Secondary battery and electrochemical device

Abstract

Embodiments of the present application provide a secondary battery and an electrochemical device. The secondary battery comprises an electrode assembly and a case. The case is used for accommodating the electrode assembly, and the case comprises a first wall and a second wall which are opposite to each other in the thickness direction of the electrode assembly. The first wall is provided with a first protruding portion protruding out of the interior of the case; the case further comprises a third wall; the third wall is connected to the first wall and the second wall; the third wall is spaced apart from the electrode assembly in a first direction; the first direction is perpendicular to the thickness direction of the electrode assembly; in the thickness direction of the electrode assembly, the size of the inner surface of the third wall is L1, the thickness of the electrode assembly is L2, and the height of the first protruding portion protruding out of the inner surface of the first wall is L3, wherein the following relationship is satisfied: L3>L1-L2. The technical solution provided by the embodiments of the present application can improve the reliability and safety performance of the secondary battery.

Description

Secondary batteries and electrochemical devices CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application CN202410353884.2, entitled “Secondary Batteries and Electrochemical Devices,” filed on March 26, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the technical field of secondary batteries, and in particular to a secondary battery and an electrochemical device. Background Art

[0003] As a type of lithium-ion battery, hard-shell batteries have greater advantages than soft-pack batteries in terms of safety and volume energy density, and therefore occupy an increasingly important position in the field of consumer electronics.

[0004] The main reason for the failure of hard-shell batteries during a drop is that the internal electrode assembly displaces relative to the outer shell and impacts the outer shell, causing the weaker welds on the outer shell to crack, which in turn causes battery leakage and battery bulging, ultimately bringing a series of safety risks. Summary of the Invention

[0005] The present application provides a secondary battery and an electrochemical device, which can improve the reliability and safety performance of the secondary battery.

[0006] This application is achieved through the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a secondary battery comprising an electrode assembly and a housing. The housing is used to accommodate the electrode assembly, and the housing comprises a first wall and a second wall opposite to each other along the thickness direction of the electrode assembly. The first wall is provided with a first protrusion protruding toward the interior of the housing, and the housing further comprises a third wall connecting the first wall and the second wall. Along a first direction, the third wall is spaced apart from the electrode assembly, and the first direction is perpendicular to the thickness direction of the electrode assembly. Along the thickness direction of the electrode assembly, the inner surface of the third wall has a dimension L1, the thickness of the electrode assembly is L2, and the height of the first protrusion protruding from the inner surface of the first wall is L3, satisfying the condition L3 ≥ L1-L2.

[0008] According to the secondary battery of the embodiment of the present application, the first protrusion protrudes toward the interior of the outer shell. Along the first direction, the projection of the first protrusion partially overlaps with the projection of the electrode assembly. When the electrode assembly moves relative to the outer shell along the first direction, the first protrusion can block the movement of the electrode assembly relative to the outer shell. At the same time, the first protrusion disperses the force of the movement of the electrode assembly relative to the outer shell, so that the force does not directly impact the weakest weld area of ​​the outer shell, thereby reducing the risk of weld cracking, so that the secondary battery has higher reliability and improves the safety performance of the secondary battery.

[0009] In one or more optional embodiments above, L3≤L2 / 3, 0.14mm≤L3≤2.73mm.

[0010] In the above solution, the protruding height of the first protrusion is relatively low, which facilitates the processing and manufacturing of the first protrusion and reduces the risk of interference between the first protrusion and other components in the housing.

[0011] In one or more of the above optional embodiments, the first protrusion contacts the first end portion of the electrode assembly in the first direction.

[0012] In the above scheme, since the first protrusion contacts the first end of the electrode assembly in the first direction, the first protrusion can prevent the electrode assembly from moving relative to the shell in the direction toward the first protrusion in the first direction, further improving the blocking effect of the first protrusion on the electrode assembly.

[0013] In one or more of the above optional embodiments, a first groove is formed on the outer surface of the first wall at a position corresponding to the first protrusion.

[0014] In the above solution, the first wall can be formed by stamping a plate-like structure, which is easy to process and manufacture.

[0015] In one or more of the above optional embodiments, the first protrusion extends along the second direction, and the second direction, the first direction, and the thickness direction of the electrode assembly are perpendicular to each other.

[0016] In the above solution, the first protrusion has a longer dimension in the second direction, so that the first protrusion has a better blocking effect on the electrode assembly in the first direction.

[0017] In one or more of the above optional embodiments, the cross section of the first protrusion is arc-shaped, rectangular or conical, and the cross section of the first protrusion is perpendicular to the second direction.

[0018] In the above solution, the cross section of the first protrusion is arc-shaped, rectangular or conical, which is convenient for processing and manufacturing.

[0019] In one or more optional embodiments above, the electrode assembly has a first end in a first direction, the outer shell also includes a fourth wall, the third wall and the fourth wall are arranged opposite to each other along the first direction, the third wall is arranged opposite to the first end in the first direction, the third wall is closer to the first end relative to the fourth wall, and along the first direction, at least a portion of the first protrusion is located between the first end and the third wall.

[0020] In the above scheme, along the first direction, at least a portion of the first protrusion is located between the first end and the third wall. The first protrusion can limit the movement of the electrode assembly relative to the outer shell toward the third wall, has a good blocking effect on the electrode assembly, and can disperse the force of the electrode assembly moving relative to the outer shell toward the third wall, thereby reducing the impact of the movement of the electrode assembly on the weak parts of the outer shell.

[0021] In one or more optional embodiments above, the secondary battery further includes a tab, which is connected to the first end and extends out of the first end along the first direction; along the first direction, the minimum distance between the first protrusion and the inner surface of the third wall is L4, satisfying 0.05mm≤L4≤1mm.

[0022] In the above solution, the tab is connected to the first end, and assembly space is reserved between the tab and the third wall. The first protrusion rationally utilizes the assembly space within the housing, reducing its impact on the energy density of the secondary battery. The minimum distance between the first protrusion and the inner surface of the third wall satisfies the above relationship. This not only facilitates processing and manufacturing, but also reduces the risk of interference between the first protrusion and the third wall. Furthermore, it occupies less space in the first direction, reducing its impact on the energy density of the secondary battery.

[0023] In one or more optional embodiments above, along the first direction, the minimum distance between the first end and the inner surface of the third wall is L5, satisfying 0.17mm≤L5≤1.5mm; the width of the first protrusion is L6, satisfying 0.4≤L6 / L5<1.

[0024] In the above solution, the minimum distance between the first end and the inner surface of the third wall satisfies the aforementioned relationship. This, on the one hand, reserves assembly space, reducing the risk of short circuits caused by contact between the electrode assembly and the third wall; on the other hand, occupies less space in the first direction, reducing the impact on the energy density of the secondary battery. The minimum distance between the first end and the inner surface of the third wall and the width of the first coating satisfy the aforementioned relationship. On the one hand, the first protrusion has a larger width, facilitating processing and manufacturing; on the other hand, the first protrusion occupies less space in the first direction, reducing the impact on the energy density of the secondary battery.

[0025] In one or more of the above optional embodiments, the first wall is further provided with a second protrusion protruding toward the interior of the housing, the second protrusion being spaced apart from the first protrusion along the first direction; the electrode assembly further has a second end portion disposed opposite the first end portion in the first direction; the fourth wall is closer to the second end portion than the third wall; along the first direction, a projection of the second protrusion partially overlaps with a projection of the electrode assembly, and at least a portion of the second protrusion is located between the second end portion and the fourth wall. Along the first direction, a minimum distance L7 between the second protrusion and the inner surface of the fourth wall is satisfied, 0.05 mm ≤ L7 ≤ 0.5 mm.

[0026] In the above solution, the second protrusion cooperates with the first protrusion to block the opposite ends of the electrode assembly in the first direction, limiting the movement of the electrode assembly relative to the housing in the first direction. At the same time, the first protrusion and / or the second protrusion disperse the force acting on the movement of the electrode assembly relative to the housing, so that the force does not directly impact the weakest weld area of ​​the housing, thereby reducing the risk of weld cracking, thereby ensuring higher reliability and improving the safety performance of the secondary battery. The minimum distance between the second protrusion and the inner surface of the fourth wall satisfies the above relationship. On the one hand, this facilitates processing and manufacturing, reduces the risk of interference between the second protrusion and the fourth wall, and on the other hand, reduces the space occupied in the first direction and reduces the impact on the energy density of the secondary battery.

