WO2024192589A1 - 电化学装置和电子装置 - Google Patents

电化学装置和电子装置 Download PDF

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Publication number
WO2024192589A1
WO2024192589A1 PCT/CN2023/082320 CN2023082320W WO2024192589A1 WO 2024192589 A1 WO2024192589 A1 WO 2024192589A1 CN 2023082320 W CN2023082320 W CN 2023082320W WO 2024192589 A1 WO2024192589 A1 WO 2024192589A1
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Prior art keywords
isolation layer
fiber isolation
polyoxyethylene
fiber
electrochemical device
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PCT/CN2023/082320
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English (en)
French (fr)
Inventor
曾志鹏
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to PCT/CN2023/082320 priority Critical patent/WO2024192589A1/zh
Priority to CN202380013375.9A priority patent/CN118044048A/zh
Publication of WO2024192589A1 publication Critical patent/WO2024192589A1/zh
Anticipated expiration legal-status Critical
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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
    • 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
    • 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
    • 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 energy storage, and in particular to an electrochemical device and an electronic device.
  • Electrochemical devices such as lithium-ion batteries are widely used in the field of consumer electronics due to their large volume and mass energy density, long cycle life, high nominal voltage and low self-discharge rate.
  • the comprehensive performance requirements for lithium-ion batteries are becoming increasingly higher.
  • lithium-ion batteries reach their limits in terms of high energy density, more and more products begin to focus on safety and stability.
  • an electrochemical device in the first aspect of the present application.
  • the invention comprises a positive electrode, a negative electrode and a fiber isolation layer, wherein the friction coefficients of the fiber isolation layer in the longitudinal direction and the transverse direction are ⁇ MD and ⁇ TD respectively, wherein 0.1 ⁇ MD ⁇ 0.5, and 0.1 ⁇ TD ⁇ 0.5.
  • the fiber separation layer is arranged on at least one of the positive electrode and the negative electrode.
  • the fiber isolation layer has a thickness of 500 nm to 30 ⁇ m.
  • At least one of the following conditions is met:
  • the fiber isolation layer comprises polymer fibers, and the diameter of the polymer fibers is 100 nm to 1 ⁇ m;
  • the porosity of the fiber isolation layer is 20% to 80%, preferably 40% to 60%;
  • the pore size of the fiber isolation layer is 20 nm to 1 ⁇ m.
  • the fiber isolation layer includes an additive, wherein the content of the additive is 1 wt % to 10 wt % based on the total weight of the fiber isolation layer.
  • the additive includes at least one of an alkane compound, an ester compound and a polyether compound, and wherein the alkane compound is selected from liquid paraffin alkanes, cycloalkanes and mixtures thereof; the ester compound is selected from monoesters, diesters and polyesters prepared by condensation esterification, ester exchange and the like of various alcohols and higher fatty acids, and the ester compound includes fatty acid polyoxyethylene esters, polyethylene glycol laurate, stearic acid polyoxyethylene ester, polyethylene glycol stearate and sorbitan stearate, sorbitan stearic acid monoester, polyoxyethylene stearic acid xylitol ester, stearic acid polyoxyethylene ester or sorbitan oil ester; the polyether compound includes at least one of hydrogenated castor oil polyoxyethylene ether, polyoxyethylene fatty amine, alkyl polyoxyethylene ether sulfate, octyl poly
  • the additive also includes at least one of alkyl sulfonates, alkylphenol polyoxyethylene ether sulfates, polyethers, antistatic agents TM, alkyl phosphate diethanolamines, fatty alcohol polyoxyethylene ethers, polyoxyethylene xylitol monooleate, alkyl polyoxyethylene ether phosphate sodium salts, octanol polyoxyethylene ethers, soybean dimethyl hydroxyethyl quaternary ammonium ethyl sulfate, or octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate.
  • the fiber isolation layer has a spinning skeleton
  • the spinning skeleton includes at least one selected from the following: polyvinylidene fluoride (PVDF), polyimide (PI), polyamide, polyacrylonitrile, polyethylene glycol, polyacrylonitrile (PAN), polyethylene oxide (PEO), polyphenylene ether (PPO), polypropylene carbonate (PPC), polymethyl methacrylate (PMMA), polyethylene terephthalate, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), poly(vinylidene fluoride-co-chlorotrifluoroethylene) and its derivatives; preferably, the spinning skeleton includes at least one selected from the following: polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polyimide (PI), polyacrylonitrile (PAN), polymethyl me
  • the fiber isolation layer preferably has a thickness of 5 ⁇ m to 10 ⁇ m.
  • the present application provides an electronic device, which includes the electrochemical device according to the first aspect of the present application.
  • FIG2 schematically shows a schematic diagram of an electrode structure of an electrochemical device according to the present application
  • FIG3 schematically shows a schematic diagram of an electrode structure of an electrochemical device according to the present application
  • FIG5 schematically shows a schematic diagram of an electrode structure of an electrochemical device according to the present application.
  • FIG6 schematically shows a schematic diagram of an electrode structure of an electrochemical device according to the present application.
  • FIG7 schematically shows a schematic diagram of preparing a fiber isolation layer by connecting multiple spinning units in series
  • FIG8 schematically shows a schematic diagram of a fiber isolation layer according to the present application.
  • FIG9 a schematically shows a SEM diagram of the surface of a conventional spinning layer
  • FIG9 b schematically shows a SEM diagram of the surface of a fiber isolation layer according to the present application.
  • FIG10 a schematically shows an optical image of a conventional spinning layer surface
  • FIG. 10 b schematically shows an optical image of a spun layer according to the present application.
  • Reference numerals list 1 fluid collector 2Conductive coating 3 Active Materials 4 fiber isolation layer 5 Ceramic Layer 21Positive electrode current collector 22 Positive electrode conductive coating 23 Positive electrode active material layer 31 negative electrode current collector 32 Negative electrode conductive coating 33 Negative electrode active material layer
  • the present application provides an electrochemical device, which includes a positive electrode, a negative electrode and a fiber separator.
  • the negative electrode includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, and the positive electrode includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer substrate.
  • the positive electrode active material includes at least one of lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminum oxide, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel lithium manganese oxide, spinel lithium nickel manganese oxide, and lithium titanate.
  • the positive electrode active material layer further includes a binder, which includes but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin or nylon, etc.
  • the binder improves the bonding between the positive electrode active material particles and also improves the bonding between the positive electrode active material and the current collector.
  • the positive electrode active material layer further comprises a conductive agent, which includes, but is not limited to: a carbon-based material, a metal-based material, a conductive polymer, and a mixture thereof.
  • a conductive agent which includes, but is not limited to: a carbon-based material, a metal-based material, a conductive polymer, and a mixture thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver.
  • the conductive polymer is a polyphenylene derivative.
  • the negative electrode active material may include a material that reversibly intercalates/deintercalates lithium ions, lithium metal, lithium metal alloy, a material capable of doping/dedoping lithium, or a transition metal oxide, such as Si, SiO x (0 ⁇ x ⁇ 2), and the like.
  • the material that reversibly intercalates/deintercalates lithium ions may be a carbon material.
