WO2019189414A1 - 非水系電解液及びそれを用いた蓄電デバイス - Google Patents
非水系電解液及びそれを用いた蓄電デバイス Download PDFInfo
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- WO2019189414A1 WO2019189414A1 PCT/JP2019/013280 JP2019013280W WO2019189414A1 WO 2019189414 A1 WO2019189414 A1 WO 2019189414A1 JP 2019013280 W JP2019013280 W JP 2019013280W WO 2019189414 A1 WO2019189414 A1 WO 2019189414A1
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- 0 C*C(C)(c1ccccc1)c1c(*)c(*)c(*)c(*)c1* Chemical compound C*C(C)(c1ccccc1)c1c(*)c(*)c(*)c(*)c1* 0.000 description 9
- HHZBXAVEEKIRMO-UHFFFAOYSA-N C=NC1OCCCOC1 Chemical compound C=NC1OCCCOC1 HHZBXAVEEKIRMO-UHFFFAOYSA-N 0.000 description 1
- RPLSBADGISFNSI-UHFFFAOYSA-N CC1(C)OCCCO1 Chemical compound CC1(C)OCCCO1 RPLSBADGISFNSI-UHFFFAOYSA-N 0.000 description 1
- LSEVJUQNMUCFKW-UHFFFAOYSA-N CC1COC(C)(C)OC1 Chemical compound CC1COC(C)(C)OC1 LSEVJUQNMUCFKW-UHFFFAOYSA-N 0.000 description 1
- PNKOSUMBMGVBPO-UHFFFAOYSA-N CC1OC(C)(C)CCC1 Chemical compound CC1OC(C)(C)CCC1 PNKOSUMBMGVBPO-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
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- 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
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F19/00—Metal compounds according to more than one of main groups C07F1/00 - C07F17/00
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
- C07F7/02—Silicon compounds
- C07F7/08—Compounds having one or more C—Si linkages
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- C—CHEMISTRY; METALLURGY
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- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
- C07F9/02—Phosphorus compounds
- C07F9/28—Phosphorus compounds with one or more P—C bonds
- C07F9/30—Phosphinic acids R2P(=O)(OH); Thiophosphinic acids, i.e. R2P(=X)(XH) (X = S, Se)
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
- C07F9/02—Phosphorus compounds
- C07F9/28—Phosphorus compounds with one or more P—C bonds
- C07F9/30—Phosphinic acids R2P(=O)(OH); Thiophosphinic acids, i.e. R2P(=X)(XH) (X = S, Se)
- C07F9/307—Acids containing the structure -C(=X)-P(=X)(R)(XH) or NC-P(=X)(R)(XH), (X = O, S, Se)
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- H—ELECTRICITY
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- 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
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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
- H01M10/056—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
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/002—Inorganic electrolyte
- H01M2300/0022—Room temperature molten salts
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
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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
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
- H01M2300/0028—Organic electrolyte characterised by the solvent
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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
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
- H01M2300/0028—Organic electrolyte characterised by the solvent
- H01M2300/0037—Mixture of solvents
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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
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0048—Molten electrolytes used at high temperature
- H01M2300/0051—Carbonates
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to a non-aqueous electrolyte and an electricity storage device using the same.
- an electrolyte such as LiPF 6 , LiBF 4 , LiN (CF 3 SO 2 ) 2 , LiCF 3 (CF 2 ) 3 SO 3 is used as a high dielectric constant such as ethylene carbonate or propylene carbonate.
- a typical example is a non-aqueous electrolyte solution dissolved in a mixed solvent of a solvent and a low-viscosity solvent such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate.
- Carbonaceous materials that can occlude and release lithium ions are mainly used as negative electrode active materials for lithium ion secondary batteries, and natural graphite, artificial graphite, amorphous carbon, etc. are typical examples.
- metal or alloy negative electrodes using silicon, tin or the like for increasing the capacity are also known.
- the positive electrode active material a transition metal composite oxide capable of mainly occluding and releasing lithium ions is used, and representative examples of the transition metal include cobalt, nickel, manganese, iron and the like.
- Such a lithium ion secondary battery uses a highly active positive electrode and negative electrode, and it is known that the charge / discharge capacity decreases due to a side reaction between the electrode and the electrolyte, improving battery characteristics. Therefore, various studies have been made on non-aqueous organic solvents and electrolytes.
- Patent Documents 1 to 3 propose a technique that uses a compound having an alkyloxycarbonyl skeleton, provides a non-aqueous electrolyte battery with low gas generation, high capacity, excellent storage characteristics and cycle characteristics.
- a technique for adding a salt such as a monolithium salt of a phosphorus-containing compound having a P ⁇ O structure has been studied.
- Patent Document 4 discloses that after exposure to a high-temperature environment by adding a phosphate ester salt.
- a technique that can suppress a decrease in charge / discharge characteristics and also suppress an increase in internal resistance.
- Patent Document 5 discloses a technique that can improve low-temperature discharge characteristics particularly after high-temperature storage by using an electrolytic solution containing at least one lithium phosphate in which a specific polar group is directly bonded to a phosphorus atom. Proposed.
- Patent Document 1 has been evaluated up to cycle characteristics, it does not show a result of suppressing internal resistance important for high output directly or indirectly. Also, Patent Documents 2 and 3 do not show the result of suppressing internal resistance important for high output directly or indirectly.
- Patent Document 4 since a cycle evaluation using a tripolar cell using a metal foil as a counter electrode is performed, loss due to a side reaction at the time of charging due to replenishment of the metal ions from the counter electrode metal foil. Is reset and the original cycle characteristics cannot be evaluated. Moreover, only the evaluation in only 5 cycles is specifically examined as an example. Moreover, although it is said that the resistance of the electrode was comparatively evaluated by AC impedance measurement after holding at 60 ° C., the holding time at 60 ° C. is unknown, and it is unknown how and what part of the measurement result was compared, The body of the evaluation result is not made, such as the influence of the metal foil as the counter electrode is not separated.
- Patent Document 5 reports a result that the retention rate of the low-temperature discharge capacity after high-temperature exposure is high.
- the absolute capacity as a reference or the relative capacity with respect to the comparative example is not presented, and it is not shown whether the high capacity can actually be maintained. Further, there is no removal method that can determine the internal resistance, and further, cycle characteristics that repeat charging and discharging are not implemented.
- the present invention has been made to solve the above problems, and is excellent in an initial resistance suppressing effect in an electricity storage device, and further, a static test such as a high temperature storage test and a dynamic test such as a high temperature cycle test. It is an object of the present invention to provide a non-aqueous electrolyte that maintains the resistance suppressing effect while being excellent in the basic characteristic of capacity retention ratio after any of the durability tests, and an electricity storage device using the non-aqueous electrolyte.
- the gist of the present invention is as follows.
- P and O are element symbols, not abbreviations.
- X 1 and X 2 each independently represent C, S or P.
- n 1 and n 2 are each independently 1 when X 1 and X 2 are C or P, and 2 when S 1 or S 2.
- n 1 is 1 when X 1 is C or P, and 2 when S 1 is S.
- n 2 is 1 when X 2 is C or P, and 2 when S 2 is S.
- Y 1 and Y 2 each independently represents a hydrocarbon group or —OW group which may have a substituent (W represents a hydrocarbon which may have a substituent).
- m 1 is 1 when X 1 is C or S, and 2 when P is 1, and m 2 is 1 when X 2 is C or S, and 2 when P 2 is P.
- Z represents a hydrocarbon group that may have a substituent, a —SiV 3 group (V represents a hydrocarbon group that may have a substituent), an organic onium, or a metal. )
- Y 1 and Y 2 are each independently a C 1-6 alkyl group in which part of the hydrogen atom may be substituted with a halogen atom, part of the hydrogen atom Is an alkenyl group having 2 to 6 carbon atoms which may be substituted with a halogen atom, an alkynyl group having 2 to 6 carbon atoms in which a part of hydrogen atoms may be substituted with a halogen atom, and a part of hydrogen atoms being halogen A group selected from the group consisting of an aryl group having 6 to 12 carbon atoms which may be substituted with an atom and an arylalkyl group having 7 to 13 carbon atoms which may be partially substituted with a halogen atom.
- W is an alkyl group having 1 to 6 carbon atoms in which a part of hydrogen atoms may be substituted with halogen atoms, or a group having 2 to 6 carbon atoms in which some hydrogen atoms may be substituted with halogen atoms
- Alkenyl group, one of the hydrogen atoms Is an alkynyl group having 2 to 6 carbon atoms that may be substituted with a halogen atom, an aryl group having 6 to 12 carbon atoms that may be partially substituted with a halogen atom, and a portion of hydrogen atoms being halogen
- Z may be an alkyl group having 1 to 6 carbon atoms in which a part of hydrogen atoms may be substituted with a halogen atom, or a part of hydrogen atoms may be substituted with a halogen atom.
- a group selected from the group consisting of an aryl group having 6 to 12 carbon atoms and an arylalkyl group having 7 to 13 carbon atoms in which a part of hydrogen atoms may be substituted with a halogen atom, or V is a hydrogen atom Alkyl group having 1 to 6 carbon atoms that may be partially substituted with halogen atoms, Alkenyl group having 2 to 6 carbon atoms that may be partially substituted with halogen atoms, or part of hydrogen atoms Is replaced by a halogen atom
- An alkynyl group having 2 to 6 carbon atoms, a part of hydrogen atom may be substituted with a halogen atom, an
- the non-aqueous electrolyte further includes a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, an aromatic compound, carbon -Cyclic carbonate having carbon unsaturated bond, fluorine-free carboxylic acid ester, cyclic compound having plural ether bonds, compound having isocyanuric acid skeleton, monofluorophosphate, difluorophosphate, borate, oxalic acid
- the nonaqueous electrolytic solution according to any one of [1] to [6], which contains at least one compound selected from the group consisting of a salt and a fluorosulfonate.
- An electricity storage device comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte solution is any one of [1] to [9]
- An electricity storage device comprising the non-aqueous electrolyte according to claim 1.
- the present invention it is excellent in the initial resistance suppression effect, and further excellent in the basic characteristic of the capacity retention rate after the durability test such as the high temperature storage test and the high temperature cycle test, while maintaining the resistance lowering effect, the battery characteristics It is possible to provide a non-aqueous electrolyte for realizing an electricity storage device excellent in the above. Thereby, miniaturization and high performance of the electricity storage device can be achieved.
- the effect of suppressing the initial resistance is suppressed while maintaining the capacity retention rate even after durability tests such as a high temperature storage test and a high temperature cycle test
- the action / principle for maintaining the effect is not clear, but it is considered as follows.
- the present invention is not limited to the operations and principles described below.
- Patent Documents 1 to 3 have a low ability to adsorb to the positive electrode transition metal in an unreacted state in an uncharged / initial stage of charge, and are accompanied by a reaction. In order to express the effect, the function of protecting the surface is not expressed in the initial stage, and therefore, it is considered that the effect of suppressing the increase in resistance is not seen.
- Patent Documents 4 and 5 and the present invention are compounds having a plurality of ionic and polar functional groups, so that they can be stably adsorbed to the positive electrode transition metal in an unreacted state in an uncharged / charged initial stage. It is possible to develop the function of protecting the surface in the initial stage.
- the most important characteristic is whether the charged positive electrode can prevent contact with the electrolyte component due to the surface adsorbate. Unlike the cycle test in which charging and discharging are repeated continuously, no deterioration behavior is observed in which the surface adsorbate reacts or peels in a dynamic environment such as insertion and desorption of lithium.
- the compound represented by the formula (1) used in the non-aqueous electrolyte of the present invention has two X ⁇ O bonds (X is C, P, S), which is a polar group different from an alkyl group or an alkoxyl group. By bonding with the phosphorus element, it is presumed that it becomes easier to coordinate to the positive electrode metal with this skeleton and the P ⁇ O skeleton.
- the compound represented by the formula (1) has a structure that has Li + in advance or can be easily converted into a salt having Li + as a cation species. It is considered that the adsorbed compound represented by the formula (1) mediates the Li and does not inhibit the insertion / elimination reaction.
- the compound represented by the formula (1) that initially adsorbed the deterioration of the positive electrode that has already started is suppressed, and Li insertion / desorption reaction is not inhibited, It is considered that the effect of suppressing the increase in resistance is expressed from the beginning.
- the compound represented by the formula (1) since the compound represented by the formula (1) has a PX (X is C, P, S) bond that is not easily cleaved, the structure is fragmented by the reaction and easily detached from the surface. Since there is a low possibility that the characteristics deteriorate, it is considered that the effect is not lost even after a long-term dynamic test such as a cycle test.
- Nonaqueous Electrolytic Solution contains an electrolyte, a nonaqueous solvent, and a compound represented by the following formula (1).
- the non-aqueous electrolyte solution of the present invention contains a compound represented by formula (1).
- optical isomers cannot be distinguished, and the isomers can be used alone or as a mixture thereof.
- X 1 and X 2 in formula (1) each independently represent C, S or P.
- X 1 and X 2 are preferably C from the viewpoint of ease of production.
- N 1 in Formula (1) is 1 when X 1 is C or P, and 2 when S 1 is S.
- n 2 is 1 when X 2 is C or P, and 2 when X 2 is S.
- Y 1 and Y 2 in Formula (1) each independently represent a hydrocarbon group or —OW group (W is an optionally substituted hydrocarbon) which may have a substituent.
- W is an optionally substituted hydrocarbon
- the hydrocarbon group which may have a substituent is preferably an alkyl group having 1 to 6 carbon atoms which may have a substituent, more preferably a substituted group.
- alkyl group having 1 to 6 carbon atoms which may have a substituent is preferable, and an alkyl group having 1 to 4 carbon atoms which may have a substituent is preferable.
- Alkyl groups are particularly preferred. If the molecular weight with respect to the chemical structure contributing to the effect or the size of the molecule itself becomes too large, there is a possibility that a sufficient effect cannot be expressed.
- the substituent which may be present is preferably a halogen atom, and particularly preferably a fluorine atom.
- a halogen atom in particular a fluorine atom, is expected to exhibit the same characteristics as no substitution due to low unnecessary reactivity.
- alkyl group examples include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, 2-fluoroethyl group, 2,2 , 2-trifluoroethyl group is preferable, and methyl group, ethyl group, and 2,2,2-trifluoroethyl group are more preferable.
- alkenyl group examples include ethenyl group, 1-propenyl group, 2-propenyl group, 1-methylethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-methyl-1-propenyl group, 2 -Methyl-1-propenyl group, 1-methyl-2-propenyl group, 2-methyl-2-propenyl group, trifluoroethynyl group are preferred, ethenyl group, 1-propenyl group, 2-propenyl group, 1-methylethenyl group Is more preferable.
- the alkynyl group is preferably an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, or a 3-butynyl group, and more preferably ethynyl or 2-propynyl.
- aryl group phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 2,3- Dimethylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 1-naphthalenyl group, 2 -Naphthalenyl 1-fluorophenyl group, 2-fluorophenyl group, 3-fluorophenyl group, pentafluorophenyl group are preferred, phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2, 3-dimethylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group
- the alkylaryl group includes phenylmethyl group, diphenylmethyl group, 1-phenylethyl group, 2-phenylethyl group, 1-phenylpropyl group, (1-phenyl-1-methyl) ethyl group, (2-methyl Phenyl) methyl group, (3-methylphenyl) methyl group, (4-methylphenyl) methyl group, (2,5-dimethylphenyl) methyl group, (2,4,6-trimethylphenyl) methyl group, (1- (Fluorophenyl) methyl group, (2-fluorophenyl) methyl group, (3-fluorophenyl) methyl group, (2,4-difluorophenyl) methyl group, (3,4-difluorophenyl) methyl group, (3- (4-difluorophenyl) methyl group, (3- (4-difluorophenyl) methyl group, (3- (4-difluorophenyl)
- M 1 in Formula (1) is when X 1 is C or S when the 1, P 2.
- M 2 is 1 when X 2 is C or S, and 2 when P 2 is P.
- Z represents a hydrocarbon group that may have a substituent, a —SiV 3 group (V represents a hydrocarbon group that may have a substituent), an organic onium, or a metal. ).
- Z is a hydrocarbon group which may have a substituent
- V when Z is a hydrocarbon group which may have a substituent, preferred for V when Z is a —SiV 3 group, preferred for Y 1 , Y 2 and W and
- the reason is the same including the reason, but among them, methyl group, ethyl group, i-propyl group, n-butyl group, t-butylvinyl group, ethynyl group, 2-propynyl group, phenyl group, pentafluorophenyl group are desirable. .
- the —SiV 3 group includes a trimethylsilyl group, an ethyldimethylsilyl group, a dimethyl-n-propylsilyl group, a dimethyl-i-propylsilyl group, a dimethyl-n-butylsilyl group, a dimethyl-t-butylsilyl group, and a diethyl-i- group.
- Propylsilyl group triethylsilyl group, tri-i-propylsilyl group, tri-n-butylsilyl group, ethynyldimethylsilyl group, dimethyl-2-propynylsilyl group, dimethylphenylsilyl group, methyldiphenylsilyl group, dimethyl (phenylmethyl) ) Silyl group, t-butyldiphenylsilyl group, triphenylsilyl group, dimethyl (pentafluorophenyl) silyl group, dimethyl (2,2,2-trifluoroethyl) silyl group and the like.
- a trimethylsilyl group preferred are a trimethylsilyl group, a dimethyl-t-butylsilyl group, a tri-i-propylsilyl group, an ethynyldimethylsilyl group, a dimethylphenylsilyl group, and a triphenylsilyl group.
- Z is an organic onium
- the type is not particularly limited, but a structure with a proven track record in various organic device electrolyte applications is preferred because of its oxidation-reduction properties, solubility, and industrial availability.
- Quaternary ammonium An onium having a structure or an onium having a quaternary phosphonium structure is preferable, and tetraalkylammonium, tetraalkylphosphonium, and 1,3-dialkylimidazolium are particularly preferable.
- Z is a metal
- the type is not particularly limited, but it is preferably a highly soluble monovalent metal that is not a “transition metal that undergoes oxidation-reduction”, and more specifically, an alkali metal is preferred.
- lithium When used in a battery using lithium such as a lithium ion battery, lithium is preferable.
- sodium When used in a battery using sodium such as a sodium ion battery, sodium is preferable.
- potassium is preferable. It is preferable to select alkali metals such as these because they are the same as ions in the system.
- Z is preferably an alkyl group, —SiV 3 group, or metal, and particularly preferably —SiV 3 group or metal. Further, among these, preferred are as described above.
- Non-Patent Document 1 Zeitschrift for Anorganische und Med Chemie (1985), 530, 16 (In the compound described in Non-Patent Document 1, it is possible to carry out by changing sodium to another alkali metal.
- Non-Patent Document 2 Heteroatom Chemistry (2012), 23, (4), 352
- the compounds represented by formula (1) may be used alone or in combination of two or more.
- the amount of the compound represented by the formula (1) (total amount in the case of two or more) is not particularly limited in order to exhibit the effect of the present invention. In general, it is 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.23% by mass or more, and particularly preferably 0.5% by mass or more.
- it is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less. Within this range, it is possible to efficiently exhibit the resistance suppression effect at the initial stage, the capacity retention ratio after the durability test such as the high temperature storage test and the high temperature cycle test, and the resistance reduction effect maintenance characteristic.
- blending the said compound with the electrolyte solution of this invention is not restrict
- a method of generating the compound in the battery or in the electrolytic solution can be mentioned. Examples of a method for generating the compound include a method in which a compound other than these compounds is added to generate a battery component such as an electrolytic solution by oxidation or hydrolysis. Furthermore, a method of generating a battery by applying an electrical load such as charge / discharge is also mentioned.
- the above compounds are detected from the constituent members, it can be assumed that the total amount is contained in the non-aqueous electrolyte solution. Under this assumption, the following 1-2.
- the specific compounds described in 1) are preferably contained, and the content thereof is not particularly limited, but the total content with respect to the total amount of the nonaqueous electrolytic solution is usually 0.001% by mass or more and 50% by mass or less.
- fluorine-containing cyclic carbonates sulfur-containing organic compounds, phosphorus-containing organic compounds, organic compounds having a cyano group, aromatic compounds, cyclic carbonates having a carbon-carbon unsaturated bond, fluorine-free carboxylic acid esters, and plural At least one compound selected from the group consisting of cyclic compounds having an ether bond is preferable because it forms a good-quality composite film on the negative electrode, and the initial battery characteristics and the battery characteristics after the durability test are improved in a good balance.
- At least one compound selected from the group consisting of a fluorine-containing cyclic carbonate, an organic compound having a cyano group, an aromatic compound, a cyclic carbonate having a carbon-carbon unsaturated bond, and a non-fluorine-containing carboxylic acid ester is contained.