[0027] In one or more of the above optional embodiments, the first wall is further provided with a third protrusion protruding toward the interior of the housing; the housing further includes a fifth wall, the fifth wall connecting the third wall and the fourth wall at its ends in the first direction, and connecting the first wall and the second wall at its ends in the thickness direction of the electrode assembly; the electrode assembly further has a third end in the second direction, the second direction, the first direction, and the thickness direction of the electrode assembly being perpendicular to each other, at least a portion of the third protrusion being located between the third end and the fifth wall along the second direction; and the projection of the third protrusion partially overlaps with the projection of the electrode assembly along the second direction. The third protrusion extends along the first direction, and the end of the third protrusion proximal to the first protrusion is spaced apart from the first protrusion. Along the first direction, the distance between the inner surface of the third wall and the inner surface of the fourth wall is L8, and the length of the third protrusion is L9, satisfying the condition 0.6L8≤L9≤0.9L8.

[0028] In the above solution, the third protrusion is provided so that when the electrode assembly moves relative to the housing in the second direction, the third protrusion can contact the electrode assembly to prevent the electrode assembly from moving relative to the housing. At the same time, the third protrusion disperses the force acting on the electrode assembly to move relative to the housing so that the force does not directly impact the weakest weld area of ​​the housing, thereby reducing the risk of weld cracking, making the secondary battery more reliable and improving the safety performance of the secondary battery. The third protrusion has a longer dimension in the first direction, so that the third protrusion has a better blocking effect on the electrode assembly in the second direction. The length of the third protrusion and the distance between the inner surface of the third wall and the inner surface of the fourth wall satisfy the above relationship. On the one hand, when the electrode assembly moves relative to the housing in the second direction, the third protrusion can have a larger contact area with the electrode assembly, and the third protrusion has a better blocking effect on the electrode assembly; on the other hand, it facilitates the processing and manufacturing of the third protrusion and reduces the risk of interference between the third protrusion and the third and fourth walls.

[0029] In one or more optional embodiments above, the first wall is further provided with a second protrusion, a third protrusion and a fourth protrusion protruding toward the interior of the shell, the second protrusion and the first protrusion are spaced apart along the first direction, the third protrusion and the fourth protrusion are spaced apart along the second direction, and the second direction, the first direction and the thickness direction of the electrode assembly are perpendicular to each other; the electrode assembly further has a second end, a third end and a fourth end, the second end is arranged opposite to the first end along the first direction, the third end and the fourth end are arranged opposite to each other along the second direction, and the fourth wall is closer to the second end relative to the third wall, and the shell further includes a fifth wall and a sixth wall arranged opposite to each other along the second direction, the fifth wall is closer to the third end relative to the sixth wall, and the sixth wall is closer to the fourth end relative to the fifth wall; along the first direction, the projection of the second protrusion partially overlaps with the projection of the electrode assembly, and at least a portion of the second protrusion is located between the second end and the fourth wall; along the second direction, the projection of the third protrusion partially overlaps with the projection of the electrode assembly, at least a portion of the third protrusion is located between the third end and the fifth wall, the projection of the fourth protrusion partially overlaps with the projection of the electrode assembly, and at least a portion of the fourth protrusion is located between the fourth end and the sixth wall.

[0030] In the above scheme, the second protrusion cooperates with the first protrusion to block the opposite ends of the electrode assembly in the first direction, limiting the movement of the electrode assembly relative to the shell in the first direction, and the third protrusion cooperates with the fourth protrusion to block the opposite ends of the electrode assembly in the second direction, limiting the movement of the electrode assembly relative to the shell in the second direction. At the same time, the first protrusion, the second protrusion, the third protrusion and the fourth protrusion can disperse the force of the electrode assembly moving relative to the shell in a plane perpendicular to the thickness direction of the electrode assembly, so that the force does not directly impact the weakest weld area of ​​the shell, further making the secondary battery have higher reliability and improving the safety performance of the secondary battery.

[0031] In one or more optional embodiments above, the housing further includes a fifth wall and a sixth wall disposed opposite to each other along the second direction, the second direction, the first direction, and the thickness direction of the electrode assembly are perpendicular to each other, and along the second direction, the distance between the inner surface of the fifth wall and the inner surface of the sixth wall is L 10 , at least one of the following conditions is satisfied: (1) along the second direction, the length of the first convex portion is L 11 , meet, 0.6L 10 ≤L 11 ≤0.9L 10 (2) Along the second direction, the minimum distance between the first protrusion and the inner surface of the fifth wall is L 12 , meet, 2mm≤L 12 ≤0.2L 10 .

[0032] In the above solution, when the length of the first protrusion and the distance between the inner surface of the fifth wall and the inner surface of the sixth wall satisfy the above relationship (0.6L 10 ≤L 11 ≤0.9L 10 ), on the one hand, when the electrode assembly moves relative to the housing along the first direction, the first protrusion and the electrode assembly can have a larger contact area, and the first protrusion has a better blocking effect on the electrode assembly; on the other hand, it is convenient to process and manufacture the first protrusion, and reduce the risk of interference between the first protrusion and the fifth wall and the sixth wall. When the minimum distance between the first protrusion and the inner surface of the fifth wall and the distance between the inner surface of the fifth wall and the inner surface of the sixth wall meet the above relationship (2mm≤L 12 ≤0.2L 10 ), on the one hand, the risk of interference between the first protrusion and the fifth wall is reduced; on the other hand, the distance between the first protrusion and the inner surface of the fifth wall is smaller, which reduces the space waste in the second direction and reduces the impact on the energy density of the secondary battery.

[0033] In one or more optional embodiments above, the housing includes a shell and a cover, the shell has an opening, the cover closes the opening, and the first wall is the cover.

[0034] In the above solution, the first wall is a cover body, which facilitates the processing and manufacturing of the first protrusion and the assembly of the electrode assembly into the outer shell.

[0035] In one or more of the above optional embodiments, the secondary battery further includes a first adhesive member, and the first adhesive member bonds the first wall and the electrode assembly.

[0036] In the above solution, the first adhesive member bonds the first wall and the electrode assembly to limit the movement of the electrode assembly relative to the first wall, thereby reducing the risk of the electrode assembly impacting the weld of the housing.

[0037] In a second aspect, an embodiment of the present application further provides an electrochemical device, which includes a secondary battery provided in any of the above embodiments.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0040] FIG1 is a perspective view of a secondary battery provided in some embodiments of the present application;

[0041] FIG2 is a top view of a secondary battery provided in some embodiments of the present application;

[0042] FIG3 is a cross-sectional view taken along the AA direction of FIG2 ;

[0043] FIG4 is a partial enlarged view of point B in FIG3 ;

[0044] FIG5 is a schematic structural diagram of a first convex portion with a rectangular cross section provided in some embodiments of the present application;

[0045] FIG6 is a schematic structural diagram of a first convex portion with a tapered cross section provided in some embodiments of the present application;

[0046] FIG7 is a cross-sectional view of a secondary battery provided in some embodiments of the present application;

[0047] FIG8 is a cross-sectional view taken along the CC direction of FIG2 ;

[0048] FIG9 is a schematic diagram of assembling a first adhesive member, a first wall, and an electrode assembly according to some embodiments of the present application;

[0049] FIG10 is a schematic structural diagram of a first adhesive member provided in some embodiments of the present application.

[0050] Icon: 100-secondary battery; 10-electrode assembly; 11-first end; 12-second end; 13-third end; 14-fourth end; 15-positive electrode plate; 16-negative electrode plate; 17-diaphragm; 20-housing; 21-first wall; 210-first body; 211-first protrusion; 212-first groove; 213-second protrusion; 214-third protrusion; 215-fourth protrusion; 22-second wall; 23-third wall; 24-fourth wall; 25-fifth wall; 26-sixth wall; 27-housing; 28-cover; 30-ear; 30a-negative electrode ear; 31-negative electrode adapter; 41-first adhesive; 411-first base material layer; 412-first adhesive layer; 413-second adhesive layer; 42-second adhesive; X-first direction; Y-second direction; Z-thickness direction of the electrode assembly. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0052] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0053] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0054] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0055] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0056] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0057] Secondary batteries (hard-shell batteries) can easily break when dropped, leading to battery failure. Research has found that secondary battery failure during drops is primarily due to the relative movement of the electrode assembly within the housing, impacting the housing and causing cracks in the weakest welds. This in turn leads to electrolyte leakage, resulting in battery failure.

