Crash pad, battery cell, battery, and electrical device having same

Abstract

A crash pad (30), a battery cell (100), a battery (1000), and an electrical device having same. The crash pad (30) comprises: a body part (31) and a weak part (32), the weak part (32) being arranged on the body part (31) and at least partially protruding from the surface of the body part (31), wherein the crash pad (30) has a first buffer state and a second buffer state. In the first buffer state, the weak part (32) protrudes from the surface of the body part (31), and the crash pad (30) supports an electrode assembly (20) by means of the weak part (32). In the second buffer state, the weak part (32) is broken, and the crash pad (30) supports the electrode assembly (20) by means of the body part (31).

Description

Buffer pad, battery cell, battery and electrical equipment having the same

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 2023225822391 and application date September 21, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a buffer pad, a battery cell, a battery, and an electrical device having the same. Background Art

[0004] Lithium-ion batteries have the advantages of high volumetric and mass energy density, long life, low self-discharge, and environmental friendliness. They are widely used in mobile communications devices, portable electronic devices such as laptops, and electric vehicles. However, during the charge and discharge cycle of lithium-ion batteries, the battery cells are prone to expansion and deformation. When the battery cells expand, the electrodes are prone to wrinkling, causing lithium deposition during the cycle. In related technologies, buffer pads are often placed in the battery, but the structural design of the buffer pads is unreasonable, making it difficult to solve the problem of a sharp increase in the expansion force of the battery cells in the later stages of recycling.

[0005] Application Contents

[0006] This application aims to solve at least one of the technical problems existing in the prior art. To this end, this application proposes a buffer pad that can reduce electrode deformation, improve electrode wrinkling caused by electrode assembly expansion, and thereby alleviate the problem of lithium deposition in the electrode assembly during cycling. It can also limit the expansion of the electrode assembly, thereby limiting the growth of the electrode assembly's expansion force. It can also provide the required space for the electrode assembly to expand, reducing the risk of a sharp increase in the expansion force of the battery cell in the later stages of cycling, and increasing the cycle life of the battery cell.

[0007] The present application also provides a battery cell having the buffer pad.

[0008] The present application also provides a battery having the above-mentioned battery cell.

[0009] The present application also provides an electrical device having the battery.

[0010] According to the buffer pad of the first aspect of the present application, the buffer pad is arranged in the shell of the battery cell, and the buffer pad includes: a main body portion; a weak portion, the weak portion is arranged in the main body portion and at least partially protrudes from the surface of the main body portion, wherein the buffer pad has a first buffer state and a second buffer state, in the first buffer state, the weak portion protrudes from the surface of the main body portion, and the buffer pad supports the electrode assembly through the weak portion, and in the second buffer state, the weak portion is destroyed, and the buffer pad supports the electrode assembly through the main body portion.

[0011] According to the buffer pad of the present application, by setting the main body and the weak part, the buffer pad can have a good supporting effect on the electrode assembly in the early and late stages of the cycle of the electrode assembly, reduce the deformation of the pole piece, and further improve the wrinkling of the pole piece caused by the expansion of the electrode assembly, thereby alleviating the lithium plating problem of the electrode assembly during the cycle and improving the performance of the electrode assembly. At the same time, the expansion of the electrode assembly can be restricted, thereby limiting the growth of the expansion force of the electrode assembly; in addition, in the second buffer state, the weak part can be destroyed, so that the compressibility of the buffer pad in the late stage of the cycle can be increased, and the space occupied by the buffer pad in the late stage of the cycle can be reduced, thereby effectively preventing the hard expansion of the electrode assembly, reducing the risk of a sharp increase in the expansion force of the battery cell in the late stage of the cycle, and improving the cycle service life of the battery cell.

[0012] According to an example of the present application, under a first preset pressure condition, the buffer pad is in the first buffer state, and the compressibility of the buffer pad is less than or equal to 10%; and / or, under a second preset pressure condition, the buffer pad is in the second buffer state, and the compressibility of the buffer pad is greater than or equal to 90%.

[0013] In this embodiment, by setting the compressibility of the buffer pad under the first preset pressure to be less than or equal to 10%, the compression amount of the buffer pad in the first buffer state will not be too large, so that the buffer pad can better support the electrode assembly and provide better buffering effect to the electrode assembly, so as to reduce the deformation of the pole piece, better improve the wrinkling phenomenon of the pole piece, further alleviate the lithium plating problem of the electrode assembly during the cycle, and improve the performance of the electrode assembly; by setting the compressibility of the buffer pad in the second buffer state to be greater than or equal to 90%, the buffer pad can have a larger compression amount in the second buffer state, reducing the space occupied by the buffer pad in the battery shell, reducing the impact of battery overvoltage on battery performance, and improving the service life of the battery.

[0014] According to an example of the present application, the first preset pressure is 0-0.4 MPa; and / or the second preset pressure is 0.8 MPa-1 MPa.

[0015] In this embodiment, by setting the first preset pressure to 0-0.4MPa and the compressibility of the buffer pad at the first preset pressure to be less than or equal to 10%, the compression amount of the buffer pad at the first preset pressure will not be too large, so that the buffer pad can better support the electrode assembly and provide better buffering effect to the electrode assembly, so as to reduce the deformation of the pole piece, better improve the wrinkling phenomenon of the pole piece, further alleviate the lithium plating problem of the electrode assembly during the cycle, and improve the performance of the electrode assembly; by setting the second preset pressure to 0.8MPa-1MPa and the compressibility of the buffer pad at the second preset pressure to be greater than or equal to 90%, the buffer pad can have a larger compression amount at the second preset pressure, reduce the space occupied by the buffer pad in the battery shell, reduce the impact of battery overvoltage on battery performance, and improve the service life of the battery.

[0016] According to an example of the present application, under a third preset pressure condition, the buffer pad is in the first buffer state, and the compressibility of the buffer pad is 40%-60%, and the third preset pressure is 0.4 MPa-0.8 MPa.

[0017] In this embodiment, by setting the compressibility of the buffer pad to 40%-60% under the third preset pressure, the buffer pad can not only meet the supporting effect on the electrode assembly, but also provide the required expansion space for the electrode assembly, thereby effectively absorbing the expansion force of the electrode assembly, improving the wrinkling phenomenon of the electrode sheet, and thus improving the cycle capacity of the electrode assembly.

[0018] According to an example of the present application, at least a portion of the periphery of the weak portion is connected to the main body portion, and a middle portion thereof protrudes away from the main body portion along the thickness direction of the main body portion.

[0019] This embodiment improves the compressibility of the buffer pad by arranging that at least part of the circumference of the weak part is connected to the main body and the middle position is protruded away from the main body along the thickness direction of the main body, so that the buffer pad can match the expansion of the electrode assembly and improve the cycle life of the electrode assembly.

[0020] According to an example of the present application, the periphery of the weak portion is sealed to the main body portion, and the weak portion and the main body portion cooperate to define a cavity.

[0021] In this embodiment, the periphery of the weak portion is sealed and connected to the main body portion, and a cavity is defined between the weak portion and the main body portion. This allows the buffer pad to meet the support requirements of the electrode assembly while also improving the compressibility of the buffer pad, so that the buffer pad matches the expansion of the electrode assembly in the early stage of the cycle, and can significantly reduce the occupied space in the battery case in the later stage of the cycle, thereby increasing the expansion space of the electrode assembly and improving the cycle service life of the electrode assembly.

[0022] According to an example of the present application, a receiving hole is formed on the main body, the weak portion is sealed to the periphery of the receiving hole, and the weak portion and the peripheral wall of the receiving hole cooperate to define the cavity.

[0023] This embodiment can further improve the compressibility of the main body by forming a receiving hole on the main body, and further improve the compressibility of the buffer pad in the later stage of the cycle, thereby further reducing the space occupied by the buffer pad in the later stage of the cycle, increasing the expansion space of the electrode assembly, and increasing the cycle service life of the electrode assembly.

[0024] According to an example of the present application, a filler is provided in the cavity, and in the second buffer state, the filler can be released from the cavity.

[0025] This embodiment provides a filler in the cavity, which can increase the supporting capacity of the buffer pad in the first buffer state. At the same time, in the second buffer state, the filler can release the cavity, thereby reducing the space occupied by the buffer pad and increasing the expandable space of the electrode assembly, thereby improving the reliability of the battery cell.

[0026] According to an example of the present application, the filler is at least one of a lithium supplement and a gas capture agent.

[0027] In this embodiment, by setting the filler as a lithium replenisher, the lithium lost during the cycle of the electrode assembly can be replenished, which helps to improve the cycle life of the electrode assembly and improve the performance of the battery; by setting the filler as a gas capture agent, the generation of gas inside the electrode assembly can be reduced, thereby improving the stability of the battery; by setting the filler as a lithium replenisher and a gas capture agent, the lithium lost during the cycle of the electrode assembly can be replenished, and the gas generated during the cycle of the electrode assembly can be reduced, thereby improving the stability and cycle life of the battery.

[0028] According to an example of the present application, the filler is at least one of cuprous oxide, cuprous sulfide, cuprous carboxylate, cuprous sulfate, activated carbon, graphene and aluminum oxide.

[0029] This embodiment can reduce the gas generated during the cycle of the electrode assembly by setting the filler to at least one of cuprous oxide, cuprous sulfide, cuprous carboxylate, cuprous sulfate, activated carbon, graphene and aluminum oxide, thereby improving the stability and cycle life of the battery.

[0030] According to an example of the present application, there are multiple weak portions, and the multiple weak portions are arranged at intervals on the surface of the main body.

[0031] This embodiment increases the contact area between the weak parts and the electrode assembly by arranging multiple weak parts at intervals on the surface of the main body, thereby dispersing the force and improving the force uniformity of the buffer pad, thereby improving the uniformity of the buffer pad's support for the electrode assembly and further improving the wrinkling of the electrode piece caused by the expansion of the electrode assembly.

[0032] According to an example of the present application, a plurality of the weak portions are arranged in a matrix on the surface of the main body.

[0033] This embodiment arranges multiple weak portions in a matrix pattern on the surface of the main body, so that the weak portions can be evenly arranged on the surface of the main body, thereby improving the uniformity of compression of the buffer pad's large buffer surface, improving the uniformity of the buffer pad's support for the electrode assembly, and further improving the wrinkling of the electrode piece caused by the expansion of the electrode assembly.

[0034] According to an example of the present application, in a projection plane perpendicular to the thickness direction of the main body, a ratio of a projection area of ​​the plurality of weak portions to a projection area of ​​the buffer pad is 20%-80%.

