CN216698428U

CN216698428U - Electrode assembly, battery cell, battery, and power consumption device

Info

Publication number: CN216698428U
Application number: CN202220095243.8U
Authority: CN
Inventors: 周建华; 宋晋阳
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2022-06-07
Anticipated expiration: 2032-01-14

Abstract

The embodiment of the application provides an electrode assembly, a single battery, a battery and an electric device, wherein the electrode assembly comprises a pole piece and a spacer, the pole piece and the spacer are wound along a winding direction to form a winding structure, and the winding structure comprises a bending area; the pole piece is including being located the first kink in kink district, and the surface of first kink has attached first protective layer, and the inboard of first kink is provided with the second protective layer adjacent with first kink, first protective layer with the second protective layer all covers the middle part of first kink along the direction of coiling. Through the setting of first protective layer and second protective layer, can effectively avoid electrode subassembly when hot pressing is convoluteed, the pole piece arouses because of being buckled that the powder falls, the condition such as fracture even of substrate printing opacity, and secondly, the structure of two-layer setting also can be in the hot pressing in-process, has restrained the powder of sunken side and has slided to the powder of protruding side provides stronger constraint fixed ability.

Description

Electrode assembly, battery cell, battery, and power consumption device

Technical Field

The application belongs to the technical field of batteries, and particularly relates to an electrode assembly, a battery monomer, a battery and an electric device.

Background

As natural resources are consumed and environmental destruction is increased, interest in devices that can store energy and efficiently use the stored energy is increased in various fields. The battery cell may be a system utilizing new renewable energy, a battery system, and an existing power system, which are combined with each other.

Safety issues are also a considerable problem in the development of battery cells. Therefore, how to enhance the safety of the battery cell is a technical problem to be solved urgently in the battery technology.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides an electrode assembly, a single battery, a battery and an electric device, and can improve the safety of the single battery.

In a first aspect of the embodiments of the present application, there is provided an electrode assembly including a pole piece and a separator, the pole piece and the separator being wound in a winding direction and forming a winding structure, the winding structure including a bending region. The pole piece comprises a first bending part located in the bending area, a first protective layer is attached to the outer surface of the first bending part, a second protective layer adjacent to the first bending part is arranged on the inner side of the first bending part, and the first protective layer and the second protective layer both cover the middle of the first bending part in the winding direction.

Adopt above-mentioned structure, through the setting of first protective layer and second protective layer, can effectively avoid electrode subassembly when hot pressing is convoluteed, the pole piece arouses because of being bent to fall the circumstances such as powder, substrate printing opacity fracture even, and secondly, the structure of two-layer setting also can be in hot pressing in-process, has restrained the powder of sunken side and has slided to provide stronger constraint fixed ability to the powder of protruding side, can effectively improve the bending deformation degree in the district of buckling.

In some embodiments of the present application, the second protection layer is stacked on the first bent portion and is not attached to the first bent portion.

By adopting the structure, the protection layer is fixedly connected with the convex side of the pole piece in the bending area, so that the bending curvature diameter of the joint can be increased, the deformation degree of the corresponding pole piece is reduced, and the extrusion force of powder on the concave side in the bending process to the pole piece of the inner ring and the internal stress of the powder are reduced.

In some embodiments of the present application, the second protective layer is attached to the spacer.

By adopting the structure, the second protective layer is attached to the isolating piece, so that the second protective layer can be conveniently fixed in the bending area, dislocation is reduced, and the yield is improved.

In some embodiments of the present application, the tensile strength of the first protective layer is greater than the tensile strength of the second protective layer.

Adopt above-mentioned structure, can guarantee that the protruding side of pole piece can obtain higher ability of buckling in the district of buckling, prevent that first protective layer fracture, and can closely laminate in the pole piece, secondly, can prevent that the second protective layer of the sunken side in the district of buckling from having great stress when buckling, resists the process of buckling.

In some embodiments of the present application, the first protective layer and the second protective layer are both located within the inflection region.

By adopting the structure, each layer in the bending area can be protected more accurately, the consumption of the first protective layer and the second protective layer is reduced, and the structure in the electrode assembly is simplified.

