CN117810357A - Negative electrode plate, preparation method thereof, electrode assembly, battery cell, battery and electricity utilization device - Google Patents
Negative electrode plate, preparation method thereof, electrode assembly, battery cell, battery and electricity utilization device Download PDFInfo
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- CN117810357A CN117810357A CN202211175113.6A CN202211175113A CN117810357A CN 117810357 A CN117810357 A CN 117810357A CN 202211175113 A CN202211175113 A CN 202211175113A CN 117810357 A CN117810357 A CN 117810357A
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- 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 provides a negative electrode plate, a preparation method thereof, an electrode assembly, a battery cell, a battery and an electricity utilization device, and relates to the technical field of batteries. The negative electrode plate comprises a negative electrode current collector, a negative electrode active material layer and a functional layer, wherein the negative electrode active material layer is arranged on at least one surface of the negative electrode current collector along the thickness direction, and the functional layer is convexly arranged on the surface of the negative electrode active material layer of at least part of the to-be-bent part. The functional layer includes a negative electrode active material and/or a conductive agent. And a functional layer is arranged on the surface of the negative electrode active material layer of the part to be bent, and can increase the CB value of the corresponding area of the battery, namely the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the area is increased, and/or electron and ion conducting channels are provided, so that accumulated lithium ions are rapidly dredged, and the occurrence of lithium precipitation is reduced or avoided. The functional layer can shorten the distance between the positive pole piece and the negative pole piece, reduce the liquid phase resistance of the battery and improve the electrochemical reaction kinetics.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a negative electrode plate, a preparation method of the negative electrode plate, an electrode assembly, a battery cell, a battery and an electric device.
Background
The lithium precipitation behavior in the battery is one of the main factors affecting the electrical performance and the safety performance of the battery, once the lithium precipitation occurs in the battery, the service life of the battery can be reduced, dendrites are easy to form along with the accumulation of the lithium precipitation amount, and the dendrites possibly puncture the diaphragm to further cause short circuit in the battery, so that potential safety hazards are caused.
Disclosure of Invention
In view of the above problems, the present application provides a negative electrode tab, a method for preparing the same, an electrode assembly, a battery cell, a battery, and an electric device, which can reduce or avoid lithium precipitation and improve the safety of the battery.
In a first aspect, the present application provides a negative electrode tab configured with a straight portion and a portion to be bent, the negative electrode tab including: the negative electrode active material layer is arranged on at least one surface of the negative electrode current collector along the thickness direction, and the functional layer is convexly arranged on the surface of the negative electrode active material layer of at least part of the part to be bent. The functional layer includes a negative electrode active material and/or a conductive agent.
In the technical scheme of the embodiment of the application, the functional layer is arranged on the surface of the part of the anode active material layer to be bent, when the functional layer comprises the anode active material, the CB value of the corresponding area of the battery can be increased, namely, the ratio of the anode active material capacity to the cathode active material capacity of the area is increased, so that the occurrence of lithium precipitation is reduced or avoided; when the functional layer comprises a conductive agent, the conductive agent can provide an electron and ion conduction channel to rapidly dredge accumulated lithium ions, so that occurrence of lithium precipitation is reduced or avoided; when the functional layer comprises a negative electrode active material and a conductive agent, the CB value of the corresponding area of the battery can be increased, and accumulated lithium ions can be rapidly dredged, so that the occurrence of lithium precipitation is reduced or avoided, and the safety and the service life of the battery are improved. In addition, the functional layer arranged on the surface of the negative electrode active material layer of the part to be bent can shorten the distance between the positive electrode plate and the negative electrode plate of the part to be bent, reduce the liquid phase resistance of the battery and improve the electrochemical reaction kinetics.
In some embodiments, the functional layer further comprises a film-forming material. The addition of the film-forming material to the functional layer 430 can improve the adhesion effect of the functional layer 430 and the anode active material layer 420.
In some embodiments, the functional layer includes 20wt% to 99wt% of the negative electrode active material and 1wt% to 80wt% of the film forming material. The CB value of the corresponding area of the battery and the bonding effect of the functional layer are regulated and controlled by regulating the ratio of the anode active material to the film forming material in the functional layer.
In some embodiments, the functional layer includes 20wt% to 99wt% conductive agent and 1wt% to 80wt% film forming material. The number of the electronic and ion conduction channels and the bonding effect of the functional layer are regulated and controlled by adjusting the duty ratio of the conductive agent and the film forming material in the functional layer.
In some embodiments, the functional layer includes 20wt% to 70wt% of the negative electrode active material, 20wt% to 70wt% of the conductive agent, and 10wt% to 60wt% of the film forming material. The CB value, the number of electronic and ionic conduction channels and the bonding effect of the functional layer in the corresponding area of the battery are regulated and controlled by regulating the proportion of the anode active material, the conductive agent and the film forming material in the functional layer.
In some embodiments, the negative electrode active material includes any one or more of a first carbon material, a lithiated metal alloy, and a lithiated oxide. Wherein the first carbon material comprises any one or more of hard carbon, soft carbon, activated carbon, graphite, silica carbon, and mesophase carbon microspheres. When the anode active material is selected from the materials, the functional layer can have more lithium ion active sites, and the CB value of the corresponding area of the battery can be better improved.
In some embodiments, the conductive agent includes a second carbon material and/or a conductive organic. Wherein the second carbon material comprises any one or more of carbon fiber, conductive carbon black, carbon nanotube and graphene. When the above-mentioned materials are selected as the conductive agent, the functional layer can be made to have a plurality of electron and ion conductive channels, and can rapidly dredge accumulated lithium ions.
In some embodiments, the functional layer has a porosity of 10% to 90%. By adjusting the porosity of the functional layer, the functional layer can be soaked with electrolyte and form a rapid lithium ion channel.
In a second aspect, the present application provides a method for preparing a negative electrode sheet in the foregoing embodiment, including: and forming a negative electrode active material layer on at least one surface of the negative electrode current collector along the thickness direction, and forming a functional layer on the surface of the negative electrode active material layer of at least part of the to-be-bent part.
In the technical scheme of the embodiment of the application, the preparation method of the negative electrode plate is simple and convenient, the functional layer is formed on the surface of the negative electrode active material layer of at least part of the to-be-bent part after the negative electrode active material layer is formed, and in the forming process of the functional layer, an intermittent coating process is not needed, so that the manufacturing difficulty is low.
In a third aspect, the present application provides an electrode assembly comprising: the positive pole piece and the negative pole piece in the embodiment are wound or folded to form a bending area and a flat area, and the flat area is connected with the bending area. The bending part is formed by winding or folding, the bending part is positioned in the bending area, and the straight part is positioned in the straight area.
In the technical scheme of this embodiment, the negative electrode active material layer surface in the area of partly buckling sets up the functional layer to can increase the regional CB value of battery correspondence, make the negative electrode active material capacity in this region increase with the positive electrode active material capacity's ratio, and/or provide electron and ion conduction channel, dredge accumulational lithium ion fast, and then reduce or avoid the emergence of lithium evolution. In addition, the functional layer arranged on the surface of the negative electrode active material layer in the partial bending region can shorten the distance between the positive electrode plate and the negative electrode plate in the partial bending region, reduce the liquid phase resistance of the battery and improve the electrochemical reaction kinetics.
