Secondary battery, battery pack, and electrical device

Abstract

A secondary battery, a battery pack, and an electrical device. By means of configuring a through hole (311) in a first cover body (310), connection and assembly processes of a current collecting disc (400) and a jelly roll (200) can be completed using the through hole (311), thereby reducing the difficulty of connection and assembly of the current collecting disc (400) and the jelly roll (200) and improving the assembling efficiency. The area S1 of the through hole (311) and the orthographic projection area S2 of the first cover body (310) on a plane perpendicular to the height direction of the secondary battery are configured such that same satisfy 0.13≤S2 / S1≤1.5, so that the through hole (311) has more space for completing the connection and assembly of the current collecting disc (400) and the jelly roll (200), and the connection area between the current collecting disc (400) and the jelly roll (200) can be effectively increased.

Description

Secondary batteries, battery packs and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 5, 2024, with application number 202410169680.3 and application name “Secondary Batteries, Battery Packs and Electrical Equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to, but are not limited to, the field of battery technology. Background Art

[0003] Cylindrical batteries are a reliable and efficient energy storage solution, providing reliable power for a variety of devices and applications. In some cylindrical batteries, the current collector is connected to the cover plate and winding core to achieve the battery's circuit connection. However, during the production process, such batteries may suffer from problems such as poor solder joints, which may affect the battery's charge and discharge efficiency.

[0004] Summary of the Invention

[0005] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0006] According to a first aspect of the present application, an embodiment of the present application provides a secondary battery, comprising:

[0007] A housing having a height direction, the housing having a receiving cavity and an opening, the receiving cavity being in communication with the opening;

[0008] a winding core, disposed in the accommodating cavity;

[0009] a cover sealing assembly for sealing the opening, the cover sealing assembly comprising a first cover body and a second cover body connected to each other, the first cover body being connected to the housing, the first cover body being provided with a through hole communicating with the accommodating cavity, and the second cover body sealing the through hole;

[0010] a collecting plate, disposed in the accommodating cavity and connected to the first cover and the winding core respectively;

[0011] The area of ​​the through hole is S1 mm 2 The orthographic projection area of ​​the first cover on a plane perpendicular to the height direction of the secondary battery is S2 mm 2 , satisfying: 0.13≤S2 / S1≤1.5.

[0012] In some embodiments, the secondary battery further satisfies: 0.4≤S2 / S1≤0.89.

[0013] In some embodiments, the first cover comprises:

[0014] a stepped portion, the collecting plate being electrically connected to a side of the stepped portion facing the winding core, and the through hole being formed in the stepped portion;

[0015] a main body portion, surrounding and connected to the step portion, with one end connected to the step portion and the other end connected to the shell;

[0016] The stepped portion protrudes from the main body on a side facing the winding core, and the second cover is connected to a side of the stepped portion facing away from the winding core.

[0017] In some embodiments, the stepped portion comprises:

[0018] a plurality of steps arranged along the height direction between the main body and the collecting plate, wherein one of two adjacent steps is connected to the other step and is located on a side of the other step close to the main body, and the through hole is opened on the step farthest from the main body;

[0019] The main body is connected to at least one of the steps, the collecting plate is connected to a side of the at least one step facing the winding core, and the second cover is connected to a side of the at least one step facing away from the winding core.

[0020] In some embodiments, the collecting tray comprises:

[0021] a first coupling portion connected to the winding core, wherein an orthographic projection of the first coupling portion on the cover sealing assembly is at least partially located within the through hole along the height direction;

[0022] a second combining portion connected to the first cover, the second combining portion surrounding the first combining portion and spaced apart from the first combining portion;

[0023] The connecting portion is disposed between the first combining portion and the second combining portion, and is connected to the first combining portion and the second combining portion respectively.

[0024] In some embodiments, the second coupling portion comprises:

[0025] a connecting portion body connected to the first cover body;

[0026] The bending section is connected to the coupling body and protrudes toward the winding core relative to the coupling body. The connecting portion is connected to a side of the bending section away from the coupling body.

