CN219017742U - Electrode assembly, battery cell, battery and electric equipment - Google Patents

Abstract

The application is applicable to the power battery technology field, proposes an electrode assembly, battery cell, battery and consumer, and electrode assembly includes: the lamination part comprises a first cathode plate, a first anode plate and a first isolating film arranged between the first cathode plate and the first anode plate, wherein at least one of the first cathode plate and the first anode plate is of a discontinuous structure and comprises at least two sections of active material parts which are arranged in a lamination way; and the winding part is coated outside the lamination part and comprises a second wound cathode piece, a second anode piece and a second isolating film arranged between the second cathode piece and the second anode piece. The electrode assembly provided by the embodiment of the application can solve the problems of falling off, brittle fracture, cracking and lithium precipitation of active substances in the electrode plate at the corner of the electrode assembly.

Description

Electrode assembly, battery cell, battery and electric equipment

Technical Field

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

Background

Energy conservation and emission reduction are key to sustainable development of the automobile industry, and electric vehicles become an important component of sustainable development of the automobile industry due to the energy conservation and environmental protection advantages of the electric vehicles. For electric vehicles, battery technology is an important factor in the development of the electric vehicles.

Lithium batteries used in electric vehicles are commonly referred to as power batteries. The battery cells in a power cell typically include a housing, an electrode assembly, and an electrolyte, both of which are sealed within the housing, with the wound form being one common form in the design of the electrode assembly. However, in some cases, the curvature of the pole piece at the corner of the inner ring of the electrode assembly is large, so that the problem of overlarge stress is caused, the problem that the pole piece at the corner is easy to fall off and brittle fracture of active substances is caused, and lithium precipitation is even caused.

Disclosure of Invention

In view of this, the embodiment of the application provides an electrode assembly, a battery monomer, a battery and electric equipment, and the electrode assembly corner pole piece has the problem that active material drops, brittle fracture and lithium precipitation exist can be improved.

Embodiments of the present application provide an electrode assembly comprising:

the lamination part comprises a first cathode plate, a first anode plate and a first isolating film arranged between the first cathode plate and the first anode plate, wherein at least one of the first cathode plate and the first anode plate is of a discontinuous structure and comprises at least two sections of lamination-arranged pole plate parts;

the winding part is coated outside the lamination part and comprises a second cathode plate, a second anode plate and a second isolating film, wherein the second cathode plate and the second anode plate are wound, and the second isolating film is arranged between the second cathode plate and the second anode plate.

The electrode assembly comprises a lamination part and a winding part, wherein the winding part is coated outside the lamination part, namely the lamination part is arranged in the innermost ring of the winding part; in lamination portion, at least one of first negative pole piece and first positive pole piece is discontinuous structure and includes the pole piece portion that at least two sections range upon range of setting, in the pole piece of discontinuous structure, the interval between two sections active material portions can correspond electrode assembly's corner to the active material portion can avoid the corner, has alleviated the problem that takes place pole piece to fall powder, brittle failure fracture because of the radian is great in the corner, and the active material portion avoids the corner, can also prevent to lead to because of the CB value of corner is less the lithium problem that separates. In addition, the electrode assembly provided by the embodiment of the application can ensure that the corner of the winding part has a larger curvature radius and is not easy to fall off powder, and meanwhile, the lamination part is arranged in the winding part, so that the energy and the capacity are considered, the material use is reduced, and the performance of the electrode assembly is improved.

In some embodiments, the first cathode sheet is a discontinuous structure and the first anode sheet is a continuous structure or a discontinuous structure.

By adopting the technical scheme, at least the first cathode plate of the lamination part is designed to be of a discontinuous structure, so that part of the area of the first cathode plate avoids the corner, the quantity of lithium ions which can be extracted from the first cathode plate positioned at the corner is obviously reduced, and the problem of lithium precipitation at the corner is relieved; the first anode sheet can be arranged into a continuous structure or a discontinuous structure according to requirements.

In some embodiments, the electrode assembly includes a flat region and corner regions at both ends of the flat region, and a plurality of segments of the active material portion are stacked in the flat region.

Through adopting above-mentioned technical scheme, multistage active material portion is in the setting of flat district inlayed, can realize avoiding the turning district with active material portion to alleviate the pole piece at corner and fall powder, brittle failure fracture and break out lithium problem.

In some embodiments, the pole piece portions of the first cathode piece are each located in the flat region.

Through adopting above-mentioned technical scheme, the pole piece portion of first negative pole piece all is located flat district, and then first negative pole piece adopts lamination structure's design mode, can promote electrode assembly's energy and capacity, and alleviates first negative pole piece and exist at the corner and fall powder, brittle failure fracture and deposit lithium problem even.

In some embodiments, the first anode sheet is a continuous structure, and the first anode sheet includes a plurality of stacked portions and bent portions that are alternately arranged, wherein the stacked portions are stacked in the flat region, and each bent portion connects two stacked portions and is located in the corner region;

the active material portion of the first cathode sheet is located between the two laminated portions along the lamination direction of the laminated portions.

By adopting the technical scheme, in the lamination part, only the first cathode sheet is arranged to be of a discontinuous structure, so that the problems of pole piece powder falling and brittle fracture and cracking of the first cathode sheet can be solved; meanwhile, the problems of small CB value and lithium precipitation in the inner ring of the electrode assembly can be relieved.

In some embodiments, the plurality of segments of the active material portion in the first cathode sheet include a first active material portion extending only within the straight region and a second active material portion extending in both the straight region and the corner region.

Through adopting above-mentioned technical scheme, first negative pole piece can include a plurality of discontinuous active material portions, and lamination portion can be designed to lamination and coiling mode of arbitrary combination, as long as along the vacancy portion between two adjacent active material portions of coiling direction corresponds the corner district, all can alleviate first negative pole piece and take place brittle failure fracture, fall powder and even the problem of lithium analysis in the corner district.