In some embodiments, the positive electrode sheet and the negative electrode sheet are wound to form a winding structure, and the surface of the negative electrode active material layer on the outer side surface of the negative electrode current collector of at least part of the bending part is provided with a functional layer. For the electrode assembly with the winding structure, the outer side surface of the negative electrode current collector is smaller than the inner side surface of the corresponding positive electrode current collector, so that the negative electrode active material capacity of the outer side surface of the negative electrode current collector is smaller than the positive electrode active material capacity of the corresponding positive electrode current collector under normal conditions, lithium precipitation reaction is easy to occur, and the surface of the negative electrode active material layer of the outer side surface of the negative electrode current collector of at least part of the bending part is provided with a functional layer, so that the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the region can be increased, or an electron and ion conducting channel is provided in the region, and accumulated lithium ions are rapidly dredged, so that the lithium removal reaction of the active material layer in part of the bending region is reduced or avoided, and the safety and the service life of the battery are improved.
In some embodiments, the positive electrode sheet and the negative electrode sheet are wound to form a winding structure, the negative electrode sheet has a first bending part located at the innermost side of the winding structure, and the surface of the negative electrode active material layer on the outer side surface of the negative electrode current collector of the first bending part is provided with a functional layer. The first bending part positioned at the innermost side of the electrode assembly is the area which is most easy to generate lithium precipitation reaction, and the surface of the negative electrode active material layer on the outer side surface of the negative electrode current collector of the first bending part is provided with a functional layer, so that the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the area can be increased, or an electron and ion conducting channel is provided in the area, and accumulated lithium ions are rapidly dredged, thereby reducing or avoiding the lithium removal reaction of the active material layer in part of the bending area, improving the safety and the service life of the battery.
In some embodiments, the surface of the anode active material layer of the inner side surface of the anode current collector of the first bent portion is provided with a functional layer. The surface of the negative electrode active material layer on the inner side surface of the negative electrode current collector of the first bending part is provided with a functional layer, so that the curvature of the negative electrode plate in the region can be reduced, and the powder dropping condition of the negative electrode plate in the region can be improved.
In some embodiments, the negative electrode tab has a second bending portion, a third bending portion, a fourth bending portion, and a fifth bending portion sequentially adjacent to the first bending portion along a winding direction, and the second bending portion, the third bending portion, the fourth bending portion, and the fifth bending portion are each provided with a functional layer on a surface of the negative electrode active material layer of the outer side surface of the respective negative electrode current collector. The first bending part, the second bending part, the third bending part, the fourth bending part and the fifth bending part which are positioned at the innermost side of the electrode assembly are the regions where lithium precipitation reaction is most easy to occur, and the surfaces of the anode active material layers on the outer sides of the anode current collectors of the first bending part, the second bending part, the third bending part, the fourth bending part and the fifth bending part are provided with functional layers, so that the ratio of the anode active material capacity to the cathode active material capacity of the plurality of regions can be increased, or electron and ion conducting channels are provided in the plurality of regions, and accumulated lithium ions are rapidly dredged, thereby reducing or avoiding the lithium removal reaction of the active material layers in part of bending regions, improving the safety and the service life of the battery.
In some embodiments, the second, third, fourth, and fifth bent portions are each provided with a functional layer on a surface of the anode active material layer of the inner side surface of the respective anode current collector. The functional layers are arranged on the surfaces of the negative electrode active material layers on the inner sides of the negative electrode current collectors of the second bending part, the third bending part, the fourth bending part and the fifth bending part, so that the curvature of the negative electrode plates in the multiple areas can be reduced, and the powder dropping condition of the negative electrode plates in the multiple areas can be improved.
In some embodiments, the positive electrode sheet and the negative electrode sheet are wound to form a winding structure with a plurality of bending parts, and the functional layers corresponding to the plurality of bending parts are sequentially thinned along the winding direction. The possibility that the lithium-separating reaction easily occurs at the plurality of bending parts of the electrode assembly is sequentially reduced along the winding direction, or the severity of the lithium-separating reaction occurs is sequentially reduced, and the functional layers corresponding to the plurality of bending parts are sequentially thinned along the winding direction, so that the functional layers can correspond to the possibility of the lithium-separating reaction or the severity of the lithium-separating reaction, and the energy density of the whole battery is improved.
In some embodiments, the thickness difference of the functional layers corresponding to the two adjacent bending parts is 1 μm to 70 μm along the winding direction. The thickness adjustment of the functional layers corresponding to the bending parts is beneficial to improving lithium precipitation and guaranteeing the overall energy density of the battery.
In some embodiments, the positive electrode sheet and the negative electrode sheet are folded to form a lamination structure, the negative electrode sheet has a sixth bending portion covered by the positive electrode sheet, and a functional layer is disposed on a surface of the negative electrode active material layer on an outer side surface of the negative electrode current collector of the sixth bending portion. The sixth bending part positioned in the lamination structure is a region easy to generate lithium precipitation reaction, and the surface of the negative electrode active material layer on the inner side surface of the negative electrode current collector of the sixth bending part is provided with a functional layer, so that the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the region can be increased, or an electron and ion conducting channel is provided in the region, and accumulated lithium ions are rapidly dredged, so that the lithium removal reaction of the active material layer in part of the bending region is reduced or avoided, the safety and the service life of the battery are improved, and the energy density of the battery is ensured.
In some embodiments, the surface of the anode active material layer of the inner side surface of the anode current collector of the sixth bent portion is provided with a functional layer. The surface of the negative electrode active material layer on the inner side surface of the negative electrode current collector of the sixth bending part is provided with a functional layer, so that the curvature of the negative electrode plate in the region can be reduced, and the powder dropping condition of the negative electrode plate in the region can be improved.
In a fourth aspect, the present application provides a battery cell including the electrode assembly of the above-described embodiments.
In a fifth aspect, the present application provides a battery comprising the battery cell of the above embodiment.
In a sixth aspect, the present application provides an electrical device, which includes a battery in the above embodiment, where the battery is used to provide electrical energy.
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
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:
FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;
fig. 2 is an exploded view of a battery according to some embodiments of the present application;
fig. 3 is a schematic exploded view of a battery cell according to some embodiments of the present application;
FIG. 4 is a top view of a negative electrode tab according to some embodiments of the present application;
FIG. 5 is a cross-sectional view of a first negative electrode tab according to some embodiments of the present application;
FIG. 6 is a cross-sectional view of a second negative electrode tab according to some embodiments of the present application;
FIG. 7 is a cross-sectional view of a third negative electrode tab according to some embodiments of the present application;
fig. 8 is a schematic structural view of a first electrode assembly according to some embodiments of the present application;
fig. 9 is a schematic structural view of a second electrode assembly according to some embodiments of the present application;
FIG. 10 is a first partial schematic structural view of a first electrode assembly according to some embodiments;
FIG. 11 is a schematic view showing a second partial structure of a first electrode assembly according to some embodiments of the present application;
FIG. 12 is a schematic view of a third partial structure of a first electrode assembly according to some embodiments of the present application;
fig. 13 is a schematic structural view of a third electrode assembly according to some embodiments of the present application.