[0027] In some embodiments, the first cover includes a main body and a plurality of steps, the plurality of steps including a first step and a second step, the main body is connected to the housing and is circumferentially connected to the first step, the first step protrudes toward the winding core relative to the main body, the first step is circumferentially connected to the second step, the second step protrudes toward the winding core relative to the first step, and the through hole is opened in the second step;

[0028] The coupling body is connected to the side of the first step facing the winding core, the connecting portion is connected to the side of the second step facing the winding core, at least part of the bending section is arranged on the side of the second step facing the shell, and the second cover is connected to the side of the second step facing away from the winding core.

[0029] In some embodiments, the current collecting plate includes a plurality of the connecting portions, which are arranged at intervals around the central axis of the current collecting plate, and each of the connecting portions is respectively connected to the first combining portion and the second combining portion.

[0030] In some embodiments, the second cover comprises:

[0031] A plurality of recesses spaced apart from each other, wherein one of two adjacent recesses is disposed around the other recess;

[0032] At least one convex portion is provided between two adjacent concave portions, the convex portion protrudes relative to the concave portion toward a side away from the winding core, and at least one convex portion is provided with an explosion-proof notch.

[0033] In some embodiments, the cover seal assembly further comprises:

[0034] A weak portion, through which the first cover body and the second cover body are connected, and the weak portion is configured to be destroyed when the pressure in the accommodating cavity reaches a preset value.

[0035] In some embodiments, a welding seam formed by welding the first cover body and the second cover body forms the weak portion, and the connection strength of the welding seam is less than the connection strength between the first cover body and the shell.

[0036] In some embodiments, the second cover is provided with a liquid injection hole, and the liquid injection hole is communicated with the accommodating cavity;

[0037] The sealing assembly further includes a sealing pin connected to the second cover body and sealing the liquid injection hole.

[0038] According to a second aspect of the present application, an embodiment of the present application provides a battery pack including the above-mentioned secondary battery.

[0039] According to a third aspect of the present application, an embodiment of the present application provides an electrical device, comprising the above-mentioned secondary battery, or comprising the above-mentioned battery pack.

[0040] The secondary battery of the embodiment of the present application includes: a shell having a receiving cavity and an opening, the receiving cavity being connected to the opening; a winding core disposed in the receiving cavity; a cover assembly that seals the opening and includes a first cover body and a second cover body connected to each other, the first cover body being connected to the shell body, the first cover body having a through hole connected to the receiving cavity, and the second cover body sealing the through hole; a current collecting plate disposed in the receiving cavity and connected to the first cover body and the winding core respectively; the area of ​​the through hole is S1 mm 2 The orthographic projection area of ​​the first cover on the plane perpendicular to the height direction of the secondary battery is S2 mm 2 , satisfying: 0.13≤S2 / S1≤1.5. In the secondary battery of the present application, by providing a through hole in the first cover, the through hole can be used to complete the connection and assembly process of the current collecting disc and the winding core, reducing the difficulty of connecting and assembling the current collecting disc and the winding core and improving the assembly efficiency; by setting the through hole area S1 and the orthographic projection area S2 of the first cover on the plane perpendicular to the height direction of the secondary battery to satisfy the above inequality range, the through hole has more space for completing the connection and assembly of the current collecting disc and the winding core, and when the connection area between the current collecting disc and the winding core is increased, sufficient welding space can still be guaranteed to ensure the welding yield; further, it can ensure that there is a large weldable area between the current collecting disc and the winding core, which helps to improve the flow capacity, reduce the internal resistance of the secondary battery, and improve the charge and discharge efficiency of the secondary battery.

[0041] The battery pack of the embodiment of the present application includes the above-mentioned secondary battery, and thus can have all the technical features and beneficial effects of the above-mentioned secondary battery.

[0042] The electric device in the embodiment of the present application includes the above-mentioned secondary battery or the above-mentioned battery pack, and thus can have all the technical features and technical effects of the above-mentioned secondary battery or battery pack.

