CN215299297U - Electrode assembly, battery cell, battery, and power consumption device - Google Patents
Electrode assembly, battery cell, battery, and power consumption device Download PDFInfo
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- CN215299297U CN215299297U CN202121488354.7U CN202121488354U CN215299297U CN 215299297 U CN215299297 U CN 215299297U CN 202121488354 U CN202121488354 U CN 202121488354U CN 215299297 U CN215299297 U CN 215299297U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The application discloses electrode subassembly, battery monomer, battery and power consumption device. The electrode assembly comprises a positive electrode piece and a negative electrode piece, wherein a positive active material layer of the positive electrode piece faces a negative active material layer of the negative electrode piece. The negative electrode active material layer includes a negative electrode main portion, a negative electrode transition portion, and a negative electrode edge portion provided along the first direction, and a thickness of the negative electrode main portion is larger than a thickness of the negative electrode transition portion and a thickness of the negative electrode edge portion. In the first direction, the edge portion of the negative electrode exceeds the positive electrode active material layer; in the stacking direction, at least a part of the negative electrode transition portion overlaps with the positive electrode active material layer, and at least a part of the negative electrode main body portion overlaps with the positive electrode active material layer. The negative pole piece is equipped with the negative pole conducting layer in the negative pole transition portion keep away from anodal active material layer one side, and the negative pole conducting layer is used for supporting negative pole transition portion to make the surface of negative pole transition portion towards anodal active material layer flush with the surface of negative pole main part towards anodal active material layer.
Description
Technical Field
The present disclosure relates to the field of batteries, and more particularly, to an electrode assembly, a battery cell, a battery, and an electric device.
Background
The battery cell is widely used in electronic devices such as a mobile phone, a notebook computer, a battery car, an electric airplane, an electric ship, an electric toy car, an electric toy ship, an electric toy airplane, an electric tool, and the like. The battery monomer can comprise a cadmium-nickel battery monomer, a hydrogen-nickel battery monomer, a lithium ion battery monomer, a secondary alkaline zinc-manganese battery monomer and the like.
In addition to improving the performance of the battery cell, safety issues are also a considerable problem in the development of battery technology. If the safety problem of the battery cell cannot be guaranteed, the battery cell cannot be used. Therefore, how to enhance the safety of the battery cell is a technical problem to be solved urgently in the battery technology.
SUMMERY OF THE UTILITY MODEL
The application provides an electrode subassembly, battery monomer, battery and power consumption device, it can strengthen the security.
In a first aspect, an embodiment of the present application provides an electrode assembly, which includes a positive electrode plate and a negative electrode plate that are stacked, where a positive active material layer of the positive electrode plate and a negative active material layer of the negative electrode plate are disposed facing each other. The negative active material layer comprises a negative main body part, a negative transition part and a negative edge part which are sequentially arranged along a first direction, the thickness of the negative main body part is greater than that of the negative transition part and that of the negative edge part, and the first direction is perpendicular to the superposition direction of the positive pole piece and the negative pole piece. In the first direction, the edge portion of the negative electrode exceeds the positive electrode active material layer; in the stacking direction, at least a part of the negative electrode transition portion overlaps with the positive electrode active material layer, and at least a part of the negative electrode main body portion overlaps with the positive electrode active material layer. The negative pole piece is equipped with the negative pole conducting layer in the negative pole transition portion keep away from anodal active material layer one side, and the negative pole conducting layer is used for supporting negative pole transition portion to make the surface of negative pole transition portion towards anodal active material layer flush with the surface of negative pole main part towards anodal active material layer.
In the above aspect, the thickness of the negative electrode edge portion is smaller than the thickness of the negative electrode main body portion, and therefore, in the process of rolling the negative electrode active material layer, the negative electrode edge portion is not directly rolled, and the risk of cracking of the negative electrode active material layer is reduced. The thickness of the negative electrode transition part is also smaller than that of the negative electrode main body part, so that the size of the thin layer region of the negative electrode active material layer along the first direction can be increased when the negative electrode active material layer is coated, and the difficulty of the coating process can be reduced. The negative pole conducting layer can play the effect of supporting negative pole transition portion, consequently, even the thickness of this application embodiment reduced negative pole transition portion, can not additionally increase the clearance between negative pole transition portion and the positive pole active material layer, improves the infiltration nature of electrolyte, reduces and educes the lithium risk, improves the security performance.
In some embodiments, the thickness of the negative electrode transition portion gradually decreases and the thickness of the negative electrode conductive layer gradually increases in a direction away from the negative electrode main body portion, so that the total thickness of the negative electrode transition portion and the negative electrode conductive layer is constant. The embodiment can avoid the generation of steps at the joint of the negative electrode transition part and the negative electrode main body part, and reduce the stress concentration during rolling.
In some embodiments, a junction of the anode transition portion and the anode edge portion exceeds the cathode active material layer in the first direction. This embodiment can reduce the risk of overlapping the anode edge portion and the cathode active material layer in the stacking direction due to assembly errors.
