Battery cell, battery and electric device

Abstract

The invention provides a battery monomer, a battery and a power utilization device. The battery cell includes a housing and a pressure relief mechanism. The housing has a first wall and a second wall disposed opposite to each other in a first direction. The housing is provided with a recess recessed relative to a surface of the second wall facing away from the first wall. The pressure relief mechanism is arranged on the first wall, and the projection of the pressure relief mechanism in the first direction is at least partially overlapped with the projection of the concave part in the first direction.

Description

Battery cells, batteries, and electrical devices Technical Field

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

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptop computers, electric vehicles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and power tools, etc.

[0003] In the development of battery technology, how to improve the reliability of battery cells is a research direction in battery technology.

[0004] Summary of the Invention

[0005] The present application provides a battery cell, a battery, and an electrical device, which can improve reliability.

[0006] In a first aspect, embodiments of the present application provide a battery cell comprising a housing and a pressure relief mechanism. The housing comprises a first wall and a second wall disposed opposite each other along a first direction. The housing comprises a recessed portion, which is recessed relative to a surface of the second wall facing away from the first wall. The pressure relief mechanism is disposed on the first wall, with a projection of the pressure relief mechanism along the first direction at least partially overlapping a projection of the recess along the first direction.

[0007] When multiple battery cells are arranged along the first direction, the recesses of the battery cells can avoid the pressure relief mechanisms of adjacent battery cells. At least part of the high-temperature and high-pressure substances released by the pressure relief mechanisms can enter the recesses and be discharged outward through the recesses, thereby reducing the battery cells' resistance to the high-temperature and high-pressure substances, enabling the battery cells to release pressure in a timely manner, improving reliability, and reducing safety risks.

[0008] In some embodiments, a projection of the pressure relief mechanism along the first direction does not overlap with a projection of the second wall along the first direction.

[0009] The second wall can avoid the pressure relief mechanism of the adjacent battery cell. When the pressure relief mechanism releases high-temperature and high-pressure substances, the second wall can avoid the high-temperature and high-pressure substances, reduce the obstruction of the high-temperature and high-pressure substances, enable the battery cell to release pressure in time, improve reliability, and reduce safety risks.

[0010] In some embodiments, a minimum distance between a projection of the pressure relief mechanism along the first direction and a projection of the second wall along the first direction is greater than or equal to 0.5 mm.

[0011] The above technical solution can reduce the risk of the second wall blocking the pressure relief mechanism of an adjacent battery cell due to assembly error when multiple battery cells are stacked along the first direction, thereby enabling the battery cells to release pressure in a timely manner, improving reliability and reducing safety risks.

[0012] In some embodiments, a projection of the pressure relief mechanism along the first direction is located within a projection of the bottom surface of the recess along the first direction.

[0013] In the first direction, the bottom surface of the recess is far away from the pressure relief mechanism of the adjacent battery cell; making the pressure relief mechanism and the bottom surface of the recess opposite to each other along the first direction can reduce the thermal shock on the shell, reduce the risk of damage to the shell under thermal shock, improve reliability, and reduce the risk of thermal runaway of multiple battery cells in succession.

[0014] In some embodiments, the recess is disposed on at least one side of the second wall in a second direction, where the second direction is perpendicular to the first direction.

[0015] The recess is provided in the end area of ​​the shell along the second direction. After the high-temperature and high-pressure material enters the recess, it can be discharged from the end of the shell along the second direction, thereby reducing the risk of high-temperature and high-pressure material gathering in the recess and improving reliability.

[0016] In some embodiments, in the second direction, a minimum distance between a projection of the pressure relief mechanism on the bottom surface of the recess and a side surface of the recess is greater than or equal to 1 mm.

[0017] The above technical solution can reduce the risk that the side of the recess will be opposite to the pressure relief mechanism of the adjacent battery cell due to assembly error when multiple battery cells are stacked along the first direction, thereby reducing the thermal shock on the side of the recess, reducing the risk of damage to the outer shell under thermal shock, improving reliability, and reducing the risk of successive thermal runaway of multiple battery cells.

[0018] In some embodiments, the first wall includes two first edges disposed opposite each other along a second direction. In the second direction, a minimum spacing between a side surface of the recess and an adjacent first edge is L1, and a maximum spacing between an end of the pressure relief mechanism away from the adjacent first edge and the first edge is L2, where L2 / L1 ≥ 0.6.

[0019] The smaller L2 is, the smaller the area of ​​the battery cell that can be used for pressure relief is; the larger L1 is, the larger the size of the recess is, the smaller the space inside the battery cell is, and the smaller the capacity of the battery cell is; the above technical solution limits L2 / L1 to greater than or equal to 0.6, which can balance the pressure relief rate and space utilization of the battery cell.

[0020] In some embodiments, the recess passes through the housing along the third direction, and the first direction, the second direction, and the third direction are perpendicular to each other.

[0021] The two ends of the recess along the third direction are open. After high-temperature and high-pressure materials enter the recess, they can be discharged from the two ends of the recess along the third direction, thereby reducing the risk of high-temperature and high-pressure materials gathering in the recess and improving reliability.

[0022] In some embodiments, the two second edges of the first wall are arranged opposite to each other along the third direction, and the first direction, the second direction and the third direction are perpendicular to each other. In the third direction, the minimum spacing S3 between the pressure relief mechanism and the second edge is 2 mm to 10 mm.

[0023] The smaller S3 is, the closer the pressure relief mechanism is to the second edge. When the second edge is subjected to an external impact, the greater the impact force transmitted to the pressure relief mechanism, the more likely it is to be damaged or fail. The larger S3 is, the smaller the size of the pressure relief mechanism in the third direction is, and the smaller the pressure relief area when the pressure relief mechanism is actuated is. In this embodiment of the application, S3 is limited to 2mm-10mm, which can reduce the risk of pressure relief mechanism failure during normal battery cell operation and minimize the loss of pressure relief area in the battery cell.

[0024] In some embodiments, the size of the housing along the second direction is greater than the size of the housing along the third direction, and the size of the housing along the third direction is greater than the size of the housing along the first direction. The first direction, the second direction, and the third direction are perpendicular to each other.

[0025] The housing has a smaller size along the first direction, and stacking battery cells in the first direction can balance the battery's dimensions, improve space utilization and energy density. The first wall has a larger area, making the location design of the pressure relief mechanism more flexible.

[0026] In some embodiments, there are two recesses, which are located on both sides of the second wall along a second direction, the second direction being perpendicular to the first direction. There are two pressure relief mechanisms, which are located at both ends of the first wall along the second direction.

[0027] The two pressure relief mechanisms increase the pressure relief rate of the battery cells and improve reliability. The two recesses can respectively avoid the two pressure relief mechanisms of adjacent battery cells, allowing both pressure relief mechanisms to smoothly release high-temperature and high-pressure materials, thereby timely releasing pressure, improving reliability, and reducing safety risks.

[0028] In some embodiments, the first wall is integrally formed with the pressure relief mechanism, and the pressure relief mechanism includes a weakened portion.

[0029] The first wall and the pressure relief mechanism are formed integrally, which not only saves the process of connecting the first wall and the pressure relief mechanism, but also improves the connection strength between the first wall and the pressure relief mechanism.

[0030] In some embodiments, the pressure relief mechanism includes a weakened portion, and a ratio of a thickness of the weakened portion to a thickness of the first wall is 0.1-0.4.

[0031] The above technical solution can reduce the risk of failure due to the breakage of the weak part when the battery cell is working normally, and can ensure that the weak part breaks open in time when the battery cell experiences thermal runaway.

[0032] In some embodiments, the first wall is provided with a groove, and the pressure relief mechanism includes a weakened portion, wherein the bottom of the groove forms the weakened portion.

[0033] The grooves can reduce the strength of the weak part, allowing it to break open in time when the battery cell experiences thermal runaway. The grooves are simple to form, and creating the weak part by creating the grooves simplifies the molding process of the pressure relief mechanism.

[0034] In some embodiments, the angle α encompassed by the weakened portion is 180°-360°.

[0035] The weak part can be a ring structure or a semi-ring structure. When the weak part ruptures, the area surrounding the weak part can be used for pressure relief. Setting α to 180°-360° can increase the pressure relief area and improve the pressure relief rate.

