End caps, battery cells, batteries and electrical equipment

Abstract

This application provides an end cap, a battery cell, a battery, and an electrical device, belonging to the field of battery technology. The end cap includes a cap body and a groove. The cap body has a first surface. A groove is disposed on the cap body to form a pressure relief area in the area where the groove is formed. The groove is recessed from the first surface along the thickness direction of the cap body, and the side surface of the groove includes a corner surface located at the corner of the groove. The corner surface is connected to the first surface through a first chamfered surface. The first chamfered surface weakens the strength of the pressure relief area at the corner of the groove, homogenizes the strength of the pressure relief area at the corner and edge of the groove, reduces the risk of local stress concentration in the pressure relief area, effectively protects the pressure relief area, and improves the impact resistance of the end cap.

Description

Technical Field

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

[0002] With the development of new energy technologies, batteries are being used more and more widely, such as in mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools.

[0003] In battery technology, not only the safety of individual battery cells but also their lifespan must be considered. The impact resistance of the end caps directly affects the lifespan of individual battery cells. Therefore, improving the impact resistance of end caps is a pressing issue that needs to be addressed in battery technology. Summary of the Invention

[0004] This application provides an end cap, a battery cell, a battery, and an electrical device, which can effectively improve the impact resistance of the end cap.

[0005] In a first aspect, embodiments of this application provide an end cap, including a cap body and a groove; the cap body has a first surface; the groove is disposed on the cap body to form a pressure relief area in the area where the groove is disposed on the cap body, the groove is recessed from the first surface along the thickness direction of the cap body, and the groove side surface includes a corner surface located at the corner position of the groove; wherein, the corner surface is connected to the first surface through a first chamfered surface.

[0006] In the above technical solution, the corner surface and the first surface are connected by the first chamfered surface. The setting of the first chamfered surface weakens the strength of the pressure relief area at the corner of the groove, and equalizes the strength of the pressure relief area at the corner and edge of the groove, reducing the risk of local stress concentration in the pressure relief area, which can effectively protect the pressure relief area and improve the impact resistance of the end cap.

[0007] In some embodiments, the radius of the first chamfered surface gradually increases from both ends to the middle along the circumference of the groove. This structure causes the strength of the pressure relief zone at the corner of the groove to gradually increase from the middle to both ends of the first chamfered surface.

[0008] In some embodiments, the maximum radius of the first chamfered surface is R1, which satisfies: 0.5mm≤R1≤2mm.

[0009] In some embodiments, the groove side surface further includes a first side surface connected to the corner surface, and the first side surface is connected to the first surface via a second chamfered surface; wherein the maximum radius of the second chamfered surface is smaller than the maximum radius of the first chamfered surface. The second chamfered surface allows the first side surface to transition more smoothly to the first surface, avoiding a sharp corner formed by direct connection between the first side surface and the first surface. The smaller maximum radius of the second chamfered surface compared to the first chamfered surface helps to even out the intensity of the pressure relief zone at the corners and edges of the groove.

[0010] In some embodiments, along the circumference of the groove, both ends of the second chamfered surface are connected to the first chamfered surface, and the radius of the second chamfered surface gradually decreases from both ends to the middle. This structure causes the strength of the pressure relief zone at the edge of the groove to gradually increase from both ends of the second chamfered surface to the middle, enhancing the strength of the pressure relief zone at the middle position of the edge of the groove and providing better impact resistance.

[0011] In some embodiments, the first chamfered surface and the second chamfered surface are connected at a first connection position, and the radius of the first chamfered surface at the first connection position is equal to the radius of the second chamfered surface at the first connection position. This structure allows the first chamfered surface to transition more smoothly to the second chamfered surface, enabling the first chamfered surface and the second chamfered surface to form a continuous chamfered surface.

[0012] In some embodiments, the maximum radius of the second chamfered surface is R2, which satisfies: 0.1mm≤R2≤0.5mm.

[0013] In some embodiments, the groove side also includes a second side, which is located at a different orientation from the first side in the groove. The second side is connected to the first side via a corner surface, and the second side is connected to the first surface via a third chamfer surface. The maximum radius of the third chamfer surface is smaller than the maximum radius of the first chamfer surface. The third chamfer surface allows the second side to transition more smoothly to the first surface, avoiding a sharp corner formed by direct connection between the second side and the first surface. The smaller maximum radius of the third chamfer surface than the first chamfer surface homogenizes the intensity of the pressure relief zone at the corners and edges of the groove.

[0014] In some embodiments, along the circumference of the groove, both ends of the third chamfered surface are connected to the first chamfered surface, and the radius of the third chamfered surface gradually decreases from both ends to the middle. This structure causes the strength of the pressure relief zone at the edge of the groove to gradually increase from both ends of the third chamfered surface to the middle, enhancing the strength of the pressure relief zone at the middle position of the edge of the groove and providing better impact resistance.

[0015] In some embodiments, the first chamfered surface and the third chamfered surface are connected at a second connection position, and the radius of the first chamfered surface at the second connection position is equal to the radius of the third chamfered surface at the second connection position. This structure allows the first chamfered surface to transition more smoothly to the third chamfered surface, enabling the first and third chamfered surfaces to form a continuous chamfered surface.

[0016] In some embodiments, the maximum radius of the third chamfer surface is R3, satisfying: 0.1mm≤R3≤0.5mm.

[0017] In some embodiments, the groove sidewall includes two first sidewalls and two second sidewalls. The two first sidewalls are arranged opposite each other along a first direction, and the two second sidewalls are arranged opposite each other along a second direction, with the first direction perpendicular to the second direction. Thus, the two first sidewalls and the two second sidewalls are located in different orientations, making the groove approximately rectangular, resulting in a simple structure that is easy to form.