  • the carbon material may be any carbon-based negative electrode active material commonly used in lithium ion rechargeable electrochemical devices. Examples of carbon materials include crystalline carbon, amorphous carbon, and combinations thereof. Crystalline carbon can be amorphous or plate-shaped, flake-shaped, spherical or fiber-shaped natural graphite or artificial graphite.
  • Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonization product, fired coke etc.
  • Low crystalline carbon and high crystalline carbon can all be used as carbon material.
  • soft carbon and hard carbon can be generally included.
  • high crystalline carbon material natural graphite, crystalline graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase carbon microbead, mesophase pitch and high temperature calcined charcoal (such as petroleum or coke derived from coal tar pitch) can be generally included.
  • the negative electrode active material layer also includes a binder, which includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon, etc.
  • a binder which includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene
  • the negative electrode active material layer further comprises a conductive agent, which includes, but is not limited to: a carbon-based material, a metal-based material, a conductive polymer, and a mixture thereof.
  • a conductive agent which includes, but is not limited to: a carbon-based material, a metal-based material, a conductive polymer, and a mixture thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver.
  • the conductive polymer is a polyphenylene derivative.
  • the fiber isolation layer of the present application is arranged on the surface of the active material layer opposite to the current collector. As shown in FIG. 1 , the active material layer and the fiber isolation layer are sequentially arranged on the current collector.
  • the fiber separation layer of the present application is arranged on the surface of the active material layer opposite to the current collector, and the fiber separation layer is arranged between the positive electrode active material layer and the negative electrode active material layer, as shown in FIG. 2 .
  • a conductive coating may be arranged between the current collector and the active material layer, wherein the conductive coating includes one or more of conductive agents such as carbon fiber, Ketjen black, acetylene black, carbon nanotubes, and graphene. As shown in FIG3 , the conductive coating, the active material layer, and the fiber isolation layer are sequentially arranged on the positive electrode current collector.
  • the electrode structure is realized by stacking a positive electrode current collector, a positive electrode conductive coating, a positive electrode active material layer, a fiber isolation layer, a negative electrode active material layer, a negative electrode active coating and a negative electrode current collector in sequence, wherein there is a fiber isolation layer in the electrode device, and the fiber isolation layer is arranged between the positive electrode active material layer and the negative electrode active material layer.
  • the electrochemical device may further include a ceramic layer, which is arranged on a side of the fiber isolation layer away from the active material layer. As shown in FIG5 , the conductive coating, the active material layer , the fiber isolation layer and the ceramic layer are sequentially arranged on the current collector.
  • the ceramic layer includes an inorganic material
  • the inorganic material includes an inorganic oxide material, such as HfO2 , SrTiO3 , SnO2 , CeO2 , MgO, NiO , CaO, BaO, ZnO , ZrO2 , Y2O3 , Al2O3 , TiO2 , SiO2 , boehmite, magnesium hydroxide, aluminum hydroxide;
  • the inorganic material can also be a material having the ability to conduct lithium ions, such as lithium phosphate ( Li3PO4 ), lithium titanium phosphate ( LixTiy ( PO4 ) 3 , wherein 0 ⁇ x ⁇ 2 and 0 ⁇ y ⁇ 3), lithium aluminum titanium phosphate ( LixAlyTiz ( PO4 ) 3 , wherein 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 1, and 0 ⁇ z ⁇ 3), Li1 +x+y (Al,Ga)x(Ti, Ge ) 2- x
  • a positive electrode fiber isolation layer is arranged on the surface of the positive electrode active material layer opposite to the positive electrode current collector, and a negative electrode fiber isolation layer is arranged on the surface of the negative electrode active material layer opposite to the negative electrode current collector, wherein the positive electrode fiber isolation layer and the negative electrode fiber isolation layer may contain the same or different additives.
  • the fiber isolation layer arranged on the positive electrode and the fiber isolation layer arranged on the negative electrode contain different additives, wherein the positive electrode fiber isolation layer contains high voltage additives and positive electrode film-forming additives, and/or the negative electrode fiber isolation layer contains SEI film-forming additives and flame retardant additives.
  • the fiber isolation layer includes an additive, wherein the content of the additive is 1 wt % to 10 wt % based on the total weight of the fiber isolation layer.
  • the additive in the fiber isolation layer includes a smoothing agent
  • the smoothing agent includes at least one of an alkane compound, an ester compound and a polyether compound, and wherein the alkane compound is selected from liquid paraffin alkanes, cycloalkanes and mixtures thereof; the ester compound is selected from monoesters, diesters and polyesters prepared by condensation esterification, ester exchange and the like of various alcohols and higher fatty acids, and the ester compound is, for example, fatty acid polyoxyethylene ester, polyethylene glycol ester, etc.
  • Lauric acid ester polyoxyethylene stearate, polyethylene glycol stearate and sorbitan stearate, sorbitan stearate monoester, polyoxyethylene stearate xylitol ester, polyoxyethylene stearate and sorbitan oil ester;
  • the polyether compound is selected from hydrogenated castor oil polyoxyethylene ether, polyoxyethylene fatty amine, alkyl polyoxyethylene ether sulfate, octyl polyoxyethylene ether, fatty alcohol polyoxyethylene, distearylamide triethylamino propylene oxide quaternary ammonium chloride, and sorbitan stearate polyoxyethylene ether.
  • fatty acid polyoxyethylene ester or fatty acid ester is a dual-functional oil component, which has both antistatic function and the performance of improving the static friction coefficient of the fiber, so that the fiber has good bundling properties.
  • the diester can effectively reduce the friction coefficient between the fibers. Number, so that the fiber has good smoothness.
  • the additive also includes an antistatic agent
  • the antistatic agent includes at least one selected from the following: alkyl sulfonate, alkylphenol polyoxyethylene ether sulfate, polyether, antistatic agent TM, alkyl phosphate diethanolamine, fatty alcohol polyoxyethylene ether, polyoxyethylene xylitol monooleate, alkyl polyoxyethylene ether phosphate sodium salt, octyl alkylphenol polyoxyethylene ether, soybean dimethyl hydroxyethyl quaternary ammonium ethyl sulfate and octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate.
  • the antistatic agent is selected from alkyl phosphate, alkyl ether phosphate and alkyl sulfate. According to some particularly preferred embodiments of the present application, the antistatic agent is a mixture of monoesters and diesters.
  • the effective functional group in the antistatic agent has a strong polarity and can be combined with moisture in the air to ionize, so that the charge can be quickly removed from the fiber surface, and it is difficult to generate static electricity accumulation.
  • the electrode structure is realized by stacking a positive electrode current collector, a positive electrode conductive coating, a positive electrode active material layer, a positive electrode fiber isolation layer, a ceramic layer, a negative electrode active material layer, a negative electrode active coating and a negative electrode current collector in sequence, wherein, by adding different additives to the positive electrode fiber isolation layer and the negative electrode fiber isolation layer, for example, adding a high voltage additive and a positive electrode film-forming additive to the positive electrode fiber isolation layer and adding an SEI film-forming additive and a flame retardant additive to the negative electrode fiber isolation layer, the positive electrode can obtain enhanced high voltage stability and high temperature/low temperature resistance, and the negative electrode can obtain enhanced film-forming density stability and flame retardant properties.
