WO2022120651A1 - 一种卷绕式电极组件、电化学装置及电子装置 - Google Patents

一种卷绕式电极组件、电化学装置及电子装置 Download PDF

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Publication number
WO2022120651A1
WO2022120651A1 PCT/CN2020/134992 CN2020134992W WO2022120651A1 WO 2022120651 A1 WO2022120651 A1 WO 2022120651A1 CN 2020134992 W CN2020134992 W CN 2020134992W WO 2022120651 A1 WO2022120651 A1 WO 2022120651A1
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region
electrode assembly
isolation layer
lithium
wound electrode
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PCT/CN2020/134992
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English (en)
French (fr)
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魏红梅
张益博
翁秋燕
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宁德新能源科技有限公司
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Priority to CN202080014002.XA priority Critical patent/CN114916246A/zh
Priority to PCT/CN2020/134992 priority patent/WO2022120651A1/zh
Publication of WO2022120651A1 publication Critical patent/WO2022120651A1/zh
Priority to US18/331,405 priority patent/US20230352744A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • 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
    • 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
    • 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
    • H01M50/44—Fibrous 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
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the field of electrochemistry, in particular to a wound electrode assembly, an electrochemical device and an electronic device.
  • Lithium-ion batteries have the characteristics of large specific energy, high operating voltage, low self-discharge rate, small size and light weight, and are widely used in various fields such as electrical energy storage, portable electronic devices and electric vehicles. With the rapid development of electric vehicles and mobile electronic devices, people have higher and higher performance requirements for lithium-ion batteries, for example, lithium-ion batteries are required to have higher energy density, safety, and cycle performance.
  • the separator of the existing lithium ion battery usually exists in the electrode assembly in an integral structure, and mainly plays the role of isolating the positive electrode and the negative electrode, as well as ensuring ion conduction and isolating electronic conduction.
  • An adhesive layer with consistent viscosity is usually provided between the separator and the electrode sheet to improve the bonding force between the separator and the electrode sheet.
  • the internal forces in different regions are different, and stress concentration is likely to occur inside the lithium-ion battery in some regions, reducing the safety of the lithium-ion battery. Therefore, a new lithium-ion battery is urgently needed to improve the safety of the lithium-ion battery.
  • the purpose of the present application is to provide a wound electrode assembly, an electrochemical device and an electronic device, so as to improve the safety of the electrochemical device.
  • the present application is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery.
  • a first aspect of the present application provides a wound electrode assembly, which includes an electrode pole piece and a separator on at least one surface of the electrode pole piece, the wound electrode assembly has a first region and a second region, The bonding force between the separator and the surface of the electrode pads in the first region of the wound electrode assembly is greater than the bonding between the separator and the surface of the electrode pads in the second region of the wound electrode assembly force, and the second area is the rewinding area of the wound electrode assembly.
  • the wound electrode assembly of the present application has a first area and a second area, wherein the second area corresponds to the rewinding area of the electrode sheet in the wound electrode assembly, and the first area is the winding area
  • the adhesive force between the separator and the surface of the electrode sheet in the first area of the wound electrode assembly is greater than that in the second area of the wound electrode assembly.
  • the junction force makes the bonding force between the isolation layer and the surface of the electrode pole piece in the first area of the wound electrode assembly higher, and when the electrode pole piece in the second area is stressed, the layers can interact with each other.
  • the adhesive force F 1 between the separator in the first region and the surface of the electrode pad is the same as the adhesive force F between the separator in the second region and the surface of the electrode pad
  • the difference between 2 is in the range of 1N/m to 15N/m, preferably in the range of 5N/ m to 10N/m.
  • the lower limit of the difference between the adhesion force F 2 between the isolation layer in the two regions and the surface of the electrode pole piece may be included in the following values: 1N/m, 2N/m, 3N/m, 4N/m or 5N/m
  • the upper limit of the difference between the adhesion force F 1 between the isolation layer in the first area and the surface of the electrode pole piece and the adhesion force F 2 between the isolation layer in the second area and the surface of the electrode pole piece can include Of the following values: 6N/m, 8N/m, 10N/m, 12N/m or 15N/m.
  • the adhesive force F 1 between the separator and the surface of the electrode pole piece in the first region may be 1 N/m to 30 N/m, preferably 10 N/m to 20 N/m. It can be understood that when the adhesion force F1 between the isolation layer and the surface of the electrode pole piece in the first region increases, the adhesion force F2 between the isolation layer and the surface of the electrode pole piece in the second region can increase accordingly. As long as the adhesive force F 1 between the isolation layer and the surface of the electrode pole piece in the first area is larger than the adhesive force F 2 in the second area.
  • the adhesion force F 1 between the isolation layer and the surface of the electrode pole piece in the first area is greater than the adhesion force F 2 between the isolation layer and the surface of the electrode pole piece in the second area, so as to avoid the electrode pole piece in the second area. Deformation due to stress concentration.
  • the adhesive force F 2 between the separator and the surface of the electrode pad in the second region may be 2N/m to 15N/m, as long as the separator and the electrode pad in the second region are
  • the adhesive force F 2 between the sheet surfaces may be smaller than the adhesive force F 1 in the first area, so as to avoid the deformation of the electrode pole pieces in the second area due to stress concentration.
  • the wound electrode assembly includes a flat area and a rolled back area, and the adhesive force between the separator and the surface of the electrode sheet in the straight area is greater than that of the separator in the rolled back area Adhesion to the surface of the electrode pads.
  • the above-mentioned straight area may refer to the area where the electrode pole piece is straight in the wound electrode assembly
  • the above-mentioned rewinding area may refer to the area in which the electrode pole piece is rolled back in the wound electrode assembly.
  • Stress concentration is more likely to occur in the reeling area of the module, because the electrode pole pieces in the reeling area are in a bent state and are more compressed.
  • Ordinary lithium-ion batteries have a deformation rate of about 6% to 7% after 300 cycles, while the current lithium-ion batteries with high-viscosity separators have a deformation rate even higher than 10% after 300 cycles.
  • the adhesive force between the separator and the surface of the electrode sheet in the straight area of the present application can be set to be greater than the adhesive force between the separator and the surface of the electrode sheet in the rolled-back area, so that the rolled back The adhesion between the spacer layer and the surface of the electrode pads in the region is relatively lower.
  • the layers in the reeling area can produce slight slippage between each other, thereby releasing the stress and avoiding the electrode pole pieces in the reeling area due to stress concentration. deformation, thereby improving the safety of lithium-ion batteries.
  • the first region may specifically refer to the flat region of the wound electrode assembly
  • the second region may specifically refer to the rolled-back region of the wound electrode assembly.
  • the isolation layer and the The adhesive force between the surfaces of the electrode pads may be 1 N/m to 30 N/m, preferably 10 N/m to 20 N/m.
  • the adhesive force between the isolation layer in the flat area and the surface of the electrode pole piece increases, the adhesive force between the isolation layer in the rolled-back area and the surface of the electrode pole piece can be increased accordingly, as long as the flat area is It is sufficient that the adhesive force between the separator and the surface of the electrode pole piece is greater than the adhesive force of the rewinding area.
  • the electrode assembly of the present application is a wound structure, which includes second regions located on the left and right sides of the rolled electrode assembly, respectively, and a first region located in the middle of the rolled electrode assembly .
  • the thickness of the wound electrode assembly is expressed as L, then the second area may refer to the area included in the length of 1/2L from the outermost edge of the wound electrode assembly on both sides of the wound electrode assembly when the wound electrode assembly is laid flat,
  • the first area is an area other than the above-mentioned second area in the wound electrode assembly. It can be understood that the electrode pads in the second region are curved and rolled up, while the electrode pads in the first region are straight.
  • the first region of the wound electrode assembly may include a first subregion and a second subregion.
  • the first sub-region refers to the region containing the tabs in the first region, that is, the tab region of the wound electrode assembly
  • the second sub-region refers to the region that does not include the tabs in the first region.
  • the tabs have a thickness. Due to the existence of the tabs, the electrode pads in the first sub-region are more prone to stress concentration.
  • the adhesive force F between the isolation layer and the electrode pads in the second sub - region can be greater than
  • the adhesive force F 4 between the isolation layer in the first sub-region and the electrode pole piece prevents the electrode pole piece in the first sub-region from being deformed due to stress concentration, and further improves the safety of the lithium ion battery.
  • the adhesive force F 3 between the isolation layer and the electrode pads in the second sub-region may be 15 N/m to 20 N/m, and the isolation layer and the electrode in the first sub-region
  • the adhesion force F 4 between the pole pieces may be 10 N/m to 15 N/m, so that the adhesion force F 3 between the isolation layer and the electrode pole pieces in the second sub-region is greater than that of the isolation layer in the first sub-region
  • the adhesive force between the electrode and the pole piece is F4 .
  • isolation layers with different adhesive forces between the electrode and the surface of the electrode sheet can be provided in different regions of the electrode sheet, so that the isolation layer in the first region is connected to the surface of the electrode sheet.
  • the adhesive force therebetween is greater than the adhesive force between the separation layer in the second region and the surface of the electrode pole piece.
  • separators with different viscosities of adhesives can be arranged in different regions of the wound electrode assembly to control the adhesive force between the separators and the surface of the electrode sheet, for example, in the first
  • An isolation layer with a low-viscosity adhesive is arranged in the second area, and an isolation layer with a high-viscosity adhesive is arranged in the first area.
  • the adhesive force between the isolation layer in the first area and the surface of the electrode pole piece can be made larger than the adhesion force between the isolation layer in the second area and the surface of the electrode pole piece, so as to avoid the electrode in the second area.
  • the pole pieces are deformed due to stress concentration.
  • the viscosity of the binder in the release layer can be changed by adjusting the content of the binder in the slurry.
  • the high viscosity mentioned in this application may refer to the interfacial adhesion force F: 10N/m ⁇ F ⁇ 20N/m, and the low viscosity may refer to the interfacial adhesion force F: 1N/m ⁇ F ⁇ 10N/m.
  • the adhesive force between the separator and the surface of the electrode sheet can be regulated by increasing the content of the binder in the separator in the region where high adhesive force is required.
  • the binder content in the polymer fibers may range from 5wt% to 25wt%, preferably 8wt% to 17wt%, for example, the lower limit of the binder content in the polymer fiber may be included in the following values: 5wt%, 8wt%, 10wt%, 12wt% or 15wt%.
