Cylindrical battery, battery pack and electric equipment

Abstract

The invention discloses a cylindrical battery, a battery pack and electric equipment. The cylindrical battery comprises a shell, an electrode assembly, an end cover, an anti-explosion sheet and a pore plate, the electrode assembly is accommodated in the case. The end cover is connected to the shell and covers the opening of the shell. The anti-explosion piece is at least partially arranged on the side, facing the electrode assembly, of the end cover. The pore plate is arranged on the side, facing the electrode assembly, of the anti-explosion piece and connected to the electrode assembly. And the pore plate and the anti-explosion sheet are welded to form a welding part. At least one side of the pore plate in the axial direction of the cylindrical battery is provided with a first concave part, and the first concave part extends along the periphery of the welding part. A cross-section of the first recess coplanar with a central axis of the cylindrical battery includes a first curve and a second curve. In the radial direction of the cylindrical battery, at least part of the first curve is located on the side, away from the welding part, of the reference line, and at least part of the second curve is located on the side, close to the welding part, of the reference line. The reference line passes through the bottommost part of the section and is parallel to the central axis, and the curvature of the first curve is greater than that of the second curve.

Description

Technical Field

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

[0002] With the rapid development of the lithium battery industry, its application in electric vehicles, electric bicycles, power tools and other fields has become a trend. Cylindrical batteries, due to their advantages such as good grouping and high stability, are highly favored and are gradually being used in various complex scenarios.

[0003] Due to the harsh operating conditions of various application scenarios, higher requirements are placed on the charge and discharge rate, service life, safety and other performance of cylindrical batteries. How to reduce the risk of cylindrical battery failure under extreme operating conditions and extend its service life has become a research and development direction for industry insiders. Summary of the Invention

[0004] The present application provides a cylindrical battery, a battery pack, and an electrical device, which are beneficial for reducing the risk of failure of the cylindrical battery under extreme working conditions and improving the service life.

[0005] In a first aspect, the present application provides a cylindrical battery comprising a housing, an electrode assembly, an end cap, an explosion-proof disc, and an orifice plate. The housing is provided with an opening. The electrode assembly is housed in the housing. The end cap is connected to the housing and covers the opening. The explosion-proof disc is at least partially located on the side of the end cap facing the electrode assembly. The orifice plate is located on the side of the explosion-proof disc facing the electrode assembly and is connected to the electrode assembly. The orifice plate is welded to the explosion-proof disc to form a weld. The orifice plate is provided with a first recess on at least one side of the cylindrical battery in the axial direction, the first recess extending along the periphery of the weld. A cross-section of the first recess coplanar with the central axis of the cylindrical battery includes a first curve and a second curve. In the radial direction of the cylindrical battery, at least a portion of the first curve is located on a side of a reference line away from the weld, and at least a portion of the second curve is located on a side of the reference line closer to the weld. The reference line passes through the bottom of the cross-section and is parallel to the central axis, and the curvature of the first curve is greater than the curvature of the second curve.

[0006] By setting a first curve with a larger curvature and a second curve with a smaller curvature, the present application can make it easier for the stress of the orifice plate to act on the part of the orifice plate corresponding to the second curve when the explosion-proof plate pulls the orifice plate through the welding part, thereby increasing the distance between the stress concentration point and the bottom of the first recess, which is conducive to dispersing the stress on the orifice plate, making the stress distribution more uniform, reducing the extent of the weakening of the off-voltage pressure value due to the weakening of the orifice plate material, reducing the risk of failure of the cylindrical battery under extreme working conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery.

[0007] In one or more of the above optional embodiments, the first recess is provided on the side of the orifice plate facing the explosion-proof disk. The explosion-proof disk covers the first recess in the axial direction, thereby reducing the risk of electrolyte or other impurities accumulating in the first recess and thus corroding the orifice plate.

[0008] In one or more of the above optional embodiments, the first curve and the second curve are both circular arcs, and the radius of the first curve is smaller than the radius of the second curve. The arc-shaped second curve has a more uniform curvature transition, which helps to more evenly distribute stress. Both the first curve and the second curve are circular arcs, which also helps to reduce the design difficulty or adjustment difficulty of the mold (e.g., a stamping mold).

[0009] In one or more optional embodiments above, the radius of the first curve is r1, the radius of the second curve is r2, 1.5≤r2 / r1≤4, 0.1mm≤r2≤0.4mm. r2 / r1 is greater than or equal to 1.5, the orifice plate is not easily stretched and deformed, which is conducive to dispersing the stress on the orifice plate, and the orifice plate is not easily broken, which is conducive to reducing the magnitude of the weakening of the off-voltage value due to the weakening of the orifice plate material, reducing the risk of failure of the cylindrical battery under extreme conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery. r2 / r1 is less than or equal to 4, which is conducive to reducing the radial size of the second curved surface in the cylindrical battery, thereby reducing the radial size of the entire first recess in the cylindrical battery, improving the structural strength of the orifice plate, and reducing the adverse effects of the weakening of the orifice plate material.

[0010] In one or more of the above optional embodiments, the first curve and the second curve are tangent. The connection between the first curved surface and the second curved surface is less likely to have sharp structures, and the portion of the orifice plate corresponding to the first recess is less likely to break, which helps to reduce the risk of the orifice plate being broken prematurely, reduces the risk of premature failure of the cylindrical battery, and extends the service life of the cylindrical battery.

[0011] In one or more optional embodiments above, the first curve and the second curve intersect, and the intersection of the first curve and the second curve is located at the bottom of the first recess. This is beneficial to reducing the radial size of the first curved surface of the cylindrical battery and increasing the radial size of the second curved surface of the cylindrical battery, thereby making the orifice plate less susceptible to stretching and deformation. The stress on the orifice plate is more likely to be concentrated at a position away from the bottom of the first recess, which is beneficial to dispersing the stress on the orifice plate, reducing the magnitude of the weakening of the off-voltage pressure value due to the weakening of the orifice plate material, reducing the risk of failure of the cylindrical battery under extreme operating conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery.

[0012] In one or more of the above optional embodiments, the first recess is disposed around the weld portion. This facilitates the complete breaking of the weak portion when the rupture disk deforms the orifice plate, thereby quickly severing the current loop. Furthermore, the orifice plate forms a flow path around the weld portion, thereby increasing the flow area and improving the uniformity of current density distribution.

[0013] In one or more of the above optional embodiments, the orifice plate includes a first portion and a second portion, the second portion being thinner than the first portion, the first recess being provided in the second portion, and the welded portion being connected to the second portion. This advantageously reduces welding power, heat generation, and quality. Furthermore, when the rupture disk flips and deforms, it pulls on the second portion, facilitating appropriate deformation of the second portion. This causes the portion of the orifice plate corresponding to the first recess to be severed, thereby disconnecting the current path and providing power-off protection for the cylindrical battery.