- Cyclic carbonate, cyclic with carbon-carbon unsaturated bond At least one compound are more preferably selected from the group consisting Boneto and fluorine-containing carboxylic acid ester, fluorine-containing cyclic carbonate or carbon - at least one compound selected from cyclic carbonates having a carbon unsaturated bond is particularly preferred.
- the method of blending the above compound with the electrolytic solution of the present invention is not particularly limited.
- a method of generating the compound in the battery or in the electrolytic solution can be mentioned.
- Examples of a method for generating the compound include a method in which a compound other than these compounds is added to generate a battery component such as an electrolytic solution by oxidation or hydrolysis.
- a method of generating a battery by applying an electrical load such as charge / discharge is also mentioned.
- Fluorine-containing cyclic carbonate examples include fluorinated products of cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof.
- fluorinated products of ethylene carbonate hereinafter referred to as “fluorinated ethylene carbonate”).
- fluorinated ethylene carbonate examples include fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms).
- fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferable.
- the electrolytic solution of the present invention by using the compound represented by the formula (1) and a fluorine-containing cyclic carbonate in combination, durability characteristics can be improved in a battery using this electrolytic solution.
- Fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4, Examples include 5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, and the like.
- monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate provide high ionic conductivity to the electrolytic solution, and can easily form a stable interface protective film. preferable.
- the fluorinated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio.
- the amount of the fluorinated cyclic carbonate (total amount in the case of 2 or more types) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% in 100% by mass of the electrolytic solution. % By mass or more, still more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, most preferably 1.2% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass.
- it is more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably 2% by mass or less.
- the amount is 100% by volume in the non-aqueous solvent, preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more. Moreover, it is preferably 50% by volume or less, more preferably 35% by volume or less, and still more preferably 25% by volume or less.
- Fluorinated unsaturated cyclic carbonates may be used alone or in combination of two or more in any combination and ratio.
- the mass ratio of the compound represented by the above formula (1) and the fluorine-containing cyclic carbonate is such that the compound represented by the formula (1): fluorine-containing cyclic carbonate is 1: 100 or more, preferably 10: 100 or more, more preferably 20: 100 or more, further preferably 25: 100 or more, and can be 10000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, and still more preferably 100 : 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. If it is this range, a battery characteristic, especially a durable characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.
- the electrolytic solution of the present invention can further contain a sulfur-containing organic compound.
- the sulfur-containing organic compound is not particularly limited as long as it is an organic compound having at least one sulfur atom in the molecule, but is preferably an organic compound having an S ⁇ O group in the molecule, Sulfonated esters, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites and cyclic sulfites.
- those corresponding to fluorosulfonate are 1-2-2. It is not included in a sulfur-containing organic compound, but is included in a fluorosulfonate that is an electrolyte described later.
- durability characteristics can be improved in a battery using this electrolytic solution.
- a chain sulfonate ester, a cyclic sulfonate ester, a chain sulfate ester, a cyclic sulfate ester, a chain sulfite ester and a cyclic sulfite ester are preferable, and a compound having an S ( ⁇ O) 2 group is more preferable. More preferred are chain sulfonic acid esters and cyclic sulfonic acid esters, and particularly preferred are cyclic sulfonic acid esters.
- sulfur-containing organic compounds examples include the following.
- chain sulfonate esters include fluorosulfonate esters such as methyl fluorosulfonate and ethyl fluorosulfonate; methyl methanesulfonate, ethyl methanesulfonate, 2-propynyl methanesulfonate, 3-butynyl methanesulfonate, 2- Methanesulfonic acid esters such as methyl (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate and 2- (methanesulfonyloxy) propionic acid; methyl vinylsulfonate, ethyl vinylsulfonate, vinyl Alkenyl sulfonates such as allyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate,
- cyclic sulfonate esters examples include 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, and 1-propene.
- 1,3-sultone 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1 -Methyl-1-propene-1,3-sultone, 2-methyl-1-propene-1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1,4-butane sultone and 1,5 -Sultone compounds such as pentane sultone; disulfonate compounds such as methylenemethane disulfonate and ethylenemethane disulfonate.
- Chain sulfate ester examples include dialkyl sulfate compounds such as dimethyl sulfate, ethyl methyl sulfate, and diethyl sulfate.
- cyclic sulfate ester examples include alkylene sulfate compounds such as 1,2-ethylene sulfate, 1,2-propylene sulfate, and 1,3-propylene sulfate.
- Chain sulfites include dialkyl sulfite compounds such as dimethyl sulfite, ethyl methyl sulfite, and diethyl sulfite.
- cyclic sulfites include alkylene sulfite compounds such as 1,2-ethylene sulfite, 1,2-propylene sulfite, and 1,3-propylene sulfite.
- the electrolytic solution of the present invention further contains a phosphorus-containing organic compound (provided that the phosphorus-containing organic compound here is used in the meaning excluding the compound represented by the formula (1)). Can do.
- the phosphorus-containing organic compound is not particularly limited as long as it is an organic compound having at least one phosphorus atom in the molecule.
- a battery using the electrolytic solution of the present invention containing a phosphorus-containing organic compound can improve durability characteristics.
- phosphoric acid ester, phosphonic acid ester, phosphinic acid ester, and phosphorous acid ester are preferable, More preferably, they are phosphoric acid ester and phosphonic acid ester, More preferably, they are phosphonic acid ester.
- electrolytic solution of the present invention by using the phosphorus-containing organic compound together with the compound represented by the formula (1), durability characteristics can be improved in a battery using this electrolytic solution.
- Examples of the phosphorus-containing organic compound include the following.
- phosphate esters include compounds having a vinyl group such as dimethyl vinyl phosphate, diethyl vinyl phosphate, methyl divinyl phosphate, ethyl divinyl phosphate, and trivinyl phosphate; allyl dimethyl phosphate, allyl diethyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, and triaryl phosphate.
- allyl group such as allyl phosphate
- compounds having a propargyl group such as propargyl dimethyl phosphate, propargyl diethyl phosphate, dipropargyl methyl phosphate, dipropargyl ethyl phosphate and tripropargyl phosphate
- 2-acryloyloxymethyldimethyl phosphate 2-acryloyl Oxymethyldiethyl phosphate
- 2-acryloyloxymethyl groups such as (royloxymethyl) methyl phosphate, bis (2-acryloyloxymethyl) ethyl phosphate and tris (2-acryloyloxymethyl) phosphate
- 2-acryloyloxyethyldimethyl phosphate 2-acryloyl
- compounds having a 2-acryloyloxyethyl group such as oxyethyl diethyl phosphate, bis (2-acryloyloxyethyl) methyl phosphate, bis (2-acryloy
- phosphonic acid esters examples include trimethyl phosphonoformate, methyl diethylphosphonoformate, triethyl phosphonoformate, ethyl dimethylphosphonoformate, methyl bis (2,2,2-trifluoroethyl) phosphonoformate, Ethyl bis (2,2,2-trifluoroethyl) phosphonoformate, trimethyl phosphonoacetate, methyl diethyl phosphonoacetate, triethyl phosphonoacetate, ethyl dimethylphosphonoacetate, methyl bis (2,2,2-trimethyl) Fluoroethyl) phosphonoacetate, ethyl bis (2,2,2-trifluoroethyl) phosphonoacetate, allyl dimethylphosphonoacetate, allyl diethylphosphonoacete DOO, 2-propynyl dimethylphosphonoacete DOO, 2-propynyl dimethylphosphon
- triallyl phosphate and tris (2-acryloyloxyethyl) phosphate trimethyl phosphonoacetate, triethylphosphonoacetate, 2-propynyl dimethylphosphonoacetate, 2-propynyldiethylphosphonoacetate Is preferred.
- the phosphorus-containing organic compound may be used alone or in combination of two or more in any combination and ratio.
- the electrolytic solution of the present invention can contain an organic compound having a cyano group.
- the organic compound having a cyano group is not particularly limited as long as it is an organic compound having at least one cyano group in the molecule, but is preferably a formula (2-4-1) or a formula (2-4- 2), more preferably a compound represented by the formula (2-4-2).
- the organic compound having a cyano group is also a cyclic compound having a plurality of ether bonds, it may belong to a cyclic compound having a plurality of ether bonds.
- the molecular weight of the compound represented by the formula (2-4-1) is not particularly limited.
- the molecular weight is preferably 55 or more, more preferably 65 or more, still more preferably 80 or more, preferably 310 or less, more preferably 185 or less, and further preferably 155 or less. Within this range, it is easy to ensure the solubility of the compound represented by the formula (2-4-1) in the nonaqueous electrolytic solution, and the effects of the present invention are easily exhibited.
- the method for producing the compound represented by the formula (2-4-1) is not particularly limited, and can be produced by arbitrarily selecting a known method.
- examples of the hydrocarbon group having 2 to 20 carbon atoms include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and the like, such as an ethyl group, an n-propyl group, and an iso-propyl group.
- a linear or branched alkyl group having 2 to 15 carbon atoms and an alkenyl group having 2 to 4 carbon atoms are included. More preferably, a linear or branched alkyl group having 2 to 12 carbon atoms is more preferable, and a linear or branched alkyl group having 4 to 11 carbon atoms is particularly preferable.
- Examples of the compound represented by the formula (2-4-1) include propionitrile, butyronitrile, pentanenitrile, hexanenitrile, heptanenitrile, octanenitrile, pelargononitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclopentanecarboro Nitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitryl, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl Examples include -2-pentenenitrile and 2-hexenenitrile.
- pentanenitrile, octanenitrile, decanenitrile, dodecanenitrile, and crotononitrile are preferred from the viewpoint of compound stability, battery characteristics, and production, and pentanenitrile, decanenitrile, dodecanenitrile, and crotononitrile are more preferred.
- Pentanenitrile, decane nitrile and crotononitrile are preferred.
- a 2 has 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom. Organic group.
- the organic group having 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom is a carbon atom and
- an organic group that may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, or a halogen atom is included.
- organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom
- a part of the skeleton carbon atom in the group composed of the carbon atom and the hydrogen atom is substituted with these atoms.
- an organic group having a substituent composed of these atoms is substituted with these atoms.
- the molecular weight of the compound represented by the formula (2-4-2) is not particularly limited.
- the molecular weight is preferably 65 or more, more preferably 80 or more, still more preferably 90 or more, preferably 270 or less, more preferably 160 or less, and still more preferably 135 or less. Within this range, it is easy to ensure the solubility of the compound represented by the formula (2-4-2) in the nonaqueous electrolytic solution, and the effects of the present invention are easily exhibited.
- the method for producing the compound represented by the formula (2-4-2) is not particularly limited, and can be produced by arbitrarily selecting a known method.
- a 2 in the compound represented by the formula (2-4-2) is an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, a cycloalkenylene group or a derivative thereof.
- Arylene group or derivative thereof carbonyl group or derivative thereof, sulfonyl group or derivative thereof, sulfinyl group or derivative thereof, phosphonyl group or derivative thereof, phosphinyl group or derivative thereof, amide group or derivative thereof, imide group or derivative thereof, ether Groups or derivatives thereof, thioether groups or derivatives thereof, borinic acid groups or derivatives thereof, borane groups or derivatives thereof, and the like.
- an alkylene group or a derivative thereof an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, an arylene group or a derivative thereof is preferable.
- a 2 is more preferably an alkylene group having 2 to 5 carbon atoms which may have a substituent.
- Examples of the compound represented by the formula (2-4-2) include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile.
- malononitrile succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10 -Tetraoxaspiro [5,5] undecane and fumaronitrile are preferred from the viewpoint of improving high-temperature storage durability characteristics.
- succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, glutaronitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane are The effect of improving the high-temperature storage durability is particularly excellent, and the deterioration due to side reaction at the electrode is small, so that it is more preferable.
- dinitrile compounds the smaller the molecular weight, the larger the proportion of cyano groups in one molecule and the higher the viscosity of the molecule, while the higher the molecular weight, the higher the boiling point of the compound. Therefore, succinosuccinonitrile, glutaronitrile, adiponitrile, and pimelonitrile are more preferable from the viewpoint of improving working efficiency.
- An organic compound having a cyano group may be used alone or in combination of two or more in any combination and ratio.
- the organic compound which has an isocyanate group can contain the organic compound which has an isocyanate group.
- the organic compound having an isocyanate group is not particularly limited as long as it is an organic compound having at least one isocyanate group in the molecule, but the number of isocyanate groups is preferably 1 or more and 4 or less, more preferably 2 in one molecule. Above 3 or less, more preferably 2.
- the electrolytic solution of the present invention by using the compound represented by the formula (1) and the compound having an isocyanate group in combination, durability characteristics can be improved in a battery using this electrolytic solution.
- organic compound having an isocyanate group examples include the following.
- Organic compounds having one isocyanate group such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate; monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, hepta Methylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanate) Natomethyl) cyclohexane, dicyclohexyl Tan-2,2′-
- Organic compounds having two isocyanate groups such as diisocyanate and 2,4,4-trimethylhexame
- the organic compound having an isocyanate group may be used alone or in combination of two or more in any combination and ratio.
- Silicon-containing compound The electrolytic solution of the present invention may contain a silicon-containing compound.
- the silicon-containing compound is not particularly limited as long as it is a compound having at least one silicon atom in the molecule.
- the durability characteristics can be improved by using the compound represented by the formula (1) and the silicon-containing compound in combination.
- Examples of the silicon-containing compound include the following compounds. Tris borate (trimethylsilyl), tris borate (trimethoxysilyl), tris borate (triethylsilyl), tris borate (triethoxysilyl), tris borate (dimethylvinylsilyl) and tris borate (diethylvinylsilyl) Boric acid compounds such as: Tris phosphate (trimethylsilyl), Tris phosphate (triethylsilyl), Tris phosphate (tripropylsilyl), Tris phosphate (triphenylsilyl), Tris phosphate (trimethoxysilyl), Phosphoric acid Phosphorus compounds such as tris (triethoxysilyl), tris (triphenoxysilyl) phosphate, tris (dimethylvinylsilyl) phosphate and tris (diethylvinylsilyl); trisphosphite (trimethylsilyl),
- these silicon containing compounds may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
- Aromatic Compound The electrolytic solution of the present invention can contain an aromatic compound.
- the aromatic compound is not particularly limited as long as it is an organic compound having at least one aromatic ring in the molecule, but is preferably represented by formulas (2-7-1) and (2-7-2) It is an aromatic compound represented.
- Aromatic compound represented by formula (2-7-1) (In the formula, the substituent X 71 represents a halogen atom, a halogen atom or an organic group which may have a hetero atom.
- the organic group which may have a hetero atom is a group having 1 to 12 carbon atoms. straight or branched chain or cyclic saturated hydrocarbon group, a group having a carboxylic acid ester structure, a group having a carbonate structure.
- the number n 71 of the substituents X 71 is 1 to 6, a plurality of substituents And each substituent may be the same or different, and may form a ring.
- a straight chain, branched chain or cyclic saturated hydrocarbon group having 3 to 12 carbon atoms or a group having a carboxylate structure is preferable from the viewpoint of battery characteristics.
- the number n 71 of the substituents X 71 is preferably 1 or more 5 or less, more preferably 1 to 3, still more preferably 1 to 2, particularly preferably 1.
- X 71 represents a halogen atom, a halogen atom or an organic group which may have a hetero atom.
- the halogen atom include chlorine, fluorine and the like, preferably fluorine.
- the organic group having no hetero atom include linear, branched, and cyclic saturated hydrocarbon groups having 3 to 12 carbon atoms.
- the linear and branched groups include those having a ring structure. It is.
- Specific examples of the linear, branched or cyclic saturated hydrocarbon group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopentyl group, and a cyclohexyl group.
- the number of carbon atoms is preferably 3 or more and 12 or less, more preferably 3 or more and 10 or less, still more preferably 3 or more and 8 or less, still more preferably 3 or more and 6 or less, and most preferably 3 or more and 5 or less.
- Examples of the hetero atom constituting the organic group having a hetero atom include an oxygen atom, a sulfur atom, a phosphorus atom, and a silicon atom.
- Examples of the group having an oxygen atom include a group having a carboxylic ester structure and a group having a carbonate structure.
- Examples of those having a sulfur atom include groups having a sulfonate structure.
- Examples of those having a phosphorus atom include a group having a phosphate ester structure, a group having a phosphonate ester structure, and the like.
- Examples of the group having a silicon atom include a group having a silicon-carbon structure.
- Examples of the aromatic compound represented by the formula (2-7-1) include the following.
- X71 being a halogen atom or an organic group which may have a halogen atom, chlorobenzene, fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride, etc.
- fluorobenzene and hexafluorobenzene More preferred is fluorobenzene.
- Examples of X 71 being a hydrocarbon group having 1 to 12 carbon atoms include 2,2-diphenylpropane, cyclopentylbenzene, cyclohexylbenzene, 1,1-diphenylcyclohexane, tert-butylbenzene, and tert-amylbenzene. Preferred are cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene.
- X 71 is a group having a carboxylate structure, such as phenyl acetate, benzyl acetate, 2-phenylethyl acetate, methyl phenylacetate, ethyl phenylacetate, 2,2-dimethyl-methyl phenylacetate, 2,2-dimethyl -Ethyl phenylacetate and the like can be mentioned, and preferably, methyl 2,2-dimethyl-phenylacetate and ethyl 2,2-dimethyl-phenylacetate are mentioned.
- Examples of X 71 having a carbonate structure include diphenyl carbonate and methylphenyl carbonate, preferably methylphenyl carbonate.
- Aromatic compound represented by formula (2-7-2) (Wherein R 11 to R 15 are independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, and R 16 and R 17 are independently carbon atoms. A hydrocarbon group having a number of 1 or more and 12 or less, and at least two of R 11 to R 17 may be combined to form a ring, provided that the formula (2-7-2) is represented by (A) And (B): (A) At least one of R 11 to R 15 is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
- R 11 to R 17 The total number of carbon atoms of R 11 to R 17 is 3 or more and 20 or less, satisfying at least one condition) It is an aromatic compound represented by these. If at least two of R 11 ⁇ R 17 but that together form a ring, it is preferred that two of R 11 ⁇ R 17 form a ring together.
- R 16 and R 17 are each independently a hydrocarbon group having 1 to 12 carbon atoms (for example, an alkyl group or an aryl group), and R 16 and R 17 are combined to form a ring (for example, a hydrocarbon group).
- a cyclic group may be formed.
- R 16 and R 17 are preferably hydrocarbon groups having 1 to 12 carbon atoms, or hydrocarbons formed by combining R 16 and R 17 together.
- a cyclic group which is a group, more preferably a methyl group, an ethyl group, a cyclohexyl group or a cyclopentyl group formed by combining R 16 and R 17 , and more preferably a methyl group, an ethyl group, or R 16. And R 17 together form a cyclohexyl group.
- R 11 to R 15 are independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group, an aryl group, an aralkyl group). They may be joined together to form a ring (for example, a cyclic group which is a hydrocarbon group).
- hydrogen, fluorine, unsubstituted or halogen-substituted hydrocarbon group having 1 to 12 carbon atoms more preferably hydrogen, fluorine, tert-butyl group, A 1-methyl-1-phenyl-ethyl group, more preferably hydrogen, a tert-butyl group, or a 1-methyl-1-phenyl-ethyl group.
- R 11 to R 15 and R 16 may be combined to form a ring (for example, a cyclic group which is a hydrocarbon group).
- R 11 and R 16 are combined to form a ring (for example, a cyclic group that is a hydrocarbon group).
- R 17 is preferably an alkyl group.
- Compounds in which R 17 is a methyl group and R 11 and R 16 together form a ring include 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl-1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane and the like.
- Formula (2-7-2) is represented by (A) and (B): (A) At least one of R 11 to R 15 is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms. (B) The total number of carbon atoms of R 11 to R 17 is 3 or more and 20 or less. Satisfies at least one of the conditions.
- Formula (2-7-2) preferably satisfies (A) from the viewpoint of suppressing oxidation on the positive electrode within the normal battery operating voltage range, and from the viewpoint of solubility in the electrolyte, B) is preferably satisfied.
- Formula (2-7-2) may satisfy both (A) and (B).
- the carbon number of the unsubstituted or halogen-substituted hydrocarbon group is preferably 1 or more and 10 or less, more preferably 1 or more and 5 or less, still more preferably 1 or more and 3 or less, and still more preferably. 1 or 2, most preferably 1.
- R 11 to R 17 may be combined to form a ring.
- at least two of R 11 to R 17 may be combined to form a ring.