Reference numerals in the specific embodiments are as follows:
1000-vehicle;
100-cell; 200-a controller; 300-motor;
10-a box body; 11-a first part; 12-a second part; 13-accommodation space;
20-battery cells; 21-a housing; 22-electrode assembly; 23-electrode terminals; 24-pressure relief structure;
211-a housing; 212-a cover; 213-sealing the space; 400-negative pole piece; 401-a straight portion; 402-a portion to be bent; 403-a first bend; 404-a second bend; 405-a third bend; 406-fourth bends; 407-fifth bend; 408-sixth bends; 410-negative current collector; 420-a negative electrode active material layer; 430—a functional layer; 501-a flat zone; 502-a kink zone; 600-positive pole piece; 700-isolating 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", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the embodiments of the present application and for simplifying the description, rather than indicating or implying that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore 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 inventor notices that lithium ions can be inserted and extracted between the cathode and the anode of the lithium ion battery in the circulation process, when lithium ions migrate from the cathode to the anode, the cathode at the turning of the inner ring wraps the anode region due to the limitation of the battery structure, the capacity ratio of the cathode to the anode of the battery is insufficient, too many lithium ions of the cathode are inserted into the anode, and the anode has insufficient capacity to insert lithium ions, so that redundant lithium ions are separated out in the anode-wrapping region of the inner ring cathode, and the circulation performance of the battery is seriously reduced by anode lithium separation. Meanwhile, when lithium ion battery is separated, the separated lithium metal is very active and reacts with electrolyte, so that the self-heating initial temperature of the battery is reduced, the self-heating rate is increased, and the safety of the battery is seriously endangered. In addition, when lithium is severely separated, lithium crystals are formed on the surface of the anode by the deintercalated lithium ions, and the lithium crystals can pierce through the isolating film, so that adjacent cathodes and anodes are in short circuit thermal runaway.
The applicant researches find that the lithium precipitation phenomenon often occurs in the bending region of the electrode assembly, the anode pole piece and the cathode pole piece are easy to fall off in the winding or folding process of the anode active material in the bending region, so that the lithium intercalation position of the cathode active material layer of the cathode pole piece is further smaller than the lithium ion quantity which can be provided by the anode active material layer of the adjacent anode pole piece, and the lithium precipitation phenomenon easily occurs when the lithium ion battery is charged.
Based on the above consideration, in order to alleviate the problem of lithium precipitation of the battery, the inventors have conducted intensive studies to design a negative electrode tab, in which a functional layer is provided on the surface of a portion of a negative electrode active material layer to be bent, and when the functional layer includes a negative electrode active material, the CB value of a corresponding region of the battery can be increased, i.e., the ratio of the capacity of the negative electrode active material to the capacity of the positive electrode active material in the region is increased, thereby reducing or avoiding occurrence of lithium precipitation; when the functional layer comprises a conductive agent, the conductive agent can provide an electron and ion conduction channel to rapidly dredge accumulated lithium ions, so that occurrence of lithium precipitation is reduced or avoided; when the functional layer comprises a negative electrode active material and a conductive agent, the CB value of the corresponding area of the battery can be increased, and accumulated lithium ions can be rapidly dredged, so that the occurrence of lithium precipitation is reduced or avoided, and the safety and the service life of the battery are improved. In addition, the functional layer arranged on the surface of the negative electrode active material layer of the part to be bent can shorten the distance between the positive electrode plate and the negative electrode plate of the part to be bent, reduce the liquid phase resistance of the battery and improve the electrochemical reaction kinetics.
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. Batteries generally include a battery housing for enclosing one or more battery cells, which can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells.
The battery cells may include lithium ion battery cells. The battery cells may be cylindrical, flat, rectangular, or otherwise shaped, as well as the embodiments herein are not limited in this regard. The battery cells are generally classified into three types according to the packaging method: cylindrical battery cell, square battery cell and soft package battery cell.
The battery cell comprises an electrode assembly and electrolyte, wherein the electrode assembly consists of a positive electrode plate, a negative electrode plate and a separation film. The battery cell mainly relies on metal ions to move between the positive pole piece and the negative pole piece to work. The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer is coated on the surface of the positive electrode current collector, the positive electrode current collector without the positive electrode active material layer protrudes out of the positive electrode current collector coated with the positive electrode active material layer, and the positive electrode current collector without the positive electrode active material layer is used as a positive electrode lug. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate and the like. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer is coated on the surface of the negative electrode current collector, the negative electrode current collector without the negative electrode active material layer protrudes out of the negative electrode current collector coated with the negative electrode active material layer, and the negative electrode current collector without the negative electrode active material layer is used as a negative electrode lug. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the high current is passed without fusing, the number of positive electrode lugs is multiple and stacked together, and the number of negative electrode lugs is multiple and stacked together. The material of the separator may be Polypropylene (PP) or Polyethylene (PE). In addition, the electrode assembly may be a wound structure or a lamination structure, and the embodiment of the present application is not limited thereto.
The battery cell further includes a current collecting member for electrically connecting the tab of the battery cell and the electrode terminal to transfer electric energy from the electrode assembly to the electrode terminal, and to the outside of the battery cell through the electrode terminal; the plurality of battery cells are electrically connected through the bus component so as to realize series connection, parallel connection or series-parallel connection of the plurality of battery cells.
The battery also comprises a sampling terminal and a battery management system, wherein the sampling terminal is connected to the converging component and used for collecting information of the battery cells, such as voltage or temperature and the like. The sampling terminal transmits the collected information of the battery monomer to the battery management system, and when the battery management system detects that the information of the battery monomer exceeds a normal range, the output power of the battery can be limited to realize safety protection.
It is to be understood that the electric device to which the battery is applied described in the embodiments of the present application may take various forms, for example, a cellular phone, a portable device, a notebook computer, an electric car, a ship, a spacecraft, an electric toy, and an electric tool, etc., for example, a spacecraft including an airplane, a rocket, a space plane, and a spacecraft, etc., an electric toy including a stationary or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., an electric tool including a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, and an electric planer.
The battery cell and the battery described in the embodiments of the present application are not limited to the above-described electric devices, but may be applied to all electric devices using the battery cell and the battery, but for simplicity of description, the following embodiments are described by taking an electric automobile as an example.
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 provided in some embodiments of the present application. The battery 100 may include a case 10 and a battery cell 20, and the battery cell 20 is accommodated in the case 10. The case 10 is used for accommodating the battery cells 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 13 for accommodating the battery cell 20. The second portion 12 may be a hollow structure having one end opened, the first portion 11 is a plate-shaped structure, and the first portion 11 is covered on the opening side of the second portion 12 to form the case 10 having the accommodation space 13; the first portion 11 and the second portion 12 may also 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 to form the case 10 having the accommodation space 13. Of course, 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 number of the battery cells 20 may be one or more. If there are multiple battery cells 20, the multiple battery cells 20 may be connected in series or parallel or a series-parallel connection, where a series-parallel connection refers to that there are both series connection and parallel connection among the multiple battery cells 20. The plurality of battery cells 20 can be directly connected in series, in parallel or in series-parallel, and then the whole body formed by the plurality of battery cells 20 is accommodated in the box 10. The plurality of battery cells 20 may be connected in series or parallel or series-parallel to form a battery module, and the plurality of battery modules may be connected in series or parallel or series-parallel to form a whole and be accommodated in the case 10. The battery 100 may further include other structures, for example, electrical connection between the plurality of battery cells 20 may be achieved through a bus bar member to achieve parallel connection or series-parallel connection of 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.