[0014] In one or more of the above optional embodiments, the thickness of the first portion is h1, the maximum thickness of the second portion is h2, 2.5 ≤ h1 / h2 ≤ 3.5, and 0.45 mm ≤ h1 ≤ 0.65 mm. h1 / h2 being greater than or equal to 2.5 facilitates reducing the thickness of the second portion 55 relative to the first portion 54, lowering the welding power and heat between the rupture disk and the orifice plate. h1 / h2 being less than or equal to 3.5 facilitates weakening the overall deformation capacity of the second portion, distributing the stress on the orifice plate, and reducing the magnitude of the reduction in the voltage-off pressure due to weakening of the orifice plate material.

[0015] In one or more optional embodiments above, along the axial direction of the cylindrical battery, a first weak portion is formed at a position of the second portion corresponding to the first recess, and the minimum thickness of the first weak portion is h3, 0.065mm≤h3≤0.075mm. h3 is greater than or equal to 0.065mm. On the one hand, it is beneficial to increase the flow area of ​​the first weak portion and improve the flow capacity. On the other hand, the first weak portion is less likely to break, which is beneficial to reduce the magnitude of the weakening of the cut-off pressure value due to the weakening of the orifice plate material. h3 is less than or equal to 0.075mm, which is beneficial to limit the maximum strength of the first weak portion, reduce the risk that the first weak portion cannot break under the set cut-off pressure value, and improve the power-off protection effect.

[0016] In one or more of the above optional embodiments, a second recess is provided on the side of the orifice plate facing the electrode assembly, and the portion of the orifice plate corresponding to the second recess forms the second portion; the first recess is located on the side of the second portion facing the rupture disk. This facilitates shortening the distance between the rupture disk and the second portion, reducing the difficulty of welding the rupture disk and the second portion.

[0017] In one or more optional embodiments above, the first curve and the second curve intersect, and along the radial direction of the cylindrical battery, the spacing between the reference line and the first part is d1, the radius of the cylindrical battery is r3, and 0.0118≤d1 / r3≤0.0167. d1 / r3 is greater than or equal to 0.0118, which is conducive to increasing the length of the second part between the first part and the reference line, reducing the degree of inclination of the second part when stretched, making the part of the orifice plate corresponding to the first recess less likely to break, and helping to reduce the adverse effects of weakening of the orifice plate material. d1 / r3 is less than or equal to 0.0167, which is conducive to limiting the length of the second part between the first part and the reference line, reducing the risk of the orifice plate failing to break under the set power-off pressure value, and improving the power-off protection effect.

[0018] In one or more optional embodiments above, the first curve and the second curve intersect, and along the radial direction of the cylindrical battery, the spacing between the reference line and the weld portion is d2, the radius of the cylindrical battery is r3, and 0.0118≤d2 / r3≤0.0143. d2 / r3 is greater than or equal to 0.0118, which helps to reduce the possibility of the explosion-proof disk and the orifice plate being welded to the first recess, thereby reducing the risk of poor welding. d2 / r3 is less than or equal to 0.0143, which helps to reduce the deformation of the area between the reference line and the weld portion of the second portion, and reduces the deformation of the entire orifice plate, making the orifice plate less likely to be broken, thereby reducing the magnitude of the weakening of the off-voltage pressure value due to the weakening of the orifice plate material, reducing the risk of failure of the cylindrical battery under extreme operating conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery.

[0019] In one or more of the above optional embodiments, the radius of the cylindrical battery is r3, 8.5mm≤r3≤27.5mm. The technical solution provided in the embodiment of the present application is applicable not only to cylindrical batteries with small diameters, but also to cylindrical batteries with large diameters, and has a wide range of applications.

[0020] In a second aspect, the present application provides a battery pack comprising a cylindrical battery according to any embodiment of the first aspect.

[0021] In a third aspect, the present application provides an electrical device comprising a battery pack according to any embodiment of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0023] Figure 1 A schematic diagram of the structure of a cylindrical battery provided in some embodiments of the present application;

[0024] Figure 2 for Figure 1 A front view of the cylindrical battery shown;

[0025] Figure 3 It is along Figure 2 A cross-sectional view taken along the direction AA;

[0026] Figure 4 for Figure 3 Schematic diagram of the enlarged structure of the middle area B;

[0027] Figure 5 for Figure 4 Schematic diagram of the enlarged structure of the middle area C;

[0028] Figure 6 A cross-sectional view of an orifice plate of a cylindrical battery provided in some embodiments of the present application;

[0029] Figure 7 yes Figure 6 Schematic diagram of the enlarged structure of the middle area D;

[0030] Figure 8 A schematic diagram of the structure of a battery pack provided in some embodiments of the present application;

[0031] Figure 9 It is a structural diagram of the electrical equipment provided in some embodiments of the present application.

[0032] The reference numerals for the specific embodiments are as follows:

[0033] DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0035] The terms "first," "second," "third," and the like in the specification and claims of this application or the accompanying drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship. 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.

[0036] 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.

[0037] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted" and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can 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.

[0038] In the embodiments of this application, "parallel" includes not only absolute parallelism but also approximately parallelism as commonly understood in engineering practice. Similarly, "perpendicular" also includes not only absolute perpendicularity but also approximately perpendicularity as commonly understood in engineering practice. For example, if the angle between two directions is 80°-90°, they are considered perpendicular; if the angle between two directions is 0°-10°, they are considered parallel.

[0039] An embodiment of the present application provides a cylindrical battery 1, which may be a lithium-ion battery, a sodium-lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, or other types of batteries.

[0040] Exemplarily, the cylindrical battery 1 is an 18650 battery, a 21700 battery, a 4680 battery or other types of cylindrical batteries.

[0041] In some embodiments, the cylindrical battery 1 is a secondary battery. After discharge, the secondary battery can be recharged to activate the active material and continue to be used.

[0042] In some embodiments, the cylindrical battery 1 includes a housing 10 having an opening 11. Exemplarily, the opening 11 is provided at one end of the cylindrical battery 1 in the axial direction X thereof.

[0043] In some embodiments, the shell 10 further includes a bottom wall 12 and a side wall 13 . The bottom wall 12 is arranged opposite to the opening 11 along the axial direction X. The side wall 13 is connected to the bottom wall 12 and encloses the bottom wall 12 to form a cylindrical space, which is open to the outside through the opening 11 .

[0044] In some embodiments, the cylindrical battery 1 further includes an electrode assembly 20 , which is housed in the housing 10 .

[0045] In some embodiments, the electrode assembly 20 is connected to the bottom wall 12 of the housing 10 , and the bottom wall 12 and the electrode assembly 20 are arranged along the axial direction X. Optionally, the electrode assembly 20 is electrically connected to the bottom wall 12 , and the bottom wall 12 forms an electrode terminal of the cylindrical battery 1 , thereby eliminating a traditional electrode terminal and simplifying the structure of the cylindrical battery 1 .