- carbon that does not correspond to R 11 to R 17 among the carbons forming the ring R 11 to R 15 are not counted as carbon constituting the benzene ring to which they are bonded, and R 16 and R 17 are carbons at the benzyl position.
- the total number of carbon atoms is preferably 3 or more and 14 or less, more preferably 3 or more and 10 or less, from the viewpoint of solubility in the electrolytic solution.
- compounds in which R 17 is a methyl group and R 11 and R 16 together form a ring include 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl -1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane and the like, which satisfy the condition (B).
- Examples of the aromatic compound represented by the formula (2-7-2) include the following.
- R 16 and R 17 are each independently a hydrocarbon group having 1 to 20 carbon atoms (provided that the total of R 16 and R 17 is 3 to 20 carbon atoms), and R 11 to R 15 are A compound that is hydrogen (fills (B)).
- R 11 to R 15 is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (which satisfies (A)).
- R 17 is a hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group having 1 to 20 carbon atoms, preferably a methyl group), and R 11 and R 16 together form a ring.
- the following compounds are preferable from the viewpoint of reducing properties on the initial negative electrode.
- the aromatic compounds may be used alone or in combination of two or more.
- Cyclic carbonate having carbon-carbon unsaturated bond Cyclic carbonate having carbon-carbon unsaturated bond (hereinafter sometimes referred to as “unsaturated cyclic carbonate”) includes a carbon-carbon double bond or a carbon-carbon triple bond. Any cyclic carbonate having a bond is not particularly limited, and any unsaturated carbonate can be used, but a cyclic carbonate having a carbon-carbon double bond is preferred. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.
- unsaturated cyclic carbonates examples include vinylene carbonates, aromatic carbonates, ethylene carbonates substituted with a substituent having a carbon-carbon double bond or carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, Catechol carbonates etc. are mentioned.
- the vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4 , 5-diallyl vinylene carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro Examples include vinylene carbonate.
- ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond or carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5- Vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl -5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate , 4,5 diallyl carbonate, 4-methyl-5-allyl carbonate and the like.
- preferable unsaturated cyclic carbonates to be particularly used in combination are vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4, 5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate DOO, include 4-vinyl-5-ethynyl-ethylene carbonate.
- vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are preferable because they form a more stable interface protective film, vinylene carbonate and vinyl ethylene carbonate are more preferable, and vinylene carbonate is more preferable.
- the production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.
- Unsaturated cyclic carbonates may be used alone or in combination of two or more in any combination and ratio. Moreover, the compounding quantity of unsaturated cyclic carbonate is not restrict
- the compounding amount of the unsaturated cyclic carbonate can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, in 100% by mass of the non-aqueous electrolyte solution. It is preferably 0.5% by mass or more and can be 10% by mass or less, preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2% by mass.
- the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics are reduced, the amount of gas generation is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid the situation.
- the mass ratio of the compound represented by the above formula (1) and the cyclic carbonate having a carbon-carbon unsaturated bond is the compound represented by the formula (1): carbon-carbon unsaturated.
- the cyclic carbonate having a saturated bond can be 1: 100 or more, preferably 10: 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and 10000: 100 or less. Preferably, it is 500: 100 or less, more preferably 300: 100 or less, still more preferably 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. If it is this range, a battery characteristic, especially a durable characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.
- the electrolyte solution of the present invention may contain a fluorine-free carboxylic acid ester.
- durability characteristics can be improved by using a compound represented by the formula (1) and a fluorine-free carboxylic acid ester in combination.
- the fluorine-free carboxylic acid ester is not particularly limited as long as it is a carboxylic acid ester having no fluorine atom in the molecule, but is preferably a fluorine-free chain carboxylic acid ester, more preferably a fluorine-free carboxylic acid ester. It is a saturated chain carboxylic acid ester.
- the total number of carbon atoms of the fluorine-free chain carboxylic acid ester is preferably 3 or more, more preferably 4 or more, still more preferably 5 or more, preferably 7 or less, more preferably 6 or less, still more preferably 5 or less. It is.
- Non-fluorine-containing chain carboxylic acid esters include methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, Saturated chain carboxylic acid esters such as methyl pivalate, ethyl pivalate, n-propyl pivalate, methyl acrylate, ethyl acrylate, n-propyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, etc. Of the unsaturated chain carboxylic acid ester.
- methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, methyl pivalate, ethyl pivalate, and n -Propyl is preferred, and methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, and n-propyl propionate are more preferred from the viewpoint of improving the ionic conductivity due to a decrease in the electrolyte viscosity, and methyl acetate, Methyl propionate, ethyl propionate, and n-propyl propionate are more preferred, and methyl acetate, ethyl propionate, and n-propyl propionate are particularly preferred.
- Fluorine-free carboxylic acid ester may be used alone or in combination of two or more in any combination and ratio.
- the amount of the fluorine-free carboxylic acid ester (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably in 100% by mass of the electrolytic solution. Is 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Most preferably, it is 1 mass% or less.
- the blending amount when the fluorine-free carboxylic acid ester is used as a non-aqueous solvent is preferably 1% by volume or more, more preferably 5% by volume or more, and further preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. Further, it is more preferably 20% by volume or more, and it can be contained at 50% by volume or less, more preferably 45% by volume or less, still more preferably 40% by volume or less. Within such a range, increase in negative electrode resistance is suppressed, and output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics can be easily controlled.
- the mass ratio of the compound represented by the above formula (1) and the fluorine-free carboxylic acid ester is such that the compound represented by the formula (1): the fluorine-free carboxylic acid ester is 1: 100 or more, Preferably it is 10: 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and can be 10000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, More preferably, it is 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. If it is this range, a battery characteristic, especially a durable characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.
- Cyclic compound having a plurality of ether bonds The cyclic compound having a plurality of ether bonds is not particularly limited as long as it is a cyclic compound having a plurality of ether bonds in the molecule, but is preferably represented by the formula (2-10). It is a compound.
- the cyclic compound having a plurality of ether bonds contributes to improvement of the high-temperature storage characteristics of the battery.
- this electrolytic solution is used in combination with the compound represented by the formula (1). In the battery using the battery, durability characteristics can be improved.
- a 15 to A 20 independently represent a hydrogen atom, a fluorine atom, or a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent.
- N 101 is 1 to 4
- n 101 is an integer of 2 or more, the plurality of A 17 and A 18 may be the same or different.
- Two members selected from A 15 to A 20 may be bonded to each other to form a ring. In this case, it is preferable to form a ring structure with A 17 and A 18 .
- the total number of carbon atoms of A 15 to A 20 is preferably 0 or more and 8 or less, more preferably 0 or more and 4 or less, still more preferably 0 or more and 2 or less, and particularly preferably 0 or more and 1 or less.
- an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, and a cyano group, an isocyanato group, an ether group, a carbonate group, a carbonyl group, which may be substituted with a halogen atom or a fluorine atom examples thereof include a carboxy group, an alkoxycarbonyl group, an acyloxy group, a sulfonyl group, a phosphantriyl group, and a phosphoryl group.
- n 101 is preferably an integer of 1 or more, 3 or less, more preferably an integer of 1 or more and 2 or less, and even more preferably n 101 is 2.
- Examples of the hydrocarbon group having 1 to 5 carbon atoms in A 15 to A 20 include monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, alkynyl groups, and aryl groups; alkylene groups, alkenylene groups, alkynylene groups, and arylene groups. Divalent hydrocarbon groups such as, and the like. Of these, an alkyl group and an alkylene group are preferable, and an alkyl group is more preferable.
- An alkyl group having 1 to 5 carbon atoms such as a pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; vinyl group, 1-propenyl Group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, etc.
- an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group is preferable, and an ethylene group, a trimethylene group, a tetramethylene group, and a pentane are more preferable.
- the hydrogen atom, fluorine atom or hydrocarbon group having 1 to 5 carbon atoms in A 15 to A 20 is a group in which a hydrogen atom, fluorine atom or the above substituent and the above hydrocarbon group having 1 to 5 carbon atoms are combined.
- it is a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms which does not have a substituent, and an alkylene group having an ether structure in which part of the carbon chain of the alkylene group is substituted with an ether group. More preferably a hydrogen atom.
- Examples of the cyclic compound having a plurality of ether bonds include the following compounds.
- a cyclic compound having a plurality of ether bonds may be used alone or in combination of two or more in any combination and ratio.
- the electrolytic solution of the present invention may further contain a compound having an isocyanuric acid skeleton.
- the compound having an isocyanuric acid skeleton is not particularly limited as long as it is an organic compound having at least one isocyanuric acid skeleton in the molecule.
- a battery using the electrolytic solution of the present invention containing a compound having an isocyanuric acid skeleton can improve durability characteristics.
- Examples of the compound having an isocyanuric acid skeleton include compounds having the following structure.
- compounds having the following structure are preferred from the viewpoint of the ability to form a negative electrode film.
- a compound represented by a compound having an isocyanuric acid skeleton may be used alone or in combination of two or more in any combination and ratio.
- the electrolytic solution of the present invention may further contain a monofluorophosphate and a difluorophosphate.
- the monofluorophosphate and the difluorophosphate are not particularly limited as long as each salt has at least one monofluorophosphate or difluorophosphate structure in the molecule.
- Durability characteristics can be improved.
- the counter cation in the monofluorophosphate and the difluorophosphate is not particularly limited, and lithium, sodium, potassium, magnesium, calcium, NR 121 R 122 R 123 R 124 (wherein R 121 to R 124 are independently And ammonium represented by a hydrogen atom or an organic group having 1 to 12 carbon atoms.
- the organic group having 1 to 12 carbon atoms represented by R 121 to R 124 of ammonium is not particularly limited.
- the organic group may be substituted with an alkyl group, a halogen atom or an alkyl group which may be substituted with a fluorine atom.
- a cycloalkyl group that may be substituted an aryl group that may be substituted with a halogen atom or an alkyl group, a nitrogen-containing heterocyclic group that may have a substituent, and the like.
- R 121 to R 124 are preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, a nitrogen atom-containing heterocyclic group, or the like.
- the counter cation lithium, sodium, and potassium are preferable, and among these, lithium is preferable.
- monofluorophosphate and difluorophosphate examples include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. Lithium monofluorophosphate and lithium difluorophosphate are preferred, and lithium difluorophosphate is more preferred.
- Monofluorophosphate and difluorophosphate may be used alone or in combination of two or more in any combination and ratio.
- the amount of one or more selected from monofluorophosphate and difluorophosphate (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more. More preferably, it is 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and can be 5% by mass or less, preferably 3% by mass. Hereinafter, it is more preferably 2% by mass or less, further preferably 1.5% by mass or less, and particularly preferably 1% by mass or less. Within this range, the effect of improving the initial irreversible capacity is remarkably exhibited.
- the mass ratio of the compound represented by the above formula (1) and one or more selected from monofluorophosphate and difluorophosphate (total amount in the case of two or more) is represented by formula (1).
- Compound: monofluorophosphate and difluorophosphate are preferably 1:99 to 99: 1, more preferably 10:90 to 90:10, and particularly preferably 20:80 to 80:20. Within this range, the intended characteristics can be improved without degrading other battery characteristics.
- the electrolytic solution of the present invention can further contain a borate.
- the borate is not particularly limited as long as it is a salt having at least one boron atom in the molecule. However, those corresponding to oxalate are not included in “1-2-13 borate” but are included in “1-2-14 oxalate” described later.
- durability characteristics can be improved in a battery using this electrolytic solution.
- Examples of the counter cation in the borate include lithium, sodium, potassium, magnesium, calcium, rubidium, cesium, and barium. Among these, lithium is preferable.
- a lithium salt is preferable, and a lithium borate salt can also be suitably used.
- LiBF 4 LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiBF 3 C 3 F 7 , LiBF 2 (CF 3 ) 2 , LiBF 2 (C 2 F 5 ) 2 , LiBF 2 (CF 3 SO 2 ) 2 , LiBF 2 (C 2 F 5 SO 2 ) 2 and the like.
- LiBF 4 is more preferable because it has an effect of improving initial charge / discharge efficiency, high-temperature cycle characteristics, and the like.
- a borate may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
- the amount of borate (total amount in the case of two or more types) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably. Is 0.3% by mass or more, particularly preferably 0.4% by mass or more, and can be 10.0% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass. % Or less, more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less. Within this range, side reactions of the battery negative electrode are suppressed and resistance is hardly increased.
- the mass ratio of the compound represented by the above formula (1) to the borate is the compound represented by the formula (1) (when used in combination): borate is from 1:99 to 99: 1. 10:90 to 90:10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, side reactions on the positive and negative electrodes in the battery are suppressed, and the resistance of the battery is difficult to increase.
- the ratio of the molar content of borate to the molar content of LiPF 6 in the non-aqueous electrolyte is preferably 0.001 or more and 12 or less. 01 to 1.1 are more preferable, 0.01 to 1.0 are still more preferable, and 0.01 to 0.7 are more preferable. Within this range, side reactions on the positive and negative electrodes in the battery are suppressed, and the charge / discharge efficiency of the battery is improved.
- the electrolyte of the present invention can further contain oxalate.
- the oxalate is not particularly limited as long as it is a compound having at least one oxalic acid structure in the molecule.
- durability characteristics can be improved in a battery using this electrolytic solution.
- a metal salt represented by the formula (2-14-1) is preferable. This salt is a salt having an oxalato complex as an anion.
- M 1 is an element selected from the group consisting of Group 1, Group 2 and Aluminum (Al) in the Periodic Table, and M 2 is a transition metal, Group 13, Group 14 and Group 15 of the Periodic Table
- R 91 is a group selected from the group consisting of halogen, an alkyl group having 1 to 11 carbon atoms and a halogen-substituted alkyl group having 1 to 11 carbon atoms, and a and b are (It is a positive integer, c is 0 or a positive integer, and d is an integer of 1 to 3.)
- M 1 is preferably lithium, sodium, potassium, magnesium, or calcium, and particularly preferably lithium, from the viewpoint of battery characteristics when the electrolytic solution of the present invention is used for a lithium secondary battery.
- M 2 is particularly preferably boron or phosphorus from the viewpoint of electrochemical stability when used in a lithium secondary battery.
- R 91 include fluorine, chlorine, methyl group, trifluoromethyl group, ethyl group, pentafluoroethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, and the like. A trifluoromethyl group is preferred.
- Examples of the metal salt represented by the formula (2-14-1) include lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate; lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) Examples thereof include lithium oxalate phosphate salts such as phosphate and lithium tris (oxalato) phosphate. Of these, lithium bis (oxalato) borate and lithium difluorobis (oxalato) phosphate are preferred, and lithium bis (oxalato) borate is more preferred.
- Oxalates may be used alone or in combinations of two or more in any combination.
- Sulfuric acid derivative salt The electrolytic solution of the present invention may further contain a sulfuric acid derivative salt.
- the sulfuric acid derivative salt is not particularly limited as long as it has at least one sulfuric acid derivative salt structure in the molecule, but it is preferable to ensure stability and solubility in the electrolytic solution.
- halosulfonate which is a monohalide structure of sulfuric acid, a sulfuric monoester salt having a hydrocarbon group which may have a substituent, or a substituent Examples thereof include sulfamate (amide sulfate) having a good hydrocarbon group.
- the halogen of the halosulfonate is not particularly limited, but chlorosulfonate and fluorosulfonate are preferable, and fluorosulfonate is most preferable.
- the sulfuric acid monoester salt having a hydrocarbon group which may have a substituent, and the hydrocarbon group which may have a substituent of the sulfamate having a hydrocarbon group which may have a substituent are particularly limited.
- aryl groups optionally substituted aryls having 7 to 13 carbon atoms Alkyl group, more preferably an aryl group which may having 7 to 11 carbon atoms which may have a substituent. If the molecular weight and the molecular size of the structure having an effect are too large, sufficient effects may not be achieved. Further, these substituents are preferably halogen atoms, and most preferably fluorine atoms. Substitution with a halogen atom, in particular a fluorine atom, is expected to exhibit the same characteristics as no substitution due to low unnecessary reactivity.
- alkyl group examples include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, 2-fluoroethyl group, 2,2 , 2-trifluoroethyl group is preferable, methyl group, ethyl group, 2,2,2-trifluoroethyl group is more preferable.
- the alkenyl group is preferably an ethenyl group, 1-propenyl group, 2-propenyl group, 1-methylethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, trifluoroethynyl group, ethenyl group, A 1-propenyl group, a 2-propenyl group, and a 1-methylethenyl group are more preferable.
- the alkynyl group is preferably an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, or a 3-butynyl group, and more preferably an ethynyl group or a 2-propynyl group.
- aryl group phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 1-fluorophenyl Group, 2-fluorophenyl group, 3-fluorophenyl group and pentafluorophenyl group are preferable, phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 1-fluorophenyl group, 2- More preferred are a fluorophenyl group and a 3-fluorophenyl group.
- the alkylaryl machine includes phenylmethyl, diphenylmethyl, 1-phenylethyl, 2-phenylethyl, (1-fluorophenyl) methyl, (2-fluorophenyl) methyl, (3-fluorophenyl) methyl, (2 , 4-Difluorophenyl) methyl, (3,4-difluorophenyl) methyl, (3- (trifluoromethyl) phenyl) methyl, (4- (trifluoromethyl) phenyl) methyl, (3,5-bis (tri Fluoromethyl) phenyl) methyl, (1-naphthyl) methyl, (2-naphthyl) methyl, and (pentafluorophenyl) methyl are preferred, and phenylmethyl and (pentafluorophenyl) methyl are more preferred.
- methyl sulfate, ethyl sulfate, n-propyl sulfate, 2-propenyl sulfate, phenyl sulfate, (4-methyl) phenyl sulfate, 2,2,2- Trifluoroethyl sulfate is more preferably methyl sulfate, ethyl sulfate, 2-propenyl sulfate, or 2,2,2-trifluoroethyl sulfate.
- the sulfamate include N, N-dimethylsulfamate, N, N-diethylsulfamate, and N, N-phenylsulfamate.
- the compound represented by the above formula (1) and a sulfuric acid derivative salt in combination durability characteristics can be improved in a battery using this electrolytic solution.
- the counter cation in the sulfuric acid derivative salt is not particularly limited, and lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR 121 R 122 R 123 R 124 (wherein R 121 to R 124 are each Independently, it is a hydrogen atom or an organic group having 1 to 12 carbon atoms.
- R 121 ⁇ R 124 is, R 121 ⁇ R 124 in the 1-2-12 is applied.
- the counter cation lithium, sodium, and potassium are preferable, and among these, lithium is preferable.
- fluorosulfonate examples include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, and lithium fluorosulfonate is preferable.
- sulfuric monoester salt lithium methyl sulfate, lithium ethyl sulfate, 2-propenyl lithium sulfate and lithium 2,2,2-trifluoroethyl sulfate are preferable.
- sulfamate lithium N, N-dimethylsulfamate is used. preferable.
- lithium bis (fluorosulfonyl) imide lithium bis (N, N-dimethylaminosulfonyl) imide, lithium bis (N, N-dimethylaminosulfonyl) imide, lithium bis (methoxysulfonyl) imide, lithium bis (ethoxysulfonyl) Imide salts having a fluorosulfonic acid structure such as imide and lithium bis (2,2,2-trifluoroethoxysulfonyl) imide can also be used as the fluorosulfonate.
- a sulfuric acid derivative salt may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
- the content of the sulfuric acid derivative salt (the total amount in the case of two or more types) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further Preferably it is 0.3% by mass or more, particularly preferably 0.4% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably. Is 2% by mass or less, particularly preferably 1% by mass or less. Within this range, there are few side reactions in the battery and resistance is hardly increased.
- the mass ratio of the compound represented by the above formula (1) and the sulfuric acid derivative salt is preferably 1:99 to 99: 1 for the compound represented by the formula (1): sulfuric acid derivative salt: 10:90 to 90: 10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, side reactions in the battery are appropriately suppressed, and high temperature durability characteristics are unlikely to deteriorate.
- Electrolyte There is no restriction
- the salts described in "15. Fluorosulfonate” can also be applied.
- a lithium salt is usually used.
- inorganic lithium salts such as LiPF 6 , LiBF 4, LiClO 4 , LiAlF 4 , LiSbF 6 , LiTaF 6 , LiWF 7 ; lithium tungstates such as LiWOF 5 ; HCO 2 Li, CH 3 CO 2 Li, CH 2 FCO 2 Li, CHF 2 CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 Carboxylic acid lithium salts such as CF 2 CO 2 Li; FSO 3 Li, CH 3 SO 3 Li, CH 2 FSO 3 Li, CHF 2 SO 3 Li, CF 3 SO 3 Li, CF 3 CF 2 SO 3 Li, CF 3 CF 2 SO 3 Li, CF 3 CF 2 CF 2 SO 3 Li, CF 3 CF 2 CF 2 SO 3 Li, CF 3 CF 2 CF 2 SO 3 Li,
- LiPF 6 , LiBF 4, FSO 3 Li, LiN (FSO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , lithium difluorooxalatoborate, lithium bis (oxalato) borate, lithium difluorobis (oxalato) phosphate are more
- LiPF 6 , LiBF 4, FSO 3 Li, LiN (FSO 2 ) 2 , and lithium bis (oxalato) borate have the effect of further improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, cycle characteristics, and the like.