Referring to fig. 3, fig. 3 is an exploded view of the battery cell 20 shown in fig. 2. The battery cell 20 refers to the smallest unit constituting the battery 100. As shown in fig. 3, the battery cell 20 may include a case 21 and an electrode assembly 22, and the electrode assembly 22 is received in the case 21. In some embodiments, the housing 21 may also be used to contain an electrolyte, such as an electrolyte solution. The housing 21 may take a variety of structural forms.
The housing 21 may include a case 211 and a cover 212.
The case 211 is an assembly for coupling the cover 212 to form an inner sealed space 213 of the battery cell 20, wherein the formed sealed space 213 may be used to accommodate the electrode assembly 22, the electrolyte, and other components. The case 211 and the cover 212 may be separate members, and an opening may be provided in the case, and the internal environment of the battery cell 20 may be formed by closing the opening with the cover 212 at the opening. However, the cover 212 and the housing 211 may be integrated, specifically, the cover 212 and the housing 211 may form a common connection surface before other components are put into the housing, and when the interior of the housing 211 needs to be sealed, the cover 212 is covered with the housing 211. The housing 211 may be of various shapes and various sizes, such as rectangular parallelepiped, cylindrical, hexagonal prism, etc. Specifically, the shape of the case 211 may be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 211 may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in the embodiment of the present application.
The cover 212 refers to a member that is covered at the opening of the case 211 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the cover 212 may be adapted to the shape of the housing 211 to fit the housing 211. In some embodiments, the cover 212 may be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the cover 212 is not easy to deform when being extruded and collided, so that the battery cell 20 can have a higher structural strength, and the safety performance can be improved. The material of the cover 212 may be other materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in the embodiment of the present application. In some embodiments, an insulator may also be provided on the inside of the cover 212, which may be used to isolate electrical connection components within the housing 211 from the cover 212 to reduce the risk of short circuits. By way of example, the insulation may be plastic, rubber, or the like.
The cover 212 may be provided with functional components such as the electrode terminals 23. The electrode terminal 23 is mounted on the cover 212. The electrode terminals 23 are electrically connected with the electrode assembly 22 to output electric energy generated from the battery cells 20. For example, the electrode terminal 23 and the electrode assembly 22 may be electrically connected through a switching tab (not shown).
The battery cell 20 may further comprise a pressure relief structure 24, the pressure relief structure 24 being adapted to relieve the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value. By way of example, the pressure relief structure 24 may be a component such as an explosion-proof valve, an explosion-proof flap, a gas valve, a pressure relief valve, or a safety valve.
In assembling the battery cell 20, the electrode assembly 22 may be placed in the case 211, the case 211 may be filled with an electrolyte, and the cover 212 may be then covered on the opening of the case 211.
Referring now to fig. 4-6, fig. 4 is a top view of a negative electrode tab 400 according to some embodiments of the present application, fig. 5 is a cross-sectional view of a first negative electrode tab 400 according to some embodiments of the present application, and fig. 6 is a cross-sectional view of a second negative electrode tab 400 according to some embodiments of the present application; fig. 7 is a cross-sectional view of a third negative electrode tab 400 according to some embodiments of the present application.
The application provides a negative pole piece 400, negative pole piece 400 is furnished with straight portion 401 and waits kink 402, and negative pole piece 400 includes: the negative electrode current collector 410, the negative electrode active material layer 420 and the functional layer 430, wherein the negative electrode active material layer 420 is disposed on at least one surface of the negative electrode current collector 410 along the thickness direction, and the functional layer 430 is protruding on the surface of the negative electrode active material layer 420 of at least part of the portion to be bent 402. The functional layer 430 includes a negative electrode active material and/or a conductive agent.
The flat portion 401 is a portion of the negative electrode tab 400 that forms a flat region 501 after being wound or bent.
The portion to be bent 402 is a portion of the negative electrode tab 400 that is wound or bent to form a bending region 502.
The functional layer 430 is a layered structure that is disposed on at least a portion of the surface of the anode active material layer 420 of the portion to be bent 402 and can provide lithium ion active sites or provide electron and ion channels.
The negative electrode active material is a component capable of lithium ion active sites.
The conductive agent is a component capable of providing an electron and ion channel.
As an example, the functional layer 430 may include a negative electrode active material, not include a conductive agent; or may include a conductive agent, not including a negative electrode active material; or may include both the anode active material and the conductive agent.
The functional layer 430 is disposed on the surface of the negative electrode active material layer 420 of a portion of the portion to be bent 402, and when the functional layer 430 includes a negative electrode active material, the CB value of the corresponding region of the battery can be increased, that is, the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the region is increased, so that occurrence of lithium precipitation is reduced or avoided; when the functional layer 430 includes a conductive agent, the conductive agent can provide electron and ion conduction channels to rapidly channel accumulated lithium ions, thereby reducing or avoiding occurrence of lithium precipitation; when the functional layer 430 includes the negative active material and the conductive agent, it is possible to increase a CB value of a corresponding region of the battery and also to rapidly drain accumulated lithium ions, thereby reducing or preventing occurrence of lithium precipitation, improving safety and life span of the battery. In addition, the functional layer 430 provided on the surface of the negative electrode active material layer 420 of a portion of the portion to be bent 402 can shorten the distance between the positive electrode tab 600 and the negative electrode tab 400 of a portion to be bent 402, the liquid phase resistance of the battery is reduced, and the electrochemical reaction kinetics is improved.
Referring to fig. 4 and 5, the anode active material layer 420 is disposed on only one surface of the anode current collector 410 in the thickness direction, and the functional layer 430 is disposed on the surface of one anode active material layer 420.
Referring to fig. 4 and 6, the anode active material layer 420 is disposed on both sides of the anode current collector 410 in the thickness direction, and the functional layer 430 is disposed on the surface of one anode active material layer 420.
Referring to fig. 4 and 7, the anode active material layers 420 are disposed on both sides of the anode current collector 410 in the thickness direction, and the functional layers 430 are disposed on the surfaces of the two anode active material layers 420.
Optionally, functional layer 430 further comprises a film-forming material, according to some embodiments of the present application.
The addition of the film-forming material to the functional layer can improve the adhesion effect of the functional layer and the anode active material layer.
Optionally, according to some embodiments of the present application, the functional layer 430 includes 20wt% to 99wt% of the anode active material and 1wt% to 80wt% of the film forming material.
The film-forming material is a component that facilitates formation of a solution or slurry of the anode active material to form a thin film structure after removal of the solvent.
Optionally, the film-forming material includes any one or more of polyvinylidene fluoride (Polyvinylidene difluoride, PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (Carboxymethyl cellulose, CMC), styrene-butadiene rubber (Polymerized styrene butadiene rubber, SBR), polypropylene (PP), polyethylene (PE), polyacrylonitrile (PAN), polyacrylic acid (PAA), and polyvinyl alcohol (Polyvinyl alcohol, PVA).
