Secondary battery, battery pack, and electronic device

Abstract

The present application provides a secondary battery, comprising: a housing having an accommodating cavity, one end of the housing along the height direction of the secondary battery being provided with an opening, the housing being provided with a hemming portion extending inward along the radial direction of the housing at the peripheral side of the opening, and a crimping portion protruding inward at a position adjacent to the opening; the electrode assembly is accommodated in the accommodating cavity; the cover plate blocks the containing cavity and is provided with a clamping part clamped between the hemming part and the crimping part, the face, facing the electrode assembly, of the clamping part serves as a reference face, the cover plate is provided with a boss protruding towards the electrode assembly compared with the reference face, and the orthographic projection, on the boss, of the center hole of the electrode assembly is at least partially overlapped with the boss; the protruding height of the side, close to the electrode assembly, of the boss is H mm compared with the datum plane, and H ranges from 0.4 to 0.8. According to the secondary battery, the battery pack and the electronic device provided by the invention, at least the swelling amount of the center of an electrode assembly when the electrode assembly generates gas can be reduced, and a cover plate can be uniformly stressed when the electrode assembly generates gas.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of secondary battery, battery pack and electronic device. BACKGROUND

[0002] In the field of new energy power battery, the application of secondary battery is more and more widely, such as secondary battery (for example, lithium ion battery) can be applied to car, energy storage, mobile phone, tablet computer, wearable device, mobile power supply, electronic cigarette, digital product, electric tool, power device, energy storage device and other electronic devices. One of the secondary battery is cylindrical battery, which includes a shell and an electrode assembly, the electrode assembly includes a positive electrode sheet, a first separator, a negative electrode sheet and a second separator, which are stacked in sequence and then wound into an electrode assembly, and then packaged in the shell. However, the existing secondary battery still needs to be further improved in some aspects. SUMMARY

[0003] In view of the problems in the related art, the purpose of the utility model is to provide a secondary battery, a battery pack and an electronic device, so as to at least reduce the expansion amount of the electrode assembly center when the electrode assembly produces gas, and also make the cover plate bear uniform stress when facing the gas produced by the electrode assembly.

[0004] To achieve the above-mentioned purpose, the embodiment of the present application provides a kind of secondary battery, comprising: shell, with accommodating cavity, the one end of shell along the height direction of secondary battery has opening, shell is equipped with the curling edge portion that extends along the radial direction of shell inward in the circumferential side of opening, it is also equipped with the crimping portion that protrudes inward in the position adjacent to opening;Electrode assembly is contained in accommodating cavity;Cover plate, cover plate blocks accommodating cavity, and has clamping portion clamped between curling edge portion and crimping portion, wherein, with the face of clamping portion as reference surface, cover plate has boss that protrudes towards electrode assembly compared with reference surface, wherein, the central hole of electrode assembly is at least partially overlapped on boss by orthographic projection on boss, the protrusion height of boss near electrode assembly side compared with reference surface is H mm, the value range of H is 0.4-0.8.

[0005] In some embodiments, the orthographic projection of the central hole of the electrode assembly on the boss falls in the surrounding area of the side of the boss near the electrode assembly;The value range of H is 0.5-0.7;Cover plate is also provided with protrusion that protrudes in the direction away from electrode assembly and compared with the face of clamping portion away from electrode assembly, the protrusion is located in the area between clamping portion and boss, the shortest distance of the surface of protrusion away from electrode assembly to reference surface is S mm, the value range of S is 0.8-1.2;The maximum length of protrusion in radial direction is L1 mm, the value range of L1 is 1-2, the maximum width of protrusion perpendicular to the direction of length is W1 mm, the value range of W1 is 3-6.

[0006] In some embodiments, L1 is in the range of 1.5-2, W1 is in the range of 4-5, and 0.5≤H / S≤0.7 is satisfied.

[0007] In some embodiments, the cover plate is provided with an explosion-proof valve, which is a notch on the side of the cover plate facing the electrode assembly; in a virtual plane perpendicular to the height direction, the orthogonal projection of the boss is located in the area surrounded by the orthogonal projection of the explosion-proof valve and does not overlap with each other.

[0008] In some embodiments, the protruding height of the boss is consistent with the thickness of the shell.

[0009] In some embodiments, the boss is punched on the cover plate facing the electrode assembly; the cover plate is integrally punched.

[0010] In some embodiments, the surface of the boss close to the electrode assembly is a circular surface, and the diameter of the circular surface is D mm, and D is in the range of 5-7.