In some embodiments, the negative electrode transition has a dimension in the first direction greater than 5mm. The embodiment can reduce the requirements on the process and improve the forming efficiency of the negative pole piece
In some embodiments, the anode transition portion has a distance D1 from the cathode active material layer in the stacking direction, the anode main portion has a distance D2 from the cathode active material layer in the stacking direction, and D1 is equal to D2. The embodiment can improve the consistency of the gap between the positive electrode active material layer and the negative electrode active material layer, improve the wettability, reduce the risk of lithium precipitation and improve the safety performance.
In some embodiments, the positive electrode active material layer is a coating of uniform thickness. The embodiment can simplify the coating process of the positive active material layer and improve the forming efficiency of the positive pole piece.
In some embodiments, the positive electrode active material layer includes a positive electrode main portion and a positive electrode edge portion arranged in this order in the first direction, and a thickness of the positive electrode main portion is greater than a thickness of the positive electrode edge portion. At least a portion of the positive electrode edge portion overlaps the negative electrode transition portion in the stacking direction. The positive electrode plate is provided with a positive electrode conducting layer on one side of the positive electrode edge part, which is far away from the negative electrode active material layer, and the positive electrode conducting layer is used for supporting the positive electrode edge part so that the surface of the positive electrode edge part, which faces the negative electrode active material layer, is flush with the surface of the positive electrode main body part, which faces the negative electrode active material layer. In this embodiment, the thickness of the edge portion of the positive electrode can be reduced by providing the positive electrode conductive layer, so as to reduce ions that can be extracted from the edge portion of the positive electrode, and reduce the risk of lithium deposition at the transition portion of the negative electrode.
In some embodiments, the weight ratio of active material in the negative conductive layer to the negative conductive layer is greater than the weight ratio of active material in the negative transition to the negative transition; alternatively, the gram capacity of the active material in the negative conductive layer is greater than the gram capacity of the active material in the negative transition portion; alternatively, the particle size of the active material in the negative electrode conductive layer is smaller than the particle size of the active material in the negative electrode transition portion.
In a second aspect, an embodiment of the present application provides a battery cell, which includes: a housing; the electrode assembly of any one of the embodiments of the first aspect, wherein the electrode assembly is housed within a case.
In a third aspect, an embodiment of the present application provides a battery, which includes a case and a battery cell of the second aspect, where the battery cell is accommodated in the case.
In a fourth aspect, an embodiment of the present application provides an electric device, which includes the battery of the third aspect, and the battery is used for providing electric energy.
Drawings
Features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;
fig. 2 is an exploded schematic view of a battery provided in accordance with some embodiments of the present application;
fig. 3 is a schematic structural view of the battery module shown in fig. 2;
fig. 4 is an exploded schematic view of the battery cell shown in fig. 3;
FIG. 5 is a schematic structural view of an electrode assembly provided in accordance with certain embodiments of the present application;
FIG. 6 isbase:Sub>A partial cross-sectional view of the electrode assembly shown in FIG. 5 taken along line A-A;
FIG. 7 is an enlarged schematic view of the electrode assembly shown in FIG. 6 at block B;
fig. 8 is another partial cross-sectional view of the electrode assembly shown in fig. 5 taken along linebase:Sub>A-base:Sub>A.
In the drawings, the drawings are not necessarily drawn to scale.
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 obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to 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.
The term "and/or" in this application is only one kind of association relationship describing the association object, and means that there may be three kinds of relationships, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in this application generally indicates that the former and latter related objects are in an "or" relationship.
In the embodiments of the present application, like reference numerals denote like components, and in the different embodiments, detailed descriptions of the like components are omitted 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 this application, the battery cell may include a lithium ion secondary battery cell, a lithium ion primary battery cell, a lithium sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, or a magnesium ion battery cell, and the embodiment of the present application is not limited thereto. 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 a packaging manner: the cylindrical battery monomer, the square battery monomer and the soft package battery monomer are also 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 cell includes an electrode assembly and an electrolyte, the electrode assembly including a positive electrode tab, a negative electrode tab, 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 comprises a positive pole current collector and a positive pole active substance layer, and the positive pole active substance layer is coated on the surface of the positive pole current collector; the positive current collector comprises a positive current collecting part and a positive electrode lug protruding out of the positive current collecting part, and the positive current collecting part is coated with a positive active substance layer. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, or the like. The negative pole piece comprises a negative pole current collector and a negative pole active substance layer, and the negative pole active substance layer is coated on the surface of the negative pole current collector; the negative current collector comprises a negative current collecting part and a negative electrode lug protruding out of the negative current collecting part, and the negative current collecting part is coated with a negative active material layer. The material of the negative electrode current collector may be copper, the negative electrode active material layer includes a negative electrode active material, 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 material of the spacer may be PP (polypropylene) or PE (polyethylene). In addition, the electrode assembly may have a winding structure or a lamination structure, and the embodiment of the present application is not limited thereto.