In some embodiments, the first anode sheet is a continuous structure, and the first anode sheet includes a plurality of stacked portions and bent portions that are alternately arranged, wherein the stacked portions are stacked in the flat region, and each bent portion connects two stacked portions and is located in the corner region;

Along a lamination direction of the lamination portions, the first active material portion is located between the lamination portions of two lamination, and a portion of the second active material portion is located between the lamination portions of two lamination; the remaining portion of the second active material portion is located between the two stacked bent portions along the stacking direction of the bent portions.

By adopting the technical scheme, the lamination part can be designed into a mode of any combination of lamination and winding, and the first anode sheet can be designed into a continuous structure; the first active material part avoids the corner area, so that the problems of brittle failure, cracking, powder falling and even lithium precipitation of the first cathode plate in the corner area can be relieved; only part of the active material is positioned in the corner area, so that the gap between the pole pieces is increased, and the wettability of the pole pieces is improved.

In some embodiments, the corners of the first anode sheet and/or the first separator in a continuous structure are in an arc-shaped or dog-ear structure.

Through adopting above-mentioned technical scheme, the form of lamination portion has multiple choice, and first anode plate, first barrier film can set up the turning into arc or dog-ear structure, has higher system Cheng Ling activity to promote manufacturing efficiency.

In some embodiments, the compacted density of the first anode sheet is less than the compacted density of the second anode sheet; and/or

The compacted density of the first cathode sheet is less than the compacted density of the second cathode sheet.

By adopting the technical scheme, the compaction density of the pole pieces in the lamination part is smaller than that of the pole pieces in the winding part, so that the wettability of the first cathode piece and the first anode piece can be increased, and the probability of wrinkling of the inner ring is reduced.

In some embodiments, the first and second cathode sheets each include a cathode current collector and a cathode active material disposed on at least one side of the cathode current collector, at least one of the following characteristics of the first and second cathode sheets being different: the compacted density, the coating weight of the cathode active material per unit area, the material of the cathode active material, the material of the cathode current collector;

the first anode sheet and the second anode sheet comprise anode current collectors and anode active materials arranged on at least one surface of the anode current collectors, and at least one of the following characteristics in the first anode sheet and the second anode sheet is different: the density of compaction, the coating weight of the anode active material per unit area, the material of the anode active material, the material of the anode current collector.

Through adopting above-mentioned technical scheme, the pole piece parameter in lamination portion and the coiling portion can set up according to the design requirement respectively to satisfy different demands, the flexibility is better.

In some embodiments, the first cathode sheet includes a cathode current collector and a cathode active material disposed on at least one side of the cathode current collector, and the first anode sheet and the second anode sheet each include an anode current collector and an anode active material disposed on at least one side of the anode current collector;

wherein the cathode current collector of the first cathode plate is of a continuous structure and the cathode active material is discontinuously distributed on the cathode current collector; and/or the number of the groups of groups,

the anode current collector of the first anode sheet is of a continuous structure and the anode active material is discontinuously distributed on the anode current collector.

Through adopting above-mentioned technical scheme, to the pole piece of discontinuous structure, the active material in the pole piece is divided into the part that a plurality of intervals set up, and the electric current collector of pole piece can keep continuous, and the wholeness of pole piece is better to can make electrode assembly's lamination portion through the mode of coiling, convenient preparation.

In some embodiments, the first cathode sheet includes a cathode current collector and a cathode active material disposed on at least one side of the cathode current collector, and the first anode sheet and the second anode sheet each include an anode current collector and an anode active material disposed on at least one side of the anode current collector;

Wherein, the cathode current collector of the first cathode plate and the cathode active material are both in a discontinuous structure; and/or the number of the groups of groups,

the anode current collector of the first anode sheet and the anode active material are both discontinuous structures.

By adopting the technical scheme, the pole piece is divided into a plurality of sections of structures which are completely disconnected, so that the problems of falling off of active substances, brittle fracture, cracking and lithium precipitation of pole pieces at corners of the electrode assembly are solved.

Embodiments of the second aspect of the present application provide a battery cell comprising an electrode assembly as described in the first aspect.

Embodiments of the third aspect of the present application provide a battery comprising the battery cell of the second aspect.

Embodiments of a fourth aspect of the present application provide a powered device comprising a battery as provided in the third aspect.

The electrode assembly, the battery monomer, the battery and the electric equipment provided by the application can improve the problems that the pole piece falls powder and brittle failure cracks occur at the corner because of the radian is large, and the pole piece avoids the corner, so that the lithium precipitation problem caused by the small CB value at the corner can be prevented. Meanwhile, the electrode assembly provided by the application can ensure that the corner of the winding part has larger curvature radius and is not easy to fall off powder, and meanwhile, the lamination part is arranged in the winding part, so that the material use is reduced, the performance of the electrode assembly is improved, the service life of a battery is prolonged, and the safety performance of the battery is improved while the energy and the capacity are considered.

The foregoing description is only an overview of the technical solutions of the present application, and may be implemented according to the content of the specification in order to make the technical means of the present application more clearly understood, and in order to make the above-mentioned and other objects, features and advantages of the present application more clearly understood, the following detailed description of the present application will be given.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the description of the embodiments or the conventional technology will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.