[0058] To address the problem of secondary battery failure caused by the electrode assembly impacting the housing, the present application provides a technical solution. The secondary battery includes a housing and an electrode assembly, the electrode assembly being disposed within the housing. The housing includes a first wall having a first protrusion protruding toward the interior of the housing. The housing also includes a third wall connecting the first wall and the second wall. The third wall is spaced apart from the electrode assembly along a first direction, the first direction being perpendicular to the thickness of the electrode assembly. Along the thickness direction of the electrode assembly, the inner surface of the third wall has a dimension L1, the thickness of the electrode assembly has a dimension L2, and the height of the first protrusion protruding from the inner surface of the first wall has a dimension L3, satisfying the condition L3 ≥ L1 - L2. The electrode assembly is a flat structure housed within the housing. Along the first direction, the projection of the first protrusion partially overlaps with the projection of the electrode assembly. When the electrode assembly moves relative to the housing in the first direction, the first protrusion can block the movement of the electrode assembly relative to the housing. Furthermore, the first protrusion disperses the force exerted by the electrode assembly relative to the housing, preventing the force from directly impacting the weakest weld area of ​​the housing, thereby reducing the risk of weld cracking. This ensures that the secondary battery has higher reliability and improves the safety performance of the secondary battery.

[0059] The secondary battery in the embodiment of the present application is a hard shell battery, and the secondary battery can be a lithium ion battery, a sodium ion battery, a magnesium ion battery, or the like.

[0060] The structure of the secondary battery provided by the embodiments of the present application will be described below with reference to the accompanying drawings.

[0061] Please refer to Figures 1 to 4, Figure 1 is a three-dimensional view of a secondary battery provided in some embodiments of the present application, Figure 2 is a top view of a secondary battery provided in some embodiments of the present application, Figure 3 is a cross-sectional view taken along the AA direction of Figure 2, and Figure 4 is a partial enlarged view of point B in Figure 3.

[0062] The embodiment of the present application provides a secondary battery 100 , which includes an electrode assembly 10 and a housing 20 . The housing 20 is used to accommodate the electrode assembly 10 , and the electrode assembly 10 is accommodated in the housing 20 .

[0063] The housing 20 provides a space for accommodating the electrode assembly 10 , and the housing 20 forms a closed environment to prevent leakage of the electrolyte.

[0064] The housing 20 may be a steel housing or an aluminum housing. When the housing 20 is an aluminum housing, the material of the housing 20 may be an aluminum alloy.

[0065] The electrode assembly 10 includes a positive electrode sheet 15 and a negative electrode sheet 16. The positive electrode sheet 15 and the negative electrode sheet 16 can be stacked or wound. The electrode assembly 10 is flat to reduce the space occupied by the electrode assembly 10. The electrode assembly 10 also includes a separator 17, which is disposed between the positive electrode sheet 15 and the negative electrode sheet 16 to insulate and separate the positive electrode sheet 15 and the negative electrode sheet 16.

[0066] In some embodiments, the housing 20 includes a first wall 21 and a second wall 22 opposite to each other along the thickness direction Z of the electrode assembly, and the electrode assembly 10 is located between the first wall 21 and the second wall 22. The first wall 21 is provided with a first protrusion 211 protruding toward the interior of the housing 20.

[0067] In some embodiments, the first wall 21 includes a first body 210 and a first protrusion 211 . The first protrusion 211 protrudes from the inner surface of the first body 210 . The inner surface of the first body 210 is the surface of the first body 210 facing the electrode assembly 10 .

[0068] The first protrusion 211 and the first body 210 can be provided separately, and the first protrusion 211 is fixed to the first body 210, for example, the first protrusion 211 and the first body 210 are welded, riveted, bonded, clamped or threaded.

[0069] The first protrusion 211 and the first body 210 may be integrally formed, that is, the first wall 21 may be stamped from a single plate, so that the first protrusion 211 protrudes from the inner surface of the first body 210 .

[0070] In some embodiments, the housing 20 further includes a third wall 23 that connects the first wall 21 and the second wall 22. The third wall 23 is spaced apart from the electrode assembly 10 along a first direction X, which is perpendicular to the thickness direction Z of the electrode assembly. That is, along the first direction X, the projection of the first protrusion 211 partially overlaps with the projection of the electrode assembly 10.

[0071] In some embodiments, along the thickness direction Z of the electrode assembly, the size of the inner surface of the third wall 23 is L1, the thickness of the electrode assembly 10 is L2, and the height of the first protrusion 211 protruding from the inner surface of the first wall 21 is L3, satisfying L3≥L1-L2.

[0072] In the figure, the direction indicated by the letter X may be the first direction, and the direction indicated by the letter Z may be the thickness direction of the electrode assembly. In some embodiments, the secondary battery 100 may be a rectangular parallelepiped, and the first direction X may be parallel to the length direction of the secondary battery 100, or the first direction X may be parallel to the width direction of the secondary battery 100. The thickness direction Z of the electrode assembly may be parallel to the thickness direction of the secondary battery 100.

[0073] The height of the first protrusion 211 protruding from the inner surface of the first wall 21 refers to the dimension of the first protrusion 211 protruding from the inner surface of the first wall 21 in the direction in which the first wall 21 points to the electrode assembly 10 .

[0074] In the thickness direction Z of the electrode assembly, one end of the inner surface of the third wall 23 may be connected to the inner surface of the first wall 21 , and the other end of the inner surface of the third wall 23 may be connected to the inner surface of the second wall 22 .

[0075] The first protrusion 211 may be in contact with the electrode assembly 10 , or the first protrusion 211 may be spaced apart from the electrode assembly 10 .

[0076] When viewed along the first direction X, the first protrusion 211 partially overlaps with the electrode assembly 10. When the electrode assembly 10 moves relative to the outer shell 20, after the electrode assembly 10 moves to contact the first protrusion 211, the first protrusion 211 can constrain the movement of the electrode assembly 10 and disperse the force of the electrode assembly 10 moving relative to the outer shell 20, thereby reducing the impact of the force on the weakest weld area of ​​the outer shell 20.

[0077] According to the secondary battery 100 of the embodiment of the present application, the first protrusion 211 protrudes toward the interior of the outer shell 20. Along the first direction X, the projection of the first protrusion 211 partially overlaps with the projection of the electrode assembly 10. When the electrode assembly 10 moves relative to the outer shell 20 along the first direction X, the first protrusion 211 can block the movement of the electrode assembly 10 relative to the outer shell 20. At the same time, the first protrusion disperses the force acting on the movement of the electrode assembly 10 relative to the outer shell 20, so that the force does not directly impact the weakest weld area of ​​the outer shell 20, thereby reducing the risk of weld cracking, so that the secondary battery 100 has higher reliability and improves the safety performance of the secondary battery 100.

[0078] In one or more of the above optional embodiments, L3≤L2 / 3.

[0079] In the above scheme, when L3≤L2 / 3, the protruding height of the first protrusion 211 is relatively low, which facilitates the processing and manufacturing of the first protrusion 211, and reduces the risk of interference between the first protrusion 211 and other components in the outer shell 20. For example, when the tab is arranged between the first end 11 and the third wall 23, the protruding height of the first protrusion 211 is relatively small, which can reduce the risk of interference between the first protrusion 211 and the tab.

[0080] In some embodiments, 2.64 mm ≤ L1 ≤ 12.54 mm.

[0081] Alternatively, L1 may be, but is not limited to, 2.64 mm, 3.04 mm, 3.54 mm, 3.94 mm, 4.54 mm, 4.94 mm, 5.44 mm, 5.94 mm, 6.44 mm, 6.94 mm, 7.44 mm, 7.94 mm, 8.44 mm, 8.94 mm, 9.44 mm, 9.94 mm, 10.44 mm, 10.94 mm, 11.44 mm, 11.94 mm, or 12.54 mm.

[0082] In some embodiments, 2.5 mm ≤ L2 ≤ 12.4 mm.

[0083] Optionally, L2 can be but is not limited to 2.5mm, 2.9mm, 3.4mm, 3.9mm, 4.4mm, 4.9mm, 5.4mm, 5.9mm, 6.4mm, 6.9mm, 7.4mm, 7.9mm, 8.4mm, 8.9mm, 9.4mm, 9.9mm, 10.4mm, 10.9mm, 11.4mm, 11.9mm or 12.4mm.

[0084] In some embodiments, 0.14 mm ≤ L3 ≤ 2.73 mm.

[0085] Alternatively, L3 may be, but is not limited to, 0.14 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.14 mm, 1.24 mm, 1.34 mm, 1.44 mm, 1.53 mm, 1.64 mm, 1.74 mm, 1.84 mm, 1.94 mm, 2.04 mm, 2.14 mm, 2.24 mm, 2.34 mm, 2.44 mm, 2.54 mm, 2.64 mm, or 2.73 mm. In one or more of the above optional embodiments, the first protrusion 211 contacts the first end 11 of the electrode assembly 10 in the first direction X.

[0086] The first end portion 11 is an end portion of the electrode assembly 10 in the first direction X. The electrode assembly 10 includes a positive electrode sheet 15, a negative electrode sheet 16, and a separator 17. The separator 17 is located between the adjacent positive electrode sheet 15 and negative electrode sheet 16. In the first direction X, the end portion of the negative electrode sheet 16 extends beyond the positive electrode sheet 15, and the end portion of the separator 17 extends beyond the negative electrode sheet 16. The end portion of the separator 17 is the first end portion 11. The contact between the first protrusion 211 and the first end portion 11 means that the first protrusion 211 is in contact with the separator 17.

