WO2023137586A1 - 一种电极极片、电化学装置和电子装置 - Google Patents

一种电极极片、电化学装置和电子装置 Download PDF

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Publication number
WO2023137586A1
WO2023137586A1 PCT/CN2022/072533 CN2022072533W WO2023137586A1 WO 2023137586 A1 WO2023137586 A1 WO 2023137586A1 CN 2022072533 W CN2022072533 W CN 2022072533W WO 2023137586 A1 WO2023137586 A1 WO 2023137586A1
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Prior art keywords
insulating layer
electrode sheet
present application
polymer particles
molecular polymer
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PCT/CN2022/072533
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English (en)
French (fr)
Inventor
张远杰
冯波
苏义松
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Dongguan Amperex Technology Ltd
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Dongguan Amperex Technology Ltd
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Priority to EP22921036.4A priority Critical patent/EP4465377A4/en
Priority to CN202280004147.0A priority patent/CN115606015A/zh
Priority to PCT/CN2022/072533 priority patent/WO2023137586A1/zh
Publication of WO2023137586A1 publication Critical patent/WO2023137586A1/zh
Priority to US18/776,571 priority patent/US20240372160A1/en
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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
    • 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
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • H01M50/593—Spacers; Insulating plates
    • 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

Definitions

  • the present application relates to the field of electrochemistry, in particular to an electrode pole piece, an electrochemical device and an electronic device.
  • lithium-ion batteries are widely used in wearable devices, smart phones, unmanned aerial vehicles, electric vehicles, and large-scale energy storage equipment.
  • the separator in the lithium-ion battery is located between the positive pole piece and the negative pole piece, and has the function of isolating the positive pole piece and the negative pole piece and conducting lithium ions at the same time.
  • the positive pole piece and the negative pole piece may come into contact, thereby forming an electronic circuit and causing an internal short circuit, which reduces the safety of the lithium-ion battery. Therefore, there is an urgent need to develop an electrode pole piece to simultaneously improve the stability and safety performance of lithium-ion batteries.
  • the purpose of this application is to provide an electrode pole piece, an electrochemical device and an electronic device, so as to improve the stability and safety performance of the electrochemical device.
  • the first aspect of the present application provides an electrode sheet, including a current collector, an active material layer, and an insulating layer, wherein the active material layer is disposed between the current collector and the insulating layer;
  • the insulating layer includes an insulating inorganic substance, a binder, and a high molecular polymer, wherein the high molecular polymer includes high molecular polymer particles, and the number of exposed high molecular polymer particles in any 45 ⁇ m ⁇ 27 ⁇ m area on the surface of the insulating layer is 2 to 60.
  • the high molecular polymer particles exposed on the surface of the insulating layer will bond with the adhesive layer particles on the surface of the isolation film.
  • the adhesive layer particles are usually also high molecular polymers, and the adhesive layer particles of the isolation film can exhibit a strong fusion bonding effect with the high molecular polymer in the pole piece insulating layer.
  • the exposed area of a single particle of the polymer particles exposed on the surface of the insulating layer is 20 ⁇ m 2 to 315 ⁇ m 2 .
  • the insulating inorganic substance includes at least one of aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide, or zinc oxide.
  • the high molecular polymer includes at least one of polyvinylidene fluoride, polyethylene or polypropylene.
  • the electrode sheet is at least one of a positive electrode sheet or a negative electrode sheet.
  • the second aspect of the present application provides an electrochemical device, including a separator, and the electrode sheet.
  • the electrode pole piece provided by the present application has a good interface bonding effect, which is beneficial to simultaneously improve the stability and safety performance of the electrochemical device.
  • the base material of the isolation film is made of the same material as the polymer, and there is no adhesive layer on the surface of the isolation film in contact with the insulating layer.
  • the base material of the isolation film is made of a different material from the polymer, and an adhesive layer is provided on the surface of the isolation film in contact with the insulating layer.
  • the binder in the binder layer includes at least one of polyvinylidene fluoride, polyacrylate, polyacrylic acid, polymethylmethacrylate, polyacrylonitrile, polyamide, polyimide, aramid, polyacrylate, styrene-butadiene rubber, polyacrylamide or polyolefin.
  • the third aspect of the present application provides an electronic device, comprising the electrochemical device described in any embodiment of the present application.
  • the electrochemical device provided by the application has good stability and safety performance, so the electronic device provided by the application has good stability and safety performance.
  • the present application provides an electrode pole piece, an electrochemical device, and an electronic device.
  • the electrode pole piece includes a current collector, an active material layer, and an insulating layer, wherein the active material layer is disposed between the current collector and the insulating layer, and the insulating layer includes an insulating inorganic substance, a binder, and a high molecular polymer.
  • the high molecular polymer includes high molecular polymer particles, and the number of the high molecular polymer particles exposed in any 45 ⁇ m ⁇ 27 ⁇ m area on the surface of the insulating layer is 2 to 60. In the present application, the polymer particles exposed on the surface of the insulating layer will bond with the particles of the bonding layer on the surface of the separator.
  • the particles of the bonding layer are usually polymers, and the particles of the bonding layer of the separator can exhibit a strong fusion and bonding effect with the polymer in the insulating layer of the pole piece, thereby improving the interface adhesion between the pole piece and the separator, and enhancing the deformation resistance of the electrochemical device, thereby helping to improve the stability and safety of the electrochemical device.
  • FIG. 1 is a scanning electron microscope image of the surface of the insulating layer containing polymer particles in Example 2.
  • FIG. 2 is a scanning electron micrograph of a cross-section of an insulating layer containing polymer particles in Example 2.
  • FIG. 2 is a scanning electron micrograph of a cross-section of an insulating layer containing polymer particles in Example 2.
  • FIG. 3 is a schematic diagram of an insulating layer structure according to an embodiment of the present application.
  • Fig. 4 is a scanning electron microscope image of the insulating layer surface of a conventional pole piece (comparative example 1).
  • FIG. 5 is a scanning electron microscope image of a cross-section of an insulating layer of a conventional pole piece (Comparative Example 1).
  • FIG. 6 is a scanning electron microscope image of the surface of the insulating layer of the pole piece after hot pressing in Example 2.
  • Example 7 is a scanning electron microscope image of the cross-section of the insulation layer of the pole piece after hot pressing in Example 2.
  • Fig. 8 is a scanning electron microscope image of the surface of the insulating layer with low content of polymer particles.
  • Fig. 9 is a scanning electron microscope image of the surface of the insulating layer with high polymer particles content.
  • a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • the insulating coating on the surface of the electrode pole piece (hereinafter referred to as the pole piece) usually includes an insulating substance and a binder, but since the binder in the insulating coating only plays the role of bonding the insulating substance, it cannot directly bond with the separator.
  • the bonding between the separator and the insulating coating on the surface of the pole piece can only rely on the binder of the separator itself, and the high bonding effect between the pole piece and the separator has a direct effect on improving the deformation resistance and hardness of the electrochemical device.
  • the present application provides an electrode pole piece, an electrochemical device and an electronic device, so as to improve the stability and safety performance of the electrochemical device.
  • the first aspect of the present application provides an electrode sheet, including a current collector, an active material layer, and an insulating layer, wherein the active material layer is disposed between the current collector and the insulating layer; the insulating layer includes an insulating inorganic substance, a binder, and a polymer.
  • the high molecular polymer includes high molecular polymer particles, and the number of exposed high molecular polymer particles in any 45 ⁇ m ⁇ 27 ⁇ m area on the surface of the insulating layer is 2 to 60.
  • the inventors of the present application have found that if there are too few exposed polymer particles per unit area of the insulating layer, the bonding effect between the pole piece and the separator will be affected; if there are too many exposed polymer particles, there will be too many bonding sites between the pole piece surface insulating layer and the separator, and after the pole piece is hot-pressed, the covered area will be too large, resulting in the blockage of the transmission channel of lithium ions in the covered area, so that the transmission of lithium ions cannot be carried out or the resistance is too large, affecting the kinetic performance of the electrochemical device. Therefore, by controlling the number of exposed polymer particles per unit area of the insulating layer within the above range, the bonding effect between the pole piece and the separator can be improved, thereby improving the stability and safety performance of the electrochemical device.
  • k 1 Dv50/d
  • Dv50 refers to the particle diameter from the small particle diameter side to 50% of the cumulative volume in the volume-based particle size distribution (can be measured using a laser particle size tester).
  • the Dv50 of the high molecular polymer particles is a statistical value, and among these high molecular polymer particles, some particles have a diameter larger than Dv50, and some particles have a diameter smaller than Dv50.
