WO2023184363A1 - 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
WO2023184363A1
WO2023184363A1 PCT/CN2022/084460 CN2022084460W WO2023184363A1 WO 2023184363 A1 WO2023184363 A1 WO 2023184363A1 CN 2022084460 W CN2022084460 W CN 2022084460W WO 2023184363 A1 WO2023184363 A1 WO 2023184363A1
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Prior art keywords
layer
electrochemical device
electrode assembly
present application
packaging
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PCT/CN2022/084460
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English (en)
French (fr)
Inventor
侯天昊
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宁德新能源科技有限公司
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Priority to PCT/CN2022/084460 priority Critical patent/WO2023184363A1/zh
Publication of WO2023184363A1 publication Critical patent/WO2023184363A1/zh

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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
    • H01M10/052—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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • 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
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
    • H01M50/124—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure
    • 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
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/131—Primary casings, jackets or wrappings of a single cell or a single battery characterised by physical properties, e.g. gas-permeability or size

Definitions

  • the present application relates to the field of energy storage, and specifically to an electrochemical device and an electronic device.
  • Metal-shell secondary batteries generally have sealed flange edges, or in order to avoid short-circuiting between the electrode assembly and the case, plastic gaskets or tapes need to be added for insulation. This part also does not contribute to energy storage but occupies the volume of the electrode assembly, thus Reduce the energy density of secondary batteries.
  • the present application provides an electrochemical device and an electronic device including the electrochemical device.
  • the packaging film used to package the electrode assembly in the electrochemical device of the present application accounts for a small volume, and the water vapor permeability rate of the packaging film is low, which can increase the volume energy density of the electrochemical device while ensuring the reliability of the packaging.
  • the present application provides an electrochemical device, which includes an electrode assembly and a packaging film for packaging the electrode assembly.
  • the packaging film includes a first layer and a second layer, and the first layer and the second layer are each closed.
  • the water vapor permeability rate of the encapsulating film is WVTR ⁇ 0.001g/(m 2 ⁇ day).
  • Each layer in the packaging film of the present application is in a closed form, and there are no edge sealing and other structures that do not contribute to energy storage, which can greatly improve the space utilization of the electrochemical device and thereby increase its volumetric energy density.
  • the low water vapor permeability rate of the packaging film can effectively isolate water vapor and oxygen molecules in the air from entering the electrochemical device and prevent solvent molecules in the electrolyte from escaping from the electrochemical device, ensuring the reliability of the packaging.
  • the mass content of each metal element in the first layer and the second layer is less than 80%.
  • the first layer is obtained by coating the first layer of raw material on the surface of the electrode assembly.
  • the coating and encapsulation method is used to integrate the first layer on the surface of the electrode assembly, eliminating the need for operations such as heat sealing or welding. Furthermore, there is no edge sealing or other structures that do not contribute to energy storage, which can be extremely effective. Greatly improve the space utilization of electrochemical devices and increase their volumetric energy density.
  • the coating packaging method of the present application can also better meet the packaging requirements of special-shaped electrochemical devices.
  • the second layer includes an inorganic layer and optionally an organic polymer layer.
  • the second layer of this application can, on the one hand, isolate water vapor and oxygen molecules in the air from entering the electrochemical device, and on the other hand, prevent the solvent molecules in the electrolyte from escaping from the electrochemical device, which can greatly ensure the reliability of the package. .
  • the second layer includes alternating inorganic and organic polymer layers.
  • the thickness of the inorganic layer is ⁇ 1 nm. In some embodiments, the thickness of the organic polymer layer is ⁇ 1 ⁇ m.
  • the inorganic layer includes at least one of metal, inorganic oxide or nitride.
  • the organic polymer layer includes resin.
  • the encapsulation film further includes a third layer, the first layer is in contact with the electrode assembly, and the second layer is disposed between the third layer and the first layer.
  • the first layer includes resin.
  • the third layer includes fibers and resin.
  • the present application provides an electronic device including the electrochemical device described in the first aspect.
  • this application adopts a coating and encapsulation method, which greatly reduces the volume ratio of the encapsulation film and improves the energy density of the electrochemical device.
  • the packaging film of this application has a low water vapor permeability rate, which can effectively isolate water vapor and oxygen molecules in the air from entering the electrochemical device and prevent solvent molecules in the electrolyte from escaping from the electrochemical device, ensuring the reliability of the packaging.
  • Figure 1 is a schematic diagram of an encapsulation film in an electrochemical device according to some embodiments of the present application.
  • Figure 2 is a schematic structural diagram of an electrode assembly and an encapsulating film in an electrochemical device according to some embodiments of the present application.
  • Figure 3 is a schematic structural diagram of an electrode assembly and an encapsulating film in an electrochemical device according to some embodiments of the present application.
  • FIG. 4 is a schematic diagram of the barrier layer of the packaging film shown in FIG. 3 .
  • Figure 5 is an X-ray CT image of a traditional aluminum-plastic film-encapsulated electrochemical device.
  • the outer packaging film of the electrode assembly is discontinuous, and there are obvious traces of melted packaging.
  • Figure 6 is an X-ray CT image of a traditional metal shell packaged electrochemical device.
  • the outer package of the electrode assembly is discontinuous and there are obvious traces of fusion welding.
  • Figure 7 is an X-ray CT image of an electrochemical device according to some embodiments of the fundamental application.
  • the outer packaging film of the electrode assembly is continuous, and there are no obvious traces of welding and packaging. Shows the characteristics of continuous closure.
  • the reference numbers are as follows: 100-encapsulation film; 10-sealing layer; 20-barrier layer; 200-electrode assembly; 1-inorganic layer; 2-organic polymer layer.
  • the present application provides an electrochemical device, which includes an electrode assembly and a packaging film for packaging the electrode assembly.
