Secondary battery and battery pack

Abstract

The embodiment of the utility model discloses a secondary battery and a battery pack, and the secondary battery is characterized in that the two ends of a top cover sheet in a top cover assembly in a first direction are bent to form bent parts, so that the two ends of the top cover sheet in the first direction respectively extend to the outer sides of the two ends of an electrode assembly in the first direction; according to the secondary battery, the bent part is arranged on the top cover assembly, and the pole in the top cover assembly is arranged on the bent part, so that the pole can be connected with the adjacent tab without a pin, the space occupied by the pin required by a traditional top cover is saved, the energy density of the secondary battery is improved, and the risk that the pin is broken and fails due to vibration is solved; and the service life of the secondary battery is prolonged.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a secondary battery and battery pack. Background Technology

[0002] With the development of science and technology, secondary batteries have been widely used in portable electronic devices such as mobile phones, digital cameras and laptops, and have broad application prospects in electric vehicles, electric bicycles and other electric vehicles, as well as large and medium-sized electric equipment such as energy storage facilities, becoming an important technical means to solve global problems such as energy crisis and environmental pollution.

[0003] Existing secondary batteries have two types of electrode lead-out methods for their internal electrode components: same-side electrode leads and opposite-side electrode leads. Opposite-side electrode leads are where the positive and negative electrode leads are respectively located at opposite ends of the electrode component in its first direction. For opposite-side electrode leads, most secondary batteries adopt a top cover structure design to reduce the difficulty of inserting the electrode component into the casing. That is, the top cover component has pins at both ends, and the two pins are respectively connected to the electrode leads on the adjacent side. During battery use, the pins are at risk of vibration and breakage. Utility Model Content

[0004] This application provides a secondary battery and battery pack that can solve the problems of low utilization of internal space and risk of pin breakage caused by the top cover in existing secondary batteries.

[0005] A first aspect of this application provides a secondary battery, comprising: a housing having a first direction and a second direction perpendicular to each other, the housing having a first opening at one end along the second direction and second openings at both ends along the first direction; an electrode assembly disposed in the housing, the electrode assembly having tabs at both ends along the first direction; and a top cover assembly including a top cover sheet and a terminal post, the top cover sheet including a main body portion and a bent portion, the main body portion extending along the first direction, the bent portion being provided at both ends along the first direction, and the terminal post being disposed on the bent portion; wherein the top cover sheet covers the first opening, the bent portion covers the second opening, and the terminal post is connected to the tab.

[0006] Optionally, the housing includes two first sidewalls disposed opposite each other along the first direction, the first sidewalls having a second opening at one end near the first opening in the second direction, the second opening extending along the second direction and communicating with the first opening; the bent portion is embedded in the second opening, and in the second direction, the end of the bent portion away from the main body abuts against the inner bottom wall of the second opening.

[0007] Optionally, the housing further has a third direction perpendicular to the first direction and the second direction respectively; the housing also includes a bottom wall and two second side walls disposed opposite to each other along the third direction, the bottom wall and the first opening being disposed opposite to each other in the second direction, the second opening extending to the bottom wall along the second direction, and in the second direction, the end of the bent portion away from the main body abuts against the bottom wall.

[0008] Optionally, the second sidewall has a first groove on the end face near the second opening in the first direction, and the first groove extends along the second direction; the bent portion is embedded in the first groove; in the first direction, the depth of the first groove is L1 mm, and the thickness of the bent portion is S1 mm, where S1≤L1.

[0009] Optionally, the second sidewall has a second groove on the end face near the first opening in the second direction, and the second groove extends along the first direction; the second groove communicates with the first groove, and the main body is embedded in the second groove; in the second direction, the depth of the second groove is L2 mm, and the thickness of the main body is S2 mm, where S2≤L2.

