Secondary battery

Abstract

The purpose of the present invention is to improve the life of a battery using a negative electrode comprising a metal by reducing the amount of gas generation, reducing the resistance, and reducing the amount of metal elements such as Mn and Ni deposited in a positive electrode in the negative electrode. A secondary battery having a liquid electrolyte and a negative electrode in which a fluoropolymer is laminated on a layer containing a metal, the secondary battery being characterized in that: the metal is at least one type selected from the group consisting of lithium, sodium, magnesium and zinc; the fluoropolymer is a copolymer having a vinylidene fluoride unit (A) and a structural unit (B) of at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, a monomer represented by general formula (1), a monomer represented by general formula (2), and a monomer represented by general formula (3), and the liquid electrolyte contains a fluorinated ether. [chemical formula 1] # imgabs0 # [chemical formula 2] # imgabs1 # [chemical formula 3] # imgabs2 #

Description

Technical Field

[0001] The present disclosure relates to a secondary battery. Background Art

[0002] In recent years, in order to further improve the energy density of alkali metal secondary batteries represented by lithium secondary batteries, research and development of alkali metal secondary batteries using alkali metals having high theoretical capacity in negative electrodes has been conducted.

[0003] However, in the case of secondary batteries using alkali metals, repeated charge and discharge shortens the battery life. Furthermore, transition metals in the positive electrode active material dissolve and accumulate on the negative electrode, which also shortens the battery life.

[0004] Patent Document 1 discloses an electrode in which the surface of lithium metal is coated with a polyvinylidene fluoride polymer.

[0005] Patent Document 2 discloses a protective film-forming composition containing a vinylidene fluoride-hexafluoropropylene copolymer. It describes that a protective film is formed by applying such a protective film-forming composition on a lithium metal foil film layer.

[0006] Patent Document 3 discloses the use of an electrolyte solution containing a fluorinated ether compound in a battery using lithium metal as an electrode.

[0007] Patent Document 4 discloses coating an electrode with a resin.

[0008] Patent Document 5 discloses an electrode in which the surface of lithium metal is coated with a polyvinylidene fluoride polymer.

[0009] Patent Documents 6 and 7 disclose the production of electrodes using a binder composition containing a polyvinylidene fluoride polymer and an electrode active material.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: International Publication No. 2017 / 140649

[0013] Patent Document 2: Japanese Patent Application No. 2019-515481

[0014] Patent document 3: International Publication No. 2020 / 246579

[0015] Patent Document 4: International Publication No. 2014 / 132579

[0016] Patent document 5: International Publication No. 2021 / 123151

[0017] Patent Document 6: International Publication No. 2018 / 092676

[0018] Patent Document 7: International Publication No. 2021 / 015229 Summary of the invention

[0019] Problems to be solved by the invention

[0020] The present disclosure aims to improve the battery life by reducing the amount of gas generated, lowering the resistance, and reducing the amount of precipitation of metal elements in the positive electrode such as Mn and Ni in the negative electrode in a battery using a negative electrode made of metal.

[0021] Means for solving problems

[0022] The present disclosure relates to a secondary battery having a negative electrode in which a fluoropolymer is laminated on a layer containing a metal and having a liquid electrolyte, wherein:

[0023] The metal is at least one selected from lithium, sodium, magnesium and zinc,

[0024] The fluoropolymer is a copolymer having a vinylidene fluoride unit (A) and a structural unit (B) derived from at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, a monomer represented by the general formula (1), a monomer represented by the general formula (2) and a monomer represented by the general formula (3).

[0025] The liquid electrolyte contains a fluorinated ether.

[0026] [Chemistry 1]

[0027]

[0028] In the formula, Rf 1 It is a linear or branched fluoroalkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they may contain an oxygen atom (—O—) between carbon atoms.

[0029] [Chemistry 2]

[0030]

[0031] R 2 It is a linear or branched fluoroalkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they may contain an oxygen atom (—O—) between carbon atoms.

[0032] [Chemistry 3]

[0033]

[0034] In the formula, R 1 , R 2 and R 3 Each independently represents a hydrogen atom, a chlorine atom or an alkyl group having 1 to 5 carbon atoms. X represents an atomic group having a molecular weight of 500 or less and having a single bond or a main chain composed of 1 to 20 atoms. Y represents an inorganic cation and / or an organic cation.

[0035] The copolymer preferably has a vinylidene fluoride content of 30 mol% to 99.5 mol% based on all monomer units.

[0036] The fluorinated ether is preferably a compound represented by the following general formula (5).

[0037] [Chemistry 4]

[0038] HCF2CF2-OR (5)

[0039] (R is an alkyl group which may contain an ether group, or a fluorinated alkyl group which may contain an ether group.)

[0040] The compound represented by the general formula (5) is preferably at least one compound selected from the group consisting of compounds represented by the following general formula.

[0041] [Chemistry 5]

[0042] ·HCF2-CF2-O-CH2-CF2-CF2H

[0043] ·HCF2-CF2-O-CH2-CH2-CH3

[0044] ·HCF2-CF2-O-CH2-CH2-CH2-CH3

[0045] ·HCF2-CF2-O-CH2-CF3

[0046] ·HCF2-CF2-O-CH2-CH2-O-CF2-CF2H

[0047] The present disclosure also relates to a secondary battery having a negative electrode including a laminate in which a fluoropolymer is directly laminated on a current collector, wherein:

[0048] The fluoropolymer is a copolymer having a vinylidene fluoride unit (A) and a structural unit (B) derived from at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, a monomer represented by the general formula (1), a monomer represented by the general formula (2) and a monomer represented by the general formula (3).

[0049] The liquid electrolyte contains a fluorinated ether.

[0050] [Chemistry 6]

[0051]

[0052] In the formula, Rf 1 It is a linear or branched fluoroalkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they may contain an oxygen atom (—O—) between carbon atoms.

[0053] [Chemistry 7]

[0054]

[0055] R 2 It is a linear or branched fluoroalkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they may contain an oxygen atom (—O—) between carbon atoms.

[0056] [Chemistry 8]

[0057]

[0058] In the formula, R 1 , R 2 and R 3 Each independently represents a hydrogen atom, a chlorine atom or an alkyl group having 1 to 5 carbon atoms. X represents an atomic group having a molecular weight of 500 or less and having a single bond or a main chain composed of 1 to 20 atoms. Y represents an inorganic cation and / or an organic cation.

[0059] The copolymer preferably has a vinylidene fluoride content of 30 mol% to 99.5 mol% based on all monomer units.

[0060] The fluorinated ether is preferably a compound represented by the following general formula (5).

[0061] [Chemistry 9]

[0062] HCF2CF2-OR (5)

[0063] (R is an alkyl group which may contain an ether group, or a fluorinated alkyl group which may contain an ether group.)

[0064] The compound represented by the general formula (5) is preferably at least one compound selected from the group consisting of compounds represented by the following general formula.

[0065] [Chemistry 10]

[0066] ·HCF2-CF2-O-CH2-CF2-CF2H

[0067] ·HCF2-CF2-O-CH2-CH2-CH3

[0068] ·HCF2-CF2-O-CH2-CH2-CH2-CH3

[0069] ·HCF2-CF2-O-CH2-CF3

[0070] ·HCF2-CF2-O-CH2-CH2-O-CF2-CF2H

[0071] Effects of the Invention

[0072] The present disclosure can reduce the amount of transition metal elution or gas generation in the positive electrode active material, reduce resistance, and suppress positive electrode degradation due to reduced precipitation of metal elements in the positive electrode such as Mn and Ni in the negative electrode, thereby improving battery life. DETAILED DESCRIPTION

[0073] Hereinafter, the present disclosure will be described in detail.

[0074] The present invention has a negative electrode formed with a coating layer and uses a liquid electrolyte containing a fluorinated ether, wherein the coating layer is formed using a fluorinated polymer having a specific composition. By forming such a coating layer and then using a specific liquid electrolyte, the above-mentioned problem can be particularly appropriately improved compared to the secondary battery described in the above patent document.

[0075] The negative electrode used in the secondary battery of the present disclosure has a coating layer formed by a fluoropolymer as described in detail below. Here, the negative electrode can be a negative electrode with a coating formed by a fluoropolymer directly on a negative electrode material mainly composed of a metal such as lithium metal (the first embodiment), or a negative electrode with a coating layer formed by a fluoropolymer on a current collector (the second embodiment).

[0076] The electrode having a structure in which a coating layer made of a fluoropolymer is formed on a current collector as described in the second aspect can also obtain the above-mentioned effects.

[0077] In the second embodiment, a negative electrode having a coating layer made of a fluoropolymer and not provided with a layer of a negative electrode material made of a metal is directly formed on the current collector as the negative electrode. In this case, when such a negative electrode is stacked with other layers constituting the battery such as a positive electrode and then charged, a metal layer of lithium metal or the like is formed on the current collector by the electrode reaction during charging. Such a metal layer is formed between the current collector and the fluoropolymer layer. That is, by charging, a negative electrode having a coating made of a fluoropolymer directly formed on a layer made of a metal such as lithium metal is formed, which is the same as the negative electrode of the first embodiment.

[0078] Therefore, the effects of the present disclosure are appropriately exerted.

[0079] It is speculated that the particularly suitable effect obtained by using a fluorinated polymer containing the above-mentioned vinylidene fluoride unit (A) and structural unit (B) in the negative electrode of the secondary battery disclosed in the present invention is based on the following effect: through the interaction between the specific fluorinated polymer layer and lithium ions, uniform metal precipitation can be carried out and the generation of dendrites can be suppressed.

[0080] Cited Documents 6 and 7 disclose the use of the same polymer in the field of batteries.

[0081] They are significantly different from the present disclosure because they do not have a negative electrode with a fluoropolymer laminated on a metal layer.

[0082] Hereinafter, the polymer used in the present disclosure will be described in detail, and then the negative electrode and the battery will be described in detail.

[0083] In the present disclosure, the negative electrode is layered with a fluoropolymer described in detail below. By having such a coating, the above-mentioned effects can be obtained. In the following description, the fluoropolymer having tetrafluoroethylene, trifluoroethylene, and trifluorochloroethylene as the structural unit (B) is referred to as fluoropolymer 1.

[0084] Furthermore, a fluoropolymer comprising as a structural unit (B) the monomer represented by the general formula (1) or the monomer represented by the general formula (2) will be hereinafter referred to as fluoropolymer 2, and a fluoropolymer comprising as a structural unit (B) the monomer represented by the general formula (3) will be hereinafter referred to as fluoropolymer 3.

[0085] It should be noted that the following description does not exclude the use of two or more fluoropolymers corresponding to fluoropolymers 1, 2, and 3. That is, any two or more monomers selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, the monomer represented by general formula (1), the monomer represented by general formula (2), and the monomer represented by general formula (3) may be used in combination.

[0086] As described in detail below, the preferred range of the copolymerization ratio varies depending on the copolymerization components used, but as a whole, the content of vinylidene fluoride is preferably 30 mol% to 99.5 mol% based on the monomer unit.

[0087] (Fluoropolymer 1)

[0088] Fluoropolymer 1 has a structural unit based on at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene and chlorotrifluoroethylene.

[0089] The content of the VdF unit in the fluoropolymer 1 is preferably 57.0 mol% or more, more preferably 60.0 mol% or more, and further preferably 63.0 mol% or more, and preferably 95.0 mol% or less, further preferably 90.0 mol% or less, and most preferably 85.0 mol% or less, based on all monomer units.

[0090] The content of at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene and chlorotrifluoroethylene in the fluoropolymer 1 is preferably 5.0 mol% or more, more preferably 8.0 mol% or more, particularly preferably 10.0 mol% or more, and most preferably 15 mol% or more, and is preferably 43.0 mol% or less, more preferably 40.0 mol% or less, further preferably 38.0 mol% or less, and particularly preferably 37.0 mol% or less, based on all monomer units.

[0091] As the fluoropolymer 1, among them, preferably, a fluoropolymer 1 consisting only of VdF units, TFE units, and any non-fluorinated monomer units, wherein the molar ratio of VdF units to TFE units (VdF units / TFE units) is 57 / 43 to 90 / 10. That is, the fluoropolymer 1 is preferably a binary copolymer consisting only of VdF units and TFE units, or a ternary or higher copolymer consisting only of VdF units, TFE units, and non-fluorinated monomer units, and does not contain fluorinated monomer units other than VdF units and TFE units.

[0092] When the fluoropolymer 1 contains VdF units and TFE units, the molar ratio of VdF units to TFE units (VdF units / TFE units) is preferably 57 / 43 to 90 / 10, more preferably 60 / 40 to 89 / 11, further preferably 63 / 37 to 88 / 12, particularly preferably 63 / 37 to 85 / 15.

[0093] The weight average molecular weight (in terms of polystyrene) of the fluoropolymer 1 is preferably 161,000 to 2,760,000, more preferably 322,000 to 2,530,000, and still more preferably 600,000 to 2,000,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC) at 50° C. using dimethylformamide as a solvent.

[0094] The number average molecular weight (in terms of polystyrene) of the fluoropolymer 1 is preferably 70000 to 1200000, more preferably 140000 to 1100000. The number average molecular weight can be measured by gel permeation chromatography (GPC) at 50°C using dimethylformamide as a solvent.

[0095] The melting point of the fluoropolymer 1 is preferably 100° C. to 170° C., more preferably 110° C. to 165° C., and further preferably 120° C. to 163° C. The melting point is determined by using a differential scanning calorimetry (DSC) apparatus, raising the temperature from 30° C. to 220° C. at a rate of 10° C. / min, then lowering the temperature to 30° C. at a rate of 10° C. / min, and again raising the temperature to 220° C. at a rate of 10° C. / min, and determining the melting point as the temperature corresponding to the maximum value in the heat of fusion curve at this time.

[0096] (Fluoropolymer 2)

[0097] Fluoropolymer 2 is a fluoropolymer having at least one copolymerized unit selected from the group consisting of a monomer unit having a structure represented by the following general formula (1) and at least one monomer unit selected from the group consisting of a structure represented by the following general formula (2).

[0098] [Chemistry 11]

[0099]

[0100] In the formula, Rf 1 It is a linear or branched fluoroalkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they may contain an oxygen atom (—O—) between carbon atoms.

[0101] [Chemistry 12]

[0102]

[0103] R 2 It is a linear or branched fluoroalkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they may contain an oxygen atom (—O—) between carbon atoms.

[0104] A fluoropolymer comprising at least one copolymerized unit selected from the group consisting of a monomer unit having a structure represented by the above general formula (1) and a monomer unit having a structure represented by the above general formula (2) is excellent in that uniformity during coating can be easily obtained.

[0105] In the fluorinated monomer represented by the general formula (1), Rf 1 It is a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or a linear or branched fluorinated alkoxy group having 1 to 12 carbon atoms. Both the fluorinated alkyl group and the fluorinated alkoxy group may contain an oxygen atom (—O—) between carbon atoms when the number of carbon atoms is 2 or more.

[0106] R 1The fluorinated alkyl group may be a partially fluorinated alkyl group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or a perfluorinated alkyl group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 1 The hydrogen atom of the fluorinated alkyl group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom.

[0107] In addition, Rf 1 The fluorinated alkoxy group may be a partially fluorinated alkoxy group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or may be a perfluorinated alkoxy group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 1 The hydrogen atom of the fluorinated alkoxy group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom.

[0108] As Rf 1 The number of carbon atoms in the moiety is preferably 1 to 10, more preferably 1 to 6, further preferably 1 to 4, and particularly preferably 1.

[0109] As Rf 1 , preferably the general formula:

[0110] -(Rf 11 ) m -(O) p -(Rf 12 -O) n -Rf 13

[0111] (Where Rf 11 and Rf 12 Rf is independently a linear or branched fluorinated alkylene group having 1 to 4 carbon atoms, 13 is a linear or branched fluorinated alkyl group having 1 to 4 carbon atoms, p is 0 or 1, m is an integer of 0 to 4, and n is an integer of 0 to 4).

[0112] R 11 and Rf 12 The fluorinated alkylene group may be a partially fluorinated alkylene group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or a perfluorinated alkylene group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 11 and Rf 12 The hydrogen atom of the fluorinated alkylene group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom. 11 and Rf 12 It can be the same or different each time it occurs.

[0113] As Rf 11The fluorinated alkylene group includes -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, -CHF-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-, etc. Among them, the perfluorinated alkylene group having 1 or 2 carbon atoms is preferred, and -CF2- is more preferred.

[0114] As Rf 12 The fluorinated alkylene groups include -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, -C HF-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc., among which perfluorinated alkylene groups having 1 to 3 carbon atoms are preferred, and -CF2-, -CF2CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2- or CF2-CF(CF3)- are more preferred.

[0115] As Rf 13 The fluorinated alkyl group may be a partially fluorinated alkyl group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or a perfluorinated alkyl group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 13 The hydrogen atom of the fluorinated alkyl group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom (eg, -CN, -CH2I, -CH2Br, etc.).

[0116] As Rf 13The fluorinated alkyl group includes -CH2F, -CHF2, -CF3, -CH2-CH2F, -CH2-CHF2, -CH2-CF3, -CHF-CH2F, -CHF-CHF2, -CHF-CF3, -CF2-CH2F, -CF2-CHF2, -CF2-CF3, -CH2-CF2-CH2F, -CHF-CF2-CH2F, -CF2-CF2-CH2F, -CF(CF3)-CH2F, -CH2-CF2-CHF2, -CHF-CF2-CHF2, -CF2-CF2-CHF2, -CF(CF3)-CHF2, -CH2-CF2-CF3, -CHF-C F2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CH2-CF2-CF2-CF3, -CHF-CF2-CF2-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3, -CF(CF3)-CF2-CF3, -C(CF 3) 2-CF3, etc., among which -CF3, -CHF-CF3, -CF2-CHF2, -CF2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3 or CF(CF3)-CF2-CF3 are preferred.

[0117] As p, 0 is preferred.

[0118] m is preferably an integer of 0 to 2, more preferably 0 or 1, and further preferably 0. When p is 0, m is also preferably 0.

[0119] n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0120] As the repeating unit, preferably

[0121] -CH2-CF[-CF3]-,

[0122] -CH2-CF[-CF2CF3]-,

[0123] -CH2-CF[-CF2CF2CF3]-,

[0124] -CH2-CF[-CF2CF2CF2CF3]-,

[0125] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CHF-CF3]-,

[0126] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF2-CF3]-,

[0127] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF3]-,

[0128] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CH(CF3)-CF2-CF3]-,

[0129] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-CF3]-,

[0130] -CH2-CF[-OCF2OCF3]-,

[0131] -CH2-CF[-OCF2CF2CF22OCF3]-,

[0132] -CH2-CF[-CF2OCFOCF3]-,

[0133] -CH2-CF[-CF2OCF2CF2CF2OCF3]-or

[0134] -CH2-CF[-O-CF2-CF3]-,

[0135] More preferred is -CH2-CF[-CF3]-.

[0136] In the fluorinated monomer (2) represented by the above formula (2), Rf 2 It is a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or a linear or branched fluorinated alkoxy group having 1 to 12 carbon atoms. Both the fluorinated alkyl group and the fluorinated alkoxy group may contain an oxygen atom (—O—) between carbon atoms when the number of carbon atoms is 2 or more.

[0137] R 2 The fluorinated alkyl group may be a partially fluorinated alkyl group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or a perfluorinated alkyl group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 2 The hydrogen atom of the fluorinated alkyl group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom.

[0138] In addition, Rf 2 The fluorinated alkoxy group may be a partially fluorinated alkoxy group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or may be a perfluorinated alkoxy group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 2 The hydrogen atom of the fluorinated alkoxy group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom.

[0139] As Rf 2 The number of carbon atoms in the moiety is preferably 1 to 10, more preferably 1 to 6, further preferably 1 to 4, and particularly preferably 1.

[0140] As Rf 2 , preferably the general formula:

[0141] -(Rf 21 ) m -(O) p -(Rf 22 -O) n -Rf 23

[0142] (Where Rf 21 and Rf 22 Rf is independently a linear or branched fluorinated alkylene group having 1 to 4 carbon atoms, 23 is a linear or branched fluorinated alkyl group having 1 to 4 carbon atoms, p is 0 or 1, m is an integer of 0 to 4, and n is an integer of 0 to 4).

[0143] R 21 and Rf 22 The fluorinated alkylene group may be a partially fluorinated alkylene group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or a perfluorinated alkylene group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 21 and Rf 22 The hydrogen atom of the fluorinated alkylene group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom. 21 and Rf 22 It can be the same or different each time it occurs.

[0144] As Rf 21 The fluorinated alkylene group includes -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, -CHF-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-, etc. Among them, the perfluorinated alkylene group having 1 or 2 carbon atoms is preferred, and -CF2- is more preferred.

[0145] As Rf 22 The fluorinated alkylene groups include -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, -C HF-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc., among which perfluorinated alkylene groups having 1 to 3 carbon atoms are preferred, and -CF2-, -CF2CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2- or CF2-CF(CF3)- are more preferred.

[0146] As Rf 23 The fluorinated alkyl group may be a partially fluorinated alkyl group in which a part of the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms, or a perfluorinated alkyl group in which all the hydrogen atoms bonded to the carbon atoms are replaced by fluorine atoms. 23 The hydrogen atom of the fluorinated alkyl group may be substituted with a substituent other than a fluorine atom, but preferably contains no substituent other than a fluorine atom (eg, -CN, -CH2I, -CH2Br, etc.).

[0147] As Rf 23The fluorinated alkyl group includes -CH2F, -CHF2, -CF3, -CH2-CH2F, -CH2-CHF2, -CH2-CF3, -CHF-CH2F, -CHF-CHF2, -CHF-CF3, -CF2-CH2F, -CF2-CHF2, -CF2-CF3, -CH2-CF2-CH2F, -CHF-CF2-CH2F, -CF2-CF2-CH2F, -CF(CF3)-CH2F, -CH2-CF2-CHF2, -CHF-CF2-CHF2, -CF2-CF2-CHF2, -CF(CF3)-CHF2, -CH2-CF2-CF3, -CHF-C F2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CH2-CF2-CF2-CF3, -CHF-CF2-CF2-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3, -CF(CF3)-CF2-CF3, -C(CF 3) 2-CF3, etc., among which -CF3, -CHF-CF3, -CF2-CHF2, -CF2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3 or CF(CF3)-CF2-CF3 are preferred.

[0148] As p, 0 is preferred.

[0149] m is preferably an integer of 0 to 2, more preferably 0 or 1, and further preferably 0. When p is 0, m is also preferably 0.

[0150] n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0151] As the repeating unit, preferably

[0152] -CHF-CH[-CF3]-,

[0153] -CHF-CH[-CF2CF3]-,

[0154] -CHF-CH[-CF2CF2CF3]- or

[0155] -CHF-CH[-CF2CF2CF2CF3]-,

[0156] More preferred is -CHF-CH[-CF3]-.

[0157] The molar ratio of the vinylidene fluoride unit / copolymer unit in the fluoropolymer 2 is preferably 87 / 13 to 20 / 80, and more preferably 85 / 15 to 30 / 70 from the viewpoint of solubility.

[0158] The fluoropolymer 2 may have structural units other than the vinylidene fluoride unit and the copolymerization unit. In this case, the content of the other polymers is preferably 50 mol% or less. It should be noted that it may also be composed only of the vinylidene fluoride unit and the copolymerization unit. The content of the other polymers is more preferably 30 mol% or less, and further preferably 15 mol% or less.

[0159] The fluoropolymer 2 may use a monomer that provides a crosslinking site as the other monomer.

[0160] The monomer providing the crosslinking site is not particularly limited, and for example, the monomer of the general formula:

[0161] CX 12 =CX 1 -Rf 1 CHR 1 X 2

[0162] (Where X 1 is a hydrogen atom, a fluorine atom or CH3, Rf 1 is a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, R 1 is a hydrogen atom or CH3, X 2 is an iodine atom or a bromine atom), and the general formula is:

[0163] CF2=CFO(CF2CF(CF3)O) m (CF2) n -X 3

[0164] (wherein, m is an integer from 0 to 5, n is an integer from 1 to 3, and X 3 is a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, or a bromine atom), a monomer of the general formula:

[0165] CH2=CFCF2O(CF(CF3)CF2O) m (CF(CF3)) n -X 4

[0166] (wherein, m is an integer from 0 to 5, n is an integer from 1 to 3, and X 4 As other monomers, a monomer represented by a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2OH) is used.

[0167] Among them, preferred is at least one selected from the group consisting of CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF2COOH, CF2=CFOCF2CF2CH2I, CF2=CFOCF2CF(CF3)OCF2CF2CH2I, CH2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOH and CH2=CFCF2OCF(CF3)CF2OCF(CF3)CH2OH.

[0168] The fluoropolymer 2 is preferably a fluoroelastomer. A fluoroelastomer is an amorphous fluorine-based polymer having a low glass transition temperature. In addition, it may contain repeating units based on a monomer that provides a crosslinking site, but in one embodiment of the present disclosure, it does not contain a crosslinking agent.

[0169] The glass transition temperature of the fluorinated elastomer is preferably 25°C or less. The glass transition temperature is more preferably 0°C or less. The glass transition temperature is further preferably -5°C or less, and most preferably -10°C or less. Furthermore, it can also be -20°C or less. Here, regarding the glass transition temperature, a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC823e) is used. After cooling to -75°C, 10 mg of the sample is heated at 20°C / min to obtain a DSC curve, and the temperature of the intersection of the extended line of the baseline before and after the secondary transition of the DSC curve and the tangent line at the inflection point of the DSC curve is taken as the glass transition temperature.

[0170] The fluorinated elastomer is preferably amorphous. Amorphous means that there is no melting point peak in the DSC curve.

[0171] Such a low Tg, amorphous fluorinated elastomer is particularly preferred in that it is easily dissolved in a solvent, imparts flexibility to an electrode, and imparts easy processability.

[0172] The fluorine-containing elastomer is a copolymer composed of vinylidene fluoride units, the copolymer units, and other monomers copolymerizable therewith as required, preferably with a molar ratio of vinylidene fluoride units / copolymer units of 99.5 / 0.5 to 80 / 20, and other monomer units accounting for 0 to 15 mol% of all monomer units.

[0173] The fluorine-containing elastomer is preferably a copolymer consisting only of vinylidene fluoride, copolymerization units, and other monomers.

[0174] The fluoropolymer 2 used in the present disclosure preferably has 0.001 mol% to 10 mol% (wherein the total of the structural unit derived from vinylidene fluoride and the copolymerized unit is 100 mol%) of the structural unit derived from the copolymerized unit, more preferably 0.01 mol% to 5 mol%, and particularly preferably 0.01 mol% to 3.0 mol%. In addition, it is preferred to have 90 mol% to 99.999 mol% of the structural unit derived from vinylidene fluoride, more preferably 95 mol% to 99.75 mol%, and particularly preferably 96 mol% to 99.63 mol%. When the copolymerized unit is 0.01 mol% or more, the viscosity of the polymer solvent does not become too high, and it is possible to prevent the coating of the polymer solvent from becoming difficult.

[0175] The weight average molecular weight (in terms of polystyrene) of the fluoropolymer 2 is preferably 161,000 to 2,760,000, more preferably 322,000 to 2,530,000, and even more preferably 600,000 to 2,000,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC) at 50° C. using dimethylformamide as a solvent.

[0176] The number average molecular weight (in terms of polystyrene) of the fluoropolymer 2 is preferably 70,000 to 1,200,000, more preferably 140,000 to 1,100,000. The number average molecular weight can be measured by gel permeation chromatography (GPC) at 50°C using dimethylformamide as a solvent.

[0177] The glass transition temperature of fluoropolymer 2 is preferably 25°C or less, more preferably 20°C or less, further preferably 15°C or less, further preferably 0°C or less, further preferably -5°C or less, and most preferably -10°C or less. The glass transition temperature of fluoropolymer 2 is preferably -25°C or more, more preferably -23°C or more, and further preferably -20°C or more. Here, regarding the glass transition temperature, a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC823e) is used, and after cooling to -75°C, 10 mg of a sample is heated at 20°C / min to obtain a DSC curve, and the temperature of the intersection of the extended line representing the baseline before and after the secondary transition of the DSC curve and the tangent line at the inflection point of the DSC curve is obtained as the glass transition temperature.

