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
  • 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
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
  • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• • 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
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • 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 non-aqueous electrolyte and a battery. More specifically, the present invention relates to a nonaqueous electrolyte that can be suitably used as a material for batteries such as lithium ion batteries, and a battery constructed using the same.
• Patent Document 1 describes a non-aqueous electrolyte used in a non-aqueous electrolyte secondary battery comprising a negative electrode and a positive electrode capable of intercalating and releasing metal ions, and a non-aqueous electrolyte, the non-aqueous electrolyte being
• Patent Documents 2 to 4 also disclose an electrolytic solution containing a disilane compound and a secondary battery containing the same.
• the present invention has been made in view of the above-mentioned current situation, and provides a non-aqueous electrolyte containing a sulfonylimide compound that has excellent storage stability in a high-temperature environment and can suppress an increase in DCR in a battery.
• the purpose is to provide.
• the present inventors conducted various studies on nonaqueous electrolytes containing sulfonylimide compounds, and found that by combining a disilane compound with a predetermined structure in a nonaqueous electrolyte containing a sulfonylimide compound with a predetermined structure in a predetermined ratio. have discovered that a non-aqueous electrolyte has excellent stability even when stored in a high-temperature environment, and can suppress the increase in DCR in batteries, and has come up with the idea that the above problems can be successfully solved. This has led to the present invention.
• the present invention includes the following non-aqueous electrolyte and the like.
• the following formula (1) M 1 N(R 1 SO 2 )(R 2 SO 2 )(1)
• M 1 represents an alkali metal atom.
• R 1 and R 2 are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms.
• R 3 to R 8 are the same or different and represent a hydrocarbon group having 1 to 14 carbon atoms, a hydrogen atom, a hydroxyl group, or a halogen atom, which may have a hetero atom.
• a non-aqueous electrolyte comprising a sulfonylimide compound having a concentration of 0.1 mol/L or more.
• R 3 to R 8 in the above formula (2) are the same or different, and are an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, an alkenyl group having 2 to 14 carbon atoms, or an alkenyl group having 2 to 14 carbon atoms.
• R 3 to R 8 in the above formula (2) are the same or different and are an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, an alkenyl group having 2 to 14 carbon atoms, or a hydrogen atom , or the non-aqueous electrolyte according to [1] or [2] above, which is a halogen atom.
• the content of the compound represented by formula (2) above is 0.05% by mass or more and less than 5.0% by mass with respect to 100% by mass of the non-aqueous electrolyte, [1] to The non-aqueous electrolyte according to any one of [4].
• [6] Furthermore, at least one selected from the group consisting of M 2 PF 6 , M 2 BF 4 , M 2 PO 2 F 2 and M 2 FSO 3 (M 2 represents an alkali metal atom); The non-aqueous electrolyte according to any one of [1] to [5] above.
• a battery comprising the non-aqueous electrolyte according to any one of [1] to [6] above.
• the non-aqueous electrolyte of the present invention has the above-mentioned structure, has excellent stability when stored in a high-temperature environment, and can suppress an increase in DCR in batteries, so it can be used as a material for batteries such as lithium ion batteries. It can be suitably used for.
• the non-aqueous electrolyte of the present invention comprises a sulfonylimide compound represented by the above formula (1) (hereinafter also simply referred to as a sulfonylimide compound) and a disilane compound (hereinafter also simply referred to as a sulfonylimide compound) represented by the above formula (2). (hereinafter also simply referred to as a disilane compound), and the concentration of the sulfonylimide compound is 0.1 mol/L or more.
• the concentration of the sulfonylimide compound is 0.1 mol/L or more.
• concentration of the sulfonylimide compound is preferably 0.1 to 6.0 mol/kg, more preferably 0.2 to 3.0 mol/kg, and still more preferably 0.4 to 2.0 mol/kg.
• kg more preferably 0.6 to 2.0 mol/kg, particularly preferably 0.8 to 2.0 mol/kg.