[0010] Optionally, the bottom wall has a third groove on the end face near the second opening in the first direction; the third groove is connected to the first groove; the bent portion is embedded in the third groove at the end opposite to the main body in the second direction; in the first direction, the depth of the third groove is L3 mm, the thickness of the bent portion is S1 mm, and S1≤L3.

[0011] Optionally, the length of the bent portion in the second direction is H1 mm; in the second direction, the minimum distance between the pole post and the end face of the bent portion near the main body is H2 mm, satisfying: 1 / 5H1≤H2<1 / 2H1.

[0012] Optionally, the top cover assembly further includes an explosion-proof valve disposed on the bend, and / or, the explosion-proof valve is disposed on the main body.

[0013] Optionally, the bent portion and the main body portion are integrally formed.

[0014] Optionally, the dimensions of the housing along the first direction are L4 mm, along the second direction are L5 mm, and along the third direction are L6 mm, satisfying: L4 > L5 > L6.

[0015] A second aspect of this application provides a battery pack including the secondary battery as described above.

[0016] The beneficial effects of this application are that it provides a secondary battery and a battery pack having the secondary battery. The secondary battery forms a bent portion by bending the top cover sheet in the top cover assembly at both ends in a first direction, so that the two ends of the top cover sheet in the first direction extend to the outer sides of the two ends of the electrode assembly in the first direction, and the electrode post in the top cover assembly is disposed on the bent portion. This allows the electrode post to be connected to the adjacent electrode tab without the need for pins, saving the space occupied by the pins required by the traditional top cover, improving the energy density of the secondary battery, solving the risk of pin breakage due to vibration, improving the service life of the secondary battery, and retaining the convenience of casing provided by the top cover, thus reducing manufacturing costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the first structure of a secondary battery provided in an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of a second structure of a secondary battery provided in an embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the first assembly structure of the top cover assembly, housing, and frame in a secondary battery according to another embodiment of this application;

[0021] Figure 4 This is a schematic diagram of a second assembly structure of the top cover assembly, housing, and frame in a secondary battery according to another embodiment of this application;

[0022] Figure 5 This is a schematic diagram of the first angle structure of the middle casing of a secondary battery provided in another embodiment of this application;

[0023] Figure 6 This is a schematic diagram of the second angle structure of the middle casing of a secondary battery provided in another embodiment of this application;

[0024] Figure 7 This is a schematic diagram of the structure of a top cover assembly in a secondary battery at a first angle, provided in another embodiment of this application;

[0025] Figure 8 This is a schematic diagram of the electrode assembly with opposite-side tabs in a secondary battery provided in an embodiment of this application;

[0026] Figure 9 This is a schematic diagram of the structure of the electrode assembly with non-full tabs on the opposite side in the secondary battery provided in the embodiments of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100. Secondary battery; 110. Housing; 1111. First opening; 1112. Second opening; 112. First sidewall; 113. Bottom wall; 114. Second sidewall; 115. First groove; 116. Second groove; 117. Third groove; 120. Electrode assembly; 121. Tab; 122. Body; 130. Top cover assembly; 131. Top cover piece; 1311. Main body; 1312. Bending part; 132. Terminal post; 1321. First surface; 1322. Second surface; 133. Explosion-proof valve; 134. Liquid injection hole;

[0029] X, first direction; Y, third direction; Z, second direction. Detailed Implementation

[0030] To make the objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this application. It should be understood that the specific embodiments described in this specification are merely for explaining this application and are not intended to limit it.

[0031] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] In the embodiments of the application, "parallel" refers to a state in which the angle formed by two lines, a line and a surface, or a surface is -1° to 1°. "Perpendicular" refers to a state in which the angle formed by two lines, a line and a surface, or a surface is 89° to 91°. Equal distances or equal angles refer to a state in which the tolerance range is -1% to 1%.