[0018] In some embodiments, the distance between the two first sides along a first direction is a first distance, and the distance between the two second sides along a second direction is a second distance, wherein the first distance is less than the second distance. This makes the groove approximately rectangular, and the pressure relief area also approximately rectangular, resulting in a large pressure relief area.

[0019] In some embodiments, the first direction is the length direction of the cover body, and the second direction is the width direction of the cover body. When the inner side of the end cover is subjected to pressure from inside the battery cell, the pressure relief area is more likely to be damaged at the short side of the groove. When the outer side of the end cover is subjected to impact force, the pressure relief area is more likely to be damaged at the long side of the groove. This makes the pressure relief area more likely to be damaged at different locations under two different operating conditions, thereby enhancing the impact resistance of the end cover and improving the service life of the battery cell.

[0020] In some embodiments, the cover body is provided with pressure relief grooves located in the pressure relief area. The area of ​​the cover body with the pressure relief grooves is thinner, so that when the pressure inside the battery cell reaches the explosion pressure, the pressure relief area cracks at the location where the pressure relief grooves are provided, so as to release pressure from the pressure relief area.

[0021] In some embodiments, the pressure relief groove is a closed groove extending along a closed trajectory connected end to end. This structure allows the pressure relief area to open when the pressure inside the battery cell reaches the explosion pressure within the region defined by the pressure relief groove, resulting in a larger pressure relief area and improved pressure relief efficiency.

[0022] In some embodiments, the end cap further includes a protective element attached to the cap body and covering the recess. The protective element covers the recess and protects the pressure relief area, reducing the risk of damage to the pressure relief area from foreign objects.

[0023] In some embodiments, the protective element is attached to the first surface. This structure, on the one hand, facilitates the installation of the protective element; on the other hand, the protective element can cover all chamfered surfaces, providing better protection for the pressure relief area.

[0024] In some embodiments, the cover body is provided with an exhaust channel that connects the interior of the groove to the exterior of the cover body. The exhaust channel allows the interior of the groove to communicate with the outside, thereby balancing the air pressure inside and outside the groove and reducing the risk of the protective component falling off due to increased air pressure inside the groove.

[0025] In some embodiments, the venting channel is a venting groove disposed on the cover body, and the venting groove penetrates the first surface. This structure of the venting channel can effectively connect the interior of the groove with the outside world and is easy to form.

[0026] Secondly, embodiments of this application provide a battery cell, including a housing and an end cap provided in any of the embodiments of the first aspect; the housing has an opening; and the end cap body closes the opening.

[0027] Thirdly, embodiments of this application provide a battery, including a housing and a battery cell provided in any of the second embodiments, wherein the battery cell is housed within the housing.

[0028] In some embodiments, the housing has a bottom wall, and end caps are disposed on the side of the battery cell facing the bottom wall.

[0029] Fourthly, embodiments of this application also provide an electrical device, including the battery provided in any one of the embodiments of the third aspect. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0032] Figure 2 Exploded views of batteries provided for some embodiments of this application;

[0033] Figure 3 Exploded views of a single battery cell provided in some embodiments of this application;

[0034] Figure 4 This is a schematic diagram of the end cap structure provided in some embodiments of this application;

[0035] Figure 5 for Figure 4 The image shows a magnified view of the end cap at point A.

[0036] Figure 6 This is a schematic diagram of the end cap structure provided in some other embodiments of this application;

[0037] Figure 7 for Figure 6 The exploded view of the end cap shown;

[0038] Figure 8 for Figure 6 The image shown is a magnified view of the end cap after the protective component has been removed.

[0039] Icons: 1-Housing; 2-Electrode assembly; 21-Positive tab; 22-Negative tab; 3-End cap; 31-Cap body; 311-Boss; 3111-First surface; 312-Pressure relief area; 313-Pressure relief groove; 314-Exhaust channel; 32-Groove; 321-Corner surface; 322-First chamfered surface; 323-First side surface; 324-Second chamfered surface; 325-Second side surface; 326-Third chamfered surface; 33-Protective component; 4-Electrode terminal; 4a-Positive electrode terminal; 4b-Negative electrode terminal; 5-Current collector; 10-Battery cell; 20-Casing; 201-First part; 202-Second part; 100-Battery; 200-Controller; 300-Motor; 1000-Vehicle; a-First connection position; b-Second connection position; X-First direction; Y-Second direction; Z-Thickness direction. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0042] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0044] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0045] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0046] In this application, "multiple" means two or more (including two).

[0047] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0048] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0049] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated one, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated one, serving as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to these.

[0050] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge / discharge rate and other performance parameters. In addition, battery safety also needs to be considered.

[0051] For individual battery cells, to ensure safety, a pressure relief structure can be set on the end cap of the battery cell. For example, a groove can be set on the end cap, making the end cap relatively weak at the location where the groove is set, so as to form a pressure relief area. In the event of thermal runaway of the battery cell, the pressure inside the battery cell can be released through the pressure relief area, reducing the risk of battery cell explosion and fire, and improving the safety of the battery cell.

[0052] The inventors noted that, under actual operating conditions, the pressure relief area of ​​the end cap of a battery cell is prone to abnormally opening without thermal runaway, which affects the service life of the battery cell.

[0053] The inventors discovered that, for end caps, the strength of the pressure relief area at the edge of the groove is less than that at the corner of the groove. When the end cap is subjected to an impact, the stress is concentrated at the edge of the groove due to the relatively weak strength of the pressure relief area at the edge of the groove. This causes greater deformation at the edge of the groove and less deformation at the corner, resulting in abnormal opening of the pressure relief area and affecting the service life of the battery cell.