[0043] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0045] FIG1 is a schematic diagram of the three-dimensional structure of a secondary battery provided in an embodiment of the present application;

[0046] FIG2 is a schematic diagram of an exploded structure of parts of the secondary battery in FIG1 ;

[0047] FIG3 is a schematic structural diagram of the secondary battery in FIG1 viewed along the height direction;

[0048] FIG4 is a schematic diagram of a partial cross-sectional structure of a secondary battery in the first embodiment of the present application;

[0049] FIG5 is a schematic diagram of a partially enlarged structure of region A of the secondary battery in FIG4 ;

[0050] 6 is a schematic structural diagram of the first cover body viewed along the height direction of the secondary battery in the first embodiment;

[0051] FIG7 is a schematic cross-sectional view of the structure along line AA in FIG6 ;

[0052] FIG8 is a schematic diagram of a partially enlarged structure of area B in FIG7 ;

[0053] 9 is a schematic structural diagram of the first cover and the current collecting plate viewed along the height direction of the secondary battery in the first embodiment;

[0054] FIG10 is a schematic cross-sectional view of the structure along line BB in FIG9 ;

[0055] FIG11 is a schematic diagram of a partially enlarged structure of area C in FIG10 ;

[0056] FIG12 is a schematic diagram of a partial cross-sectional structure of a secondary battery in a second embodiment of the present application;

[0057] FIG13 is a schematic diagram of a partially enlarged structure of region D of the secondary battery in FIG12 ;

[0058] 14 is a schematic structural diagram of the first cover body viewed along the height direction of the secondary battery in the second embodiment;

[0059] FIG15 is a schematic cross-sectional view of the structure along line CC in FIG14;

[0060] FIG16 is a schematic diagram of a partially enlarged structure of area E in FIG15 ;

[0061] 17 is a schematic structural diagram of the first cover and the current collecting plate viewed along the height direction of the secondary battery in the second embodiment;

[0062] FIG18 is a schematic cross-sectional view of the structure along line DD in FIG17 ;

[0063] FIG19 is a schematic diagram of a partially enlarged structure of the F area in FIG18;

[0064] 20 is a schematic structural diagram of the current collecting plate viewed along the height direction of the secondary battery in the second embodiment;

[0065] FIG21 is a schematic cross-sectional view of the structure along line EE in FIG20;

[0066] FIG22 is a schematic diagram of a partially enlarged cross-sectional structure of a secondary battery in some embodiments of the present application;

[0067] FIG23 is a schematic diagram of the second cover structure viewed along the height direction of the secondary battery in the third embodiment of the present application;

[0068] FIG24 is a schematic cross-sectional view of the structure along line FF in FIG23;

[0069] FIG25 is a schematic diagram of the connection structure between the first cover and the second cover, viewed along the height direction of the secondary battery in the fourth embodiment of the present application;

[0070] FIG26 is a schematic cross-sectional view of the structure along line GG in FIG25 ;

[0071] Figure markings: 100-shell; 110-accommodating chamber; 120-opening; 200-winding core; 300-covering assembly; 310-first cover body; 311-through hole; 312-main body; 313-stepped portion; 3131-step; 3132-first step; 3133-second step; 320-second cover body; 321-recessed portion; 322-convex portion; 323-explosion-proof notch; 324-liquid injection hole; 330-sealing pin; 340-weak portion; 400-collecting plate; 410-second joint; 411-joining portion body; 412-bending section; 420-first joint; 430-connecting portion; 500-positive pole.

[0072] Implementation Methods of the Application

[0073] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of this application.

[0074] In the description of this application, it should be understood that the terms "height", "thickness", "up", "down", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting this application. In the description of this application, "plurality" means two or more, and at least one means one, two, or more than two, unless otherwise clearly and specifically defined.

[0075] It should also be noted that in the drawings of the embodiments of this application, the arrow marked with an X indicates the height direction X of the secondary battery. This height direction X is introduced to more clearly illustrate the structure and relative positional relationships of the components of the secondary battery. In actual applications, the height direction X may vary depending on the placement of the secondary battery. In some embodiments, the secondary battery can be a cylindrical battery, which has a generally cylindrical shape. The positive and negative electrodes can be respectively disposed at the two ends of the cylinder. The height direction is the direction corresponding to the two ends of the cylindrical battery.

[0076] As an introduction to this application, cylindrical battery negative electrode covers and casings are often sealed using laser welding. The current collector is welded to the cover and core separately to complete the battery circuit connection. However, during the production process of such batteries, large cumulative tolerances in height often cause the core to be too high after being inserted into the casing, making it impossible to weld the casing cover, resulting in assembly difficulties. Alternatively, the core is too short, resulting in a cold weld between the negative electrode current collector and the negative electrode cover, affecting the battery's charge and discharge efficiency.

