CN113764619A - Pole piece and pole piece assembly - Google Patents

Pole piece and pole piece assembly Download PDF

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Publication number
CN113764619A
CN113764619A CN202111188969.2A CN202111188969A CN113764619A CN 113764619 A CN113764619 A CN 113764619A CN 202111188969 A CN202111188969 A CN 202111188969A CN 113764619 A CN113764619 A CN 113764619A
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China
Prior art keywords
active material
material layer
pole piece
difference
particles
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Pending
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CN202111188969.2A
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Chinese (zh)
Inventor
吴聪苗
叶蓁
黄成�
冯登科
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Xiamen Haichen New Energy Technology Co Ltd
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Xiamen Haichen New Energy Technology Co Ltd
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Application filed by Xiamen Haichen New Energy Technology Co Ltd filed Critical Xiamen Haichen New Energy Technology Co Ltd
Priority to CN202111188969.2A priority Critical patent/CN113764619A/en
Publication of CN113764619A publication Critical patent/CN113764619A/en
Priority to US17/949,524 priority patent/US20230111642A1/en
Pending legal-status Critical Current

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    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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 relates to the field of batteries, in particular to a pole piece and a pole piece assembly. A pole piece, comprising: a current collector having opposing first and second surfaces; a first active material layer covering at least a partial region of the first surface; and a second active material layer covering at least a partial region of the second surface; wherein, the particle size distribution of the first active material layer and the second active material layer is different. After the pole piece is prepared into a battery, the first active material layer, the diaphragm and the pole piece with the polarity opposite to that of the pole piece form the battery with the first electrical property, and the second active material layer, the diaphragm and the pole piece with the polarity opposite to that of the pole piece form the battery with the second electrical property; the first electrical property and the second electrical property are cross-complemented, thereby improving the electrical performance of the entire cell.

Description

Pole piece and pole piece assembly
Technical Field
The application relates to the field of batteries, in particular to a pole piece and a pole piece assembly.
Background
The pole piece is mainly made of a current collector and an active material, and the active material is coated on two sides of the current collector in detail. The pole piece is the core component of battery, and the pole piece can seriously influence the electrical property of battery, in this application, in order to improve the electrical property of battery, provides a pole piece.
Disclosure of Invention
An object of the embodiment of this application is to provide a pole piece and pole piece subassembly, it aims at improving the electrical property of battery.
The application provides a pole piece, the pole piece includes:
a current collector having opposing first and second surfaces;
a first active material layer covering at least a partial region of the first surface; and
a second active material layer covering at least a partial region of the second surface;
the electrode plate is a positive electrode plate, the active material components of the first active material layer and the second active material layer are the same, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 0.05-0.3 mu m; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 1 μm to 4 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 3 μm to 5 μm.
Or the active material compositions of the first active material layer and the second active material layer are different, and the difference between the particle diameters of the active material particles D10 of the first active material layer and the second active material layer is 1-3 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 2 μm to 5 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 3 μm to 25 μm.
Or the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 0.1-4 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 0.1-8 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 0.1-10 μm;
or the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 0.1-4 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 0.1-10 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 0.1 μm to 20 μm.
After the pole piece is prepared into a battery through winding or lamination, the pole piece and the pole piece with the polarity opposite to that of the pole piece are separated through a diaphragm, a first active material layer of the pole piece, the diaphragm and an active material layer of the pole piece with the other polarity form the battery with a first electrical property, and a second active material layer of the pole piece, the diaphragm and the active material layer of the pole piece with the other polarity form the battery with a second electrical property; the first electrical property and the second electrical property are complemented in a crossed manner, so that the electrical property of the whole battery is improved; in other words, the first active material layer and the second active material layer may be regarded as one electrode of the battery, respectively, and may be regarded as two electrodes of the same polarity having different electrical properties of the battery due to the difference in particle size distribution between the first active material layer and the second active material layer; after the two electrodes are respectively formed into the battery, the batteries with different electrical properties can be formed, the effect of mutual assistance of the electrical properties can be realized, and the electrical properties of the battery can be increased.
In some embodiments of the present application, the active material composition of the first active material layer is the same as that of the second active material layer, and the difference between the compacted densities of the active material particles of the first active material layer and the second active material layer is 0.02g/cm or more3。
Optionally, the electrode plate is a positive electrode plate, the active material components of the first active material layer and the second active material layer are different, and the difference between the compacted densities of the active material particles of the first active material layer and the second active material layer is not less than 0.8g/cm3。
Optionally, the pole piece is a negative pole piece, and the difference between the compacted densities of the active material particles of the first active material layer and the second active material layer is 0.1g/cm3～1.8g/cm3。
In some embodiments of the present application, the electrode sheet is a positive electrode sheet, the active material of the first active material layer and/or the second active material layer is lithium iron phosphate, and the lithium iron phosphate satisfies the following conditions:
the grain diameter of D10 is more than 0.4 μm;
the grain diameter of D50 is 0.8-4 μm;
the grain diameter of D90 is 3-10 μm;
optionally, the pole piece is a positive pole piece, the active material of the first active material layer and/or the second active material layer is a ternary single crystal material, and the ternary single crystal material satisfies the following conditions:
the grain diameter of D10 is more than 1.5 μm;
the grain diameter of D50 is 4-10 μm;
the grain diameter of D90 is 9-20 μm;
optionally, the pole piece is a positive pole piece, the active material of the first active material layer and/or the second active material layer is a ternary polycrystalline material, and the ternary polycrystalline material satisfies the following conditions:
the grain diameter of D10 is more than 1.5 μm;
the grain diameter of D50 is 8-12 μm;
the particle size of D90 is 18-34 μm.
Optionally, the pole piece is a negative pole piece, the active material of the first active material layer and/or the second active material layer is graphite, and the graphite satisfies the following condition:
the grain diameter of D10 is more than 4 μm;
the grain diameter of D50 is 7-15 μm;
the grain diameter of D90 is less than or equal to 30 μm;
optionally, the pole piece is a negative pole piece, the active material of the first active material layer and/or the second active material layer is carbon silicon, and the carbon silicon satisfies the following condition:
the grain diameter of D10 is 1-4 μm;
the grain diameter of D50 is 4-8 μm;
the particle size of D90 is 9-12 μm.
Optionally, the electrode sheet is a negative electrode sheet, the first active material particles and/or the second active material particles are mesocarbon microbeads, and the mesocarbon microbeads satisfy the following conditions:
the grain diameter of D10 is more than 4 μm;
the particle size of D50 is 7-15 μm;
the grain diameter of D90 is less than or equal to 30 μm.
The first active material layer and the second active material layer both comprise lithium iron phosphate; wherein the difference between the carbon coating amount of the lithium iron phosphate in the first active material layer and the carbon coating amount of the lithium iron phosphate in the second active material layer is greater than or equal to 0.1%; the carbon coating amount is the ratio of the total mass of the carbon element to the total mass of the lithium iron phosphate and the carbon element.
