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WO2025141848A1 - Batterie secondaire au lithium - Google Patents

Batterie secondaire au lithium Download PDF

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Publication number
WO2025141848A1
WO2025141848A1 PCT/JP2023/047211 JP2023047211W WO2025141848A1 WO 2025141848 A1 WO2025141848 A1 WO 2025141848A1 JP 2023047211 W JP2023047211 W JP 2023047211W WO 2025141848 A1 WO2025141848 A1 WO 2025141848A1
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Prior art keywords
active material
electrolyte
secondary battery
negative electrode
lithium secondary
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English (en)
Japanese (ja)
Inventor
一樹 瀧本
剛輔 大山
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Terawatt Technology KK
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Terawatt Technology KK
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Priority to PCT/JP2023/047211 priority Critical patent/WO2025141848A1/fr
Publication of WO2025141848A1 publication Critical patent/WO2025141848A1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates

Definitions

  • the present invention relates to a lithium secondary battery.
  • lithium secondary batteries which charge and discharge by the movement of lithium ions between the positive and negative electrodes, are known to exhibit high voltage and high energy density.
  • a typical lithium secondary battery is the lithium-ion secondary battery (LIB), which has active materials capable of retaining lithium elements in the positive and negative electrodes and charges and discharges by the exchange of lithium ions between the positive and negative active materials.
  • LIB lithium-ion secondary battery
  • lithium secondary batteries Lithium-metal batteries
  • AFB Anode-free batteries
  • lithium secondary batteries that can achieve high voltages have the problem that the cycle characteristics of the lithium secondary battery deteriorate due to the high reactivity between the battery components and the electrolyte. Specifically, repeated charging and discharging causes side reactions between the electrolyte and the negative and positive electrode materials, resulting in a decrease in battery capacity. Therefore, there is a need for ideas to prevent such a decrease in battery capacity.
  • Patent Document 1 discloses an electrolyte solution containing an electrolyte salt and an organic solvent for the purpose of improving the warm storage performance, high-temperature cycle performance, and power performance of a lithium-ion battery, where the electrolyte salt contains a lithium salt, the organic solvent contains a cyclic ether, and where the mass fraction of the lithium salt relative to the electrolyte solution is W1 and the mass fraction of the cyclic ether relative to the electrolyte solution is W2, the electrolyte solution satisfies 0.2 ⁇ W1/W2 ⁇ 1.06.
  • Patent Document 2 also discloses an electrolyte solution containing an electrolyte salt and an organic solvent, with the aim of achieving low internal resistance, high-temperature storage performance, and high-temperature cycle performance of the battery, where the electrolyte salt contains lithium bis(fluorosulfonyl)imide, the mass % content of the lithium bis(fluorosulfonyl)imide in the electrolyte solution is 4.5% to 11%, the organic solvent contains ethylene carbonate, and the electrolyte solution satisfies 0.9 ⁇ WLiFSI/(16.77% ⁇ WEC) ⁇ 2.9 (where WLiFSI is the mass % content of lithium bis(fluorosulfonyl)imide in the electrolyte solution, and WEC is the mass % content of the ethylene carbonate in the electrolyte solution).
  • the electrolyte salt contains lithium bis(fluorosulfonyl)imide
  • the present invention was made in consideration of the above circumstances, and aims to provide a lithium secondary battery with improved cycle characteristics.
  • the present invention makes it possible to provide a lithium secondary battery with excellent cycle characteristics.
  • the basic configuration of a lithium secondary battery according to one embodiment of the present invention will be described with reference to Fig. 1.
  • the lithium secondary battery according to one embodiment of the present invention includes, for example, a plurality of negative electrodes 10, a plurality of separators 20, and a plurality of positive electrodes 30, as shown in Fig. 1, and the negative electrodes 10 and the positive electrodes 30 are disposed apart from each other via the separators 20.
  • a plurality of negative electrodes 10 and the positive electrodes 30 are disposed apart from each other via the separators 20.
  • the negative electrode active material composition When forming the negative electrode active material layer, the negative electrode active material composition is applied to one or both sides of the negative electrode current collector.
  • the amount of the negative electrode active material composition applied is preferably 1 mg/ cm2 or more and 30 mg/cm2 or less , 2 mg/cm2 or more and 25 mg/cm2 or less , or 3 mg/ cm2 or more and 20 mg/cm2 or less, in terms of basis weight on one side.