FIG. 1 is a schematic view of a vehicle according to an embodiment of the present application;

fig. 2 is a schematic view showing an exploded structure of a battery according to an embodiment of the present application;

FIG. 3 is a schematic view of an electrode assembly according to an embodiment of the present application;

fig. 4 is a schematic structural view of a lamination part in the electrode assembly shown in fig. 3;

fig. 5 is a schematic structural view of an electrode assembly according to another embodiment of the present application;

fig. 6 is a schematic structural view of a lamination part in the electrode assembly shown in fig. 5;

Fig. 7 is a schematic structural view of an electrode assembly according to still another embodiment of the present application;

fig. 8 is a schematic structural view of a lamination part in the electrode assembly shown in fig. 7;

FIG. 9 is a schematic structural view of a lamination portion provided in an embodiment of the present application;

fig. 10 is a schematic structural view of a lamination portion provided in another embodiment of the present application;

fig. 11 is a schematic structural view of a lamination portion according to still another embodiment of the present application.

The meaning of the labels in the figures is:

1000. a vehicle;

100. a battery; 20. a battery cell; 10. a case; 11. a first portion; 12. a second portion;

21. an electrode assembly; 21a, a flat region; 22a, corner regions;

211. a lamination part; 2111. a first cathode sheet; 2112. a first anode sheet; 21121. a lamination section; 21122. a bending portion; 2113. a first separation film; 201. a cathode active material portion; 201a, a first active material portion; 201b, a second active material portion; 202. an anode active material portion;

212. a winding part; 2121. a second cathode sheet; 2122. a second anode sheet; 2123. and a second isolation film.

Detailed Description

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection 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 herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description and claims of the present application and in the description of the figures above are intended to cover non-exclusive inclusions.

In the description of the embodiments of the present application, the technical terms "first," "second," etc. are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases 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. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, which means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

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

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are orientation or positional relationship based on the drawings, and are merely for convenience of describing the embodiments of the present application and simplifying the description, and are not intended to indicate or imply that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

The battery cells in a power cell typically include a housing, an electrode assembly, and an electrolyte, both of which are sealed within the housing, with the wound form being one common form in the design of the electrode assembly.

The inventor researches find that for the coiled electrode assembly, the coiled electrode assembly is flattened when the coiled electrode assembly is assembled into a shell, the pole piece at the corner of the inner ring of the electrode assembly is excessively bent and has larger curvature, and the problem of overlarge stress at the corner exists, so that the performance of the electrode assembly is reduced, for example, the problems of active material falling and brittle fracture cracking of the pole piece at the corner occur after the pole piece is extruded for a long time, and lithium precipitation is even caused.

In the charging process of the lithium ion battery, lithium ions can be deintercalated from the cathode and intercalated into the anode, but when some abnormal conditions occur and cause that the lithium ions deintercalated from the cathode cannot be intercalated into the anode, the lithium ions can only be separated out on the surface of the anode to form a layer of gray substance, which is called lithium precipitation. The lithium separation at the corners directly affects the cycle life of the battery, and the malignant cycle brings about a great potential safety hazard to the battery.

In order to solve the problems, the inventor has conducted intensive studies and devised an electrode assembly, a battery cell, a battery and electric equipment. The electrode assembly comprises a lamination part and a winding part wrapping the outside of the lamination part, wherein the lamination part and the winding part comprise a cathode plate, an anode plate and a separation film for separating the cathode plate and the anode plate; at least one of the cathode sheet and the anode sheet in the lamination part is of a discontinuous structure and is divided into at least two sections of pole sheet parts at intervals in the winding direction, so that the winding part is positioned at the outer ring part of the electrode assembly, the lamination part is positioned at the inner ring part of the electrode assembly, and the pole sheet can avoid the corner of the electrode assembly due to the fact that at least one pole sheet of the lamination part is of a discontinuous structure, and the problems of powder falling, brittle fracture cracking and lithium precipitation of the pole sheet at the corner are solved.

The electrode assembly and the battery cell disclosed by the embodiment of the application can be used for electric equipment using a battery as a power supply or various energy storage systems using the battery as an energy storage element. The powered device may be, but is not limited to, a cell 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. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

For convenience of description, the following embodiments take a powered device according to an embodiment of the present application as an example of the vehicle 1000.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or a range-extended vehicle. The battery 100 is provided in the interior of 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 be used as an operating power source of the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, the controller 200 being configured to control the battery 100 to power the motor 300, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1000.

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

Referring to fig. 2, fig. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 includes a case 10 and a battery cell 20, and the battery cell 20 is accommodated in the case 10. The case 10 is used to provide an accommodating space for the battery cell 20, and the case 10 may have various structures. In some embodiments, the case 10 may include a first portion 11 and a second portion 12, the first portion 11 and the second portion 12 being overlapped with each other, the first portion 11 and the second portion 12 together defining an accommodating space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one end opened, the first portion 11 may be a plate-shaped structure, and the first portion 11 covers the opening side of the second portion 12, so that the first portion 11 and the second portion 12 together define a containing space; the first portion 11 and the second portion 12 may be hollow structures each having an opening at one side, and the opening side of the first portion 11 is engaged with the opening side of the second portion 12. Of course, the case 10 formed by the first portion 11 and the second portion 12 may be of various shapes, such as a cylinder, a rectangular parallelepiped, or the like.

In the battery 100, the plurality of battery cells 20 may be connected in series, parallel or a series-parallel connection, wherein the series-parallel connection refers to that the plurality of battery cells 20 are connected in series or parallel. The plurality of battery cells 20 can be directly connected in series or in parallel or in series-parallel, and then the whole formed by the plurality of battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting a plurality of battery cells 20 in series or parallel or series-parallel connection, and a plurality of battery modules are then connected in series or parallel or series-parallel connection to form a whole and are accommodated in the case 10. The battery 100 may further include other structures, for example, the battery 100 may further include a bus member for making electrical connection between the plurality of battery cells 20.

Wherein each battery cell 20 may be a secondary battery or a primary battery; but not limited to, lithium sulfur batteries, sodium ion batteries, or magnesium ion batteries. The battery cell 20 may be in the shape of a cylinder, a flat body, a rectangular parallelepiped, or other shapes, etc.