  • the packaging film includes a first layer and a second layer, and the first layer and the second layer are each closed.
  • the water vapor permeability rate of the encapsulating film is WVTR ⁇ 0.001g/(m 2 ⁇ day).
  • Each layer in the packaging film of the present application is in a closed form, and there are no edge sealing and other structures that do not contribute to energy storage, which can greatly improve the space utilization of the electrochemical device and thereby increase its volumetric energy density.
  • the low water vapor permeability rate of the packaging film can effectively isolate water vapor and oxygen molecules in the air from entering the electrochemical device and prevent solvent molecules in the electrolyte from escaping from the electrochemical device, ensuring the reliability of the packaging.
  • the "closed form” in this application means that the morphology of each layer is uniform throughout, and there is no structure formed by heat sealing or welding. For example, when observing the electrochemical device through X-ray CT, it does not contain tabs or poles. Within the scope of any CT cross-section of the column, there are no obvious traces of welding and heat sealing in each layer, showing closed characteristics. More clearly, the above-mentioned cross-section can be observed through an optical microscope and any other microscopic imaging method.
  • Electrode assembly in this application refers to the part of an electrochemical device consisting of a positive electrode, a negative electrode and a separator.
  • the water vapor permeability rate WVTR of the encapsulation film is 0.0001g/(m 2 ⁇ day), 0.0002g/(m 2 ⁇ day), 0.0003g/(m 2 ⁇ day), 0.0004g/ (m 2 ⁇ day), 0.0005g/(m 2 ⁇ day), 0.0006g/(m 2 ⁇ day), 0.0007g/(m 2 ⁇ day), 0.0008g/(m 2 ⁇ day), 0.0009g/ (m 2 ⁇ day) or a range consisting of any two of these values.
  • the mass content of each metal element in the first layer and the second layer is less than 80%, such as less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, less than 50%. %, less than 45%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, or less than 1%.
  • the first layer is obtained by coating the first layer of raw material on the surface of the electrode assembly.
  • the coating and encapsulation method is used to integrate the first layer on the surface of the electrode assembly, eliminating the need for operations such as heat sealing or welding. Furthermore, there is no edge sealing or other structures that do not contribute to energy storage, which can be extremely effective. Greatly improve the space utilization of electrochemical devices and increase their volumetric energy density.
  • the coating packaging method of the present application can also better meet the packaging requirements of special-shaped electrochemical devices.
  • coating includes at least one of spraying, blade coating, dipping or brushing.
  • the first layer is a sealing layer. On the one hand, it is used to seal the electrode assembly to ensure that it is sealed without leakage. On the other hand, it serves as the base of the second layer to increase the adhesion with the second layer.
  • the second layer includes an inorganic layer and optionally an organic polymer layer.
  • the second layer is a barrier layer.
  • the second layer of this application can, on the one hand, isolate water vapor and oxygen molecules in the air from entering the electrochemical device, and on the other hand, prevent the solvent molecules in the electrolyte from escaping from the electrochemical device, which can greatly ensure the reliability of the package.
  • the second layer is evaporated on the surface of the first layer by vapor deposition.
  • vapor deposition includes at least one of chemical vapor deposition, physical vapor deposition, or atomic layer deposition.
  • the second layer includes an inorganic layer and an organic polymer layer.
  • the second layer includes alternating inorganic and organic polymer layers.
  • the second layer includes an inorganic layer, an organic polymer layer, and an inorganic layer stacked in sequence.
  • an organic polymer layer is formed by coating an organic polymer precursor on the surface of the first layer, and then using vapor deposition to evaporate an inorganic substance on the organic polymer layer to obtain an inorganic layer.
  • vapor deposition is used to evaporate an inorganic substance on the surface of the first layer to form an inorganic layer, and then an organic polymer precursor is coated on the surface of the inorganic layer to obtain an organic polymer layer.
  • the thickness of the inorganic layer is ⁇ 1 nm, for example, 5 nm, 10 nm, 30 nm, 50 nm, 70 nm, 90 nm, 100 nm, 110 nm, 130 nm, 150 nm, 170 nm, 190 nm, 200 nm, 230 nm, 250 nm, 270 nm, 300 nm , 350nm, 400nm, 450nm, 500nm or a range consisting of any two of these values.
  • the thickness of the organic polymer layer is ⁇ 1 ⁇ m, such as 5 ⁇ m, 7 ⁇ m, 10 ⁇ m, 30 ⁇ m, 50 ⁇ m, 70 ⁇ m, 100 ⁇ m, 150 ⁇ m, 200 ⁇ m, 250 ⁇ m, 300 ⁇ m, 350 ⁇ m, 400 ⁇ m, 450 ⁇ m, or any of these values.
  • the inorganic layer includes at least one of metal, inorganic oxide or nitride.
  • the metal includes at least one of a noble metal or a transition metal.
  • the metal includes at least one of aluminum, iron, copper, silver, gold, nickel, manganese, zinc, tin, zirconium, titanium, or vanadium.
  • the inorganic oxide includes at least one of titanium oxide, aluminum oxide, hafnium dioxide, iron oxide, copper oxide, silver oxide, nickel oxide, manganese oxide, zinc oxide, tin oxide, zirconium titanium oxide, or vanadium oxide.
  • the nitride includes at least one of silicon nitride, silicon oxynitride, boron nitride, titanium nitride, or aluminum nitride.
  • the organic polymer layer includes resin.
  • the organic polymer layer includes at least one of acrylic resin, epoxy resin, or polyurethane.
  • the encapsulation film further includes a third layer, the first layer is in contact with the electrode assembly, and the second layer is disposed between the third layer and the first layer.
  • the third layer is a protective layer used to protect the electrode assembly and provide high mechanical strength to inhibit expansion of the electrode assembly.
