CN216903239U

CN216903239U - Electrode assembly, single battery, battery and electric equipment

Info

Publication number: CN216903239U
Application number: CN202122613476.0U
Authority: CN
Inventors: 金泽林; 陈威; 郑巨胜; 郑东来; 史东洋
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2021-10-28
Filing date: 2021-10-28
Publication date: 2022-07-05
Anticipated expiration: 2031-10-28

Abstract

The embodiment of the application provides an electrode subassembly, battery monomer, battery and consumer, belongs to battery technical field. The electrode assembly comprises a first pole piece, a second pole piece and a separator, and is wound along the winding direction to form a winding structure, and the separator is arranged between the first pole piece and the second pole piece; the separator is provided with a first composite area and a second composite area, the first composite area is closer to the winding starting end of the separator than the second composite area in the winding direction, the surface of at least one side of the first composite area and the surface of at least one side of the second composite area are compounded with the heat-resistant layer, the maximum thickness of the heat-resistant layer of the first composite area is smaller than the minimum thickness of the heat-resistant layer of the second composite area, and the thermal stability of the battery is economically and reliably improved.

Description

Electrode assembly, single battery, battery and electric equipment

Technical Field

The application relates to the technical field of batteries, in particular to an electrode assembly, a battery monomer, a battery and electric equipment.

Background

At present, most batteries are secondary batteries, and after the batteries are discharged, the active materials can be activated by a charging mode for continuous use. Secondary batteries are widely used in electronic devices such as mobile phones, notebook computers, battery cars, electric automobiles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools, etc.

The electrode assembly is a core component for realizing the charging and discharging functions of the battery, and generally comprises two pole pieces with different polarities and a separator positioned between the two pole pieces, wherein in the battery, the two pole pieces are contacted with each other to cause short circuit due to the fact that the separator is deformed by heating. How to economically and reliably improve the thermal stability of the battery becomes a problem to be solved urgently.

Disclosure of Invention

The application provides an electrode subassembly, battery monomer, battery and consumer, can improve the thermal stability of battery more economically, reliably.

In a first aspect, an embodiment of the present application provides an electrode assembly, which includes a first pole piece, a second pole piece, and a separator, and is wound along a winding direction to form a winding structure, wherein the separator is disposed between the first pole piece and the second pole piece. The separator is provided with a first composite area and a second composite area, the first composite area is closer to the winding starting end of the separator than the second composite area in the winding direction, the surface of at least one side of the first composite area and the surface of at least one side of the second composite area are compounded with heat-resistant layers, and the maximum thickness of the heat-resistant layers of the first composite area is smaller than the minimum thickness of the heat-resistant layers of the second composite area.

According to this application embodiment, the separator sets up between first pole piece and second pole piece for keep apart first pole piece and second pole piece, prevent that first pole piece and second pole piece contact from causing the short circuit. The separator has a first composite region and a second composite region, and a heat-resistant layer is compounded on at least one side surface of the first composite region and the second composite region, and the heat-resistant layer improves the heat-resistant performance of the electrode assembly. The risk that the first pole piece and the second pole piece are in contact to cause short circuit due to thermal deformation of the isolating piece is reduced. The maximum thickness of the first composite zone heat-resistant layer is smaller than the minimum thickness of the second composite zone heat-resistant layer, so that the heat resistance of the outer ring of the electrode assembly is enhanced, the manufacturing cost of the electrode assembly is reduced, and the energy density of the battery is improved.

In some embodiments, the first composite region extends at least to the winding start of the first or second pole piece and the second composite region extends at least to the winding end of the first or second pole piece in the winding direction.

According to the embodiment of the application, the first composite area extends to the winding starting end of the first pole piece or the second pole piece, and the second composite area at least extends to the winding tail end of the first pole piece or the second pole piece, so that the area of the partition, projected and overlapped in the thickness direction of the first pole piece and the second pole piece, is provided with the heat-resistant layer, and the possibility of keeping the partition between the first pole piece and the second pole piece at high temperature is further improved.

In some embodiments, the second composite region partially extends beyond the winding end of the first or second pole piece in the winding direction, the extending portion surrounding the electrode assembly at least one turn.