  • the polymer particles of the present application include particles with a diameter of D, and the particles with a diameter of D refer to those particles in which 1 ⁇ k 2 ⁇ 3 in the polymer particles, where k 2 is the ratio of the diameter D to the thickness of the insulating layer d ⁇ m.
  • the particles with diameter D in the high molecular polymer particles may include particles with a diameter greater than 4 ⁇ m and less than or equal to 12 ⁇ m; when the Dv50 of the high molecular polymer particles is 6 ⁇ m and the thickness of the insulating layer is 2 ⁇ m, the particles with diameter D in the high molecular polymer particles may include particles with a diameter greater than 2 ⁇ m and less than or equal to 6 ⁇ m.
  • the inventors of the present application found that after adding one or more polymers to the insulating layer of the electrode pole piece, since the polymer has a larger particle size, as shown in Figures 1 and 2, the polymer is exposed on the surface of the insulating layer in the form of a single particle or a cluster of polymers.
  • the polymer particles exposed on the surface of the insulating layer will bond with the particles of the adhesive layer on the surface of the separator.
  • the particles of the adhesive layer are usually polymers, and the particles in the adhesive layer of the separator can show a strong fusion and bonding effect with the polymer in the insulating layer of the pole piece, thereby improving the interfacial adhesion between the pole piece and the separator.
  • the design of polymer particles in the insulating layer of the pole piece can significantly improve the interfacial adhesion between the insulating layer and the isolation film and the cohesion of the inorganic particles in the insulating layer, and improve the overall resistance to deformation of the electrochemical device, thereby helping to improve the stability and safety of the electrochemical device.
  • FIG. 2 In the scanning electron microscope (SEM) test of the sample, argon ion cutting technology, also known as ion milling section polishing technology, is used to polish the sample surface to remove the damaged layer, so as to obtain high-quality samples.
  • SEM scanning electron microscope
  • the conventional pole piece is exposed on the surface of the pole piece insulating layer due to no polymer particles, as shown in Figure 4 and Figure 5.
  • the surface of the pole piece insulating layer presents a flat surface with some pores and a slightly rough surface, without significant protruding points, and only the bonding layer particles on the surface of the separator are bonded to the inorganic particles in the pole piece insulating layer. Since the inorganic particles in the insulating layer of the pole piece usually have a certain regular shape, the bonding effect of the particles of the bonding layer on the surface of the separator and the insulating layer is not good, so that the bonding effect between the pole piece and the separator is limited.
  • the exposed area of a single particle of the polymer particles exposed on the surface of the insulating layer is 20 ⁇ m 2 to 315 ⁇ m 2 .
  • the exposed area of a single polymer particle is too small, it will affect the bonding effect between the pole piece interface; if the exposed area of a single high molecular polymer particle is too large, although the bonding effect between the pole piece and the separator is significantly improved, it will cause serious blockage of the pores on the surface of the pole piece, resulting in a decrease in the porosity of the pole piece and a reduction in the kinetic performance of the electrochemical device. Therefore, making the exposed area of a single polymer particle within the above-mentioned range can improve the bonding effect of the pole piece interface, thereby improving the stability and safety performance of the electrochemical device.
  • the present application has no particular limitation on the insulating inorganic substance, as long as the purpose of the present application can be achieved.
  • the insulating inorganic substance includes at least one of aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide, or zinc oxide.
  • the present application has no special limitation on the high molecular polymer, as long as the purpose of the present application can be achieved.
  • the high molecular polymer includes at least one of polyvinylidene fluoride, polyethylene or polypropylene.
  • the present application has no special limitation on the binder in the insulating layer, as long as the purpose of the present application can be achieved.
  • the binder includes at least one of polyacrylate, polyacrylic acid, polyacrylate, polymethylmethacrylate, polyacrylonitrile, polyamide, or sodium carboxymethylcellulose.
  • the present application has no special limitation on the type of the electrode pole piece, as long as the purpose of the present application can be achieved.
  • the electrode sheet is at least one of a positive electrode sheet or a negative electrode sheet.
  • the positive electrode sheet generally includes a positive electrode current collector.
  • This application has no special restrictions on the positive electrode current collector, as long as the purpose of this application can be achieved, for example, it may include but not limited to aluminum foil, aluminum alloy foil or composite current collector.
  • the thickness of the positive electrode collector there is no particular limitation on the thickness of the positive electrode collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8 ⁇ m to 12 ⁇ m.
  • the positive electrode active material layer may be disposed on one surface in the thickness direction of the positive electrode current collector, or may be disposed on two surfaces in the thickness direction of the positive electrode current collector. It should be noted that the "surface” here may refer to the entire area of the positive electrode collector or a partial area of the positive electrode collector. This application is not particularly limited, as long as the purpose of this application can be achieved.
  • the active material layer of the positive electrode includes a positive electrode active material.
  • the present application has no special restrictions on the type of the positive electrode active material, as long as the purpose of the present application can be achieved.
  • the positive electrode active material can include at least one of lithium nickel cobalt manganese oxide (811, 622, 523, 111), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganate, lithium manganese iron phosphate, or lithium titanate.
  • the positive electrode active material may also contain non-metallic elements, for example, non-metallic elements include at least one of fluorine, phosphorus, boron, chlorine, silicon, sulfur, etc., and these elements can further improve the stability of the positive electrode material.
  • non-metallic elements include at least one of fluorine, phosphorus, boron, chlorine, silicon, sulfur, etc., and these elements can further improve the stability of the positive electrode material.
  • the positive electrode active material layer may also include a positive electrode binder.
  • the present application has no particular limitation on the positive electrode binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to at least one of fluorine-containing resin, polypropylene resin, fiber-type binder, rubber-type binder or polyimide-type binder.
  • the positive electrode active material layer can also include a positive electrode conductive agent.
  • the present application has no special restrictions on the positive electrode conductive agent, as long as the purpose of the application can be achieved, for example, it can include but not limited to at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber, acetylene black, flake graphite, Ketjen black, graphene, metal materials or conductive polymers.
  • the positive electrode conductive agent includes conductive carbon black and carbon nanotubes.
  • the aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the aforementioned carbon fibers may include, but are not limited to, vapor grown carbon fibers (VGCF) and/or carbon nanofibers.
  • the above metal material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the above-mentioned conductive polymer may include but not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • positive electrode active material positive electrode binder, and positive electrode conductive agent
  • conventional contents in this field can be used, as long as the purpose of this application can be achieved.
  • the mass percentage of the positive electrode active material is 90% to 98%
  • the mass percentage of the positive electrode binder is 0.5% to 5%
  • the mass percentage of the positive electrode conductive agent is 0.5% to 5%.
  • the positive electrode sheet may further include a conductive layer located between the positive electrode current collector and the positive electrode active material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, for example, may include but not limited to the above-mentioned positive electrode conductive agent and the above-mentioned positive electrode binder.
  • the negative electrode sheet usually includes a negative electrode collector.
  • This application has no special restrictions on the negative electrode collector, as long as the purpose of this application can be achieved, for example, it may include but not limited to copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or composite current collectors.
  • the thickness of the current collector of the negative electrode there is no particular limitation on the thickness of the current collector of the negative electrode, as long as the purpose of the present application can be achieved, for example, the thickness is 4 ⁇ m to 12 ⁇ m.
  • the negative electrode active material layer may be disposed on one surface in the thickness direction of the negative electrode current collector, or may be disposed on two surfaces in the thickness direction of the negative electrode current collector. It should be noted that the "surface” here may be the entire area of the negative electrode collector, or a partial area of the negative electrode collector. This application is not particularly limited, as long as the purpose of this application can be achieved.
  • the negative electrode active material layer includes the negative electrode active material, wherein the negative electrode active material is not particularly limited, as long as the purpose of the application can be achieved, for example, the negative electrode active material includes a carbon material that can reversibly intercalate/deintercalate lithium ions.
  • the carbon material may be a carbon material known in the art to be used as an anode active material, for example, the carbon material may include but not limited to crystalline carbon and/or amorphous carbon.
  • the aforementioned crystalline carbon may include, but is not limited to, amorphous, plate-shaped, platelet-shaped, spherical or fibrous natural graphite or artificial graphite.
  • the aforementioned amorphous carbon may include, but is not limited to, at least one of soft carbon, hard carbon, mesophase pitch carbide, or calcined coke.
  • the negative electrode active material may include, but not limited to, at least one of natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon oxide (SiO x , x is 1 or 2) or a silicon-carbon composite.
  • the mass ratio of silicon and carbon in the silicon-carbon composite is 1:10 to 10:1, and the Dv50 is 0.1 ⁇ m to 100 ⁇ m.