[0046] In some embodiments, the electrode assembly 20 includes a first electrode sheet and a second electrode sheet with opposite polarities. During the charge and discharge process of the cylindrical battery 1, active ions (e.g., lithium ions) are intercalated and released back and forth between the first electrode sheet and the second electrode sheet. One of the first electrode sheet and the second electrode sheet is a positive electrode sheet, and the other is a negative electrode sheet.

[0047] In some embodiments, the electrode assembly 20 includes a separator disposed between the first electrode sheet and the second electrode sheet, the separator insulating the first electrode sheet from the second electrode sheet. The separator can reduce the risk of short circuit between the positive and negative electrode sheets while allowing active ions to pass through.

[0048] In some embodiments, the first electrode sheet includes a first electrode sheet body and a first electrode tab, and the second electrode sheet includes a second electrode sheet body and a second electrode tab. The first electrode sheet body includes a first current collector and a first active material layer applied to the surface of the first current collector, and the first electrode tab is connected to the first current collector. The second electrode sheet body includes a second current collector and a second active material layer applied to the surface of the second current collector, and the second electrode tab is connected to the second current collector. One of the first electrode tab and the second electrode tab is a positive electrode tab, and the other is a negative electrode tab.

[0049] In some embodiments, the first tab and the first current collector are a single piece.

[0050] In some embodiments, the second tab and the second current collector are an integral piece.

[0051] In some embodiments, the cylindrical battery 1 further includes an end cap 30, which is connected to the housing 10 and covers the opening 11. The end cap 30 closes the opening 11, thereby forming a closed cylindrical space between the housing 10 and the end cap 30. The housing 10 and the end cap 30 are used to encapsulate components such as the electrode assembly 20 and the electrolyte.

[0052] In some embodiments, the housing 10 and the end cap 30 are made of steel, aluminum, alloy or other materials. The housing 10 and the end cap 30 can be made of the same or different materials.

[0053] In some embodiments, the end cap 30 is directly connected to the side wall 13 of the housing 10. In other embodiments, the end cap 30 is indirectly connected to the side wall 13 of the housing 10 through other structures.

[0054] In some embodiments, the end cap 30 is insulated from the side wall 13 and electrically connected to the electrode assembly 20, forming another electrode terminal of the cylindrical battery 1. For example, the end cap 30 and the bottom wall 12 can be electrically connected to the first and second electrode sheets of the electrode assembly 20, respectively.

[0055] In some embodiments, the end cap 30 is connected to the electrode assembly 20 , and in the axial direction X, the electrode assembly 20 is located between the end cap 30 and the bottom wall 12 .

[0056] In some embodiments, the cylindrical battery 1 includes an explosion-proof disc 40 , which is at least partially disposed on a side of the end cap 30 facing the electrode assembly 20 .

[0057] When the gas pressure inside the cylindrical battery 1 exceeds the upper limit that the explosion-proof disc 40 can withstand, the gas inside the cylindrical battery 1 can cause the explosion-proof disc 40 to flip and explode away from the electrode assembly 20, thereby achieving the purpose of power off and pressure relief, which is beneficial to reducing the risk of explosion of the cylindrical battery 1 due to excessive internal gas pressure and improving the safety performance of the cylindrical battery 1.

[0058] In some embodiments, the burst disk 40 is connected to the end cap 30. Alternatively, the burst disk 40 is connected to the end cap 30 by welding, riveting, or other suitable means.

[0059] In the axial direction X, the end cover 30 has a restrictive effect on the bursting disc 40, which helps to reduce the possibility of deformation of the end cover 30 when the bursting disc 40 flips over, and reduces the risk of excessive flipping stroke of the bursting disc 40 and untimely pressure relief.

[0060] In some embodiments, the burst disk 40 includes a pressure relief portion 41 and a second weakened portion 42 . The second weakened portion 42 extends along the periphery of the pressure relief portion 41 .

[0061] The second weak portion 42 is a portion of the bursting disc 40 that is easily ruptured, and the bursting disc 40 releases pressure by rupturing the second weak portion 42. Optionally, the second weak portion 42 is thinner than the pressure relief portion 41, so that it is easier to rupture than the pressure relief portion 41.

[0062] In some embodiments, the second weak portion 42 is an arc-shaped structure disposed on the periphery of the pressure relief portion 41. In other words, the two ends of the second weak portion 42 are not connected to form a non-enclosed structure. In other embodiments, the second weak portion 42 is an annular closed structure surrounding the pressure relief portion 41.

[0063] In some embodiments, the bursting disc 40 includes a connecting portion 43, and a second weak portion 42 connects the pressure relief portion 41 and the connecting portion 43. The connecting portion 43 is connected to the end cap 30 to enhance the restraining effect of the end cap 30 on the bursting disc 40, facilitating the flipping and pressure relief of the bursting disc 40.

[0064] In some embodiments, the cylindrical battery 1 includes a perforated plate 50, which is disposed on a side of the explosion-proof disc 40 facing the electrode assembly 20 and is connected to the electrode assembly 20. Along the axial direction X, the perforated plate 50 is located between the explosion-proof disc 40 and the electrode assembly 20.

[0065] In some embodiments, the orifice plate 50 is electrically connected to the electrode assembly 20. For example, the orifice plate 50 is electrically connected to the first tab or the second tab of the electrode assembly 20.

[0066] In some embodiments, the orifice plate 50 is directly electrically connected to the electrode assembly 20. In other embodiments, the orifice plate 50 is indirectly electrically connected to the electrode assembly 20 through a conductive component (eg, a current collecting plate).

[0067] In some embodiments, the orifice plate 50 is provided with a through hole 51. The through hole 51 extends through the orifice plate 50 in the axial direction X. The through hole 51 serves as a passage for gas flow. The gas inside the cylindrical battery 1 acts on the explosion-proof disk 40 through the through hole 51, which helps reduce the risk of explosion of the cylindrical battery 1 due to excessive internal gas pressure.

[0068] In some embodiments, the orifice plate 50 is welded to the burst disk 40 to form a weld W.

[0069] For example, the welding portion W is an annular structure arranged around the central axis a of the cylindrical battery 1, which is conducive to improving the uniformity of the current density distribution. Alternatively, the welding portion W is arc-shaped or strip-shaped.

[0070] In some embodiments, the welding method between the orifice plate 50 and the explosion-proof disk 40 includes but is not limited to laser welding, ultrasonic welding, etc.

[0071] In some embodiments, the orifice plate 50 is provided with a first recess 52 on at least one side in the axial direction X of the cylindrical battery 1 , and the first recess 52 extends along the outer circumference of the welding portion W.