  • the first layer includes resin.
  • the third layer includes fibers and resin.
  • the resin includes at least one of a thermosetting resin or a thermoplastic resin.
  • thermosetting resin in this application may refer to a resin with thermosetting properties. Thermoset refers to the property that chemical changes occur after heating and gradually harden into shape. After hardening into shape, it cannot dissolve even when heated to above the glass transition temperature Tg or melting point Tm. According to the test standards of the standard “GB/T 3682.1-2018", the melt index should be ⁇ 1g/10min.
  • thermoset resins include, but are not limited to, phenolic resins, epoxy resins, melamine resins, polyimide resins, polyester resins, acrylic resins, silicone resins, cross-linked polyolefin resins, and mixtures thereof.
  • thermoplastic resin in this application may refer to a resin with thermoplasticity.
  • Thermoplasticity refers to the property of repeatedly softening when heated and solidifying when cooled without chemical reaction. According to the standard “GB/T 3682.1-2018", the melt index should be greater than 1g/10min.
  • thermoplastic resins include, but are not limited to, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, polyethylene terephthalate, and its mixture.
  • the electrode assembly includes a positive electrode, a negative electrode, and a separation film located between the positive electrode and the negative electrode.
  • the positive electrode includes a positive active material layer and a positive current collector.
  • the positive active material layer includes a positive active material, a binder, and a conductive agent.
  • the cathode active material may include lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminate, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium iron manganese phosphate, silicic acid At least one of lithium iron, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel type lithium manganate, spinel type lithium nickel manganate and lithium titanate.
  • the binder may include various binder polymers, such as polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethylcellulose, lithium carboxymethylcellulose, modified At least one of polyvinylidene fluoride, modified SBR rubber or polyurethane.
  • any conductive material can be used as the conductive agent as long as it does not cause chemical changes.
  • conductive agents include: carbon-based materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.; metal-based materials, such as metal powder or metal fibers including copper, nickel, aluminum, silver, etc. ; Conductive polymers, such as polyphenylene derivatives, etc.; or mixtures thereof.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil can be used.
  • the composite current collector can 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 negative electrode includes a negative active material layer and a negative current collector.
  • the negative active material layer includes a negative active material, a binder, and a conductive agent.
  • the negative active material may include a material that reversibly intercalates/deintercalates lithium ions, lithium metal, lithium metal alloy, or transition metal oxide.
  • the negative active material includes at least one of carbon material or silicon material, the carbon material includes at least one of graphite and hard carbon, and the silicon material includes silicon, silicon oxy compound, silicon carbon compound or silicon alloy. of at least one.
  • the binder includes styrene-butadiene rubber, polyacrylic acid, polyacrylate, polyimide, polyamideimide, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, water-based acrylic resin , at least one of polyvinyl formal or styrene-acrylic acid copolymer resin.
  • any conductive material can be used as the conductive material as long as it does not cause chemical changes.
  • the conductive material includes at least one of conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, conductive graphite, or graphene.
  • the negative electrode current collector may be copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with conductive metal, or a combination thereof.
  • the isolation membrane used in the electrochemical device of the present application are not particularly limited, and it can be any technology disclosed in the prior art.
  • the isolation membrane includes polymers or inorganic substances formed of materials that are stable to the electrolyte of the present application.
  • the isolation film may include a base material layer and a surface treatment layer.
  • the base material layer is a non-woven fabric, film or composite film with a porous structure.
  • the base material layer is made of at least one material selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • polypropylene porous membrane, polyethylene porous membrane, polypropylene non-woven fabric, polyethylene non-woven fabric or polypropylene-polyethylene-polypropylene porous composite membrane can be used.
  • a surface treatment layer is provided on at least one surface of the base layer.
  • the surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic layer.
  • the inorganic layer includes inorganic particles and a binder.
  • the inorganic particles are selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, At least one of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyethylene alkoxy , at least one of polymethylmethacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer is selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyethylene alkoxy, polyvinylidene fluoride, At least one of poly(vinylidene fluoride-hexafluoropropylene).
  • the electrochemical device of the present application also includes an electrolyte. Electrolytes useful in this application may be electrolytes known in the art.
  • the electrolyte solution includes organic solvents, electrolyte salts, and optional additives.
  • the organic solvent of the electrolyte solution according to the present application may be any organic solvent known in the prior art that can be used as a solvent for the electrolyte solution.
  • the electrolyte used in the electrolyte solution according to the present application is not limited, and it can be any electrolyte known in the prior art.
  • the additives of the electrolyte according to the present application may be any additives known in the art that can be used as electrolyte additives.
  • organic solvents include, but are 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 ether solvents, such as at least one of 1,3-dioxane (DOL) and ethylene glycol dimethyl ether (DME).
  • the electrolyte salt may be a lithium salt, a sodium salt, or the like.
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • lithium salts include, but are not limited to: lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium bistrifluoromethanesulfonimide LiN (CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bisoxalatoborate LiB(C 2 O 4 ) 2 (LiBOB) or Lithium difluorooxalate borate LiBF 2 (C 2 O 4 ) (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiN CF 3 SO 2 ) 2
  • LiTFSI lithium bistrifluoromethanesulfonimide LiN
  • sodium salts include, but are not limited to: NaClO 4 , NaPF 6 , NaBF 4 , Na(FSO 2 ) 2 N, Na(CF 3 SO 2 ) 2 N, Na(C 2 F 5 SO 2 ) At least one of 2 N, NaCF 3 SO 3 , NaSbF 6 , NaBC 4 O 8 , NaFSI, NaTFSI, lower aliphatic carboxylic acid sodium salt, NaAlCl 4 , NaPO 2 F 2 or Na 2 PO 3 F.