[0178] The Mooney viscosity (ML1+10(121°C)) of the fluoropolymer 2 at 121°C is preferably 2 or more, more preferably 5 or more, further preferably 10 or more, particularly preferably 15 or more, and may be 200 or less.

[0179] The Mooney viscosity (ML1+10 (121°C)) of the fluoropolymer 2 at 140°C is preferably 2 or more, more preferably 5 or more, further preferably 10 or more, particularly preferably 15 or more, and may be 200 or less.

[0180] The Mooney viscosity is a value measured in accordance with ASTM-D1646-15 and JIS K6300-1:2013.

[0181] The terminal structure of the fluoropolymer 2 preferably satisfies the following inequality:

[0182] 0.01≤([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH])≤0.25

[0183] (wherein R represents an alkyl group having 1 to 20 carbon atoms). More preferably, 0.03≤([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH]≤0.20.

[0184] When the terminal functional group satisfies the above formula, the adhesiveness and flexibility become good, and excellent functions are obtained.

[0185] That is, [—CH 2 OH] and [—COOH] have a functional group such as a hydroxyl group or a carboxyl group having high affinity, and therefore are preferred in terms of high affinity with the electrolyte solution.

[0186] Therefore, if these functional groups are contained in a certain ratio or more, it is preferred in terms of excellent adhesion. On the other hand, if the amount of [-CH2OH] and [-COOH] is excessive, the flexibility is reduced. From this aspect, it is preferred that [-CH2OH] and [-COOH] are within the above range.

[0187] It should be noted that satisfying the above general formula does not mean that the above fluoropolymer 2 has all the functional groups [-CH3], [-CF2H], [-CH2OH], [-CH2I], [-OC(O)RH], and [-COOH] at the end, but means that the number ratio of the terminal groups present therein is within the above range.

[0188] The amount of each terminal group of the resin can be determined by NMR analysis.

[0189] The terminal group analysis of NMR was measured by the solution NMR method of protons. The analysis sample was adjusted to a 20 wt % solution using acetone-d6 as a solvent for measurement.

[0190] The reference peak is set to 2.05 ppm for the peak of acetone

[0191] Measurement device: Varian VNMRS400

[0192] Resonance frequency: 399.74 (Sfrq)

[0193] Pulse width: 45°

[0194] Each end corresponds to the following peak position.

[0195] [-CH3]: 1.72~1.86ppm

[0196] [-CF2H]: 6.1~6.8ppm

[0197] [-CH2OH]: 3.74~3.80ppm

[0198] [-CH2I]: 3.87~3.92ppm

[0199] [-OC(O)RH]: 1.09~1.16ppm

[0200] [-COOH]: 10~15ppm

[0201] Based on the integrated value of each peak determined by the above measurement, the amount of functional groups was calculated from the intensity of each peak, and the amount was calculated by the following formula based on the result.

[0202] ([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH])

[0203] The method for adjusting [-CH2OH] and [-COOH] to be within the above-specified range is not particularly limited, and can be controlled by a known method (for example, the selection and amount of the initiator used).

[0204] In order to improve adhesion and flexibility and improve solubility in solvents, the number average molecular weight (Mn) of the fluoropolymer 2 is preferably 7,000 to 5,000,000, the weight average molecular weight (Mw) is preferably 10,000 to 10,000,000, and Mw / Mn is preferably 1.0 to 30.0, more preferably 1.5 to 25.0. The number average molecular weight (Mn), weight average molecular weight (Mw) and Mw / Mn are values ​​measured by GPC method.

[0205] The fluoropolymer 2 can be produced by a common radical polymerization method. The polymerization may be in the form of bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, but emulsion polymerization is preferred from the viewpoint of ease of industrial implementation.

[0206] In the polymerization, a polymerization initiator, a chain transfer agent, a surfactant and a solvent may be used, and any known substance may be used. In the polymerization of the copolymer, an oil-soluble radical polymerization initiator or a water-soluble radical initiator may be used as the polymerization initiator.

[0207] The oil-soluble free radical polymerization initiator may be a known oil-soluble peroxide, and representative examples thereof include: dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and di-sec-butyl peroxydicarbonate; peroxyesters such as tert-butyl peroxyisobutyrate and tert-butyl peroxypivalate; dialkyl peroxides such as di-tert-butyl peroxide; and di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-tetradecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecanoyl) peroxide, di(perfluorobutanoyl) peroxide, di(perfluoropentanoyl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide. peroxide, bis(perfluorononanoyl) peroxide, bis(ω-chloro-hexafluorobutyryl) peroxide, bis(ω-chloro-decafluorohexanoyl) peroxide, bis(ω-chloro-tetrafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydro-dodecafluoroheptanoyl-perfluorobutyryl-peroxide, bis(dichloropentafluorobutyryl) peroxide, bis(trichlorooctafluorohexanoyl) peroxide, bis(tetrachloroundecanoyl) peroxide, bis(pentachlorotetrafluorodecanoyl) peroxide, bis(undecachlorotriacontafluorodocosanoyl) peroxide, etc.

[0208] As the water-soluble free radical polymerization initiator, it can be a known water-soluble peroxide, for example, ammonium salts, potassium salts, sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, percarbonic acid, tert-butyl peroxymaleate, tert-butyl hydroperoxide, etc. It can also contain sulfites and reducing agents such as sulfites, and the amount thereof can be 0.1 to 20 times that of the peroxide.

[0209] The amount of the free radical polymerization initiator added is not particularly limited, and can be added all at once, sequentially, or continuously at the initial stage of polymerization in an amount that does not significantly reduce the polymerization rate (for example, a concentration of several ppm relative to water). The upper limit is the range in which the polymerization reaction heat can be removed from the device surface.

[0210] The solvent is preferably a solvent without chain transfer properties, such as dichloropentafluoropropane (R-225) in solution polymerization, and water, a mixture of water and a water-soluble organic solvent, or a mixture of water and a water-insoluble organic solvent in emulsion polymerization and suspension polymerization.

[0211] In the above polymerization, examples of chain transfer agents include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as isopentane, methane, ethane, propane, isopropanol, acetone, various mercaptans, carbon tetrachloride, and cyclohexane.

[0212] Bromine compounds or iodine compounds may also be used as chain transfer agents. As a polymerization method using a bromine compound or an iodine compound, for example, a method of performing emulsion polymerization in an aqueous medium under pressure in the presence of a bromine compound or an iodine compound in a substantially oxygen-free state (iodine transfer polymerization method) may be cited. As a representative example of the bromine compound or iodine compound used, for example, the general formula:

[0213] R 2 I x Br y

[0214] (where x and y are integers from 0 to 2 and satisfy 1≤x+y≤2, R 2 is a saturated or unsaturated fluorocarbon group or chlorofluorocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, wherein R 2 The compound shown in FIG. 1 is a compound of the type shown in FIG. 1 (containing or not containing oxygen atoms).

[0215] Examples of the iodine compound include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodoperfluoropropane-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodoperfluoropentane-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodoperfluoropropane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrC F2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluoro-1-butene, 2-bromo-4-iodoperfluoro-1-butene, mono-iodine and mono-bromine substitutions of benzene, di-iodine and mono-bromine substitutions, and (2-iodoethyl) and (2-bromoethyl) substitutions, etc. These compounds can be used alone or in combination with each other.

[0216] Among these, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane are preferably used in view of polymerization reactivity, crosslinking reactivity, and availability.

[0217] About the polymer obtained by the above method, in the case of emulsion polymerization, the polymer of powder state can be obtained by precipitating the dispersion liquid that completes polymerization, and washing, dehydrating, drying. Precipitation can be carried out by adding inorganic salts or inorganic acids such as aluminum sulfate or imparting mechanical shear force or freezing dispersion liquid. In the case of suspension polymerization, the polymer of powder state can be obtained by reclaiming and drying from the dispersion liquid that completes polymerization. In the case of solution polymerization, the solution comprising the polymer can be directly dried and obtained, or it can be obtained by dripping a poor solvent and refining.

[0218] As the fluoropolymer 2, one kind may be used, or two or more kinds may be used. In particular, a mode in which two copolymers having different molecular structures are used in combination is also possible.

[0219] (Fluoropolymer 3)

[0220] The fluoropolymer used in the present disclosure may contain a copolymer of vinylidene fluoride and a monomer represented by the above formula (3).

[0221] In the above formula (3), R 1 , R 2 and R 3 Each of them is independently a hydrogen atom, a chlorine atom or an alkyl group having 1 to 5 carbon atoms. From the viewpoint of polymerization reaction, it is particularly desirable that R 1 , R 2 It is a substituent with little steric hindrance, preferably hydrogen or an alkyl group having 1 to 3 carbon atoms, preferably hydrogen or methyl.

[0222] In the above formula (3), X is a single bond or an atomic group with a main chain consisting of 1 to 20 atoms and a molecular weight of 500 or less, preferably 200 or less. In addition, the lower limit of the molecular weight when it is an atomic group is not particularly limited, but is usually 15. If it is within this range, it is preferred from the perspective of appropriately suppressing the gelation of the electrode mixture slurry.

[0223] In the above formula (3), X may be a structure represented by the following formula (3-1).

[0224] -COO-X'···(3-1)

[0225] In the above formula (3-1), X' is an atomic group with a molecular weight of 456 or less, the main chain of which is composed of 1 to 18 atoms, preferably the main chain is composed of 1 to 13 atoms, more preferably the main chain is composed of 1 to 8 atoms, and the molecular weight is preferably 156 or less. In addition, the lower limit of the molecular weight of X' as an atomic group is not particularly limited, and is usually 14. If it is within this range, it is preferred from the perspective of polymerizability. It should be noted that the number of atoms in the main chain does not include the number of hydrogen atoms. In addition, the number of atoms in the main chain refers to the minimum number of atoms that connects the carboxyl group recorded on the right side of X in formula (3) and the group (R 1 R 2 C=CR 3 -) is the number of atoms in the backbone portion of the chain. In addition, X may be branched by including a functional group as a side chain. The side chain included in X may be one or more.

[0226] Y in the above general formula (3) represents an inorganic cation and / or an organic cation.

[0227] Examples of inorganic cations include cations of H, Li, Na, K, Mg, Ca, Al, and Fe. Examples of organic cations include NH4, NH3, and R 15 NH2R 15 2. NHR 15 3. NR 15 4(R 15 Y is preferably H, Li, Na, K, Mg, Ca, Al, NH4, more preferably H, Li, Na, K, Mg, Al, NH4, further preferably H, Li, Al, NH4, and particularly preferably H. It should be noted that, for the sake of convenience, specific examples of inorganic cations and organic cations are described with symbols and valences omitted.

[0228] In addition, the monomer shown in the above formula (3) is preferably a compound containing a polar group. As a compound containing a polar group, for example, a compound containing a carboxyl group, an epoxy group, a hydroxyl group, a sulfonic acid group, etc. can be cited, wherein a compound containing a carboxyl group is preferably used. From the aspect of good bonding between the electrode active material and the collector, it is preferred that the compound containing a polar group shown in the above formula (3) contains a carboxyl group.

[0229] As the polar group-containing compound represented by formula (3), specifically, for example, acrylic acid (AA), 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, acryloxyethyl succinic acid (AES), acryloxypropyl succinic acid (APS), etc. can be cited, among which acrylic acid, 2-carboxyethyl acrylate, acryloxyethyl succinic acid and acryloxypropyl succinic acid are preferred. In the present disclosure, as the polar group-containing compound represented by formula (1), one or more kinds can be included.

[0230] The fluoropolymer 3 used in the present disclosure preferably has 0.01 mol% to 10 mol% (wherein the total of the structural unit derived from vinylidene fluoride and the structural unit derived from the monomer represented by formula (3) is set to 100 mol%) of the structural unit derived from the monomer represented by formula (3), more preferably 0.20 mol% to 7 mol%, and particularly preferably 0.30 mol% to 4 mol%. In addition, it is preferred to have 90 mol% to 99.99 mol% of the structural unit derived from vinylidene fluoride, more preferably 93 mol% to 99.75 mol%, and particularly preferably 96 mol% to 99.63 mol%. When the structural unit derived from the monomer represented by formula (3) is 0.01 mol% or more, the proportion of formula (3) in the fluoropolymer will not become too small, and the effect of inhibiting the gelation of the fluoropolymer solution can be obtained. In addition, when the structural unit derived from the monomer represented by formula (3) is 10 mol% or less, the viscosity will not become too high, and it is possible to prevent the coating from becoming difficult.

[0231] It should be noted that the amount of the vinylidene fluoride unit of the fluoropolymer 3 and the amount of the monomer unit represented by the above formula (3) can usually be determined by the amount of the copolymer. 1 The content of MgCl2 can be determined by H NMR spectroscopy or neutralization titration.

[0232] The fluoropolymer 3 used in the present disclosure may also have components of other monomers other than the monomers shown in vinylidene fluoride and the above-mentioned formula (3). For example, fluorine-based monomers or hydrocarbon monomers such as ethylene and propylene that can copolymerize with vinylidene fluoride and monomers that can copolymerize with the above-mentioned formula (3) can be cited. As fluorine-based monomers that can copolymerize with vinylidene fluoride, vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether represented by perfluoromethyl vinyl ether, etc. can be cited. As monomers that can copolymerize with the above-mentioned formula (3), (meth) acrylic acid, (meth) alkyl acrylate compounds represented by methyl (meth) acrylate, etc. can be cited. It should be noted that other monomers can be used alone or in combination.

[0233] When the fluoropolymer 3 contains the other monomer, it is preferred that the fluoropolymer 3 contains 0.01 mol % to 10 mol % of the other monomer unit, based on 100 mol % of all monomer units constituting the fluoropolymer 3.

[0234] The weight average molecular weight of the fluoropolymer 3 used in the present disclosure determined by GPC (gel permeation chromatography) measurement is usually in the range of 50,000 to 1,500,000.

[0235] The fluoropolymer 3 can be obtained by polymerizing vinylidene fluoride and at least one of the monomers represented by the above formula (3) using an existing known method. There is no particular limitation on the polymerization method, and examples thereof include suspension polymerization, emulsion polymerization, and solution polymerization. Among them, from the perspective of ease of post-processing, the polymerization method is preferably aqueous suspension polymerization or emulsion polymerization. In addition, the vinylidene fluoride used in the polymerization and the monomer represented by the above formula (3) are respectively known compounds, and general commercial products can be used.

[0236] The fluoropolymer 3 is usually preferably obtained by copolymerizing 90 to 99.9 parts by mass of vinylidene fluoride and 0.1 to 10 parts by mass of the monomer represented by the above formula (3), and more preferably 95 to 99.9 parts by mass of vinylidene fluoride and 0.1 to 5 parts by mass of the monomer represented by the above formula (3) (wherein the total of vinylidene fluoride and the monomer represented by the above formula (3) is set to 100 parts by mass).

[0237] The intrinsic viscosity ηi of the fluoropolymer 3 is preferably 0.5 dl / g to 5.0 dl / g, more preferably 1.0 dl / g to 4.0 dl / g, and further preferably 1.5 dl / g to 3.5 dl / g. If the intrinsic viscosity is within the above range, the productivity will not be deteriorated due to the decrease in the solid content of the fluororesin solution, and the thickness of the electrode will not be uneven when the electrode mixture is applied, which is preferred from the perspective of facilitating electrode production.

[0238] The intrinsic viscosity ηi can be determined by dissolving 80 mg of the polymer in 20 ml of N,N-dimethylformamide and using an Ubbelohde viscometer in a constant temperature bath at 30° C. using the following formula.

[0239] ηi=(1 / C)·ln(η / η0)

[0240] In the above formula, η is the viscosity of the polymer solution, η0 is the viscosity of N,N-dimethylformamide as a solvent, and C is 0.4 g / dl.

[0241] When the intrinsic viscosity is within the above range, the productivity will not be deteriorated due to a decrease in the solid content of the fluororesin solution, and the thickness of the electrode will not be uneven when the electrode mixture is applied, which is preferable in that the electrode can be easily produced.

[0242] (negative electrode)

[0243] The negative electrode in the secondary battery of the present disclosure preferably includes a metallic layer of at least one metal element selected from the group consisting of lithium, sodium, magnesium, and zinc.

[0244] In addition, in the above-mentioned first embodiment, the negative electrode must include a metallic layer of at least one metal element selected from the group consisting of lithium, sodium, magnesium and zinc.

[0245] In the second embodiment, the electrode does not have a metallic layer when it is manufactured. The metallic layer of the metallic element formed by charging thereafter is preferably composed of at least one metallic element selected from the group consisting of lithium, sodium, magnesium and zinc.

[0246] Among these, it is most preferable to use a lithium metal single substance or an alloy containing the lithium metal single substance, and the most preferable is lithium metal single substance.

[0247] The negative electrode can be manufactured by a general method for manufacturing metal foil. In addition, when an alloy material is used, a method of forming a thin film layer (negative electrode active material layer) containing the above-mentioned negative electrode active material by a method such as evaporation, sputtering, or plating is also used.

[0248] The thickness of the negative electrode plate is designed according to the positive electrode plate used and is not particularly limited. The thickness of the composite layer obtained by subtracting the thickness of the metal foil of the core material is usually 15 μm or more, preferably 20 μm or more, and more preferably 30 μm or more. In addition, it is usually 300 μm or less, preferably 280 μm or less, and more preferably 250 μm or less.

[0249] (Current Collector for Negative Electrode)

[0250] Examples of the material of the negative electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, nickel, copper, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum, copper, or alloys thereof, are preferred.

[0251] As the shape of the current collector, in the case of metal materials, metal foil, metal cylinder, metal coil, metal plate, metal film, metal sheet, stamped metal, foamed metal, etc. can be mentioned, and in the case of carbon materials, carbon plate, carbon film, carbon cylinder, etc. can be mentioned. Among these, metal film is preferred. It should be noted that the film can be suitably formed into a mesh. The thickness of the film is arbitrary, usually more than 1 μm, preferably more than 3 μm, more preferably more than 5 μm, and usually less than 1 mm, preferably less than 100 μm, more preferably less than 50 μm. If the film is thinner than this range, the strength required as a current collector is sometimes insufficient. On the contrary, if the film is thicker than this range, the handleability is sometimes impaired.

[0252] In addition, from the viewpoint of reducing electrical contact resistance, it is also preferred that a conductive auxiliary agent is coated on the surface of the current collector. Examples of the conductive auxiliary agent include carbon or noble metals such as gold, platinum, and silver.

[0253] The ratio of the thickness of the current collector to the negative electrode active material layer is not particularly limited, and the value of (the thickness of the negative electrode active material layer on one side before the liquid electrolyte is injected) / (the thickness of the current collector) is preferably less than 20, more preferably less than 15, and most preferably less than 10. In addition, it is preferably more than 0.5, more preferably more than 0.8, and most preferably more than 1. If it exceeds this range, the current collector sometimes generates heat caused by Joule heat during high current density charging and discharging. If it is less than this range, the volume ratio of the collector increases and the capacity of the battery sometimes decreases.

[0254] The coating with the fluoropolymer is preferably performed in a coating thickness of 3 μm to 8 μm before drying. By setting the coating thickness within such a range, the effects of the present disclosure can be appropriately exhibited.

[0255] (Method for manufacturing negative electrode)

[0256] The negative electrode of the present disclosure can be produced by a method of applying the above-mentioned polymer solution on the negative electrode material or the current collector and drying it, or by a method of calendering and pasting it.

[0257] Examples of solvents used in preparing a polymer solution include N-methyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone and N-butyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, hexamethylphosphoramide, dimethyl sulfoxide, diethylenetriamine, N,N-dimethylaminopropylamine, diethyl ether, propylene oxide, tetrahydrofuran, and the like.

[0258] The content of the polymer in the polymer solution is preferably 3% by mass to 40% by mass, more preferably 5% by mass to 15% by mass, based on the entire polymer solution.

[0259] The density of the dried coating layer is preferably 0.3 g / cm 3 ~3.0g / cm 3 , more preferably 1 g / cm 3 ~2g / cm 3 .

[0260] The thickness of the coating layer after drying can be calculated from the weight of the fluoropolymer in the polymer solution and the thickness of the coating layer applied to the negative electrode material or the current collector.

[0261] In the second method, the collector formed with a coating layer is put into liquid nitrogen for freeze-drying, and the freeze-dried sample is cut perpendicularly to the coating layer to prepare a sample for cross-sectional observation. The coating layer cross-section of the sample is observed using a scanning electron microscope (SEM), thereby also being able to measure the thickness of the coating layer after drying.

[0262] The density of the coating layer after drying can be calculated by calculating the weight from the weight change of the coating layer before and after drying and dividing the calculated weight by the volume of the coating layer after drying.

[0263] (Battery)

[0264] The present invention discloses a secondary battery having the above-mentioned negative electrode and a liquid electrolyte containing a fluorinated ether as an essential component. The above-mentioned fluorinated ether and the liquid electrolyte containing it are described in detail below. When an electrolyte containing a fluorinated ether is used and the above-mentioned negative electrode is used, the formation of dendrites can be particularly reduced, which is preferred from this aspect.

[0265] (Fluorinated ether)

[0266] The liquid electrolyte preferably contains less than 90% by mass of the fluorinated ether in the entire electrolyte solvent.

[0267] The fluorinated ether is not particularly limited as long as it is an ether compound partially containing fluorine.

[0268] Examples of the fluorinated ether include other fluorinated ethers represented by the following general formula (I).

[0269] R 4 -O-Rf 5 (I)

[0270] (Where Rf 4 and Rf 5 are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluorinated alkyl group having 1 to 10 carbon atoms. 4 and Rf 5 At least one of them is a fluorinated alkyl group. )

[0271] By containing other fluorinated ethers, the flame retardancy of the liquid electrolyte is improved, and the stability and safety at high temperature and high voltage are improved.

[0272] In the above general formula (I), Rf 4 and Rf 5 At least one of the above mentioned compounds may be a fluorinated alkyl group having 1 to 10 carbon atoms. In order to further improve the flame retardancy, stability at high temperature and high voltage, and safety of the liquid electrolyte, Rf is preferably 4 and Rf 5 are all fluorinated alkyl groups having 1 to 10 carbon atoms. In this case, Rf 4 and Rf 5 They can be the same or different from each other.

[0273] Among them, Rf is more preferred 4 and Rf 5 Same or different, Rf 4 is a fluorinated alkyl group having 3 to 6 carbon atoms, and Rf 5 It is a fluorinated alkyl group having 2 to 6 carbon atoms.

[0274] If Rf 4 and Rf 5 If the total number of carbon atoms is too small, the boiling point of the fluorinated ether becomes too low. 4 or Rf 5 If the number of carbon atoms is too large, the solubility of the electrolyte salt decreases, and the compatibility with other solvents begins to be adversely affected. In addition, the viscosity increases, so the rate characteristics decrease. 4 The number of carbon atoms is 3 or 4, Rf 5 When the number of carbon atoms is 2 or 3, it is advantageous in that the boiling point and rate characteristics are excellent.

[0275] Examples of such fluorinated ethers include fluorinated ethers represented by the following general formula (10).

[0276] HCF2CF2-OR(10)

[0277] (In the formula, R is an alkyl group which may contain an ether group, or a fluorinated alkyl group which may contain an ether group.)

[0278] First, the fluorinated ether compound represented by the general formula (10) will be described in detail below, and then fluorinated ether compounds other than the fluorinated ether compound represented by the general formula (10) (hereinafter sometimes referred to as "other fluorinated ether compounds") will be described.

[0279] In the present disclosure, the fluorinated ether compound represented by the above general formula (10) may be used in combination with "other fluorinated ether compounds".

[0280] In the compound represented by the general formula (10), the fluorinated alkyl group is preferably a fluorinated alkyl group having 1 to 10 carbon atoms, and more preferably a fluorinated alkyl group having 2 to 6 carbon atoms.

[0281] In the compound represented by the general formula (10), if the number of carbon atoms of the fluorinated alkyl group is too small, the boiling point is lowered and the volatility of the electrolyte becomes higher. On the other hand, if the number of carbon atoms is too large, the viscosity is increased and the output characteristics are reduced.

[0282] The compound represented by the general formula (10) preferably has a fluorine content of 40% to 75% by mass. When the fluorine content is within this range, the balance between non-flammability and compatibility is particularly good. It is also preferred from the perspective of good oxidation resistance and safety.

[0283] The lower limit of the fluorine content is more preferably 43% by mass, further preferably 45% by mass, and particularly preferably 50% by mass, and the upper limit is more preferably 70% by mass, further preferably 66% by mass.

[0284] The fluorine content of the fluorinated ether is a value calculated based on the structural formula of the fluorinated ether according to {(the number of fluorine atoms×19) / molecular weight of the fluorinated ether}×100(%).

[0285] R includes, for example, -CH2CF2CF3, -CF2CFHCF3, -CF2CF2CF2H, -CH2CF2CF2H, -CH2CH2CF2CF3, -CH2CF2CFHCF3, -CF2CF2CF2CF2H, -CH2CF2CF2CF2H, -CH2CH2CF2CF2H, -CH2CF(CF3)CF2H, -CF2CF2H, -CH2CF2H, -CH2CF3, -CF2CH 3、 -CH2-CH3, CH2-CH2-CH3, CH2-CH2-CH2-CH3, -CH2CH2-O-CF2CF2H, -CH2CH2-O-CH3, -CH2CH2-O-CH2CH 3. -CH2CH2-O-CF3, -CH2CH2-O-CH2CF3, -CH2CH2-O-CF2CF2H, -CH2CH2-O-CF2H, -CH2CH2-O-CH2CF2H, etc.

[0286] Specific examples of the compounds represented by the general formula (10) include HCF2CF2-O-CH2CF2CF2H, HCF2CF2-O-CH2CF2CF3, HCF2CF2-O-CH2CF3, HCF2-CF2-O-CH2-CH2-CH3, HCF2-CF2-O-CH2-CH2-CH3, HCF2-CF2-O-CH2-CH2-CH2-CH3, HCF2-CF2-O-CH2-CH2-CH3, HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, etc.

[0287] The fluorinated ether represented by the general formula (10) is particularly preferably at least one fluorinated ether selected from the group consisting of fluorinated ethers represented by the following general formulas (12) to (14).

[0288] HCF2CF2-O-CH2CF2CF2H(12)

[0289] HCF2CF2-O-CH2CF2CF3(13)

[0290] HCF2CF2-O-CH2CF3(14)

[0291] In particular, the inclusion of the fluorinated ether represented by the above general formulas (12) to (14) as an additive in the liquid electrolyte is advantageous in lowering the flash point of the electrolyte.

[0292] Examples of the other fluorinated ethers (that is, fluorinated ethers other than those represented by the general formula (10)) include the following fluorinated ethers.

[0293] The fluorine content of the other fluorinated ether is preferably 40% to 75% by mass. When the fluorine content is within this range, the balance between non-flammability and compatibility is particularly excellent. In addition, it is also preferred from the perspective of good oxidation resistance and safety.

[0294] The lower limit of the fluorine content is more preferably 45% by mass, further preferably 50% by mass, and particularly preferably 55% by mass, and the upper limit is more preferably 70% by mass, further preferably 66% by mass.

[0295] The fluorine content of other fluorinated ethers is a value calculated based on the structural formula of other fluorinated ethers according to {(number of fluorine atoms×19) / molecular weight of other fluorinated ethers}×100(%).

[0296] As Rf 4, for example, CF3CF2CH2-, CF3CFHCF2-, HCF2CF2CF2-, HCF2CF2CH2-, CF3CF2CH2CH2-, CF3CFHCF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CF2CH2-, HCF2CF2CH2CH2-, HCF2CF(CF3)CH2-, etc. can be mentioned. In addition, as Rf 4 For example, -CH2CF2CF3, -CF2CFHCF3, -CF2CF2CF2H, -CH2CF2CF2H, -CH2CH2CF2CF3, -CH2CF2CFHCF3, -CF2CF2CF2CF2H, -CH2CF2CF2CF2H, -CH2CH2CF2CF2H, -CH2CF(CF3)CF2H, -CF2CF2H, -CH2CF2H, -CF2CH3, etc. can be mentioned.

[0297] Specific examples of the other fluorinated ethers include HCF2CF2CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, C6F 13 OCH3、C6F 13 OC2H5、C8F 17 OCH3、C8F 17 OC2H5, CF3CFHCF2CH(CH3)OCF2CFHCF3, HCF2CF2OCH(C2H5)2, HCF2CF2OC4H9, HCF2CF2OCH2CH(C2H5)2, HCF2CF2OCH2CH(CH3)2, etc.