In the process of manufacturing the negative pole piece, the negative pole active material, the adhesive, the conductive agent, the solvent and the like are mixed to prepare negative pole active slurry, then the negative pole active slurry is coated on a negative pole current collector, and the negative pole active slurry forms a negative pole active material layer through the working procedures of drying, rolling and the like. The negative electrode active slurry is water-based slurry, and if the negative electrode active material layer is coated in the same thickness, the negative electrode active material layer can generate bulges at the edge when being dried due to the fluidity and the surface tension of the negative electrode active slurry; at the time of roll pressing, the projections are directly subjected to roll pressing, thereby causing cracks at the edges of the anode active material layer. In order to reduce cracks, the thickness of the edge of the anode active material layer is reduced to form a thin layer region when coating, so that even if the thin layer region generates a projection when dried, the projection does not exceed the normal thickness region of the anode active material layer, and the projection is not rolled when rolled, thereby reducing the risk of cracking of the anode active material layer.
However, the inventors found that, after the thickness of the thin layer region is reduced, the gap between the thin layer region and the positive electrode active material layer increases, which causes poor wetting of the electrolyte, deterioration of the kinetic properties, and a lithium deposition phenomenon easily occurring in the thin layer region at the time of high-power charging, leading to a safety risk.
In view of this, the embodiment of the present application provides a technical solution, where an electrode assembly in the technical solution includes a positive electrode sheet and a negative electrode sheet that are stacked, and a positive active material layer of the positive electrode sheet and a negative active material layer of the negative electrode sheet are disposed facing each other. The negative active material layer comprises a negative main body part, a negative transition part and a negative edge part which are sequentially arranged along a first direction, the thickness of the negative main body part is greater than that of the negative transition part and that of the negative edge part, and the first direction is perpendicular to the superposition direction of the positive pole piece and the negative pole piece. In the first direction, the edge portion of the negative electrode exceeds the positive electrode active material layer; in the stacking direction, at least a part of the negative electrode transition portion overlaps with the positive electrode active material layer, and at least a part of the negative electrode main body portion overlaps with the positive electrode active material layer. The negative pole piece is equipped with the negative pole conducting layer in the negative pole transition portion keep away from anodal active material layer one side, and the negative pole conducting layer is used for supporting negative pole transition portion to make the surface of negative pole transition portion towards anodal active material layer flush with the surface of negative pole main part towards anodal active material layer. This structure can reduce the clearance between the positive electrode active material layer and the negative electrode active material layer, reduce the risk of lithium precipitation, and enhance the safety of the battery.
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, spacecraft, and the like; the 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 tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and electric 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.
Fig. 1 is a schematic structural diagram of a vehicle according to some embodiments of the present application.
Referring to fig. 1, a battery 2 is disposed inside a vehicle 1, and the battery 2 may be disposed at the bottom or the head or the tail of the vehicle 1. The battery 2 may be used for power supply of the vehicle 1, and for example, the battery 2 may serve as an operation power source of the vehicle 1.
The vehicle 1 may further comprise a controller 3 and a motor 4, the controller 3 being adapted to control the battery 2 to power the motor 4, e.g. for start-up, navigation and operational power demands while driving of the vehicle 1.
In some embodiments of the present application, the battery 2 may not only serve as an operating power source of the vehicle 1, but also serve as a driving power source of the vehicle 1, instead of or in part of fuel or natural gas, to provide driving power for the vehicle 1.
Fig. 2 is an exploded view of a battery provided in some embodiments of the present application.
Referring to fig. 2, the battery 2 includes a case 5 and a battery cell (not shown in fig. 2), and the battery cell is accommodated in the case 5.
The case 5 is used for accommodating the battery cells, and the case 5 may have various structures. In some embodiments, the box body 5 may include a first box body portion 51 and a second box body portion 52, the first box body portion 51 and the second box body portion 52 cover each other, and the first box body portion 51 and the second box body portion 52 jointly define a receiving space 53 for receiving the battery cells. The second box portion 52 may be a hollow structure with one open end, the first box portion 51 is a plate-shaped structure, and the first box portion 51 covers the open side of the second box portion 52 to form the box 5 with the accommodating space 53; the first casing portion 51 and the second casing portion 52 may be hollow structures each having one side opened, and the opening side of the first casing portion 51 may be covered with the opening side of the second casing portion 52 to form the casing 5 having the accommodating space 53. Of course, the first tank portion 51 and the second tank portion 52 may be various shapes, such as a cylinder, a rectangular parallelepiped, and the like.
In order to improve the sealing property after the first casing portion 51 and the second casing portion 52 are connected, a sealing member, such as a sealant or a gasket, may be provided between the first casing portion 51 and the second casing portion 52.
If the first box portion 51 covers the top of the second box portion 52, the first box portion 51 may also be referred to as an upper box cover, and the second box portion 52 may also be referred to as a lower box cover.
In the battery 2, one or more battery cells may be provided. If the number of the battery monomers is multiple, the multiple battery monomers can be connected in series or in parallel or in series-parallel, and the series-parallel refers to that the multiple battery monomers are connected in series or in parallel. The plurality of battery monomers can be directly connected in series or in parallel or in series-parallel, and the whole formed by the plurality of battery monomers is accommodated in the box body 5; of course, a plurality of battery cells may be connected in series or in parallel or in series-parallel to form the battery module 6, and a plurality of battery modules 6 may be connected in series or in parallel or in series-parallel to form a whole and accommodated in the box 5.