[0054] Therefore, this application provides an end cap, which includes a cap body and a groove. The cap body has a first surface. The groove is disposed on the cap body to form a pressure relief area in the area where the groove is disposed on the cap body. The groove is recessed from the first surface along the thickness direction of the cap body, and the groove side includes a corner surface located at the corner of the groove. The corner surface is connected to the first surface through a first chamfered surface.

[0055] In this type of end cap, the corner surface is connected to the first surface through a first chamfered surface. The first chamfered surface weakens the strength of the pressure relief area at the corner of the groove, and equalizes the strength of the pressure relief area at the corner and edge of the groove. When the end cap is subjected to impact force, the deformation of the pressure relief area at the edge of the groove will not differ too much from the deformation of the pressure relief area at the corner of the groove, reducing the risk of local stress concentration in the pressure relief area, effectively protecting the pressure relief area, and improving the impact resistance of the end cap.

[0056] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0057] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0058] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0059] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. A battery 100 is disposed inside the vehicle 1000, and the battery 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000.

[0060] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0061] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0062] Please refer to Figure 2 , Figure 2 The exploded view of a battery 100 provided in some embodiments of this application shows that the battery 100 includes a battery cell 10 and a housing 20 for housing the battery cell 10.

[0063] The housing 20 is a component that houses the battery cell 10, providing a space for the battery cell 10. The housing 20 can adopt various structures. In some embodiments, the housing 20 may include a first portion 201 and a second portion 202, which overlap each other to define a space for accommodating the battery cell 10. The first portion 201 and the second portion 202 can be various shapes, such as cuboids, cylinders, etc. The first portion 201 can be a hollow structure open on one side, and the second portion 202 can also be a hollow structure open on one side, with the open side of the second portion 202 overlapping the open side of the first portion 201, thus forming a housing 20 with a accommodating space. Alternatively, the first portion 201 can be a hollow structure open on one side, and the second portion 202 can be a plate-like structure, with the second portion 202 overlapping the open side of the first portion 201, thus forming a housing 20 with a accommodating space. The first part 201 and the second part 202 can be sealed by a sealing element, which can be a sealing ring, sealant, etc.

[0064] In battery 100, there can be one or more battery cells 10. If there are multiple battery cells 10, they can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 10 are connected in both series and parallel. Alternatively, multiple battery cells 10 can be first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole, which is then housed within the housing 20. Another option is that all battery cells 10 can be directly connected in series, parallel, or in a mixed manner, and then the whole consisting of all battery cells 10 is housed within the housing 20.

[0065] In some embodiments, the battery 100 may further include a busbar component, through which multiple battery cells 10 can be electrically connected to each other to achieve series, parallel, or mixed connection of multiple battery cells 10. The busbar component may be a metallic conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0066] Please refer to Figure 3 , Figure 3 This is an exploded view of a battery cell 10 provided in some embodiments of this application. The battery cell 10 includes a housing 1, an electrode assembly 2, an end cap 3, electrode terminals 4, and a current collector 5.

[0067] The housing 1 is a component used to house the electrode assembly 2. The housing 1 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The housing 1 can be in various shapes, such as a cylinder or a cuboid. The housing 1 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0068] Electrode assembly 2 is the component in the battery cell 10 where the electrochemical reaction occurs. Electrode assembly 2 may include a positive electrode, a negative electrode, and a separator. Electrode assembly 2 can be a wound structure formed by winding the positive electrode, separator, and negative electrode, or a stacked structure formed by arranging the positive electrode, separator, and negative electrode in layers. Electrode assembly 2 has a positive electrode tab 21 and a negative electrode tab 22. The positive electrode tab 21 may be the portion of the positive electrode that is not coated with a positive active material layer, and the negative electrode tab 22 may be the portion of the negative electrode that is not coated with a negative active material layer.

[0069] End cap 3 is a component that closes the opening of housing 1 to isolate the internal environment of battery cell 10 from the external environment. End cap 3 and housing 1 together define a sealed space for accommodating electrode assembly 2, electrolyte, and other components. The shape of end cap 3 can be adapted to the shape of housing 1; for example, if housing 1 is a cuboid structure, end cap 3 can be a rectangular structure adapted to housing 1. End cap 3 can also be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. End cap 3 can be fixed to housing 1 by welding.

[0070] In the battery cell 10, there can be one or two end caps 3. If the housing 1 is a hollow structure with an opening at one end, then one end cap 3 can be provided. If the housing 1 is a hollow structure with openings at both ends, then two end caps 3 can be provided, with the two end caps 3 respectively closing the two openings of the housing 1.

[0071] Electrode terminals 4 are components that connect the battery cell 10 to other components to output the electrical energy of the battery cell 10. Electrode terminals 4 are disposed on end caps 3 and are used for electrical connection to the positive tab 21 or negative tab 22 of the electrode assembly 2. In the battery cell 10, there can be two electrode terminals 4, namely a positive electrode terminal 4a and a negative electrode terminal 4b. The positive electrode terminal 4a is used for electrical connection to the positive tab 21, and the negative electrode terminal 4b is used for electrical connection to the negative tab 22. In embodiments where there are two end caps 3 in the battery cell 10, the positive electrode terminal 4a and the negative electrode terminal 4b can be disposed on the same end cap 3, or they can be disposed on two separate end caps 3. Figure 3 As shown, in an embodiment where the end cap 3 in the battery cell 10 is one, the positive electrode terminal 4a and the negative electrode terminal 4b can be disposed on the same end cap 3.

[0072] The current collector 5 is a component that enables electrical connection between the tab and the electrode terminal 4. For example... Figure 3 As shown, taking the end cap 3 in the battery cell 10 as an example, and both the positive electrode terminal 4a and the negative electrode terminal 4b are disposed on the end cap 3, the positive electrode terminal 4a can be connected to the positive electrode tab 21 through a current collector 5, and the negative electrode terminal 4b can be connected to the negative electrode tab 22 through another current collector 5.