  • the fiber isolation layer is preferably formed on the active material layer by an electrospinning process using a spinning solution.
  • the spinning solution contains additives, and the additives include a smoothing agent and an optional antistatic agent.
  • the positive electrode spinning solution used to form the positive electrode fiber isolation layer preferably contains additives different from the negative electrode spinning solution used to form the negative electrode fiber isolation layer.
  • the fiber isolation layer includes polymer fibers, and the diameter of the polymer fibers is 100 nm to 1 ⁇ m.
  • the fiber isolation layer has a spinning skeleton
  • the spinning skeleton includes at least one selected from the following: polyvinylidene fluoride (PVDF), polyimide (PI), polyamide, polyacrylonitrile, polyethylene glycol, polyacrylonitrile (PAN), polyethylene oxide (PEO), polyphenylene ether (PPO), polypropylene carbonate (PPC), polymethyl methacrylate (PMMA), polyethylene terephthalate, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), poly(vinylidene fluoride-co-chlorotrifluoroethylene) and its derivatives; preferably, the spinning skeleton includes at least one selected from the following: polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene fluor
  • the spinning main body skeleton further comprises an inorganic material
  • the inorganic material comprises an inorganic oxide material, such as HfO2 , SrTiO3 , SnO2, CeO2 , MgO, NiO, CaO, BaO, ZnO, ZrO2 , Y2O3 , Al2O3 , TiO2 , SiO2 , boehmite , magnesium hydroxide , aluminum hydroxide
  • the inorganic material can also be a material having the ability to conduct lithium ions, such as lithium phosphate ( Li3PO4 ), lithium titanium phosphate ( LixTiy ( PO4 ) 3 , wherein 0 ⁇ x ⁇ 2 and 0 ⁇ y ⁇ 3), lithium aluminum titanium phosphate ( LixAlyTiz ( PO4 ) 3 , wherein 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 1, and 0 ⁇ z ⁇ 3), Li1 +x+y (Al,Ga)x(
  • the fiber isolation layer has a thickness of 500 nm to 30 ⁇ m, preferably 5 ⁇ m to 10 ⁇ m.
  • FIG8 shows a schematic diagram of the structure of the fiber isolation layer according to the present application.
  • the friction coefficients of the fiber isolation layer according to the present application in the longitudinal direction and the transverse direction are ⁇ MD and ⁇ TD respectively, wherein 0.1 ⁇ MD ⁇ 0.5, and 0.1 ⁇ TD ⁇ 0.5, wherein ⁇ MD is the friction coefficient in the longitudinal direction and ⁇ TD is the friction coefficient in the transverse direction.
  • the friction coefficient of the fiber isolation layer When the friction coefficient of the fiber isolation layer is greater than 0.5, the fiber isolation layer rubs against the equipment to generate static electricity, causing the fiber morphology structure to be destroyed, wrinkles, flying silk, and poor needle pulling, and the large electrostatic adsorption capacity also causes the fiber isolation layer to adsorb powder particles floating in the environment, thereby causing particle puncture and short circuit; when the friction coefficient of the fiber isolation layer is less than 0.1, it is easy to cause misalignment between the layers inside the core due to too little friction, and ultimately cause defects such as uneven winding end faces and core spirals.
  • the additive changes the surface morphology of the fiber and reduces the friction coefficient. Furthermore, since the fiber isolation layer has a smaller friction coefficient and a smoother surface, the fiber isolation layer according to the present application is not prone to wrinkles and flying threads, thereby achieving a better needle pulling effect. At the same time, the fiber isolation layer according to the present application is not easy to stick to the roller or absorb foreign particles, which effectively alleviates the short circuit of the isolation layer caused by electrostatic adsorption of dust.
  • Figures 9a and 9b show SEM images of a conventional spun fiber layer and a fiber isolation layer containing additives according to the present application.
  • the fiber isolation layer according to the present application has fibers with uniform wire diameters and excellent porosity.
  • the porosity of the fiber isolation layer of the present application is 20% to 80%, preferably 40% to 60%.
  • the porosity of the fiber isolation layer is lower than 20%, the excessively small porosity may cause ion transmission pathways to be blocked, thereby hindering the positive transfer of the battery cell.
  • the porosity of the fiber isolation layer is higher than 80%, excessive porosity can lead to unstable structure and degraded mechanical strength, which cannot resist the puncture of particles on the surface of the pole piece. Therefore, excessive porosity may cause local short circuit and cause battery performance degradation and severe self-discharge.
  • the pore size of the fiber isolation layer is 20nm to 1 ⁇ m.
  • the too small pore size may lead to insufficient ion transmission pathways, hindering the normal circulation of the battery cell.
  • the pore size of the fiber isolation layer is greater than 1 ⁇ m, the excessively large pore size may lead to a decrease in mechanical strength at the position of the pore, thereby being unable to resist the puncture of particles on the surface of the pole piece. Therefore, an excessively large pore size may cause a local short circuit and cause battery performance degradation and severe self-discharge.
  • Figures 10a and 10b show optical photographs of the surface of a conventional spun fiber layer and the surface of a fiber isolation layer containing additives according to the present application. Electrostatically adsorbed foreign particles are circled in Figure 10a. By comparing Figures 10a and 10b, it can be seen that the fiber isolation layer containing additives according to the present application avoids undesirable phenomena such as fiber flying, wrinkles, and foreign particle adsorption that often occur in conventional spun fiber layers.
  • the electrochemical device of the present application does not include a separator in the usual sense, such as a separator including a substrate layer and a surface treatment layer. Therefore, the electrochemical device of the present application does not include a conventional separator, such as a polyethylene separator and a polypropylene separator.
  • the electrochemical device of the present application also includes an electrolyte.
  • the electrolyte that can be used in the present application can be an electrolyte known in the prior art.
  • the electrolyte includes an organic solvent, a lithium salt and an optional additive.
  • the organic solvent in the electrolyte of the present application may be any organic solvent known in the prior art that can be used as a solvent for the electrolyte.
  • the electrolyte used in the electrolyte according to the present application is not limited, and it can be any electrolyte known in the prior art.
  • the additive of the electrolyte according to the present application may be any additive known in the prior art that can be used as an electrolyte additive.
  • the organic solvent includes, but is not limited to: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate.
  • the organic solvent includes an ether solvent, for example, including at least one of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME).
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • the lithium salt includes, but is not limited to, lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium bis(trifluoromethanesulfonyl)imide LiN(CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bis(oxalatoborate) LiB(C 2 O 4 ) 2 (LiBOB), or lithium di(oxalatoborate) LiBF 2 (C 2 O 4 )(LiDFOB).
  • the additive includes at least one of fluoroethylene carbonate and adiponitrile.
  • the electrochemical device of the present application includes, but is not limited to: a lithium ion battery or a sodium ion battery. In some embodiments, the electrochemical device is a lithium ion battery.
  • the present application further provides an electronic device, which includes the electrochemical device described in the first aspect of the present application.
  • the electronic device or device of the present application is not particularly limited.
  • the electronic device of the present application includes, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.
  • the preparation of positive electrode sheets involves the coating of positive electrode active materials and the coating of fiber isolation layers.