In some embodiments of the present application, the pole piece includes a plurality of bent portions located in the bent region, and at least one of the innermost bent portions is the first bent portion.

By adopting the structure, when a plurality of layers of pole pieces appear in the bending area, the innermost pole piece in the bending area is effectively protected.

In some embodiments of the present application, in the bending region, the number of the bending portions is N, M bending portions which are continuous from inside to outside are the first bending portion, and M/N has a value of 0.1-0.4.

By adopting the structure, in the bending process, the stress at the bending part of the pole piece is strongly related to the curvature diameter, so that the smaller the curvature diameter is, the higher the powder falling and light transmitting probability is, and the risk of serious powder falling and light transmitting exists in the region of the inner layer of the bending region, so that the safety problem of the battery caused by the powder falling and light transmitting of the pole piece can be remarkably reduced after the first protective layer and the second protective layer are additionally arranged in the region.

In some embodiments of the present application, in a first direction, at least one end of the first protection layer and the second protection layer extends beyond the first bending portion, and portions of the first protection layer and the second protection layer beyond the first bending portion are connected, where the first direction is orthogonal to the winding direction.

In some embodiments of the present application, the first protective layer and the second protective layer are integrally formed.

By adopting the structure, the first protective layer and the second protective layer can be uniformly distributed on two sides of the pole piece, so that the stress on the pole piece is more uniform, and the stability of the electrode assembly is improved.

In some embodiments of the present application, each of the first protective layer and the second protective layer includes a substrate region and two edge regions, and the two edge regions are respectively located at two ends of the substrate region along the winding direction; the thickness of the edge region decreases in a direction away from the base region.

By adopting the structure, the edges and corners in the winding direction can be reduced by adjusting the thickness of the protective layer in the winding direction, the fault structures at two ends of the protective layer are reduced, and the two ends of the adjacent pole piece protective layer are prevented from being broken.

In a second aspect of the present embodiments, a battery cell is provided, which includes a housing and the electrode assembly, and the electrode assembly is accommodated in the housing.

In a third aspect of the embodiments of the present application, a battery is provided, which includes a box body and the above battery cell, and the battery cell is accommodated in the box body.

In a fourth aspect of the embodiments of the present application, there is provided an electric device, including the above battery, for supplying electric energy.

Compared with the prior art, through the setting of first protective layer and second protective layer, can effectively avoid electrode subassembly when hot pressing is convoluteed, the pole piece arouses because of being buckled that the circumstances such as fall powder, substrate printing opacity fracture even, and secondly, the structure of two-layer protective layer also can be at hot pressing in-process, has restrained the powder of sunken side and has slided to provide stronger constraint fixed ability to the powder of protruding side, can effectively improve the bending deformation degree in the district of buckling.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a vehicle according to some embodiments of the present application.

Fig. 2 is an exploded view of a battery provided in some embodiments of the present application.

Fig. 3 is a schematic structural view of the battery module of the embodiment shown in fig. 2.

Fig. 4 is an exploded view of a battery cell according to some embodiments of the present disclosure.

Fig. 5 is a schematic structural view of an electrode assembly provided in some embodiments of the present application.

Fig. 6 is an enlarged view of fig. 5 at the bend region.

Fig. 7 is a schematic sectional structure view of the electrode assembly of the embodiment shown in fig. 5 in the thickness direction.

Fig. 8 is a schematic cross-sectional structure of the first protection layer along the thickness direction according to some embodiments of the present disclosure.

Fig. 9 is a schematic cross-sectional structure view of a first protection layer according to another embodiment of the present application.

In the drawings:

1. an electrode assembly; 11. pole pieces; 12. a spacer; 13. a first bent portion; 131. a first protective layer; 132. a second protective layer; 133. a connecting layer;

10. a battery cell; 20. a housing; 21. an end cap; 22. a housing;

110. a box body; 111. a first tank portion; 112. a second tank portion; 120. a battery module;

100. a battery; 200. a controller; 300. a motor; 1000. a vehicle.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following embodiments are merely used to more clearly illustrate the technical solutions of the present application, and therefore, the following embodiments are only used as examples, and the scope of the present application is not limited thereby.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "including" and "having," and any variations thereof, in the description and claims of this application and the description of the above figures are intended to cover non-exclusive inclusions.