  • the thickness of the negative electrode active material layer is preferably 20 ⁇ m or more and 200 ⁇ m or less, 30 ⁇ m or more and 175 ⁇ m or less, or 40 ⁇ m or more and 150 ⁇ m or less.
  • the electrolyte solution of the present embodiment contains LiFSI, LiPF6 , and LiPO2F2 as lithium salts, and may contain other salts as necessary.
  • other salts include lithium salts such as LiI, LiCl, LiBr, LiF , LiBF4 , LiAsF6 , LiSO3CF3, LiN( SO2CF3 ) 2 , LiN ( SO2CF3CF3 ) 2 , LiBF2 ( C2O4 ) , LiB( O2C2H4 ) 2 , LiB( O2C2H4 ) F2 , LiB( OCOCF3 ) 4 , LiNO3 , and Li2SO4 , and salts of metals such as Na, K, Ca , and Mg .
  • the lithium ion concentration in the electrolyte is 0.7 M or more and 3.0 M or less, and preferably 0.8 M or more and 2.5 M or less, 1.0 M or more and 2.0 M or less, and 1.3 M or more and 1.7 M or less.
  • the solvent of the electrolyte is not particularly limited as long as it dissolves the lithium salt of the present embodiment.
  • solvents include chain or cyclic carbonate compounds, ether compounds, and chain or cyclic fluorine compounds in which one or more hydrogen atoms of the carbon skeleton are substituted with fluorine atoms.
  • the electrolyte solvent may be used alone or in combination of two or more.
  • the solvent for the electrolyte preferably contains at least one of a chain carbonate compound, a cyclic carbonate compound, a chain fluorine compound, and a cyclic fluorine compound, more preferably contains at least one of a chain carbonate compound, a cyclic carbonate compound, and a cyclic fluorine compound, even more preferably contains a chain carbonate compound, a cyclic carbonate compound, and a cyclic fluorine compound, and even more preferably contains a chain carbonate compound, a cyclic carbonate compound, a chain fluorine compound, and a cyclic fluorine compound.
  • a chain carbonate compound is a carbonate compound in which one or more hydrogen atoms in the carbon skeleton are not replaced by fluorine atoms and which does not have a cyclic structure such as an aromatic ring, an alicyclic ring, a monocyclic ring, or a heterocyclic ring.
  • chain carbonate compounds include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, and chloroethylene carbonate.
  • the compound contains dimethyl carbonate or ethylene carbonate, and more preferably, the compound contains dimethyl carbonate and ethylene carbonate.
  • a cyclic carbonate compound is a carbonate compound in which one or more hydrogen atoms in the carbon skeleton are not replaced by fluorine atoms and which has a cyclic structure such as an aromatic ring, alicyclic ring, monocyclic ring, or heterocyclic ring.
  • Examples of cyclic carbonate compounds include ethylene carbonate and propylene carbonate. Of these, it is preferable to contain ethylene carbonate. By containing a cyclic carbonate compound, the effect of improving cycle characteristics according to the present invention tends to be even more pronounced.
  • a chain fluorine compound is a compound that does not have a ring structure such as an aromatic ring, alicyclic ring, monocyclic ring, or heterocyclic ring, and in which one or more hydrogen atoms in the carbon skeleton are replaced with fluorine atoms.
  • chain fluorine compounds include 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, methyl perfluoroisobutyl ether, ethyl nonafluoroisobutyl ether, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethoxy-2,2,3,3-tetrafluoropropoxymethane, methyl-1,1,2,2-tetrafluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, and propyl-1,1,2,2-tetrafluoroethyl ether.
  • a chain fluorine compound having an ether group is preferred, and more preferably contains at least one selected from the group consisting of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, methyl perfluoroisobutyl ether, ethyl nonafluoroisobutyl ether, and 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane, and even more preferably contains 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, or ethyl nonafluoroisobutyl ether.
  • Cyclic fluorine compounds are compounds that have a ring structure such as an aromatic ring, alicyclic ring, monocyclic ring, or heterocyclic ring, and in which one or more hydrogen atoms in the carbon skeleton are substituted with fluorine atoms.
  • Examples of cyclic fluorine compounds include fluoroethylene carbonate, 1,1,2,2,3,3,4-heptafluorocyclopentane, hexadecafluoro(1,3-dimethylcyclohexane), tetradecafluoromethylcyclohexane, fluorocyclohexane, fluorocyclopentane, and octadecafluorodecahydronaphthalene.