Fig. 3 is a schematic structural view of the battery module 6 shown in fig. 2.
Referring to fig. 3, in some embodiments, there are a plurality of battery cells 7, and the plurality of battery cells 7 are connected in series, in parallel, or in series-parallel to form the battery module 6. The plurality of battery modules 6 are connected in series or in parallel or in series-parallel to form a whole and are accommodated in the case.
The plurality of battery cells 7 in the battery module 6 may be electrically connected to each other by a bus member, so as to realize parallel connection, series connection, or parallel-series connection of the plurality of battery cells 7 in the battery module 6.
Fig. 4 is an exploded view of the battery cell 7 shown in fig. 3.
Referring to fig. 4, a battery cell 7 according to an embodiment of the present disclosure includes an electrode assembly 10 and a case 20, wherein the electrode assembly 10 is accommodated in the case 20.
In some embodiments, the housing 20 may also be used to contain an electrolyte, such as an electrolyte. The housing 20 can take a variety of configurations.
In some embodiments, the case 20 may include a case 21 and an end cap 22, the case 21 having a hollow structure with one side open, and the end cap 22 covering the opening of the case 21 and forming a sealing connection to form a sealed space for accommodating the electrode assembly 10 and the electrolyte.
In assembling the battery cell 7, the electrode assembly 10 may be placed in the case 21, the cap 22 may be fitted to the opening of the case 21, and the electrolyte may be injected into the case 21 through the electrolyte injection port formed in the cap 22.
The housing 21 may be in various shapes, such as a cylinder, a rectangular parallelepiped, or the like. The shape of the case 21 may be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylindrical structure, it may be optionally a cylindrical case; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped case may be used. Of course, the end cap 22 may have various structures, for example, the end cap 22 has a plate-shaped structure, a hollow structure with one end open, and the like. Illustratively, in fig. 4, the housing 21 has a rectangular parallelepiped structure, the end cap 22 has a plate-like structure, and the end cap 22 covers an opening at the top of the housing 21.
In some embodiments, cell 7 may further include a positive electrode terminal 30, a negative electrode terminal 40, and a pressure relief mechanism 50, all of which are mounted on end cap 22, positive electrode terminal 30, negative electrode terminal 40, and pressure relief mechanism 50. The positive electrode terminal 30 and the negative electrode terminal 40 are each used to be electrically connected to the electrode assembly 10 to output electric energy generated by the electrode assembly 10. The pressure relief mechanism 50 is used to relieve the internal pressure of the battery cell 7 when the internal pressure or temperature of the battery cell 7 reaches a threshold value.
Illustratively, the pressure relief mechanism 50 is located between the positive electrode terminal 30 and the negative electrode terminal 40, and the pressure relief mechanism 50 may be a component such as an explosion-proof valve, an explosion-proof sheet, a gas valve, a pressure relief valve, or a safety valve.
Of course, in other embodiments, the case 20 may have other structures, for example, the case 20 includes a case 21 and two end caps 22, the case 21 has a hollow structure with two opposite open sides, and the two end caps 22 respectively cover the two open sides of the case 21 and form a sealing connection to form a sealing space for accommodating the electrode assembly 10 and the electrolyte. In this structure, the positive electrode terminal 30 and the negative electrode terminal 40 may be mounted on the same end cap 22, or may be mounted on different end caps 22; the pressure relief mechanism 50 may be mounted on one end cap 22, or the pressure relief mechanisms 50 may be mounted on both end caps 22.
In the battery cell 7, one or more electrode assemblies 10 may be accommodated in the case 20. Illustratively, in fig. 4, there are two electrode assemblies 10.
The specific structure of the electrode assembly 10 will be described in detail with reference to the accompanying drawings.
Fig. 5 isbase:Sub>A structural view of an electrode assembly according to some embodiments of the present application, fig. 6 isbase:Sub>A partial cross-sectional view of the electrode assembly shown in fig. 5 taken along linebase:Sub>A-base:Sub>A, and fig. 7 is an enlarged view of the electrode assembly shown in fig. 6 at block B.
As shown in fig. 5 to 7, the present embodiment provides an electrode assembly 10, which includes a positive electrode tab 11 and a negative electrode tab 12 that are stacked, and a positive electrode active material layer 111 of the positive electrode tab 11 is disposed to face a negative electrode active material layer 121 of the negative electrode tab 12. The negative electrode active material layer 121 includes a negative electrode main body portion 121a, a negative electrode transition portion 121b, and a negative electrode edge portion 121c that are sequentially arranged in a first direction X, the thickness of the negative electrode main body portion 121a is greater than the thickness of the negative electrode transition portion 121b and the thickness of the negative electrode edge portion 121c, and the first direction X is perpendicular to the stacking direction Y of the positive electrode tab 11 and the negative electrode tab 12. In the first direction X, the negative electrode edge portion 121c goes beyond the positive electrode active material layer 111; in the stacking direction Y, at least a part of the negative electrode transition portion 121b overlaps the positive electrode active material layer 111, and at least a part of the negative electrode main body portion 121a overlaps the positive electrode active material layer 111. The negative electrode tab 12 is provided with a negative electrode conductive layer 123 on a side of the negative electrode transition portion 121b away from the positive electrode active material layer 111, and the negative electrode conductive layer 123 supports the negative electrode transition portion 121b such that a surface of the negative electrode transition portion 121b facing the positive electrode active material layer 111 is flush with a surface of the negative electrode main body portion 121a facing the positive electrode active material layer 111.