  • electrochemical devices of the present application include, but are not limited to: all types of primary batteries, secondary batteries, or capacitors.
  • the electrochemical device is a lithium secondary battery.
  • lithium secondary batteries include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.
  • the electrochemical device is a sodium-ion battery.
  • the present application further provides an electronic device, which includes the electrochemical device described in the first aspect of the present application.
  • electronic devices of the present application 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, and stereo headsets. , VCR, LCD TV, portable cleaner, portable CD player, mini CD, transceiver, electronic notepad, calculator, memory card, portable recorder, radio, backup power supply, motor, automobile, motorcycle, power-assisted bicycle, bicycle , lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • these steps are also completed on the back of the electrode piece in a completely consistent manner, that is, a double-sided coated positive electrode piece is obtained.
  • the positive electrode sheet is cold-pressed to a compacted density of 4.1g/ cm3 , which completes the entire preparation process of the positive electrode sheet.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • LiPF 6 lithium salt lithium hexafluorophosphate
  • PE polyethylene
  • the isolation film stack the positive electrode piece, isolation film, and negative electrode piece in order, so that the isolation film is between the positive and negative electrodes to play the role of isolation, and then fold the stacked
  • the pole piece and isolation film are rolled into an electrode assembly, and then the electrode assembly is injected with liquid, and the electrode assembly after the liquid injection is completed is packaged.
  • the resin precursor see the table below for specific types
  • a resin layer i.e., the sealing layer
  • the inorganic substance see the table below for specific types
  • X-ray CT X-ray electronic computed tomography
  • model: GE Phoenix m300 X-ray electronic computed tomography
  • the scanned battery images are then calculated and synthesized using the software provided by the device.
  • the processed image can be used to cut any cross-section of the battery to obtain a synthesized X-ray CT cross-sectional image.
  • the battery is completely embedded in epoxy resin, and then the embedded battery is placed in a liquid nitrogen atmosphere, and the battery is subjected to brittle fracture treatment (the outermost part of the brittle fracture position of the battery core does not contain tabs, and freezing ultra-thin sectioning technology is used) The effect will be better if the cross section is smoothed), and a sample of the packaging film area is transferred to the scanning electron microscope (SEM) cavity to obtain a sample for scanning electron microscopy analysis.
  • SEM scanning electron microscope
  • EDS X-ray energy spectroscopy
  • Table 1 shows the impact of different packaging methods on volumetric energy density. Comparative Examples 1 and 2 are traditional soft package or metal shell packaging, and Example 1 is coated packaging. Among them, coating packaging increases the energy density of lithium-ion batteries by more than 15% compared to traditional packaging methods.
  • Table 2 reflects the impact of different barrier layer compositions on battery cycle performance.
  • the material selected in Comparative Example 3 does not contain an inorganic barrier layer, and the water vapor permeability is 0.10015g/(m 2 ⁇ day), so the cycle capacity decays quickly.
  • Examples 2 and 3 adopt a barrier process of single-layer or double-layer aluminum oxide by atomic layer deposition. The water vapor permeability is low, and the cycle life is increased by more than 30% compared to Comparative Example 3.
  • Example 3-1 to 3-5 The battery preparation and other parameters of Examples 3-1 to 3-5 are consistent with Example 1, and the only difference lies in the barrier layer material.
  • Example 3-1 and Example 3-2 are pure metals.
  • Examples 3-3 and 3-4 are inorganic oxides.
  • Example 3 -5 Composite structure of metal + inorganic oxide. Among them, the composite structure of metal + inorganic oxide significantly improves the battery cycle performance.
  • Example 4-1 The battery preparation and other parameters of Example 4-1 to Example 4-2 are consistent with Example 3, and the only difference lies in the material and structure of the barrier layer.
  • Table 4 shows the impact of different barrier layer structures on battery cycle performance.
  • Examples 4-1 and 4-2 are laminated structures of inorganic layer + organic layer
  • Example 4-3 is 3 of inorganic layer + organic layer + inorganic layer.
  • the composite laminated structure improves the cycle performance by more than 5% compared to the single-layer inorganic barrier layer.
  • Example 5-1 The battery preparation and other parameters of Example 5-1 to Example 5-3 are consistent with Example 3. The only difference lies in the material, structure and thickness of the barrier layer.
  • Example 5-1 uses a thinner inorganic barrier layer, which has a relatively higher energy density. The cycle performance is compared to Example 5-1 which has a thicker barrier layer. 2 and 5-3 are affected to a certain extent. Therefore, the thickness of the inorganic layer is preferably ⁇ 10 nm.