  • the positive electrode active material lithium cobalt oxide (molecular formula LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed at a weight ratio of 97.5:1.0:1.5, and an appropriate amount of N-methylpyrrolidone (NMP) is added as a solvent and stirred to prepare a positive electrode slurry with a solid content of 0.75. After stirring evenly, the positive electrode slurry is coated on a current collector aluminum foil, dried at 90° C., and the positive electrode sheet is cut into a specification of 38 mm ⁇ 58 mm for standby use;
  • a DMF (dimethylformamide) solution of PVDF is used as a spinning solution, and an additive is added to the spinning solution, wherein the additive is a smoothing agent fatty acid polyoxyethylene ester.
  • the additive is a smoothing agent fatty acid polyoxyethylene ester.
  • a fiber isolation layer with a thickness of 30 ⁇ m is formed on one side of the positive electrode plate by electrospinning on the surface of the positive electrode plate.
  • the fiber isolation layer has an average pore size of 150 nm and a porosity of 60%, wherein the concentration of the additive is 1 wt % based on the total weight of the fiber isolation layer. Then, these steps are completed on the other side of the positive electrode plate in the same manner, and dried at 90°C to obtain a double-sided spinning-coated positive electrode plate.
  • the negative electrode active material graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) were mixed in a weight ratio of 96:1.5:2.5, and deionized water ( H2O ) was added as a solvent to prepare a negative electrode slurry with a solid content of 0.7. After stirring evenly, the negative electrode slurry was coated on a single side of a copper foil current collector, dried at 110°C, and the electrode sheet was cut into a size of 41mm ⁇ 61mm for standby use.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the positive electrode sheet and the negative electrode sheet prepared according to Example 1 are stacked in sequence, the four corners of the entire stacked structure are fixed with tape and placed in an aluminum-plastic film, and after top and side sealing, liquid injection and packaging, a lithium-ion battery is obtained.
  • Examples 2-10 were carried out in substantially the same manner as Example 1, except that different additives and additive concentrations were used according to Table 1.
  • Examples 11-16 were carried out in substantially the same manner as Example 1, except that a DMF (dimethylformamide) solution of PI (polyimide) was used as a spinning solution in step (2) of preparing the positive electrode sheet, and different additives and additive concentrations were used according to Table 2.
  • a DMF (dimethylformamide) solution of PI polyimide
  • Comparative Example 1 was carried out in substantially the same manner as Example 1, except that no additive was added to the PVDF spinning solution.
  • Comparative Example 2 was carried out in substantially the same manner as Example 11, except that no additive was added to the PI spinning solution.
  • the friction coefficient of the diaphragm was measured in the MD and TD directions respectively. Each sample was tested ten times and the average value was taken.