As an example, the functional layer 430 may include 20wt% of the anode active material and 80wt% of the film forming material, or may include 30wt% of the anode active material and 70wt% of the film forming material, or may include 40wt% of the anode active material and 60wt% of the film forming material, or may include 50wt% of the anode active material and 50wt% of the film forming material, or may include 60wt% of the anode active material and 40wt% of the film forming material, or may include 70wt% of the anode active material and 30wt% of the film forming material, or may include 80wt% of the anode active material and 20wt% of the film forming material, or may include 90wt% of the anode active material and 10wt% of the film forming material, or may include 99wt% of the anode active material and 1wt% of the film forming material.
The CB value of the corresponding region of the battery and the adhesive effect of the functional layer 430 are regulated by adjusting the duty ratio of the negative electrode active material and the film forming material in the functional layer 430.
Optionally, functional layer 430 includes 20wt% to 99wt% conductive agent and 1wt% to 80wt% film forming material, according to some embodiments of the present application.
As an example, the functional layer 430 may include 20wt% of a conductive agent and 80wt% of a film-forming material, or may include 30wt% of a conductive agent and 70wt% of a film-forming material, or may include 40wt% of a conductive agent and 60wt% of a film-forming material, or may include 50wt% of a conductive agent and 50wt% of a film-forming material, or may include 60wt% of a conductive agent and 40wt% of a film-forming material, or may include 70wt% of a conductive agent and 30wt% of a film-forming material, or may include 80wt% of a conductive agent and 20wt% of a film-forming material, or may include 90wt% of a conductive agent and 10wt% of a film-forming material, or may include 99wt% of a conductive agent and 1wt% of a film-forming material.
The number of electron and ion conduction channels and the bonding effect of the functional layer 430 are regulated by adjusting the ratio of the conductive agent to the film forming material in the functional layer 430.
Optionally, according to some embodiments of the present application, the functional layer 430 includes 20wt% to 70wt% of the anode active material, 20wt% to 70wt% of the conductive agent, and 10wt% to 60wt% of the film forming material.
As an example, the functional layer 430 may include 20wt% of a negative electrode active material, 20wt% of a conductive agent, and 60wt% of a film forming material, or may include 30wt% of a negative electrode active material, 30wt% of a conductive agent, and 40wt% of a film forming material, or may include 40wt% of a negative electrode active material, 40wt% of a conductive agent, and 20wt% of a film forming material, or may include 70wt% of a negative electrode active material, 20wt% of a conductive agent, and 10wt% of a film forming material, or may include 20wt% of a negative electrode active material, 70wt% of a conductive agent, and 10wt% of a film forming material, or may include 50wt% of a negative electrode active material, 30wt% of a conductive agent, and 20wt% of a film forming material.
The CB value, the number of electron and ion conduction channels, and the bonding effect of the functional layer 430 in the corresponding region of the battery are regulated by adjusting the ratios of the anode active material and the conductive agent and the film forming material in the functional layer 430.
According to some embodiments of the present application, optionally, the negative electrode active material includes any one or more of a first carbon material, a lithiated metal alloy, and a lithiated oxide.
The first carbon material comprises any one or more of hard carbon, soft carbon, activated carbon, graphite, silica carbon, and mesophase carbon microbeads.
The lithiable metal includes any one or more of Al, mg, and Zn.
The lithiated metal alloys include LiAl alloys and/or MgAl alloys.
The lithiable oxide includes ZnO and/or MnO.
When the above materials are selected for the negative electrode active material, the functional layer 430 can be made to have more lithium ion active sites, and the CB value of the corresponding region of the battery can be better improved.
Optionally, according to some embodiments of the present application, the conductive agent comprises a second carbon material and/or a conductive organic.
The second carbon material includes any one or more of carbon fiber, conductive carbon black, carbon nanotube, and graphene.
Optionally, the carbon nanotubes comprise single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
Optionally, the graphene comprises any one or more of single-layer graphene, oligolayer graphene, few-layer graphene, multi-layer graphene, and three-dimensional graphene.
The conductive organic matter comprises polypyrrole and/or polythiophene.
When the above-described materials are selected as the conductive agent, the functional layer 430 can be made to have a plurality of electron and ion conductive channels, and can rapidly channel accumulated lithium ions.
Optionally, the functional layer 430 has a porosity of 10% to 90%, according to some embodiments of the present application.
As an example, the porosity of the functional layer 430 may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%.
By adjusting the porosity of the functional layer 430, the functional layer 430 can be made to wet with an electrolyte and form a rapid lithium ion channel.
According to some embodiments of the present application, the present application further provides a method for preparing the negative electrode tab 400 in the above embodiments, which includes: a negative electrode active material layer 420 is formed on at least one surface of the negative electrode current collector 410 in the thickness direction, and a functional layer 430 is formed on the surface of the negative electrode active material layer 420 of at least part of the portion 402 to be bent.
The preparation method of the negative electrode plate 400 is simple and convenient, the functional layer 430 is formed on the surface of the negative electrode active material layer 420 of at least part of the to-be-bent part 402 after the negative electrode active material layer 420 is formed, and in the forming process of the functional layer 430, an intermittent coating process is not needed, so that the manufacturing difficulty is low.
Referring to fig. 8 to 12, fig. 8 is a schematic structural view of a first electrode assembly 22 according to some embodiments of the present application, fig. 9 is a schematic structural view of a second electrode assembly 22 according to some embodiments of the present application, fig. 10 is a schematic structural view of a third electrode assembly 22 according to some embodiments of the present application, fig. 11 is a schematic structural view of a first partial structure of the first electrode assembly 22 according to some embodiments of the present application, and fig. 12 is a schematic structural view of a second partial structure of the first electrode assembly 22 according to some embodiments of the present application.
The present application also provides an electrode assembly 22 comprising: the positive electrode sheet 600 and the negative electrode sheet 400 in the above embodiments are wound or folded to form a bending region 502 and a flat region 501, and the flat region 501 is connected to the bending region 502. The to-be-bent portion 402 is wound or folded to form a bent portion, the bent portion is located in the bent area 502, and the flat portion 401 is located in the flat area 501.
Referring to fig. 8, the positive electrode sheet 600, the negative electrode sheet 400 and the separator 700 are wound to form an electrode assembly 22 having a winding structure, wherein a flat region 501 is formed in the middle of the electrode assembly 22, and two ends of the flat region 501 are respectively provided with a bending region 502. And the closer the positive electrode sheet 600 and the negative electrode sheet 400 positioned in the bending region 502 are to the center of the winding structure, the larger the curvatures of the positive electrode sheet 600 and the negative electrode sheet 400 after winding are.
Referring to fig. 9, the positive electrode sheet 600, the negative electrode sheet 400 and the separator 700 are folded to form an electrode assembly 22 with a laminated structure, wherein a flat region 501 is formed in the middle of the electrode assembly 22, and a plurality of bending regions 502 are formed at two ends of the flat region 501. Each inflection zone 502 includes a pole piece on the inside and on the outside. The curvatures of each of the positive electrode tab 600 and the negative electrode tab 400 positioned at the inner side after being folded are the same, and the curvatures of each of the positive electrode tab 600 and the negative electrode tab 400 positioned at the outer side after being folded at the bending region 502 are the same.