  • the negative electrode active material layer may also include a negative electrode conductive agent.
  • the present application has no special limitation on the negative electrode conductive agent, as long as the purpose of the application can be achieved, for example, it may include but not limited to at least one of carbon-based materials, metal-based materials or conductive polymers.
  • the above-mentioned carbon-based material is at least one selected from natural graphite, artificial graphite, conductive carbon black, acetylene black, Ketjen black or carbon fiber.
  • the above-mentioned metal-based material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the conductive polymer may include, but is not limited to, at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene, or polypyrrole.
  • the negative electrode active material layer may also include a negative electrode binder.
  • the application has no special restrictions on the negative electrode binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylic acid ( At least one of esterified styrene-butadiene rubber, epoxy resin or nylon.
  • the negative electrode sheet may further include a conductive layer located between the negative electrode current collector and the negative electrode active material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, and the conductive layer may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • the second aspect of the present application provides an electrochemical device, which includes a separator, and the electrode sheet.
  • the electrode pole piece provided by the present application has a good interface bonding effect, which is beneficial to simultaneously improve the stability and safety performance of the electrochemical device.
  • the present application has no particular limitation on the isolation film, as long as the purpose of the application can be achieved, for example, it may include but not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene-based polyolefin (PO) isolation film, polyester film (such as polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide film (PA), spandex, aramid film, woven film, non-woven film (non-woven), microporous film, composite film, diaphragm paper, roll At least one of pressed or spun films, preferably polyethylene or polypropylene, have a good effect on preventing short circuits and can improve the stability of electrochemical devices through the shutdown effect.
  • PET polyethylene terephthalate
  • PI polyimide film
  • PA polyamide film
  • aramid film woven film
  • non-woven film non-woven film
  • microporous film composite film
  • diaphragm paper roll
  • the separator of the present application may have a porous structure, and the pore size is not particularly limited as long as the purpose of the present application can be achieved, for example, the pore size may be 0.01 ⁇ m to 1 ⁇ m.
  • the thickness of the isolation film is not particularly limited, as long as the purpose of the present application can be achieved, for example, the thickness may be 5 ⁇ m to 500 ⁇ m.
  • the base material of the isolation film is made of the same material as the polymer, and there is no adhesive layer on the surface of the isolation film in contact with the insulating layer.
  • the base material of the isolation film is made of a different material from the polymer, and an adhesive layer is provided on the surface of the isolation film in contact with the insulating layer.
  • the present application has no particular limitation on the adhesive in the adhesive layer of the separator, as long as the purpose of the present application can be achieved.
  • the binder in the binder layer includes at least one of polyvinylidene fluoride, polyacrylate, polyacrylic acid, polymethylmethacrylate, polyacrylonitrile, polyamide, polyimide, aramid, polyacrylate, styrene-butadiene rubber, polyacrylamide or polyolefin.
  • the electrochemical device may further include an electrolyte, which may include, but not limited to, one or more of a gel electrolyte, a solid electrolyte, and an electrolytic solution.
  • the electrolytic solution may include a lithium salt and a non-aqueous solvent.
  • lithium salts can be selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , Li 2 SiF 6 , LiBOB or at least one of lithium difluoroborate.
  • the lithium salt comprises LiPF 6 .
  • the present application has no special limitation on the non-aqueous solvent, as long as the purpose of the present application can be achieved, for example, it may include but not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • the above-mentioned carbonate compound may include but not limited to at least one of chain carbonate compound, cyclic carbonate compound or fluorocarbonate compound.
  • Above-mentioned chain carbonate compound can include but not limited to at least one in dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC) or methyl ethyl carbonate (MEC).
  • the above-mentioned cyclic carbonate may include but not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinylethylene carbonate (VEC).
  • Fluorocarbonate compounds may include, but are not limited to, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2- At least one of methyl ethylene ester or trifluoromethyl ethylene carbonate.
  • the above-mentioned carboxylate compound may include but not limited to at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decanolactone, valerolactone, mevalonolactone or caprolactone.
  • the aforementioned ether compound may include but not limited to at least one of dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.
  • the electrochemical device of the present application is not particularly limited, and it may include any device that undergoes an electrochemical reaction.
  • electrochemical devices may include, but are not limited to, primary batteries, secondary batteries, fuel cells, solar cells, or capacitors, among others.
  • the electrochemical device is a lithium secondary battery
  • the secondary battery may include, but not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery. More preferably, the electrochemical device is a lithium ion battery.
  • the preparation process of the electrochemical device is well known to those skilled in the art, and the present application is not particularly limited.
  • it may include but not limited to the following steps: stack the positive pole piece, the separator and the negative pole piece in sequence, and wind and fold them as required to obtain an electrode assembly with a winding structure, put the electrode assembly into a packaging bag, inject the electrolyte into the packaging bag and seal it to obtain an electrochemical device;
  • the four corners of the sheet structure are fixed to obtain an electrode assembly with a laminated sheet structure, the electrode assembly is placed in a packaging bag, the electrolyte is injected into the packaging bag and sealed to obtain an electrochemical device.
  • overcurrent prevention elements, guide plates, etc. can also be placed in the packaging bag as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the third aspect of the present application provides an electronic device, comprising the electrochemical device described in any embodiment of the present application.
  • the electrochemical device provided by the application has good stability and safety performance, so the electronic device provided by the application has good stability and safety performance.
  • the electronic device of the application is not particularly limited, and it may be any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, video recorders, LCD televisions, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, power-assisted bicycles, power tools, drones, handheld vacuum cleaners, bicycles, lighting appliances, toys, games Machines, clocks, electric tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • the positive electrode active material lithium cobaltate, the conductive agent acetylene black, and the binder polyvinylidene fluoride were mixed according to a mass ratio of 98:0.8:1.2, N-methylpyrrolidone (NMP) was added, and stirred evenly under the action of a vacuum mixer to obtain a positive electrode slurry, wherein the solid content of the positive electrode slurry was 70 wt%.
  • the positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 12 ⁇ m, and the aluminum foil was dried at 85° C. to obtain a positive electrode sheet coated with a positive electrode material layer on one side.
  • Negative electrode active material artificial graphite, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose are mixed according to a mass ratio of 98:1:1, deionized water is added, and negative electrode slurry is obtained under the action of a vacuum mixer, wherein the solid content of the negative electrode slurry is 75wt%.
  • the negative electrode slurry was evenly coated on one surface of the negative electrode current collector copper foil with a thickness of 12 ⁇ m, and the copper foil was dried at 85° C. to obtain a negative electrode sheet coated with a negative electrode material layer on one side. Repeat the above steps on the other surface of the copper foil to obtain a negative electrode sheet coated with a negative electrode material layer on both sides.
  • the insulating layer slurry was uniformly coated on the surface of the negative electrode sheet prepared in 1), and dried at 85°C, wherein the thickness of the insulating layer was 0.67 ⁇ m, and then the negative electrode sheet coated with the insulating layer was cold-pressed, cut into pieces, and slit, and then dried under vacuum conditions at 85°C for 12 hours to obtain a composite negative electrode sheet with a size of 74mm ⁇ 867mm and a thickness of 0.113mm with an insulating layer.
  • a porous polyethylene film (provided by Celgard) with a thickness of 7 ⁇ m and a pore size of 0.1 ⁇ m is used. Polyacrylate is used on the surface of the isolation membrane.
  • the coating quality of the adhesive layer is 10 ⁇ 2mg/5000mm 2 and the thickness is 3 ⁇ 1 ⁇ m.
  • the electrode assembly is obtained by winding.
  • the electrode assembly in an aluminum-plastic film packaging bag, inject electrolyte after drying, and obtain a lithium-ion battery through processes such as vacuum packaging, standing, chemical formation, degassing, and edge trimming.
  • the formation upper limit voltage is 4.45V
  • the formation temperature is 80°C
  • the formation resting time is 2h.
  • Example 1 Except for adjusting relevant preparation parameters as shown in Table 1, all the other are the same as Example 1.
  • Example 1 Except ⁇ preparation of positive electrode sheet> and ⁇ preparation of negative electrode sheet> are different from Example 1, the rest are the same as Example 1.
  • the insulating layer slurry was evenly coated on the surface of the positive electrode piece prepared in 1), and dried at 85°C, wherein the thickness of the insulating layer was 10 ⁇ m, and then the positive electrode piece coated with the insulating layer was cold-pressed, cut into pieces, and slit, and then dried under vacuum conditions at 85°C for 12 hours to obtain a composite positive electrode piece with a size of 72mm ⁇ 850mm including an insulating layer.