• the content of the disilane compound is not particularly limited, but it is preferably 0.05% by mass or more and less than 5.0% by mass with respect to 100% by mass of the nonaqueous electrolyte. Thereby, it is possible to more sufficiently reduce the increase in DCR in the battery under low temperature conditions, and to further improve the DCR increase rate and capacity retention rate upon repeated charging.
• the content of the disilane compound is more preferably 0.1 to 3.0% by mass, still more preferably 0.2 to 2.0% by mass, and even more preferably 0.5 to 1.5% by mass.
• the content is particularly preferably 0.5 to 1.0% by mass.
• the non-aqueous electrolyte contains the sulfonylimide compound as an alkali metal salt, but may also contain an alkali metal salt other than the sulfonylimide compound.
• the concentration of the alkali metal salt other than the sulfonylimide compound in the nonaqueous electrolyte is not particularly limited, but is preferably 0.1 to 1.5 mol/L. More preferably 0.2 to 1.0 mol/L, still more preferably 0.2 to 0.6 mol/L.
• the concentration of the alkali metal salt other than the sulfonylimide compound is preferably 0.1 to 1.5 mol/kg, more preferably 0.2 to 1.0 mol/kg, and even more preferably 0.2 ⁇ 0.6 mol/kg.
• the non-aqueous electrolyte preferably has a total alkali metal concentration of the sulfonylimide compound and an alkali metal salt other than the sulfonylimide compound from 0.8 to 6.0 mol/L. More preferably 1.0 to 3.0 mol/L, still more preferably 1.2 to 2.0 mol/L.
• the total alkali metal concentration of the sulfonylimide compound and the alkali metal salt other than the sulfonylimide compound is preferably 0.8 to 6.0 mol/kg, more preferably 1.0 to 3.0 mol/kg. kg, more preferably 1.2 to 2.0 mol/kg.
• the amount of the sulfonylimide compound is preferably 5 to 100 mol% based on 100 mol% of the electrolyte (the sulfonylimide compound and other alkali metal salts) in the nonaqueous electrolyte. Thereby, the effects of the present invention can be more fully exhibited. More preferably 10 to 95 mol%, still more preferably 20 to 90 mol%, even more preferably 30 to 85 mol%, even more preferably 40 to 85 mol%, particularly preferably 50 to 85 mol%. It is 85 mol%, particularly preferably 60 to 85 mol%. In one embodiment, the sulfonylimide compound may be present in an amount of 70 mol% or more, 80 mol% or more, or 90 mol% or more based on 100 mol% of the electrolyte.
• the non-aqueous electrolyte contains a non-aqueous solvent as a solvent, but may contain water at a rate of 10% or less.
• the moisture content is preferably 1% or less. Thereby, the effects of the present invention can be more fully exhibited.
• the water content is more preferably 1000 ppm or less, and still more preferably 100 ppm or less.
• the moisture content can be measured using a Karl Fischer moisture measuring device.
• the proportion of the nonaqueous solvent in the nonaqueous electrolyte is not particularly limited, but is preferably 100 parts by mass to 5000 parts by mass with respect to 100 parts by mass of the electrolyte (the sulfonylimide compound and other alkali metal salts). , more preferably from 150 parts by weight to 2,500 parts by weight, even more preferably from 200 parts by weight to 2,000 parts by weight.
• the non-aqueous electrolyte may contain the sulfonylimide compound, the disilane compound, an alkali metal salt other than the sulfonylimide compound, and other components other than the solvent.
• the content of other components is not particularly limited, but is preferably 0 to 20% by mass based on 100% by mass of the non-aqueous electrolyte.
• the amount is more preferably 0 to 10% by weight, and even more preferably 0 to 5% by weight.
• the sulfonylimide compound has the following formula (1); M 1 N(R 1 SO 2 )(R 2 SO 2 )(1) (In the formula, M 1 represents an alkali metal atom. R 1 and R 2 are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms.) It is a compound represented by
• alkali metal in M1 examples include lithium, sodium, potassium, rubidium, cesium, and francium. Lithium, sodium, and potassium are preferred, and lithium is more preferred.