- LiPF 6 is most preferable from the viewpoint of oxidation-reduction stability of the electrolyte.
- LiPF 6 decomposes in the system to produce Lewis acid PF 5 and causes deterioration of electrolyte stability, electrolyte physical properties, and battery characteristics. Therefore, by using together with the compound represented by the formula (1), it is possible to exhibit excellent characteristics as an electrolyte while suppressing the adverse effects caused by the Lewis acid.
- the ratio of the molar content of the compound represented by the formula (1) to the molar content of the electrolyte contained in the non-aqueous electrolytic solution is not particularly limited in order to exhibit the effects of the present invention, but is usually 0.00. 043 or more, preferably 0.050 or more, more preferably 0.075 or more, further preferably 0.080 or more, particularly preferably 0.100 or more, usually 0.935 or less, preferably 0.850 or less. More preferably, it is 0.760 or less, More preferably, it is 0.300 or less, Most preferably, it is 0.200 or less. If it is this range, a battery characteristic, especially a continuous charge durability characteristic can be improved remarkably.
- the ratio of the molar content of the compound represented by the formula (1) to the molar content of the electrolyte is a value obtained by dividing the molar content of the compound represented by the formula (1) by the molar content of the electrolyte. It is a parameter
- the concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolyte solution is in a good range, and good battery performance is ensured.
- the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.25 mol / L or more, more preferably 0.5 mol / L or more, still more preferably 1.1 mol / L or more, and preferably Is 3.0 mol / L or less, more preferably 2.5 mol / L or less, and still more preferably 2.0 mol / L or less. If it is this range, since there is not too little lithium which is a charged particle and a viscosity can be made into an appropriate range, it will become easy to ensure favorable electrical conductivity.
- the salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate can be 0.01% by mass or more, preferably 0.1% by mass. % Or more, and can be 20% by mass or less, preferably 10% by mass or less.
- the electrolyte preferably contains at least one selected from the group consisting of monofluorophosphates, difluorophosphates, borates, oxalates and fluorosulfonates and at least one of the other salts.
- Other salts include the lithium salts exemplified above, and in particular, LiPF 6 , LiBF 4, LiN (FSO 2 ) 2, LiN (FSO 2 ) (CF 3 SO 2 ), LiN (CF 3 SO 2).
- the other salt may be 0.01% by mass or more, preferably 0.1% by mass or more, and 20% by mass from the viewpoint of ensuring an appropriate balance between the conductivity and viscosity of the electrolytic solution. Or less, preferably 15% by mass or less, more preferably 10% by mass or less.
- the fluorosulfonate is not particularly limited as long as it is a salt having at least one fluorosulfonic acid structure in the molecule.
- the electrolytic solution of the present invention by using the compound represented by the above formula (1) and the fluorosulfonate together, durability characteristics can be improved in a battery using this electrolytic solution.
- the counter cation in the fluorosulfonate is not particularly limited, and lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR 131 R 132 R 133 R 134 (wherein R 131 to R 134 are And each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms.
- R 131 ⁇ R 134 is, R 131 ⁇ R 134 in the above 1-2-2 is applied.
- the counter cation lithium, sodium, and potassium are preferable, and among these, lithium is preferable.
- fluorosulfonate examples include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, and the like, preferably lithium fluorosulfonate.
- An imide salt having a fluorosulfonic acid structure such as lithium bis (fluorosulfonyl) imide can also be used as the fluorosulfonic acid salt.
- a fluorosulfonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
- the content of fluorosulfonate (total amount in the case of two or more) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, More preferably, it is 0.3% by mass or more, particularly preferably 0.4% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, Preferably it is 2 mass% or less, Most preferably, it is 1 mass% or less. Within this range, there are few side reactions in the battery and resistance is hardly increased.
- the mass ratio of the compound represented by the above formula (1) and the fluorosulfonate is preferably 1:99 to 99: 1 for the compound represented by the formula (1): fluorosulfonate, 10:90 to 90:10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, side reactions in the battery are appropriately suppressed, and high temperature durability characteristics are unlikely to deteriorate.
- Nonaqueous solvent There is no restriction
- the volume of the non-aqueous solvent is a measured value at 25 ° C., but the measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.
- Cyclic carbonate having no fluorine atom examples include cyclic carbonates having an alkylene group having 2 to 4 carbon atoms.
- cyclic carbonate having an alkylene group having 2 to 4 carbon atoms and having no fluorine atom include ethylene carbonate, propylene carbonate, and butylene carbonate.
- ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.
- cyclic carbonate having no fluorine atom one kind may be used alone, or two kinds or more may be used in arbitrary combination and ratio.
- the blending amount of the cyclic carbonate not having a fluorine atom is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired.
- the blending amount when one kind is used alone is 100 volumes of a non-aqueous solvent. %, 5% by volume or more, more preferably 10% by volume or more.
- the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in ionic conductivity is suppressed, and as a result, the load characteristics of the non-aqueous electrolyte secondary battery are easily set in a favorable range.
- Chain carbonate As the chain carbonate, a chain carbonate having 3 to 7 carbon atoms is preferable, and a dialkyl carbonate having 3 to 7 carbon atoms is more preferable.
- chain carbonates include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, n-butyl methyl carbonate, isobutyl methyl carbonate, tert -Butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, tert-butyl ethyl carbonate and the like.
- dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl are particularly preferable.
- Carbonate is particularly preferable.
- chain carbonates having a fluorine atom (hereinafter sometimes referred to as “fluorinated chain carbonate”) can also be suitably used.
- the number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less.
- the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or may be bonded to different carbons.
- fluorinated chain carbonate examples include fluorinated dimethyl carbonate and derivatives thereof, fluorinated ethyl methyl carbonate and derivatives thereof, and fluorinated diethyl carbonate and derivatives thereof.
- Fluorinated dimethyl carbonate and derivatives thereof include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate, and the like. It is done.
- Fluorinated ethyl methyl carbonate and its derivatives include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2 -Trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate and the like.
- Fluorinated diethyl carbonate and its derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2- Trifluoroethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2, Examples include 2,2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, and the like.
- the chain carbonate one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
- the blending amount of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more in 100% by volume of the non-aqueous solvent.
- the chain carbonate is preferably 90% by volume or less, more preferably 85% by volume or less, in 100% by volume of the nonaqueous solvent.
- Cyclic carboxylic acid ester As the cyclic carboxylic acid ester, those having 3 to 12 carbon atoms are preferable. Specific examples include gamma butyrolactone, gamma valerolactone, gamma caprolactone, epsilon caprolactone, and the like. Among these, gamma butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.
- cyclic carboxylic acid ester one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
- Ether compound As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms in which part of hydrogen may be substituted with fluorine is preferable.
- chain ether having 3 to 10 carbon atoms examples include diethyl ether, di (2,2,2-trifluoroethyl) ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2, , 2-tetrafluoroethyl) ether, ethyl-n-propyl ether, di-n-propyl ether, dimethoxymethane, ethoxymethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-trifluoroethoxy) ) Methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, dimethoxyethane, methoxyethoxyethane, diethoxyethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, And diethylene glycol dimethyl methyl
- Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,4-dioxane, and the like, and fluorinated compounds thereof.
- dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether have high solvating ability to lithium ions and have ion dissociation properties.
- dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferable because they have low viscosity and give high ionic conductivity.
- the ether compounds may be used alone or in combination of two or more in any combination and ratio.
- Sulfone compound As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable.
- the number of sulfonyl groups in one molecule is preferably 1 or 2.
- Examples of the cyclic sulfone having 3 to 6 carbon atoms include trimethylene sulfones, tetramethylene sulfones, hexamethylene sulfones as monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, hexamethylene disulfones as disulfone compounds, etc. Is mentioned.
- tetramethylene sulfones from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.
- the sulfolane is preferably sulfolane and / or a sulfolane derivative (hereinafter sometimes referred to as “sulfolane” including sulfolane).
- sulfolane derivative one in which one or more hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable.
- Examples of the chain sulfone having 2 to 6 carbon atoms include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl.
- the sulfone compounds may be used alone or in combination of two or more in any combination and ratio.
- composition of non-aqueous solvent As the non-aqueous solvent of the present invention, one of the above-exemplified non-aqueous solvents may be used alone, or two or more thereof may be used in any combination and ratio.
- the non-aqueous solvent a combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate can be mentioned.
- the total of the cyclic carbonate having no fluorine atom and the chain carbonate in the non-aqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, and further preferably 90% by volume or more.
- the ratio of the cyclic carbonate having no fluorine atom to the total of the cyclic carbonate and the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more, Moreover, it is preferably 50% by volume or less, more preferably 35% by volume or less, still more preferably 30% by volume or less, and particularly preferably 25% by volume or less.
- the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent may be improved.
- preferable combinations of cyclic carbonate and chain carbonate having no fluorine atom include ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate and diethyl carbonate, ethylene Examples include carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
- those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable, in particular, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, Those containing ethylene carbonate, symmetric chain carbonates and asymmetric chain carbonates such as ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate have cycle characteristics and large current discharge characteristics. This is preferable because of a good balance.
- the asymmetric chain carbonate is preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
- the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 25% by volume or more. Preferably it is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less.
- the load characteristics of the battery may be improved.
- the volume ratio of dimethyl carbonate to ethyl methyl carbonate in all non-aqueous solvents is 1.1 or more in terms of improving the electric conductivity of the electrolyte and improving the battery characteristics after storage. Is preferably 1.5 or more, more preferably 2.5 or more.
- the volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics at low temperatures.
- the non-aqueous electrolyte described above is used for an electricity storage device including a positive electrode and a negative electrode capable of occluding and releasing metal ions.
- the details of the electricity storage device will be described later, but for a non-aqueous electrolyte secondary battery. It is particularly useful.
- An electricity storage device using the non-aqueous electrolyte of the present invention comprises a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent.
- a compound represented by the above formula (1) is contained together with an aqueous solvent.
- An electricity storage device using the non-aqueous electrolyte of the present invention includes a non-aqueous electrolyte secondary battery, a lithium battery, a polyvalent cation battery, a metal-air secondary battery, a secondary battery using an s-block metal other than the above, A lithium ion capacitor and an electric double layer capacitor are preferable, a lithium battery and a lithium ion capacitor are more preferable, and a nonaqueous electrolyte secondary battery and a lithium battery are still more preferable.
- the non-aqueous electrolyte solution used for these electrical storage devices is what is called a gel electrolyte quasi-solidified with a polymer, a filler, or the like.
- the lithium salt of the present invention can also be used as an electrolyte salt of a solid electrolyte.
- the lithium battery using the non-aqueous electrolyte of the present invention includes a current collector and a positive electrode having a positive electrode active material layer provided on the current collector, and a current collector and a negative electrode provided on the current collector.
- a negative electrode having an active material layer and capable of occluding and releasing ions and the above-described non-aqueous electrolyte solution of the present invention are provided.
- the lithium battery in this invention is a general term for a lithium primary battery and a lithium secondary battery.
- the configuration of the lithium battery of the present invention is the same as that of conventionally known lithium batteries except for the above-described non-aqueous electrolyte solution of the present invention.
- a positive electrode and a negative electrode are laminated via a porous film (separator) impregnated with the non-aqueous electrolyte solution of the present invention, and these are housed in a case (exterior body). Therefore, the shape of the lithium battery of the present invention is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.
- Non-aqueous electrolyte solution The non-aqueous electrolyte solution of the present invention described above is used as the non-aqueous electrolyte solution.
- Negative electrode The negative electrode has a negative electrode active material layer on a current collector, and the negative electrode active material layer contains a negative electrode active material.
- the negative electrode active material will be described.
- the negative electrode active material used in the lithium primary battery is not particularly limited as long as it can electrochemically release lithium ions. Specific examples thereof include metallic lithium.
- the negative electrode active material used in the lithium secondary battery is not particularly limited as long as it can electrochemically occlude and release metal ions (for example, lithium ions). Specific examples include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like. These may be used individually by 1 type, and may be used together combining 2 or more types arbitrarily.
- Negative electrode active material examples include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like.
- carbonaceous material used as a negative electrode active material (1) natural graphite, (2) a carbonaceous material obtained by heat-treating an artificial carbonaceous material and an artificial graphite material at least once in the range of 400 to 3200 ° C; (3) a carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different crystallinities and / or has an interface in contact with the different crystalline carbonaceous materials, (4) A carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different orientations and / or has an interface in contact with the carbonaceous materials having different orientations, Is preferably a good balance between initial irreversible capacity and high current density charge / discharge characteristics.
- the carbonaceous materials (1) to (4) may be used alone or in combination of two or more in any combination and ratio.
- artificial carbonaceous material and artificial graphite material of (2) above natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, and those obtained by oxidizing these pitches, needle coke, pitch coke, and Carbon materials that are partially graphitized, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials and their carbides, or carbonizable organic materials are benzene, toluene, xylene, quinoline And a solution dissolved in a low-molecular organic solvent such as n-hexane, and carbides thereof.
- the single metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / metalloid elements (that is, excluding carbon), more preferably aluminum, silicon and tin (hereinafter referred to as “ Simple metals) and alloys or compounds containing these atoms (sometimes abbreviated as “specific metal elements”). These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
- a negative electrode active material having at least one kind of atom selected from a specific metal element, a metal simple substance of any one specific metal element, an alloy composed of two or more specific metal elements, one type or two or more specific types Alloys composed of metal elements and one or more other metal elements, as well as compounds containing one or more specific metal elements, and oxides, carbides, nitrides and silicides of the compounds And composite compounds such as sulfides or phosphides.
- these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.
- compounds in which these complex compounds are complexly bonded to several elements such as simple metals, alloys or non-metallic elements are also included.
- silicon and tin an alloy of these elements and a metal that does not operate as a negative electrode can be used.
- tin a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not operate as a negative electrode, and a nonmetallic element may be used. it can.
- any one simple metal of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element In particular, silicon and / or tin metal simple substance, alloy, oxide, carbide, nitride and the like are preferable from the viewpoint of capacity per unit mass and environmental load.
- the lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but a material containing titanium and lithium is preferable from the viewpoint of high current density charge / discharge characteristics, A lithium-containing composite metal oxide material containing titanium is more preferable, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as “lithium titanium composite oxide”). That is, it is particularly preferable to use a lithium titanium composite oxide having a spinel structure in a negative electrode active material for a non-aqueous electrolyte secondary battery because the output resistance is greatly reduced.
- lithium or titanium of the lithium titanium composite oxide is at least selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. Those substituted with one element are also preferred.
- the metal oxide is a lithium titanium composite oxide represented by the formula (A), and in the formula (A), 0.7 ⁇ x ⁇ 1.5, 1.5 ⁇ y ⁇ 2.3, 0 ⁇ It is preferable that z ⁇ 1.6 because the structure upon doping and dedoping of lithium ions is stable.
- M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb. ]
- compositions represented by the above formula (A) are particularly preferable because of a good balance of battery performance.
- Particularly preferred representative compositions of the above compounds are Li 4/3 Ti 5/3 O 4 in (a), Li 1 Ti 2 O 4 in (b), and Li 4/5 Ti 11/5 O in (c). 4 .
- any known method can be used for producing the electrode as long as the effects of the present invention are not significantly impaired. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to a negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.
- a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a technique such as vapor deposition, sputtering, or plating is also used.
- the current collector for holding the negative electrode active material As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.
- the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, etc. when the current collector is a metal material.
- a metal thin film is preferable, and a copper foil is more preferable.
- a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.
- the binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used in manufacturing the electrode.
- resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; SBR (styrene butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, NBR (Acrylonitrile / butadiene rubber), rubbery polymers such as ethylene / propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene ⁇ Thermoplastic elastomeric polymers such as butadiene / styrene copolymer, styrene / isoprene / styrene block copolymer or hydrogenated products thereof; syndiotactic-1,2-polybutadiene,
- the ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10 mass% or less is still more preferable, and 8 mass% or less is especially preferable. When the ratio of the binder to the negative electrode active material is within the above range, the battery capacity and the strength of the negative electrode can be sufficiently secured.
- the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0 .6% by mass or more is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less.
- the main component contains a fluorine-based polymer typified by polyvinylidene fluoride
- the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. Preferably, it is usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.
- a thickener is usually used to adjust the viscosity of the slurry.
- the thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.
- the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Moreover, it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is still more preferable.
- the ratio of the thickener to the negative electrode active material is in the above range, it is possible to suppress a decrease in battery capacity and an increase in resistance, and it is possible to ensure good coatability.
- the electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g ⁇ cm ⁇ 3 or more, and 1.2 g ⁇ cm ⁇ 3 or more. but more preferably, particularly preferably 1.3 g ⁇ cm -3 or more, preferably 2.2 g ⁇ cm -3 or less, more preferably 2.1 g ⁇ cm -3 or less, 2.0 g ⁇ cm -3 or less Further preferred is 1.9 g ⁇ cm ⁇ 3 or less.
- the density of the negative electrode active material existing on the current collector is in the above range, the negative electrode active material particles are prevented from being destroyed, and an increase in initial irreversible capacity or to the vicinity of the current collector / negative electrode active material interface. While the deterioration of the high current density charge / discharge characteristics due to the reduced permeability of the non-aqueous electrolyte solution can be suppressed, the decrease in battery capacity and the increase in resistance can be suppressed.
- the thickness of the negative electrode plate is designed according to the positive electrode plate to be used, and is not particularly limited.
- the thickness of the composite layer obtained by subtracting the thickness of the metal foil of the core is usually 15 ⁇ m or more, preferably 20 ⁇ m or more. More preferably, it is 30 ⁇ m or more, and usually 300 ⁇ m or less, preferably 280 ⁇ m or less, more preferably 250 ⁇ m or less.
- Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.
- Positive electrode ⁇ Positive electrode active material> The positive electrode active material used for the positive electrode is described below.
- the negative electrode active material used for the lithium primary battery is not particularly limited as long as it can electrochemically occlude lithium ions. Specific examples thereof include graphite fluoride, manganese dioxide, thionyl chloride, iron disulfide, and copper oxide.
- the positive electrode active material used in the lithium secondary battery is not particularly limited as long as it can electrochemically occlude and release metal ions (for example, lithium ions).
- metal ions for example, lithium ions
- lithium and at least one transition metal Substances containing are preferred. Specific examples include lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.
- V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable as the transition metal of the lithium transition metal composite oxide.
- Specific examples include lithium-cobalt composite oxides such as LiCoO 2 and LiNiO 2 .
- lithium transition metal composite oxides Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W, etc. That.
- LiNi 0.5 Mn 0.5 O 2 LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0 .45 Co 0.10 Al 0.45 O 2 , LiMn 1.8 Al 0.2 O 4 , LiMn 1.5 Ni 0.5 O 4 and the like.
- transition metal of the lithium-containing transition metal phosphate compound V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include LiFePO 4 , Li 3 Fe 2 (PO 4 ) 3 , Iron phosphates such as LiFeP 2 O 7, cobalt phosphates such as LiCoPO 4 , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn, Fe , Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other elements.
- lithium phosphate in the positive electrode active material because continuous charging characteristics are improved.
- the lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass with respect to the total of the positive electrode active material and lithium phosphate. %, And the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 5% by mass or less.
- Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.
- these surface adhering substances are dissolved or suspended in a solvent, impregnated and added to the positive electrode active material, and dried.
- the surface adhering substance precursor is dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, It can be made to adhere to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and firing simultaneously.
- the method of making carbonaceous adhere mechanically later in the form of activated carbon etc. can also be used, for example.
- the amount of the surface adhering substance is, by mass, with respect to the positive electrode active material, preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more, and the upper limit, preferably 20% or less, more preferably as the lower limit. Is used at 10% or less, more preferably 5% or less.
- the surface adhering substance can suppress the oxidation reaction of the electrolyte solution on the surface of the positive electrode active material, and can improve the durability of the battery. However, when the amount of adhesion is too small, the effect is not sufficiently exhibited. If the amount is too large, the resistance may increase in order to inhibit the entry and exit of lithium ions.
- a material having a composition different from that attached to the surface of the positive electrode active material is also referred to as a “positive electrode active material”.