According to the embodiment of the application, the heat-resistant layer has a certain heat insulation effect, so that the second composite region exceeds the first pole piece or the second pole piece and partially surrounds the electrode assembly for at least one circle, a certain blocking effect is realized on the heat transfer from the fault electrode assembly to the surrounding electrode assembly, the spread of the heat is delayed, and the safety performance of the battery is improved.

In some embodiments, the first composite zone and the second composite zone each have a plurality of sub-composite zones, each sub-composite zone having a uniform heat resistant layer thickness, the heat resistant layer thickness of the plurality of sub-composite zones increasing in the direction of winding.

According to the embodiment of the application, the thickness of the heat-resistant layer in each sub-composite area is unchanged, the processing difficulty of compounding the heat-resistant layer and the isolating piece is reduced, and the production efficiency is improved. The heat-resistant layer thickness of the plurality of sub-composite regions increases in the winding direction, so that the heat-resistant property of the heat-resistant layer is gradually enhanced in the winding direction.

In some embodiments, the heat resistant layer thickness of the first composite zone and the second composite zone continuously increases in the direction of winding.

According to the embodiment of the application, the thickness of the heat-resisting layer is continuously increased in the winding direction, so that the first pole piece, the isolating piece and the second pole piece are tightly attached to each other after the winding structure is hot-pressed, and the energy density of the battery is further improved.

In some embodiments, both sides of the second composite zone are composited with a heat resistant layer.

According to the embodiment of the application, the heat-resistant layers are compounded on the two surfaces of the second compounding area, so that the heat resistance of the outer ring of the electrode assembly is further improved, and the heat is prevented from being transferred to the inner ring of the electrode assembly to a certain extent.

In some embodiments, the heat resistant layer is a ceramic layer.

According to the embodiment of the application, the ceramic layer has good heat resistance, resists electrolyte and is not easy to burn, so that the ceramic layer can prevent the deformation of the separator to a certain extent when the temperature of the battery rises.

In some embodiments, the ceramic layer has a thickness D, 0.75 μm D3 μm.

According to the embodiment of the application, the ceramic layer is designed in different areas according to different thicknesses, so that the heat resistance of the electrode assembly is improved, and meanwhile, the cost waste and the energy density loss are reduced.

Second aspect an embodiment of the present application provides a battery cell, including a case and the above-described electrode assembly; the electrode assembly is housed in the case.

In the above scheme, the battery cell includes an electrode assembly, the electrode assembly includes a first pole piece, a second pole piece and a spacer, the spacer is disposed between the first pole piece and the second pole piece, and the first pole piece, the second pole piece and the spacer are wound in a winding direction to form a winding structure. The separator is provided with a first composite area and a second composite area, the first composite area is closer to the winding starting end of the separator than the second composite area in the winding direction, the surface of at least one side of the first composite area and the surface of at least one side of the second composite area are compounded with heat-resistant layers, and the thickness of the heat-resistant layers of the first composite area is smaller than that of the heat-resistant layers of the second composite area. The scheme can more economically and reliably improve the thermal stability of the battery.

Third aspect an embodiment of the present application provides a battery, including a box and a battery cell provided in the second aspect of the present application; the battery monomer is held in the box.

Fourth aspect an embodiment of the present application provides an electric device, including the battery provided in the third aspect of the present application.

The electrode assembly provided by the application comprises a first pole piece, a second pole piece and a spacer, wherein the first pole piece, the second pole piece and the spacer are wound along the winding direction to form a winding structure, and the spacer is arranged between the first pole piece and the second pole piece. The separator is provided with a first composite area and a second composite area, the first composite area is closer to the winding starting end of the separator than the second composite area in the winding direction, the surface of at least one side of the first composite area and the surface of at least one side of the second composite area are compounded with heat-resistant layers, and the maximum thickness of the heat-resistant layers of the first composite area is smaller than the minimum thickness of the heat-resistant layers of the second composite area. Through the scheme, the thermal stability of the battery is improved more economically and reliably.

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 a person skilled in the art to obtain other drawings based on the drawings without any creative effort.

FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;

fig. 2 is a schematic structural diagram of a battery provided in some embodiments of the present application;

fig. 3 is a schematic structural view of a battery module according to some embodiments of the present disclosure;

fig. 4 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

FIG. 5 is a schematic structural view of an electrode assembly provided in accordance with certain embodiments of the present application;

fig. 6 is a view illustrating a structure in which a separator is spread in an electrode assembly;

FIG. 7 is a schematic view of an electrode assembly according to further embodiments of the present application;

FIG. 8 is another structural view illustrating the development of a separator in the electrode assembly;

in the drawings, the drawings are not necessarily to scale.

Description of the labeling: 10-a box body; 11-a first part; 12-a second part; 13-a containment chamber; 20-a battery module; 30-a battery cell; 31-a housing; 40-an electrode assembly; a first pole piece-41; a second pole piece-42; a spacer-43; a first recombination zone-431; a second composite region-432; sub-recombination zone-433; a heat resistant layer-44; -Z in the winding direction; 100-a battery; 1000-vehicle.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

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 in the description of the application in the present application 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. The terms "first," "second," and the like in the description and claims of this application or in the above-described drawings are used for distinguishing between different elements and not for describing a particular sequential or chronological order.

Reference in the specification 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 specification. 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.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "attached" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In the embodiments of the present application, like reference numerals denote like parts, and a detailed description of the same parts is omitted in different embodiments for the sake of brevity. It should be understood that the thickness, length, width and other dimensions of the various components in the embodiments of the present application and the overall thickness, length, width and other dimensions of the integrated device shown in the drawings are only exemplary and should not constitute any limitation to the present application.

The appearances of "a plurality" in this application are intended to mean more than two (including two).

In the present application, the battery cell may include a lithium ion secondary battery, a lithium ion primary battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, a magnesium ion battery, or the like, which is not limited in the embodiments of the present application. The battery cell may be a cylinder, a flat body, a rectangular parallelepiped, or other shapes, which is not limited in the embodiments of the present application. The battery cells are generally divided into three types in an encapsulation manner: the cylindrical battery monomer, the square battery monomer and the soft package battery monomer are not limited in the embodiment of the application.

Reference to a battery in embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, etc. Batteries generally 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.

The battery monomer comprises an electrode assembly and electrolyte, wherein the electrode assembly comprises a positive pole piece, a negative pole piece and a separator. The battery cell mainly depends on metal ions to move between the positive pole piece and the negative pole piece to work. The positive pole piece includes anodal mass flow body and anodal active substance layer, and anodal active substance layer coats in anodal mass flow body's surface, and the anodal mass flow body protrusion in the anodal mass flow body that has coated anodal active substance layer of uncoated anodal active substance layer, and the anodal mass flow body that does not coat anodal active substance layer is as anodal utmost point ear. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, or the like. The negative pole piece includes negative pole mass flow body and negative pole active substance layer, and the negative pole active substance layer coats in the surface of negative pole mass flow body, and the negative pole mass flow body protrusion in the negative pole mass flow body of coating the negative pole active substance layer not coating the negative pole active substance layer, and the negative pole mass flow body of not coating the negative pole active substance layer is as negative pole utmost point ear. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the fuse is not fused when a large current is passed, the number of the positive electrode tabs is multiple and the positive electrode tabs are stacked together, and the number of the negative electrode tabs is multiple and the negative electrode tabs are stacked together. The base film material of the separator may be PP (polypropylene) or PE (polyethylene), etc.

When the battery has faults such as short circuit, the temperature of the battery may be continuously increased, and when the temperature reaches a certain value, the separator starts to deform, so that the positive and negative pole pieces may contact with each other to cause short circuit. In order to improve the thermal stability of the battery, a separator having a heat resistant layer is generally used. However, the thicker the heat-resistant layer thickness is, the higher the manufacturing cost is; the thinner the heat-resistant layer thickness is, the worse the heat-resistant property is. The prior designs have difficulty in economically and reliably improving the thermal stability of the electrode assembly.

The inventors have recognized that when the temperature of one electrode assembly or battery cell increases, the heat is transferred to the outside of the other electrode assemblies or battery cells and then to the inside of the electrode assemblies or battery cells through contact.