In the description of the embodiments of the present application, the technical terms "first", "second", and the like are used only for distinguishing different objects, and are not to be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary-secondary relationship of the technical features indicated. In the description of the embodiments of the present application, "a plurality" means two or more unless specifically defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is only one kind of association relation describing an associated object, and means that three kinds of relations may exist, for example, a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" means two or more (including two), and similarly, "plural sets" means two or more (including two sets), "plural pieces" means two or more (including two pieces).

In the description of the embodiments of the present application, the technical terms "center", "longitudinal" and "transverse" are used "

The indicated orientations or positional relationships such as "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the embodiments of the present application and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus are not to be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless otherwise explicitly specified or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral part; mechanical connection or electrical connection is also possible; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the embodiments of the present application can be understood by those of ordinary skill in the art according to specific situations.

At present, from the perspective of market development prospect and application trend, the compression of battery volume is a hot spot for improvement long pursued in the field. The main structure of the existing battery comprises a shell and a battery component therein, and the volume of the electrode component occupies a large ratio, which is a main reason for influencing the volume of the battery. Typically the electrode assembly may be volumetrically compressed by winding the pole pieces and separator and then compacting.

The inventor of the application notices that in the electrode assembly obtained by adopting the winding mode, the stress borne by the pole piece in the bending area is large in the winding and compacting process, so that the situations of pole piece powder falling, base material light transmission and even breakage and the like in the bending area are easy to occur, and potential safety hazards exist. In the prior art, when the problem of lithium separation caused by overlarge gaps among the layers of the pole piece is solved, the problem of lithium separation can be solved by additionally arranging the barrier layers among the layers of the pole piece, and the safety problem caused by loss of the pole piece in the bending area can be solved in an auxiliary manner. But present barrier layer is mostly the unilateral setting, can laminate and solve the lithium problem of analysing, but falls powder, substrate printing opacity, the cracked improvement effect of pole piece to the pole piece and is limited.

In order to alleviate the defects of the winding structure used in the conventional electrode assembly, the applicant researches and discovers that the bending region can be protected by adding protective layers on two sides of the electrode plate in the bending region in the winding structure, so that the electrode plate is prevented from being broken, and the winding structure is generally suitable for the conventional electrode assembly.

In view of the above, the present inventors have conducted extensive studies to design an electrode assembly, a battery cell, a battery, and an electric device in order to solve the problems of the winding structure used in the conventional electrode assembly.

The embodiment of the application provides an electric device using a battery as a power supply, wherein the electric device can be but is not limited to a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, a battery car, an electric automobile, a ship, a spacecraft and the like. The electric toy may include a stationary or mobile electric toy, such as a game machine, an electric car toy, an electric ship toy, an electric airplane toy, and the like, and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

For convenience of description, the following embodiments take an example in which a power consuming apparatus according to an embodiment of the present application is a vehicle 1000.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present disclosure. The vehicle 1000 may be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile may be a pure electric automobile, a hybrid electric automobile, or a range-extended automobile, etc. The battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom or the head or the tail of the vehicle 1000. The battery 100 may be used for power supply of the vehicle 1000, for example, the battery 100 may serve as an operation power source of the vehicle 1000. The vehicle 1000 may further include a controller 200 and a motor 300, the controller 200 being configured to control the battery 100 to supply power to the motor 300, for example, for power requirements for operation during starting, navigation, and traveling of the vehicle 1000.

In some embodiments of the present application, the battery 100 may not only serve as an operating power source of the vehicle 1000, but also serve as a driving power source of the vehicle 1000, instead of or in part of fuel or natural gas to provide driving power for the vehicle 1000.

In some embodiments of the present application, a battery refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, batteries typically include a case for enclosing one or more battery cells. The box can avoid liquid or other foreign matters to influence the charging or discharging of battery monomer.