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Abstract

提供一种电化学装置，其包括电极组件和用于封装所述电极组件的封装膜，所述封装膜包括第一层和第二层，所述第一层和所述第二层各自呈闭合形态，其中，所述封装膜的水蒸气渗透速率WVTR≤0.001g/(m 2·天)。本申请电化学装置中用于封装电极组件的封装膜体积占比小，且封装膜的水蒸气渗透速率低，能够在提升电化学装置体积能量密度的同时，保证封装的可靠性。还提供一种包括电化学装置的电子装置。

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
二次电池在消费电子领域具有广泛的应用，且近年来其终端市场呈现出小型化、高能量密度的需求。目前，二次电池的主流封装形式有两种，软包和金属壳封装。但这两种传统主流封装工艺存在空间利用率相对较低、电池能量密度损失大的问题。软包二次电池普遍存在顶封和侧封边，封印边没有活性物质却占有一定的体积，因此降低电池的能量密度，并且电极组件容量越小，能量密度降低越多。现有技术中尽管可以使用侧封折边工艺减小能量密度损失，但顶封处由于连接极耳热熔层和包装袋热熔层，存在漏液的风险。金属壳二次电池普遍存在密封法兰边，或者为避免电极组件与壳体短路，需要添加塑料垫片或胶纸做绝缘处理，该部分同样对储存能量没有贡献却占据电极组件的体积，进而降低二次电池的能量密度。
发明内容
鉴于现有技术存在的上述问题，本申请提供一种电化学装置及包括该电化学装置的电子装置。本申请电化学装置中用于封装电极组件的封装膜体积占比小，且封装膜的水蒸气渗透速率低，能够在提升电化学装置体积能量密度的同时，保证封装的可靠性。
在第一方面，本申请提供一种电化学装置，其包括电极组件和用于封装电极组件的封装膜，该封装膜包括第一层和第二层，第一层和第二层各自呈闭合形态，其中，封装膜的水蒸气渗透速率WVTR≤0.001g/(m 2·天)。本申请的封装膜中各层呈闭合形态，不存在对储存能量没有贡献的封边等结构，能够极大的提高电化学装置的空间利用率，进而提升其体积能量密度。同时，封装膜的水蒸气渗透速率低能够有效隔绝空气中的水蒸气和氧气分子进入电化学装置以及隔绝电解液中的溶剂分子逸出电化学装置，保证封装的可靠性。
根据本申请的一些实施方式，第一层和第二层中，各自金属元素的质量含量占比小于80％。
在一些实施方式中，通过将第一层原料涂覆于所述电极组件表面，得到第一层。本申请中，利用涂覆封装的方式，使第一层在电极组件表面一体化成型，无需再进行例如热封或焊接等操作，进而不存在对储存能量没有贡献的封边等结构，能够极大的提高电化学装置的空间利用率，提升其体积能量密度。此外，本申请的涂覆封装方式还能够更好地满足异形电化学装置的封装。
根据本申请的一些实施方式，第二层包括无机层和可选的有机聚合物层。本申请的第二层，一方面能够隔绝空气中的水蒸气和氧气分子进入电化学装置，另一方面是隔绝电解液中的溶剂分子逸出电化学装置，可以极大的保证封装的可靠性。
根据本申请的一些实施方式，第二层包括交替的无机层和有机聚合物层。
根据本申请的一些实施方式，无机层的厚度≥1nm。在一些实施方式中，有机聚合物层的厚度≥1μm。
根据本申请的一些实施方式，无机层包括金属、无机氧化物或氮化物中的至少一种。根据本申请的一些实施方式，有机聚合物层包括树脂。
根据本申请的一些实施方式，封装膜还包括第三层，第一层与电极组件相接触，第二层设置于第三层与第一层之间。
根据本申请的一些实施方式，第一层包括树脂。在一些实施方式中，第三层包括纤维和树脂。
在第二方面，本申请提供一种电子装置，其包括第一方面所述的电化学装置。
相比于现有技术，本申请采用涂覆封装的方式，极大地降低了封装膜的体积占比，提升了电化学装置的能量密度。同时本申请封装膜的水蒸气渗透速率较低，能够有效隔绝空气中的水蒸气和氧气分子进入电化学装置以及隔绝电解液中的溶剂分子逸出电化学装置，保证封装的可靠性。
附图说明
图1为本申请一些实施方式的电化学装置中封装膜的示意图。
图2为本申请一些实施方式的电化学装置中电极组件与封装膜的结构示意图。
图3为本申请一些实施方式的电化学装置中电极组件与封装膜的结构示意图。
图4为图3所述的封装膜的阻隔层的示意图。
图5为传统铝塑膜封装电化学装置的X-ray CT图，在不包含极耳或极柱的CT截面图范围内，电极组件外侧封装膜不连续，存在明显的熔融封装的痕迹。
图6为传统金属壳封装电化学装置的X-ray CT图，在不包含极耳或极柱的CT截面图范围内，电极组件外侧封装不连续，存在明显的熔融焊接的痕迹。
图7为根本申请的一些实施方式的电化学装置的X-ray CT图，在不包含极耳或极柱的CT截面图范围内，电极组件外侧封装膜连续，无明显的焊接和封装痕迹，呈现连续闭合的特征。
附图标记说明如下：100-封装膜；10-封闭层；20-阻隔层；200-电极组件；1-无机层；2-有机聚合物层。
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，其包括电极组件和用于封装电极组件的封装膜，该封装膜包括第一层和第二层，第一层和第二层各自呈闭合形态，其中，封装膜的水蒸气渗透速率WVTR≤0.001g/(m 2·天)。本申请的封装膜中各层呈闭合形态，不存在对储存能量没有贡献的封边等结构，能够极大的提高电化学装置的空间利用率，进而提升其体积能量密度。同时，封装膜的水蒸气渗透速率低能够有效隔绝空气中的水蒸气和氧气分子进入电化学装置以及隔绝电解液中的溶剂分子逸出电化学装置，保证封装的可靠性。
本申请中“闭合形态”是每一层各处的形貌均一，不存在通过热封或焊接形成的结构，例如，通过X-ray CT观察该电化学装置时，在不包含极耳或极柱的任意CT截面图范围内，每一层中无明显的焊接和热封痕迹，呈现闭合的特征。更为清晰地，可以通过光学显微镜，及其他任意显微成像方式对上述截面进行观察。
本申请中“电极组件”指的是电化学装置中由正极、负极和隔离膜组成的部分。
