Secondary battery, battery pack, and electric device

Abstract

The utility model discloses a secondary battery, a battery pack and a power utilization device, and belongs to the technical field of batteries, the secondary battery comprises a shell, a top cover assembly, an insulating part and an electrode assembly, and the shell is provided with an accommodating cavity; the top cover assembly has a width direction, and the top cover assembly is connected with the shell and covers and seals the accommodating cavity; the insulating part is arranged in the containing cavity and comprises a body part and a protruding part, the body part is provided with an insulating cavity, the body part and the shell are arranged in a spaced mode in the width direction and form a gap, and the protruding part is arranged in the gap and connected with the body part; the electrode assembly is arranged in the insulating cavity and connected with the insulating part, the electrode assembly is connected with the top cover assembly, and the protruding part can generate elastic deformation. According to the lithium ion battery, the protruding part is arranged to fill the gap between the electrode assembly and the shell, and the clamping force can be applied to the electrode assembly when the electrode assembly expands or contracts, so that the gap between the pole pieces is avoided, and the electrochemical performance of the lithium ion battery is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a secondary battery, a battery pack and a power utilization device. BACKGROUND

[0002] The battery will be charged and discharged for many times in use. The electrode assembly in the battery will expand when charged and shrink when discharged.

[0003] However, after repeated expansion and shrinkage, gaps are easily generated between the pole pieces, the lithium ion transmission path is lengthened, and the electrochemical performance of the lithium ion battery is reduced. UTILITY MODEL CONTENT

[0004] The utility model aims to provide a secondary battery to solve the technical problem of reduced electrochemical performance of a lithium ion battery, another purpose of the application is to provide a battery pack, and another purpose of the application is to provide a power utilization device.

[0005] Technical scheme, the application provides a secondary battery, which comprises:

[0006] A shell having a containing cavity;

[0007] A top cover assembly having a width direction, the top cover assembly is connected with the shell and covers the containing cavity;

[0008] An insulating piece arranged in the containing cavity, the insulating piece comprises a body part and a protruding part, the body part has an insulating cavity, the body part is arranged along the width direction and spaced apart from the shell to form a gap, and the protruding part is arranged in the gap and connected with the body part;

[0009] An electrode assembly arranged in the insulating cavity and connected with the insulating piece, the electrode assembly is connected with the top cover assembly, and the protruding part can be elastically deformed.

[0010] In some embodiments, the top cover assembly further has a length direction and a thickness direction, the width direction, the length direction and the thickness direction intersect with each other, the protruding part comprises a plurality of first elastic pieces, the first elastic pieces are connected with the body part, and the plurality of first elastic pieces are arranged in an array along the length direction and the thickness direction.

[0011] In some embodiments, the first elastic piece has a cavity.

[0012] In some embodiments, the protruding part comprises a first protruding subpart and a second protruding subpart, and the first protruding subpart is arranged around the second protruding subpart.

[0013] In some embodiments, along the width direction, the first protruding sub-portion has a maximum dimension W1 mm, and the second protruding sub-portion has a maximum dimension W2 mm, satisfying: W1 < W2.

[0014] In some embodiments, the first protruding sub-portion comprises a plurality of second elastic members connected with the body portion.

[0015] In some embodiments, the top cover assembly further has a length direction and a thickness direction, the width direction, the length direction and the thickness direction intersecting; and the plurality of second elastic members are arranged in an array along the length direction and the thickness direction.

[0016] In some embodiments, the second protruding sub-portion has a connecting surface located on a side of the second protruding sub-portion away from the body portion along the width direction.

[0017] In some embodiments, the second protruding sub-portion comprises a plurality of third elastic members connected with the body portion.

[0018] In some embodiments, the plurality of third elastic members are arranged in an array along the length direction and the thickness direction.

[0019] In some embodiments, the protruding portion comprises a plurality of fourth elastic members arranged along a direction perpendicular to the width direction.