  • fluoroethylene carbonate is preferred.
  • the electrolyte preferably contains a chain fluorine compound having the above formula (A), (B) or (C), and more preferably contains a chain fluorine compound having the above formula (A) or (B).
  • a chain fluorine compound having such a structure By containing a chain fluorine compound having such a structure, the cycle characteristics of the lithium secondary battery tend to be further improved.
  • the electrolyte solution of this embodiment preferably contains a chain or cyclic fluorinated carbonate.
  • a chain or cyclic fluorinated carbonate By containing a chain or cyclic fluorinated carbonate, the effect of improving cycle characteristics according to the present invention tends to be more pronounced. From the same viewpoint, it is preferable for the electrolyte solution to contain fluoroethylene carbonate as the chain or cyclic fluorinated carbonate.
  • An ether compound is a compound that has an ether group and is not fluorinated.
  • ether compounds include 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,2-dimethoxypropane (DMP), diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dimethoxypropane, 1,4-dimethoxybutane, 1,1-dimethoxyethane, 2,2-dimethoxypropane, 1,2-diethoxybutane, and 2,3-diethoxybutane.
  • DME 1,2-dimethoxyethane
  • DEE 1,2-diethoxyethane
  • DMP 1,2-dimethoxypropane
  • diethylene glycol dimethyl ether triethylene glycol dimethyl ether
  • tetraethylene glycol dimethyl ether 1,3-dimethoxypropane
  • 1,4-dimethoxybutane 1,1-d
  • the content of the carbonate compound is preferably 30% by mass or more and 100% by mass or less, 35% by mass or more and 95% by mass or less, 45% by mass or more and 90% by mass or less, or 55% by mass or more and 85% by mass or less, relative to the total amount of the electrolyte.
  • the carbonate compound includes both fluorinated carbonate compounds and non-fluorinated carbonate compounds.
  • the content of the chain carbonate compound is preferably 10% by volume or more and 60% by volume or less, 20% by volume or more and 50% by volume or less, or 25% by volume or more and 45% by volume or less, based on the total amount of the chain carbonate compound and the cyclic carbonate compound.
  • the chain carbonate compound includes both fluorinated chain carbonate compounds and non-fluorinated chain carbonate compounds.
  • the content of the cyclic carbonate compound is preferably 5% by volume or more and 60% by volume or less, 10% by volume or more and 50% by volume or less, or 20% by volume or more and 40% by volume or less, based on the total amount of the chain carbonate compound and the cyclic carbonate compound.
  • the cyclic carbonate compound includes both fluorinated and non-fluorinated cyclic carbonate compounds.
  • the content of the chain fluorine compound is preferably 0% by mass or more and 50% by mass or less, 0% by mass or more and 40% by mass or less, 1% by mass or more and 30% by mass or less, or 3% by mass or more and 25% by mass or less, relative to the total amount of the chain carbonate compound and the cyclic carbonate compound.
  • the content of the cyclic fluorine compound is preferably from 0% by mass to 30% by mass, from 1% by mass to 20% by mass, or from 3% by mass to 10% by mass, relative to the total amount of the chain carbonate compound and the cyclic carbonate compound.
  • the content of the fluorinated carbonate is preferably from 0% by mass to 30% by mass, from 1% by mass to 20% by mass, or from 3% by mass to 10% by mass, relative to the total amount of the chain carbonate compound and the cyclic carbonate compound.
  • the separator 20 of the present embodiment is not particularly limited as long as it has the function of physically and/or electrically isolating the positive electrode 30 and the negative electrode 10 and the function of ensuring the ion conductivity of lithium ions.
  • Examples of such a separator include insulating porous members, polymer electrolytes, gel electrolytes, and inorganic solid electrolytes, and typically includes at least one selected from the group consisting of insulating porous members, polymer electrolytes, and gel electrolytes.
  • one type of member may be used alone, or two or more types of members may be used in combination.
  • an insulating porous material, a polymer electrolyte, or a gel electrolyte is used alone or in combination as the separator 20.
  • the lithium secondary battery needs to further include an electrolytic solution.
  • the polymer electrolyte is not particularly limited, but examples thereof include solid polymer electrolytes mainly containing a polymer and an electrolyte, and semi-solid polymer electrolytes mainly containing a polymer, an electrolyte, and a plasticizer.