Referring to fig. 10, the bent portion includes a negative electrode current collector 410, a negative electrode active material layer 420 disposed only on an outer side surface of the negative electrode current collector 410, and a functional layer 430 disposed on a surface of the negative electrode active material layer 420.
Referring to fig. 11, the bent portion includes a negative electrode current collector 410, a negative electrode active material layer 420 disposed on the outer side and the inner side of the negative electrode current collector 410, and a functional layer 430 disposed on the surface of the negative electrode active material layer 420 on the outer side of the negative electrode current collector 410.
The functional layer 430 is disposed on the surface of the anode active material layer 420 in the partial bending region 502, so as to increase the CB value of the corresponding region of the battery, i.e. increase the ratio of the anode active material capacity to the cathode active material capacity in the region, and/or provide electron and ion conduction channels, so as to rapidly dredge accumulated lithium ions, thereby reducing or avoiding occurrence of lithium precipitation. In addition, the functional layer 430 disposed on the surface of the anode active material layer 420 in the partial bending region 502 can shorten the distance between the anode sheet 600 and the cathode sheet 400 in the partial bending region 502, reduce the liquid phase resistance of the battery, and improve the electrochemical reaction kinetics.
Optionally, according to some embodiments of the present application, the positive electrode tab 600 and the negative electrode tab 400 are wound to form a winding structure, and the surface of the negative electrode active material layer 420 on the outer side surface of the negative electrode current collector 410 of at least part of the bent portion is provided with a functional layer 430.
The outer side of the negative electrode current collector 410 is a convex surface of the negative electrode current collector 410 after being bent.
For the electrode assembly 22 of the winding structure, the outer side surface of the negative electrode current collector 410 is smaller than the inner side surface of the corresponding positive electrode current collector, which results in that the negative electrode active material capacity of the outer side surface of the negative electrode current collector 410 is smaller than the positive electrode active material capacity of the corresponding positive electrode current collector under normal conditions, lithium precipitation reaction is very easy to occur, and the surface of the negative electrode active material layer 420 of the outer side surface of the negative electrode current collector 410 at least in part of the bending part is provided with the functional layer 430, so that the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the region can be increased, or electron and ion conduction channels are provided in the region, and accumulated lithium ions are rapidly dredged, thereby reducing or avoiding the lithium removal reaction of the active material layer in part of the bending region 502, improving the safety and service life of the battery.
Optionally, according to some embodiments of the present application, the positive electrode tab 600 and the negative electrode tab 400 are wound to form a winding structure, the negative electrode tab 400 has a first bending portion 403 located at an innermost side of the winding structure, and a surface of the negative electrode active material layer 420 on an outer side of the negative electrode current collector 410 of the first bending portion 403 is provided with a functional layer 430.
The first bending portion 403 has a structure with the largest bending curvature of the negative electrode tab 400.
The first bending part 403 located at the innermost side of the electrode assembly 22 is the region where the lithium precipitation reaction is most likely to occur, and the functional layer 430 is disposed on the surface of the negative electrode active material layer 420 on the outer side surface of the negative electrode current collector 410 of the first bending part 403, so that the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the region can be increased, or the electron and ion conducting channels are provided in the region, so that the accumulated lithium ions are rapidly dredged, thereby reducing or avoiding the delithiation reaction of the active material layer in part of the bending region 502, improving the safety and the service life of the battery.
Optionally, referring to fig. 12, a third partial structural schematic view of the first electrode assembly 22 according to some embodiments of the present application is shown. The surface of the anode active material layer 420 on the inner side surface of the anode current collector 410 of the first bent portion 403 is provided with a functional layer 430.
The inner side of the negative electrode current collector 410 is a concave surface of the negative electrode current collector 410 after bending.
The surface of the negative electrode active material layer 420 on the inner side surface of the negative electrode current collector 410 of the first bending part 403 is provided with a functional layer 430, so that the curvature of the negative electrode tab 400 in the region can be reduced, and the powder dropping condition of the negative electrode tab 400 in the region can be improved.
Optionally, referring to fig. 13, a schematic structural view of a third electrode assembly 22 according to some embodiments of the present application is shown in fig. 13. Along the winding direction, the negative electrode tab 400 has a second bent portion 404, a third bent portion 405, a fourth bent portion 406, and a fifth bent portion 407 that are sequentially adjacent to the first bent portion 403, and the second bent portion 404, the third bent portion 405, the fourth bent portion 406, and the fifth bent portion 407 are each provided with a functional layer 430 on the surface of the negative electrode active material layer 420 on the outer side surface of the respective negative electrode current collector 410.
The second bending portion 404 has a second largest bending curvature of the negative electrode tab 400, and a straight portion 401 is disposed between the second bending portion 404 and the first bending portion 403.
The third bending portion 405 is a structure with a third largest bending curvature of the negative electrode tab 400, and a straight portion 401 is disposed between the third bending portion 405 and the second bending portion 404.
The fourth bending portion 406 is a structure with a fourth bending curvature of the negative electrode tab 400, and a straight portion 401 is disposed between the fourth bending portion 406 and the third bending portion 405.
The fifth bending portion 407 has a structure with a fifth largest bending curvature of the negative electrode tab 400, and a straight portion 401 is disposed between the fifth bending portion 407 and the fourth bending portion 406.
The first, second, third, fourth and fifth bent portions 403, 404, 405, 406 and 407 positioned at the innermost side of the electrode assembly 22 are regions where lithium precipitation reaction is most likely to occur, and the surface of the anode active material layer 420 at the outer side of the anode current collector 410 of the first, second, third, fourth and fifth bent portions 403, 405, 406 and 407 is provided with a functional layer 430, which can increase the ratio of the anode active material capacity to the cathode active material capacity of the regions or provide electron and ion conductive channels at the regions, rapidly dredge accumulated lithium ions, thereby reducing or avoiding the delithiation reaction of the active material layer at part of the bent regions 502, improving the safety and the service life of the battery.
According to some embodiments of the present application, optionally, each of the second bent portion 404, the third bent portion 405, the fourth bent portion 406, and the fifth bent portion 407 is provided with a functional layer 430 on a surface of the anode active material layer 420 of the inner side surface of the respective anode current collector 410.
The functional layer 430 is disposed on the surface of the negative electrode active material layer 420 on the inner side surface of the negative electrode current collector 410 of the second, third, fourth and fifth bent portions 404, 405, 406 and 407, so as to reduce the curvature of the negative electrode tab 400 in the plurality of regions and improve the powder dropping condition of the negative electrode tab 400 in the plurality of regions.
Optionally, according to some embodiments of the present application, the positive electrode sheet 600 and the negative electrode sheet 400 are wound to form a winding structure with a plurality of bending portions, and the functional layers 430 corresponding to the plurality of bending portions are sequentially thinned along the winding direction.
The possibility of the reaction in which lithium is easily separated from the plurality of bent portions of the electrode assembly 22 is sequentially reduced or the severity of the lithium separation reaction is sequentially reduced in the winding direction, and the functional layers 430 corresponding to the plurality of bent portions are sequentially thinned in the winding direction so as to correspond to the possibility of the lithium separation reaction or the severity of the lithium separation reaction, which is advantageous in improving the energy density of the battery as a whole.