[0020] In some embodiments, the fourth elastic members have a maximum dimension W3 mm along the width direction; and along a direction perpendicular to the width direction, the maximum dimension W3 mm of the plurality of fourth elastic members along the width direction first increases and then decreases.

[0021] Correspondingly, the present application further provides a battery pack comprising the secondary battery as described in any one of the above embodiments.

[0022] Correspondingly, the present application further provides an electric device comprising the secondary battery as described in any one of the above embodiments, or comprising the battery pack as described in any one of the above embodiments.

[0023] Beneficial effects: compared with the prior art, the secondary battery provided by the embodiment of the application comprises a shell, a top cover assembly, an insulating piece and an electrode assembly, the shell has a containing cavity; the top cover assembly has a width direction, the top cover assembly is connected with the shell and covers and seals the containing cavity; the insulating piece is arranged in the containing cavity, the insulating piece comprises a body part and a protruding part, the body part has an insulating cavity, the body part is arranged along the width direction and spaced apart from the shell to form a gap, the protruding part is arranged in the gap and connected with the body part; the electrode assembly is arranged in the insulating cavity and connected with the insulating piece, the electrode assembly is connected with the top cover assembly, and the protruding part can be elastically deformed. The protruding part is arranged to fill the gap between the electrode assembly and the shell, so that clamping force can be applied to the electrode assembly when the electrode assembly expands or shrinks, thereby avoiding the generation of a gap between the pole pieces, and the electrochemical performance of the lithium ion battery is improved.

[0024] Correspondingly, the application also provides a battery pack comprising the secondary battery according to any one of the above embodiments, which comprises the technical solutions and technical effects of the secondary battery according to any one of the above embodiments.

[0025] Correspondingly, the application also provides an electric device comprising the secondary battery according to any one of the above embodiments, which comprises the technical solutions and technical effects of the secondary battery according to any one of the above embodiments; or comprising the battery pack according to any one of the above embodiments, which comprises the technical solutions and technical effects of the battery pack according to any one of the above embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0026] The technical solutions and other beneficial effects of the application will become apparent from the following detailed description of the application, taken in conjunction with the accompanying drawings.

[0027] Figure 1 A structure diagram of the secondary battery provided by the embodiment of the application is shown in the figure;

[0028] Figure 2 A structure diagram of an embodiment of the secondary battery provided by the embodiment of the application, which comprises a first elastic piece, is shown in the figure;

[0029] Figure 3 An expanded diagram of the insulating piece of the secondary battery provided by the embodiment of the application, which comprises a first elastic piece, is shown in the figure;

[0030] Figure 4 A structure diagram of an embodiment of the secondary battery provided by the embodiment of the application, which comprises a second elastic piece, is shown in the figure;

[0031] Figure 5 An expanded diagram of the insulating piece of the secondary battery provided by the embodiment of the application, which comprises a second elastic piece, is shown in the figure;

[0032] Figure 6A structure diagram of an embodiment of the secondary battery including a plurality of second elastic members provided by the embodiment of the present application;

[0033] Figure 7 An expanded diagram of an insulating member including a fourth elastic member in a secondary battery provided by the embodiment of the present application.

[0034] Figure 8 A structure diagram of an embodiment of the secondary battery including a fourth elastic member provided by the embodiment of the present application;

[0035] Figure 9 An expanded diagram of an insulating member including a fourth elastic member in a secondary battery provided by the embodiment of the present application.

[0036] The reference signs, 100 - a housing, 110 - a receiving cavity, 200 - a top cover assembly, 300 - an insulating member, 310 - a body portion, 311 - an insulating cavity, 312 - a gap, 320 - a protruding portion, 321 - a first elastic member, 3211 - a cavity, 322 - a first protruding sub-portion, 3221 - a second elastic member, 323 - a second protruding sub-portion, 3231 - a third elastic member, 3232 - a connecting surface, 3241 - a fourth elastic member, 400 - an electrode assembly. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0038] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected or can communicate with each other; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In the description of the present application, the meaning of "a plurality of" is two or more than two, unless otherwise explicitly specified and limited. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more features.