[0087] In some embodiments, along the thickness direction Z of the electrode assembly, the projection of the first protrusion 211 may partially overlap with the projection of the first end portion 11 , or the projection of the first protrusion 211 may not overlap with the projection of the first end portion 11 .

[0088] In the above scheme, since the first protrusion 211 contacts the first end 11 of the electrode assembly 10 in the first direction X, the first protrusion 211 can prevent the electrode assembly 10 from moving relative to the outer shell 20 in the direction toward the first protrusion 211 in the first direction X, further improving the blocking effect of the first protrusion 211 on the electrode assembly 10.

[0089] Referring to FIG. 3 , in one or more of the above optional embodiments, a first groove 212 is formed on the outer surface of the first wall 21 at a position corresponding to the first protrusion 211 .

[0090] During the manufacturing process of the secondary battery 100 , the first wall 21 may be stamped from a single plate, so that the first convex portion 211 is formed on one side of the first wall 21 in a thickness direction, and the first concave portion 212 is formed on the other side.

[0091] In the above solution, the first wall 21 can be formed by stamping a plate-like structure, which is easy to process and manufacture.

[0092] 2 , in one or more of the above optional embodiments, the first protrusion 211 extends along the second direction Y, and the second direction Y, the first direction X, and the thickness direction Z of the electrode assembly are perpendicular to each other.

[0093] The first convex portion 211 extends along the second direction Y, that is, the length direction of the first convex portion 211 is parallel to the second direction Y, and the first convex portion 211 is longer in the second direction Y. The width direction of the first convex portion 211 may be parallel to the first direction X.

[0094] In the above solution, the first protrusion 211 has a longer dimension in the second direction Y, so that the first protrusion 211 has a better blocking effect on the electrode assembly 10 in the first direction X.

[0095] Please refer to Figure 3, and further to Figures 5 and 6. Figure 5 is a schematic diagram of the structure of a first convex portion with a rectangular cross-section provided in some embodiments of the present application, and Figure 6 is a schematic diagram of the structure of a first convex portion with a tapered cross-section provided in some embodiments of the present application. In one or more of the above optional embodiments, the cross-section of the first convex portion 211 is arc-shaped, rectangular, or tapered, and the cross-section of the first convex portion 211 is perpendicular to the second direction Y.

[0096] The cross section of the first convex portion 211 refers to a cross section of the first convex portion 211 cut along a plane perpendicular to the second direction Y.

[0097] When the cross section of the first protrusion 211 is arc-shaped, the arc protrudes toward the electrode assembly 10 .

[0098] When the cross section of the first protrusion 211 is rectangular, the intersection of two adjacent surfaces can be an arc transition, which is convenient for processing and manufacturing and reduces damage to the electrode assembly 10 .

[0099] In the above solution, the cross section of the first protrusion 211 is arc-shaped, rectangular or conical, which is convenient for processing and manufacturing.

[0100] In some embodiments, the first wall 21 includes a first body 210 and a first protrusion 211 protruding from the inner surface of the first body 210. The cross-section of the first protrusion 211 includes an arc segment and two straight line segments. The arc segment is located between the two straight line segments. One end of each straight line segment is connected to the first body 210, and the other end of each straight line segment is connected to the arc segment. The arc segment is located at the end of the first protrusion 211 away from the first body 210.

[0101] Please refer to Figures 3 to 6. In one or more optional embodiments above, the electrode assembly 10 has a first end 11 in the first direction X, and the housing 20 further includes a third wall 23 and a fourth wall 24 arranged opposite to each other along the first direction X. The third wall 23 is arranged opposite to the first end 11 in the first direction X, and the third wall 23 is closer to the first end 11 than the fourth wall 24. Along the first direction X, at least a portion of the first protrusion 211 is located between the first end 11 and the third wall 23.

[0102] The third wall 23 and the fourth wall 24 are located between the first wall 21 and the second wall 22. The two ends of the third wall 23 in the thickness direction Z of the electrode assembly are respectively connected to the first wall 21 and the second wall 22. The two ends of the fourth wall 24 in the thickness direction Z of the electrode assembly are respectively connected to the first wall 21 and the second wall 22. The third wall 23, the fourth wall 24, the first wall 21 and the second wall 22 form a storage space for accommodating the electrode assembly 10.

[0103] Along the first direction X, a portion of the first protrusion 211 is located between the first end 11 and the third wall 23 , and a projection of another portion of the first protrusion 211 in the thickness direction Z of the electrode assembly overlaps with a projection of the first end 11 in the thickness direction Z of the electrode assembly.

[0104] Along the first direction X, the first protrusion 211 is entirely located between the first end 11 and the third wall 23 , and the projection of the first protrusion 211 in the thickness direction Z of the electrode assembly does not overlap with the projection of the first end 11 in the thickness direction Z of the electrode assembly.

[0105] In the above scheme, along the first direction X, at least a portion of the first protrusion 211 is located between the first end 11 and the third wall 23. The first protrusion 211 can limit the movement of the electrode assembly 10 relative to the outer shell 20 toward the third wall 23, has a good blocking effect on the electrode assembly 10, and can disperse the force of the electrode assembly 10 moving relative to the outer shell 20 toward the third wall 23, thereby reducing the impact of the movement of the electrode assembly 10 on the weak parts of the outer shell 20.

[0106] Please refer to Figure 7, which is a cross-sectional view of a secondary battery provided in some embodiments of the present application. In one or more optional embodiments above, the secondary battery 100 further includes a tab 30 connected to the first end 11 and extending from the first end 11 along the first direction X.

[0107] The tabs 30 are electrically connected to the corresponding electrode sheets at the first end 11 to facilitate the extraction of electrical energy from the electrode assembly 10. The tabs 30 may include a positive tab and a negative tab 30a. The positive tab is electrically connected to the positive electrode sheet 15 of the electrode assembly 10, and the negative tab 30a is electrically connected to the negative electrode sheet 16 of the electrode assembly 10. For example, the positive tab is welded to the positive current collector of the positive electrode sheet 15, and the negative tab 30a is welded to the negative current collector of the negative electrode sheet 16. Alternatively, the positive tab is riveted to the positive current collector, and the negative tab 30a is riveted to the negative current collector. Alternatively, the positive tab is bonded to the positive current collector using a conductive adhesive, and the negative tab 30a is bonded to the negative current collector using a conductive adhesive.

[0108] In some embodiments, the positive electrode tab is connected to the positive electrode terminal set in the shell 20 through the positive electrode adapter, and the negative electrode tab 30a is connected to the negative electrode terminal set in the shell 20 through the negative electrode adapter 31, or the negative electrode tab 30a is connected to the shell 20 through the negative electrode adapter 31.

[0109] In the above solution, the tab is connected to the first end 11 , and an assembly space is reserved between the tab and the third wall 23 . The first protrusion 211 reasonably utilizes the assembly space in the housing 20 to reduce the impact on the energy density of the secondary battery 100 .

[0110] 3 , in one or more of the above optional embodiments, along the first direction X, the minimum distance between the first protrusion 211 and the inner surface of the third wall 23 is L4, satisfying 0.05 mm ≤ L4 ≤ 1 mm.

[0111] The inner surface of the third wall 23 is a surface of the third wall 23 facing the electrode assembly 10 .

[0112] The minimum distance between the first protrusion 211 and the inner surface of the third wall 23 is the distance between the end of the first protrusion 211 closest to the third wall 23 in the first direction X and the inner surface of the third wall 23. When the first protrusion 211 is parallel to the inner surface of the third wall 23, the distance between any position of the first protrusion 211 and the inner surface of the third wall 23 is the minimum distance between the first protrusion 211 and the inner surface of the third wall 23.

[0113] Alternatively, L4 may be, but is not limited to, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm or 1 mm.

[0114] In the above scheme, the minimum distance between the first protrusion 211 and the inner surface of the third wall 23 satisfies the above relationship. On the one hand, when L4 ≥ 0.05 mm, it is convenient for processing and manufacturing, and the risk of interference between the first protrusion 211 and the third wall 23 is reduced. On the other hand, when L4 ≤ 1 mm, the space occupied in the first direction X is small, which reduces the impact on the energy density of the secondary battery 100.

[0115] 3 , in one or more optional embodiments above, along the first direction X, the minimum distance between the first end portion 11 and the inner surface of the third wall 23 is L5, satisfying 0.17 mm ≤ L5 ≤ 1.5 mm.