In some embodiments of the present applicationWherein the active material components of the first active material layer and the second active material layer are the same, and the difference between the specific surface areas of the active material particles of the first active material layer and the second active material layer is 0.1m2/g～8m2/g；
Optionally, the electrode plate is a positive electrode plate, the active material components of the first active material layer and the second active material layer are different, and the difference between the specific surface areas of the active material particles of the first active material layer and the second active material layer is 7m2/g～15m2/g；
Optionally, the electrode sheet is a negative electrode sheet, the active material components of the first active material layer and the second active material layer are the same, and the difference between the specific surface areas of the active material particles of the first active material layer and the second active material layer is 0.2m2/g～8m2/g；
Optionally, the electrode plate is a negative electrode plate, the active material components of the first active material layer and the second active material layer are different, and the difference between the specific surface areas of the active material particles of the first active material layer and the second active material layer is 0.5m2/g～8m2/g。
In some embodiments of the present application, the electrode sheet is a positive electrode sheet, the active material composition of the first active material layer and the second active material layer is the same, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 10mAh/g to 60 mAh/g;
optionally, the pole piece is a positive pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 20 mAh/g-110 mAh/g.
Optionally, the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 10mAh/g to 100 mAh/g.
Optionally, the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 10mAh/g to 200 mAh/g.
In some embodiments of the present application, a difference between the thicknesses of the first active material layer and the second active material layer is 5 μm to 50 μm.
In some embodiments of the present application, the pole piece is a positive pole piece, and the current collector is a metal foil;
alternatively, the current collector includes a support layer and a metal layer covering both surfaces of the support layer.
The application also provides a pole piece assembly, which comprises a diaphragm and two pole pieces which are positioned on two sides of the diaphragm and have opposite polarities;
at least one of the two pole pieces is the pole piece.
In some embodiments of the present application, either one of the positive and said negative current collectors of the pole piece assembly is a composite current collector, the other one is a metal foil current collector.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 is a schematic cross-sectional view illustrating an embodiment of a pole piece provided in an example of the present application;
FIG. 2 is a schematic cross-sectional structural view of another embodiment of a pole piece provided in an example of the present application;
fig. 3 shows a schematic cross-sectional structure diagram of a pole piece assembly provided in an embodiment of the present application.
Icon: 100-pole piece; 101-a current collector; 110-a first active material layer; 120-a second active material layer; 201-a support layer; 202-a metal layer; 301-a first pole piece; 302-a second pole piece; 303-a third pole piece; 304-a fourth pole piece; 305-diaphragm.
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 and completely 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. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present application, it is to be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like, refer to the orientation or positional relationship as shown in the drawings, or as conventionally placed in use of the product of the application, or as conventionally understood by those skilled in the art, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore should not be considered as limiting the present application.
Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present application, it should also be noted that, unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; 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 in a specific case by those of ordinary skill in the art.
Examples
Fig. 1 is a schematic cross-sectional structure diagram of an embodiment of a pole piece 100 provided in this application, please refer to fig. 1, this embodiment provides a pole piece 100; the pole piece 100 includes a first active material layer 110, a second active material layer 120, and a current collector 101; the current collector 101 has two opposing surfaces, a first surface and a second surface; the first active material layer 110 covers at least a partial area of the first surface of the current collector 101; the second active material layer 120 covers at least a partial area of the second surface of the current collector 101.
The raw material of the first active material layer 110 mainly includes an active material, a conductive agent, and a binder.
The raw material of the second active material layer 120 mainly includes an active material, a conductive agent, and a binder.
For example, the binder can be one or more selected from styrene-butadiene rubber, polyvinyl alcohol and polypropylene alcohol. For example, the conductive agent can be one or more selected from Super-P, conductive carbon black and conductive graphite.
The active material may be selected according to the polarity of the electrode sheet 100, and in an embodiment where the electrode sheet 100 is a positive electrode sheet, the active material may be one or more of lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium iron phosphate.
In the embodiment where the electrode sheet 100 is a negative electrode sheet, the active material may be one or more of artificial graphite, natural graphite, soft carbon, hard carbon, and mesocarbon microbeads, for example.
In the present embodiment, there is a difference in particle size distribution of the first active material layer 110 and the second active material layer 120.
In other words, in the process of preparing the first and second active material layers 110 and 120, a slurry containing an active material is applied to the current collector 101; the slurry of the first active material layer 110 and the second active material layer 120 may be different, for example, the physical or chemical properties of the active materials are different, or the slurry is the same, and the coating process is different to obtain different first active material layers 110 and second active material layers 120.
Hereinafter, the present application will be exemplarily described with respect to the difference in the particle size distribution of the first active material layer 110 and the second active material layer 120.
The particle diameters of the active materials of the first active material layer 110 and the second active material layer 120 are different.
In the embodiment where the electrode sheet is a positive electrode sheet and the first active material layer 110 and the second active material layer 120 have the same composition, the active material particles have different particle sizes of D10, D50 and D90. In the present embodiment, the difference between the particle diameters of the active material particles D10 of the first active material layer 110 and the second active material layer 120 is 0.05 μm to 0.3 μm (for example, may be 0.05 μm, 0.08 μm, 0.1 μm, 0.15 μm, 0.19 μm, 0.2 μm, 0.23 μm, 0.25 μm, 0.3 μm, etc.); the difference between the particle diameters of the active material particles D50 of the first active material layer 110 and the second active material layer 120 is 1 μm to 4 μm (for example, may be 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2.1 μm, 2.4 μm, 2.9 μm, 3.4 μm, 4 μm, or the like); the difference between the particle diameters of the active material particles D90 of the first active material layer 110 and the second active material layer 120 is 3 μm to 5 μm (for example, may be 3 μm, 3.3 μm, 3.6 μm, 4 μm, 4.2 μm, 4.6 μm, 5 μm, or the like).
A larger particle size of the active material results in a longer ion migration path, poor rate capability, and a smaller particle size with good rate capability, but is difficult to disperse. The matching of the particle sizes is beneficial to prolonging the cycle life.
In the present embodiment, the first active material layer 110 and the second active material layer 120 have the same composition, and the active material particles in the two layers satisfy the above conditions, so that the same battery has good charge and discharge characteristics at different rates, and in the case of high-rate charge and discharge, the active material layer with a small particle size bears more current, thereby avoiding the safety problem caused by serious polarization and even lithium deposition due to a large current. Meanwhile, the large-particle-size side reduces the difficulty of dispersion in the powder stirring process and improves the processing performance of the process.
The electrode sheet 100 is a positive electrode sheet, and in the embodiment where the first active material layer 110 and the second active material layer 120 are different in composition, the active material particles are different in particle size of D10, particle size of D50, and particle size of D90. The difference between the particle diameters of the active material particles D10 of the two layers is 1 μm to 3 μm (for example, may be 1 μm, 1.2 μm, 1.6 μm, 1.8 μm, 2.1 μm, 2.3 μm, 2.7 μm, 3 μm, etc.); the difference between the particle diameters of the active material particles D50 of the two layers is 2 μm to 5 μm (for example, may be 2 μm, 2.3 μm, 2.6 μm, 3 μm, 3.2 μm, 3.6 μm, 4 μm, 5 μm, etc.); the difference in the particle diameter of the D90 of the active material particles of the two layers is 3 μm to 25 μm (e.g., may be 3 μm, 3.5 μm, 4 μm, 4.6 μm, 5.4 μm, 6.7 μm, 7.6 μm, 8.9 μm, 10 μm, 15 μm, 17 μm, 20 μm, 25 μm, etc.).