[0011] In some embodiments, the secondary battery further comprises: a plastic part surrounding the periphery of the cover plate to insulate and seal the cover plate and the shell; the first current collector is arranged between the electrode assembly and the cover plate and is electrically connected with the shell, the connecting piece of the first current collector is located on the side of the crimping part facing the electrode assembly and is welded with the crimping part, and the welding mark is located in the shell; the secondary battery is a cylindrical battery.

[0012] Embodiments of the present application also provide a battery pack comprising any of the above secondary batteries.

[0013] Embodiments of the present application also provide an electronic device comprising any of the above secondary batteries.

[0014] The beneficial technical effects of the present application are:

[0015] In the present application, the boss protruding towards the electrode assembly compared to the reference surface, wherein the orthogonal projection of the center hole of the electrode assembly on the boss at least partially overlaps with the boss, and the protruding height of the boss compared to the reference surface is H mm, H is in the range of 0.5-0.7, which can at least reduce the expansion amount of the center of the electrode assembly when the electrode assembly produces gas, and can also make the cover plate bear force evenly when facing the gas produced by the electrode assembly. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0017] Figure 1A schematic diagram of a vehicle is shown.

[0018] Figure 2A A perspective view of a secondary battery according to embodiments of the present application is shown.

[0019] Figure 2B A cross-sectional view of a cover plate of a secondary battery according to embodiments of the present application is shown.

[0020] Figure 2C A partial cross-sectional view of an opposite end of a secondary battery from the cover plate is shown.

[0021] Figure 3 A top view of a cover plate of a secondary battery according to embodiments of the present application is shown.

[0022] Figure 4 A stress cloud map of a protrusion having a protrusion height of 0.4mm to 0.8mm when subjected to an internal gas impact force is shown.

[0023] Figure 5 A cross-sectional view of a cover plate of a secondary battery according to embodiments of the present application is shown.

[0024] Figure 6 A perspective view of a secondary battery according to embodiments of the present application is shown. Figure 5 An enlarged view at dotted box F. DETAILED DESCRIPTION

[0025] For better understanding of the spirit of the embodiments of the present application, the following further describes the embodiments of the present application in combination with some preferred embodiments of the present application.

[0026] Embodiments of the present application will be described in detail below. Throughout the present application, the same or similar components and components having the same or similar functions are denoted by like reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative in nature, diagrammatic in nature, and are provided to provide a basic understanding of the present application. The embodiments of the present application should not be interpreted as limiting the present application.

[0027] As used herein, the terms "approximately", "substantially", "essentially", and "about" are used to describe and account for small variations. When used in connection with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs exactly, as well as instances in which the event or circumstance occurs approximately.

[0028] In this description, relative terms such as "central," "longitudinal," "lateral," "forward," "rearward," "rightward," "leftward," "internal," "external," "lower," "higher," "horizontal," "vertical," "above," "below," "top," "bottom," and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures.

[0029] For convenience, "first," "second," "third," etc. can be used herein to distinguish between various components of one figure or series of figures. "First," "second," "third," etc. are not intended to denote corresponding components unless so specified.

[0030] Referring to Figure 1 , the following embodiments are described for the convenience of illustration, taking the electronic device as a vehicle 1000. It is not difficult to understand that the electronic device provided by the present application is not limited to a vehicle, and the electronic device can also be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc.

[0031] The vehicle 1000 is internally provided with a battery pack 1002, which can be arranged at the bottom of the vehicle body 1001 (as shown in Figure 1 ), or at the head, or at the tail, or at any other appropriate position. The battery pack 1002 can be used for power supply of the vehicle 1000, for example, the battery pack 1002 can be used as an operating power source or a driving power source of the vehicle 1000. The battery pack 1002 can include a plurality of secondary batteries (such as the secondary battery 100 in Figure 2A ) and a housing accommodating the plurality of secondary batteries.

[0032] Figure 2A A perspective view of the secondary battery 100 according to an embodiment of the present application is shown. Figure 2B is a cross-sectional view of the cover plate of the secondary battery according to an embodiment of the present application. Referring to Figure 2A and Figure 2B , the housing 200 of the secondary battery 100 includes an end wall 220 and a side wall 210 surrounding the end wall 220, an end of the side wall 210 away from the end wall 220 is formed with an opening 205, the opening 205 is located at one end of the housing 200 along the height direction H of the secondary battery 100, and the electrode assembly 120 is accommodated in the accommodation cavity of the housing 200. The secondary battery 100 can be a cylindrical battery. The electrode assembly 120 of the secondary battery 100 is mainly formed by winding the positive electrode tab and the negative electrode tab, and a separator is usually arranged between the positive electrode tab and the negative electrode tab.