• alkyl group having 1 to 6 carbon atoms in R 1 examples include straight chain alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group (amyl group), and n-hexyl group.
• the number of carbon atoms in the alkyl group in R 1 and R 2 is preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 to 2.
• the fluoroalkyl group having 1 to 6 carbon atoms in R 1 and R 2 above may be one in which at least a portion of the hydrogen atoms bonded to the carbon atoms of the alkyl group having 1 to 6 carbon atoms are substituted with fluorine atoms.
• Specific examples of the alkyl group are as described above.
• Examples of the fluoroalkyl group having 1 to 6 carbon atoms include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, a pentafluoroethyl group, a fluoropropyl group, and a fluoropropyl group. Examples include pentyl group and fluorohexyl group.
• the number of carbon atoms in the fluoroalkyl group in R 1 and R 2 is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 to 2.
• R 1 and R 2 are preferably a fluorine atom, a trifluoromethyl group, or a pentafluoroethyl group. More preferably, it is a fluorine atom, and it is preferable that at least one of the above R 1 and R 2 is a fluorine atom.
• a form in which R 1 and R 2 are both fluorine atoms is one of the preferred embodiments of the present invention.
• Examples of the sulfonylimide compounds include lithium bis(fluorosulfonyl)imide (hereinafter also referred to as LiFSI), lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium sulfonyl)(pentafluoroethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, potassium bis(fluorosulfonyl)imide, potassium(fluorosulfonyl)(trifluoromethylsulfonyl)imide, potassium bis(trifluoromethylsulfonyl)imide , sodium bis(fluorosulfonyl)imide, sodium(fluorosulfonyl)(trifluoromethylsulfonyl)imide, sodium bis(trifluoromethylsulfony
• lithium bis(fluorosulfonyl)imide lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, and lithium(fluorosulfonyl)(pentafluoroethylsulfonyl)imide are preferred, and lithium bis(fluorosulfonyl)imide is more preferred. It is.
• the disilane compound has the following formula (2);
• R 3 to R 8 are the same or different and represent a hydrocarbon group having 1 to 14 carbon atoms, a hydrogen atom, a hydroxyl group, or a halogen atom, which may have a hetero atom.) It is a compound that is
• the hydrocarbon group having 1 to 14 carbon atoms in R 3 to R 8 above includes an aliphatic alkyl group having 1 to 14 carbon atoms, an alicyclic alkyl group having 3 to 14 carbon atoms, and an alkenyl group having 2 to 14 carbon atoms. , an alkynyl group having 2 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, and the like.
• Examples of the aliphatic alkyl group having 1 to 14 carbon atoms include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group (amyl group), n-hexyl group, n-heptyl group.
• n-octyl group n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, i-propyl group, sec-butyl group, i-butyl group , t-butyl group, 1-methylbutyl group, 1-ethylpropyl group, 2-methylbutyl group, i-amyl group, neopentyl group, 1,2-dimethylpropyl group, 1,1-dimethylpropyl group, t-amyl group , 1,3-dimethylbutyl group, 3,3-dimethylbutyl group, 2-ethylbutyl group, 2-ethyl-2-methylpropyl group, 1-methylheptyl group, 2-ethylhexyl group, 1,5-dimethylhexyl group , t-o
• Examples of the alicyclic alkyl group having 3 to 14 carbon atoms include cyclopropyl group, cyclopropylmethyl group, cyclobutyl group, cyclobutylmethyl group, cyclopentyl group, cyclohexyl group, cyclohexylmethyl group, cycloheptyl group, and cyclooctyl group. group, cyclohexylpropyl group, cyclododecyl group, norbornyl group (C7), adamantyl group (C10), cyclopentylethyl group, and the like.
• alkenyl group having 2 to 14 carbon atoms examples include vinyl group, allyl group, 1-butenyl group, 2-butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, and dodecenyl group. , tetradecenyl group, etc.
• alkynyl group having 2 to 14 carbon atoms examples include ethynyl group, 1-propynyl group, 2-propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, and dodecynyl group. , tetradecynyl group, etc.
• the number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 4, particularly preferably 1 to 2.