In order to meet the requirements of balancing cost and heat resistance, according to the heat transfer path, the inventor provides an electrode assembly, a battery cell, a battery and an electric device, wherein the electrode assembly comprises a first pole piece, a second pole piece and a separator, and is wound along a winding direction to form a winding structure, and the separator is arranged between the first pole piece and the second pole piece. The separator is provided with a first composite area and a second composite area, the first composite area is closer to the winding starting end of the separator than the second composite area in the winding direction, the surface of at least one side of the first composite area and the surface of at least one side of the second composite area are compounded with heat-resistant layers, and the maximum thickness of the heat-resistant layers of the first composite area is smaller than the minimum thickness of the heat-resistant layers of the second composite area. The scheme is more economical and reliable, and the thermal stability of the battery is improved.

The technical scheme described in the embodiment of the application is suitable for the battery and the electric equipment using the battery.

The electric equipment can be vehicles, mobile phones, portable equipment, notebook computers, ships, spacecrafts, electric toys, electric tools and the like. The vehicle can be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle and the like; spacecraft include aircraft, rockets, space shuttles, and spacecraft, among others; electric toys include stationary or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric airplane toys, and the like; the electric power tools include metal cutting electric power tools, grinding electric power tools, assembly electric power tools, and electric power tools for railways, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planers. The embodiment of the present application does not specifically limit the above-mentioned electric devices.

For convenience of explanation, the following embodiments will be described by taking an electric device as an example of a vehicle.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present disclosure, a battery 100 is disposed inside the vehicle 1000, and the battery 100 may be disposed at a bottom portion or a head portion or a tail portion 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.

In some embodiments of the present application, the battery 100 may be used not only as an operating power source of the vehicle 1000, but also 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, referring to fig. 2, fig. 2 is a schematic structural diagram of a battery 100 disclosed in some embodiments of the present application, where the battery 100 includes a case 10 and a battery module 20, and the case 10 is used for accommodating the battery module 20.

The case 10 may include a first portion 11 and a second portion 12, and the first portion 11 and the second portion 12 cover each other to define a receiving cavity 13 for receiving the battery cell 30. The first and second portions 11 and 12 may be in various shapes, such as rectangular parallelepiped, cylindrical, etc. The first portion 11 may be a hollow structure with one side open, the second portion 12 may also be a hollow structure with one side open, and the open side of the second portion 12 is covered on the open side of the first portion 11, so as to form the box body 10 with the accommodating cavity 13. As shown in fig. 2, the first portion 11 may have a hollow structure with one side open, the second portion 12 may have a plate-like structure, and the second portion 12 may cover the open side of the first portion 11 to form the case 10 having the housing chamber 13. Illustratively, in fig. 2, the first portion 11 and the second portion 12 are each a rectangular parallelepiped structure.

The first portion 11 and the second portion 12 may be sealed by a sealing element, which may be a sealing ring, a sealant, or the like.

In the battery 100, one or more battery cells 30 may be provided. If there are a plurality of battery cells 30, the plurality of battery cells 30 may be connected in series, in parallel, or in series-parallel, where in series-parallel refers to that the plurality of battery cells 30 are connected in series or in parallel. The battery modules 20 may be formed by connecting a plurality of battery cells 30 in series, in parallel, or in series-parallel, and the plurality of battery modules 20 are connected in series, in parallel, or in series-parallel to form a whole and are accommodated in the case 10. Or all the battery cells 30 may be directly connected in series or in parallel or in series-parallel, and the whole of all the battery cells 30 is accommodated in the case 10.

Referring to fig. 3, fig. 3 is a schematic structural view of a battery module 20 disclosed in some embodiments of the present application, where the battery module 20 includes a battery cell 30. One or more battery cells 30 may be provided.

Referring to fig. 4, fig. 4 is a schematic structural diagram of a battery cell 30 disclosed in some embodiments of the present application. The battery cell 30 includes a case 31, an end cap, and an electrode assembly 40.

The case 31 has an opening, and the case 31 serves to receive the electrode assembly 40. The material of the housing 31 may be aluminum, steel, aluminum alloy, etc., and is not particularly limited herein. The shape of the housing 31 may be cylindrical, square, etc., and is not particularly limited thereto. Illustratively, referring to fig. 4, the housing 31 is square.