[0039] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplifying the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0040] To solve the technical problem of the above-mentioned reduction of the electrochemical performance of the lithium ion battery, the first embodiment of the present application provides a secondary battery, please refer to Figure 1 The secondary battery includes a shell 100, a top cover assembly 200, an insulating piece 300, and an electrode assembly 400. The shell 100 has a receiving cavity 110. The top cover assembly 200 has a width direction Y. The top cover assembly 200 is connected with the shell 100 and covers the receiving cavity 110. The insulating piece 300 is arranged in the receiving cavity 110. The insulating piece 300 includes a body part 310 and a protruding part 320. The body part 310 has an insulating cavity 311. The body part 310 is arranged along the width direction Y and spaced apart from the shell 100 to form a gap 312. The protruding part 320 is arranged in the gap 312 and connected with the body part 310. The electrode assembly 400 is arranged in the insulating cavity 311 and connected with the insulating piece 300. The electrode assembly 400 is connected with the top cover assembly 200. The protruding part 320 can be elastically deformed.

[0041] Among them, the width direction Y is the direction of the arrow Y in the drawing.

[0042] In some embodiments, the protruding part 320 can abut against the shell 100. Specifically, during the assembly of the secondary battery, in order to facilitate the insulating piece 300 and the electrode assembly 400 to be assembled into the receiving cavity 110, the maximum size of the insulating piece 300 in the width direction Y is smaller than the size of the receiving cavity 110 in the width direction Y. After the secondary battery is subjected to charging and discharging, the electrode assembly 400 expands, and the protruding part 320 contacts or abuts against the shell 100.

[0043] In some embodiments, the protruding part 320 can at least be elastically deformed in the width direction Y to apply a force to the electrode assembly 400 along the width direction Y, thereby reducing the possibility of generating a gap 312 between the adjacent pole pieces in the electrode assembly 400 along the width direction Y.

[0044] In the above-mentioned embodiments, by arranging the insulating piece 300 with the protruding part 320 in the gap 312 to fill the gap 312, the electrode assembly 400 can always be indirectly connected with the shell 100 through the insulating piece 300 when expanding and shrinking. The shell 100 can apply a clamping force to the electrode assembly 400 when the electrode assembly 400 expands and shrinks, so that the pole pieces in the electrode assembly 400 are more tightly connected, reducing the possibility of generating a gap 312 between the adjacent pole pieces in the electrode assembly 400 when expanding and shrinking, and improving the electrochemical performance of the secondary battery.

[0045] In some embodiments, referring to Figure 2 and Figure 3 , Figure 3 is an expanded view of the insulating piece 300, the top cover assembly 200 also has a length direction X and a thickness direction Z, the width direction Y, the length direction X and the thickness direction Z intersect with each other; the protruding part 320 includes a plurality of first elastic pieces 321, the first elastic pieces 321 are connected with the body part 310, and the plurality of first elastic pieces 321 are arrayed along the length direction X and the thickness direction Z.

[0046] Wherein, the length direction X is the direction of the arrow X in the drawing; the thickness direction Z is the direction of the arrow Z in the drawing.

[0047] In some embodiments, two first elastic pieces 321 adjacent along the length direction X are connected; in another embodiment, two first elastic pieces 321 adjacent along the thickness direction Z are connected.

[0048] In the above embodiments, referring to Figure 3 , the first elastic pieces 321 arrayed along the length direction X and the thickness direction Z can make the entire large surface of the electrode assembly 400 bear force more uniformly, so that the first elastic pieces 321 have a better effect of reducing the gap 312 between the electrode pieces.

[0049] In some embodiments, the shape of the first elastic piece 321 is hemispherical, the spherical surface of the first elastic piece 321 faces the shell 100, and the flat surface is connected with the body part 310.

[0050] In some embodiments, referring again to Figure 2 , the first elastic piece 321 has a cavity 3211.