[0298] Among them, the substance containing HCF2 at one or both ends has excellent polarizability and can provide other fluorinated ethers with high boiling points. The boiling point of other fluorinated ethers is preferably 67°C to 120°C, more preferably 80°C or higher, and even more preferably 90°C or higher.

[0299] Examples of such other fluorinated ethers include one or more of CF3CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, HCF2CF2CH2OCF2CFHCF3, HCF2CF2CH2OCH2CF2CF2H, CF3CFHCF2CH2OCF2CFHCF3, and HCF2CF2CH2OCF2CF2H.

[0300] Among them, it is advantageous from the aspects of high boiling point, compatibility with other solvents and good solubility of electrolyte salt. Therefore, it is preferably at least one selected from the group consisting of HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C) and CF3CF2CH2OCF2CFHCF3 (boiling point 82°C), and HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C) is more preferred.

[0301] The content of the fluorinated ether in the liquid electrolyte is preferably less than 90% by mass.

[0302] When the content is within this range, the liquid electrolyte can be used as a good liquid electrolyte. That is, if the content is increased, the concentration of the liquid electrolyte increases, and the ion conductivity decreases, so the battery life decreases.

[0303] The lower limit is preferably 3% by mass, more preferably 5% by mass, and the upper limit is preferably 70% by mass, more preferably 60% by mass.

[0304] When the fluorinated ether represented by the general formula (10) is used, the content of the fluorinated ether is preferably within the above range.

[0305] (Components other than fluorinated ethers in liquid electrolyte)

[0306] The liquid electrolyte disclosed herein preferably contains components other than the fluorinated ether. Components that can be mixed into such a liquid electrolyte are described in detail below.

[0307] The solvent preferably contains at least one selected from the group consisting of carbonate esters and carboxylic acid esters.

[0308] The carbonate ester mentioned above may be a cyclic carbonate ester or a chain carbonate ester.

[0309] The cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0310] Examples of the non-fluorinated cyclic carbonate include non-fluorinated saturated cyclic carbonates, preferably non-fluorinated saturated alkylene carbonates having an alkylene group having 2 to 6 carbon atoms, and more preferably non-fluorinated saturated alkylene carbonates having an alkylene group having 2 to 4 carbon atoms.

[0311] Among them, as the above-mentioned non-fluorinated saturated cyclic carbonate, from the aspect of high dielectric constant and suitable viscosity, it is preferably selected from at least one of the group consisting of ethylene carbonate, propylene carbonate, cis-2,3-pentylene carbonate, cis-2,3-butylene carbonate, 2,3-pentylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 1,2-butylene carbonate and butylene carbonate.

[0312] The above-mentioned non-fluorinated saturated cyclic carbonate ester may be used alone or in combination of two or more in any ratio.

[0313] When the non-fluorinated saturated cyclic carbonate is contained, the content of the non-fluorinated saturated cyclic carbonate is preferably 5 to 90 volume %, more preferably 10 to 60 volume %, and further preferably 15 to 45 volume % based on the solvent.

[0314] The fluorinated cyclic carbonate is a cyclic carbonate having a fluorine atom. A solvent containing the fluorinated cyclic carbonate can be suitably used even at a high voltage.

[0315] In addition, in this specification, "high voltage" means a voltage of 4.2V or more. In addition, the upper limit of "high voltage" is preferably 4.9V.

[0316] The fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0317] The fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom, and specifically, the following general formula (A) can be cited.

[0318] [Chemistry 13]

[0319]

[0320] (Where X 1 ~X 4 are the same or different and represent -H, -CH3, -C2H5, -F, a fluorinated alkyl group with or without an ether bond, or a fluorinated alkoxy group with or without an ether bond. 1 ~X 4 At least one of them is -F, a fluorinated alkyl group having or not having an ether bond, or a fluorinated alkoxy group having or not having an ether bond). The above-mentioned fluorinated alkyl group is -CF3, -CF2H, -CH2F, etc.

[0321] When the liquid electrolyte of the present disclosure is applied to a high-voltage lithium-ion secondary battery or the like, the inclusion of the fluorinated saturated cyclic carbonate improves the oxidation resistance of the liquid electrolyte, and stable and excellent charge and discharge characteristics can be obtained.

[0322] In addition, in this specification, "ether bond" is a bond represented by -O-.

[0323] From the perspective of good dielectric constant and oxidation resistance, X is preferred. 1 ~X 4 One or two of them are -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond.

[0324] Since it is expected that the viscosity at low temperature will be reduced, the flash point will be raised, and the solubility of the electrolyte salt will be improved, X 1 ~X 4 Preferred are -H, -F, a fluorinated alkyl group (a), a fluorinated alkyl group having an ether bond (b), or a fluorinated alkoxy group (c).

[0325] The fluorinated alkyl group (a) is obtained by replacing at least one of the hydrogen atoms of the alkyl group with a fluorine atom. The number of carbon atoms in the fluorinated alkyl group (a) is preferably 1 to 20, more preferably 1 to 17, further preferably 1 to 7, and particularly preferably 1 to 5. If the number of carbon atoms is too large, the low-temperature characteristics may be reduced or the solubility of the electrolyte salt may be reduced. If the number of carbon atoms is too small, the solubility of the electrolyte salt may be reduced, the discharge efficiency may be reduced, and the viscosity may be increased.

[0326] Examples of the fluorinated alkyl group having 1 carbon atom in the fluorinated alkyl group (a) include CFH2-, CF2H-, and CF3-. In particular, CF2H- or CF3- is preferred in terms of high temperature storage characteristics, and CF3- is most preferred.

[0327] As the fluorinated alkyl group having 2 or more carbon atoms in the fluorinated alkyl group (a), preferably, from the viewpoint of good solubility of the electrolyte salt, a fluorinated alkyl group represented by the following general formula (a-1) can be exemplified.

[0328] R 8 -R 9 -(a-1)

[0329] (Where R 8 is an alkyl group having 1 or more carbon atoms and having or not having a fluorine atom; R 9 is an alkylene group having 1 to 3 carbon atoms and having or not having a fluorine atom; wherein R 1 and R 2 At least one of them has a fluorine atom. )

[0330] It should be noted that R 1 and R 2 It may contain atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0331] R 8 It is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. 8 , preferably a linear or branched alkyl group having 1 to 16 carbon atoms. 8 The number of carbon atoms in the moiety is more preferably 1-6, and even more preferably 1-3.

[0332] As R 8Specifically, examples of the linear or branched alkyl group include CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0333] [Chemistry 14]

[0334] wait.

[0336] In addition, in R 8 In the case of a straight-chain alkyl group having a fluorine atom, examples include CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2 CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2 CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2C F2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3 CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2C H2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HFCClCF2CFClCF2CH2-, etc.

[0337] In addition, in R 8 In the case of a branched alkyl group having a fluorine atom, preferably

[0338] [Chemistry 15]

[0339]

[0340] [Chemistry 16]

[0341] wait.

[0342] Among them, if there are branches such as CH3- and CF3-, the viscosity tends to be high, so the number thereof is preferably small (one) or zero.

[0343] R 9 It is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom. 9 It may be linear or branched. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below. 9 It is composed of them individually or in combination.

[0344] (i) The smallest structural unit of a straight chain:

[0345] -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0346] (ii) The smallest structural unit of a branched chain:

[0347] [Chemistry 17]

[0348]

[0349] Among the above examples, it is preferred that the structure be composed of a structural unit not containing Cl, since it does not cause a dehydrochlorination reaction by a base and is more stable.

[0350] In R 9 In the case of a linear chain, it is composed only of the above-mentioned linear minimum structural unit, among which -CH2-, -CH2CH2- or -CF2- are preferred. From the perspective of being able to further improve the solubility of the electrolyte salt, -CH2- or -CH2CH2- is more preferred.

[0351] In R 9 In the case of a branched chain, it is a group containing at least one of the minimum structural units of the branched chain, and preferably, it can be exemplified by the general formula: a X b )-(X a is H, F, CH3 or CF3; X bis CH3 or CF3. b In the case of CF3, X a These units can further improve the solubility of the electrolyte salt.

[0352] Preferred fluorinated alkyl groups (a) include CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CHF-, CH3CF2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0353] [Chemistry 18]

[0354]

[0355] [Chemistry 19]

[0356] wait.

[0358] The above-mentioned fluorinated alkyl group (b) having an ether bond is obtained by replacing at least one of the hydrogen atoms possessed by the alkyl group having an ether bond with a fluorine atom. The number of carbon atoms of the above-mentioned fluorinated alkyl group (b) having an ether bond is preferably 2 to 17. If the number of carbon atoms is too large, the viscosity of the above-mentioned fluorinated saturated cyclic carbonate becomes higher. In addition, due to the increase in the number of fluorinated groups, it is sometimes observed that the solubility of the electrolyte salt caused by the decrease in dielectric constant and the compatibility with other solvents are reduced. From this aspect, the number of carbon atoms of the above-mentioned fluorinated alkyl group (b) having an ether bond is more preferably 2 to 10, and further preferably 2 to 7.

[0359] The alkylene group constituting the ether portion of the fluorinated alkyl group (b) having an ether bond may be a linear or branched alkylene group. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below.

[0360] (i) The smallest structural unit of a straight chain:

[0361] -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0362] (ii) The smallest structural unit of a branched chain:

[0363] [Chemistry 20]

[0364]

[0365] The alkylene group may be composed of these minimum structural units alone, or may be composed of linear (i) groups, branched (ii) groups, or a combination of a linear (i) group and a branched (ii) group. Preferred specific examples are described below.

[0366] Among the above examples, it is preferred that the structure be composed of a structural unit not containing Cl, since it does not cause a dehydrochlorination reaction by a base and is more stable.

[0367] As a more preferable fluorinated alkyl group (b) having an ether bond, a group represented by the general formula (b-1) can be mentioned.

[0368] R 10 -(OR 11 ) n2 -(b-1)

[0369] (Where R 10 is an alkyl group having 1 to 6 carbon atoms which may or may not have a fluorine atom; R 11 is an alkylene group having 1 to 4 carbon atoms and having or not having a fluorine atom; n2 is an integer of 1 to 3; wherein R 3 and R 4 At least one of them has a fluorine atom. )

[0370] As R 10 and R 11 The following groups can be exemplified, and these groups can be appropriately combined to form the fluorinated alkyl group (b) having an ether bond represented by the above general formula (b-1), but the present invention is not limited to these groups.

[0371] (1) As R 10 , preferably of the general formula: General formula: X c 3C-(R 12 ) n3 -(3 X c Same or different, both H or F; R 12 is an alkylene group having 1 to 5 carbon atoms and which may have a fluorine atom; n3 is an alkyl group represented by 0 or 1).

[0372] When n3 is 0, R 10 , examples include CH3-, CF3-, HCF2- and H2CF-.

[0373] As a specific example when n3 is 1, R 10It is a straight-chain group, and examples thereof include CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2CH2-, CF3CF2CH2CH2- , CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF 2CF2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF 2CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, H CF2CF2CF2CF2CH2CH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, CH3CF2-, CH3CH2-, CH3CF2CH2-, CH3CF2CF2-, CH3CH2C H2-, CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CH2CH2CH2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CH2CF2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, etc.

[0374] As n3 is 1 and R 10 For branched groups, examples include

[0375] [Chemistry 21]

[0376] wait.

[0377] Among them, if there is a branch such as CH3- or CF3-, the viscosity tends to be high, so R is more preferred. 10 It is a straight chain.

[0378] (2) -(OR 4 ) n2 -, n2 is an integer of 1 to 3, preferably 1 or 2. It should be noted that when n2 = 2 or 3, R 11 Can be the same or different.

[0379] As R 11 Preferred specific examples include the following linear or branched groups.

[0380] Examples of the straight-chain group include -CH2-, -CHF-, -CF2-, -CH2CH2-, -CF2CH2-, -CF2CF2-, -CH2CF2-, -CH2CH2CH2-, -CH2CH2CF2-, -CH2CF2CH2-, -CH2CF2CF2-, -CF2CH2CH2-, -CF2CF2CH2-, -CF2CH2CF2-, -CF2CH2CF2-, -CF2CH2CF2- and the like.

[0381] Examples of branched groups include

[0382] [Chemistry 22]

[0383] wait.

[0384] The fluorinated alkoxy group (c) is obtained by replacing at least one of the hydrogen atoms in the alkoxy group with a fluorine atom. The fluorinated alkoxy group (c) preferably has 1 to 17 carbon atoms, and more preferably has 1 to 6 carbon atoms.

[0385] As the fluorinated alkoxy group (c), a particularly preferred one is a fluorinated alkoxy group having the general formula: d 3C-(R 13 ) n3 -O-(3 X d Same or different, both H or F; R 13 Preferably, it is an alkylene group having 1 to 5 carbon atoms and having or not having a fluorine atom; n3 is 0 or 1; wherein 3 X d A fluorinated alkoxy group represented by (any of which contains a fluorine atom).

[0386] Specific examples of the fluorinated alkoxy group (c) include: 8 The exemplified alkyl groups have a fluorinated alkoxy group having an oxygen atom bonded to the terminal.

[0387] The fluorine content of the fluorinated alkyl (a), the fluorinated alkyl (b) and the fluorinated alkoxy (c) in the above-mentioned fluorinated saturated cyclic carbonate is preferably more than 10 mass %. If the fluorine content is too low, it is possible to fully obtain the viscosity reduction effect and the rising effect of the flash point under low temperature. From this aspect, the above-mentioned fluorine content is more preferably more than 12 mass %, more preferably more than 15 mass %. The upper limit is usually 76 mass %.

[0388] The fluorine content of the fluorinated alkyl group (a), the fluorinated alkyl group having an ether bond (b), and the fluorinated alkoxy group (c) is a value calculated according to {(number of fluorine atoms×19) / formula weight of each group}×100(%) based on the structural formula of each group.

[0389] In view of good dielectric constant and oxidation resistance, the fluorine content of the fluorinated saturated cyclic carbonate as a whole is preferably 10% by mass or more, more preferably 15% by mass or more, and the upper limit is usually 76% by mass.

[0390] The fluorine content of the fluorinated saturated cyclic carbonate is a value calculated based on the structural formula of the fluorinated saturated cyclic carbonate according to {(number of fluorine atoms×19) / molecular weight of the fluorinated saturated cyclic carbonate}×100(%).

[0391] Specific examples of the fluorinated saturated cyclic carbonate include the following.

[0392] As X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate esters in which at least one of them is -F include:

[0393] [Chemistry 23]

[0394] wait.

[0395] These compounds have high withstand voltage and good solubility of electrolyte salts.

[0396] In addition, you can also use

[0397] [Chemistry 24]

[0398] wait.

[0399] As X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate wherein at least one of the fluorinated alkyl groups (a) is a fluorinated alkyl group and the rest are all -H include:

[0400] [Chemistry 25]

[0401]

[0402] [Chemistry 26]

[0403]

[0404] [Chemistry 27]

[0405] wait.

[0407] As X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate in which at least one of the fluorinated alkyl groups (b) or the fluorinated alkoxy group (c) has an ether bond and the rest are all -H include:

[0408] [Chemistry 28]

[0409]

[0410] [Chemistry 29]

[0411]

[0412] [Chemistry 30]

[0413]

[0414] [Chemistry 31]

[0415]

[0416] [Chemistry 32]

[0417]

[0418] [Chemistry 33] wait. Among them, the fluorinated saturated cyclic carbonate is preferably any one of the following compounds.

[0419] [Chemistry 34]

[0420]

[0421] [Chemistry 35]

[0422]

[0423] Examples of the fluorinated saturated cyclic carbonates include, in addition to these, trans-4,5-difluoro-1,3-dioxolane-2-one, 5-(1,1-difluoroethyl)-4,4-difluoro-1,3-dioxolane-2-one, 4-methylene-1,3-dioxolane-2-one, 4-methyl-5-trifluoromethyl-1,3-dioxolane-2-one, 4-ethyl-5-fluoro-1,3-dioxolane-2-one, 4-ethyl-5,5-difluoro-1,3-dioxolane-2-one, -1,3-dioxolane-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolane-2-one, 4-ethyl-4,5,5-trifluoro-1,3-dioxolane-2-one, 4,4-difluoro-5-methyl-1,3-dioxolane-2-one, 4-fluoro-5-methyl-1,3-dioxolane-2-one, 4-fluoro-5-trifluoromethyl-1,3-dioxolane-2-one, 4,4-difluoro-1,3-dioxolane-2-one, etc.

[0424] Among these, as the fluorinated saturated cyclic carbonate ester, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethylethylene carbonate (3,3,3-trifluoropropylene carbonate), and 2,2,3,3,3-pentafluoropropylethylene carbonate are more preferred.

[0425] The above-mentioned fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom, and is preferably a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond. Specifically, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, etc. can be mentioned.

[0426] The above-mentioned fluorinated cyclic carbonates may be used alone or in combination of two or more in any ratio.

[0427] When the fluorinated cyclic carbonate is contained, the content of the fluorinated cyclic carbonate is preferably 5% to 90% by volume, more preferably 10% to 60% by volume, and even more preferably 15% to 45% by volume based on the solvent.

[0428] The above-mentioned chain carbonate may be a non-fluorinated chain carbonate or a fluorinated chain carbonate.

[0429] As the non-fluorinated chain carbonate, for example, CH3OCOOCH3 (dimethyl carbonate: DMC), CH3CH2OCOOCH2CH3 (diethyl carbonate: DEC), CH3CH2OCOOCH3 (ethyl methyl carbonate: EMC), CH3OCOOCH2CH2CH3 (methyl propyl carbonate), methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl isopropyl carbonate, methyl-2-phenylphenyl carbonate, phenyl-2-phenylphenyl carbonate, trans-2,3-pentylene carbonate, trans-2,3-butylene carbonate, ethylphenyl carbonate and other hydrocarbon chain carbonates can be mentioned. Among them, preferably at least one selected from the group consisting of ethyl methyl carbonate, diethyl carbonate and dimethyl carbonate.

[0430] The above-mentioned non-fluorinated chain carbonates may be used alone or in combination of two or more in any ratio.

[0431] When the non-fluorinated chain carbonate is contained, the content of the non-fluorinated chain carbonate is preferably 10% to 90% by volume, more preferably 40% to 85% by volume, and further preferably 50% to 80% by volume based on the solvent.

[0432] The fluorinated chain carbonate is a chain carbonate having a fluorine atom. A solvent containing the fluorinated chain carbonate can be suitably used even at a high voltage.

[0433] Examples of the fluorinated chain carbonate include compounds represented by the general formula (B).

[0434] R 3 OCOOR 14 (B)

[0435] (Where Rf 3 is a fluorinated alkyl group having 1 to 7 carbon atoms, R 14 It is an alkyl group having 1 to 7 carbon atoms and containing or not containing fluorine atoms.

[0436] R 3 is a fluorinated alkyl group having 1 to 7 carbon atoms, R 14 It is an alkyl group having 1 to 7 carbon atoms and containing or not containing a fluorine atom.

[0437] The fluorinated alkyl group is obtained by replacing at least one of the hydrogen atoms in the alkyl group with a fluorine atom. 14 In the case of an alkyl group containing a fluorine atom, it becomes a fluorinated alkyl group.

[0438] From the perspective of low viscosity, Rf 3 and R 14 The number of carbon atoms in is preferably 1-7, more preferably 1-2.

[0439] If the number of carbon atoms is too large, low-temperature characteristics may be reduced or the solubility of the electrolyte salt may be reduced. If the number of carbon atoms is too small, a reduction in the solubility of the electrolyte salt, a reduction in discharge efficiency, and an increase in viscosity may be observed.

[0440] Examples of the fluorinated alkyl group having 1 carbon atom include CFH2-, CF2H-, CF3-, etc. In particular, CFH2- or CF3- is preferred from the viewpoint of high-temperature storage characteristics.

[0441] As the fluorinated alkyl group having 2 or more carbon atoms, preferably, there can be mentioned a fluorinated alkyl group represented by the following general formula (d-1), since the solubility of the electrolyte salt is good.

[0442] R 1 -R 2 -(d-1)

[0443] (Where R 1 is an alkyl group having 1 or more carbon atoms and having or not having a fluorine atom; R 2 is an alkylene group having 1 to 3 carbon atoms and having or not having a fluorine atom; wherein R 1 and R 2 At least one of them has a fluorine atom. )

[0444] It should be noted that R 1 and R 2 It may contain atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0445] R 1 It is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. 1 , preferably a linear or branched alkyl group having 1 to 6 carbon atoms. 1 The number of carbon atoms is more preferably 1-3.

[0446] As R 1 Specifically, examples of the linear or branched alkyl group include CH3-, CF3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0447] [Chemistry 36]

[0448] wait.

[0450] In addition, in R 1In the case of a straight-chain alkyl group having a fluorine atom, examples include CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2 CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2 CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2C F2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3 CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2C H2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HFCClCF2CFClCF2CH2-, etc.

[0451] In addition, in R 1 In the case of a branched alkyl group having a fluorine atom, preferably

[0452] [Chemistry 37]

[0453]

[0454] [Chemistry 38]

[0455] wait.

[0456] Among them, if there are branches such as CH3- and CF3-, the viscosity tends to be high, so the number thereof is preferably small (one) or zero.

[0457] R 2 It is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom. 2 It may be linear or branched. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below. 2 It is composed of them individually or in combination.

[0458] (i) The smallest structural unit of a straight chain:

[0459] -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0460] (ii) The smallest structural unit of a branched chain:

[0461] [Chemistry 39]

[0462]

[0463] Among the above examples, it is preferred that the structure be composed of a structural unit not containing Cl, since it does not cause a dehydrochlorination reaction by a base and is more stable.

[0464] In R 2 In the case of a linear chain, it is composed only of the above-mentioned linear minimum structural unit, among which -CH2-, -CH2CH2- or -CF2- are preferred. From the perspective of further improving the solubility of the electrolyte salt, -CH2- or -CH2CH2- is more preferred.

[0465] In R 2 In the case of a branched chain, it contains at least one of the branched chain minimum structural units, preferably represented by the general formula: a X b )-(X a is H, F, CH3 or CF3; X b is CH3 or CF3. b In the case of CF3, X a These units can further improve the solubility of the electrolyte salt.

[0466] Preferred fluorinated alkyl groups include, for example, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CH2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0467] [Chemistry 40]

[0468]

[0469] [Chemistry 41]

[0470] wait.

[0472] Among them, as Rf 3 and R 14 The fluorinated alkyl groups are preferably CF3-, CF3CF2-, (CF3)2CH-, CF3CH2-, C2F5CH2-, CF3CF2CH2-, HCF2CF2CH2-, CF3CFHCF2CH2-, CFH2-, and CF2H-. From the perspective of high flame retardancy, rate characteristics, and good oxidation resistance, CF3CH2-, CF3CF2CH2-, HCF2CF2CH2-, CFH2-, and CF2H- are more preferred.

[0473] In R 14 In the case of an alkyl group not containing a fluorine atom, it is an alkyl group having 1 to 7 carbon atoms. 14 The number of carbon atoms in the moiety is preferably 1-4, more preferably 1-3.

[0474] Examples of the alkyl group not containing a fluorine atom include CH3-, CH3CH2-, (CH3)2CH-, C3H7-, etc. Among them, CH3- and CH3CH2- are preferred because of their low viscosity and good rate characteristics.

[0475] The fluorine content of the above-mentioned fluorinated linear carbonate is preferably 15% to 70% by mass. If the fluorine content is within the above range, the compatibility with the solvent and the solubility of the salt can be maintained. The above-mentioned fluorine content is more preferably more than 20% by mass, more preferably more than 30% by mass, particularly preferably more than 35% by mass, more preferably less than 60% by mass, and more preferably less than 50% by mass.

[0476] It should be noted that in the present disclosure, the fluorine content is based on the structural formula of the above-mentioned fluorinated chain carbonate.

[0477] {(number of fluorine atoms × 19) / molecular weight of fluorinated chain carbonate} × 100 (%)

[0478] Calculated value.

[0479] As the fluorinated chain carbonate, any of the following compounds is preferred from the viewpoint of low viscosity.

[0480] [Chemistry 42]

[0481]

[0482] As the fluorinated chain carbonate ester, 2,2,2-trifluoroethyl methyl carbonate (F3CH2COC(=O)OCH3) is particularly preferred.

[0483] The above-mentioned fluorinated chain carbonates may be used alone or in combination of two or more in any ratio.

[0484] When the fluorinated chain carbonate is contained, the content of the fluorinated chain carbonate is preferably 10% to 90% by volume, more preferably 40% to 85% by volume, and even more preferably 50% to 80% by volume, based on the solvent.

[0485] The carboxylic acid ester may be a cyclic carboxylic acid ester or a chain carboxylic acid ester.

[0486] The cyclic carboxylic acid ester may be a non-fluorinated cyclic carboxylic acid ester or a fluorinated cyclic carboxylic acid ester.

[0487] Examples of the non-fluorinated cyclic carboxylic acid ester include non-fluorinated saturated cyclic carboxylic acid esters, and non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group having 2 to 4 carbon atoms are preferred.

[0488] Specific examples of the non-fluorinated saturated cyclic carboxylic acid ester having an alkylene group having 2 to 4 carbon atoms include β-propiolactone, γ-butyrolactone, ε-caprolactone, δ-valerolactone, and α-methyl-γ-butyrolactone. Among them, γ-butyrolactone and δ-valerolactone are particularly preferred from the perspective of increasing the degree of lithium ion dissociation and improving load characteristics.

[0489] The above-mentioned non-fluorinated saturated cyclic carboxylic acid esters may be used alone or in combination of two or more in any ratio.

[0490] When the non-fluorinated saturated cyclic carboxylic acid ester is contained, the content of the non-fluorinated saturated cyclic carboxylic acid ester is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, further preferably 1 to 60% by volume, particularly preferably 5 to 40% by volume, based on the solvent.

[0491] The chain carboxylate may be a non-fluorinated chain carboxylate or a fluorinated chain carboxylate. When the solvent contains the chain carboxylate, an increase in resistance of the liquid electrolyte after high-temperature storage can be further suppressed.

[0492] Examples of the non-fluorinated chain carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, tert-butyl propionate, tert-butyl butyrate, sec-butyl propionate, sec-butyl butyrate, n-butyl butyrate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl acetate, methyl ethyl 2-(diethylphosphoryl)acetate, isopropyl propionate, isopropyl acetate, ethyl formate, ethyl 2-propynyl oxalate, isopropyl formate, isopropyl butyrate, isobutyl formate, isobutyl propionate, isobutyl butyrate, isobutyl acetate, and the like.

[0493] Among them, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and ethyl propionate and propyl propionate are particularly preferred.

[0494] The above-mentioned non-fluorinated chain carboxylic acid esters may be used alone or in combination of two or more in any ratio.

[0495] When the non-fluorinated chain carboxylic acid ester is contained, the content of the non-fluorinated chain carboxylic acid ester is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, further preferably 1 to 60% by volume, particularly preferably 5 to 40% by volume, based on the solvent.

[0496] The fluorinated chain carboxylic acid ester is a chain carboxylic acid ester having a fluorine atom. A solvent containing the fluorinated chain carboxylic acid ester can be suitably used even at a high voltage.

[0497] As the fluorinated chain carboxylic acid ester, the following general formula is preferred from the viewpoint of good compatibility with other solvents and oxidation resistance:

[0498] R 31 COOR 32

[0499] (Where R 31 and R 32 are each independently an alkyl group having 1 to 4 carbon atoms and containing or not containing a fluorine atom, R 31 and R 32 At least one of them contains a fluorine atom).