  • the gel electrolyte is not particularly limited, but may be, for example, one that mainly contains a polymer and a liquid electrolyte (i.e., a solvent and an electrolyte).
  • Polymers that may be included in the polymer electrolyte and gel electrolyte include, but are not limited to, polymers containing functional groups containing oxygen atoms such as ethers and esters, halogen groups, and polar groups such as cyano groups.
  • resins having ethylene oxide units in the main chain and/or side chains such as polyethylene oxide (PEO), resins having propylene oxide units in the main chain and/or side chains such as polypropylene oxide (PPO), acrylic resins, vinyl resins, ester resins, nylon resins, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polysiloxane, polyphosphazene, polymethylmethacrylate, polyamide, polyimide, aramid, and polytetrafluoroethylene.
  • PEO polyethylene oxide
  • PPO polypropylene oxide
  • acrylic resins vinyl resins, ester resins, nylon resins, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polysiloxane, polyphosphazene, polymethylmethacrylate, polyamide, polyimide, aramid, and polytetrafluoroethylene.
  • PVdF polyvinylidene fluoride
  • PAN
  • Examples of electrolytes contained in the polymer electrolyte and gel electrolyte include salts of Li, Na, K, Ca, and Mg.
  • the polymer electrolyte and gel electrolyte contain a lithium salt.
  • the lithium salt is not particularly limited, but may be, for example, any salt that can be contained in the above-mentioned electrolyte solution. Such salts or lithium salts may be used alone or in combination of two or more.
  • the compounding ratio of the polymer and the lithium salt in the polymer electrolyte and the gel electrolyte may be determined by the ratio of the polar group of the polymer to the lithium atoms of the lithium salt.
  • the compounding ratio of the polymer and the lithium salt can be adjusted so that the ratio ([Li]/[O]) is, for example, 0.02 or more and 0.20 or less, 0.03 or more and 0.15 or less, or 0.04 or more and 0.12 or less.
  • the solvent contained in the gel electrolyte is not particularly limited, but for example, the solvents that can be contained in the above-mentioned electrolytic solution can be used alone or in combination of two or more. Examples of preferred solvents are the same as those in the above-mentioned electrolytic solution.
  • the plasticizer contained in the semi-solid polymer electrolyte is not particularly limited, but may include, for example, components similar to the solvent that may be contained in the gel electrolyte, and various oligomers.
  • the separator 20 includes an insulating porous material
  • the pores of the material are filled with a substance having ion conductivity, and the material exhibits ion conductivity. Therefore, in this embodiment, the material is filled with, for example, the electrolyte solution of this embodiment, or a gel electrolyte containing the electrolyte solution of this embodiment.
  • the material constituting the insulating porous member is not particularly limited, and examples thereof include insulating polymeric materials, specifically, polyethylene (PE) and polypropylene (PP). That is, the separator 20 may be a porous polyethylene (PE) film, a porous polypropylene (PP) film, or a laminated structure thereof.
  • PE polyethylene
  • PP polypropylene
  • the positive electrode 30 of this embodiment has a positive electrode current collector and a positive electrode active material layer.
  • the average thickness of the positive electrode 30 is not particularly limited, but is, for example, 20 ⁇ m to 100 ⁇ m, 30 ⁇ m to 80 ⁇ m, or 40 ⁇ m to 70 ⁇ m. However, the average thickness of the positive electrode 30 can be appropriately adjusted according to the desired battery capacity.
  • the positive electrode current collector of this embodiment may have a positive electrode current collector film that includes a resin layer containing polyethylene terephthalate and a metal layer provided on both sides of the resin layer, or may have a metal layer without a resin layer.
  • the metal layer is formed by attaching the metal layer to the surfaces on both sides of the resin layer by vapor deposition, sputtering, electrolytic plating, or with an adhesive.
  • the resin layer of the positive electrode current collector is an insulator and prevents electrical conduction between the metal layers provided on both sides of the resin layer.
  • the resin constituting the resin layer is not particularly limited, but may be, for example, a sheet-like (film-like) or fibrous resin.
  • the resin may include at least one selected from the group consisting of polyethylene terephthalate (PET), polypropylene, polyamide, acrylic resin, polycarbonate, polyethylene, polyvinyl chloride, and polystyrene.