The battery cell 20 refers to the smallest unit constituting the battery, and the battery cell 20 includes a case, an electrode assembly, and an electrolyte, both of which are contained in the case. The outer case may include a case having an opening and an end cap covering the opening of the case to isolate the inner environment of the battery cell from the outer environment. The end cap may be provided with a functional part such as an electrode terminal or the like. The electrode terminal may be further provided with a pressure release mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell reaches a threshold value. The housing may be of various shapes and sizes, such as rectangular parallelepiped, cylindrical, hexagonal prism, etc.; the material of the housing may be a variety of metals such as, but not limited to, copper, iron, aluminum, stainless steel, aluminum alloys, and the like.

The electrode assembly is a component in which electrochemical reactions occur in the battery cell 20. One or more electrode assemblies may be contained within the case.

Embodiments of the first aspect of the present application provide an electrode assembly. Referring to fig. 3 and 4, the electrode assembly 21 includes a lamination part 211 and a winding part 212 coated outside the lamination part 211.

The lamination portion 211 includes a first cathode sheet 2111, a first anode sheet 2112, and a first separator 2113 provided between the first cathode sheet 2111 and the first anode sheet 2112, at least one of the first cathode sheet 2111 and the first anode sheet 2112 being of a discontinuous structure and including at least two sections of active material portions stacked.

The winding part 212 includes a second cathode sheet 2121, a second anode sheet 2122, and a second separator 2123 provided between the second cathode sheet 2121 and the second anode sheet 2122, which are wound.

The battery monomer mainly depends on metal ions to move between the cathode plate and the anode plate to work, and the isolating film is an insulating film and is used for isolating the cathode plate and the anode plate and preventing the cathode plate and the anode plate from being short-circuited; the material of the first and second separation films 2113 and 2123 may be PP (polypropylene), PE (polyethylene), or the like.

The cathode sheet (also called as positive electrode sheet) comprises a cathode current collector and cathode active substances arranged on at least one surface of the cathode current collector, and taking lithium ion battery cells as an example, the cathode current collector can be made of aluminum, and the cathode active substances can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate and the like. The anode sheet (also called as a negative electrode sheet) includes an anode current collector and an anode active material provided on at least one surface of the anode current collector, the anode current collector may be made of copper, and the anode active material may be carbon or silicon or the like.

The lamination portion 211 is located inside the winding portion 212, that is, the lamination portion 211 is provided inside the innermost ring of the winding portion 212. In the lamination portion 211, at least one of the first cathode sheet 2111 and the first anode sheet 2112 is of a discontinuous structure and includes at least two spaced apart active material portions. For example, as shown in fig. 3 and 4, the first cathode sheet 2111 and the first anode sheet 2112 are both discontinuous structures, and it is understood that only the first cathode sheet 2111 or only the first anode sheet 2112 may be discontinuous structures; as shown in fig. 3 and 4, the first separator 2113 is also a discontinuous structure, and it is understood that the first separator 2113 may be a continuous wound structure.

At least two active material portions are disposed at intervals along the winding direction of the electrode assembly 21. The winding direction refers to the winding direction of the entire electrode assembly 21, that is, the winding direction of the winding portion 212. If one of the first cathode sheet 2111 and the first anode sheet 2112 is a continuous structure and the first separator 2113 is a continuous structure or a discontinuous structure, the continuous structure of the electrode sheet and the first separator 2113 is wound in the same direction as the winding direction of the whole electrode assembly 21. Taking the first cathode sheet 2111 as an example of a discontinuous structure, the first cathode sheet 2111 includes at least two spaced apart active material portions (cathode active material portions 201) in the winding direction, and the at least two spaced apart active material portions are stacked. Accordingly, the first cathode tab 2111 may include at least two stacked active material portions, and a gap between the two active material portions may correspond to a corner of the electrode assembly 21, i.e., the active material portions may avoid the corner, thereby avoiding problems of pole piece powder falling and brittle fracture cracking due to excessive bending at the corner.

In the winding part 212, since the winding part 212 is disposed outside the lamination part 211, that is, the winding part 212 is disposed at the outer ring of the electrode assembly 21, the radius of curvature of the winding part 212 at the corner is large, and the problems of pole piece powder falling, brittle fracture cracking and lithium precipitation are not easy to occur, the winding part 212 can be directly formed by winding the second cathode sheet 2121, the second anode sheet 2122 and the second separator 2123, and the second cathode sheet 2121, the second anode sheet 2122 and the second separator 2123 can be in a continuous winding structure, so that the manufacturing efficiency is high.

It is understood that the first cathode tab 2111 of the lamination portion 211 and the second cathode tab 2121 of the winding portion 212 may be electrically connected through a tab, and the first anode tab 2111 of the lamination portion 211 and the second anode tab 2122 of the winding portion 212 may be electrically connected through a tab.

In this embodiment of the present application, the "discontinuous" may be completely separated, that is, they are not in contact, and taking the first cathode sheet as an example, the complete separation refers to that the cathode current collector is broken into at least two sections, and the two sections of cathode current collectors are disposed at a certain distance, and the cathode current collector and the cathode active material form a gap at the breaking position; the "discontinuous" may also be partially separated, for example, by the first cathode sheet, where the partial separation means that the cathode current collector is continuous, and the cathode active material on the cathode current collector is separated to form at least two sections of active material portions, and two adjacent sections of cathode active material portions are disposed at a certain distance, that is, the cathode active material forms a void at the break.