[0077] In view of this, embodiments of the present application provide a secondary battery, aiming to solve at least one of the above-mentioned technical problems.

[0078] Referring to FIG. 1 , FIG. 2 and FIG. 4 , the secondary battery of the embodiment of the present application may be a cylindrical battery, which includes a housing 100 , a winding core 200 , a sealing assembly 300 and a current collecting plate 400 .

[0079] The shell 100 has a accommodating cavity 110 and an opening 120, and the accommodating cavity 110 is connected to the opening 120. The shell 100 provides external protection and isolation for the secondary battery, and can also play a role in heat dissipation, leakage prevention and mechanical support. It is an important component to ensure the performance and safety of the secondary battery.

[0080] The winding core 200 is disposed in the accommodating cavity 110 . The winding core 200 is a core component of the secondary battery and can generally be formed by winding or laminating positive and negative electrode materials and an isolation layer.

[0081] The capping assembly 300 seals the opening 120, enclosing the accommodating cavity 110. This ensures a good seal within the housing 100 and prevents leakage of chemical substances within the battery cells. Furthermore, the capping assembly 300 includes a first cover 310 and a second cover 320. The first cover 310 is connected to the housing 100 and defines a through hole 311 that communicates with the accommodating cavity 110. The second cover 320 seals the through hole 311. Optionally, the first cover 310 and the second cover 320 can be connected by welding.

[0082] The collecting tray 400 is disposed in the accommodating cavity 110 and is connected to the first cover 310 and the winding core 200 respectively. The collecting tray 400 is used to conduct current between the winding core 200 and the sealing assembly 300 to achieve conduction of the internal circuit of the secondary battery.

[0083] Please refer to FIG6 , where the area of ​​the through hole 311 is S1 mm 2 The orthographic projection area of ​​the first cover 310 on the plane perpendicular to the height direction X of the secondary battery is S2 mm 2 , satisfying: 0.13≤S2 / S1≤1.5.

[0084] Thus, in the secondary battery of the embodiment of the present application, by providing a through hole 311 in the first cover body 310, the through hole 311 can be used to complete the connection and assembly process between the collecting plate 400 and the winding core 200. In particular, in the welding preparation method, the welding light can be irradiated onto the collecting plate 400 through the through hole 311 to realize the welding of the collecting plate 400 and the winding core 200, thereby reducing the difficulty of connecting and assembling the collecting plate 400 and the winding core 200 and improving the assembly efficiency. By setting the area S1 of the through hole 311 and the orthographic projection area S2 of the first cover body 310 on the plane perpendicular to the height direction X of the secondary battery to satisfy the above inequality range, the area distribution of the first cover body 310 and the through hole 311 in the sealing assembly 300 can be more appropriate, and more space can be obtained for completing the connection and assembly of the collecting plate 400 and the winding core 200, which can effectively increase the connection area between the collecting plate 400 and the winding core 200. In particular, when adopting the welding preparation method, the welding light can be irradiated more on the collecting plate 400, ensuring that there is a larger weldable area between the collecting plate 400 and the winding core 200, which helps to improve the current flow capacity, reduce the internal resistance of the secondary battery, and improve the charging and discharging efficiency of the secondary battery.

[0085] Specifically, S2 / S1 can be any value among 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or a range value between any two values. In the range of 0.13 to 1.5, when S2 / S1 is smaller, the area of ​​the through hole 311 is larger, and the welding area of ​​the collecting disc 400 and the winding core 200 is larger; when S2 / S1 is larger, the area of ​​the first cover 310 is larger, and the connection area between the collecting disc 400 and the first cover 310 is larger; within the above range, the overcurrent capacity can be guaranteed, and the corresponding secondary battery can have better charge and discharge efficiency. Optionally, S1 can be 550~1450mm 2 , that is, the area of ​​the through hole 311 is 550~1450mm 2 .

[0086] It should be noted that for a cylindrical battery, it has a substantially cylindrical outer contour, so the height direction X refers to the axial length of the battery. The projection plane of the first cover 310 can be any plane perpendicular to the height direction X.