[0500] As R 31 and R 32, examples of non-fluorinated alkyl groups include methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), n-butyl (-CH2CH2CH2CH3), tert-butyl (-C(CH3)3), etc.; -CF3, -CF2H, -CFH2, -CF2CF3, -CF2CF2H, -CF2CFH2, -CH2CF3, -CH2CF2H, -CH2CFH2, -CF2CF2CF3, -CF2CF2CF2H, -CF2CF2CFH2, -CH2CF2CF3, -CH2CF2CF2H, -CH2CF2CFH2, -CH2CH2CF3, -CH2CH2CF2H, -CH2CH2CFH2, -CF(CF3)2, -CF(CF2H)2, -CF(CFH2)2, -CH(CF3)2, -CH(CF2H)2, -CH(CFH2)2, -CF(OCH3)CF3, -CF2CF2CF2CF3, -CF2CF2CF2CF2H, -CF2CF2CF2CFH2, -CH2CF2CF2CF3, -CH2CF2CF2CF2H, -CH2CF2CF2CFH2, -CH2CH2CF2CF3, -CH2CH2CF2CF2H, -CH2CH2CF2CFH2, -CH2CH2CH2CF3, -CH2CH2CH2CF2H, -CH2CH2CH2CFH2, -CF(CF3)CF2CF3, -CF(CF2H)CF2CF3, -CF(CFH2)CF2CF3, -CF(CF3)CF2CF2H, -CF(CF3)CF2CFH2, -CF(CF3)CH2CF3, -CF(CF3)CH2CF2H, -CF(CF3)CH2CFH2, -CH(CF3)CF2CF3, -CH(CF2H)CF2CF3, -CH(CFH2)CF2CF3, -CH(CF3)CF2CF2H, -CH(CF3)CF2CFH2, -CH(CF3)CH2CF3, -CH(CF3)CH2CF2H, -CH(CF3)CH2CFH2, -CF2CF(CF3)CF3, -CF2CF(CF2H)CF3, -CF2CF(CFH2)CF3, -CF2CF(CF3)CF2H, -CF2CF(CF3)CFH2, -CH2CF(CF3)CF3, -CH2CF(CF2H)CF3, -CH2CF(CFH2)CF3, -CH2CF(CF3)CF2H, -CH2CF(CF3)CFH2, -CH2CH(CF3)CF3, -CH2CH(CF2H)CF3, -CH2CH(CFH2)CF3, -CH2CH(CF3)CF2H,-CH2CH(CF3)CFH2, -CF2CH(CF3)CF3, -CF2CH(CF2H)CF3, -CF2CH(CFH2)CF3, -CF2CH(CF3)CF2H, -CF2CH(CF3)CFH2, -C(CF3)3, -C(CF2H)3, -C(CFH2)3 and other fluorinated alkyl groups. Among them, methyl, ethyl, -CF3, -CF2H, -CF2CF3, -CH2CF3, -CH2CF2H, -CH2CFH2, -CH2CH2CF3, -CH2CF2CF3, -CH2CF2CF2H, -CH2CF2CFH2 are particularly preferred from the perspective of good compatibility with other solvents, viscosity and oxidation resistance.

[0501] Specific examples of the fluorinated chain carboxylic acid esters include CF3CH2C(=O)OCH3(3,3,3-trifluoropropionic acid methyl ester), HCF2C(=O)OCH3(difluoroacetic acid methyl ester), HCF2C(=O)OC2H5(difluoroacetic acid ethyl ester), CF3C(=O)OCH2CH2CF3, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H(trifluoroacetic acid 2,2,3,3-tetrafluoropropyl ester), CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, isopropyl trifluorobutyrate, ethyl trifluoroacetate, trifluoroacetate, One or more of tert-butyl fluoroacetate, n-butyl trifluoroacetate, methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3,3-tetrafluoropropyl acetate, CH3C(=O)OCH2CF3 (2,2,2-trifluoroethyl acetate), 1H,1H-heptafluorobutyl acetate, methyl 4,4,4-trifluorobutyrate, ethyl 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropionate, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, butyl 2,2-difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, methyl heptafluorobutyrate, and the like.

[0502] Among them, CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H, CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl pentafluoroisobutyrate, isopropyl trifluorobutyrate, ethyl trifluoroacetate, tert-butyl trifluoroacetate, n-butyl trifluoroacetate, methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3,3-tetrafluoropropyl acetate, CH3C(=O)OCH2CF3, 1H acetate are preferred. ,1H-heptafluorobutyl, methyl 4,4,4-trifluorobutyrate, ethyl 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropyl 3,3,3-trifluoropropionate, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, butyl 2,2-difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, methyl heptafluorobutyrate, more preferably CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CH3C(=O)OCH2CF3, particularly preferably HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CH3C(=O)OCH2CF3.

[0503] The above-mentioned fluorinated chain carboxylic acid esters may be used alone or in combination of two or more in any ratio.

[0504] When the fluorinated chain carboxylic acid ester is contained, the content of the fluorinated chain carboxylic acid ester is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume based on the solvent.

[0505] The above-mentioned solvent preferably comprises at least one selected from the group consisting of the above-mentioned cyclic carbonate, the above-mentioned linear carbonate and the above-mentioned linear carboxylate, more preferably comprises the above-mentioned cyclic carbonate and at least one selected from the group consisting of the above-mentioned linear carbonate and the above-mentioned linear carboxylate. The above-mentioned cyclic carbonate is preferably a saturated cyclic carbonate.

[0506] The liquid electrolyte containing the solvent of the above composition can further improve the high-temperature storage characteristics and cycle characteristics of the electrochemical device.

[0507] Under the situation that above-mentioned solvent comprises above-mentioned cyclic carbonate and at least one in the group consisting of above-mentioned linear carbonate and above-mentioned linear carboxylate, above-mentioned cyclic carbonate and at least one in the group consisting of above-mentioned linear carbonate and above-mentioned linear carboxylate preferably add up to and comprise 10 volume %~100 volume %, more preferably comprise 30 volume %~100 volume, further preferably comprise 50 volume %~100 volume %.

[0508] Under the situation that above-mentioned solvent comprises above-mentioned cyclic carbonate and at least one in the group being composed of above-mentioned linear carbonate and above-mentioned linear carboxylate, as above-mentioned cyclic carbonate and at least one volume ratio being composed of above-mentioned linear carbonate and above-mentioned linear carboxylate, preferably 5 / 95~95 / 5, more preferably more than 10 / 90, further preferably more than 15 / 85, particularly preferably more than 20 / 80, more preferably below 90 / 10, further preferably below 60 / 40, particularly preferably below 50 / 50.

[0509] Above-mentioned solvent also preferably comprises at least one selected from the group consisting of above-mentioned non-fluorinated saturated cyclic carbonate, above-mentioned non-fluorinated chain carbonate and above-mentioned non-fluorinated chain carboxylic acid ester, more preferably comprises at least one selected from the group consisting of above-mentioned non-fluorinated saturated cyclic carbonate and above-mentioned non-fluorinated chain carbonate and above-mentioned non-fluorinated chain carboxylic acid ester.The liquid electrolyte containing the solvent of above-mentioned composition can be suitable for the electrochemical device used at lower voltage.

[0510] Under the situation that above-mentioned solvent comprises above-mentioned non-fluorinated saturated cyclic carbonate and at least one in the group consisting of above-mentioned non-fluorinated chain carbonate and above-mentioned non-fluorinated chain carboxylic ester, above-mentioned non-fluorinated saturated cyclic carbonate and at least one in the group consisting of above-mentioned non-fluorinated chain carbonate and above-mentioned non-fluorinated chain carboxylic ester preferably comprises 5 volume %~100 volume % in total, more preferably comprises 20 volume %~100 volume %, further preferably comprises 30 volume %~100 volume %.

[0511] In the case where the liquid electrolyte comprises the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain carboxylic acid ester, the volume ratio of the non-fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, further preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, further preferably 60 / 40 or less, particularly preferably 50 / 50 or less.

[0512] Above-mentioned solvent also preferably comprises at least one selected from the group consisting of above-mentioned fluorinated saturated cyclic carbonate, above-mentioned fluorinated chain carbonate and above-mentioned fluorinated chain carboxylic acid ester, more preferably comprises at least one selected from the group consisting of above-mentioned fluorinated saturated cyclic carbonate and above-mentioned fluorinated chain carbonate and above-mentioned fluorinated chain carboxylic acid ester.The liquid electrolyte containing the solvent of the above-mentioned composition can not only be suitable for the electrochemical device used at a relatively low voltage, but can also be suitable for the electrochemical device used at a relatively high voltage.

[0513] In the case where the above-mentioned solvent comprises the above-mentioned fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above-mentioned fluorinated chain carbonate and the above-mentioned fluorinated chain carboxylic acid ester, the above-mentioned fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above-mentioned fluorinated chain carbonate and the above-mentioned fluorinated chain carboxylic acid ester preferably comprise 5 volume %~100 volume %, more preferably comprise 10 volume %~100 volume %, further preferably comprise 30 volume %~100 volume %.

[0514] In the case where the solvent comprises at least one of the fluorinated saturated cyclic carbonate and the group consisting of the fluorinated chain carbonate and the fluorinated chain carboxylic acid ester, the volume ratio of the fluorinated saturated cyclic carbonate and the group consisting of the fluorinated chain carbonate and the fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably more than 10 / 90, further preferably more than 15 / 85, particularly preferably more than 20 / 80, more preferably less than 90 / 10, further preferably less than 60 / 40, particularly preferably less than 50 / 50.

[0515] In addition, an ionic liquid may be used as the above-mentioned solvent. The "ionic liquid" refers to a liquid composed of ions composed of a combination of organic cations and anions.

[0516] The organic cation is not particularly limited, and examples thereof include imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0517] There are no particular limitations on the anions that serve as counterions to these organic cations, and for example, PF6 anion, PF3(C2F5)3 anion, PF3(CF3)3 anion, BF4 anion, BF2(CF3)2 anion, BF3(CF3) anion, bisoxalatoborate anion, P(C2O4)F2 anion, Tf(trifluoromethanesulfonyl) anion, Nf(nonafluorobutanesulfonyl) anion, bis(fluorosulfonyl)imide anion, bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, dicyanoamide anion, and halide anion can be used.

[0518] The above solvent is preferably a non-aqueous solvent, and the liquid electrolyte disclosed in the present invention is preferably a non-aqueous liquid electrolyte.

[0519] The content of the solvent in the liquid electrolyte is preferably 70% by mass to 99.999% by mass, more preferably 80% by mass or more, and more preferably 92% by mass or less.

[0520] The liquid electrolyte of the present disclosure may further include a compound (8) represented by the general formula (8).

[0521] General formula (8):

[0522] [Chemistry 43]

[0523]

[0524] (In the formula, A a+ is a metal ion, a hydrogen ion or an onium ion. a is an integer from 1 to 3, b is an integer from 1 to 3, p is b / a, n 203 is an integer from 1 to 4, n 201 is an integer from 0 to 8, n 202 is 0 or 1, Z 201 It is a transition metal, an element of Group III, Group IV or Group V of the periodic table.

[0525] X 201 is O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (the alkylene group, the halogenated alkylene group, the arylene group, and the halogenated arylene group may have a substituent or a heteroatom in their structure. In addition, when n202 is 1 and n203 is 2 to 4, n 203 X 201 They can be bonded separately.)

[0526] L 201 is a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms (the alkylene group, the halogenated alkylene group, the arylene group, and the halogenated arylene group may have a substituent or a heteroatom in their structure. In addition, when n201 is 2 to 8, n201 L 201 can be bonded to form a ring) or -Z 203 Y 203 .Y 201 , Y 202 and Z 203 Each independently is O, S, NY 204 , hydrocarbon group or fluorinated hydrocarbon group. 203 and Y 204Each independently represents H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (the alkyl group, the halogenated alkyl group, the aryl group, and the halogenated aryl group may have a substituent or a heteroatom in the structure thereof, and Y 203 or Y 204 When there are multiple ligands, they may be bonded to form a ring.)

[0527] As A a+ , lithium ion, sodium ion, potassium ion, magnesium ion, calcium ion, barium ion, cesium ion, silver ion, zinc ion, copper ion, cobalt ion, iron ion, nickel ion, manganese ion, titanium ion, lead ion, chromium ion, vanadium ion, ruthenium ion, yttrium ion, lanthanide ion, actinide ion, tetrabutylammonium ion, tetraethylammonium ion, tetramethylammonium ion, triethylmethylammonium ion, triethylammonium ion, pyridinium ion, imidazolium ion, hydrogen ion, tetraethylphosphonium ion, tetramethylphosphonium ion, tetraphenylphosphonium ion, triphenylsulfonium ion, triethylsulfonium ion and the like can be mentioned.

[0528] When used in electrochemical devices, A a+ Lithium ion, sodium ion, magnesium ion, tetraalkylammonium ion, and hydrogen ion are preferred, and lithium ion is particularly preferred. a+ The valence a of the cation is an integer of 1 to 3. When it is greater than 3, the lattice energy becomes large, which causes a problem of difficulty in dissolving in a solvent. Therefore, when solubility is required, it is more preferably 1. The valence b of the anion is also an integer of 1 to 3, and is particularly preferably 1. The constant p representing the ratio of the cation to the anion is necessarily determined by the ratio of the valences b / a of the two.

[0529] Next, the ligand of the general formula (8) will be described. In this specification, Z in the general formula (8) is 201 The bonded organic or inorganic moieties are called ligands.

[0530] Z 201 Preferred are Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf or Sb, more preferred are Al, B or P.

[0531] X 201represents O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene groups and arylene groups may have a substituent or a heteroatom in their structure. Specifically, the alkylene group and the arylene group may be replaced by a halogen atom, a chain or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group, an acyl group, an amide group, or a hydroxyl group as a substituent, and may be a structure in which nitrogen, sulfur, or oxygen is introduced instead of carbon in the alkylene group and the arylene group. In addition, in n 202 is 1 and n 203 When it is 2 to 4, n203 X 201 As an example of this, a ligand such as ethylenediaminetetraacetic acid can be mentioned.

[0532] L 201 represents a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms, or -Z 203 Y 203 (About Z 203 , Y 203 , as described later). The alkyl and aryl groups here are also 201 Similarly, the structure may have a substituent or a heteroatom. When n201 is 2 to 8, n201 L 201 Each of them may be bonded to form a ring. 201 , preferably a fluorine atom or a cyano group. This is because, in the case of a fluorine atom, the solubility and dissociation degree of the salt of the anionic compound are improved, and the ionic conductivity is improved. In addition, the oxidation resistance is improved, thereby suppressing the generation of side reactions.

[0533] Y 201 , Y 202 and Z 203 Each independently represents O, S, NY 204 , hydrocarbon group or fluorinated hydrocarbon group. 201 and Y 202 Preferably O, S or NY 204 , more preferably O. As a feature of compound (8), due to the presence of Y in the same ligand 201 and Y 202 With Z 201 bonds formed, so these ligands and Z 201 The chelate structure is formed. Through the chelate effect, the heat resistance, chemical stability and hydrolysis resistance of the compound are improved. The constant n2O2 in the ligand is 0 or 1, and particularly when it is 0, the chelate ring becomes a five-membered ring, so the chelate effect is most strongly exerted, and the stability is increased, so it is preferred.

[0534] In addition, in this specification, a fluorinated hydrocarbon group is a group in which at least one hydrogen atom of a hydrocarbon group is substituted with a fluorine atom.

[0535] Y 203 and Y 204 Each of them is independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms, wherein these alkyl groups and aryl groups may have a substituent or a heteroatom in their structure. 203 or Y 204 When there are plural groups, they may be bonded to form a ring.

[0536] In addition, the constant n related to the number of ligands mentioned above 203 is an integer of 1 to 4, preferably 1 or 2, and more preferably 2. In addition, the constant n related to the number of the ligands is 201 is an integer of 0 to 8, preferably an integer of 0 to 4, more preferably 0, 2 or 4. 203 When n is 1 201 Preferably 2, in n 203 When n is 2 201 Preferably 0.

[0537] In the general formula (8), the alkyl group, the halogenated alkyl group, the aryl group, and the halogenated aryl group also include groups having other functional groups such as a branched chain, a hydroxyl group, and an ether bond.

[0538] As compound (8), preferably, it is of the general formula:

[0539] [Chemistry 44]

[0540]

[0541] (In the formula, A a+ ,a,b,p,n201,Z 201 and L 201 As described above), or the compound of the general formula:

[0542] [Chemistry 45]

[0543]

[0544] (In the formula, A a+ ,a,b,p,n201,Z 201 and L 201 As described above).

[0545] Examples of compound (8) include lithium oxalate borate salts, and examples thereof include the following formula:

[0546] [Chemistry 46]

[0547]

[0548] The lithium bis(oxalate)borate (LIBOB) shown has the following formula:

[0549] [Chemistry 47]

[0550]

[0551] The lithium difluorooxalatoborate (LIDFOB) shown in the embodiment of the present invention can also be represented by the following formula as compound (8):

[0552] [Chemistry 48]

[0553]

[0554] The lithium difluorooxalate phosphate (LIDFOP) shown in the following formula:

[0555] [Chemistry 49]

[0556]

[0557] The lithium tetrafluorooxalate phosphate (LITFOP) shown in the following formula:

[0558] [Chemistry 50]

[0559]

[0560] As shown in lithium bis(oxalate)difluorophosphate, etc.

[0561] In addition, specific examples of dicarboxylic acid complex salts in which the central element of the complex is boron include lithium bis(malonate)borate, lithium difluoro(malonate)borate, lithium bis(methylmalonate)borate, lithium difluoro(methylmalonate)borate, lithium bis(dimethylmalonate)borate, lithium difluoro(dimethylmalonate)borate, and the like.

[0562] Specific examples of dicarboxylic acid complex salts in which the central element of the complex is phosphorus include lithium tris(oxalate)phosphate, lithium tris(malonate)phosphate, lithium difluorobis(malonate)phosphate, lithium tetrafluoro(malonate)phosphate, lithium tris(methylmalonate)phosphate, lithium difluorobis(methylmalonate)phosphate, lithium tetrafluoro(methylmalonate)phosphate, lithium tris(dimethylmalonate)phosphate, lithium difluorobis(dimethylmalonate)phosphate, lithium tetrafluoro(dimethylmalonate)phosphate, and the like.

[0563] Specific examples of dicarboxylic acid complex salts in which the central element of the complex is aluminum include LiAl(C2O4)2, LiAlF2(C2O4) and the like.

[0564] Among them, lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium tri(oxalate)phosphate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluoro(oxalate)phosphate are more preferably used because they are easily available and can contribute to the formation of a stable film-like structure.

[0565] As the compound (8), lithium bis(oxalate)borate is particularly preferred.

[0566] The content of the compound (8) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and is preferably 10% by mass or less, more preferably 3% by mass or less, based on the solvent, since better cycle characteristics can be obtained.

[0567] The liquid electrolyte disclosed herein preferably further comprises an electrolyte salt (excluding compounds (1) and (8)). As the electrolyte salt, in addition to lithium salts, ammonium salts, and metal salts, any electrolyte salt that can be used for liquid electrolytes, such as liquid salts (ionic liquids), inorganic polymer salts, and organic polymer salts, can be used.

[0568] As the electrolyte salt of the liquid electrolyte for lithium ion secondary batteries, lithium salt is preferred. As the above lithium salt, any lithium salt can be used, and specifically the following substances can be mentioned. For example:

[0569] LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiTaF6, LiWF7, LiAsF6, LiAlCl4, LiI, LiBr, LiCl, LiB 10 Cl 10 , Li2SiF6, Li2PFO3, LiPO2F2 and other inorganic lithium salts;

[0570] Lithium tungstate such as LiWOF5;

[0571] Lithium carboxylates such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li;

[0572] Lithium salts having an S=O group, such as FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li, methyl lithium sulfate, ethyl lithium sulfate (C2H5OSO3Li), and 2,2,2-trifluoroethyl lithium sulfate;

[0573] LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium bis(perfluoroethanesulfonyl imide), lithium cyclic 1,2-perfluoroethanedisulfonyl imide, lithium cyclic 1,3-perfluoropropanedisulfonyl imide, lithium cyclic 1,2-ethanedisulfonyl imide, lithium cyclic 1,3-propanedisulfonyl imide, lithium cyclic 1,4-perfluorobutanedisulfonyl imide, LiN(CF3SO2)(FSO2), LiN(CF3SO2)(C3F7SO2), LiN(CF3SO2)(C4F9SO2), LiN(POF2)2 and other imide lithium salts;

[0574] Methyl lithium salts such as LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3;

[0575] Formula: LiPF a (C n F 2n+1 ) 6-a (wherein a is an integer from 0 to 5, and n is an integer from 1 to 6) (for example, LiPF3(C2F5)3, LiPF3(CF3)3, LiPF3(iso-C3F7)3, LiPF5(iso-C3F7), LiPF4(CF3)2, LiPF4(C2F5)2), LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, LiBF2(C2F5SO2)2, etc., fluorine-containing organic lithium salts, LiSCN, LiB(CN)4, LiB(C6H5)4, Li2(C2O4), LiP(C2O4), Li2B 12 F b H 12-b (b is an integer from 0 to 3), etc.

[0576] Among them, from the perspective of improving output characteristics, high-rate charge and discharge characteristics, high-temperature storage characteristics, cycle characteristics, etc., LiPF6, LiBF4, LiSbF6, LiTaF6, LiPO2F2, FSO3Li, CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethanedisulfonyl imide lithium, cyclic 1,3-perfluoropropanedisulfonyl imide lithium, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, etc. are particularly preferred, and at least one lithium salt selected from the group consisting of LiPF6, LiN(FSO2)2 and LiBF4 is most preferred.

[0577] These electrolyte salts can be used alone or in combination of two or more. A preferred example of using two or more is the combination of LiPF6 and LiBF4, the combination of LiPF6 and LiPO2F2, C2H5OSO3Li or FSO3Li, which has the effect of improving high temperature storage characteristics, load characteristics and cycle characteristics.

[0578] In this case, the mixing amount of LiBF4, LiPO2F2, C2H5OSO3Li or FSO3Li relative to 100 mass % of the entire liquid electrolyte is not limited, and is arbitrary as long as it does not significantly impair the effects of the present disclosure. It is usually 0.01 mass % or more, preferably 0.1 mass % or more, and usually 30 mass % or less, preferably 20 mass % or less, more preferably 10 mass % or less, and further preferably 5 mass % or less, relative to the liquid electrolyte of the present disclosure.

[0579] In addition, another example is the use of inorganic lithium salts and organic lithium salts, and the combination of the two has the effect of suppressing the deterioration caused by high temperature storage. As an organic lithium salt, preferably CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethane disulfonyl imide lithium, cyclic 1,3-perfluoropropane disulfonyl imide lithium, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, etc. In this case, the ratio of the organic lithium salt relative to the overall 100% by mass of the liquid electrolyte is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and preferably 30% by mass or less, particularly preferably 20% by mass or less.

[0580] As long as the effect of the present disclosure is not impaired, the concentration of these electrolyte salts in the liquid electrolyte is not particularly limited. From the perspective of making the conductivity of the liquid electrolyte a good range and ensuring good battery performance, the total molar concentration of lithium in the liquid electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, and further preferably 0.5 mol / L or more, and preferably 4.0 mol / L or less, more preferably 3.8 mol / L or less, and further preferably 3.5 mol / L or less.

[0581] If the total molar concentration of lithium is too low, the conductivity of the liquid electrolyte may be insufficient. On the other hand, if the concentration is too high, the viscosity increases, so the conductivity may decrease, and the battery performance may decrease.

[0582] As the electrolyte salt of the liquid electrolyte for the electric double layer capacitor, an ammonium salt is preferred.

[0583] Examples of the ammonium salt include the following (IIa) to (IIe).

[0584] (IIa) Tetraalkyl quaternary ammonium salt

[0585] Preferred examples include tetraalkyl quaternary ammonium salts represented by general formula (IIa).

[0586] [Chemistry 51]

[0587]

[0588] (Where R 1a , R 2a , R 3a and R 4a are the same or different, and are all alkyl groups having 1 to 6 carbon atoms and containing or not containing an ether bond; X - is an anion.)

[0589] In addition, from the viewpoint of improving oxidation resistance, an ammonium salt in which a part or all of the hydrogen atoms of the ammonium salt are substituted with fluorine atoms and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms is also preferred.

[0590] As a specific example, the general formula (IIa-1) can be cited:

[0591] [Chemistry 52]

[0592]

[0593] (Where R 1a , R 2a and X - Same as above; x and y are the same or different, and are integers from 0 to 4, and x+y=4)

[0594] The tetraalkyl quaternary ammonium salt shown, general formula (IIa-2):

[0595] [Chemistry 53]

[0596]

[0597] (Where R 5a is an alkyl group having 1 to 6 carbon atoms; R 6a is a divalent hydrocarbon group having 1 to 6 carbon atoms; R 7a is an alkyl group having 1 to 4 carbon atoms; z is 1 or 2; X - for anions)

[0598] The trialkylammonium salts containing an alkyl ether group shown above, etc.

[0599] By introducing an alkyl ether group, it is possible to reduce the viscosity.

[0600] Anion X - It can be an inorganic anion or an organic anion. Examples of inorganic anions include AlCl4 - 、BF4 - PF6 - 、AsF6 - 、TaF6 - ,I - 、SbF6 - Examples of organic anions include bisoxalatoborate anion, difluorooxalatoborate anion, tetrafluorooxalatophosphate anion, difluorobisoxalatophosphate anion, CF3COO - CF3SO3 - 、(CF3SO2)2N - 、(C2F5SO2)2N - wait.

[0601] Among these, BF4 is preferred from the viewpoint of good oxidation resistance and ion dissociation. - PF6 - 、AsF6 - 、SbF6 - .

[0602] As preferred specific examples of tetraalkylammonium salts, Et4NBF4, Et4NClO4, Et4NPF6, Et4NAsF6, Et4NSbF6, Et4NCF3SO3, Et4N(CF3SO2)2N, Et4NC4F9SO3, Et3MeNBF4, Et3MeNClO4, Et3MeNPF6, Et3MeNAsF6, Et3MeNSbF6, Et3MeNCF3SO3, Et3MeN(CF3SO2)2N, and Et3MeNC4F9SO3 can be used. In particular, Et4NBF4, Et4NPF6, Et4NSbF6, Et4NAsF6, Et3MeNBF4, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium salt, etc. can be mentioned.

[0603] (IIb) Spirocyclic Bispyrrolidinium Salt

[0604] Preferred examples include general formula (IIb-1):

[0605] [Chemistry 54]

[0606]

[0607] (Where R 8a and R 9a are the same or different and are all alkyl groups with 1 to 4 carbon atoms; - is an anion; n1 is an integer from 0 to 5; n2 is an integer from 0 to 5)

[0608] The spirocyclic bispyrrolidinium salt shown has the general formula (IIb-2):

[0609] [Chemistry 55]

[0610]

[0611] (Where R 10a and R 11a are the same or different and are all alkyl groups with 1 to 4 carbon atoms; - is an anion; n3 is an integer from 0 to 5; n4 is an integer from 0 to 5)

[0612] The spirocyclic bipyrrolidinium salt shown, or general formula (IIb-3):

[0613] [Chemistry 56]

[0614]

[0615] (Where R 12a and R 13a are the same or different and are all alkyl groups with 1 to 4 carbon atoms; -is an anion; n5 is an integer from 0 to 5; n6 is an integer from 0 to 5)

[0616] In addition, the spirobispyrrolidinium salt in which a part or all of the hydrogen atoms are substituted with fluorine atoms and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms is also preferred from the viewpoint of improving oxidation resistance.

[0617] Anion X - Preferred specific examples are the same as those of (IIa). Among them, BF4-, PF6-, (CF3SO2)2N- or (C2F5SO2)2N- are preferred from the perspective of high dissociation and low internal resistance at high voltage.

[0618] Preferred specific examples of the spirocyclic bispyrrolidinium salt include, for example

[0619] [Chemistry 57]

[0620] wait.

[0621] The spirobispyrrolidinium salt is excellent in solubility in solvents, oxidation resistance, and ion conductivity.

[0622] (IIc) Imidazolium salt

[0623] Preferred examples include imidazolium salts represented by general formula (IIc).

[0624] [Chemistry 58]

[0625]

[0626] (Where R 14a and R 15a are the same or different and are all alkyl groups with 1 to 6 carbon atoms; - is an anion.)

[0627] Furthermore, those in which a part or all of the hydrogen atoms of the imidazolium salt are substituted with fluorine atoms and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms are preferred from the viewpoint of improving oxidation resistance.

[0628] Anion X - Preferred specific examples are the same as those for (IIa).

[0629] As a preferred specific example, there can be mentioned, for example

[0630] [Chemistry 59]

[0631] wait.

[0632] This imidazolium salt is excellent in that it has low viscosity and good solubility.

[0633] (IId): N-alkylpyridinium salt

[0634] Preferred examples include N-alkylpyridinium salts represented by general formula (IId).