[0051] In the above embodiments, by providing the cavity 3211 inside the first elastic piece 321 to improve the elasticity of the first elastic piece 321, the insulating piece 300 can withstand a larger degree of expansion of the electrode assembly 400, and can tightly fit with the electrode assembly 400 when the electrode assembly 400 shrinks to a greater extent, and provide clamping force for the electrode assembly 400.

[0052] In some embodiments, referring to Figure 4 , Figure 5 , Figure 6 and Figure 7 , the protruding part 320 includes a first protruding sub-part 322 and a second protruding sub-part 323, and the first protruding sub-part 322 is arranged around the second protruding sub-part 323.

[0053] In some embodiments, the first protruding sub-part 322 will only abut against the shell 100 after the electrode assembly 400 expands; in some embodiments, the second protruding sub-part 323 always abuts against the shell 100.

[0054] The electrode assembly 400 has a larger expansion range in the central region along the length direction X and the thickness direction Z during expansion, and a smaller expansion range in the peripheral region. The first protruding sub portion 322 and the second protruding sub portion 323 are arranged to adapt to the difference in the expansion range of the electrode assembly 400 during expansion, so that the clamping force applied to the electrode assembly 400 during expansion is more balanced, and the separation of the electrode tab in the local region of the electrode assembly 400 is avoided.

[0055] In some embodiments, referring to Figure 4 and Figure 6 , along the width direction Y, the first protruding sub portion 322 has a maximum size W1 mm, and the second protruding sub portion 323 has a maximum size W2 mm, which satisfies: W1 < W2.

[0056] In the above embodiment, since the maximum size W1 of the first protruding sub portion 322 is smaller than the maximum size W2 of the second protruding sub portion 323, it can be ensured that the second protruding sub portion 323 contacts the shell 100 earlier than the first protruding sub portion 322 during click expansion, so that the middle region with a larger expansion range is earlier constrained by the clamping force, and the possibility of gap 312 between the electrode tabs in the expansion region is reduced.

[0057] In some embodiments, referring to Figure 5 and Figure 7 , the first protruding sub portion 322 includes a plurality of second elastic members 3221, and the second elastic members 3221 are connected with the body portion 310.

[0058] In the above embodiment, the first protruding sub portion 322 includes a plurality of second elastic members 3221, which can make the clamping force applied by the first protruding sub portion 322 to the electrode assembly 400 more uniform during expansion of the electrode assembly 400, reduce the possibility of gap 312 between the electrode tabs in the local region of the electrode assembly 400, and improve the electrochemical performance of the electrode assembly 400.

[0059] In some embodiments, the second elastic member 3221 is in a semispherical shape, the spherical surface of the second elastic member 3221 faces the shell 100, and the flat surface is connected with the body portion 310.

[0060] In some embodiments, referring to Figure 5 and Figure 7 , the top cover assembly 200 also has a length direction X and a thickness direction Z, and the width direction Y, the length direction X and the thickness direction Z intersect; and the plurality of second elastic members 3221 are arranged in an array along the length direction X and the thickness direction Z.

[0061] In some embodiments, referring to Figure 5 and Figure 7In some embodiments, referring again to Figs. 1 and 2, the second elastic member 3221 is arranged in an array along the length direction X and the thickness direction Z.

[0062] In the above embodiments, referring to Figure 3 The second elastic member 3221 arranged in an array along the length direction X and the thickness direction Z can make the force on the entire large surface of the electrode assembly 400 more uniform, and the second elastic member 3221 can better reduce the gap 312 between the electrode pieces.

[0063] In some embodiments, referring again to Figure 6 and Figure 7 The second protruding sub-portion 323 includes a plurality of third elastic members 3231, and the third elastic members 3231 are connected to the body portion 310.

[0064] In some embodiments, the third elastic member 3231 includes a first portion and a second portion connected along the width direction Y, the first portion is columnar, the first portion is connected to the body portion 310, and the second portion is hemispherical, the second portion is connected to a side of the first portion away from the body portion 310 along the width direction Y, and a spherical surface of the second portion is used to abut against the shell.