  • Negative electrode active material artificial graphite, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose are mixed according to a mass ratio of 98:1:1, deionized water is added, and the negative electrode slurry is obtained under the action of a vacuum mixer, wherein the solid content of the negative electrode slurry is 75wt%.
  • the negative electrode slurry was evenly coated on one surface of the negative electrode current collector copper foil with a thickness of 12 ⁇ m, and the copper foil was dried at 85° C. to obtain a negative electrode sheet coated with a negative electrode material layer on one side. Repeat the above steps on the other surface of the copper foil to obtain a negative electrode sheet coated with a negative electrode material layer on both sides.
  • the negative pole piece was dried under vacuum at 85°C for 12 hours to obtain a negative pole piece with a size specification of 74mm ⁇ 867mm and a thickness specification of 0.113mm.
  • Example 10 Except for adjusting relevant preparation parameters as shown in Table 1, the rest are the same as in Example 10.
  • a porous polypropylene film with a thickness of 7 ⁇ m and a pore size of 0.1 ⁇ m was used.
  • Example 12 Except for adjusting relevant preparation parameters as shown in Table 1, the rest are the same as in Example 12.
  • Example 1 Except that ⁇ preparation of insulating layer slurry> is different from Example 1, the rest is the same as Example 1.
  • Example 1 Except for adjusting relevant preparation parameters as shown in Table 1, all the other are the same as Example 1.
  • the pole piece to be tested is vertically impacted with an ion beam to obtain a fresh cross-section, and a scanning electron microscope (SEM) is used to take images of the cross-section. Measure the diameter of the equivalent maximum circle of the high molecular polymer particles in the insulating layer of the section, and the diameter D of the high molecular polymer particles is equal to the diameter of the equivalent maximum circle.
  • SEM scanning electron microscope
  • the length of the cross-section is ⁇ 1mm (for example, 1mm), and 20 SEM photos are taken at equal distances, and the magnification is ⁇ 1000 times (for example, 1000 times).
  • a place with uniform flatness is selected as a measurement point, and the thickness of the insulating layer is measured. The data of all the measurement points is counted to obtain the median thickness data, and the thickness d of the insulating layer is equal to the median thickness.
  • the lithium ion battery prepared in the embodiment and the comparative example is discharged to its operating voltage lower limit with 0.1C rate (C), then from the lithium ion battery prepared by embodiment 1 to embodiment 7, embodiment 10 to embodiment 11, comparative example 2 to comparative example 7, take out the composite body of negative pole piece and separator, then after the composite body of negative pole piece and separator is spread and naturally air-dried for 1 hour (h), get a test sample with a width of 30 mm and a length of 150 mm with a blade; From the lithium-ion battery prepared in Example 9, take out the composite of the positive pole piece and the separator, spread the composite of the positive pole piece and the separator and air-dry it naturally for 1 hour, and then take a test sample with a width of 30 mm and a length of 150 mm with a blade.
  • C 0.1C rate
  • the test sample to the test fixture of the high-speed rail tensile machine for bond strength testing (peeling angle 90 degrees, tensile speed 50mm/min, tensile displacement 60mm).
  • peeling angle 90 degrees, tensile speed 50mm/min, tensile displacement 60mm When the peeling interface is the insulation layer and the isolation film layer, the measured result is the bonding strength between the insulation layer and the isolation film.
  • the number of discs is greater than 40, and the surface of the discs is flat without gaps; the positive pole pieces are taken out separately from the lithium-ion batteries prepared in Examples 8 to 9, and then the positive pole pieces are soaked in pure DMC solvent for 1 hour.
  • porosity is defined as the ratio of the pore volume of the sample to the total volume of the sample, which reflects the number of pores in the sample, which plays a key role in the ion transmission in lithium-ion batteries.
  • the real volume is defined as the volume of the sample without pores.