The end cap is used for covering the opening of the shell 31, and the end cap can be made of plastic, aluminum, steel, aluminum alloy and the like. The end cap and the shell 31 can be covered by welding, bonding, clamping and the like.

Referring to fig. 5 and 6, fig. 5 is a schematic structural view of an electrode assembly 40 provided in some embodiments of the present application; fig. 6 is a schematic view showing a structure in which the separator 43 is spread out in the electrode assembly 40. The electrode assembly 40 includes a first pole piece 41, a second pole piece 42, and a separator 43, and is wound in a winding direction Z to form a wound structure, with the separator 43 disposed between the first pole piece 41 and the second pole piece 42. The partition 43 has a first composite area 431 and a second composite area 432, the first composite area 431 is closer to the winding start end of the partition 43 than the second composite area 432 in the winding direction Z, at least one side surface of the first composite area 431 and the second composite area 432 is compounded with the heat-resistant layer 44, and the maximum thickness of the heat-resistant layer 44 of the first composite area 431 is smaller than the minimum thickness of the heat-resistant layer 44 of the second composite area 432.

The first pole piece 41 and the second pole piece 42 have opposite polarities, one of the two is a positive pole piece, and the other is a negative pole piece, for example, referring to fig. 5, the first pole piece 41 is a positive pole piece, and the second pole piece 42 is a negative pole piece. Therefore, for example, the first pole piece 41 includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, the positive electrode current collector which is not coated with the positive electrode active material layer protrudes from the positive electrode current collector which is coated with the positive electrode active material layer, and the positive electrode current collector which is not coated with the positive electrode active material layer serves as a positive electrode tab. The positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate and the like. The second pole piece 42 includes a negative current collector and a negative active substance layer, the negative active substance layer is coated on the surface of the negative current collector, the negative current collector not coated with the negative active substance layer protrudes out of the negative current collector coated with the negative active substance layer, and the negative current collector not coated with the negative active substance layer is used as a negative pole tab. The material of the negative electrode collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the high current can be passed through without fusing, a plurality of positive electrode tabs are stacked together, and a plurality of negative electrode tabs are stacked together.

The separator 43 includes a base film and a composite layer on the base film. The composite layer may be composed of one or more materials, and the composite layer may be used to reinforce the strength of the separator 43, improve the thermal stability of the electrode assembly 40, or improve the storage capacity of the separator 43 for the electrolyte. The composite layer may be polyvinylidene fluoride, ceramic coating, or the like. The base film material may be PP (polypropylene) or PE (polyethylene), etc., and the application does not make any special requirement. The spacer 43 is used to maintain insulation between the first pole piece 41 and the second pole piece 42.

The first pole piece 41, the second pole piece 42, and the separator 43 are wound in the winding direction Z to form a wound structure. Namely, the first pole piece 41, the second pole piece 42 and the spacer 43 are correspondingly overlapped, and are wound around the winding needle from one end to the other end corresponding to the one end, wherein the one end is a winding starting end and is positioned at the innermost circle of the winding structure, and the other end is a winding tail end and is positioned at the outermost circle of the winding structure. The winding direction Z refers to a direction in which winding is performed from the winding start end to the winding end.

The first and second

composite regions

431 and 432 are regions into which the separator 43 is divided in the length direction thereof, and the first composite region 431 is closer to the winding start end than the second composite region 432, so that the first composite region 431 is located at the inner circumference of the winding structure than the second composite region 432 after the winding structure is formed.

Projections of the first composite region 431 and the second composite region 432 in the thickness direction together cover the coated region of the active material layer of the first pole piece 41 or the second pole piece 42.

The heat resistant layer 44 completely covers at least one side of the first composite region 431 and at least one side of the second composite region 432. The heat-resistant layer 44 has better heat-resistant properties than the base film, so the heat-resistant layer 44 can reduce deformation of the separator 43 at an elevated temperature. The heat-resistant layer 44 may be made of one material or a mixture of materials. The heat-resistant layer 44 may be made by mixing ceramic powder, a solvent, a binder, and the like.