The first active material layer 110 and the second active material layer 120 have different compositions, and the active material particles of the two layers satisfy the above conditions, so that the same battery has the characteristics of the two material compositions, such as energy density, high/low temperature characteristics, rate discharge characteristics, and the like of the positive/negative electrode materials. Due to the fact that the battery is adaptive to different working conditions, abnormal conditions in the charging and discharging process can be reduced, and the service life of the battery can be prolonged to a certain extent.
In the embodiment where the electrode sheet 100 is a negative electrode sheet, the active material components of the first active material layer and the second active material layer are the same, and the difference between the particle diameters of the active material particles D10 of the first active material layer and the second active material layer is 0.1 μm to 4 μm (for example, may be 0.1 μm, 0.5 μm, 1 μm, 3 μm, 3.2 μm, 3.6 μm, 4 μm, or the like); the difference in particle diameter of the active material particles D50 of the first active material layer and the second active material layer is 0.1 μm to 8 μm (for example, may be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 5 μm, 7 μm, 7.6 μm, 8 μm, or the like); the difference in particle diameter of the active material particles D90 of the first active material layer and the second active material layer is 0.1 μm to 10 μm (for example, may be 0.3 μm, 2 μm, 3 μm, 4.6 μm, 5.5 μm, 6.9 μm, 7.6 μm, 8.9 μm, 10 μm, or the like);
in the embodiment where the electrode sheet 100 is a negative electrode sheet, the active material components of the first active material layer and the second active material layer are different, and the difference between the particle diameters of the active material particles D10 of the first active material layer and the second active material layer is 0.1 μm to 4 μm (for example, may be 0.1 μm, 0.4 μm, 1 μm, 2.2 μm, 3.4 μm, 3.7 μm, 4 μm, and the like); the difference in particle diameter of the active material particles D50 of the first active material layer and the second active material layer is 0.1 μm to 10 μm (for example, may be 0.3 μm, 2 μm, 3 μm, 4.6 μm, 5.5 μm, 6.9 μm, 7.6 μm, 8.9 μm, 10 μm, or the like); the difference in particle diameter of the active material particles D90 of the first active material layer and the second active material layer is 0.1 μm to 20 μm (for example, may be 0.2 μm, 3 μm, 4.6 μm, 5.2 μm, 6.5 μm, 10 μm, 12 μm, 15 μm, 20 μm, or the like).
As an example, in an embodiment in which the active material of the first active material layer 110 is lithium iron phosphate, the lithium iron phosphate satisfies the following condition:
the grain diameter of D10 is more than 0.4 μm; for example, the particle size of D10 is 0.45. mu.m, 0.5. mu.m, 0.8. mu.m, 0.9. mu.m, 1. mu.m, 1.5. mu.m, 4. mu.m, 9. mu.m, or the like.
The grain diameter of D50 is 0.8-4 μm; for example, D50 has a particle size of 0.8. mu.m, 0.9. mu.m, 1.6. mu.m, 2.1. mu.m, 2.8. mu.m, 3.5. mu.m, or 4 μm.
The grain diameter of D90 is 3-10 μm; for example, the particle size of D90 is 3 μm, 3.6. mu.m, 4.1. mu.m, 4.5. mu.m, 5.5. mu.m, 6.8. mu.m, 7.7. mu.m, 8.8. mu.m, 10 μm, etc.
Accordingly, the above condition may be also applied when the active material of the second active material layer 120 is lithium iron phosphate.
Illustratively, in an embodiment where the active material of the first active material layer 110 is a ternary single crystal material, for example, the ternary single crystal material is lithium nickel manganese cobalt (li (nicomn) O2The ternary single crystal material satisfies the following conditionsA piece:
the grain diameter of D10 is more than 1.5 μm; for example, D10 has a particle size of 1.5. mu.m, 1.6. mu.m, 1.8. mu.m, 2.2. mu.m, 2.6. mu.m, 3. mu.m, 5. mu.m, or 9.5. mu.m.
The grain diameter of D50 is 4-6 μm; for example, the particle size of D50 is 4 μm, 4.3 μm, 4.5 μm, 4.6 μm, 5 μm, 5.6 μm, 5.8 μm, 6 μm, or the like.
The grain diameter of D90 is 9-20 μm; for example, D90 has a particle size of 9 μm, 11 μm, 12 μm, 13.6 μm, 14 μm, 16.5 μm, 20 μm, or the like.
Illustratively, in embodiments where the active material of the first active material layer 110 is a ternary polycrystalline material, for example, the ternary polycrystalline material is lithium nickel manganese cobalt (li (nicomn) O)2The ternary polycrystalline material satisfies the following conditions:
the grain diameter of D10 is more than 1.5 μm; for example, D10 has a particle size of 1.5. mu.m, 1.9. mu.m, 2.2. mu.m, 2.5. mu.m, 3.2. mu.m, 4.5. mu.m, 5.5. mu.m, 10 μm, etc.
The grain diameter of D50 is 8-12 μm; for example, the particle size of D50 is 8 μm, 8.5 μm, 9 μm, 10.6 μm, 11 μm, or 12 μm, and so forth.
The particle size of D90 is 18 μm to 34 μm, for example, the particle size of D90 is 18 μm, 19 μm, 20 μm, 22 μm, 25 μm, 27 μm, 29 μm, 30 μm, 32 μm, 34 μm, etc.
Illustratively, the active material of the first active material layer 110 is graphite, and the particle diameter of the graphite particles satisfies the following condition:
the grain diameter of D10 is more than 4 μm; for example, the particle size of D10 is 4 μm, 4.2. mu.m, 5. mu.m, 6.2. mu.m, 7 μm, or the like.
The grain diameter of D50 is 7-15 μm; for example, D50 has a particle size of 7 μm, 8 μm, 8.6 μm, 9.2 μm, 10 μm, 12 μm, 13.5 μm, or 15 μm.
The grain diameter of D90 is less than or equal to 30 μm; for example, the particle size of D90 is 30 μm, 32 μm, 37 μm, 40 μm, 42 μm, 45 μm, 48 μm, or the like.
Illustratively, the active material of the first active material layer 110 is carbon silicon, and the particle diameter of the carbon silicon particle satisfies the following condition:
the grain diameter of D10 is 1-4 μm; for example, D10 has a particle size of 1 μm, 1.5. mu.m, 2. mu.m, 2.6. mu.m, 3. mu.m, 3.7. mu.m, 4 μm, etc.
The grain diameter of D50 is 4-8 μm; for example, the particle size of D50 is 4 μm, 6 μm, 7 μm, 7.2 μm, 7.5 μm, 8 μm, or the like.
The particle size of D90 is 9-12 μm. For example, D90 has a particle size of 9 μm, 10 μm, 11 μm, 11.5 μm, 12 μm, or the like.