[0035] In this embodiment, by setting the ratio of the projected area of ​​multiple weak parts to the projected area of ​​the buffer pad to 20%-80%, the area of ​​the weak parts can be prevented from being too large, which is beneficial to improving the overall structural strength of the buffer pad body, improving its structural stability, and enhancing the supporting capacity of the buffer pad; it can also prevent the area of ​​the weak parts from being too small, thereby improving the compression capacity of the buffer pad, so that the buffer pad can provide sufficient expansion space in the later stage of the battery cycle, thereby improving the reliability and cycle life of the battery cell.

[0036] According to an example of the present application, in a projection plane perpendicular to the thickness direction of the main body, a ratio of a projection area of ​​the plurality of weak portions to a projection area of ​​the buffer pad is 40%-60%.

[0037] This embodiment sets the ratio of the projected area of ​​multiple weak parts to the projected area of ​​the buffer pad to 40%-60%, which can further improve the overall structural strength of the buffer pad body, improve its structural stability, and enhance the supporting capacity of the buffer pad; it can also further improve the compression capacity of the buffer pad, so that the buffer pad can provide sufficient expansion space in the later stage of the battery cycle, thereby improving the reliability and cycle life of the battery cell.

[0038] According to an example of the present application, the ratio of the distance between two adjacent weak portions to the maximum length dimension of the weak portion in the plane where the main body portion is located is 1 / 3-2.

[0039] This embodiment improves the structural strength and supporting effect of the buffer pad throughout the battery life cycle by setting the ratio of the spacing between two adjacent weak parts to the maximum length dimension of the weak part in the plane where the main body is located to 1 / 3-2; at the same time, it can also increase the expandable space of the electrode assembly in the later stage of the cycle, thereby increasing the cycle service life of the battery cell.

[0040] According to an example of the present application, the ratio of the distance between two adjacent weak portions to the maximum length dimension of the weak portion in the plane where the main body portion is located is 1-1.5.

[0041] This embodiment sets the ratio of the spacing between two adjacent weak parts to the maximum length dimension of the weak part in the plane where the main body is located to 1-1.5, which can further improve the structural strength and support effect of the buffer pad throughout the life cycle of the battery; at the same time, it can further increase the expandable space of the electrode assembly in the later stage of the cycle, thereby increasing the cycle service life of the battery cell.

[0042] According to an example of the present application, the weak portion is provided on both side surfaces of the main body in the thickness direction.

[0043] This embodiment provides weak portions on both side surfaces of the main body in the thickness direction, which can further reduce the thickness of the buffer pad in the later stage of the cycle, and further reduce the space occupied by the buffer pad in the later stage of the cycle, increase the expandable space of the electrode assembly, and thus improve the reliability of the battery cell.

[0044] According to an example of the present application, the main body is provided with a plurality of weak portions on both side surfaces of the thickness square, the plurality of weak portions on the surface of one side of the main body corresponds one to one with the plurality of weak portions on the surface of the other side of the main body, and the corresponding two weak portions are facing each other in the thickness direction of the main body.

[0045] In this embodiment, by arranging two corresponding weak parts facing each other in the thickness direction of the main body, the weak parts on the two side surfaces in the thickness direction of the main body can be subjected to the same force, and can rupture simultaneously after reaching a certain pressure, thereby greatly reducing the thickness of the buffer pad, thereby further reducing the space occupied by the buffer pad in the later stage of the cycle, increasing the expandable space of the electrode assembly, and thus improving the reliability and cycle life of the battery cell.

[0046] According to an example of the present application, the weak portion is a hollow structure, and the wall thickness of the weak portion is 5 μm-150 μm.

[0047] In this embodiment, the weak part is set to a hollow structure with a wall thickness of 5μm-150μm, so that the weak part can play a supporting role in the early stage of the electrode assembly cycle, and can be broken in time in the later stage of the electrode assembly cycle, thereby reducing the space occupied by the weak part after the rupture.

[0048] According to an example of the present application, the wall thickness of the weak portion is 20 μm-50 μm.

[0049] In this embodiment, by setting the wall thickness of the weak part to 20μm-50μm, the weak part will not be easily broken due to too small a thickness, nor will it be difficult to break due to too large a thickness, and the problem of large space occupation will be solved. In addition, the weak part can play a supporting role in the early stage of the electrode assembly cycle, and can be broken in time in the later stage of the electrode assembly cycle, thereby reducing the space occupied by the weak part after the break.

[0050] According to an example of the present application, the outer contour of the weak portion is in the shape of a cylinder, a semi-cylinder, a hemisphere, a semi-ellipsoid or a cuboid.

[0051] This embodiment reduces the manufacturing process of the weak portion by setting the outer contour of the weak portion to be cylindrical, semi-cylindrical, hemispherical, semi-ellipsoidal or rectangular, thereby increasing the production rate of the buffer pad and reducing the production cost of the buffer pad; in addition, the contact area between the weak portion and the electrode assembly can be increased, thereby improving the support effect of the buffer pad.

[0052] According to an example of the present application, the weak portion is in the shape of a hollow hemisphere, and the diameter of the weak portion is 1 mm-50 mm.

[0053] This embodiment sets the weak part to a hollow hemispherical shape with a diameter of 1mm-50mm, which can effectively prevent the problem of insufficient supporting capacity due to the weak part being too small. It can also effectively prevent the problem of the buffer pad occupying a large space inside the battery shell due to the weak part being too large, thereby causing the energy density of the battery to be damaged.

[0054] According to an example of the present application, the diameter of the weak portion is 5 mm-20 mm.

[0055] In this embodiment, by setting the diameter of the weak portion to 5 mm-20 mm, the weak portion can meet the support requirements for the electrode assembly and reduce the space occupied by the buffer pad inside the battery housing.

[0056] According to an example of the present application, the ratio of the height of the weak portion protruding from the main body to the maximum length dimension of the weak portion in the plane where the main body is located is 1.01-3.0.

[0057] In this embodiment, the ratio of the height of the weak portion protruding from the main body to the maximum length of the weak portion in the plane where the main body is located is set to 1.01-3.0, thereby controlling the thickness of the buffer pad so that the buffer pad can maintain the supporting force for the electrode assembly in the early stage of the battery cycle and can provide sufficient expansion space for the electrode assembly after the weak portion ruptures in the later stage of the cycle.

[0058] According to an example of the present application, the ratio between the height of the weak portion protruding from the main body portion and the maximum length dimension of the weak portion in the plane where the main body portion is located is 1.5-2.

[0059] In this embodiment, by setting the ratio of the height of the weak portion protruding from the main body to the maximum length dimension of the weak portion in the plane where the main body is located to 1.5-2, the buffer pad can maintain the support force for the electrode assembly in the early stage of the battery cycle, and can also provide sufficient expansion space for the electrode assembly after the weak portion ruptures in the later stage of the cycle.

[0060] According to an example of the present application, the buffer pad is a polyethylene piece, a polypropylene piece, a polyethylene terephthalate piece, an aerogel piece, a foam material piece or a silicone rubber piece.

[0061] In this embodiment, by configuring the buffer pad to be a polyethylene part, a polypropylene part, a polyethylene terephthalate part, an aerogel part, a foam material part and / or a silicone rubber part, the possibility of the buffer pad being corroded or crushed by the electrolyte can be reduced, the reliability of the buffer pad throughout the life cycle of the battery cell can be improved, and the service life of the buffer pad can be increased; at the same time, the production cost of the buffer pad can be reduced, and thus the production cost of the battery can be reduced.

[0062] According to an example of the present application, in the first buffering state, the thickness of the buffer pad is 0.5 mm-5 mm.

[0063] In this embodiment, by setting the buffer pad to a thickness of 0.5mm-5mm in the first buffer state, the buffer pad can support the electrode assembly in the early stage of the battery cycle, thereby improving the problem of wrinkling at the electrode interface, thereby alleviating the problem of lithium plating at the interface and improving the performance of the battery cell; at the same time, it can also reduce the space occupied by the buffer pad, thereby improving the energy density of the battery cell.

[0064] According to an example of the present application, in the first buffering state, the thickness of the buffer pad is 1 mm-3.5 mm.

[0065] In this embodiment, by setting the thickness of the buffer pad to 1mm-3.5mm in the first buffer state, the buffer pad can support the electrode assembly in the early stage of the battery cycle, and can further limit the space occupied by the buffer pad, thereby improving the problem of wrinkling at the electrode interface while not affecting the energy density of the battery cell.

[0066] According to the second aspect of the present application, the battery cell includes: a shell having a accommodating cavity; an electrode assembly, the electrode assembly being arranged in the accommodating cavity; and a buffer pad according to the first aspect of the present application, the buffer pad being arranged between the electrode assembly and the inner wall surface of the accommodating cavity, and / or the buffer pad being arranged between two adjacent electrode assemblies.

[0067] According to the battery cell of the present application, by setting the buffer pad of the first aspect mentioned above, and utilizing the main body and weak part included in the buffer pad, the buffer pad can have a better supporting effect on the electrode assembly in both the early and late stages of the battery cell cycle, and can reduce the deformation of the pole piece, thereby improving the wrinkling of the pole piece caused by the expansion of the electrode assembly, thereby alleviating the lithium plating problem of the electrode assembly during the cycle and improving the performance of the battery cell. At the same time, the expansion of the electrode assembly can be restricted, thereby limiting the growth of the expansion force of the electrode assembly; in addition, in the second buffer state, the weak part can be destroyed, so that the compressibility of the buffer pad in the late stage of the cycle can be increased, and the space occupied by the buffer pad in the late stage of the cycle can be reduced, thereby effectively preventing the hard expansion of the electrode assembly, reducing the risk of a sharp increase in the expansion force of the battery cell in the late stage of the cycle, and improving the cycle service life of the battery cell.

[0068] A battery according to a third aspect of the present application includes the battery cell according to the second aspect of the present application.

[0069] According to the battery of the present application, the battery cell according to the second aspect is provided, thereby improving the overall performance of the battery.

[0070] The electrical device according to the fourth aspect of the present application includes the battery according to the third aspect of the present application, and the battery is used to provide electrical energy.

[0071] According to the electric device of the present application, the battery according to the third aspect is provided, thereby improving the overall performance of the electric device.