According to the embodiment of the present application, the isolating member 43 is disposed between the first pole piece 41 and the second pole piece 42, and is used for isolating the first pole piece 41 from the second pole piece 42, so as to prevent the first pole piece 41 from contacting with the second pole piece 42 to cause a short circuit. The separator 43 has a first composite region 431 and a second composite region 432, and the heat resistant layer 44 is compounded on at least one surface of the first composite region 431 and the second composite region 432, and the heat resistant layer 44 improves the heat resistance of the electrode assembly 40. The risk that the spacer 43 is deformed by heat, causing the first pole piece 41 and the second pole piece 42 to partially contact and cause short circuit, is reduced. The thickness of the heat-resistant layer 44 of the first composite region 431 is smaller than that of the heat-resistant layer 44 of the second composite region 432, so that the heat-resistant performance of the outer ring of the electrode assembly 40 is enhanced, the manufacturing cost of the electrode assembly 40 is reduced, and the energy density of the battery is improved.

Referring to fig. 5 and 6, in the winding direction Z, the first composite zone 431 extends at least to the winding start of the first pole piece 41 or the second pole piece 42, and the second composite zone 432 extends at least to the winding end of the first pole piece 41 or the second pole piece 42.

The first compound region 431 at least extends to the winding start end of the first pole piece 41 or the second pole piece 42 means that when the first pole piece 41 is a negative pole piece, the first compound region 431 extends to the winding start end of the first pole piece 41 or exceeds the winding start end of the first pole piece 41. When the second pole piece 42 is a negative pole piece, the first compound region 431 extends to the winding start end of the second pole piece 42 or exceeds the winding start end of the second pole piece 42.

The second composite region 432 extending at least to the winding end of the first pole piece 41 or the second pole piece 42 means that when the first pole piece 41 is a negative pole piece, the second composite region 432 extends to the winding end of the first pole piece 41 or beyond the winding end of the first pole piece 41. When the second pole piece 42 is a negative pole piece, the second composite region 432 extends to or beyond the winding end of the second pole piece 42.

According to the embodiment of the present application, the first composite region 431 extends to the winding start end of the first pole piece 41 or the second pole piece 42, and the second composite region 432 extends at least to the winding end of the first pole piece 41 or the second pole piece 42, so that the heat-resistant layer 44 is provided at the projection overlapping part of the spacer 43 in the thickness direction of the first pole piece 41 and the second pole piece 42, and the possibility of keeping the first pole piece 41 and the second pole piece 42 isolated at high temperature is further improved.

Referring to fig. 5 and 6, the heat-resistant layer 44 of the first and second

composite zones

431 and 432 continuously increases in thickness in the winding direction Z.

The heat-resistant layer 44 continuously increases in thickness means that the heat-resistant layer 44 becomes thicker as it comes closer to the winding end in the winding direction Z.

According to the embodiment of the application, the thickness of the heat-resistant layer 44 is continuously increased in the winding direction Z, so that after the winding structure is hot-pressed, the first pole piece 41, the spacer 43 and the second pole piece 42 are tightly attached to each other, and the energy density of the battery is further improved.

Referring to fig. 6 and 7, fig. 7 is a schematic structural view of an electrode assembly 40 according to another embodiment of the present application, in which the second composite region 432 partially extends beyond the winding end of the first pole piece 41 or the second pole piece 42 and partially surrounds the electrode assembly 40 for at least one circle in the winding direction Z.

Illustratively, in fig. 7, the excess portion surrounds the electrode assembly 40 in the winding direction for one revolution. In practical applications, the length of the excess portion may be increased as necessary to enhance the heat insulating ability of the electrode assembly 40.

According to the embodiment of the present application, since the heat-resistant layer 44 has a certain thermal insulation effect, the portion of the second composite region 432, which exceeds the first pole piece 41 or the second pole piece 42, surrounds the electrode assembly 40 for at least one circle, which plays a certain role in hindering heat from being transferred from the failed electrode assembly 40 to the surrounding electrode assembly 40, thereby delaying heat spreading and improving the safety performance of the battery.