  • the binder content in the polymer fibers may be 2 wt % to 20 wt %, preferably 6 wt % to 15 wt %, for example, the upper limit of the binder content in the polymer fibers may include Of the following values: 8 wt %, 12 wt %, 15 wt %, 17 wt % or 20 wt %.
  • the content of the binder in the polymer fibers in the first region is higher than the content of the binder in the polymer fibers in the second region, so that the adhesive force between the isolation layer in the first region and the surface of the electrode sheet is improved It is greater than the adhesive force between the isolation layer in the second area and the surface of the electrode pole piece.
  • the fiber diameter of the polymer fibers in the isolation layer is 10 nm to 5 ⁇ m, preferably 20 nm to 2 ⁇ m, for example, the lower limit of the fiber diameter of the polymer fibers may be included in the following values: 20 nm , 50 nm, 100 nm or 500 nm; the upper limit of the fiber diameter of the polymer fiber may be included in the following values: 1000 nm, 1500 nm or 2 ⁇ m.
  • the thickness of the isolation layer is 1 ⁇ m to 50 ⁇ m, preferably 3 ⁇ m to 15 ⁇ m.
  • the isolation layer may also contain inorganic particles, and the volume of the inorganic particles accounts for no more than 40% of the total volume of solid matter in the isolation layer, preferably 15% to 30%, for example, the volume of the inorganic particles accounts for the isolation layer.
  • the lower limit of the total volume of solid matter in the layer may include the following values: 5%, 9%, 18% or 21%
  • the upper limit of the volume of inorganic particles to the total volume of solid matter in the isolation layer may include the following values: 24%, 27%, 35 or 40%.
  • the addition of inorganic particles can improve the strength of the isolation layer.
  • the average particle size of the inorganic particles in the isolation layer is 20 nm to 5 ⁇ m, preferably 50 nm to 2 ⁇ m, for example: the lower limit of the average particle size of the inorganic particles can be included in the following values: 50 nm , 100 nm or 500 nm; the upper limit value of the average particle diameter of the inorganic particles may be included in the following values: 1000 nm, 1500 nm or 2 ⁇ m.
  • the above-mentioned inorganic particles may include a binder to improve the adhesion of the inorganic particles.
  • the binder content in the inorganic particles is 4 wt % to 7 wt %, for example, the binder content in the inorganic particles is 4 wt %, 5 wt %, 6 wt % or 7 wt %.
  • the binder content in the inorganic particles is 3 wt % to 15 wt %, for example, the binder content in the inorganic particles is 3 wt %, 5 wt %, 7 wt %, 10 wt % or 15 wt %. It can be seen from the above that for the second region, the content of the binder in the inorganic particles is higher than that of the first region, so that the isolation layer in the second region can have higher strength. However, inorganic particles only account for no more than 40% of the total volume of solid matter in the isolation layer, indicating a higher proportion of polymer fibers in the isolation layer. It can be seen that the purpose of the invention of the present application can be achieved by adjusting the content of the binder in the polymer fibers in the first region and the second region.
  • the polymer fibers may further include inorganic fillers, and the content of the inorganic fillers in the polymer fibers is 5wt% to 10wt%, for example, the content of the inorganic fillers in the polymer fibers The content is 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%.
  • polymer fibers may include polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyethylene oxide, Polyphenylene ether, polypropylene carbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride-hexafluoropropylene or polyvinylidene fluoride-co-chlorotrifluoroethylene or the above At least one of the fibers of the substance derivative.
  • the application does not have any special restrictions on the inorganic substances of the inorganic particles in the isolation layer, and the application does not have any special restrictions on the inorganic substances of the inorganic fillers in the polymer fibers, as long as the requirements of the application are met.
  • the above-mentioned inorganic substances may include oxidation Hafnium, strontium titanate, tin dioxide, cesium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium oxide, yttrium oxide, aluminum oxide, titanium oxide, silicon dioxide, boehmite, hydroxide
  • binder in this application, as long as it meets the requirements of the application, for example, it may include polyvinyl alcohol, polytetrafluoroethylene, styrene-butadiene rubber, sodium carboxymethyl cellulose, polyphenylene acid, polybutyl acrylate , at least one of polyacrylonitrile, polyurethane or acrylonitrile multipolymer.
  • preparation method of the isolation layer there is no particular limitation on the preparation method of the isolation layer in the present application, and a preparation method known to those skilled in the art can be adopted, for example, the following preparation method can be adopted:
  • Disperse polymers and binders with different contents in an organic solvent and stir evenly until the viscosity of the slurry is stable to obtain slurry A and slurry B with different binder contents, wherein the binder is in the slurry A. is greater than that in slurry B.
  • the content of the binder in the slurry C may be greater than the content of the binder in the slurry D, or the content of the binder in the slurry C and the slurry D is the same.
  • the separation layer is obtained by alternately spraying slurry A and slurry C on the first area of the electrode sheet by electrospinning equipment and electrospray equipment.
  • slurry B and slurry D are alternately sprayed by electrospinning equipment and electrospray equipment to obtain an isolation layer, so that in the obtained isolation layer, the binder in the isolation layer in the first area is The content is greater than the binder content in the release layer in the second region.
  • both the electrospinning equipment and the electrospray equipment are connected with a voltage stabilizer.
  • inorganic fillers such as calcium oxide
  • the inorganic fillers and inorganic particles in the present application can be selected from the same inorganic substances, and can also be selected from different inorganic substances.
  • a separator can be prepared on the surface of the positive electrode, and a separator can also be prepared on the surface of the negative electrode.
  • the separator can also be prepared on the surface of the positive and negative electrodes at the same time, as long as the winding It is only necessary that the adhesive force between the isolation layers in different regions of the type electrode assembly and the surface of the electrode pads is not uniform, and these should all belong to the protection scope of the present application.
  • the above-mentioned isolation layer can be provided on one side of the positive pole piece, or the above-mentioned isolation layer can be set on one side of the negative pole piece, or the above-mentioned isolation layer is provided on both sides of the positive pole piece, or on both sides of the negative pole piece. All are provided with the above-mentioned isolation layer, or one side of the positive pole piece and the one side of the negative pole piece are provided with the above-mentioned isolation layer, as long as the bonding force between the isolation layer and the surface of the electrode pole piece in different regions in the wound electrode assembly is guaranteed Not evenly.
  • a positive electrode sheet in the present application is not particularly limited, as long as the purpose of the present application can be achieved.
  • a positive electrode sheet typically includes a positive electrode current collector and a positive electrode active material layer.
  • the positive electrode current collector is not particularly limited, and can be any positive electrode current collector known in the art, such as aluminum foil, aluminum alloy foil, or composite current collector.
  • the positive electrode active material layer includes a positive electrode active material.
  • the positive electrode active material is not particularly limited, and any positive electrode active material known in the art can be used. At least one of lithium, lithium iron phosphate, lithium-rich manganese-based material, lithium cobaltate, lithium manganate, lithium iron manganese phosphate, or lithium titanate.
  • a negative pole piece in the present application is not particularly limited, as long as the purpose of the present application can be achieved.
  • a negative pole piece usually includes a negative electrode current collector and a negative electrode active material layer.
  • the negative electrode current collector is not particularly limited, and any negative electrode current collector known in the art can be used, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector.
  • the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material is not particularly limited, and any negative electrode active material known in the art can be used.
  • at least one of artificial graphite, natural graphite, mesocarbon microspheres, soft carbon, hard carbon, silicon, silicon carbon, lithium titanate, and the like may be included.
  • the lithium ion battery of the present application further includes an electrolyte, and the electrolyte may be one or more of a gel electrolyte, a solid electrolyte, and an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is 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.
  • LiPF 6 can be chosen as the lithium salt because it can give high ionic conductivity and improve cycle characteristics.
  • the non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or a combination thereof.
  • the above-mentioned carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound, or a combination thereof.
  • Examples of the above-mentioned chain carbonate compound are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), carbonic acid Methyl ethyl ester (MEC) and combinations thereof.
  • Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), and combinations thereof.
  • fluorocarbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethyl carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-dicarbonate Fluoro-1-methylethylene, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Ethyl carbonate 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • 1,2-dicarbonate Fluoro-1-methylethylene 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethyl
  • carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , caprolactone, valerolactone, mevalonolactone, caprolactone, and combinations thereof.
  • ether compounds examples include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl ether Oxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
  • Examples of the above-mentioned other organic solvents are 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, and phosphate esters and combinations thereof.
  • the present application also provides an electrochemical device, comprising an electrode assembly and an electrolyte, the electrode assembly is the wound electrode assembly described in any of the above embodiments, and the electrochemical device has good safety performance.
  • the present application also provides an electronic device comprising the electrochemical device described in the embodiments of the present application, and the electronic device has good safety performance.
  • electronic devices may include, but are not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, assisted bicycles, bicycles, Lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large-scale household storage batteries and lithium-ion capacitors, etc.
  • an electrochemical device can be manufactured by the following process: overlapping the positive electrode and the negative electrode through a separator, and putting them into a case after winding, folding, etc. as required, injecting the electrolyte into the case and sealing, the separator used therein The above-mentioned separator provided in this application.
  • an overcurrent preventing element, a guide plate, etc. may be placed in the case to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the adhesive force between the separator and the surface of the electrode electrode sheet in the first area of the wound electrode assembly is greater than that in the second area of the wound electrode assembly
  • the junction force makes the bonding force between the isolation layer and the surface of the electrode pole piece in the first area of the wound electrode assembly higher, and the electrode pole piece in the second area can produce mutual formation between layers when under stress. Tiny slip, thereby releasing the stress, thus reducing the occurrence of stress concentration caused by the consistent adhesion between the existing separator and the surface of the electrode, and reducing the deformation of lithium-ion batteries caused by stress concentration, Thereby improving the safety of lithium-ion batteries.
  • FIG. 1 is a schematic structural diagram of a lithium ion battery according to an embodiment of the application.
  • FIG. 2 is a schematic structural diagram of a wound electrode assembly in another embodiment of the present application (along the surface direction of the pole piece);
  • FIG. 3 is a schematic structural diagram of an electrode pole piece coated on a single side with an isolation layer in an embodiment of the application;
  • FIG. 4 is a schematic structural diagram of an embodiment of the present application where the separator is disposed on the positive pole piece coated on both sides;
  • FIG. 5 is a schematic structural diagram of an embodiment of the present application where the isolation layer is disposed on the negative pole piece coated on both sides;
  • Fig. 6 is a kind of structural representation of spinning and electrospray equipment in an embodiment of the application.