[0072] In some embodiments, the first recess 52 is defined on the side of the orifice plate 50 facing the electrode assembly 20. In other embodiments, the first recess 52 is defined on the side of the orifice plate 50 facing the burst disk 40. In still other embodiments, the first recess 52 is defined on both the side of the orifice plate 50 facing the electrode assembly 20 and the side of the orifice plate 50 facing the burst disk 40.

[0073] Illustratively, the first recess 52 is an annular structure surrounding the welding portion W. Alternatively, the first recess 52 is an arc-shaped structure extending along the outer circumference of the welding portion W, and the first recess 52 is spaced apart at both ends along the circumference of the cylindrical battery 1 .

[0074] In some embodiments, the orifice plate 50 is a stamped part, and the first recess 52 is formed by stamping.

[0075] When the internal pressure of the cylindrical battery 1 increases, the explosion-proof disc 40 flips and deforms toward the side away from the electrode assembly 20, pulling the orifice plate 50 through the weld W, causing the orifice plate 50 to deform. When the internal pressure of the cylindrical battery 1 reaches the designed pressure value, the portion of the orifice plate 50 corresponding to the first recess 52 is broken, thereby disconnecting the current path and achieving power-off protection for the cylindrical battery 1.

[0076] In some embodiments, a cross section of the first recess 52 coplanar with the central axis a of the cylindrical battery 1 includes a first curve 521 and a second curve 522. Along the radial direction of the cylindrical battery 1, at least a portion of the first curve 521 is located on a side of the reference line b away from the weld W, and at least a portion of the second curve 522 is located on a side of the reference line b close to the weld W. The reference line b passes through the bottom of the cross section and is parallel to the central axis a. The curvature of the first curve 521 is greater than the curvature of the second curve 522.

[0077] The cross section of the first recess 52 coplanar with the central axis a of the cylindrical battery 1 refers to a cross section of the first recess 52 taken along a cutting plane passing through the central axis a of the cylindrical battery 1 , where an extension of the cross section passes through the central axis a.

[0078] The bottom of the cross section of the first recess 52 coplanar with the central axis a of the cylindrical battery 1 corresponds to the bottom of the first recess 52 , that is, the thinnest position of the aperture plate 50 . Reference line b passes through the bottom of the first recess 52 .

[0079] In some embodiments, along the axial direction X of the cylindrical battery 1 , a portion of the orifice plate 50 corresponding to the first recess 52 forms a first weak portion 53 . Exemplarily, the first weak portion 53 is formed by punching the first recess 52 out of the orifice plate 50 .

[0080] The bottom of the first concave portion 52 corresponds to the thinnest portion of the first weak portion 53 , and the reference line b passes through the thinnest portion of the first weak portion 53 .

[0081] In some embodiments, the first curved line 521 extends to a top edge of the first concave portion 52 away from the welding portion W. The second curved line 522 extends to a top edge of the first concave portion 52 close to the welding portion W.

[0082] In some embodiments, the first curve 521 and the second curve 522 intersect. In other embodiments, the first curve 521 and the second curve 522 are indirectly connected by a connecting line.

[0083] In some embodiments, the entire first curve 521 is located on the side of the reference line b away from the welding portion W. In other embodiments, a portion of the first curve 521 is located on the side of the reference line b away from the welding portion W, and another portion of the first curve 521 is located on the side of the reference line b close to the welding portion W.

[0084] In some embodiments, the entire second curve 522 is located on the side of the reference line b close to the weld W. In other embodiments, a portion of the second curve 522 is located on the side of the reference line b close to the weld W, and another portion of the second curve 522 is located on the side of the reference line b away from the weld W.

[0085] In some embodiments, the first concave portion 52 includes a first curved surface 523 and a second curved surface 524. The cross section of the first curved surface 523 coplanar with the central axis a of the cylindrical battery 1 is a first curve 521, and the cross section of the second curved surface 524 coplanar with the central axis a of the cylindrical battery 1 is a second curve 522.

[0086] The curvature of the first curve 521 is greater than that of the second curve 522 , and the curvature of the first curve 521 is greater than that of the second curve 522 . Accordingly, the curvature of the first curved surface 523 is greater than that of the second curved surface 524 .

[0087] Under extreme operating conditions such as high-rate discharge and cycling, the elastic modulus, yield strength, and tensile strength of the cylindrical battery 1 are easily weakened by high temperature, fatigue, and other factors. This can significantly reduce the cutoff pressure of the orifice plate 50, making the cylindrical battery 1 more susceptible to failure and shortening its service life. The cutoff pressure of the orifice plate 50 refers to the pressure in the cylindrical battery 1 when the explosion-proof disc 40 ruptures and flips, disconnecting the orifice plate 50 and thus severing the current circuit.

[0088] When the explosion-proof disk 40 pulls the orifice plate 50 through the welding portion W to deform, the stress on the orifice plate 50 is concentrated on the second curved surface 524 of the first recess 52 near the welding portion W, and is transferred to a position gradually approaching the bottom of the first recess 52 as the orifice plate 50 deforms.

[0089] In the embodiment of the present application, the first curve 521 of the first recess 52, located away from the weld W, has a greater degree of curvature, which facilitates reducing the radial dimension of the first curve 521 in the cylindrical battery 1. The second curve 522 of the first recess 52, located closer to the weld W, has a lesser degree of curvature, which facilitates increasing the radial dimension of the second curve 522 in the cylindrical battery 1. By providing a first curve 521 with a greater curvature and a second curve 522 with a smaller curvature, when the explosion-proof disk 40 pulls the orifice plate 50 through the weld W, the stress of the orifice plate 50 is more easily applied to the portion of the orifice plate 50 corresponding to the second curve 522. This increases the distance between the stress concentration point and the bottom of the first recess 52, which facilitates distributing the stress on the orifice plate 50 and achieving a more uniform stress distribution. This reduces the magnitude of the weakening of the cutoff pressure value due to weakening of the orifice plate 50 material, reduces the risk of failure of the cylindrical battery 1 under extreme operating conditions such as high-rate discharge and cycling, and extends the service life of the cylindrical battery 1.

[0090] In some embodiments, the first recess 52 is provided on the side of the orifice plate 50 facing the explosion-proof disk 40. In other words, the first recess 52 is provided on the side of the orifice plate 50 facing away from the electrode assembly 20. Along the axial direction X of the cylindrical battery 1, the orifice plate 50 is provided between the explosion-proof disk 40 and the electrode assembly 20.

[0091] The first recess 52 faces away from the electrode assembly 20 and toward the rupture disk 40. Along the axial direction X, the rupture disk 40 covers the first recess 52, which helps reduce the risk of electrolyte or other impurities accumulating in the first recess 52 and corroding the orifice plate 50.