[0036] In some embodiments, the battery cell further includes an electrode terminal mounted on a region of the first wall surrounded by the weak portion.

[0037] When the battery cell thermally runs away, the weak part ruptures, and the area of ​​the first wall surrounded by the weak part folds or flies out under the impact of high-temperature and high-pressure materials, thereby driving the electrode terminal to move, disconnecting the electrical connection between the electrode terminal and the electrode assembly, cutting off the circuit, and slowing down the thermal runaway of the battery cell.

[0038] In some embodiments, the weak portion includes a first straight segment, a second straight segment, and an arc segment connected between the first straight segment and the second straight segment.

[0039] By providing the arc segment, a smooth transition between the first straight segment and the second straight segment can be achieved, stress concentration can be reduced, and the risk of rupture and failure of the weak portion during normal operation of the battery cell can be reduced.

[0040] In some embodiments, the minimum distance between the arc segment and the edge of the first wall is D1, the minimum distance between the first straight segment and the edge of the first wall is D2, and D1 ≥ D2.

[0041] Compared with the first straight segment, the arc segment is more susceptible to damage when subjected to impact force; in the embodiment of the present application, D1 is set to be greater than or equal to D2, so that there is a larger distance between the arc segment and the edge of the first wall, thereby reducing the risk of the arc segment breaking or failing when the edge of the first wall is subjected to external impact.

[0042] In some embodiments, a minimum distance between the second straight line segment and the edge of the first wall is D3, and D1 ≥ D3.

[0043] Compared with the second straight segment, the arc segment is more susceptible to damage when subjected to impact force; in the embodiment of the present application, D1 is set to be greater than or equal to D3, so that there is a larger distance between the arc segment and the edge of the first wall, thereby reducing the risk of the arc segment breaking or failing when the edge of the first wall is subjected to external impact.

[0044] In some embodiments, the first wall includes a first edge extending along a third direction, a second edge extending along a second direction, and an arcuate edge connecting the first edge and the second edge. The first direction, the second direction, and the third direction are perpendicular to each other. The first straight line segment is parallel to the first edge, the second straight line segment is parallel to the second edge, and the arcuate segment is opposite to the arcuate edge. The minimum spacing between the arcuate segment and the arcuate edge is greater than or equal to the spacing between the first straight line segment and the first edge.

[0045] The arc edge is located at the corner of the shell and is more susceptible to external impact. The above technical solution creates a larger distance between the arc segment and the arc edge, thereby reducing the risk of the arc segment breaking or failing when the arc edge is subjected to external impact, thereby improving reliability.

[0046] In some embodiments, there are two first straight line segments, the two first straight line segments are spaced apart along the second direction, and both ends of the second straight line segment along the second direction are respectively connected to the two first straight line segments through two arc segments.

[0047] In the above technical solution, the weak portion is substantially enclosed into a rectangular area. When the battery cell experiences thermal runaway, the weak portion ruptures, and a substantially rectangular pressure relief port is formed on the outer shell of the battery cell, thereby releasing pressure in time.

[0048] In some embodiments, the weak portion is annular and includes two first straight segments, two second straight segments and four arc segments. In the circumferential direction of the weak portion, adjacent first straight segments and second straight segments are connected by the arc segments.

[0049] When the battery cell experiences thermal runaway, the weak portion ruptures, and the portion of the first wall surrounded by the weak portion separates from the battery cell, thereby reducing the obstruction to high-temperature and high-pressure materials and releasing pressure in a timely manner.

[0050] In some embodiments, the housing includes a shell and an end cap. The shell has an opening, and the end cap is used to cover the opening. The end cap is a first wall, and the shell includes a second wall. The end cap is welded to the shell to form a welded portion. Welding provides high connection strength and is simple and easy to implement.

[0051] In some embodiments, the pressure relief mechanism includes a weakened portion, the welded portion surrounds the weakened portion, and the minimum spacing between the weakened portion and the welded portion is 0.5 mm to 5 mm.

[0052] When welding the shell and end cap, the heat generated by welding is transferred to the weak part, causing the weak part to be affected by thermal stress. The above technical solution can reduce the thermal stress transferred to the weak part, reducing the risk of premature rupture and failure of the weak part.

[0053] In some embodiments, the weak portion includes a first straight segment, a second straight segment, and an arc segment connected between the first straight segment and the second straight segment. The minimum distance between the arc segment and the weld portion is D4, and the minimum distance between the first straight segment and the weld portion is D5, where D4≥D5.

[0054] Compared with the first straight segment, the arc segment is more prone to fatigue damage under the action of thermal stress; in the embodiment of the present application, D4 is set to be greater than or equal to D5, so that there is a larger distance between the arc segment and the welding part, thereby reducing the risk of the arc segment breaking or failing under thermal stress.

[0055] In some embodiments, the minimum distance between the second straight line segment and the welding portion is D6, and D4≥D6.

[0056] Compared with the second straight segment, the arc segment is more prone to fatigue damage under the action of thermal stress; in the embodiment of the present application, D4 is set to be greater than or equal to D6, so that there is a larger distance between the arc segment and the welding part, thereby reducing the risk of the arc segment breaking and failing under thermal stress.

[0057] In some embodiments, the weld portion includes a first weld segment extending along a third direction, a second weld segment extending along a second direction, and an arcuate weld segment connecting the first weld segment and the second weld segment. The first, second, and third directions are perpendicular to each other. The first straight segment is parallel to the first weld segment, the second straight segment is parallel to the second weld segment, and the arcuate segments are opposite to the arcuate weld segments. The minimum spacing between the arcuate weld segments is greater than or equal to the minimum spacing between the first straight segment and the first weld segment.

[0058] The arc segment is more prone to fatigue damage under the action of thermal stress; the embodiment of the present application allows a larger distance between the arc segment and the arc welding segment, thereby reducing the risk of the arc segment breaking and failing under thermal stress.

[0059] In some embodiments, D4 is 1 mm-4 mm, optionally, D4 is 2 mm-3 mm.

[0060] The above technical solution can create a larger distance between the arc segment and the welding portion, thereby reducing the risk of the arc segment breaking or failing under thermal stress.

[0061] In some embodiments, D5 is 0.8 mm to 4 mm, optionally, D5 is 1 mm to 2.5 mm.

[0062] The above technical solution can create a larger distance between the first straight line segment and the welding portion, thereby reducing the risk of the first straight line segment breaking or failing under thermal stress.

[0063] In some embodiments, the pressure relief mechanism includes a weak portion; the thickness of the weak portion is T1, the penetration depth of the weld is T2, and T1 and T2 satisfy: 0.05≤T1 / T2≤0.3.

[0064] The above technical solution can cause the weak part to rupture before the weld part when the battery cell is in thermal runaway, thereby achieving directional pressure relief of the battery cell, reducing the risk of separation between the shell and the end cover, and ensuring that the strength of the weak part meets the design requirements, reducing the risk of the weak part rupturing when the battery cell is working normally.

[0065] In a second aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells provided in any embodiment of the second aspect. The plurality of battery cells are arranged along a first direction. In the first direction, the pressure relief mechanism is opposite to the recessed portions of adjacent battery cells.

[0066] In a third aspect, an embodiment of the present application provides an electrical device, comprising a battery cell provided by any embodiment of the second aspect, wherein the battery cell is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0068] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0069] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application;

[0070] FIG3 is a schematic diagram of a battery provided in some embodiments of the present application;

[0071] FIG4 is a front view schematic diagram of a battery cell provided in some embodiments of the present application;

[0072] FIG5 is a schematic side view of a battery cell provided in some embodiments of the present application;

[0073] FIG6 is an enlarged schematic diagram of block A in FIG4 ;

[0074] FIG7 is an enlarged schematic diagram of FIG6 at block B;

[0075] FIG8 is a schematic cross-sectional view taken along line CC in FIG6 ;

[0076] FIG9 is an enlarged schematic diagram of block D in FIG8 ;

[0077] FIG10 is an enlarged schematic diagram of FIG9 at the circle E;

[0078] FIG11 is a simplified schematic diagram of a weak portion of a pressure relief mechanism of a battery cell provided in some embodiments of the present application;

[0079] FIG12 is a simplified schematic diagram of a weak portion of a pressure relief mechanism of a battery cell provided in other embodiments of the present application;

[0080] FIG13 is an enlarged schematic diagram of the battery shown in FIG3 at the circle F. FIG.

