WO2022195716A1 - Separator, lithium ion secondary battery, and methods for producing same - Google Patents

Separator, lithium ion secondary battery, and methods for producing same Download PDF

Info

Publication number
WO2022195716A1
WO2022195716A1 PCT/JP2021/010591 JP2021010591W WO2022195716A1 WO 2022195716 A1 WO2022195716 A1 WO 2022195716A1 JP 2021010591 W JP2021010591 W JP 2021010591W WO 2022195716 A1 WO2022195716 A1 WO 2022195716A1
Authority
WO
WIPO (PCT)
Prior art keywords
separator
negative electrode
lithium
layer
ion secondary
Prior art date
Application number
PCT/JP2021/010591
Other languages
French (fr)
Japanese (ja)
Inventor
紘揮 三國
直人 黒田
Original Assignee
昭和電工マテリアルズ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 昭和電工マテリアルズ株式会社 filed Critical 昭和電工マテリアルズ株式会社
Priority to PCT/JP2021/010591 priority Critical patent/WO2022195716A1/en
Priority to TW111109396A priority patent/TW202249339A/en
Publication of WO2022195716A1 publication Critical patent/WO2022195716A1/en

Links

Images

Classifications

    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon 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
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material

Definitions

  • the present invention relates to separators, lithium-ion secondary batteries, and methods of manufacturing these.
  • a separator is placed between the positive electrode and the negative electrode.
  • the separator is required to have ion permeability while maintaining electrical insulation between the positive electrode and the negative electrode.
  • Polyolefin-based porous sheets are generally used as such separators.
  • the polyolefin-based porous sheet also has a shutdown function that closes the pores and stops the permeation of ions when the battery overheats.
  • Patent Document 1 discloses a polyolefin microporous membrane having high process transportability and battery safety when used as a battery separator.
  • lithium metal which has a high theoretical capacity and a low electrode potential
  • lithium metal which has a high theoretical capacity and a low electrode potential
  • lithium dendrites tend to grow with charging and discharging, and as a result, the characteristics of secondary batteries such as cycle characteristics tend to deteriorate, and short circuits tend to occur. be.
  • the present invention provides a separator that can improve the cycle characteristics of a lithium ion secondary battery using lithium metal as a negative electrode material, a lithium ion secondary battery using the separator, and a method for producing these. With the goal.
  • the present inventors have found that a separator having a specific layer on the surface of a porous sheet is superior to a separator made of only the porous sheet, which uses lithium metal as a negative electrode material. They have found that the cycle characteristics of ion secondary batteries can be improved.
  • the present invention provides the following [1] to [24].
  • a porous sheet comprising a layer provided on at least one side of the porous sheet and containing a lithium salt and a polymer; separator.
  • a method for producing a separator comprising the step of applying a composition containing a lithium salt and a polymer on at least one surface of a porous sheet to form a layer containing the lithium salt and the polymer.
  • the method for producing a separator according to [10] wherein in the above step, the composition is applied only on one surface of the porous sheet.
  • the method for producing a separator according to [10], wherein in the above steps, the composition is applied to one side and the other side of the porous sheet.
  • the separator which can improve the cycling characteristics of the lithium ion secondary battery using lithium metal as negative electrode material, the lithium ion secondary battery using the said separator, and the manufacturing method of these are provided. can be done.
  • FIG. 1 is a schematic cross-sectional view showing a separator according to one embodiment
  • FIG. 1 is a perspective view showing a lithium ion secondary battery according to one embodiment
  • FIG. 3 is an exploded perspective view showing an electrode group of the lithium ion secondary battery shown in FIG. 2;
  • FIG. 1 is a schematic cross-sectional view showing a separator according to one embodiment.
  • the separator 1A(1) includes a porous sheet 2 and a layer 3 provided only on one surface (one main surface) of the porous sheet 2.
  • the separator 1B(1) is provided on the porous sheet 2 and on one surface and the other surface (the other main surface) of the porous sheet 2. a layer 3;
  • the porous sheet 2 is a sheet that has many pores and is permeable to ions.
  • the material of the porous sheet 2 is not particularly limited, and may contain materials used for known lithium-ion secondary battery separators.
  • the porous sheet 2 contains, for example, resins, inorganic substances, and the like.
  • the porous sheet 2 preferably contains a polyolefin such as polyethylene or polypropylene from the viewpoint of being stable with respect to the electrolytic solution and being excellent in liquid retention.
  • the porous sheet 2 may be, for example, a sheet in which a fibrous or particulate inorganic material is adhered to a thin-film substrate such as nonwoven fabric, woven fabric, or microporous film.
  • the thickness of the porous sheet 2 is preferably 5 ⁇ m or more, 10 ⁇ m or more, or 15 ⁇ m or more from the viewpoint of ensuring insulation between the positive electrode and the negative electrode, and preferably 50 ⁇ m or less and 40 ⁇ m from the viewpoint of suppressing an increase in electrical resistance. or less, or 30 ⁇ m or less.
  • the layer 3 is at least part of the surface of the porous sheet 2 (one surface of the separator 1A in FIG. 1(a), one surface and the other surface of the separator 1B in FIG. 1(b); the same applies hereinafter). are placed in The layer 3 may be arranged so as to cover part of the surface of the porous sheet 2 , or may be arranged so as to cover the entire surface of the porous sheet 2 . Components (details of which will be described later) that constitute the layer 3 may also exist in the pores of the porous sheet 2 .
  • the thickness of the layer 3 may be, for example, 0.1 ⁇ m or more, 0.5 ⁇ m or more, or 1 ⁇ m or more, and from the viewpoint of further improving the cycle characteristics of the lithium ion secondary battery, it is preferably 5 ⁇ m or more, and more preferably. is 6 ⁇ m or more, 8 ⁇ m or more, or 10 ⁇ m or more, and more preferably 12 ⁇ m or more, 14 ⁇ m or more, or 15 ⁇ m or more.
  • the thickness of the layer 3 is preferably 30 ⁇ m or less, 25 ⁇ m or less, or 20 ⁇ m or less from the viewpoint of suppressing an increase in electrical resistance.
  • Layer 3 contains a lithium salt and a polymer. Since the lithium salt has a higher reduction potential than lithium metal, when the separator 1 is used in a lithium ion secondary battery, the layer 3 containing the lithium salt acts as a protective layer that suppresses the growth of lithium dendrites, resulting in , the cycle characteristics of the lithium-ion secondary battery are considered to be improved.
  • a known lithium salt can be used as the lithium salt.
  • a lithium salt may be a salt of a lithium cation with any anion.
  • the anion may be an organic anion or an inorganic anion.
  • the lithium salt is preferably solid at normal temperature and normal pressure (eg, at least at atmospheric pressure and 30° C.). In this case, it becomes easier to retain the lithium salt in the layer 3 .
  • Examples of lithium salts include LiNO 3 , LiNO 2 , LiB(C 2 O 4 ) 2 , LiBF 2 (C 2 O 4 ), Li 2 CO 3 and the like.
  • Layer 3 contains one or more of these lithium salts, preferably LiNO 3 .
  • the content of the lithium salt is preferably 5% by mass or more, 10% by mass or more, or 15% by mass or more based on the total mass of the layer 3. Yes, for example, it may be 80% by mass or less, 70% by mass or less, or 60% by mass or less.
  • the type of polymer is not particularly limited.
  • the polymer may be, for example, a polymer capable of retaining lithium salts in layer 3 .
  • the polymer is, for example, one or more selected from the group consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, methyl methacrylate, styrene, and butadiene as monomer units. It may be a polymer comprising
  • the polymer contains vinylidene fluoride as a monomer unit. In another embodiment, the polymer comprises hexafluoropropylene as monomer units. In yet another embodiment, the polymer comprises vinylidene fluoride and hexafluoropropylene as monomeric units.
  • Polymers include, for example, homopolymers containing only polyvinylidene fluoride as monomer units (polyvinylidene fluoride), copolymers containing vinylidene fluoride and hexafluoropropylene as monomer units (vinylidene fluoride-tetrafluoroethylene copolymer), styrene and It may be a copolymer containing butadiene as a monomer unit (styrene/butadiene copolymer).
  • the polymer is preferably a vinylidene fluoride-tetrafluoroethylene copolymer. In this case, since the layer 3 is swollen by the electrolyte, the interfacial resistance between the separator 1 and the positive or negative electrode can be reduced.
  • the polymer content is preferably 20% by weight or more, 30% by weight or more, or 40% by weight or more, for example 95% by weight or less, 90% by weight or less, or 85% by weight or less. % by mass or less.
  • the ratio of the lithium salt content to the polymer content is preferably 0.05 or more, 0.1 or more, or 0.2 or more, and may be, for example, 4.0 or less, 3.0 or less, or 2.0 or less.
  • Another embodiment of the present invention is a step of applying a composition containing a lithium salt and a polymer on at least one surface of the porous sheet 2 to form a layer 3 containing a lithium salt and a polymer (formation step).
  • the composition is applied to only one side of the porous sheet 2 during the forming process.
  • the composition is applied on one side and the other side of the porous sheet 2 in the forming step.
  • the lithium salt and polymer in the composition As the lithium salt and polymer in the composition, the lithium salt and polymer used for the layer 3 described above can be used.
  • the content of the lithium salt is preferably 1% by mass or more, 2% by mass or more, or 3% by mass or more, based on the total mass of the composition, for example, 20% by mass or less, 15% by mass or less, or 10% by mass. % or less.
  • the polymer content is preferably 3% by mass or more, 4% by mass or more, or 5% by mass or more, for example, 25% by mass or less, 20% by mass or less, or 15% by mass, based on the total mass of the composition.
  • the ratio of the lithium salt content to the polymer content in the composition is the ratio of the lithium salt content to the polymer content in the separator described above. It may be similar to ratio.
  • the composition may further contain a solvent in addition to the lithium salt and polymer.
  • the solvent is, for example, a solvent that dissolves the lithium salt.
  • the polymer may be dissolved in the solvent or dispersed in the solvent.
  • solvents include acetone, acetonitrile, ethyl acetate, diethyl ether, hexane, tetrahydrofuran, dimethylformamide, dimethylsulfoxide, 1-methyl-2-pyrrolidone (hereinafter also referred to as NMP), toluene and the like.
  • the content of the solvent may be, for example, 50% by mass or more, 60% by mass or more, or 70% by mass or more, and 95% by mass or less, Or it may be 90% by mass or less.
  • the forming step may form a layer by removing the solvent from the composition after applying the composition.
  • the composition is applied to at least part of the surface of the porous sheet 2.
  • the composition may be applied so as to partially cover the surface of the porous sheet 2 or may be applied so as to cover the entire surface of the porous sheet 2 .
  • the method of applying the composition is not particularly limited, but includes, for example, a doctor blade method, a dipping method, a spray method, and the like.
  • the method for removing the solvent is not particularly limited, but includes, for example, a method of volatilizing the solvent by heating and drying the separator coated with the composition.
  • the heating temperature may be 40° C. or higher, 50° C. or higher, or 60° C. or higher, and may be 120° C. or lower, 110° C. or lower, or 100° C. or lower.
  • the heating time may be 1 minute or more, 2 minutes or more, or 3 minutes or more, and may be 120 minutes or less, or 60 minutes or less.
  • FIG. 2 is a perspective view showing a lithium ion secondary battery according to one embodiment.
  • the lithium ion secondary battery 11 includes an electrode group 12 composed of a positive electrode, a negative electrode, and a separator, and a bag-shaped battery casing 13 that accommodates the electrode group 12 .
  • a positive electrode current collecting tab 14 and a negative electrode current collecting tab 15 are provided on the positive electrode and the negative electrode, respectively.
  • the positive electrode current collecting tab 14 and the negative electrode current collecting tab 15 protrude from the inside of the battery exterior body 13 to the outside so that the positive electrode and the negative electrode can be electrically connected to the outside of the lithium ion secondary battery 11, respectively.
  • the battery outer casing 13 is filled with an electrolytic solution (not shown).
  • the lithium ion secondary battery 11 may be a battery having a shape other than the so-called “laminate type” as described above (coin type, cylindrical type, laminated type, etc.).
  • the battery outer package 13 may be a container made of a laminated film, for example.
  • the laminated film may be, for example, a laminated film in which a resin film such as a polyethylene terephthalate (PET) film, a metal foil such as aluminum, copper, or stainless steel, and a sealant layer such as polypropylene are laminated in this order.
  • PET polyethylene terephthalate
  • metal foil such as aluminum, copper, or stainless steel
  • a sealant layer such as polypropylene
  • FIG. 3 is an exploded perspective view showing one embodiment of the electrode group 12 in the lithium ion secondary battery 11 shown in FIG.
  • the electrode group 12 includes a positive electrode 16, a separator 1, and a negative electrode 17 in this order.
  • the positive electrode 16 and the negative electrode 17 are arranged so that the surfaces on the positive electrode layer 19 side and the negative electrode material layer 21 side face the separator 1 , respectively.
  • the positive electrode 16 includes a positive electrode current collector 18 and a positive electrode material layer 19 provided on the positive electrode current collector 18 .
  • a positive current collector tab 14 is provided on the positive current collector 18 .
  • the positive electrode current collector 18 is made of, for example, aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, or the like.
  • the positive electrode current collector 18 may be made of aluminum, copper, or the like whose surface is treated with carbon, nickel, titanium, silver, or the like for the purpose of improving adhesiveness, conductivity, and oxidation resistance.
  • the thickness of the positive electrode current collector 18 is, for example, 1 to 50 ⁇ m in terms of electrode strength and energy density.
  • the positive electrode material layer 19 contains a positive electrode active material, a conductive agent, and a binder.
  • the thickness of the positive electrode material layer 19 is, for example, 20 to 200 ⁇ m.
  • the positive electrode active material may be, for example, lithium oxide.
  • the positive electrode active material may be, for example, lithium phosphate.
  • lithium phosphates include lithium manganese phosphate ( LiMnPO4 ), lithium iron phosphate ( LiFePO4 ), lithium cobalt phosphate ( LiCoPO4 ) and lithium vanadium phosphate ( Li3V2 ( PO4). 3 ).
  • the content of the positive electrode active material may be 80% by mass or more, 85% by mass or more, or 99% by mass or less based on the total amount of the positive electrode material layer.
  • the conductive agent may be carbon black such as acetylene black and ketjen black, or carbon materials such as graphite, graphene, and carbon nanotubes.
  • the content of the conductive agent may be, for example, 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more, and 50% by mass or less and 30% by mass or less, based on the total amount of the positive electrode material layer. , or 15% by mass or less.
  • Binders include resins such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber , isoprene rubber, butadiene rubber, ethylene-propylene rubber; Thermoplastic elastomers such as ethylene copolymers, styrene/isoprene/styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene/vinyl acetate copolymers, propylene/ ⁇ - Soft resins such as olefin copolymers; fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride
  • the content of the binder, based on the total amount of the positive electrode material layer may be, for example, 0.1% by mass or more, 1% by mass or more, or 1.5% by mass or more, and 30% by mass or less, or 20% by mass. or less, or 10% by mass or less.
  • the separator 1 is the separator as described above.
  • the layer 3 may be arranged so as to face the negative electrode 17 , and preferably the layer 3 is arranged so as to face the negative electrode 17 .
  • the layer 3 can more effectively suppress the growth of lithium dendrites and further improve the cycle characteristics of the lithium ion secondary battery.
  • the negative electrode 17 includes a negative electrode current collector 20 and a negative electrode material layer 21 provided on the negative electrode current collector 20 .
  • a negative electrode collector tab 15 is provided on the negative electrode collector 20 .
  • the negative electrode current collector 20 is made of copper, stainless steel, nickel, aluminum, titanium, baked carbon, conductive polymer, conductive glass, aluminum-cadmium alloy, or the like.
  • the negative electrode current collector 20 may be one in which the surface of copper, aluminum, or the like is treated with carbon, nickel, titanium, silver, or the like for the purpose of improving adhesiveness, conductivity, and resistance to reduction.
  • the thickness of the negative electrode current collector 20 is, for example, 1 to 50 ⁇ m in terms of electrode strength and energy density.
  • the negative electrode material layer 21 contains a negative electrode active material.
  • the negative electrode material layer 21 may be made of, for example, a negative electrode active material, and may contain a negative electrode active material and a binder.
  • the negative electrode active material is not particularly limited as long as it can absorb and release lithium ions.
  • Examples of negative electrode active materials include lithium metal, carbon materials, metal composite oxides, and oxides or nitrides of group 4 elements such as tin, germanium, and silicon.
  • the negative electrode active material may be one of these alone or a mixture of two or more thereof.
  • the negative electrode active material preferably contains lithium metal.
  • the lithium metal may be metallic lithium alone or a lithium alloy.
  • a lithium alloy may be, for example, an alloy of lithium and aluminum.
  • the shape of the negative electrode active material may be, for example, particulate.
  • the content of the negative electrode active material may be 80% by mass or more, 85% by mass or more, or 99% by mass or less based on the total amount of the negative electrode material layer.
  • the binder and its content may be the same as the binder and its content in the positive electrode material layer described above.
  • the negative electrode material layer 21 may further contain a thickener to adjust the viscosity.
  • the thickener is not particularly limited, but may be carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, salts thereof, and the like.
  • the thickener may be one of these alone or a mixture of two or more thereof.
  • the negative electrode material layer 21 contains a thickener
  • its content is not particularly limited.
  • the content of the thickener may be 0.1% by mass or more, preferably 0.2% by mass or more, based on the total amount of the negative electrode material layer. Preferably, it is 0.5% by mass or more.
  • the content of the thickener may be 5% by mass or less, preferably 3% by mass, based on the total amount of the negative electrode material layer, from the viewpoint of suppressing a decrease in battery capacity or an increase in resistance between negative electrode active materials. or less, more preferably 2% by mass or less.
  • the electrolytic solution contains, for example, an electrolyte salt and a non-aqueous solvent.
  • the electrolyte salt may be, for example, a lithium salt.
  • the lithium salt may be the same as or different from the lithium salt contained in layer 3 described above.
  • Lithium salts are, for example, LiPF6 , LiBF4, LiClO4, LiB( C6H5 ) 4 , LiCH3SO3 , CF3SO2OLi , LiN ( SO2F ) 2 ( Li[FSI], lithium bis fluorosulfonylimide), LiN(SO 2 CF 3 ) 2 (Li[TFSI], lithium bistrifluoromethanesulfonylimide), and LiN(SO 2 CF 2 CF 3 ) 2 at least one selected from the group consisting of good.
  • the lithium salt preferably contains LiPF 6 from the viewpoint of further improving solubility in solvents, charge/discharge characteristics, output characteristics, cycle characteristics, etc. of lithium ion secondary
  • the concentration of the electrolyte salt is preferably 0.5 mol/L or more, more preferably 0.7 mol/L or more, and still more preferably 0.7 mol/L or more, based on the total amount of the non-aqueous solvent, from the viewpoint of excellent charge-discharge characteristics. It is 8 mol/L or more, preferably 1.5 mol/L or less, more preferably 1.3 mol/L or less, and still more preferably 1.2 mol/L or less.
  • Non-aqueous solvents include, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ⁇ -butyl lactone, acetonitrile, 1,2-dimethoxyethane, dimethoxymethane, tetrahydrofuran, dioxolane, methylene chloride, methyl acetate, etc.
  • the non-aqueous solvent may be one of these alone or a mixture of two or more, preferably a mixture of two or more.
  • the electrolytic solution may further contain materials other than the electrolyte salt and the non-aqueous solvent.
  • Other materials may be, for example, heterocyclic compounds containing nitrogen, sulfur, or nitrogen and sulfur, cyclic carboxylic acid esters, fluorine-containing cyclic carbonates, compounds having unsaturated bonds in other molecules, and the like.
  • Another embodiment of the present invention includes a manufacturing step of manufacturing the separator 1 by the separator manufacturing method described above, and an arranging step of arranging the separator 1 between the positive electrode 16 and the negative electrode 17. This is a method for manufacturing a secondary battery.
  • the electrode group 12 is formed by the placement process.
  • the separator 1 When the separator 1 has the layer 3 only on one surface of the porous sheet 2 as shown in FIG. It may be positioned so as to face the negative electrode 17 , preferably the separator 1 is positioned so that the layer 3 faces the negative electrode 17 . In this case, the layer 3 can more effectively suppress the growth of lithium dendrites and further improve the cycle characteristics of the lithium ion secondary battery.
  • the composition may be applied on the negative electrode.
  • a method of coating to form a layer, and a method of coating the composition on a base material to form a layer, peeling off only the layer, and placing the layer between the negative electrode and the separator can be considered.
  • forming the layer 3 on the separator 1 and adopting a manufacturing method using the separator 1 is advantageous in terms of process and is preferable.
  • the method for manufacturing the lithium ion secondary battery 11 includes, for example, a step of obtaining the positive electrode 16, a step of obtaining the negative electrode 17, a step of housing the electrode group 12 in the battery outer package 13, and a step of adding the electrolyte to the battery outer package.
  • a step of infusing the body 13 may be provided.
  • the material used for the positive electrode layer 19 is dispersed in a dispersion medium using a kneader, a disperser, or the like to obtain a slurry-like positive electrode material, and then the positive electrode material is subjected to a doctor blade method or a dipping method.
  • the positive electrode 16 is obtained by coating the positive electrode current collector 18 by a spray method or the like, and then volatilizing the dispersion medium. After volatilizing the dispersion medium, if necessary, a compression molding step using a roll press may be provided.
  • the cathode material layer 19 may be formed as a cathode material layer having a multi-layer structure by performing the above-described processes from coating the cathode material to volatilizing the dispersion medium multiple times.
  • the dispersion medium may be water, NMP, or the like.
  • the negative electrode material layer 21 is formed on the negative electrode current collector 20 .
  • the negative electrode material layer 21 is made of a negative electrode active material
  • the negative electrode 17 is formed by pressing a negative electrode active material foil (for example, lithium metal foil) against the negative electrode current collector 20 to integrate it.
  • a negative electrode active material foil for example, lithium metal foil
  • the negative electrode material layer 21 is formed on the negative electrode current collector 20 by the same method as the step of obtaining the positive electrode 16 described above.
  • a negative electrode 17 can be obtained.
  • the electrode group 12 formed by the above-described process is housed in the battery exterior body 13 .
  • the electrolytic solution is injected into the battery outer casing 13.
  • the electrolytic solution can be prepared, for example, by first dissolving an electrolyte salt in a non-aqueous solvent and then dissolving other materials.
  • Example 2 A separator was produced in the same manner as in Example 1, except that the thickness of the layer was 10 ⁇ m.
  • Example 3 A separator was produced in the same manner as in Example 1, except that the layer thickness was changed to 15 ⁇ m.
  • Comparative example 1 The polyolefin-based porous sheet itself used in Examples 1 to 3 was used as a separator according to Comparative Example 1.
  • Comparative example 2 A separator (thickness: 40 ⁇ m) according to Comparative Example 2 was produced by laminating two polyolefin-based porous sheets used in Examples 1 to 3.
  • a positive electrode cut into a square of 13.5 cm 2 and a negative electrode cut into a square of 14.3 cm 2 were laminated with the separator according to each of the above Examples and Comparative Examples interposed therebetween to prepare an electrode group.
  • This electrode group was accommodated in a container (battery outer package) formed of an aluminum laminate film (trade name: aluminum laminate film, manufactured by Dai Nippon Printing Co., Ltd.).
  • a container battery outer package
  • aluminum laminate film trade name: aluminum laminate film, manufactured by Dai Nippon Printing Co., Ltd.
  • 1 mL of the electrolytic solution was added into the container, and the container was thermally welded to produce a lithium ion secondary battery for evaluation.
  • a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate containing 1 mol/L of LiPF 6 was used as the electrolyte.
  • Cycle characteristics of each lithium ion secondary battery produced were evaluated by measuring the discharge capacity retention rate at 100 cycles in a cycle test in which charge and discharge were repeated after the initial charge and discharge.
  • the charging pattern in an environment of 25° C., the lithium ion secondary battery was charged at a current value of 1 C to a maximum voltage of 4.2V, and then subjected to constant voltage charging at 4.2V.
  • a charge termination condition was a current value of 0.05C.
  • constant current discharge was performed at 1C to 2.7V, and the discharge capacity was obtained.

Abstract

One embodiment of the present invention provides a separator comprising a porous sheet and a layer that is provided upon at least one surface of the porous sheet and that contains a lithium salt and a polymer.