  • FIG. 7 is a schematic structural diagram of stacking of electrode and pole pieces in the process of testing the adhesion force of the present application.
  • FIG. 1 shows a schematic structural diagram of a wound electrode assembly in an embodiment of the present application.
  • the electrode assembly is a wound structure, which includes second regions located at the left and right ends of the wound electrode assembly and a first region located in the middle of the wound electrode assembly.
  • the wound electrode assembly may include a first sub-region 1 and a second sub-region 2 , and the first sub-region 1 refers to the one shown in FIG. 1 .
  • the first region includes the tab 11
  • the second sub-region refers to the first region shown in FIG. 1 that does not include the tab 11 .
  • FIG. 2 is a schematic structural diagram of a wound electrode assembly in an embodiment of the present application (along the surface direction of the pole piece).
  • the viscosity of the binder is lower than the viscosity of the binder used in the first area, so that the adhesive force between the isolation layer and the surface of the electrode pole piece in the first area is greater than that of the isolation layer and the electrode pole piece in the second area Adhesion between surfaces.
  • the isolation layer of the present application may be disposed on at least one surface of the electrode sheet, for example, it may be a structure in which the isolation layer is provided on one side of the electrode sheet as shown in FIG. 3, or it may be It is the structure in which the positive pole piece shown in Figure 4 is provided with isolation layers on both sides, and it can also be the structure in which the negative pole piece shown in Figure 5 is provided with isolation layers on both sides, specifically for example, the positive pole piece and the negative pole piece in Figure 3
  • One of the surfaces is provided with an isolation layer 30, in FIG. 4, both surfaces of the positive pole piece are provided with an isolation layer 30, and in FIG. 5, both surfaces of the negative pole piece are provided with an isolation layer 30.
  • the positive electrode plate includes a positive electrode current collector 10 and a positive electrode active material layer 20
  • the negative electrode electrode plate includes a negative electrode current collector 50 and a negative electrode active material layer 40 .
  • FIG. 6 is a schematic structural diagram of a spinning and electrospraying device according to an embodiment of the present application.
  • the device includes an electrospinning device 60 , an electrospraying device 70 and a voltage regulator 80 .
  • the capacity of the lithium-ion battery After the capacity of the lithium-ion battery is completed, that is, when the lithium-ion battery is half-charged after the first charge-discharge cycle is completed, measure the thickness of the battery in the first area and the second area (winding area) of the lithium-ion battery. Take 3 points respectively and record the thickness data H 0 ; after the lithium-ion battery has been tested for 300 charge-discharge cycles, it maintains the same state of charge (such as the same voltage) as when the capacity is completed, select the same measurement position, and use the same measurement tool The thickness of the lithium-ion battery is measured, the data H 1 is recorded, and the deformation rate of each measurement position is calculated by the following expression:
  • Measurement position deformation rate (H 1 -H 0 )/H 0 ⁇ 100%
  • the lithium-ion battery was allowed to stand at room temperature for 30 minutes, charged at a constant current rate of 0.05C to a voltage of 4.45V, and then the electrochemical device was discharged to 3.00V at a rate of 0.05C, and the above-mentioned charge/discharge steps were repeated for 3 cycles.
  • After completing the formation of the lithium-ion battery it was charged to a voltage of 4.45V with a constant current and constant voltage at a charging rate of 0.2C, and then the electrochemical device was discharged to 3.00V at a discharge rate of 0.2C, and its discharge energy was recorded, and then its 0.2C discharge time was calculated.
  • the test environment temperature is 25°C, and the same charging process is used for the comparative example and the embodiment: the current in the constant current charging stage is 0.7C until the cut-off voltage is 4.5V, and then the battery is charged with constant voltage until the cut-off current is 0.05C. After being fully charged, let it stand for 5 minutes, and then discharge it to 3.0V with a current of 0.5C. This is a charge-discharge cycle process. After repeating this charge-discharge cycle for 300 times, the discharge capacity after 300 cycles is divided by the first cycle. The discharge capacity is the cycle capacity retention rate.
  • the hot-pressed sandwich structure is taken out from the packaging bag 8 and transferred to the tension machine equipment.
  • the end of the tension clamping plate 5 is fixed on the lower chuck of the tension machine, and is kept perpendicular to the ground.
  • the glued part 7 of the isolation layer 30 It is fixed on the upper chuck of the tensile machine, so that the upper chuck is kept parallel to the surface of the sample, and the upper and lower chucks are clamped with clamps respectively. It is necessary to ensure that the operating console controls the tension machine to start, and after the upper chuck is pre-stretched, the tension test is performed, and the data is saved after completion, and the test is completed.
  • the positive active material lithium cobaltate, conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97.5:1:1.5, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a solid content of 75%. slurry and stir well. The slurry was uniformly coated on one surface of an aluminum foil with a thickness of 12 ⁇ m, and dried at 90° C. to obtain a single-sided coated positive electrode sheet, and the thickness of the positive electrode active material layer was about 100 ⁇ m.
  • NMP N-methylpyrrolidone
  • the polymer is selected from polyvinylidene fluoride (PVDF), the binder is selected from polyvinyl alcohol (PVA), the inorganic particles are selected from alumina (Al 2 O 3 ), and the average particle size of the inorganic particles is 200 nm.
  • PVDF polyvinylidene fluoride
  • PVA polyvinyl alcohol
  • PVA polyvinyl alcohol
  • the inorganic particles are selected from alumina (Al 2 O 3 )
  • the average particle size of the inorganic particles is 200 nm.
  • the slurry A and the slurry C were sprayed alternately in the first region of the electrode sheet by the electrospinning device 60 and the electrospraying device 70 shown in FIG. 6 to obtain a separation layer with a thickness of 7 ⁇ m.
  • the slurry B and the slurry D are sprayed alternately through the electrospinning device 60 and the electrospraying device 70 to obtain an isolation layer with a thickness of 7 ⁇ m.
  • the porosity of the isolation layer is was 48%, and the fiber diameter of the isolation layer was 100 nm.
  • the negative electrode active material graphite, conductive carbon black, and styrene-butadiene rubber were mixed in a weight ratio of 96:1.5:2.5, and deionized water was added as a solvent to prepare a slurry with a solid content of 70%, and the mixture was uniformly stirred.
  • the slurry was uniformly coated on the negative electrode current collector copper foil, dried at 110°C, and cold pressed to obtain a negative electrode pole piece with a negative electrode active material layer thickness of 150 ⁇ m on one side coated with a negative electrode active material layer.
  • the same method is used to complete these steps on the back side of the negative pole piece, that is, the negative pole piece coated on both sides is obtained.
  • the negative pole pieces are cut into sheets with a size of 76 mm ⁇ 851 mm and the tabs are welded for use.
  • the prepared negative pole piece and the positive pole piece of the integrated isolation layer are opposite, stacked and wound into an electrode assembly, so that the positive electrode tab and the negative electrode tab are arranged in the first area of the wound electrode assembly, and then the winding structure ends.
  • the positive electrode head area is glued and placed in an aluminum-plastic film, and after top-side sealing, liquid injection, and packaging, a lithium-ion battery is obtained.
  • Example 1 ⁇ Preparation of Separation Layer>, in addition to adjusting the content of the binder in the slurry A, slurry B, slurry C, and slurry D, the binder content in the polymer fibers in the first region, the first Except for the content of binder in inorganic particles in one area, the content of binder in polymer fibers in the second area, and the content of binder in inorganic particles in the second area as shown in Table 1 corresponding to each example, the rest are the same as those shown in Table 1.
  • Example 1 is the same.
  • Example 1 The same as Example 1 except that ⁇ Preparation of positive electrode sheet> and ⁇ Preparation of negative electrode sheet> were different from those of Example 1.
  • the positive active material lithium cobaltate, conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97.5:1:1.5, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a solid content of 75%. slurry and stir well.
  • the slurry was uniformly coated on one surface of an aluminum foil with a thickness of 12 ⁇ m, dried at 90° C., and then cold-pressed to obtain a positive electrode sheet with a positive electrode active material layer with a thickness of 100 ⁇ m on one side coated with a positive electrode active material layer, and then The above steps are repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. Cut the positive pole piece into a size of 74mm ⁇ 867mm and weld aluminum tabs for use.
  • the negative electrode active material graphite, conductive carbon black, and styrene-butadiene rubber are mixed according to the weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a solid content of 70%, and stir evenly.
  • the slurry was uniformly coated on the copper foil of the negative electrode current collector, and dried at 110° C. to obtain a single-sided coated positive electrode piece, and the thickness of the negative electrode active material layer was about 100 ⁇ m.
  • the content of , the content of the binder in the polymer fibers in the second region, and the content of the binder in the inorganic particles in the second region are as shown in Example 10 in Table 1, and the rest are the same as in Example 1.
  • the rest is the same as in Example 3 except that the separator is coated on one side of the positive electrode sheet.
  • Example 3 The same procedure as in Example 3 was performed except that the thickness of one side of the isolation layer was adjusted to 3 ⁇ m.
  • Example 3 The same procedure as in Example 3 was performed except that the thickness of one side of the isolation layer was adjusted to 15 ⁇ m.
  • Example 1 ⁇ Preparation of Separation Layer>, in addition to adjusting the content of the binder in the slurry A, slurry B, slurry C, and slurry D, the binder content in the polymer fibers in the first region, the first Except for the content of binder in inorganic particles in one area, the content of binder in polymer fibers in the second area, and the content of binder in inorganic particles in the second area as shown in Table 1 corresponding to each example, the rest are the same as those shown in Table 1.
  • Example 1 is the same.
  • Example 1 ⁇ Preparation of Separation Layer>, in addition to adjusting the content of the binder in the slurry A, slurry B, slurry C, and slurry D, the binder content in the polymer fibers in the first region, the first Except for the content of binder in inorganic particles in one area, the content of binder in polymer fibers in the second area, and the content of binder in inorganic particles in the second area as shown in Table 1 corresponding to each example, the rest are the same as those shown in Table 1.
  • Example 1 is the same.
  • the polymer is selected from polyvinylidene fluoride
  • the binder is selected from polyvinyl alcohol
  • the inorganic particles are selected from alumina
  • the average particle diameter of the inorganic particles is 200 nm.
  • the second sub-region in the first region of the electrode sheet is sprayed alternately with the slurry A and the slurry C through the electrospinning device 60 and the electrospraying device 70 shown in FIG. 6 to obtain an isolation layer with a thickness of 7 ⁇ m;
  • the slurry B and the slurry D are sprayed alternately through the electrospinning equipment 60 and the electrospray equipment 70 to obtain an isolation layer with a thickness of 7 ⁇ m, the porosity of the isolation layer is 48%, and the thickness of the isolation layer is 48%.