[0116] The electrode assembly 10 includes a positive electrode sheet 15, a negative electrode sheet 16, and a separator 17. The separator 17 is disposed between the positive electrode sheet 15 and the negative electrode sheet 16. Furthermore, in the thickness direction Z of the electrode assembly, the separator 17 is disposed at the end of the electrode assembly 10 near the first wall 21 and the second wall 22. Typically, in the first direction X, the negative electrode sheet 16 extends beyond the edge of the positive electrode sheet 15. To prevent short circuiting between the positive electrode sheet 15 and the negative electrode sheet 16, the separator 17 extends beyond the edge of the negative electrode sheet 16 in the first direction X. Therefore, the first end 11 is the end of the separator 17 in the first direction X near the third wall 23.

[0117] Alternatively, L5 may be, but is not limited to, 0.17 mm, 0.27 mm, 0.37 mm, 0.47 mm, 0.57 mm, 0.67 mm, 0.77 mm, 0.87 mm, 0.97 mm, 1.07 mm, 1.17 mm, 1.27 mm, 1.37 mm, 1.47 mm, or 1.5 mm.

[0118] In some embodiments, along the first direction X, a minimum distance between the negative electrode tab 16 and the inner surface of the third wall 23 is greater than or equal to 0.67 mm and less than or equal to 2 mm.

[0119] Optionally, along the first direction X, the minimum distance between the negative electrode tab 16 and the inner surface of the third wall 23 may be, but is not limited to, 0.67 mm, 0.77 mm, 0.87 mm, 0.97 mm, 1.07 mm, 1.17 mm, 1.27 mm, 1.37 mm, 1.47 mm, 1.57 mm, 1.67 mm, 1.77 mm, 1.87 mm, 1.97 mm or 2 mm.

[0120] In the above scheme, the minimum distance between the first end portion 11 and the inner surface of the third wall 23 satisfies the above relationship. On the one hand, when L5 ≥ 0.17 mm, assembly space is reserved to reduce the risk of short circuit between the electrode assembly 10 and the third wall 23. On the other hand, when L5 ≤ 1.5 mm, a smaller space is occupied in the first direction X, reducing the impact on the energy density of the secondary battery 100.

[0121] 3 , in one or more optional embodiments above, along the first direction X, the minimum distance between the first end portion 11 and the inner surface of the third wall 23 is L5, and the width of the first protrusion 211 is L6, satisfying 0.4≤L6 / L5<1.

[0122] Optionally, L6 / L5 may be, but is not limited to, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9.

[0123] In the above scheme, the minimum distance between the first end portion 11 and the inner surface of the third wall 23 and the width of the first coating satisfy the above relationship. On the one hand, when L6 / L5 ≥ 0.4, the first protrusion 211 has a larger width, which is convenient for processing and manufacturing; on the other hand, when L6 / L5 < 1, the first protrusion 211 occupies a smaller space in the first direction X, reducing the impact on the energy density of the secondary battery 100. At the same time, assembly space is reserved to reduce the interference between the first protrusion 211 and the electrode assembly 10.

[0124] 3 , in one or more optional embodiments above, the first wall 21 is further provided with a second protrusion 213 protruding toward the interior of the housing 20 , and the second protrusion 213 is spaced apart from the first protrusion 211 along the first direction X.

[0125] In the embodiment where the first wall 21 includes the first body 210 , the second protrusion 213 protrudes from the inner surface of the first body 210 , and the structure of the second protrusion 213 may be the same as or similar to that of the first protrusion 211 .

[0126] The second convex portion 213 is disposed parallel to the first convex portion 211 , and the second convex portion 213 extends along the second direction Y.

[0127] The electrode assembly 10 further includes a second end portion 12 disposed opposite to the first end portion 11 in the first direction X, and the fourth wall 24 is closer to the second end portion 12 than the third wall 23 .

[0128] The second end 12 and the first end 11 are two opposite ends of the electrode assembly 10 in the first direction X. The fourth wall 24 is closer to the second end 12 than the third wall 23 , that is, the second end 12 is disposed facing the fourth wall 24 .

[0129] Along the first direction X, the projection of the second protrusion 213 partially overlaps with the projection of the electrode assembly 10 , and at least a portion of the second protrusion 213 is located between the second end portion 12 and the fourth wall 24 .

[0130] In some embodiments, along the first direction X, a portion of the second protrusion 213 is located between the second end 12 and the fourth wall 24, and a projection of another portion of the second protrusion 213 in the thickness direction Z of the electrode assembly overlaps with a projection of the second end 12 in the thickness direction Z of the electrode assembly. Alternatively, along the first direction X, the entire second protrusion 213 is located between the second end 12 and the fourth wall 24, and a projection of the second protrusion 213 in the thickness direction Z of the electrode assembly does not overlap with a projection of the second end 12 in the thickness direction Z of the electrode assembly.

[0131] In the above scheme, the second protrusion 213 cooperates with the first protrusion 211 to block the opposite ends of the electrode assembly 10 in the first direction X, limiting the movement of the electrode assembly 10 relative to the outer shell 20 in the first direction X. At the same time, the first protrusion and / or the second protrusion 213 disperse the force of the electrode assembly 10 moving relative to the outer shell 20, so that the force does not directly impact the weakest weld area of ​​the outer shell 20, thereby reducing the risk of weld cracking, so that the secondary battery 100 has higher reliability and improves the safety performance of the secondary battery 100.

[0132] In some embodiments, a second groove is formed on the outer surface of the first wall 21 at a position corresponding to the second protrusion 213 .

[0133] 3 , in one or more of the above optional embodiments, along the first direction X, the minimum distance between the second protrusion 213 and the inner surface of the fourth wall 24 is L7, satisfying 0.05 mm ≤ L7 ≤ 0.5 mm.

[0134] Optionally, L7 may be, but is not limited to, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm or 0.5 mm.

[0135] In the above scheme, the minimum distance between the second protrusion 213 and the inner surface of the fourth wall 24 satisfies the above relationship. On the one hand, when L7 ≥ 0.05 mm, it is convenient for processing and manufacturing, and the risk of interference between the second protrusion 213 and the fourth wall 24 is reduced. On the other hand, when L7 ≤ 0.5 mm, the space occupied in the first direction X is reduced, and the impact on the energy density of the secondary battery 100 is reduced.

[0136] Please refer to Figure 8 , which is a cross-sectional view taken along line CC of Figure 2 . In one or more of the above optional embodiments, the first wall 21 is further provided with a third protrusion 214 protruding toward the interior of the housing 20 .

[0137] In the embodiment where the first wall 21 includes the first body 210, the third protrusion 214 protrudes from the inner surface of the first body 210. The structure of the third protrusion 214 can be the same or similar to that of the first protrusion 211, but the third protrusion 214 is located at a different position from the first protrusion 211.

[0138] The housing 20 further includes a fifth wall 25 , whose ends in the first direction X are connected to the third wall 23 and the fourth wall 24 , and whose ends in the thickness direction Z of the electrode assembly are connected to the first wall 21 and the second wall 22 .

[0139] The fifth wall 25 , the first wall 21 , the second wall 22 , the third wall 23 and the fourth wall 24 form an accommodation space for accommodating the electrode assembly 10 .

[0140] In some embodiments, the fifth wall 25 may be disposed perpendicular to the second direction Y.

[0141] The electrode assembly 10 also has a third end 13 in the second direction Y. The second direction Y, the first direction X and the thickness direction Z of the electrode assembly are perpendicular to each other. Along the second direction Y, at least a portion of the third protrusion 214 is located between the third end 13 and the fifth wall 25. Along the second direction Y, the projection of the third protrusion 214 partially overlaps with the projection of the electrode assembly 10.

[0142] The third end portion 13 is an end portion of the electrode assembly 10 in the second direction Y.

[0143] Along the second direction Y, a portion of the third protrusion 214 is located between the third end portion 13 and the fifth wall 25, and a projection of another portion of the third protrusion 214 in the thickness direction Z of the electrode assembly overlaps with a projection of the third end portion 13 in the thickness direction Z of the electrode assembly. Alternatively, along the second direction Y, the entire third protrusion 214 is located between the third end portion 13 and the fifth wall 25, and a projection of the third protrusion 214 in the thickness direction Z of the electrode assembly does not overlap with a projection of the third end portion 13 in the thickness direction Z of the electrode assembly.

[0144] In the above scheme, the third protrusion 214 is arranged so that when the electrode assembly 10 moves relative to the outer shell 20 along the second direction Y, the third protrusion 214 can contact the electrode assembly 10 to prevent the electrode assembly 10 from moving relative to the outer shell 20. At the same time, the third protrusion disperses the force of the electrode assembly 10 moving relative to the outer shell 20, so that the force does not directly impact the weakest weld area of ​​the outer shell 20, thereby reducing the risk of weld cracking, so that the secondary battery 100 has higher reliability and improves the safety performance of the secondary battery 100.