[0072] 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

[0073] FIG1 is a schematic diagram of a vehicle according to an embodiment of the present application;

[0074] FIG2 is a schematic diagram of a battery according to an embodiment of the present application;

[0075] FIG3 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0076] FIG4 is a schematic diagram of a cushion according to an embodiment of the present application;

[0077] FIG5 is a cross-sectional view of line AA shown in FIG4;

[0078] FIG6 is a schematic diagram of a cushion according to an embodiment of the present application from another angle;

[0079] FIG7 is a schematic diagram of a cushion according to another embodiment of the present application;

[0080] FIG8 is a schematic diagram of a cushion according to another embodiment of the present application;

[0081] FIG9 is a cross-sectional view of line BB shown in FIG8;

[0082] FIG10 is a schematic diagram of a cushion according to another embodiment of the present application from another angle;

[0083] FIG11 is a cross-sectional view of a battery cell according to an embodiment of the present application;

[0084] FIG12 is a cross-sectional view of a battery cell according to an embodiment of the present application from another angle;

[0085] FIG13 is a cross-sectional view of a battery cell according to another embodiment of the present application;

[0086] FIG14 is a cross-sectional view of a battery cell according to another embodiment of the present application from another angle;

[0087] FIG15 is a cross-sectional view of a battery cell according to another embodiment of the present application;

[0088] FIG16 is a cross-sectional view of a battery cell according to yet another embodiment of the present application from another angle.

[0089] Reference numerals: vehicle 1; battery 1000; battery cell 100; housing 10; accommodating chamber 101; electrode assembly 20; cushion 30; body 31; weak portion 32; end cap 40; insulating film 50; adapter 60; housing 200; controller 2000; motor 3000. DETAILED DESCRIPTION

[0090] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0091] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein 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 figure descriptions are intended to cover non-exclusive inclusions.

[0092] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0093] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present 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 herein may be combined with other embodiments.

[0094] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0095] In the description of the embodiments of the present application, the term "plurality" refers to more than two (including two).

[0096] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0097] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0098] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0099] During the cycling of the electrode assembly, it is prone to expansion and deformation. When the electrode assembly expands, the electrode sheets are prone to wrinkling, causing lithium deposition during the cycling process. In related technologies, buffer pads are often placed in batteries. However, the buffer pads are poorly designed, occupying a large space and exhibiting poor compressibility. This can lead to a sharp increase in expansion force in the electrode assembly during the later stages of cycling, which in turn affects the cycle life of the electrode assembly.

[0100] Based on the above considerations, in order to solve the problem that the expansion force of the battery cell increases sharply in the later stage of recycling and the cycle service life is reduced, a buffer pad is designed. The buffer pad includes a main body and a weak part, and the buffer pad includes a first buffer state and a second buffer state. In the first buffer state, the weak part protrudes from the surface of the main body, and the buffer pad supports the electrode assembly through the weak part. In the second buffer state, the weak part is destroyed, and the buffer pad supports the electrode assembly through the main body. In this way, the buffer pad can have a good supporting effect on the electrode assembly in both the early and late stages of the battery cycle, so that the buffer pad can always limit the expansion of the electrode assembly throughout the life cycle of the battery. At the same time, it can also reduce the space occupied by the buffer pad in the later stage of the cycle, thereby reducing the risk of a sharp increase in the expansion force in the later stage of the battery cycle and improving the cycle service life of the battery cell.

[0101] When the battery is recycled, since the buffer pad includes a main body and a weak part, and the weak part protrudes from the surface of the main body, after the battery has been circulated for a period of time, the weak part can be damaged by the expansion force of the electrode assembly. Therefore, the space occupied by the buffer pad can be greatly reduced in the later stage of the battery cycle, thereby increasing the expansion space of the electrode assembly, reducing the risk of a sharp increase in the expansion force in the later stage of the battery cycle, and improving the cycle service life of the battery cell.

[0102] The buffer member disclosed in the embodiments of the present application can be applied to battery cells, which can be used in electrical devices that use batteries as power sources, or various energy storage systems that use batteries as energy storage elements. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, and the like. Electric toys may include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric airplane toys, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, among others.

[0103] For the convenience of description, the following embodiments are described by taking a vehicle 1 as an example of an electrical device according to an embodiment of the present application.

[0104] Referring to Figure 1, Figure 1 is a schematic diagram of a vehicle 1 provided in some embodiments of the present application. The vehicle 1 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 1000 is provided inside the vehicle 1, and the battery 1000 can be provided at the bottom, head or tail of the vehicle 1. The battery 1000 can be used to power the vehicle 1. For example, the battery 1000 can serve as an operating power source for the vehicle 1. The vehicle 1 can also include a controller 2000 and a motor 3000. The controller 2000 is used to control the battery 1000 to power the motor 3000, for example, for starting, navigating and operating power requirements of the vehicle 1 during driving.

[0105] In some embodiments of the present application, the battery 1000 can serve not only as an operating power source for the vehicle 1 , but also as a driving power source for the vehicle 1 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1 .

[0106] In this application, the battery 1000 refers to a single physical module that includes one or more battery cells 100 to provide higher voltage and capacity. For example, the battery 1000 mentioned in this application may include a battery module or a battery pack. Some batteries 1000 may include a box 200 for encapsulating one or more battery cells 100 or multiple battery modules. The box 200 can effectively prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells 100. Of course, some batteries 1000 may not include the above-mentioned box 200 and are directly installed in the battery 1000 installation compartment of the electrical device.

[0107] 2 is a schematic diagram of a battery 1000 according to some embodiments of the present invention. The battery 1000 includes a housing 200 and a battery cell 100. The housing 200 has a cavity, and the battery cell 100 is accommodated in the cavity of the housing 200.

[0108] In the battery 1000, there may be multiple battery cells 100, and the multiple battery cells 100 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. The multiple battery cells 100 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 100 may be housed within the housing 200. Of course, the battery 1000 may also be a battery module formed by first connecting multiple battery cells 100 in series, in parallel, or in a hybrid connection, and then the multiple battery modules are further connected in series, in parallel, or in a hybrid connection to form an entire battery cell, and then housed within the housing 200. The battery 1000 may also include other structures, for example, the battery 1000 may also include a busbar component for electrically connecting the multiple battery cells 100.

[0109] Each battery cell 100 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 100 may be cylindrical, flat, rectangular, or in other shapes.

[0110] Referring to Figure 3, Figure 3 is an exploded view of a battery cell 100 according to some embodiments of the present application. As shown in Figure 3, the battery cell 100 according to this embodiment may include a housing 10, an end cap 40, an electrode assembly 20, an electrolyte, and a buffer pad 30. The housing 10 has a housing 101 formed therein for accommodating the electrode assembly 20, the electrolyte, and the buffer pad 30.

[0111] The shell 10 and the end cap 40 can be independent components, and an opening can be provided on the shell 10. The internal environment of the battery 1000 is formed by covering the opening with the end cap 40. Without limitation, the end cap 40 and the shell 10 can also be integrated. Specifically, the end cap 40 and the shell 10 can form a common connection surface before other components are put into the shell. When the interior of the shell 10 needs to be encapsulated, the end cap 40 is covered with the shell 10. The shell 10 can be of various shapes and sizes, such as cylindrical, hexagonal, etc. Specifically, the shape of the shell 10 can be determined according to the specific shape and size of the electrode assembly 20. The material of the shell 10 can be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. According to an example of the present application, an insulating film 50 is also provided on the inner side of the shell 10. The insulating film 50 is wrapped around the outer surface of the electrode assembly 20 to isolate the electrode assembly 20 from the shell 10 to reduce the risk of short circuit.

[0112] The end cap 40 refers to a component that covers the opening of the shell 10 to isolate the internal environment of the battery 1000 from the external environment. Without limitation, the shape of the end cap 40 can be adapted to the shape of the shell 10 to match the shell 10. Optionally, the end cap 40 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 40 is not easily deformed when squeezed or collided, so that the battery 1000 can have a higher structural strength and improved safety performance. The material of the end cap 40 can also be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. According to an example of the present application, an insulating member can also be provided on the inner side of the end cap 40, and the insulating member can be used to isolate the electrical connection components in the shell 10 from the end cap 40 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc. According to an example of the present application, the battery cell 100 also includes a transition piece 60, which is connected to the tab for current transmission.

[0113] The electrode assembly 20 consists of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell 100 primarily relies on the movement of metal ions between the positive and negative electrode sheets to operate. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The positive current collector not coated with the positive active material layer protrudes from the positive current collector coated with the positive active material layer, and the positive current collector not coated with the positive active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc.

[0114] The negative electrode sheet consists of a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The negative current collector uncoated with the negative active material layer protrudes from the negative current collector coated with the negative active material layer. The negative current collector uncoated with the negative active material layer serves as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon, silicon, or other materials. To ensure that high currents can pass without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together.

[0115] The material of the separator can be PP (polypropylene) or PE (polyethylene). The electrode assembly 20 of the embodiment of the present application is a wound structure. In addition, the electrode assembly 20 can be a wound structure or a laminated structure.

[0116] The following describes a buffer pad 30 according to an embodiment of the first aspect of the present application with reference to Figures 4 to 16. Figure 4 is a schematic diagram of the buffer pad 30 according to an embodiment of the present application. Figure 5 is a cross-sectional view taken along line AA shown in Figure 4. Figure 6 is a schematic diagram of the buffer pad 30 according to an embodiment of the present application from another angle. Figure 7 is a schematic diagram of the buffer pad 30 according to another embodiment of the present application. Figure 8 is a schematic diagram of the buffer pad 30 according to yet another embodiment of the present application. Figure 9 is a cross-sectional view taken along line BB shown in Figure 8. Figure 10 is a schematic diagram of the buffer pad 30 according to yet another embodiment of the present application from yet another angle. Figure 11 is a cross-sectional view of a battery cell 100 according to an embodiment of the present application. Figure 12 is a cross-sectional view of a battery cell 100 according to an embodiment of the present application from yet another angle. Figure 13 is a cross-sectional view of a battery cell 100 according to yet another embodiment of the present application. Figure 14 is a cross-sectional view of a battery cell 100 according to yet another embodiment of the present application from yet another angle. Figure 15 is a cross-sectional view of a battery cell 100 according to yet another embodiment of the present application. Figure 16 is a cross-sectional view of a battery cell 100 according to yet another embodiment of the present application from yet another angle.

[0117] As shown in Figure 4, an embodiment of the present application proposes a buffer pad 30, which is arranged in the shell 10 of the battery cell 100. The buffer pad 30 includes: a main body 31 and a weak portion 32. The weak portion 32 is arranged in the main body 31 and at least partially protrudes from the surface of the main body 31. The buffer pad 30 has a first buffer state and a second buffer state. In the first buffer state, the weak portion 32 protrudes from the surface of the main body 31, and the buffer pad 30 supports the electrode assembly 20 through the weak portion 32. In the second buffer state, the weak portion 32 is destroyed, and the buffer pad 30 supports the electrode assembly 20 through the main body 31.