[0035] This application provides a secondary battery and a battery pack having the secondary battery. The secondary battery is constructed by bending a top cover sheet in a top cover assembly at both ends in a first direction to form bent portions. These bent portions extend to the outer sides of the electrode assemblies at both ends in the first direction, and the electrode posts in the top cover assembly are disposed on the bent portions. This allows the electrode posts to connect to adjacent tabs without the need for pins, saving the space occupied by pins traditionally required by the top cover. This improves the energy density of the secondary battery, eliminates the risk of pin breakage due to vibration, and extends the battery's lifespan. As a typical application, the battery pack including the secondary battery can be used to power electric vehicles and other electrical equipment.

[0036] In some embodiments of this application, a battery pack (not shown in the figures) is provided, the battery pack including a secondary battery 100.

[0037] In some embodiments of this application, a secondary battery 100 is provided, with reference to Figures 1-4 as well as Figures 7-9 The secondary battery 100 includes: a housing 110, an electrode assembly 120, and a top cover assembly 130.

[0038] In some embodiments of this application, reference is made to Figures 1-4 The housing 110 has a first direction X and a second direction Z that are perpendicular to each other, specifically as follows: Figures 1-4 In the illustrated embodiment, the first direction X is orthogonal to the second direction Z. The housing 110 has a first opening 1111 at one end along the second direction Z, and second openings 1112 at both ends along the first direction X. Specifically, the first opening 1111 is located at the top of the housing 110 in the second direction Z, and the second openings 1112 are located on opposite side walls of the housing 110 in the first direction X. The two ends of the first opening 1111 in the first direction X are respectively connected to adjacent second openings 1112. The housing 110 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, or plastic; this embodiment does not impose any special limitations on this.

[0039] Electrode assembly 120 is disposed in housing 110, see reference Figure 8 and Figure 9 The electrode assembly 120 includes tabs 121 and a body 122. The body 122 extends along a first direction X and is formed by winding a positive electrode plate, a negative electrode plate, and a diaphragm. A tab 121 is respectively disposed on each of the two end faces of the body 122 in the first direction X, forming a diaphragm structure on opposite sides of the electrode assembly 120. One tab 121 is the positive tab, and the other tab 121 is the negative tab. Specifically... Figure 8 In the illustrated embodiment, the portion of the electrode plate coated with an active material layer constitutes the body 122 of the electrode assembly 120, while the two ends of the electrode plate in the first direction X, without an active material layer, constitute the tabs 121 of the electrode assembly 120. Specifically, as shown... Figure 9 In the illustrated embodiment, the portion of the electrode coated with an active material layer constitutes the body 122 of the electrode assembly 120, while the two ends of the electrode in the first direction X, which are not coated with an active material layer and are cut, constitute the tabs 121 of the electrode assembly 120. Alternatively, as... Figure 9 In the embodiment shown, the tab 121 is welded to the body 122.

[0040] In some embodiments of this application, reference is made to Figures 1-4 as well as Figure 7 The top cover assembly 130 includes a top cover plate 131 and a pole post 132. The top cover plate 131 includes a main body portion 1311 and multiple bent portions 1312, specifically as follows: Figures 1-4 as well as Figure 7In the illustrated embodiment, there are two bending portions 1312. The main body 1311 extends along a first direction X, and the two bending portions 1312 are respectively connected to the two ends of the main body 1311 in the first direction X. The bending portions 1312 extend along a second direction Z. The main body 1311 and the two bending portions 1312 form a U-shaped structure of the top cover plate 131. Each of the two bending portions 1312 is provided with a pole post 132. Specifically, each bending portion 1312 is provided with one pole post 132. The main body 1311 of the top cover plate 131 covers the first opening 1111 of the housing 110, and the bending portions 1312 cover the second opening 1112 of the housing 110. The pole post 132 provided on the bending portion 1312 is connected to the adjacent tab 121.