[0635] [Chemistry 60]

[0636]

[0637] (Where R 16a is an alkyl group having 1 to 6 carbon atoms; - is an anion.)

[0638] Furthermore, N-alkylpyridinium salts in which a part or all of hydrogen atoms are substituted with fluorine atoms and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms are preferred from the viewpoint of improving oxidation resistance.

[0639] Anion X - Preferred specific examples are the same as those for (IIa).

[0640] As a preferred specific example, there can be mentioned, for example

[0641] [Chemistry 61]

[0642] wait.

[0643] This N-alkylpyridinium salt is excellent in that it has low viscosity and good solubility.

[0644] (IIe) N,N-Dialkylpyrrolidinium salt

[0645] Preferred examples include N,N-dialkylpyrrolidinium salts represented by the general formula (IIe).

[0646] [Chemistry 62]

[0647]

[0648] (Where R 17a and R 18a are the same or different and are all alkyl groups with 1 to 6 carbon atoms; - is an anion.)

[0649] Furthermore, N,N-dialkylpyrrolidinium salts in which a part or all of hydrogen atoms are substituted with fluorine atoms and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms are preferred from the viewpoint of improving oxidation resistance.

[0650] Anion X - Preferred specific examples are the same as those for (IIa).

[0651] As a preferred specific example, there can be mentioned, for example

[0652] [Chemistry 63]

[0653]

[0654] [Chemistry 64] wait.

[0655] This N,N-dialkylpyrrolidinium salt is excellent in that it has low viscosity and good solubility.

[0656] Among these ammonium salts, (IIa), (IIb) and (IIc) are preferred from the viewpoint of good solubility, oxidation resistance and ion conductivity, and (IIa) and (IIb) are more preferred.

[0657] [Chemistry 65]

[0658]

[0659] (wherein, Me is methyl; Et is ethyl; X - , x, y are the same as in formula (IIa-1)).

[0660] In addition, as the electrolyte salt for the electric double layer capacitor, a lithium salt can be used. As the lithium salt, for example, LiPF6, LiBF4, LiN(FSO2)2, LiAsF6, LiSbF6, LiN(SO2C2H5)2 are preferred.

[0661] In order to further increase the capacity, magnesium salts may be used, such as Mg(ClO4)2, Mg(OOC2H5)2, etc.

[0662] When the electrolyte salt is the above-mentioned ammonium salt, the concentration is preferably 0.7 mol / L or more. If it is less than 0.7 mol / L, there is a possibility that not only the low temperature characteristics will deteriorate, but also the initial internal resistance will increase. The concentration of the above-mentioned electrolyte salt is more preferably 0.9 mol / L or more.

[0663] The upper limit of the concentration is preferably 2.0 mol / L or less, more preferably 1.5 mol / L or less, in terms of low-temperature characteristics.

[0664] When the ammonium salt is triethylmethylammonium tetrafluoroborate (TEMABF4), the concentration thereof is preferably 0.7 mol / L to 1.5 mol / L from the viewpoint of excellent low-temperature characteristics.

[0665] In the case of spirobipyrrolidinium tetrafluoroborate (SBPBF4), the concentration is preferably 0.7 mol / L to 2.0 mol / L.

[0666] The liquid electrolyte disclosed herein preferably further comprises a compound (2) represented by the general formula (2).

[0667] [Chemistry 66]

[0668]

[0669] (Where X 21 is a group containing at least H or C, n21 is an integer from 1 to 3, Y 21 and Z 21 are the same or different, and are groups containing at least H, C, O or F, n22 is 0 or 1, and Y 21 and Z 21 They can bond to each other to form a ring.)

[0670] When the liquid electrolyte contains the compound (2), even when stored at high temperatures, the capacity retention rate is unlikely to further decrease, and the amount of gas generated is unlikely to further increase.

[0671] When n21 is 2 or 3, 2 or 3 X 21 Can be the same or different.

[0672] Y 21 and Z 21 If there are multiple Y 21 and Z 21 Can be the same or different.

[0673] As X 21 , preferably -CY 21 Z 21 -(where Y 21 and Z 21 as above) or -CY 21 =CZ 21 -(where Y 21 and Z 21 As described above).

[0674] As Y 21 , preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0675] As Z 21 , preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0676] Or, Y 21 and Z 21They may be bonded to each other to form a carbocyclic or heterocyclic ring which may or may not contain an unsaturated bond and may or may not have aromaticity. The number of carbon atoms in the ring is preferably 3 to 20.

[0677] Next, a specific example of compound (2) is described. It should be noted that, in the following examples, "analogues" refer to acid anhydrides obtained by replacing a part of the structure of the exemplified acid anhydride with other structures within the scope of the present disclosure, for example, dimers, trimers and tetramers composed of multiple acid anhydrides, or isomers with the same number of carbon atoms in the substituent but with branched chains, substances in which the substituent is bonded to the acid anhydride at different positions, etc.

[0678] Specific examples of the acid anhydride forming a five-membered ring structure include succinic anhydride, methylsuccinic anhydride (4-methylsuccinic anhydride), dimethylsuccinic anhydride (4,4-dimethylsuccinic anhydride, 4,5-dimethylsuccinic anhydride, etc.), 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4,5-divinylsuccinic anhydride, phenylsuccinic anhydride (4-phenylsuccinic anhydride ... 5-diphenylsuccinic anhydride, 4,4-diphenylsuccinic anhydride, citraconic anhydride, maleic anhydride, methylmaleic anhydride (4-methylmaleic anhydride), 4,5-dimethylmaleic anhydride, phenylmaleic anhydride (4-phenylmaleic anhydride), 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, 5,5-dimethylitaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, and the like, and the like.

[0679] Specific examples of the acid anhydride having a six-membered ring structure include cyclohexanedicarboxylic anhydride (cyclohexane-1,2-dicarboxylic anhydride, etc.), 4-cyclohexene-1,2-dicarboxylic anhydride, glutaric anhydride, glutaconic anhydride, 2-phenylglutaric anhydride, and analogs thereof.

[0680] Specific examples of the acid anhydride having another ring structure include 5-norbornene-2,3-dicarboxylic anhydride, cyclopentanetetracarboxylic anhydride, pyromellitic anhydride, diglycolic anhydride, and analogs thereof.

[0681] Specific examples of the acid anhydride that forms a ring structure and is substituted with a halogen atom include monofluorosuccinic anhydride (such as 4-fluorosuccinic anhydride), 4,4-difluorosuccinic anhydride, 4,5-difluorosuccinic anhydride, 4,4,5-trifluorosuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride (4,4,5,5-tetrafluorosuccinic anhydride), 4-fluoromaleic anhydride, 4,5-difluoromaleic anhydride, trifluoromethylmaleic anhydride, 5-fluoroitaconic anhydride, 5,5-difluoroitaconic anhydride, and analogs thereof.

[0682] Among them, preferred examples of compound (2) include glutaric anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, phenylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, dimethylsuccinic anhydride, trifluoromethylsuccinic anhydride, monofluorosuccinic anhydride, and tetrafluorosuccinic anhydride; more preferred examples include maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, trifluoromethylsuccinic anhydride, and tetrafluorosuccinic anhydride; and even more preferred examples include maleic anhydride and succinic anhydride.

[0683] Compound (2) is preferably selected from the group consisting of general formula (3):

[0684] [Chemistry 67]

[0685]

[0686] (Where X 31 ~X 34 The compounds (3) and the general formula (4) are the same or different and are groups containing at least H, C, O or F:

[0687] [Chemistry 68]

[0688]

[0689] (Where X 41 and X 42 The compounds (4) are at least one of the groups consisting of the compounds (4) represented by the groups (a) and (b) that are the same or different and contain at least H, C, O or F.

[0690] As X 31 ~X 34 , which are the same or different, are preferably at least one selected from the group consisting of an alkyl group, a fluorinated alkyl group, an alkenyl group and a fluorinated alkenyl group.

[0691] X 31 ~X 34 The number of carbon atoms in the moiety is preferably 1-10, more preferably 1-3.

[0692] As X 31 ~X 34 , the same or different, more preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0693] As X41 and X 42 , which are the same or different, are preferably at least one selected from the group consisting of an alkyl group, a fluorinated alkyl group, an alkenyl group and a fluorinated alkenyl group. 41 and X 42 The number of carbon atoms in is preferably 1-10, more preferably 1-3.

[0694] As X 41 and X 42 , the same or different, more preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0695] The compound (3) is preferably any one of the following compounds.

[0696] [Chemistry 69]

[0697]

[0698] The compound (4) is preferably any one of the following compounds.

[0699] [Chemistry 70]

[0700]

[0701] The liquid electrolyte is not likely to decrease in capacity retention and increase in gas generation even when stored at high temperatures, and therefore preferably contains 0.0001% to 15% by mass of compound (2) relative to the liquid electrolyte. The content of compound (2) is more preferably 0.01% to 10% by mass, further preferably 0.1% to 3% by mass, and particularly preferably 0.1% to 1.0% by mass.

[0702] In the case where the liquid electrolyte contains both compounds (3) and (4), the capacity retention rate is unlikely to decrease and the gas generation amount is unlikely to increase even when stored at high temperatures. Therefore, the liquid electrolyte preferably contains 0.08% to 2.50% by mass of the compound (3) and 0.02% to 1.50% by mass of the compound (4) relative to the liquid electrolyte, and more preferably contains 0.80% to 2.50% by mass of the compound (3) and 0.08% to 1.50% by mass of the compound (4).

[0703] The liquid electrolyte disclosed herein may contain at least one selected from the group consisting of nitrile compounds represented by the following general formulae (1a), (1b), and (1c).

[0704] [Chemistry 71]

[0705]

[0706] (Where R a and R b Each independently represents a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted by a halogen atom. n represents an integer of 1 to 10.

[0707] [Chemistry 72]

[0708]

[0709] (Where R c represents a hydrogen atom, a halogen atom, an alkyl group, a group in which at least a part of the hydrogen atoms of the alkyl group is substituted with a halogen atom, or a group consisting of NC-R c1 -X c1 -(R c1 represents an alkylene group, X c1 represents an oxygen atom or a sulfur atom). d and R e Each independently represents a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted by a halogen atom. m represents an integer of 1 to 10.

[0710] [Chemistry 73]

[0711]

[0712] (Where R f , R g , R h and R i Each independently represents a group containing a cyano group (CN), a hydrogen atom (H), a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of the alkyl group is substituted with a halogen atom. f , R g , R h and R i At least one of the groups is a group containing a cyano group. l represents an integer of 1 to 3.)

[0713] This can improve the high temperature storage characteristics of the electrochemical device. The above-mentioned nitrile compounds may be used alone or in any combination and ratio.

[0714] In the above general formula (1a), R a and R b Each is independently a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of the alkyl group are substituted with halogen atoms.

[0715] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, among which a fluorine atom is preferred.

[0716] The alkyl group is preferably an alkyl group having 1 to 5 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group.

[0717] Examples of the group in which at least a part of the hydrogen atoms of the alkyl group are substituted with halogen atoms include a group in which at least a part of the hydrogen atoms of the above-mentioned alkyl group are substituted with the above-mentioned halogen atoms. a and R b In the case of an alkyl group or a group in which at least a part of the hydrogen atoms of the alkyl group are substituted with halogen atoms, R a and R b They may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0718] R a and R b A hydrogen atom or an alkyl group is preferred.

[0719] In the above general formula (1a), n is an integer of 1 to 10. When n is 2 or more, n R a They can be all the same or at least partly different. b n is preferably an integer of 1-7, more preferably an integer of 2-5.

[0720] As the nitrile compound represented by the general formula (1a), dinitriles and trinitriles are preferred.

[0721] Specific examples of dinitriles include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, octanonitrile, azelaic acid, sebacononitrile, undecane dicarbonitrile, dodecane dicarbonitrile, methyl malononitrile, ethyl malononitrile, isopropyl malononitrile, tert-butyl malononitrile, methyl succinonitrile, 2,2-dimethyl succinonitrile, 2,3-dimethyl succinonitrile, 2,3,3-trimethyl succinonitrile, 2,2,3,3-tetramethyl succinonitrile, 2,3-diethyl-2,3-dimethyl succinonitrile, 2,2-diethyl-3,3-dimethyl succinonitrile, dicyclohexane-1,1-dicarbonitrile, dicyclohexane-2,2-dicarbonitrile, dicyclohexane-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexane dicarbonitrile, 2,3-diisobutyl-2,3-dimethyl succinonitrile, 2,2 ... Butyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyano octane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3,3'-(ethylenedisulfide)dipropionitrile, 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, butyronitrile, phthalonitrile, etc. Among these, succinonitrile, glutaronitrile, and adiponitrile are particularly preferred.

[0722] Specific examples of the trinitriles include pentaerythritol, propane tricarbonitrile, 1,3,5-hexane tricarbonitrile, 1,3,6-hexane tricarbonitrile, heptane tricarbonitrile, 1,2,3-propane tricarbonitrile, 1,3,5-pentane tricarbonitrile, cyclohexane tricarbonitrile, tricyanoethylamine, tricyanoethoxypropane, tricyanoethylene, tris(2-cyanoethyl)amine, and the like. Particularly preferred are 1,3,6-hexane tricarbonitrile and cyclohexane tricarbonitrile, and most preferred is cyclohexane tricarbonitrile.

[0723] In the above general formula (1b), R c represents a hydrogen atom, a halogen atom, an alkyl group, a group in which at least a part of the hydrogen atoms of the alkyl group are substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 represents an alkylene group, X c1 represents an oxygen atom or a sulfur atom), R d and R e Each is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted with a halogen atom.

[0724] Examples of the halogen atom, the alkyl group, and the group in which at least a part of hydrogen atoms in the alkyl group is substituted with a halogen atom include the groups exemplified for the above general formula (1a).

[0725] The above NC-R c1 -X c1 -R in c1 The alkylene group is preferably an alkylene group having 1 to 3 carbon atoms.

[0726] R c , R d and R e Each of R is independently preferably a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted with a halogen atom. c , R d and R e At least one of them is preferably a halogen atom or a group in which at least a part of the hydrogen atoms of the alkyl group are substituted with a halogen atom, and more preferably a fluorine atom or a group in which at least a part of the hydrogen atoms of the alkyl group are substituted with a fluorine atom. d and R e In the case of an alkyl group or a group in which at least a part of the hydrogen atoms of the alkyl group are substituted with halogen atoms, R d and R e They may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0727] In the above general formula (1b), m is an integer of 1 to 10. When m is 2 or more, m R d They can be all the same or at least partly different. e m is preferably an integer of 2-7, more preferably an integer of 2-5.

[0728] Examples of the nitrile compound represented by the general formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanecarbonitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, pentafluoropropionitrile, methoxyacetonitrile, and benzonitrile. Among them, 3,3,3-trifluoropropionitrile is particularly preferred.

[0729] In the above general formula (1c), R f , R g , R h and R iEach is independently a group containing a cyano group (CN), a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group are substituted with a halogen atom.

[0730] As for the halogen atom, the alkyl group, and the group in which at least a part of the hydrogen atoms of the alkyl group are substituted by the halogen atom, the groups exemplified for the above general formula (1a) can be cited. As the group containing a cyano group, in addition to the cyano group, a group in which at least a part of the hydrogen atoms in the alkyl group are substituted by the cyano group can be cited. As the alkyl group in this case, the groups exemplified for the above general formula (1a) can be cited.

[0731] R f , R g , R h and R i At least one of R is a group containing a cyano group. f , R g , R h and R i At least two of them are groups containing a cyano group, and more preferably R h and R i is a group containing a cyano group. h and R i In the case of a group containing a cyano group, R f and R g Preferred is a hydrogen atom.

[0732] In the above general formula (1c), l is an integer of 1 to 3. When l is 2 or more, one R f They can be all the same or at least partly different. g l is preferably an integer of 1 to 2.

[0733] Examples of the nitrile compound represented by the general formula (1c) include 3-hexenedinitrile, malononitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, and 2-hexenenitrile. Preferred are 3-hexenedinitrile and malononitrile, and particularly preferred is 3-hexenedinitrile.

[0734] The content of the nitrile compound is preferably 0.2% to 7% by mass relative to the liquid electrolyte. Thus, the high-temperature storage characteristics and safety of the electrochemical device under high voltage can be further improved. The lower limit of the total content of the nitrile compound is more preferably 0.3% by mass, more preferably 0.5% by mass. The upper limit is more preferably 5% by mass, more preferably 2% by mass, and particularly preferably 0.5% by mass.

[0735] The liquid electrolyte of the present disclosure may include a compound having an isocyanate group (hereinafter sometimes referred to as "isocyanate"). The isocyanate is not particularly limited, and any isocyanate can be used. Examples of isocyanates include monoisocyanates, diisocyanates, triisocyanates, and the like.

[0736] Specific examples of the monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, isocyanatocyclohexane, methoxycarbonyl isocyanate, ethoxycarbonyl isocyanate, propoxycarbonyl isocyanate, butoxycarbonyl isocyanate, methoxysulfonyl isocyanate, ethoxysulfonyl isocyanate, propoxysulfonyl isocyanate, butoxysulfonyl isocyanate, fluorosulfonyl isocyanate, methyl isocyanate, butyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, and ethyl isocyanate.

[0737] Specific examples of diisocyanates include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropylene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, toluene diisocyanate, 1,2-bis(isocyanate) 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate diisocyanate, isophorone diisocyanate, bicyclo[2.2.1]heptane-2,5-diylbis(methyl=isocyanate), bicyclo[2.2.1]heptane-2,6-diylbis(methyl=isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, octamethylene diisocyanate, tetramethylene diisocyanate, and the like.

[0738] Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-triisocyanatomethylbenzene, 1,3,5-tris(6-isocyanatohexane-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 4-(isocyanatomethyl)octamethylene diisocyanate.

[0739] Among them, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohexane-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,4,4-trimethylhexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate are easily available industrially and can suppress the manufacturing cost of liquid electrolytes to a low level. From this aspect, they are preferred. In addition, from a technical point of view, they can also help to form a stable film-like structure and are more preferably used.

[0740] The content of isocyanate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged, it is arbitrary, relative to the liquid electrolyte, preferably 0.001 mass % or more and 1.0 mass % or less. If the content of isocyanate is above the lower limit, it is possible to bring sufficient cycle characteristics improvement effect to the non-aqueous liquid electrolyte secondary battery. In addition, if below the upper limit, the initial resistance increase of the non-aqueous liquid electrolyte secondary battery can be avoided. The content of isocyanate is more preferably 0.01 mass % or more, more preferably 0.1 mass % or more, particularly preferably 0.2 mass % or more, and more preferably 0.8 mass % or less, more preferably 0.7 mass % or less, particularly preferably 0.6 mass % or less.

[0741] The liquid electrolyte disclosed herein may include a cyclic sulfonic acid ester. The cyclic sulfonic acid ester is not particularly limited, and any cyclic sulfonic acid ester may be used. Examples of the cyclic sulfonic acid ester include saturated cyclic sulfonic acid esters, unsaturated cyclic sulfonic acid esters, saturated cyclic disulfonic acid esters, and unsaturated cyclic disulfonic acid esters.

[0742] Specific examples of the saturated cyclic sulfonic acid esters include 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone, 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1,3-butane sultone, 1,4-butane sultone, Sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone, 2,4-butane sultone, etc.

[0743] Specific examples of the unsaturated cyclic sulfonic acid esters include 1-propylene-1,3-sultone, 2-propylene-1,3-sultone, 1-fluoro-1-propylene-1,3-sultone, 2-fluoro-1-propylene-1,3-sultone, 3-fluoro-1-propylene-1,3-sultone, 1-fluoro-2-propylene-1,3-sultone, 2-fluoro-2-propylene-1,3-sultone, 3-fluoro-2-propylene-1,3-sultone, 1-methyl-1-propylene-1,3-sultone, 2-methyl-1-propylene-1,3-sultone, Esters, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-Fluoro-2-butene-1,4-sultone, 2-Fluoro-2-butene-1,4-sultone, 3-Fluoro-2-butene-1,4-sultone, 4-Fluoro-2-butene-1,4-sultone, 1,3-Propene sultone, 1-Fluoro-3-butene-1,4-sultone, 2-Fluoro-3-butene-1,4-sultone, 3-Fluoro-3-butene-1,4-sultone, 4-Fluoro-3-butene-1,4-sultone, 1-Methyl-1-butene-1,4-sultone, 2-Methyl-1-butene-1,4-sultone , 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone, 1-methyl-2-butene-1,4-sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3-butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, 4-methyl-3-butene-1,4-sultone, etc.

[0744] Among them, from the aspect of being easy to obtain and being able to contribute to the formation of a stable film-like structure, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, and 1-propylene-1,3-sultone are more preferably used. The content of the cyclic sulfonic acid ester is not particularly limited, and is arbitrary as long as it does not significantly impair the effect of the present disclosure, and is preferably 0.001 mass % or more and 3.0 mass % or less relative to the liquid electrolyte.

[0745] If the content of the cyclic sulfonic acid ester is above the lower limit, the non-aqueous liquid electrolyte secondary battery can be provided with a sufficient cycle characteristic improvement effect. In addition, if it is below the upper limit, the increase in the manufacturing cost of the non-aqueous liquid electrolyte secondary battery can be avoided. The content of the cyclic sulfonic acid ester is more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and more preferably 2.5% by mass or less, further preferably 2.0% by mass or less, particularly preferably 1.8% by mass or less.

[0746] The liquid electrolyte of the present disclosure may further contain polyethylene oxide having a weight average molecular weight of 2,000 to 40,000 and having -OH, -OCOOH or -COOH at the terminal.

[0747] By including such a compound, the stability of the electrode interface is improved, and the characteristics of the electrochemical device can be improved.

[0748] As the above-mentioned polyethylene oxide, for example, polyethylene oxide monoalcohol, polyethylene oxide carboxylic acid, polyethylene oxide glycol, polyethylene oxide dicarboxylic acid, polyethylene oxide triol, polyethylene oxide tricarboxylic acid, etc. can be cited. They can be used alone or in combination of two or more. Among them, in terms of making the characteristics of the electrochemical device better, a mixture of polyethylene oxide monoalcohol and polyethylene oxide glycol, and a mixture of polyvinyl carboxylic acid and polyethylene dicarboxylic acid are preferred.

[0749] If the weight average molecular weight of the polyethylene oxide is too small, it may be easily oxidatively decomposed. The weight average molecular weight is more preferably 3000 to 40000. The weight average molecular weight can be measured by polystyrene conversion using gel permeation chromatography (GPC).

[0750] The content of the polyethylene oxide in the liquid electrolyte is preferably 1×10 -6 mol / kg~1×10 -2 If the content of the polyethylene oxide is too high, the characteristics of the electrochemical device may be impaired.

[0751] The content of the polyethylene oxide is more preferably 5×10 -6 mol / kg or more.

[0752] The liquid electrolyte disclosed in the present invention may further contain a fluorinated saturated cyclic carbonate, an unsaturated cyclic carbonate, an overcharge inhibitor, other known auxiliary agents, etc. as additives, thereby suppressing the degradation of the characteristics of the electrochemical device.

[0753] As fluorinated saturated cyclic carbonate, compounds represented by the above general formula (A) can be cited. Among them, fluoroethylene carbonate, difluoroethylene carbonate, monofluoromethylethylene carbonate, trifluoromethylethylene carbonate, 2,2,3,3,3-pentafluoropropylethylene carbonate (4-(2,2,3,3,3-pentafluoro-propyl)-[1,3]dioxolane-2-one) are preferred. Fluorinated saturated cyclic carbonate can be used alone or in any combination and ratio.

[0754] The content of the fluorinated saturated cyclic carbonate is preferably 0.001% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass, and even more preferably 0.1% by mass to 3% by mass, based on the liquid electrolyte.

[0755] Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, ethylene carbonates, allyl carbonates, and catechol carbonates.

[0756] Examples of 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-fluorovinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluorovinylene carbonate, ethynyl ethylene carbonate, propargyl ethylene carbonate, methyl vinylene carbonate, and dimethyl vinylene carbonate.

[0757] Specific examples of ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene 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-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-methylene-1,3-dioxolane-2-one, 4,5-dimethylene-1,3-dioxolane-2-one, 4-methyl-5-allylethylene carbonate, and the like.

[0758] Wherein, as unsaturated cyclic carbonate, preferably 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-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate.In addition, vinylene carbonate, vinyl ethylene carbonate, ethynyl ethylene carbonate can form a more stable interface protection film, so it is particularly preferred, and vinylene carbonate is most preferably used.

[0759] The molecular weight of unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged. The molecular weight is preferably more than 50 and less than 250. If it is the scope, it is easy to ensure that the unsaturated cyclic carbonate is for the solubility of liquid electrolyte, and it is easy to fully show the effect of the present disclosure. The molecular weight of unsaturated cyclic carbonate is more preferably more than 80, and in addition, it is more preferably less than 150.

[0760] The method for producing the unsaturated cyclic carbonate is not particularly limited, and the unsaturated cyclic carbonate can be produced by any known method.

[0761] The unsaturated cyclic carbonate may be used alone or in combination of two or more in any ratio.

[0762] The content of the above-mentioned unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged, it is arbitrary. The content of the above-mentioned unsaturated cyclic carbonate is preferably more than 0.001 mass %, more preferably more than 0.01 mass %, and more preferably more than 0.1 mass % in 100 mass % of liquid electrolyte. In addition, the above-mentioned content is preferably less than 5 mass %, more preferably less than 4 mass %, and more preferably less than 3 mass %. If it is within the above-mentioned range, the electrochemical device using the liquid electrolyte is easy to show sufficient cycle characteristics to improve the effect, in addition, it is easy to avoid the situation that the high temperature storage characteristics are reduced, the gas generation amount becomes more, and the discharge capacity retention rate reduces.

[0763] As the unsaturated cyclic carbonate, in addition to the above-mentioned non-fluorinated unsaturated cyclic carbonate, a fluorinated unsaturated cyclic carbonate can also be preferably used.

[0764] The fluorinated unsaturated cyclic carbonate is a cyclic carbonate with unsaturated bonds and fluorine atoms. As long as the number of fluorine atoms possessed by the fluorinated unsaturated cyclic carbonate is more than 1, there is no particular restriction. Wherein, the fluorine atoms are usually below 6, preferably below 4, most preferably 1 or 2.

[0765] Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives and fluorinated ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon double bond.

[0766] Examples of the fluorinated vinylene carbonate derivatives include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, and 4-fluoro-5-vinylvinylene carbonate.

[0767] Examples of the fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5- Difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, and the like.

[0768] Among them, as the fluorinated unsaturated cyclic carbonate, 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, and 4,5-difluoro-4,5-diallylethylene carbonate are more preferably used because they form a stable interface protective film.

[0769] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged. The molecular weight is preferably more than 50, and is additionally less than 500. If it is within this range, it is easy to ensure the solubility of the fluorinated unsaturated cyclic carbonate for the liquid electrolyte.

[0770] The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and any known method may be selected for production. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

[0771] Fluorinated unsaturated cyclic carbonate can be used alone as one, or two or more can be used in any combination and ratio. In addition, the content of fluorinated unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged. The content of fluorinated unsaturated cyclic carbonate is usually preferably 0.001 mass % or more, more preferably 0.01 mass % or more, more preferably 0.1 mass % or more in 100 mass % of liquid electrolyte, in addition, preferably 5 mass % or less, more preferably 4 mass % or less, more preferably 3 mass % or less. If within the range, the electrochemical device using liquid electrolyte is easy to show sufficient cycle characteristics to improve the effect, in addition, it is easy to avoid the situation that the high temperature storage characteristics are reduced, the gas generation amount becomes more, and the discharge capacity retention rate is reduced.

[0772] The liquid electrolyte disclosed herein may include a compound having a triple bond. The type of the compound is not particularly limited as long as it has one or more triple bonds in the molecule.

[0773] Specific examples of the compound having a triple bond include the following compounds.