Description

セパレータ、リチウムイオン二次電池、及びこれらの製造方法SEPARATOR, LITHIUM-ION SECONDARY BATTERY, AND METHOD OF MANUFACTURING THESE
　本発明は、セパレータ、リチウムイオン二次電池、及びこれらの製造方法に関する。 The present invention relates to separators, lithium-ion secondary batteries, and methods of manufacturing these.
　リチウムイオン二次電池では、正極と負極との間にセパレータが配置されている。セパレータには、正極－負極間の電気絶縁性を保ちながら、イオン透過性を有することが求められる。このようなセパレータとして、ポリオレフィン系の多孔質シートが一般に用いられている。ポリオレフィン系の多孔質シートは、電池が異常発熱した場合に孔を閉塞させ、イオンの透過を停止するシャットダウン機能も有している。例えば、特許文献１には、電池用セパレータとして用いた場合に高い工程搬送性と電池安全性を有するポリオレフィン微多孔膜が開示されている。 In a lithium-ion secondary battery, a separator is placed between the positive electrode and the negative electrode. The separator is required to have ion permeability while maintaining electrical insulation between the positive electrode and the negative electrode. Polyolefin-based porous sheets are generally used as such separators. The polyolefin-based porous sheet also has a shutdown function that closes the pores and stops the permeation of ions when the battery overheats. For example, Patent Document 1 discloses a polyolefin microporous membrane having high process transportability and battery safety when used as a battery separator.
特開２０２１－１４５７２号公報JP 2021-14572 A
　一方で、リチウムイオン二次電池の電池特性を向上させるために、高理論容量かつ低電極電位を有するリチウム金属を負極材料として用いることが提案されている。しかし、負極にリチウム金属を用いた場合には、充放電に伴ってリチウムデンドライトが成長しやすく、その結果、サイクル特性等の二次電池の特性が悪化しやすい、短絡が生じやすいなどの課題がある。 On the other hand, in order to improve the battery characteristics of lithium-ion secondary batteries, it has been proposed to use lithium metal, which has a high theoretical capacity and a low electrode potential, as a negative electrode material. However, when lithium metal is used for the negative electrode, lithium dendrites tend to grow with charging and discharging, and as a result, the characteristics of secondary batteries such as cycle characteristics tend to deteriorate, and short circuits tend to occur. be.
　そこで、本発明は、負極材料としてリチウム金属を用いたリチウムイオン二次電池のサイクル特性を向上させることができるセパレータ、当該セパレータを用いたリチウムイオン二次電池、及びこれらの製造方法を提供することを目的とする。 Therefore, the present invention provides a separator that can improve the cycle characteristics of a lithium ion secondary battery using lithium metal as a negative electrode material, a lithium ion secondary battery using the separator, and a method for producing these. With the goal.
　本発明者らは、鋭意研究を行った結果、多孔質シートの面上に特定の層を設けたセパレータが、当該多孔質シートのみからなるセパレータに比べて、負極材料としてリチウム金属を用いたリチウムイオン二次電池のサイクル特性を向上させることができることを見出した。本発明は、いくつかの側面において、下記の［１］～［２４］を提供する。 As a result of intensive research, the present inventors have found that a separator having a specific layer on the surface of a porous sheet is superior to a separator made of only the porous sheet, which uses lithium metal as a negative electrode material. They have found that the cycle characteristics of ion secondary batteries can be improved. In some aspects, the present invention provides the following [1] to [24].
［１］　多孔質シートと、
　多孔質シートの少なくとも一方面上に設けられており、リチウム塩及びポリマを含有する層と、
を備えるセパレータ。
［２］　層が、多孔質シートの一方面上にのみ設けられている、［１］に記載のセパレータ。
［３］　層が、多孔質シートの一方面上及び他方面上に設けられている、［１］に記載のセパレータ。
［４］　多孔質シートが、ポリオレフィンを含有する、［１］～［３］のいずれかに記載のセパレータ。
［５］　リチウム塩が、硝酸リチウムである、［１］～［４］のいずれかに記載のセパレータ。
［６］　ポリマが、フッ化ビニリデンをモノマ単位として含む、［１］～［５］のいずれかに記載のセパレータ。
［７］　ポリマが、ヘキサフルオロプロピレンをモノマ単位として含む、［１］～［５］のいずれかに記載のセパレータ。
［８］　ポリマが、フッ化ビニリデン及びヘキサフルオロプロピレンをモノマ単位として含む、［１］～［５］のいずれかに記載のセパレータ。
［９］　層の厚みが、５μｍ以上である、［１］～［８］のいずれかに記載のセパレータ。
［１０］　多孔質シートの少なくとも一方面上に、リチウム塩及びポリマを含有する組成物を塗布して、リチウム塩及びポリマを含有する層を形成する工程を備える、セパレータの製造方法。
［１１］　上記工程において、多孔質シートの一方面上にのみ組成物を塗布する、［１０］に記載のセパレータの製造方法。
［１２］　上記工程において、多孔質シートの一方面上及び他方面上に組成物を塗布する、［１０］に記載のセパレータの製造方法。
［１３］　多孔質シートが、ポリオレフィンを含有する、［１０］～［１２］のいずれか］に記載のセパレータの製造方法。
［１４］　リチウム塩が、硝酸リチウムである、［１０］～［１３］のいずれかに記載のセパレータの製造方法。
［１５］　ポリマが、フッ化ビニリデンをモノマ単位として含む、［１０］～［１４］のいずれかに記載のセパレータの製造方法。
［１６］　ポリマが、ヘキサフルオロプロピレンをモノマ単位として含む、［１０］～［１４］のいずれかに記載のセパレータの製造方法。
［１７］　ポリマが、フッ化ビニリデン及びヘキサフルオロプロピレンをモノマ単位として含む、［１０］～［１４］のいずれかに記載のセパレータの製造方法。
［１８］　層の厚みが、５μｍ以上である、［１０］～［１７］のいずれかに記載のセパレータの製造方法。
［１９］　正極と、
　負極と、
　正極と負極との間に配置されている［１］～［９］のいずれかに記載のセパレータと、
を備える、リチウムイオン二次電池。
［２０］　セパレータは、層が負極と対向するように配置されている、［１９］に記載のリチウムイオン二次電池。
［２１］　負極が、リチウム金属を含有する、［１９］又は［２０］に記載のリチウムイオン二次電池。
［２２］　［１０］～［１８］のいずれかに記載の製造方法によりセパレータを製造する製造工程と、
　正極と負極との間にセパレータを配置する配置工程と、
を備える、リチウムイオン二次電池の製造方法。
［２３］　配置工程において、セパレータを、層が負極と対向するように配置する、［２２］に記載のリチウムイオン二次電池の製造方法。
［２４］　負極が、リチウム金属を含有する、［２２］又は［２３］に記載のリチウムイオン二次電池の製造方法。 [1] a porous sheet;
a layer provided on at least one side of the porous sheet and containing a lithium salt and a polymer;
separator.
[2] The separator according to [1], wherein the layer is provided only on one surface of the porous sheet.
[3] The separator according to [1], wherein the layer is provided on one side and the other side of the porous sheet.
[4] The separator according to any one of [1] to [3], wherein the porous sheet contains polyolefin.
[5] The separator according to any one of [1] to [4], wherein the lithium salt is lithium nitrate.
[6] The separator according to any one of [1] to [5], wherein the polymer contains vinylidene fluoride as a monomer unit.
[7] The separator according to any one of [1] to [5], wherein the polymer contains hexafluoropropylene as a monomer unit.
[8] The separator according to any one of [1] to [5], wherein the polymer contains vinylidene fluoride and hexafluoropropylene as monomer units.
[9] The separator according to any one of [1] to [8], wherein the layer has a thickness of 5 μm or more.
[10] A method for producing a separator, comprising the step of applying a composition containing a lithium salt and a polymer on at least one surface of a porous sheet to form a layer containing the lithium salt and the polymer.
[11] The method for producing a separator according to [10], wherein in the above step, the composition is applied only on one surface of the porous sheet.
[12] The method for producing a separator according to [10], wherein in the above steps, the composition is applied to one side and the other side of the porous sheet.
[13] The method for producing a separator according to any one of [10] to [12], wherein the porous sheet contains polyolefin.
[14] The method for producing a separator according to any one of [10] to [13], wherein the lithium salt is lithium nitrate.
[15] The method for producing a separator according to any one of [10] to [14], wherein the polymer contains vinylidene fluoride as a monomer unit.
[16] The method for producing a separator according to any one of [10] to [14], wherein the polymer contains hexafluoropropylene as a monomer unit.
[17] The method for producing a separator according to any one of [10] to [14], wherein the polymer contains vinylidene fluoride and hexafluoropropylene as monomer units.
[18] The method for producing a separator according to any one of [10] to [17], wherein the layer has a thickness of 5 μm or more.
[19] a positive electrode;
a negative electrode;
a separator according to any one of [1] to [9] disposed between the positive electrode and the negative electrode;
A lithium ion secondary battery.
[20] The lithium ion secondary battery according to [19], wherein the separator is arranged so that the layer faces the negative electrode.
[21] The lithium ion secondary battery of [19] or [20], wherein the negative electrode contains lithium metal.
[22] A manufacturing process for manufacturing a separator by the manufacturing method according to any one of [10] to [18];
An arrangement step of arranging a separator between the positive electrode and the negative electrode;
A method for manufacturing a lithium ion secondary battery, comprising:
[23] The method for producing a lithium ion secondary battery according to [22], wherein in the arranging step, the separator is arranged so that the layer faces the negative electrode.
[24] The method for producing a lithium ion secondary battery according to [22] or [23], wherein the negative electrode contains lithium metal.
　本発明によれば、負極材料としてリチウム金属を用いたリチウムイオン二次電池のサイクル特性を向上させることができるセパレータ、当該セパレータを用いたリチウムイオン二次電池、及びこれらの製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the separator which can improve the cycling characteristics of the lithium ion secondary battery using lithium metal as negative electrode material, the lithium ion secondary battery using the said separator, and the manufacturing method of these are provided. can be done.
一実施形態に係るセパレータを示す模式断面図である。1 is a schematic cross-sectional view showing a separator according to one embodiment; FIG. 一実施形態に係るリチウムイオン二次電池を示す斜視図である。1 is a perspective view showing a lithium ion secondary battery according to one embodiment; FIG. 図２に示したリチウムイオン二次電池の電極群を示す分解斜視図である。FIG. 3 is an exploded perspective view showing an electrode group of the lithium ion secondary battery shown in FIG. 2;
　以下、図面を適宜参照しながら、本発明の実施形態について詳細に説明する。なお、本発明は、以下の実施形態に限定されない。また、図面の説明において、同一の要素には同一の符号を付し、重複する説明は省略する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In addition, this invention is not limited to the following embodiment. In addition, in the description of the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.
［セパレータ］
　図１は、一実施形態に係るセパレータを示す模式断面図である。一実施形態において、図１（ａ）に示すように、セパレータ１Ａ（１）は、多孔質シート２と、多孔質シート２の一方面（一方の主面）上にのみ設けられた層３と、を備えている。他の一実施形態において、セパレータ１Ｂ（１）は、図１（ｂ）に示すように、多孔質シート２と、多孔質シート２の一方面上及び他方面（他方の主面）上に設けられた層３と、を備えている。 [Separator]
FIG. 1 is a schematic cross-sectional view showing a separator according to one embodiment. In one embodiment, as shown in FIG. 1(a), the separator 1A(1) includes a porous sheet 2 and a layer 3 provided only on one surface (one main surface) of the porous sheet 2. , is equipped with In another embodiment, as shown in FIG. 1B, the separator 1B(1) is provided on the porous sheet 2 and on one surface and the other surface (the other main surface) of the porous sheet 2. a layer 3;
　多孔質シート２は、多数の細孔を有し、イオンを透過することのできるシートである。多孔質シート２の材料は、特に制限されず、公知のリチウムイオン二次電池用セパレータに用いられる材料を含有していてよい。多孔質シート２は、例えば、樹脂、無機物等を含有する。 The porous sheet 2 is a sheet that has many pores and is permeable to ions. The material of the porous sheet 2 is not particularly limited, and may contain materials used for known lithium-ion secondary battery separators. The porous sheet 2 contains, for example, resins, inorganic substances, and the like.
　樹脂としては、オレフィン系ポリマ（ポリオレフィン）、フッ素系ポリマ、セルロース系ポリマ、ポリイミド、ナイロン等が挙げられる。多孔質シート２は、電解液に対して安定で、保液性に優れる観点から、好ましくは、ポリエチレン、ポリプロピレン等のポリオレフィンを含有する。 Examples of resins include olefin-based polymers (polyolefins), fluorine-based polymers, cellulose-based polymers, polyimides, and nylons. The porous sheet 2 preferably contains a polyolefin such as polyethylene or polypropylene from the viewpoint of being stable with respect to the electrolytic solution and being excellent in liquid retention.