Referring to fig. 2, fig. 2 is an exploded view of a battery 100 according to some embodiments of the present disclosure. The battery 100 includes a case 110 and the battery cell 10 (not shown in fig. 2), and the battery cell 10 is accommodated in the case 110. The case 110 is used to accommodate the battery cell 10, and the case 110 may have various structures. In some embodiments, the box body 110 may include a first box body portion 111 and a second box body portion 112, the first box body portion 111 and the second box body portion 112 cover each other, and the first box body portion 111 and the second box body portion 112 jointly define a receiving space for receiving the battery cell 10. The second casing part 112 may be a hollow structure with one open end, the first casing part 111 is a plate-shaped structure, and the first casing part 111 covers the open side of the second casing part 112 to form the casing 110 with an accommodating space; the first casing portion 111 and the second casing portion 112 may be hollow structures with one side opened, and the opening side of the first casing portion 111 covers the opening side of the second casing portion 112 to form the casing 110 having the accommodating space. Of course, the first and

second casing portions

111 and 112 may be various shapes, such as a cylinder, a rectangular parallelepiped, and the like.

In order to improve the sealing property after the first casing portion 111 and the second casing portion 112 are connected, a sealing member, such as a sealant or a gasket, may be provided between the first casing portion 111 and the second casing portion 112. And assuming that the first box portion 111 covers the top of the second box portion 112, the first box portion 111 may also be referred to as an upper box cover, and the second box portion 112 may also be referred to as a lower box 110.

In the battery 100, there may be one or a plurality of battery cells 10. If there are a plurality of battery cells 10, the plurality of battery cells 10 may be connected in series, in parallel, or in series-parallel, where in series-parallel refers to that the plurality of battery cells 10 are connected in series or in parallel. The plurality of battery cells 10 can be directly connected in series or in parallel or in series-parallel, and the whole formed by the plurality of battery cells 10 is accommodated in the box body 110; of course, a plurality of battery cells 10 may be connected in series, in parallel, or in series-parallel to form a battery module 120, and a plurality of battery modules 120 may be connected in series, in parallel, or in series-parallel to form a whole and accommodated in the case 110.

In the present application, please refer to fig. 3, and fig. 3 is a schematic structural diagram of the battery module 120 shown in fig. 2. The battery module 120 is formed by connecting a plurality of battery cells 10 in series, in parallel, or in series-parallel. The plurality of battery modules 120 are connected in series or in parallel or in series-parallel to form a whole, and are accommodated in the case 110.

Specifically, the plurality of battery cells 10 in the battery module 120 may be electrically connected to each other by the bus bar member, so as to realize parallel connection, series connection, or parallel connection of the plurality of battery cells 10 in the battery module 120.

Fig. 4 is an exploded view of the battery cell 10 according to some embodiments of the present disclosure. As shown in fig. 4, the battery cell 10 provided in the embodiment of the present application includes an electrode assembly 1 and a case 20, and the electrode assembly 1 is accommodated in the case 20.

In some embodiments, housing 20 may also be used to contain an electrolyte, such as an electrolyte. The housing 20 can take a variety of configurations.

In some embodiments, the case 20 may include a case 22 and an end cap 21, the case 22 having a hollow structure with one side open, and the end cap 21 covering the opening of the case 22 and forming a sealing connection to form a sealed space for accommodating the electrode assembly 1 and the electrolyte.

Without limitation, the housing 22 may be a variety of shapes, such as a cylinder, a rectangular parallelepiped, or the like. The shape of the case 22 may be determined according to the specific shape of the electrode assembly 1. For example, if the electrode assembly 1 has a cylindrical structure, it may be selected as the cylindrical case 22; if the electrode assembly 1 has a rectangular parallelepiped structure, a rectangular parallelepiped case 22 may be used. Of course, the end cap 21 may have various structures, for example, the end cap 21 has a plate-like structure, a hollow structure with one end open, and the like. Illustratively, in fig. 4, the housing 22 is a rectangular parallelepiped structure, the end cap 21 is a plate structure, and the end cap 21 covers an opening at the top of the housing 22.