[0073] Please refer to Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the structure of the end cap 3 provided in some embodiments of this application; Figure 5 for Figure 4 The image shows a partial enlarged view of the end cap 3 at point A. This application provides an end cap 3, including a cap body 31 and a groove 32. The cap body 31 has a first surface 3111. The groove 32 is disposed on the cap body 31 to form a pressure relief area 312 in the area where the groove 32 is disposed on the cap body 31. The groove 32 is recessed from the first surface 3111 along the thickness direction Z of the cap body 31. The groove side of the groove 32 includes a corner surface 321 located at the corner of the groove 32. The corner surface 321 is connected to the first surface 3111 via a first chamfered surface 322.

[0074] The cover body 31 is used to connect with the housing 1 ( Figure 3 (As shown in the diagram) The end cap 3 is connected to close the opening of the housing 1, and the cap body 31 and the end cap 3 can be fixed by welding. For example, the cap body 31 has a rectangular structure.

[0075] The first surface 3111 can be the outermost surface of the cover body 31 in the thickness direction Z, that is, the outermost surface of the cover body 31 away from the shell 1. For example, if the cover body 31 is a flat plate structure, the first surface 3111 can be the outer surface of the cover body 31 away from the shell 1 in the thickness direction Z. For example, ... Figure 4 As shown, a boss 311 is formed by a portion of the cover body 31 protruding away from the housing 1 along its thickness direction Z. The first surface 3111 can be the outer surface of the boss 311 that is away from the housing 1 along the thickness direction Z of the cover body 31. A recessed space is formed on the side of the cover body 31 facing the housing 1 at a position corresponding to the protrusion. The recessed space can accommodate the components inside the battery cell 10, such as the current collector 5 and the tabs of the electrode assembly 2, thereby improving the energy density of the battery cell 10. In addition, this structure can also improve the bending strength of the cover body 31 and the impact resistance of the end cover 3.

[0076] The groove 32 can be formed in various ways, such as stamping or milling. The groove 32 can be of various shapes, such as rectangular, parallelogram, or trapezoidal. For example, in... Figure 5 In the middle, the groove 32 is roughly rectangular.

[0077] The side surfaces of the groove 32 are the surfaces surrounding the groove 32. The side surfaces are distributed around the openings formed by the groove 32 on the first surface 3111. The side surfaces and the bottom surface of the groove 32 together define the internal space of the groove 32. Taking the groove 32 as roughly rectangular as an example, the side surfaces of the groove 32 have four sides located in different directions. The four sides are located on the four sides of the rectangle, and adjacent sides are connected by corner surfaces 321. The corner surfaces 321 correspond to the corner positions of the groove 32, and the side surfaces correspond to the edge positions of the groove 32.

[0078] The pressure relief area 312 is the part of the cover body 31 corresponding to the groove 32. That is, after the groove 32 is provided on the cover body 31, the remaining part of the cover body 31 at the location of the groove 32 is the pressure relief area 312. The pressure relief area 312 is thinner than other areas of the cover body 31. The pressure relief area 312 is the part of the end cap 3 used for pressure relief. When the internal pressure of the battery cell 10 reaches the explosion pressure, the pressure relief area 312 can be opened by means of partial rupture, partial or complete detachment, etc., to form a channel for the discharge inside the battery cell 10 to flow outward, thereby achieving the purpose of pressure relief.

[0079] The corner surface 321 is the part of the side of the groove located at the corner of the groove 32. The corner surface 321 can be an arc surface, and the center line of the arc surface can extend along the thickness direction Z of the cover body 31. Taking the groove 32 as an example that is roughly rectangular, the groove 32 has four sides located in different directions. Adjacent sides are connected by the corner surface 321, so that the adjacent sides are smoothly transitioned by the corner surface 321.

[0080] The first chamfered surface 322 connects the corner surface 321 and the first surface 3111, achieving a smooth transition between the corner surface 321 and the first surface 3111. The first chamfered surface 322 extends along the arc trajectory of the corner surface 321, and the cross-section of the first chamfered surface 322 is arc-shaped. The first chamfered surface 322 can be a variable-diameter structure, that is, the radius of the first chamfered surface 322 varies along the extension direction of the first chamfered surface 322; the first chamfered surface 322 can also be a constant-diameter structure, that is, the radius of the first chamfered surface 322 does not change along the extension direction of the first chamfered surface 322.

[0081] In this embodiment, the corner surface 321 is connected to the first surface 3111 through the first chamfer surface 322. The first chamfer surface 322 weakens the strength of the pressure relief area 312 at the corner of the groove 32, and equalizes the strength of the pressure relief area 312 at the corner and edge of the groove 32, reducing the risk of local stress concentration in the pressure relief area 312, which can effectively protect the pressure relief area 312 and improve the impact resistance of the end cap 3.

[0082] In some embodiments, please continue to refer to Figure 5 Along the circumference of the groove 32, the radius of the first chamfered surface 322 gradually increases from both ends to the middle position.

[0083] The circumferential direction of the groove 32 is the same as the extension direction of the side surface of the groove 32. The two ends of the first chamfer surface 322 in the circumferential direction of the groove 32 are the two ends of the first chamfer surface 322 in the extension direction. The extension direction of the first chamfer surface 322 is consistent with the extension direction of the arc trajectory of the corner surface 321. The radii of the first chamfer surface 322 at the two ends can be equal or unequal.