[0041] In existing secondary batteries, for the opposite-side output tab structure of the electrode assembly, the electrode post is usually placed on the top surface of the top cover. In order to achieve the electrical connection between the opposite-side output tab and the electrode post, a pin needs to be added to the top cover assembly. One end of the pin is connected to the electrode post and the other end is connected to the tab. However, the design of the pin will occupy too much space inside the casing, affecting the energy density of the secondary battery. Moreover, the processing and manufacturing cost of the pin is high, and there is a risk of breakage under vibration.

[0042] The secondary battery provided in this application embodiment has a U-shaped structure formed by opening second openings 1112 at both ends of the housing 110 along the first direction X and opening a first opening 1111 at one end of the housing 110 along the second direction Z. The first opening 1111 and the two second openings 1112 communicate to form a U-shaped structure. The main body 1311 and the two bent portions 1312 form a U-shaped structure of the top cover 131. The main body 1311 covers the first opening 1111, and the bent portions 1312 cover the second openings 1112. The bent portions 1312 extend as part of the top cover 131 to the side wall of the housing 110 in the first direction X, thus replacing the top cover assembly of the existing secondary battery. The presence of the pins and the fact that the bent portion 1312 covers the second opening 1112 on the side wall of the housing 110 eliminates the need for the bent portion 1312 to occupy internal space. The electrode post 132 can be electrically connected to the tab 121 of the electrode assembly 120 simply by placing it on the bent portion 1312, thereby improving the space utilization within the housing 110 and increasing the energy density of the secondary battery 100. Furthermore, the design of the bend portion 1312 and the second opening 1112 ensures the stability and firmness of the assembly between the bent portion 1312 and the housing 110, preventing damage to the bent portion 1312 during vibration and extending the lifespan of the secondary battery 100. In addition, the assembly direction of the top cover assembly 130 to the housing 110 in the secondary battery 100 provided in this embodiment is the same as the assembly direction of the top cover, reducing assembly difficulty and manufacturing costs. Moreover, the concave structure design of the top cover piece 131 simplifies the manufacturing process and effectively reduces processing and manufacturing costs.

[0043] The top cover 131 is fixed to the housing 110 by laser welding.

[0044] In some embodiments of this application, reference is made to Figure 1 and Figure 2 The housing 110 includes two first sidewalls 112 disposed opposite each other along a first direction X. A second opening 1112 is formed at one end of the first sidewall 112 near the first opening 1111 in a second direction X. The second opening 1112 extends along a second direction Z. A bent portion 1312 is embedded in the second opening 1112. In the second direction Z, the end of the bent portion 1312 away from the main body 1311 abuts against the inner bottom wall of the second opening 1112. The second opening 1112 occupies a portion of the first sidewall 112 in the second direction Z, thus shortening the length of the bent portion 1312 in the second direction Z and reducing manufacturing costs. The pole post 132 on the shorter bent portion 1312 can be connected with… Figure 9 The electrode assembly 120 shown matches the tab 121 to avoid the bent portion 1312 occupying too much space in the second direction Z, thus improving space utilization. Furthermore, the height of the electrode post 132 on the bent portion 1312 in the second direction Z can be made consistent with... Figure 9 The tabs 121 in the electrode assembly 120 shown are at similar heights in the second direction Z, which reduces the lever arm between the weld between the pole post 132 and the tab 121 and the center of gravity of the electrode assembly 120. This can effectively reduce the stress concentrated on the tabs 121 of the electrode assembly 120 during vibration, and reduce the risk of failure caused by the tabs 121 of the electrode assembly 120 tearing.