• the number of carbon atoms in the alkenyl group and alkynyl group is preferably 2 to 10, more preferably 2 to 8, still more preferably 2 to 4, particularly preferably 2 to 3.
• the number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6 to 8, and still more preferably 6 to 7.
• the number of carbon atoms in the substituent is also included in the number of carbon atoms.
• the hydrocarbon group in R 3 to R 8 above may have a hetero atom, and examples of the hetero atom include a nitrogen atom, a sulfur atom, an oxygen atom, a phosphorus atom, a halogen atom, and the like.
• the hydrocarbon groups in R 3 to R 8 above may have a substituent having a hetero atom, and examples of the substituent having a hetero atom include a hydroxyl group, an ether group, an ester group, a carboxyl group, an acyl group, and a sulfone group. Examples include acid groups, amino groups, phosphoric acid groups, and the like.
• the substituent having a hetero atom is preferably an ether group, and the hydrocarbon group having a hetero atom is preferably an alkoxy group having 1 to 12 carbon atoms or an aryloxy group having 6 to 14 carbon atoms.
• the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group.
• the aryloxy group include phenyloxy group and benzyloxy group.
• halogen atoms in R 3 to R 8 include fluorine atom, chlorine atom, bromine atom, and iodine atom.
• R 3 to R 8 are preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, an alkenyl group having 2 to 14 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 6 to 12 carbon atoms.
• aryloxy group hydrogen atom, or halogen atom, more preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, an alkenyl group having 2 to 14 carbon atoms, a hydrogen atom, or , a halogen atom, more preferably an alkyl group having 1 to 12 carbon atoms, a hydrogen atom, or a halogen atom, particularly preferably a methyl group, a hydrogen atom, or a halogen atom.
• disilane compounds include tetramethyldisilane, tetraethyldisilane, tetrapropyldisilane, hexamethyldisilane, hexaethyldisilane, hexapropyldisilane, divinyltetramethyldisilane, hexaphenyldisilane, hexahydrodisilane, 1,1, 2,2-tetramethyl-1,2-diphenyldisilane, 1,2-dimethyl-1,1,2,2-tetraphenyldisilane, 1,2-di(t-butyl)-1,1,2,2 -Tetramethyldisilane, 1,1,2,2-tetramethyl-1,2-dimethoxydisilane, 1,1,2,2-tetramethyl-1,2-diethoxydisilane, 1,1,2-trimethyl- 1,2,2-trimethoxydisilane, 1,1,2-trimethyl-1,2,2-triethoxydisilane, 1,
• alkali metal salts are preferably M 2 PF 6 , M 2 BF 4 , M 2 PO 2 F 2 or M 2 FSO 3 (M 2 represents an alkali metal atom ); A form containing at least one selected from the group consisting of M 2 BF 4 , M 2 PO 2 F 2 and M 2 FSO 3 is one of the preferred embodiments of the present invention. More preferred as other alkali metal salts is M 2 PF 6 . Specific examples and preferred forms of the alkali metal atom are the same as those of the alkali metal atom in the sulfonylimide compound.
• the solvent in the nonaqueous electrolyte of the present invention is nonaqueous and is not particularly limited as long as it can dissolve the electrolyte (sulfonylimide compound and other alkali metal salts), disilane compound, and other components described below.
• linear carbonates such as dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate
• cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and chloroethylene carbonate
• tetrahydrofuran 2-methyltetrahydrofuran, 1,4-dioxane, 1, Ethers such as 1-dimethoxyethane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane
• Lactones Lactones; chain carboxylic acid esters such as methyl propionate and methyl butyrate; fluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4-difluoroethylene carbonate, tetrafluoroethylene carbonate, 4-fluoro-5-methyl
• fluorinated cyclic carbonates such as ethylene carbonate
• fluorinated chain carbonates such as trifluorodimethyl carbonate, trifluorodiethyl carbonate, and trifluoroethylmethyl carbonate.
• These non-aqueous solvents may be used in combination of two or more.
• chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate are preferred.