[0065] In the above embodiments, by arranging a plurality of third elastic members 3231, the part with the largest expansion range of the electrode assembly 400 during the expansion process can bear more uniform clamping force, and the third elastic member 3231 can better reduce the gap 312 between the electrode pieces.

[0066] In some embodiments, referring again to Figure 7 The plurality of third elastic members 3231 are arranged in an array along the length direction X and the thickness direction Z.

[0067] In some embodiments, two third elastic members 3231 adjacent along the length direction X are connected; in another embodiment, two third elastic members 3231 adjacent along the thickness direction Z are connected.

[0068] In the above embodiments, the third elastic member 3231 arranged in an array along the length direction X and the thickness direction Z can make the force on the entire large surface of the electrode assembly 400 more uniform, and the third elastic member 3231 can better reduce the gap 312 between the electrode pieces.

[0069] In some embodiments, referring again to Figure 4 and Figure 5 The second protruding sub-portion 323 has a connecting surface 3232 located on a side of the second protruding sub-portion 323 away from the body portion 310 along the width direction Y.

[0070] In some embodiments, the connection surface 3232 is formed by the plurality of third elastic members 3231 facing the housing 100 in the width direction Y.

[0071] In some embodiments, the second protruding sub-section 323 has and only has one third elastic member 3231, and the third elastic member 3231 has a connection surface 3232 facing the housing 100 for connecting with the housing 100.

[0072] In the above embodiments, by setting the connection surface 3232 to increase the contact area of the third elastic member 3231 with a larger size in the thickness direction Z with the housing 100, the clamping force exerted by the third elastic member 3231 on the electrode assembly 400 is more uniform, and the third elastic member 3231 reduces the gap 312 between the electrode tabs better.

[0073] In some embodiments, referring again to Figure 4 , the maximum size H of the third elastic member 3231 in the length direction X decreases in the width direction Y. In other embodiments, the size of the third elastic member 3231 in the thickness direction Z decreases in the width direction Y.

[0074] In the above embodiments, the actual shape of the third elastic member 3231 is a boss shape, which can reduce the possibility of interference between the third elastic member 3231 and the first protruding sub-section 322 when elastic deformation occurs, so that the third elastic member 3231 and the first protruding sub-section 322 can smoothly elastically deform to exert a clamping force on the electrode assembly 400.

[0075] In some embodiments, referring to Figure 9 , the protruding section 320 includes a plurality of fourth elastic members 3241 arranged in a direction perpendicular to the width direction Y.

[0076] In some embodiments, the direction perpendicular to the width direction Y includes the length direction X; in other embodiments, the direction perpendicular to the width direction Y includes the thickness direction Z; in yet other embodiments, the direction perpendicular to the width direction Y also includes a direction inclined to both the length direction X and the width direction Y.

[0077] In some embodiments, the plurality of fourth elastic members 3241 are arranged in a plurality of directions perpendicular to the width direction Y. In other words, the plurality of fourth elastic members 3241 are arranged radially in the direction perpendicular to the width direction Y.

[0078] In some embodiments, the plurality of fourth elastic members 3241 are arranged in a plurality of directions perpendicular to the width direction Y. In other words, the plurality of fourth elastic members 3241 are arranged radially in the direction perpendicular to the width direction Y.

[0079] In the above embodiment, the plurality of fourth elastic members 3241 arranged in the direction perpendicular to the width direction Y can make the entire large surface of the electrode assembly 400 bear force more uniformly, so that the fourth elastic members 3241 have a better effect of reducing the gap 312 between the pole pieces.

[0080] In some embodiments, referring again to Figure 8 , the fourth elastic member 3241 is semispherical in shape, the spherical surface of the fourth elastic member 3241 faces the shell 100, and the flat surface is connected to the body portion 310.

[0081] In some embodiments, referring again to Figure 8 , the fourth elastic member 3241 has a maximum dimension W3 mm in the width direction Y, and in the direction perpendicular to the width direction Y, the maximum dimension W3 mm of the plurality of fourth elastic members 3241 in the width direction Y first increases and then decreases.