The electrode assembly 21 includes a lamination portion 211 and a winding portion 212, wherein the winding portion 212 is covered on the outside of the lamination portion 211, that is, the lamination portion 211 is disposed in the innermost ring of the winding portion 212; in the lamination portion 211, at least one of the first cathode sheet 2111 and the first anode sheet 2112 is of a discontinuous structure and includes at least two stacked active material portions, and a void portion between the two active material portions may correspond to a corner of the electrode assembly 21, that is, the active material portion may avoid the corner, so as to avoid the problems of pole piece powder falling and brittle fracture caused by a large radian at the corner, and the active material portion may avoid the corner, so that the problem of lithium precipitation caused by a small CB value at the corner can be prevented.

Where "CB value" refers to the ratio of the anode active material capacity per unit area to the cathode active material capacity per unit area, reflecting the ability of the active ions provided by the cathode to be received by the anode during charging. If the CB value is small, the electrode assembly 21 is at risk of lithium precipitation.

In addition, in order to avoid the problem of powder falling at corners, the electrode assembly 21 in some cases is designed as a roll core of a hollow structure, resulting in low space and active material utilization of the electrode assembly 21, reduced energy density and increased cost; the electrode assembly 21 provided by the embodiment of the application can ensure that the corner of the winding part 212 has a larger curvature radius and is not easy to fall off powder, and meanwhile, the lamination part 211 is arranged in the winding part 212, so that the material use is reduced and the performance of the electrode assembly 21 is improved while the energy and the capacity are considered.

In some embodiments, the first cathode sheet 2111 is a discontinuous structure, the first anode sheet 2112 is a continuous structure or a discontinuous structure, and the first separator 2113 is a continuous structure or a discontinuous structure.

For example, as shown in fig. 4, in an embodiment, the first cathode sheet 2111, the first anode sheet 2112, and the first separator 2113 are each of a discontinuous structure, and the first cathode sheet 2111, the first anode sheet 2112, and the first separator 2113 each include a plurality of sheet portions and the plurality of sheet portions are stacked. In other embodiments, one of the first anode sheet 2112 and the first separator 2113 is also a continuous structure, the other is a discontinuous structure, and the first separator 2113 is a discontinuous structure.

In other embodiments, one of the first anode sheet 2112 and the first separator 2113 is a continuous structure, the other is a discontinuous structure, and the first separator 2113 is a continuous structure.

In some cases, the CB (CellBalance) value of the cell is small in the region where the cathode wraps the anode at the corner of the inner ring of the electrode assembly 21, which easily leads to the risk of lithium precipitation at the corner.

Therefore, the embodiment of the present application designs the first cathode tab 2111 of the inner ring of the electrode assembly 21 to be of a discontinuous structure such that a partial region of the first cathode tab 2111 avoids a corner, and the number of lithium ions that can be deintercalated on the first cathode tab 2111 located at the corner is significantly reduced, thereby alleviating the problem of lithium precipitation at the corner.

Through adopting above-mentioned technical scheme, at least, with lamination portion 211's first negative pole piece 2111 design to discontinuous structure, first positive pole piece 2112 and first barrier film 2113 can set up to continuous structure or discontinuous structure as required to alleviate the problem of lithium analysis, promoted the cycle life and the security performance of battery.

In some embodiments, the electrode assembly 21 includes a flat region 21a and corner regions 21b at both ends of the flat region 21a, and the multi-segment active material portions are stacked in the flat region 21 a.

It is understood that the flat regions 21a and the corner regions 21b are defined based on the overall shape of the electrode assembly, that is, the electrode assembly composed of the lamination portion 211 and the winding portion 212 is divided into the flat regions 21a and the corner regions 21b in the overall shape.

As shown in fig. 3 and 4, the cross-sectional shape of the electrode assembly 21 is substantially a rectangle with rounded sides, and the shorter sides of the rectangle are circular arcs or substantially circular arcs as compared with the rectangle. The electrode assembly 21 includes a flat region 21a and two corner regions 21b, the corner regions 21b being circular arcs or substantially circular arcs. The flat region 21a refers to a region of the electrode assembly 21 having a parallel structure, i.e., the cathode tab, the anode tab, and the separator within the flat region 21a are substantially parallel to each other, and each layer of the cathode tab, the anode tab, and the separator is planar. The corner region 21b refers to the corner of the electrode assembly 21, and the cathode tab, the anode tab, and the separator in the corner region 21b are bent, and each layer of the cathode tab, the anode tab, and the separator in the corner region 21b may be curved or have a corner. The "angle" refers to a bending angle with a certain angle, and may be various angles such as an acute angle, a right angle, an obtuse angle, and the like, and combinations thereof.

Since the plural active material portions are disposed in layers within the flat region 21a, the empty portion between each two adjacent active material portions may correspond to the corner region 21b. Since the corner region 21b of the inner ring of the electrode assembly 21 is excessively bent and the curvature of some pole pieces is excessively large in some cases, the first cathode sheet 2111 and/or the second cathode sheet 2121 with discontinuous structures can be avoided from the corner region 21b by corresponding the empty part between the two active material parts to the corner region 21b in the embodiment, so that the problems of pole piece powder falling, brittle fracture, cracking and lithium precipitation at the corners are relieved. Since the outer ring of the electrode assembly 21 has a large radius of curvature at the corner region 21b, the problem of lithium precipitation does not easily occur, and thus the winding portion 212 does not need to be provided with a discontinuous structure of the pole piece.

Specifically, the first cathode sheet 2111 has a discontinuous structure, and a void portion between two adjacent cathode active material portions 201 in the first cathode sheet 2111 corresponds to the corner region 21b; if the first anode tab 2112 is also of a discontinuous structure, the void between two adjacent anode active material portions 202 in the first anode tab 2112 also corresponds to the corner region 21b.