[0045] In some embodiments of this application, reference is made to Figures 3-6 The housing 110 has a third direction Y that is perpendicular to the first direction X and the second direction Z, specifically as follows: Figures 3-6 In the illustrated embodiment, the first direction X, the second direction Z, and the third direction Y are orthogonal to each other. The housing 110 includes a bottom wall 113 and two second side walls 114 disposed opposite each other along the third direction Y. The bottom wall 113 is disposed opposite to the first opening 1111 in the second direction Z. The second opening 1112 extends along the second direction Z to the bottom wall 113, such that the bottom wall 113 and the two second side walls 114 form a U-shaped cross-sectional structure of the housing 110. In the second direction Z, the end of the bent portion 1312 away from the main body portion 1311 abuts against the bottom wall 113. Figures 3-6 In the illustrated embodiment, the housing 110 omits the first sidewall 112, and only includes a bottom wall 113 and a second sidewall 114. This arrangement increases the length of the bent portion 1312 in the second direction Z. The bent portion 1312 serves as the first sidewall of the housing 110 and is assembled with the housing 110, thereby allowing the pole post 132 disposed on the bent portion 1312 to be connected to... Figure 8 The tabs 121 in the electrode assembly 120 shown are electrically connected, improving space utilization and thus increasing the energy density of the secondary battery.

[0046] In some embodiments of this application, reference is made to Figures 1-6 The second sidewall 114 has a first groove 115 on its end face near the second opening 1112 in the first direction X. The first groove 115 extends along the second direction Z. The first grooves 115 on the two second sidewalls 114 are arranged opposite each other in the third direction Y. The opening of the first groove 115 gives the second sidewall 114 a two-stage stepped structure in the first direction X. The bent portion 1312 is embedded in the first groove 115, so that the top cover 131 is assembled with the shell 110 along the second direction Z. During the process, the first groove 115 can guide and direct the bent portion 1312, so that the two opposite sides of the bent portion 1312 in the third direction Y can abut against the adjacent second sidewall 114, ensuring the accuracy of the assembly of the bent portion 1312 and the housing 110. Moreover, the abutment between the side of the bent portion 1312 and the second sidewall 114 can ensure the sealing between the bent portion 1312 and the second sidewall 114 and ensure the welding effect between the bent portion 1312 and the second sidewall 114.

[0047] In some embodiments of this application, reference is made to Figure 5 The depth of the first groove 115 in the first direction X is L1 mm. Specifically, the depth of the first groove 115 is the distance between the opening end of the first groove 115 and the inner bottom wall of the first groove 115 in the first direction X. Figure 7 The thickness of the bent portion 1312 in the first direction X is S1 mm, S1≤L1, so that the bent portion 1312 can be embedded in the first groove 115. The outer surface of the bent portion 1312 in the first direction X will not exceed the end face of the second side wall 114 in the first direction X, thus ensuring the overall flatness of the secondary battery 100.

[0048] In some embodiments of this application, reference is made to Figures 2-6 The second sidewall 114 has a second groove 116 on its end face near the first opening 1111 in the second direction Z. The second groove 116 extends in the first direction X. The second grooves 116 on the two second sidewalls 114 are arranged opposite each other in the third direction Y. The opening of the second groove 116 makes one end of the second sidewall 114 in the second direction Z have a two-stage stepped structure. The main body 1311 of the top cover 131 is embedded in the second groove 116, so that when the top cover assembly 130 is assembled with the housing 110 in the second direction Z, the main body 1311 can be embedded in the second groove 116, thereby ensuring the stability and firmness of the assembly between the main body 1311 and the two second sidewalls 114. Moreover, the opposite sides of the main body 1311 in the third direction Y can be close to the adjacent second sidewalls 114, ensuring the sealing between the main body 1311 and the second sidewalls 114 and ensuring the welding effect between the bent part 1312 and the second sidewalls 114.

[0049] In some embodiments of this application, reference is made to Figure 5 and Figure 6 The second groove 116 is connected to the adjacent first groove 115 at both ends in its extension direction (i.e., in the first direction X), thereby ensuring the flatness of the connection between the main body 1311 and the bent part 1312 and ensuring the smoothness of the assembly of the top cover 131 and the housing 110.