  • the fiber diameter is 100 nm.
  • Example 19 in addition to adjusting the content of the binder in slurry A, slurry B, slurry C, and slurry D, the binder content in the polymer fibers in the second sub-region, the Except for the binder content in the inorganic particles in the second sub-region, the binder content in the polymer fibers in the first sub-region, and the binder content in the inorganic particles in the first sub-region as shown in Table 2 corresponding to Example 20, the rest Same as Example 19.
  • Example 19 in addition to adjusting the content of the binder in slurry A, slurry B, slurry C, and slurry D, the binder content in the polymer fibers in the second sub-region, the Except for the binder content in the inorganic particles in the second sub-region, the binder content in the polymer fibers in the first sub-region, and the binder content in the inorganic particles in the first sub-region as shown in Table 2 corresponding to Example 21, the rest Same as Example 19.
  • the positive active material lithium cobaltate, conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97.5:1:1.5, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a solid content of 75%. slurry and stir well.
  • the slurry was uniformly coated on one surface of an aluminum foil with a thickness of 12 ⁇ m, dried at 90° C., and then cold-pressed to obtain a positive electrode sheet with a positive active material layer thickness of 100 ⁇ m, and then on the other surface of the positive electrode sheet.
  • the above steps are repeated to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. Cut the positive pole piece into a size of 74mm ⁇ 867mm and weld aluminum tabs for use.
  • the negative electrode active material graphite, conductive carbon black, and styrene-butadiene rubber are mixed according to the weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a solid content of 70%, and stir evenly.
  • the slurry was uniformly coated on the negative electrode current collector copper foil, dried at 110°C, and cold pressed to obtain a negative electrode pole piece with a negative electrode active material layer thickness of 150 ⁇ m on one side coated with a negative electrode active material layer.
  • the same method is used to complete these steps on the back side of the negative pole piece, that is, the negative pole piece coated on both sides is obtained.
  • the negative pole pieces are cut into sheets with a size of 76 mm ⁇ 851 mm and the tabs are welded for use.
  • Porous polyethylene (PE) separator is selected, the average pore size is 0.073 ⁇ m, the porosity is 26%, and the thickness of the separator is 20 ⁇ m.
  • the prepared positive pole piece, separator and negative pole piece are oppositely stacked and wound to form an electrode assembly. After the end of the winding structure, the pole ear, and the positive head area are glued, they are placed in an aluminum plastic film. After top-side sealing, liquid injection, and packaging, a lithium-ion battery is obtained.
  • Al 2 O 3 and polyacrylate were mixed in a mass ratio of 90:10 and dissolved in deionized water to form a ceramic slurry with a solids content of 50%. Then, the ceramic slurry was uniformly coated on one side of a polyethylene (PE) porous substrate (thickness 7 ⁇ m, average pore size 0.073 ⁇ m, porosity 26%) by gravure coating method, and dried to obtain ceramic slurry.
  • PE polyethylene
  • PVDF and polyacrylate were mixed in a mass ratio of 96:4 and dissolved in deionized water to form a polymer slurry with a solids content of 50%. Then, the polymer slurry is uniformly coated on both surfaces of the above-mentioned double-layer structure of the ceramic coating layer and the porous substrate by the gravure coating method, and is subjected to drying treatment to obtain a separator, wherein the single layer formed by the polymer slurry is The coating thickness is 2 ⁇ m.
  • the rest is the same as that of Comparative Example 1, and the thickness of the non-woven fabric is 20 ⁇ m.
  • Example 1 The rest is the same as that of Example 1, except that ⁇ Preparation of positive electrode sheet> is different from that of Example 1.
  • the positive active material lithium cobalt oxide, conductive carbon black, and PVDF are mixed in a mass ratio of 97.5:1:1.5, and then NMP is added as a solvent to prepare a slurry with a solid content of 75%, and stir evenly.
  • the slurry was uniformly coated on one surface of an aluminum foil with a thickness of 12 ⁇ m, and dried at 90° C. to obtain a single-sided coated positive electrode sheet, and the thickness of the positive electrode active material layer was about 100 ⁇ m.
  • the electrospinning equipment 60 shown in FIG. 6 is used to spray a layer of PVDF and PE mixed fiber layer with a thickness of 10 ⁇ m, wherein the fiber layer has an average pore diameter of 100 nm and a porosity of 50%. Then, the slurry F was sprayed onto the surface of the PVDF+PE fiber layer by the electrospray equipment 70 to form a separation layer with a thickness of 12 ⁇ m.