[0774] 1-pentyne, 2-pentyne, 1-hexyne, 2-hexyne, 3-hexyne, 1-heptyne, 2-heptyne, 3-heptyne, 1-octyne, 2-octyne, 3-octyne, 4-octyne, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-dodecyne, 2-dodecyne, 3-dodecyne, 4-dodecyne, 5-dodecyne, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butyne, 4-phenyl-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentyne, 5-phenyl-1-pentyne, 1-phenyl-1-hexyne, 6-phenyl-1-hexyne, diphenylacetylene, 4-ethynyltoluene, dicyclohexylacetylene and the like hydrocarbon compounds;

[0775] 2-Propynyl methyl carbonate, 2-propynyl ethyl carbonate, 2-propynyl propyl carbonate, 2-propynyl butyl carbonate, 2-propynyl phenyl carbonate, 2-propynyl cyclohexyl carbonate, di(2-propynyl) carbonate, 1-methyl-2-propynyl methyl carbonate, 1,1-dimethyl-2-propynyl methyl carbonate, 2-butynyl methyl carbonate, 3-butynyl methyl carbonate, 2-pentynyl methyl carbonate, Monocarbonates such as 3-pentynyl methyl carbonate and 4-pentynyl methyl carbonate; dicarbonates such as 2-butyne-1,4-diol dimethyl dicarbonate, 2-butyne-1,4-diol diethyl dicarbonate, 2-butyne-1,4-diol dipropyl dicarbonate, 2-butyne-1,4-diol dibutyl dicarbonate, 2-butyne-1,4-diol diphenyl dicarbonate and 2-butyne-1,4-diol dicyclohexyl dicarbonate;

[0776] 2-Propynyl acetate, 2-propynyl propionate, 2-propynyl butyrate, 2-propynyl benzoate, 2-propynyl cyclohexanecarboxylate, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-propynyl propionate, 1,1-dimethyl-2-propynyl butyrate, 1,1-dimethyl-2-propynyl benzoate, 1,1-dimethyl-2-propynyl cyclohexanecarboxylate, 2-butynyl acetate, 3-butynyl acetate, 2-pentynyl acetate, 3-pentynyl acetate, 4-pentynyl acetate, methyl acrylate, ethyl acrylate Ester, propyl acrylate, vinyl acrylate, 2-propylene acrylate, 2-butylene acrylate, 3-butylene acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl methacrylate, 2-propylene methacrylate, 2-butylene methacrylate, 3-butylene methacrylate, methyl 2-propiolate, ethyl 2-propiolate, propyl 2-propiolate, vinyl 2-propiolate, 2-propylene 2-propiolate, 2-butylene 2-propiolate, 3-butylene 2-propiolate, 2-butylene 2-Butynoic acid methyl ester, 2-butynoic acid ethyl ester, 2-butynoic acid propyl ester, 2-butynoic acid vinyl ester, 2-butynoic acid 2-propenyl ester, 2-butynoic acid 2-butenyl ester, 2-butynoic acid 3-butynoic acid methyl ester, 3-butynoic acid ethyl ester, 3-butynoic acid propyl ester, 3-butynoic acid vinyl ester, 3-butynoic acid 2-propenyl ester, 3-butynoic acid 2-butenyl ester, 3-butynoic acid 3-butynoic acid methyl ester, 2-pentynoic acid ethyl ester, 2-pentynoic acid propyl ester, 2-pentynoic acid vinyl ester, 2-pentynoic acid 2-propenyl ester, 2-pentynoic acid Monocarboxylic acid esters such as 2-butenyl pentynoate, 3-butenyl pentynoate, methyl 3-pentynoate, ethyl 3-pentynoate, propyl 3-pentynoate, vinyl 3-pentynoate, 2-propenyl pentynoate, 2-butenyl pentynoate, 3-butenyl pentynoate, methyl 4-pentynoate, ethyl 4-pentynoate, propyl 4-pentynoate, vinyl 4-pentynoate, 2-propenyl pentynoate, 2-butenyl pentynoate, and 3-butenyl pentynoate, fumarate esters, methyl pivalate, and ethyl pivalate;

[0777] dicarboxylic acid esters such as 2-butyne-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol dibutyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne-1,4-diol dicyclohexanecarboxylate, hexahydrobenzo[1,3,2]dioxathiolane-2-oxide (1,2-cyclohexanediol, 2,2-dioxo-1,2-oxathiolane-4-yl acetate, 2,2-dioxo-1,2-oxathiolane-4-yl acetate;

[0778] Oxalic acid diesters such as 2-propynyl methyl oxalate, 2-propynyl ethyl oxalate, 2-propynyl propyl oxalate, 2-propynyl vinyl oxalate, 2-propynyl allyl oxalate, di(2-propynyl) oxalate, 2-butynyl methyl oxalate, 2-butynyl ethyl oxalate, 2-butynyl propyl oxalate, 2-butynyl vinyl oxalate, 2-butynyl allyl oxalate, di(2-butynyl) oxalate, 3-butynyl methyl oxalate, 3-butynyl ethyl oxalate, 3-butynyl propyl oxalate, 3-butynyl vinyl oxalate, 3-butynyl allyl oxalate, and di(3-butynyl) oxalate;

[0779] Phosphine oxides such as methyl(2-propynyl)(vinyl)phosphine oxide, divinyl(2-propynyl)phosphine oxide, di(2-propynyl)(vinyl)phosphine oxide, di(2-propenyl)(2-propynyl)phosphine oxide, di(2-propenyl)(2-propynyl)phosphine oxide, di(3-butenyl)(2-propynyl)phosphine oxide, and di(2-propynyl)(3-butenyl)phosphine oxide;

[0780] 2-Propynyl methyl (2-propenyl) phosphinate, 2-propynyl 2-butenyl (methyl) phosphinate, 2-propynyl di (2-propenyl) phosphinate, 2-propynyl di (3-butenyl) phosphinate, 1,1-dimethyl-2-propynyl methyl (2-propenyl) phosphinate, 1,1-dimethyl-2-propynyl 2-butenyl (methyl) phosphinate, 1,1-dimethyl-2-propynyl di (2-propenyl) phosphinate , and phosphinates such as 1,1-dimethyl-2-propynyl di(3-butenyl)phosphinate, 2-propenyl methyl(2-propynyl)phosphinate, 3-butenyl methyl(2-propynyl)phosphinate, 2-propenyl di(2-propynyl)phosphinate, 3-butenyl di(2-propynyl)phosphinate, 2-propenyl 2-propynyl(2-propenyl)phosphinate, and 3-butenyl 2-propynyl(2-propenyl)phosphinate;

[0781] 2-propenylphosphonic acid methyl 2-propynyl ester, 2-butenylphosphonic acid methyl (2-propynyl) ester, 2-propenylphosphonic acid (2-propynyl) (2-propenyl) ester, 3-butenylphosphonic acid (3-butenyl) (2-propynyl) ester, 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl) ester, 2-butenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl) ester, 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl) ester, and 3-butenylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl) Phosphonic acid esters such as phosphonic acid (2-propynyl)(2-propenyl) methylphosphonate, phosphonic acid (3-butenyl)(2-propenyl) methylphosphonate, phosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl) methylphosphonate, phosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl) ethylphosphonate, phosphonic acid (2-propynyl) (2-propenyl) (3-butenyl) (2-propenyl) (1,1-dimethyl-2-propynyl) ethylphosphonate, phosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl) (3-butenyl) ethylphosphonate, phosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl) (3-butenyl) ethylphosphonate and phosphonic acid (1,1-dimethyl-2-propynyl) ethylphosphonate;

[0782] Phosphoric acid esters such as (methyl)(2-propenyl)(2-propynyl) phosphate, (ethyl)(2-propenyl)(2-propynyl) phosphate, (2-butenyl)(methyl)(2-propynyl) phosphate, (2-butenyl)(ethyl)(2-propynyl) phosphate, (1,1-dimethyl-2-propynyl)(methyl)(2-propenyl) phosphate, (1,1-dimethyl-2-propynyl)(ethyl)(2-propenyl) phosphate, (2-butenyl)(1,1-dimethyl-2-propynyl)(methyl) phosphate and (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl) phosphate;

[0783] Among these, compounds having an alkynyloxy group are preferred because they can form a negative electrode coating more stably in a liquid electrolyte.

[0784] Furthermore, from the perspective of improving storage characteristics, compounds such as 2-propynyl methyl carbonate, di(2-propynyl) carbonate, 2-butyne-1,4-diol dimethyl dicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, 2-propynyl methyl oxalate, and di(2-propynyl) oxalate are particularly preferred.

[0785] The above-mentioned compound with a triple bond can be used alone as one, or two or more can be used in any combination and ratio. The compound with a triple bond is not limited to the overall mixing amount of the liquid electrolyte disclosed in the present invention, as long as it does not significantly damage the effect of the present invention. It is arbitrary, relative to the liquid electrolyte disclosed in the present invention, usually with 0.01% by mass or more, preferably with 0.05% by mass or more, more preferably with 0.1% by mass or more, and usually with 5% by mass or less, preferably with 3% by mass or less, and more preferably with a concentration of 1% by mass or less. When the above range is met, the effects of output characteristics, load characteristics, cycle characteristics, high temperature storage characteristics, etc. are further improved.

[0786] In the liquid electrolyte of the present disclosure, an overcharge inhibitor may be used in order to effectively suppress battery rupture or ignition when an electrochemical device using the liquid electrolyte is in an overcharged state or the like.

[0787] As the overcharge preventing agent, there can be mentioned aromatic compounds such as biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, unsubstituted or alkyl-substituted terphenyl derivatives, unsubstituted or alkyl-substituted terphenyl derivatives, partially hydrogenated products, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, cyclopentylbenzene, cyclohexylbenzene, isopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, tert-butylbenzene, tert-amylbenzene, tert-hexylbenzene, anisole, etc.; 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene Partial fluorides of the above aromatic compounds such as fluorobenzene, fluorotoluene, and trifluorotoluene; fluorinated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 1,6-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; aromatic acetates such as 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, and phenylethylphenyl acetate; aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate; toluene derivatives such as toluene and xylene; unsubstituted or alkyl-substituted biphenyl derivatives such as 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and o-cyclohexylbiphenyl, etc. Among them, preferred are aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, diphenyl ether, and dibenzofuran; diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, diphenyl carbonate, methylphenyl carbonate, etc. They can be used alone or in combination of two or more. When two or more are used in combination, a combination of cyclohexylbenzene and tert-butylbenzene or tert-amylbenzene is particularly preferred from the perspective of the balance between overcharge prevention characteristics and high-temperature storage characteristics; at least one selected from oxygen-free aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene is used in combination with at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran.

[0788] The liquid electrolyte used in the battery of the present disclosure may be a carboxylic anhydride (excluding compound (2)). The compound represented by the following general formula (6) is preferred. The method for producing the carboxylic anhydride is not particularly limited, and any known method may be selected for production.

[0789] [Chemistry 74]

[0790]

[0791] (In general formula (6), R 61 , R 62Each independently represents a hydrocarbon group having 1 to 15 carbon atoms which may have a substituent.

[0792] R 61 , R 62 As long as it is a monovalent hydrocarbon group, there is no particular limitation on its type. For example, it can be an aliphatic hydrocarbon group, it can also be an aromatic hydrocarbon group, or it can be a group formed by bonding an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group can be a saturated hydrocarbon group, or it can contain an unsaturated bond (carbon-carbon double bond or carbon-carbon triple bond). In addition, the aliphatic hydrocarbon group can be chain-shaped or cyclic, and in the case of a chain-shaped group, it can be straight-chain or branched. In addition, it can also be a group formed by bonding a chain-shaped group and a ring-shaped group. It should be noted that R 61 and R 62 They can be the same as each other or different.

[0793] In addition, in R 61 , R 62 When the hydrocarbon group has a substituent, the type of the substituent is not particularly limited as long as it does not violate the main purpose of the present disclosure. Examples include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, preferably fluorine atoms. Alternatively, as a substituent other than a halogen atom, examples include substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups, preferably cyano groups and carbonyl groups. 61 , R 62 The hydrocarbon group may have only one of these substituents, or may have two or more. When having two or more substituents, these substituents may be the same or different from each other.

[0794] R 61 , R 62 The number of carbon atoms in each hydrocarbon group is usually 1 or more, and is usually 15 or less, preferably 12 or less, more preferably 10 or less, and further preferably 9 or less. 61 and R 62 When the two hydrocarbon groups are bonded to each other to form a divalent hydrocarbon group, the number of carbon atoms in the divalent hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 13 or less, more preferably 10 or less, and further preferably 8 or less. 61 , R 62 When the hydrocarbon group has a substituent containing a carbon atom, it is preferred that R also contain the substituent. 61 , R 62 The total number of carbon atoms satisfies the above range.

[0795] Next, specific examples of the acid anhydride represented by the above general formula (6) are described. It should be noted that, in the following examples, "analogs" refer to acid anhydrides obtained by replacing a part of the structure of the exemplified acid anhydride with other structures within the scope of the present disclosure, for example, dimers, trimers and tetramers composed of multiple acid anhydrides, or isomers with the same number of carbon atoms of the substituent but with branched chains, substances with different positions of the substituent bonded to the acid anhydride, etc.

[0796] First, the following lists R 61 , R 62 Specific examples of the same acid anhydride.

[0797] As R 61 , R 62 Specific examples of the acid anhydride having a chain alkyl group include acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutyric anhydride, 3-methylbutyric anhydride, 2,2-dimethylbutyric anhydride, 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, 2,2,3-trimethylbutyric anhydride, 2,3,3-trimethylbutyric anhydride, 2,2,3,3-tetramethylbutyric anhydride, 2-ethylbutyric anhydride, and the like, and analogs thereof.

[0798] As R 61 , R 62 Specific examples of the acid anhydride of a cyclic alkyl group include cyclopropanecarboxylic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, and the like, and analogs thereof.

[0799] As R 61 , R 62 Specific examples of the alkenyl acid anhydride include acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 2,3,3-trimethylacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3,3-diphenylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, 2,2-dimethyl-3-butenoic anhydride, 3-methyl-3-butenoic anhydride, 2-methyl-3-methyl-3-butenoic anhydride, 2,2-dimethyl-3-methyl-3-butenoic anhydride, 3-pentenoic anhydride, 4-pentenoic anhydride, 2-cyclopentenecarboxylic anhydride, 3-cyclopentenecarboxylic anhydride, 4-cyclopentenecarboxylic anhydride, and analogs thereof.

[0800] As R 61 , R 62 Specific examples of the acid anhydride which is an alkynyl group include propiolic anhydride, 3-phenylpropiolic anhydride, 2-butynoic anhydride, 2-pentynoic anhydride, 3-butynoic anhydride, 3-pentynoic anhydride, 4-pentynoic anhydride and the like, and analogs thereof.

[0801] As R 61 , R 62 Specific examples of the acid anhydride which is an aromatic group include benzoic anhydride, 4-methylbenzoic anhydride, 4-ethylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 2-methylbenzoic anhydride, 2,4,6-trimethylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, 2-naphthalenecarboxylic anhydride, and the like, and analogs thereof.

[0802] In addition, as R 61 , R 62 Examples of acid anhydrides substituted with halogen atoms include acid anhydrides mainly substituted with fluorine atoms. However, acid anhydrides obtained by replacing part or all of these fluorine atoms with chlorine atoms, bromine atoms or iodine atoms are also included in the exemplified compounds.

[0803] As R 61 , R 62 Examples of the acid anhydride of the chain alkyl group substituted with a halogen atom include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, 2-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrapropionic anhydride, 2,3,3,3-tetrapropionic anhydride, 3-fluoropropionic anhydride, 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic anhydride, perfluoropropionic anhydride, and analogs thereof.

[0804] As R 61 , R 62 Examples of the acid anhydride of a cyclic alkyl group substituted with a halogen atom include 2-fluorocyclopentanecarboxylic anhydride, 3-fluorocyclopentanecarboxylic anhydride, 4-fluorocyclopentanecarboxylic anhydride, and the like, and analogs thereof.

[0805] As R 61 , R 62 Examples of the acid anhydride of the alkenyl group substituted with a halogen atom include 2-fluoroacrylic anhydride, 3-fluoroacrylic anhydride, 2,3-difluoroacrylic anhydride, 3,3-difluoroacrylic anhydride, 2,3,3-trifluoroacrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, 3-(trifluoromethyl)acrylic anhydride, 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3,3-tri(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 3-(4-fluorophenyl)acrylic anhydride, 2,3-bis(4-fluorophenyl)acrylic anhydride, 3,3-bis(4-fluorophenyl)acrylic anhydride, 2-fluoro-3-butenoic anhydride, 2,2-difluoro-3-butenoic anhydride, 3-fluoro-2-butenoic anhydride, 4-fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride, 3,3,4-trifluoro-3-butenoic anhydride, and analogs thereof.

[0806] As R 61 , R 62 Examples of the anhydride of the alkynyl group substituted with a halogen atom include 3-fluoro-2-propiolic anhydride, 3-(4-fluorophenyl)-2-propiolic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propiolic anhydride, 4-fluoro-2-butynoic anhydride, 4,4-difluoro-2-butynoic anhydride, 4,4,4-trifluoro-2-butynoic anhydride, and the like, and analogs thereof.

[0807] As R 61 , R 62 Examples of the acid anhydride of the aryl group substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and the like, and analogs thereof.

[0808] As R 61 , R 62 Examples of acid anhydrides having a substituent containing a functional group such as an ester, nitrile, ketone, or ether include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutyric anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and analogs thereof.

[0809] Next, the following lists R 61 , R 62 Specific examples of acid anhydrides that are different from each other.

[0810] Considered as R 61 , R 62 Of all the combinations of the above-mentioned examples and their analogs, representative examples are given below.

[0811] Examples of combinations of chain alkyl groups include acetic propionic anhydride, acetic butyric anhydride, butyric propionic anhydride, and acetic 2-methylpropionic anhydride.

[0812] Examples of the combination of a chain alkyl group and a cyclic alkyl group include acetic cyclopentane anhydride, acetic cyclohexane anhydride, and cyclopentane propionic anhydride.

[0813] Examples of the combination of a chain alkyl group and an alkenyl group include acetic anhydride, acetic anhydride, acetic anhydride, acetic anhydride, and acetic anhydride.

[0814] Examples of the combination of a chain alkyl group and an alkynyl group include acetic anhydride propiolic acid, acetic anhydride 2-butiolic acid, acetic anhydride 3-butiolic acid, acetic anhydride 3-phenylpropiolic acid, and propiolic anhydride.

[0815] Examples of the combination of a chain alkyl group and an aryl group include acetic anhydride benzoic acid, acetic 4-methylbenzoic acid, acetic 1-naphthalenecarboxylic anhydride, and benzoic acid propionic anhydride.

[0816] Examples of the combination of a chain alkyl group and a hydrocarbon group having a functional group include acetic fluoroacetic anhydride, acetic trifluoroacetic anhydride, acetic 4-fluorobenzoic anhydride, acetic fluoropropionic anhydride, acetic alkyl oxalic anhydride, acetic 2-cyanoacetic anhydride, acetic 2-oxopropionic anhydride, acetic methoxyacetic anhydride, methoxyacetic propionic anhydride, and the like.

[0817] Examples of combinations of cyclic alkyl groups include cyclopentanecarboxylic acid and cyclohexanecarboxylic anhydride.

[0818] Examples of the combination of a cyclic alkyl group and an alkenyl group include cyclopentane acrylic acid anhydride, 3-cyclopentane methacrylic acid anhydride, 3-cyclopentane butylene acrylic acid anhydride, and cyclohexane acrylic acid anhydride.

[0819] Examples of the combination of a cyclic alkyl group and an alkynyl group include propiolic acid cyclopentane anhydride, 2-butynoic acid cyclopentane anhydride, and propiolic acid cyclohexane anhydride.

[0820] Examples of the combination of a cyclic alkyl group and an aryl group include benzoic acid cyclopentane anhydride, 4-methylbenzoic acid cyclopentane anhydride, and benzoic acid cyclohexane anhydride.

[0821] Examples of the combination of a cyclic alkyl group and a hydrocarbon group having a functional group include fluoroacetic cyclopentanecarboxylic anhydride, cyclopentanecarboxylic trifluoroacetic anhydride, cyclopentanecarboxylic 2-cyanoacetic anhydride, cyclopentanecarboxylic methoxyacetic anhydride, and cyclohexanecarboxylic fluoroacetic anhydride.

[0822] Examples of combinations of alkenyl groups include acrylic acid 2-methacrylic anhydride, acrylic acid 3-methacrylic anhydride, acrylic acid 3-butenoic anhydride, and 2-methacrylic acid 3-methacrylic anhydride.

[0823] Examples of the combination of an alkenyl group and an alkynyl group include acrylic acid propiolic anhydride, acrylic acid 2-butynic anhydride, and 2-methacrylic acid propiolic anhydride.

[0824] Examples of the combination of an alkenyl group and an aryl group include acrylic acid benzoic anhydride, acrylic acid 4-methylbenzoic anhydride, and 2-methacrylic acid benzoic anhydride.

[0825] Examples of the combination of an alkenyl group and a hydrocarbon group having a functional group include acrylic acid fluoroacetic anhydride, acrylic acid trifluoroacetic anhydride, acrylic acid 2-cyanoacetic anhydride, acrylic acid methoxyacetic anhydride, and 2-methacrylic acid fluoroacetic anhydride.

[0826] Examples of combinations of alkynyl groups include propiolic acid 2-butynoic anhydride, propiolic acid 3-butynoic anhydride, and 2-butynoic acid 3-butynoic anhydride.

[0827] Examples of the combination of an alkynyl group and an aryl group include benzoic acid propiolic anhydride, 4-methylbenzoic acid propiolic anhydride, and benzoic acid 2-butynoic anhydride.

[0828] Examples of the combination of an alkynyl group and a hydrocarbon group having a functional group include propiolic acid fluoroacetic anhydride, propiolic acid trifluoroacetic anhydride, propiolic acid 2-cyanoacetic anhydride, propiolic acid methoxyacetic anhydride, and 2-butynoic acid fluoroacetic anhydride.

[0829] Examples of combinations of aryl groups include benzoic acid 4-methylbenzoic anhydride, benzoic acid 1-naphthalenecarboxylic anhydride, and 4-methylbenzoic acid 1-naphthalenecarboxylic anhydride.

[0830] Examples of the combination of an aryl group and a hydrocarbon group having a functional group include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, and 4-methylbenzoic acid fluoroacetic anhydride.

[0831] Examples of the combination of hydrocarbon groups having a functional group include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, trifluoroacetic acid 2-cyanoacetic anhydride, and the like.

[0832] Among the acid anhydrides forming a chain structure, acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, propiolic anhydride, 2-butynoic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, trifluoroacetic anhydride, 3,3,3- Trifluoropropionic anhydride, 2-(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride; more preferably acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride.

[0833] These compounds form a film having excellent durability by appropriately forming a bond with lithium oxalate salt, and are particularly preferred from the viewpoint of being able to improve charge and discharge rate characteristics, input and output characteristics, and impedance characteristics after a durability test.

[0834] It should be noted that the molecular weight of the carboxylic anhydride is not limited, and is arbitrary as long as it does not significantly impair the effects of the present disclosure, and is generally 90 or more, preferably 95 or more, and is generally 300 or less, preferably 200 or less. If the molecular weight of the carboxylic anhydride is within the above range, the viscosity increase of the liquid electrolyte can be suppressed, and the film density is optimized, so that the durability can be appropriately improved.

[0835] In addition, the method for producing the carboxylic anhydride is not particularly limited, and any known method can be selected to produce the carboxylic anhydride. The carboxylic anhydride described above can be contained in the non-aqueous liquid electrolyte of the present disclosure alone or in any combination and ratio.

[0836] In addition, the content of the above-mentioned carboxylic anhydride relative to the liquid electrolyte of the present disclosure is not particularly limited, as long as it does not significantly damage the effect of the present disclosure, it is arbitrary, relative to the liquid electrolyte of the present disclosure, usually 0.01 mass % or more, preferably 0.1 mass % or more, and usually 5 mass % or less, preferably 3 mass % or less. If the content of the carboxylic anhydride is within the above range, it is easy to play the effect of improving the cycle characteristics, and the reactivity is appropriate, so it is easy to improve the battery characteristics.

[0837] The liquid electrolyte disclosed in the present invention may use other known additives. Examples of other additives include hydrocarbon compounds such as pentane, heptane, octane, nonane, decane, cycloheptane, benzene, furan, naphthalene, 2-phenylbicyclohexane, cyclohexane, 2,4,8,10-tetraoxaspiro[5.5]undecane, and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane;

[0838] Fluorinated aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, trifluorotoluene, monofluorobenzene, 1-fluoro-2-cyclohexylbenzene, 1-fluoro-4-tert-butylbenzene, 1-fluoro-3-cyclohexylbenzene, 1-fluoro-2-cyclohexylbenzene, and fluorobiphenyl;

[0839] Carbonate compounds such as erythritan carbonate, spirobis-dimethylene carbonate, and methoxyethyl-methyl carbonate;

[0840] Ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxapentadecane, ethoxymethoxyethane, trimethoxymethane, glycol dimethyl ether, and ethyl monoglycol dimethyl ether;

[0841] Ketone compounds such as dimethyl ketone, diethyl ketone, 3-pentanone, etc.

[0842] Anhydrides such as 2-allylsuccinic anhydride;

[0843] Ester compounds such as dimethyl oxalate, diethyl oxalate, ethyl methyl oxalate, di(2-propynyl) oxalate, methyl 2-propynyl oxalate, dimethyl succinate, di(2-propynyl) glutarate, methyl formate, ethyl formate, 2-propynyl formate, 2-butyne-1,4-diyl dicarboxylate, 2-propynyl methacrylate, and dimethyl malonate;

[0844] Acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide and other amide compounds;

[0845] Ethylene sulfate, vinylene sulfate, ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, cyclobutene sulfone, diphenyl sulfone, N,N-dimethyl methanesulfonamide, N,N-diethyl methanesulfonamide, methyl vinylsulfonate, ethyl vinylsulfonate, allyl vinylsulfonate, propargyl vinylsulfonate, methyl allylsulfonate, ethyl allylsulfonate, allylsulfonate, propargyl allylsulfonate, 1,2-bis(vinylsulfonyloxy)ethane, propanedisulfonic anhydride, sulfobutyric anhydride, sulfobenzoic anhydride, sulfopropionic anhydride, ethanedisulfonic anhydride, methylene methanedisulfonate, 2-propynyl methanesulfonate, amyl sulfite, pentafluorophenyl methanesulfonate, propylene sulfate, propylene sulfite, propane sultone, butylene sulfite, (butane -2,3-diyl) dimethanesulfonate, (2-butyne-1,4-diyl) dimethanesulfonate, vinyl sulfonic acid (2-propynyl) ester, bis(2-vinylsulfonylethyl) ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiolane-2-oxide, 2-propynyl 2-(methylsulfonyloxy) propionate, 5,5-dimethyl-1,2-oxathiolane-4-one 2,2-dioxide, 3-sulfo-propionic anhydride methanedisulfonic acid trimethylene 2-methyltetrahydrofuran, methanedisulfonic acid trimethylene ester, tetramethylene sulfoxide, methanedisulfonic acid dimethylene ester, difluoroethyl methyl sulfone, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, ethylenebissulfonic acid methyl ester, ethylenebissulfonic acid ethyl ester, ethylene sulfate, thiophene-1-oxide and other sulfur-containing compounds;

[0846] 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and nitrogen-containing compounds such as N-methylsuccinimide, nitromethane, nitroethane, and ethylenediamine;

[0847] Trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, ethyl diethylphosphonoacetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide, bis(2,2-difluoroethyl) 2,2,2-trifluoroethyl phosphate, bis(2,2,3,3-tetrafluoropropyl) 2,2,2-trifluoroethyl phosphate Ester, bis(2,2,2-trifluoroethyl) methyl phosphate, bis(2,2,2-trifluoroethyl) ethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2-difluoroethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2,3,3-tetrafluoropropyl phosphate, tributyl phosphate, tri(2,2,2-trifluoroethyl) phosphate, tri(1,1,1,3,3,3-hexafluoropropane-2-yl) phosphate, trioctyl phosphate, 2-phenylphenyl dimethyl phosphate, 2-phenyl phosphate 2-(Dimethoxyphosphoryl)acetic acid methyl ester, 2-(Dimethylphosphoryl)acetic acid methyl ester, 2-(diethoxyphosphoryl)acetic acid methyl ester, 2-(Diethylphosphoryl)acetic acid methyl ester, methylenebisphosphonic acid methyl ester, methylenebisphosphonic acid ethyl ester, ethylenebisphosphonic acid methyl ester, ethylenebisphosphonic acid ethyl ester, butylenebisphosphonic acid methyl ester, butylenebisphosphonic acid ethyl ester, 2-(Dimethoxyphosphoryl)acetic acid Phosphorus-containing compounds such as 2-propynyl ester, 2-(dimethylphosphoryl)acetate 2-propynyl ester, 2-(diethoxyphosphoryl)acetate 2-propynyl ester, 2-(diethylphosphoryl)acetate 2-propynyl ester, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, tris(trimethoxysilyl) phosphite, and trimethylsilyl polyphosphate;

[0848] Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate;

[0849] Silane compounds such as bis(trimethyl)aluminum orthosilicate, bis(triethyl)aluminum orthosilicate, bis(propanol)triethylaluminum orthosilicate, bis(butanol)trimethylaluminum orthosilicate, bis(trimethylsiloxy)titanium, tetra(triethylsiloxy)titanium, tetramethylsilane, etc.; etc.