  • the mass of the sample holding block is 100g to 500g, the test speed is 50mm/min to 250mm/min, the temperature is 10°C to 40°C, and the humidity is 20%RH to 70%RH.

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Abstract

本申请提供了一种电化学装置，该电化学装置包括正极、负极和纤维隔离层，所述纤维隔离层在纵向方向和横向方向的摩擦系数分别为εMD和εTD，其中，0.1＜εMD＜0.5，且0.1＜εTD＜0.5。本申请还提供了一种电子装置，该电子装置包括根据本申请所述的电化学装置。

Description

电化学装置和电子装置 技术领域
本申请涉及储能领域，具体涉及一种电化学装置和电子装置。
背景技术
电化学装置如锂离子电池由于其较大的体积和质量能量密度、较长的循环寿命、较高的标称电压和较低的自放电率而在消费电子领域具有广泛的应用。然而，随着近年来清洁能源的大力发展，如电动汽车、移动电子设备、家庭式智能及储能系统的兴起，对锂离子电池的综合性能要求也越来越高。而当锂离子电池在高能量密度的方面达到极限，越来越多的产品开始关注于安全性和稳定性的发挥。
随着用电器具的快速发展，人们对提供动力的锂电池的稳定性和安全性提出了更高的要求。静电纺丝隔膜由于其具有较高的孔隙率和优异的热尺寸稳定性而被认为是最具潜力的下一代功能隔膜。然而静电纺丝中利用的聚合物纤维多为介电常数高的聚合物，形成的纤维层具有较高的比表面积，造成该纤维层容易与基材、传送辊等设备发生摩擦并产生静电。因此，现有技术中的静电纤维层容易黏附于机台设备上，例如传送辊、卷针等，造成纤维形貌结构被破坏，以及褶皱、飞丝、拔针不良等不期望的现象。此外，较大的静电吸附特性，还使得纤维极易吸附漂浮于环境中的粉末颗粒，并引入卷芯中，进而引发颗粒穿刺导致的短路。此类问题严重影响了锂电池的性能，并且由于在使用过程中可能发生内短路而存在一定的安全隐患。
因此，改善纤维表面的粗糙程度，是纤维隔膜的应用中亟待解决的问题。然而，表面粗糙度不够的隔膜，由于隔膜表面相对光滑，在传送和收放卷，拔针等过程中，又会出现卷芯内部层与层之间发生错位，并最终导致卷绕端面不整齐，卷芯螺旋等缺陷。为了解决上述问题，在隔膜的选择和改性过程中，需要对表面的摩擦系数进行一定范围的限定，以获得最优的结果。
发明内容
针对现有技术的不足，在本申请的第一方面提供了一种电化学装置，该电化学装置包 括正极、负极和纤维隔离层，所述纤维隔离层在纵向方向和横向方向的摩擦系数分别为εMD和εTD，其中，0.1＜εMD＜0.5，且0.1＜εTD＜0.5。
根据本申请的一些实施方式，所述纤维隔离层布置在正极和负极中的至少一者上。
根据本申请的一些实施方式，所述纤维隔离层厚度为500nm至30μm。
根据本申请的一些实施方式，满足以下条件中至少一者：
(i)所述纤维隔离层中包括聚合物纤维，且所述聚合物纤维的直径为100nm至1μm；
(ii)所述纤维隔离层的孔隙率为20％至80％，优选40％至60％；
(iii)所述纤维隔离层的孔径为20nm至1μm。
根据本申请的一些实施方式，所述纤维隔离层包括添加剂，其中，基于所述纤维隔离层的总重量计，所述添加剂的含量为1重量％至10重量％。
根据本申请的一些实施方式，所述添加剂包括烷烃类化合物，酯类化合物和聚醚类化合物中的至少一种，并且其中，所述烷烃类化合物选自液体石蜡烷烃、环烷烃及其混合物；所述酯类化合物选自由各种醇类与高级脂肪酸通过缩合酯化，酯交换等途径制备而成的单酯、双酯以及多酯，所述酯类化合物包括脂肪酸聚氧乙烯酯、聚乙二醇月桂酸酯，硬脂酸聚氧乙烯酯、聚乙二醇硬脂酸酯和山梨糖醇酐硬脂酸酯，山梨糖醇酐硬脂酸单酯、聚氧乙烯硬脂酸木糖醇酯，硬脂酸聚氧乙烯酯或山梨糖醇酐油脂酯中的至少一种；所述聚醚类化合物包括氢化蓖麻油聚氧乙烯醚、聚氧乙烯脂肪胺、烷基聚氧乙烯醚硫酸酯盐、辛烷基聚氧乙烯醚、脂肪醇聚氧乙烯，二硬脂酰胺三乙胺基环氧丙烷季铵氯化物、和山梨糖醇酐硬脂酸酯聚氧乙烯醚中的至少一种。
根据本申请的一些实施方式，所述添加剂还包括烷基磺酸盐、烷基酚聚氧乙烯醚硫酸酯盐、聚醚、抗静电剂TM、烷基磷酸酯二乙醇胺、脂肪醇聚氧乙烯醚、聚氧乙烯木糖醇单油酸酯、烷基聚氧乙烯醚磷酸酯钠盐、辛烷基酚聚氧乙烯醚、大豆二甲基羟乙基季铵乙基硫酸盐或十八烷基二甲基羟乙基季铵硝酸盐中的至少一种。
根据本申请的一些实施方式，所述纤维隔离层具有纺丝骨架，所述纺丝骨架包括选自以下的至少一种：聚偏二氟乙烯(PVDF)、聚酰亚胺(PI)、聚酰胺、聚丙烯腈、聚乙二醇、聚丙烯腈(PAN)、聚氧化乙烯(PEO)、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)、聚甲基丙烯酸甲酯(PMMA)、聚对苯二甲酸乙二醇酯、聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚(偏二氟乙烯-共-三氟氯乙烯)及其衍生物；优选所述纺丝骨架包括选自以下的至少一种：聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚偏二氟乙烯(PVDF)、聚酰亚胺(PI)、聚丙烯腈(PAN)、聚甲基丙烯酸甲酯(PMMA)、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)、聚氧化乙烯(PEO)及其衍生物。
根据本申请的一些实施方式，所述纤维隔离层优选厚度为5μm至10μm。
在第二方面，本申请提供了一种电子装置，其包括根据本申请第一方面所述的电化学装置。
附图简述
图1示意性示出了根据本申请的电化学装置的电极结构的示意图；
图2示意性示出了根据本申请的电化学装置的电极结构的示意图；
图3示意性示出了根据本申请的电化学装置的电极结构的示意图；
图4示意性示出了根据本申请的电化学装置的电极结构的示意图；
图5示意性示出了根据本申请的电化学装置的电极结构的示意图；
图6示意性示出了根据本申请的电化学装置的电极结构的示意图；
图7示意性示出了多纺丝单元串联制备纤维隔离层的示意图；
图8示意性示出了根据本申请的纤维隔离层的示意图；
图9a示意性示出了常规纺丝层表面的SEM示意图；
图9b示意性示出了根据本申请的纤维隔离层表面的SEM示意图；
图10a示意性示出了常规纺丝层表面的光学图像；
图10b示意性示出了根据本申请的纺丝层的光学图像。
附图标记列表
1集流体
2导电涂层
3活性材料
4纤维隔离层
5陶瓷层
21正极集流体
22正极导电涂层
23正极活性材料层
31负极集流体
32负极导电涂层
33负极活性材料层
具体实施方式
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。
一、电化学装置
在第一方面，本申请提供一种电化学装置，其包括正极、负极和纤维隔离层。负极包括负极集流体和负极活性材料层，负极活性材料层包括负极活性材料，并且，正极包括正极集流体和正极活性材料层，正极活性材料层包括正极活性材料。
在一些实施例中，正极集流体可以采用金属箔片或复合集流体。例如，可以使用铝箔。复合集流体可以通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子基材上而形成。
在一些实施例中，正极活性材料包括钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂和钛酸锂中的至少一种。