[0145] In some embodiments, a third groove is formed on the outer surface of the first wall 21 at a position corresponding to the third protrusion 214 .

[0146] 2 , in one or more optional embodiments above, the third protrusion 214 extends along the first direction X, and one end of the third protrusion 214 close to the first protrusion 211 is spaced apart from the first protrusion 211 .

[0147] The third protrusion 214 extends along the first direction X, and a length direction of the third protrusion 214 is parallel to the first direction X.

[0148] In the first direction X, the third protrusion 214 is spaced apart from the first protrusion 211 at one end thereof close to the first protrusion 211 , and along the thickness direction Z of the electrode assembly, the projection of the third protrusion 214 does not overlap with the projection of the first protrusion 211 .

[0149] In the above solution, the third protrusion 214 has a longer dimension in the first direction X, so that the third protrusion 214 has a better blocking effect on the electrode assembly 10 in the second direction Y.

[0150] In some embodiments, along the first direction X, the length of the third protrusion 214 is greater than or equal to 0.6 times the dimension between the inner surface of the third wall 23 and the inner surface of the fourth wall 24, and less than or equal to 0.9 times the dimension between the inner surface of the third wall 23 and the inner surface of the fourth wall 24.

[0151] 2 , in one or more optional embodiments above, along the first direction X, the distance between the inner surface of the third wall 23 and the inner surface of the fourth wall 24 is L8, and the length of the third protrusion 214 is L9, satisfying 0.6L8≤L9≤0.9L8.

[0152] Alternatively, L9 may be, but is not limited to, 0.6L8, 0.65L8, 0.7L8, 0.75L8, 0.8L8, 0.85L8 or 0.9L8.

[0153] In the above scheme, the length of the third protrusion 214 and the distance between the inner surface of the third wall 23 and the inner surface of the fourth wall 24 satisfy the above relationship. On the one hand, when L9≥0.6L8, when the electrode assembly 10 moves along the second direction Y relative to the outer shell 20, the third protrusion 214 and the electrode assembly 10 can have a larger contact area, and the third protrusion 214 has a better blocking effect on the electrode assembly 10; on the other hand, when L9≤0.9L8, it is convenient for the processing and manufacturing of the third protrusion 214, reducing the risk of interference between the third protrusion 214 and the third wall 23 and the fourth wall 24.

[0154] Please refer to Figures 2, 3 and 8. In one or more optional embodiments above, the first wall 21 is further provided with a second protrusion 213, a third protrusion 214 and a fourth protrusion 215 protruding toward the interior of the shell 20. The second protrusion 213 and the first protrusion 211 are spaced apart along the first direction X, and the third protrusion 214 and the fourth protrusion 215 are spaced apart along the second direction Y. The second direction Y, the first direction X and the thickness direction Z of the electrode assembly are perpendicular to each other.

[0155] The electrode assembly 10 also has a second end 12, a third end 13 and a fourth end 14. The second end 12 is arranged opposite to the first end 11 along the first direction X, the third end 13 and the fourth end 14 are arranged opposite to each other along the second direction Y, and the fourth wall 24 is closer to the second end 12 than the third wall 23.

[0156] The housing 20 further includes a fifth wall 25 and a sixth wall 26 disposed opposite to each other along the second direction Y. The fifth wall 25 is closer to the third end 13 than the sixth wall 26 , and the sixth wall 26 is closer to the fourth end 14 than the fifth wall 25 .

[0157] Along the first direction X, the projection of the second protrusion 213 partially overlaps with the projection of the electrode assembly 10 , and at least a portion of the second protrusion 213 is located between the second end portion 12 and the fourth wall 24 .

[0158] Along the second direction Y, the projection of the third protrusion 214 partially overlaps with the projection of the electrode assembly 10, and at least a portion of the third protrusion 214 is located between the third end 13 and the fifth wall 25. The projection of the fourth protrusion 215 partially overlaps with the projection of the electrode assembly 10, and at least a portion of the fourth protrusion 215 is located between the fourth end 14 and the sixth wall 26.

[0159] In some embodiments, along the thickness direction Z of the electrode assembly, the projections of the first protrusion 211 , the second protrusion 213 , the third protrusion 214 , and the fourth protrusion 215 do not overlap with each other to facilitate processing and manufacturing.

[0160] In the above scheme, the second protrusion 213 cooperates with the first protrusion 211 to block the opposite ends of the electrode assembly 10 in the first direction X, and limit the movement of the electrode assembly 10 relative to the shell 20 in the first direction X. The third protrusion 214 cooperates with the fourth protrusion 215 to block the opposite ends of the electrode assembly 10 in the second direction Y, and limit the movement of the electrode assembly 10 relative to the shell 20 in the second direction Y. At the same time, the first protrusion 211, the second protrusion 213, the third protrusion 214 and the fourth protrusion 215 can disperse the force of the electrode assembly 10 moving relative to the shell 20 in a plane perpendicular to the thickness direction Z of the electrode assembly, so that the force does not directly impact the weakest weld area of ​​the shell 20, further making the secondary battery 100 have higher reliability and improving the safety performance of the secondary battery 100.

[0161] In some embodiments, a fourth groove is formed on the outer surface of the first wall 21 at a position corresponding to the fourth protrusion 215 .

[0162] 2 , in one or more optional embodiments above, the housing 20 further includes a fifth wall 25 and a sixth wall 26 arranged opposite to each other along the second direction Y, and the second direction Y, the first direction X, and the thickness direction Z of the electrode assembly are perpendicular to each other.

[0163] The electrode assembly 10 is located between the fifth wall 25 and the sixth wall 26 . The fifth wall 25 , the sixth wall 26 , the first wall 21 , the second wall 22 , the third wall 23 and the fourth wall 24 form an accommodating space for accommodating the electrode assembly 10 .

[0164] Along the second direction Y, the distance between the inner surface of the fifth wall 25 and the inner surface of the sixth wall 26 is L 10 , at least one of the following conditions is satisfied: (1) along the second direction Y, the length of the first protrusion 211 is L 11 , meet, 0.6L 10 ≤L 11 ≤0.9L 10 (2) Along the second direction Y, the minimum distance between the first protrusion 211 and the inner surface of the fifth wall 25 is L 12 , meet, 2mm≤L 12 ≤0.2L 10 .

[0165] The inner surface of the sixth wall 26 is the surface of the sixth wall 26 facing the electrode assembly 10 .

[0166] Optionally, L 11 Can be but not limited to 0.6L 10 , 0.65L 10 , 0.7L 10 , 0.75L 10 , 0.8L 10 , 0.85L 10 or 0.9L 10 .

[0167] Optionally, L 12 Can be but not limited to 2mm, 2.5mm, 0.05L 10 , 0.1L 10 , 0.15L 10 or 0.2L 10 .

[0168] In the above solution, when the length of the first protrusion 211 and the distance between the inner surface of the fifth wall 25 and the inner surface of the sixth wall 26 satisfy the above relationship (0.6L 10 ≤L 11 ≤0.9L 10 ), on the one hand, when L 11 ≥0.6L 10When the electrode assembly 10 moves relative to the housing 20 along the first direction X, the first protrusion 211 and the electrode assembly 10 can have a larger contact area, and the first protrusion 211 has a better blocking effect on the electrode assembly 10; on the other hand, when L 11 ≤0.9L 10 When the minimum distance between the first protrusion 211 and the inner surface of the fifth wall 25 and the distance between the inner surface of the fifth wall 25 and the inner surface of the sixth wall 26 meet the above relationship (2mm≤L 12 ≤0.2L 10 ), on the one hand, when L 12 ≥2mm, the risk of interference between the first protrusion 211 and the fifth wall 25 is reduced. On the other hand, when L 12 ≤0.2L 10 When the first protrusion 211 is spaced from the inner surface of the fifth wall 25 , the distance between the first protrusion 211 and the inner surface of the fifth wall 25 is small, thereby reducing space waste in the second direction Y and lowering the impact on the energy density of the secondary battery 100 .

[0169] In some embodiments, along the second direction Y, the length of the second protrusion 213 is greater than or equal to 0.6 times the distance between the inner surface of the fifth wall 25 and the inner surface of the sixth wall 26, and less than or equal to 0.9 times the distance between the inner surface of the fifth wall 25 and the inner surface of the sixth wall 26.

[0170] 1 and 3 , in one or more optional embodiments above, the housing 20 includes a shell 27 and a cover 28 , the shell 27 has an opening, the cover 28 closes the opening, and the first wall 21 serves as the cover 28 .