[0081] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] The term "plurality" used in this application refers to two or more (including two).

[0089] In the embodiments of the present application, "parallel" includes not only the absolutely parallel situation, but also the roughly parallel situation conventionally recognized in engineering; at the same time, "vertical" includes not only the absolutely vertical situation, but also the roughly vertical situation conventionally recognized in engineering.

[0090] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0091] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may be a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0092] A battery cell comprises an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet comprises a positive current collector and a positive active material layer, which is coated on the surface of the positive electrode collector. The positive electrode collector comprises a positive current collector portion and a positive tab, which is coated with the positive active material layer, while the positive tab is uncoated. For example, in a lithium-ion battery cell, the positive current collector can be made of aluminum, and the positive active material layer comprises a positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet comprises a negative current collector and a negative active material layer, which is coated on the surface of the negative electrode collector. The negative electrode collector comprises a negative current collector portion and a negative tab, which is coated with the negative active material layer, while the negative tab is uncoated. The negative electrode current collector may be made of copper, and the negative electrode active material layer includes a negative electrode active material, which may be carbon or silicon, etc. The separator may be made of PP (polypropylene) or PE (polyethylene), etc.

[0093] The battery cell may further include a housing having a receiving cavity in which the electrode assembly and the electrolyte are received. The housing protects the electrode assembly and reduces the risk of foreign matter affecting the electrode assembly.

[0094] 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, battery reliability must also be considered.

[0095] The pressure relief mechanism on a battery cell has a significant impact on its reliability. For example, short circuits and overcharging can cause thermal runaway within the cell, leading to a sudden increase in pressure. In these situations, the pressure relief mechanism activates to release the internal pressure, preventing explosion or fire.

[0096] A pressure relief mechanism is a component or element that activates to release internal pressure when the internal pressure of a battery cell reaches a predetermined threshold. This threshold varies depending on the design requirements. It may depend on the materials of one or more of the positive and negative electrode plates, electrolyte, and separator in the battery cell.

[0097] The pressure relief mechanism may take the form of an explosion-proof valve, an air valve, a pressure relief valve, or a safety valve, and may specifically employ a pressure-sensitive element or structure. Specifically, when the internal pressure of the battery cell reaches a predetermined threshold, the pressure relief mechanism actuates, or a weak area within the pressure relief mechanism ruptures, thereby forming an opening or passage through which the internal pressure can be released. Alternatively, the pressure relief mechanism may employ a temperature-sensitive element or structure. Specifically, when the internal temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism actuates, thereby forming an opening or passage through which the internal pressure can be released.

[0098] The "activation" mentioned in this application refers to the action of the pressure relief mechanism or its activation to a certain state, thereby allowing the internal pressure of the battery cell to be released. The action produced by the pressure relief mechanism may include, but is not limited to: at least a portion of the pressure relief mechanism is ruptured, broken, torn or opened, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged outward from the actuated part as emissions. In this way, the pressure of the battery cell can be relieved under controllable pressure, thereby avoiding potential more serious accidents.

[0099] The emissions from the battery cells mentioned in this application include but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0100] In related technologies, multiple battery cells of a battery are usually arranged in sequence; a battery cell may block the pressure relief mechanism of the battery cell adjacent to it; when the pressure relief mechanism releases pressure, the discharge is blocked by the battery cell, resulting in low pressure relief efficiency and causing safety hazards.

[0101] In view of this, an embodiment of the present application provides a technical solution, which provides a recess on the outer shell of the battery cell to avoid the pressure relief mechanism of the adjacent battery cell, reduce the obstruction to the high-temperature and high-pressure materials released by the pressure relief mechanism, enable the battery cell to release pressure in time, and improve reliability.

[0102] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0103] 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.

[0104] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0105] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0106] As shown in FIG1 , a battery 2 is provided inside the vehicle 1. The battery 2 may be provided at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1. For example, the battery 2 may serve as an operating power source for the vehicle 1.

[0107] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0108] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0109] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application.

[0110] As shown in FIG. 2 , the battery 2 includes a case 5 and battery cells 6 (not shown). The battery cells 6 are accommodated in the case 5 .

[0111] The housing 5 is used to accommodate the battery cells 6 and can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b overlap each other and together define a storage space 5c for accommodating the battery cells 6. The second housing portion 5b can be a hollow structure with one end open. The first housing portion 5a is a plate-like structure, and the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. The first housing portion 5a and the second housing portion 5b can also both be hollow structures with one end open. The open side of the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0112] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0113] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0114] In the battery 2, there can be one or more battery cells 6. If there are multiple battery cells 6, the multiple battery cells 6 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections within the multiple battery cells 6. The multiple battery cells 6 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 6 can be housed within the housing 5. Alternatively, multiple battery cells 6 can be first connected in series, in parallel, or in a hybrid connection to form a battery module, and then the multiple battery modules can be connected in series, in parallel, or in a hybrid connection to form a single unit and housed within the housing 5.

[0115] Figure 3 is a schematic diagram of a battery provided in some embodiments of the present application; Figure 4 is a schematic front view of a battery cell provided in some embodiments of the present application; Figure 5 is a schematic side view of a battery cell provided in some embodiments of the present application; Figure 6 is an enlarged schematic diagram of box A in Figure 4; Figure 7 is an enlarged schematic diagram of box B in Figure 6; and Figure 8 is a schematic cross-sectional view taken along line CC in Figure 6.

[0116] Referring to Figures 3 to 8 , the battery cell 6 of the present embodiment includes a housing 20 and a pressure relief mechanism 10. The housing 20 has a first wall 21 and a second wall 22 disposed opposite each other along a first direction X. The housing 20 is provided with a recess 23, which is recessed relative to the surface of the second wall 22, facing away from the first wall 21. The pressure relief mechanism 10 is disposed on the first wall 21, with the projection of the pressure relief mechanism 10 along the first direction X at least partially overlapping with the projection of the recess 23 along the first direction X.

[0117] The housing 20 is a hollow structure, forming a cavity within it. For example, the cavity can be used to accommodate the electrode assembly of the battery cell 6. The shape of the housing 20 can be determined based on the specific shape of the electrode assembly. For example, if the electrode assembly is a rectangular parallelepiped structure, a rectangular housing can be selected; if the electrode assembly is a cylindrical structure, a cylindrical housing can be selected.

[0118] The material of the housing 20 can be various, for example, the material of the housing 20 can be metal or plastic. Alternatively, the material of the housing 20 can be copper, iron, aluminum, steel, aluminum alloy, etc.

[0119] The first wall 21 is a wall of the housing 20 having a certain thickness. It can be the top wall, the bottom wall, or the side wall of the housing 20, and this embodiment of the present application is not limited thereto. The second wall 22 is also a wall of the housing 20 having a certain thickness. The first wall 21 and the second wall 22 are spaced apart in the first direction X.

[0120] The embodiment of the present application does not limit the shape of the first wall 21 and the shape of the second wall 22. For example, the first wall 21 can be a flat structure, a curved structure, or other structures. The second wall 22 can be a flat structure, a curved structure, or other structures.

[0121] The embodiment of the present application does not limit the position and number of the recess 23. For example, there can be one recess 23 or more.

[0122] The recess 23 is recessed relative to the surface of the second wall 22 facing away from the first wall 21 toward the first wall 21. For example, in the first direction X, the bottom surface 231 of the recess is closer to the first wall 21 than the second wall 22.

[0123] The embodiments of the present application do not limit the molding method of the pressure relief mechanism 10 and the first wall 21. In some examples, the pressure relief mechanism 10 and the first wall 21 are independently molded components, and the two can be connected by welding, bonding, or other methods. For example, the first wall 21 is provided with a pressure relief hole that passes through the first wall 21. The pressure relief mechanism 10 is mounted on the first wall 21 and covers the pressure relief hole, thereby separating the space inside and outside the first wall 21. In alternative embodiments, the pressure relief mechanism 10 and the first wall 21 can also be an integrally molded structure.

[0124] In some examples, a portion of the projection of the pressure relief mechanism 10 along the first direction X is located within the projection of the recess 23 along the first direction X. In other examples, the entire projection of the pressure relief mechanism 10 along the first direction X is located within the projection of the recess 23 along the first direction X.