[0087] Next, a number of embodiments and comparative examples are provided to illustrate the effects of the secondary battery of the present application, wherein some common area measurement methods can be selected to measure and obtain S1 and S2. For example, for the through hole 311, the measurement method of the area S1 can be specifically selected according to its shape. When the through hole 311 is circular, square, rectangular, etc., a vernier caliper, micrometer or other measuring tool can be used to measure the corresponding size of the through hole 311, and the area S1 can be calculated using a geometric formula. For the through hole 311 with an irregular hole structure, it can also be measured by image processing. For example, an image of the through hole 311 in the secondary battery can be obtained, and the image can be loaded using image processing software and S1 can be measured using the software. Alternatively, it can also be measured by projection, using a projection measurement device (such as a digital microscope or an image measuring instrument) to measure the image area of ​​the through hole 311, and then the area S1 can be obtained. Accordingly, the area S2 can be obtained directly by projection measurement, or it can be obtained by image processing using image software.

[0088] The impact of S2 / S1 on the charge and discharge efficiency of secondary batteries can be determined by the overcurrent capability. The overcurrent capability is determined as follows: when charging under the 15-minute and 30-minute fast charging strategies (usually with a current range of 120A to 160A), the maximum temperature on the collecting plate during the process is ≤60°C, which is considered qualified; if the maximum temperature on the collecting plate during the 15-minute or 30-minute fast charging process is ≥60°C, it is considered unqualified. The test results of the embodiment and comparative example are shown in the following table:

[0089] As shown in the table above, when S2 / S1 is controlled within the range of 0.13 to 1.5, the temperature of the collecting plate 400 is within 60°C during 15-minute and 30-minute fast charging. It can be seen that the overcurrent capacity of the secondary battery can be guaranteed, and the corresponding secondary battery can have good charge and discharge efficiency. Optionally, when S2 / S1 is controlled within the range of 0.4 to 0.89, the temperature of the collecting plate 400 is within 50°C during 15-minute and 30-minute fast charging, which is a better effect. When S2 / S1>1.5, or when S2 / S1<0.13, the maximum temperature on the collecting plate 400 is ≥60°C during 15-minute or 30-minute fast charging, and the overcurrent capacity is reduced, which does not meet the requirements.

[0090] Referring to Figures 4 to 19 , in some embodiments, the first cover 310 includes a main body 312 and a stepped portion 313. The main body 312 surrounds and connects to the stepped portion 313 and is connected to the housing 100. The collecting plate 400 is electrically connected to the side of the stepped portion 313 facing the winding core 200, and the through hole 311 is defined in the stepped portion 313. The stepped portion 313 includes an extension extending along the height direction X and a connecting portion connected to the extension. The connecting portion extends radially from the first cover 310. The stepped portion 313 protrudes relative to the main body 312 toward the collecting plate 400, thereby forming a stepped structure with a height difference along the height direction X on the first cover 310. The second cover 320 is connected to the side of the stepped portion 313 facing away from the winding core 200. By setting the first cover body 310 into a stepped structure, on the one hand, it helps to increase the contact area between the first cover body 310 and the shell 100 and / or the collecting plate 400, thereby increasing the connection area and ensuring the stability of the structure and circuit connection; on the other hand, the stepped structure can be used to increase the ability of the first cover body 310 to produce elastic deformation along the height direction X, which helps to absorb the assembly tolerance in the height direction X; furthermore, the stepped portion 313 can be used to press the collecting plate 400 against the winding core 200, further avoiding the occurrence of cold solder joints.

[0091] Alternatively, referring again to Figures 4 to 11 , in the first embodiment, the stepped portion 313 is a step 3131. Specifically, referring to Figure 8 , the stepped portion 313 protrudes relative to the main portion 312 toward the collecting tray 400, forming a step 3131. In other words, the stepped portion 313 protrudes relative to the main portion 312 toward the side closer to the winding core 200, forming a platform closer to the winding core 200, to which the collecting tray 400 is connected.