[0171] The second wall 22 , the third wall 23 , the fourth wall 24 , the fifth wall 25 and the sixth wall 26 of the frame form a housing 27 .

[0172] In the above solution, the first wall 21 is the cover 28 , which facilitates the processing and manufacturing of the first protrusion 211 and the assembly of the electrode assembly 10 into the outer shell 20 .

[0173] Please refer to Figures 9 and 10. Figure 9 is a schematic diagram of the assembly of the first adhesive member, the first wall, and the electrode assembly provided in some embodiments of the present application, and Figure 10 is a schematic diagram of the structure of the first adhesive member provided in some embodiments of the present application. In one or more of the above optional embodiments, the secondary battery 100 further includes a first adhesive member 41, which adheres the first wall 21 and the electrode assembly 10.

[0174] In the above solution, the first adhesive 41 bonds the first wall 21 and the electrode assembly 10 to limit the movement of the electrode assembly 10 relative to the first wall 21 and reduce the risk of the electrode assembly 10 impacting the weld of the housing 20 .

[0175] The first adhesive member 41 includes a first substrate layer 411 and a first adhesive layer 412 and a second adhesive layer 413 disposed on both sides of the first substrate layer 411 in the thickness direction. The first adhesive layer 412 is bonded to the electrode assembly 10, and the second adhesive layer 413 is bonded to the first wall 21. The thickness direction of the first substrate layer 411 is parallel to the thickness direction Z of the electrode assembly.

[0176] The material of the first adhesive layer 412 includes at least one of polyethylene oxide, acrylonitrile-styrene-butadiene copolymer, styrene-butadiene copolymer, polyvinyl alcohol, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyacrylic acid, polymethyl methacrylate, polypropylene, polyethylene or polyamide.

[0177] The material of the second adhesive layer 413 includes at least one of polymethyl methacrylate, polyacrylic acid, polyacrylic acid salt, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, styrene-isoprene-styrene block copolymer, ethylene-vinyl acetate copolymer, or polyimide.

[0178] The material of the first base material layer 411 includes at least one of polyethylene, polypropylene, polyethylene terephthalate, or polyimide.

[0179] In one or more of the above optional embodiments, the secondary battery 100 further includes a second adhesive member 42 , and the second adhesive member 42 bonds the second wall 22 and the electrode assembly 10 .

[0180] In the above solution, the second adhesive 42 bonds the second wall 22 and the electrode assembly 10 to limit the movement of the electrode assembly 10 relative to the second wall 22 and reduce the risk of the electrode assembly 10 impacting the weld of the housing 20 .

[0181] The second adhesive member 42 includes a second substrate layer and a third adhesive layer and a fourth adhesive layer disposed on both sides of the second substrate layer in the thickness direction. The third adhesive layer is bonded to the electrode assembly 10, and the fourth adhesive layer is bonded to the second wall 22. The thickness direction of the second substrate layer is parallel to the thickness direction Z of the electrode assembly.

[0182] The material of the third adhesive layer is the same as that of the first adhesive layer 412. The material of the fourth adhesive layer is the same as that of the second adhesive layer 413. The material of the second base material layer is the same as that of the first base material layer 411.

[0183] According to some embodiments of the present application, an electrochemical device is further provided, which includes the secondary battery 100 provided in any of the above embodiments.

[0184] According to some embodiments of the present application, an electrical device is further provided, which includes the electrochemical device provided in any of the above embodiments.

[0185] The following describes a specific embodiment

[0186] Example 1

[0187] A secondary battery 100 is assembled as follows:

[0188] (1) Preparation of negative electrode sheet: Mix the negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) in a weight ratio of 96:1.5:2.5, add deionized water as a solvent, prepare a slurry with a weight percentage of 70wt%, and stir evenly. The slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 10μm, leaving an empty foil area at the edge of the copper foil, and dried at 110℃ to obtain a negative electrode sheet with a coating thickness of 150μm and a single-sided negative electrode active material layer. Repeat the above steps on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided negative electrode active material layer. Then, the excess empty foil area is removed by laser die-cutting to obtain a negative electrode tab.

[0189] (2) Preparation of positive electrode sheet: The positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 12μm, leaving an empty foil area at the edge of the aluminum foil, and then dried at 90°C to obtain a positive electrode sheet with a positive electrode active material layer thickness of 100μm. When preparing other first electrodes coated on both sides, repeat the above coating steps on the other surface of the aluminum foil. Then, the excess empty foil area is removed by laser die-cutting to obtain a positive electrode tab.

[0190] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) was added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0191] (4) Preparation of the diaphragm: A three-layer diaphragm is used, which includes a first bonding layer, a first substrate layer, and a first bonding layer stacked in layers. The first substrate layer is made of polyethylene (PE), the first bonding layer contains a first adhesive, and the first bonding layer also contains inorganic ceramic particles Al2O3.

[0192] (5) Preparation of electrode assembly 10: The positive electrode sheet, the separator and the negative electrode sheet are stacked and arranged, and the stacked structure is hot-pressed on a flat plate for 10 seconds at a temperature of 80° C. and a pressure of 1.5 MPa to form an electrode assembly 10 for use.

[0193] (6) Assembly of the electrode assembly 10: Place the stainless steel shell with the pits formed in it into an assembly fixture with the pits facing upwards, place the electrode assembly 10 in the pits, and then cover the electrode assembly 10 with the cover with the first protrusions facing downwards. Use laser welding to seal the edges of the cover and the shell. The length of the secondary battery is 89.15 mm, the width of the secondary battery is 63.15 mm, and the thickness of the secondary battery is 8.49 mm; the length of the electrode assembly is 86.2 mm, the width of the electrode assembly is 60.2 mm, and the thickness L2 of the electrode assembly is 8.2 mm; the pit length of the stainless steel shell is 89 mm, the pit width is 63 mm, and the pit depth is 8.34 mm;

[0194] The length L of the first protrusion 11 The width L6 of the first protrusion is 43.5 mm, the height L3 of the first protrusion is 1.53 mm, and the minimum distance L4 between the first protrusion and the inner surface of the third wall along the first direction is 0.07 mm. The minimum distance L5 between the first end and the inner surface of the third wall is 1.4 mm, L6 / L5 is 0.32, and the dimension L1 of the inner surface of the third wall along the thickness direction of the electrode assembly is 8.34 mm. The distance L between the inner surface of the fifth wall and the inner surface of the sixth wall along the second direction is 0.07 mm. 10 63mm, L 11 / L 10 is 0.9.

[0195] (7) Liquid injection and packaging: The electrolyte is injected into the assembled electrode assembly 10, and the secondary battery 100 is manufactured through vacuum packaging, static standing, hot pressing, shaping and other processes.

[0196] Comparative Example 1

[0197] The difference from the first embodiment is that the cover (first wall) is not provided with the first protrusion.

[0198] Comparative Example 2

[0199] The difference from Example 1 is that the height L3 of the first convex portion is 0.13 mm.

[0200] Examples 2-8

[0201] The difference from Example 1 is that the width L6 of the first convex portion is different.

[0202] Examples 9-13

[0203] The difference from the first embodiment is that the minimum distance L4 between the first protrusion and the inner surface of the third wall is different.

[0204] Examples 14-21

[0205] The difference from Example 1 is that the height L3 of the first convex portion is different; and the width L3 of the first convex portion is 1.2 mm.

[0206] Examples 22-27

[0207] The difference from Example 1 is that the length L of the first convex portion is 11 different.

[0208] Examples 28-35

[0209] The difference from embodiment 1 is that the cover is further provided with a second convex portion.

[0210] The secondary batteries of the comparative examples and embodiments were subjected to a drop test. The test results are shown in Table 1.

[0211] The drop test method for secondary batteries is as follows: pre-treat the secondary battery at 25°C, let it stand at room temperature for 60 minutes, and then test the voltage of the secondary battery before the drop test; place the secondary battery in a fixture and use a drop device to freely drop it from a position 1.5m above the ground in the following order: head-tail-right corner of the head-right corner of the tail-left corner of the head-left corner of the tail (angle: 45±15°), and repeat 6 rounds. After the drop, measure and record the voltage of the secondary battery, and check the appearance of the secondary battery before and after the test and take pictures. The pass criteria for the drop test: no smoke, no leakage, and voltage drop <30mV. The pass rate of the drop test is: the proportion of 100 secondary batteries that pass the test.

[0212] Table 1

[0213] By comparing Comparative Example 1-2 and Example 1-35, it can be seen that, when other parameters are the same, in Comparative Example 1, the cover body (first wall) is not provided with the first protrusion, and the height of the first protrusion is 0. In Comparative Example 2, L3 is less than L1-L2, and the drop pass rate of Comparative Example 1 and Comparative Example 2 is low; in Example 1-35, L3 is greater than or equal to L1-L2, and the drop pass rate is high.