[0125] In the embodiment of the present application, when multiple battery cells 6 are arranged along the first direction X, the recess 23 of a battery cell 6 can avoid the pressure relief mechanism 10 of the adjacent battery cell 6. At least part of the high-temperature and high-pressure material released by the pressure relief mechanism 10 can enter the recess 23 and be discharged outward through the recess 23, thereby reducing the barrier of the battery cell 6 to the high-temperature and high-pressure material, allowing the battery cell 6 to release pressure in a timely manner, improving reliability, and reducing safety risks.

[0126] In some embodiments, the battery cell 6 includes an electrode assembly (not shown) housed within the housing 20 .

[0127] The electrode assembly includes a first electrode sheet and a second electrode sheet of opposite polarity. One of the first electrode sheet and the second electrode sheet is a positive electrode sheet, and the other is a negative electrode sheet. Exemplarily, the electrode assembly generates electrical energy through oxidation and reduction reactions when ions are inserted into and extracted from the positive and negative electrode sheets.

[0128] Optionally, the electrode assembly further includes an isolating member, which is used to insulate and isolate the first electrode piece from the second electrode piece.

[0129] The electrode assembly may be a wound structure formed by winding the first electrode sheet, the separator, and the second electrode sheet, or a laminated structure formed by stacking the first electrode sheet, the separator, and the second electrode sheet.

[0130] There may be one electrode assembly or multiple electrode assemblies. When there are multiple electrode assemblies, the multiple electrode assemblies may be stacked. For example, the multiple electrode assemblies may be stacked along the first direction X.

[0131] In some embodiments, the housing 20 includes a shell 20 a and an end cover 20 b . The shell 20 a has an opening, and the end cover 20 b is used to cover the opening.

[0132] The housing 20 a is a component used to cooperate with the end cover 20 b to form an internal cavity of the battery cell 6 . The formed internal cavity can be used to accommodate an electrode assembly, an electrolyte, and other components.

[0133] The housing 20a and the end cap 20b may be separate components. For example, an opening may be provided on the housing 20a, and the end cap 20b may be placed over the opening to form an internal cavity of the battery cell 6.

[0134] The housing 20a can have various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 20a can be determined based on the specific shape and size of the electrode assembly. The housing 20a can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0135] The shape of the end cap 20b can be adapted to the shape of the housing 20a to fit the housing 20a. Optionally, the end cap 20b can be made of a material with a certain hardness and strength (such as an aluminum alloy). In this way, the end cap 20b is less likely to deform when squeezed or collided, thereby providing the battery cell 6 with higher structural strength and improved reliability.

[0136] The housing 20a may be open on one side, with the end cap 20b provided to cover the opening of the housing 20a. In some examples, one of the first wall 21 and the second wall 22 is the end cap 20b, and the other is the bottom wall of the housing 20a opposite the end cap 20b. In other examples, the first wall 21 and the second wall 22 are two opposing side walls of the housing 20a.

[0137] Alternatively, the housing 20a may be open on both sides, with two end caps 20b provided, each of which covers the two openings of the housing 20a. In some examples, the first wall 21 and the second wall 22 are the two end caps 20b; in other examples, the first wall 21 and the second wall 22 are the two opposing side walls of the housing 20a.

[0138] The end cover 20b is connected to the housing 20a by welding, bonding, clamping or other means.

[0139] In some embodiments, the size of the housing 20 along the second direction Y is greater than the size of the housing 20 along the third direction Z. The size of the housing 20 along the third direction Z is greater than the size of the housing 20 along the first direction X. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0140] The size of the housing 20 along the first direction X is relatively small. Stacking the battery cells 6 in the first direction X can balance the external dimensions of the battery and improve space utilization and energy density.

[0141] The first wall 21 has a larger area, which allows for more flexible design of the position of the pressure relief mechanism 10 .

[0142] In some embodiments, a projection of the pressure relief mechanism 10 along the first direction X does not overlap with a projection of the second wall 22 along the first direction X.

[0143] In the embodiment of the present application, the second wall 22 can avoid the pressure relief mechanism 10 of the adjacent battery cell 6. When the pressure relief mechanism 10 releases high-temperature and high-pressure substances, the second wall 22 can avoid the high-temperature and high-pressure substances, reduce the obstruction of the high-temperature and high-pressure substances, and enable the battery cell 6 to release pressure in time, thereby improving reliability and reducing safety risks.

[0144] In some embodiments, a minimum distance S1 between a projection of the pressure relief mechanism 10 along the first direction X and a projection of the second wall 22 along the first direction X is greater than or equal to 0.5 mm.

[0145] The embodiment of the present application can reduce the risk of the second wall 22 blocking the pressure relief mechanism 10 of an adjacent battery cell 6 due to assembly error when multiple battery cells 6 are stacked along the first direction X, thereby enabling the battery cells 6 to release pressure in a timely manner, improving reliability, and reducing safety risks.

[0146] Optionally, S1 is 0.5 mm, 1 mm, 2 mm or 5 mm.

[0147] In some embodiments, a projection of the pressure relief mechanism 10 along the first direction X is located within a projection of the recess 23 along the first direction X.

[0148] The projection of the recess 23 along the first direction X includes a projection of a bottom surface 231 of the recess along the first direction X and a projection of a side surface 232 of the recess along the first direction X.

[0149] In some embodiments, a projection of the pressure relief mechanism 10 along the first direction X is located within a projection of the bottom surface 231 of the recess along the first direction X.

[0150] In the first direction X, the bottom surface 231 of the recess is far away from the pressure relief mechanism 10 of the adjacent battery cell 6; in the embodiment of the present application, the pressure relief mechanism 10 and the bottom surface 231 of the recess are opposite to each other along the first direction X, which can reduce the thermal shock on the shell 20, reduce the risk of damage to the shell 20 under thermal shock, improve reliability, and reduce the risk of thermal runaway of multiple battery cells 6.

[0151] In some embodiments, in the second direction Y, a minimum distance S2 between a projection of the pressure relief mechanism 10 on the bottom surface 231 of the recess and a side surface 232 of the recess is greater than or equal to 1 mm.

[0152] The embodiment of the present application can reduce the risk that the side surface 232 of the recessed portion will be opposite to the pressure relief mechanism 10 of the adjacent battery cell 6 due to assembly error when multiple battery cells 6 are stacked along the first direction X, thereby reducing the thermal shock to the side surface 232 of the recessed portion, reducing the risk of damage to the outer shell 20 under thermal shock, improving reliability, and reducing the risk of successive thermal runaway of multiple battery cells 6.

[0153] In some embodiments, S2 is ≥ 2 mm. Optionally, S2 is 2 mm, 3 mm, or 5 mm.

[0154] In some embodiments, the recess 23 is disposed on at least one side of the second wall 22 in the second direction Y, where the second direction Y is perpendicular to the first direction X.

[0155] The housing 20 may be provided with a recess 23 on one side of the second wall 22 along the second direction Y, or may be provided with recesses 23 on both sides of the second wall 22 along the second direction Y.

[0156] The recess 23 is provided in the end area of ​​the shell 20 along the second direction Y. After the high-temperature and high-pressure material enters the recess 23, it can be discharged from the end of the shell 20 along the second direction Y, thereby reducing the risk of high-temperature and high-pressure material gathering in the recess 23 and improving reliability.

[0157] In some embodiments, a third wall 24 is provided at an end of the housing 20 along the second direction Y, and the recess 23 extends to the third wall 24 along the second direction Y. In other words, in the second direction Y, the recess 23 is recessed relative to the third wall 24 .

[0158] In some embodiments, the recess 23 passes through the housing 20 along the third direction Z, and the first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0159] The recess 23 is open at both ends along the third direction Z. After high-temperature and high-pressure materials enter the recess 23, they can be discharged from both ends along the third direction Z, thereby reducing the risk of high-temperature and high-pressure materials gathering in the recess 23 and improving reliability.

[0160] In some embodiments, two recesses 23 are provided, and the two recesses 23 are respectively located on both sides of the second wall 22 along the second direction Y, where the second direction Y is perpendicular to the first direction X.

[0161] Both recesses 23 can be used to avoid the pressure relief mechanisms 10 of adjacent battery cells 6 , which can make the arrangement of the battery cells 6 more flexible and facilitate the connection of multiple battery cells 6 into groups.