[0092] Optionally, in some embodiments, the stepped portion 313 includes a plurality of steps 3131 arranged along the height direction X of the secondary battery between the main body 312 and the current collecting tray 400. Of two adjacent steps 3131, one step 3131 surrounds and connects to the other step 3131 and is located on the side of the other step 3131 closer to the main body 312. The through hole 311 is located on the step 3131 farthest from the main body 312, that is, the through hole 311 is located on the step 3131 closest to the winding core 200. The main body 312 is connected to at least one step 3131, the current collecting tray 400 is connected to the side of the at least one step 3131 facing the winding core 200, and the second cover 320 is located on the side of the at least one step 3131 facing away from the current collecting tray 400 and is connected to the side of the at least one step 3131 facing away from the winding core 200. In this embodiment, by providing a plurality of steps 3131, the contact area between the first cover body 310 and the shell 100 and / or the collecting plate 400 is further increased, thereby improving the stability of the structure and circuit connection; the ability of the first cover body 310 to produce elastic deformation along the height direction X can also be further increased, which is more conducive to absorbing the assembly tolerance in the height direction X; and the plurality of steps 3131 can also be used to further press the collecting plate 400 and the winding core 200 to avoid cold welding, thereby greatly improving the circuit connection reliability inside the secondary battery.

[0093] Please refer to Figures 4 to 19 again. In some embodiments, the current collecting tray 400 includes a first joint portion 420, a second joint portion 410, and a connecting portion 430. The first joint portion 420 is connected to the core 200. Along the height direction X of the secondary battery, the orthographic projection of the first joint portion 420 on the cover assembly 300 is at least partially located within the through hole 311. Therefore, the first joint portion 420 and the core 200 can be welded through the through hole 311 to ensure the stability of the connection between the current collecting tray 400 and the core 200. The second joint portion 410 is connected to the first cover body 310. The second joint portion 410 surrounds the first joint portion 420 and is spaced apart from the first joint portion 420. The connecting portion 430 is disposed between the first joint portion 420 and the second joint portion 410, and is connected to the first joint portion 420 and the second joint portion 410 respectively. That is to say, there is a gap between the first coupling portion 420 and the second coupling portion 410, and the two are respectively connected to the winding core 200 and the first cover body 310, and are connected together through the connecting portion 430, thereby ensuring the firmness and stability of the connection, and the formed collecting plate 400 can be deformed in the height direction X, which can absorb the assembly tolerance in the height direction X.

[0094] For example, in the first embodiment, the first coupling portion 420 corresponds to the position of the through hole 311 along the height direction X, and the side of the first coupling portion 420 facing away from the through hole 311 is welded to the winding core 200, the second coupling portion 410 is connected to the first cover body 310, and is connected to the first coupling portion 420 through the connecting portion 430.

[0095] Optionally, in the first embodiment, the following condition is satisfied: 0.2≤S2 / S1≤0.5, so that the secondary battery has better charge and discharge efficiency.

[0096] Optionally, please refer to Figures 12, 13, 17 to 21. In the second embodiment, the second coupling portion 410 includes a coupling portion body 411 and a bent section 412. The coupling portion body 411 is connected to the first cover body 310, and the bent section 412 is connected to the coupling portion body 411 and protrudes toward the winding core 200 relative to the coupling portion body 411. The connecting portion 430 is connected to the side of the bent section 412 away from the coupling portion body 411. By providing the bent section 412, on the one hand, the collecting plate 400 can form a stepped structure, thereby improving the ability to generate elastic deformation along the height direction X, thereby improving the ability to absorb assembly tolerances in the height direction; on the other hand, it can adapt to the stepped structure formed by the first cover body 310, increase the connection area with the first cover body 310, improve the connection stability, and ensure the flow capacity.

[0097] Specifically, referring to Figure 22, in the second embodiment, the first cover 310 includes a main body 312 and a plurality of steps 3131. The plurality of steps 3131 include a first step 3132 and a second step 3133. The main body 312 is connected to the housing 100 and is circumferentially connected to the first step 3132. The first step 3132 protrudes relative to the main body 312 toward the winding core 200. The first step 3132 is circumferentially connected to the second step 3133. The second step 3133 protrudes relative to the first step 3132 toward the winding core 200. The through hole 311 is defined in the second step 3133. The coupling body 411 is connected to the side of the first step 3132 facing the winding core 200. The connecting portion 430 is connected to the side of the second step 3133 facing the winding core 200. At least a portion of the bent section 412 is disposed on the side of the second step 3133 facing the housing 100. The second cover 320 is connected to the side of the second step 3133 facing away from the winding core 200.