Referring to fig. 8, fig. 8 is another structural view illustrating the expansion of the separator 43 in the electrode assembly 40. The first composite region 431 and the second composite region 432 each have a plurality of sub-composite regions 433, the heat resistant layer 44 of each sub-composite region 433 has a uniform thickness, and the heat resistant layers 44 of the plurality of sub-composite regions 433 have increasing thicknesses in the winding direction Z.

Plural means two or more. The first recombination zone 431 and the second recombination zone 432 may have the same or different number of sub-recombination zones 433. The length of each sub-composite region 433 may be the same or different, and for example, referring to FIG. 8, the length of each sub-composite region 433 is the same.

The uniform thickness of the heat resistant layer 44 in each sub-composite zone 433 means that the thickness is the same throughout the individual sub-composite zones 433.

The plurality of sub-composite regions 433 are arranged in series along the winding direction Z, and the thickness between the plurality of sub-composite regions 433 increases, i.e., the thickness of the heat resistant layer 44 increases as the sub-composite regions 433 closer to the winding end. The difference in thickness of the heat resistant layer 44 between adjacent sub-composite regions 433 may be the same or different, and illustratively, as shown in FIG. 8, the greater the difference in thickness of the heat resistant layer 44 between adjacent sub-composite regions 433 closer to the winding end.

According to the embodiment of the application, the thickness of the heat-resistant layer 44 in each sub-composite area 433 is unchanged, the processing difficulty of compounding the heat-resistant layer 44 and the isolating piece 43 is reduced, and the production efficiency is improved. The heat-resistant layer 44 of the plurality of sub-composite regions 433 has an increasing thickness in the winding direction Z, so that the heat-resistant property of the heat-resistant layer 44 is gradually enhanced in the winding direction Z.

Referring to fig. 7 and 8, the second composite region 432 is composited with heat resistant layers 44 on both sides.

The two sides of the second composite region 432 refer to the contact surfaces of the second composite region 432 with the first and

second pole pieces

41 and 42.

The heat-resistant layer 44 and the base film may be combined by spin coating, gravure coating, or the like. According to the actual production condition, a specific compounding mode is selected, and no special requirement is made here.

According to the embodiment of the present application, the heat-resistant layer 44 is combined on both sides of the second combining region 432, so that the heat resistance of the outer ring of the electrode assembly 40 is further improved, and the heat transfer to the inner ring of the electrode assembly 40 is hindered to some extent.

In some embodiments, the heat resistant layer 44 is a ceramic layer.

The ceramic layer is not limited to only one ceramic material, and the ceramic layer can be prepared by mixing ceramic powder, a solvent, a binder and the like according to a certain proportion. The specific mixing ratio is not particularly limited in the present application.

According to the embodiment of the present application, the ceramic layer has good heat resistance, is resistant to electrolyte, and is not easily combusted, so that the ceramic layer can prevent the deformation of the separator 43 to some extent when the temperature of the battery rises.

In some embodiments, the ceramic layer on the spacers 43 has a thickness D, 0.75 μm D3 μm.

Alternatively, D may be 1 μm, 1.5 μm, 2 μm, 2.5 μm, etc., and is designed and manufactured according to the thickness requirement of each region in actual production.

On the premise that other factors are not changed, the larger the thickness of the ceramic layer is, the better the heat resistance of the electrode assembly 40 is, and the higher the manufacturing cost is. According to the requirements of heat resistance and manufacturing cost of products, the minimum thickness of the ceramic layer is not less than 0.75 μm, and the maximum thickness of the ceramic layer is not more than 3 μm.

According to the embodiment of the application, the ceramic layer is designed to have different thicknesses in different areas according to requirements, so that the heat resistance of the electrode assembly 40 is improved, and meanwhile, the cost waste and the loss of energy density are reduced.