[0092] In some embodiments, the first curve 521 and the second curve 522 are both arcs, and the radius of the first curve 521 is smaller than the radius of the second curve 522 .

[0093] In some embodiments, three points are selected on the first curve 521 using an image dimension measuring instrument (Keyence IM8000) and fitted into a circle. The radius of the circle is measured to be the radius of the first curve 521. Three points are selected on the second curve 522 and fitted into another circle. The radius of the other circle is measured to be the radius of the second curve 522.

[0094] The arc-shaped second curve 522 has a more uniform bend transition, which is conducive to more uniform stress distribution. The first curve 521 and the second curve 522 are both arcs, which is also conducive to reducing the design difficulty or adjustment difficulty of the mold (such as a stamping mold).

[0095] In some embodiments, the radius of the first curve 521 is r1, the radius of the second curve 522 is r2, and 1.5≤r2 / r1≤4.

[0096] Optionally, r2 / r1 is 1.5, 1.8, 2, 2.3, 2.5, 3, 3.3, 3.5, 3.8, 4 or any value in between any two of them.

[0097] In the embodiment of the present application, r2 / r1 is set to be greater than or equal to 1.5. This makes the orifice plate 50 less susceptible to tensile deformation, which helps to disperse the stress on the orifice plate 50. The orifice plate 50 is less likely to break, which helps to reduce the magnitude of the weakening of the cutoff pressure value due to weakening of the orifice plate 50 material, thereby reducing the risk of failure of the cylindrical battery 1 under extreme operating conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery 1. In the embodiment of the present application, r2 / r1 is set to be less than or equal to 4. This helps to reduce the radial dimension of the second curved surface 524 in the cylindrical battery 1, thereby reducing the radial dimension of the entire first recess 52 in the cylindrical battery 1, improving the structural strength of the orifice plate 50, and reducing the adverse effects caused by weakening of the orifice plate 50 material.

[0098] In some embodiments, 0.1 mm ≤ r2 ≤ 0.4 mm. Optionally, r2 is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, or any value therebetween.

[0099] In some embodiments, 0.025 mm ≤ r1 ≤ 0.26 mm. Optionally, r1 is 0.025 mm, 0.026 mm, 0.03 mm, 0.05 mm, 0.07 mm, 0.09 mm, 0.1 mm, 0.13 mm, 0.15 mm, 0.17 mm, 0.2 mm, 0.23 mm, 0.25 mm, 0.26 mm, or any value therebetween.

[0100] In some embodiments, the first curve 521 and the second curve 522 are tangent to each other. In other words, the first curve 521 and the second curve 522 are directly connected, and the connection between the first curve 521 and the second curve 522 is relatively smooth. Accordingly, the first curved surface 523 and the second curved surface 524 are smoothly connected.

[0101] The connection position of the first curved surface 523 and the second curved surface 524 is not prone to sharp structures, and the portion of the orifice plate 50 corresponding to the first recess 52 is not prone to breakage, which helps to reduce the risk of the orifice plate 50 being pulled apart prematurely, reduce the risk of premature failure of the cylindrical battery 1, and extend the service life of the cylindrical battery 1.

[0102] In some embodiments, the first curve 521 and the second curve 522 intersect each other, and the intersection of the first curve 521 and the second curve 522 is located at the bottom of the first concave portion 52 .

[0103] Optionally, the first curve 521 and the second curve 522 are tangent to each other, and the point of tangency between the first curve 521 and the second curve 522 is located at the bottom of the first concave portion 52. Reference line b passes through the point of tangency between the first curve 521 and the second curve 522. Accordingly, the connection position between the first curved surface 523 and the second curved surface 524 is located at the bottom of the first concave portion 52.

[0104] The first curve 521 is located entirely on the side of the reference line b away from the weld W, and the second curve 522 is located entirely on the side of the reference line b closer to the weld W. This helps reduce the radial dimension of the first curved surface 523 of the cylindrical battery 1 and increases the radial dimension of the second curved surface 524 of the cylindrical battery 1, thereby making the orifice plate 50 less susceptible to stretching and deformation. The stress on the orifice plate 50 is more likely to be concentrated at a position away from the bottom of the first recess 52, which helps to disperse the stress on the orifice plate 50, reduce the magnitude of the weakening of the cutoff pressure value due to weakening of the orifice plate 50 material, reduce the risk of failure of the cylindrical battery 1 under extreme operating conditions such as high-rate discharge and cycling, and extend the service life of the cylindrical battery 1.

[0105] In some embodiments, the first recess 52 is disposed around the welding portion W.

[0106] The first recess 52 is a closed annular structure surrounding the welding portion W. Exemplarily, the first recess 52 is circular, oval, square or other suitable shapes.

[0107] The orifice plate 50 is provided with a first recess 52 in a circle surrounding the welding portion W. The weak portion of the orifice plate 50 corresponding to the first recess 52 is annular. On the one hand, this is conducive to the weak portion being completely broken when the explosion-proof disk 40 pulls the orifice plate 50 to deform, thereby quickly cutting off the current circuit; on the other hand, the orifice plate 50 forms a flow path in a circle surrounding the welding portion W, which is conducive to increasing the flow area and improving the uniformity of the current density distribution.

[0108] In some embodiments, the orifice plate 50 includes a first portion 54 and a second portion 55 . The thickness of the second portion 55 is smaller than that of the first portion 54 . The first recess 52 is provided in the second portion 55 . The welding portion W is connected to the second portion 55 .

[0109] In some embodiments, a second recess 56 is provided on the orifice plate 50, thereby forming a second portion 55 in a portion of the orifice plate 50 corresponding to the second recess 56. For example, the second recess 56 is provided on the side of the orifice plate 50 facing the electrode assembly 20; or, the second recess 56 is provided on the side of the orifice plate 50 facing the burst disk 40; or, the second recess 56 is provided on both the side of the orifice plate 50 facing the electrode assembly 20 and the side of the orifice plate 50 facing the burst disk 40, such that, along the axial direction X of the cylindrical battery 1, the projection of the second recess 56 provided on the side of the orifice plate 50 facing the electrode assembly 20 and the projection of the second recess 56 provided on the side of the orifice plate 50 facing the burst disk 40 at least partially overlap.

[0110] In some embodiments, the second recess 56 is circular. The diameter of the second recess 56 is D3, 2.2 mm ≤ D3 ≤ 4.2 mm. Alternatively, D3 is 2.2 mm, 2.4 mm, 2.6 mm, 2.7 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4.0 mm, 4.2 mm, or any value therebetween.

[0111] The second portion 55 is relatively thin, the explosion-proof disc 40 is welded to the second portion 55, and the first recess 52 is provided in the second portion 55. On the one hand, this is conducive to reducing welding power, reducing welding heat generation, and improving welding effect; on the other hand, when the explosion-proof disc 40 flips and deforms, it pulls the second portion 55, which is conducive to the second portion 55 to produce appropriate deformation, so that the portion of the orifice plate 50 corresponding to the first recess 52 is pulled off, thereby disconnecting the current path and achieving power-off protection of the cylindrical battery 1.