[0118] Among them, the buffer pad 30 is arranged in the shell 10 of the battery cell 100. The buffer pad 30 can support the electrode assembly 20. At the same time, the buffer pad 30 has a certain compressibility. The buffer pad 30 can be deformed under the action of external force, thereby effectively preventing the buffer pad 30 from squeezing the electrode assembly 20, thereby improving the reliability of the electrode assembly 20.

[0119] Specifically, the weak portion 32 is provided on the main body portion 31 and at least partially protrudes from the surface of the main body portion 31. That is, the weak portion 32 can partially protrude from the surface of the main body portion 31 or completely protrude from the surface of the main body portion 31, wherein the main body portion 31 provides support and installation space for the weak portion 32.

[0120] The first buffering state of the buffer pad 30 can be considered to be in the early stage of the cycle of the battery cell 100, when the expansion force of the electrode assembly 20 is small, the buffer pad 30 is initially compressed, and the weak portion 32 is not damaged. The buffer pad 30 supports the electrode assembly 20 through the weak portion 32, providing support for the electrode assembly 20, which can make the positive and negative electrodes fit tightly with the diaphragm, which is conducive to reducing the problem of wrinkling on the electrode interface.

[0121] The second buffering state of the buffer pad 30 can be considered to be in the late stage of the cycle of the battery cell 100, when the expansion force of the electrode assembly 20 is large, the thickness of the electrode assembly 20 increases, the weak part 32 is destroyed, the thickness of the buffer pad 30 is reduced, and the internal space of the battery 1000 becomes larger, providing the required space for the expansion of the electrode assembly 20. At the same time, the buffer pad 30 supports the electrode assembly 20 through the main body 31, so that the positive and negative electrodes can fit tightly with the diaphragm, thereby reducing the problem of wrinkling at the electrode interface.

[0122] According to the buffer pad 30 of the present application, by setting the main body 31 and the weak part 32, the buffer pad 30 can have a good supporting effect on the electrode assembly 20 both in the early stage and the late stage of the cycle of the battery cell 100, and can reduce the deformation of the electrode sheet, thereby improving the wrinkling of the electrode sheet caused by the expansion of the electrode assembly 20, thereby alleviating the lithium plating problem of the electrode assembly 20 during the cycle and improving the performance of the battery cell 100. At the same time, the expansion of the electrode assembly 20 can be restricted, thereby limiting the growth of the expansion force of the electrode assembly 20; in addition, in the second buffer state, the weak part 32 can be destroyed, so that the compressibility of the buffer pad 30 in the late stage of the cycle can be increased, and the space occupied by the buffer pad 30 in the late stage of the cycle can be reduced, thereby effectively preventing the hard expansion of the electrode assembly 20, reducing the risk of a sharp increase in the expansion force of the battery cell 100 in the late stage of the cycle, and improving the cycle service life of the battery cell 100.

[0123] According to an example of the present application, under a first preset pressure condition, the buffer pad 30 is in a first buffering state, and the compressibility of the buffer pad 30 is less than or equal to 10%; and / or, under a second preset pressure condition, the buffer pad 30 is in a second buffering state, and the compressibility of the buffer pad 30 is greater than or equal to 90%.

[0124] The compressibility of the cushion 30 refers to the percentage of the reduced volume of the cushion 30 to the volume of the cushion 30 in its natural state.

[0125] The first preset pressure and the second preset pressure may be preset values ​​set according to the expansion force of the electrode assembly 20 and the gas pressure inside the battery case 10 .

[0126] In this embodiment, by setting the compressibility of the buffer pad 30 under the first preset pressure to be less than or equal to 10%, the compression amount of the buffer pad 30 in the first buffer state will not be too large, so that the buffer pad 30 can better support the electrode assembly 20, provide better buffering effect for the electrode assembly 20, reduce pole piece deformation, better improve pole piece wrinkling, further alleviate the lithium plating problem of the electrode assembly 20 during the cycle, and improve the performance of the electrode assembly 20; by setting the compressibility of the buffer pad 30 in the second buffer state to be greater than or equal to 90%, the buffer pad 30 can have a larger compression amount in the second buffer state, reduce the space occupied by the buffer pad 30 in the battery shell 10, reduce the impact of overvoltage of the battery 1000 on the performance of the battery 1000, and improve the service life of the battery 1000.

[0127] According to an example of the present application, the first preset pressure is 0-0.4 MPa; and / or the second preset pressure is 0.8 MPa-1 MPa.

[0128] The first preset pressure and the second preset pressure may be preset values ​​set according to the expansion force of the electrode assembly 20 and the gas pressure inside the battery case 10. The first preset pressure may be considered as the pressure at the beginning of the cycle of the battery cell 100, and the second preset pressure may be considered as the pressure at the end of the cycle of the battery cell 100.

[0129] For example, the first preset pressure may be 0.1 MPa, 0.2 MPa, 0.3 MPa or 0.4 MPa; the second preset pressure may be 0.8 MPa, 0.9 MPa or 1.0 MPa.

[0130] In this embodiment, by setting the first preset pressure to 0-0.4MPa and the compressibility of the buffer pad 30 at the first preset pressure to be less than or equal to 10%, the compression amount of the buffer pad 30 at the first preset pressure will not be too large, so that the buffer pad 30 can better support the electrode assembly 20, provide better buffering effect to the electrode assembly 20, reduce pole piece deformation, better improve pole piece wrinkling, further alleviate the lithium plating problem of the electrode assembly 20 during the cycle, and improve the performance of the electrode assembly 20; by setting the second preset pressure to 0.8MPa-1MPa and the compressibility of the buffer pad 30 at the second preset pressure to be greater than or equal to 90%, the buffer pad 30 can have a larger compression amount at the second preset pressure, reduce the space occupied by the buffer pad 30 in the battery shell 10, reduce the impact of overpressure of the battery 1000 on the performance of the battery 1000, and improve the service life of the battery 1000.

[0131] According to an example of the present application, under the third preset pressure condition, the buffer pad 30 is in the first buffer state, and the compressibility of the buffer pad 30 is 40%-60%, and the third preset pressure is 0.4 MPa-0.8 MPa.

[0132] Among them, under the third preset pressure condition, the electrode assembly 20 can be considered to be in the middle of the cycle. At this time, the expansion force of the electrode assembly 20 increases, and some gas is also generated inside the battery cell 100. The internal pressure increases compared to the initial stage of the cycle. The electrode assembly 20 squeezes the buffer pad 30, and the buffer pad 30 provides expansion space for the electrode assembly 20, and the weak part 32 is not broken.

[0133] For example, the third preset pressure may be 0.4 MPa, 0.5 MPa, 0.6 MPa, or 0.7 MPa; and the compressibility of the buffer pad 30 may be 40%, 50%, or 60%.

[0134] In this embodiment, by setting the compressibility of the buffer pad 30 to 40%-60% under the third preset pressure, the buffer pad 30 can not only meet the supporting effect on the electrode assembly 20, but also provide the required expansion space for the electrode assembly 20, thereby effectively absorbing the expansion force of the electrode assembly 20, improving the wrinkling phenomenon of the electrode sheet, and thus improving the cycle capacity of the electrode assembly 20.

[0135] According to an example of the present application, as shown in FIG4 , at least part of the circumference of the weak portion 32 is connected to the main body 31 and the middle portion protrudes away from the main body 31 along the thickness direction of the main body 31 (for example, the direction of e2 shown in FIG4 ).

[0136] That is, the weak portion 32 may be partially connected to the main body 31 along its periphery, or may be connected to the main body 31 along its entire periphery. The middle portion of the weak portion 32 protrudes away from the main body 31 along the thickness direction of the main body 31 and contacts the large surface of the electrode assembly 20 to support the electrode assembly 20. The middle portion of the weak portion 32 is the position where the weak portion 32 protrudes the farthest from the main body 31.

[0137] In this embodiment, the compressibility of the buffer pad 30 can be improved by arranging that at least part of the circumference of the weak portion 32 is connected to the main body portion 31 and the middle position is raised away from the main body portion 31 along the thickness direction of the main body portion 31, so that the buffer pad 30 can match the expansion of the electrode assembly 20 and improve the cycle service life of the electrode assembly 20.

[0138] According to an example of the present application, as shown in FIG4 , the periphery of the weak portion 32 is sealed with the main body portion 31 , and the weak portion 32 and the main body portion 31 cooperate to define a cavity.

[0139] Specifically, in the first buffer state, since the periphery of the weak portion 32 is sealed and connected to the main body 31, the connection surface between the weak portion 32 and the main body 31 can be larger and the connection stability can be higher, thereby improving the supporting effect of the buffer pad 30 on the electrode assembly 20; at the same time, the weak portion 32 and the main body 31 cooperate to define a cavity, and the cavity deformation space is large, thereby improving the compressibility of the buffer pad 30, so that the buffer pad 30 can match the expansion of the electrode assembly 20 and improve the cycle service life of the electrode assembly 20.

[0140] In the second buffer state, the expansion force of the electrode assembly 20 increases, the weak area is destroyed, and the cavity ruptures, which can greatly reduce the thickness of the buffer pad 30, thereby effectively reducing the space occupied by the buffer pad 30 in the later stage of the cycle, and thus effectively ensuring the expansion space of the electrode assembly 20, thereby reducing the impact of overvoltage of the battery 1000 on the performance of the battery 1000 and improving the service life of the battery 1000.

[0141] In this embodiment, the periphery of the weak portion 32 is sealedly connected to the main body 31, and a cavity is defined between the weak portion 32 and the main body 31. This can enable the buffer pad 30 to meet the support requirements of the electrode assembly 20 while also improving the compressibility of the buffer pad 30, so that the buffer pad 30 matches the expansion of the electrode assembly 20 in the early stage of the cycle, and can significantly reduce the occupied space in the battery case 10 in the later stage of the cycle, thereby increasing the expansion space of the electrode assembly 20 and improving the cycle service life of the electrode assembly 20.

[0142] According to an example of the present application, a receiving hole is formed on the main body 31 , the weak portion 32 is sealed and connected to the periphery of the receiving hole, and the weak portion 32 and the peripheral wall of the receiving hole cooperate to define a cavity.

[0143] This embodiment forms a receiving hole on the main body 31, which can further improve the compressibility of the main body 31, and further improve the compressibility of the buffer pad 30 in the later stage of the cycle, thereby further reducing the space occupied by the buffer pad 30 in the later stage of the cycle, increasing the expansion space of the electrode assembly 20, and improving the cycle service life of the electrode assembly 20.