[0033] The shell 200 is provided with a crimping portion 32 extending radially inwardly of the shell 200 at the periphery of the opening 205, and a press-fit portion 31 protruding inwardly adjacent to the opening 205. The secondary battery 100 is further provided with a cover plate 300 sealing the accommodation cavity. The press-fit portion 31 and the crimping portion 32 can jointly clamp the cover plate 300. The cover plate 300 is provided with a clamping portion 3101 clamped between the crimping portion 32 and the press-fit portion 31. In some embodiments, the secondary battery 100 can further include a plastic member 80 surrounding the periphery of the cover plate 300 to insulate and seal the cover plate 300 and the shell 200. See Figure 2B The secondary battery 100 further includes a first current collector 140 between the electrode assembly 120 and the cover plate 300. The first current collector 140 is electrically connected to the shell 200, and in particular, the first current collector 140 can electrically connect the shell 200 and the electrode assembly 120, so that the shell 200 is charged (e.g. negatively charged). The first current collector 140 is provided with a connecting tab 142 welded to the press-fit portion 31. It can be appreciated that the first current collector 140 can be provided with a plurality of connecting tabs 142, for example, four connecting tabs 142. The connecting tab 142 of the first current collector 140 is welded to the side of the press-fit portion 31 facing the electrode assembly 120, and the welding mark 144 formed by the welding is located inside the shell 200. That is, the welding is performed from inside the shell to outside the shell. Since the first current collector 140 is relatively thin, and the shell 200 is generally thick, welding from inside to outside makes the welding mark 144 located inside the shell 200, so that the relatively thin first current collector 140 can make it easier to perform penetration welding, and can avoid the problem of false welding.

[0034] Figure 2C A partial cross-sectional view of the secondary battery is shown, and the cover plate 300 is located at the opposite end of the secondary battery. See Figure 2C An end wall 202 of the shell 200 is shown, and a pole 160 is provided at the end wall 202. In particular, the end wall 202 is provided with a pole hole 204. The pole 160 includes a columnar portion 162 extending through the pole hole 204, and a riveting portion 164 connected to one end of the columnar portion 162 and folded outwardly of the end wall 202. The pole 160 can be electrically connected to the electrode assembly 120 by a second current collector 340, so that the pole 160 is charged (e.g. positively charged).

[0035] The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the positive electrode current collector; the positive electrode current collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area, the positive electrode coating area is coated with the positive electrode active material layer, and the positive electrode tab is not coated with the positive electrode active material layer. The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area, the negative electrode coating area is coated with the negative electrode active material layer, and the negative electrode tab is not coated with the negative electrode active material layer. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate. The material of the negative electrode current collector can be copper, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be carbon or silicon. The material of the separator can be PP or PE. In order to protect and insulate the electrode assembly, an insulating film can also be wrapped outside the electrode assembly, and the insulating film can be synthesized from PP, PE, PET, PVC, or other high polymer materials.

[0036] In some embodiments, the material of the shell 200 is, for example, copper, iron, aluminum, steel, aluminum alloy, etc., preferably steel (for example, SPCC), which has higher strength. In order to prevent the shell 200 from rusting during long-term use, a layer of anti-rust material such as pre-plated nickel can also be plated on the surface of the shell 200. If there is an uncured area of the insulating film in the prior art, the secondary battery 100 generates corrosive gas through electrochemical reaction, which causes the shell 200 to be corroded and the inner wall to be blackened. The possible reason is that, in the prior art, because the positive and negative electrodes are corroded, the corrosive liquid passes through the area without the insulating film and contacts the shell, which directly causes the corrosion of the shell. The embodiment of the present application avoids this situation. The electrode assembly 120 is provided with a first tab and a second tab at the two ends thereof respectively facing the opening and the end wall 220 of the secondary battery 100, and the polarities of the first tab and the second tab are opposite, wherein the first tab is a negative tab and faces the opening side. It should be noted that, in other embodiments, the first tab can also be a positive tab, and the second tab can be a negative tab.