[0214] By comparing Examples 1-8, it can be seen that, when other parameters are the same, in Example 1 and Examples 4-7, 0.4≤L6 / L5<1, the drop pass rate is higher; in Examples 2 and 3, L6 / L5<0.4, the drop pass rate is lower; in Example 8, L6 / L5>1, the first protrusion exceeds the minimum distance between the first end and the inner surface of the third wall, the first protrusion interferes with the weld between the third wall and the first wall, and the drop pass rate is lower.

[0215] By comparing Example 1 with Examples 9-13, it can be seen that, when other parameters are the same, in Example 1 and Examples 10-12, 0.05mm≤L4≤1mm, the drop pass rate is higher; in Example 9, L4<0.05mm, the distance between the first protrusion and the inner surface of the third wall is relatively close, there is a problem with the outer shell packaging, a new weak point is formed, and the drop pass rate is low; in Example 13, L4>1mm, the distance between the first protrusion and the inner surface of the third wall is relatively far, which affects the performance of the battery cell and the drop pass rate is low.

[0216] By comparing Example 1 and Examples 14-21, it can be seen that, when other parameters are the same, in Example 1 and Example 14-20, (0.14mm) L2-L1≤L3≤L2 / 3(2.73mm), the drop pass rate is higher; in Example 21, L3>L2 / 3(2.73mm), the height of the first protrusion is too high, resulting in a decrease in the strength of the cover body and a lower drop pass rate.

[0217] Comparing Example 1 with Examples 22-27, it can be seen that, when other parameters are the same, in Example 1 and Examples 23-26, 0.6≤L 11 / L 10 ≤0.9, the drop pass rate is high; in Example 22, L 11 / L 10 <0.6, the length of the first convex portion is short, the first convex portion has a poor blocking effect on the electrode assembly, and the drop pass rate is low; in Example 27, L 11 / L 10 >0.9, the length of the first convex portion is too long, which affects the strength of the weld and the drop pass rate is low.

[0218] Comparing Example 1 with Examples 29-35, it can be seen that, with other parameters being the same, in Examples 29-35, the second protrusion is added, which improves the drop pass rate. Comparing Example 1 with Example 28, it can be seen that although the second protrusion is added, the minimum distance L7 between the second protrusion and the fourth wall is less than 0.05mm, but a new weak point is formed, resulting in a low drop pass rate. In Examples 29-24, 0.05mm≤L7≤0.5mm, the drop pass rate is high, and the performance of the secondary battery is less affected. In Example 35, L7>0.5mm, the second protrusion abuts the pole piece of the electrode assembly, affecting the performance of the secondary battery.

[0219] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A secondary battery, characterized in that: include: electrode assembly; a housing for accommodating the electrode assembly, the housing comprising a first wall and a second wall opposite to each other in a thickness direction of the electrode assembly; The first wall is provided with a first protrusion protruding toward the interior of the housing, and the housing further includes a third wall, the third wall connecting the first wall and the second wall, and the third wall is spaced apart from the electrode assembly along a first direction, and the first direction is perpendicular to the thickness direction of the electrode assembly; Along the thickness direction of the electrode assembly, the size of the inner surface of the third wall is L1, the thickness of the electrode assembly is L2, and the height of the first protrusion protruding from the inner surface of the first wall is L3, satisfying L3≥L1-L2.

2. The secondary battery according to claim 1, wherein L3≤L2 / 3.

3. The secondary battery according to claim 1, wherein The first protrusion contacts a first end portion of the electrode assembly in the first direction.

4. The secondary battery according to claim 1, wherein A first groove is formed on the outer surface of the first wall at a position corresponding to the first protrusion.

5. The secondary battery according to claim 1, wherein The first protrusion extends along a second direction, and the second direction, the first direction, and a thickness direction of the electrode assembly are perpendicular to each other.

6. The secondary battery according to claim 5, characterized in that The cross section of the first convex portion is arc-shaped, rectangular or conical, and the cross section of the first convex portion is perpendicular to the second direction.

7. The secondary battery according to claim 1, wherein The electrode assembly has a first end in the first direction, and the shell also includes a fourth wall. The third wall and the fourth wall are arranged opposite to each other along the first direction. The third wall is arranged opposite to the first end in the first direction. The third wall is closer to the first end relative to the fourth wall. Along the first direction, at least a portion of the first protrusion is located between the first end and the third wall.

8. The secondary battery according to claim 7, wherein: The secondary battery further includes a tab connected to the first end portion and extending out of the first end portion along the first direction; along the first direction, a minimum distance between the first protrusion and the inner surface of the third wall is L4, satisfying 0.05 mm ≤ L4 ≤ 1 mm.

9. The secondary battery according to claim 8, characterized in that Along the first direction, a minimum distance between the first end portion and the inner surface of the third wall is L5, satisfying 0.17 mm ≤ L5 ≤ 1.5 mm; a width of the first protrusion is L6, satisfying 0.4 ≤ L6 / L5 < 1.

10. The secondary battery according to claim 7, wherein The first wall is further provided with a second protrusion protruding toward the interior of the housing, and the second protrusion is spaced apart from the first protrusion along the first direction; The electrode assembly further includes a second end portion disposed opposite to the first end portion in the first direction, the fourth wall being closer to the second end portion than the third wall, a projection of the second protrusion partially overlapping with a projection of the electrode assembly along the first direction, and at least a portion of the second protrusion being located between the second end portion and the fourth wall; Along the first direction, a minimum distance between the second protrusion and the inner surface of the fourth wall is L7, satisfying 0.05 mm ≤ L7 ≤ 0.5 mm.

11. The secondary battery according to claim 7, wherein The first wall is further provided with a third protrusion protruding toward the interior of the housing; The housing further includes a fifth wall, wherein two ends of the fifth wall in the first direction are respectively connected to the third wall and the fourth wall, and two ends of the fifth wall in the thickness direction of the electrode assembly are respectively connected to the first wall and the second wall; The electrode assembly further has a third end portion in a second direction, wherein the second direction, the first direction, and the thickness direction of the electrode assembly are perpendicular to each other, and along the second direction, at least a portion of the third protrusion is located between the third end portion and the fifth wall; Along the second direction, the projection of the third protrusion partially overlaps with the projection of the electrode assembly; The third convex portion extends along the first direction, and one end of the third convex portion close to the first convex portion is spaced apart from the first convex portion; Along the first direction, a distance between an inner surface of the third wall and an inner surface of the fourth wall is L8, and a length of the third protrusion is L9, satisfying 0.6L8≤L9≤0.9L8.

12. The secondary battery according to claim 7, wherein The first wall is further provided with a second protrusion, a third protrusion, and a fourth protrusion protruding toward the interior of the housing, the second protrusion and the first protrusion are spaced apart along the first direction, the third protrusion and the fourth protrusion are spaced apart along the second direction, and the second direction, the first direction, and the thickness direction of the electrode assembly are perpendicular to each other; The electrode assembly further comprises a second end, a third end, and a fourth end, wherein the second end is arranged opposite to the first end along the first direction, the third end and the fourth end are arranged opposite to each other along the second direction, and the fourth wall is closer to the second end than the third wall. The housing further comprises a fifth wall and a sixth wall arranged opposite to each other along the second direction, the fifth wall is closer to the third end than the sixth wall, and the sixth wall is closer to the fourth end than the fifth wall. Along the first direction, a projection of the second protrusion partially overlaps with a projection of the electrode assembly, and at least a portion of the second protrusion is located between the second end portion and the fourth wall; Along the second direction, the projection of the third protrusion partially overlaps with the projection of the electrode assembly, and at least a portion of the third protrusion is located between the third end and the fifth wall. The projection of the fourth protrusion partially overlaps with the projection of the electrode assembly, and at least a portion of the fourth protrusion is located between the fourth end and the sixth wall.

13. The secondary battery according to claim 1, wherein The housing further includes a fifth wall and a sixth wall disposed opposite to each other along a second direction, wherein the second direction, the first direction, and the thickness direction of the electrode assembly are perpendicular to each other, and along the second direction, the distance between the inner surface of the fifth wall and the inner surface of the sixth wall is L. 10 ; Along the second direction, the length of the first protrusion is L 11 , meet, 0.6L 10 ≤L 11 ≤0.9L 10 and / or Along the second direction, the minimum distance between the first protrusion and the inner surface of the fifth wall is L 12 , meet, 2mm≤L 12 ≤0.2L 10 .

14. The secondary battery according to claim 1, wherein The housing includes a shell and a cover. The shell has an opening. The cover closes the opening. The first wall serves as the cover.

15. An electrochemical device, characterized in that The invention comprises the secondary battery according to any one of claims 1 to 14.

Images