[0112] In some embodiments, the thickness of the first portion 54 is h1, the maximum thickness of the second portion 55 is h2, and 2.5≤h1 / h2≤3.5.

[0113] In some embodiments, the first portion 54 has a uniform thickness structure, and h1 is the thickness measured at any position of the first portion 54. In other embodiments, the first portion 54 has a non-uniform thickness structure, and h1 is the average thickness of the first portion 54. For example, after preparing the metallographic structure of the end cap assembly, ten thicknesses of the first portion 54 are measured at ten positions of the first portion 54, and the average of the ten thicknesses is recorded as h1.

[0114] The second portion 55 includes a first weak portion 53 corresponding to the first recess 52 and a third portion 57 not corresponding to the first recess 52. The second portion 55 has a maximum thickness at the third portion 57 not corresponding to the first recess 52.

[0115] In some embodiments, the third portion 57 has a uniform thickness structure, and h2 is the thickness measured at any position of the third portion 57. In other embodiments, the third portion 57 has a non-uniform thickness structure, and h2 is the maximum thickness of the third portion 57.

[0116] Optionally, h1 / h2 can be 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 or any value in between any two of them.

[0117] In this embodiment, h1 / h2 is set to be greater than or equal to 2.5, which helps reduce the thickness of the second portion 55 relative to the first portion 54, lowering the welding power and heat between the explosion-proof disk 40 and the orifice plate 50. In this embodiment, h1 / h2 is set to be less than or equal to 3.5, which helps reduce the overall deformation capacity of the second portion 55, distributing the stress on the orifice plate 50, and reducing the extent of the reduction in the voltage-off pressure due to weakening of the orifice plate 50 material.

[0118] In some embodiments, 0.45 mm ≤ h1 ≤ 0.65 mm.

[0119] Optionally, h1 is 0.45 mm, 0.47 mm, 0.49 mm, 0.50 mm, 0.51 mm, 0.53 mm, 0.55 mm, 0.57 mm, 0.59 mm, 0.60 mm, 0.61 mm, 0.63 mm, 0.65 mm or any value in between any two of them.

[0120] In the embodiment of the present application, h1 is set to be greater than or equal to 0.45 mm, which is beneficial to improving the overall strength of the orifice plate 50 and reducing the adverse effects caused by weakening of the material of the orifice plate 50. In the embodiment of the present application, h1 is set to be less than or equal to 0.65 mm, which is beneficial to reducing the space occupied by the orifice plate 50 in the axial direction X and improving the energy density of the cylindrical battery 1.

[0121] In some embodiments, 0.15 mm ≤ h2 ≤ 0.2 mm. Optionally, h2 is 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, or any value therebetween.

[0122] In some embodiments, along the axial direction X of the cylindrical battery 1 , a first weak portion 53 is formed at a position of the second portion 55 corresponding to the first recess 52 . The minimum thickness of the first weak portion 53 is h3, and 0.065 mm ≤ h3 ≤ 0.075 mm.

[0123] Optionally, h3 is 0.065 mm, 0.066 mm, 0.067 mm, 0.068 mm, 0.069 mm, 0.070 mm, 0.071 mm, 0.072 mm, 0.073 mm, 0.074 mm, 0.075 mm or any value therebetween.

[0124] In the embodiment of the present application, h3 is set to be greater than or equal to 0.065 mm. This, on the one hand, helps increase the flow area of ​​the first weak portion 53 and improve the flow capacity. On the other hand, the first weak portion 53 is less likely to break, which helps reduce the extent of the weakening of the power-off pressure value due to weakening of the orifice plate 50 material. In the embodiment of the present application, h3 is set to be less than or equal to 0.075 mm, which helps limit the maximum strength of the first weak portion 53, reduces the risk of the first weak portion 53 failing to break at the set power-off pressure value, and improves the power-off protection effect.

[0125] In some embodiments, a second recess 56 is provided on the side of the orifice plate 50 facing the electrode assembly 20. Along the axial direction X of the cylindrical battery 1, the portion of the orifice plate 50 corresponding to the second recess 56 forms a second portion 55. The first recess 52 is located on the side of the second portion 55 facing the explosion-proof disk 40.

[0126] The second recess 56 is provided on the side of the orifice plate 50 facing the electrode assembly 20 , which helps to shorten the distance between the explosion-proof disc 40 and the second portion 55 and reduce the difficulty of welding between the explosion-proof disc 40 and the second portion 55 .

[0127] In some embodiments, the first curve 521 intersects the second curve 522. Along the radial direction of the cylindrical battery 1, the distance between the reference line b and the first portion 54 is d1, the radius of the cylindrical battery 1 is r3, and 0.0118≤d1 / r3≤0.0167.

[0128] In some embodiments, the second portion 55 is circular, and the first portion 54 is disposed around the second portion 55. The first recess 52 is annular, with the center of the first recess 52 coaxial with the center of the second portion 55. The radius of the second portion 55 is greater than the outer diameter of the first recess 52. The distance d1 between the reference line b and the first portion 54 is the difference between the radius of the second portion 55 and the radius of the circle containing the bottom of the first recess 52.

[0129] Optionally, d1 / r3 is 0.0118, 0.0121, 0.0124, 0.0127, 0.0130, 0.0135, 0.0140, 0.0145, 0.0150, 0.0155, 0.0160, 0.0163, 0.0165, 0.0167 or any value between any two thereof.

[0130] In some embodiments, 0.25 mm ≤ d1 ≤ 0.35 mm. Optionally, d1 is 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.30 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, or any value therebetween.

[0131] Reference line b passes through the bottom of first recess 52, and a distance d1 is provided between the bottom of first recess 52 and first portion 54. When burst disk 40 pulls second portion 55, the region of second portion 55 between first recess 52 and first portion 54 also deforms.

[0132] When the explosion-proof disk 40 deforms the orifice plate 50 by pulling it through the weld W, the first portion 54 has a larger thickness and a smaller deformation, while the second portion 55 tilts and deforms based on its connection point with the first portion 54. In this embodiment of the present application, setting d1 / r3 to be greater than or equal to 0.0118 helps increase the length of the second portion 55 between the first portion 54 and the reference line b, reduces the degree of tilt when the second portion 55 is stretched, and makes the portion of the orifice plate 50 corresponding to the first recess 52 less likely to break, thereby reducing the adverse effects of material weakening of the orifice plate 50. In this embodiment of the present application, setting d1 / r3 to be less than or equal to 0.0167 helps limit the length of the second portion 55 between the first portion 54 and the reference line b, reduces the risk of the orifice plate 50 failing to break under the set power-off pressure value, and improves the power-off protection effect.