[0037] Figure 3 A top view of the cover plate 300 of the secondary battery 100 of the embodiment of the present application is shown. Now, the cover plate 300 will be described in combination with the secondary battery 100. Figure 2A and Figure 3With reference to the drawings, it will be understood that the cover plate 300 closes the opening to enclose the electrode assembly 120 inside the case 200. The periphery of the cover plate 300 is the clamping portion 3101 clamped between the crimping portion 31 and the crimping portion 32. The cover plate 300 is provided with a rupture disc 303, which is a notch on the side of the cover plate 300 facing the electrode assembly 120. The material of the cover plate 300 can be preferably steel, or other metal material that can be used. The surface of the cover plate 300 is pre-plated with nickel to prevent rusting or corrosion. However, the pre-plated nickel at the notch can be damaged, so the notch is more prone to rusting or corrosion. If the notch is provided on the side of the cover plate 300 facing away from the electrode assembly 120 (i.e. towards the outside of the secondary battery), the notch will be in contact with air, thus corroding the cover plate. Therefore, by providing the notch on the side of the cover plate 300 facing the electrode assembly 120, the cover plate can be prevented from being corroded.

[0038] It will be understood that Figure 3 Fig. 4 shows a plan view of the cover plate 300 in the direction of closing the opening of the cover plate 300.

[0039] Figure 5 Fig. 5 shows a sectional view of an embodiment of the cover plate. In combination with Figure 2B and Figure 5It can be understood that, taking the face of the clamping portion 3101 facing the electrode assembly 120 as a reference face A, the cover plate 300 has a boss 320 protruding toward the electrode assembly 120 compared to the reference face A, and the orthogonal projection of the central hole K of the electrode assembly 120 on the boss 320 at least partially overlaps the boss 320. Preferably, the orthogonal projection of the central hole K of the electrode assembly 120 on the boss 320 falls in the surrounding area of the boss 320 on the side close to the electrode assembly 120, that is, the boss 320 has a larger area than the central hole K of the electrode assembly 120 and can cover the central hole K of the electrode assembly 120. It can be understood that, in some embodiments, in a virtual plane perpendicular to the axis of the shell, the orthogonal projection of the boss 320 is located in the area surrounded by the orthogonal projection of the explosion-proof valve 303 and does not overlap each other. The boss 320 can be spaced apart from the central hole K of the electrode assembly 120 by a distance. The protrusion height of the boss 320 on the side close to the electrode assembly 120 compared to the reference face A is Hmm, and the value range of H is 0.4-0.8, preferably, the value range of H is 0.5-0.7. The boss 320 thus arranged can reduce the expansion amount of the center of the electrode assembly when the electrode assembly produces gas, and also make the force on the cover plate 300 uniform when facing the gas produced by the electrode assembly. Since the secondary battery needs to be charged and discharged during the battery life test (EOL), a large amount of gas will be produced in the electrode assembly of the secondary battery, causing the electrode assembly to swell. Since the most gas is produced at the positive center of the electrode assembly, that is, the position of the central hole, the central hole of the electrode assembly is the most swollen position. At the same time, a large amount of gas produced in the central hole of the electrode assembly impacts the cover plate located above the electrode assembly, so that the center position of the cover plate, that is, the position corresponding to the central hole K of the electrode assembly 120, receives a larger force than other positions of the cover plate. The boss protruding toward the electrode assembly 120, and the orthogonal projection of the central hole K of the electrode assembly 120 on the boss 320 at least partially overlaps the boss 320, and the protrusion height of the boss 320 on the side close to the electrode assembly 120 compared to the reference face 3101 is H mm, and the value range of H is 0.4-0.8. The boss 320 thus arranged can reduce the expansion amount of the center of the electrode assembly during the battery life test, and the gas flow generated flows to the surrounding of the center of the cover plate 300, so that the force on the cover plate 300 is uniform when facing the gas produced by the electrode assembly. Moreover, the boss 320 protrudes toward the electrode assembly 120, that is, the center of the cover plate 300 is recessed, which does not additionally increase the height of the secondary battery 100.

[0040] Continue to engage Figure 3 And Figure 5To describe, in some embodiments, the cover plate 300 is further provided with a protrusion 330 that protrudes in a direction away from the electrode assembly 120 and compared to the surface of the clamping portion 3101 that is away from the electrode assembly 120. It can be understood that the protrusion direction of the protrusion 330 is opposite to the protrusion direction of the boss 320, and the protrusion 330 is located in the area between the clamping portion 3101 and the boss 320. The shortest distance between the surface 331 of the protrusion 320 that is away from the electrode assembly 120 and the reference plane A is S mm, and the value range of S is 0.8-1.2, and S is preferably 1 mm. See Figure 3 The maximum length of the protrusion 330 in the radial direction of the shell is L1 mm, and the value range of L1 is 1-2. The maximum width of the protrusion 330 in the direction perpendicular to the length of the protrusion 330 is W1 mm, and the value range of W1 is 3-6.