[0144] According to an example of the present application, a filler is provided in the cavity, and in the second buffer state, the filler can be released from the cavity.

[0145] In the second buffer state, the battery cell 100 is in the late stage of the cycle, more gas is generated inside the battery cell 100, and the expansion force of the electrode assembly 20 becomes larger. At this time, the weak portion 32 is destroyed to form a release hole, and the filler can be released from the cavity through the release hole, thereby reducing the space occupied by the buffer pad 30.

[0146] Optionally, the filler is a slow-release substance that can be used to improve the performance of the electrode assembly 20. Thus, in the second buffer state, the filler releases the buffer pad 30, which can improve the performance of the electrode assembly 20 and increase the stability and cycle life of the battery cell 100.

[0147] In this embodiment, by providing a filler in the cavity, the supporting capacity of the buffer pad 30 can be increased in the first buffer state. At the same time, in the second buffer state, the filler can release the cavity, thereby reducing the space occupied by the buffer pad 30 and increasing the expandable space of the electrode assembly 20, thereby improving the reliability of the battery cell 100.

[0148] According to an example of the present application, the filler is at least one of a lithium supplement and a gas capture agent.

[0149] The filler may be a lithium supplement agent, a gas capture agent, or both a lithium supplement agent and a gas capture agent.

[0150] When the filler is a lithium supplement, the buffer pad 30 is arranged inside the electrode assembly 20. The lithium supplement can replenish the lithium lost during the cycle of the electrode assembly 20, which helps to improve the cycle life of the electrode assembly 20 and improve the performance of the battery cell 100.

[0151] When the filler is a gas capture agent, the buffer pad 30 can be disposed between the electrode assembly 20 and the shell 10 . The gas capture agent can reduce the generation of gas inside the electrode assembly 20 , thereby improving the stability of the battery cell 100 .

[0152] When the filler is a lithium replenisher and a gas capture agent, the buffer pad 30 can be set between two adjacent electrode assemblies 20, or it can be set between two adjacent electrode assemblies 20 and between the electrode assembly 20 and the shell 10. At this time, the filler can not only replenish the lithium lost during the cycle of the electrode assembly 20, but also reduce the gas generated during the cycle of the electrode assembly 20, thereby improving the stability and cycle life of the battery cell 100.

[0153] In this embodiment, by setting the filler as a lithium replenisher, the lithium lost during the cycle of the electrode assembly 20 can be replenished, which helps to improve the cycle life of the electrode assembly 20 and improve the performance of the battery cell 100; by setting the filler as a gas capture agent, the generation of gas inside the electrode assembly 20 can be reduced, thereby improving the stability of the battery 1000; by setting the filler as a lithium replenisher and a gas capture agent, the lithium lost during the cycle of the electrode assembly 20 can be replenished, and the gas generated during the cycle of the electrode assembly 20 can be reduced, thereby improving the stability and cycle life of the battery cell 100.

[0154] According to an example of the present application, the filler is at least one of cuprous oxide, cuprous sulfide, cuprous carboxylate, cuprous sulfate, activated carbon, graphene, and aluminum oxide.

[0155] That is, the filler can be one of the above substances or a mixture of the above substances, wherein the above substances have an adsorption effect on the gas generated during the cycle of the battery cell 100 .

[0156] In this embodiment, by setting the filler to at least one of cuprous oxide, cuprous sulfide, cuprous carboxylate, cuprous sulfate, activated carbon, graphene and aluminum oxide, the gas generated during the cycle of the electrode assembly 20 can be reduced, thereby improving the stability and cycle life of the battery cell 100.

[0157] According to an example of the present application, as shown in FIG. 4 and FIG. 5 , there are multiple weak portions 32 , and the multiple weak portions 32 are arranged at intervals on the surface of the main body 31 .

[0158] For example, the number of the weak portions 32 may be two, three or more. The multiple weak portions 32 are arranged at intervals on the surface of the body, and the multiple weak portions 32 may be arranged at intervals on one side of the body 31 or on both sides of the body 31.

[0159] In this embodiment, by arranging multiple weak portions 32 at intervals on the surface of the main body, the contact area between the weak portions 32 and the electrode assembly 20 can be increased, thereby dispersing the force and improving the force uniformity of the buffer pad 30, thereby improving the uniformity of the support of the buffer pad 30 for the electrode assembly 20 and further improving the wrinkling phenomenon of the electrode piece caused by the expansion of the electrode assembly 20.

[0160] According to an example of the present application, as shown in FIG6 , a plurality of weak portions 32 are arranged in a matrix on the surface of the main body portion 31 .

[0161] For example, a matrix arrangement may mean that a plurality of weak portions 32 are formed in multiple rows in the length direction of the main body 31 (for example, in the direction of e3 shown in FIG6 ), and in multiple columns in the width direction (for example, in the direction of e1 shown in FIG6 ), and the weak portions 32 in each row and column are evenly arranged.

[0162] In this embodiment, multiple weak portions 32 are arranged in a matrix on the surface of the main body 31, so that the weak portions 32 can be evenly arranged on the surface of the main body 31, thereby improving the uniformity of compression of the large buffering surface of the buffer pad 30, improving the uniformity of support of the buffer pad 30 for the electrode assembly 20, and further improving the wrinkling phenomenon of the electrode piece caused by the expansion of the electrode assembly 20.

[0163] According to an example of the present application, as shown in Figure 6, in a projection plane perpendicular to the thickness direction of the main body 31 (for example, the direction of e2 shown in Figure 5), the ratio of the projection area of ​​multiple weak portions 32 to the projection area of ​​the buffer pad 30 is 20%-80%.

[0164] For example, the ratio of the projected area of ​​the plurality of weak portions 32 to the projected area of ​​the cushioning pad 30 may be 20%, 30%, 40%, 50%, 60%, 70% or 80%.

[0165] In this embodiment, by setting the ratio of the projected area of ​​multiple weak portions 32 to the projected area of ​​the buffer pad 30 to be 20%-80%, the area of ​​the weak portion 32 can be prevented from being too large, which is beneficial to improving the overall structural strength of the buffer pad 30 body, improving its structural stability, and enhancing the supporting capacity of the buffer pad 30; the area of ​​the weak portion 32 can also be prevented from being too small, thereby improving the compression capacity of the buffer pad 30, so that the buffer pad 30 can provide sufficient expansion space in the later stage of the battery cell 100 cycle, thereby improving the reliability and cycle life of the battery cell 100.

[0166] According to an example of the present application, as shown in Figure 6, in a projection plane perpendicular to the thickness direction of the main body 31 (for example, the direction of e2 shown in Figure 5), the ratio of the projection area of ​​multiple weak portions 32 to the projection area of ​​the buffer pad 30 is 40%-60%.

[0167] For example, the ratio of the projected area of ​​the plurality of weak portions 32 to the projected area of ​​the cushioning pad 30 may be 40%, 45%, 50%, 55% or 60%.

[0168] In this embodiment, by setting the ratio of the projected area of ​​multiple weak portions 32 to the projected area of ​​the buffer pad 30 to be 40%-60%, the ratio of the projected area of ​​multiple weak portions 32 to the projected area of ​​the buffer pad 30 is 40%-60%, which can further improve the overall structural strength of the buffer pad 30 body, improve its structural stability, and enhance the supporting capacity of the buffer pad 30; it can also further improve the compression capacity of the buffer pad 30, so that the buffer pad 30 can provide sufficient expansion space in the later stage of the battery cell 100 cycle, thereby improving the reliability and cycle life of the battery cell 100.

[0169] According to an example of the present application, as shown in FIG7 , the ratio of the distance between two adjacent weak portions 32 to the maximum length of the weak portion 32 in the plane where the main body portion 31 is located is 1 / 3-2.

[0170] Among them, the gap between the two connected weak parts 32 is related to the area occupied by the weak parts 32 in the main body 31. When the gap between the two adjacent weak parts 32 is too large, the area occupied by the weak parts 32 in the main body 31 is reduced, which may affect the supporting effect of the buffer pad 30 in the early stage of the cycle of the electrode assembly 20 and the space occupancy of the electrode assembly 20 in the later stage of the cycle; when the gap between the two adjacent weak parts 32 is too small, the area occupied by the weak parts 32 in the main body 31 increases, which may affect the structural strength of the buffer pad 30. At the same time, in the later stage of the cycle of the battery cell 100, it may also affect the supporting effect of the buffer pad 30 on the electrode assembly 20.

[0171] For example, the ratio of the interval h1 between two adjacent weak portions 32 to the maximum length h of the weak portion 32 in the plane where the main body portion 31 is located may be 1 / 3, 2 / 3, 1, 1.5 or 2.

[0172] This embodiment improves the structural strength and supporting effect of the buffer pad 30 throughout the life cycle of the battery 1000 by setting the ratio of the spacing between two adjacent weak portions 32 to the maximum length dimension of the weak portion 32 in the plane where the main body portion 31 is located to 1 / 3-2; at the same time, it can also ensure the expandable space of the electrode assembly 20 in the later stage of the cycle, thereby improving the cycle service life of the battery cell 100.

[0173] According to an example of the present application, as shown in FIG7 , the ratio of the distance between two adjacent weak portions 32 to the maximum length of the weak portion 32 in the plane where the main body portion 31 is located is 1-1.5.

[0174] For example, the ratio of the interval h1 between two adjacent weak portions 32 to the maximum length h of the weak portion 32 in the plane where the main body portion 31 is located may be 1, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0175] This embodiment sets the ratio of the spacing between two adjacent weak portions 32 to the maximum length dimension of the weak portion 32 in the plane where the main body portion 31 is located to 1-1.5, which can further improve the structural strength and support effect of the buffer pad 30 throughout the life cycle of the battery cell 100; at the same time, it can further increase the expandable space of the electrode assembly 20 in the later stage of the cycle, thereby improving the cycle service life of the battery cell 100.

[0176] According to an example of the present application, as shown in FIG8 , both side surfaces of the main body 31 in the thickness direction (eg, the direction of e2 shown in FIG8 ) are provided with weak portions 32 .

[0177] In this embodiment, by providing weak portions 32 on both side surfaces of the main body 31 in the thickness direction, the thickness of the buffer pad 30 in the later stage of the cycle can be further reduced, thereby further reducing the space occupied by the buffer pad 30 in the later stage of the cycle, increasing the expandable space of the electrode assembly 20, and thus improving the reliability and cycle life of the battery cell 100.