  • the lithium ion battery with the isolation layer of the present application has an improved cycle capacity retention rate, indicating that the lithium ion battery of the present application not only has excellent resistance to deformation capability, but also has a long service life.
  • the volume fraction of inorganic particles in the isolation layer usually affects the strength of the isolation layer; the thickness of the isolation layer usually affects its strength and bonding properties; the porosity usually affects the air permeability of the isolation layer; the fiber diameter of the polymer fiber usually affects the isolation layer. Strength; the average particle size of the inorganic particles generally affects the adhesive properties of the release layer.

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Abstract

一种卷绕式电极组件、电化学装置及电子装置，其中卷绕式电极组件包括电极极片以及在电极极片的至少一个表面上的隔离层（30），在卷绕式电极组件的第一区域内隔离层（30）与电极极片表面之间的粘结力大于在卷绕式电极组件的第二区域内的粘结力，使得卷绕式电极组件中第一区域内隔离层（30）与电极极片表面之间的粘结力较高，第二区域内的电极极片在受到应力时，层与层之间相互可以产生微小的滑移，从而释放应力，因而能够减少因现有隔离膜与电极极片表面之间的粘结力一致而导致的应力集中情况的发生，减少电化学装置因应力集中而导致的变形，从而提高电化学装置的安全性。

Description

一种卷绕式电极组件、电化学装置及电子装置 技术领域
本申请涉及电化学领域，具体涉及一种卷绕式电极组件、电化学装置及电子装置。
背景技术
锂离子电池具有比能量大、工作电压高、自放电率低、体积小、重量轻等特点，广泛应用于电能储存、便携式电子设备和电动汽车等各个领域。随着电动汽车和可移动电子设备的高速发展，人们对锂离子电池的性能需求也越来越高，例如需要锂离子电池具有更高的能量密度、安全性、循环性能等。
现有锂离子电池的隔离膜通常以整体结构存在于电极组件中，主要起到隔离正极和负极、以及保证离子传导和隔绝电子传导的作用。在隔离膜和电极极片之间通常设置有粘度一致的粘结层以提高隔离膜和电极极片间的结合力。但是对于形状复杂的锂离子电池而言，由于其结构的特殊性，不同区域的内部受力情况不同，在一些区域内锂离子电池内部容易产生应力集中，降低锂离子电池的安全性。因此亟需一种新的锂离子电池，以提高锂离子电池的安全性。
发明内容
本申请的目的在于提供一种卷绕式电极组件、电化学装置及电子装置，以提高电化学装置的安全性。
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。
具体技术方案如下：
本申请的第一方面提供了一种卷绕式电极组件，其包括电极极片以及在电极极片的至少一个表面上的隔离层，卷绕式电极组件具有第一区域和第二区域，在卷绕式电极组件的第一区域内隔离层与电极极片表面之间的粘结力大于在卷绕式电极组件的第二区域内所述隔离层与电极极片表面之间的的粘结力，第二区域为卷绕式电极组件的卷回区。
从整体上而言，本申请的卷绕式电极组件中具有第一区域和第二区域，其中第二区域对应卷绕式电极组件中的电极极片的卷回区，第一区域为卷绕式电极组件中除第二区域以外的区域，在卷绕式电极组件的第一区域内隔离层与电极极片表面之间的粘结力大于在卷绕式电极组件的第二区域内的粘结力，使得卷绕式电极组件中第一区域内隔离层与电极极 片表面之间的粘结力较高，第二区域内的电极极片在受到应力时，层与层之间相互可以产生微小的滑移，从而释放应力，因而能够降低因现有隔离膜与电极极片表面之间的粘结力一致而导致的应力集中情况的发生，减少锂离子电池在循环过程中因应力集中而导致的变形，从而提高锂离子电池的安全性。
在本申请的一种实施方案中，第一区域内的隔离层与电极极片表面之间的粘结力F 1与第二区域内的隔离层与电极极片表面之间的粘结力F 2之差在1N/m至15N/m范围内，优选为5N/m至10N/m范围内，例如，第一区域内的隔离层与电极极片表面之间的粘结力F 1与第二区域内的隔离层与电极极片表面之间的粘结力F 2之差的下限值可以包括以下数值中：1N/m、2N/m、3N/m、4N/m或5N/m；第一区域内的隔离层与电极极片表面之间的粘结力F 1与第二区域内的隔离层与电极极片表面之间的粘结力F 2之差的上限值可以包括以下数值中：6N/m、8N/m、10N/m、12N/m或15N/m。
通过控制第一区域内的隔离层与电极极片表面之间的粘结力F 1与第二区域内的隔离层与电极极片表面之间的粘结力F 2之差在上述范围内，避免了第二区域内的电极极片因应力集中而变形，从而提高了锂离子电池的安全性。
在本申请的一种实施方案中，第一区域内隔离层与电极极片表面之间的粘结力F 1可以为1N/m至30N/m，优选为10N/m至20N/m。可以理解，当第一区域内隔离层与电极极片表面之间的粘结力F 1增大时，第二区域内隔离层与电极极片表面之间的粘结力F 2可以随之增大，只要使得第一区域内隔离层与电极极片表面之间的粘结力F 1大于第二区域内的粘结力F 2即可。第一区域内隔离层与电极极片表面之间的粘结力F 1大于第二区域内隔离层与电极极片表面之间的粘结力F 2，从而避免第二区域内的电极极片因应力集中而变形。
在本申请的一种实施方案中，第二区域内隔离层与电极极片表面之间的粘结力F 2可以为2N/m至15N/m，只要使得第二区域内隔离层与电极极片表面之间的粘结力F 2小于第一区域内的粘结力F 1即可，避免了第二区域内的电极极片因应力集中而变形。
在本申请的一种实施方案中，卷绕式电极组件包括平直区和卷回区，平直区中的隔离层与电极极片表面之间的粘结力大于卷回区中的隔离层与电极极片表面之间的粘结力。
上述平直区可以指卷绕式电极组件中电极极片为平直的区域，上述卷回区可以指卷绕式电极组件中电极极片为卷回的区域，通常情况下在卷绕式电极组件的卷回区更容易产生应力集中，这是由于卷回区的电极极片呈弯曲状态，受挤压程度更高。普通锂离子电池在300次循环后变形率约为6％至7％，而目前具有高粘度隔离膜的锂离子电池300次循环后 变形率甚至高于10％。并且在受压作用下，使得卷回区的电极极片界面间隙减小而导致保液空间及电解液传输通道变少，锂离子电池内部易出现紫斑和析锂，存在安全隐患。基于此，本申请的平直区中的隔离层与电极极片表面之间的粘结力可以设置为大于卷回区中的隔离层与电极极片表面之间的粘结力，这样卷回区中隔离层与电极极片表面之间的粘结力相对更低。在包含上述卷绕式电极组件的锂离子电池充放电过程中，卷回区的层与层之间相互可以产生微小的滑移，从而释放应力，避免卷回区中的电极极片因应力集中而变形，从而提高了锂离子电池的安全性。
在本申请的一种实施方案中，第一区域具体可以指卷绕式电极组件的平直区，第二区域具体可以指卷绕式电极组件的卷回区，则平直区内隔离层与电极极片表面之间的粘结力可以为1N/m至30N/m，优选为10N/m至20N/m。当平直区的隔离层与电极极片表面之间的粘结力增大时，卷回区的隔离层与电极极片表面之间的粘结力可以随之增大，只要使得平直区的隔离层与电极极片表面之间的粘结力大于卷回区的粘结力即可。
在本申请的一种实施方案中，本申请的电极组件为卷绕结构，其包含分别位于卷绕式电极组件左、右两侧的第二区域以及位于卷绕式电极组件中部的第一区域。卷绕式电极组件的厚度表示为L，则第二区域可以指卷绕式电极组件平放时，卷绕式电极组件两侧分别距其最外端边缘1/2L的长度所包含的区域，第一区域是卷绕式电极组件中除上述第二区域以外的区域。可以理解的是，第二区域的电极极片呈弯曲的卷回状，而第一区域的电极极片呈平直状。
在本申请的一种实施方案中，卷绕式电极组件的第一区域中可以包括第一子区域和第二子区域。所说的第一子区域是指第一区域内的包含极耳的区域，也即卷绕式电极组件的极耳区，第二子区域是指第一区域内的不包含极耳的区域。极耳具有厚度，由于极耳的存在，第一子区域的电极极片更容易出现应力集中，本申请中第二子区域中的隔离层与电极极片之间的粘结力F 3可以大于第一子区域中的隔离层与电极极片之间的粘结力F 4，从而避免第一子区域的电极极片因应力集中而变形，进一步提高了锂离子电池的安全性。
在本申请的一种实施方案中，第二子区域中的隔离层与电极极片之间的粘结力F 3可以为15N/m至20N/m，第一子区域中的隔离层与电极极片之间的粘结力F 4可以为10N/m至15N/m，使得第二子区域中的隔离层与电极极片之间的粘结力F 3大于第一子区域中的隔离层与电极极片之间的粘结力F 4即可。
在本申请的一种实施方案中，可以在电极极片的不同区域内设置与电极极片表面之间 具有不同粘结力的隔离层，从而使第一区域内的隔离层与电极极片表面之间的粘结力大于第二区域内的隔离层与电极极片表面之间的粘结力。
在本申请的一种实施方案中，可以在卷绕式电极组件的不同区域内设置具有不同粘度粘结剂的隔离层来调控隔离层与电极极片表面之间粘结力，例如，在第二区域内设置具有低粘度粘结剂的隔离层，在第一区域设置具有高粘度粘结剂的隔离层。这样便可以使第一区域内的隔离层与电极极片表面之间的粘结力大于第二区域内的隔离层与电极极片表面之间的粘结力，从而避免第二区域内的电极极片因应力集中而变形。可以通过调整粘结剂在浆料中的含量以改变隔离层中粘结剂的粘度。本申请所说的高粘度可以是指界面间粘结力F：10N/m<F≤20N/m，低粘度可以是界面间粘结力F：1N/m≤F≤10N/m。
在本申请的一种实施方案中，可以通过在需要高粘结力的区域内提高隔离层中粘结剂的含量来调控隔离层与电极极片表面之间粘结力。可以理解的是，所述隔离层中包含聚合物纤维，在聚合物纤维中可以包括粘结剂，则在所述第一区域内，所述聚合物纤维中粘结剂含量可以为5wt％至25wt％，优选为8wt％至17wt％，例如，聚合物纤维中粘结剂含量的下限值可以包括以下数值中：5wt％、8wt％、10wt％、12wt％或15wt％。
在所述第二区域内，所述聚合物纤维中粘结剂含量可以为2wt％至20wt％，优选为6wt％至15wt％，例如，聚合物纤维中粘结剂含量的上限值可以包括以下数值中：8wt％、12wt％、15wt％、17wt％或20wt％。使得第一区域内聚合物纤维中粘结剂的含量高于第二区域内聚合物纤维中粘结剂的含量，从而使第一区域内的隔离层与电极极片表面之间的粘结力大于第二区域内的隔离层与电极极片表面之间的粘结力。