[0162] In some embodiments, there are two pressure relief mechanisms 10 , which are disposed at both ends of the first wall 21 along the second direction Y.

[0163] The two pressure relief mechanisms 10 increase the pressure relief rate of the battery cells 6 and improve reliability. The two recesses 23 can respectively avoid the two pressure relief mechanisms 10 of adjacent battery cells 6, allowing the two pressure relief mechanisms 10 to smoothly release high-temperature and high-pressure materials, thereby timely releasing pressure, improving reliability, and reducing safety risks.

[0164] In some embodiments, the first wall 21 is integrally formed with the pressure relief mechanism 10 , and the pressure relief mechanism 10 includes a weakened portion 10 a .

[0165] The strength of the weak portion 10 a is lower than the strength of the first wall 21 , and the weak portion 10 a is a portion that is easily broken, shattered, torn, or opened.

[0166] In some examples, grooves, notches, or other structures may be provided in a predetermined region of the first wall 21 to reduce the local strength of the first wall 21, thereby forming a weak portion 10a on the first wall 21. For example, a thinning process may be performed on the predetermined region of the first wall 21, and the thinned portion of the first wall 21 forms the weak portion 10a. In other examples, a material treatment may be performed on the predetermined region of the first wall 21 to make the strength of the region weaker than that of other regions. In other words, the region serves as the weak portion 10a.

[0167] The entire pressure relief mechanism 10 may be a weak portion 10 a , or only a partial area thereof may be a weak portion 10 a .

[0168] The first wall 21 and the pressure relief mechanism 10 are formed integrally, which not only saves the process of connecting the first wall 21 and the pressure relief mechanism 10 , but also improves the connection strength between the first wall 21 and the pressure relief mechanism 10 .

[0169] In some embodiments, the pressure relief mechanism 10 includes a weak portion 10 a , and a ratio of a thickness T1 of the weak portion 10 a to a thickness T3 of the first wall 21 is 0.1-0.4.

[0170] In the embodiment of the present application, the value of T1 / T3 is limited to 0.1-0.4, which can reduce the risk of the weak portion 10a breaking and failing when the battery cell 6 is working normally, and ensure that the weak portion 10a breaks in time when the battery cell 6 experiences thermal runaway.

[0171] For example, if T1 / T3 is too small, for example, less than 0.1, the strength of the weak portion 10a is too low. When the battery cell 6 is subjected to shock such as vibration, the weak portion 10a may be at risk of fatigue fracture, causing the pressure relief mechanism 10 to fail and posing a safety hazard. If T1 / T3 is too large, for example, less than 0.4, the strength of the weak portion 10a is too high. When the battery cell 6 experiences thermal runaway, the pressure required to break the weak portion 10a is too high, resulting in the risk of delayed breaking of the weak portion 10a.

[0172] In some embodiments, T1 / T3 is 0.1, 0.2, 0.3, or 0.4.

[0173] In some embodiments, the first wall 21 is provided with a groove 21a, and the pressure relief mechanism 10 includes a weak portion 10a. The bottom of the groove 21a forms the weak portion 10a. In other words, the weak portion 10a corresponds to the bottom surface of the groove 21a.

[0174] The groove 21a can reduce the strength of the weak portion 10a, so that the weak portion 10a can be broken in time when the battery cell 6 experiences thermal runaway. The groove 21a is formed in a simple manner. By forming the weak portion 10a by forming the groove 21a, the molding process of the pressure relief mechanism 10 can be simplified.

[0175] In some embodiments, the angle α encompassed by the weakened portion 10a is 180°-360°.

[0176] The weak portion 10a may be annular or semi-annular.

[0177] In some examples, the weak portion 10a is annular, that is, α is 360°.

[0178] In other examples, the weak portion 10a is semi-circular, and α is the central angle between the two ends of the weak portion 10a on the circumscribed circle of the weak portion 10a.

[0179] Exemplarily, α is 180°, 210°, 240°, 270°, 300°, 330° or 360°.

[0180] In an embodiment of the present application, the weak portion 10a may be a ring structure or a semi-ring structure. When the weak portion 10a ruptures, the area surrounded by the weak portion 10a can be used for pressure relief; setting α to 180°-360° can increase the pressure relief area and improve the pressure relief rate.

[0181] In some embodiments, the battery cell 6 further includes an electrode terminal 30 , which is mounted on a region of the first wall 21 surrounded by the weak portion 10 a .

[0182] The electrode terminal 30 can be used to electrically connect the electrode assembly to a circuit outside the battery cell 6 to enable charging and discharging of the electrode assembly.

[0183] When the battery cell 6 thermally runs away, the weak portion 10a ruptures, and the area of ​​the first wall 21 surrounded by the weak portion 10a folds or flies out under the impact of the high-temperature and high-pressure material, thereby driving the electrode terminal 30 to move, disconnecting the electrical connection between the electrode terminal 30 and the electrode assembly, cutting off the circuit, and slowing down the thermal runaway of the battery cell 6.

[0184] In some embodiments, the first wall 21 includes two first edges 211 disposed opposite each other along the second direction Y. In the second direction Y, the minimum distance between the side surface 232 of the recess and the adjacent first edge 211 is L1, and the maximum distance between the end of the pressure relief mechanism 10 away from the adjacent first edge 211 and the first edge 211 is L2, where L2 / L1 ≥ 0.6.

[0185] In the second direction Y, the distance between the recess 23 and one first edge 211 is greater than the distance between the recess 23 and another first edge 211. The first edge 211 adjacent to the recess 23 is the first edge 211 with a smaller distance from the recess 23. L1 may be the minimum distance between the first edge 211 adjacent to the recess 23 and the side surface 232 of the recess in the second direction Y.

[0186] In the second direction Y, the distance between the pressure relief mechanism 10 and one first edge 211 is greater than the distance between the pressure relief mechanism 10 and another first edge 211. The first edge 211 adjacent to the pressure relief mechanism 10 is the first edge 211 that is closer to the pressure relief mechanism 10. L2 may be the maximum distance in the second direction Y between the first edge 211 adjacent to the pressure relief mechanism 10 and the end of the pressure relief mechanism 10 away from the first edge 211.

[0187] In the embodiment of the present application, L2 / L1 is limited to be greater than or equal to 0.6, which can balance the pressure release rate and space utilization of the battery cell 6.

[0188] For example, the smaller L2 / L1 is, the smaller L2 is or the larger L1 is. The smaller L2 is, the smaller the area of ​​the battery cell 6 that can be used for pressure relief is; if L2 is too small, the pressure relief rate of the battery cell 6 will be insufficient. The larger L1 is, the larger the size of the recess 23 is, the smaller the space inside the battery cell 6 is, and the smaller the capacity of the battery cell 6 is; if L1 is too large, the space utilization and energy density of the battery cell 6 will be low. In this embodiment of the application, L2 / L1 is limited to greater than or equal to 0.6 to balance the pressure relief rate and space utilization of the battery cell 6.

[0189] Optionally, L2 / L1 is 0.6, 0.7, 0.8 or 0.9.

[0190] In some embodiments, L2 / L1 ≥ 0.8.

[0191] In some embodiments, the two second edges 212 of the first wall 21 are oppositely arranged along the third direction Z, and the first direction X, the second direction Y, and the third direction Z are perpendicular to each other. In the third direction Z, the minimum distance S3 between the pressure relief mechanism 10 and the second edge 212 is 2 mm to 10 mm.

[0192] The embodiment of the present application can reduce the risk of failure of the pressure relief mechanism 10 when the battery cell 6 is operating normally, and reduce the loss of the pressure relief area of ​​the battery cell 6 .

[0193] For example, the smaller S3 is, the closer the pressure relief mechanism 10 is to the second edge 212; when the second edge 212 is subjected to an external impact, the greater the impact force transmitted to the pressure relief mechanism 10, and the more likely the pressure relief mechanism 10 is to be damaged or fail. The larger S3 is, the smaller the size of the pressure relief mechanism 10 in the third direction Z is, and the smaller the pressure relief area when the pressure relief mechanism 10 is actuated is. In this embodiment of the application, S3 is limited to 2mm-10mm, which can reduce the risk of failure of the pressure relief mechanism 10 during normal operation of the battery cell 6 and reduce the loss of pressure relief area of ​​the battery cell 6.