　無機物としては、アルミナ、二酸化珪素等の酸化物、窒化アルミニウム、窒化珪素等の窒化物、硫酸バリウム、硫酸カルシウム等の硫酸塩が挙げられる。多孔質シート２は、例えば、不織布、織布、微多孔性フィルム等の薄膜状基材に、繊維状又は粒子状の無機物を付着させたシートであってよい。 Examples of inorganic substances include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate. The porous sheet 2 may be, for example, a sheet in which a fibrous or particulate inorganic material is adhered to a thin-film substrate such as nonwoven fabric, woven fabric, or microporous film.
　多孔質シート２の厚みは、正極及び負極の絶縁性を確保する観点から、好ましくは５μｍ以上、１０μｍ以上、又は１５μｍ以上であり、電気抵抗の上昇を抑制する観点から、好ましくは５０μｍ以下、４０μｍ以下、又は３０μｍ以下である。 The thickness of the porous sheet 2 is preferably 5 μm or more, 10 μm or more, or 15 μm or more from the viewpoint of ensuring insulation between the positive electrode and the negative electrode, and preferably 50 μm or less and 40 μm from the viewpoint of suppressing an increase in electrical resistance. or less, or 30 μm or less.
　層３は、多孔質シート２の面（図１（ａ）のセパレータ１Ａでは一方面、図１（ｂ）のセパレータ１Ｂでは一方面及び他方面のそれぞれの面。以下同様。）の少なくとも一部に配置されている。層３は、多孔質シート２の面の一部を覆うように配置されていてもよく、多孔質シート２の面を全て覆うように配置されていてもよい。層３を構成する成分（詳細は後述する）は、多孔質シート２の孔内にも存在していてよい。 The layer 3 is at least part of the surface of the porous sheet 2 (one surface of the separator 1A in FIG. 1(a), one surface and the other surface of the separator 1B in FIG. 1(b); the same applies hereinafter). are placed in The layer 3 may be arranged so as to cover part of the surface of the porous sheet 2 , or may be arranged so as to cover the entire surface of the porous sheet 2 . Components (details of which will be described later) that constitute the layer 3 may also exist in the pores of the porous sheet 2 .
　層３の厚みは、例えば、０．１μｍ以上、０．５μｍ以上、又は１μｍ以上であってよく、リチウムイオン二次電池のサイクル特性を更に向上させる観点から、好ましくは５μｍ以上であり、より好ましくは、６μｍ以上、８μｍ以上、又は１０μｍ以上であり、更に好ましくは、１２μｍ以上、１４μｍ以上、又は１５μｍ以上である。層３の厚みは、電気抵抗の上昇を抑制する観点から、好ましくは、３０μｍ以下、２５μｍ以下、又は２０μｍ以下である。 The thickness of the layer 3 may be, for example, 0.1 μm or more, 0.5 μm or more, or 1 μm or more, and from the viewpoint of further improving the cycle characteristics of the lithium ion secondary battery, it is preferably 5 μm or more, and more preferably. is 6 μm or more, 8 μm or more, or 10 μm or more, and more preferably 12 μm or more, 14 μm or more, or 15 μm or more. The thickness of the layer 3 is preferably 30 μm or less, 25 μm or less, or 20 μm or less from the viewpoint of suppressing an increase in electrical resistance.
　層３は、リチウム塩及びポリマを含有する。リチウム塩は、リチウム金属と比較して還元電位が高いため、セパレータ１をリチウムイオン二次電池に用いると、リチウム塩を含有する層３がリチウムデンドライトの成長を抑制する保護層として働き、その結果、リチウムイオン二次電池のサイクル特性が向上すると考えられる。 Layer 3 contains a lithium salt and a polymer. Since the lithium salt has a higher reduction potential than lithium metal, when the separator 1 is used in a lithium ion secondary battery, the layer 3 containing the lithium salt acts as a protective layer that suppresses the growth of lithium dendrites, resulting in , the cycle characteristics of the lithium-ion secondary battery are considered to be improved.
　リチウム塩としては、公知のリチウム塩を用いることができる。リチウム塩は、リチウムカチオンと、任意のアニオンとの塩であってよい。アニオンは、有機アニオンであってよく、無機アニオンであってよい。リチウム塩は、常温常圧下（例えば、少なくとも大気圧下かつ３０℃）において固体であることが好ましい。この場合、リチウム塩を層３に保持することが容易となる。リチウム塩としては、例えば、ＬｉＮＯ３、ＬｉＮＯ２、ＬｉＢ（Ｃ２Ｏ４）２、ＬｉＢＦ２（Ｃ２Ｏ４）、Ｌｉ２ＣＯ３等が挙げられる。層３は、これらのリチウム塩の１種又は２種以上を含有し、好ましくはＬｉＮＯ３を含有する。 A known lithium salt can be used as the lithium salt. A lithium salt may be a salt of a lithium cation with any anion. The anion may be an organic anion or an inorganic anion. The lithium salt is preferably solid at normal temperature and normal pressure (eg, at least at atmospheric pressure and 30° C.). In this case, it becomes easier to retain the lithium salt in the layer 3 . Examples of lithium salts include LiNO 3 , LiNO 2 , LiB(C 2 O 4 ) 2 , LiBF 2 (C 2 O 4 ), Li 2 CO 3 and the like. Layer 3 contains one or more of these lithium salts, preferably LiNO 3 .
　リチウム塩の含有量は、リチウムイオン二次電池のサイクル特性を更に向上させる観点から、層３の全質量を基準として、好ましくは、５質量％以上、１０質量％以上、又は１５質量％以上であり、例えば、８０質量％以下、７０質量％以下、又は６０質量％以下であってよい。 From the viewpoint of further improving the cycle characteristics of the lithium ion secondary battery, the content of the lithium salt is preferably 5% by mass or more, 10% by mass or more, or 15% by mass or more based on the total mass of the layer 3. Yes, for example, it may be 80% by mass or less, 70% by mass or less, or 60% by mass or less.
　ポリマの種類は、特に限定されない。ポリマは、例えば、リチウム塩を層３中に保持することができるポリマであってよい。ポリマは、例えば、四フッ化エチレン、フッ化ビニリデン、ヘキサフルオロプロピレン、アクリル酸、マレイン酸、エチルメタクリレート、メチルメタクリレート、スチレン、及びブタジエンからなる群より選ばれる１種又は２種以上をモノマ単位として含むポリマであってよい。 The type of polymer is not particularly limited. The polymer may be, for example, a polymer capable of retaining lithium salts in layer 3 . The polymer is, for example, one or more selected from the group consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, methyl methacrylate, styrene, and butadiene as monomer units. It may be a polymer comprising
　一実施形態において、ポリマは、フッ化ビニリデンをモノマ単位として含む。他の一実施形態において、ポリマは、ヘキサフルオロプロピレンをモノマ単位として含む。また他の一実施形態において、ポリマは、フッ化ビニリデン及びヘキサフルオロプロピレンをモノマ単位として含む。 In one embodiment, the polymer contains vinylidene fluoride as a monomer unit. In another embodiment, the polymer comprises hexafluoropropylene as monomer units. In yet another embodiment, the polymer comprises vinylidene fluoride and hexafluoropropylene as monomeric units.
　ポリマは、例えば、ポリフッ化ビニリデンのみをモノマ単位として含むホモポリマ（ポリフッ化ビニリデン）、フッ化ビニリデンとヘキサフルオロプロピレンとをモノマ単位として含むコポリマ（フッ化ビニリデン・テトラフルオロエチレン共重合体）、スチレンとブタジエンとをモノマ単位として含むコポリマ等（スチレン・ブタジエン共重合体）であってよい。 Polymers include, for example, homopolymers containing only polyvinylidene fluoride as monomer units (polyvinylidene fluoride), copolymers containing vinylidene fluoride and hexafluoropropylene as monomer units (vinylidene fluoride-tetrafluoroethylene copolymer), styrene and It may be a copolymer containing butadiene as a monomer unit (styrene/butadiene copolymer).
　ポリマは、好ましくは、フッ化ビニリデン・テトラフルオロエチレン共重合体である。この場合、層３が電解液によって膨潤するため、セパレータ１と正極又は負極との界面抵抗を低減することができる。 The polymer is preferably a vinylidene fluoride-tetrafluoroethylene copolymer. In this case, since the layer 3 is swollen by the electrolyte, the interfacial resistance between the separator 1 and the positive or negative electrode can be reduced.
　ポリマの含有量は、層３の全質量を基準として、好ましくは、２０質量％以上、３０質量％以上、又は４０質量％以上であり、例えば、９５質量％以下、９０質量％以下、又は８５質量％以下であってよい。 The polymer content, based on the total weight of layer 3, is preferably 20% by weight or more, 30% by weight or more, or 40% by weight or more, for example 95% by weight or less, 90% by weight or less, or 85% by weight or less. % by mass or less.
　ポリマの含有量に対するリチウム塩の含有量の比（リチウム塩の含有量（質量）／ポリマの含有量（質量））は、リチウムイオン二次電池のサイクル特性を更に向上させる観点から、好ましくは、０．０５以上、０．１以上、又は０．２以上であり、例えば、４．０以下、３．０以下、又は２．０以下であってよい。 The ratio of the lithium salt content to the polymer content (lithium salt content (mass)/polymer content (mass)) is preferably 0.05 or more, 0.1 or more, or 0.2 or more, and may be, for example, 4.0 or less, 3.0 or less, or 2.0 or less.
［セパレータの製造方法］
　本発明の他の一実施形態は、多孔質シート２の少なくとも一方面上に、リチウム塩及びポリマを含有する組成物を塗布して、リチウム塩及びポリマを含有する層３を形成する工程（形成工程）を備える、セパレータの製造方法である。一実施形態では、形成工程において、多孔質シート２の一方面上にのみ組成物を塗布する。また、他の一実施形態では、形成工程において、多孔質シート２の一方面上及び他方面上に組成物を塗布する。 [Separator manufacturing method]
Another embodiment of the present invention is a step of applying a composition containing a lithium salt and a polymer on at least one surface of the porous sheet 2 to form a layer 3 containing a lithium salt and a polymer (formation step). In one embodiment, the composition is applied to only one side of the porous sheet 2 during the forming process. In another embodiment, the composition is applied on one side and the other side of the porous sheet 2 in the forming step.
　組成物におけるリチウム塩及びポリマとしては、上述した層３に用いられるリチウム塩及びポリマを用いることができる。 As the lithium salt and polymer in the composition, the lithium salt and polymer used for the layer 3 described above can be used.
　リチウム塩の含有量は、組成物全質量を基準として、好ましくは１質量％以上、２質量％以上、又は３質量％以上であり、例えば、２０質量％以下、１５質量％以下、又は１０質量％以下であってよい。 The content of the lithium salt is preferably 1% by mass or more, 2% by mass or more, or 3% by mass or more, based on the total mass of the composition, for example, 20% by mass or less, 15% by mass or less, or 10% by mass. % or less.
　ポリマの含有量は、組成物全質量を基準として、好ましくは３質量％以上、４質量％以上、又は５質量％以上であり、例えば、２５質量％以下、２０質量％以下、又は１５質量％以下であってよい。 The polymer content is preferably 3% by mass or more, 4% by mass or more, or 5% by mass or more, for example, 25% by mass or less, 20% by mass or less, or 15% by mass, based on the total mass of the composition. may be:
　組成物におけるポリマの含有量に対するリチウム塩の含有量の比（リチウム塩の含有量（質量）／ポリマの含有量（質量））は、上述したセパレータにおけるポリマの含有量に対するリチウム塩の含有量の比と同様であってよい。 The ratio of the lithium salt content to the polymer content in the composition (lithium salt content (mass)/polymer content (mass)) is the ratio of the lithium salt content to the polymer content in the separator described above. It may be similar to ratio.
　組成物は、リチウム塩及びポリマに加えて、溶媒を更に含有していてもよい。溶媒は、例えばリチウム塩を溶解させる溶媒である。組成物において、ポリマは、溶媒に溶解した状態であってよく、溶媒に分散した状態であってもよい。溶媒としては、例えば、アセトン、アセトニトリル、酢酸エチル、ジエチルエーテル、ヘキサン、テトラヒドロフラン、ジメチルホルムアミド、ジメチルスルホキシド、１－メチル－２－ピロリドン（以下、ＮＭＰともいう。）、トルエン等が挙げられる。 The composition may further contain a solvent in addition to the lithium salt and polymer. The solvent is, for example, a solvent that dissolves the lithium salt. In the composition, the polymer may be dissolved in the solvent or dispersed in the solvent. Examples of solvents include acetone, acetonitrile, ethyl acetate, diethyl ether, hexane, tetrahydrofuran, dimethylformamide, dimethylsulfoxide, 1-methyl-2-pyrrolidone (hereinafter also referred to as NMP), toluene and the like.
　組成物が溶媒を含有する場合、溶媒の含有量は、組成物全質量を基準として、例えば、５０質量％以上、６０質量％以上、又は７０質量％以上であってよく、９５質量％以下、又は９０質量％以下であってよい。 When the composition contains a solvent, the content of the solvent, based on the total mass of the composition, may be, for example, 50% by mass or more, 60% by mass or more, or 70% by mass or more, and 95% by mass or less, Or it may be 90% by mass or less.
　組成物が溶媒を更に含有する場合、形成工程は、組成物を塗布した後で、当該組成物から溶媒を除去することにより、層を形成してもよい。 When the composition further contains a solvent, the forming step may form a layer by removing the solvent from the composition after applying the composition.
　組成物は、多孔質シート２の面の少なくとも一部に塗布される。組成物は、多孔質シート２の面の一部を覆うように塗布されてもよく、多孔質シート２の面を全て覆うように塗布されてもよい。 The composition is applied to at least part of the surface of the porous sheet 2. The composition may be applied so as to partially cover the surface of the porous sheet 2 or may be applied so as to cover the entire surface of the porous sheet 2 .