[0041] Preferably, the value range of L1 is 1.5-2, the value range of W1 is 4-5, and 0.5≤H / S≤0.7. Accordingly, the present invention can make the cover plate 300 more evenly stressed when facing the electrode assembly 120 to generate gas.

[0042] In some embodiments, the shortest distance between the surface 331 of the protrusion 330 facing away from the electrode assembly 120 and the reference plane A is S mm, and the value of S is in the range of 0.8-1.2. It can be understood that the boss 320 is formed by stamping the cover plate 300 toward the electrode assembly 120, and the protrusion 330 is formed by stamping the cover plate 300 away from the electrode assembly 120. The cover plate 300 is stamped integrally. Preferably, the protrusion 330 can serve as a reinforcing rib. Figure 3 Four are shown in the figure, but are not limited thereto, and are arranged circumferentially around the boss 320.

[0043] Also refer to Figure 4 , Figure 4 The stress cloud diagram of the boss 320 with a protrusion height of 0.4mm to 0.8mm when subjected to the impact force of the internal gas is shown. For ease of understanding, a 1 / 4 cross-section of the boss with a protrusion height of 0.4mm to 0.8mm and part of the shell 200 are shown, and the explosion-proof valve on the cover plate 300 is omitted. Similar to the arrangement of the secondary battery 100 of the embodiment of the present application, the clamping portion 3101 of the cover plate 300 is clamped between the curling portion 32 and the crimping portion 31, so that the clamping portion 3101 faces the electrode assembly ( Figure 4 The surface (not shown) is the reference surface A. It can be understood that the electrode assembly is located in the accommodating cavity of the shell 200, and the cover plate 300 has a boss 320 that protrudes toward the electrode assembly compared to the reference surface A. Figure 4In the figure, the red / yellow area represents a high stress area, while the blue / green area represents a smaller stress area, and the area with a smaller stress difference is closer to the color block in the upper left corner, and the size of the stress can reflect the size of the force. It can be understood that, in the Figure 4 In the figure, the area around the boss 320, i.e. the central area of the cover plate 300, is subjected to a greater stress than the area outside the center of the cover plate 300, but the color block corresponding to the stress of the central area of the cover plate 300 is similar to the color block corresponding to the stress of the area outside the center of the cover plate 300, and the force received by the cover plate 300 during the gas production of the electrode assembly is uniform.

[0044] As mentioned above, during the gas production of the electrode assembly, the central position of the cover plate, i.e. the position corresponding to the central hole of the electrode assembly, is subjected to a greater force than other positions of the cover plate. Generally speaking, for a secondary battery, if the central position of the cover plate is subjected to a too large force, the rupture disc surrounded by the cover plate may be ejected. Preferably, the boss 320 provided as mentioned above is located in the area surrounded by the rupture disc 303 of the cover plate 300, so that the force received by the cover plate 300 during the gas production of the electrode assembly is uniform, which helps to make the opening pressure of the secondary battery 100 more stable.

[0045] In some embodiments, the boss 320 has a protruding height of 0.6 mm. In some embodiments, the protruding height of the boss 320 is consistent with the thickness of the shell 200. In some embodiments, referring to Figure 6 , the surface of the boss 320 close to the electrode assembly 120 is a circular surface, and the diameter of the circular surface is D mm, and the value range of D is 5-7. It can be understood that, for example, the surface of the boss 320 facing the electrode assembly 120 can include a top surface, a circumferential surface surrounding the top surface, and a circular arc transition surface connecting the top surface and the circumferential surface, and the surface of the boss 320 close to the electrode assembly 120 is the top surface, and when the top surface is a circular surface, the diameter of the circular surface is D mm. It can be understood that, in some embodiments, when the boss is a circular boss, the axis of the circular boss and the central hole K of the electrode assembly 120 can be coaxial.

[0046] Referring to Figure 2BIt can be understood that the protrusion 330 protrudes outward in a direction away from the electrode assembly 120, which can increase the internal gas storage space for accommodating gas when gas is generated, reduce the internal pressure of the secondary battery 100, and compensate for the impact of the protrusion 320 descending in the direction of the electrode assembly 120 on the gas storage space. It can be understood that the descending of the protrusion 320 in the direction of the electrode assembly 120 results in a smaller residual space (i.e., the space between the cover plate 300 and the end of the electrode assembly 120 facing the cover plate 300 in the secondary battery 100), and the smaller residual space affects the internal pressure. The protrusion 330 protrudes outward in a direction away from the electrode assembly 120, which increases the residual space to reduce the internal pressure of the secondary battery 100.