• components in the nonaqueous electrolyte of the present invention are components other than the sulfonylimide compound, the disilane compound, alkali metal salts other than the sulfonylimide compound, and solvents, and are not particularly limited, but include, for example, phenylethylene carbonate, Carbonate compounds such as erythritane carbonate; 1,3-propanesultone, 1,4-butanesultone, 1,5-pentanesultone, 1,4-hexanesultone, 4,6-heptanesultone, methyl methanesulfonate, Sulfonic acid esters such as methyl benzenesulfonate and methyl trifluoromethanesulfonate; Sulfone compounds such as sulfolane, 3-methylsulfolane, ethylmethylsulfone, diphenylsulfone, and bis(4-fluorophenyl)sulfone; succin
• the non-aqueous electrolyte of the present invention has the above-described structure and has excellent stability when stored in a high-temperature environment, so it can be suitably used as a material for batteries such as lithium ion batteries.
• the present invention also provides a battery comprising the non-aqueous electrolyte of the present invention.
• the above battery is preferably a battery comprising a positive electrode and a negative electrode, more preferably a separator impregnated with the non-aqueous electrolyte of the present invention is provided between the positive electrode and the negative electrode, and Preferably, these are housed in an outer case.
• the shape of the battery according to the present invention is not particularly limited, and any conventionally known battery shape such as a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, etc. can be used. Furthermore, when used as a high voltage power source (several tens of volts to several hundreds of volts) to be installed in an electric vehicle, a hybrid electric vehicle, etc., a battery module can be constructed by connecting individual batteries in series. .
• the battery is preferably an alkali metal battery, and an alkali metal battery comprising the nonaqueous electrolyte of the present invention is also an aspect of the present invention.
• the battery is more preferably a secondary battery, and one preferred embodiment of the present invention is that the battery is a lithium ion secondary battery.
• the positive electrode constituting the battery is not particularly limited, but includes a positive electrode active material composition containing a positive electrode active material, a conductive aid, a binder, a dispersion solvent, etc. supported on a positive electrode current collector, Usually formed into a sheet.
• Examples of methods for manufacturing the positive electrode include coating a positive electrode active material composition on a positive electrode current collector using a doctor blade method, immersing the positive electrode current collector in a positive electrode active material composition, and then drying; A method in which a sheet obtained by kneading, molding, and drying an active material composition is bonded to a positive electrode current collector via a conductive adhesive, followed by pressing and drying; Examples include a method of coating or casting onto an electric body, forming it into a desired shape, removing the liquid lubricant, and then stretching in uniaxial or multiaxial directions.
• the material of the positive electrode current collector is not particularly limited, and for example, conductive metals such as aluminum, aluminum alloy, SUS (stainless steel), and titanium can be used. Among these, aluminum is preferred from the viewpoint of being easy to process into a thin film and being inexpensive.
• the positive electrode active material may be any cathode active material as long as it can absorb and release ions, and conventionally known positive electrode active materials can be used.
• M 3 CoO 2 , M 3 NiO 2 , M 3 MnO 2 , M 3 Ni x Co y Mnz O 2 and M 3 Ni x Co y Al z O 2 (x, y, z are x+y+z 1, 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1)
• Composite metal oxides such as ternary oxides
• Olivine structure such as nickel manganic acid
• positive electrode active materials may be used alone or in combination.
• a battery configured with a positive electrode containing such a positive electrode active material is one of the preferred embodiments of the present invention.
• Examples of the conductive aid include acetylene black, carbon black, graphite, metal powder materials, single-walled carbon nanotubes, multi-walled carbon nanotubes, and vapor-grown carbon fibers.
• fluorine-based resins such as polyvinylidene fluoride and polytetrafluoroethylene; synthetic rubbers such as styrene-butadiene rubber and nitrile-butadiene rubber; polyamide-based resins such as polyamide-imide; polyolefin-based resins such as polyethylene and polypropylene; ; poly(meth)acrylic resin; polyacrylic acid; cellulose resin such as carboxymethyl cellulose; and the like.