　組成物を塗布する方法としては、特に制限されないが、例えば、ドクターブレード法、ディッピング法、スプレー法等が挙げられる。 The method of applying the composition is not particularly limited, but includes, for example, a doctor blade method, a dipping method, a spray method, and the like.
　溶媒を除去する方法としては、特に制限されないが、例えば、組成物を塗布したセパレータを加熱乾燥させることにより、溶媒を揮発させる方法が挙げられる。この場合、加熱温度は、４０℃以上、５０℃以上、又は６０℃以上であってよく、１２０℃以下、１１０℃以下、又は１００℃以下であってよい。また、加熱時間は、１分間以上、２分間以上、又は３分間以上であってよく、１２０分間以下、又は６０分間以下であってよい。 The method for removing the solvent is not particularly limited, but includes, for example, a method of volatilizing the solvent by heating and drying the separator coated with the composition. In this case, the heating temperature may be 40° C. or higher, 50° C. or higher, or 60° C. or higher, and may be 120° C. or lower, 110° C. or lower, or 100° C. or lower. Also, the heating time may be 1 minute or more, 2 minutes or more, or 3 minutes or more, and may be 120 minutes or less, or 60 minutes or less.
［リチウムイオン二次電池］
　図２は、一実施形態に係るリチウムイオン二次電池を示す斜視図である。図２に示すように、リチウムイオン二次電池１１は、正極、負極及びセパレータから構成される電極群１２と、電極群１２を収容する袋状の電池外装体１３とを備えている。正極及び負極には、それぞれ正極集電タブ１４及び負極集電タブ１５が設けられている。正極集電タブ１４及び負極集電タブ１５は、それぞれ正極及び負極がリチウムイオン二次電池１１の外部と電気的に接続可能なように、電池外装体１３の内部から外部へ突き出している。電池外装体１３内には、電解液（図示せず）が充填されている。リチウムイオン二次電池１１は、上述したようないわゆる「ラミネート型」以外の形状の電池（コイン型、円筒型、積層型等）であってもよい。 [Lithium ion secondary battery]
FIG. 2 is a perspective view showing a lithium ion secondary battery according to one embodiment. As shown in FIG. 2 , the lithium ion secondary battery 11 includes an electrode group 12 composed of a positive electrode, a negative electrode, and a separator, and a bag-shaped battery casing 13 that accommodates the electrode group 12 . A positive electrode current collecting tab 14 and a negative electrode current collecting tab 15 are provided on the positive electrode and the negative electrode, respectively. The positive electrode current collecting tab 14 and the negative electrode current collecting tab 15 protrude from the inside of the battery exterior body 13 to the outside so that the positive electrode and the negative electrode can be electrically connected to the outside of the lithium ion secondary battery 11, respectively. The battery outer casing 13 is filled with an electrolytic solution (not shown). The lithium ion secondary battery 11 may be a battery having a shape other than the so-called "laminate type" as described above (coin type, cylindrical type, laminated type, etc.).
　電池外装体１３は、例えばラミネートフィルムで形成された容器であってよい。ラミネートフィルムは、例えば、ポリエチレンテレフタレート（ＰＥＴ）フィルム等の樹脂フィルムと、アルミニウム、銅、ステンレス鋼等の金属箔と、ポリプロピレン等のシーラント層とがこの順で積層された積層フィルムであってよい。 The battery outer package 13 may be a container made of a laminated film, for example. The laminated film may be, for example, a laminated film in which a resin film such as a polyethylene terephthalate (PET) film, a metal foil such as aluminum, copper, or stainless steel, and a sealant layer such as polypropylene are laminated in this order.
　図３は、図２に示したリチウムイオン二次電池１１における電極群１２の一実施形態を示す分解斜視図である。図３に示すように、電極群１２は、正極１６と、セパレータ１と、負極１７とをこの順に備えている。正極１６及び負極１７は、正極材層１９側及び負極材層２１側の面がそれぞれセパレータ１と対向するように配置されている。 FIG. 3 is an exploded perspective view showing one embodiment of the electrode group 12 in the lithium ion secondary battery 11 shown in FIG. As shown in FIG. 3, the electrode group 12 includes a positive electrode 16, a separator 1, and a negative electrode 17 in this order. The positive electrode 16 and the negative electrode 17 are arranged so that the surfaces on the positive electrode layer 19 side and the negative electrode material layer 21 side face the separator 1 , respectively.
　正極１６は、正極集電体１８と、正極集電体１８上に設けられた正極材層１９とを備えている。正極集電体１８には、正極集電タブ１４が設けられている。 The positive electrode 16 includes a positive electrode current collector 18 and a positive electrode material layer 19 provided on the positive electrode current collector 18 . A positive current collector tab 14 is provided on the positive current collector 18 .
　正極集電体１８は、例えば、アルミニウム、チタン、ステンレス、ニッケル、焼成炭素、導電性高分子、導電性ガラス等で形成されている。正極集電体１８は、接着性、導電性及び耐酸化性向上の目的で、アルミニウム、銅等の表面にカーボン、ニッケル、チタン、銀等で処理が施されたものであってもよい。正極集電体１８の厚みは、電極強度及びエネルギー密度の点から、例えば１～５０μｍである。 The positive electrode current collector 18 is made of, for example, aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, or the like. The positive electrode current collector 18 may be made of aluminum, copper, or the like whose surface is treated with carbon, nickel, titanium, silver, or the like for the purpose of improving adhesiveness, conductivity, and oxidation resistance. The thickness of the positive electrode current collector 18 is, for example, 1 to 50 μm in terms of electrode strength and energy density.
　正極材層１９は、一実施形態において、正極活物質と、導電剤と、結着剤とを含有する。正極材層１９の厚みは、例えば２０～２００μｍである。 In one embodiment, the positive electrode material layer 19 contains a positive electrode active material, a conductive agent, and a binder. The thickness of the positive electrode material layer 19 is, for example, 20 to 200 μm.
　正極活物質は、例えばリチウム酸化物であってよい。リチウム酸化物としては、例えば、ＬｉｘＣｏＯ２、ＬｉｘＮｉＯ２、ＬｉｘＭｎＯ２、ＬｉｘＣｏｙＮｉ１－ｙＯ２、ＬｉｘＣｏｙＭ１－ｙＯｚ、ＬｉｘＮｉ１－ｙＭｙＯｚ、ＬｉｘＭｎ２Ｏ４及びＬｉｘＭｎ２－ｙＭｙＯ４（各式中、Ｍは、Ｎａ、Ｍｇ、Ｓｃ、Ｙ、Ｍｎ、Ｆｅ、Ｃｏ、Ｃｕ、Ｚｎ、Ａｌ、Ｃｒ、Ｐｂ、Ｓｂ、Ｖ及びＢからなる群より選ばれる少なくとも１種の元素を示す（ただし、Ｍは、各式中の他の元素と異なる元素である）。ｘ＝０～１．２、ｙ＝０～０．９、ｚ＝２．０～２．３である。）が挙げられる。ＬｉｘＮｉ１－ｙＭｙＯｚで表されるリチウム酸化物は、ＬｉｘＮｉ１－（ｙ１＋ｙ２）Ｃｏｙ１Ｍｎｙ２Ｏｚ（ただし、ｘ及びｚは上述したものと同様であり、ｙ１＝０～０．９、ｙ２＝０～０．９であり、かつ、ｙ１＋ｙ２＝０～０．９である。）であってよく、例えばＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２、ＬｉＮｉ０．６Ｃｏ０．２Ｍｎ０．２Ｏ２、ＬｉＮｉ０．８Ｃｏ０．１Ｍｎ０．１Ｏ２であってよい。ＬｉｘＮｉ１－ｙＭｙＯｚで表されるリチウム酸化物は、ＬｉｘＮｉ１－（ｙ３＋ｙ４）Ｃｏｙ３Ａｌｙ４Ｏｚ（ただし、ｘ及びｚは上述したものと同様であり、ｙ３＝０～０．９、ｙ４＝０～０．９であり、かつ、ｙ３＋ｙ４＝０～０．９である。）であってよく、例えばＬｉＮｉ０．８Ｃｏ０．１５Ａｌ０．０５Ｏ２であってもよい。 The positive electrode active material may be, for example, lithium oxide. Examples of lithium oxides include Li x CoO 2 , Li x NiO 2 , Li x MnO 2 , Li x Co y Ni 1-y O 2 , Li x Co y M 1-y O z , Li x Ni 1- yM y O z , Li x Mn 2 O 4 and Li x Mn 2- y My O 4 (wherein M is Na, Mg, Sc, Y, Mn, Fe, Co, Cu, Zn, Al , Cr, Pb, Sb, V and B (wherein M is an element different from the other elements in each formula), x=0 to 1.2 , y=0 to 0.9 and z=2.0 to 2.3). Lithium oxide represented by Li x Ni 1-yM y O z is Li x Ni 1-(y1+y2) Co y1 Mn y2 O z (where x and z are the same as described above and y1= 0 to 0.9, y2=0 to 0.9, and y1+y2=0 to 0.9), for example LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiNi0.5Co0.2Mn0.3O2 , LiNi0.6Co0.2Mn0.2O2 , LiNi0.8Co0.1Mn0.1O2 . _ _ _ _ _ _ Lithium oxide represented by Li x Ni 1-yM y O z is Li x Ni 1-(y3+y4) Co y3 Al y4 O z (where x and z are the same as described above and y3= 0 to 0.9, y4=0 to 0.9, and y3+y4=0 to 0.9.), for example LiNi 0.8 Co 0.15 Al 0.05 O 2 There may be.
　正極活物質は、例えばリチウムのリン酸塩であってもよい。リチウムのリン酸塩としては、例えば、リン酸マンガンリチウム（ＬｉＭｎＰＯ４）、リン酸鉄リチウム（ＬｉＦｅＰＯ４）、リン酸コバルトリチウム（ＬｉＣｏＰＯ４）及びリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）が挙げられる。 The positive electrode active material may be, for example, lithium phosphate. Examples of lithium phosphates include lithium manganese phosphate ( LiMnPO4 ), lithium iron phosphate ( LiFePO4 ), lithium cobalt phosphate ( LiCoPO4 ) and lithium vanadium phosphate ( Li3V2 ( PO4). 3 ).
　正極活物質の含有量は、正極材層全量を基準として、８０質量％以上、又は８５質量％以上であってよく、９９質量％以下であってよい。 The content of the positive electrode active material may be 80% by mass or more, 85% by mass or more, or 99% by mass or less based on the total amount of the positive electrode material layer.
　導電剤は、アセチレンブラック、ケッチェンブラック等のカーボンブラック、黒鉛、グラフェン、カーボンナノチューブなどの炭素材料であってよい。導電剤の含有量は、正極材層全量を基準として、例えば、０．０１質量％以上、０．１質量％以上、又は１質量％以上であってよく、５０質量％以下、３０質量％以下、又は１５質量％以下であってよい。 The conductive agent may be carbon black such as acetylene black and ketjen black, or carbon materials such as graphite, graphene, and carbon nanotubes. The content of the conductive agent may be, for example, 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more, and 50% by mass or less and 30% by mass or less, based on the total amount of the positive electrode material layer. , or 15% by mass or less.
　結着剤は、例えば、ポリエチレン、ポリプロピレン、ポリエチレンテレフタレート、ポリメチルメタクリレート、ポリイミド、芳香族ポリアミド、セルロース、ニトロセルロース等の樹脂；ＳＢＲ（スチレン－ブタジエンゴム）、ＮＢＲ（アクリロニトリル－ブタジエンゴム）、フッ素ゴム、イソプレンゴム、ブタジエンゴム、エチレン－プロピレンゴム等のゴム；スチレン・ブタジエン・スチレンブロック共重合体又はその水素添加物、ＥＰＤＭ（エチレン・プロピレン・ジエン三元共重合体）、スチレン・エチレン・ブタジエン・エチレン共重合体、スチレン・イソプレン・スチレンブロック共重合体又はその水素添加物等の熱可塑性エラストマー；シンジオタクチック－１、２－ポリブタジエン、ポリ酢酸ビニル、エチレン・酢酸ビニル共重合体、プロピレン・α－オレフィン共重合体等の軟質樹脂；ポリフッ化ビニリデン、ポリテトラフルオロエチレン、フッ素化ポリフッ化ビニリデン、テトラフルオロエチレン・エチレン共重合体、フッ化ビニリデン・テトラフルオロエチレン共重合体等のフッ素含有樹脂；ニトリル基含有モノマをモノマ単位として有する樹脂；アルカリ金属イオン（例えばリチウムイオン）のイオン伝導性を有する高分子組成物などが挙げられる。 Binders include resins such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber , isoprene rubber, butadiene rubber, ethylene-propylene rubber; Thermoplastic elastomers such as ethylene copolymers, styrene/isoprene/styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene/vinyl acetate copolymers, propylene/α - Soft resins such as olefin copolymers; fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, tetrafluoroethylene/ethylene copolymers, and vinylidene fluoride/tetrafluoroethylene copolymers; A resin having a nitrile group-containing monomer as a monomer unit; a polymer composition having ion conductivity for alkali metal ions (eg, lithium ions);
　結着剤の含有量は、正極材層全量を基準として、例えば、０．１質量％以上、１質量％以上、又は１．５質量％以上であってよく、３０質量％以下、２０質量％以下、又は１０質量％以下であってよい。 The content of the binder, based on the total amount of the positive electrode material layer, may be, for example, 0.1% by mass or more, 1% by mass or more, or 1.5% by mass or more, and 30% by mass or less, or 20% by mass. or less, or 10% by mass or less.
　セパレータ１は、上述した通りのセパレータである。セパレータ１が、図１（ａ）に示すように、多孔質シート２の一方面上にのみ層３を備えている場合、セパレータ１は、層３が正極１６と対向するように配置されていてもよく、負極１７と対向するように配置されていてもよく、好ましくは、層３が負極１７と対向するように配置されている。この場合、層３によってより効果的にリチウムデンドライトの成長を抑制することができ、リチウムイオン二次電池のサイクル特性を更に向上させることができる。 The separator 1 is the separator as described above. When the separator 1 has the layer 3 only on one surface of the porous sheet 2 as shown in FIG. Alternatively, the layer 3 may be arranged so as to face the negative electrode 17 , and preferably the layer 3 is arranged so as to face the negative electrode 17 . In this case, the layer 3 can more effectively suppress the growth of lithium dendrites and further improve the cycle characteristics of the lithium ion secondary battery.