Illustratively, the material of the first active material layer 110 is mesocarbon microbeads, and the mesocarbon microbeads satisfy the following conditions:
the grain diameter of D10 is more than 4 μm; for example, the particle size of D10 is 4 μm, 4.2. mu.m, 5. mu.m, 6.2. mu.m, 7 μm, or the like.
The particle size of D50 is 7-15 μm; for example, the particle size of D50 is 7 μm, 8 μm, 10 μm, 11 μm, 13 μm, 15 μm, or the like.
The grain diameter of D90 is less than or equal to 30 μm; for example, the particle size of D90 is 3 μm, 8 μm, 9 μm, 11.5 μm, 18 μm, 25 μm, 30 μm, or the like.
Further, in other embodiments of the present application, the first active material layer 110 and the second active material layer 120 may have other performance differences in addition to the above-described differences in particle size distribution, and the following description is given for the present application with respect to other performance differences of the first active material layer 110 and the second active material layer 120.
In the first example, the specific surface areas of the particles of the active materials of the first active material layer 110 and the second active material layer 120 are different.
Illustratively, in the embodiment in which the pole piece 100 is a positive pole piece, and in the embodiment in which the first active material layer 110 and the second active material layer 120 are the same in composition, the difference between the specific surface areas of the active material particles of the first active material layer 110 and the second active material layer 120 is 0.1m2/g～8m2In terms of/g, e.g. a difference in specific surface area of 0.1m2/g、0.6m2/g、1m2/g、1.5m2/g、2m2/g、2.2m2/g、2.3m2/g、2.9m2/g、3m2/g、3.6m2/g、4m2/g、4.7m2/g、5.3m2/g、5.8m2/g、6.3m2/g、7.6m2/g、8m2/g。
Illustratively, in the embodiment in which the pole piece 100 is a positive pole piece, and in the embodiment in which the compositions of the first active material layer 110 and the second active material layer 120 are different, the difference between the specific surface areas of the active material particles of the first active material layer 110 and the second active material layer 120 is 7m2/g～15m2(ii) in terms of/g. For example, the difference in specific surface area is 7m2/g、8m2/g、8.3m2/g、8.9m2/g、9.4m2/g、9.9m2/g、10.2m2/g、11.1m2/g、12.0m2/g、13.4m2/g、14.3m2/g、15m2/g。
For example, in the embodiment where the active material of the first active material layer 110 is lithium iron phosphate, the specific surface area of the lithium iron phosphate is 8m2/g～16m2Per g, e.g. lithium iron phosphate particles having a specific surface area of 8m2/g、10.2m2/g、11.3m2/g、11.9m2/g、12.5m2/g、13.6m2/g、14.7m2/g、15.3m2/g、16m2/g。
The active material of the first active material layer 110 may also have a specific surface area of 8m2/g～16m2The lithium iron phosphate/g is required to have a specific surface area difference of 1.5m2/g～8m2The ratio is/g.
For example, the active material of the first active material layer 110 is single crystal lithium nickel cobalt manganese oxide (li (nicomn) O2A specific surface area of 0.3m2/g～0.6m2Per g (which may be, for example, 0.4 m)2/g、0.5m2/g、0.55m2In terms of/g). For example, the active material of the first active material layer 110 is polycrystalline lithium nickel cobalt manganese oxide (li (nicomn) O2Specific surface area of 0.2m2/g～0.6m2Per g (which may be, for example, 0.3 m)2/g、0.4m2/g、0.5m2/g)。
As an example, in an embodiment in which the pole piece 100 is a negative pole piece, and in an embodiment in which the first active material layer 110 and the second active material layer 120 are the same in composition, the difference between the specific surface areas of the active material particles of the first active material layer 110 and the second active material layer 120 is 0.2m2/g～8m2In g, e.g. a difference of 0.2m in specific surface area2/g、0.5m2/g、1m2/g、1.6m2/g、2m2/g、2.7m2/g、3.6m2/g、4m2/g、5.7m2/g、6m2/g、6.3m2/g、7.6m2/g、8m2/g。
Illustratively, in the embodiment in which the pole piece 100 is a negative pole piece, and in the embodiment in which the compositions of the first active material layer 110 and the second active material layer 120 are different, the difference between the specific surface areas of the active material particles of the first active material layer 110 and the second active material layer 120 is 0.5m2/g～8m2In g, e.g. a difference of 0.5m in specific surface area2/g、1m2/g、1.6m2/g、2m2/g、2.7m2/g、3.5m2/g、4m2/g、5.5m2/g、6m2/g、6.3m2/g、7.5m2/g、8m2/g。
For example, the active material of the first active material layer 110 is graphite having a specific surface area of 0.5m2/g～8m2Per g (which may be, for example, 0.5 m)2/g、1.6m2/g、2m2/g、2.8m2/g、3.5m2/g、4m2/g、5.8m2/g、6m2/g、6.8m2/g、7.8m2/g、8m2In terms of/g). For example, the active material of the first active material layer 110 is silicon carbon having a specific surface area of 0.5m2/g～8m2Per g (which may be, for example, 0.5 m)2/g、1.9m2/g、2m2/g、2.3m2/g、3.3m2/g、4m2/g、5.3m2/g、6m2/g、6.3m2/g、7.3m2/g、8m2In terms of/g). For example, the active material of the first active material layer 110 is mesocarbon microbeads having a specific surface area of 0.5m2/g～4m2Per g (which may be, for example, 0.5 m)2/g、1.9m2/g、2m2/g、2.3m2/g、3.3m2/g、4m2/g)。
In a second example, the gram capacities of the particles of the active materials of the first active material layer 110 and the second active material layer 120 are different.
Illustratively, in the embodiment in which the pole piece 100 is a positive pole piece, and in the embodiment in which the first active material layer 110 and the second active material layer 120 are the same in composition, the difference in the gram capacity of the particles of the active materials of the first active material layer 110 and the second active material layer 120 is 10mAh/g to 60 mAh/g; for example, 10mAh/g, 16mAh/g, 20mAh/g, 22mAh/g, 27mAh/g, 37mAh/g, 45mAh/g, 50mAh/g, 57mAh/g, 60mAh/g, and so forth.
Illustratively, in the embodiment in which the pole piece 100 is a positive pole piece, and the compositions of the first active material layer 110 and the second active material layer 120 are different, the difference between the gram capacities of the active materials of the first active material layer 110 and the second active material layer 120 is 20mAh/g to 110 mAh/g; for example, it may be 20mAh/g, 32mAh/g, 47mAh/g, 60mAh/g, 72mAh/g, 86mAh/g, 97mAh/g, 100mAh/g, 110mAh/g, and so forth.
For example, in the embodiment where the active material of the first active material layer 110 is lithium iron phosphate, the gram capacity of the lithium iron phosphate is 100mAh/g to 160 mAh/g; for example, 100mAh/g, 120mAh/g, 125mAh/g, 135mAh/g, 142mAh/g, 148mAh/g, 154mAh/g, 160mAh/g, and so forth.
For example, the active material of the first active material layer 110 is single crystal lithium nickel cobalt manganese oxide (li (nicomn) O2The gram capacity is 160 mAh/g-210 mAh/g; for example, 160mAh/g, 197mAh/g, 198mAh/g, 210mAh/g, and so forth may be provided.