[0084] Understandably, in this embodiment, the first chamfered surface 322 has a variable diameter structure. The radius of the first chamfered surface 322 gradually increases from both ends to the middle position. The thickness of the cover body 31 is smaller at the middle position of the first chamfered surface 322 and larger at both ends of the first chamfered surface 322. The thickness of the cover body 31 at the position of the first chamfered surface 322 gradually decreases from both ends to the middle position of the first chamfered surface 322, so that the strength of the pressure relief area 312 at the corner position of the groove 32 gradually increases from the middle to both ends of the first chamfered surface 322.

[0085] In some embodiments, the maximum radius of the first chamfered surface 322 is R1, which satisfies: 0.5mm≤R1≤2mm.

[0086] In an embodiment where the first chamfered surface 322 has a constant diameter, the radius of the first chamfered surface 322 at any position in its extension direction is R1; in an embodiment where the first chamfered surface 322 has a variable diameter, taking the example that the radius of the first chamfered surface 322 gradually increases from both ends to the middle position, the radius of the first chamfered surface 322 at the middle position is R1.

[0087] In some embodiments, please continue to refer to Figure 5 The groove side also includes a first side surface 323 connected to the corner surface 321, and the first side surface 323 is connected to the first surface 3111 through a second chamfered surface 324. The maximum radius of the second chamfered surface 324 is smaller than the maximum radius of the first chamfered surface 322.

[0088] The first side 323 is one of the sides of the groove. Taking the groove 32 as a rectangle, the first side 323 is a plane. The first side 323 can be a side of the groove extending along the length direction or a side of the groove extending along the width direction.

[0089] The second chamfered surface 324 connects the first side surface 323 and the first surface 3111, achieving a smooth transition between the two surfaces. The second chamfered surface 324 extends along the extension direction of the first side surface 323, and its cross-section is arc-shaped. The second chamfered surface 324 can be a variable-diameter structure, meaning its radius varies along its extension direction; or it can be a constant-diameter structure, meaning its radius remains constant along its extension direction. In embodiments where the second chamfered surface 324 is a constant-diameter structure, the radius of the second chamfered surface 324 at any position along its extension direction is equal to its maximum radius.

[0090] In this embodiment, the second chamfered surface 324 allows the first side surface 323 to transition more smoothly to the first surface 3111, preventing the first side surface 323 from directly connecting with the first surface 3111 and forming a sharp corner. The maximum radius of the second chamfered surface 324 is smaller than the maximum radius of the first chamfered surface 322, which can homogenize the strength of the pressure relief area 312 at the corners and edges of the groove 32.

[0091] In some embodiments, please continue to refer to Figure 5 Along the circumference of the groove 32, both ends of the second chamfered surface 324 are connected to the first chamfered surface 322, and the radius of the second chamfered surface 324 gradually decreases from both ends to the middle position.

[0092] The two ends of the second chamfered surface 324 in the circumferential direction of the groove 32 are also the two ends of the second chamfered surface 324 in the extending direction. The extending direction of the second chamfered surface 324 is consistent with the extending direction of the first side surface 323. The radii of the second chamfered surface 324 at the two ends can be equal or unequal. For example, in Figure 5 In the middle, the radii of the second chamfered surface 324 are equal at both ends.

[0093] Given that the radius of the first chamfered surface 322 gradually increases from both ends to the middle position, and the maximum radius of the second chamfered surface 324 is less than the maximum radius of the first chamfered surface 322, it is understandable that the radius at both ends of the second chamfered surface 324 is less than the radius at the middle position of the first chamfered surface 322.

[0094] In this embodiment, the second chamfered surface 324 has a variable diameter structure. The radius of the second chamfered surface 324 gradually decreases from both ends to the middle position. The thickness of the cover body 31 is greater at the middle position of the second chamfered surface 324 and less at both ends. The thickness of the cover body 31 at the position of the second chamfered surface 324 gradually increases from both ends to the middle position. This makes the strength of the pressure relief area 312 at the edge of the groove 32 gradually increase from both ends to the middle position of the second chamfered surface 324, thereby enhancing the strength of the pressure relief area 312 at the middle position of the edge of the groove 32 and providing better impact resistance.

[0095] In some embodiments, please continue to refer to Figure 5 The first chamfered surface 322 and the second chamfered surface 324 are connected at the first connection position a, and the radius of the first chamfered surface 322 at the first connection position a is equal to the radius of the second chamfered surface 324 at the first connection position a.

[0096] The first connection position a is the position where the first chamfered surface 322 and the second chamfered surface 324 are connected. In an embodiment where both ends of the second chamfered surface 324 are connected to the first chamfered surface 322, two first connection positions a are formed at the two ends of the second chamfered surface 324.

[0097] In this embodiment, the radius of the first chamfered surface 322 at the first connection position a is equal to the radius of the second chamfered surface 324 at the first connection position a, so that the first chamfered surface 322 can transition to the second chamfered surface 324 more smoothly, and the first chamfered surface 322 and the second chamfered surface 324 can form a continuous chamfered surface.

[0098] In some embodiments, the maximum radius of the second chamfered surface 324 is R2, which satisfies: 0.1mm≤R2≤0.5mm.

[0099] In an embodiment where the second chamfered surface 324 has a constant diameter, the radius of the second chamfered surface 324 at any position in its extension direction is R2; in an embodiment where the second chamfered surface 324 has a variable diameter, taking the example that the radius of the second chamfered surface 324 gradually decreases from both ends to the middle position, the radius of at least one of the two ends of the second chamfered surface 324 is R2.

[0100] In some embodiments, the groove side also includes a second side surface 325, which is located at a different position from the first side surface 323 in the groove 32. The second side surface 325 and the first side surface 323 are connected by a corner surface 321, and the second side surface 325 is connected to the first surface 3111 by a third chamfer surface 326. The maximum radius of the third chamfer surface 326 is smaller than the maximum radius of the first chamfer surface 322.