[0194] Optionally, S3 is 2 mm, 3 mm, 5 mm, 8 mm or 10 mm.

[0195] In some embodiments, the weak portion 10 a includes a first straight segment 11 , a second straight segment 12 , and an arc segment 13 connected between the first straight segment 11 and the second straight segment 12 .

[0196] The present application does not limit the number of the first straight segments 11 , the number of the second straight segments 12 , and the number of the arc segments 13 .

[0197] The arc segment 13 can be provided to achieve a smooth transition between the first straight segment 11 and the second straight segment 12 , thereby reducing stress concentration and lowering the risk of the weak portion 10 a being broken or failing when the battery cell 6 is operating normally.

[0198] In some embodiments, the minimum distance between the arc segment 13 and the edge of the first wall 21 is D1, and the minimum distance between the first straight segment 11 and the edge of the first wall 21 is D2, where D1≥D2.

[0199] The edges of the first wall 21 include two first edges 211 and two second edges 212 .

[0200] Exemplarily, D1 can be: the minimum distance between the projection of the arc segment 13 along the first direction X and the projection of the edge of the first wall 21 along the first direction X; D2 can be: the minimum distance between the projection of the first straight line segment 11 along the first direction X and the projection of the edge of the first wall 21 along the first direction X.

[0201] Compared with the first straight segment 11, the arc segment 13 is more susceptible to damage when subjected to impact force; in the embodiment of the present application, D1 is set to be greater than or equal to D2, so that there is a larger distance between the arc segment 13 and the edge of the first wall 21, thereby reducing the risk of the arc segment 13 breaking or failing when the edge of the first wall 21 is subjected to external impact.

[0202] In some embodiments, D1 > D2.

[0203] In some embodiments, the minimum distance between the second straight segment 12 and the edge of the first wall 21 is D3, and D1 ≥ D3.

[0204] D3 may be: a minimum distance between a projection of the second straight line segment 12 along the first direction X and a projection of an edge of the first wall 21 along the first direction X. Optionally, D3 is equal to S3.

[0205] Compared with the second straight segment 12, the arc segment 13 is more susceptible to damage when subjected to impact force; in the embodiment of the present application, D1 is set to be greater than or equal to D3, so that there is a larger distance between the arc segment 13 and the edge of the first wall 21, thereby reducing the risk of the arc segment 13 breaking or failing when the edge of the first wall 21 is subjected to external impact.

[0206] In some embodiments, the first wall 21 includes a first edge 211 extending along a third direction Z, a second edge 212 extending along a second direction Y, and an arcuate edge 213 connecting the first edge 211 and the second edge 212. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other. The first straight segment 11 is parallel to the first edge 211, the second straight segment 12 is parallel to the second edge 212, and the arcuate segment 13 is opposite to the arcuate edge 213. The minimum distance between the arcuate segment 13 and the arcuate edge 213 is greater than or equal to the distance between the first straight segment 11 and the first edge 211.

[0207] The arcuate edge 213 is located at the corner of the housing 20 and is more susceptible to external impacts. The embodiment of the present application provides a larger distance between the arcuate segment 13 and the arcuate edge 213, thereby reducing the risk of the arcuate segment 13 breaking or failing when the arcuate edge 213 is subjected to external impacts, thereby improving reliability.

[0208] In some embodiments, the minimum distance between the arc segment 13 and the arc edge 213 is greater than or equal to the distance between the second straight segment 12 and the second edge 212 .

[0209] For example, the minimum distance between the projection of the arc segment 13 along the first direction X and the projection of the arc edge 213 along the first direction X may be D1; in the second direction Y, the distance between the first straight line segment 11 and the first edge 211 may be D2; in the third direction Z, the distance between the second straight line segment 12 and the second edge 212 may be D3.

[0210] In some embodiments, a length of the first edge 211 extending along the third direction Z is smaller than a length of the second edge 212 extending along the second direction Y.

[0211] FIG9 is an enlarged schematic diagram of the square frame D in FIG8 ; FIG10 is an enlarged schematic diagram of the circular frame E in FIG9 .

[0212] Referring to Figures 6 to 10 , in some embodiments, the housing 20 includes a shell 20a and an end cap 20b. The shell 20a has an opening, and the end cap 20b is used to cover the opening. The end cap 20b is a first wall 21, and the shell 20a includes a second wall 22. The end cap 20b is welded to the shell 20a to form a weld 25.

[0213] The welding connection has high strength, simple process and is easy to implement.

[0214] In some embodiments, the pressure relief mechanism 10 includes a weak portion 10a, a weld portion 25 surrounds the weak portion 10a, and a minimum spacing S4 between the weak portion 10a and the weld portion 25 is 0.5 mm to 5 mm.

[0215] When welding the housing 20a and the end cap 20b, the heat generated by the welding is transferred to the weak portion 10a, causing the weak portion 10a to be affected by thermal stress. The embodiment of the present application can reduce the thermal stress transferred to the weak portion 10a, reducing the risk of premature rupture and failure of the weak portion 10a.

[0216] For example, the smaller S4 is, the greater the thermal stress on the weak portion 10a is, and the more likely the weak portion 10a is to rupture and fail prematurely; if S4 is too small, then when the battery cell 6 is in normal working condition, the weak portion 10a may also rupture due to changes in internal pressure, causing the pressure relief mechanism 10 to fail.

[0217] During the charge and discharge process of the battery cell 6, pressure changes will occur inside the battery cell 6; when the internal pressure of the battery cell 6 increases, the first wall 21 may bulge and deform; when the internal pressure of the battery cell 6 decreases, the first wall 21 may shrink and deform. In other words, as the internal pressure of the battery cell 6 changes, the first wall 21 will deform multiple times; and the closer to the center of the first wall 21, the greater the deformation of the first wall 21. Correspondingly, the larger S4 is, the closer the weak portion 10a is to the center of the first wall 21, and the easier it is for the weak portion 10a to fatigue as the first wall 21 deforms. If S4 is too large, the weak portion 10a may rupture when the battery cell 6 is operating normally, causing the pressure relief mechanism 10 to fail. The embodiment of the present application limits S4 to 0.5mm-5mm to reduce the risk of premature rupture and failure of the weak portion 10a.

[0218] Optionally, S4 is 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm.

[0219] In some embodiments, the weakened portion 10a includes a first straight segment 11, a second straight segment 12, and an arcuate segment 13 connecting the first straight segment 11 and the second straight segment 12. The minimum distance between the arcuate segment 13 and the welded portion 25 is D4, and the minimum distance between the first straight segment 11 and the welded portion 25 is D5, where D4 ≥ D5.

[0220] Exemplarily, D4 can be: the minimum distance between the projection of the arc segment 13 along the first direction X and the projection of the welding portion 25 along the first direction X; D5 can be: the minimum distance between the projection of the first straight line segment 11 along the first direction X and the projection of the welding portion 25 along the first direction X.

[0221] Compared with the first straight segment 11, the arc segment 13 is more susceptible to fatigue damage under the action of thermal stress; in the embodiment of the present application, D4 is set to be greater than or equal to D5, so that there is a larger distance between the arc segment 13 and the welding portion 25, thereby reducing the risk of the arc segment 13 breaking or failing under thermal stress.

[0222] In some embodiments, D4>D5.

[0223] In some embodiments, the minimum distance between the second straight segment 12 and the welding portion 25 is D6, and D4 ≥ D6.

[0224] D6 may be a minimum distance between a projection of the second straight line segment 12 along the first direction X and a projection of the welding portion 25 along the first direction X.

[0225] Compared with the second straight segment 12, the arc segment 13 is more susceptible to fatigue damage under the action of thermal stress; in the embodiment of the present application, D4 is set to be greater than or equal to D6, so that there is a larger distance between the arc segment 13 and the welding portion 25, thereby reducing the risk of the arc segment 13 breaking or failing under thermal stress.

[0226] In some embodiments, D4>D6.