[0050] In some embodiments of this application, reference is made to Figure 5 The depth of the second groove 116 in the second direction Z is L2 mm. Specifically, the depth of the second groove 116 is the distance between the opening end of the second groove 116 and the inner bottom wall of the second groove 116 in the second direction Z. Figure 7The thickness of the main body 1311 in the second direction Z is S2 mm, S2≤L2, so that the main body 1311 can be embedded in the second groove 116 and the outer surface of the main body 1311 in the second direction Z will not exceed the end face of the second side wall 114 in the second direction Z, thus ensuring the overall flatness of the secondary battery 100.

[0051] In some embodiments of this application, reference is made to Figures 3-6 A third groove 117 is provided on the end face of the bottom wall 113 near the second opening 1112 in the first direction X. The third groove 117 extends along the third direction Y. The two ends of the third groove 117 in the third direction Y are respectively connected to the adjacent first groove 115. The end of the bent part 1312 away from the main body part 1311 in the second direction Z is embedded in the third groove 117, so that when the top cover assembly 130 is assembled with the shell 110 in the second direction Z, the bent part 1312 can be embedded in the third groove 117, thereby ensuring the stability and firmness of the assembly between the bent part 1312 and the bottom wall 113, ensuring the sealing between the bent part 1312 and the bottom wall 113, and ensuring the welding effect between the bent part 1312 and the bottom wall 113.

[0052] In some embodiments of this application, reference is made to Figure 5 The depth of the third groove 117 in the first direction X is L3 mm. Specifically, the depth of the third groove 117 is the distance between the opening end of the third groove 117 and the inner bottom wall of the third groove 117 in the first direction X, as shown in the figure. Figure 7 The thickness of the bent portion 1312 in the first direction X is S1 mm, S1≤L3, so that the end of the bent portion 1312 away from the main body portion 1311 in the second direction Z can be embedded in the third groove 117. The outer surface of the bent portion 1312 in the first direction X will not exceed the end face of the bottom wall 113 in the first direction X, ensuring the overall flatness of the secondary battery 100.

[0053] In some embodiments of this application, reference is made to Figure 3 and Figure 4The length of the bent portion 1312 in the second direction Z is H1 mm. In the second direction Z, the minimum distance between the pole post 132 and the end face of the bent portion 1312 near the main body 1311 is H2 mm, satisfying: 1 / 5H1≤H2<1 / 2H1. When the relationship between the values ​​of H2 and H1 is within the above range, the height of the pole post 132 on the bent portion 1312 in the second direction Z is similar to the height of the tab 121 in the electrode assembly 120 in the second direction Z. This reduces the lever arm between the weld between the pole post 132 and the tab 121 and the center of gravity of the electrode assembly 120, effectively reducing the stress concentrated on the tab 121 of the electrode assembly 120 during vibration, lowering the risk of failure due to tearing of the tab 121 of the electrode assembly 120, and also ensuring the connection strength between the bent portion 1312 and the main body 1311.

[0054] In other embodiments, the following condition is satisfied: 3 / 10H1≤H2≤2 / 5H1.

[0055] In some embodiments of this application, reference is made to Figure 3 and Figure 4 The pole post 132 is square in shape and includes a first surface 1321 and a second surface 1322 disposed opposite to each other along the second direction Z. H2 is the minimum distance between the plane where the first surface 1321 is located and the plane where the end face of the bent portion 1312 near the main body portion 1311 is located in the second direction Z.

[0056] In some embodiments of this application, the pole post 132 is cylindrical in shape, and any point on the outer ring surface of the pole post 132 has a distance in the second direction Z from the plane containing the end face of the bent portion 1312 near the main body portion 1311. H2 is the minimum value among multiple distances.

[0057] In some embodiments of this application, the top cover assembly 130 further includes an explosion-proof valve 133, see reference 133. Figure 1 , Figure 3 and Figure 7 An explosion-proof valve 133 is disposed on the main body 1311. Gas generated by the electrode assembly 120 during the use of the secondary battery 100 can be discharged along the second direction Z towards the main body 1311 through the gap between the bent part 1312 and the main body 122, and discharged through the explosion-proof valve 133.