  • PET polyethylene terephthalate
  • polypropylene polypropylene
  • polyamide acrylic resin
  • polycarbonate polycarbonate
  • polyethylene polyethylene
  • polyvinyl chloride polyvinyl chloride
  • polystyrene polystyrene
  • the resin layer of the positive electrode current collector may contain other additives as appropriate depending on the desired physical properties, in addition to the above-mentioned resins.
  • additives include, but are not limited to, colorants, flame retardants, surfactants, etc.
  • the thickness of the resin layer of the positive electrode collector is, for example, 2 ⁇ m or more and 15 ⁇ m or less, 3 ⁇ m or more and 12 ⁇ m or less, or 4 ⁇ m or more and 10 ⁇ m or less.
  • the metal layer of the positive electrode collector is in physical and/or electrical contact with the positive electrode active material layer and functions to give and receive electrons to and from the positive electrode active material layer.
  • the metal layer of the positive electrode collector is made of a conductor such as a metal that does not react with lithium in a battery.
  • the metal constituting the metal layer of the positive electrode collector is not particularly limited, but is at least one selected from the group consisting of aluminum, titanium, stainless steel, nickel, and alloys thereof. From the viewpoint of more effectively and reliably achieving the effects of the present invention, aluminum or an aluminum alloy is preferable, and aluminum is particularly preferable.
  • the metal may be used alone or in combination of two or more.
  • the term "metal that does not react with lithium” means a metal that does not react with lithium ions or lithium metal to form an alloy under the operating conditions of a lithium secondary battery.
  • the thickness of the metal layer is not particularly limited, and is, for example, 0.1 ⁇ m or more and 4.0 ⁇ m or less, 0.2 ⁇ m or more and 3.0 ⁇ m or less, 0.3 ⁇ m or more and 2.5 ⁇ m or less, or 0.4 ⁇ m or more and 2.0 ⁇ m or less.
  • the thickness of the metal layer is not particularly limited, but is, for example, 4.0 ⁇ m or more and 20.0 ⁇ m or less, 6.0 ⁇ m or more and 17.5 ⁇ m or less, or 8.0 ⁇ m or more and 15.0 ⁇ m or less.
  • the positive electrode active material is a material that causes an electrode reaction, i.e., an oxidation reaction and a reduction reaction, in the positive electrode 30.
  • the positive electrode active material of this embodiment is not particularly limited, but is, for example, contained in a positive electrode active material composition that includes a binder, a conductive additive, a sacrificial positive electrode agent, and other additives, and the positive electrode active material composition is applied to at least one or both sides of a positive electrode current collector and press-molded to form a positive electrode active material layer on at least one or both sides of the positive electrode current collector.
  • the method of disposing the positive electrode active material layer on the positive electrode current collector is not limited to press molding, and examples of the method include a method in which a thermosetting compound is added to the positive electrode active material composition and then heated to harden it, a method in which a photocurable compound is added to the positive electrode active material composition and then irradiated with light to harden it, and a method in which the positive electrode active material composition is a two-component hardening composition and then hardened by mixing the two components, etc.
  • the positive electrode active material layer of the present embodiment may contain one or more compounds represented by the general formula: Li z Ni x Co y M 1-x-y O 2 + ⁇ (wherein 0.5 ⁇ x ⁇ 1.0, 0 ⁇ y ⁇ 0.35, 0.9 ⁇ z ⁇ 1.3, ⁇ 0.2 ⁇ 0.15, and M is one or more elements selected from the group consisting of Mn, Al, V, Mg, Mo, Nb, Ti, Zr, Fe, Cu, Cr, Zn, F, and B).
  • the redox shuttle reaction is more likely to occur, but by containing an additive to be described in detail below in the electrolyte, the reaction is suppressed, and there is a tendency for the electrolyte to have excellent performance stability at high temperatures.
  • the positive electrode active material may include other positive electrode active materials other than the above-mentioned compounds.
  • the other positive electrode active materials of the present embodiment include a host material of lithium element (typically, lithium ion).
  • Such other positive electrode active materials include, but are not limited to, metal oxides and metal phosphates.
  • the metal oxides include, but are not limited to, cobalt oxide-based compounds, manganese oxide-based compounds, and nickel oxide-based compounds.
  • the metal phosphates include, but are not limited to, iron phosphate-based compounds and cobalt phosphate-based compounds.