在本申请的一种实施方案中，隔离层中的聚合物纤维的纤维直径为10nm至5μm，优选为20nm至2μm，例如，聚合物纤维的纤维直径的下限值可以包括以下数值中：20nm、50nm、100nm或500nm；聚合物纤维的纤维直径的上限值可以包括以下数值中：1000nm、1500nm或2μm。通过控制聚合物纤维的直径在上述范围内，能够提高聚合物纤维的结构强度。
在本申请的一种实施方案中，隔离层的厚度为1μm至50μm，优选为3μm至15μm。通过控制隔离层的厚度在上述范围内，能够使隔离层具有优异的结构强度的同时还不会过厚，提高了活性材料在锂离子电池中的相对含量，从而提升锂离子电池的能量密度。
在本申请的一种实施方案中，隔离层中还可以包含无机颗粒，无机颗粒体积占隔离层中固体物质总体积不超过40％，优选为15％至30％，例如，无机颗粒体积占隔离层中固体 物质总体积的下限值可以包括以下数值中：5％、9％、18％或21％、；无机颗粒体积占隔离层中固体物质总体积的上限值可以包括以下数值中：24％、27％、35或40％。无机颗粒的加入可以提高隔离层的强度。
在本申请的一种实施方案中，隔离层中的无机颗粒的平均粒径为20nm至5μm，优选为50nm至2μm，例如：无机颗粒的平均粒径的下限值可以包括以下数值中：50nm、100nm或500nm；无机颗粒的平均粒径的上限值可以包括以下数值中：1000nm、1500nm或2μm。通过控制无机颗粒的平均粒径在上述范围内，能够进一步提高隔离层的结构强度。
在本申请的一种实施方案中，上述无机颗粒中可以包括粘结剂，使无机颗粒的附着性更好。在第一区域内，所述无机颗粒中粘结剂含量为4wt％至7wt％，例如，无机颗粒中粘结剂含量为4wt％、5wt％、6wt％或7wt％。
在第二区域内，所述无机颗粒中粘结剂含量为3wt％至15wt％，例如，无机颗粒中粘结剂含量为3wt％、5wt％、7wt％、10wt％或15wt％。由上可以看出，对于第二区域，其无机颗粒中的粘结剂含量比第一区域更高，可以使第二区域内的隔离层具有更高的强度。不过无机颗粒只占隔离层中固体物质总体积不超过40％，表明隔离层中聚合物纤维的比例更高。可见，通过调整第一区域和第二区域的聚合物纤维中粘结剂的含量，就可以实现本申请的发明目的。
在本申请的一种实施方案中，聚合物纤维中还可以包含无机填料，无机填料在所述聚合物纤维中的含量为5wt％至10wt％，例如，无机填料在所述聚合物纤维中的含量为5wt％、6wt％、7wt％、8wt％、9wt％或10wt％。通过控制无机填料在聚合物纤维中的含量在上述范围内，能够使聚合物纤维具有良好的结构强度，但无机填料不宜添加过多，否则会影响聚合物纤维的粘结性能。
本申请对聚合物纤维没有特别限制，只要满足本申请要求即可，例如聚合物纤维可以包括聚偏氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯、聚偏氟乙烯-六氟丙烯或聚偏二氟乙烯-共-三氟氯乙烯或上述物质衍生物的纤维中的至少一种。
本申请对隔离层中的无机颗粒的无机物没有特别限制，并且本申请对聚合物纤维中的无机填料的无机物也没有特别限制，只要满足本申请要求即可，例如上述无机物可以包括氧化铪、钛酸锶、二氧化锡、氧化铯、氧化镁、氧化镍、氧化钙、氧化钡、氧化锌、氧化锆、氧化钇、氧化铝、氧化钛、二氧化硅、勃姆石、氢氧化镁、氢氧化铝、磷酸锂、锂钛 磷酸盐、锂铝钛磷酸盐、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、氧化锂、氟化锂、氢氧化锂、碳酸锂、偏铝酸锂、锂锗磷硫陶瓷或石榴石陶瓷中的至少一种。
本申请对粘结剂没有特别限制，只要满足本申请要求即可，例如可以包括聚乙烯醇、聚四氟乙烯、丁苯橡胶、羧甲基纤维素钠、聚苯烯酸、聚丙烯酸丁酯、聚丙烯腈、聚氨酯或丙烯腈多元共聚物中的至少一种。
本申请对隔离层的制备方法没有特别限制，可以采用本领域技术人员公知的制备方法，例如可以采用如下制备方法：
将聚合物和含量不同的粘结剂分散在有机溶剂中，并搅拌均匀至浆料粘度稳定，得到粘结剂含量不同的浆料A和浆料B，其中，粘结剂在浆料A中的含量大于在浆料B中的含量。
将无机颗粒和粘结剂分散在有机溶剂中，并搅拌均匀至浆料粘度稳定，制备浆料C和浆料D。其中，浆料C中粘结剂的含量可以大于浆料D中粘结剂的含量，或者浆料C和浆料D中粘结剂的含量相同。
在电极极片的第一区域利用浆料A和浆料C通过电纺丝设备和电喷雾设备交替喷涂得到隔离层。
在电极极片的第二区域利用浆料B和浆料D通过电纺丝设备和电喷雾设备交替喷涂得到隔离层，使所得到的隔离层中，第一区域内隔离层中的粘结剂含量大于第二区域内隔离层中的粘结剂含量。其中，电纺丝设备和电喷雾设备均连接有稳压器。
若需要制备双面设置隔离层的电极极片，则可以在电极极片背面重复上述步骤，即得到双面设置隔离层的电极极片。
并且，若需要进一步提高聚合物纤维的强度，则可以在含有聚合物的浆料中加入无机填料，例如加入氧化钙。本申请中的无机填料和无机颗粒可以选自相同的无机物，也可以选自不同的无机物。
本领域技术人员应当理解，本申请可以在正极极片表面制备隔离层，也可以在负极极片表面制备隔离层，当然，还可以在正、负极极片表面同时制备隔离层，只要保证卷绕式电极组件中不同区域的隔离层与电极极片表面之间的粘结力不均匀即可，这些都应当属于本申请的保护范围。
示例性地，可以在正极极片的其中一面设置上述隔离层，或者在负极极片的其中一面 设置上述隔离层，或者在正极极片的两面均设置上述隔离层，或者在负极极片的两面均设置上述隔离层，或者在正极极片的其中一面和负极极片的其中一面设置上述隔离层，只要保证卷绕式电极组件中不同区域的隔离层与电极极片表面之间的粘结力不均匀即可。
本申请中的正极极片没有特别限制，只要能够实现本申请目的即可。例如，正极极片通常包含正极集流体和正极活性物质层。其中，正极集流体没有特别限制，可以为本领域公知的任何正极集流体，例如铝箔、铝合金箔或复合集流体等。正极活性物质层包括正极活性物质，正极活性物质没有特别限制，可以使用本领域公知的任何正极活性物质，例如，可以包括镍钴锰酸锂(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中的至少一种。
本申请中的负极极片没有特别限制，只要能够实现本申请目的即可。例如，负极极片通常包含负极集流体和负极活性物质层。其中，负极集流体没有特别限制，可以使用本领域公知的任何负极集流体，例如铜箔、铝箔、铝合金箔以及复合集流体等。负极活性物质层包括负极活性物质，负极活性物质没有特别限制，可以使用本领域公知的任何负极活性物质。例如，可以包括人造石墨、天然石墨、中间相碳微球、软碳、硬碳、硅、硅碳、钛酸锂等中的至少一种。
本申请的锂离子电池还包括电解质，电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。
在本申请一些实施方案中，锂盐选自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、LiSiF 6、LiBOB和二氟硼酸锂中的一种或多种。举例来说，锂盐可以选用LiPF 6，因为它可以给出高的离子导电率并改善循环特性。
非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。
上述碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。
上述链状碳酸酯化合物的实例为碳酸二甲酯(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)、碳酸甲乙酯(MEC)及其组合。环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)及其组合。氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(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、碳酸三氟甲基亚乙酯及其组合。
上述羧酸酯化合物的实例为甲酸甲酯、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、己内酯及其组合。
上述醚化合物的实例为二丁醚、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、四氢呋喃及其组合。
上述其它有机溶剂的实例为二甲亚砜、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、和磷酸酯及其组合。
本申请还提供了一种电化学装置，包括电极组件和电解液，所述电极组件为上述任一实施方案所说的卷绕式电极组件，该电化学装置具有良好的安全性能。
本申请还提供了一种电子装置，包含本申请实施方案中所述的电化学装置，该电子装置具有良好的安全性能。
本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、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。
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。例如电化学装置可以通过以下过程制造：将正极和负极经由隔离膜重叠，并根据需要将其卷绕、折叠等操作后放入壳体内，将电解液注入壳体并封口，其中所用的隔离膜为本申请提供的上述隔离膜。此外，也可以根据需要将防过电流元件、导板等置于壳体中，从而防止电化学装置内部的压力上升、过充放电。
本申请提供的一种卷绕式电极组件，在卷绕式电极组件的第一区域内隔离层与电极极片表面之间的粘结力大于在卷绕式电极组件的第二区域内的粘结力，使得卷绕式电极组件中第一区域内隔离层与电极极片表面之间的粘结力较高，第二区域内的电极极片在受到应 力时层与层之间相互可以产生微小的滑移，从而释放应力，因而能够降低因现有隔离膜与电极极片表面之间的粘结力一致而导致的应力集中情况的发生，减少锂离子电池因应力集中而导致的变形，从而提高锂离子电池的安全性。
附图说明
为了更清楚地说明本申请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为本申请一种实施方案的锂离子电池的结构示意图；
图2为本申请另一种实施方案中的卷绕式电极组件的结构示意图(沿极片的表面方向)；
图3为本申请的一种实施方案中隔离层设置于单面涂布的电极极片的结构示意图；
图4为本申请的一种实施方案中隔离层设置于双面涂布的正极极片的结构示意图；
图5为本申请的一种实施方案中隔离层设置于双面涂布的负极极片的结构示意图；
图6为本申请的一种实施方案中纺丝和电喷雾设备的一种结构示意图；
图7为本申请进行粘结力测试过程中电极极片堆叠的一种结构示意图。
附图标记：1：第一子区域；2：第二子区域；3：集流体层；4：双面胶；5：拉力加持板；6：压力板；7：贴胶处；8：封装袋；9：电极活性材料层；10：正极集流体；11：极耳；20：正极活性材料层；30：隔离层；40：负极活性材料层；50：负极集流体；60：电纺丝设备；70：电喷雾设备；80：稳压器。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图和实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，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。
图1示出了本申请一种实施方案中的卷绕式电极组件的结构示意图，参考图1，该电极组件为卷绕结构，其包含位于卷绕式电极组件左、右两端的第二区域以及位于卷绕式电极组件中部的第一区域。