　負極１７は、負極集電体２０と、負極集電体２０上に設けられた負極材層２１とを備えている。負極集電体２０には、負極集電タブ１５が設けられている。 The negative electrode 17 includes a negative electrode current collector 20 and a negative electrode material layer 21 provided on the negative electrode current collector 20 . A negative electrode collector tab 15 is provided on the negative electrode collector 20 .
　負極集電体２０は、銅、ステンレス、ニッケル、アルミニウム、チタン、焼成炭素、導電性高分子、導電性ガラス、アルミニウム－カドミウム合金等で形成されている。負極集電体２０は、接着性、導電性、耐還元性向上の目的で、銅、アルミニウム等の表面にカーボン、ニッケル、チタン、銀等で処理が施されたものであってもよい。負極集電体２０の厚みは、電極強度及びエネルギー密度の点から、例えば１～５０μｍである。 The negative electrode current collector 20 is made of copper, stainless steel, nickel, aluminum, titanium, baked carbon, conductive polymer, conductive glass, aluminum-cadmium alloy, or the like. The negative electrode current collector 20 may be one in which the surface of copper, aluminum, or the like is treated with carbon, nickel, titanium, silver, or the like for the purpose of improving adhesiveness, conductivity, and resistance to reduction. The thickness of the negative electrode current collector 20 is, for example, 1 to 50 μm in terms of electrode strength and energy density.
　負極材層２１は、負極活物質を含有する。負極材層２１は、例えば、負極活物質からなっていてよく、負極活物質と結着剤とを含有していてもよい。 The negative electrode material layer 21 contains a negative electrode active material. The negative electrode material layer 21 may be made of, for example, a negative electrode active material, and may contain a negative electrode active material and a binder.
　負極活物質は、リチウムイオンを吸蔵及び放出可能な物質であれば特に制限されない。負極活物質としては、例えば、リチウム金属、炭素材料、金属複合酸化物、錫、ゲルマニウム、ケイ素等の第四族元素の酸化物又は窒化物などが挙げられる。負極活物質は、これらの１種単独又は２種以上の混合物であってよい。負極活物質は、好ましくはリチウム金属を含有する。リチウム金属は、金属リチウム単体又はリチウム合金であってよい。リチウム合金は、例えば、リチウムとアルミニウムとの合金であってよい。負極活物質がリチウム金属を含有する場合、リチウムデンドライトの成長が特に深刻な問題となるため、上述したセパレータ１を用いることによるリチウムイオン二次電池のサイクル特性向上の効果が顕著となる。負極活物質の形状は、例えば、粒子状であってよい。 The negative electrode active material is not particularly limited as long as it can absorb and release lithium ions. Examples of negative electrode active materials include lithium metal, carbon materials, metal composite oxides, and oxides or nitrides of group 4 elements such as tin, germanium, and silicon. The negative electrode active material may be one of these alone or a mixture of two or more thereof. The negative electrode active material preferably contains lithium metal. The lithium metal may be metallic lithium alone or a lithium alloy. A lithium alloy may be, for example, an alloy of lithium and aluminum. When the negative electrode active material contains lithium metal, the growth of lithium dendrites becomes a particularly serious problem. Therefore, the use of the above-described separator 1 significantly improves the cycle characteristics of the lithium ion secondary battery. The shape of the negative electrode active material may be, for example, particulate.
　負極活物質の含有量は、負極材層全量を基準として、８０質量％以上、又は８５質量％以上であってよく、９９質量％以下であってよい。 The content of the negative electrode active material may be 80% by mass or more, 85% by mass or more, or 99% by mass or less based on the total amount of the negative electrode material layer.
　結着剤及びその含有量は、上述した正極材層における結着剤及びその含有量と同様であってよい。 The binder and its content may be the same as the binder and its content in the positive electrode material layer described above.
　負極材層２１は、粘度を調節するために増粘剤を更に含有してもよい。増粘剤は、特に制限されないが、カルボキシメチルセルロース、メチルセルロース、ヒドロキシメチルセルロース、エチルセルロース、ポリビニルアルコール、酸化スターチ、リン酸化スターチ、カゼイン、これらの塩等であってよい。増粘剤は、これらの１種単独又は２種以上の混合物であってよい。 The negative electrode material layer 21 may further contain a thickener to adjust the viscosity. The thickener is not particularly limited, but may be carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, salts thereof, and the like. The thickener may be one of these alone or a mixture of two or more thereof.
　負極材層２１が増粘剤を含む場合、その含有量は特に制限されない。増粘剤の含有量は、負極材層の塗布性の観点からは、負極材層全量を基準として、０．１質量％以上であってよく、好ましくは０．２質量％以上であり、より好ましくは０．５質量％以上である。増粘剤の含有量は、電池容量の低下又は負極活物質間の抵抗の上昇を抑制する観点からは、負極材層全量を基準として、５質量％以下であってよく、好ましくは３質量％以下であり、より好ましくは２質量％以下である。 When the negative electrode material layer 21 contains a thickener, its content is not particularly limited. From the viewpoint of coating properties of the negative electrode material layer, the content of the thickener may be 0.1% by mass or more, preferably 0.2% by mass or more, based on the total amount of the negative electrode material layer. Preferably, it is 0.5% by mass or more. The content of the thickener may be 5% by mass or less, preferably 3% by mass, based on the total amount of the negative electrode material layer, from the viewpoint of suppressing a decrease in battery capacity or an increase in resistance between negative electrode active materials. or less, more preferably 2% by mass or less.
　電解液は、例えば、電解質塩と、非水溶媒とを含有する。電解質塩は、例えばリチウム塩であってよい。リチウム塩は、上述した層３に含有されているリチウム塩と同一でも異なっていてもよい。リチウム塩は、例えば、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＢ（Ｃ６Ｈ５）４、ＬｉＣＨ３ＳＯ３、ＣＦ３ＳＯ２ＯＬｉ、ＬｉＮ（ＳＯ２Ｆ）２（Ｌｉ［ＦＳＩ］、リチウムビスフルオロスルホニルイミド）、ＬｉＮ（ＳＯ２ＣＦ３）２（Ｌｉ［ＴＦＳＩ］、リチウムビストリフルオロメタンスルホニルイミド）、及びＬｉＮ（ＳＯ２ＣＦ２ＣＦ３）２からなる群より選ばれる少なくとも１種であってよい。リチウム塩は、溶媒に対する溶解性、リチウムイオン二次電池の充放電特性、出力特性、サイクル特性等に更に優れる観点から、好ましくはＬｉＰＦ６を含む。 The electrolytic solution contains, for example, an electrolyte salt and a non-aqueous solvent. The electrolyte salt may be, for example, a lithium salt. The lithium salt may be the same as or different from the lithium salt contained in layer 3 described above. Lithium salts are, for example, LiPF6 , LiBF4, LiClO4, LiB( C6H5 ) 4 , LiCH3SO3 , CF3SO2OLi , LiN ( SO2F ) 2 ( Li[FSI], lithium bis fluorosulfonylimide), LiN(SO 2 CF 3 ) 2 (Li[TFSI], lithium bistrifluoromethanesulfonylimide), and LiN(SO 2 CF 2 CF 3 ) 2 at least one selected from the group consisting of good. The lithium salt preferably contains LiPF 6 from the viewpoint of further improving solubility in solvents, charge/discharge characteristics, output characteristics, cycle characteristics, etc. of lithium ion secondary batteries.
　電解質塩の濃度は、充放電特性に優れる観点から、非水溶媒全量を基準として、好ましくは０．５ｍｏｌ／Ｌ以上であり、より好ましくは０．７ｍｏｌ／Ｌ以上であり、更に好ましくは０．８ｍｏｌ／Ｌ以上であり、また、好ましくは１．５ｍｏｌ／Ｌ以下であり、より好ましくは１．３ｍｏｌ／Ｌ以下であり、更に好ましくは１．２ｍｏｌ／Ｌ以下である。 The concentration of the electrolyte salt is preferably 0.5 mol/L or more, more preferably 0.7 mol/L or more, and still more preferably 0.7 mol/L or more, based on the total amount of the non-aqueous solvent, from the viewpoint of excellent charge-discharge characteristics. It is 8 mol/L or more, preferably 1.5 mol/L or less, more preferably 1.3 mol/L or less, and still more preferably 1.2 mol/L or less.
　非水溶媒は、例えば、エチレンカーボネート、プロピレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネート、γ－ブチルラクトン、アセトニトリル、１，２－ジメトキシエタン、ジメトキシメタン、テトラヒドロフラン、ジオキソラン、塩化メチレン、酢酸メチル等であってよい。非水溶媒は、これらの１種単独又は２種以上の混合物であってよく、好ましくは２種以上の混合物である。 Non-aqueous solvents include, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyl lactone, acetonitrile, 1,2-dimethoxyethane, dimethoxymethane, tetrahydrofuran, dioxolane, methylene chloride, methyl acetate, etc. can be The non-aqueous solvent may be one of these alone or a mixture of two or more, preferably a mixture of two or more.
　電解液は、電解質塩及び非水溶媒以外のその他の材料を更に含有してもよい。その他の材料は、例えば、窒素、硫黄、又は窒素及び硫黄を含有する複素環化合物、環状カルボン酸エステル、フッ素含有環状カーボネート、その他の分子内に不飽和結合を有する化合物等であってよい。 The electrolytic solution may further contain materials other than the electrolyte salt and the non-aqueous solvent. Other materials may be, for example, heterocyclic compounds containing nitrogen, sulfur, or nitrogen and sulfur, cyclic carboxylic acid esters, fluorine-containing cyclic carbonates, compounds having unsaturated bonds in other molecules, and the like.
［リチウムイオン二次電池の製造方法］
　本発明の他の一実施形態は、上述したセパレータの製造方法によりセパレータ１を製造する製造工程と、正極１６と負極１７との間にセパレータ１を配置する配置工程と、を備える、リチウムイオン二次電池の製造方法である。配置工程により、電極群１２が形成される。 [Method for producing lithium ion secondary battery]
Another embodiment of the present invention includes a manufacturing step of manufacturing the separator 1 by the separator manufacturing method described above, and an arranging step of arranging the separator 1 between the positive electrode 16 and the negative electrode 17. This is a method for manufacturing a secondary battery. The electrode group 12 is formed by the placement process.
　セパレータ１が、図１（ａ）に示すように、多孔質シート２の一方面上にのみ層３を備えている場合、配置工程では、セパレータ１を、層３が正極１６と対向するように配置してもよく、負極１７と対向するように配置してもよく、好ましくは、セパレータ１を、層３が負極１７と対向するように配置する。この場合、層３によってより効果的にリチウムデンドライトの成長を抑制することができ、リチウムイオン二次電池のサイクル特性を更に向上させることができる。 When the separator 1 has the layer 3 only on one surface of the porous sheet 2 as shown in FIG. It may be positioned so as to face the negative electrode 17 , preferably the separator 1 is positioned so that the layer 3 faces the negative electrode 17 . In this case, the layer 3 can more effectively suppress the growth of lithium dendrites and further improve the cycle characteristics of the lithium ion secondary battery.
　リチウムイオン二次電池において、負極上でのリチウムデンドライトの成長を抑制するために、リチウム塩及びポリマを含有する層を設ける場合、上述したセパレータ１を用いる方法以外にも、負極上に組成物を塗布して層を形成する方法、基材上に組成物を塗布して層を形成した後、当該層のみを剥離して負極とセパレータとの間に配置する方法が考えられる。しかし、負極上に組成物を塗布して層を形成する方法では、特に負極にリチウム金属を用いる場合、負極に対して高温加熱等の処理をすることは安全上好ましくないため、組成物に用いる溶媒選定等に制約がかかる。また、基材上に組成物を塗布して層を形成した場合は、層の剥離・移動時に層が破損するリスクが高くなる。そのため、上述したように、セパレータ１に層３を形成しておき、当該セパレータ１を用いる製造方法を採用することが、プロセス上有利であり、好ましい。 In a lithium ion secondary battery, when a layer containing a lithium salt and a polymer is provided in order to suppress the growth of lithium dendrites on the negative electrode, in addition to the method of using the separator 1 described above, the composition may be applied on the negative electrode. A method of coating to form a layer, and a method of coating the composition on a base material to form a layer, peeling off only the layer, and placing the layer between the negative electrode and the separator can be considered. However, in the method of forming a layer by applying a composition on the negative electrode, especially when lithium metal is used for the negative electrode, it is not preferable for safety to subject the negative electrode to a treatment such as high-temperature heating. Restrictions apply to solvent selection, etc. In addition, when a layer is formed by coating a composition on a substrate, the risk of damage to the layer increases when the layer is peeled off or moved. Therefore, as described above, forming the layer 3 on the separator 1 and adopting a manufacturing method using the separator 1 is advantageous in terms of process and is preferable.