[0101] The second side 325 is one of the sides of the groove. Taking the groove 32 as a rectangle, the second side 325 is a plane. The second side 325 can be a side of the groove extending along the length direction or a side of the groove extending along the width direction.

[0102] The third chamfered surface 326 connects the second side surface 325 and the first surface 3111, achieving a smooth transition between the two surfaces. The third chamfered surface 326 extends along the extension direction of the second side surface 325, and its cross-section is arc-shaped. The third chamfered surface 326 can be a variable-diameter structure, meaning its radius varies along its extension direction; or it can be a constant-diameter structure, meaning its radius remains constant along its extension direction. In embodiments where the third chamfered surface 326 is a constant-diameter structure, the radius of the third chamfered surface 326 at any position along its extension direction is equal to its maximum radius.

[0103] In this embodiment, the third chamfered surface 326 allows the second side surface 325 to transition more smoothly to the first surface 3111, preventing the second side surface 325 from directly connecting with the first surface 3111 and forming a sharp corner. The maximum radius of the third chamfered surface 326 is smaller than the maximum radius of the first chamfered surface 322, which can homogenize the strength of the pressure relief area 312 at the corners and edges of the groove 32.

[0104] In some embodiments, please continue to refer to Figure 5 Along the circumference of the groove 32, both ends of the third chamfered surface 326 are connected to the first chamfered surface 322, and the radius of the third chamfered surface 326 gradually decreases from both ends to the middle position.

[0105] The two ends of the third chamfered surface 326 in the circumferential direction of the groove 32 are also the two ends of the third chamfered surface 326 in the extending direction. The extending direction of the third chamfered surface 326 is consistent with the extending direction of the second side surface 325. The radii of the third chamfered surface 326 at the two ends can be equal or unequal. For example, in Figure 5 In the middle, the radii of the third chamfered surface 326 are equal at both ends.

[0106] Given that the radius of the first chamfered surface 322 gradually increases from both ends to the middle position, and the maximum radius of the third chamfered surface 326 is less than the maximum radius of the first chamfered surface 322, it is understandable that the radius at both ends of the third chamfered surface 326 is less than the radius at the middle position of the first chamfered surface 322.

[0107] Understandably, in this embodiment, the third chamfered surface 326 has a variable diameter structure. The radius of the third chamfered surface 326 gradually decreases from both ends to the middle position. The thickness of the cover body 31 is greater at the middle position of the third chamfered surface 326 and less at both ends. The thickness of the cover body 31 at the third chamfered surface 326 gradually increases from both ends to the middle position, so that the strength of the pressure relief area 312 at the edge of the groove 32 gradually increases from both ends to the middle position of the third chamfered surface 326, thereby enhancing the strength of the pressure relief area 312 at the middle position of the edge of the groove 32 and providing better impact resistance.

[0108] In some embodiments, please continue to refer to Figure 5 The first chamfered surface 322 and the third chamfered surface 326 are connected at the second connection position b, and the radius of the first chamfered surface 322 at the second connection position b is equal to the radius of the third chamfered surface 326 at the second connection position b.

[0109] The second connection position b is the position where the first chamfered surface 322 and the third chamfered surface 326 are connected. In an embodiment where both ends of the third chamfered surface 326 are connected to the first chamfered surface 322, two second connection positions b are formed at the two ends of the third chamfered surface 326.

[0110] In this embodiment, the radius of the first chamfered surface 322 at the second connection position b is equal to the radius of the third chamfered surface 326 at the second connection position b, so that the first chamfered surface 322 can transition to the third chamfered surface 326 more smoothly, and the first chamfered surface 322 and the third chamfered surface 326 can form a continuous chamfered surface.

[0111] In some embodiments, the maximum radius of the third chamfered surface 326 is R3, satisfying: 0.1mm≤R3≤0.5mm.

[0112] In an embodiment where the third chamfered surface 326 has a constant diameter, the radius of the third chamfered surface 326 at any position in its extension direction is R3; in an embodiment where the third chamfered surface 326 has a variable diameter, taking the example that the radius of the third chamfered surface 326 gradually decreases from both ends to the middle position, the radius of at least one of the two ends of the third chamfered surface 326 is R3.

[0113] In some embodiments, please continue to refer to Figure 5 The side of the groove includes two first side surfaces 323 and two second side surfaces 325. The two first side surfaces 323 are arranged opposite each other along the first direction X, and the two second side surfaces 325 are arranged opposite each other along the second direction Y. The first direction X is perpendicular to the second direction Y.

[0114] Among them, the first direction X and the second direction Y are both perpendicular to the thickness direction Z of the cover body 31.

[0115] Both first side surfaces 323 are planar and parallel, and both second side surfaces 325 are planar and parallel.

[0116] In this embodiment, the side of the groove is roughly rectangular, so the groove 32 is also roughly rectangular, which is simple in structure and easy to form.

[0117] In some embodiments, please continue to refer to Figure 5 The distance between the two first side surfaces 323 along the first direction X is the first distance, and the distance between the two second side surfaces 325 along the second direction Y is the second distance. The first distance is less than the second distance.

[0118] The groove 32 is roughly rectangular, with a first side 323 extending along the length of the groove 32 and a second side 325 extending along the width of the groove 32. Understandably, the first direction X is the width direction of the groove 32, the second direction Y is the length direction of the groove 32, the first distance is the width of the groove 32, and the second distance is the length of the groove 32.

[0119] For example, the dimension of the first side surface 323 in the length direction of the groove 32 is greater than the dimension of the second side surface 325 in the width direction of the groove 32. The dimension of the second chamfered surface 324 in the length direction of the groove 32 is greater than the dimension of the third chamfered surface 326 in the width direction of the groove 32.