  • the other positive electrode active materials may be used alone or in combination of two or more.
  • the positive electrode active material composition may contain a binder.
  • a binder By containing a binder, the positive electrode active material layer is more easily bound to the positive electrode current collector, and flexibility is improved after the positive electrode active material layer is disposed on the positive electrode current collector.
  • multiple positive electrodes 30 and negative electrodes 10 may be stacked alternately with a separator 20 sandwiched between the positive electrodes 30 and negative electrodes 10, which tends to improve battery performance such as energy density.
  • the negative electrodes 10 and positive electrodes 30 may be wrapped so that they do not come into contact with each other and face the opposite side of the separator 20, and the separator 20 may be stacked without cutting. Such stacking is preferable from the viewpoints of preventing short circuits and improving productivity.
  • the negative electrode 10 of this embodiment has a negative electrode active material layer containing a Si active material, although this is not shown. Therefore, the negative electrode active material layer is obtained by applying a negative electrode active material composition, which is a mixture of the above-mentioned negative electrode active material, a binder, an additive, a conductive assistant, a solvent, etc., to both sides or one side of the negative electrode current collector, and then press molding the composition. The obtained molded body is punched to a predetermined size by a punching process, to obtain the negative electrode 10 of this embodiment.
  • a negative electrode active material composition which is a mixture of the above-mentioned negative electrode active material, a binder, an additive, a conductive assistant, a solvent, etc.
  • the shape of the battery of the lithium secondary battery of this embodiment is not particularly limited, and may be, for example, a sheet type, a laminated sheet type, a thin shape, a cylindrical shape with a bottom, a rectangular shape with a bottom, etc. From the viewpoint of more effectively and reliably achieving the effects of this embodiment, a sheet type, a laminated sheet type, or a thin shape is preferable.
  • Lithium ion secondary batteries of Examples 1 to 15 and Comparative Examples 1 to 11 were fabricated as follows.
  • This composition was applied to both sides of the negative electrode current collector so that the basis weight was 6.2 mg/cm 2 , pressed, and cut out to a size of 4.4 cm x 4.4 cm.
  • a metal sheet (copper foil with a thickness of 4.0 ⁇ m) for the negative electrode was ultrasonically welded and attached to the end of the negative electrode 10 obtained in this way.
  • a current collector film was used in which 1.0 ⁇ m of aluminum, which is a metal layer, was vapor-deposited on both sides of a 6.0 ⁇ m-thick PET film, which is a resin layer.
  • a positive electrode active material composition was prepared by mixing 96 parts by mass of LiNi 0.8 Co 0.15 Al 0.05 O 2 as a positive electrode active material, 2 parts by mass of carbon black as a conductive assistant, and 2 parts by mass of polyvinylidene fluoride (PVDF) as a binder in N-methyl-pyrrolidone (NMP) as a solvent.
  • PVDF polyvinylidene fluoride
  • This positive electrode active material composition was applied to both sides of the positive electrode current collector with a basis weight of 15 mg/cm 2 , pressed, and a positive electrode active material layer was formed on both sides of the positive electrode current collector, and a molded body was obtained. This molded body was cut into a predetermined size (4 cm x 4 cm) to obtain a positive electrode 30.
  • a solvent solution was prepared by mixing ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 30:35:35, respectively.
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • EMC ethyl methyl carbonate
  • FEC fluoroethylene carbonate
  • HFE hydrofluoroether
  • HFE hydrofluoroether
  • Lithium salts including lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF 6 ), and lithium difluorophosphate (LiPO 2 F 2 ), were dissolved in the above solution so as to achieve the molar fractions and lithium ion concentrations shown in Table 1.
  • LiFSI lithium bis(fluorosulfonyl)imide
  • LiPF 6 lithium hexafluorophosphate
  • LiPO 2 F 2 lithium difluorophosphate
  • the lithium secondary battery includes a negative electrode active material containing Si and an electrolyte, and the average particle size of the negative electrode active material is 5.0 ⁇ m or more and 30 ⁇ m or less.
  • the lithium salts LiFSI, LiPF 6 , and LiPO 2 F 2 are included.
  • the molar fraction of the LiFSI is x
  • the molar fraction of the LiPF 6 is y
  • the molar fraction of the LiPO 2 F 2 is z
  • x + y + z 1
  • the concentration of lithium ions is 0.7 M or more and 3.0 M or less.