For example, the active material of the first active material layer 110 is polycrystalline lithium nickel cobalt manganese oxide (li (nicomn) O2The gram capacity is 165 mAh/g-211 mAh/g; for example, 165mAh/g, 180mAh/g, 181mAh/g, 184mAh/g, 185mAh/g, 211mAh/g, and the like. Correspondingly, the active material of the second active material layer 120 may also be polycrystalline lithium nickel cobalt manganese oxide, single crystal lithium nickel cobalt manganese oxide or lithium iron phosphate with the above gram volume; when the two layers of materials are the same, the difference of the capacities of the active materials in the two layers is 10 mAh/g-60 mAh/g; when the two layers of materials are different, the difference of the capacities of the active materials in the two layers is 20 mAh/g-110 mAh/g.
As an example, in an embodiment in which the pole piece 100 is a negative pole piece, and in an embodiment in which the first active material layer 110 and the second active material layer 120 are the same in composition, the difference in gram capacity of the particles of the active materials of the first active material layer 110 and the second active material layer 120 is 10mAh/g to 100 mAh/g. For example, 10mAh/g, 29mAh/g, 41mAh/g, 53mAh/g, 67mAh/g, 83mAh/g, 97mAh/g, 100mAh/g, and the like.
Illustratively, in embodiments where the pole piece 100 is a negative pole piece, and the compositions of the first active material layer 110 and the second active material layer 120 are different, the difference in the gram capacities of the active materials of the first active material layer 110 and the second active material layer 120 is 10mAh/g to 200 mAh/g. For example, 10mAh/g, 29mAh/g, 41mAh/g, 53mAh/g, 67mAh/g, 83mAh/g, 97mAh/g, 100mAh/g, 150mAh/g, 200mAh/g, and the like.
For example, the active material of the first active material layer 110 is graphite having a gram capacity of 250mAh/g to 360 mAh/g; for example, the concentration may be 250mAh/g, 290mAh/g, 300mAh/g, 310mAh/g, 330mAh/g, 360 mAh/g. The active material of the first active material layer 110 is silicon carbon, and the gram capacity of the first active material layer is 360 mAh/g-1000 mAh/g; for example, the concentration may be 360mAh/g, 420mAh/g, 520mAh/g, 680mAh/g, 730mAh/g, 1000 mAh/g. The active material of the first active material layer 110 is mesocarbon microbeads with gram capacity of 200 mAh/g-400 mAh/g; for example, 200mAh/g, 250mAh/g, 290mAh/g, 320mAh/g, 380mAh/g, 400mAh/g can be used.
In the present application, after the pole piece 100 is prepared into a battery, the first active material layer 110 and the pole piece with opposite polarity to the pole piece 100 form a battery with a first electrical property, and the second active material layer 120 and the pole piece with opposite polarity to the pole piece 100 form a battery with a second electrical property; the battery with the first electrical property and the battery with the second electrical property can jointly prolong the cycle life of the batteries.
In a third example, the active materials of the first active material layer 110 and the second active material layer 120 are both lithium iron phosphate coated with a carbon layer, and the carbon content in the lithium iron phosphate of the first active material layer 110 and the second active material layer 120 is different.
In detail, the first active material layer 110 includes lithium iron phosphate at least partially covered with a carbon layer, the second active material layer 120 includes lithium iron phosphate at least partially covered with a carbon layer, and the content of the carbon layer in the first active material layer 110 is different from the content of the carbon layer in the second active material layer 120. Specifically, the content of the carbon layer in the first active material layer 110 and the content of the carbon layer in the second active material layer 120 are 0.8% to 1.6%; in other words, the carbon layer content in the first active material layer 110 is equal to the carbon layer content in the second active material layer 120 (1 ± n), where n is 0.8% to 1.6%, and may be, for example, 0.8%, 0.9%, 1.1%, 1.3%, 1.4%, 1.6%, or the like. Wherein the content of the carbon layer is the ratio of the mass of the carbon layer to the total mass of the lithium iron phosphate and the carbon layer.
For example, in the embodiment where the active material of the first active material layer 110 is lithium iron phosphate coated with a carbon layer, the content of the carbon layer is 0.8% to 1.6%, and may be, for example, 0.8%, 0.9%, 1.1%, 1.3%, 1.5%, 1.6%, and the like.
The carbon layer contents of the first active material layer 110 and the second active material layer 120 are different, so that the conductivity and rate of the battery can be improved.
In a fourth example, the compacted densities of the active materials of the first and second active material layers 110 and 120 are not the same.
Illustratively, in the embodiment where the electrode sheet is a positive electrode sheet and the compositions of the first active material layer 110 and the second active material layer 120 are different, the difference between the compacted densities of the active materials of the first active material layer 110 and the second active material layer 120 is greater than or equal to 0.8g/cm3The difference between the two compacted densities may be 1.2g/cm3、1.5g/cm3、2g/cm3、2.5g/cm3And so on.
Illustratively, in the embodiment where the electrode sheet is a positive electrode sheet and the first active material layer 110 and the second active material layer 120 are the same in composition, the difference between the compacted densities of the active materials of the first active material layer 110 and the second active material layer 120 is greater than or equal to 0.02g/cm3The difference between the two compacted densities may be 0.02g/cm3、0.3g/cm3、0.9g/cm3、1.2g/cm3、1.5g/cm3And so on.
For example, in an embodiment where the active material of the first active material layer 110 is lithium iron phosphate, the compacted density of the lithium iron phosphate is 2.1g/cm3～2.6g/cm3For example, it may be 2.1g/cm3、2.2g/cm3、2.38g/cm3、2.4g/cm3、2.45g/cm3、2.6g/cm3And so on. Accordingly, the second active material layer 120 may also be selected to have a compacted density of 2.1g/cm3～2.6g/cm3The lithium iron phosphate of (1).
For example, the active material of the first active material layer 110 is single crystal lithium nickel cobalt manganese oxide (li (nicomn) O2The compacted density is 3.2g/cm3～3.75g/cm3For example, it may be 3.2g/cm3、3.3g/cm3、3.5g/cm3、3.75g/cm3And so on.
For example, the active material of the first active material layer 110 is polycrystalline lithium nickel cobalt manganese oxide (li (nicomn) O2The compacted density is 3.2g/cm3～3.6g/cm3For example, it may be 3.2g/cm3、3.3g/cm3、3.5g/cm3、3.55g/cm3、3.6g/cm3And so on.
Accordingly, the second active material layer 120 may also be selected to have a compacted density of 2.1g/cm3～2.6g/cm3The compacted density of the lithium iron phosphate is 3.2g/cm3～3.6g/cm3Polycrystalline lithium nickel cobalt manganese oxide (Li (NiCoMn) O)2The compacted density is 3.2g/cm3～3.75g/cm3Single crystal lithium nickel cobalt manganese oxide (Li (NiCoMn) O)2。
Illustratively, the pole piece is a negative pole piece, and the difference between the compacted densities of the active materials of the first active material layer 110 and the second active material layer 120 is 0.1g/cm3～1.8g/cm3The difference between the two compacted densities may be 0.1g/cm3、0.5g/cm3、1.0g/cm3、1.5g/cm3、1.8g/cm3And so on.