The electrode assembly 10 further includes a separator 13 separating the positive electrode tab 11 from the negative electrode tab 12, and the separator 13 has a large number of through micro-holes, so as to ensure that electrolyte ions can freely pass through the separator and have good penetrability on lithium ions. The material of the spacer 13 may be PP, PE, or the like.
The electrode assembly 10 may be of a coiled, laminated or other configuration.
In some embodiments, electrode assembly 10 is of a coiled construction. The positive pole piece 11, the negative pole piece 12 and the separator 13 are all in a belt-shaped structure. The positive electrode tab 11, the separator 13, and the negative electrode tab 12 are wound around the winding axis to form a wound structure. In the winding structure, the positive electrode tab 11 and the negative electrode tab 12 are stacked in a direction perpendicular to the winding axis, that is, the stacking direction Y of the positive electrode tab 11 and the negative electrode tab 12 is perpendicular to the winding axis. The positive electrode plate 11 and the negative electrode plate 12 are wound in a plurality of turns along a winding direction, and the winding direction is a direction in which the positive electrode plate 11 and the negative electrode plate 12 are wound circumferentially from inside to outside. The electrode assembly 10 may be flat or cylindrical.
In an alternative embodiment, electrode assembly 10 is of a laminated construction. Specifically, the electrode assembly 10 includes a plurality of positive electrode tabs 11 and a plurality of negative electrode tabs 12, and the positive electrode tabs 11 and the negative electrode tabs 12 are alternately stacked. In the laminated structure, the positive electrode plate 11 and the negative electrode plate 12 are both in a sheet shape, and the stacking direction Y of the positive electrode plate 11 and the negative electrode plate 12 is parallel to the thickness direction of the positive electrode plate 11 and the thickness direction of the negative electrode plate 12.
The positive electrode plate 11 includes a positive electrode collector 112 and a positive electrode active material layer 111 coated on two sides of the positive electrode collector 112, and the negative electrode plate 12 includes a negative electrode collector 122 and a negative electrode active material layer 121 coated on two sides of the negative electrode collector 122.
In the present embodiment, both sides of the anode current collector 122 are provided with the anode active material layer 121, and the anode active material layers 121 described herein each refer to the anode active material layer 121 on one side; similarly, the positive electrode active material layer 111 is provided on both sides of the positive electrode collector 112, and the positive electrode active material layers 111 described herein each refer to the positive electrode active material layer 111 on one side.
The positive current collector 112 includes a positive current collecting portion and a positive tab protruding from the positive current collecting portion, the positive tab being connected to an end of the positive current collecting portion and being for electrical connection to a positive electrode terminal. The negative current collector 122 includes a negative current collecting portion and a negative tab protruding from the negative current collecting portion, the negative tab being connected to an end of the negative current collecting portion and adapted to be electrically connected to a negative electrode terminal.
In the embodiment of the present application, the cathode active material layer 111 refers to a coating containing a cathode active material applied to the surface of the cathode current collector, and the anode active material layer 121 refers to a coating containing an anode active material applied to the surface of the anode current collector.
The present embodiment does not limit the magnitude relationship between the thickness of the negative electrode transition portion 121b and the thickness of the negative electrode edge portion 121c, that is, the thickness of the negative electrode transition portion 121b may be greater than, equal to, or less than the thickness of the negative electrode edge portion 121c.
In the stacking direction Y, the surface of the negative electrode edge portion 121c facing the positive electrode active material layer 111 is lower than the surface of the negative electrode body portion 121a facing the positive electrode active material layer 111. Accordingly, the anode edge portion 121c is not directly rolled in the process of rolling the anode active material layer 121.
In the first direction X, the negative electrode edge portion 121c goes beyond the positive electrode active material layer 111; that is, the negative electrode edge portion 121c as a whole exceeds the positive electrode active material layer 111 in the first direction X; the negative electrode edge portion 121c does not overlap with the positive electrode active material layer 111 in the stacking direction Y.
The positive electrode active material layer 111 has a first end 111c and a second end 111d that are opposite to each other in the first direction X, and the second end 111d is closer to the negative electrode edge portion 121c than the first end 111c. In the first direction X, the connection between the negative electrode transition portion 121b and the negative electrode edge portion 121c may be beyond the second end portion 111d, or may be flush with the second end portion 111d. In the first direction X, one end of the negative electrode main body portion 121a, which is far from the negative electrode transition portion 121b, exceeds the first end portion 111c.