　リチウムイオン二次電池１１の製造方法は、上述した工程に加えて、例えば、正極１６を得る工程、負極１７を得る工程、電極群１２を電池外装体１３に収容する工程、電解液を電池外装体１３に注液する工程を備えていてよい。 In addition to the above-described steps, the method for manufacturing the lithium ion secondary battery 11 includes, for example, a step of obtaining the positive electrode 16, a step of obtaining the negative electrode 17, a step of housing the electrode group 12 in the battery outer package 13, and a step of adding the electrolyte to the battery outer package. A step of infusing the body 13 may be provided.
　正極１６を得る工程では、正極材層１９に用いる材料を混練機、分散機等を用いて分散媒に分散させてスラリー状の正極材を得た後、この正極材をドクターブレード法、ディッピング法、スプレー法等により正極集電体１８上に塗布し、その後分散媒を揮発させることにより正極１６を得る。分散媒を揮発させた後、必要に応じて、ロールプレスによる圧縮成型工程が設けられてもよい。正極材層１９は、上述した正極材の塗布から分散媒の揮発までの工程を複数回行うことにより、多層構造の正極材層として形成されてもよい。分散媒は、水、ＮＭＰ等であってよい。 In the step of obtaining the positive electrode 16, the material used for the positive electrode layer 19 is dispersed in a dispersion medium using a kneader, a disperser, or the like to obtain a slurry-like positive electrode material, and then the positive electrode material is subjected to a doctor blade method or a dipping method. The positive electrode 16 is obtained by coating the positive electrode current collector 18 by a spray method or the like, and then volatilizing the dispersion medium. After volatilizing the dispersion medium, if necessary, a compression molding step using a roll press may be provided. The cathode material layer 19 may be formed as a cathode material layer having a multi-layer structure by performing the above-described processes from coating the cathode material to volatilizing the dispersion medium multiple times. The dispersion medium may be water, NMP, or the like.
　負極１７を得る工程では、負極集電体２０上に負極材層２１を形成する。例えば、負極材層２１が負極活物質からなる場合、負極１７を得る工程では、負極活物質の箔（例えばリチウム金属箔）を負極集電体２０に押し付けて一体化させることにより、負極１７を得ることができる。また、例えば、負極材層２１が負極活物質と結着剤とを含有する場合、上述した正極１６を得る工程と同様の方法で、負極集電体２０上に負極材層２１を形成して負極１７を得ることができる。 In the step of obtaining the negative electrode 17 , the negative electrode material layer 21 is formed on the negative electrode current collector 20 . For example, when the negative electrode material layer 21 is made of a negative electrode active material, in the step of obtaining the negative electrode 17, the negative electrode 17 is formed by pressing a negative electrode active material foil (for example, lithium metal foil) against the negative electrode current collector 20 to integrate it. Obtainable. Further, for example, when the negative electrode material layer 21 contains a negative electrode active material and a binder, the negative electrode material layer 21 is formed on the negative electrode current collector 20 by the same method as the step of obtaining the positive electrode 16 described above. A negative electrode 17 can be obtained.
　電極群１２を電池外装体１３に収容する工程では、上述した工程により形成した電極群１２を、電池外装体１３に収容する。 In the step of housing the electrode group 12 in the battery exterior body 13 , the electrode group 12 formed by the above-described process is housed in the battery exterior body 13 .
　電解液を電池外装体１３に注液する工程では、電解液を電池外装体１３に注入する。電解液は、例えば、電解質塩をはじめに非水溶媒に溶解させてから、その他の材料を溶解させることにより調製することができる。 In the step of injecting the electrolytic solution into the battery outer casing 13, the electrolytic solution is injected into the battery outer casing 13. The electrolytic solution can be prepared, for example, by first dissolving an electrolyte salt in a non-aqueous solvent and then dissolving other materials.
　以下、実施例に基づいて本発明を更に具体的に説明するが、本発明はこれらの実施例に何ら限定されるものではない。 The present invention will be described more specifically below based on examples, but the present invention is not limited to these examples.
（実施例１）
［組成物の調製］
　硝酸リチウム０．５質量部、ポリ（フッ化ビニリデン－ヘキサフルオロプロピレン）（フッ化ビニリデン／ヘキサフルオロプロピレン（質量比）＝９５／５）１．０質量部、及びアセトン８．５質量部を混合して、組成物を調製した。 (Example 1)
[Preparation of composition]
Mix 0.5 parts by mass of lithium nitrate, 1.0 part by mass of poly(vinylidene fluoride-hexafluoropropylene) (vinylidene fluoride/hexafluoropropylene (mass ratio) = 95/5), and 8.5 parts by mass of acetone to prepare a composition.
［セパレータの作製］
　得られた組成物を、ポリオレフィン系の多孔質シート（厚み２０μｍ、空孔率４５％）の一方面上にアプリケータを用いて塗布した後、６０℃で２０分間加熱乾燥させることにより、硝酸リチウム及びポリ（フッ化ビニリデン－ヘキサフルオロプロピレン）を含有する層（厚み５μｍ）を形成して、実施例１に係るセパレータを作製した。 [Preparation of separator]
The resulting composition was applied to one side of a polyolefin porous sheet (thickness: 20 μm, porosity: 45%) using an applicator, and then dried by heating at 60° C. for 20 minutes to obtain lithium nitrate. and a layer (5 μm thick) containing poly(vinylidene fluoride-hexafluoropropylene) was formed to prepare a separator according to Example 1.
（実施例２）
　実施例１において、層の厚みを１０μｍとした以外は、実施例１と同様にしてセパレータを作製した。 (Example 2)
A separator was produced in the same manner as in Example 1, except that the thickness of the layer was 10 μm.
（実施例３）
　実施例１において、層の厚みを１５μｍとした以外は、実施例１と同様にして、セパレータを作製した。 (Example 3)
A separator was produced in the same manner as in Example 1, except that the layer thickness was changed to 15 μm.
（比較例１）
　実施例１～３において用いたポリオレフィン系の多孔質シートそれ自体を、比較例１に係るセパレータとして用いた。 (Comparative example 1)
The polyolefin-based porous sheet itself used in Examples 1 to 3 was used as a separator according to Comparative Example 1.
（比較例２）
　実施例１～３において用いたポリオレフィン系の多孔質シートを２枚積層して、比較例２に係るセパレータ（厚み４０μｍ）を作製した。 (Comparative example 2)
A separator (thickness: 40 μm) according to Comparative Example 2 was produced by laminating two polyolefin-based porous sheets used in Examples 1 to 3.
［正極の作製］
　正極活物質としての層状型リチウム・ニッケル・マンガン・コバルト複合酸化物（９２．５質量％）に、導電剤としてのアセチレンブラック（ＡＢ）（５質量％）と、結着剤（２．５質量％）とを順次添加し、混合した。得られた混合物に対し、分散媒としてのＮＭＰを添加し、混練することによりスラリー状の正極材を調製した。この正極材を正極集電体としての厚み１５μｍのアルミニウム箔に均等かつ均質に所定量塗布した。その後、分散媒を揮発させてから、プレスすることにより密度２．６ｇ／ｃｍ３まで圧密化して、正極を得た。 [Preparation of positive electrode]
Layered lithium-nickel-manganese-cobalt composite oxide (92.5% by mass) as a positive electrode active material, acetylene black (AB) (5% by mass) as a conductive agent, and a binder (2.5% by mass) %) were sequentially added and mixed. NMP as a dispersion medium was added to the obtained mixture, and the mixture was kneaded to prepare a slurry positive electrode material. A predetermined amount of this positive electrode material was evenly and homogeneously applied to an aluminum foil having a thickness of 15 μm as a positive electrode current collector. Thereafter, after volatilizing the dispersion medium, the mixture was compressed to a density of 2.6 g/cm 3 by pressing to obtain a positive electrode.
［負極の作製］
　負極活物質としてのリチウム金属箔（厚み５００μｍの金属リチウム単体の箔）の表面を光沢が出るまで磨き、このリチウム金属箔を、負極集電体としての銅メッシュに、均等かつ均一に押し付けて一体化させることにより負極を得た。 [Preparation of negative electrode]
The surface of a lithium metal foil (500 μm thick metallic lithium simple substance foil) as a negative electrode active material is polished until it becomes glossy, and this lithium metal foil is evenly and uniformly pressed against a copper mesh as a negative electrode current collector to be integrated. A negative electrode was obtained by the reaction.
［リチウムイオン二次電池の作製］
　１３．５ｃｍ２の四角形に切断した正極電極と、更に１４．３ｃｍ２の四角形に切断した負極とを、上記の各実施例、比較例に係るセパレータを介して積層し、電極群を作製した。この電極群を、アルミニウム製のラミネートフィルム（商品名：アルミラミネートフィルム、大日本印刷株式会社製）で形成された容器（電池外装体）に収容した。次いで、容器の中に電解液を１ｍＬ添加し、容器を熱溶着させ、評価用のリチウムイオン二次電池を作製した。電解液としては、１ｍｏｌ／ＬのＬｉＰＦ６を含むエチレンカーボネート、ジメチルカーボネート及びジエチルカーボネートの混合溶液を使用した。 [Production of lithium ion secondary battery]
A positive electrode cut into a square of 13.5 cm 2 and a negative electrode cut into a square of 14.3 cm 2 were laminated with the separator according to each of the above Examples and Comparative Examples interposed therebetween to prepare an electrode group. This electrode group was accommodated in a container (battery outer package) formed of an aluminum laminate film (trade name: aluminum laminate film, manufactured by Dai Nippon Printing Co., Ltd.). Next, 1 mL of the electrolytic solution was added into the container, and the container was thermally welded to produce a lithium ion secondary battery for evaluation. A mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate containing 1 mol/L of LiPF 6 was used as the electrolyte.
［サイクル特性の評価］
　作製した各リチウムイオン二次電池について、初回充放電後に、充放電を繰り返すサイクル試験によって、１００サイクル時の放電容量維持率を測定することによりサイクル特性を評価した。充電パターンとしては、２５℃の環境下で、リチウムイオン二次電池を１Ｃの電流値で定電流充電を上限電圧４．２Ｖまで行い、続いて４．２Ｖで定電圧充電を行った。充電終止条件は、電流値０．０５Ｃとした。放電については、１Ｃで定電流放電を２．７Ｖまで行い、放電容量を求めた。この一連の充放電を１００サイクル繰返し、１サイクル目の充放電後の放電容量を１００％として、１００サイクル目の充放電後の放電容量の相対値（放電容量維持率（％））を求めた。各実施例及び比較例に係るセパレータを用いた場合の結果を表１に示す。 [Evaluation of cycle characteristics]
Cycle characteristics of each lithium ion secondary battery produced were evaluated by measuring the discharge capacity retention rate at 100 cycles in a cycle test in which charge and discharge were repeated after the initial charge and discharge. As for the charging pattern, in an environment of 25° C., the lithium ion secondary battery was charged at a current value of 1 C to a maximum voltage of 4.2V, and then subjected to constant voltage charging at 4.2V. A charge termination condition was a current value of 0.05C. As for the discharge, constant current discharge was performed at 1C to 2.7V, and the discharge capacity was obtained. This series of charging and discharging was repeated for 100 cycles, and the relative value of the discharging capacity after charging and discharging at the 100th cycle (discharge capacity retention rate (%)) was obtained, with the discharge capacity after charging and discharging at the 1st cycle being 100%. . Table 1 shows the results when the separators according to each example and comparative example were used.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１のとおり、実施例１～３に係るセパレータを用いた場合の放電容量維持率は、比較例１～２に係るセパレータを用いた場合と比較して高かった。また、実施例１～３に係るセパレータを比較すると、層の厚みが厚いほど、サイクル特性が良好であった。 As shown in Table 1, the discharge capacity retention rate when using the separators according to Examples 1-3 was higher than when using the separators according to Comparative Examples 1-2. Further, when the separators according to Examples 1 to 3 were compared, the thicker the layer, the better the cycle characteristics.
　１、１Ａ、１Ｂ…セパレータ、２…多孔質シート、３…層、１１…リチウムイオン二次電池、１２…電極群、１３…電池外装体、１４…正極集電タブ、１５…負極集電タブ、１６…正極、１７…負極、１８…正極集電体、１９…正極材層、２０…負極集電体、２１…負極材層。 DESCRIPTION OF SYMBOLS 1, 1A, 1B... Separator, 2... Porous sheet, 3... Layer, 11... Lithium-ion secondary battery, 12... Electrode group, 13... Battery exterior body, 14... Positive electrode current collecting tab, 15... Negative electrode current collecting tab , 16... positive electrode, 17... negative electrode, 18... positive electrode current collector, 19... positive electrode material layer, 20... negative electrode current collector, 21... negative electrode material layer.