[0098] Optionally, in the second embodiment, the following condition is satisfied: 0.4≤S2 / S1≤0.8, so that the secondary battery has better charge and discharge efficiency.

[0099] Please refer to Figure 9 and Figure 20 again. In some embodiments, the collecting plate 400 includes a plurality of connecting parts 430. The plurality of connecting parts 430 are arranged at intervals around the central axis of the collecting plate 400. The structural strength of the collecting plate 400 is improved by providing a plurality of connecting parts 430.

[0100] Referring to Figures 23 and 24 , in the third embodiment, the second cover 320 includes a plurality of spaced-apart recesses 321 and at least one protrusion 322. Two adjacent recesses 321 are arranged so that one surrounds the other, and a protrusion 322 is provided between the two adjacent recesses 321. The protrusion 322 projects relative to the recesses 321 toward a side away from the collecting plate 400. At least one protrusion 322 is provided with an explosion-proof notch 323. By providing the explosion-proof notch 323 on the protrusion 322, the flow guide space formed between two adjacent recesses 321 and the protrusion 322 can be utilized to guide the pressure relief fluid, thereby increasing the pressure relief speed and ensuring safety.

[0101] Please refer to Figures 25 and 26 . In some embodiments, the capping assembly 300 further includes a weak portion 340, through which the first cap 310 and the second cap 320 are connected. The weak portion 340 is configured to be broken when the pressure within the accommodating chamber 110 reaches a preset value. Specifically, the first cap 310 and the second cap 320 can be connected by welding or adhesive. The welding is controlled to produce a weld seam or the adhesive connection strength is less than the connection strength between the first cap 310 and the housing 100 and less than the sealing strength of the positive electrode column 500, thereby forming the weak portion 340. When the internal pressure of the secondary battery rises to a preset value, the weak portion 340 can first rupture and release gas.

[0102] Please refer to Figure 2 and Figure 3 again. In some embodiments, the second cover body 320 is provided with a liquid injection hole 324, which is connected to the accommodating cavity 110; the sealing assembly 300 also includes a sealing pin 330, which is connected to the second cover body 320 and seals the liquid injection hole 324.

[0103] In some embodiments, the current collecting disk 400 is a negative current collecting disk 400 .

[0104] During assembly, the winding core 200 is assembled into the housing 100 and connected to the terminal assembly of the positive electrode column 500. The collecting plate 400 is connected to the first cover 310, and then the first cover 310 is connected to the housing 100, and the opening 120 is sealed. The first joint 420 of the collecting plate 400 is pressed tightly through the through hole 311 by a clamp so that it is in close contact with one end surface of the winding core 200, and then the two are welded to achieve electrical connection. Then, the second cover 320 is connected to the first cover 310, and the injection hole 324 on the second cover 320 is sealed with a sealing nail 330.

[0105] Accordingly, a battery pack provided in an embodiment of the present application includes the secondary battery of the above embodiment, so the battery pack can have all the technical features and beneficial effects of the above secondary battery, which will not be repeated here.

[0106] Accordingly, the embodiments of the present application provide an electrical device, which can be various types of equipment such as new energy vehicles, computers, and energy storage and power supply devices. It is understood that the electrical device includes the secondary battery of the above-mentioned embodiment, or includes the battery pack of the above-mentioned embodiment, and thus can have all the technical features and technical effects of the above-mentioned secondary battery or battery pack, which will not be described in detail here.

[0107] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0108] The above is a detailed introduction to the secondary batteries, battery packs and electrical equipment provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A secondary battery, wherein: include: A housing having a height direction, the housing having a receiving cavity and an opening, the receiving cavity being in communication with the opening; a winding core, disposed in the accommodating cavity; a cover sealing assembly for sealing the opening, the cover sealing assembly comprising a first cover body and a second cover body connected to each other, the first cover body being connected to the housing, the first cover body being provided with a through hole communicating with the accommodating cavity, and the second cover body sealing the through hole; a collecting plate, disposed in the accommodating cavity and connected to the first cover and the winding core respectively; The area of the through hole is S1mm 2 The orthographic projection area of the first cover on the plane perpendicular to the height direction is S2mm 2 , satisfying: 0.13≤S2 / S1≤1.