[0227] In some embodiments, the welding portion 25 includes a first welding segment 251 extending along a third direction Z, a second welding segment 252 extending along a second direction Y, and an arcuate welding segment 253 connecting the first welding segment 251 and the second welding segment 252. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other. The first straight segment 11 is parallel to the first welding segment 251, the second straight segment 12 is parallel to the second welding segment 252, and the arcuate segment 13 is opposite to the arcuate welding segment 253. The minimum distance between the arcuate segment 13 and the arcuate welding segment 253 is greater than or equal to the minimum distance between the first straight segment 11 and the first welding segment 251.

[0228] The arc segment 13 is more prone to fatigue damage under the action of thermal stress; the embodiment of the present application allows a larger distance between the arc segment 13 and the arc welding segment 253, thereby reducing the risk of the arc segment 13 breaking or failing under thermal stress.

[0229] In some embodiments, the minimum distance between the arc segment 13 and the arc welding segment 253 is greater than or equal to the minimum distance between the second straight segment 12 and the second welding segment 252 .

[0230] For example, the minimum distance between the projection of the arc segment 13 along the first direction X and the projection of the arc-shaped welding segment 253 along the first direction X may be D4; in the second direction Y, the distance between the first straight segment 11 and the first welding segment 251 may be D5; and in the third direction Z, the distance between the second straight segment 12 and the second welding segment 252 may be D6. Optionally, D5 is equal to S4.

[0231] In some embodiments, a length of the first welding segment 251 extending along the third direction Z is smaller than a length of the second welding segment 252 extending along the second direction Y.

[0232] In some embodiments, D4 is 1 mm to 4 mm. Alternatively, D4 is 2 mm to 3 mm. Exemplarily, D4 is 1 mm, 1.2 mm, 1.5 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.5 mm, or 4 mm.

[0233] The embodiment of the present application can create a larger distance between the arc segment 13 and the welding portion 25 , thereby reducing the risk of the arc segment 13 being broken or failing under thermal stress.

[0234] In some embodiments, D5 is 0.8 mm to 4 mm. Alternatively, D5 is 1 mm to 2.5 mm. Exemplarily, D5 is 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.5 mm, or 4 mm.

[0235] The embodiment of the present application can create a larger distance between the first straight segment 11 and the welding portion 25 , thereby reducing the risk of the first straight segment 11 being cracked or failing under thermal stress.

[0236] In some embodiments, D6 is 0.8 mm to 4 mm. Alternatively, D6 is 1 mm to 2.5 mm. Exemplarily, D6 is 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.5 mm, or 4 mm.

[0237] In some embodiments, the pressure relief mechanism 10 includes a weak portion 10a. The thickness of the weak portion 10a is T1, and the penetration depth of the weld portion 25 is T2. T1 and T2 satisfy the following relationship: 0.05≤T1 / T2≤0.3. For example, T1 is the minimum thickness of the weak portion 10a, and T2 is the minimum penetration depth of the weld portion 25.

[0238] In the embodiment of the present application, when the battery cell 6 thermally runs away, the weak portion 10a can be ruptured before the welding portion 25, thereby achieving directional pressure relief of the battery cell 6, reducing the risk of separation between the shell 20a and the end cover 20b, and ensuring that the strength of the weak portion 10a meets the design requirements, thereby reducing the risk of the weak portion 10a rupturing when the battery cell 6 is operating normally.

[0239] For example, the smaller T1 / T2 is, the smaller T1 is or the larger T2 is. If T1 is too small, the strength of the weak portion 10a is low, making it susceptible to rupture when the battery cell 6 is subjected to external impact. If T2 is too large, the greater the heat generated during welding, the greater the thermal stress transferred to the weak portion 10a, making it susceptible to rupture when the battery cell 6 is subjected to external impact. In the embodiment of the present application, T1 / T2 is ≥ 0.05 to reduce the risk of rupture of the weak portion 10a during normal operation of the battery cell 6.

[0240] For example, the larger T1 / T2 is, the larger T1 is or the smaller T2 is. If T1 is too large, the strength of the weak portion 10a is too high. When the battery cell 6 thermally runs away, the weak portion 10a may be difficult to rupture in time, causing a safety hazard. If T2 is too small, the connection strength between the shell 20a and the end cover 20b is too low. When the battery cell 6 thermally runs away, the shell 20a and the end cover 20b may separate before the weak portion 10a ruptures, causing the battery cell 6 to be unable to achieve directional pressure relief, causing a safety hazard. In the embodiment of the present application, T1 / T2≤0.3, which can make the weak portion 10a rupture before the welding portion 25, achieve directional pressure relief of the battery cell 6, reduce the risk of separation between the shell 20a and the end cover 20b, and ensure that the strength of the weak portion 10a meets the design requirements and timely pressure relief.

[0241] In some embodiments, T1 / T2 is 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3.

[0242] In some embodiments, T1 is 0.03 mm to 0.2 mm. Alternatively, T1 is 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, or 0.2 mm.

[0243] In some embodiments, T2 is 0.4 mm to 0.7 mm. Alternatively, T2 is 0.4 mm, 0.5 mm, 0.6 mm or 0.7 mm.

[0244] FIG11 is a simplified schematic diagram of a weak portion of a pressure relief mechanism of a battery cell provided in some embodiments of the present application; FIG12 is a simplified schematic diagram of a weak portion of a pressure relief mechanism of a battery cell provided in other embodiments of the present application.

[0245] As shown in Figures 11 and 12, in some embodiments, there are two first straight line segments 11, and the two first straight line segments 11 are spaced apart along the second direction Y. The two ends of the second straight line segment 12 along the second direction Y are respectively connected to the two first straight line segments 11 through two arc segments 13.

[0246] The weak portion 10a of the embodiment of the present application is substantially enclosed into a rectangular area. When the battery cell 6 experiences thermal runaway, the weak portion 10a ruptures, and a substantially rectangular pressure relief hole is formed on the outer shell of the battery cell, thereby releasing pressure in time.

[0247] 11 , in some embodiments, the weak portion 10a is annular and includes two first straight segments 11, two second straight segments 12, and four arc segments 13. Around the weak portion 10a, adjacent first straight segments 11 and second straight segments 12 are connected by arc segments 13.

[0248] When the battery cell 6 experiences thermal runaway, the weak portion 10 a ruptures, and the portion of the first wall 21 surrounded by the weak portion 10 a separates from the battery cell, thereby reducing the obstruction to high-temperature and high-pressure materials and releasing pressure in time.

[0249] As shown in FIG. 12 , in some embodiments, the weak portion 10 a is composed of two first straight segments 11 , one second straight segment 12 and two arc segments 13 .

[0250] In the event of thermal runaway of the battery cell, the weak portion 10a ruptures, and the portion of the first wall 21 surrounded by the weak portion 10a folds over to form a pressure relief vent, thereby providing timely pressure relief. The portion of the first wall 21 surrounded by the weak portion 10a does not separate from the battery cell, thus reducing the risk of the portion of the first wall 21 surrounded by the weak portion 10a damaging other components.

[0251] FIG13 is an enlarged schematic diagram of the battery shown in FIG3 at the circle F. FIG.

[0252] 3 and 13 , an embodiment of the present application further provides a battery 2 comprising a plurality of battery cells 6 provided in any of the aforementioned embodiments. The plurality of battery cells 6 are arranged along a first direction X. In the first direction X, the pressure relief mechanism 10 is opposite to the recesses 23 of adjacent battery cells 6 .

[0253] The recess 23 of the battery cell 6 can avoid the pressure relief mechanism 10 of the adjacent battery cell 6. Part of the high-temperature and high-pressure material released by the pressure relief mechanism 10 can enter the recess 23 and be released outward through the recess 23, thereby reducing the barrier of the battery cell 6 to the high-temperature and high-pressure material, allowing the battery cell 6 to release pressure in time, improving reliability, and reducing safety risks.

[0254] In some embodiments, at least a portion of the electrode terminal 30 is accommodated in the recess 23 of the adjacent battery cell 6. In the embodiment of the present application, the recess 23 can be used to accommodate the electrode terminal 30, thereby improving space utilization and battery energy density.

[0255] In some embodiments, the battery 2 further includes a busbar 7, which is electrically connected to the electrode terminal 30. For example, a plurality of busbars 7 can connect a plurality of battery cells 6 in series, in parallel, or in mixed series.

[0256] In some examples, at least a portion of the current collecting component 7 is accommodated in the recess 23. In the embodiment of the present application, the recess 23 can be used to accommodate the current collecting component 7, thereby improving space utilization and energy density of the battery.