Claims (24)

  1. 　多孔質シートと、
    　前記多孔質シートの少なくとも一方面上に設けられており、リチウム塩及びポリマを含有する層と、
    を備えるセパレータ。     a porous sheet;
    a layer provided on at least one surface of the porous sheet and containing a lithium salt and a polymer;
    separator.
  2. 　前記層が、前記多孔質シートの一方面上にのみ設けられている、請求項１に記載のセパレータ。 The separator according to claim 1, wherein the layer is provided only on one side of the porous sheet.
  3. 　前記層が、前記多孔質シートの一方面上及び他方面上に設けられている、請求項１に記載のセパレータ。 The separator according to claim 1, wherein the layer is provided on one side and the other side of the porous sheet.
  4. 　前記多孔質シートが、ポリオレフィンを含有する、請求項１～３のいずれか一項に記載のセパレータ。 The separator according to any one of claims 1 to 3, wherein the porous sheet contains polyolefin.
  5. 　前記リチウム塩が、硝酸リチウムである、請求項１～４のいずれか一項に記載のセパレータ。 The separator according to any one of claims 1 to 4, wherein the lithium salt is lithium nitrate.
  6. 　前記ポリマが、フッ化ビニリデンをモノマ単位として含む、請求項１～５のいずれか一項に記載のセパレータ。 The separator according to any one of claims 1 to 5, wherein the polymer contains vinylidene fluoride as a monomer unit.
  7. 　前記ポリマが、ヘキサフルオロプロピレンをモノマ単位として含む、請求項１～５のいずれか一項に記載のセパレータ。 The separator according to any one of claims 1 to 5, wherein the polymer contains hexafluoropropylene as a monomer unit.
  8. 　前記ポリマが、フッ化ビニリデン及びヘキサフルオロプロピレンをモノマ単位として含む、請求項１～５のいずれか一項に記載のセパレータ。 The separator according to any one of claims 1 to 5, wherein the polymer contains vinylidene fluoride and hexafluoropropylene as monomer units.
  9. 　前記層の厚みが、５μｍ以上である、請求項１～８のいずれか一項に記載のセパレータ。 The separator according to any one of claims 1 to 8, wherein the layer has a thickness of 5 μm or more.
  10. 　多孔質シートの少なくとも一方面上に、リチウム塩及びポリマを含有する組成物を塗布して、前記リチウム塩及び前記ポリマを含有する層を形成する工程を備える、セパレータの製造方法。 A method for producing a separator, comprising the step of applying a composition containing a lithium salt and a polymer on at least one surface of a porous sheet to form a layer containing the lithium salt and the polymer.
  11. 　前記工程において、前記多孔質シートの一方面上にのみ前記組成物を塗布する、請求項１０に記載のセパレータの製造方法。 The method for manufacturing a separator according to claim 10, wherein in the step, the composition is applied only on one side of the porous sheet.
  12. 　前記工程において、前記多孔質シートの一方面上及び他方面上に前記組成物を塗布する、請求項１０に記載のセパレータの製造方法。 11. The method for manufacturing a separator according to claim 10, wherein in said step, said composition is applied on one side and the other side of said porous sheet.
  13. 　前記多孔質シートが、ポリオレフィンを含有する、請求項１０～１２のいずれか一項に記載のセパレータの製造方法。 The method for producing a separator according to any one of claims 10 to 12, wherein the porous sheet contains polyolefin.
  14. 　前記リチウム塩が、硝酸リチウムである、請求項１０～１３のいずれか一項に記載のセパレータの製造方法。 The method for producing a separator according to any one of claims 10 to 13, wherein the lithium salt is lithium nitrate.
  15. 　前記ポリマが、フッ化ビニリデンをモノマ単位として含む、請求項１０～１４のいずれか一項に記載のセパレータの製造方法。 The method for producing a separator according to any one of claims 10 to 14, wherein the polymer contains vinylidene fluoride as a monomer unit.
  16. 　前記ポリマが、ヘキサフルオロプロピレンをモノマ単位として含む、請求項１０～１４のいずれか一項に記載のセパレータの製造方法。 The method for producing a separator according to any one of claims 10 to 14, wherein the polymer contains hexafluoropropylene as a monomer unit.
  17. 　前記ポリマが、フッ化ビニリデン及びヘキサフルオロプロピレンをモノマ単位として含む、請求項１０～１４のいずれか一項に記載のセパレータの製造方法。 The method for producing a separator according to any one of claims 10 to 14, wherein the polymer contains vinylidene fluoride and hexafluoropropylene as monomer units.
  18. 　前記層の厚みが、５μｍ以上である、請求項１０～１７のいずれか一項に記載のセパレータの製造方法。 The method for producing a separator according to any one of claims 10 to 17, wherein the layer has a thickness of 5 µm or more.
  19. 　正極と、
    　負極と、
    　前記正極と前記負極との間に配置されている請求項１～９のいずれか一項に記載のセパレータと、
    を備える、リチウムイオン二次電池。     a positive electrode;
    a negative electrode;
    The separator according to any one of claims 1 to 9, which is arranged between the positive electrode and the negative electrode;
    A lithium ion secondary battery.
  20. 　前記セパレータは、前記層が前記負極と対向するように配置されている、請求項１９に記載のリチウムイオン二次電池。 The lithium ion secondary battery according to claim 19, wherein the separator is arranged such that the layer faces the negative electrode.
  21. 　前記負極が、リチウム金属を含有する、請求項１９又は２０に記載のリチウムイオン二次電池。 The lithium ion secondary battery according to claim 19 or 20, wherein the negative electrode contains lithium metal.
  22. 　請求項１０～１８のいずれか一項に記載の製造方法によりセパレータを製造する製造工程と、
    　正極と負極との間に前記セパレータを配置する配置工程と、
    を備える、リチウムイオン二次電池の製造方法。     A manufacturing process for manufacturing a separator by the manufacturing method according to any one of claims 10 to 18;
    an arrangement step of arranging the separator between the positive electrode and the negative electrode;
    A method for manufacturing a lithium ion secondary battery, comprising:
  23. 　前記配置工程において、前記セパレータを、前記層が前記負極と対向するように配置する、請求項２２に記載のリチウムイオン二次電池の製造方法。 23. The method for manufacturing a lithium ion secondary battery according to claim 22, wherein in the arranging step, the separator is arranged so that the layer faces the negative electrode.
  24. 　前記負極が、リチウム金属を含有する、請求項２２又は２３に記載のリチウムイオン二次電池の製造方法。 The method for manufacturing a lithium ion secondary battery according to claim 22 or 23, wherein the negative electrode contains lithium metal.
PCT/JP2021/010591 2021-03-16 2021-03-16 Separator, lithium ion secondary battery, and methods for producing same WO2022195716A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/JP2021/010591 WO2022195716A1 (en) 2021-03-16 2021-03-16 Separator, lithium ion secondary battery, and methods for producing same
TW111109396A TW202249339A (en) 2021-03-16 2022-03-15 Separator, lithium ion secondary battery, and methods for producing same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2021/010591 WO2022195716A1 (en) 2021-03-16 2021-03-16 Separator, lithium ion secondary battery, and methods for producing same