• binders may be used alone or in combination. Moreover, these binders may be in a state dissolved in a solvent or in a state dispersed in a solvent at the time of use.
• the blending amounts of the conductive aid and the binder can be appropriately adjusted in consideration of the purpose of use of the battery (emphasis on output, emphasis on energy, etc.), ionic conductivity, and the like.
• examples of the solvent used in the positive electrode active material composition include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, tetrahydrofuran, acetonitrile, acetone, ethanol, ethyl acetate, water, and the like. These solvents may be used in combination.
• the amount of the solvent used is not particularly limited, and may be appropriately determined depending on the manufacturing method and the materials used.
• the negative electrode constituting the above battery is not particularly limited, but a negative electrode active material composition containing a negative electrode active material, a dispersion solvent, a binder, and if necessary a conductive aid, etc. is supported on a negative electrode current collector. It is usually shaped into a sheet.
• conductive metals such as copper, iron, nickel, silver, and stainless steel (SUS) can be used. Note that copper is preferred from the viewpoint of ease of processing into a thin film.
• any conventionally known negative electrode active material used in batteries may be used as long as it is capable of intercalating and releasing ions.
• metal alloys such as alkali metals and alkali metal-aluminum alloys, graphite materials such as artificial graphite and natural graphite, mesophase fired bodies made from coal and petroleum pitch, carbon materials such as non-graphitizable carbon, and Si , Si alloy, SiO, and other Si-based negative electrode materials, and Sn-based negative electrode materials such as Sn alloys can be used.
• the negative electrode As a method for manufacturing the negative electrode, a method similar to that for manufacturing the positive electrode can be adopted. Further, the conductive aid, binder, and solvent for material dispersion used in manufacturing the negative electrode are the same as those used in the positive electrode.
• the separator is arranged to separate the positive electrode and the negative electrode.
• the separator constituting the battery is not particularly limited, and commonly used separators can be used.
• Examples of the separator include porous sheets made of polymers that can absorb and retain nonaqueous electrolytes (eg, polyolefin microporous separators, cellulose separators, etc.), nonwoven fabric separators, porous metal bodies, and the like.
• polyolefin-based microporous separators are suitable because they have the property of being chemically stable to organic solvents.
• Examples of the material for the porous sheet include polyethylene, polypropylene, and a laminate having a three-layer structure of polypropylene/polyethylene/polypropylene.
• non-woven fabric separator examples include cotton, rayon, acetate, nylon, polyester, polypropylene, polyethylene, polyimide, aramid, glass, etc., depending on the mechanical strength etc. required for the non-aqueous electrolyte layer.
• the above-mentioned materials can be used alone or in combination.
• the method for evaluating the physical properties of the non-aqueous electrolyte and battery characteristics is as follows. (Evaluation of storage stability of non-aqueous electrolyte) 10 ml of the non-aqueous electrolyte was poured into a PFA (fluororesin) container, the PFA container was sealed and wrapped in an aluminum laminated zipper, and stored in a constant temperature bath set at 60° C. for an arbitrary period of time. The electrolyte solution after storage was diluted 100 times with ultrapure water, and the sulfate ion (SO 4 2- ) concentration was measured by ion chromatography as described below.
• Storage stability was evaluated using the following formula (4) based on the relative amount of sulfate ions when the concentration of sulfate ions in the electrolytic solution to which no disilane compound was added was set to 100.
• Relative amount of sulfate ions (%) Sulfate ion concentration when disilane compound is included / Sulfate ion concentration when disilane compound is not included x 100 (4) (ion chromatography measurement)
• the nonaqueous electrolyte was diluted 100 times with ultrapure water to prepare a measurement solution, and the amount contained in the nonaqueous electrolyte was measured using the ion chromatography system ICS-3000 (manufactured by Nippon Dionex Co., Ltd.) under the following measurement conditions.
• DCR increase rate, capacity maintenance rate (i) DCR
• the aged lithium ion secondary battery (cell) was CCCV charged at 4.2 V and 1 C (30 mA) at room temperature. After 30 minutes, it was discharged at 0.2C (6mA) for 10 seconds, then after being left for 30 minutes, it was discharged at 1C (30mA) for 10 seconds, and after being left for another 30 minutes, it was CC discharged at 3C (90mA) for 10 seconds.