By adopting the technical scheme, the active material parts in the first cathode strip 2111 and/or the first anode strip 2112 with the discontinuous structures are arranged in the flat area 21a in an inner layer manner, so that the problems of powder falling and brittle fracture cracking of the pole piece in the corner area 21b can be avoided, and the problem of lithium precipitation can be relieved.

Referring to fig. 3 to 4, in some embodiments, the active material portions in the first cathode sheet 2111 each correspond to a flat region 21a.

The first cathode sheet 2111 includes at least two active material portions (cathode active material portions 201), and the active material portions are located in the flat regions 21a, that is, the active material portions are each in a flat sheet-like structure, and a plurality of active material portions are disposed in the flat regions 21a.

In particular, since the brittle fracture problem and the powder falling problem often occur in the first to third turns of the electrode assembly 21 from inside to outside, the first cathode tabs 2111 may be positioned in the first to third turns of the inner turn of the electrode assembly 21. Since the first cathode tab 2111 is located only in the flat region 21a, each active material portion may be equal to or close to the length of the flat region 21a in order to secure the energy and capacity of the electrode assembly 21, i.e., both ends of each active material portion extend to the end of the flat region 21a near the corner region 21b, respectively, the first cathode tab 2111 does not need to be provided with a break in the flat region 21a.

It will be appreciated that in other embodiments, the first cathode tabs 2111 may also be provided on the inner, middle and outer rings of the electrode assembly 21.

By adopting the above technical scheme, the active material portion of the first cathode sheet 2111 is located in the flat region 21a, and then the first cathode sheet 2111 adopts the lamination structure design mode, so that the energy and the capacity of the electrode assembly 21 can be improved, and the problems of powder falling, brittle fracture, cracking and even lithium precipitation of the first cathode sheet 2111 at the corner are relieved.

As shown in fig. 3 and 4, in some embodiments, not only the first cathode sheet 2111 is in a discontinuous structure, but also the first anode sheet 2112 is in a discontinuous structure, the active material portions in the first cathode sheet 2111 and the active material portions in the first anode sheet 2112 are all located in the flat region 21a, and the active material portions of the first cathode sheet 2111 and the active material portions of the first anode sheet 2112 are alternately and stacked in the flat region 21 a.

When the first cathode sheet 2111 and the first anode sheet 2112 are both in a discontinuous structure, the active material portion (cathode active material portion 201) in the first cathode sheet 2111 and the active material portion (anode active material portion 202) in the first anode sheet 2112 can be positioned only in the flat region 21a, and thus, the first anode sheet 2112 can be prevented from being excessively bent at the corner to be dropped and cracked.

As shown in fig. 5 and 6, another embodiment of the present application provides an electrode assembly 21, the electrode assembly 21 including a lamination part 211 and a winding part 212; the first cathode sheet 2111 has a discontinuous structure, the first anode sheet 2112 has a continuous structure, and the first separator 2113 has a continuous structure. The first anode tab 2112 includes a plurality of stacked portions 21121 and bent portions 21122 alternately arranged, the plurality of stacked portions 21121 being stacked in a straight region 21a, each bent portion 21122 connecting two stacked portions 21121 and being located in a corner region 21b; along the lamination direction (T direction in fig. 6) of the lamination portions 21121, the active material portion of the first cathode sheet 2111 is located between the two lamination portions 21121 that are laminated.

Since the first cathode sheet 2111 is easy to fall off powder at the corner of the inner ring of the electrode assembly 21, by adopting the above technical scheme, in the lamination part 211, only the first cathode sheet 2111 is arranged to be of a discontinuous structure, so that the problems of pole piece powder falling and brittle fracture cracking of the first cathode sheet 2111 can be solved; meanwhile, the problems of small CB value and lithium precipitation in the inner ring of the electrode assembly 21 can be relieved.

Referring to fig. 7 and 8, a further embodiment of the present application provides an electrode assembly 21 including a lamination part 211 and a winding part 212; in the lamination section 211, the first cathode sheet 2111 is of a discontinuous structure, and the first anode sheet 2112 and the first separator 2113 are of a continuous structure; the electrode assembly 21 includes a flat region 21a and two corner regions 21b, and a void portion between two adjacent active material portions corresponds to the corner region 21b.

In the present embodiment, the multi-stage active material portion in the first cathode sheet 2111 includes a first active material portion 201a and a second active material portion 201b, the first active material portion 201a extending only within the flat region 21a, and the second active material portion 201b extending at both the flat region 21a and the corner region 21b.

Taking fig. 8 as an example, from the innermost turn of the electrode assembly 21, the first active material portion 201a is located only in the flat region 21a, the second active material portion 201b is wound one and a half turns from the flat region 21a in the winding direction of the first anode tab 2112, and a void portion between the two active material portions corresponds to one corner region 21b; next, the further first active material portion 201a is located only in the flat region 21a.

As can be seen, the first cathode sheet 2111 may include a plurality of discontinuous active material portions, and the lamination portion may be designed as a combination of lamination and winding, so long as the empty portion between two adjacent active material portions along the winding direction corresponds to the corner region 21b, the problems of brittle fracture, powder dropping and even lithium precipitation of the first cathode sheet 2111 in the corner region 21b can be alleviated.

In some embodiments, the first anode sheet 2112 is a continuous structure, and the first anode sheet 2112 includes a plurality of stacked portions 21121 and curved portions 21122 alternately arranged, the plurality of stacked portions 21121 being stacked within the flat region 21a, each curved portion 21122 connecting two stacked portions 21121 and being located at the corner region 21b. Along the lamination direction (T direction) of the lamination portions 21121, the first active material portion 201a is located between the two lamination portions 21121, and a part of the second active material portion 201b is located between the two lamination portions 21121; along the lamination direction (L direction) of the bent portions 21122, the remaining portion of the second active material portion 201b is located between the two laminated bent portions 21122.