如图1所示，在本申请的一种实施方案中，卷绕式电极组件可以包括第一子区域1和第二子区域2，所说的第一子区域1是指图1所示的第一区域中包含极耳11的区域，第二子区域是指图1所示的第一区域中不包含极耳11的区域。
图2为本申请一种实施方案中的卷绕式电极组件的结构示意图(沿极片的表面方向)， 在本申请的一种实施方案中，如图2所示，第二区域中使用的粘结剂的粘度低于第一区域中使用的粘结剂的粘度，使第一区域中的隔离层与电极极片表面之间的粘结力大于第二区域中的隔离层与电极极片表面之间的粘结力。
在本申请的一种实施方案中，本申请的隔离层可以设置在电极极片的至少一个表面上，例如，可以是如图3所示的电极极片单面设置隔离层的结构，也可以是图4所示的正极极片双面设置隔离层的结构，还可以是图5所示的负极极片双面设置隔离层的结构，具体地例如，图3中正极极片和负极极片的其中一个表面设置有隔离层30，图4中正极极片的两个表面均设置有隔离层30，图5中负极极片的两个表面均设置有隔离层30。其中，正极极片包括正极集流体10和正极活性材料层20，负极极片包括负极集流体50和负极活性材料层40。
图6为本申请的一种实施方案中纺丝和电喷雾设备的结构示意图，该设备中包括电纺丝设备60、电喷雾设备70以及稳压器80。
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。
测试方法和设备：
锂离子电池变形程度测试：
锂离子电池容量完成后，即锂离子电池电池完成第一次充放电循环后再充一半电量的状态时，测量锂离子电池的第一区域和第二区域(卷回区)电池厚度，各区域分别取3个点，记录厚度数据H 0；锂离子电池经300次充放电循环测试后，与容量完成时保持相同的充电状态(例如相同的电压)，选择相同测量位置，使用相同的测量工具测量锂离子电池的厚度，记录数据H 1，通过以下表达式计算各测量位置的变形率：
测量位置变形度率＝(H 1-H 0)/H 0×100％
然后将不同位置的计算结果取平均值，得到锂离子电池变形率。
锂离子电池放电能量密度测试：
将锂离子电池在常温下静置30分钟，以0.05C充电速率恒流充电至电压4.45V，随后再以0.05C倍率将电化学装置放电至3.00V，重复上述充/放电步骤3个循环以完成待测锂 离子电池的化成。完成锂离子电池的化成后，以0.2C充电速率恒流恒压充电至电压4.45V，随后以0.2C放电倍率将电化学装置放电至3.00V，记录其放电能量，随后计算其0.2C放电时的能量密度：
能量密度(Wh/L)＝放电能量(Wh)/锂离子电池体积尺寸(L)
锂离子电池容量保持率测试：
测试环境温度25℃，对比例和实施例均采用同一充电流程：以恒流充电阶段的电流为0.7C充电至截止电压为4.5V，然后恒压充电至截止电流为0.05C时停止充电，电池满充后均静置5min，再以0.5C电流放电至3.0V，此为一个充放电循环过程，反复300次这种充放电循环之后，采用300次循环后的放电容量除以第一次循环的放电容量即为循环容量保持率。
粘结力测试：
将普通电极极片(正极极片或负极极片)和集成隔离层的电极极片分别裁切成50mm×100mm的长条，然后将二者堆叠形成如图7所示的三明治结构，使隔离层30的两侧与电极活性材料层9接触，拉力加持板5通过双面胶4与集流体层3粘接，然后将上述三明治结构置于封装袋8中并密封，再在该三明治结构中滴加电解液(电解液的组成和浓度均和锂离子电池中的相同)，静置至上述集成隔离层的电极极片的表面为完全湿润状态，再将包含上述三明治结构的封装袋置于压力机平板上，压力板6具有加热功能，压力板加热至90℃后，压力机施加压力1Mpa，持续30min，完成卸载压力，待压力板冷却后取出被压物，进行粘结力测试。
将热压后的三明治结构从封装袋8中取出，转移至拉力机设备，拉力夹持板5的末端固定在拉力机的下夹头，与地面保持垂直状态，隔离层30的贴胶处7固定在拉力机的上夹头，使上夹头与样品表面保持平行，将上下夹头分别用夹具夹紧。需保证操作台控制拉力机启动，上夹头进行预拉伸后，进行拉力测试，完成后保存数据，测试完成。
实施例1
<正极极片的制备>
a)<正极活性材料的涂布>
将正极活性材料钴酸锂、导电炭黑、聚偏二氟乙烯(PVDF)按质量比97.5︰1︰1.5 混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为12μm的铝箔的一个表面上，90℃条件下烘干，得到单面涂布的正极极片，正极活性材料层厚度约100μm。
b)<隔离层的制备>
浆料的制备：
聚合物选用聚偏氟乙烯(PVDF)，粘结剂选用聚乙烯醇(PVA)，无机颗粒选用氧化铝(Al 2O 3)，无机颗粒的平均粒径为200nm。
将PVDF和PVA分散在二甲基甲酰胺(DMF)︰丙酮＝7︰3的混合溶剂中，搅拌均匀至浆料粘度稳定，得到固含量为25％的浆料A，其中PVDF与PVA之间的质量比为91.3︰8.7；
将PVDF和PVA分散在DMF︰丙酮＝7︰3的混合溶剂中，搅拌均匀至浆料粘度稳定，得到固含量为25％的浆料B，其中PVDF与PVA之间的质量比为94︰6；
将Al 2O 3和PVA分散在DMF︰丙酮＝7︰3的混合溶剂中，并搅拌均匀至浆料粘度稳定，得到固含量为40％的浆料C，其中Al 2O 3与PVA之间的质量比为95.9︰4.1；
将Al 2O 3和PVA分散在DMF︰丙酮＝7︰3的混合溶剂中，并搅拌均匀至浆料粘度稳定，得到固含量为40％的浆料D，其中Al 2O 3与PVA之间的质量比为96.8︰3.2。
第一区域隔离层的制备：
在电极极片的第一区域内利用浆料A和浆料C通过图6所示的电纺丝设备60和电喷雾设备70交替喷涂，得到厚度为7μm的隔离层。
卷回区隔离层的制备：
在电极极片的第二区域(即卷回区)内利用浆料B和浆料D通过电纺丝设备60和电喷雾设备70交替喷涂，得到厚度为7μm的隔离层，隔离层的孔隙率为48％，隔离层的纤维直径为100nm。
c)<双面涂布电极极片的制备>
在正极极片背面重复上述步骤a和b，然后在40℃条件下真空烘干去除DMF等分散剂，随后升高温度至80℃热处理6h(小时)以完成交联过程，即得到双面集成隔离层的正极极片，然后将正极极片裁切成规格为74mm×867mm的片材并焊接极耳待用。
<负极极片的制备>
将负极活性材料石墨、导电炭黑、丁苯橡胶按照重量比96︰1.5︰2.5进行混合，加入 去离子水作为溶剂，调配成为固含量为70％的浆料，并搅拌均匀。将浆料均匀涂覆在负极集流体铜箔上，110℃条件下烘干，冷压后得到负极活性材料层厚度为150μm的单面涂覆负极活性材料层的负极极片。
以上步骤完成后，采用同样的方法在该负极极片背面也完成这些步骤，即得到双面涂布完成的负极极片。涂布完成后，将负极极片裁切成规格为76mm×851mm的片材并焊接极耳待用。
<电解液的制备>
在干燥氩气气氛中，将有机溶剂碳酸乙烯酯、碳酸甲乙酯和碳酸二乙酯以质量比EC︰EMC︰DEC＝30︰50︰20混合得到有机溶液，然后向有机溶剂中加入锂盐六氟磷酸锂溶解并混合均匀，得到锂盐的浓度为1.15Mol/L的电解液。
<锂离子电池的制备>
将制备好的负极极片和集成隔离层的正极极片相对并叠好卷绕成电极组件，使正极极耳和负极极耳设置于卷绕式电极组件的第一区域，然后卷绕结构收尾处、极耳处，正极头部区域贴胶后，置入铝塑膜中，经顶侧封、注液、封装后，得到锂离子电池。
实施例2-9
在实施例1<隔离层的制备>中除了调整浆料A、浆料B、浆料C、浆料D中粘结剂的含量，使第一区域内聚合物纤维中粘结剂含量、第一区域内无机颗粒中粘结剂含量、第二区域内聚合物纤维中粘结剂含量、第二区域内无机颗粒中粘结剂含量如表1各实施例对应所示的含量以外，其余与实施例1相同。
实施例10
除了<正极极片的制备>和<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>
将正极活性材料钴酸锂、导电炭黑、聚偏二氟乙烯(PVDF)按质量比97.5︰1︰1.5混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为12μm的铝箔的一个表面上，90℃条件下烘干，冷压后得到正极活性材料层厚度为100μm的单面涂覆正极活性材料层的正极极片，然后在该正极极片的另一个表面上重复以上步骤，得到双面涂覆有正极活性材料层的正极极片。将正极极片裁切成74mm×867mm的规格并焊接铝极耳后待用。
<负极极片的制备>
a)<负极活性材料的涂布>
将负极活性材料石墨、导电炭黑、丁苯橡胶按照重量比96︰1.5︰2.5进行混合，加入去离子水作为溶剂，调配成为固含量为70％的浆料，并搅拌均匀。将浆料均匀涂覆在负极集流体铜箔上，110℃条件下烘干，得到单面涂布的正极极片，负极活性材料层厚度约100μm。
b)<隔离层的制备>
调整浆料A、浆料B、浆料C、浆料D中粘结剂的含量，使负极极片中第一区域聚合物纤维中的粘结剂含量、第一区域无机颗粒中粘结剂的含量、第二区域聚合物纤维中粘结剂的含量、第二区域无机颗粒中粘结剂的含量如表1实施例10所示的含量以外，其余与实施例1相同。
c)<双面涂布电极极片的制备>
在负极极片背面重复上述步骤a和b，然后在40℃条件下真空烘干去除DMF等分散剂，随后升高温度至80℃热处理6h(小时)以完成交联过程，即得到双面集成隔离层的负极极片，然后将负极极片裁切成规格为74mm×851mm的片材待用。
实施例11
除了将隔离层涂布在正极极片的单面以外，其余与实施例3相同。
实施例12
除了将隔离层的单面厚度调整为3μm以外，其余与实施例3相同。
实施例13
除了将隔离层的单面厚度调整为15μm以外，其余与实施例3相同。
实施例14
除了在<隔离层的制备>中，聚合物选用聚酰亚胺，粘结剂选用丁苯橡胶，无机颗粒选用氧化镁，无机颗粒的平均粒径为50nm，隔离层的纤维直径为20nm以外，其余与实施例3相同。
实施例15
除了在<隔离层的制备>中，聚合物选用聚丙烯腈，粘结剂选用羧甲基纤维素钠，无机颗粒选用氧化钙，无机颗粒的平均粒径为2μm，隔离层的纤维直径为2μm以外，其余与实施例3相同。
实施例16
在实施例1<隔离层的制备>中除了调整浆料A、浆料B、浆料C、浆料D中粘结剂的含量，使第一区域内聚合物纤维中粘结剂含量、第一区域内无机颗粒中粘结剂含量、第二区域内聚合物纤维中粘结剂含量、第二区域内无机颗粒中粘结剂含量如表1各实施例对应所示的含量以外，其余与实施例1相同。
实施例17
在实施例1<隔离层的制备>中除了调整浆料A、浆料B、浆料C、浆料D中粘结剂的含量，使第一区域内聚合物纤维中粘结剂含量、第一区域内无机颗粒中粘结剂含量、第二区域内聚合物纤维中粘结剂含量、第二区域内无机颗粒中粘结剂含量如表1各实施例对应所示的含量以外，其余与实施例1相同。
实施例18
在<锂离子电池的制备>中，除了将正极极耳和负极极耳设置在卷绕式电极组件的第二区域以外，其余与实施例1相同。
实施例19
除了隔离层的制备与实施例1不同以外，其余与实施例1相同。
<隔离层的制备>
浆料的制备：
聚合物选用聚偏氟乙烯，粘结剂选用聚乙烯醇，无机颗粒选用氧化铝，无机颗粒的平均粒径为200nm。
将PVDF和PVA分散在DMF︰丙酮＝7︰3的混合溶剂中，搅拌均匀至浆料粘度稳定，得到固含量为25％的浆料A，其中PVDF与PVA之间的质量比为83︰17；
将PVDF和PVA分散在DMF︰丙酮＝7︰3的混合溶剂中，搅拌均匀至浆料粘度稳定，得到固含量为25％的浆料B，其中PVDF与PVA之间的质量比为85.6︰14.4；
将Al 2O 3和PVA分散在DMF︰丙酮＝7︰3的混合溶剂中，并搅拌均匀至浆料粘度稳定，得到固含量为40％的浆料C，其中Al 2O 3与PVA之间的质量比为95.2︰4.8；