For example, the active material of the first active material layer 110 is graphite having a compacted density of 1.1g/cm3～1.8g/cm3For example, it may be 1.1g/cm3、1.3g/cm3、1.6g/cm3、1.7g/cm3、1.8g/cm3And so on.
For example, the active material of the first active material layer 110 is silicon carbon having a compacted density of 1.1g/cm3～2.0g/cm3For example, it may be 1.1g/cm3、1.4g/cm3、1.6g/cm3、1.8g/cm3、2.0g/cm3And so on.
For example, the active material of the first active material layer 110 is mesocarbon microbeads having a compacted density of 1.1g/cm3～2.0g/cm3For example, it may be 1.1g/cm3、1.5g/cm3、1.7g/cm3、1.9g/cm3、2.0g/cm3And so on.
In the present application, the difference between the gram capacities of the first active material layer 110 and the second active material layer 120 satisfies the above conditions, and the design end can provide more combinations of solutions to meet the energy density requirement of the cell, and simultaneously reduce the cost of the active material and the range of the supply chain to achieve greater competitive advantage.
In the fifth example, the thicknesses of the first active material layer 110 and the second active material layer 120 are not the same.
Illustratively, the pole piece is a positive pole piece, and the difference between the thicknesses of the first active material layer 110 and the second active material layer 120 is 5 μm to 50 μm, for example, the difference between the thicknesses of the two layers is 5 μm, 7 μm, 11 μm, 13 μm, 21 μm, 29 μm, 31 μm, 40 μm, 46 μm, 49 μm, 50 μm, or the like. Accordingly, for embodiments in which the thicknesses of the first active material layer 110 and the second active material layer 120 are different, the active materials of the first active material layer 110 and the second active material layer 120 may be the same or different.
For example, the active material of the first active material layer 110 is lithium iron phosphate, and the coating amount of the first active material layer 110 is 5mg/cm2～22mg/cm2For example, it may be 5mg/cm2、6mg/cm2、7mg/cm2、9mg/cm2、10mg/cm2、11mg/cm2、13mg/cm2、14mg/cm2、16mg/cm2、18mg/cm2、20mg/cm2、21mg/cm2Or 22mg/cm2。
For example, the active material of the first active material layer 110 is single crystal lithium nickel cobalt manganese oxide (li (nicomn) O2The coating amount of the first active material layer 110 was 10mg/cm2～26mg/cm2For example, it may be 10mg/cm2、13mg/cm2、14mg/cm2、15mg/cm2、16mg/cm2、17mg/cm2、19mg/cm2、20mg/cm2、22mg/cm2、24mg/cm2Or 26mg/cm2。
For example, the active material of the first active material layer 110 is polycrystalline lithium nickel cobalt manganese oxide (li (nicomn) O2. The coating amount of the first active material layer 110 was 10mg/cm2～26mg/cm2For example, it may be 10mg/cm2、14mg/cm2、15mg/cm2、17mg/cm2、19mg/cm2、20mg/cm2、22mg/cm2、23mg/cm2、25mg/cm2Or 26mg/cm2。
Accordingly, the coating amount of the second active material layer 120 may also refer to the coating amounts of the above three materials.
Illustratively, the pole piece is a negative pole piece, and the difference between the thicknesses of the first active material layer 110 and the second active material layer 120 is 5 μm to 100 μm, for example, the difference between the thicknesses of the two layers is 5 μm, 7 μm, 11 μm, 13 μm, 21 μm, 29 μm, 31 μm, 40 μm, 46 μm, 49 μm, 50 μm, 70 μm, 85 μm, 90 μm, 100 μm, and so on. Accordingly, for embodiments in which the thicknesses of the first active material layer 110 and the second active material layer 120 are different, the active materials of the first active material layer 110 and the second active material layer 120 may be the same or different.
For example, the active material of the first active material layer 110 is graphite, and the coating amount of the first active material layer 110 is 5mg/cm2～15mg/cm2(ii) a For example, it may be 5mg/cm2、8mg/cm2、10mg/cm2、13mg/cm2、14mg/cm2Or 15mg/cm2。
For example, the active material of the first active material layer 110 is silicon carbonThe coating amount of the first active material layer 110 is 5 to 10mg/cm2(ii) a For example, it may be 5mg/cm2、7mg/cm2、9mg/cm2、10mg/cm2、12mg/cm2、14mg/cm2Or 15mg/cm2。
For example, the active material of the first active material layer 110 is mesocarbon microbeads, and the coating amount of the first active material layer 110 is 5 to 10mg/cm2. For example, it may be 5mg/cm2、7mg/cm2、8mg/cm2、9mg/cm2Or 10mg/cm2。
Accordingly, the coating amount of the second active material layer 120 may also refer to the coating amounts of the above three materials.
In some embodiments of the present application, the first active material layer 110 and the second active material layer 120 may be provided to be different from at least one of the first example, the second example, the third example, the fourth example, and the fifth example described above; alternatively, in some embodiments, the first active material layer 110 and the second active material layer 120 may only differ in particle size.
In the embodiment shown in fig. 1, the current collector 101 is a metal foil, in the embodiment where the electrode sheet 100 is a positive electrode sheet, the current collector 101 is an aluminum foil, and in the embodiment where the electrode sheet 100 is a negative electrode sheet, the current collector 101 is a copper foil.
Fig. 2 shows a schematic cross-sectional structure of another embodiment of a pole piece 100 provided in an example of the present application, please refer to fig. 1 and fig. 2 together, where the main difference between the pole piece 100 shown in fig. 2 and the pole piece 100 shown in fig. 1 is that the current collector in fig. 2 is different from the current collector 101 in fig. 1.
In fig. 2, the current collector includes a support layer 201 and a metal layer 202, and the metal layer 202 covers both surfaces of the support layer 201.
The surfaces of the two metal layers 202 facing away from the support layer 201 are provided with a first active material layer 110 and a second active material layer 120, respectively.
As an example, the material of the support layer 201 may be one or more of polyesters, polyolefins, polyamides, polyimides, polyethers, epoxy resins, phenol resins, cross-linked products thereof, and copolymers thereof.
The material of the metal layer 202 may be, for example, aluminum or copper.
Please refer to the description of the pole piece 100 in fig. 1 above for the first active material layer 110 and the second active material layer 120 in the pole piece 100 shown in fig. 2, which are not repeated herein.
The pole piece 100 provided by the embodiment of the application has at least the following advantages:
the difference exists in the particle size distribution of the first active material layer 110 and the second active material layer 120 of the pole piece 100, after the pole piece 100 and the pole piece with the polarity opposite to that of the pole piece 100 are prepared into a battery, the first active material layer 110, the diaphragm and the pole piece with the polarity opposite to that of the pole piece 100 form one battery, and the second active material layer 120, the diaphragm and the pole piece with the polarity opposite to that of the pole piece 100 form the other battery; the battery at least comprises two batteries with different electrical properties, the two batteries have different properties, and the properties of the two batteries are mutually complemented to form the battery with better electrical property.