Referring to fig. 6 and 7, in some embodiments, the electrode assembly 40 includes a first pole piece 41, a second pole piece 42, and a separator 43, and is wound in a winding direction Z to form a wound structure, with the separator 43 disposed between the first pole piece 41 and the second pole piece 42. The partition 43 has a first composite region 431 and a second composite region 432, the first composite region 431 is closer to the winding start end of the partition 43 than the second composite region 432 in the winding direction Z, at least one side surface of the first composite region 431 and the second composite region 432 is compounded with the heat-resistant layer 44, and the maximum thickness of the heat-resistant layer 44 of the first composite region 431 is smaller than the minimum thickness of the heat-resistant layer 44 of the second composite region 432. In the winding direction Z, the second composite region 432 partially extends beyond the winding end of the first pole piece 41 or the second pole piece 42, and the extending portion surrounds the electrode assembly 40 for at least one circle. The heat-resistant layer 44 of each of the first composite region 431 and the second composite region 432 continuously increases in thickness in the winding direction Z. Wherein, the heat-resistant layers 44 are compounded on both sides of the second compound area 432, the heat-resistant layers 44 are ceramic layers, and the thickness D is within the range of 0.75 mu m and less than or equal to D and less than or equal to 3 mu m.

Referring to fig. 7 and 8, in some embodiments, the electrode assembly 40 includes a first pole piece 41, a second pole piece 42, and a separator 43, and is wound in a winding direction Z to form a wound structure, with the separator 43 disposed between the first pole piece 41 and the second pole piece 42. The partition 43 has a first composite region 431 and a second composite region 432, the first composite region 431 is closer to the winding start end of the partition 43 than the second composite region 432 in the winding direction Z, at least one side surface of the first composite region 431 and the second composite region 432 is compounded with the heat-resistant layer 44, and the maximum thickness of the heat-resistant layer 44 of the first composite region 431 is smaller than the minimum thickness of the heat-resistant layer 44 of the second composite region 432. In the winding direction Z, the second composite region 432 partially extends beyond the winding end of the first pole piece 41 or the second pole piece 42 and partially surrounds the electrode assembly 40 for at least one turn. The first composite region 431 and the second composite region 432 are both provided with a plurality of sub-composite regions 433, the heat-resistant layer 44 of each sub-composite region 433 is uniform in thickness, the thickness of the heat-resistant layer 44 of the sub-composite regions 433 is gradually increased in the winding direction Z, the heat-resistant layer 44 is a ceramic layer, and the thickness D is within the range of 0.75 mu m or more and D or less and 3 mu m or less.

While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. The present application is not intended to be limited to the particular embodiments disclosed herein, but rather to cover all embodiments falling within the scope of the appended claims.

Claims

1. An electrode assembly comprising a first pole piece, a second pole piece, and a separator, and wound in a winding direction to form a wound structure, the separator being disposed between the first pole piece and the second pole piece;

the separator is provided with a first composite area and a second composite area, the first composite area is closer to the winding starting end of the separator than the second composite area in the winding direction, a heat-resistant layer is compounded on at least one side surface of the first composite area and the second composite area, and the maximum thickness of the heat-resistant layer of the first composite area is smaller than the minimum thickness of the heat-resistant layer of the second composite area.

2. The electrode assembly of claim 1, wherein the first composite region extends at least to a winding start end of the first or second pole piece and the second composite region extends at least to a winding end of the first or second pole piece in the winding direction.

3. The electrode assembly of claim 2, wherein the second composite region partially extends beyond the winding end of the first or second pole piece in the winding direction and the extending portion surrounds the electrode assembly for at least one revolution.

4. The electrode assembly of any of claims 1-3, wherein the first composite zone and the second composite zone each have a plurality of sub-composite zones, each having a uniform heat resistance layer thickness, the heat resistance layers of the plurality of sub-composite zones increasing in thickness in the winding direction.

5. The electrode assembly according to any one of claims 1 to 3, wherein the heat-resistant layer thickness of each of the first composite zone and the second composite zone continuously increases in the winding direction.

6. The electrode assembly of claim 1, wherein said heat resistant layer is laminated to both sides of said second composite region.

7. The electrode assembly of claim 1, wherein the heat resistant layer is a ceramic layer.

8. The electrode assembly of claim 7, wherein the ceramic layer has a thickness D, 0.75 μm D3 μm.

9. A battery cell comprising a case and the electrode assembly according to any one of claims 1-8; the electrode assembly is housed within the case.

10. A battery comprising a case and the battery cell of claim 9; the battery unit is accommodated in the box body.

11. An electrical device comprising the battery of claim 10.