  • lithium-ion batteries prepared in Examples and Comparative Examples in a constant temperature box at 25°C, keep them warm for 1 hour, charge them at a constant current of 1C to 4.45V, charge them at a constant voltage of 4.45V to 0.02C, let them stand for 3 minutes, then discharge them at a constant current of 1C to 3V, let them stand for 3 minutes, and cycle them 10 times in this way. Decompose the lithium-ion battery and observe whether there is lithium precipitation on the surface of the negative electrode sheet.
  • the exposed polymer particles or the exposed surface of the clustered polymer on the surface of the insulating layer are observed perpendicular to the surface of the pole piece sample.
  • the maximum distance between the two points is the equivalent circle diameter D of the exposed surface of the polymer particle or cluster.
  • Comparative Example 2 to Comparative Example 3 From Example 1 to Example 3, Comparative Example 2 to Comparative Example 3, it can be seen that when the added polymer particle size Dv50 in the insulating layer is too small (such as Comparative Example 2), the bonding strength between the pole piece and the separator will be reduced, causing the bonding effect between the pole piece interface to be insignificant, which is not conducive to improving the stability of the electrochemical device; phenomenon, which has certain potential safety hazards, which is not conducive to improving the safety of electrochemical devices.
  • Example 2 Example 4 to Example 5, Comparative Example 4 to Comparative Example 5, when k 1 When k 1 When it is too large, a single polymer particle has more volume exposed above the surface of the insulating layer, but because the polymer particles expose too much volume on the surface of the insulating layer, after the hot-pressing process for making lithium-ion batteries, it will cause local pores on the surface of the pole piece to be blocked, resulting in a decrease in the porosity of the pole piece, resulting in the phenomenon of lithium precipitation in the lithium-ion battery, which has certain safety hazards, which is not conducive to improving the safety of electrochemical devices.
  • Example 4 and Example 10 From Example 3 and Example 11, Example 4 and Example 10, it can be seen that coating the same design of the insulating layer on the positive pole piece or the negative pole piece has no significant effect on the bonding strength between the insulating layer and the separator.
  • Example 6 and Example 12 Example 9 and Example 13 it can be seen that when the material of the separator substrate and the high polymer in the insulating layer are the same, although no adhesive layer is coated on the surface of the separator, the bonding effect between the pole piece and the separator does not deteriorate, thereby simplifying the design of the separator. device stability.

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Abstract

本申请提供了一种电极极片、电化学装置和电子装置，电极极片包括集流体、活性材料层以及绝缘层，其中，活性材料层设置于集流体与所述绝缘层之间；绝缘层包括绝缘无机物、粘结剂和高分子聚合物，其中，高分子聚合物包括高分子聚合物颗粒，在绝缘层表面任意45μm×27μm区域内裸露的高分子聚合物颗粒的数量为2个至60个。通过调控绝缘层单位面积上裸露的高分子聚合物颗粒的数量在上述范围内，可以显著提升电极极片与隔离膜之间的粘结效果，增强电化学装置的抗变形能力，从而有利于提高电化学装置的稳定性能和安全性能。

Description

一种电极极片、电化学装置和电子装置 技术领域
本申请涉及电化学领域，特别是涉及一种电极极片、电化学装置和电子装置。
背景技术
锂离子电池由于具有高能量密度、长循环寿命及无记忆效应等优点而被广泛应用于穿戴设备、智能手机、无人机、电动汽车及大型储能等设备等领域，已成为当今世界最具发展潜力的新型绿色化学电源，但也对锂离子电池的安全性能提出更高的要求。
其中，锂离子电池中的隔离膜位于正极极片与负极极片之间，有隔绝正极极片与负极极片且同时导通锂离子的作用。但是在异物刺破隔离膜等极端条件下，正极极片与负极极片可能会接触，从而形成电子回路导致内部短路发生，降低锂离子电池的安全性。因此，亟待开发一种电极极片，以同时提高锂离子电池的稳定性能和安全性能。
发明内容
本申请的目的在于提供一种电极极片、电化学装置和电子装置，以提高电化学装置的稳定性能和安全性能。
本申请的第一方面提供了一种电极极片，包括集流体、活性材料层以及绝缘层，其中，所述活性材料层设置于所述集流体与所述绝缘层之间；所述绝缘层包括绝缘无机物、粘结剂和高分子聚合物，其中，所述的高分子聚合物包括高分子聚合物颗粒，在所述绝缘层表面任意45μm×27μm区域内裸露的所述高分子聚合物颗粒的数量为2个至60个。
本申请的有益效果：本申请中，裸露在绝缘层表面的高分子聚合物颗粒会与隔离膜表面的粘结层粒子进行粘结，这种粘结层粒子通常也为高分子聚合物，而这种隔离膜粘结层粒子可以与极片绝缘层中的高分子聚合物之间表现出很强的融合粘结作用。通过调控绝缘层单位面积上裸露的高分子聚合物颗粒的数量在上述范围内，能够提升电极极片界面的粘结效果，从而提高电化学装置的稳定性能和安全性能。
在本申请的一些实施方式中，所述高分子聚合物颗粒的Dv50为1μm至20μm，所述高分子聚合物颗粒Dv50与所述绝缘层厚度dμm的比值为k 1＝Dv50/d，满足1≤k 1≤3。通过调控k 1在上述范围内，可以显著提升电极极片与隔离膜之间的粘结效果，增强电化学装置的抗变形能力，从而有利于提高电化学装置的稳定性能和安全性能。
在本申请的一些实施方式中，所述高分子聚合物颗粒中包含直径D的颗粒，所述直径D与所述绝缘层厚度dμm的比值为k 2＝D/d，满足1<k 2≤3。通过调控k 2在上述范围内，可以显著提升电极极片与隔离膜之间的粘结效果，增强电化学装置的抗变形能力，从而有利于提高电化学装置的稳定性能和安全性能。
在本申请的一些实施方式中，在绝缘层表面上裸露的所述高分子聚合物颗粒中单个颗粒的裸露面积为20μm 2至315μm 2。
在本申请的一些实施方式中，所述绝缘无机物包括三氧化二铝、二氧化钛、氧化镁、氧化锆或氧化锌中的至少一种。
在本申请的一些实施方式中，所述高分子聚合物包括聚偏氟乙烯、聚乙烯或聚丙烯中的至少一种。
在本申请的一些实施方式中，所述电极极片为正极极片或负极极片中的至少一种。
本申请第二方面提供了一种电化学装置，包含隔离膜，以及所述的电极极片。本申请提供的电极极片具有良好的界面粘结效果，从而有利于同时提高电化学装置的稳定性能和安全性能。
在本申请的一些实施方式中，所述隔离膜的基材与所述高分子聚合物具有相同的材质，其中，所述隔离膜与所述绝缘层接触的表面上无粘结剂层。
在本申请的一些实施方式中，所述隔离膜的基材与所述高分子聚合物具有不同的材质，其中，所述隔离膜与所述绝缘层接触的表面上有粘结剂层。
在本申请的一些实施方式中，所述粘结剂层中的粘结剂包括聚偏氟乙烯、聚丙烯酸盐、聚丙烯酸、聚甲基丙烯酸甲酯、聚丙烯腈、聚酰胺、聚酰亚胺、芳纶、聚丙烯酸酯、丁苯橡胶、聚丙烯酰胺或聚烯烃中的至少一种。
本申请第三方面提供了一种电子装置，包含本申请任一实施方案中所述的电化学装置。本申请提供的电化学装置具有良好的稳定性能和安全性能，从而本申请提供的电子装置具有良好的稳定性能和安全性能。