根据本申请的一些实施方式，封装膜的水蒸气渗透速率WVTR为0.0001g/(m 2·天)、0.0002g/(m 2·天)、0.0003g/(m 2·天)、0.0004g/(m 2·天)、0.0005g/(m 2·天)、0.0006g/(m 2·天)、0.0007g/(m 2·天)、0.0008g/(m 2·天)、0.0009g/(m 2·天)或这些值中任意两者组成的范围。
根据本申请的一些实施方式，第一层和第二层中，各自金属元素的质量含量小于80％，例如小于75％、小于70％、小于65％、小于60％、小于55％、小于50％、小于45％、小于40％、小于35％、小于30％、小于25％、小于20％、小于15％、小于10％、小于5％ 或小于1％。
在一些实施方式中，通过将第一层原料涂覆于所述电极组件表面，得到第一层。本申请中，利用涂覆封装的方式，使第一层在电极组件表面一体化成型，无需再进行例如热封或焊接等操作，进而不存在对储存能量没有贡献的封边等结构，能够极大的提高电化学装置的空间利用率，提升其体积能量密度。此外，本申请的涂覆封装方式还能够更好地满足异形电化学装置的封装。在一些实施方式中，涂覆包括喷涂，刮涂，浸涂或刷涂中的至少一种。
在一些实施方式中，第一层为封闭层，一方面用于封闭电极组件，保证封闭不漏液，另一方面作为第二层的基底，增大和第二层的粘附性。
根据本申请的一些实施方式，第二层包括无机层和可选的有机聚合物层。在一些实施方式中，第二层为阻隔层。本申请的第二层，一方面能够隔绝空气中的水蒸气和氧气分子进入电化学装置，另一方面是隔绝电解液中的溶剂分子逸出电化学装置，可以极大的保证封装的可靠性。在一些实施方式中，第二层是以气相沉积的方式蒸镀在第一层的表面。在一些实施方式中，气相沉积包括化学气相沉积、物理气相沉积或原子层沉积中的至少一种。
根据本申请的一些实施方式，第二层包括无机层和有机聚合物层。在一些实施方式中，第二层包括交替的无机层和有机聚合物层。在一些实施方式中，第二层包括依次叠设的无机层、有机聚合物层和无机层。在一些实施方式中，通过将有机物聚合物前驱体涂覆在第一层的表面形成有机聚合物层，然后使用气相沉积将无机物蒸镀在有机聚合物层，得到无机层。在一些实施方式中，使用气相沉积将无机物蒸镀在第一层的表面形成无机层，然后将有机物聚合物前驱体涂覆在无机层的表面，得到有机聚合物层。
根据本申请的一些实施方式，无机层的厚度≥1nm，例如为5nm、10nm、30nm、50nm、70nm、90nm、100nm、110nm、130nm、150nm、170nm、190nm、200nm、230nm、250nm、270nm、300nm、350nm、400nm、450nm、500nm或这些值中任意两者组成的范围。
根据本申请的一些实施方式，有机聚合物层的厚度≥1μm，例如5μm、7μm、10μm、30μm、50μm、70μm、100μm、150μm、200μm、250μm、300μm、350μm、400μm、450μm或这些值中任意两者组成的范围。
根据本申请的一些实施方式，无机层包括金属、无机氧化物或氮化物中的至少一种。在一些实施方式中，金属包括贵金属或过渡金属中的至少一种。在一些实施方式中，金属包括铝、铁、铜、银、金、镍、锰、锌、锡、锆、钛或钒中的至少一种。在一些实施方式中，无机氧化物包括氧化钛、氧化铝、二氧化铪、氧化铁、氧化铜、氧化银、氧化镍、氧 化锰、氧化锌、氧化锡、氧化锆钛或氧化钒中的至少一种。在一些实施方式中，氮化物包括氮化硅、氮氧化硅、氮化硼、氮化钛或氮化铝中的至少一种。
根据本申请的一些实施方式，有机聚合物层包括树脂。在一些实施方式中，有机聚合物层包括丙烯酸树脂、环氧树脂或聚氨酯中的至少一种。
根据本申请的一些实施方式，封装膜还包括第三层，第一层与电极组件相接触，第二层设置于第三层与第一层之间。在一些实施方式中，第三层为保护层，用于保护电极组件并提供高的机械强度以抑制电极组件的膨胀。
根据本申请的一些实施方式，第一层包括树脂。在一些实施方式中，第三层包括纤维和树脂。
在一些实施方式中，树脂包括热固性树脂或热塑性树脂中的至少一种。
本申请中“热固性树脂”可以指的是具有热固性的树脂。热固性是指具有加热后产生化学变化，逐渐硬化成型，硬化成型后，再加热到玻璃化转变温度Tg或熔点Tm以上时，也不能溶解的性能。根据标准《GB/T 3682.1-2018》的测试标准，熔融指数应＜1g/10min。在一些实施方式中，热固性树脂包含但不限于酚醛树脂、环氧树脂、三聚氰胺树脂、聚酰亚胺树脂、聚酯树脂、丙烯酸树脂、有机硅树脂、交联的聚烯烃树脂及其混合物。
本申请中“热塑性树脂”可以指的是具有热塑性的树脂。热塑性是指具有反复受热软化，冷却固化而不发生化学反应的性能。根据标准《GB/T 3682.1-2018》，熔融指数应大于1g/10min。在一些实施方式中，热塑性树脂包括但不限于聚丙烯、聚乙烯、聚氯乙烯、聚苯乙烯、聚甲醛、聚碳酸酯、聚苯醚、聚砜、聚对苯二甲酸乙二醇酯及其混合物。
根据本申请的一些实施方式，电极组件包括正极、负极和位于正极和负极之间的隔离膜。
根据本申请的一些实施方式，正极包括正极活性材料层和正极集流体。
根据本申请的一些实施方式，正极活性材料层包括正极活性材料、粘结剂和导电剂。在一些实施方式中，正极活性材料可以包括钴酸锂、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。在一些实施方式中，粘结剂可以包括各种粘合剂聚合物，例如聚偏氟乙烯、聚四氟乙烯、聚烯烃类、羧甲基纤维素钠、羧甲基纤维素锂、改性聚偏氟乙烯、改性SBR橡胶或聚氨酯中的至少一种。在一些实施例中，可以使用任何导电的材料作为导电剂，只要它不引起化学变化即可。导电剂的示例包括：碳基材料，例如天然石墨、人造石墨、炭黑、乙炔黑、科琴黑、碳纤维等； 金属基材料，例如包括铜、镍、铝、银等的金属粉或金属纤维；导电聚合物，例如聚亚苯基衍生物等；或它们的混合物。
根据本申请的一些实施方式，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。
根据本申请的一些实施方式，负极包括负极活性材料层和负极集流体。