The negative electrode transition part 121b and the negative electrode main body part 121a constitute an ion receiving region, and a projection of the positive electrode active material layer 111 in the stacking direction Y is located within a projection of the ion receiving region in the stacking direction Y. During charging, ions extracted from the positive electrode active material layer 111 are inserted into the negative electrode transition part 121b and the negative electrode main body part 121 a.
The negative conductive layer 123 is coated on the surface of the negative current collector 122, and the negative transition portion 121b is located on a side of the negative conductive layer 123 far from the negative current collector 122. The negative electrode transition portion 121b is a portion of the negative electrode active material layer 121 that overlaps with the negative electrode conductive layer 123 in the stacking direction Y. The negative electrode edge portion 121c and the negative electrode main body portion 121a are coated on the surface of the negative electrode collector 122. In the preparation of the negative electrode tab 12, the negative electrode conductive layer 123 may be coated on a predetermined region of the surface of the negative electrode collector 122, and then the negative electrode active material layer 121 may be coated thereon.
The negative electrode conductive layer 123 may be a coating having a constant thickness or a coating having a variable thickness, and the present application is not limited as long as the negative electrode conductive layer 123 can make the surface of the negative electrode transition part 121b facing the positive electrode active material layer 111 flush with the surface of the negative electrode main part 121a facing the positive electrode active material layer 111.
In the process of manufacturing the positive electrode plate 11, the positive active material, the adhesive, the conductive agent, the solvent and the like are mixed to prepare the positive active slurry, then the positive active slurry is coated on the positive current collector 112, and the positive active slurry is dried, rolled and the like to form the positive active material layer 111. Since the positive electrode active material is an oil-based paste and is less likely to form a protrusion at the edge during drying, the positive electrode active material layer 111 may be provided with or without a thin layer region at the edge.
In the electrode assembly 10 of the embodiment of the present application, the thickness of the anode edge portion 121c is smaller than that of the anode body portion 121a, and therefore, the anode edge portion 121c is not directly rolled during rolling of the anode active material layer 121, thereby reducing the risk of cracking of the anode active material layer 121. Since the thickness of the negative electrode transition part 121b is also smaller than that of the negative electrode main body part 121a, the size of the thin region (i.e., the negative electrode transition part 121b and the negative electrode edge part 121 c) of the negative electrode active material layer 121 in the first direction X can be increased when the negative electrode active material layer 121 is applied, and the difficulty of the application process can be reduced.
The negative electrode conductive layer 123 can support the negative electrode transition part 121b, and therefore, even if the thickness of the negative electrode transition part 121b is reduced in the embodiment of the present application, the gap between the negative electrode transition part 121b and the positive electrode active material layer 111 is not additionally increased, wettability of the electrolyte is improved, a lithium deposition risk is reduced, and safety performance is improved.
The surface of the negative electrode transition part 121b facing the positive electrode active material layer 111 is flush with the surface of the negative electrode main part 121a facing the positive electrode active material layer 111, so that when the negative electrode active material layer 121 is rolled, the stress consistency of the negative electrode sheet 12 can be improved, and the consistency of the negative electrode current collector 122 in compression and extension is improved.
Upon charging, the electrode assembly 10 as a whole expands and presses the case. By providing the negative conductive layer 123 in the embodiment of the present application, the thickness uniformity of the electrode assembly 10 can be improved, the expansion of the electrode assembly 10 can be more uniform, and the flatness of the outer surface of the case can be improved.
In some embodiments, the thickness of the negative electrode transition part 121b gradually decreases and the thickness of the negative electrode conductive layer 123 gradually increases in a direction away from the negative electrode main body part 121a, so that the total thickness of the negative electrode transition part 121b and the negative electrode conductive layer 123 is constant.
The total thickness of the negative electrode transition part 121b and the negative electrode conductive layer 123 is equal to the thickness of the negative electrode main body part 121a so that the surface of the negative electrode transition part 121b facing the positive electrode active material layer 111 is flush with the surface of the negative electrode main body part 121a facing the positive electrode active material layer 111.
The cross section of the negative electrode conductive layer 123 parallel to the stacking direction Y and the first direction X may be trapezoidal, triangular, or other shapes. The negative electrode transition portion 121b may have a trapezoidal, triangular, or other shape in cross section parallel to the stacking direction Y and the first direction X.
This embodiment can avoid the occurrence of a step at the junction of the negative electrode transition part 121b and the negative electrode main body part 121a, and reduce stress concentration at the time of roll pressing.
In some embodiments, the junction of the anode transition portion 121b and the anode edge portion 121c exceeds the cathode active material layer 111 in the first direction X. That is, in the first direction X, the junction of the negative electrode transition portion 121b and the negative electrode edge portion 121c exceeds the second end portion 111d.
This embodiment can reduce the risk of the negative electrode edge portion 121c and the positive electrode active material layer 111 overlapping in the stacking direction Y due to assembly errors. If the negative electrode edge portion 121c overlaps the positive electrode active material layer 111 in the stacking direction Y, a large gap between the negative electrode edge portion 121c and the positive electrode active material layer 111 may cause a risk of lithium deposition in the negative electrode edge portion 121c.