本申请提供了一种电极极片、电化学装置以及电子装置，电极极片包括集流体、活性材料层以及绝缘层，其中，所述活性材料层设置于所述集流体与所述绝缘层之间，所述绝缘层包括绝缘无机物、粘结剂和高分子聚合物，高分子聚合物包括高分子聚合物颗粒，在绝缘层表面任意45μm×27μm区域内裸露的所述高分子聚合物颗粒的数量为2个至60个。本申请中，裸露在绝缘层表面的高分子聚合物颗粒会与隔离膜表面的粘结层粒子进行粘结， 这种粘结层粒子通常也为高分子聚合物，而这种隔离膜粘结层粒子可以与极片绝缘层中的高分子聚合物之间表现出很强的融合粘结作用，进而提升极片与隔离膜之间的界面粘结力，增强电化学装置的抗变形能力，从而有利于提高电化学装置的稳定性能和安全性能。
附图说明
为了更清楚地说明本申请实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例。
图1为实施例2中含高分子聚合物颗粒的绝缘层表面扫描电镜图。
图2为实施例2中含高分子聚合物颗粒的绝缘层横截面扫描电镜图。
图3为本申请一种实施方案的绝缘层结构示意图。
图4为常规极片(对比例1)的绝缘层表面扫描电镜图。
图5为常规极片(对比例1)的绝缘层横截面扫描电镜图。
图6为实施例2热压后的极片绝缘层表面扫描电镜图。
图7为实施例2热压后的极片绝缘层横截面扫描电镜图。
图8为低含量高分子聚合物颗粒的绝缘层表面扫描电镜图。
图9为高含量高分子聚合物颗粒的绝缘层表面扫描电镜图。
具体实施方式
为使本发明的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本发明进一步详细说明。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他技术方案，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
电极极片(下文简称极片)表面的绝缘涂层通常包括绝缘物质和粘结剂，但由于绝缘涂层中的粘结剂只起到粘结绝缘物质的作用，并不能直接与隔离膜发生粘结，隔离膜与极片表面绝缘涂层的粘结只能依靠隔离膜自身的粘结剂，而极片与隔离膜之间的高粘结效果对于提高电化学装置的抗变形能力以及硬度具有直接的改善作用。基于上述问题，本申请提供一种电极极片、电化学装置和电子装置，以提高电化学装置的稳定性能和安全性能。
本申请第一方面提供了一种电极极片，包括集流体、活性材料层以及绝缘层，其中， 所述活性材料层设置于所述集流体与所述绝缘层之间；所述绝缘层包括绝缘无机物、粘结剂和高分子聚合物。其中，高分子聚合物包括高分子聚合物颗粒，在所述绝缘层表面任意45μm×27μm区域内裸露的所述高分子聚合物颗粒的数量为2个至60个。本申请发明人发现，若绝缘层单位面积上裸露的高分子聚合物颗粒过少则影响极片与隔离膜之间的粘结效果；若裸露的高分子聚合物颗粒过多则会使得极片表面绝缘层与隔离膜的粘结位点过多，在极片热压后会形成覆盖面积过大，导致覆盖处锂离子的传输通道被堵塞，从而使得锂离子传输无法进行或者阻力过大，影响电化学装置的动力学性能。因此，通过调控绝缘层单位面积上裸露的高分子聚合物颗粒的数量在上述范围内，能够提升极片与隔离膜之间的粘结效果，从而提高电化学装置的稳定性能和安全性能。
在本申请的一些实施方式中，所述高分子聚合物的颗粒粒径Dv50为1μm至20μm，所述高分子聚合物的颗粒粒径Dv50与绝缘层厚度dμm的比值为k 1＝Dv50/d，满足1≤k 1≤3。通过调控k 1在上述范围内，能够显著提升极片与隔离膜之间的粘结效果，以及增强电化学装置的抗变形能力，从而有利于同时提高电化学装置的稳定性能和安全性能。本申请中，Dv50是指在体积基准的粒度分布中，从小粒径侧起、达到体积累积50％的粒径(可采用使用激光粒径测试仪测量)。
在本申请的一些实施方式中，所述高分子聚合物颗粒中包含直径D的颗粒，所述直径D与所述绝缘层厚度dμm的比值为k 2＝D/d，满足1<k 2≤3。通过调控k 2在上述范围内，可以显著提升电极极片与隔离膜之间的粘结效果，增强电化学装置的抗变形能力，从而有利于提高电化学装置的稳定性能和安全性能。
可以理解的是，高分子聚合物颗粒的Dv50是一个统计值，这些高分子聚合物颗粒中，有的颗粒的直径大于Dv50，有的颗粒的直径小于Dv50。基于此，本申请的高分子聚合物颗粒中包含直径D的颗粒，该直径D的颗粒是指：高分子聚合物颗粒中1<k 2≤3的那些颗粒，其中k 2是直径D与绝缘层厚度dμm的比值。例如，当高分子聚合物颗粒的Dv50为6μm、绝缘层厚度为4μm时，高分子聚合物颗粒中直径D的颗粒可包括直径大于4μm且小于等于12μm的颗粒；当高分子聚合物颗粒的Dv50为6μm、绝缘层厚度为2μm时，高分子聚合物颗粒中直径D的颗粒可包括直径大于2μm且小于等于6μm的颗粒。
本申请发明人研究发现，在电极极片的绝缘层中添加一种或多种高分子聚合物后，由于高分子聚合物具有较大的颗粒尺寸，如图1、图2所示，高分子聚合物以单个颗粒或者团簇的高聚物形式在绝缘层的表面裸露出来。裸露在绝缘层表面的高分子聚合物颗粒会与 隔离膜表面的粘结层粒子进行粘结，这种粘结层粒子通常也为高分子聚合物，而这种隔离膜粘结剂层中的粒子可以与极片绝缘层中的高分子聚合物之间表现出很强的融合粘结作用，进而提升极片与隔离膜之间的界面粘结力。另一方面，由于高分子聚合物颗粒在绝缘层中是贯穿性存在，从而对绝缘层自身内聚力也有显著的提升。因此，如图3所示，极片绝缘层中含高分子聚合物颗粒的设计，可以显著提升绝缘层与隔离膜之间的界面粘结力以及绝缘层无机粒子自身的内聚力，提升电化学装置整体的抗变形能力，从而有利于提高电化学装置的稳定性能和安全性能。
图2在样品的扫描电子显微镜(SEM)测试中采用了氩离子切割技术，也称离子研磨截面抛光技术，针对样品表面进行抛光，去除损伤层，从而得到高质量样品。
而常规的极片由于无高分子聚合物颗粒，如图4、图5所示裸露在极片绝缘层表面，极片绝缘层表面呈现有部分气孔且略带粗糙的平整表面，无显著的突出点，仅有隔离膜表面的粘结层粒子与极片绝缘层中的无机粒子进行粘结。由于极片绝缘层中的无机粒子通常具有一定的规则形状，使得隔离膜表面的粘结层粒子与绝缘层进行粘结的效果并不好，从而使得极片与隔离膜之间的粘结效果有限。
本申请中，绝缘层中包含高分子聚合物颗粒的电极极片，在制备锂离子电池过程中的热压工序后，如图6、图7所示，在电极极片表面仍可以观察到突出点状物，表明高分子聚合物颗粒在实际锂离子电池中是可以在极片与隔离膜之间起粘结作用的。当需要调整电极极片绝缘层与隔离膜之间的粘结效果时，可以调控绝缘层单位面积上裸露的高分子聚合物颗粒的数量，从而提高电化学装置的稳定性能和安全性能，如图8、图9所示。
在本申请的一些实施方式中，在绝缘层表面上裸露的所述高分子聚合物颗粒中单个颗粒的裸露面积为20μm 2至315μm 2。当单个高分子聚合物颗粒的裸露面积过小时则会影响极片界面之间的粘结效果；若单个高分子聚合物颗粒的裸露面积过大，虽然对于极片与隔离膜之间的粘结效果有明显提升，但会使极片表面的局部位置孔隙堵塞严重，造成极片的孔隙率下降，降低电化学装置的动力学性能。因此，使单个高分子聚合物颗粒的裸露面积在上述范围内，能够提升极片界面的粘结效果，从而提高电化学装置的稳定性能和安全性能。
本申请对绝缘无机物没有特别限制，只要能实现本申请的目的即可。在本申请的一些实施方式中，所述绝缘无机物包括三氧化二铝、二氧化钛、氧化镁、氧化锆或氧化锌中的至少一种。
本申请对高分子聚合物没有特别限制，只要能实现本申请的目的即可。在本申请的一 些实施方式中，所述高分子聚合物包括聚偏氟乙烯、聚乙烯或聚丙烯中的至少一种。
本申请对绝缘层中的粘结剂没有特别限制，只要能实现本申请的目的即可。在本申请的一些实施方式中，所述粘结剂包括聚丙烯酸盐、聚丙烯酸、聚丙烯酸酯、聚甲基丙烯酸甲酯、聚丙烯腈、聚酰胺或羧甲基纤维素钠中的至少一种。
本申请对电极极片种类没有特别限制，只要能实现本申请的目的即可。在本申请的一些实施方式中，所述电极极片为正极极片或负极极片中的至少一种。
在本申请中，正极极片通常包括正极集流体，本申请对正极集流体没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为8μm至12μm。在本申请中，正极活性材料层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
本申请中，正极的活性材料层包含正极活性材料，本申请对正极活性材料的种类没有特别限制，只要能够实现本申请目的即可，例如，正极活性材料可以包含镍钴锰酸锂(811、622、523、111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂、锰酸锂、磷酸锰铁锂或钛酸锂等中的至少一种。在本申请中，正极活性材料还可以包含非金属元素，例如非金属元素包括氟、磷、硼、氯、硅、硫等中的至少一种，这些元素能进一步提高正极材料的稳定性。
在本申请中，正极活性材料层中还可以包括正极粘结剂，本申请对正极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于含氟树脂、聚丙烯树脂、纤维型粘结剂、橡胶型粘结剂或聚酰亚胺型粘结剂中的至少一种。
在本申请中，正极活性材料层中还可以包括正极导电剂，本申请对正极导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、乙炔黑、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种，优选地，正极导电剂包括导电炭黑和碳纳米管。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不 限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
本申请对正极活性材料、正极粘结剂、正极导电剂的含量没有特别限制，可以采用本领域的常规含量，只要能实现本申请的目的即可。例如，基于正极材料层的质量，正极活性材料的质量百分含量为90％至98％，正极粘结剂的质量百分含量为0.5％至5％，正极导电剂的质量百分含量为0.5％至5％。
任选地，正极极片还可以包括导电层，导电层位于正极集流体和正极活性材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，例如可以包括但不限于上述正极导电剂和上述正极粘结剂。
在本申请中，负极极片通常包括负极集流体，本申请对负极集流体没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。在本申请中，对负极的集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为4μm至12μm。在本申请中，负极活性材料层可以设置于负极集流体厚度方向上的一个表面上，也可以设置于负极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