- shape examples of the shape of the particles of the positive electrode active material include a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, and a column shape as conventionally used. Moreover, primary particles may aggregate to form secondary particles.
- the tap density of the positive electrode active material is preferably 0.5 g / cm 3 or more, more preferably 0.8 g / cm 3 or more, and further preferably 1.0 g / cm 3 or more.
- the tap density of the positive electrode active material is within the above range, the amount of the dispersion medium and the necessary amount of the conductive material and the binder necessary for forming the positive electrode active material layer can be suppressed. As a result, the filling rate of the positive electrode active material and the battery Capacity can be secured.
- a complex oxide powder having a high tap density a high-density positive electrode active material layer can be formed.
- the tap density is preferably as high as possible, and there is no particular upper limit.
- the tap density is preferably 4.0 g / cm 3 or less, more preferably 3.7 g / cm 3 or less, and still more preferably 3.5 g / cm 3 or less. When it is within the above range, it is possible to suppress a decrease in load characteristics.
- the tap density is defined as the powder packing density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is put in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm. Ask.
- Method for producing positive electrode active material As a manufacturing method of the positive electrode active material, a general method is used as a manufacturing method of the inorganic compound. In particular, various methods are conceivable for producing a spherical or elliptical active material. For example, a transition metal raw material is dissolved or ground and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, dried as necessary, and then added with a Li source such as LiOH, Li 2 CO 3 , LiNO 3 and the like, and then fired at a high temperature to obtain an active material. .
- a Li source such as LiOH, Li 2 CO 3 , LiNO 3 and the like
- the positive electrode active material may be used alone, or one or more of the different compositions may be used in any combination or ratio.
- a combination of LiCoO 2 and LiMn 2 O 4 such as LiNi 0.33 Co 0.33 Mn 0.33 O 2 or a part of this Mn substituted with another transition metal or the like Or a combination with LiCoO 2 or a part of this Co substituted with another transition metal or the like.
- the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. Manufacture of the positive electrode using a positive electrode active material can be performed by a conventional method.
- a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form are pressure-bonded to a positive electrode current collector, or these materials are liquid media
- a positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.
- the content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. Moreover, an upper limit becomes like this. Preferably it is 99 mass% or less, More preferably, it is 98 mass% or less. Within the above range, the electric capacity of the positive electrode active material in the positive electrode active material layer can be secured, and the strength of the positive electrode can be maintained.
- the positive electrode active material layer obtained by coating and drying is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material.
- Density of the positive electrode active material layer is preferably 1.5 g / cm 3 or more as a lower limit, more preferably 2 g / cm 3, and even more preferably at 2.2 g / cm 3 or more, the upper limit is preferably 5 g / cm It is 3 or less, more preferably 4.5 g / cm 3 or less, and still more preferably 4 g / cm 3 or less. Within the above range, good charge / discharge characteristics can be obtained, and an increase in electrical resistance can be suppressed.
- a known conductive material can be arbitrarily used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
- the conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and the upper limit is usually 50% by mass or less, preferably It is used so as to contain 30% by mass or less, more preferably 15% by mass or less. Sufficient electrical conductivity and battery capacity can be ensured within the above range.
- the binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material that can be dissolved or dispersed in the liquid medium used during electrode production may be used.
- Resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, isoprene rubber , Rubber polymers such as butadiene rubber and ethylene-propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / Ethylene copolymer, styrene Thermoplastic elastomeric
- the ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and the upper limit is usually 80% by mass or less, preferably Is 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less.
- the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. On the other hand, if it is too high, battery capacity and conductivity may be reduced.
- the material of the positive electrode current collector is not particularly limited, and a known material can be arbitrarily used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly aluminum, are preferable.
- the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case from the viewpoint of increasing the stability at high output and high temperature.
- the sum of the electrode areas of the positive electrode with respect to the surface area of the exterior of the secondary battery is preferably 15 times or more, more preferably 40 times or more.
- the outer surface area of the outer case is the total area obtained by calculation from the vertical, horizontal, and thickness dimensions of the case part filled with the power generation element excluding the protruding part of the terminal in the case of a bottomed square shape. .
- the geometric surface area approximates the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder.
- the total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in the structure in which the positive electrode mixture layer is formed on both sides via the current collector foil. , The sum of the areas where each surface is calculated separately.
- the thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer obtained by subtracting the metal foil thickness of the core material is preferably as a lower limit with respect to one side of the current collector. Is 10 ⁇ m or more, more preferably 20 ⁇ m or more, and the upper limit is preferably 500 ⁇ m or less, more preferably 450 ⁇ m or less.
- Electrode surface coating (Positive electrode surface coating) Moreover, you may use what adhered the substance of the composition different from this to the surface of the said positive electrode plate.
- Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.
- a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit.
- the electrolytic solution of the present invention is usually used by impregnating this separator.
- the material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired.
- a resin, glass fiber, inorganic material, etc. formed of a material that is stable with respect to the electrolytic solution of the present invention is used, and a porous sheet or a nonwoven fabric-like material having excellent liquid retention is used. Is preferred.
- polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used.
- glass filters and polyolefins are preferable, polyolefins are more preferable, and polypropylenes are particularly preferable.
- One of these materials may be used alone, or two or more of these materials may be used in any combination and ratio, or those laminated may be used.
- a specific example of a laminate of two or more kinds in any combination includes a three-layer separator in which polypropylene, polyethylene, and polypropylene are laminated in this order.
- the thickness of the separator is arbitrary, but is usually 1 ⁇ m or more, preferably 5 ⁇ m or more, more preferably 8 ⁇ m or more, and usually 50 ⁇ m or less, preferably 40 ⁇ m or less, more preferably 30 ⁇ m or less. Within the above range, insulation and mechanical strength can be secured, while battery performance such as rate characteristics and energy density can be secured.
- the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Moreover, it is 90% or less normally, 85% or less is preferable and 75% or less is still more preferable.
- the porosity is in the above range, insulation and mechanical strength can be secured, while film resistance can be suppressed and good rate characteristics can be obtained.
- a thin film shape such as a nonwoven fabric, a woven fabric, or a microporous film is used.
- the thin film shape those having a pore diameter of 0.01 to 1 ⁇ m and a thickness of 5 to 50 ⁇ m are preferably used.
- a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used.
- a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 ⁇ m on both surfaces of the positive electrode and using a fluororesin as a binder.
- the electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed through the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape through the separator. Either is acceptable.
- the ratio of the mass of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. .
- the current collecting structure is not particularly limited, but is preferably a structure that reduces the resistance of the wiring portion and the joint portion.
- a structure formed by bundling the metal core portions of the electrode layers and welding them to the terminals is preferably used.
- the internal resistance increases. Therefore, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance.
- the electrode group has the winding structure described above, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode, respectively, and bundling the terminals.
- the material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, a nickel-plated steel plate, stainless steel, aluminum, an aluminum alloy, a metal such as a magnesium alloy, or a laminated film (laminate film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.
- the metal is welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed sealed structure, or a caulking structure using the above metals via a resin gasket. Things.
- the outer case using the laminate film include a case where a resin-sealed structure is formed by heat-sealing resin layers.
- a resin different from the resin used for the laminate film may be interposed between the resin layers.
- a metal and a resin are joined, so that a resin having a polar group or a modified group having a polar group introduced as an intervening resin is used.
- Resins are preferably used.
- the shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.
- a protective element PTC (Positive Temperature Coefficient) whose resistance increases when abnormal heat generation or excessive current flows, temperature fuse, thermistor, shuts off the current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature at abnormal heat generation A valve (current cutoff valve) or the like can be used. It is preferable to select a protective element that does not operate under normal use at a high current, and it is more preferable that the protective element is designed so as not to cause abnormal heat generation or thermal runaway even without the protective element.
- Multivalent cation battery An oxide material or the like is used for the positive electrode, and a metal such as magnesium, calcium, or aluminum or a compound containing these metals is used for the negative electrode.
- a non-aqueous electrolyte solution in which a magnesium salt, calcium salt, aluminum salt or the like is dissolved in a non-aqueous solvent so as to give the same element as the reactive active material species of the negative electrode, that is, magnesium ion, calcium ion, and aluminum ion.
- a non-aqueous electrolyte for a polyvalent cation battery can be prepared by using and dissolving the compound represented by the formula (1) therein.
- Metal-air battery A metal such as zinc, lithium, sodium, magnesium, aluminum, calcium, or a compound containing these metals is used for the negative electrode. Since the positive electrode active material is oxygen, a porous gas diffusion electrode is used for the positive electrode. The porous material is preferably carbon. In the electrolyte, lithium salt, sodium salt, magnesium salt, aluminum salt, calcium salt, etc. are dissolved in a non-aqueous solvent to give the same element as the negative electrode active material species, that is, lithium, sodium, magnesium, aluminum, calcium, etc.
- the non-aqueous electrolyte for metal-air batteries can be prepared by using the non-aqueous electrolyte and dissolving the compound represented by (1) therein.
- Secondary batteries using s-block metals other than the above s-block elements include Group 1 elements (hydrogen, alkali metals), Group 2 elements (beryllium, magnesium and alkaline earth metals) and By helium, an s-block metal secondary battery refers to a secondary battery using the s-block metal as a negative electrode and / or an electrolyte.
- Specific examples of the s-block metal secondary battery other than the above include lithium-sulfur batteries, sodium-sulfur batteries using sodium as a positive electrode, and sodium ion batteries.
- Lithium ion capacitor A material capable of forming an electric double layer is used for the positive electrode, and a material capable of inserting and extracting lithium ions is used for the negative electrode. Activated carbon is preferred as the positive electrode material. Moreover, as a negative electrode material, a carbonaceous material is preferable.
- a non-aqueous electrolyte solution a non-aqueous electrolyte solution containing the compound represented by (1) is used.
- Electric double layer capacitor A material capable of forming an electric double layer is used for the positive electrode and the negative electrode. Activated carbon is preferable as the positive electrode material and the negative electrode material.
- a non-aqueous electrolyte solution a non-aqueous electrolyte solution containing the compound represented by (1) is used.
- Natural graphite powder as negative electrode active material aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry.
- This slurry was uniformly applied to one side of a 10 ⁇ m thick copper foil, dried, and then pressed to obtain a negative electrode.
- EC ethylene carbonate
- DMC dimethyl carbonate
- EMC ethyl methyl carbonate
- the basic electrolyte solution 2 was dissolved at a rate of 0.1 mol / L.
- EC ethylene carbonate
- EMC ethyl methyl carbonate
- EP ethyl propionate
- EC ethylene carbonate
- EMC ethyl methyl carbonate
- MA methyl acetate
- the basic electrolyte solution 5 was dissolved at a rate of 1.0 mol / L.
- nonaqueous electrolyte solution of each example was prepared by blending the basic electrolyte solution with the compound represented by the formula (1) described in each table in the described amount.
- a non-aqueous electrolyte solution of a comparative example was prepared by blending the basic electrolyte solution as it is or by adding a described amount of a compound considered appropriate as a comparative example other than the compound represented by the formula (1).
- a battery was prepared using a total of six types of electrolytes including these and the basic electrolyte. After evaluating the initial characteristics of the battery, a high temperature storage endurance test was performed, and an evaluation after the high temperature storage endurance test was performed. The results are summarized in Table 1 as Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after initial storage and storage were relative values with the value of Comparative Example 1-1 at that time as 100. Further, the remaining / recovered capacity after storage was a relative value with the initial value of Comparative Example 1-1 as 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Table 1 shows the following. While Examples 1-1 and 1-2 were not inferior to Comparative Example 1-1, it was found that the initial impedance was greatly reduced. At this point, Comparative Example 1-2 is inferior in initial efficiency, and the effect of suppressing impedance is not seen.
- Comparative Example 1-3 showed the same tendency as Examples 1-1 and 1-2, while Comparative Example 1-4 using a diester having a similar structure had a weak effect of suppressing impedance.
- Examples 1-1 and 1-2 were improved in both residual and recovery capacities relative to Comparative Example 1-1. In addition, it was confirmed that Examples 1-1 and 1-2 continued to maintain a low impedance value as compared with Comparative Example 1-1.
- Comparative Example 1-3 shows the same tendency as the Examples 1-1 and 1-2 with respect to the remaining / recovered capacity after storage, and the impedance is low although it does not reach that of Examples 1-1 and 1-2. The value is shown.
- Comparative Example 1-4 shows the same tendency as the Examples 1-1 and 1-2 in the remaining / recovered capacity after storage, but the impedance suppressing effect is not large. Since the remaining / recovered capacity after storage is maintained, the deterioration of the battery itself was suppressed, and as a result, it was considered that the impedance did not deteriorate as much as Comparative Example 1-1. It is thought that it is not the result of evaluating the amount of material having a suppressing effect.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after the initial, 200th cycle, and 400th cycle were relative values with the value of Comparative Example 2-1 at that time as 100.
- the capacity after 200 cycles and after 400 cycles was a relative value with the value of initial Comparative Example 2-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Table 2 shows the following. The tendency of initial evaluation was the same tendency as ⁇ Evaluation 1>.
- Comparative Example 2-2 had a lower capacity and an increased impedance, and that it would rather have an adverse effect when added.
- Comparative Example 2-3 the impedance after 200 cycles and after 400 cycles shows a low value that is not as good as that of Examples 2-1 and 2-2, similar to Comparative Example 1-3 after the high temperature storage durability test. It was. However, the results showed that the capacity after 200 cycles and after 400 cycles was almost the same as that of Comparative Example 2-1 using the basic electrolyte.
- ⁇ Evaluation 3> Compounds 3 and 4 were dissolved in 0.03 mol (about 0.5% by mass and about 0.7% by mass, respectively) per 1 kg of the basic electrolyte solution to obtain electrolyte solutions 3 and 4, respectively.
- Comparative Example 3-1 a basic electrolyte was used. Separately, another battery having the same configuration as in ⁇ Evaluation 1> and ⁇ Evaluation 2> was created. After evaluating the initial characteristics of these batteries, a high-temperature cycle endurance test was performed, and an evaluation after the high-temperature cycle endurance test was performed. These were Examples 3-1 and 3-2 and Comparative Example 3-1, respectively, and the results are summarized in Table 3.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after the initial 200 cycles were relative values with the value of Comparative Example 3-1 at that time as 100.
- the capacity after 200 cycles was a relative value with the value of the initial comparative example 3-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Examples 3-1 and 3-2 showed that the initial charge / discharge efficiency and the initial capacity were not inferior to those of Comparative Example 3-1, but the initial impedance was greatly reduced.
- the initial charge / discharge efficiency, initial capacity, and impedance after initial, 100 cycles, and 200 cycles were relative values with the value of Comparative Example 4-1 at that time as 100. Further, the capacity after 100 cycles and after 200 cycles was a relative value with the initial value of Comparative Example 4-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Examples 4-1 to 4-3 are not inferior to Comparative Example 3-1 in initial charge and discharge efficiency and initial capacity. In Examples 4-1 and 4-2, the initial impedance is greatly reduced. Example 4-3 was not significantly different, but this is considered to be a result of a strong influence of a resistance component having a time constant on the higher frequency side.
- a battery was prepared using a total of four types of electrolytes including these and the basic electrolyte 2. After evaluating the initial characteristics of the battery, a high-temperature cycle endurance test was performed, and an evaluation after the high-temperature cycle endurance test was performed. These were designated as Examples 5-1 and 5-2 and Comparative Examples 5-1 and 5-2, respectively, and the results are summarized in Table 5.
- the initial capacity and the impedance after the initial 100 cycles were relative values with the value of Comparative Example 5-1 at that time as 100. Further, the capacity after 100 cycles was a relative value with the initial value of Comparative Example 5-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- the electrolyte solution 9 was prepared by blending 0.6% by mass of the compound 1 with respect to the basic electrolyte solution. Furthermore, 1.0% by mass of vinylene carbonate (VC) and monofluoroethylene carbonate (FEC) was blended with respect to the electrolyte solution 9 to obtain electrolyte solutions 10 and 11, respectively. Moreover, 0.8 mass% of compound 2 was mix
- VC vinylene carbonate
- FEC monofluoroethylene carbonate
- a battery was prepared using a total of nine types of electrolytes including these and the basic electrolyte. After evaluating the initial characteristics of the battery, a high-temperature cycle endurance test was performed, and an evaluation after the high-temperature cycle endurance test was performed. Each of these was designated as Examples 6-1 to 6-6 and Comparative Examples 6-1 to 6-3, and the results are summarized in Table 6.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after the initial 200 cycles were relative values with the value of Comparative Example 6-1 at that time as 100. Further, the capacity after 200 cycles was a relative value with the initial value of Comparative Example 6-1 as 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- the electrolytic solution 2 and the electrolytic solution 12 have the same composition, the relative values of the characteristics after the initial characteristic evaluation and the high-temperature cycle durability test are different from those of ⁇ Evaluation 2> because of the error between lots of the produced batteries. .
- Example 6-1 in which only Compound 1 was added to the basic electrolyte, initial characteristics and improved characteristics after the high-temperature cycle endurance test were observed compared to Comparative Example 6-1, but examples in which VC and FEC were further added.
- Example 6-2 and 6-3 the post-cycle capacity was further improved while suppressing an increase in impedance at the 200th cycle.
- Example 6-4 in which only Compound 2 was added to the basic electrolyte, the effect of improving the characteristics with respect to Comparative Example 6-1 was confirmed, but Example 6-5 in which VC and FEC were further added, In 6-6, the post-cycle capacity was further improved while suppressing an increase in impedance at the 200th cycle.
- Comparative Examples 6-2 and 6-3 in which only VC and FEC were added to the basic electrolyte, the post-cycle capacity could be improved more than or equal to Comparative Example 6-1, but compounds 1, 2 and VC, Examples 6-2, 6-3, 6-5, and 6-6 using FEC together do not reach the capacity after cycle, and the effect of suppressing the increase in impedance after cycle is also inferior to each example.
- the decomposition of the non-aqueous electrolyte is more effectively suppressed than in the case where each of Compounds 1, 2, VC, and FEC is used alone. It was suggested that the electrochemical side reaction on the electrode of the decomposition product was suppressed. In addition, since the state of low impedance is maintained, the compound represented by the formula (1) is also taken into the film formed from VC or FEC and adsorbed on the electrode, thereby stabilizing the electrode surface. It is considered to be maintained.
- a battery was prepared using a total of four types of electrolyte solutions, these and the basic electrolyte solution 3. After evaluating the initial characteristics of the battery, a high-temperature cycle endurance test was performed, and an evaluation after the high-temperature cycle endurance test was performed. These were designated as Examples 7-1 and 7-2 and Comparative Examples 7-1 and 7-2, respectively, and the results are summarized in Table 7.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after the initial 200 cycles were relative values with the value of Comparative Example 7-1 at that time as 100.
- the capacity after 200 cycles was a relative value with the initial value of Comparative Example 7-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Example 7-1 and 7-2 the initial charge / discharge efficiency was greatly improved as compared with Comparative Example 7-1.
- Comparative Example 7-2 the effect of improving the initial charge / discharge efficiency was not confirmed. Further, in Examples 7-1 and 7-2, the initial impedance was greatly reduced, but in Comparative Example 7-2, the effect was small.
- the decomposition of the non-aqueous electrolyte solution can be achieved by adding the compound represented by the formula (1) to the basic electrolyte solution 3 in which a part of the chain carbonate is substituted with the chain carboxylate ester. It was suggested that the electrochemical side reaction on the electrode of the decomposition product was suppressed. Furthermore, since the state of low impedance is maintained, the stabilization mechanism of the compound represented by the formula (1) that is initially adsorbed is maintained even in the case of an electrolyte composition containing a chain carboxylic acid ester. it is conceivable that.
- a battery was prepared using a total of three electrolytes, these and the basic electrolyte 4. After evaluating the initial characteristics of the battery, a high-temperature cycle endurance test was performed, and an evaluation after the high-temperature cycle endurance test was performed. These were designated as Examples 8-1 and 8-2 and Comparative Example 8-1, respectively, and the results are summarized in Table 8.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after the initial 100 cycles were relative values with the value of Comparative Example 8-1 at that time as 100. Further, the capacity after 100 cycles was a relative value with the initial value of Comparative Example 8-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Example 8-1 The initial charge / discharge efficiency of Example 8-1 was greatly improved compared to Comparative Example 8-1.
- Example 8-2 in which VC was blended, the initial charge / discharge efficiency was further improved.
- the initial impedance was greatly reduced.
- Example 8-1 The capacity after 100 cycles of Example 8-1 was significantly improved compared to Comparative Example 8-1, but the capacity after cycle was further improved in Example 8-2 to which VC was further added.