In some embodiments, the negative electrode transition portion 121b has a dimension in the first direction X greater than 5mm. Correspondingly, the size of the negative electrode conductive layer 123 in the first direction X is greater than 5mm.
The smaller the dimension of the negative electrode transition portion 121b in the first direction X, the higher the demand for the process. In this embodiment, the size of the negative electrode transition portion 121b in the first direction X is greater than 5mm, which can reduce the requirements for the process and improve the forming efficiency of the negative electrode sheet 12.
In some embodiments, the distance between the negative electrode transition part 121b and the positive electrode active material layer 111 in the stacking direction Y is D1, the distance between the negative electrode main part 121a and the positive electrode active material layer 111 in the stacking direction Y is D2, and D1 is equal to D2.
This embodiment can improve the uniformity of the gap between the positive electrode active material layer 111 and the negative electrode active material layer 121, improve wettability, reduce the risk of lithium deposition, and improve safety.
In some embodiments, the positive electrode active material layer 111 is a coating of equal thickness. The positive electrode active material layer 111 may be a coating layer having a uniform thickness because the positive electrode active material is an oil-based slurry and is less likely to form a protrusion on the edge during drying.
This embodiment can simplify the coating process of the positive electrode active material layer 111 and improve the molding efficiency of the positive electrode sheet 11.
In some embodiments, the negative electrode conductive layer 123 contains a negative electrode active material, so that ions extracted from the positive electrode active material layer 111 can also be embedded in the negative electrode conductive layer 123; that is, the negative electrode conductive layer 123 and the negative electrode transition part 121b can receive ions extracted from the positive electrode active material layer 111, and lithium deposition is less likely to occur in the negative electrode active material layer 121, thereby improving safety.
In some embodiments, the weight ratio of active material in the negative conductive layer 123 to the negative conductive layer 123 is greater than the weight ratio of active material in the negative transition 121b to the negative transition 121 b. In the present embodiment, the weight ratio of the active material in the negative electrode conductive layer 123 is increased by increasing the active material in the negative electrode conductive layer 123, and the capacity per unit area of the negative electrode conductive layer 123 is increased, so that the negative electrode conductive layer 123 can receive more ions, and the risk of lithium deposition is reduced.
In some embodiments, the gram capacity of the active material in the negative conductive layer 123 is greater than the gram capacity of the active material in the negative transition portion 121 b. The present embodiment increases the capacity per unit area of the negative electrode conductive layer 123 by increasing the gram capacity of the active material in the negative electrode conductive layer 123, so that the negative electrode conductive layer 123 can receive more ions, reducing the risk of lithium deposition.
In some embodiments, the particle size of the active material in the negative electrode conductive layer 123 is smaller than the particle size of the active material in the negative electrode transition part 121 b. The smaller the particle size of the active material, the more easily the ions diffuse, and the less easily they locally aggregate. This embodiment can make ions diffuse in the anode conductive layer 123 easier and not easily concentrate locally in the anode conductive layer 123 by reducing the particle diameter of the active material in the anode conductive layer 123, thereby reducing the risk of lithium deposition.
For example, in fig. 7, the protrusion formed on the end of the negative electrode edge portion 121c away from the negative electrode transition portion 121b is the protrusion formed on the negative electrode active material layer 121 during the drying process.
Fig. 8 is another partial cross-sectional view of the electrode assembly shown in fig. 5 taken along linebase:Sub>A-base:Sub>A.
As shown in fig. 8, in some embodiments, the positive electrode active material layer 111 includes a positive electrode main portion 111a and a positive electrode edge portion 111b sequentially arranged in the first direction X, and the thickness of the positive electrode main portion 111a is greater than that of the positive electrode edge portion 111 b. At least a part of the positive electrode edge portion 111b overlaps the negative electrode transition portion 121b in the stacking direction Y. The positive electrode tab 11 is provided with a positive electrode conductive layer 113 on the side of the positive electrode edge 111b away from the negative electrode active material layer 121, and the positive electrode conductive layer 113 is configured to support the positive electrode edge 111b so that the surface of the positive electrode edge 111b facing the negative electrode active material layer 121 is flush with the surface of the positive electrode body 111a facing the negative electrode active material layer 121.
The positive electrode conductive layer 113 is coated on the surface of the positive electrode collector 112, and the positive electrode edge portion 111b is located on the side of the positive electrode conductive layer 113 away from the positive electrode collector 112. The positive electrode edge 111b is a portion of the positive electrode active material layer 111 that overlaps with the positive electrode conductive layer 113 in the stacking direction Y. The positive electrode main body 111a is coated on the surface of the positive electrode collector 112. In the preparation of the positive electrode tab 11, the positive electrode conductive layer 113 may be coated on a predetermined area of the surface of the positive electrode current collector 112, and then the positive electrode active material layer 111 may be coated thereon.