本申请中，负极活性材料层包括负极活性材料，其中，负极活性材料没有特别限制，只要能实现本申请的目的即可，例如负极活性材料包括可逆地嵌入/脱嵌锂离子的碳材料。碳材料可以是本领域已知的用作负极活性材料的碳材料，例如，碳材料可以包括但不限于结晶碳和/或非晶碳。上述结晶碳可以包括但不限于无定形的、片形的、小片形的、球形的或纤维状的天然石墨或人造石墨。上述非晶碳可以包括但不限于软碳、硬碳、中间相沥青碳化物或煅烧焦中的至少一种。示例性地，负极活性材料可以包括但不限于天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、氧化硅(SiO x，x为1或2)或硅-碳复合物中的至少一种。其中，硅-碳复合物中硅与碳的质量比为1:10至10:1、Dv50为0.1μm至100μm。
在本申请中，负极活性材料层中还可以包括负极导电剂，本申请对负极导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于基于碳的材料、基于金属的材料或导电聚合物中的至少一种。上述基于碳的材料选自天然石墨、人造石墨、导电碳黑、乙炔黑、科琴黑或碳纤维中的至少一种。上述基于金属的材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。导电聚 合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
在本申请中，负极活性材料层中还可以包括负极粘结剂，本申请对负极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、聚丙烯酸、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙中的至少一种。
任选地，负极极片还可以包括导电层，导电层位于负极集流体和负极活性材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，导电层可以包括但不限于上述导电剂和上述粘结剂。
本申请第二方面提供了一种电化学装置，其包含隔离膜，以及所述的电极极片。本申请提供的电极极片具有良好的界面粘结效果，从而有利于同时提高电化学装置的稳定性能和安全性能。
本申请对隔离膜没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯(PE)、聚丙烯(PP)、聚四氟乙烯为主的聚烯烃(PO)类隔离膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜中的至少一种，优选为聚乙烯或聚丙烯，它们对防止短路具有良好的作用，并可以通过关断效应改善电化学装置的稳定性。本申请的隔离膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔离膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm。
在本申请的一些实施方式中，所述隔离膜的基材与所述高分子聚合物具有相同的材质，其中，所述隔离膜与所述绝缘层接触的表面上无粘结剂层。
在本申请的一些实施方式中，所述隔离膜的基材与所述高分子聚合物具有不同的材质，其中，所述隔离膜与所述绝缘层接触的表面上有粘结剂层。
本申请对隔离膜粘结剂层中的粘结剂没有特别限制，只要能实现本申请的目的即可。在本申请的一些实施方式中，所述粘结剂层中的粘结剂包括聚偏氟乙烯、聚丙烯酸盐、聚丙烯酸、聚甲基丙烯酸甲酯、聚丙烯腈、聚酰胺、聚酰亚胺、芳纶、聚丙烯酸酯、丁苯橡胶、聚丙烯酰胺或聚烯烃中的至少一种。
在本申请中，电化学装置还可以包括电解质，电解质可以包括但不限于凝胶电解质、 固态电解质和电解液中的一种或多种。其中，电解液可以包括锂盐和非水溶剂。
本申请对锂盐没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于锂盐可以选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、Li 2SiF 6、LiBOB或者二氟硼酸锂中的至少一种。优选地，锂盐包括LiPF 6。
本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。上述环状碳酸酯可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施方案中，电化学装置可以包括但不限于：一次电池、二次电池、燃料电池、太阳能电池或电容等。优选地，电化学装置为锂二次电池，二次电池可以包括但不限于锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池等。更优选地，电化学装置为锂离子电池。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔离膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入 包装袋并封口，得到电化学装置；或者，将正极极片、隔离膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装袋内，将电解液注入包装袋并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止电化学装置内部的压力上升、过充放电。
本申请第三方面提供了一种电子装置，包含本申请任一实施方案中所述的电化学装置。本申请提供的电化学装置具有良好的稳定性能和安全性能，从而本申请提供的电子装置具有较好的稳定性能和安全性能。
申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、动力工具、无人机、手持吸尘器、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
实施例1
<正极极片的制备>
将正极活性材料钴酸锂、导电剂乙炔黑、粘结剂聚偏二氟乙烯按照质量比为98:0.8:1.2进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌均匀，获得正极浆料，其中正极浆料的固含量为70wt％。将正极浆料均匀涂覆于厚度为12μm的正极集流体铝箔的一个表面上，将铝箔在85℃下烘干处理，得到单面涂覆有正极材料层的正极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极材料层的正极极片。然后经过冷压、裁片、分切后，在85℃的真空条件下干燥12h，得到尺寸规格为72×850mm、厚度规格为0.097mm的干燥的正极极片。
<负极极片的制备>
1)将负极活性材料人造石墨、粘结剂丁苯橡胶、增稠剂羧甲基纤维素钠按照质量比为98:1:1进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料，其中负极浆料的 固含量为75wt％。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，将铜箔在85℃下烘干，得到单面涂覆有负极材料层的负极极片。在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极材料层的负极极片。
2)将绝缘无机物三氧化二铝、粘结剂丙烯酸、高聚物PP颗粒按照质量比为95:3:2进行混合，加入去离子水，在真空搅拌机作用下获得固含量为17wt％的绝缘层浆料，其中所使用的高聚物PP颗粒的Dv50为1μm。将绝缘层浆料均匀涂覆在1)中制得的负极极片表面上，在85℃下烘干，其中绝缘层厚度为0.67μm，然后将涂覆绝缘层的负极极片经过冷压、裁片、分切后，在85℃的真空条件下干燥12h，得到尺寸规格为74mm×867mm、厚度规格为0.113mm的含绝缘层的复合负极极片。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯按照质量比为1:1:1混合得到有机溶剂，然后向有机溶剂中加入锂盐LiPF 6溶解并混合均匀，得到电解液。其中，LiPF 6在电解液中的浓度为1mol/L。
<隔离膜的制备>
采用厚度为7μm的多孔聚乙烯薄膜(Celgard公司提供)，孔径为0.1μm，其中隔离膜表面有聚丙烯酸酯，粘结剂层的涂布质量为10±2mg/5000mm 2，厚度为3±1μm。
<锂离子电池的制备>
将上述制备得到的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间以起到隔离的作用，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。其中，化成上限电压为4.45V，化成温度为80℃，化成静置时间为2h。
实施例2至实施例9
除了如表1所示调整相关制备参数以外，其余与实施例1相同。
实施例10
除了<正极极片的制备>、<负极极片的制备>与实施例1不同以外，其余与实施例1相同。
<正极极片的制备>
1)将正极活性材料钴酸锂、导电剂乙炔黑、粘结剂聚偏氟乙烯按照质量比为98:0.8:1.2进行混合，加入NMP，在真空搅拌机作用下搅拌均匀，获得正极浆料，其中正极浆料的固 含量为70wt％。将正极浆料均匀涂覆于厚度为12μm的正极集流体铝箔的一个表面上，将铝箔在85℃下烘干，得到单面涂覆有正极材料层的正极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极材料层的正极极片。
2)将绝缘无机物三氧化二铝、粘结剂丙烯酸、高聚物PP颗粒按照质量比为95:3:2进行混合，加入去离子水，在真空搅拌机作用下获得固含量为17wt％的绝缘层浆料，其中所使用的高聚物PP颗粒的Dv50为10μm。将绝缘层浆料均匀涂覆在在1)中制得的正极极片表面上，在85℃下烘干，其中绝缘层厚度为10μm，然后将涂覆绝缘层的正极极片经过冷压、裁片、分切后，在85℃的真空条件下干燥12h，得到规格为72mm×850mm的含绝缘层的复合正极极片。
<负极极片的制备>
1)将负极活性材料人造石墨、粘结剂丁苯橡胶、增稠剂羧甲基纤维素钠按照质量比为98:1:1进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料，其中负极浆料的固含量为75wt％。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，将铜箔在85℃下烘干，得到单面涂覆有负极材料层的负极极片。在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极材料层的负极极片。
然后将负极极片经过冷压、裁片、分切后，在85℃的真空条件下干燥12h，得到尺寸规格为74mm×867mm、厚度规格为0.113mm负极极片。
实施例11
除了如表1所示进行调整相关制备参数以外，其余与实施例10相同。
实施例12
除了<隔离膜的制备>、以及如表1所示调整相关制备参数以外，其余与实施例1相同。
采用厚度为7μm的多孔聚丙烯薄膜，孔径为0.1μm。