[0850] They can be used alone or in combination of two or more. By adding these auxiliary agents, the capacity retention characteristics or cycle characteristics after high temperature storage can be improved. As the above-mentioned other auxiliary agents, phosphorus-containing compounds are preferred, preferably tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite.

[0851] The amount of other auxiliary agents is not particularly limited, as long as it does not significantly damage the effect of the present disclosure. Other auxiliary agents are preferably 0.01% by mass or more in 100% by mass of the liquid electrolyte, and are also 5% by mass or less. If it is within this range, it is easy to fully show the effect of other auxiliary agents, and it is also easy to avoid the situation where the characteristics of the battery such as high-load discharge characteristics are reduced. The amount of other auxiliary agents is more preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 3% by mass or less, and more preferably 1% by mass or less.

[0852] The liquid electrolyte used in the battery of the present invention may further contain cyclic and chain carboxylates, ether compounds, nitrogen-containing compounds, boron-containing compounds, organic silicon compounds, non-flammable (flame retardant) agents, surfactants, high dielectric additives, cycle characteristics and rate characteristics improvers, sulfone compounds, etc. as additives within the range that does not impair the effects of the present invention.

[0853] Examples of the cyclic carboxylic acid ester include cyclic carboxylic acid esters having a total carbon number of 3 to 12 in the structural formula. Specifically, examples include γ-butyrolactone, γ-valerolactone, γ-caprolactone, ε-caprolactone, and 3-methyl-γ-butyrolactone. Among them, γ-butyrolactone is particularly preferred from the perspective of improving the characteristics of the electrochemical device due to the improved degree of lithium ion dissociation.

[0854] Usually, in 100% by mass of the solvent, the compounding amount of the cyclic carboxylic acid ester as an additive is preferably 0.1% by mass or more, more preferably 1% by mass or more. If it is this range, the conductivity of the liquid electrolyte is improved, and the large current discharge characteristics of the electrochemical device are easily improved. In addition, the compounding amount of the cyclic carboxylic acid ester is preferably 10% by mass or less, more preferably 5% by mass or less. By setting the upper limit in this way, the viscosity of the liquid electrolyte is set to an appropriate range, the reduction of conductivity is avoided, the increase of the negative electrode resistance is suppressed, and the large current discharge characteristics of the electrochemical device are easily made to be a good range.

[0855] In addition, as the cyclic carboxylic acid ester, a fluorinated cyclic carboxylic acid ester (fluorinated lactone) can also be preferably used. As the fluorinated lactone, for example, there can be mentioned a fluorinated lactone represented by the following formula (C).

[0856] [Chemistry 75]

[0857]

[0858] (Where X 15 ~X 20 are the same or different, all are -H, -F, -Cl, -CH3 or fluorinated alkyl; wherein X 15 ~X 20 At least one of them is a fluorinated alkyl group.)

[0859] As X 15 ~X 20 The fluorinated alkyl group may be, for example, -CFH2, -CF2H, -CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, -CF(CF3)2, etc. From the perspective of high oxidation resistance and safety improvement effect, -CH2CF3 and -CH2CF2CF3 are preferred.

[0860] If X 15 ~X 20 At least one of them is a fluorinated alkyl group, then -H, -F, -Cl, -CH3 or a fluorinated alkyl group may be substituted only with X 15 ~X 20 The position of may be substituted with multiple positions. From the viewpoint of good solubility of the electrolyte salt, 1 to 3 positions are preferred, and 1 to 2 positions are more preferred.

[0861] The substitution position of the fluorinated alkyl group is not particularly limited, but X is preferred due to good synthesis yield. 17 and / or X 18 , especially X 17 or X 18 is a fluorinated alkyl group, especially -CH2CF3, -CH2CF2CF3. X other than a fluorinated alkyl group 15 ~X 20 It is -H, -F, -Cl or CH 3 , and is preferably -H from the viewpoint of good solubility of the electrolyte salt.

[0862] Examples of the fluorine-containing lactone include, in addition to the fluorine-containing lactone represented by the above formula, a fluorine-containing lactone represented by the following formula (D).

[0863] [Chemistry 76]

[0864]

[0865] (In the formula, either A or B is CX 226 X 227 (X 226 and X 227 Rf is the same or different, and is -H, -F, -Cl, -CF3, -CH3 or an alkylene group in which the hydrogen atom may be substituted by a halogen atom and may contain a heteroatom in the chain, and the other is an oxygen atom; 12 is a fluorinated alkyl or fluorinated alkoxy group with or without an ether bond; X 221 and X 222 The same or different are -H, -F, -Cl, -CF3 or CH3; X 223 ~X 225The same or different, all are -H, -F, -Cl or an alkyl group in which the hydrogen atom may be substituted by a halogen atom and may contain a heteroatom in the chain; n = 0 or 1.

[0866] As the fluorine-containing lactone represented by formula (D), a 5-membered ring structure represented by the following formula (E) is preferably mentioned from the viewpoint of easy synthesis and good chemical stability:

[0867] [Chemistry 77]

[0868]

[0869] (In the formula, A, B, Rf 12 , X 221 , X 222 and X 223 Same as formula (D).

[0870] Furthermore, the combination of A and B provides a fluorine-containing lactone represented by the following formula (F) and a fluorine-containing lactone represented by the following formula (G).

[0871] [Chemistry 78]

[0872]

[0873] (Where Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 Same as formula (D).

[0874] [Chemistry 79]

[0875]

[0876] (Where Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 Same as formula (D).

[0877] Among these, from the aspect that they can particularly exhibit excellent characteristics such as high dielectric constant and high withstand voltage, from the aspect that the solubility of electrolyte salt and the reduction of internal resistance are good, and from the aspect that the characteristics as a liquid electrolyte in the present disclosure are improved, the following can be mentioned:

[0878] [Chemistry 80]

[0879] wait.

[0880] By containing a fluorinated cyclic carboxylic acid ester, effects such as improvement in ion conductivity, improvement in safety, and improvement in stability at high temperatures can be obtained.

[0881] Examples of the chain carboxylic acid esters include those having a total carbon number of 3 to 7 in the structural formula thereof. Specifically, examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isobutyl propionate, n-butyl propionate, methyl butyrate, isobutyl propionate, tert-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, isopropyl isobutyrate, and the like.

[0882] Among them, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, and the like are preferred from the viewpoint of improving ion conductivity by reducing viscosity.

[0883] As the ether compound, chain ethers having 2 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms are preferred.

[0884] Examples of the chain ether having 2 to 10 carbon atoms include dimethyl ether, diethyl ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, diethoxymethane, dimethoxyethane, methoxyethoxyethane, diethoxyethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol, diethylene glycol dimethyl ether, pentaethylene glycol, triethylene glycol dimethyl ether, triethylene glycol, tetraethylene glycol, tetraethylene glycol dimethyl ether, and diisopropyl ether.

[0885] Examples of the cyclic ether having 3 to 6 carbon atoms include 1,2-dioxane, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane, trioxane, 2-methyl-1,3-dioxolane, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-(trifluoroethyl)dioxolane, 2,2-bis(trifluoromethyl)-1,3-dioxolane, and fluorinated compounds thereof. Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, and crown ether are preferred from the perspective of high solvating ability for lithium ions and improving ion dissociation degree; dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are particularly preferred from the perspective of low viscosity and providing high ion conductivity.

[0886] Examples of the nitrogen-containing compound include nitrile, fluorine-containing nitrile, carboxylic acid amide, fluorine-containing carboxylic acid amide, sulfonic acid amide, fluorine-containing sulfonamide, acetamide, formamide, etc. In addition, 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide, etc., can also be used. However, the nitrile compounds represented by the general formulas (1a), (1b), and (1c) are not included in the nitrogen-containing compound.

[0887] Examples of the boron-containing compound include boric acid esters such as trimethyl borate and triethyl borate, boric acid ethers, and boric acid alkyl esters.

[0888] Examples of the organic silicon-containing compound include (CH3)4-Si, (CH3)3-Si-Si(CH3)3, and silicone oil.

[0889] As the above-mentioned incombustible (flame retardant) agent, phosphate ester or phosphazene compound can be cited. As the above-mentioned phosphate ester, for example, fluorine-containing alkyl phosphate ester, non-fluorine-based alkyl phosphate ester, aryl phosphate ester, etc. can be cited. Among them, fluorine-containing alkyl phosphate ester is preferred from the aspect of being able to exert the incombustible effect in a small amount.

[0890] Examples of the phosphazene compounds include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0891] Specific examples of the fluorine-containing alkyl phosphate include fluorine-containing dialkyl phosphates described in Japanese Patent Application Laid-Open No. 11-233141, cyclic alkyl phosphates described in Japanese Patent Application Laid-Open No. 11-283669, and fluorine-containing trialkyl phosphates.

[0892] As the above-mentioned non-combustible (flame retardant) agent, preferred are (CH3O)3P=O, (CF3CH2O)3P=O, (HCF2CH2O)3P=O, (CF3CF2CH2)3P=O, (HCF2CF2CH2)3P=O and the like.

[0893] The surfactant may be any of a cationic surfactant, anionic surfactant, nonionic surfactant, and amphoteric surfactant. From the viewpoint of good cycle characteristics and rate characteristics, a surfactant containing a fluorine atom is preferred.

[0894] The content of the surfactant is preferably 0.01% by mass to 2% by mass in the liquid electrolyte from the viewpoint of being able to reduce the surface tension of the liquid electrolyte without reducing the charge-discharge cycle characteristics.

[0895] Examples of the dielectric constant-enhancing additive include sulfolane, methyl sulfolane, γ-butyrolactone, and γ-valerolactone.

[0896] Examples of the cycle characteristics and rate characteristics improving agent include methyl acetate, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0897] In addition, the liquid electrolyte used in the battery of the present disclosure may be further combined with a polymer material to form a gel liquid electrolyte in a gel state (plasticized).

[0898] As such polymer materials, there can be cited conventionally known polyethylene oxide, polypropylene oxide, their modified bodies (Japanese Patent Publication No. 8-222270, Japanese Patent Publication No. 2002-100405); polyacrylate polymers, polyacrylonitrile, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer and other fluororesins (Japanese Patent Publication No. 4-506726, Japanese Patent Publication No. 8-507407, Japanese Patent Publication No. 10-294131); composites of these fluororesins and hydrocarbon resins (Japanese Patent Publication No. 11-35765, Japanese Patent Publication No. 11-86630), etc. It is particularly desirable to use polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer as polymer materials for gel electrolytes.

[0899] In addition, the liquid electrolyte used in the battery of the present disclosure may contain an ion-conductive compound described in Japanese Patent Application No. 2004-301934.

[0900] The ion conductive compound is an amorphous fluorine-containing polyether compound having a fluorine-containing group in a side chain represented by the formula (101).

[0901] A-(D)-B(101)

[0902] [Wherein, D is formula (201):

[0903] -(D1) n -(FAE) m -(AE) p -(Y) q -(201)

[0904] (wherein, D1 is an ether unit having a fluorine-containing ether group in the side chain represented by formula (2a),

[0905] [Chemistry 81]

[0906]

[0907] (wherein, Rf is a fluorinated ether group with or without a crosslinking functional group; R10 is a group or bond that bonds Rf to the main chain)

[0908] FAE is an ether unit having a fluorinated alkyl group in the side chain represented by formula (2b),

[0909] [Chemistry 82]

[0910]

[0911] (wherein, Rfa is a hydrogen atom, a fluorinated alkyl group with or without a crosslinking functional group; R 11 is a group or bond that bonds Rfa to the main chain)

[0912] AE is an ether unit represented by formula (2c),

[0913] [Chemistry 83]

[0914]

[0915] (Where R 13 is a hydrogen atom, an alkyl group having or not having a crosslinking functional group, an aliphatic cyclic hydrocarbon group having or not having a crosslinking functional group, or an aromatic hydrocarbon group having or not having a crosslinking functional group; R 12 To R 13 Groups or bonds bonded to the main chain)

[0916] Y is a unit comprising at least one of the formulae (2d-1) to (2d-3),

[0917] [Chemistry 84]

[0918]

[0919] n is an integer of 0 to 200; m is an integer of 0 to 200; p is an integer of 0 to 10000; q is an integer of 1 to 100; wherein n+m is not 0, and the bonding order of D1, FAE, AE and Y is not specific);

[0920] A and B are the same or different and are hydrogen atoms, alkyl groups containing or not containing fluorine atoms and / or crosslinking functional groups, phenyl groups containing or not containing fluorine atoms and / or crosslinking functional groups, -COOH groups, -OR (R is a hydrogen atom or an alkyl group containing or not containing fluorine atoms and / or crosslinking functional groups), ester groups or carbonate groups (wherein, when the terminal of D is an oxygen atom, it is not -COOH groups, -OR, ester groups or carbonate groups).]

[0921] The liquid electrolyte used in the battery of the present disclosure may contain a sulfone compound. As the sulfone compound, cyclic sulfones having 3 to 6 carbon atoms and chain sulfones having 2 to 6 carbon atoms are preferred. The number of sulfonyl groups in one molecule is preferably 1 or 2.

[0922] Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones as monosulfone compounds, and trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones as disulfone compounds. Among them, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred from the perspective of dielectric constant and viscosity, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0923] As sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter, including sulfolane, sometimes referred to as "sulfolanes") are preferred. As sulfolane derivatives, substances in which one or more of the hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with fluorine atoms or alkyl groups are preferred.

[0924] Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methylsulfolane, 4 -fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3-(trifluoromethyl)sulfolane, 3-fluoro-3-(trifluoromethyl)sulfolane, 4-fluoro-3-(trifluoromethyl)sulfolane, 3-cyclobutene sulfolane, 5-fluoro-3-(trifluoromethyl)sulfolane, and the like.

[0925] Examples of the chain sulfone include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl sulfone, tert-butyl methyl sulfone, tert-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl Trifluoromethyl sulfone, perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, bis(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl n-propyl sulfone, difluoromethyl n-propyl sulfone, trifluoromethyl n-propyl sulfone, fluoromethyl isopropyl sulfone, difluoromethyl isopropyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl n-propyl sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl n-butyl sulfone, trifluoroethyl tert-butyl sulfone, pentafluoroethyl n-butyl sulfone, pentafluoroethyl tert-butyl sulfone, etc.

[0926] Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, trifluoromethyl n-propyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl n-butyl sulfone, trifluoroethyl tert-butyl sulfone, trifluoromethyl n-butyl sulfone, trifluoromethyl tert-butyl sulfone and the like are preferred from the viewpoint of high ion conductivity and high input and output.

[0927] The content of the sulfone compound is not particularly limited, as long as it does not significantly damage the effect of the present disclosure, and is arbitrary. In the above-mentioned solvent 100 volume %, it is usually 0.3 volume % or more, preferably 0.5 volume % or more, more preferably 1 volume % or more, and usually 40 volume % or less, preferably 35 volume % or less, more preferably 30 volume % or less. If the content of the sulfone compound is within the above range, it is easy to obtain the effect of improving the durability such as cycle characteristics and storage characteristics. In addition, the viscosity of the non-aqueous liquid electrolyte can be made into an appropriate range, avoiding the reduction of conductivity, and the input and output characteristics and charge and discharge rate characteristics of the non-aqueous liquid electrolyte secondary battery can be made into an appropriate range.

[0928] From the perspective of improving output characteristics, the liquid electrolyte used in the battery of the present disclosure also preferably contains as an additive at least one compound (7) selected from the group consisting of lithium fluorophosphate salts (excluding LiPF6) and lithium salts having an S═O group.

[0929] When the compound (7) is used as an additive, it is preferable to use a compound other than the compound (7) as the electrolyte salt.

[0930] Examples of the lithium fluorophosphate salts include monofluorolithium phosphate (LiPO3F), difluorolithium phosphate (LiPO2F2), and the like.

[0931] Examples of the lithium salts having an S═O group include lithium monofluorosulfonate (FSO 3 Li), lithium methyl sulfate (CH 3 OSO 3 Li), lithium ethyl sulfate (C 2 H 5 OSO 3 Li), and 2,2,2-trifluoroethyl lithium sulfate.

[0932] Among the compounds (7), LiPO2F2, FSO3Li and C2H5OSO3Li are preferred.

[0933] The content of the compound (7) is preferably 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, further preferably 0.1 to 10% by mass, particularly preferably 0.1 to 7% by mass, based on the liquid electrolyte.

[0934] The liquid electrolyte used in the battery of the present disclosure may be further mixed with other additives as needed. Examples of other additives include metal oxides and glass.

[0935] The liquid electrolyte used in the battery disclosed herein preferably has a hydrogen fluoride (HF) content of 5ppm to 200ppm. By containing HF, the film formation of the above-mentioned additives can be promoted. If the HF content is too little, the film forming ability on the negative electrode decreases, and there is a tendency for the characteristics of the electrochemical device to decrease. In addition, if the HF content is too much, there is a tendency for the oxidation resistance of the liquid electrolyte to decrease due to the influence of HF. Even if the liquid electrolyte used in the battery disclosed herein contains HF in the above-mentioned range, it will not reduce the high-temperature storage recovery capacity rate of the electrochemical device.

[0936] The HF content is more preferably 10 ppm or more, and further preferably 20 ppm or more. In addition, the HF content is more preferably 100 ppm or less, further preferably 80 ppm or less, and particularly preferably 50 ppm or less.

[0937] The HF content can be determined by neutralization titration.

[0938] The liquid electrolyte used in the battery of the present disclosure can be prepared by any method using the above-mentioned components.

[0939] (positive electrode)

[0940] In the battery of the present disclosure, the positive electrode is not particularly limited, and a positive electrode composed of a positive electrode active material layer containing a positive electrode active material and a current collector can be used.

[0941] As the above-mentioned positive electrode active material, there is no particular limitation as long as it can electrochemically encapsulate / release at least one metal ion selected from lithium, sodium, magnesium and zinc, for example, preferably a material containing an alkali metal and at least one transition metal. As specific examples, transition metal composite oxides containing alkali metals, transition metal phosphate compounds containing alkali metals, sulfur-based materials, conductive polymers, etc. can be cited.

[0942] Among them, as the positive electrode active material, a transition metal composite oxide containing an alkali metal that can generate a high voltage is particularly preferred. As the above-mentioned alkali metal ion, lithium ion, sodium ion, etc. can be cited. In a preferred embodiment, the alkali metal ion can be a lithium ion. That is, in this embodiment, the alkali metal ion secondary battery is a lithium ion secondary battery.

[0943] Examples of the alkali metal-containing transition metal composite oxide include

[0944] Formula: MaMn 2-b M 1 b O4

[0945] (wherein, M is at least one metal selected from the group consisting of Li and Na; 0.5≤a; 0≤b≤1.5; M 1 an alkali metal-manganese spinel composite oxide represented by at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge,

[0946] Formula: MNi 1-c M 2 c O2

[0947] (wherein, M is at least one metal selected from the group consisting of Li and Na; 0≤c≤0.5; M 2 an alkali metal-nickel composite oxide represented by at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge, or

[0948] Formula: MCo 1-d M 3 d O2

[0949] (wherein, M is at least one metal selected from the group consisting of Li and Na; 0≤d≤0.5; M3 The alkali metal-cobalt composite oxide is represented by at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge.

[0950] Among the above, M is preferably one metal selected from the group consisting of Li and Na, more preferably Li or Na, and further preferably Li.

[0951] Among them, MCoO2, MMnO2, MNiO2, MMn2O4, MNi 0.8 Co 0.15 Al 0.05 O2, or MNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc., preferably a compound represented by the following general formula (3).

[0952] MNi h Co i Mn j M 5 k O2 (3)

[0953] (In the formula, M is 5 represents at least one selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge, (h+i+j+k)=1.0, 0≤h≤1.0, 0≤i≤1.0, 0≤j≤1.5, 0≤k≤0.2.)

[0954] Examples of the alkali metal-containing transition metal phosphate compound include the following formula (4):

[0955] M e M 4 f (PO4) g (4)

[0956] (wherein, M is at least one metal selected from the group consisting of Li and Na, M 4 represents at least one selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni and Cu, 0.5≤e≤3, 1≤f≤2, 1≤g≤3). Among the above, M is preferably a metal selected from the group consisting of Li and Na, and more preferably Li.

[0957] As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferred. As specific examples, iron phosphates such as LiFePO4, Li3Fe2(PO4)3, LiFeP2O7, etc.; cobalt phosphates such as LiCoPO4; substances obtained by substituting a part of the transition metal atoms that are the main body of these lithium transition metal phosphate compounds with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc. As the above-mentioned lithium-containing transition metal phosphate compound, an olivine-type structure is preferred.

[0958] As other positive electrode active materials, MFePO4, MNi 0.8 Co 0.2 O2, M 1.2 Fe 0.4 Mn 0.4 O2, MNi 0.5 Mn 1.5 O2, MV3O6, M2MnO3, MMnO3, etc. In particular, positive electrode active materials such as M2MnO3, MNi 0.5 Mn 1.5 O2, etc. are preferred in that the crystal structure does not collapse when the secondary battery operates at a voltage exceeding 4.4V or a voltage of 4.6V or higher. Therefore, electrochemical devices such as secondary batteries using a positive electrode material containing the above-exemplified positive electrode active materials are preferred because the residual capacity is not easily reduced, the resistance increase rate does not easily change even when stored at a high temperature, and the battery performance does not deteriorate even when operating at a high voltage.

[0959] As other positive electrode active materials, M2MnO3 and MM 6 O2 (wherein M is at least one metal selected from the group consisting of Li and Na, and M 6 is a transition metal such as Co, Ni, Mn, Fe, etc.) solid solution materials, etc.

[0960] As the above solid solution material, for example, it is an alkali metal manganese oxide represented by the general formula Mx[Mn(1-y)M 7 y]Oz. Here, M in the formula is at least one metal selected from the group consisting of Li and Na, and M 7 is composed of at least one metal element other than M and Mn, and includes, for example, one or more elements selected from the group consisting of Co, Ni, Fe, Ti, Mo, W, Cr, Zr, and Sn. In addition, the values of x, y, and z in the formula are in the range of 0.5 < x < 2, 0 ≤ y < 1, and 1.5 < z < 3. Among them, Li 1.2 Mn0.5 Co 0.14 Ni 0.14 A manganese-containing solid solution material based on Li2MnO3 and solid-solution-dissolved with LiNiO2 and LiCoO2 such as O2 can provide an alkali metal ion secondary battery having a high energy density and is preferred in this regard.

[0961] In addition, if lithium phosphate is included in the positive electrode active material, the continuous charging characteristics are improved, and thus it is preferred. The use of lithium phosphate is not limited, and it is preferred to use a mixture of the above positive electrode active material and lithium phosphate. 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 or more with respect to the total lower limit of the above 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 further preferably 5% by mass or less.

[0962] As the above-mentioned chalcogen-based material, materials containing sulfur atoms can be exemplified, and at least one selected from the group consisting of elemental sulfur, metal sulfides, and organic sulfur compounds is preferred, and elemental sulfur is more preferred. The above metal sulfide may be a metal polysulfide. The above organic sulfur compound may be an organic polysulfide.

[0963] As the above metal sulfide, LiS x (0 < x ≤ 8) shown compounds; Li2S x (0 < x ≤ 8) shown compounds; compounds having a two-dimensional layered structure such as TiS2 and MoS2; general formula Me x Mo6S8 (Me is various transition metals represented by Pb, Ag, and Cu) shown Chevrel phase compounds having a firm three-dimensional framework structure, etc.

[0964] As the above organic sulfur compound, carbon sulfur compounds, etc. can be exemplified.

[0965] The above organic sulfur compound is sometimes supported on a porous material such as carbon and used as a carbon composite material. As the content of sulfur contained in the carbon composite material, for the reason of more excellent cycle performance and further reduced overvoltage, it is preferably 10% by mass to 99% by mass with respect to the above carbon composite material, more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 85% by mass or less.

[0966] When the above positive electrode active material is the above elemental sulfur, the content of sulfur contained in the above positive electrode active material is equal to the content of the above elemental sulfur.

[0967] Examples of the conductive polymer include p-doped conductive polymers and n-doped conductive polymers, polyacetylene-based polymers, polyphenylene-based polymers, heterocyclic polymers, ionic polymers, ladder polymers, and network polymers.

[0968] In addition, a material having a different composition attached to the surface of the above-mentioned positive electrode active material may also be used. Examples of the surface-attached material include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; carbon; and the like.

[0969] These surface-attached substances can be attached to the surface of the positive electrode active material by, for example, the following methods: a method of dissolving or suspending the substance in a solvent and adding it to the positive electrode active material by infiltration and drying; a method of dissolving or suspending the surface-attached substance precursor in a solvent and adding it to the positive electrode active material by infiltration and then reacting it by heating or the like; a method of adding it to the positive electrode active material precursor and simultaneously firing it; etc. It should be noted that in the case of attaching carbon, a method of mechanically attaching carbon in the form of activated carbon or the like can also be used.

[0970] The amount of the surface-attached substance is used in the following amount relative to the mass of the positive electrode active material: the lower limit is preferably 0.1 ppm or more, more preferably 1 ppm or more, and further preferably 10 ppm or more, and the upper limit is preferably 20% or less, more preferably 10% or less, and further preferably 5% or less. The surface-attached substance can inhibit the oxidation reaction of the liquid electrolyte on the surface of the positive electrode active material and improve the battery life. However, if the amount of the attached substance is too small, the effect cannot be fully demonstrated; if it is too large, it will hinder the entry and exit of lithium ions, thereby possibly increasing the resistance.

[0971] The shape of the particles of the positive electrode active material may be block, polyhedron, sphere, ellipsoid, plate, needle, column, etc. The primary particles may be aggregated to form secondary particles.

[0972] The tap density of the positive electrode active material is preferably 0.5 g / cm 3 More preferably, 0.8 g / cm 3 More preferably, 1.0 g / cm 3Above. If the tap density of the positive electrode active material is lower than the above lower limit, the amount of dispersion medium required when the positive electrode active material layer is formed increases, and the required amount of conductive material and binder increases, the filling rate of the positive electrode active material in the positive electrode active material layer is limited, and the battery capacity may be limited. By using a composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. The larger the tap density is, the better. There is no particular upper limit. However, if it is too large, the diffusion of lithium ions using the liquid electrolyte in the positive electrode active material layer as a medium becomes rate-limiting, and sometimes the load characteristics are easily reduced. Therefore, the upper limit is preferably 4.0 g / cm 3 Below, more preferably 3.7 g / cm 3 Below, more preferably 3.5 g / cm 3 the following.

[0973] It should be noted that in the present disclosure, the tap density is the powder packing density (tap density) g / cm2 when 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass cylinder and vibrated 200 times with a stroke of about 20 mm. 3 Find out.

[0974] The median diameter d50 of the particles of the positive electrode active material (secondary particle diameter in the case where the primary particles are agglomerated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, further preferably 0.8 μm or more, and most preferably 1.0 μm or more, and preferably 30 μm or less, more preferably 27 μm or less, further preferably 25 μm or less, and most preferably 22 μm or less. If it is less than the above lower limit, a high tap density product may not be obtained; if it exceeds the upper limit, the diffusion of lithium in the particles takes time, which sometimes leads to a decrease in battery performance, or when the positive electrode of the battery is made, that is, the active material and the conductive material, the binder, etc. are slurried with a solvent and coated into a thin film, causing problems such as stripes. Here, by mixing two or more of the above-mentioned positive electrode active materials with different median diameters d50, the filling property during the production of the positive electrode can be further improved.