The positive electrode conductive layer 113 may be a coating having a constant thickness or a coating having a varying thickness, and the present application is not limited thereto as long as the positive electrode conductive layer 113 can make the surface of the positive electrode edge portion 111b facing the negative electrode active material layer 121 flush with the surface of the positive electrode main portion 111a facing the negative electrode active material layer 121.
In this embodiment, the thickness of the positive electrode edge portion 111b can be reduced by providing the positive electrode conductive layer 113 to reduce ions that can be extracted from the positive electrode edge portion 111b, thereby reducing the risk of lithium deposition in the negative electrode transition portion 121 b. The positive electrode conductive layer 113 can support the positive electrode edge 111b, so that even if the thickness of the positive electrode edge 111b is reduced in the embodiment of the present application, the gap between the negative electrode transition portion 121b and the positive electrode edge 111b is not additionally increased, the wettability of the electrolyte is improved, the risk of lithium deposition is reduced, and the safety performance is improved
In some embodiments, the positive conductive layer 113 is a pure conductive coating, for example, the positive conductive layer 113 is a pure conductive coating composed of a binder and a conductive agent.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; 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 solutions described in the foregoing embodiments may be modified or some technical features may be equivalently replaced, but the modifications or the replacements do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims (11)
1. An electrode assembly is characterized by comprising a positive electrode piece and a negative electrode piece which are arranged in a superposition manner, wherein a positive active material layer of the positive electrode piece is arranged opposite to a negative active material layer of the negative electrode piece;
the negative active material layer comprises a negative main body part, a negative transition part and a negative edge part which are sequentially arranged along a first direction, the thickness of the negative main body part is greater than that of the negative transition part and that of the negative edge part, and the first direction is perpendicular to the stacking direction of the positive pole piece and the negative pole piece;
the anode edge portion exceeds the cathode active material layer in the first direction; in the stacking direction, at least a part of the negative electrode transition portion overlaps with the positive electrode active material layer, and at least a part of the negative electrode main body overlaps with the positive electrode active material layer;
the negative pole piece is provided with a negative pole conducting layer on one side, far away from the positive pole active material layer, of the negative pole transition part, and the negative pole conducting layer is used for supporting the negative pole transition part, so that the surface, facing the positive pole active material layer, of the negative pole transition part is flush with the surface, facing the positive pole active material layer, of the negative pole main body part.
2. The electrode assembly according to claim 1, wherein the thickness of the negative electrode transition portion is gradually decreased and the thickness of the negative electrode conductive layer is gradually increased in a direction away from the negative electrode main body portion so that the total thickness of the negative electrode transition portion and the negative electrode conductive layer is constant.
3. The electrode assembly according to claim 1, wherein a junction of the anode transition portion and the anode edge portion exceeds the cathode active material layer in the first direction.
4. The electrode assembly of claim 1, wherein a dimension of the negative electrode transition portion in the first direction is greater than 5mm.
5. The electrode assembly according to any one of claims 1 to 4, wherein a distance between the anode transition portion and the cathode active material layer in the stacking direction is D1, a distance between the anode main portion and the cathode active material layer in the stacking direction is D2, and D1 is equal to D2.
6. The electrode assembly of claim 5, wherein the positive electrode active material layer is a coating of uniform thickness.
7. The electrode assembly of claim 5,
the positive electrode active material layer comprises a positive electrode main body part and a positive electrode edge part which are sequentially arranged along the first direction, and the thickness of the positive electrode main body part is greater than that of the positive electrode edge part;
at least a portion of the positive electrode edge portion overlaps with the negative electrode transition portion in the overlapping direction;
the positive pole piece is equipped with the positive pole conducting layer in keeping away from of positive pole edge part negative pole active material layer one side, the positive pole conducting layer is used for supporting the positive pole edge part to make the surface of positive pole edge part towards the negative pole active material layer flush with the surface of positive pole main part towards the negative pole active material layer.
8. The electrode assembly of claim 1,
a weight ratio of active material in the negative conductive layer to the negative conductive layer is greater than a weight ratio of active material in the negative transition portion to the negative transition portion; or alternatively
The gram capacity of the active material in the negative conductive layer is greater than the gram capacity of the active material in the negative transition portion; or alternatively
The particle size of the active material in the negative electrode conductive layer is smaller than the particle size of the active material in the negative electrode transition portion.
9. A battery cell, comprising:
a housing;
the electrode assembly of any of claims 1-8, housed within the case.
10. A battery comprising a case and the battery cell according to claim 9, wherein the battery cell is accommodated in the case.
11. An electrical device comprising the battery of claim 10, wherein the battery is configured to provide electrical energy.
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| CN202121488354.7U CN215299297U (en) | 2021-06-30 | 2021-06-30 | Electrode assembly, battery cell, battery, and power consumption device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024021025A1 (en) * | 2022-07-29 | 2024-02-01 | 宁德时代新能源科技股份有限公司 | Electrode sheet, electrode assembly, battery cell, battery, and electric device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024021025A1 (en) * | 2022-07-29 | 2024-02-01 | 宁德时代新能源科技股份有限公司 | Electrode sheet, electrode assembly, battery cell, battery, and electric device |
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