[0257] According to some embodiments of the present application, there is also provided an electrical device comprising a battery cell according to any of the above embodiments, the battery cell being used to provide electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery cell.

[0258] Referring to Figures 4 to 10 , some embodiments of the present application provide a battery cell 6 comprising a housing 20 and a pressure relief mechanism 10. The housing 20 comprises a shell 20a and an end cap 20b. The shell 20a has an opening, and the end cap 20b is used to cover the opening. The end cap 20b is welded to the shell 20a and forms a weld 25. The shell 20a includes a second wall 22 disposed opposite the end cap 20b along a first direction X. The shell 20a is provided with a recess 23, which is recessed relative to the surface of the second wall 22 facing away from the end cap 20b. The end cap 20b and the pressure relief mechanism 10 are integrally formed. The end cap 20b is provided with a recess 21a, and the bottom of the recess 21a forms a weak portion 10a. The pressure relief mechanism 10 includes the weak portion 10a. The projection of the weak portion 10a along the first direction X is located within the projection of the bottom surface 231 of the recess along the first direction X.

[0259] 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.

[0260] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A battery cell, comprising: A housing having a first wall and a second wall disposed opposite to each other along a first direction, wherein the housing is provided with a recessed portion, the recessed portion being recessed relative to a surface of the second wall facing away from the first wall; as well as The pressure relief mechanism is provided on the first wall, and a projection of the pressure relief mechanism along the first direction at least partially overlaps with a projection of the recess along the first direction.

2. The battery cell according to claim 1, wherein: A projection of the pressure relief mechanism along the first direction does not overlap with a projection of the second wall along the first direction.

3. The battery cell according to claim 2, wherein: A minimum distance between a projection of the pressure relief mechanism along the first direction and a projection of the second wall along the first direction is greater than or equal to 0.5 mm.

4. The battery cell according to claim 2 or 3, wherein: A projection of the pressure relief mechanism along the first direction is located within a projection of the bottom surface of the recess along the first direction.

5. The battery cell according to any one of claims 1 to 4, wherein: The recess is provided on at least one side of the second wall in a second direction, and the second direction is perpendicular to the first direction. The battery cell according to claim 5 , wherein: In the second direction, a minimum distance between a projection of the pressure relief mechanism on the bottom surface of the recess and a side surface of the recess is greater than or equal to 1 mm.

7. The battery cell according to claim 5 or 6, wherein: The first wall includes two first edges arranged opposite to each other along the second direction; In the second direction, the minimum distance between the side surface of the recess and the adjacent first edge is L1, the maximum distance between the end of the pressure relief mechanism away from the adjacent first edge and the first edge is L2, and L2 / L1≥0.

6.

8. The battery cell according to any one of claims 5 to 7, wherein: The recess passes through the housing along a third direction, and the first direction, the second direction and the third direction are perpendicular to each other.

9. The battery cell according to any one of claims 5 to 8, wherein: Two second edges of the first wall are oppositely arranged along a third direction, and the first direction, the second direction and the third direction are perpendicular to each other; In the third direction, the minimum distance between the pressure relief mechanism and the second edge is 2 mm to 10 mm.

10. The battery cell according to any one of claims 1 to 9, wherein: The size of the housing along the second direction is greater than the size of the housing along the third direction, and the size of the housing along the third direction is greater than the size of the housing along the first direction; The first direction, the second direction, and the third direction are perpendicular to each other.

11. The battery cell according to any one of claims 1 to 10, wherein: There are two recesses, and the two recesses are respectively located on both sides of the second wall along a second direction, and the second direction is perpendicular to the first direction; There are two pressure relief mechanisms, and the two pressure relief mechanisms are arranged at two ends of the first wall along the second direction.

12. The battery cell according to any one of claims 1 to 11, wherein: The first wall is integrally formed with the pressure relief mechanism, and the pressure relief mechanism includes a weakened portion.

13. The battery cell according to any one of claims 1 to 12, wherein: The pressure relief mechanism includes a weak portion, and a ratio of a thickness of the weak portion to a thickness of the first wall is 0.1-0.

4.

14. The battery cell according to any one of claims 1 to 13, wherein: The first wall is provided with a groove, and the pressure relief mechanism includes a weakened portion; The bottom of the groove forms the weak portion.

15. The battery cell according to any one of claims 12 to 14, wherein: The angle of the weak portion is 180°-360°. 16 . The battery cell according to claim 12 , further comprising an electrode terminal mounted on a region of the first wall surrounded by the weak portion.

17. The battery cell according to any one of claims 12 to 16, wherein: The weak portion includes a first straight line segment, a second straight line segment, and an arc segment connected between the first straight line segment and the second straight line segment.

18. The battery cell according to claim 17, wherein: The minimum distance between the arc segment and the edge of the first wall is D1, and the minimum distance between the first straight segment and the edge of the first wall is D2, where D1≥D2.

19. The battery cell according to claim 18, wherein: The minimum distance between the second straight line segment and the edge of the first wall is D3, and D1 ≥ D3.

20. The battery cell according to claim 18 or 19, wherein: The first wall includes a first edge extending along a third direction, a second edge extending along a second direction, and an arcuate edge connecting the first edge and the second edge, wherein the first direction, the second direction, and the third direction are perpendicular to each other; The first straight line segment is parallel to the first edge, the second straight line segment is parallel to the second edge, and the arc segment is opposite to the arc edge; The minimum distance between the arc segment and the arc edge is greater than or equal to the distance between the first straight segment and the first edge.

21. The battery cell according to claim 20, wherein: There are two first straight line segments, and the two first straight line segments are spaced apart along the second direction. Both ends of the second straight line segment along the second direction are respectively connected to the two first straight line segments through the two arc segments.

22. The battery cell according to claim 21, wherein The weak portion is annular and includes two first straight line segments, two second straight line segments and four arc segments; In the circumferential direction of the weak portion, adjacent first straight line segments and second straight line segments are connected by the arc segment.

23. The battery cell according to any one of claims 1 to 22, wherein: The housing comprises a shell and an end cover, the shell having an opening, and the end cover is used to cover the opening; The end cover is the first wall, and the shell includes the second wall; the end cover is welded to the shell to form a welding portion.

24. The battery cell according to claim 23, wherein: The pressure relief mechanism includes a weak portion; The welding portion surrounds the weak portion; and the minimum distance between the weak portion and the welding portion is 0.5 mm to 5 mm.

25. The battery cell according to claim 24, wherein The weak portion includes a first straight line segment, a second straight line segment, and an arc segment connected between the first straight line segment and the second straight line segment; The minimum distance between the arc segment and the welding portion is D4, the minimum distance between the first straight segment and the welding portion is D5, and D4≥D5.

26. The battery cell according to claim 25, wherein: The minimum distance between the second straight line segment and the welding portion is D6, and D4≥D6.

27. The battery cell according to claim 25 or 26, wherein: The welding portion includes a first welding segment extending along a third direction, a second welding segment extending along a second direction, and an arc-shaped welding segment connecting the first welding segment and the second welding segment, wherein the first direction, the second direction, and the third direction are perpendicular to each other; The first straight segment is parallel to the first welding segment, the second straight segment is parallel to the second welding segment, and the arc segment is opposite to the arc welding segment; The minimum distance between the arc segment and the arc welding segment is greater than or equal to the minimum distance between the first straight segment and the first welding segment.

28. The battery cell according to any one of claims 25 to 27, wherein: D4 is 1mm-4mm, optionally, D4 is 2mm-3mm.

29. The battery cell according to any one of claims 25 to 28, wherein: D5 is 0.8mm-4mm, optionally, D5 is 1mm-2.5mm.

30. The battery cell according to any one of claims 23 to 29, wherein: The pressure relief mechanism includes a weak portion; the thickness of the weak portion is T1, the penetration depth of the weld portion is T2, and T1 and T2 satisfy: 0.05≤T1 / T2≤0.

3.

31. A battery comprising a plurality of battery cells according to any one of claims 1 to 30; The plurality of battery cells are arranged along the first direction; in the first direction, the pressure relief mechanism is opposite to the recessed portions of the adjacent battery cells.

32. An electrical device comprising the battery cell according to any one of claims 1 to 30, wherein the battery cell is used to provide electrical energy.

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