According to some embodiments of the present application, optionally, the thickness difference of the functional layers 430 corresponding to the adjacent two bending portions is 1 μm to 70 μm along the winding direction.
As an example, the thickness difference of the functional layers 430 corresponding to the adjacent two bent portions may be 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, or 70 μm.
The thickness adjustment of the functional layer 430 corresponding to the plurality of bent portions is advantageous in improving lithium precipitation and ensuring the overall energy density of the battery.
Alternatively, the functional layer 430 has a thickness of 0.1 μm to 200 μm.
As an example, the thickness of the functional layer 430 may be 0.1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, or 200 μm.
Optionally, according to some embodiments of the present application, the positive electrode tab 600 and the negative electrode tab 400 are folded to form a lamination structure, the negative electrode tab 400 has a sixth bending portion 408 covered by the positive electrode tab 600, and a surface of the negative electrode active material layer 420 on an outer side surface of the negative electrode current collector 410 of the sixth bending portion 408 is provided with a functional layer 430.
Since the curvature of the curve formed by folding each of the negative electrode tabs 400 located at the outer side of the folded region 502 of the lamination stack electrode assembly 22 is the same, the sixth folded portion 408 may be a folded portion at an arbitrary position.
The sixth bending part 408 of the lamination structure is a region where lithium precipitation reaction is easy to occur, and the surface of the negative electrode active material layer 420 on the inner side surface of the negative electrode current collector 410 of the sixth bending part 408 is provided with the functional layer 430, so that the ratio of the negative electrode active material capacity to the positive electrode active material capacity of the region can be increased, or an electron and ion conducting channel is provided in the region, and accumulated lithium ions are rapidly dredged, so that the lithium removal reaction of the active material layer in a part of the bending region 502 is reduced or avoided, the safety and the service life of the battery are improved, and the energy density of the battery is ensured.
According to some embodiments of the present application, optionally, the surface of the anode active material layer 420 of the inner side surface of the anode current collector 410 of the sixth bent portion 408 is provided with a functional layer 430.
The functional layer 430 is disposed on the surface of the negative electrode active material layer 420 on the inner side surface of the negative electrode current collector 410 of the sixth bending portion 408, so as to reduce the curvature of the negative electrode tab 400 in the region and improve the powder dropping condition of the negative electrode tab 400 in the region.
The electrode assemblies of the present application are described in further detail below in conjunction with examples, and the structures and parameters of the electrode assemblies of examples 1 to 38 and comparative examples 1 to 3 are shown in tables 1 to 3.
TABLE 1 Structure and parameters of electrode Assembly with functional layer as negative electrode active Material
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TABLE 2 Structure and parameters of electrode Assembly with functional layer as conductive agent
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TABLE 3 Structure and parameters of electrode Assembly with functional layers of negative electrode active Material and conductive agent
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Test examples
Batteries were fabricated using the electrode assemblies of examples 1 to 38 and comparative examples 1 to 3 of the present application, and the capacity retention and the bent portion positive electrode sheet and negative electrode sheet distances (gap) of the fabricated batteries were measured, respectively, and the test results are shown in tables 4 to 6.
The preparation method of the battery comprises the following steps:
and winding the positive pole piece, the negative pole piece and the isolating film to form a battery, wherein the designs of electrolyte, an aluminum plastic film and the like are consistent.
Adopting a new-Wei capacity test cabinet, and carrying out capacity cycle test on the prepared battery according to the following steps: (1) full charge to charge limit voltage of 0.33C, initial capacity Cap is tested according to discharge limit voltage of 1.0C 0 The method comprises the steps of carrying out a first treatment on the surface of the (2) At 25 ℃ +/-5 ℃, the battery is fully charged to the charging limit voltage according to 1.5 DEG CThe cut-off current is 0.05 ℃ and the mixture is left for 5 to 10 minutes; (3) discharging the battery to a discharge cut-off voltage according to a discharge mode of 1.0 ℃ at 25+/-5 ℃ and placing the battery for 5-10 min; (4) repeating the steps (2) - (3) for 50 times. And comparing the capacity retention rate after circulation with the full charge disassembly interface.
The method for testing the distance (gap) between the positive pole piece and the negative pole piece of the bent part of the battery is as follows:
and shooting the distance Gap between the positive pole piece and the negative pole piece of the bending part of the battery by adopting X-ray CT.
Table 4 test results of examples 1 to 13 and comparative example 1
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Table 5 test results of examples 14 to 25 and comparative example 2
| Project | Capacity retention (%) | Gap |
| Example 14 | 94％ | <50μm |
| Example 15 | 91％ | <50μm |
| Implementation of the embodimentsExample 16 | 93％ | <50μm |
| Example 17 | 94％ | <50μm |
| Example 18 | 94％ | <50μm |
| Example 19 | 93％ | <50μm |
| Example 20 | 94％ | <50μm |
| Example 21 | 94％ | <50μm |
| Example 22 | 94％ | <50μm |
| Example 23 | 95％ | <50μm |
| Example 24 | 94％ | <50μm |
| Example 25 | 94％ | <50μm |
| Comparative example 2 | <90％ | <200μm |
Table 6 test results of examples 26 to 38 and comparative example 3
| Project | Capacity retention (%) | Gap |
| Example 26 | 93％ | <50μm |
| Example 27 | 91％ | <50μm |
| Example 28 | 94％ | <50μm |
| Example 29 | 93％ | <50μm |
| Example 30 | 95％ | <50μm |
| Example 31 | 95％ | <50μm |
| Example 32 | 93％ | <50μm |
| Example 33 | 93％ | <50μm |
| Example 34 | 94％ | <50μm |
| Example 35 | 94％ | <50μm |
| Example 36 | 94％ | <50μm |
| Example 37 | 93％ | <50μm |
| Example 38 | 94％ | <50μm |
| Comparative example 3 | <90％ | <200μm |
As is clear from table 4, in examples 1 to 13, the functional layer was provided on the surface of the anode active material layer on the outer surface of the anode current collector in the first bent portion, or the first, second, third, fourth, and fifth bent portions, or the sixth bent portion, and the functional layer was made of the anode active material, so that the occurrence of lithium precipitation was reduced or avoided, and the capacity retention rate of the battery after 50 cycles was 93% or more, and was 97% at the maximum, and the Gap value was < 50 μm. In contrast, comparative example 1 had no functional layer, and the capacity retention rate of the battery after 50 cycles was 90% or less, with Gap value < 200. Mu.m.
As is clear from table 5, in examples 14 to 25, the functional layer was provided on the surface of the negative electrode active material layer on the outer surface of the negative electrode current collector in the first bent portion, or the first, second, third, fourth, and fifth bent portions, or the sixth bent portion, and the functional layer included a conductive agent, so that the occurrence of lithium precipitation was reduced or avoided, and the capacity retention rate after 50 cycles of the battery was 91% or more, and was 95% at most, with Gap value < 50 μm. In contrast, comparative example 2 has no functional layer, and the capacity retention rate of the battery after 50 cycles is 90% or less, with Gap value < 200 μm.