[0120] like Figure 5 As shown, in an embodiment where the radius of the first chamfered surface 322 gradually increases from both ends to the middle, the radius of the second chamfered surface 324 gradually decreases from both ends to the middle, and the radius of the third chamfered surface 326 gradually decreases from both ends to the middle, the radius of the end where the first chamfered surface 322 and the second chamfered surface 324 are connected may be greater than the radius of the end where the first chamfered surface 322 and the third chamfered surface 326 are connected.

[0121] In this embodiment, the groove 32 is roughly rectangular, and the pressure relief area 312 is also roughly rectangular, with a large pressure relief area.

[0122] In some embodiments, the first direction X is the length direction of the cover body 31, and the second direction Y is the width direction of the cover body 31.

[0123] For example, the cover body 31 is rectangular, the width direction of the groove 32 is consistent with the length direction of the cover body 31, and the length direction of the groove 32 is consistent with the width direction of the cover body 31.

[0124] Since the width direction of the groove 32 is consistent with the length direction of the cover body 31, and the length direction of the groove 32 is consistent with the width direction of the cover body 31, when the end cover 3 is subjected to pressure from the inside of the battery cell 10, the pressure relief area 312 is more likely to be damaged at the short side of the groove 32. When the end cover 3 is subjected to impact force on the outside, the pressure relief area 312 is more likely to be damaged at the long side of the groove 32. This makes the pressure relief area 312 more likely to be damaged at different locations under two different working conditions, thereby enhancing the impact resistance of the end cover 3 and improving the service life of the battery cell 10.

[0125] In some embodiments, please continue to refer to Figure 5 The cover body 31 is provided with pressure relief grooves 313, which are located in the pressure relief area 312.

[0126] The pressure relief mark 313 can be set on the bottom surface of the groove 32. The pressure relief mark 313 can be formed in a variety of ways, such as stamping, milling, etc.

[0127] The area where the pressure relief groove 313 is provided on the cover body 31 is thinner, so that when the pressure inside the battery cell 10 reaches the explosion pressure, the pressure relief area 312 will crack at the location where the pressure relief groove 313 is provided, so that pressure can be released from the pressure relief area 312.

[0128] In some embodiments, please continue to refer to Figure 5 The pressure relief mark 313 is a closed groove extending along a closed trajectory that connects the beginning and end.

[0129] A closed trajectory can have various shapes, such as circles, ellipses, rectangles, etc. For example, in... Figure 5 In the middle, the closed trajectory is roughly rectangular, and the area defined by the pressure relief mark 313 is also roughly rectangular. The length direction of the area defined by the pressure relief mark 313 is consistent with the length direction of the groove 32.

[0130] For example, the area defined by the pressure relief notch 313 is more than half the area of ​​the pressure relief zone 312.

[0131] In this embodiment, the pressure relief groove 313 is a closed groove. When the internal pressure of the battery cell 10 reaches the explosion pressure, the pressure relief area 312 can detach from the area defined by the pressure relief groove 313 to form an opening. The discharge inside the battery cell 10 can be discharged outward through the opening, which has a large pressure relief area and improves the pressure relief efficiency.

[0132] In other embodiments, the pressure relief groove 313 can be a non-closed groove, for example, the pressure relief groove 313 can be straight, U-shaped, C-shaped, etc.

[0133] In some embodiments, please refer to Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the structure of the end cap 3 provided in other embodiments of this application. Figure 7 for Figure 6 The exploded view of the end cap 3 is shown. The end cap 3 also includes a protective member 33, which is connected to the cap body 31 and covers the groove 32.

[0134] The protective element 33 can be a sheet-like structure, and its shape can be adapted to the shape of the groove 32. For example, if the groove 32 is rectangular, the protective element 33 can also be rectangular. The protective element 33 can be made of metallic materials, such as copper, iron, aluminum, steel, or aluminum alloy; it can also be made of non-metallic materials, such as rubber or plastic. The protective element 33 can be connected to the cover body 31 in various ways, such as by snap-fit ​​or adhesive bonding.

[0135] In this embodiment, the protective element 33 covers the groove 32, and the protective element 33 protects the pressure relief area 312, reducing the risk of damage to the pressure relief area 312 caused by foreign objects.

[0136] In some embodiments, please continue to refer to Figure 6 and Figure 7 The protective element 33 is attached to the first surface 3111. For example, the protective element 33 is bonded to the first surface 3111.

[0137] In an embodiment where the cover body 31 has a first chamfered surface 322, a second chamfered surface 324, and a third chamfered surface 326, the protective member 33 completely covers the first chamfered surface 322, the second chamfered surface 324, and the third chamfered surface 326.

[0138] In this embodiment, the protective member 33 is connected to the first surface 3111. This structure makes it easier to install the protective member 33. On the other hand, the protective member 33 can cover all the chamfered surfaces, providing better protection for the pressure relief area 312.

[0139] In some embodiments, please continue to refer to Figure 6 and Figure 7The cover body 31 is provided with an exhaust channel 314, which connects the inside of the groove 32 and the outside of the cover body 31.

[0140] The exhaust channel 314 can be a hole provided in the cover body 31, or one end of the hole can penetrate the side of the groove 32 and the other end can penetrate the first surface 3111. The exhaust channel 314 can also be a groove provided in the cover body 31. There can be one or more exhaust channels 314 on the cover body 31.

[0141] The exhaust channel 314 connects the inside of the groove 32 with the outside, so as to balance the air pressure inside the groove 32 and the outside, and reduce the risk of the protective part 33 falling off due to the increase of air pressure inside the groove 32.