[0178] According to an example of the present application, as shown in Figure 8, a plurality of weak portions 32 are provided on both side surfaces of the main body 31 on the thickness square, and the plurality of weak portions 32 on the surface of one side of the main body 31 correspond one-to-one to the plurality of weak portions 32 on the surface of the other side of the main body 31, and the corresponding two weak portions 32 are facing each other in the thickness direction of the main body 31 (for example, the direction of e2 shown in Figure 8).

[0179] In this embodiment, by arranging two corresponding weak portions 32 facing each other in the thickness direction of the main body 31, the weak portions 32 on the two side surfaces in the thickness direction of the main body 31 can be subjected to the same force, and can rupture simultaneously after reaching a certain pressure, thereby significantly reducing the thickness of the buffer pad 30, thereby further reducing the space occupied by the buffer pad 30 in the later stage of the cycle, increasing the expandable space of the electrode assembly 20, and thus improving the reliability and cycle life of the battery cell 100.

[0180] According to an example of the present application, the weak portion 32 is a hollow structure, and the wall thickness of the weak portion 32 is 5 μm-150 μm.

[0181] The hollow structure refers to a cavity formed inside the weak portion 32 .

[0182] For example, the wall thickness of the weak portion 32 may be 5 μm, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 130 μm, 140 μm, or 150 μm.

[0183] In this embodiment, the weak portion 32 is set to a hollow structure, and the wall thickness of the weak portion 32 is 5μm-150μm, so that the weak portion 32 can play a supporting role in the early stage of the cycle of the electrode assembly 20, and can be broken in time in the later stage of the cycle of the electrode assembly 20, thereby reducing the space occupied by the weak portion 32 after the rupture.

[0184] According to an example of the present application, the wall thickness of the weak portion 32 is 20 μm-50 μm.

[0185] For example, the wall thickness of the weak portion 32 may be 20 μm, 30 μm, 40 μm or 50 μm.

[0186] In this embodiment, by setting the wall thickness of the weak portion 32 to 20μm-50μm, the weak portion 32 will not be easily broken due to a too small thickness, nor will it be difficult to break due to a too large thickness, and the problem of large space occupation will be solved. In addition, the weak portion 32 can play a supporting role in the early stage of the cycle of the electrode assembly 20, and can be broken in time in the later stage of the cycle of the electrode assembly 20, thereby reducing the space occupied by the weak portion 32 after the break.

[0187] According to an example of the present application, as shown in FIG8 , the outer contour of the weak portion 32 is in the shape of a cylinder, a semi-cylinder, a hemisphere, a semi-ellipsoid or a cuboid.

[0188] The outer contour of the weak portion 32 can be any one of a cylinder, a semi-cylinder, a hemisphere, a semi-ellipsoid or a cuboid. The above shapes are relatively simple, and the manufacturing process is simple, and the contact surface with the electrode assembly 20 is large.

[0189] In this embodiment, by setting the outer contour of the weak portion 32 to be cylindrical, semi-cylindrical, hemispherical, semi-ellipsoidal or rectangular, the manufacturing process of the weak portion 32 can be reduced, thereby increasing the production rate of the buffer pad 30 and reducing the production cost of the buffer pad 30; in addition, the contact area between the weak portion 32 and the electrode assembly 20 can be increased, thereby improving the support effect of the buffer pad 30.

[0190] According to an example of the present application, as shown in FIG9 , the weak portion 32 is in the shape of a hollow hemisphere, and the diameter of the weak portion 32 is 1 mm-50 mm.

[0191] For example, the diameter of the weakened portion 32 may be 1 mm, 2 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm.

[0192] This embodiment sets the weak portion 32 to a hollow hemispherical shape, and the diameter of the weak portion 32 is 1mm-50mm. This can effectively prevent the problem of insufficient supporting capacity due to the weak portion 32 being too small. It can also effectively prevent the problem of the buffer pad 30 occupying a large space inside the battery shell 10 due to the weak portion 32 being too large, thereby causing the energy density of the battery 1000 to be damaged.

[0193] According to an example of the present application, as shown in FIG9 , the diameter of the weak portion 32 is 5 mm to 20 mm.

[0194] For example, the diameter of the weakened portion 32 may be 5 mm, 10 mm, 15 mm, or 20 mm.

[0195] In this embodiment, by setting the diameter of the weak portion 32 to 5 mm-20 mm, the weak portion 32 can not only meet the support requirements for the electrode assembly 20 but also reduce the space occupied by the buffer pad 30 inside the battery housing 10 .

[0196] According to an example of the present application, as shown in FIG9 , the ratio between the height of the weak portion 32 protruding from the main body 31 and the maximum length of the weak portion 32 in the plane where the main body 31 is located is 1.01-3.0.

[0197] For example, the ratio of the height s of the weak portion 32 protruding from the main body 31 to the maximum length h of the weak portion 32 in the plane where the main body 31 is located can be 1.01, 1.05, 1.1, 1.5, 2, 2.5 or 3.

[0198] In this embodiment, the ratio of the height of the weak portion 32 protruding from the main body 31 to the maximum length dimension of the weak portion 32 in the plane where the main body 31 is located is set to 1.01-3.0, thereby controlling the thickness of the buffer pad 30 so that the buffer pad 30 can maintain the supporting force for the electrode assembly 20 in the early stage of the cycle of the battery cell 100, and can also provide sufficient expansion space for the electrode assembly 20 after the weak portion 32 ruptures in the later stage of the cycle.

[0199] According to an example of the present application, as shown in FIG9 , the ratio between the height of the weak portion 32 protruding from the main body 31 and the maximum length of the weak portion 32 in the plane where the main body 31 is located is 1.5-2.

[0200] For example, the ratio of the height s of the weak portion 32 protruding from the main body 31 to the maximum length h of the weak portion 32 in the plane where the main body 31 is located can be 1.5, 1.6, 1.7, 1.8, 1.9 or 2.

[0201] In this embodiment, by setting the ratio of the height of the weak portion 32 protruding from the main body 31 to the maximum length dimension of the weak portion 32 in the plane where the main body 31 is located to 1.5 to 2, the buffer pad 30 can maintain its support force on the electrode assembly 20 in the early stage of the cycle of the battery cell 100, and can also provide sufficient expansion space for the electrode assembly 20 after the weak portion 32 ruptures in the later stage of the cycle.

[0202] According to an example of the present application, the buffer pad 30 is a polyethylene piece, a polypropylene piece, a polyethylene terephthalate piece, an aerogel piece, a foam material piece or a silicone rubber piece.

[0203] Specifically, the buffer pad 30 can be made of one of the above materials, which all have high resistance to electrolyte corrosion, compressibility, and resilience, and are low in price and simple in manufacturing process.

[0204] In this embodiment, by setting the buffer pad 30 to a polyethylene part, a polypropylene part, a polyethylene terephthalate part, an aerogel part, a foam material part and / or a silicone rubber part, the possibility of the buffer pad 30 being corroded or crushed by the electrolyte can be reduced, the reliability of the buffer pad 30 throughout the life cycle of the battery cell 100 can be improved, and the service life of the buffer pad 30 can be increased; at the same time, the production cost of the buffer pad 30 can also be reduced, and the production cost of the battery 1000 can be reduced.

[0205] According to an example of the present application, as shown in FIG9 , in the first buffering state, the thickness of the buffer pad 30 is 0.5 mm-5 mm.

[0206] In the first buffering state, the thickness of the buffer pad 30 is the sum of the thickness of the weak portion 32 and the thickness m1 of the main body 31 .

[0207] For example, the thickness m of the buffer pad 30 may be 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm.

[0208] In this embodiment, by setting the buffer pad 30 to have a thickness of 0.5mm-5mm in the first buffer state, the buffer pad 30 can support the electrode assembly 20 in the early stage of the battery cell 100 cycle, thereby improving the problem of wrinkling at the electrode interface, thereby alleviating the problem of lithium plating at the interface and improving the performance of the battery cell 100; at the same time, it can also reduce the space occupied by the buffer pad 30, thereby increasing the energy density of the battery cell 100.

[0209] According to an example of the present application, as shown in FIG9 , in the first buffering state, the thickness of the buffer pad 30 is 1 mm-3.5 mm.

[0210] In the first buffering state, the thickness of the buffer pad 30 is the sum of the thickness of the weak portion 32 and the thickness m1 of the main body 31 .

[0211] For example, the thickness m of the buffer pad 30 may be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or 3.5 mm.

[0212] In this embodiment, by setting the buffer pad 30 to have a thickness of 1mm-3.5mm in the first buffer state, the buffer pad 30 can support the electrode assembly 20 in the early stage of the battery cell 100 cycle, and can further limit the space occupied by the buffer pad 30, thereby improving the problem of wrinkling at the electrode interface while not affecting the energy density of the battery cell 100.

[0213] The battery cell 100 according to the second aspect embodiment of the present application, as shown in Figures 11 to 16, includes: a shell 10, an electrode assembly 20 and a buffer pad 30 according to the first aspect embodiment of the present application, the shell 10 has a accommodating cavity 101; the electrode assembly 20 is arranged in the accommodating cavity 101; the buffer pad 30 is arranged between the electrode assembly 20 and the inner wall surface of the accommodating cavity 101, and / or the buffer pad 30 is arranged between two adjacent electrode assemblies 20.

[0214] That is to say, the buffer pad 30 can be arranged only between the electrode assembly 20 and the inner wall of the accommodating cavity 101, or only between two adjacent electrode assemblies 20, or both between the electrode assembly 20 and the inner wall of the accommodating cavity 101 and between two connected electrode assemblies 20.

[0215] When the buffer pad 30 is disposed between the electrode assembly 20 and the inner wall of the accommodating cavity 101, it can not only support and cushion the electrode assembly 20, but also separate the battery case 10 from the electrode assembly 20, effectively preventing the electrode assembly 20 from squeezing the battery case 10 after expansion. When the buffer pad 30 is disposed between two adjacent electrode assemblies 20, it can not only support and cushion the two adjacent electrode assemblies 20, but also separate the adjacent electrode assemblies 20, effectively preventing the adjacent electrode assemblies 20 from squeezing each other after expansion.

[0216] The housing 10 is used to house the electrode assembly 20, electrolyte, and buffer pad 30. It is primarily used to isolate the interior of the battery cell 100 from the outside world, effectively preventing communication between the interior of the battery cell 100 and the outside world, thereby improving the reliability of the battery cell 100. The electrode assembly 20 is the core component of the battery cell 100 and is primarily composed of a negative electrode sheet, a positive electrode sheet, and a separator.