Publications (1)

Publication Number Publication Date
WO2022195716A1 true WO2022195716A1 (en) 2022-09-22

Family

ID=83320095

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2021/010591 WO2022195716A1 (en) 2021-03-16 2021-03-16 Separator, lithium ion secondary battery, and methods for producing same

Country Status (2)

Country Link
TW (1) TW202249339A (en)
WO (1) WO2022195716A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008524824A (en) * 2004-12-22 2008-07-10 エルジー・ケム・リミテッド Presence / absence composite porous separator membrane and electrochemical device using the separator membrane
JP2013114764A (en) * 2011-11-25 2013-06-10 Sony Corp Lithium ion battery and separator, and battery pack, electronic device, electric vehicle, power storage device, and electric power system
WO2018003979A1 (en) * 2016-07-01 2018-01-04 宇部興産株式会社 Separator and power storage device
CN109167012A (en) * 2018-08-15 2019-01-08 珠海光宇电池有限公司 Multi-layer compound structure diaphragm and preparation method thereof and lithium-sulfur cell

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008524824A (en) * 2004-12-22 2008-07-10 エルジー・ケム・リミテッド Presence / absence composite porous separator membrane and electrochemical device using the separator membrane
JP2013114764A (en) * 2011-11-25 2013-06-10 Sony Corp Lithium ion battery and separator, and battery pack, electronic device, electric vehicle, power storage device, and electric power system
WO2018003979A1 (en) * 2016-07-01 2018-01-04 宇部興産株式会社 Separator and power storage device
CN109167012A (en) * 2018-08-15 2019-01-08 珠海光宇电池有限公司 Multi-layer compound structure diaphragm and preparation method thereof and lithium-sulfur cell

Also Published As

Publication number Publication date
TW202249339A (en) 2022-12-16

Similar Documents

Publication Publication Date Title
KR102362887B1 (en) Method of pre-lithiating an anode for lithium secondary battery and Lithium metal laminate for being used therefor
JP3868231B2 (en) Carbon material, negative electrode for lithium ion secondary battery and lithium ion secondary battery
JP4087343B2 (en) Lithium ion secondary battery and method for charging lithium ion secondary battery
JP5365107B2 (en) Method for producing electrode for electrochemical device
CN110265629B (en) Negative electrode and lithium ion secondary battery
CN104508874B (en) Lithium rechargeable battery
JP6946694B2 (en) Lithium ion secondary battery
JP2019175657A (en) Lithium ion secondary battery
JP2002151156A (en) Method of manufacturing lithium secondary battery
JP6369970B2 (en) Composite positive electrode active material, electrode for lithium secondary battery including the same, and lithium secondary battery
JP2018170142A (en) Lithium ion secondary battery
JP2018160379A (en) Negative electrode for lithium ion secondary battery and lithium ion secondary battery
JP2017188424A (en) Positive electrode active material for lithium ion secondary battery and lithium ion secondary battery positive electrode using the same, and lithium ion secondary battery
US20190280297A1 (en) Negative electrode and lithium ion secondary battery
WO2022195716A1 (en) Separator, lithium ion secondary battery, and methods for producing same
JP7135840B2 (en) Positive electrode and lithium ion secondary battery
CN110265628B (en) Positive electrode and lithium ion secondary battery
JP2007172878A (en) Battery and its manufacturing method
JP7127385B2 (en) Anodes and electrochemical devices
JP7147754B2 (en) Electrolyte and electrochemical device
US10211456B2 (en) Positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery positive electrode and lithium ion secondary battery using the same
EP3358652B1 (en) Positive electrode for lithium-ion secondary cell, and lithium-ion secondary cell
JP2002134173A (en) Method for manufacturing nonaqueous secondary battery
US11973219B2 (en) Method for pre-lithiation of negative electrode for lithium secondary battery and lithium metal laminate used therefor
WO2023008569A1 (en) Electrochemical device, electrolyte solution, and additive used for electrolyte solution

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21931468

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21931468

Country of ref document: EP

Kind code of ref document: A1