实施例13
除了如表1所示调整相关制备参数以外，其余与实施例12相同。
对比例1
除了<绝缘层浆料的制备>与实施例1不同以外，其余与实施例1相同。
2)将绝缘无机物三氧化二铝、粘结剂丙烯酸按照质量比为97:3进行混合，未添加高聚物颗粒，然后加入去离子水，在真空搅拌机作用下获得固含量为17wt％的绝缘层浆料。将绝缘层浆料均匀涂覆在前述制得的负极极片表面上，在85℃下烘干，其中绝缘层厚度为 5μm，然后将涂覆绝缘层的负极极片经过冷压、裁片、分切后，在85℃的真空条件下干燥12h，得到尺寸规格为74mm×867mm、厚度规格为0.113mm的含绝缘层的复合负极极片。
对比例2至对比例7
除了如表1所示调整相关制备参数以外，其余与实施例1相同。
测试方法和设备：
高分子聚合物颗粒直径D的测试方法：
将待测目标极片使用离子束进行垂直冲击，获取新鲜截面，使用扫描电子显微镜(SEM)拍摄截面的影像。测量截面绝缘层中的高分子聚合物颗粒等效最大圆的直径，高分子聚合物颗粒的直径D等于等效最大圆的直径。
绝缘层厚度d的测试方法：
将待测目标极片使用离子束进行垂直冲击，获取新鲜截面，使用SEM拍摄截面的影像。截面的长度≥1mm(例如1mm)，等距离拍摄20张SEM照片，放大倍数≥1000倍(例如1000倍)，在每张照片中选取平整度均匀的地方作为测量点，测量绝缘层的厚度，统计所有的测量点数据，得出中值厚度数据，则绝缘层的厚度d等于中值厚度。
绝缘层表面45μm×27μm面积内裸露的高分子聚合物颗粒的数量测试方法：
(1)从锂离子电池中取出待测目标极片，并裁切成多个4×4mm的样品(例如5个)；
(2)使用SEM观察样品表面，将影像放大至能清晰观察到样品表面裸露的高分子聚合物颗粒时，视野中选取任意10个45μm×27μm的观察区域，并获取10个观察区域相应的影像，记录观察区域影像的面积及10个观察区域中高分子聚合物颗粒最大长度处于1μm至20μm之间的颗粒数量；
(3)选取3个4×4mm样品，重复步骤(2)，统计所有样品观察区域中的高分子聚合物颗粒最大长度处于1μm至20μm之间的颗粒数量，得出中值数量数据，中值数量即为45μm×27μm观察区域内高分子聚合物颗粒的数量。
粘结强度测试：
将实施例和对比例中制备的锂离子电池以0.1C倍率(C)放电至其工作电压下限，再从实施例1至实施例7、实施例10至实施例11、对比例2至对比例7制备的锂离子电池中取出负极极片与隔离膜的复合体，然后将负极极片与隔离膜的复合体铺展自然风干1小时(h)后，用刀片取宽30mm、长150mm的测试试样；从实施例8至实施例9制备的锂离子电池中取出正极极片与隔离膜的复合体，然后将正极极片与隔离膜的复合体铺展自然风干1h后， 用刀片取宽30mm、长150mm的测试试样。将测试样固定到高铁拉力机的测试夹具上进行粘结强度测试(剥离角度90度，拉伸速度50mm/min，拉伸位移60mm)。当剥离界面为绝缘层和隔离膜层时，则所测结果为绝缘层与隔离膜之间的粘结强度。
极片孔隙率测试：
将实施例和对比例中制备的锂离子电池以0.1C倍率放电至其工作电压下限，再从实施例1至实施例7、实施例10至实施例11、对比例2至对比例7制备的锂离子电池中单独取出负极极片，然后将负极极片浸泡在纯DMC溶剂中进行清洗1h，重复浸泡三次，在将负极极片铺展自然风干4h后，将风干后的负极极片冲成直径大小为10mm的圆片，数量大于40片，且圆片表面平整无缺口；从实施例8至实施例9制备的锂离子电池中单独取出正极极片，然后将正极极片浸泡在纯DMC溶剂中进行清洗1h，重复浸泡三次，在将正极极片铺展自然风干4h后，将风干后的正极极片冲成直径大小为10mm的圆片，数量大于40片，且圆片表面平整无缺口。用真密度测试仪获得样品极片的真实体积V2，表观体积V1＝S×H(S为样品表面积，H为样品厚度)，计算孔隙率＝(V1-V2)/V1×100％。
本测试方法中，孔隙率定义为样品的孔体积与样品总体积的比值，反映了样品中孔隙的数量多少，这对于锂离子电池中的离子传输起到关键的影响，真实体积定义为样品不含孔的体积。
锂离子电池析锂测试：
将实施例和对比例中制备的锂离子电池静置在25℃的恒温箱中，保温1h后，以1C的充电倍率恒流充电至4.45V后，在4.45V下恒压充电至0.02C后，静置3min，再以1C的放电倍率恒流放电至3V后，静置3min，然后以这样的流程循环10次，循环结束后，锂离子电池再满充至4.45V后，然后拆解锂离子电池观察其负极极片表面是否有析锂现象。
面积测试：
将实施例和对比例中制备的锂离子电池以0.1C倍率放电至其工作电压下限，再从实施例1至实施例7、实施例10至实施例11、对比例2至对比例7制备的锂离子电池中单独取出负极极片，然后将负极极片浸泡在纯DMC溶剂中进行清洗1h，重复浸泡三次，然后将极负极极片铺展自然风干4h后，将风干后的负极极片裁成4mm×4mm的小片；从实施例8至实施例9制备的锂离子电池中单独取出正极极片，然后将正极极片浸泡在纯DMC溶剂中进行清洗1h，重复浸泡三次，然后将正极极片铺展自然风干4h后，将风干后的正极极片裁成4mm×4mm的小片。用SEM对测试样品进行观察。
通过观察SEM视野，以垂直于极片样品表面方向，观察到绝缘层表面裸露的高聚物颗粒或者团簇的高聚物的裸露表面，以垂直方向的投影面中，两点连线最大距离为为高聚物颗粒或团簇的高聚物裸露表面的等效圆直径D，根据圆面积S＝π×(D/2) 2，计算出单个高聚物颗粒或者团簇的高聚物裸露表面的裸露面积。
Figure PCTCN2022072533-appb-000001
Figure PCTCN2022072533-appb-000002
从实施例1至实施例13、对比例1可以看出，当极片表面的绝缘层加入高聚物颗粒后，能够显著增强极片与隔离膜之间的粘结强度，使极片与隔离膜之间的粘结效果得到提升，增强电化学装置的抗变形能力，从而有利于同时提高电化学装置的稳定性能和安全性能。
从实施例1至实施例3、对比例2至对比例3可以看出，当绝缘层中所添加的高聚物颗粒粒径Dv50过小时(例如对比例2)，会导致极片与隔离膜之间的粘结强度下降，导致极片界面之间的粘结效果不明显，而不利于提升电化学装置的稳定性；当绝缘层中所添加的高聚物颗粒粒径Dv50过大时(例如对比例3)，会导致极片的孔隙率下降，使得锂离子电池出现析锂现象，这具有一定的安全隐患，从而不利于提升电化学装置的安全性。
从实施例2、实施例4至实施例5、对比例4至对比例5可以看出，当k 1过小时，单个高聚物颗粒有较多的体积埋藏在绝缘层表面以下，从而使得电机极片与隔离膜之间的粘结强度较低，导致极片界面之间的粘结效果不明显，从而不利于提升电化学装置的稳定性；当k 1过大时，单个高聚物颗粒有较多的体积暴露在绝缘层表面以上，但由于高聚物颗粒在绝缘层表面暴露过多体积，在经过制作锂离子电池的热压过程后，会造成极片表面局部孔隙被堵塞，从而造成极片的孔隙率下降，使得锂离子电池出现析锂现象，这具有一定的安全隐患，从而不利于提升电化学装置的安全性。
从实施例5至实施例9、对比例6至对比例7可以看出，当绝缘层单位面积上裸露的高聚物颗粒数量过少时，则极片与隔离膜之间的粘结强度较低，导致极片界面之间的粘结效果不明显，从而不利于提升电化学装置的稳定性；当绝缘层单位面积上裸露的高聚物颗粒数量过多时，虽然极片与隔离膜之间的粘结强度可以得到大幅度提升，但是由于裸露在绝缘层表面的高聚物颗粒过多，则导致极片孔隙率下降、影响锂离子电池的动力学性能，从而使得锂离子电池出现析锂现象，这具有一定的安全隐患，从而不利于提升电化学装置的安全性。
从实施例3与实施例11、实施例4与实施例10可以看出，将相同设计的绝缘层涂覆在正极极片或负极极片上，对绝缘层与隔离膜之间的粘结强度并无显著影响，这是由于当绝缘层的设计使用在正极极片或者负极极片上，但并未改变隔离膜与绝缘层之间的接触面，因此极片与隔离膜之间的粘结效果仍可以由高聚物颗粒的加入而获得改善。
从实施例6与实施例12、实施例9与实施例13可以看出，当隔离膜基材与绝缘层中高聚物的材质相同时，虽然在隔离膜表面上未涂覆粘结剂层，但极片与隔离膜之间的粘结效果并没有恶化，从而可以简化隔离膜设计，其因是由于当隔离膜基材与绝缘层中高聚物 的材质相同时，利用相似相容原理，在锂离子电池制作的热压过程中，两者能够产生较好的粘结效果，从而可以改善电化学装置的稳定性。
从实施例1至实施例13可以看出，当缘层中所添加的高聚物颗粒粒径Dv50、k 1、绝缘层单位面积上裸露的高聚物颗粒数量都在本申请的范围内时，得到的电化学装置同时具有良好的稳定性和安全性。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (10)

  1. 一种电极极片，包括集流体、活性材料层以及绝缘层，其中，所述活性材料层设置于所述集流体与所述绝缘层之间；
    所述绝缘层包括绝缘无机物、粘结剂和高分子聚合物，其中，所述的高分子聚合物包括高分子聚合物颗粒，在所述绝缘层表面任意45μm×27μm区域内裸露的所述高分子聚合物颗粒的数量为2个至60个。
  2. 根据权利要求1所述的电极极片，其中，所述高分子聚合物颗粒的Dv50为1μm至20μm，所述高分子聚合物颗粒Dv50与所述绝缘层厚度dμm的比值为k 1＝Dv50/d，满足1≤k 1≤3。
  3. 根据权利要求1所述的电极极片，其中，所述高分子聚合物颗粒中包含直径D的颗粒，所述直径D与所述绝缘层厚度dμm的比值为k 2＝D/d，满足1<k 2≤3。
  4. 根据权利要求1所述的电极极片，其中，在所述绝缘层表面上裸露的所述高分子聚合物颗粒中单个颗粒的裸露面积为20μm 2至315μm 2。
  5. 根据权利要求1所述的电极极片，其中，所述绝缘无机物包括三氧化二铝、二氧化钛、氧化镁、氧化锆或氧化锌中的至少一种。
  6. 根据权利要求1所述的电极极片，其中，所述高分子聚合物包括聚偏氟乙烯、聚乙烯或聚丙烯中的至少一种。
  7. 根据权利要求1所述的电极极片，其中，所述电极极片为正极极片或负极极片中的至少一种。
  8. 一种电化学装置，包含隔离膜，以及权利要求1-7中任一项所述的电极极片；
    当所述隔离膜的基材与所述高分子聚合物具有相同的材质，其中，所述隔离膜与所述绝缘层接触的表面上无粘结剂层；
    当所述隔离膜的基材与所述高分子聚合物具有不同的材质，其中，所述隔离膜与所述绝缘层接触的表面上有粘结剂层。
  9. 根据权利要求8所述的电化学装置，所述粘结剂层中的粘结剂包括聚偏氟乙烯、聚丙烯酸盐、聚丙烯酸、聚甲基丙烯酸甲酯、聚丙烯腈、聚酰胺、聚酰亚胺、芳纶、聚丙烯酸酯、丁苯橡胶、聚丙烯酰胺或聚烯烃中的至少一种。
  10. 一种电子装置，其包含权利要求8-9任一项所述的电化学装置。
PCT/CN2022/072533 2022-01-18 2022-01-18 一种电极极片、电化学装置和电子装置 Ceased WO2023137586A1 (zh)

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