[0217] Among them, the positive electrode sheet is a positive electrode active material coated on the surface of the positive electrode current collector. In some specific embodiments, the positive electrode active material layer includes a ternary material, lithium manganese oxide or lithium iron phosphate, and the positive electrode current collector is aluminum foil. For example, the positive electrode active material adopts a ternary positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2. The negative electrode sheet is a negative electrode active material coated on the surface of a negative electrode current collector. In some specific embodiments, the negative electrode current collector is copper foil, and the negative electrode active material layer includes graphite or silicon. For example, graphite can be used as the negative electrode active material. The separator is provided between the positive and negative electrode sheets to provide isolation.

[0218] Furthermore, the accommodating cavity 101 is filled with an electrolyte. The electrolyte not only provides some active lithium ions, which serve as conductive ions during the charge and discharge process, but also provides ion channels through which lithium ions can move freely, thereby enabling the battery cell 100 to complete the charge and discharge process.

[0219] According to the battery cell 100 of the embodiment of the present application, by setting the buffer pad 30 of the above-mentioned first embodiment, using the main body 31 and the weak part 32 included in the buffer pad 30, the buffer pad 30 can have a good supporting effect on the electrode assembly 20 both in the early and late stages of the cycle of the battery cell 100, and can reduce the deformation of the electrode sheet, thereby improving the wrinkling of the electrode sheet caused by the expansion of the electrode assembly 20, thereby alleviating the lithium plating problem of the electrode assembly 20 during the cycle and improving the performance of the battery cell 100. At the same time, the expansion of the electrode assembly 20 can be restricted, thereby limiting the increase in the expansion force of the electrode assembly 20; in addition, in the second buffer state, the weak part 32 can be destroyed, thereby increasing the compressibility of the buffer pad 30 in the late stage of the cycle, reducing the space occupied by the buffer pad 30 in the late stage of the cycle, thereby effectively preventing the hard expansion of the electrode assembly 20, reducing the risk of a sharp increase in the expansion force of the battery cell 100 in the late stage of the cycle, and improving the cycle service life of the battery cell 100.

[0220] The following describes the preparation process of the battery cell 100 according to the above embodiment based on some specific embodiments.

[0221] First, prepare the negative electrode sheet, positive electrode sheet, separator and electrolyte. Among them, the positive electrode active material uses the ternary positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2, the positive electrode current collector is made of aluminum foil; the negative electrode active material is graphite, and the negative electrode current collector is made of copper foil; the diaphragm is a polyethylene (PE) porous polymer diaphragm (thickness 7um).

[0222] Specifically, the negative electrode sheet is prepared by mixing graphite, conductive carbon black (SP), styrene-butadiene rubber emulsion (SBR), and sodium carboxymethyl cellulose in a mass ratio of 96.2:0.8:1.8:1.2, dissolving the mixture in deionized water, and applying the resulting slurry to both surfaces of a copper foil (6 μm thick) to form a first active material layer. Subsequently, a second active material, conductive carbon black (SP), styrene-butadiene rubber emulsion (SBR), and sodium carboxymethyl cellulose are mixed in a mass ratio of 96.2:0.8:1.8:1.2, and applying the resulting slurry to both surfaces of the first active material layer. The mixture is then dried, cold-pressed, and cut into the negative electrode sheets.

[0223] The preparation method of the positive electrode is to make the active material LiNi 0.8 Co 0.1 Mn 0.1 O2 is mixed with conductive carbon black (SP) and polyvinylidene fluoride (PVDF) in a mass ratio of 96.8:2.2:1, and the mixed substance is then dissolved in N-methylpyrrolidone (NMP). The positive electrode slurry is prepared after slurrying, and then the positive electrode slurry is coated on aluminum foil (12um thick), and then the coated aluminum foil is dried, cold pressed, and cut to obtain the positive electrode sheet.

[0224] The preparation method of the electrolyte is to mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 3:6:1, and then dissolve fully dried lithium salt (LiPF6) in a mixed organic solvent at a ratio of 1 mol / L to obtain the required electrolyte.

[0225] The prepared positive electrode sheet, separator, and negative electrode sheet are then stacked in order, with the separator positioned between the positive and negative electrode sheets. The stacked sheets are then wound to form the desired electrode assembly 20. The two electrode assemblies 20 are welded to the end caps 40, and the cushioning pad 30 is inserted between the two electrode assemblies 20. The entire structure is then placed in the housing 10 to form a dry cell. The prepared electrolyte is then injected into the high-temperature dried dry cell. After vacuum packaging, standing, formation, and shaping, a lithium-ion secondary battery is obtained.

[0226] The battery 1000 according to the embodiment of the third aspect of the present application includes the battery cell 100 according to the embodiment of the second aspect of the present application.

[0227] According to the battery 1000 of the embodiment of the present application, the overall performance of the battery 1000 is improved by providing the battery cell 100 of the embodiment of the second aspect described above.

[0228] The electrical device according to the fourth aspect of the embodiment of the present application includes the battery 1000 according to the embodiment of the third aspect of the present application, and the battery 1000 is used to provide electrical energy.

[0229] According to the electric device of the embodiment of the present application, the overall performance of the electric device is improved by providing the battery 1000 of the embodiment of the third aspect mentioned above.

[0230] The following will describe a battery cell 100 according to three specific embodiments of the present application with reference to FIG. 1 to FIG. 16 .

[0231] Example 1:

[0232] 11 , the battery cell 100 includes a shell 10 , an electrode assembly 20 and a buffer pad 30 , wherein the shell 10 specifically includes a receiving cavity 101 filled with electrolyte; the electrode assembly 20 and the buffer pad 30 each include two, and the buffer pad 30 is arranged between the electrode assembly 20 and the inner wall of the receiving cavity 101 .

[0233] Specifically, the buffer pad 30 is a polyethylene piece, a polypropylene piece, a polyethylene terephthalate piece, an aerogel piece, a foam material piece or a silicone rubber piece.

[0234] The buffer pad 30 includes a main body 31 and a weak portion 32. The main body 31 is plate-shaped. The weak portion 32 is provided on the main body 31 and at least partially protrudes from the surface of the main body 31. The weak portion 32 includes multiple weak portions 32, and the multiple weak portions 32 are arranged in a matrix on the surface of the main body 31. At the same time, weak portions 32 are provided on both side surfaces in the thickness direction of the main body 31, and the multiple weak portions 32 on one side surface of the main body 31 correspond one-to-one to the multiple weak portions 32 on the other side surface of the main body 31, and the corresponding two weak portions 32 are facing each other in the thickness direction of the main body 31.

[0235] Furthermore, the weak portion 32 is a hollow hemispherical shape, and the wall thickness of the weak portion 32 is 20μm-50μm; the diameter of the weak portion 32 is 5mm-20mm; the ratio of the spacing between two adjacent weak portions 32 to the maximum length dimension of the weak portion 32 in the plane where the main body 31 is located is 1-1.5; the ratio of the height of the weak portion 32 protruding from the main body 31 to the maximum length dimension of the weak portion 32 in the plane where the main body 31 is located is 1.5-2; in the projection plane perpendicular to the thickness direction of the main body 31, the ratio of the projected area of ​​multiple weak portions 32 to the projected area of ​​the buffer pad 30 is 40%-60%.

[0236] In addition, a receiving hole is formed on the main body 31, and the periphery of the weak portion 32 is sealed and connected to the periphery of the receiving hole and cooperates to define a cavity. A filler is provided in the cavity, and the filler is a gas capture agent.

[0237] The cushioning pad 30 has a first cushioning state and a second cushioning state. In the first cushioning state, the weak portion 32 protrudes from the surface of the main body 31, and the cushioning pad 30 supports the electrode assembly 20 via the weak portion 32. In the second cushioning state, the weak portion 32 is destroyed, and the cushioning pad 30 supports the electrode assembly 20 via the main body 31. In the first cushioning state, the cushioning pad 30 has a compressibility of less than or equal to 10%, and a thickness of 1 mm to 3.5 mm. In the second cushioning state, the cushioning pad 30 has a compressibility of greater than or equal to 90%.

[0238] Furthermore, under the pressure condition of 0-0.4MPa, the compressibility of the buffer pad 30 is less than or equal to 10%, and the compression rebound rate is greater than or equal to 90%; under the pressure condition of 0.4MPa-0.8MPa, the compressibility of the buffer pad 30 is 40%-60%, and the compression rebound rate is 50%-80%; under the pressure condition of 0.8MPa-1.0MPa, the compressibility of the buffer pad 30 is greater than or equal to 90%, and the compression rebound rate is less than or equal to 5%.

[0239] According to the battery cell 100 of the embodiment of the present application, a buffer pad 30 of the above-mentioned first embodiment is provided. By utilizing the main body 31 and the weak portion 32 included in the buffer pad 30, the buffer pad 30 can provide a good supporting effect on the electrode assembly 20 both in the early and late stages of the cycle of the battery cell 100, reduce the deformation of the pole piece, and further improve the wrinkling of the pole piece caused by the expansion of the electrode assembly 20, thereby alleviating the lithium plating problem of the electrode assembly 20 during the cycle and improving the performance of the battery cell 100. At the same time, the expansion of the electrode assembly 20 can be restricted, thereby limiting the increase in the expansion force of the electrode assembly 20. In addition, in the second buffer state, the weak portion 32 can be destroyed, thereby increasing the compressibility of the buffer pad 30 in the late stage of the cycle and reducing the space occupied by the buffer pad 30 in the late stage of the cycle, thereby effectively preventing the hard expansion of the electrode assembly 20, reducing the risk of a sharp increase in the expansion force of the battery cell 100 in the late stage of the cycle, and improving the cycle service life of the battery cell 100.

[0240] Example 2:

[0241] 13 , the structure of this embodiment is substantially the same as that of the first embodiment, wherein the same components are designated by the same reference numerals, and the only difference is that the buffer pad 30 described in the first embodiment is disposed between the electrode assembly 20 and the inner wall of the accommodating cavity 101 , while the buffer pad 30 described in the second embodiment is disposed between the two electrode assemblies 20 .

[0242] Specifically, the buffer pad 30 is positioned between two adjacent electrode assemblies 20. The filler within the cavity of the buffer pad 30 is a lithium supplement. When positioned between two adjacent electrode assemblies 20, the buffer pad 30 not only supports and cushions the two adjacent electrode assemblies 20, but also separates the adjacent electrode assemblies 20, effectively preventing the adjacent electrode assemblies 20 from squeezing each other after expansion, thereby improving the reliability of the battery cell 100. Furthermore, the lithium supplement can replenish lithium lost during the cycling of the battery cell 100, thereby increasing the cycle life of the battery cell 100.