By adopting the above technical scheme, the lamination portion may be designed as a lamination and winding in any combination, and the first anode tab 2112 may be designed as a continuous structure; since the first active material portion 201a avoids the corner region, the problem that the first cathode sheet 2111 is brittle and cracked in the corner region 21b, powder is dropped and even lithium is separated can be alleviated; only part of the active material is located in the corner region 21b, increasing the gap between the pole pieces and improving the wettability of the pole pieces.

In other embodiments, the first anode tab 2112 may also be a discontinuous structure.

In some embodiments, the corners of the first anode sheet 2112 and/or the first separator 2113 in a continuous structure are in an arc or dog-ear structure.

For example, as shown in fig. 5 and 6, the corners of the first anode sheet 2112 and the first separator 2113 are each curved. It will be appreciated that the corners of the first anode sheet 2112 and the first separator 2113 may also be formed at intervals to form a plurality of folded corners, for example, by forming two right angles spaced apart to effect winding.

Since the first cathode sheet 2111 of the lamination portion 211 is a discontinuous structure, any one of the first anode sheet 2112 and the first separator 2113 may be a continuous structure. The first cathode sheet 2111 has been designed in a discontinuous structure and avoid the corner region 21b, and the first anode sheet 2112 and the first separator 2113 may have corners arranged in an arc or folded structure when being wound to adapt to different demands.

Through adopting above-mentioned technical scheme, the form of lamination portion 211 has multiple choice, and first anode strip 2112, first barrier film 2113 can set up the turning into arc or dog-ear structure, has higher system Cheng Ling activity to promote manufacturing efficiency.

Fig. 9 to 11 are schematic structural views of a lamination portion 211 provided in some embodiments of the present application. As shown in fig. 9 and 10, the first cathode sheet 2111 and the first anode sheet 2112 are each of a discontinuous structure, and the active material portions of the first cathode sheet 2111 and the second cathode sheet 2121 are alternately and stacked; the first separator 2113 is a continuous wound structure. That is, the lamination portion 211 adopts a single-layer lamination design. The difference is that the first separation film 2113 in fig. 9 is arc-shaped at its corners, and the first separation film 2113 in fig. 10 is right-angled at its corners.

As shown in fig. 11, the first anode tab 2112 has a discontinuous structure, and the first cathode tab 2111 has a continuous structure, so as to avoid brittle fracture, cracking and powder dropping of the first anode tab 2112.

It should be noted that, in order to solve the problems of corner powder falling and brittle failure of the inner ring, the number of layers of the active material portion in the lamination portion 211 may be greater than 1; the number of layers of the lamination portion 211 is not limited in this application, and for example, the number of layers of the active material portion may be 2, 3, 4 or more. The specific form of the laminate is not limited to the above embodiment, as long as at least one of the first anode sheet 2112 and the first cathode sheet 2111 can be designed as a discontinuous structure.

Referring again to fig. 3-11, in some embodiments, the compacted density of the first anode tab 2112 is less than the compacted density of the second anode tab 2122; and/or the compacted density of the first cathode sheet 2111 is less than the compacted density of the second cathode sheet 2121.

The first and second cathode sheets 2111 and 2121 each include a cathode current collector and a cathode active material provided on at least one surface of the cathode current collector, and the first and second anode sheets 2112 and 2122 each include an anode current collector and an anode active material provided on at least one surface of the anode current collector. "compacted density" refers to the weight of the cathode active material or anode active material per unit volume.

Since the lamination portion 211 is disposed on the inner ring and the winding portion 212 is disposed on the outer ring, the compacted density of the pole pieces in the lamination portion 211 is smaller than that in the winding portion 212, so that the wettability of the first cathode strip 2111 and the first anode strip 2112 can be increased, and the probability of wrinkling the inner ring can be reduced.

It should be noted that, the lamination portion 211 and the winding portion 212 may adopt different design systems, and each of the first cathode sheet 2111 and the second cathode sheet 2121 includes a cathode current collector and a cathode active material disposed on at least one surface of the cathode current collector, where at least one of the following parameters in the first cathode sheet 2111 and the second cathode sheet 2121 is different: the compacted density, the coating weight of the cathode active material per unit area, the material of the cathode active material, the material of the cathode current collector;

The first anode tab 2112 and the second anode tab 2122 each include an anode current collector and an anode active material provided on at least one side of the anode current collector, and at least one of the following characteristics in the first anode tab 2112 and the second anode tab 2122 is different: the density of compaction, the coating weight of the anode active material per unit area, the material of the anode active material, the material of the anode current collector.

In addition, the spacing between any of the electrode plates in the inner, middle and outer rings of the electrode assembly 21 may be adjusted according to design requirements.

Through adopting above-mentioned technical scheme, the pole piece parameter in lamination portion 211 and the portion of convoluteing 212 can set up according to the design requirement respectively to satisfy different demands, the flexibility is better.

In some embodiments, the pole pieces in the winding portion 212 are made of a material with a low CB value, so that the CB value in the winding portion 212 is smaller than the CB value in the lamination portion 211, so as to reduce the cost.

Referring to fig. 3 to 11, in some embodiments, the cathode current collector and the cathode active material of the first cathode sheet are both discontinuous structures; and/or the anode current collector and the anode active material of the first anode sheet are both discontinuous structures.

Therefore, for the pole piece with a discontinuous structure, a plurality of active material parts in the pole piece are completely disconnected, and the problems of falling off, brittle fracture, cracking and lithium precipitation of active materials in the pole piece at the corner of the electrode assembly are improved.

In other embodiments, the cathode current collector of the first cathode sheet is a continuous structure and the cathode active material is discontinuously distributed on the cathode current collector; and/or the anode current collector of the first anode sheet is of a continuous structure and the anode active material is discontinuously distributed on the anode current collector.