[0082] In the above embodiment, the fourth elastic member 3241 at the middle position perpendicular to the width direction Y has the maximum dimension in the width direction Y, and the fourth elastic member 3241 at the peripheral region has a smaller dimension, so that the middle region of the electrode assembly 400, which has the largest expansion range, can be clamped first to avoid the gap 312 between the pole pieces in the middle region.

[0083] Correspondingly, the application also provides a battery pack comprising the secondary battery according to any one of the above embodiments.

[0084] Correspondingly, the application also provides a power consumption device comprising the secondary battery according to any one of the above embodiments or the battery pack according to any one of the above embodiments. The power consumption device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an energy storage cabinet, an electric tool, and the like. The vehicle can be a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle, or a range extended vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, and the like. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric plane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, etc. The embodiments of the application do not specially limit the above power consumption devices.

[0085] The above describes in detail a secondary battery, a battery pack and a power utilization device provided by the embodiments of the present application. The principles and implementation manners of the present application are described by using specific examples. The above embodiment descriptions are only used to help understand the technical solutions of the present application and the core ideas thereof. Those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A secondary battery characterized by comprising: The application relates to a secondary battery. The secondary battery comprises a shell, a top cover assembly, an insulation piece and an electrode assembly. The shell has a containing cavity. The top cover assembly has a width direction and is connected with the shell and covers the containing cavity. The insulation piece is arranged in the containing cavity and comprises a body part and a protruding part.

2. The secondary battery according to claim 1, characterized by The body part has an insulation cavity and is arranged in the containing cavity and spaced apart from the shell along the width direction.

3. The secondary battery according to claim 2, characterized by The protruding part is arranged in a gap between the body part and the shell and is connected with the body part.

4. The secondary battery according to claim 1, characterized by The electrode assembly is arranged in the insulation cavity and connected with the insulation piece.

5. The secondary battery according to claim 4, characterized by The electrode assembly is connected with the top cover assembly.

6. The secondary battery according to claim 5, characterized by The protruding part can be elastically deformed.

7. The secondary battery according to claim 6, characterized by The top cover assembly further has a length direction and a thickness direction.

8. The secondary battery according to claim 4, characterized by The width direction, the length direction and the thickness direction intersect with each other.

9. The secondary battery according to claim 7, characterized by The protruding part comprises a plurality of first elastic pieces connected with the body part.

10. The secondary battery according to claim 9, characterized by The first elastic pieces are arranged in an array along the length direction and the thickness direction.

11. The secondary battery according to claim 1, characterized by The first elastic piece has a cavity.

12. The secondary battery according to claim 11, characterized by The protruding part comprises a first protruding subpart and a second protruding subpart.

13. A battery pack, characterized by The first protruding subpart is arranged around the second protruding subpart.

14. An electrical device, comprising: Along the width direction, the first protruding subpart has a maximum size W1 mm and the second protruding subpart has a maximum size W2 mm. W1 < W2. The first protruding subpart comprises a plurality of second elastic pieces connected with the body part. The top cover assembly further has a length direction and a thickness direction. The width direction, the length direction and the thickness direction intersect with each other. The plurality of second elastic pieces are arranged in an array along the length direction and the thickness direction. The second protruding subpart has a connecting surface located on a side of the second protruding subpart away from the body part along the width direction. The second protruding subpart comprises a plurality of third elastic pieces connected with the body part. The plurality of third elastic pieces are arranged in an array along the length direction and the thickness direction. The protruding part comprises a plurality of fourth elastic pieces arranged along a direction perpendicular to the width direction. The fourth elastic piece has a maximum size W3 mm along the width direction. The maximum size W3 mm of the plurality of fourth elastic pieces along the width direction first increases and then decreases along a direction perpendicular to the width direction. The application relates to a secondary battery. The application relates to a secondary battery. The application relates to a secondary battery.

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