[0058] In some embodiments of this application, reference is made to Figure 2 and Figure 4An explosion-proof valve 133 is disposed on the bending portion 1312. Specifically, each bending portion 1312 is provided with an explosion-proof valve 133. By disposing the explosion-proof valve 133 on the bending portion 1312, the explosion-proof valve 133 can be disposed opposite to the tab 121 in the electrode assembly 120 along the first direction X. This allows the gas generated by the electrode assembly 120 during the use of the secondary battery 100 to be directly discharged from the adjacent explosion-proof valve 133 along the first direction X, shortening the exhaust path, improving exhaust efficiency, and enhancing the safety of the secondary battery 100.

[0059] In some embodiments of this application, explosion-proof valves 133 are provided on both the main body 1311 and the bent portion 1312.

[0060] In some embodiments of this application, reference is made to Figure 1 The main body 1311 of the top cover plate 131 is provided with an injection hole 134.

[0061] In some embodiments of this application, the main body 1311 and the bending portion 1312 are integrally formed, and the top cover 131 has a simple structure. The integral forming of the main body 1311 and the bending portion 1312 can effectively improve the production efficiency of the top cover 131 and reduce the manufacturing cost.

[0062] In some embodiments of this application, reference is made to Figure 1 The dimensions of the housing 110 along the first direction X are L4 mm, along the second direction Z are L5 mm, and along the third direction Y are L6 mm, satisfying L4 > L5 > L6. This forms a cuboid structure for the housing 110. The second sidewall 114 has the largest surface area among the six faces, and the second opening 1112 is opened on the relatively smaller first sidewall 112, improving the space utilization of the housing 110. In addition, the first opening 1111 is opened on a face formed by the longest and shortest sides, providing sufficient opening area for the electrode assembly to be installed in the housing without reducing the strength of the housing 110 or causing partial deformation of the housing 110 and damaging the installed electrode assembly, thus balancing the convenience of installation and product yield.

[0063] Test example:

[0064] A battery pack includes a secondary battery. The secondary battery includes a housing 110. The housing 110 has a first direction X and a second direction Z that are perpendicular to each other. A first opening 1111 is formed at one end of the housing 110 along the second direction Z, and a second opening 1112 is formed at both ends along the first direction X.

[0065] An electrode assembly 120 is disposed in a housing 110, and tabs 121 are respectively provided at both ends of the electrode assembly 120 that are oppositely disposed in the first direction X.

[0066] The top cover assembly 130 includes a top cover plate 131 and a pole post 132. The top cover plate 131 includes a main body portion 1311 and a plurality of bent portions 1312. The main body portion 1311 extends along a first direction X. The plurality of bent portions 1312 are connected to both ends of the main body portion 1311 in the first direction X. Each of the plurality of bent portions 1312 is provided with a pole post 132.

[0067] The top cover 131 covers the first opening 1111, the bent part 1312 covers the second opening 1112, and the pole post 132 is connected to the pole tab 121.

[0068] The length of the bent portion 1312 in the second direction Z is H1 mm; the minimum distance between the pole post 132 and the end face of the bent portion 1312 near the main body portion 1311 in the second direction Z is H2 mm.

[0069] Test method:

[0070] 1) Connection strength between the bent part and the main body:

[0071] Tensile tests were performed on the bent portion and the main body in the first direction X, the second direction Z, and the third direction Y. The main body was fixed with a clamp, and the bent portion was clamped with a clamp. Tensile forces were applied in the first direction X, the second direction Z, and the third direction Y, respectively. The tensile force values ​​when the bent portion broke in each direction were recorded to evaluate the connection strength between the bent portion and the main body.

[0072] 2) Welding strength between the electrode tab and the top cover connecting piece:

[0073] The battery core was fixed with a clamp, and the top cover was held with the clamp. A tensile force was applied along the direction perpendicular to the welding surface of the tab and the top cover connecting piece until the weld point broke. The maximum tensile force during this process was recorded to evaluate the welding strength of the tab and the top cover connecting piece.