[0243] Example 3,

[0244] 15 , the structure of this embodiment is substantially the same as that of the first embodiment, wherein the same components are designated by the same reference numerals, and the only difference is that the buffer pad 30 described in the first embodiment is disposed between the electrode assembly 20 and the inner wall of the accommodating cavity 101 , while the buffer pad 30 described in the third embodiment is disposed between the electrode assembly 20 and the inner wall of the accommodating cavity 101 and between the two electrode assemblies 20 .

[0245] Specifically, there are three buffer pads 30, which are respectively arranged between the electrode assembly 20 and the inner wall of the accommodating cavity 101 and between the two electrode assemblies 20. In this way, the buffer pad 30 can support both large surfaces of the electrode assembly 20, and at the same time separate the two adjacent electrode assemblies 20 and the electrode assembly 20 from the battery shell 10, effectively preventing the expansion and squeezing of the electrode assemblies 20 and the electrode assembly 20 on the shell 10; at the same time, the cavity of the buffer pad 30 arranged between the electrode assembly 20 and the inner wall of the accommodating cavity 101 can be filled with a gas capture agent as a filler, and the cavity of the buffer pad 30 arranged between the two adjacent electrode assemblies 20 can be filled with a lithium replenisher as a filler. In this way, the buffer not only plays a supporting role, but also can replenish the lithium lost during the cycle of the electrode assembly 20, and can reduce the gas generated during the cycle of the electrode assembly 20, thereby improving the stability and cycle life of the battery cell 100.

[0246] A comparative example 1 is briefly described below, and this comparative example 1 is used as a comparative example with the above-mentioned embodiment 1 and embodiment 2 of the present application.

[0247] In the comparative example 1, no buffer pad 30 is provided in the battery cell 100 .

[0248] The following test experiments are carried out on Examples 1 to 2 and Comparative Example 1.

[0249] The testing process is as follows:

[0250] The battery cell 100 is tested with a fixture having two steel or aluminum plates, the fixture force is 3000N, and the battery housing 10 is not provided with a buffer pad 30; and a sensor is used to monitor the expansion force value of the buffer large surface of the electrode assembly 20.

[0251] In a constant temperature environment of 25°C, the battery cell 100 is charged and discharged for the first time. Constant current and constant voltage charging (charging to a current of 0.05C) is performed at a charging current of 1.0C (i.e., the current value that completely discharges the theoretical capacity within 1 hour) until the upper limit voltage reaches 4.25V. After standing for 5 minutes, constant current discharge is performed at a discharge current of 1.0C until the final voltage reaches 2.8V. The discharge capacity of the first cycle is recorded; then continuous charge and discharge cycles are performed.

[0252] Here, the capacity retention rate at the nth cycle=(discharge capacity at the nth cycle / discharge capacity at the first cycle)×100.

[0253] After assembly, injection, and high-temperature stabilization, the battery cell 100 undergoes a formation process at a constant temperature of 45°C. Constant-current charging is performed at a charging current of 0.1cc (the current required to completely discharge the theoretical capacity within one hour) until the voltage reaches 3.4V. This is followed by constant-current charging at 0.33C to 3.75V. Ideally, constant-current charging at 0.33C is continued to 4.2V. Constant-voltage charging is then continued until the current reaches 0.05C, at which point the battery 1000 is fully charged. After the fully charged battery 1000 rests for 5 minutes, it is disassembled and the wrinkles at the anode interface are observed.

[0254] The test results of the battery cell 100 cycle capacity retention rate and the electrode assembly 20 interface wrinkling are shown in Table 1:

[0255] Table 1

[0256] The above test results show that compared with comparative example 1, the use of the buffer pad 30 provided in Examples 1 to 2 of the present application can reduce wrinkling on the interface, reduce the expansion force of the electrode assembly 20, and improve the cycle retention rate of the electrode assembly 20. As the number of buffer components increases, the expansion force decreases relatively and the cycle retention rate increases relatively.

[0257] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A buffer pad, arranged in a housing (10) of a battery cell, characterized in that: The buffer pad comprises: Body part(31); a weak portion (32), wherein the weak portion (32) is disposed on the main body portion (31) and at least partially protrudes from the surface of the main body portion (31), The buffer pad has a first buffer state and a second buffer state. In the first buffer state, the weak portion (32) protrudes from the surface of the main body (31), and the buffer pad supports the electrode assembly (20) through the weak portion (32). In the second buffer state, the weak portion (32) is destroyed, and the buffer pad supports the electrode assembly (20) through the main body (31).

2. The cushion according to claim 1, characterized in that: Under a first preset pressure condition, the buffer pad is in the first buffer state, and the compressibility of the buffer pad is less than or equal to 10%; and / or under a second preset pressure condition, the buffer pad is in the second buffer state, and the compressibility of the buffer pad is greater than or equal to 90%.

3. The cushion according to claim 2, characterized in that: The first preset pressure is 0-0.4 MPa; and / or the second preset pressure is 0.8 MPa-1 MPa.

4. The cushion according to any one of claims 2-3, characterized in that: Under the third preset pressure condition, the buffer pad is in the first buffer state, and the compressibility of the buffer pad is 40%-60%, and the third preset pressure is 0.4MPa-0.8MPa.

5. The cushion according to any one of claims 1 to 4, characterized in that: At least part of the circumference of the weak portion (32) is connected to the main body portion (31), and the middle portion protrudes away from the main body portion (31) along the thickness direction of the main body portion (31).

6. The cushion according to claim 5, characterized in that: The periphery of the weak portion (32) is sealedly connected to the main body (31), and a cavity is defined between the weak portion (32) and the main body (31).

7. The cushion according to claim 6, characterized in that: The main body (31) is formed with a receiving hole, the weak portion (32) is sealedly connected to the periphery of the receiving hole, and the weak portion (32) cooperates with the peripheral wall of the receiving hole to define the cavity.

8. The cushion according to claim 6 or 7, characterized in that: A filler is arranged in the cavity, and in the second buffer state, the filler can be released from the cavity.

9. The cushion according to claim 8, characterized in that: The filler is at least one of a lithium supplement and a gas capture agent.

10. The cushioning pad according to claim 9, characterized in that: The filler is at least one of cuprous oxide, cuprous sulfide, cuprous carboxylate, cuprous sulfate, activated carbon, graphene and aluminum oxide.

11. The cushion according to any one of claims 1 to 10, characterized in that: There are a plurality of the weak portions (32), and the plurality of the weak portions (32) are arranged at intervals on the surface of the main body (31).

12. The cushioning pad according to claim 11, characterized in that: The plurality of weak portions (32) are arranged in a matrix on the surface of the main body (31).

13. The cushioning pad according to any one of claims 11 to 12, characterized in that: In a projection plane perpendicular to the thickness direction of the main body (31), the ratio of the projection area of ​​the plurality of weak portions (32) to the projection area of ​​the buffer pad is 20%-80%.

14. The cushioning pad according to claim 13, characterized in that: In a projection plane perpendicular to the thickness direction of the main body (31), the ratio of the projection area of ​​the plurality of weak portions (32) to the projection area of ​​the buffer pad is 40%-60%.

15. The cushioning pad according to any one of claims 11 to 14, characterized in that: The ratio between the spacing between two adjacent weak portions (32) and the maximum length dimension of the weak portion (32) in the plane where the main body portion (31) is located is 1 / 3-2.

16. The cushioning pad according to claim 15, characterized in that: The ratio between the distance between two adjacent weak portions (32) and the maximum length dimension of the weak portion (32) in the plane where the main body portion (31) is located is 1-1.

5.

17. The cushioning pad according to any one of claims 1 to 16, characterized in that: The weak portions (32) are provided on both side surfaces of the main body portion (31) in the thickness direction.

18. The cushioning pad according to claim 17, characterized in that: The main body (31) is provided with a plurality of weak portions (32) on both side surfaces of the thickness square, the plurality of weak portions (32) on one side surface of the main body (31) correspond one to one with the plurality of weak portions (32) on the other side surface of the main body (31), and the two corresponding weak portions (32) are directly opposite in the thickness direction of the main body (31).

19. The cushioning pad according to any one of claims 1 to 18, characterized in that: The weak portion (32) is a hollow structure, and the wall thickness of the weak portion (32) is 5 μm-150 μm.

20. The cushioning pad according to claim 19, characterized in that The wall thickness of the weak portion (32) is 20 μm-50 μm.

21. The cushioning pad according to any one of claims 1 to 20, characterized in that: The outer contour of the weak portion (32) is in the shape of a cylinder, a semi-cylinder, a hemisphere, a semi-ellipsoid or a cuboid.

22. The cushioning pad according to claim 21, characterized in that The weak portion (32) is in the shape of a hollow hemisphere, and the diameter of the weak portion (32) is 1 mm-50 mm.

23. The cushioning pad according to claim 22, characterized in that The diameter of the weak portion (32) is 5 mm to 20 mm.

24. The cushioning pad according to any one of claims 1 to 23, characterized in that: The ratio between the height of the weak portion (32) protruding from the main body (31) and the maximum length dimension of the weak portion (32) in the plane where the main body (31) is located is 1.01-3.

0.

25. The cushioning pad according to claim 24, characterized in that The ratio between the height of the weak portion (32) protruding from the main body (31) and the maximum length dimension of the weak portion (32) in the plane where the main body (31) is located is 1.5-2.

26. The cushioning pad according to any one of claims 1 to 25, characterized in that: The buffer pad is a polyethylene piece, a polypropylene piece, a polyethylene terephthalate piece, an aerogel piece, a foam material piece or a silicone rubber piece.

27. The cushioning pad according to any one of claims 1 to 26, characterized in that: In the first buffering state, the thickness of the buffer pad is 0.5 mm-5 mm.

28. The cushioning pad according to claim 27, characterized in that In the first buffering state, the thickness of the buffer pad is 1mm-3.5mm.

29. A battery cell, characterized in that: include: A housing (10), wherein the housing (10) has a receiving chamber (101); An electrode assembly (20), the electrode assembly (20) being arranged in the accommodating cavity (101); According to any one of claims 1 to 28, the buffer pad is arranged between the electrode assembly (20) and the inner wall surface of the accommodating cavity (101), and / or the buffer pad is arranged between two adjacent electrode assemblies (20).

30. A battery, characterized in that: Comprising the battery cell according to claim 29.

31. An electrical equipment, characterized in that: The battery of claim 30 is used to provide electrical energy.

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