在一些实施例中，正极活性材料层还包括粘合剂，粘合剂包括但不限于：聚乙烯醇、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、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙等。粘合剂提高正极活性材料颗粒彼此间的结合，并且还提高正极活性材料与集流体的结合。
在一些实施例中，正极活性材料层还包括导电剂，导电剂包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝或银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在一些实施例中，负极集流体可以采用金属箔片或复合集流体，例如铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、覆有导电金属的聚合物基底或其任意组合。
在一些实施例中，负极活性材料可以包括可逆地嵌入/脱嵌锂离子的材料、锂金属、锂金属合金、能够掺杂/脱掺杂锂的材料或过渡金属氧化物，例如Si、SiOx(0<x<2)等材料。可逆地嵌入/脱嵌锂离子的材料可以是碳材料。碳材料可以是在锂离子可再充电电化学装置中通常使用的任何碳基负极活性材料。碳材料的示例包括结晶碳、非晶碳和它们的组合。 结晶碳可以是无定形的或板形的、小片形的、球形的或纤维形的天然石墨或人造石墨。非晶碳可以是软碳、硬碳、中间相沥青碳化产物、烧制焦炭等。低结晶碳和高结晶碳均可以用作碳材料。作为低结晶碳材料，可通常包括软碳和硬碳。作为高结晶碳材料，可通常包括天然石墨、结晶石墨、热解碳、中间相沥青基碳纤维、中间相碳微珠、中间相沥青和高温锻烧炭(如石油或衍生自煤焦油沥青的焦炭)。
在一些实施例中，负极活性材料层还包括粘结剂，粘结剂包括，但不限于：聚乙烯醇、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、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙等。
在一些实施例中，负极活性材料层还包括导电剂，导电剂包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝或银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
根据本申请的一些实施方式，本申请的纤维隔离层布置在活性材料层的与集流体相反的表面上，如图1中示出的，活性材料层和纤维隔离层依次布置在集流体上。
根据本申请的一些实施方式，本申请的纤维隔离层布置在活性材料层的与集流体相反的表面上，并且该纤维隔离层布置在正极活性材料层和负极活性材料层之间，如图2中示出的。
根据本申请的一些实施方式，还可以在集流体和活性材料层之间布置导电涂层，所述导电涂层包括碳纤维、科琴黑、乙炔黑、碳纳米管和石墨烯等导电剂中的一者或多者。如在图3中示出的，导电涂层、活性材料层和纤维隔离层依次布置在正极集流体上。
根据本申请的一些实施方式，如在图4中示出的，电极结构通过依次叠放正极集流体、正极导电涂层、正极活性材料层、纤维隔离层、负极活性材料层、负极活性涂层和负极集流体来实现，其中，电极装置中存在一个纤维隔离层，且该纤维隔离层布置在正极活性材料层和负极活性材料层之间。
根据本申请的一些实施方式，电化学装置还可以包括陶瓷层，所述陶瓷层布置在纤维隔离层的远离活性材料层的一侧，如图5中示出的，导电涂层、活性材料层、纤维隔离层和陶瓷层依次布置在集流体上。陶瓷层包括无机材料，所述无机材料包括无机氧化物材料，例如HfO2、SrTiO3、SnO2、CeO2、MgO、NiO、CaO、BaO、ZnO、ZrO2、Y2O3、Al2O3、 TiO2、SiO2、勃姆石，氢氧化镁、氢氧化铝；所述无机材料还可以是具有导锂离子能力的材料，如磷酸锂(Li3PO4)、锂钛磷酸盐(LixTiy(PO4)3，其中0<x<2且0<y<3)、锂铝钛磷酸盐(LixAlyTiz(PO4)3，其中0<x<2，0<y<1，且0<z<3)、其中0≤x≤1且0≤y≤1的Li1+x+y(Al,Ga)x(Ti,Ge)2-xSiyP3-yO12、锂镧钛酸盐(LixLayTiO3，其中0<x<2且0<y<3)、锂锗硫代磷酸盐(LixGeyPzSw，其中0<x<4，0<y<1，0<z<1，且0<w<5)、锂氮化物(LixNy，其中0<x<4，0<y<2)、SiS2玻璃(LixSiySz，其中0≤x<3，0<y<2，且0<z<4)、P2S5玻璃(LixPySz，其中0≤x<3，0<y<3，且0<z<7)、Li2O、LiF、LiOH、Li2CO3、LiAlO2、Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2陶瓷、和石榴石陶瓷(Li3+xLa3M2O12，其中0≤x≤5，且M is Te、Nb、或Zr)中的一种或几种。
根据本申请的一些实施方式，在正极活性材料层的与正极集流体相反的表面上布置有正极纤维隔离层，且在负极活性材料层的与负极集流体相反的表面上布置有负极纤维隔离层，其中，正极纤维隔离层和负极纤维隔离层可以包含相同或不同的添加剂。
根据本申请的一个优选实施方式，布置在正极上的纤维隔离层和布置在负极上的纤维隔离层含有不同的添加剂，其中，正极纤维隔离层中包含高电压添加剂和正极成膜添加剂，和/或负极纤维隔离层中包含SEI成膜添加剂和阻燃添加剂。
根据本申请的一些实施方式，所述纤维隔离层包括添加剂，其中，基于所述纤维隔离层的总重量计，所述添加剂的含量为1重量％至10重量％。
根据本申请的一些实施方式，纤维隔离层中的添加剂包括平滑剂，所述平滑剂包括烷烃类化合物，酯类化合物和聚醚类化合物中的至少一种，并且其中，所述烷烃类化合物选自液体石蜡烷烃、环烷烃及其混合物；所述酯类化合物选自由各种醇类与高级脂肪酸通过缩合酯化，酯交换等途径制备而成的单酯、双酯以及多酯，所述酯类化合物例如是脂肪酸聚氧乙烯酯、聚乙二醇月桂酸酯，硬脂酸聚氧乙烯酯、聚乙二醇硬脂酸酯和山梨糖醇酐硬脂酸酯，山梨糖醇酐硬脂酸单酯、聚氧乙烯硬脂酸木糖醇酯，硬脂酸聚氧乙烯酯和山梨糖醇酐油脂酯；所述聚醚类化合物选自氢化蓖麻油聚氧乙烯醚、聚氧乙烯脂肪胺、烷基聚氧乙烯醚硫酸酯盐、辛烷基聚氧乙烯醚、脂肪醇聚氧乙烯，二硬脂酰胺三乙胺基环氧丙烷季铵氯化物、和山梨糖醇酐硬脂酸酯聚氧乙烯醚。
通过在纤维隔离层中加入添加剂，可以降低纤维隔离层的摩擦系数，特别地，脂肪酸聚氧乙烯酯或脂肪酸酯是具有双功能的油剂组分，其既有抗静电功能，又有提高纤维静摩擦系数的性能，可以使纤维具有好的集束性，同时，双酯可以有效降低纤维之间的摩擦系 数，使纤维获得良好的平滑性。
根据本申请的一些实施方式，所述添加剂还包括抗静电剂，所述抗静电剂包括选自以下的至少一者：烷基磺酸盐、烷基酚聚氧乙烯醚硫酸酯盐、聚醚、抗静电剂TM、烷基磷酸酯二乙醇胺、脂肪醇聚氧乙烯醚、聚氧乙烯木糖醇单油酸酯、烷基聚氧乙烯醚磷酸酯钠盐、辛烷基酚聚氧乙烯醚、大豆二甲基羟乙基季铵乙基硫酸盐和十八烷基二甲基羟乙基季铵硝酸盐。根据本申请的一些优选实施方式，所述抗静电剂选自烷基磷酸酯盐、烷基醚磷酸酯盐和烷基硫酸酯盐，根据本申请的一些特别优选的实施方式，所述抗静电剂是单酯和双酯的混合物。抗静电剂中的有效官能团极性较强，可以与空气中的水分结合，发生电离，使电荷能够很快的从纤维表面移走，难于产生静电积累。
根据本申请的一些实施方式，如在图6中示出的，电极结构通过依次叠放正极集流体、正极导电涂层、正极活性材料层、正极纤维隔离层、陶瓷层、负极活性材料层、负极活性涂层和负极集流体来实现，其中，通过在正极纤维隔离层和负极纤维隔离层添加不同的添加剂，例如在正极纤维隔离层中添加高电压添加剂和正极成膜添加剂并在负极纤维隔离层中添加SEI成膜添加剂和阻燃添加剂，可以使正极获得增强的高电压稳定性和耐高温/耐低温性能，并且使负极获得增强的成膜致密稳定性和阻燃特性。