In some embodiments, the battery cell 10 may further include a positive electrode terminal and a negative electrode terminal, both mounted on the end cap 21. The positive electrode terminal and the negative electrode terminal are each used to be electrically connected to the electrode assembly 1 to output electric energy generated by the electrode assembly 1.

In other embodiments, the case 20 may have other structures, for example, the case 20 includes a case 22 and two end caps 21, the case 22 has a hollow structure with two opposite open sides, and one end cap 21 is correspondingly covered on one open side of the case 22 and is connected to the open side in a sealing manner, so as to form a sealed space for accommodating the electrode assembly 1 and the electrolyte. In this structure, the positive electrode terminal and the negative electrode terminal may be mounted on the same end cap 21 or may be mounted on different end caps 21.

In the battery cell 10, one or more electrode assemblies 1 may be accommodated in the case 20.

Fig. 5 is a schematic structural view of an electrode assembly 1 according to some embodiments of the present disclosure. As shown in fig. 5, the electrode assembly 1 includes a pole piece 11 and a separator 12, the pole piece 11 and the separator 12 being wound in a winding direction a and forming a wound structure, the wound structure including a bending region; the pole piece 11 includes the first kink 13 that is located the kink district, and the surface of first kink 13 has attached first protective layer 131, and the inboard of first kink 13 is provided with the second protective layer 132 adjacent with first kink 13, and first protective layer 131 and second protective layer 132 all cover the middle part of first kink 13 along winding direction a.

The pole piece 11 may include, without limitation, a positive pole piece and a negative pole piece. Specifically, the separator 12 is used to separate the positive electrode tab from the negative electrode tab, so as to reduce the risk of short circuit between the positive electrode tab and the negative electrode tab. The separator 12 has a large number of through pores, which can ensure free passage of electrolyte ions and good permeability to lithium ions. Specifically, the positive electrode tab, the separator 12, and the negative electrode tab are sequentially laminated and then wound to form the electrode assembly 1. Without limitation, the first protective layer 131 and the second protective layer 132 at least cover a bending center point of the first bending portion 13 along the winding direction a.

In the present embodiment, the winding direction a is a direction in which the pole piece 11 is wound from inside to outside in the circumferential direction. In fig. 5, the winding direction a is clockwise. For example, the material of the spacer 12 may be PP (polypropylene) or PE (polyethylene), etc.

In the present embodiment, the electrode assembly 1 may have various shapes, for example, the electrode assembly 1 may have a cylindrical shape, a flat shape, a prism shape (e.g., a triangular prism, a quadrangular prism, or a hexagonal prism), or other shapes.

In some embodiments, the first bent portion 13 is bent substantially in a circular arc shape. Illustratively, the electrode assembly 1 is a flat body. Illustratively, the coiled structure further includes a flat region C connected to the bend region B. The flat region C is a region where the electrode assembly 1 has a flat structure. Illustratively, the bending regions B are two and are respectively connected to two ends of the straight region C.

Without limitation, attaching means attaching the first protective layer 131 to the pole piece 11 means forming the first protective layer 131 on the pole piece 11 by adhesion, coating, spraying, or other means.

Through the setting of first protective layer 131 and second protective layer 132, can effectively avoid electrode subassembly 1 when hot pressing is convoluteed, pole piece 11 arouses because of being buckled that the circumstances such as powder falls, substrate printing opacity splits even, and secondly, the powder of sunken side slides also can be restrained at hot pressing in-process to the structure of two-layer setting, and provides stronger constraint fixed ability to the powder of protruding side, can effectively improve the buckling deformation degree in the bending zone.

In some embodiments of the present application, the second protection layer 132 is stacked on the first bent portion 13 and is not attached to the first bent portion 13.

The second protection layer 132 can be independently disposed on the pole piece 11, which means that the second protection layer 132 is separately stacked with the pole piece 11, i.e. has no adhesion or coating relationship.

Through the protruding side fixed connection with pole piece 11 in protective layer and the bending zone, can increase the bending curvature diameter of junction to the messenger corresponds pole piece 11 deformation degree and reduces, if the sunken side also attaches, then in the in-process of buckling, the less second protective layer 132 of bending curvature diameter receives great bending force, can further act on pole piece 11 on the contrary, causes pole piece 11 to damage.