  • the capacity retention rate is higher than that of Comparative Examples 1 to 11, and it was confirmed that the lithium secondary battery has excellent cycle characteristics.
  • a lithium secondary battery comprising a negative electrode active material containing Si and an electrolyte,
  • the average particle size of the negative electrode active material is 5.0 ⁇ m or more and 30 ⁇ m or less
  • the electrolyte contains LiFSI, LiPF6 , and LiPO2F2 as lithium salts,
  • the molar fraction of LiFSI is x
  • the molar fraction of LiPF6 is y
  • the molar fraction of LiPO2F2 is z
  • x+y+z 1
  • the concentration of lithium ions is 0.7 M or more and 3.0 M or less.
  • the electrolytic solution contains a chain fluorine compound having at least one of the monovalent groups represented by the above formulas (A) to (D), The content of the chain fluorine compound is 0.5 mass% or more and 30 mass% or less with respect to the total amount of components other than the chain fluorine compound in the electrolyte solution.
  • the negative electrode active material includes Li y —SiO x or SiC; The lithium secondary battery according to [1] or [2].
  • the concentration of the lithium ions is 1.0 M or more and 2.5 M or less.
  • the average particle size of the negative electrode active material is 7.0 ⁇ m or more and 20 ⁇ m or less.
  • the electrolyte comprises a fluorinated carbonate; The lithium secondary battery according to any one of [1] to [5].
  • the electrolyte solution contains a chain fluorine compound A having the formula (A) or the formula (B), The lithium secondary battery according to any one of [1] to [6].
  • the lithium secondary battery of the present invention has excellent cycle characteristics and is therefore industrially applicable as an electricity storage device for a variety of applications.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

La présente invention concerne une batterie secondaire au lithium qui a d'excellentes caractéristiques de cyclage. La présente invention concerne une batterie secondaire au lithium qui comprend : un matériau actif d'électrode négative qui contient du Si ; et une solution d'électrolyte. Le diamètre de particules moyen du matériau actif d'électrode négative est compris entre 5,0 et 30 µm. La solution d'électrolyte contient LiFSI, LiPF6 et LiPO2F2 à titre de sels de lithium. La fraction molaire de LiFSI étant x, la fraction molaire de LiPF6 étant y, la fraction molaire de LiPO2F2 étant z et x + y + z = 1, 0,05 ≤ x ≤ 0,95, 0,05 ≤ y ≤ 0,90 et 0,005 ≤ z ≤ 0,35. La concentration en ions de lithium de la solution d'électrolyte est comprise entre 0,7 et 3,0 M.
PCT/JP2023/047211 2023-12-28 2023-12-28 Batterie secondaire au lithium Pending WO2025141848A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016009994A1 (fr) * 2014-07-15 2016-01-21 宇部興産株式会社 Solution d'électrolyte non aqueuse et dispositif de stockage d'électricité dans lequel celle-ci est utilisée
WO2018212027A1 (fr) * 2017-05-18 2018-11-22 日本電気株式会社 Solution électrolytique pour batterie secondaire au lithium-ion, et batterie secondaire au lithium-ion mettant en œuvre celle-ci
WO2022230661A1 (fr) * 2021-04-26 2022-11-03 パナソニックＩｐマネジメント株式会社 Électrode négative pour batterie secondaire ainsi que procédé de fabrication de celle-ci, et batterie secondaire
US20230238581A1 (en) * 2022-01-25 2023-07-27 Sila Nanotechnologies, Inc. Electrolytes for lithium-ion battery cells with nitrile additives

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016009994A1 (fr) * 2014-07-15 2016-01-21 宇部興産株式会社 Solution d'électrolyte non aqueuse et dispositif de stockage d'électricité dans lequel celle-ci est utilisée
WO2018212027A1 (fr) * 2017-05-18 2018-11-22 日本電気株式会社 Solution électrolytique pour batterie secondaire au lithium-ion, et batterie secondaire au lithium-ion mettant en œuvre celle-ci
WO2022230661A1 (fr) * 2021-04-26 2022-11-03 パナソニックＩｐマネジメント株式会社 Électrode négative pour batterie secondaire ainsi que procédé de fabrication de celle-ci, et batterie secondaire
US20230238581A1 (en) * 2022-01-25 2023-07-27 Sila Nanotechnologies, Inc. Electrolytes for lithium-ion battery cells with nitrile additives

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