根据本申请的一些实施方式，如图7所示，纤维隔离层通过静电纺丝工艺使用纺丝溶液优选在活性材料层上形成纤维隔离层，根据本申请的纺丝溶液中含有添加剂，所述添加剂包括平滑剂、可选的抗静电剂，优选用于形成正极纤维隔离层的正极纺丝溶液含有与用于形成负极纤维隔离层的负极纺丝溶液不同的添加剂。
根据本申请的一些实施方式，所述纤维隔离层中包括聚合物纤维，且所述聚合物纤维的直径为100nm至1μm。
根据本申请的一些实施方式，所述纤维隔离层具有纺丝骨架，所述纺丝骨架包括选自以下的至少一种：聚偏二氟乙烯(PVDF)、聚酰亚胺(PI)、聚酰胺、聚丙烯腈、聚乙二醇、聚丙烯腈(PAN)、聚氧化乙烯(PEO)、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)、聚甲基丙烯酸甲酯(PMMA)、聚对苯二甲酸乙二醇酯、聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚(偏二氟乙烯-共-三氟氯乙烯)及其衍生物；优选所述纺丝骨架包括选自以下的至少一种：聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚偏二氟乙烯(PVDF)、聚丙烯腈(PAN)、聚甲基丙烯酸甲酯(PMMA)、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)、聚氧化乙烯(PEO)及其衍生物。
根据本申请的一些实施方式，所述纺丝主体骨架还包括无机材料，所述无机材料包括无机氧化物材料，例如HfO2、SrTiO3、SnO2、CeO2、MgO、NiO、CaO、BaO、ZnO、ZrO2、 Y2O3、Al2O3、TiO2、SiO2、勃姆石，氢氧化镁、氢氧化铝；所述无机材料还可以是具有导锂离子能力的材料，如磷酸锂(Li3PO4)、锂钛磷酸盐(LixTiy(PO4)3，其中0<x<2且0<y<3)、锂铝钛磷酸盐(LixAlyTiz(PO4)3，其中0<x<2，0<y<1，且0<z<3)、其中0≤x≤1且0≤y≤1的Li1+x+y(Al,Ga)x(Ti,Ge)2-xSiyP3-yO12、锂镧钛酸盐(LixLayTiO3，其中0<x<2且0<y<3)、锂锗硫代磷酸盐(LixGeyPzSw，其中0<x<4，0<y<1，0<z<1，且0<w<5)、锂氮化物(LixNy，其中0<x<4，0<y<2)、SiS2玻璃(LixSiySz，其中0≤x<3，0<y<2，且0<z<4)、P2S5玻璃(LixPySz，其中0≤x<3，0<y<3，且0<z<7)、Li2O、LiF、LiOH、Li2CO3、LiAlO2、Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2陶瓷、和石榴石陶瓷(Li3+xLa3M2O12，其中0≤x≤5，且M is Te、Nb、或Zr)中的一种或几种。根据本申请的一些实施方式，所述无机材料存在于纤维隔离层的聚合物纤维内或聚合物纤维的间隙中，或所述无机材料布置在由聚合物纤维形成的层之间。
根据本申请的一些实施方式，所述纤维隔离层的厚度为500nm至30μm，优选5μm至10μm。借助于根据本申请的实施方式，通过调整静电纺丝的工艺参数，可以获得更薄的纤维隔离层，从而提高电池的能量密度。
图8示出了根据本申请的纤维隔离层的结构示意图，根据本申请的一些实施方式，根据本申请的纤维隔离层在纵向方向和横向方向的摩擦系数分别为εMD和εTD，其中，0.1＜εMD＜0.5，且0.1＜εTD＜0.5，其中，εMD为纵向方向的摩擦系数且εTD为横向方向的摩擦系数。当纤维隔离层的摩擦系数大于0.5时，该纤维隔离层与设备摩擦从而产生静电，造成纤维形貌结构破坏，褶皱，飞丝，拔针不良，并且较大的静电吸附能力还使得纤维隔离层吸附漂浮在环境中的粉末颗粒从而引发颗粒穿刺和短路；当纤维隔离层的摩擦系数小于0.1时，容易由于过小的摩擦而导致卷芯内部层与层之间发生错位，并最终造成卷绕端面不整齐，卷芯螺旋等缺陷。
添加剂改变了纤维的表面形态，降低了摩擦系数，进一步的，由于纤维隔离层具有更小的摩擦系数和更光滑的表面，根据本申请的纤维隔离层不容易出现褶皱、飞丝的现象，获得了更优的拔针效果，同时根据本申请的纤维隔离层不易粘辊或吸附异物颗粒，这有效缓解了隔离层因静电吸附粉尘造成的短路。
图9a和图9b示出了常规纺丝纤维层和根据本申请的含有添加剂的纤维隔离层的SEM图像，根据本申请的纤维隔离层具有丝径均匀的纤维和优异的孔隙率。根据本申请的一些实施方式，本申请的纤维隔离层的孔隙率为20％至80％，优选40％至60％。当纤维隔离层的孔隙率低于20％时，过小的孔隙率可导致离子传输通路堵塞，从而阻碍电芯正 常循环，当纤维隔离层的孔隙率高于80％时，过大的孔隙率可导致不稳定的结构和劣化的机械强度，从而无法抵抗极片表面颗粒的穿刺。因此，过大的孔隙率可能引发局部短路，并造成电池性能衰减和严重的自放电。
根据本申请的一些实施方式，所述纤维隔离层的孔径为20nm至1μm。当纤维隔离层的孔径小于20nm时，过小的孔径可导致离子传输通路不足，阻碍电芯正常循环。当纤维隔离层的孔径大于1μm时，过大的孔径可导致在该孔位置处的机械强度下降，从而无法抵抗极片表面颗粒的穿刺。因此，过大的孔径可能引发局部短路，并造成电池性能衰减和严重的自放电。
图10a和10b示出了常规纺丝纤维层表面和根据本申请的含有添加剂的纤维隔离层的表面的光学照片，图10a中圈出了静电吸附的异物颗粒，对比图10a和10b可以看出，根据本申请的含有添加剂的纤维隔离层避免了常规纺丝纤维层中经常出现的纤维飞丝、褶皱、异物颗粒吸附等不期望的现象。
根据本申请的一些实施方式，本申请的电化学装置不包括通常意义上的隔离膜，例如包括基材层和表面处理层的隔离膜。因此，本申请的电化学装置中不包括常规隔离膜，例如聚乙烯隔膜和聚丙烯隔膜。
本申请的电化学装置还包括电解液。可用于本申请的电解液可以为现有技术中已知的电解液。
根据本申请的一些实施方式，电解液包括有机溶剂、锂盐和可选的添加剂。本申请的电解液中的有机溶剂可为现有技术中已知的任何可作为电解液的溶剂的有机溶剂。根据本申请的电解液中使用的电解质没有限制，其可为现有技术中已知的任何电解质。根据本申请的电解液的添加剂可为现有技术中已知的任何可作为电解液添加剂的添加剂。在一些实施例中，有机溶剂包括，但不限于：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚丙酯或丙酸乙酯。在一些实施例中，有机溶剂包括醚类溶剂，例如包括1，3-二氧五环(DOL)和乙二醇二甲醚(DME)中的至少一种。在一些实施例中，锂盐包括有机锂盐或无机锂盐中的至少一种。在一些实施例中，锂盐包括，但不限于：六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、二氟磷酸锂(LiPO2F2)、双三氟甲烷磺酰亚胺锂LiN(CF3SO2)2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO2F)2)(LiFSI)、双草酸硼酸锂LiB(C2O4)2(LiBOB)或二氟草酸硼酸锂LiBF2(C2O4)(LiDFOB)。在一些实施例中，添加剂包括氟代碳酸乙烯酯和己二腈中的至少一种。
根据本申请的一些实施方式，本申请的电化学装置包括，但不限于：锂离子电池或钠离子电池。在一些实施例中，电化学装置是锂离子电池。