[0074] Using the above testing methods, test cases 1-3 were tested, and the following data was obtained:

[0075] <![CDATA[H1]]> <![CDATA[H2]]> Connection strength (N) Welding strength (N) Test Example 1 30 8 300 32 Test Example 2 30 7 400 35 Test Example 3 30 11 350 36 Test Example 4 30 14 380 31

[0076] Based on the above data, when 1 / 5H1≤H2<1 / 2H1, the stress concentration of the tabs can be reduced while ensuring the connection strength between the bent part and the main body, thereby improving the reliability of the secondary battery and extending the overall life of the battery pack.

[0077] The above provides a detailed description of a secondary battery and battery pack provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A secondary battery, characterized in that, include: A housing having a first direction and a second direction perpendicular to each other, wherein a first opening is provided at one end along the second direction and a second opening is provided at both ends along the first direction; An electrode assembly is disposed in the housing, and the electrode assembly has tabs at both ends in the first direction; A top cover assembly includes a top cover sheet and an electrode post. The top cover sheet includes a main body and a bent portion. The main body extends along a first direction, and the bent portion is provided at both ends of the main body in the first direction. The electrode post is provided on the bent portion. The top cover covers the first opening, the bent portion covers the second opening, and the pole post is connected to the pole tab.

2. The secondary battery as described in claim 1, characterized in that, The housing includes two first sidewalls arranged opposite each other along the first direction. The first sidewalls have a second opening at one end near the first opening in the second direction. The second opening extends along the second direction and communicates with the first opening. The bent portion is embedded in the second opening, and in the second direction, the end of the bent portion away from the main body abuts against the inner bottom wall of the second opening.

3. The secondary battery as described in claim 1, characterized in that, The housing also has a third direction perpendicular to the first direction and the second direction respectively; the housing also includes a bottom wall and two second side walls disposed opposite to each other along the third direction, the bottom wall and the first opening being disposed opposite to each other in the second direction, the second opening extending to the bottom wall along the second direction, and in the second direction, the bent portion abutting against the bottom wall at the end away from the main body portion.

4. The secondary battery as described in claim 3, characterized in that, The second sidewall has a first groove on the end face near the second opening in the first direction, and the first groove extends along the second direction; The bent portion is embedded in the first groove; In the first direction, the depth of the first groove is L1 mm, and the thickness of the bent portion is S1 mm, where S1 ≤ L1.

5. The secondary battery as described in claim 4, characterized in that, The second sidewall has a second groove on the end face near the first opening in the second direction, and the second groove extends along the first direction; The second groove is connected to the first groove, and the main body is embedded in the second groove; In the second direction, the depth of the second groove is L2 mm, and the thickness of the main body is S2 mm, where S2 ≤ L2.

6. The secondary battery as described in claim 4, characterized in that, The bottom wall has a third groove on the end face near the second opening in the first direction; The third groove is connected to the first groove; The bent portion is fitted into the third groove at one end in the second direction that is away from the main body portion; In the first direction, the depth of the third groove is L3 mm, and the thickness of the bent portion is S1 mm, where S1 ≤ L3.

7. The secondary battery as described in claim 1, characterized in that, The length of the bent portion in the second direction is H1 mm; In the second direction, the minimum distance between the pole post and the end face of the bent portion near the main body is H2 mm, satisfying: 1 / 5H1≤H2<1 / 2H1.

8. The secondary battery as described in claim 1, characterized in that, The bent portion and the main body portion are integrally formed.

9. The secondary battery as described in claim 1, characterized in that, The dimensions of the housing along the first direction are L4 mm, along the second direction are L5 mm, and along the third direction are L6 mm, satisfying: L4 > L5 > L6.

10. A battery pack, characterized in that, Includes the secondary battery as described in any one of claims 1 to 9.

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