根据本申请的一些实施方式，负极活性材料层包括负极活性材料、粘结剂和导电剂。在一些实施方中，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、锂金属合金或过渡金属氧化物。在一些实施方式中，负极活性材料包括碳材料或硅材料中的至少一种，碳材料包括石墨、硬碳中的至少一种，硅材料包括硅、硅氧化合物、硅碳化合物或硅合金中的至少一种。在一些实施方式中，粘结剂包括丁苯橡胶、聚丙烯酸、聚丙烯酸盐、聚酰亚胺、聚酰胺酰亚胺、聚偏氟乙烯、聚二氟乙烯、聚四氟乙烯、水性丙烯酸树脂、聚乙烯醇缩甲醛或苯乙烯-丙烯酸共聚树脂中的至少一种。在一些实施方式中，可以使用任何导电的材料作为该导电材料，只要它不引起化学变化即可。在一些实施方式中，导电材料包括导电炭黑、乙炔黑、碳纳米管、科琴黑、导电石墨或石墨烯中的至少一种。
根据本申请的一些实施方式，负极集流体可以为铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、包覆有导电金属的聚合物基板或它们的组合。
本申请的电化学装置中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。例如隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的至少一种。粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯烷氧、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的至少一 种。
聚合物层中包含聚合物，聚合物的材料选自聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯烷氧、聚偏氟乙烯、聚(偏氟乙烯-六氟丙烯)中的至少一种。
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。
在一些实施方式中，电解液包括有机溶剂、电解质盐和可选的添加剂。根据本申请的电解液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，电解质盐可以是锂盐、钠盐等。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(LiPF 6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)。在一些实施例中，钠盐包括，但不限于：NaClO 4、NaPF 6、NaBF 4、Na(FSO 2) 2N、Na(CF 3SO 2) 2N、Na(C 2F 5SO 2) 2N、NaCF 3SO 3、NaSbF 6、NaBC 4O 8、NaFSI、NaTFSI、低级脂肪族羧酸钠盐、NaAlCl 4、NaPO 2F 2或Na 2PO 3F中的至少一种。
在一些实施例中，本申请的电化学装置包括，但不限于：所有种类的一次电池、二次电池或电容。在一些实施例中，电化学装置是锂二次电池。在一些实施例中，锂二次电池包括，但不限于：锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。在一些实施例中，电化学装置是钠离子电池。
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。
实施例及对比例
1、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(H 2O)作为溶剂，调配成为固含量为0.7的浆料，并搅拌均匀。将浆料均匀涂覆在负极集流体铜箔上，极片上有效物质的重量为95g/m 2。110℃条件下烘干，得到负极极片。以上步骤完成后，即已完成负极极片的单面涂布。之后，以完全一致的方法，在该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。完成涂布后，将负极极片冷压至1.7g/cm 3的压实密度，即完成了负极极片的全部制备流程。
2、正极极片的制备
将正极活性材料钴酸锂(LiCoO 2)、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N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为0.75的浆料，并搅拌均匀。将浆料均匀涂覆在正极集流体铝箔上，极片上有效物质的重量为180g/m 2。90℃条件下烘干，得到正极极片。以上步骤完成后，即已完成正极极片的单面涂布。之后，以完全一致的方法，在该极片背面也完成这些步骤，即得到双面涂布完成的正极极片。完成涂布后，将正极极片冷压至4.1g/cm 3的压实密度，即完成了正极极片的全部制备流程。
3、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)以质量比EC:EMC:DEC＝30:50:20混合，然后向有机溶剂中加入锂盐六氟磷酸锂(LiPF 6)溶解并混合均匀，得到锂盐的浓度为1.15M的电解液。
4、锂离子电池的制备
选用厚度15μm的聚乙烯(PE)作为隔离膜，将正极极片、隔离膜、负极极片按照顺 序叠好，使隔离膜处于正负极之间以起到隔离的作用，然后将叠好的极片和隔离膜卷成电极组件，然后对电极组件进行注液，对注液完成的电极组件进行封装。具体地，优先涂覆树脂前驱体(具体种类见下表)，经过固化后形成树脂层(即封闭层)，然后将无机物(具体种类见下表)使用气相沉积的方式蒸镀在树脂层的表面以及可选的将树脂前驱体(具体种类见下表)涂覆在无机物形成的层的表面，形成阻隔层。将封装后的电极组件，进行化成(0.02C恒流充电到3.3V，再以0.1C恒流充电到3.6V)等操作后，得到软包锂离子电池。
测试方法
1、水蒸气渗透速率测试
选用陶瓷剪刀小心拆开成品电池，剥离电极组件与封装膜，并取下至少1平方厘米尺寸的封装膜。同时准备直径为10cm的铝塑膜，该铝塑膜至少有4个0.5平方厘米破孔缺陷。用双面胶将成品电池的封装膜贴到铝塑膜破孔区域上，再参照国标《GB/T 21529-2008》进行测试。