In some embodiments of the present application, the second protective layer 132 is attached to the separator 12.

By attaching the second protection layer 132 to the spacer 12, the second protection layer 132 can be fixed in the bending region conveniently, so that the dislocation is reduced, and the yield is improved.

In some embodiments of the present application, the tensile strength of the first protective layer 131 is greater than the tensile strength of the second protective layer 132.

Tensile strength, which may also be referred to as tensile strength, reflects the resistance of the material to fracture. The ability of the material or test piece to resist breakage when subjected to static tension or the maximum tensile force (tensile stress) that the material can withstand without breaking.

The tensile strength of the first protective layer 131 can be measured as follows: cutting a section of sample on the first protective layer 131, and measuring the cross-sectional area S of the sample; fixing the two ends of the sample on the pull rodOn a force testing machine; starting a tensile testing machine, loading at a constant speed, and recording the maximum load F of the shear failure of the sample; the tensile strength of the first protective layer 131 can be measured by calculating F/S. The unit of tensile strength is N/m²。

Similarly, the tensile strength of the second passivation layer 132 can be measured according to the above method.

Can guarantee that the protruding side of utmost point piece 11 can obtain higher ability of buckling in the district of buckling, prevent that first protective layer 131 from splitting, and can closely laminate in utmost point piece 11, secondly, can prevent that the second protective layer 132 of the sunken side in the district of buckling from having great stress when buckling, resists the process of buckling.

In some embodiments of the present application, the first protection layer 131 and the second protection layer 132 are both located in the bending region.

It is possible to protect each layer in the bending region more accurately, reduce the amount of the first protective layer 131 and the second protective layer 132, and simplify the structure of the electrode assembly 1.

Fig. 6 is an enlarged view of fig. 5 at the bend region. As shown in fig. 6, in some embodiments of the present application, the pole piece 11 includes a plurality of folds at the fold regions, and at least the innermost one of the folds is a first fold 13.

When a plurality of pole pieces 11 are arranged in the bending area, the innermost pole piece 11 in the bending area is effectively protected.

In some embodiments of the present application, in the bending region, the number of the bending portions is N, M bending portions which are continuous from the inside to the outside are the first bending portions 13, and the value of M/N is 0.1-0.4.

Wherein the value of M/N may be 0.3.

In the bending process, the stress magnitude of the bent part of the pole piece 11 is strongly related to the curvature diameter, so that the smaller the curvature diameter is, the higher the powder falling and light transmitting probability is, and the risk of serious powder falling and light transmitting exists in the region of the inner layer of the bending region, so that after the first protective layer 131 and the second protective layer 132 are additionally arranged in the region, the safety problem of the battery 100 caused by the powder falling and light transmitting of the pole piece 11 can be remarkably reduced.

Fig. 7 is a schematic sectional structure view of the electrode assembly 1 of the embodiment shown in fig. 5 in the thickness direction. As shown in fig. 7, in some embodiments of the present application, in the first direction X, at least one end of the first protection layer 131 and the second protection layer 132 extends beyond the pole piece 11 in the bending region, and the portions of the first protection layer 131 and the second protection layer 132 beyond the bending region are connected, and the first direction X is orthogonal to the winding direction.

In some embodiments of the present application, the first protective layer 131 and the second protective layer 132 are integrally formed.

Without limitation, the pole piece 11 is provided with a connection layer 133 at one end in the first direction X, and the first protection layer 131 and the second protection layer 132 are connected through the connection layer 133. Illustratively, the connection layer 133 is formed by extending and bending the first protection layer 131 and the second protection layer 132 on both sides.

By adopting the above structure, the first protective layer 131 and the second protective layer 132 can be uniformly arranged on both sides of the pole piece 11, so that the stress on the pole piece 11 can be more uniform, and the stability of the electrode assembly 1 can be improved; secondly, the first protection layer 131 and the second protection layer 132 disposed on both sides are connected to each other, so as to reduce the risk that the first protection layer 131 and the second protection layer 132 fall off from the first pole piece 11, improve the reliability of the structure, and ensure the feasibility of the winding process when the second protection layer 132 is not attached.