The application also provides a pole piece assembly, which comprises a diaphragm and two pole pieces which are positioned on two sides of the diaphragm and have opposite polarities; at least one of the two pole pieces is the pole piece 100 described above. For example, the two pole pieces are the pole pieces 100 with opposite polarities.
In this embodiment, the pole piece assembly includes two kinds of pole pieces, a positive pole piece and a negative pole piece; the number of the positive pole pieces is greater than or equal to 1, and the number of the negative pole pieces is greater than or equal to 1; for embodiments in which the number of positive pole pieces is greater than 1, each positive pole piece may be the same, or only a portion of the number of positive pole pieces may be the same; part or all of the positive electrode sheet is constructed as described above for sheet 100. Accordingly, for embodiments in which the number of negative pole pieces is greater than 1, each negative pole piece may be the same, or only a portion of the number of negative pole pieces may be the same, with some or all of the negative pole pieces configured as pole pieces 100 described above.
Fig. 3 shows a schematic cross-sectional structure diagram of a pole piece assembly provided in an embodiment of the present application. Referring to fig. 3, in the present embodiment, the pole piece assembly includes a first pole piece 301, a second pole piece 302, a third pole piece 303, and a fourth pole piece 304; the first pole piece 301 and the third pole piece 303 are both positive pole pieces, the second pole piece 302 and the fourth pole piece 304 are both negative pole pieces, and the particle size distribution of the two surfaces of the first pole piece 301 has the difference; two adjacent pole pieces are separated by a separator 305. The above difference exists in the particle size distribution of the two surfaces of the second pole piece 302, and the above difference exists in the particle size distribution of the active material layers of the two surfaces of the third pole piece 303; the particle size distribution of the active material layers on both sides of the fourth sheet 304 has the above-described difference.
In some embodiments of the present application, the first pole piece 301 and the third pole piece 303 may be the same or different, and the second pole piece 302 and the fourth pole piece 304 may be the same or different.
The tabs of the pole piece assemblies are shown on the same side in fig. 3, it being understood that in other embodiments the tabs of the pole piece assemblies may be on different sides.
As mentioned above, because the particle size distribution of the active material layers on both sides of the pole piece has the above difference, after the pole piece assembly is wound or laminated to prepare a battery, at least two batteries with different electrical properties can be formed, and the performance of a plurality of batteries with different electrical properties is complementary, so as to improve the electrical property of the final battery.
In some embodiments of the present application, either one of the positive and negative current collectors of the pole piece assembly is a composite current collector, the other is a metal foil current collector. In other words, the positive current collector is a composite current collector, and the negative current collector is a metal foil current collector; or the negative current collector is a composite current collector, and the positive current collector is a metal foil current collector.
For example, the first pole piece 301 and the third pole piece 303 are both composite current collectors, and the second pole piece 302 and the fourth pole piece 304 are both metal foil current collectors; or the first pole piece 301 and the third pole piece 303 are both metal foil current collectors, and the second pole piece 302 and the fourth pole piece 304 are both composite current collectors; two adjacent pole pieces are separated by a separator 305.
Examples 1-2 and comparative example 1
Examples 1-2 and comparative example 1 each provide a battery comprising a positive electrode sheet, a separator, and a negative electrode sheet; the positive pole piece comprises an aluminum foil, a conductive layer positioned on one surface of the aluminum foil and a first active layer; and a conductive layer and a second active layer on the other surface of the aluminum foil.
The negative pole piece comprises a copper foil, a conducting layer positioned on one surface of the copper foil and a third active layer; and a conductive layer and a fourth active layer on the other surface of the copper foil.
The first active layer is formed by coating first active slurry, and the first active slurry comprises, by mass, 96: 2: 2, conductive carbon black and a binder.
The second active layer is formed by coating second active slurry, and the second active slurry comprises, by mass, 96: 2: 2, conductive carbon black and a binder.
Table 1 shows the main parameters of the first and second active layers of the positive electrode. Table 2 shows the main parameters of the two active layers (named third active layer, fourth active layer) of the negative electrode; in tables 1 and 2: specific surface area, gram volume, particle size, carbon layer content, thickness, and compacted density all refer to the properties of the active material particles.
TABLE 1
Figure BDA0003300424900000231
TABLE 2
Figure BDA0003300424900000241
Test examples
The cycle life, rate, internal resistance, energy density, high and low temperature characteristics of the batteries provided in examples 1-2 and comparative example 1 were examined. The results are shown in Table 3.
TABLE 3
Figure BDA0003300424900000242
In Table 3, 3C @ 90% represents: 3C is adopted for discharging at 25 ℃, and the discharge capacity is 90 percent of the rated capacity; accordingly, 3C @ 95% represents: 3C is adopted for discharging at 25 ℃, and the discharge capacity is 95 percent of the rated capacity; 3C @ 92% represents: at 25 ℃, 3C discharge was used, and the discharge capacity was 92% of the rated capacity.
50% SOC DCR/m Ω represents: and (4) discharging for 30s at 25 ℃ and 50% SOC by adopting 3C, and calculating to obtain the discharging DCR.
As can be seen from table 3:
compared with the comparative example 1, the coating weight and the compaction designed in the example 1 are unchanged, the particle size of the second layer of the cathode material is small, the specific surface area is large, the path of electron migration is short, the carbon coating is improved, the third layer of the cathode adopts mesocarbon microspheres, the gram capacity of the material is improved, the isotropy is good, the rate capability is improved, the cycle life is greatly prolonged, and the low-temperature working interval is widened to-30 ℃; the particle size of the material of the second active layer is small, the dynamic performance is good, the electrochemical impedance and the concentration impedance are relatively small, the thickness of the conductive layer is unchanged, and the ohmic impedance is unchanged, so that the DCR is reduced integrally. The particle size distribution of the negative electrode mesocarbon microbeads is narrow and small, the thickness of the conducting layer is increased, and the DCR is relatively small.
In example 2, compared to comparative example 1, the material of the second active layer of the positive electrode in example 2 was changed to polycrystalline nickel cobalt manganese (811 system), and the gram volume of the polycrystalline nickel cobalt manganese material was much higher than that of lithium iron phosphate, and the material was also heavier than that of lithium iron phosphate in unit weight, so that the coating weight and the compaction density were both designed to be large, and the weight energy density was improved much. The cycle number is greatly reduced because the particle size is larger and the specific surface area is smaller. The polycrystalline nickel-cobalt-manganese alloy has good conductivity, and does not need carbon coating, so the rate capability is improved integrally. The performance of the polycrystalline nickel-cobalt-manganese material at low temperature is relatively good, so that the design working temperature range of the battery core can be expanded to-25 ℃ in a low temperature region. Compared with the comparative example 1, the third layer of the negative electrode is made of silicon-carbon materials, the gram capacity is high, the coating weight and the thickness of a pole piece are reduced, so the energy density is also improved, and the cycle performance is slightly attenuated due to large volume expansion and easy particle breakage in the cycle process. The second active layer is made of polycrystalline nickel-cobalt-manganese, so that the conductive performance is good, the ohmic resistance is favorably reduced, meanwhile, the thickness of the second conductive layer is increased, the overcurrent capacity is improved, and the ohmic resistance is reduced to a greater degree on the whole. The electrochemical impedance and concentration impedance of the polycrystalline nickel-cobalt-manganese alloy are not larger than that of lithium iron phosphate, so that the DCR is reduced to a greater extent. The conductivity of the negative silicon carbon material is slightly reduced (which can lead to the increase of DCR), but the thickness of the conductive layer is increased, so that the comprehensive effect is that the effect of the negative electrode on the DCR is slightly increased, but the influence of the positive electrode is larger, so that the DCR is reduced as a whole.