- the impedance of Examples 8-1 and 8-2 at the time after 100 cycles was lower than that of Comparative Example 8-1, and it was confirmed that the increase in resistance was continuously suppressed even after 100 cycles.
- the stabilization mechanism by the initial adsorption of the compound represented by the formula (1) is maintained, which is an electrolytic solution containing a chain carboxylic acid ester and a VC coating It is considered that the adsorption stabilization mechanism of the compound represented by the formula (1) is maintained even in the presence of.
- a battery was prepared using a total of two types of electrolytes, that is, the basic electrolyte 5. After evaluating the initial characteristics of the battery, a high-temperature cycle endurance test was performed, and an evaluation after the high-temperature cycle endurance test was performed. Each of these was designated as Example 9-1 and Comparative Example 9-1, and the results are summarized in Table 9.
- the initial charge / discharge efficiency, the initial capacity, and the impedance after the initial and 100 cycles were each relative values with the value of Comparative Example 9-1 being 100. Further, the capacity after 100 cycles was a relative value with the initial value of Comparative Example 9-1 being 100. Only the impedance is evaluated to be superior as the relative value is small, and the others are evaluated as excellent as the relative value is large.
- Example 9-1 The initial charge / discharge efficiency and the initial capacity of Example 9-1 were improved as compared with Comparative Example 9-1. It was also confirmed that Example 9-1 greatly reduced the initial impedance. The capacity of Example 9-1 after 100 cycles was improved compared to Comparative Example 9-1, the impedance after 100 cycles was lower than that of Comparative Example 9-1, and the increase in resistance was suppressed even after 100 cycles. It was confirmed that it continued. From the above results, the decomposition of the non-aqueous electrolyte is suppressed by adding the compound represented by the formula (1) to the basic electrolyte 5 using LiFSI as the main salt, and the electrode of the decomposition product It was suggested that the electrochemical side reaction was suppressed. Furthermore, since the state of low impedance is maintained, even if the electrolyte composition uses LiFSI as the main salt, the stabilization mechanism of the compound represented by the formula (1) adsorbed initially is maintained. it is conceivable that.
- the non-aqueous electrolyte solution of the present invention is useful because it can improve the cycle capacity maintenance rate of the electricity storage device containing the non-aqueous electrolyte solution and the input / output characteristics after the cycle. Therefore, the non-aqueous electrolyte solution and the electricity storage device of the present invention can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, etc.
- Walkie Talkie Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Backup Power Supply, Motor, Automobile, Motorcycle, Motorbike, Bicycle, Lighting Equipment, Toy, Game Equipment, Clock, Electric Tool, Strobe, Camera, Home Backup power source, office backup power source, load leveling power source, natural energy storage power source and the like.
Abstract
Description
X1及びX2はそれぞれ独立して、C、S又はPを表す。
n1、n2はそれぞれ独立して、X1 、X2がC又はPのときは1であり、Sのときは2である。
n1はX1がC又はPのときは1であり、Sのときは2である。
n2はX2がC又はPのときは1であり、Sのときは2である。
Y1及びY2はそれぞれ独立して、置換基を有してもよい炭化水素基又は-OW基(Wは置換基を有してもよい炭化水素を表す。)を表す。
m1はX1がC又はSのときは1、Pのときは2であり、m2はX2がC又はSのときは1、Pのときは2である。
Zは、置換基を有してもよい炭化水素基、-SiV3基(Vは置換基を有してもよい炭化水素基を表す。)、有機オニウム、金属を表す。)
Wが水素原子の一部がハロゲン原子で置換されていてもよい炭素数1~6のアルキル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルケニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルキニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数6~12のアリール基及び水素原子の一部がハロゲン原子で置換されていてもよい炭素数7~13のアリールアルキル基からなる群より選ばれる-OW基である、[1]又は[2]に記載の非水系電解液。
Vが水素原子の一部がハロゲン原子で置換されていてもよい炭素数1~6のアルキル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルケニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルキニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数6~12のアリール基及び水素原子の一部がハロゲン原子で置換されていてもよい炭素数7~13のアリールアルキル基からなる群より選ばれる-SiV3基、水素若しくはアルカリ金属であるものを含む、[1]~[3]のいずれか1つに記載の非水系電解液。
本発明の非水系電界液は、電解質、非水溶媒及び以下の式(1)で表される化合物を含有する。
本発明の非水系電解液は、式(1)で表される化合物を含有する。なお、式(1)で表される化合物においては光学異性体の区別はつけないものとし、異性体単独又はこれらの混合として適用することもできる。
Y1及びY2、並びにWにおいて、置換基を有してもよい炭化水素基としては、好ましくは、置換基を有してもよい炭素数1~6のアルキル基であり、より好ましくは置換基を有してもよい炭素数1~4のアルキル基であり;
好ましくは置換基を有してもよい炭素数2~6のアルケニル基であり、より好ましくは置換基を有してもよい炭素数2~4のアルケニル基であり;
好ましくは置換基を有してもよい炭素数2~6のアルキニル基であり、より好ましくは置換基を有してもよい炭素数及び炭素数2~4のアルキニル基であり;
好ましくは置換基を有してもよい炭素数6~12のアリール基であり、より好ましくは置換基を有してもよい炭素数6~10のアリール基であり;
好ましくは置換基を有してもよい炭素数7~13のアリールアルキル基であり、より好ましくは置換基を有してもよい炭素数7~11のアリール基である。
効果に寄与する化学構造に対する分子量や分子そのものの大きさが大きくなり過ぎると十分な効果を発現できなくなるおそれがある。
非特許文献1:Zeitschrift fuer Anorganische und Allgemeine Chemie (1985), 530, 16
(非特許文献1に記載の化合物においてナトリウムを他のアルカリ金属に変えて実施することが可能である。)
非特許文献2:Heteroatom Chemistry (2012), 23, (4), 352
本発明の態様は、上記式(1)で表される化合物とともに、フッ素含有環状カーボネート、硫黄含有有機化合物、リン含有有機化合物、シアノ基を有する有機化合物、イソシアネート基を有する有機化合物、ケイ素含有化合物、芳香族化合物、炭素-炭素不飽和結合を有する環状カーボネート、フッ素非含有カルボン酸エステル、複数のエーテル結合を有する環状化合物及びイソシアヌル酸骨格を有する化合物、モノフルオロリン酸塩、ジフルオロリン酸塩、ホウ酸塩、シュウ酸塩及びフルオロスルホン酸塩からなる群より選ばれる少なくとも1種の化合物((II)群の化合物)を含むことができる。これらを併用することで、式(1)で表される化合物が引き起こし得る正負極上での副反応を効率よく抑制できるためである。
フッ素含有環状カーボネートとしては、炭素数2以上6以下のアルキレン基を有する環状カーボネートのフッ素化物、及びその誘導体が挙げられ、例えばエチレンカーボネートのフッ素化物(以下、「フッ素化エチレンカーボネート」と記載する場合がある)、及びその誘導体が挙げられる。エチレンカーボネートのフッ素化物の誘導体としては、アルキル基(例えば、炭素数1以上4以下のアルキル基)で置換されたエチレンカーボネートのフッ素化物が挙げられる。これらの中でもフッ素数1以上8以下のフッ素化エチレンカーボネート、及びその誘導体が好ましい。
これらの中でも、モノフルオロエチレンカーボネート、4,4-ジフルオロエチレンカーボネート、4,5-ジフルオロエチレンカーボネートが、電解液に高イオン伝導性を与え、かつ安定な界面保護被膜を容易に形成しやすい点で好ましい。
本発明の電解液は、更に硫黄含有有機化合物を含むことができる。硫黄含有有機化合物は、分子内に硫黄原子を少なくとも1つ有している有機化合物であれば、特に制限されないが、好ましくは分子内にS=O基を有している有機化合物であり、鎖状スルホン酸エステル、環状スルホン酸エステル、鎖状硫酸エステル、環状硫酸エステル、鎖状亜硫酸エステル及び環状亜硫酸エステルが挙げられる。ただしフルオロスルホン酸塩に該当するものは、1-2-2.硫黄含有有機化合物ではなく、後述する電解質であるフルオロスルホン酸塩に包含されるものとする。 本発明の電解液において、式(1)で表される化合物と硫黄含有有機化合物とを併用することによって、この電解液を用いた電池において、耐久特性を改善することができる。
鎖状スルホン酸エステルとしては、フルオロスルホン酸メチル及びフルオロスルホン酸エチル等のフルオロスルホン酸エステル;メタンスルホン酸メチル、メタンスルホン酸エチル、メタンスルホン酸2-プロピニル、メタンスルホン酸3-ブチニル、2-(メタンスルホニルオキシ)プロピオン酸メチル、2-(メタンスルホニルオキシ)プロピオン酸エチル、2-(メタンスルホニルオキシ)プロピオン酸2-プロピニル等のメタンスルホン酸エステル;ビニルスルホン酸メチル、ビニルスルホン酸エチル、ビニルスルホン酸アリル、ビニルスルホン酸プロパルギル、アリルスルホン酸メチル、アリルスルホン酸エチル、アリルスルホン酸アリル、アリルスルホン酸プロパルギル等のアルケニルスルホン酸エステル;メタンジスルホン酸1-メトキシカルボニルエチル、メタンジスルホン酸1-エトキシカルボニルエチル1,2-エタンジスルホン酸1-メトキシカルボニルエチル、1,2-エタンジスルホン酸1-エトキシカルボニルエチル、1,3-プロパンジスルホン酸1-メトキシカルボニルエチル、1,3-プロパンジスルホン酸1-エトキシカルボニルエチル1,4-ブタンジスルホン酸1-メトキシカルボニルエチル、1,4-ブタンジスルホン酸1-エトキシカルボニルエチル等のアルキルジスルホン酸エステル等が挙げられる。
環状スルホン酸エステルとしては、1,3-プロパンスルトン、1-フルオロ-1,3-プロパンスルトン、2-フルオロ-1,3-プロパンスルトン、3-フルオロ-1,3-プロパンスルトン、1-プロペン-1,3-スルトン、1-フルオロ-1-プロペン-1,3-スルトン、2-フルオロ-1-プロペン-1,3-スルトン、3-フルオロ-1-プロペン-1,3-スルトン、1-メチル-1-プロペン-1,3-スルトン、2-メチル-1-プロペン-1,3-スルトン、3-メチル-1-プロペン-1,3-スルトン、1,4-ブタンスルトン及び1,5-ペンタンスルトン等のスルトン化合物;メチレンメタンジスルホネート、エチレンメタンジスルホネート等のジスルホネート化合物等が挙げられる。
鎖状硫酸エステルとしては、ジメチルスルフェート、エチルメチルスルフェート及びジエチルスルフェート等のジアルキルスルフェート化合物等が挙げられる。
環状硫酸エステルとしては、1,2-エチレンスルフェート、1,2-プロピレンスルフェート、1,3-プロピレンスルフェート等のアルキレンスルフェート化合物が挙げられる。
鎖状亜硫酸エステルとしては、ジメチルスルファイト、エチルメチルスルファイト及びジエチルスルファイト等のジアルキルスルファイト化合物が挙げられる。
環状亜硫酸エステルとしては、1,2-エチレンスルファイト、1,2-プロピレンスルファイト、1,3-プロピレンスルファイト等のアルキレンスルファイト化合物が挙げられる。
硫黄含有有機化合物は、1種を単独で用いてもよく、2種以上を任意の組み合わせ及び比率で併有してもよい。
本発明の電解液は、更にリン含有有機化合物(ただし、ここでいうリン含有有機化合物には式(1)で表される化合物を除く意味で用いるものとする。)を含むことができる。リン含有有機化合物は、分子内に少なくとも一つリン原子を有している有機化合物であれば、特に制限されない。リン含有有機化合物を含有する本発明の電解液を用いた電池は、耐久特性を改善することができる。
リン含有有機化合物としては、リン酸エステル、ホスホン酸エステル、ホスフィン酸エステル、亜リン酸エステルが好ましく、より好ましくはリン酸エステル及びホスホン酸エステルであり、更に好ましくはホスホン酸エステルである。
本発明の電解液において、リン含有有機化合物を式(1)で表される化合物と併用することによって、この電解液を用いた電池において、耐久特性を改善することができる。
リン酸エステルとしては、ジメチルビニルホスフェート、ジエチルビニルホスフェート、メチルジビニルホスフェート、エチルジビニルホスフェート及びトリビニルホスフェート等のビニル基を有する化合物;アリルジメチルホスフェート、アリルジエチルホスフェート、ジアリルメチルホスフェート、ジアリルエチルホスフェート及びトリアリルホスフェート等のアリル基を有する化合物;プロパルギルジメチルホスフェート、プロパルギルジエチルホスフェート、ジプロパルギルメチルホスフェート、ジプロパルギルエチルホスフェート及びトリプロパルギルホスフェート等のプロパルギル基を有する化合物;2-アクリロイルオキシメチルジメチルホスフェート、2-アクリロイルオキシメチルジエチルホスフェート、ビス(2-アクリロイルオキシメチル)メチルホスフェート、ビス(2-アクリロイルオキシメチル)エチルホスフェート及びトリス(2-アクリロイルオキシメチル)ホスフェート等の2-アクリロイルオキシメチル基を有する化合物;2-アクリロイルオキシエチルジメチルホスフェート、2-アクリロイルオキシエチルジエチルホスフェート、ビス(2-アクリロイルオキシエチル)メチルホスフェート、ビス(2-アクリロイルオキシエチル)エチルホスフェート及びトリス(2-アクリロイルオキシエチル)ホスフェート等の2-アクリロイルオキシエチル基を有する化合物等が挙げられる。
ホスホン酸エステルとしては、トリメチル ホスホノフォルメート、メチル ジエチルホスホノフォルメート、トリエチル ホスホノフォルメート、エチル ジメチルホスホノフォルメート、メチル ビス(2,2,2-トリフルオロエチル)ホスホノフォルメート、エチル ビス(2,2,2-トリフルオロエチル)ホスホノフォルメート、トリメチル ホスホノアセテート、メチル ジエチルホスホノアセテート、トリエチル ホスホノアセテート、エチル ジメチルホスホノアセテート、メチル ビス(2,2,2-トリフルオロエチル)ホスホノアセテート、エチル ビス(2,2,2-トリフルオロエチル)ホスホノアセテート、アリル ジメチルホスホノアセテート、アリル ジエチルホスホノアセテート、2-プロピニル ジメチルホスホノアセテート、2-プロピニル ジエチルホスホノアセテート、トリメチル 3-ホスホノプロピオネート、メチル 3-(ジエチルホスホノ)プロピオネート等が挙げられる。
本発明の電解液は、シアノ基を有する有機化合物を含むことができる。シアノ基を有する有機化合物としては、分子内にシアノ基を少なくとも1つ有している有機化合物であれば、特に制限されないが、好ましくは式(2-4-1)、式(2-4-2)で表される化合物であり、より好ましくは式(2-4-2)で表される化合物である。なお、シアノ基を有する有機化合物が、複数のエーテル結合を有する環状化合物でもある場合、複数のエーテル結合を有する環状化合物に属してもよいものとする。
A1-CN (2-4-1)
(式中、A1は炭素数2以上20以下の炭化水素基を示す。)
NC-A2-CN (2-4-2)
(式中、A2は、水素原子、炭素原子、窒素原子、酸素原子、硫黄原子、リン原子及びハロゲン原子からなる群より選ばれる1種以上の原子で構成された炭素数1以上10以下の有機基である。)
本発明の電解液は、イソシアネート基を有する有機化合物を含むことができる。イソシアネート基を有する有機化合物は、分子内に少なくとも1つのイソシアネート基を有する有機化合物であれば、特に制限されないが、イソシアネート基の数は、一分子中、好ましくは1以上4以下、より好ましくは2以上3以下、更に好ましくは2である。
メチルイソシアネート、エチルイソシアネート、プロピルイソシアネート、イソプロピルイソシアネート、ブチルイソシアネート等のイソシアネート基を1個有する有機化合物;モノメチレンジイソシアネート、ジメチレンジイソシアネート、トリメチレンジイソシアネート、テトラメチレンジイソシアネート、ペンタメチレンジイソシアネート、ヘキサメチレンジイソシアネート、ヘプタメチレンジイソシアネート、オクタメチレンジイソシアネート、ノナメチレンジイソシアネート、デカメチレンジイソシアネート、ドデカメチレンジイソシアネート、1,2-ビス(イソシアナトメチル)シクロヘキサン、1,3-ビス(イソシアナトメチル)シクロヘキサン、1,4-ビス(イソシアナトメチル)シクロヘキサン、ジシクロヘキシルメタン-2,2’-ジイソシアネート、ジシクロヘキシルメタン-3,3’-ジイソシアネート、ジシクロヘキシルメタン-4,4’-ジイソシアネート、ビシクロ[2.2.1]ヘプタン-2,5-ジイルビス(メチルイソシアネート)、ビシクロ[2.2.1]ヘプタン-2,6-ジイルビス(メチルイソシアネート)、ジイソシアン酸イソホロン、カルボニルジイソシアネート、1,4-ジイソシアナトブタン-1,4-ジオン、1,5-ジイソシアナトペンタン-1,5-ジオン、2,2,4-トリメチルヘキサメチレンジイソシアナート、2,4,4-トリメチルヘキサメチレンジイソシアナート等のイソシアネート基を2個有する有機化合物等が挙げられる。