5.

2. The secondary battery according to claim 1, wherein The secondary battery further satisfies: 0.4≤S2 / S1≤0.

89.

3. The secondary battery according to claim 1 or 2, wherein The secondary battery further satisfies: 550≤S1≤1450.

4. The secondary battery according to claim 1, wherein The first cover comprises: a stepped portion, the collecting plate being electrically connected to a side of the stepped portion facing the winding core, and the through hole being formed in the stepped portion; a main body portion, surrounding and connecting the step portion, wherein one end of the main body portion is connected to the step portion, and the other end is connected to the shell; The stepped portion protrudes from the main body on a side facing the winding core, and the second cover is connected to a side of the stepped portion facing away from the winding core.

5. The secondary battery according to claim 4, wherein The stepped portion includes: a plurality of steps arranged along the height direction between the main body and the collecting plate, wherein one of two adjacent steps is connected to the other step and is located on a side of the other step close to the main body, and the through hole is opened on the step farthest from the main body; The main body is connected to at least one of the steps, the collecting plate is connected to a side of the at least one step facing the winding core, and the second cover is connected to a side of the at least one step facing away from the winding core.

6. The secondary battery according to claim 1, wherein The collecting plate comprises: a first coupling portion connected to the winding core, wherein an orthographic projection of the first coupling portion on the cover sealing assembly is at least partially located within the through hole along the height direction; a second combining portion connected to the first cover, the second combining portion surrounding the first combining portion and spaced apart from the first combining portion; The connecting portion is disposed between the first combining portion and the second combining portion, and is connected to the first combining portion and the second combining portion respectively.

7. The secondary battery according to claim 6, wherein The second combining portion includes: a connecting portion body connected to the first cover body; The bending section is connected to the coupling body and protrudes toward the winding core relative to the coupling body. The connecting portion is connected to a side of the bending section away from the coupling body.

8. The secondary battery according to claim 7, wherein The first cover includes a main body and a plurality of steps, the plurality of steps including a first step and a second step, the main body is connected to the housing and is circumferentially connected to the first step, the first step protrudes toward the winding core relative to the main body, the first step is circumferentially connected to the second step, the second step protrudes toward the winding core relative to the first step, and the through hole is opened in the second step; The coupling body is connected to the side of the first step facing the winding core, the connecting portion is connected to the side of the second step facing the winding core, at least part of the bending section is arranged on the side of the second step facing the shell, and the second cover is connected to the side of the second step facing away from the winding core.

9. The secondary battery according to claim 6, wherein The current collecting plate includes a plurality of connecting portions, which are arranged at intervals around the central axis of the current collecting plate, and each connecting portion is respectively connected to the first combining portion and the second combining portion.

10. The secondary battery according to claim 1, wherein The second cover comprises: A plurality of recesses spaced apart from each other, wherein one of two adjacent recesses is disposed around the other recess; At least one convex portion is provided between two adjacent concave portions, the convex portion protrudes relative to the concave portion toward a side away from the winding core, and at least one convex portion is provided with an explosion-proof notch.

11. The secondary battery according to claim 1, wherein The cover seal assembly further comprises: A weak portion, through which the first cover body and the second cover body are connected, and the weak portion is configured to be destroyed when the pressure in the accommodating cavity reaches a preset value.

12. The secondary battery according to claim 11, wherein A welding seam formed by welding the first cover body and the second cover body forms the weak portion, and the connection strength of the welding seam is smaller than the connection strength between the first cover body and the shell.

13. The secondary battery according to claim 1, wherein The second cover body is provided with a liquid injection hole, and the liquid injection hole is communicated with the accommodating cavity; The sealing assembly further includes a sealing pin connected to the second cover body and sealing the liquid injection hole.

14. A battery pack, wherein: The secondary battery according to any one of claims 1 to 13 is included.

15. An electrical device, wherein: The method comprises the secondary battery according to any one of claims 1 to 13, or the battery pack according to claim 14.

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