In summary, the pole piece 100 provided in the embodiment of the present application has better electrical performance.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. A pole piece, comprising:
a current collector having opposing first and second surfaces;
a first active material layer covering at least a partial region of the first surface; and
a second active material layer covering at least a partial region of the second surface;
the electrode plate is a positive electrode plate, the active material components of the first active material layer and the second active material layer are the same, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 0.05-0.3 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 1 μm to 4 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 3 to 5 μm;
or the pole piece is a positive pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 1-3 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 2 to 5 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 3 to 25 μm;
or the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 0.1-4 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 0.1-8 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 0.1-10 μm;
or the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the particle sizes of the active material particles D10 of the first active material layer and the second active material layer is 0.1-4 μm; the difference between the particle diameters of the active material particles D50 of the first active material layer and the second active material layer is 0.1-10 μm; the difference between the particle diameters of the active material particles D90 of the first active material layer and the second active material layer is 0.1 μm to 20 μm.
2. The pole piece according to claim 1, wherein the pole piece is a positive pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference between the compacted densities of the active material particles of the first active material layer and the second active material layer is not less than 0.02g/cm3；
Optionally, the electrode plate is a positive electrode plate, the active material components of the first active material layer and the second active material layer are different, and the electrode plate is a positive electrode plateThe difference between the compacted densities of the active material particles of the first active material layer and the second active material layer is not less than 0.8g/cm3；
Optionally, the pole piece is a negative pole piece, and the difference between the compacted densities of the active material particles of the first active material layer and the second active material layer is 0.1g/cm3～1.8g/cm3。
3. The pole piece of claim 1, wherein the pole piece is a positive pole piece, the active material of the first active material layer and/or the second active material layer is lithium iron phosphate, and the lithium iron phosphate satisfies the following conditions:
the grain diameter of D10 is more than 0.4 μm;
the grain diameter of D50 is 0.8-4 μm;
the grain diameter of D90 is 3-10 μm;
optionally, the pole piece is a positive pole piece, the active material of the first active material layer and/or the second active material layer is a ternary single crystal material, and the ternary single crystal material satisfies the following conditions:
the grain diameter of D10 is more than 1.5 μm;
the grain diameter of D50 is 4-10 μm;
the grain diameter of D90 is 9-20 μm;
optionally, the pole piece is a positive pole piece, the active material of the first active material layer and/or the second active material layer is a ternary polycrystalline material, and the ternary polycrystalline material satisfies the following condition:
the grain diameter of D10 is more than 1.5 μm;
the grain diameter of D50 is 8-12 μm;
the grain diameter of D90 is 18-34 μm;
optionally, the pole piece is a negative pole piece, the active material of the first active material layer and/or the second active material layer is graphite, and the graphite satisfies the following condition:
the grain diameter of D10 is more than 4 μm;
the grain diameter of D50 is 7-15 μm;
the grain diameter of D90 is less than or equal to 30 μm;
optionally, the pole piece is a negative pole piece, the active material of the first active material layer and/or the second active material layer is carbon silicon, and the silicon carbide satisfies the following condition:
the grain diameter of D10 is 1-4 μm;
the grain diameter of D50 is 4-8 μm;
the grain diameter of D90 is 9-12 μm;
optionally, the pole piece is a negative pole piece, the first active material layer and/or the second active material layer is/are mesocarbon microbeads, and the mesocarbon microbeads satisfy the following conditions:
the grain diameter of D10 is more than 4 μm;
the particle size of D50 is 7-15 μm;
the grain diameter of D90 is less than or equal to 30 μm.
4. The pole piece of claim 1, wherein the first active material layer and the second active material layer each comprise lithium iron phosphate; wherein the difference between the carbon coating amount of the lithium iron phosphate in the first active material layer and the carbon coating amount of the lithium iron phosphate in the second active material layer is greater than or equal to 0.1%; the carbon coating amount is the ratio of the total mass of the carbon element to the total mass of the lithium iron phosphate and the carbon element.
5. The pole piece according to claim 1, wherein the pole piece is a positive pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference of the specific surface areas of the active material particles of the first active material layer and the second active material layer is 0.1m2/g～8m2/g；
Optionally, the electrode plate is a positive electrode plate, the active material components of the first active material layer and the second active material layer are different, and the difference between the specific surface areas of the active material particles of the first active material layer and the second active material layer is 7m2/g～15m2/g；
Optionally, the electrode plate is a negative electrode plate, and the first active material layer and the second active material layer are arranged on the electrode plateThe active material compositions of the two active material layers are the same, and the difference of the specific surface area of the active material particles of the first active material layer and the second active material layer is 0.2m2/g～8m2/g；
Optionally, the electrode plate is a negative electrode plate, the active material components of the first active material layer and the second active material layer are different, and the difference between the specific surface areas of the active material particles of the first active material layer and the second active material layer is 0.5m2/g～8m2/g。
6. The pole piece of claim 1, wherein the pole piece is a positive pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference of the gram capacities of the active material particles of the first active material layer and the second active material layer is 10mAh/g to 60 mAh/g;
optionally, the pole piece is a positive pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 20 mAh/g-110 mAh/g;
optionally, the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are the same, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 10 mAh/g-100 mAh/g;
optionally, the pole piece is a negative pole piece, the active material components of the first active material layer and the second active material layer are different, and the difference between the gram capacities of the active material particles of the first active material layer and the second active material layer is 10mAh/g to 200 mAh/g.
7. The pole piece according to any one of claims 1 to 6, wherein the pole piece is a positive pole piece, and the difference between the thicknesses of the first active material layer and the second active material layer is 5 μm to 50 μm;
optionally, the pole piece is a negative pole piece, and the difference between the thicknesses of the first active material layer and the second active material layer is 5 μm to 100 μm.
8. The pole piece of any one of claims 1 to 6, wherein the difference between the thicknesses of the first active material layer and the second active material layer is 5 μm to 50 μm.
9. A pole piece assembly is characterized by comprising a diaphragm and two pole pieces which are positioned on two sides of the diaphragm and have opposite polarities;
at least one of the two pole pieces is a pole piece according to any one of claims 1 to 8.
10. The pole piece assembly of claim 9, wherein either one of the positive and negative current collectors of the pole piece assembly is a composite current collector and the other is a metal foil current collector.
CN202111188969.2A 2021-10-12 2021-10-12 Pole piece and pole piece assembly Pending CN113764619A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114256501A (en) * 2021-12-17 2022-03-29 珠海冠宇电池股份有限公司 Negative plate and lithium ion battery containing same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114256501A (en) * 2021-12-17 2022-03-29 珠海冠宇电池股份有限公司 Negative plate and lithium ion battery containing same

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