本発明の電解液は、ケイ素含有化合物を含むことができる。ケイ素含有化合物は、分子内に少なくとも1つのケイ素原子を有する化合物であれば、特に制限されない。本発明の電解液において、式(1)で表される化合物とケイ素含有化合物を併用することによって、耐久特性を改善することができる。
ホウ酸トリス(トリメチルシリル)、ホウ酸トリス(トリメトキシシリル)、ホウ酸トリス(トリエチルシリル)、ホウ酸トリス(トリエトキシシリル)、ホウ酸トリス(ジメチルビニルシリル)及びホウ酸トリス(ジエチルビニルシリル)等のホウ酸化合物; リン酸トリス(トリメチルシリル)、リン酸トリス(トリエチルシリル)、リン酸トリス(トリプロピルシリル)、リン酸トリス(トリフェニルシリル)、リン酸トリス(トリメトキシシリル)、リン酸トリス(トリエトキシシリル)、リン酸トリス(トリフエノキシシリル)、リン酸トリス(ジメチルビニルシリル)及びリン酸トリス(ジエチルビニルシリル)等のリン酸化合物;亜リン酸トリス(トリメチルシリル)、亜リン酸トリス(トリエチルシリル)、亜リン酸トリス(トリプロピルシリル)、亜リン酸トリス(トリフェニルシリル)、亜リン酸トリス(トリメトキシシリル)、亜リン酸トリス(トリエトキシシリル)、亜リン酸トリス(トリフエノキシシリル)、亜リン酸トリス(ジメチルビニルシリル)及び亜リン酸トリス(ジエチルビニルシリル)等の亜リン酸化合物;メタンスルホン酸トリメチルシリル、テトラフルオロメタンスルホン酸トリメチルシリル等のスルホン酸化合物;ヘキサメチルジシラン、ヘキサエチルジシラン、1,1,2,2-テトラメチルジシラン、1,1,2,2-テトラエチルジシラン、1,2-ジフェニルテトラメチルジシラン及び1,1,2,2-テトラフェニルジシラン等のジシラン化合物等が挙げられる。
なお、これらケイ素含有化合物は、1種を単独で用いてもよく、2種以上を任意の組み合わせ及び比率で併用してもよい。
本発明の電解液は、芳香族化合物を含むことができる。芳香族化合物としては、分子内に芳香環を少なくとも1つ有している有機化合物であれば、特に制限されないが、好ましくは式(2-7-1)及び式(2-7-2)で表される芳香族化合物である。
ハロゲン原子として、塩素、フッ素等が挙げられ、好ましくはフッ素である。
ヘテロ原子を有さない有機基として、炭素数3以上12以下の直鎖状、分岐状、環状の飽和炭化水素基が挙げられ、直鎖状、分岐状のものは環構造を持つものも含まれる。炭素数1以上12以下の直鎖状、分岐状、環状の飽和炭化水素基として具体的には、メチル基、エチル基、プロピル基、イソプロピル基、シクロペンチル基、シクロヘキシル基等が挙げられる。炭素数は好ましくは3以上12以下、より好ましくは3以上10以下、更に好ましくは3以上8以下、更により好ましくは3以上6以下、最も好ましくは3以上5以下である。
X71がハロゲン原子又はハロゲン原子を有していてもよい有機基であるものとして、クロロベンゼン、フルオロベンゼン、ジフルオロベンゼン、トリフルオロベンゼン、テトラフルオロベンゼン、ペンタフルオロベンゼン、ヘキサフルオロベンゼン、ベンゾトリフルオライド等が挙げられ、好ましくはフルオロベンゼン、ヘキサフルオロベンゼンである。より好ましくはフルオロベンゼンが挙げられる。
(A)R11~R15のうち少なくとも1つは、ハロゲン又は非置換もしくはハロゲン置換の炭素数1以上20以下の炭化水素基である、
(B)R11~R17の炭素数の合計は、3以上20以下である、のうち少なくとも一方の条件を満たす)
で表される芳香族化合物である。R11~R17のうち少なくとも2つが一緒になって環を形成している場合、R11~R17のうち2つが一緒になって環を形成していることが好ましい。
(A)R11~R15のうち少なくとも1つは、ハロゲン又は非置換もしくはハロゲン置換の炭素数1以上20以下の炭化水素基である、
(B)R11~R17の炭素数の合計は、3以上20以下である、
のうち少なくとも一方の条件を満たす。
R16及びR17が、独立して、炭素数1以上20以下の炭化水素基であり(ただし、R16及びR17の合計は炭素数3以上20以下である)、R11~R15が水素である化合物((B)を満たす)。
炭素-炭素不飽和結合を有する環状カーボネート(以下、「不飽和環状カーボネート」と記載する場合がある)としては、炭素-炭素二重結合又は炭素-炭素三重結合を有する環状カーボネートであれば、特に制限はなく、任意の不飽和カーボネートを用いることができるが、好ましくは炭素-炭素二重結合を有する環状カーボネートである。なお、芳香環を有する環状カーボネートも、不飽和環状カーボネートに包含されることとする。
本発明の電解液は、フッ素非含有カルボン酸エステルを含むことができる。本発明の電解液において、式(1)で表される化合物とフッ素非含有カルボン酸エステルを併用することにより、耐久特性を改善することができる。フッ素非含有カルボン酸エステルは、分子内にフッ素原子を有さないカルボン酸エステルであれば、特に制限されないが、好ましくはフッ素非含有の鎖状カルボン酸エステルであり、より好ましくはフッ素非含有の飽和鎖状カルボン酸エステルである。フッ素非含有の鎖状カルボン酸エステルの総炭素数は、好ましくは3以上、より好ましくは4以上、更に好ましくは5以上であり、好ましくは7以下、より好ましくは6以下、更に好ましくは5以下である。
複数のエーテル結合を有する環状化合物としては、分子内に複数のエーテル結合を有する環状化合物であれば、特に限定されないが、好ましくは式(2-10)で表される化合物である。複数のエーテル結合を有する環状化合物は、電池の高温保存特性の向上に寄与するものであり、本発明の電解液においては、式(1)で表される化合物と併用することによって、この電解液を用いた電池において、耐久特性を改善することができる。
本発明の電解液は、更にイソシアヌル酸骨格を有する化合物を含むことができる。イソシアヌル酸骨格を有する化合物は、分子内に少なくとも一つイソシアヌル酸骨格を有している有機化合物であれば、特に制限されない。イソシアヌル酸骨格を有する化合物を含有する本発明の電解液を用いた電池は、耐久特性を改善することができる。
本発明の電解液は、更にモノフルオロリン酸塩、ジフルオロリン酸塩を含むことができる。モノフルオロリン酸塩及びジフルオロリン酸塩は、それぞれ、分子内に少なくとも1つのモノフルオロリン酸又はジフルオロリン酸構造を有する塩であれば、特に制限されない。本発明の電解液において、上記式(1)で表される化合物とモノフルオロリン酸塩及びジフルオロリン酸塩から選ばれる1種以上とを併用することにより、この電解液を用いた電池において、耐久特性を改善することができる。
モノフルオロリン酸塩及びジフルオロリン酸塩から選ばれる1種以上の量(2種以上の場合は合計量)は、0.001質量%以上であることができ、好ましくは0.01質量%以上、より好ましくは0.1質量%以上、更に好ましくは0.2質量%以上、特に好ましくは0.3質量%以上であり、また、5質量%以下であることができ、好ましくは3質量%以下、より好ましくは2質量%以下、更に好ましくは1.5質量%以下、特に好ましくは1質量%以下である。この範囲内であると、初期不可逆容量向上の効果が顕著に発現される。
本発明の電解液は、更にホウ酸塩を含むことができる。ホウ酸塩は、分子内にホウ素原子を少なくとも1つ有している塩であれば、特に制限されない。ただしシュウ酸塩に該当するものは、「1-2-13.ホウ酸塩」ではなく、後述する「1-2-14.シュウ酸塩」に包含されるものとする。本発明の電解液において、式(1)で表される化合物とホウ酸塩とを併用することによって、この電解液を用いた電池において、耐久特性を改善することができる。
ホウ酸塩の量(2種以上の場合は合計量)は、0.05質量%以上であることができ、好ましくは0.1質量%以上、より好ましくは0.2質量%以上、更に好ましくは0.3質量%以上、特に好ましくは0.4質量%以上であり、また、10.0質量%以下であることができ、好ましくは5.0質量%以下、より好ましくは3.0質量%以下、更に好ましくは2.0質量%以下、特に好ましくは1.0質量%以下である。この範囲内であると、電池負極の副反応が抑制され抵抗を上昇させにくい。
本発明の電解液は、更にシュウ酸塩を含むことができる。シュウ酸塩は、分子内に少なくとも1つのシュウ酸構造を有する化合物であれば、特に制限されない。本発明の電解液において、式(1)で表される化合物とシュウ酸塩とを併用することによって、この電解液を用いた電池において、耐久特性を改善することができる。
シュウ酸塩としては、式(2-14-1)で表される金属塩が好ましい。この塩は、オキサラト錯体をアニオンとする塩である。
M1は、本発明の電解液をリチウム二次電池に用いたときの電池特性の点から、リチウム、ナトリウム、カリウム、マグネシウム、カルシウムが好ましく、リチウムが特に好ましい。
R91としては、フッ素、塩素、メチル基、トリフルオロメチル基、エチル基、ペンタフルオロエチル基、プロピル基、イソプロピル基、ブチル基、sec-ブチル基、tert-ブチル基等が挙げられ、フッ素、トリフルオロメチル基が好ましい。
本発明の電解液は、更に硫酸誘導体塩を含むことができる。
硫酸誘導体塩としては、分子内に少なくとも1つの硫酸誘導体塩構造を有している塩であれば、特に制限されないが、電解液中での安定性・溶解性が確保されていることが好ましい。
効果を有する構造に対する分子量、分子の大きさが大きくなりすぎると十分な効果を発現できなくなる場合がある。
さらに、これら置換基はハロゲン原子であることが好ましく、フッ素原子であることが最も好ましい。ハロゲン原子、とりわけフッ素原子での置換は、不要な反応性の低さから無置換と同等の特性を発現することが想定される。
本発明の電解液において、上記式(1)で表される化合物と硫酸誘導体塩とを併用することにより、この電解液を用いた電池において、耐久特性を改善することができる。
硫酸モノエステル塩としては、メチル硫酸リチウム、エチル硫酸リチウム、2-プロペニル硫酸リチウム、2,2,2-トリフルオロエチル硫酸リチウムが好ましく、スルファミン酸塩としては、N,N-ジメチルスルファミン酸リチウムが好ましい。
硫酸誘導体塩の含有量(2種以上の場合は合計量)は、0.05質量%以上であることができ、好ましくは0.1質量%以上、より好ましくは0.2質量%以上、更に好ましくは0.3質量%以上、特に好ましくは0.4質量%以上であり、また、10質量%以下であることができ、好ましくは8質量%以下、より好ましくは5質量%以下、更に好ましくは2質量%以下、特に好ましくは1質量%以下である。この範囲内であると、電池中での副反応が少なく、抵抗を上昇させにくい。
電解質は特に制限なく、電解質として公知のものを任意に用いることができる。
また、「1-2-12.モノフルオロリン酸塩、ジフルオロリン酸塩」、「1-2-13.ホウ酸塩」、「1-2-14.シュウ酸塩」、「1-2-15.フルオロスルホン酸塩」で説明した塩類も適用できる。
リチウムテトラフルオロオキサラトホスフェート、リチウムジフルオロビス(オキサラト)ホスフェート、リチウムトリス(オキサラト)ホスフェート等のリチウムオキサラトホスフェート塩類;等が挙げられる。
本発明における非水溶媒について特に制限はなく、公知の有機溶媒を用いることが可能である。具体的には、フッ素原子を有していない環状カーボネート、鎖状カーボネート、環状カルボン酸エステル及び「1-2-9.フッ素非含有カルボン酸エステル」において前述した鎖状カルボン酸エステル、エーテル系化合物、スルホン系化合物等が挙げられる。
フッ素原子を有していない環状カーボネートとしては、炭素数2~4のアルキレン基を有する環状カーボネートが挙げられる。
鎖状カーボネートとしては、炭素数3~7の鎖状カーボネートが好ましく、炭素数3~7のジアルキルカーボネートがより好ましい。
環状カルボン酸エステルとしては、炭素数が3~12のものが好ましい。具体的には、ガンマブチロラクトン、ガンマバレロラクトン、ガンマカプロラクトン、イプシロンカプロラクトン等が挙げられる。これらの中でも、ガンマブチロラクトンがリチウムイオン解離度の向上に由来する電池特性向上の点から特に好ましい。
エーテル系化合物としては、一部の水素がフッ素にて置換されていてもよい炭素数3~10の鎖状エーテル、及び炭素数3~6の環状エーテルが好ましい。
スルホン系化合物としては、炭素数3~6の環状スルホン、及び炭素数2~6の鎖状スルホンが好ましい。1分子中のスルホニル基の数は、1又は2であることが好ましい。
本発明の非水溶媒として、上記例示した非水溶媒1種を単独で用いてもよく、2種以上を任意の組み合わせ及び比率で併用してもよい。
本発明の非水系電解液を用いた蓄電デバイスは、リチウムイオンを吸蔵・放出可能な負極及び正極、並びに電解質及び非水溶媒を含む非水系電解液を具備し、該非水系電解液が電解質及び非水溶媒とともに、前述の式(1)で表される化合物を含有する。
本発明の非水系電解液を用いたリチウム電池は、集電体及び該集電体上に設けられた正極活物質層を有する正極と、集電体及び該集電体上に設けられた負極活物質層を有しかつイオンを吸蔵及び放出し得る負極と、上述した本発明の非水系電解液とを備えるものである。尚、本発明におけるリチウム電池とは、リチウム一次電池とリチウム二次電池の総称である。
本発明のリチウム電池は、上述した本発明の非水系電解液以外の構成については、従来公知のリチウム電池と同様である。通常は、本発明の非水系電解液が含浸されている多孔膜(セパレータ)を介して正極と負極とが積層され、これらがケース(外装体)に収納された形態を有する。従って、本発明のリチウム電池の形状は特に制限されるものではなく、円筒型、角形、ラミネート型、コイン型、大型等の何れであってもよい。
非水系電解液としては、上述の本発明の非水系電解液を用いる。なお、本発明の趣旨を逸脱しない範囲において、本発明の非水系電解液に対し、その他の非水系電解液を配合して用いることも可能である。
負極は、集電体上に負極活物質層を有するものであり、負極活物質層は負極活物質を含有する。以下、負極活物質について述べる。
リチウム一次電池に用いられる負極活物質としては、電気化学的にリチウムイオンを放出可能なものであれば特に制限はない。その具体例としては金属リチウムが挙げられる。
リチウム二次電池に用いられる負極活物質としては、電気化学的に金属イオン(例えば、リチウムイオン)を吸蔵・放出可能なものであれば、特に制限はない。具体例としては、炭素質材料、合金系材料、リチウム含有金属複合酸化物材料等が挙げられる。これらは1種を単独で用いてもよく、また2種以上を任意に組み合わせて併用してもよい。
負極活物質としては、炭素質材料、合金系材料、リチウム含有金属複合酸化物材料等が挙げられる。
(1)天然黒鉛、
(2)人造炭素質物質及び人造黒鉛質物質を400~3200℃の範囲で1回以上熱処理した炭素質材料、
(3)負極活物質層が少なくとも2種以上の異なる結晶性を有する炭素質からなり、かつ/又はその異なる結晶性の炭素質が接する界面を有している炭素質材料、
(4)負極活物質層が少なくとも2種以上の異なる配向性を有する炭素質からなり、かつ/又はその異なる配向性の炭素質が接する界面を有している炭素質材料、
から選ばれるものが、初期不可逆容量、高電流密度充放電特性のバランスがよく好ましい。また、(1)~(4)の炭素質材料は、1種を単独で用いてもよく、2種以上を任意の組み合わせ及び比率で併用してもよい。
[式(A)中、Mは、Na、K、Co、Al、Fe、Ti、Mg、Cr、Ga、Cu、Zn及びNbからなる群より選ばれる少なくとも1種の元素を表わす。]
(a)1.2≦x≦1.4、1.5≦y≦1.7、z=0
(b)0.9≦x≦1.1、1.9≦y≦2.1、z=0
(c)0.7≦x≦0.9、2.1≦y≦2.3、z=0
電極の製造は、本発明の効果を著しく損なわない限り、公知のいずれの方法を用いることができる。例えば、負極活物質に、バインダー、溶媒、必要に応じて、増粘剤、導電材、充填材等を加えてスラリーとし、これを集電体に塗布、乾燥した後にプレスすることによって形成することができる。
負極活物質を保持させる集電体としては、公知のものを任意に用いることができる。負極の集電体としては、アルミニウム、銅、ニッケル、ステンレス鋼、ニッケルメッキ鋼等の金属材料が挙げられるが、加工し易さとコストの点から特に銅が好ましい。
負極活物質を結着するバインダーとしては、非水系電解液や電極製造時に用いる溶媒に対して安定な材料であれば、特に制限されない。
増粘剤は、通常、スラリーの粘度を調製するために使用される。増粘剤としては、特に制限されないが、具体的には、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、カゼイン及びこれらの塩等が挙げられる。これらは、1種を単独で用いても、2種以上を任意の組み合わせ及び比率で併用してもよい。
負極活物質を電極化した際の電極構造は特に制限されないが、集電体上に存在している負極活物質の密度は、1g・cm-3以上が好ましく、1.2g・cm-3以上が更に好ましく、1.3g・cm-3以上が特に好ましく、また、2.2g・cm-3以下が好ましく、2.1g・cm-3以下がより好ましく、2.0g・cm-3以下が更に好ましく、1.9g・cm-3以下が特に好ましい。集電体上に存在している負極活物質の密度が、上記範囲であると、負極活物質粒子の破壊を防止して、初期不可逆容量の増加や、集電体/負極活物質界面付近への非水系電解液の浸透性低下による高電流密度充放電特性悪化を抑制することができる一方、電池容量の低下や抵抗の増大を抑制することができる。
負極板の厚さは用いられる正極板に合わせて設計されるものであり、特に制限されないが、芯材の金属箔厚さを差し引いた合材層の厚さは通常15μm以上、好ましくは20μm以上、より好ましくは30μm以上、また、通常300μm以下、好ましくは280μm以下、より好ましくは250μm以下が望ましい。
また、上記負極板の表面に、これとは異なる組成の物質が付着したものを用いてもよい。表面付着物質としては酸化アルミニウム、酸化ケイ素、酸化チタン、酸化ジルコニウム、酸化マグネシウム、酸化カルシウム、酸化ホウ素、酸化アンチモン、酸化ビスマス等の酸化物、硫酸リチウム、硫酸ナトリウム、硫酸カリウム、硫酸マグネシウム、硫酸カルシウム、硫酸アルミニウム等の硫酸塩、炭酸リチウム、炭酸カルシウム、炭酸マグネシウム等の炭酸塩等が挙げられる。
<正極活物質>
以下に正極に使用される正極活物質について述べる。
リチウム一次電池に用いられる負極活物質としては、電気化学的にリチウムイオンを吸蔵可能なものであれば特に制限はない。その具体例としてはフッ化黒鉛、二酸化マンガン、塩化チオニル、二硫化鉄、酸化銅が挙げられる。
ト複合酸化物、これらのリチウム遷移金属複合酸化物の主体となる遷移金属原子の一部をNa、K、B、F、Al、Ti、V、Cr、Mn、Fe、Co、Li、Ni、Cu、Zn、Mg、Ga、Zr、Si、Nb、Mo、Sn、W等の他の元素で置換したもの等が挙げられる。置換されたものとしては、LiNi0.5Mn0.5O2、LiNi0.85Co0.10Al0.05O2、LiNi0.33Co0.33Mn0.33O2、LiNi0.45Co0.10Al0.45O2、LiMn1.8Al0.2O4、LiMn1.5Ni0.5O4等が挙げられる。
また、上記正極活物質の表面に、これとは異なる組成の物質が付着したものを用いてもよい。表面付着物質としては酸化アルミニウム、酸化ケイ素、酸化チタン、酸化ジルコニウム、酸化マグネシウム、酸化カルシウム、酸化ホウ素、酸化アンチモン、酸化ビスマス等の酸化物、硫酸リチウム、硫酸ナトリウム、硫酸カリウム、硫酸マグネシウム、硫酸カルシウム、硫酸アルミニウム等の硫酸塩、炭酸リチウム、炭酸カルシウム、炭酸マグネシウム等の炭酸塩、炭素等が挙げられる。
正極活物質の粒子の形状は、従来用いられるような、塊状、多面体状、球状、楕円球状、板状、針状、柱状等が挙げられる。また、一次粒子が凝集して、二次粒子を形成していてもよい。
正極活物質のタップ密度は、好ましくは0.5g/cm3以上、より好ましくは0.8g/cm3以上、更に好ましくは1.0g/cm3以上である。該正極活物質のタップ密度が上記範囲であると、正極活物質層形成時に必要な分散媒量及び導電材や結着剤の必要量を抑えることができ、結果正極活物質の充填率及び電池容量を確保することができる。タップ密度の高い複合酸化物粉体を用いることにより、高密度の正極活物質層を形成することができる。タップ密度は一般に大きいほど好ましく、特に上限はないが、好ましくは4.0g/cm3以下、より好ましくは3.7g/cm3以下、更に好ましくは3.5g/cm3以下である。上記範囲であると負荷特性の低下を抑制することができる。
正極活物質の製造法としては、無機化合物の製造法として一般的な方法が用いられる。特に球状ないし楕円球状の活物質を作製するには種々の方法が考えられるが、例えば、遷移金属の原料物質を水等の溶媒中に溶解ないし粉砕分散して、攪拌をしながらpHを調節して球状の前駆体を作製回収し、これを必要に応じて乾燥した後、LiOH、Li2CO3、LiNO3等のLi源を加えて高温で焼成して活物質を得る方法等が挙げられる。
以下に、正極の構成について述べる。本発明において、正極は、正極活物質と結着剤とを含有する正極活物質層を、集電体上に形成して作製することができる。正極活物質を用いる正極の製造は、常法により行うことができる。即ち、正極活物質と結着剤、ならびに必要に応じて導電材及び増粘剤等を乾式で混合してシート状にしたものを正極集電体に圧着するか、又はこれらの材料を液体媒体に溶解又は分散させてスラリーとして、これを正極集電体に塗布し、乾燥することにより、正極活物質層を集電体上に形成されることにより正極を得ることができる。
導電材としては、公知の導電材を任意に用いることができる。具体例としては、銅、ニッケル等の金属材料;天然黒鉛、人造黒鉛等の黒鉛(グラファイト);アセチレンブラック等のカーボンブラック;ニードルコークス等の無定形炭素等の炭素材料等が挙げられる。なお、これらは、1種を単独で用いてもよく、2種以上を任意の組み合わせ及び比率で併用してもよい。導電材は、正極活物質層中に、通常0.01質量%以上、好ましくは0.1質量%以上、より好ましくは1質量%以上であり、また上限は、通常50質量%以下、好ましくは30質量%以下、より好ましくは15質量%以下含有するように用いられる。上記範囲であると、十分な導電性と電池容量を確保することができる。