[0142] In some embodiments, please refer to Figure 8 , Figure 8 for Figure 6 The enlarged view of the end cap 3 after removing the protective member 33 shows that the exhaust channel 314 is an exhaust groove provided on the cap body 31, and the exhaust groove penetrates the first surface 3111.

[0143] The exhaust groove can be set at the edge of the groove 32, for example, the exhaust groove is set corresponding to the first side 323 or the second side 325 of the groove 32; the exhaust groove can also be set at the corner of the groove 32, for example, the exhaust groove is set corresponding to the corner surface 321 of the groove 32.

[0144] For example, in Figure 8 In the middle, the exhaust groove is provided corresponding to the first side surface 323, and the exhaust groove extends to the second chamfered surface 324.

[0145] In this embodiment, the exhaust channel 314 is an exhaust groove provided on the cover body 31. The exhaust channel 314 can effectively connect the inside of the groove 32 with the outside world and is easy to form.

[0146] This application provides a battery cell 10, including a housing 1 and an end cap 3 provided in any of the above embodiments. The housing 1 has an opening, and the end cap body 31 closes the opening.

[0147] This application provides a battery 100, including a housing 20 and a battery cell 10 provided in any of the above embodiments, wherein the battery cell 10 is housed within the housing 20.

[0148] In some embodiments, the housing 20 has a bottom wall, and the end cap 3 is disposed on the side of the battery cell 10 facing the bottom wall.

[0149] The bottom wall is the wall located at the bottom of the box 20 under normal use. Taking the box 20 as an example, which includes a first part 201 and a second part 202, under normal use, the second part 202 covers the top of the first part 201, and the wall of the first part 201 facing away from the second part 202 is the bottom wall.

[0150] The end cap 3 is located on the side of the battery cell 10 facing the bottom wall, so that the battery cell 10 is in an inverted state.

[0151] This application also provides an electrical device, including the battery 100 provided in any of the above embodiments.

[0152] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0153] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An end cap, comprising: The cover body has a first surface; A groove is provided on the cover body to form a pressure relief area in the area where the groove is provided on the cover body. The groove is recessed from the first surface along the thickness direction of the cover body. The groove side includes a first side, a second side and a corner surface located at the corner of the groove. The second side is connected to the first side through the corner surface. The corner surface is connected to the first surface through a first chamfered surface, and the radius of the first chamfered surface gradually increases from both ends to the middle along the circumference of the groove.

2. The end cap of claim 1, wherein, The maximum radius of the first chamfered surface is R1, which satisfies: 0.5mm≤R1≤2mm.

3. The end cap of claim 1, wherein, The first side surface is connected to the first surface via a second chamfered surface; The maximum radius of the second chamfered surface is smaller than the maximum radius of the first chamfered surface.

4. The end cap according to claim 3, wherein, Along the circumference of the groove, both ends of the second chamfered surface are connected to the first chamfered surface, and the radius of the second chamfered surface gradually decreases from both ends to the middle position.

5. The end cap according to claim 3, wherein, The first chamfered surface and the second chamfered surface are connected at a first connection position, and the radius of the first chamfered surface at the first connection position is equal to the radius of the second chamfered surface at the first connection position.

6. The end cap according to claim 3, wherein, The maximum radius of the second chamfered surface is R2, which satisfies: 0.1mm≤R2≤0.5mm.

7. The end cap according to claim 3, wherein, The second side and the first side are located in different positions in the groove, and the second side is connected to the first surface through a third chamfered surface; The maximum radius of the third chamfered surface is smaller than the maximum radius of the first chamfered surface.

8. The end cap according to claim 7, wherein, Along the circumference of the groove, both ends of the third chamfered surface are connected to the first chamfered surface, and the radius of the third chamfered surface gradually decreases from both ends to the middle position.

9. The end cap according to claim 7, wherein, The first chamfered surface is connected to the third chamfered surface at a second connection position, and the radius of the first chamfered surface at the second connection position is equal to the radius of the third chamfered surface at the second connection position.

10. The end cap according to claim 7, wherein, The maximum radius of the third chamfered surface is R3, which satisfies: 0.1mm≤R3≤0.5mm.

11. The end cap according to claim 7, wherein, The groove side includes two first side surfaces and two second side surfaces. The two first side surfaces are arranged opposite each other along a first direction, and the two second side surfaces are arranged opposite each other along a second direction. The first direction is perpendicular to the second direction.

12. The end cap according to claim 11, wherein, The distance between the two first sides along the first direction is the first distance, and the distance between the two second sides along the second direction is the second distance, wherein the first distance is less than the second distance.

13. The end cap according to claim 12, wherein, The first direction is the length direction of the cover body, and the second direction is the width direction of the cover body.

14. The end cap according to any one of claims 1-13, wherein, The cover body is provided with pressure relief grooves, which are located in the pressure relief area.

15. The end cap according to claim 14, wherein, The pressure relief groove is a closed groove extending along a closed trajectory that connects the beginning and end.

16. The end cap according to any one of claims 1-13, wherein, The end cap also includes a protective element connected to the cap body and covering the groove.

17. The end cap according to claim 16, wherein, The protective element is attached to the first surface.

18. The end cap according to claim 16, wherein, The cover body is provided with an exhaust channel, which connects the inside of the groove and the outside of the cover body.

19. The end cap according to claim 18, wherein, The exhaust channel is an exhaust groove provided on the cover body, and the exhaust groove penetrates the first surface.

20. A single battery cell, comprising: The shell has an opening; The end cap as described in any one of claims 1-19, wherein the cap body closes the opening.

21. A battery, comprising: Box; The battery cell as described in claim 20 is housed within a casing.

22. The battery according to claim 21, wherein, The housing has a bottom wall, and the end cap is located on the side of the battery cell facing the bottom wall.

23. An electrical appliance comprising the battery as described in claim 21 or 22.

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