[0047] As a preferred, the protrusion surface 331 of the protrusion 330 away from the electrode assembly 120 is a rectangular surface, the width of the rectangular surface is 1mm to 2mm, and the length of the rectangular surface is 3mm to 6mm. In some embodiments, the width of the rectangular surface is 1.5mm to 2mm, and the length of the rectangular surface is 4mm to 5mm.

[0048] As a preferred, the protrusion 330 is located in the area surrounded by the explosion-proof valve 303 of the cover plate 300, so as to be the protrusion 330 of the explosion-proof valve 303, which makes the deformation of the cover plate 300 under internal pressure more consistent and enhances the stability of the explosion-proof valve 303.

[0049] In some embodiments, the secondary battery 100 is a cylindrical battery, and as a preferred, the secondary battery 100 is a 4680 cylindrical battery.

[0050] Embodiments of the present application also provide a battery pack 1002 comprising the secondary battery 100 of any one of the above.

[0051] Embodiments of the present application also provide an electronic device 1000 comprising at least one of the secondary battery 100 of any one of the above and the battery pack 1002.

[0052] The above only describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a shell having a receiving cavity, the shell having an opening at one end in the height direction of the secondary battery, the shell being provided with a curled edge portion extending inward in the radial direction of the shell at the periphery of the opening, and being further provided with a crimping portion protruding inward at a position adjacent to the opening; an electrode assembly accommodated in the receiving cavity; a cover plate sealing the receiving cavity and having a clamping portion clamped between the curled edge portion and the crimping portion, wherein the cover plate has a boss protruding toward the electrode assembly relative to a reference surface which is a surface of the cover plate facing the electrode assembly, wherein the boss is at least partially overlapped by the orthographic projection of the central hole of the electrode assembly on the boss, the protruding height of the boss on the side close to the electrode assembly relative to the reference surface is H mm, and the value of H is in the range of 0.4-0.

8.

2. The secondary battery according to claim 1, wherein: the orthographic projection of the central hole of the electrode assembly on the boss falls within the surrounding area on the side of the boss close to the electrode assembly; the value of H is in the range of 0.5-0.7; the cover plate is further provided with a protrusion protruding in the direction away from the electrode assembly relative to the surface of the clamping portion facing away from the electrode assembly, the protrusion being located in the area between the clamping portion and the boss, the shortest distance between the surface of the protrusion facing away from the electrode assembly and the reference surface is S mm, and the value of S is in the range of 0.8-1.2; the maximum length of the protrusion in the radial direction is L1 mm, the value of L1 is in the range of 1-2, and the maximum width of the protrusion in the direction perpendicular to the length is W1 mm, the value of W1 is in the range of 3-6.

3. The secondary battery according to claim 2, characterized by the value of L1 is in the range of 1.5-2, and the value of W1 is in the range of 4-5; 0.5≤H / S≤0.7 is satisfied.

4. The secondary battery according to claim 2, wherein: the cover plate is provided with a pressure relief valve which is a notch on the side of the cover plate facing the electrode assembly, in a virtual plane perpendicular to the height direction, the orthographic projection of the boss is located in the area surrounded by the orthographic projection of the pressure relief valve and does not overlap with each other.

5. The secondary battery according to claim 1, characterized by the protruding height of the boss is consistent with the thickness of the shell.

6. The secondary battery according to claim 1, characterized by the boss is stamped on the side of the cover plate facing the electrode assembly; the cover plate is integrally stamped.

7. The secondary battery according to claim 6, characterized by the surface of the boss close to the electrode assembly is a circular surface, and the diameter of the circular surface is D mm, the value of D is in the range of 5-7.

8. The secondary battery according to claim 1, characterized by Further comprising: a plastic member surrounding the periphery of the cover plate to insulate and seal the cover plate and the shell; a first current collector plate provided between the electrode assembly and the cover plate and electrically connected with the shell, the connecting sheet of the first current collector plate being located on the side of the crimping portion facing the electrode assembly and being welded with the crimping portion, and the welding mark being located in the shell; the secondary battery is a cylindrical battery.

9. A battery pack characterized by comprising: The secondary battery according to any one of claims 1 to 8.

10. An electronic device, comprising: The secondary battery according to any one of claims 1 to 8.

Images