正極活物質層の製造に用いる結着剤としては、特に限定されず、塗布法の場合は、電極製造時に用いる液体媒体に対して溶解又は分散される材料であればよいが、具体例としては、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系高分子;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状高分子;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状高分子;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状高分子;ポリフッ化ビニリデン(PVdF)、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、ポリテトラフルオロエチレン・エチレン共重合体等のフッ素系高分子;アルカリ金属イオン(特にリチウムイオン)のイオン伝導性を有する高分子組成物等が挙げられる。なお、これらの物質は、1種を単独で用いてもよく、2種以上を任意の組み合わせ及び比率で併用してもよい。
正極集電体の材質としては特に制限されず、公知のものを任意に用いることができる。具体例としては、アルミニウム、ステンレス鋼、ニッケルメッキ、チタン、タンタル等の金属材料;カーボンクロス、カーボンペーパー等の炭素材料が挙げられる。これらの中でも金属材料、特にアルミニウムが好ましい。
本発明の電解液を用いる場合、高出力かつ高温時の安定性を高める観点から、正極活物質層の面積は、電池外装ケースの外表面積に対して大きくすることが好ましい。具体的には、二次電池の外装の表面積に対する正極の電極面積の総和が面積比で15倍以上とすることが好ましく、更に40倍以上とすることがより好ましい。外装ケースの外表面積とは、有底角型形状の場合には、端子の突起部分を除いた発電要素が充填されたケース部分の縦と横と厚さの寸法から計算で求める総面積をいう。有底円筒形状の場合には、端子の突起部分を除いた発電要素が充填されたケース部分を円筒として近似する幾何表面積である。正極の電極面積の総和とは、負極活物質を含む合材層に対向する正極合材層の幾何表面積であり、集電体箔を介して両面に正極合材層を形成してなる構造では、それぞれの面を別々に算出する面積の総和をいう。
正極板の厚さは特に限定されないが、高容量かつ高出力の観点から、芯材の金属箔厚さを差し引いた合材層の厚さは、集電体の片面に対して下限として、好ましくは10μm以上、より好ましくは20μm以上で、上限としては、好ましくは500μm以下、より好ましくは450μm以下である。
また、上記正極板の表面に、これとは異なる組成の物質が付着したものを用いてもよい。表面付着物質としては酸化アルミニウム、酸化ケイ素、酸化チタン、酸化ジルコニウム、酸化マグネシウム、酸化カルシウム、酸化ホウ素、酸化アンチモン、酸化ビスマス等の酸化物、硫酸リチウム、硫酸ナトリウム、硫酸カリウム、硫酸マグネシウム、硫酸カルシウム、硫酸アルミニウム等の硫酸塩、炭酸リチウム、炭酸カルシウム、炭酸マグネシウム等の炭酸塩、炭素等が挙げられる。
正極と負極との間には、短絡を防止するために、通常はセパレータを介在させる。この場合、本発明の電解液は、通常はこのセパレータに含浸させて用いる。
<電極群>
電極群は、上記の正極板と負極板とを上記のセパレータを介してなる積層構造のもの、及び上記の正極板と負極板とを上記のセパレータを介して渦巻き状に捲回した構造のもののいずれでもよい。電極群の質量が電池内容積に占める割合(以下、電極群占有率と称する)は、通常40%以上であり、50%以上が好ましく、また、通常90%以下であり、80%以下が好ましい。電極群占有率が、上記範囲であると、電池容量を確保できるとともに内部圧力の上昇に伴う充放電繰り返し性能や高温保存等の特性低下を抑制し、更にはガス放出弁の作動を防止することができる。
集電構造は、特に制限されないが、配線部分や接合部分の抵抗を低減する構造にすることが好ましい。電極群が上記の積層構造のものでは、各電極層の金属芯部分を束ねて端子に溶接して形成される構造が好適に用いられる。一枚の電極面積が大きくなる場合には、内部抵抗が大きくなるので、電極内に複数の端子を設けて抵抗を低減することも好適に用いられる。電極群が上記の捲回構造のものでは、正極及び負極にそれぞれ複数のリード構造を設け、端子に束ねることにより、内部抵抗を低くすることができる。
外装ケースの材質は用いられる非水系電解液に対して安定な物質であれば特に制限されない。具体的には、ニッケルめっき鋼板、ステンレス、アルミニウム又はアルミニウム合金、マグネシウム合金等の金属類、又は、樹脂とアルミ箔との積層フィルム(ラミネートフィルム)が用いられる。軽量化の観点から、アルミニウム又はアルミニウム合金の金属、ラミネートフィルムが好適に用いられる。
保護素子として、異常発熱や過大電流が流れた時に抵抗が増大するPTC(PositiveTemperature Coefficient)、温度ヒューズ、サーミスター、異常発熱時に電池内部圧力や内部温度の急激な上昇により回路に流れる電流を遮断する弁(電流遮断弁)等を使用することができる。上記保護素子は高電流の通常使用で作動しない条件のものを選択することが好ましく、保護素子がなくても異常発熱や熱暴走に至らない設計にすることがより好ましい。
正極に酸化物材料等を用い、負極にマグネシウム、カルシウム、アルミニウム等の金属や、これらの金属を含む化合物等を用いる。電解質には、負極の反応活物質種と同じ元素、すなわちマグネシウムイオンやカルシウムイオン、アルミニウムイオンを与えるように、マグネシウム塩やカルシウム塩、アルミニウム塩等を非水溶媒に溶解させた非水系電解液を用い、そこに式(1)で表される化合物を溶解させることにより、多価カチオン電池用非水系電解液を調製することができる。
負極に亜鉛、リチウム、ナトリウム、マグネシウム、アルミニウム、カルシウムなどの金属や、これらの金属を含む化合物等を用いる。正極活物質は酸素であるため、正極は多孔質のガス拡散電極を用いる。多孔質材料は炭素が好ましい。電解質には、負極活物質種と同じ元素、すなわちリチウム、ナトリウム、マグネシウム、アルミニウム、カルシウムなどを与えるように、リチウム塩やナトリウム塩、マグネシウム塩、アルミニウム塩、カルシウム塩等を非水溶媒に溶解させた非水系電解液を用い、そこに(1)で表される化合物を溶解させることにより、金属空気電池用非水系電解液を調製することができる。
s-ブロック元素とは、第1族元素(水素、アルカリ金属)、第2族元素(ベリリウム、マグネシウム及びアルカリ土類金属)及びヘリウムのことで、s-ブロック金属二次電池とは、前記s-ブロック金属を負極及び又は電解質に用いた二次電池をあらわす。上記以外のs-ブロック金属二次電池は、具体的には、正極に硫黄を用いたリチウム硫黄電池やナトリウム硫黄電池、またナトリウムイオン電池等が挙げられる、
正極に電気二重層を形成できる材料を用い、負極にリチウムイオンを吸蔵・放出可能な材料を用いる。正極材料としては活性炭が好ましい。また負極材料としては、炭素質材料が好ましい。非水系電解液には、(1)で表される化合物を含有した非水系電解液を用いる。
正極及び負極に電気二重層を形成できる材料を用いる。正極材料及び負極材料としては活性炭が好ましい。非水系電解液には、(1)で表される化合物を含有した非水系電解液を用いる。
以下具体的な評価手法について、説明する。
正極活物質としてニッケルマンガンコバルト酸リチウム(LiNi1/3Mn1/3Co1/3O2)85質量部を用い、カーボンブラック10質量部とポリフッ化ビニリデン5質量部を混合し、N-メチル-2-ピロリドンを加えスラリー化した。これを厚さ15μmのアルミニウム箔の両面に均一に塗布、乾燥した後、プレスして正極とした。
負極活物質として天然黒鉛粉末、増粘剤としてカルボキシメチルセルロースナトリウムの水性ディスパージョン(カルボキシメチルセルロースナトリウムの濃度1質量%)、結着材としてスチレンブタジエンゴムの水性ディスパージョン(スチレンブタジエンゴムの濃度50質量%)を加え、ディスパーザーで混合してスラリー化した。このスラリーを厚さ10μmの銅箔の片面に均一に塗布、乾燥した後、プレスして負極とした。なお、乾燥後の負極において、天然黒鉛:カルボキシメチルセルロースナトリウム:スチレンブタジエンゴム=98:1:1の質量比となるように作製した。
基本電解液:1.0M LiPF6/EC:DMC:EMC=3:3:4
乾燥アルゴン雰囲気下、エチレンカーボネート(EC)、ジメチルカーボネート(DMC)及びエチルメチルカーボネート(EMC)からなる混合溶媒(混合体積比EC:DMC:EMC=3:3:4)に、電解質であるLiPF6を1.0mol/Lの割合で溶解させ基本電解液とした。
乾燥アルゴン雰囲気下、エチレンカーボネート(EC)、ジエチルカーボネート(DEC)からなる混合溶媒(混合体積比EC:DEC=2:8)に、電解質であるLiPF6及びLiBF4をそれぞれ1.2mol/L、0.1mol/Lの割合で溶解させ基本電解液2とした。
乾燥アルゴン雰囲気下、エチレンカーボネート(EC)、エチルメチルカーボネート(EMC)及びプロピオン酸エチル(EP)からなる混合溶媒(混合体積比EC:EMC:EP=3:4:3)に、電解質であるLiPF6を1.0mol/Lの割合で溶解させ基本電解液3とした。
乾燥アルゴン雰囲気下、エチレンカーボネート(EC)、エチルメチルカーボネート(EMC)及び酢酸メチル(MA)からなる混合溶媒(混合体積比EC:EMC:MA=3:4:3)に、電解質であるLiPF6を1.0mol/Lの割合で溶解させ基本電解液4とした。
乾燥アルゴン雰囲気下、エチレンカーボネート(EC)、エチルメチルカーボネート(EMC)及び酢酸メチル(MA)からなる混合溶媒(混合体積比EC:EMC:MA=3:4:3)に、電解質であるLiFSIを1.0mol/Lの割合で溶解させ基本電解液5とした。
上記の正極、負極、及びポリプロピレン製のセパレータを、負極、セパレータ、正極、セパレータ、負極の順に積層して電池要素を作製した。この電池要素をアルミニウム(厚さ40μm)の両面を樹脂層で被覆したラミネートフィルムからなる袋内に正・負極の端子を突設させながら挿入した後、非水系電解液を袋内に注入し、真空封止を行ない、シート状のリチウム二次電池を作製した。
リチウム二次電池をガラス板で挟んで加圧した状態で、25℃において、1/6Cに相当する電流で4.2Vまで定電流充電した後引き続き電流が0.01Cまで絞り込まれるまで定電圧充電を行った(定電流-定電圧充電・CC-CV充電ともいう。)。
比較には0.5Hzにおける虚数成分の抵抗値を用いた。
初期特性評価後の電池を、25℃において、1/6Cに相当する電流で上限4.2V、0.01Cに絞り込まれるまで定電流―定電圧充電した後、60℃の恒温槽にて2週間保存を行った。
高温保存耐久試験後の電池を25℃に戻した。
1/6Cに相当する電流の定電流で2.5Vまで放電し、この容量を保存後放電容量とした。また、再度、25℃にて1/6Cに相当する電流で上限4.2V、0.01Cに絞り込まれるまで定電流-定電圧充電した後、1/6Cに相当する電流の定電流で2.5Vまで放電し、この容量を保存後の回復容量とした。
比較には0.5Hzにおける虚数成分の抵抗値を用いた。
初期特性評価後の電池を、60℃の恒温槽中にて、1Cに相当する電流で上限4.2V、0.01Cに絞り込まれるまで定電流-定電圧充電した後、1Cに相当する電流の定電流で2.5Vまで放電し、これを1サイクルとした。
高温耐久試験後の電池を25℃に戻した。
25℃にて、1/6Cに相当する電流の定電流で2.5Vまで放電し、再度、25℃にて1/6Cに相当する電流で上限4.2V、0.01Cに絞り込まれるまで定電流―定電圧充電した後、1/6Cに相当する電流の定電流で2.5Vまで放電し、この容量をサイクル後容量とした。
比較には0.5Hzにおける虚数成分の抵抗値を用いた。
実施例に使用した電解液に加えた化合物(式(1)に該当する化合物)、及び比較例に使用した電解液に加えた化合物(式(1)に該当しない化合物)の構造を以下に示す。式(1)で表される化合物は文献1を、比較例で用いられた化合物は前記特許文献1~5に記載されている化合物であり、それぞれの特許文献に記載の方法を用いて合成して用いた。
化合物1,2を基本電解液1kgあたり0.03mol(それぞれ約0.5質量%、0.8質量%)溶解し、それぞれ電解液1,2とした。また、比較化合物1~3を基本電解液1kgあたり0.03mol溶解し、それぞれ比較電解液1~3とした。
実施例1-1,1-2は比較例1-1に劣らない一方、初期インピーダンスは大きく低減されていることがわかった。この時点で、比較例1-2は初期効率に劣り、インピーダンスを抑制する効果は見られない。
評価1で用いた電解液を使用して、別途再度同様の構成の別の電池を作成した。電池の初期特性の評価を行った後、高温サイクル耐久試験を行い、高温サイクル耐久試験後評価を実施した。これらのそれぞれを実施例2-1,2-2及び比較例2-1~2-3とし、結果を表2にまとめた。
初期評価の傾向は、<評価1>と同様の傾向であった。
化合物3,4を基本電解液1kgあたり0.03mol(それぞれ約0.5質量%、約0.7質量%)溶解し、それぞれ電解液3,4とした。比較例3-1には基本電解液を用いた。別途再度<評価1>及び<評価2>と同様の構成の別の電池を作成した。これらの電池の初期特性評価した後、高温サイクル耐久試験を行い、高温サイクル耐久試験後評価を実施した。これらをそれぞれ実施例3-1,3-2及び比較例3-1とし、結果を表3にまとめた。
化合物1を基本電解液1kgあたりそれぞれ0.06,0.12mol(それぞれ約1.0質量%、2.0質量%)溶解し、それぞれ電解液5,6とした。これに加え電解液1を再度使用した。比較例4-1には基本電解液を用いた。
基本電解液2に対し、化合物1、2をそれぞれ0.6質量%、0.8質量%配合し、それぞれ電解液7,8とした。また、基本電解液2に対し、比較化合物1を0.45質量%配合し、比較電解液4とした。
基本電解液に対し、化合物1を0.6質量%配合し、電解液9とした。さらに、電解液9に対しビニレンカーボネート(VC)、モノフルオロエチレンカーボネート(FEC)をそれぞれ1.0質量%配合し、それぞれ電解液10、11とした。また、基本電解液に対し、化合物2を0.8質量%配合し、電解液12とした。さらに、電解液12に対しVC、FECをそれぞれ1.0質量%配合し、それぞれ電解液13、14とした。また、基本電解液に対し、VC、FECをそれぞれ1.0質量%配合し、それぞれ比較電解液5、6とした。
同様に、基本電解液に対し化合物2のみを加えた実施例6-4においても、比較例6-1に対する特性向上効果は確認されるが、さらにVC、FECを加えた実施例6-5、6-6では、200サイクル時点でインピーダンスの増加を抑制しつつ、サイクル後容量がさらに向上した。
基本電解液3に対し、化合物1、2をそれぞれ0.6質量%、0.8質量%配合し、それぞれ電解液15,16とした。また、基本電解液3に対し、比較化合物1を0.45質量%配合し、比較電解液7とした。
基本電解液4に対し、化合物1を0.6質量%配合し、電解液17とした。さらに、電解液17にVCを1.0質量%配合し、電解液18とした。
基本電解液5に対し、化合物1を0.6質量%配合し、電解液9-1とした。
初期充放電効率、初期容量、及び初期・100サイクル後のインピーダンスはそれぞれ、その時の比較例9-1の値を100とした相対値とした。また、100サイクル後の容量は、比較例9-1の初期の値を100とした相対値とした。インピーダンスのみ相対値が小さいほど優れたものと評価され、その他は大きいほど優れたものと評価される。
実施例9-1の100サイクル後の容量は、比較例9-1に対して向上し、100サイクル後時点のインピーダンスも比較例9-1に対して低く、100サイクル後も抵抗増加を抑制し続けていることが確認された。
以上の結果から、主塩にLiFSIを用いた基本電解液5に対しても、式(1)で表される化合物を添加することにより、非水系電解液の分解が抑制され、分解物の電極上での電気化学的副反応が抑制されていることが示唆された。さらに、インピーダンスが低い状態を維持することから、主塩にLiFSIを用いた電解液組成であっても、初期的に吸着した式(1)で表される化合物の安定化機構が維持されるものと考えられる。
Claims (11)
- 非水溶媒及び下記式(1)で表される化合物を含有する非水系電解液。
X1及びX2はそれぞれ独立して、C、S又はPを表す。
n1、n2はそれぞれ独立して、X1 、X2がCまたはPのときは1であり、Sのときは2である。
n1はX1がCまたはPのときは1であり、Sのときは2である。
n2はX2がCまたはPのときは1であり、Sのときは2である。
Y1及びY2はそれぞれ独立して、置換基を有してもよい炭化水素基又は-OW基(Wは置換基を有してもよい炭化水素を表す。)を表す。
m1はX1がCまたはSのときは1、Pのときは2であり、m2はX2がCまたはSのときは1、Pのときは2である。
Zは、置換基を有してもよい炭化水素基、-SiV3基(Vは置換基を有してもよい炭化水素基を表す。)、有機オニウム、金属を表す。) - 前記式(1)において、X1及びX2がCであり、n1及びn2が1であり、かつm1及びm2が1であるものを含む、請求項1に記載の非水系電解液。
- 前記式(1)において、Y1及びY2がそれぞれ独立して、水素原子の一部がハロゲン原子で置換されていてもよい炭素数1~6のアルキル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルケニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルキニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数6~12のアリール基及び水素原子の一部がハロゲン原子で置換されていてもよい炭素数7~13のアリールアルキル基からなる群より選ばれる基であるか、又は
Wが水素原子の一部がハロゲン原子で置換されていてもよい炭素数1~6のアルキル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルケニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルキニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数6~12のアリール基及び水素原子の一部がハロゲン原子で置換されていてもよい炭素数7~13のアリールアルキル基からなる群より選ばれる-OW基である、請求項1または2に記載の非水系電解液。 - 前記式(1)において、Zが水素原子の一部がハロゲン原子で置換されていてもよい炭素数1~6のアルキル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルケニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルキニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数6~12のアリール基及び水素原子の一部がハロゲン原子で置換されていてもよい炭素数7~13のアリールアルキル基、からなる群より選ばれる基であるか、又は
Vが水素原子の一部がハロゲン原子で置換されていてもよい炭素数1~6のアルキル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルケニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数2~6のアルキニル基、水素原子の一部がハロゲン原子で置換されていてもよい炭素数6~12のアリール基及び水素原子の一部がハロゲン原子で置換されていてもよい炭素数7~13のアリールアルキル基からなる群より選ばれる-SiV3基、水素若しくはアルカリ金属であるものを含む、請求項1~3のいずれか1項に記載の非水系電解液。 - 前記式(1)で表される化合物を、0.001質量%以上10質量%以下で含有する、請求項1~4のいずれか1項に記載の非水系電解液。
- 電解質を含有する、請求項1~5のいずれか1項に記載の非水系電解液。
- 前記非水系電解液が、更に、フッ素含有環状カーボネート、硫黄含有有機化合物、リン含有有機化合物、シアノ基を有する有機化合物、イソシアネート基を有する有機化合物、ケイ素含有化合物、芳香族化合物、炭素-炭素不飽和結合を有する環状カーボネート、フッ素非含有カルボン酸エステル、複数のエーテル結合を有する環状化合物、イソシアヌル酸骨格を有する化合物、モノフルオロリン酸塩、ジフルオロリン酸塩、ホウ酸塩、シュウ酸塩及びフルオロスルホン酸塩からなる群より選ばれる少なくとも1種の化合物を含有する、請求項1~6のいずれか1項に記載の非水系電解液。
- 前記フッ素含有環状カーボネート、硫黄含有有機化合物、リン含有有機化合物、シアノ基を有する有機化合物、イソシアネート基を有する有機化合物、ケイ素含有化合物、芳香族化合物、炭素-炭素不飽和結合を有する環状カーボネート、フッ素非含有カルボン酸エステル、複数のエーテル結合を有する環状化合物、イソシアヌル酸骨格を有する化合物、モノフルオロリン酸塩、ジフルオロリン酸塩、ホウ酸塩、シュウ酸塩及びフルオロスルホン酸塩からなる群より選ばれる少なくとも1種の化合物の非水系電解液全量に対する合計含有量が、0.001質量%以上50質量%以下である、請求項7に記載の非水系電解液。
- 非水系電解液二次電池用である請求項1~8のいずれか1項に記載の非水系電解液。
- リチウムイオンを吸蔵・放出可能な負極及び正極、並びに電解質及び非水溶媒を含む非水系電解液を具備する蓄電デバイスであって、該非水系電解液が請求項1~9のいずれか1項に記載の非水系電解液であることを特徴とする蓄電デバイス。
- 蓄電デバイスが非水系電解液二次電池である請求項10に記載の蓄電デバイス。
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JP7448723B2 (ja) | 2021-07-14 | 2024-03-12 | エルジー エナジー ソリューション リミテッド | リチウム二次電池用非水系電解液及びこれを含むリチウム二次電池 |
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