[0133] In some embodiments, the first curve 521 intersects the second curve 522. Along the radial direction of the cylindrical battery 1, the distance between the reference line b and the welding portion W is d2, the radius of the cylindrical battery 1 is r3, and 0.0118≤d2 / r3≤0.0143.

[0134] In some embodiments, the welding portion W and the first recess 52 are both annular, and the center of the first recess 52 is coaxial with the center of the welding portion W. The inner diameter of the first recess 52 is greater than the outer diameter of the welding portion W. The distance d2 between the reference line b and the welding portion W is the difference between the radius of the circle on which the bottom of the first recess 52 is located and the outer diameter of the welding portion W.

[0135] Optionally, d2 / r3 is 0.0118, 0.0120, 0.0122, 0.0124, 0.0127, 0.0130, 0.0133, 0.0135, 0.0137, 0.0140, 0.0143 or any value between any two thereof.

[0136] In some embodiments, 0.25 mm ≤ d2 ≤ 0.3 mm. Optionally, d2 is 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.30 mm, or any value therebetween.

[0137] The reference line b passes through the bottom of the first recess 52 , and the distance between the bottom of the first recess 52 and the welding portion W is d2 .

[0138] The explosion-proof disc 40 is connected to the orifice plate 50 via the welding portion W. When the explosion-proof disc 40 pulls the second portion 55, the area of ​​the second portion 55 between the first recess 52 and the welding portion W will also be deformed.

[0139] In the embodiment of the present application, d2 / r3 is set to be greater than or equal to 0.0118, which is beneficial to reducing the possibility of the explosion-proof plate 40 and the orifice plate 50 being welded to the first recess 52 and reducing the risk of cold welding. In the embodiment of the present application, d2 / r3 is set to be less than or equal to 0.0143, which is beneficial to reducing the deformation of the area between the reference line b and the welding portion W of the second part 55. Due to the large degree of curvature of the first curve 521, the area between the reference line b and the first part 54 of the second part 55 is also not easily deformed. As a result, it is beneficial to reduce the deformation of the entire orifice plate 50, making the orifice plate 50 less likely to be broken, and it is beneficial to reduce the magnitude of the weakening of the cut-off pressure value due to the weakening of the orifice plate 50 material, reducing the risk of failure of the cylindrical battery 1 under extreme operating conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery 1.

[0140] In some embodiments, the pressure relief portion 41 includes a main body 411 and a protrusion 412. The protrusion 412 protrudes from a surface 411a of the main body 411 facing the orifice plate 50. The protrusion 412 is welded to the orifice plate 50 to form a weld W. A gap G is formed between the main body 411 and the orifice plate 50, and the through hole 51 of the orifice plate 50 is connected to the gap G.

[0141] In some embodiments, along the axial direction X of the cylindrical battery 1 , the projection of the second portion 55 and the projection of the convex portion 412 at least partially overlap. Optionally, the projection of the second portion 55 is located within the projection of the convex portion 412 .

[0142] In some embodiments, the cylindrical battery 1 includes an insulating member 60 disposed around the protrusion 412. The insulating member 60 and the protrusion 412 are spaced apart in the radial direction of the cylindrical battery 1. Along the axial direction X of the cylindrical battery 1, the insulating member 60 is sandwiched between the orifice plate 50 and the explosion-proof disk 40. The explosion-proof disk 40, the orifice plate 50, and the insulating member 60 enclose a gap G.

[0143] In some embodiments, along the axial direction X of the cylindrical battery 1 , the projection of the insulating member 60 and the projection of the through hole 51 are separated, which helps to reduce the blocking effect of the insulating member 60 on the exhaust air flow.

[0144] The convex portion 412 protrudes from the main body 411 in the direction close to the orifice plate 50, which not only facilitates the welding of the convex portion 412 and the orifice plate 50, but also forms a gap G between the main body 411 and the orifice plate 50. The gas discharged through the through hole 51 acts on the main body 411 through the gap G, which is conducive to the main body 411 flipping and deforming in the direction away from the orifice plate 50, thereby smoothly blasting and releasing pressure.

[0145] In some embodiments, the radius of the cylindrical battery 1 is r3, 8.5 mm ≤ r3 ≤ 27.5 mm.

[0146] Optionally, r3 is 8.5 mm, 9 mm, 10.5 mm, 12.5 mm, 15 mm, 17.5 mm, 20 mm, 23 mm, 25 mm, 27.5 mm or any value therebetween.

[0147] The technical solution provided in the embodiment of the present application is not only applicable to cylindrical batteries 1 with small diameters, but also to cylindrical batteries 1 with large diameters, and has a wide range of applications.

[0148] In the embodiment of the present application, the power-off pressure of the cylindrical battery and the temperature of the end cover when the power is off can be tested in the following manner.

[0149] Power-off stress test:

[0150] End cap assemblies were prepared for 21700 batteries and tested for power-off pressure using a high-temperature pressure tester (WG-5.04B) at an inflation rate of 0.1 MPa / s. The orifice plate dimensions were adjusted under the same power-off pressure conditions. 100 end cap assemblies were fabricated and tested, yielding the data shown in Table 1.

[0151] The end cap assemblies before and after adjustment were used to produce 50 cylindrical batteries in the same batch, each with a capacity of 4Ah, and divided into 5 groups.

[0152] The first group was placed in a constant temperature box at 25±2℃ for 1 hour, and then a circular hole with a diameter of 5mm was drilled in the bottom wall. The interior of the shell was inflated through the circular hole at the bottom of the shell at a speed of 0.1MPa / s until the orifice plate was pulled apart. The disconnection pressure was recorded as shown in the first column of Table 2.

[0153] The second through fifth groups were then placed in a constant temperature oven at 25±2°C for 1 hour. They were then discharged from 100% SOC to 0% SOC at rates of 5°C, 10°C, 15°C, and 20°C, respectively, and the end cap temperatures were measured. A hole was then dug in the bottom wall of the cylindrical battery. After the electrolyte had drained out, the battery was placed in an oven set to the end cap temperature and held there for 1 hour. The resulting burst test resulted in the short-circuit stress values ​​shown in Table 2.

[0154] Table 1

[0155]

[0156]

[0157] The first curve 521 and the second curve 522 of the cylindrical battery 1 provided in the embodiment of the present application and the cylindrical battery in the comparative example are both arcs.

[0158] Table 2

[0159] Discharge rate 5C 10C 15C 20C End cover temperature (℃) 25 48 82 160 228 Comparative ratio of cut-off pressure value (MPa) 1.22 1.13 0.97 0.83 0.66 Example Breaking Pressure Value (MPa) 1.22 1.17 1.03 0.93 0.80 Comparative ratio of the weakening range of the power-off pressure value 0％ 7.38％ 20.49％ 31.97％ 45.9％ Example: Cut-off pressure value weakening range 0％ 4.09％ 15.57％ 23.77％ 34.43％

[0160] The end cap temperature can represent the orifice plate temperature to a certain extent. In some test methods, the corrected orifice plate temperature can also be calculated based on the end cap temperature and the set compensation method.