As is clear from table 6, in examples 26 to 38, the functional layer including the negative electrode active material and the conductive agent was provided on the surface of the negative electrode active material layer on the outer surface of the negative electrode current collector in the first bent portion, the first, second, third, fourth, and fifth bent portions, or the sixth bent portion, so that the occurrence of lithium precipitation was reduced or avoided, and the capacity retention rate after 50 cycles of the battery was 91% or more, and was 95% or less, and the Gap value was < 50 μm. And comparative example 3 has no functional layer, the capacity retention rate of the battery after 50 cycles is below 90%, and the Gap value is < 200 μm.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting 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 scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the embodiments, and are intended to be included within the scope of the claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.
Claims (22)
1. The negative electrode plate is characterized by being provided with a straight part and a part to be bent, wherein the negative electrode plate comprises a negative electrode current collector, a negative electrode active material layer and a functional layer, the negative electrode active material layer is arranged on at least one surface of the negative electrode current collector along the thickness direction, and the functional layer is convexly arranged on the surface of at least part of the negative electrode active material layer of the part to be bent;
the functional layer includes a negative electrode active material and/or a conductive agent.
2. The negative electrode tab of claim 1, wherein the functional layer further comprises a film-forming material.
3. The negative electrode tab of claim 1, wherein the functional layer comprises 20wt% to 99wt% of the negative electrode active material and 1wt% to 80wt% of a film forming material.
4. The negative electrode tab of claim 1, wherein the functional layer comprises 20wt% to 99wt% of the conductive agent and 1wt% to 80wt% of the film forming material.
5. The negative electrode tab of claim 1, wherein the functional layer comprises 20wt% to 70wt% of the negative electrode active material, 20wt% to 70wt% of the conductive agent, and 10wt% to 60wt% of the film forming material.
6. The anode electrode tab according to any one of claims 1 to 5, wherein the anode active material comprises any one or more of a first carbon material, a lithiated metal alloy, and a lithiated oxide;
wherein the first carbon material comprises any one or more of hard carbon, soft carbon, activated carbon, graphite, silica carbon and mesophase carbon microspheres.
7. The negative electrode tab of any one of claims 1-5, wherein the conductive agent comprises a second carbon material and/or a conductive organic;
wherein the second carbon material comprises any one or more of carbon fiber, conductive carbon black, carbon nanotube and graphene.
8. The negative electrode tab of claim 1, wherein the functional layer has a porosity of 10% to 90%.
9. A method of producing the negative electrode sheet according to any one of claims 1 to 8, characterized in that the method of producing the negative electrode sheet comprises: and forming the negative electrode active material layer on at least one surface of the negative electrode current collector along the thickness direction, and forming the functional layer on the surface of the negative electrode active material layer of at least part of the to-be-bent part.
10. An electrode assembly, the electrode assembly comprising: the positive electrode plate and the negative electrode plate of any one of claims 1-8, wherein the positive electrode plate and the negative electrode plate are wound or folded to form a bending region and a flat region, and the flat region is connected with the bending region;
the to-be-bent part is wound or folded to form a bent part, the bent part is positioned in the bent area, and the flat part is positioned in the flat area.
11. The electrode assembly according to claim 10, wherein the positive electrode tab and the negative electrode tab are wound to form a wound structure, and a functional layer is provided on a surface of the negative electrode active material layer of an outer side surface of the negative electrode current collector of at least part of the bent portion.
12. The electrode assembly according to claim 10, wherein the positive electrode sheet and the negative electrode sheet are wound to form a wound structure, the negative electrode sheet has a first bent portion located at an innermost side of the wound structure, and a surface of the negative electrode active material layer of an outer side surface of the negative electrode current collector of the first bent portion is provided with the functional layer.
13. The electrode assembly according to claim 12, wherein a surface of the anode active material layer of an inner side surface of the anode current collector of the first bent portion is provided with the functional layer.
14. The electrode assembly according to claim 12, wherein the anode tab has a second bent portion, a third bent portion, a fourth bent portion, and a fifth bent portion that are sequentially adjacent to the first bent portion in a winding direction, the second bent portion, the third bent portion, the fourth bent portion, and the fifth bent portion being each provided with the functional layer on a surface of the anode active material layer of an outer side surface of the respective anode current collector.
15. The electrode assembly according to claim 14, wherein the second bent portion, the third bent portion, the fourth bent portion, and the fifth bent portion are each provided with the functional layer on a surface of the anode active material layer of an inner side surface of the respective anode current collector.
16. The electrode assembly according to claim 10, wherein the positive electrode sheet and the negative electrode sheet are wound to form a winding structure having a plurality of the bent portions, and the functional layers corresponding to the plurality of the bent portions are sequentially thinned in a winding direction.
17. The electrode assembly of claim 16, wherein the difference in thickness between the functional layers corresponding to adjacent two of the bent portions in the winding direction is 1 μm to 70 μm.
18. The electrode assembly according to claim 10, wherein the positive electrode tab and the negative electrode tab are folded to form a lamination structure, the negative electrode tab has a sixth bent portion covered by the positive electrode tab, and a surface of the negative electrode active material layer of an outer side surface of the negative electrode current collector of the sixth bent portion is provided with the functional layer.
19. The electrode assembly according to claim 18, wherein a surface of the anode active material layer of an inner side surface of the anode current collector of the sixth bent portion is provided with the functional layer.
20. A battery cell comprising the electrode assembly of any one of claims 10-19.
21. A battery comprising the cell of claim 20.
22. An electrical device comprising the battery of claim 21 for providing electrical energy.
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| CN202211175113.6A CN117810357A (en) | 2022-09-26 | 2022-09-26 | Negative electrode plate, preparation method thereof, electrode assembly, battery cell, battery and electricity utilization device |
| PCT/CN2023/105137 WO2024066624A1 (en) | 2022-09-26 | 2023-06-30 | Negative electrode sheet and preparation method therefor, and electrode assembly, battery cell, battery and electric apparatus |
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| CN202211175113.6A CN117810357A (en) | 2022-09-26 | 2022-09-26 | Negative electrode plate, preparation method thereof, electrode assembly, battery cell, battery and electricity utilization device |
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| JP2016015245A (en) * | 2014-07-02 | 2016-01-28 | 株式会社日本自動車部品総合研究所 | Lithium ion secondary battery |
| CN205992575U (en) * | 2016-07-21 | 2017-03-01 | 中航锂电（洛阳）有限公司 | Positive plate and coiled lithium-ion power battery core and lithium-ion-power cell |
| CN110249473B (en) * | 2017-02-24 | 2022-07-08 | 三洋电机株式会社 | Nonaqueous electrolyte secondary battery |
| CN212810367U (en) * | 2020-08-21 | 2021-03-26 | 宁德时代新能源科技股份有限公司 | Electrode assembly, battery cell, battery and electric device |
| CN214254496U (en) * | 2021-01-19 | 2021-09-21 | 宁德时代新能源科技股份有限公司 | Electrode assembly, battery cell, battery, and power consumption device |
| CN114464771A (en) * | 2022-02-09 | 2022-05-10 | 珠海冠宇电池股份有限公司 | Battery cell |
| CN114447280A (en) * | 2022-02-09 | 2022-05-06 | 珠海冠宇电池股份有限公司 | Battery cell |
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