将Al 2O 3和PVA分散在二甲基甲酰胺︰丙酮＝7︰3的混合溶剂中，并搅拌均匀至浆料粘度稳定，得到固含量为40％的浆料D，其中Al 2O 3与PVA之间的质量比为95.5︰4.5。
第一区域中第二子区域隔离层的制备：
在电极极片第一区域内的第二子区域利用浆料A和浆料C通过图6所示的电纺丝设备60和电喷雾设备70交替喷涂，得到厚度为7μm的隔离层；
第一区域中第一子区域隔离层的制备：
在电极极片第一区域的第一子区域利用浆料B和浆料D通过电纺丝设备60和电喷雾设备70交替喷涂，得到厚度为7μm的隔离层；
第二区域隔离层的制备：
在电极极片的第二区域利用浆料B和浆料D通过电纺丝设备60和电喷雾设备70交替喷涂，得到厚度为7μm的隔离层，隔离层的孔隙率为48％，隔离层的纤维直径为100nm。
实施例20
在实施例19<隔离层的制备>中除了调整浆料A、浆料B、浆料C、浆料D中粘结剂的含量，使第二子区域聚合物纤维中粘结剂含量、第二子区域无机颗粒中粘结剂含量、第一子区域聚合物纤维中粘结剂含量、第一子区域无机颗粒中粘结剂含量如表2中实施例20对应所示的含量以外，其余与实施例19相同。
实施例21
在实施例19<隔离层的制备>中除了调整浆料A、浆料B、浆料C、浆料D中粘结剂的含量，使第二子区域聚合物纤维中粘结剂含量、第二子区域无机颗粒中粘结剂含量、第一子区域聚合物纤维中粘结剂含量、第一子区域无机颗粒中粘结剂含量如表2中实施例21对应所示的含量以外，其余与实施例19相同。
对比例1
<正极极片的制备>
将正极活性材料钴酸锂、导电炭黑、聚偏二氟乙烯(PVDF)按质量比97.5︰1︰1.5混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为12μm的铝箔的一个表面上，90℃条件下烘干，冷压后得到正极活性材料层厚度为100μm的正极极片，然后在该正极极片的另一个表面上重复以上步骤，得到双面涂覆有正极活性材料层的正极极片。将正极极片裁切成74mm×867mm的规格并焊接铝极耳后待用。
<负极极片的制备>
将负极活性材料石墨、导电炭黑、丁苯橡胶按照重量比96︰1.5︰2.5进行混合，加入去离子水作为溶剂，调配成为固含量为70％的浆料，并搅拌均匀。将浆料均匀涂覆在负极集流体铜箔上，110℃条件下烘干，冷压后得到负极活性材料层厚度为150μm的单面涂覆 负极活性材料层的负极极片。
以上步骤完成后，采用同样的方法在该负极极片背面也完成这些步骤，即得到双面涂布完成的负极极片。涂布完成后，将负极极片裁切成规格为76mm×851mm的片材并焊接极耳待用。
<隔离膜的制备>
选用多孔聚乙烯(PE)隔离膜，平均孔径为0.073μm，孔隙率为26％，隔离膜厚度20μm。
<电解液的制备>
在干燥氩气气氛中，将有机溶剂碳酸乙烯酯、碳酸甲乙酯和碳酸二乙酯以质量比EC︰EMC︰DEC＝30︰50︰20混合得到有机溶液，然后向有机溶剂中加入锂盐六氟磷酸锂溶解并混合均匀，得到锂盐的浓度为1.15Mol/L的电解液。
<锂离子电池的制备>
将制备好的正极极片、隔离膜和负极极片相对并叠好卷绕成电极组件，卷绕结构收尾处、极耳处，正极头部区域贴胶后，置入铝塑膜中，经顶侧封、注液、封装后，得到锂离子电池。
对比例2
除了<隔离膜的制备>与对比例1不同以外，其余与对比例1相同。
<隔离膜的制备>
将Al 2O 3与聚丙烯酸酯依照质量比90︰10混合并将其溶入到去离子水中以形成固含量为50％的陶瓷浆料。随后采用微凹涂布法将陶瓷浆料均匀涂布到聚乙烯(PE)多孔基材(厚度7μm，平均孔径为0.073μm，孔隙率为26％)的其中一面上，经过干燥处理以获得陶瓷涂层与多孔基材的双层结构，陶瓷涂层的厚度为50μm。
将PVDF与聚丙烯酸酯依照质量比96︰4混合并将其溶入到去离子水中以形成固含量为50％的聚合物浆料。随后采用微凹涂布法将聚合物浆料均匀涂布到上述陶瓷涂层与多孔基材双层结构的两个表面上，经过干燥处理以获得隔离膜，其中聚合物浆料形成的单层涂层厚度为2μm。
对比例3
除隔离膜选用无纺布外，其余与对比例1相同，无纺布的厚度为20μm。
对比例4
除<正极极片的制备>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>
a)<正极活性材料的涂布>
将正极活性材料钴酸锂、导电炭黑、PVDF按质量比97.5︰1︰1.5混合，然后加入NMP作为溶剂，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为12μm的铝箔的一个表面上，90℃条件下烘干，得到单面涂布的正极极片，正极活性材料层厚度约100μm。
b)<隔离层的制备>
将PVDF和低熔点PE(熔点90℃至115℃)分散在DMF︰丙酮＝7︰3的混合溶剂中，搅拌均匀至浆料粘度稳定，得到固含量为25％的浆料E，其中PVDF与低熔点PE之间的质量比为82︰18；
将Al 2O 3和低熔点PE分散在NMP︰丙酮＝7︰3的混合溶剂中，并搅拌均匀至浆料粘度稳定，得到固含量为40％的浆料F，其中，Al 2O 3与低熔点PE之间的质量比为95︰5；
在正极极片表面利用浆料E通过图6所示的电纺丝设备60喷涂得到一层厚度为10μm的PVDF与PE混合的纤维层，其中纤维层平均孔径为100nm，孔隙率为50％，再通过电喷雾设备70将浆料F喷涂到该PVDF+PE纤维层表面，形成厚度为12μm的隔离层。
c)<双面涂布电极极片的制备>
在正极极片背面重复上述步骤a和b，然后在40℃条件下真空烘干去除DMF等分散剂，随后升高温度至80℃热处理6h(小时)以完成交联过程，即得到双面集成隔离层的正极极片，然后将正极极片裁切成规格为74mm×867mm的片材并焊接极耳待用。
各实施例和对比例的制备参数及测试结果如下表1和表2所示：
表1 实施例1-18及各对比例的测试参数以及相应的实验结果
Figure PCTCN2020134992-appb-000001
Figure PCTCN2020134992-appb-000002
表2 实施例19-21的测试参数以及相应的实验结果
Figure PCTCN2020134992-appb-000003
从实施例1-21和对比例1、2、4可以看出，具有本申请隔离层的锂离子电池，300次循环后锂离子电池变形率明显下降，表明本申请的锂离子电池在多次循环后具有更低的变形程度，因此具有更高的安全性。
从实施例1-21和对比例1-3可以看出，具有本申请隔离层的锂离子电池，02C放电后体积能量密度得到明显提升，表明本申请的锂离子电池具有很高的能量密度。
从实施例1-15、17-20和对比例1-4可以看出，具有本申请隔离层的锂离子电池，循环容量保持率得到提升，表明本申请的锂离子电池不仅具有优异的抗变形能力，还具有很长的使用寿命。
隔离层中无机颗粒的体积占比通常影响隔离层的强度；隔离层的厚度通常影响其强度和粘结性能；孔隙率通常影响隔离层的透气性能；聚合物纤维的纤维直径通常影响隔离层的强度；无机颗粒的平均粒径通常影响隔离层的粘结性能。通过实施例1-21可以看出，只要使上述条件在本申请范围内，使得锂离子电池中不同区域的界面间粘结力存在差异，具体地，使得锂离子电池的第一区域中隔离层与电极极片表面之间的粘结力大于第二区域中隔离层与电极极片表面之间的粘结力，使得第一区域的第一子区域中隔离层与电极极片表面之间的粘结力大于第二子区域中隔离层与电极极片表面之间的粘结力，进而使锂离子电池具有低的变形，就能实现本申请的发明目的。
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 (17)

  1. 一种卷绕式电极组件，其包括电极极片以及在所述电极极片的至少一个表面上的隔离层，所述卷绕式电极组件具有第一区域和第二区域，在所述第一区域内所述隔离层与电极极片表面之间的粘结力大于在所述第二区域内所述隔离层与电极极片表面之间的粘结力，所述第二区域为所述卷绕式电极组件的卷回区。
  2. 根据权利要求1所述的卷绕式电极组件，其中，所述第一区域中的隔离层与电极极片表面之间的粘结力F 1与所述第二区域中的隔离层与电极极片表面之间的粘结力F 2之差为1N/m至15N/m。
  3. 根据权利要求2所述的卷绕式电极组件，其中，所述第一区域中的隔离层与电极极片表面之间的粘结力F 1与所述第二区域中的隔离层与电极极片表面之间的粘结力F 2之差为5N/m至10N/m。
  4. 根据权利要求1所述的卷绕式电极组件，其中，所述第一区域内所述隔离层与电极极片表面之间的粘结力F 1为1N/m至30N/m。
  5. 根据权利要求4所述的卷绕式电极组件，其中，所述第一区域内所述隔离层与电极极片表面之间的粘结力F 1为10N/m至20N/m。
  6. 根据权利要求1所述的卷绕式电极组件，其中，所述第一区域包括第一子区域和第二子区域，所述第二子区域中的隔离层与电极极片之间的粘结力F 3大于所述第一子区域中的隔离层与电极极片之间的粘结力F 4，所述第一子区域为所述卷绕式电极组件的极耳区。
  7. 根据权利要求1所述的卷绕式电极组件，其中，所述隔离层中包含聚合物纤维，所述聚合物纤维中包括粘结剂，在所述第一区域内，所述聚合物纤维中粘结剂含量为5wt％至25wt％，在所述第二区域内，所述聚合物纤维中粘结剂含量为2wt％至20wt％。
  8. 根据权利要求7所述的卷绕式电极组件，其中，所述聚合物纤维中还包含无机填料，所述无机填料在所述聚合物纤维中的含量为5wt％至10wt％。
  9. 根据权利要求7所述的卷绕式电极组件，其中，所述隔离层中还包含无机颗粒，所述无机颗粒体积占所述隔离层中固体物质总体积不超过40％。
  10. 根据权利要求9所述的卷绕式电极组件，其中，所述无机颗粒中包括粘结剂，在所述第一区域内，所述无机颗粒中粘结剂含量为4wt％至7wt％，在所述第二区域内，所述无机颗粒中粘结剂含量为3wt％至15wt％。
  11. 根据权利要求1所述的卷绕式电极组件，其中，所述卷绕式电极组件的正极极耳和 负极极耳设置于所述第二区域。
  12. 根据权利要求7所述的卷绕式电极组件，其中，所述聚合物纤维包括聚偏氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯、聚偏氟乙烯-六氟丙烯或聚偏二氟乙烯-共-三氟氯乙烯或上述物质衍生物的纤维中的至少一种。
  13. 根据权利要求9所述的卷绕式电极组件，其中，所述无机颗粒的无机物包括氧化铪、钛酸锶、二氧化锡、氧化铯、氧化镁、氧化镍、氧化钙、氧化钡、氧化锌、氧化锆、氧化钇、氧化铝、氧化钛、二氧化硅、勃姆石、氢氧化镁、氢氧化铝、磷酸锂、锂钛磷酸盐、锂铝钛磷酸盐、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、氧化锂、氟化锂、氢氧化锂、碳酸锂、偏铝酸锂、锂锗磷硫陶瓷或石榴石陶瓷中的至少一种。
  14. 根据权利要求7所述的卷绕式电极组件，其中，所述粘结剂包括聚乙烯醇、聚四氟乙烯、丁苯橡胶、羧甲基纤维素钠、聚苯烯酸、聚丙烯酸丁酯、聚丙烯腈、聚氨酯或丙烯腈多元共聚物中的至少一种。
  15. 根据权利要求1所述的卷绕式电极组件，其中，所述卷绕式电极组件满足以下特征中的至少一者：
    (a)所述隔离层中的聚合物纤维的纤维直径为10nm至5μm；
    (b)所述隔离层的厚度为1μm至50μm；
    (c)所述隔离层中的无机颗粒的平均粒径为20nm至5μm；
    (d)所述隔离层中的无机颗粒体积占所述隔离层中固体物质总体积的15％至30％。
  16. 一种电化学装置，其包含权利要求1-15任一项所述的卷绕式电极组件。
  17. 一种电子装置，其包含权利要求16中所述的电化学装置。
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