[0161] The test data in Table 2 show that as the discharge rate of the cylindrical battery increases, the end cap temperature gradually increases, and accordingly, the orifice plate temperature gradually increases. The orifice plate cutoff pressure values ​​for both the comparative example and the embodiment of the present application gradually decrease. This shows that under high-rate discharge conditions, the orifice plate is easily affected by high temperatures, causing the material to weaken, which in turn weakens the orifice plate cutoff pressure value.

[0162] From Table 1 and Table 2, it can be seen that even if the minimum thickness of the first weak portion of the cylindrical battery in the embodiment of the present application is smaller than the minimum thickness of the first weak portion of the comparative example, under the same discharge rate, the orifice plate breakaway pressure value in the embodiment of the present application is greater than the orifice plate breakaway pressure value in the comparative example, and the weakening amplitude of the orifice plate breakaway pressure value in the embodiment of the present application is smaller than the weakening amplitude of the orifice plate breakaway pressure value in the comparative example.

[0163] The cylindrical battery 1 provided in the embodiment of the present application sets the curvature of the first curve 521 to be greater than the curvature of the second curve 522, which is beneficial to dispersing the stress on the orifice plate 50 and reducing the possibility of stress concentration at the bottom of the first recess 52, making the portion of the orifice plate 50 corresponding to the first recess 52 less likely to be broken, which is beneficial to reducing the extent of the weakening of the off-voltage pressure value due to the weakening of the orifice plate 50 material, reducing the risk of failure of the cylindrical battery 1 under extreme operating conditions such as high-rate discharge and cycling, and extending the service life of the cylindrical battery 1.

[0164] According to the second aspect of this application, referring to Figure 8 , an embodiment of the present application further provides a battery pack 100, the battery pack 100 including a plurality of cylindrical batteries 1 provided according to any embodiment of the present application.

[0165] In some embodiments, the battery pack 100 further includes a plurality of busbars that connect the cylindrical batteries 1. At least two cylindrical batteries 1 can be connected in series or in parallel via the busbars.

[0166] According to the third aspect of this application, referring to Figure 9 The embodiment of the present application further provides an electric device 1000, which includes the battery pack 100 provided in any embodiment of the present application. The battery pack 100 can provide electric energy for the electric device 1000.

[0167] The electrical device 1000 of the present embodiment may be a portable device, an electric toy, a drone, an electric tool, an energy storage system, or the like. The electric tool includes metal cutting tools, cleaning tools, and the like, such as an electric drill, an electric wrench, a vacuum cleaner, a robot vacuum, and the like. The present embodiment does not impose any particular restrictions on the above-mentioned electrical devices.

[0168] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A cylindrical battery, characterized in that: include: a housing having an opening; an electrode assembly, housed in the housing; an end cover connected to the housing and covering the opening; an explosion-proof disk, at least partially disposed on a side of the end cap facing the electrode assembly; as well as an orifice plate, disposed on a side of the explosion-proof disc facing the electrode assembly and connected to the electrode assembly, the orifice plate being welded to the explosion-proof disc to form a weld, the orifice plate being provided with a first recess on at least one side in the axial direction of the cylindrical battery, the first recess extending along the outer periphery of the weld; The cross-section of the first recessed portion coplanar with the central axis of the cylindrical battery includes a first curve and a second curve. Along the radial direction of the cylindrical battery, at least a portion of the first curve is located on a side of a reference line away from the welding portion, and at least a portion of the second curve is located on a side of the reference line close to the welding portion. The reference line passes through the bottom of the cross-section and is parallel to the central axis. The curvature of the first curve is greater than the curvature of the second curve.

2. The cylindrical battery according to claim 1, characterized in that: The first recess is provided on a side of the orifice plate facing the explosion-proof disk.

3. The cylindrical battery according to claim 1 or 2, characterized in that: The first curve and the second curve are both circular arcs, and the radius of the first curve is smaller than the radius of the second curve.

4. The cylindrical battery according to claim 3, characterized in that: The radius of the first curve is r1, the radius of the second curve is r2, 1.5≤r2 / r1≤4, 0.1mm≤r2≤0.4mm.

5. The cylindrical battery according to any one of claims 1 to 4, characterized in that: The first curve and the second curve are tangent to each other.

6. The cylindrical battery according to any one of claims 1 to 5, characterized in that: The first curve and the second curve intersect, and an intersection point of the first curve and the second curve is located at the bottom of the first concave portion.

7. The cylindrical battery according to any one of claims 1 to 6, characterized in that: The first recess is arranged around the welding portion.

8. The cylindrical battery according to any one of claims 1 to 7, characterized in that: The orifice plate includes a first portion and a second portion, the thickness of the second portion is smaller than that of the first portion, the first recess is provided in the second portion, and the welding portion is connected to the second portion.

9. The cylindrical battery according to claim 8, characterized in that: The thickness of the first part is h1, the maximum thickness of the second part is h2, 2.5≤h1 / h2≤3.5, 0.45mm≤h1≤0.65mm.

10. The cylindrical battery according to claim 8 or 9, characterized in that: Along the axial direction of the cylindrical battery, a first weak portion is formed at a position of the second portion corresponding to the first recess, and a minimum thickness of the first weak portion is h3, where 0.065 mm ≤ h3 ≤ 0.075 mm.

11. The cylindrical battery according to any one of claims 8 to 10, characterized in that: A second recess is provided on a side of the orifice plate facing the electrode assembly, and a portion of the orifice plate corresponding to the second recess forms the second portion; The first recess is located on a side of the second portion facing the burst disk.

12. The cylindrical battery according to any one of claims 8 to 11, characterized in that: The first curve and the second curve intersect, and along the radial direction of the cylindrical battery, the distance between the reference line and the first portion is d1, the radius of the cylindrical battery is r3, and 0.0118≤d1 / r3≤0.0167.

13. The cylindrical battery according to any one of claims 1 to 12, characterized in that: The first curve and the second curve intersect, and along the radial direction of the cylindrical battery, the distance between the reference line and the welding portion is d2, the radius of the cylindrical battery is r3, and 0.0118≤d2 / r3≤0.0143.

14. The cylindrical battery according to any one of claims 1 to 13, characterized in that: The radius of the cylindrical battery is r3, 8.5mm≤r3≤27.5mm.

15. A battery pack, characterized in that: The invention comprises a plurality of cylindrical batteries according to any one of claims 1 to 14.

16. An electrical device, characterized in that: Comprising the battery pack according to claim 15.

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