2、X-ray CT
将电池转移至配备X射线电子计算机断层扫描(X-Ray CT，型号：GE Phoenix m300)腔体内，对电池进行扫描。随后使用设备配套的软件对电池扫描后的图像进行计算合成处理。可对处理后的图像对电池做任意截面的截取，即得到合成的X-ray CT截面图像。
注意在选取截面图像过程时，避免截取的图像中电池最外侧包含极耳的区域。截取所得图像应调整亮度，直至可以区分封装体的轮廓。
3、光学显微镜观察封装体轮廓
使用环氧树脂将电池进行完整包埋，随后将包埋后的电池放置液氮氛围下，对电池进行脆断处理(电池脆断位置的最外侧不含极耳)，然后使用冷冻超薄切片技术将断面断口做平整处理，即可获得适合光学显微镜观察的样品。
将上述样品置于光学显微镜(型号：Olympus BX53M)下，调整焦距至封装体清晰位置，选取合适的放大倍数的显微镜镜头，使用图像拼接的功能得到完整的断面光学显微图像。
4、EDS
使用环氧树脂将电池进行完整包埋，随后将包埋后的电池放置液氮氛围下，对电池进行脆断处理(电芯脆断位置的最外侧不含极耳，使用冷冻超薄切片技术将断面做平整处理 效果更佳)，并取封装膜区域样品转移至扫描电镜(SEM)腔体内，即可得到用于扫描电镜分析的样品。
将样品在SEM下观察，在合适的倍率下利用X射线能谱分析(EDS)进行数据采集，获得封装膜区域的元素含量。采集至少3处不同位置，取平均值。
5、电池的能量密度
室温(25℃±2℃)环境下，将电池静置不小于30分钟；按照出货规定的充电方式充电至出货规定的截止条件(充电时间不大于8h)；静置不小于30分钟，计量放电能量E(以Wh计)；用千分尺或游标卡尺测量锂离子电池的长宽高方向的最大值，计量体积V(以L计)；电池放电的体积能量密度VED(Wh/L)＝E/V。
6、电池的循环容量保持率
将电池在25±3℃下静置30分钟，接通外部电路，以0.5C恒定电流充电至4.4V，然后以4.4V恒定电压充电至电流0.05C，然后以0.2C电流放电至3.0V，记录放电容量为Q1。重复上述步骤500次，记录放电容量为Q500，则25℃循环500圈的容量保持率：
η(％)＝Q500/Q1×100％
测试结果
表1
Figure PCTCN2022084460-appb-000001
表1中体现了不同封装方式对体积能量密度的影响，对比例1和对比例2为传统软包或金属壳封装，实施例1为涂覆封装。其中，涂覆封装相比于传统的封装方式，锂离子电池能量密度提升大于15％。
表2
Figure PCTCN2022084460-appb-000002
表2体现了不同阻隔层构成对电池循环性能的影响。对比例3所选材料不包含无机阻隔层，水气渗透率为0.10015g/(m 2·天)，因此循环容量衰减较快。实施例2和实施例3采用了原子层沉积单层或双层氧化铝的阻隔工艺，水气渗透率较低，循环寿命相比于对比例3提升大于30％。
表3
Figure PCTCN2022084460-appb-000003
注：实施例3-1至实施例3-5的电池制备以及其余参数与实施例1一致，不同之处仅在于阻隔层材料。
表3中体现了不同无机阻隔材料对电池循环性能的影响，实施例3-1和实施例3-2为纯金属，实施例3-3和实施例3-4为无机氧化物，实施例3-5金属+无机氧化物的复合结构。其中，金属+无机氧化物的复合结构对电池循环性能的提升显著。
表4
Figure PCTCN2022084460-appb-000004
注：实施例4-1至实施例4-2的电池制备以及其余参数与实施例3一致，不同之处仅在于阻隔层材料和结构。
表4体现不同阻隔层结构对电池循环性能的影响，实施例4-1和4-2为无机层+有机层的叠层结构，实施例4-3为无机层+有机层+无机层的3复合叠层架构，相对于单层的无机阻隔层，循环性能提升5％以上。
表5
Figure PCTCN2022084460-appb-000005
注：实施例5-1至实施例5-3的电池制备以及其余参数与实施例3一致，不同之处仅 在于阻隔层材料、结构和厚度。
表5体现了不同阻隔层厚度对电池循环性能的影响，实施例5-1选用了较薄的无机阻隔层，能量密度相对较高，循环性能相对于更厚阻隔层的厚的实施例5-2和5-3，受到一定影响。因此，优选无机层的厚度≥10nm。
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、原理及范的情况下对实施例进行改变，替代和修改。

Claims (10)

  1. 一种电化学装置，包括电极组件和用于封装所述电极组件的封装膜，所述封装膜包括第一层和第二层，所述第一层和所述第二层各自呈闭合形态，其中，所述封装膜的水蒸气渗透速率WVTR≤0.001g/(m 2·天)。
  2. 根据权利要求1所述的电化学装置，其中，所述第一层和所述第二层中，各自金属元素的质量含量占比小于80％。
  3. 根据权利要求1所述的电化学装置，其中，通过将第一层原料涂覆于所述电极组件表面，得到所述第一层。
  4. 根据权利要求1所述的电化学装置，其中，所述第二层包括无机层和可选的有机聚合物层。
  5. 根据权利要求1所述的电化学装置，其中，所述第二层包括交替的无机层和有机聚合物层。
  6. 根据权利要求4或5所述的电化学装置，其中，所述无机层的厚度≥1nm，所述有机聚合物层的厚度≥1μm。
  7. 根据权利要求4或5所述的电化学装置，其中，所述无机层包括金属、无机氧化物或氮化物中的至少一种；和/或
    所述有机聚合物层包括树脂。
  8. 根据权利要求1所述的电化学装置，其中，所述封装膜还包括第三层，所述第一层与所述电极组件相接触，所述第二层设置于所述第三层与所述第一层之间。
  9. 根据权利要求8所述的电化学装置，其中，所述第一层包括树脂，和/或所述第三层包括纤维和树脂。
  10. 一种电子装置，包括权利要求1至9中任一项所述的电化学装置。
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