• Each discharge current was plotted on the horizontal axis, and the difference ( ⁇ V) between the closed circuit voltage at the start of discharge and 10 seconds later at each discharge current was plotted on the vertical axis, and the slope of the IV straight line was defined as the DCR of the cell.
• LiFSI manufactured by Nippon Shokubai Co., Ltd.
• LiPF 6 tella Non-aqueous electrolytes (hereinafter also simply referred to as "electrolytes") with various salt concentrations were prepared by dissolving the following solutions (manufactured by Chemipha Co., Ltd.). A disilane compound was further added to some of the electrolytic solutions at concentrations shown in Table 1 to prepare non-aqueous electrolytic solutions.
• the obtained positive electrode composite slurry was applied to aluminum foil (positive electrode current collector, manufactured by Nippon Foil Co., Ltd., thickness 15 ⁇ m) so that the coating weight after drying was 19.4 mg/ cm2 . It was coated on one side with an applicator and dried on a hot plate at 110°C for 10 minutes. Furthermore, it was dried for 12 hours in a vacuum drying oven at 110°C. Thereafter, a sheet-shaped positive electrode (thickness: 83 ⁇ m) was obtained by pressure molding using a roll press machine until the density was 3.1 g/cm 3 .
• (iv) Cell aging process The cell obtained in (iii) above was aged using a charge/discharge test device (manufactured by Asuka Electronics Co., Ltd., product number: ACD-01, same hereinafter). Specifically, constant current (CC) charging was performed at 0.1 C (3 mA) for 3 hours at room temperature (25° C., the same applies hereinafter), and the battery was left at room temperature for 48 hours. After standing, the excess laminate was opened and the cell was vacuum-sealed to degas the cell. Further, after constant current constant voltage (CCCV) charging was performed at 4.2 V and 0.5 C (15 mA) at room temperature, CC discharge was performed at 2.75 V and 0.2 C (6 mA).
• CCCV constant current constant voltage
• CC discharge is performed at 2.75V, 1C (30mA)
• CC discharge is performed at 2.75V, 2C (60mA)
• CC discharge was performed at 2.75V and 0.2C (6mA). The above was the cell aging process.
• LiFePO 4 is an iron phosphate positive electrode active material, acetylene black is used as a conductive agent, and polyvinylidene fluoride (PVdF, manufactured by Kureha Co., Ltd., product number: KF1120) is used as a binder.
• the obtained positive electrode composite slurry was applied to aluminum foil (positive electrode current collector, manufactured by Nippon Foil Co., Ltd., thickness 15 ⁇ m) so that the coating weight after drying was 20.0 mg/cm 2 . It was coated on one side with an applicator and dried on a hot plate at 110°C for 10 minutes. Furthermore, it was dried for 12 hours in a vacuum drying oven at 110°C. Thereafter, a sheet-like positive electrode (thickness: 129 ⁇ m) was obtained by pressure molding using a roll press machine until the density was 1.6 g/cm 3 .
• the obtained negative electrode composite slurry was applied to copper foil (negative electrode current collector, manufactured by Fukuda Metal Foil & Powder Industries Co., Ltd., thickness 15 ⁇ m) so that the coating weight after drying was 8.7 mg/cm 2 . It was coated on one side with an applicator and dried on a hot plate at 80°C for 10 minutes. Furthermore, it was dried for 12 hours in a vacuum drying oven at 100°C. Thereafter, a sheet-shaped negative electrode (thickness: 73 ⁇ m) was obtained by pressure molding using a roll press machine until the density was 1.2 g/cm 3 .
• the disilane compound represented by the above formula (2) is added to the nonaqueous electrolyte containing the sulfonylimide compound represented by the above formula (1) at a concentration of 0.1 mol/L or more. It was revealed that the product has excellent stability when stored in a high-temperature environment, and can suppress an increase in DCR.

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• 2023
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