二、电子装置
本申请进一步提供了一种电子装置，其包括本申请第一方面所述的电化学装置。
本申请的电子设备或装置没有特别限定。在一些实施例中，本申请的电子设备包括但不限于，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。
在下述实施例及对比例中，所使用到的试剂、材料以及仪器如没有特殊的说明，均可商购获得。
实施例1
正极极片的制备
正极极片的制备涉及正极活性材料的涂覆以及纤维隔离层的涂覆。
(1)将正极活性材料钴酸锂(分子式为LiCoO2)、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97.5:1.0:1.5进行混合，加入适量N-甲基吡咯烷酮(NMP)作为溶剂搅拌混合，调配成为固含量为0.75的正极浆料，搅拌均匀后将该正极浆料涂覆在集流体铝箔上，在90℃下烘干，并将正极极片裁切成38mm×58mm的规格备用；
(2)使用PVDF的DMF(二甲基甲酰胺)溶液作为纺丝溶液，并在纺丝溶液中加入添加剂，所述添加剂为平滑剂脂肪酸聚氧乙烯酯，均匀混合后，在正极极片表面通过静电纺丝的方法，在正极极片的一面形成厚度为30μm的纤维隔离层，该纤维隔离层的平均孔径为150nm，孔隙率为60％，其中，基于该纤维隔离层的总重量，添加剂的浓度为1重量％，然后以相同的方法，在该正极极片的另一面也完成这些步骤，并在90℃条件下烘干，即得到双面纺丝涂布的正极极片。
负极极片的制备
将负极活性材料石墨(Graphite)、导电炭黑(Super P)、丁苯橡胶(SBR)按照重量比96:1.5:2.5进行混合，加入去离子水(H2O)作为溶剂，调配成为固含量为0.7的负极浆料，搅拌均匀后该负极浆料单面涂覆在铜箔集流体上，在110℃下烘干，并将极片裁切成41mm×61mm的规格待用。
以上步骤完成负极极片的单面涂布后，以相同的方法，在该极片背面也完成这些步骤，得到双面涂布的负极极片。
电解液的制备
在干燥氩气气氛中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)按照重量比EC:EMC:DEC＝30:50:20混合形成基础溶剂，然后向该基础溶剂中加入锂盐六氟磷酸锂(LiPF6)并混合均匀，得到锂盐的浓度为1.15M的电解液。
锂离子电池的制备
将根据实施例1制备的正极极片、负极极片依次相对叠放，用胶带将整个叠片结构的四个角进行固定并置入铝塑膜中，经顶侧封、注液、封装后，得到锂离子电池。
实施例2-10
以与实施例1基本相同的方法进行实施例2-10，区别在于，根据表1使用不同的添加剂以及添加剂浓度。
实施例11-16
以与实施例1基本相同的方法进行实施例11-16，区别在于，在正极极片制备的步骤(2)中使用PI(聚酰亚胺)的DMF(二甲基甲酰胺)溶液作为纺丝溶液，且根据表2使用不同的添加剂以及添加剂浓度。
对比例1
以与实施例1基本相同的方法进行对比例1，区别在于，在PVDF纺丝溶液中，不加入任何添加剂。
对比例2
以与实施例11基本相同的方法进行对比例2，区别在于，在PI纺丝溶液中，不加入任何添加剂。
摩擦系数测试
裁取适当面积的隔膜装夹到试样夹持块上，将不锈钢片固定在滑动平台的表面，然后把夹有隔膜的夹持块轻轻放到不锈钢片上与其完全接触，连接实验夹持块的铁丝一端放入带有拉力传感器的弹簧销座内，完成上述步骤后在一定速度条件下使滑动平台沿着导轨向右做匀速运动，连接试样夹持块的力值传感器因为隔膜与不锈钢片之间的摩擦而产生力值的变化，此时记录该测定过程隔膜与不锈钢片之间的力-位移曲线图，并根据力值算的隔膜与不锈钢片之间的最大静磨擦系数。
在MD和TD方向分别测量隔膜的摩擦系数，每个试样进行十次测试并取平均值。其 中，试样加持块的质量为100g至500g，试验速度为50mm/min至250mm/min，温度为10℃至40℃，湿度为20％RH至70％RH。
对实施例1-16和对比例1-2获得的纤维隔离层摩擦系数测试，实施例1-16和对比例1-2获得的电化学装置进行首次库伦效率测试、电芯自放电速率测试以及Hi-pot通过率测试，测试结果示出在表1和表2中。
表1
表2
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变、替代和修改，这些改变、替代和修改也落入本申请的保护范围。

Claims (10)

  1. 一种电化学装置，其特征在于，该电化学装置包括正极、负极和纤维隔离层，所述纤维隔离层在纵向方向和横向方向的摩擦系数分别为εMD和εTD，其中，0.1＜εMD＜0.5，且0.1＜εTD＜0.5。
  2. 根据权利要求1所述的电化学装置，其特征在于，所述纤维隔离层布置在正极和负极中的至少一者上。
  3. 根据权利要求1所述的电化学装置，其特征在于，所述纤维隔离层的厚度为500nm至30μm。
  4. 根据权利要求1所述的电化学装置，其特征在于，满足以下条件中至少一者：
    (i)所述纤维隔离层中包括聚合物纤维，且所述聚合物纤维的直径为100nm至1μm；
    (ii)所述纤维隔离层的孔隙率为20％至80％
    (iii)所述纤维隔离层的孔径为20nm至1μm。
  5. 根据权利要求1所述的电化学装置，其特征在于，所述纤维隔离层包括添加剂，其中，基于所述纤维隔离层的总重量计，所述添加剂的含量为1重量％至10重量％。
  6. 根据权利要求5所述的电化学装置，其特征在于，所述添加剂包括烷烃类化合物，酯类化合物和聚醚类化合物中的至少一种，并且其中，
    所述烷烃类化合物选自液体石蜡烷烃、环烷烃及其混合物；
    所述酯类化合物选自由各种醇类与高级脂肪酸通过缩合酯化，酯交换等途径制备而成的单酯、双酯以及多酯，所述酯类化合物包括脂肪酸聚氧乙烯酯、聚乙二醇月桂酸酯，硬脂酸聚氧乙烯酯、聚乙二醇硬脂酸酯和山梨糖醇酐硬脂酸酯，山梨糖醇酐硬脂酸单酯、聚氧乙烯硬脂酸木糖醇酯，硬脂酸聚氧乙烯酯或山梨糖醇酐油脂酯中的至少一种；
    所述聚醚类化合物包括氢化蓖麻油聚氧乙烯醚、聚氧乙烯脂肪胺、烷基聚氧乙烯醚硫酸酯盐、辛烷基聚氧乙烯醚、脂肪醇聚氧乙烯，二硬脂酰胺三乙胺基环氧丙烷季铵氯化物、和山梨糖醇酐硬脂酸酯聚氧乙烯醚中的至少一种。
  7. 根据权利要求5所述的电化学装置，其特征在于，所述添加剂还包括烷基磺酸盐、烷基酚聚氧乙烯醚硫酸酯盐、聚醚、抗静电剂TM、烷基磷酸酯二乙醇胺、脂肪醇聚氧乙烯醚、聚氧乙烯木糖醇单油酸酯、烷基聚氧乙烯醚磷酸酯钠盐、辛烷基酚聚氧乙烯醚、大豆二甲基羟乙基季铵乙基硫酸盐或十八烷基二甲基羟乙基季铵硝酸盐中的至少一种。
  8. 根据权利要求1所述的电化学装置，其特征在于，所述纤维隔离层具有纺丝骨架， 所述纺丝骨架包括选自以下的至少一种：聚偏二氟乙烯(PVDF)、聚酰亚胺(PI)、聚酰胺、聚丙烯腈、聚乙二醇、聚丙烯腈(PAN)、聚氧化乙烯、聚苯醚(PPO)、聚碳酸亚丙酯(PPC)、聚甲基丙烯酸甲酯(PMMA)、聚对苯二甲酸乙二醇酯、聚偏氟乙烯-六氟丙烯(PVDF-HFP)、聚(偏二氟乙烯-共-三氟氯乙烯)及其衍生物。
  9. 根据权利要求1所述的电化学装置，其特征在于，所述纤维隔离层的厚度为5μm至10μm，和/或
    所述纤维隔离层的孔隙率为40％至60％。
  10. 一种电子装置，其特征在于，该电子装置包括权利要求1至9中任一项所述的电化学装置。
PCT/CN2023/082320 2023-03-17 2023-03-17 电化学装置和电子装置 Ceased WO2024192589A1 (zh)

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