For example, the cross-sectional structures of the first protective layer 131 and the second protective layer 132 are the same in the thickness direction, and the first protective layer 131 will be described as an example below.

Fig. 8 is a schematic cross-sectional structure of the first protection layer 131 along the thickness direction according to some embodiments of the present disclosure, and fig. 9 is a schematic cross-sectional structure of the first protection layer 131 along the thickness direction according to other embodiments of the present disclosure. As shown in fig. 8 and 9, in some embodiments of the present application, the first protective layer 131 and the second protective layer 132 include a base region 133 and two edge regions 134, which are respectively located at two ends of the base region 133 along the winding direction; the thickness of the edge regions 134 decreases in a direction away from the base region 133.

The cross section of the first protective layer 131 and the second protective layer 132 along the thickness direction may be a trapezoid or a trapezoid-like structure with two sides being arcs. Without limitation, the cross section of the first and second

protective layers

131 and 132 in the thickness direction may be a shuttle shape.

Through the adjustment to the thickness of the protective layer in the winding direction, the edge angle in the winding direction can be reduced, the fault structures at two ends of the protective layer are reduced, when the pole piece 11 expands, the pole piece 11 and the first protective layer 131 or the second protective layer 132 can be extruded mutually, and the thinning processing is performed on the edge area 133, so that the stress concentration between the pole piece 11 and the first protective layer 131 or the second protective layer 132 is reduced, and the risk that the pole piece 11 is cracked due to the edge area 134 is reduced.

In some embodiments, the surface of the edge region 153 facing away from the pole piece 11 is an arcuate surface. The cambered surface is smoother, can better disperse stress, reduce the stress concentration on the pole piece 11, reduce the risk of pole piece 11 fracture. Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; these modifications and substitutions do not cause the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present application, and are intended to be covered by the claims and the specification of the present application. In particular, the features mentioned in the embodiments can be combined in any manner, as long as no structural conflict exists. This application is not intended to be limited to the particular embodiments disclosed herein but is to cover all embodiments that may fall within the scope of the appended claims.

Claims

1. An electrode assembly comprising a pole piece and a separator wound in a winding direction and forming a wound structure, the wound structure comprising a bend region;

the pole piece comprises a first bending part located in the bending area, a first protective layer is attached to the outer surface of the first bending part, a second protective layer adjacent to the first bending part is arranged on the inner side of the first bending part, and the first protective layer and the second protective layer both cover the middle of the first bending part in the winding direction.

2. The electrode assembly of claim 1, wherein the second protective layer is stacked on and unattached to the first bend.

3. The electrode assembly of claim 2, wherein the second protective layer is attached to the separator.

4. The electrode assembly of claim 1, wherein the tensile strength of the first protective layer is greater than the tensile strength of the second protective layer.

5. The electrode assembly of claim 1, wherein the first protective layer and the second protective layer are both located within the inflection region.

6. The electrode assembly of claim 1, wherein the pole piece includes a plurality of bends at the bend region, at least an innermost one of the bends being the first bend.

7. The electrode assembly according to claim 6, wherein the number of the bent portions is N, M bent portions continuing from the inside to the outside are the first bent portions, and the value of M/N is 0.1-0.4 in the bent region.

8. The electrode assembly of claim 1, wherein at least one end of the first and second passivation layers extends beyond the first bend portion in a first direction, and the first and second passivation layers are connected at portions beyond the first bend portion, the first direction being orthogonal to the winding direction.

9. The electrode assembly of claim 8, wherein the first and second protective layers are integrally formed.

10. The electrode assembly of any of claims 1-9, wherein each of the first and second protective layers comprises a base region and two edge regions, the two edge regions being located at respective ends of the base region in the winding direction;

the thickness of the edge region decreases in a direction away from the base region.

11. A battery cell comprising a housing and an electrode assembly as claimed in any one of claims 1 to 10, wherein the electrode assembly is housed within the housing.

12. A battery comprising a case and the battery cell of claim 11, wherein the battery cell is accommodated in the case.

13. An electrical device comprising a battery as claimed in claim 12 for providing electrical energy.