Thus, for the pole piece with a discontinuous structure, the active substances in the pole piece are divided into a plurality of parts which are arranged at intervals, the current collector of the pole piece can be kept continuous, the integrity of the pole piece is better, and the lamination part of the electrode assembly can be manufactured in a winding mode, so that the manufacturing is convenient.

The electrode assembly 21 provided in the embodiments of the present application is not limited to be applicable to a lithium battery structure, but may be used for other batteries and energy storage devices, such as super-capacitors, metal batteries, sodium batteries, solid-state batteries, and the like.

Referring to fig. 1 to 11, a second aspect of the present application provides a battery cell 20 including an electrode assembly 21 provided in the first aspect.

A third aspect of the present application provides a battery 100 comprising a battery cell 20 as provided in the second aspect.

Referring to fig. 1, a fourth aspect of the present application provides a powered device, including the battery of the third aspect, and the battery is configured to provide power to the powered device.

The powered device may be any of the aforementioned devices or systems that employ a battery.

The above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims (16)

1. An electrode assembly, characterized in that: comprising the following steps:

the lamination part comprises a first cathode plate, a first anode plate and a first isolating film arranged between the first cathode plate and the first anode plate, wherein at least one of the first cathode plate and the first anode plate is of a discontinuous structure and comprises at least two sections of active material parts which are arranged in a lamination way;

the winding part is coated outside the lamination part and comprises a second cathode plate, a second anode plate and a second isolating film, wherein the second cathode plate and the second anode plate are wound, and the second isolating film is arranged between the second cathode plate and the second anode plate.

2. The electrode assembly of claim 1, wherein: the first cathode sheet is of a discontinuous structure, and the first anode sheet is of a continuous structure or a discontinuous structure.

3. The electrode assembly of claim 2, wherein: the electrode assembly comprises a flat region and corner regions positioned at two ends of the flat region, and a plurality of sections of the active material parts are stacked in the flat region.

4. The electrode assembly of claim 3, wherein: the active material portions in the first cathode sheet are all located in the flat region.

5. The electrode assembly of claim 4, wherein: the first anode plate is of a discontinuous structure, active material parts in the first anode plate are located in the straight area, and the active material parts of the first cathode plate and the active material parts of the first anode plate are alternately and stacked in the straight area.

6. The electrode assembly of claim 4, wherein: the first anode sheet is of a continuous structure and comprises a plurality of stacked parts and bent parts which are alternately arranged, the stacked parts are stacked in the straight area, and each bent part is connected with two stacked parts and is positioned in the corner area;

The active material portion of the first cathode sheet is located between the two laminated portions along the lamination direction of the laminated portions.

7. The electrode assembly of claim 3, wherein: the plurality of segments of the active material portion in the first cathode sheet include a first active material portion extending only within the straight region and a second active material portion extending simultaneously in the straight region and the corner region.

8. The electrode assembly of claim 7, wherein: the first anode sheet is of a continuous structure and comprises a plurality of stacked parts and bent parts which are alternately arranged, the stacked parts are stacked in the straight area, and each bent part is connected with two stacked parts and is positioned in the corner area;

along a lamination direction of the lamination portions, the first active material portion is located between the lamination portions of two lamination, and a portion of the second active material portion is located between the lamination portions of two lamination; the remaining portion of the second active material portion is located between the two stacked bent portions along the stacking direction of the bent portions.

9. The electrode assembly of claim 2, wherein: the corners of the first anode sheet and/or the first isolating film which are in a continuous structure are in an arc-shaped or folded angle structure.

10. The electrode assembly of any one of claims 1-9, wherein: the compacted density of the first anode sheet is less than the compacted density of the second anode sheet; and/or

The compacted density of the first cathode sheet is less than the compacted density of the second cathode sheet.

11. The electrode assembly of any one of claims 1-9, wherein: the first cathode plate and the second cathode plate comprise a cathode current collector and cathode active materials arranged on at least one surface of the cathode current collector, and at least one of the following characteristics in the first cathode plate and the second cathode plate is different: the compacted density, the coating weight of the cathode active material per unit area, the material of the cathode active material, the material of the cathode current collector;

the first anode sheet and the second anode sheet comprise anode current collectors and anode active materials arranged on at least one surface of the anode current collectors, and at least one of the following characteristics in the first anode sheet and the second anode sheet is different: the density of compaction, the coating weight of the anode active material per unit area, the material of the anode active material, the material of the anode current collector.

12. The electrode assembly of any one of claims 1-9, wherein: the first cathode sheet comprises a cathode current collector and cathode active materials arranged on at least one surface of the cathode current collector, and the first anode sheet and the second anode sheet both comprise an anode current collector and anode active materials arranged on at least one surface of the anode current collector;

wherein the cathode current collector of the first cathode plate is of a continuous structure and the cathode active material is discontinuously distributed on the cathode current collector; and/or the number of the groups of groups,

the anode current collector of the first anode sheet is of a continuous structure and the anode active material is discontinuously distributed on the anode current collector.

13. The electrode assembly of any one of claims 1-9, wherein: the first cathode sheet comprises a cathode current collector and cathode active materials arranged on at least one surface of the cathode current collector, and the first anode sheet and the second anode sheet both comprise an anode current collector and anode active materials arranged on at least one surface of the anode current collector;

wherein, the cathode current collector of the first cathode plate and the cathode active material are both in a discontinuous structure; and/or the number of the groups of groups,

the anode current collector of the first anode sheet and the anode active material are both discontinuous structures.

14. A battery cell comprising an electrode assembly according to any one of claims 1-13.

15. A battery comprising the battery cell of claim 14.

16. A powered device comprising the battery of claim 15.

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