[0975] It should be noted that in the present disclosure, the median diameter d50 is measured using a known laser diffraction / scattering particle size distribution measuring device. When using LA-920 manufactured by HORIBA as a particle size distribution meter, as a dispersion medium used during measurement, a 0.1% by mass sodium hexametaphosphate aqueous solution is used, and after 5 minutes of ultrasonic dispersion, the measured refractive index is set to 1.24 for measurement.

[0976] In the case where the primary particles are agglomerated to form secondary particles, the average primary particle size of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and further preferably 0.2 μm or more, and the upper limit is preferably 5 μm or less, more preferably 4 μm or less, further preferably 3 μm or less, and most preferably 2 μm or less. If the upper limit is exceeded, it is difficult to form spherical secondary particles, which has an adverse effect on the powder filling property, or the specific surface area is greatly reduced, so the possibility of reduced battery performance such as output characteristics is sometimes increased. On the contrary, if it is lower than the lower limit, crystallization is usually not developed, so problems such as poor reversibility of charge and discharge may occur.

[0977] It should be noted that in the present disclosure, the primary particle size is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph with a magnification of 10,000 times, for any 50 primary particles, the longest value of the slice intercepted on a straight line in the horizontal direction by the left and right boundaries of the primary particles is obtained, and the average value is taken to obtain the primary particle size.

[0978] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 / g or more, and the upper limit is preferably 50m 2 / g or less, more preferably 40m 2 / g or less, more preferably 30m 2 If the BET specific surface area is smaller than this range, the battery performance is likely to decrease, and if it is larger than this range, it is difficult to increase the tap density, and coating properties may be problematic when the positive electrode active material layer is formed.

[0979] It should be noted that in the present disclosure, the BET specific surface area is defined as: using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.), after pre-drying the sample at 150°C for 30 minutes under nitrogen flow, using a nitrogen-helium mixed gas accurately adjusted so that the relative pressure of nitrogen to atmospheric pressure becomes 0.3, the value is measured by the nitrogen adsorption BET single-point method based on the gas flow method.

[0980] When the secondary battery of the present disclosure is used as a large lithium ion secondary battery for hybrid vehicles or distributed power sources, high output is required, and therefore the particles of the positive electrode active material preferably mainly contain secondary particles.

[0981] The particles of the positive electrode active material preferably contain 0.5 volume % to 7.0 volume % of secondary particles with an average particle size of 40 μm or less and an average primary particle size of 1 μm or less. By containing particles with an average primary particle size of 1 μm or less, the contact area with the liquid electrolyte becomes larger, which can make the diffusion of lithium ions between the electrode and the liquid electrolyte faster, and as a result, the output performance of the battery can be improved.

[0982] As a method for manufacturing positive electrode active materials, a common method for manufacturing inorganic compounds is used. In particular, various methods are considered for making spherical or ellipsoidal active materials, for example, the following methods can be cited: dissolving or crushing the raw material of the transition metal and dispersing it in a solvent such as water, adjusting the pH under stirring, making a spherical precursor and recovering it, drying it as needed, then adding LiOH, Li2CO3, LiNO3 and other Li sources and firing at high temperature to obtain the active material.

[0983] In order to manufacture the positive electrode, the above-mentioned positive electrode active materials can be used alone, or two or more of different compositions can be used together in any combination or ratio. As a preferred combination in this case, LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 O2, etc., LiMn2O4 or a combination in which a portion of the Mn is replaced with other transition metals, or LiCoO2 or a combination in which a portion of the Co is replaced with other transition metals.

[0984] From the aspect of high battery capacity, the content of the above-mentioned positive electrode active material is preferably 50% to 99.5% by mass of the positive electrode mixture, and more preferably 80% to 99% by mass. In addition, 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. In addition, the upper limit is preferably 99% by mass or less, and more preferably 98% by mass or less. When the content of the positive electrode active material in the positive electrode active material layer is low, the capacitance sometimes becomes insufficient. On the contrary, when the content is too high, the strength of the positive electrode is sometimes insufficient.

[0985] The positive electrode mixture preferably further includes a binder, a thickener, and a conductive material.

[0986] As the above-mentioned binder, any material can be used as long as it is a material safe for the solvent and liquid electrolyte used in the manufacture of the electrode, and examples thereof include: resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, and nitrocellulose; rubber polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), and ethylene-propylene rubber; styrene-butadiene-styrene block copolymers. or their hydrogenated products; thermoplastic elastomer polymers such as EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer or their hydrogenated products; soft resin polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, propylene-α-olefin copolymer; fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymer, tetrafluoroethylene-ethylene copolymer; polymer compositions having ion conductivity of alkali metal ions (particularly lithium ions), etc. These may be used alone or in any combination and ratio.

[0987] The content of binder is usually 0.1 mass % or more, preferably 1 mass % or more, more preferably 1.5 mass % or more, and usually 80 mass % or less, preferably 60 mass % or less, more preferably 40 mass % or less, most preferably 10 mass % or less. If the ratio of binder is too low, positive electrode active material cannot be fully maintained, and the mechanical strength of positive electrode is sometimes insufficient, and battery performance such as cycle characteristics is sometimes deteriorated. On the other hand, if the ratio of binder is too high, it sometimes leads to a reduction in battery capacity and conductivity.

[0988] Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, polyvinyl pyrrolidone, and salts thereof. One type may be used alone, or two or more types may be used in any combination and ratio.

[0989] The ratio of thickener to active material is usually 0.1 mass %, preferably 0.2 mass %, more preferably 0.3 mass %, and usually 5 mass %, preferably 3 mass %, more preferably 2 mass %. If it is lower than this scope, the coating property is significantly reduced sometimes. If it is higher than this scope, the proportion of active material in positive electrode active material layer is reduced, and sometimes the problem of reduced capacity of battery or the problem of increased resistance between positive electrode active materials is generated.

[0990] As the above-mentioned conductive material, any known conductive material can be used. As a specific example, metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, etc., carbon materials such as amorphous carbon such as needle coke, carbon nanotubes, fullerene, VGCF, etc. can be cited. It should be noted that they can be used alone, or two or more can be used in any combination and ratio. The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 1% by mass or more in the positive electrode active material layer. In addition, it is usually used in a manner containing 50% by mass or less, preferably 30% by mass or less, and more preferably 15% by mass or less. If the content is lower than this range, the conductivity is sometimes insufficient. On the contrary, if the content is higher than this range, the battery capacity is sometimes reduced.

[0991] As a solvent for forming the slurry, as long as it is a solvent that can dissolve or disperse the positive electrode active material, the conductive material, the binder, and the thickener used as needed, its type is not particularly limited, and any of aqueous solvents and organic solvents can be used. As aqueous solvents, for example, water, mixed solvents of alcohol and water, etc. can be cited. As organic solvents, for example, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; non-protonic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide, etc.

[0992] Examples of the material of the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, nickel, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum or alloys thereof, are preferred.

[0993] As the shape of the current collector, in the case of metal materials, metal foil, metal cylinder, metal coil, metal plate, metal film, metal roughening foil, porous metal net, stamping metal, foamed metal, etc. can be mentioned, and in the case of carbon materials, carbon plate, carbon film, carbon cylinder, etc. can be mentioned. Among these, metal film is preferred. It should be noted that the film can be appropriately formed into a mesh. The thickness of the film is arbitrary, usually more than 1 μm, preferably more than 3 μm, more preferably more than 5 μm, and usually less than 1 mm, preferably less than 100 μm, more preferably less than 50 μm. If the film is thinner than this range, the strength required as a current collector is sometimes insufficient. On the contrary, if the film is thicker than this range, sometimes the handling property is impaired.

[0994] In addition, from the perspective of reducing the electrical contact resistance between the current collector and the positive electrode active material layer, it is also preferred that a conductive additive be coated on the surface of the current collector. Examples of the conductive additive include carbon or noble metals such as gold, platinum, and silver.

[0995] The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, and the value of (the thickness of the positive electrode active material layer on one side before the liquid electrolyte is injected) / (the thickness of the current collector) is preferably less than 20, more preferably less than 15, and most preferably less than 10. In addition, it is preferably more than 0.5, more preferably more than 0.8, and most preferably more than 1. If it exceeds this range, the current collector sometimes generates heat caused by Joule heat during high current density charging and discharging. If it is less than this range, the volume ratio of the current collector to the positive electrode active material increases, and the capacity of the battery sometimes decreases.

[0996] The positive electrode can be manufactured according to conventional methods. For example, a method can be cited in which a slurry-like positive electrode mixture is prepared by adding the above-mentioned binder, thickener, conductive material, solvent, etc. to the above-mentioned positive electrode active material, applying the slurry to the collector, and pressing it after drying to obtain a high density.

[0997] The density increase can be achieved by hand pressing, roll pressing, etc. The density of the positive electrode active material layer is preferably 1.5 g / cm 3 More preferably, 2 g / cm 3 More preferably, 2.2 g / cm 3 More than 5 g / cm 3 Below, more preferably 4.5g / cm 3 Below, more preferably 4g / cm 3 If the range is exceeded, the permeability of the liquid electrolyte to the collector / active material interface is reduced, and the charge and discharge characteristics under high current density are reduced, and sometimes high output cannot be obtained. In addition, if it is less than this range, the conductivity between active materials is reduced, and sometimes the battery resistance increases and high output cannot be obtained.

[0998] In the case of using the liquid electrolyte used in the battery of the present invention or the liquid electrolyte used in the alkali metal secondary battery of the present invention, the area of ​​the positive electrode active material layer is preferably larger than the outer surface area of ​​the battery casing from the perspective of high output and improved stability at high temperature. Specifically, the sum of the electrode areas of the positive electrode is preferably 15 times or more in terms of area ratio relative to the surface area of ​​the outer packaging of the secondary battery, and more preferably 40 times or more. Regarding the outer surface area of ​​the battery casing, in the case of a square shape with a bottom, it refers to the total area calculated by calculating the length, width and thickness dimensions of the shell part filled with the power generation element except the protruding part of the terminal. In the case of a cylindrical shape with a bottom, it refers to the geometric surface area of ​​the shell part filled with the power generation element except the protruding part of the terminal. The sum of the electrode mixture area of ​​the positive electrode refers to the geometric surface area of ​​the positive electrode mixture layer facing the mixture layer containing the negative electrode active material. In a structure where a positive electrode mixture layer is formed on both sides by a collector foil, it refers to the sum of the areas calculated for each face.

[0999] The thickness of the positive electrode plate is not particularly limited. From the perspective of high capacity and high output, the thickness of the composite layer after deducting the thickness of the metal foil of the core material is preferably 10 μm or more, more preferably 20 μm or more, and preferably 500 μm or less, more preferably 450 μm or less, relative to a single side of the collector as the lower limit.

[1000] In addition, a positive electrode plate having a substance having a different composition attached to the surface of the positive electrode plate may also be used. Examples of the surface-attached substance include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; carbon; and the like.

[1001] (Diaphragm)

[1002] The secondary battery of the present disclosure preferably further includes a separator.

[1003] The material and shape of the above-mentioned separator are not particularly limited as long as the liquid electrolyte is stable and the liquid retention is excellent, and a known separator can be used. Among them, it is preferred to use a porous sheet or non-woven fabric-like material formed of a material that is stable to the liquid electrolyte used in the battery of the present invention or the liquid electrolyte used in the alkali metal secondary battery of the present invention, using resin, glass fiber, inorganic material, etc., and having excellent liquid retention.

[1004] As materials for the resin and glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamide, polytetrafluoroethylene, polyethersulfone, glass filters, etc. can be used. Polypropylene / polyethylene two-layer membranes, polypropylene / polyethylene / polypropylene three-layer membranes, etc. These materials can be used alone or in any combination and ratio.

[1005] Among them, the separator is preferably a porous sheet or nonwoven fabric made of polyolefin such as polyethylene or polypropylene from the viewpoint of good permeability of the liquid electrolyte and good shutdown effect.

[1006] The thickness of the separator is arbitrary, usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. If the separator is too thin compared to the above range, the insulation and mechanical strength may sometimes be reduced. In addition, if it is too thick compared to the above range, the battery performance such as rate characteristics may sometimes be reduced, and the energy density of the liquid electrolyte battery as a whole may sometimes be reduced.

[1007] In addition, when a porous material such as a porous sheet or nonwoven fabric is used as a diaphragm, the porosity of the diaphragm is arbitrary, usually 20% or more, preferably 35% or more, more preferably 45% or more, and usually 90% or less, preferably 85% or less, more preferably 75% or less. If the porosity is too small compared to the above range, there is a tendency for the membrane resistance to increase and the rate characteristics to deteriorate. In addition, if it is too large compared to the above range, there is a tendency for the mechanical strength of the diaphragm to decrease and the insulation to decrease.

[1008] In addition, the average pore size of the diaphragm is also arbitrary, usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore size exceeds the above range, short circuit is likely to occur. In addition, if it is less than the above range, the membrane resistance sometimes increases and the rate characteristics decrease.

[1009] On the other hand, as inorganic materials, oxides such as aluminum oxide and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and materials in the form of particles or fibers are used.

[1010] As a form, a non-woven fabric, a woven fabric, a microporous film or other thin film-shaped material is used. In the case of a thin film, a film with a pore size of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm is preferably used. In addition to the above-mentioned independent thin film shape, a separator formed by forming a composite porous layer containing particles of the above-mentioned inorganic substance on the surface of the positive electrode and / or the negative electrode using a resin binder can also be used.

[1011] For example, a fluororesin is used as a binder, and alumina particles having a particle size of 90% less than 1 μm are formed into a porous layer on both sides of the positive electrode.

[1012] (Battery Design)

[1013] The electrode group may be any one of a laminated structure in which the separator is interposed between the positive electrode plate and the negative electrode plate, and an electrode group in which the positive electrode plate and the negative electrode plate are wound in a spiral shape with the separator interposed therebetween. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less.

[1014] If the electrode group occupancy is less than the above range, the battery capacity will be reduced. In addition, if it exceeds the above range, the void space is small, the battery temperature rises, the components expand, the vapor pressure of the liquid component of the electrolyte increases, and the internal pressure rises, which will reduce the various characteristics of the battery such as the charge and discharge repetition performance and high temperature storage, and the gas release valve that releases the internal pressure to the outside may sometimes work.

[1015] The current collecting structure is not particularly limited. In order to more effectively improve the charge-discharge characteristics of high current density caused by the liquid electrolyte used in the battery of the present invention or the liquid electrolyte used in the alkali metal secondary battery of the present invention, it is preferred to adopt a structure that reduces the resistance of the wiring part or the joint part. In the case of reducing the internal resistance in this way, the effect of using the liquid electrolyte used in the battery of the present invention or the liquid electrolyte used in the alkali metal secondary battery of the present invention can be particularly well exerted.

[1016] When the electrode group has the above-mentioned laminated structure, it is preferred to use a structure formed by bundling the metal core parts of each electrode layer and welding them to the terminal. When the area of ​​a piece of electrode becomes larger, since the internal resistance becomes larger, it is also preferred to set multiple terminals in the electrode to reduce the resistance. When the electrode group has the above-mentioned winding structure, multiple lead structures can be set in the positive electrode and the negative electrode respectively, and bundled on the terminal, thereby reducing the internal resistance.

[1017] The material of the shell is not particularly limited as long as it is a material that is stable to the liquid electrolyte used. Specifically, metals such as nickel-plated steel, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminated film (laminated film) of resin and aluminum foil are used. From the perspective of lightweight, it is preferred to use metals such as aluminum or aluminum alloys and laminated films.

[1018] In the case of using metal, there can be mentioned a case in which metals are welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed package structure; or a case in which the above metals are used to form a riveted structure through a resin gasket. In the case of using the above laminated film, there can be mentioned a case in which a sealed package structure is formed by thermally bonding resin layers to each other. In order to improve the sealing performance, a resin different from the resin used in the laminated film can also be sandwiched between the above resin layers. In particular, in the case of forming a sealed structure by thermally bonding the resin layers through the collector terminal, since the metal is bonded to the resin, it is preferred to use a resin having a polar group or a modified resin into which a polar group is introduced as the sandwiched resin.

[1019] The secondary battery of the present disclosure may have any shape, for example, cylindrical, square, laminated, button, large, etc. The shape and structure of the positive electrode, negative electrode, and separator may be changed according to the shape of each battery.

[1020] Example

[1021] Hereinafter, the present disclosure will be specifically described based on Examples. In the following Examples, "parts" and "%" mean "parts by mass" and "% by mass" respectively, unless otherwise specified.

[1022] Types of Fluoropolymers

[1023] Polymer A:

[1024] Fluorinated copolymer containing vinylidene fluoride (VdF) units and tetrafluoroethylene (TFE) units

[1025] VdF / TFE=81 / 19 (mol%)

[1026] Weight average molecular weight: 970000

[1027] Melting point: 128°C

[1028] Polymer B:

[1029] Fluorinated copolymer containing VdF units and trifluoroethylene (TrFE) units

[1030] VdF / TrFE=80 / 20 (mol%)

[1031] Weight average molecular weight: 720000

[1032] Melting point: 165℃

[1033] Polymer C:

[1034] Fluorine copolymer containing VdF unit, TrFE unit and chlorotrifluoroethylene (CTFE) unit

[1035] VdF / TrFE / CTFE=65 / 28 / 7 (mol%)

[1036] Weight average molecular weight: 650000

[1037] Melting point: 170℃

[1038] Polymer D:

[1039] Fluorine copolymer containing VdF units and acrylic acid units

[1040] VdF / acrylic acid=99 / 1 (mol%)

[1041] Weight average molecular weight: 1120000

[1042] Melting point: 161°C

[1043] Polymer E:

[1044] Fluorinated copolymer containing VdF units and 2,3,3,3-tetrafluoropropylene units

[1045] VdF / 2,3,3,3-tetrafluoropropylene=77 / 23

[1046] Weight average molecular weight: 480000

[1047] Tg: -13℃

[1048] Mooney viscosity: ML1+10(121℃): 25

[1049] Polymer F:

[1050] Fluorinated copolymer containing VdF units and perfluoro-(2,9,9-trihalo-5-trifluoromethyl-3,6-dioxa-8-heptene) (AEHF-1) units

[1051] VdF / AEHF-1=81.4 / 18.6

[1052] Weight average molecular weight: 950000

[1053] Tg: -27℃

[1054] Mooney viscosity: (ML1+10(121℃)): 15

[1055] It should be noted that AEHF-1 is a compound represented by the following general formula.

[1056] [Chemistry 85]

[1057]

[1058] Polymer G: (Polymer of Comparative Example)

[1059] Fluorine copolymer containing VdF units and hexafluoropropylene (HFP) units

[1060] VdF / HFP=95:5

[1061] Weight average molecular weight: 870000

[1062] Melting point: 141°C

[1063] Types of fluoroethers

[1064] (E-1)HCF2-CF2-O-CH2-CF2-CF2H

[1065] (E-2)HCF2-CF2-O-CH2-CH2-CH3

[1066] (E-3)HCF2-CF2-O-CH2-CH2-CH2-CH3

[1067] (E-4)HCF2-CF2-O-CH2-CF3

[1068] (E-5)HCF2-CF2-O-CH2-CH2-O-CF2-CF2H

[1069] (E-6)CF3-CF2-CH2-O-CH2-CF2-CF3

[1070] Lithium salt

[1071] LiPF6

[1072] LiFSI: Lithium bis(fluorosulfonyl)imide

[1073] LiBOB: Lithium bis(oxalate)borate

[1074] Cyclic carbonate

[1075] EC: Ethylene carbonate

[1076] FEC: Fluoroethylene carbonate

[1077] Chain carbonate

[1078] EMC: Ethyl Methyl Carbonate

[1079] DMC: dimethyl carbonate

[1080] Other solvents

[1081] GBL: gamma-butyrolactone

[1082] DME: dimethoxyethane

[1083] (Method for measuring weight average molecular weight)

[1084] The measurement was performed by gel permeation chromatography (GPC). AS-8010 and CO-8020 columns (three GMHHR-H columns connected in series) manufactured by Tosoh Corporation and RID-10A manufactured by Shimadzu Corporation were used, and dimethylformamide (DMF) as a solvent was passed through at a flow rate of 1.0 ml / min, and the result was calculated from the measured data (reference: polystyrene).

[1085] (Measurement method of Tg)

[1086] Using a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC823e), 10 mg of the sample was heated at 20°C / min to obtain a DSC curve, and the temperature of the intersection of the extended line of the baseline before and after the secondary transition of the DSC curve and the tangent line at the inflection point of the DSC curve was taken as the glass transition temperature (Tg).

[1087] (Method for measuring Mooney viscosity)

[1088] <Mooney viscosity (ML1+10 (121°C, 140°C))>

[1089] The measurement was performed in accordance with ASTM-D1646-15 and JIS K6300-1:2013.

[1090] Measuring equipment: MV2000E manufactured by ALPHA TECHNOLOGIES

[1091] Rotor speed: 2rpm

[1092] Measuring temperature: 121℃, 140℃

[1093] (Examples 1 to 17, Comparative Examples 1 to 6)

[1094] (Coating on current collector)

[1095] 8 parts by weight of various fluoropolymers were dissolved in N-methyl-2-pyrrolidone (NMP) as a solvent to obtain protective film-forming compositions.

[1096] The protective film forming composition was applied to the upper part of the copper foil (15 μm) as the negative electrode collector with a scraper at a thickness of 5 μm. The applied composition was dried at about 100°C. The electrode was cut into a size of 40 mm × 40 mm. The thickness of the coating after drying was 0.4 μm, and the density of the coating layer after drying was 1.6 g / cm 3 In addition, in Comparative Examples 2 and 3, the copper foil which did not perform this coating was used as an electrode.

[1097] In addition, LiCoO2, a conductive agent (Super-P, Timcal Ltd.), polyvinylidene fluoride (PVdF), and NMP were mixed to obtain a positive electrode composition. In this positive electrode composition, the mixing weight ratio of LiCoO2, the conductive agent, and PVdF was 97:1.5:1.5.

[1098] The above positive electrode composition was coated on the upper part of an aluminum foil (thickness: about 15 μm) and dried under vacuum at about 110 °C to obtain a positive electrode. The obtained positive electrode was cut into a size of 39 mm × 39 mm to fabricate an electrode.

[1099] A polyethylene / polypropylene separator was interposed between the positive electrode and the negative electrode current collector foil obtained through the above process to manufacture a laminated battery. Here, between the above positive electrode and the negative electrode, various electrolytes were obtained from the combinations of Li salts and solvents listed in Table 1.

[1100] <High-temperature storage characteristic evaluation test>

[1101] The button battery manufactured above was charged at a constant current-constant voltage to 4.4 V (hereinafter referred to as CC / CV charging) (0.1C cut-off) at 25 °C with a current equivalent to 0.2C, and then discharged at a constant current of 0.2C to 3V. This was regarded as one cycle, and the initial discharge capacity was obtained from the discharge capacity of the third cycle. Here, 1C represents the current value for discharging the reference capacity of the battery in 1 hour. For example, 0.2C represents 1 / 5 of this current value. After charging again by CC / CV (0.1C cut-off) to 4.4V, high-temperature storage was carried out under the conditions of 65 °C for 36 hours. After the battery was fully cooled, the volume was measured by the Archimedes method, and the amount of gas generated was obtained from the volume change before and after storage. Then, it was discharged at 0.2C to 3V at 25 °C, the remaining capacity after high-temperature storage was measured, and the ratio of the remaining capacity to the initial discharge capacity was obtained and used as the storage capacity retention rate (%).

[1102] (Remaining capacity) / (Initial discharge capacity) × 100 = Storage capacity retention rate (%)

[1103] <Evaluation of IV resistance>

[1104] The battery for which the evaluation of the initial discharge capacity was completed was charged at a constant current of 0.2C to half of the initial discharge capacity at 25 °C. It was discharged at 2.0C at 25 °C, and the voltage at 10 seconds was measured. The resistance was calculated from the voltage drop during discharge and used as the IV resistance. The resistance increase rate (%) was calculated from the resistance before and after high-temperature storage.

[1105] (Resistance after high-temperature storage) / (Resistance before high-temperature storage) × 100 = Resistance increase rate (%)

[1106] <Measurement of the Dissolution Amount of Transition Metal from the Positive Electrode>

[1107] The battery after the storage capacity measurement was disassembled, the negative electrode was cleaned with DMC, and the transition metal precipitated on the negative electrode was taken out. Ni was quantified in the DMC solution containing transition metals by ICP emission analysis, thereby calculating the dissolution amount of transition metals. It should be noted that the dissolution amount of Ni in the positive electrode is assumed to be the precipitation amount on the negative electrode. The results are shown in Table 1.

[1108] (Thickness of the coating layer after drying)

[1109] The thickness of the coating layer after drying was calculated from the weight of the fluoropolymer in the protective film-forming composition and the thickness of the coating layer before drying.

[1110] (Density of the coating layer after drying)

[1111] The weight of the coating layer was calculated from the weight change before and after drying, and the weight was divided by the volume of the coating layer after drying to calculate the density of the coating layer after drying.

[1112]

[1113] (Examples 18 to 26, Comparative Examples 7 to 10)

[1114] (Coating on Li metal)

[1115] 8 parts by weight of various fluoropolymers were dissolved in N-methyl-2-pyrrolidone (NMP) as a solvent to obtain protective film-forming compositions.

[1116] Use a scraper to apply the protective film-forming composition to the upper part of the lithium metal film (thickness: about 15 μm) with a thickness of about 8 μm. After drying the above-mentioned coating result at about 25°C, heat treatment is performed in vacuum at about 40°C to produce a lithium negative electrode with a protective film formed on the lithium metal. Cut into a size of 20 mm × 20 mm to make an electrode. The thickness of the coating after drying is 0.4 μm, and the density of the coating layer after drying is 1.6 g / cm 3 .

[1117] In addition, mixed LiNi 0.8 Mn 0.1 Co 0.1 O2, a conductive agent (Super-P, Timcal Ltd.), polyvinylidene fluoride (PVdF) and NMP to obtain a positive electrode composition. In the positive electrode composition, the mixing weight ratio of LiCoO2, the conductive agent and PVDF is 97.5:1.25:1.25.

[1118] The above-mentioned positive electrode composition was coated on the upper part of an aluminum foil (thickness: about 15 μm) and dried under vacuum at about 110 °C to obtain a positive electrode. The obtained positive electrode was cut into a size of 19 mm × 19 mm to fabricate an electrode.

[1119] A polyethylene / polypropylene separator was interposed between the positive electrode obtained through the above process and a lithium metal negative electrode to fabricate a laminated battery. Here, between the above positive electrode and the negative electrode, various electrolytes were obtained from the combinations of the Li salts and solvents listed in Table 2.

[1120] <High-temperature storage property evaluation test>

[1121] The button battery fabricated above was charged at a constant current-constant voltage to 4.3 V (hereinafter referred to as CC / CV charging) (0.1C cut-off) at 25 °C with a current equivalent to 0.2C, and then discharged at a constant current of 0.2C to 3V. This was regarded as one cycle, and the initial discharge capacity was obtained from the discharge capacity of the third cycle. Here, 1C represents the current value for discharging the reference capacity of the battery in 1 hour. For example, 0.2C represents 1 / 5 of this current value. After charging again by CC / CV (0.1C cut-off) to 4.3V, high-temperature storage was carried out under the conditions of 45 °C for 48 hours. After the battery was sufficiently cooled, the volume was measured by the Archimedes method, and the amount of gas generated was obtained from the volume change before and after storage. Then, it was discharged at 0.2C to 3V at 25 °C, the residual capacity after high-temperature storage was measured, and the ratio of the residual capacity to the initial discharge capacity was obtained and used as the storage capacity retention rate (%).

[1122] (Residual capacity) / (Initial discharge capacity) × 100 = Storage capacity retention rate (%)

[1123] <Evaluation of IV resistance>

[1124] The battery for which the evaluation of the initial discharge capacity was completed was charged at a constant current of 0.2C at 25 °C to half of the initial discharge capacity. It was discharged at 2.0C at 25 °C, and the voltage at 10 seconds was measured. The resistance was calculated from the voltage drop during discharge and used as the IV resistance. The resistance increase rate (%) was calculated from the resistance before and after high-temperature storage.

[1125] (Resistance after high-temperature storage) / (Resistance before high-temperature storage) × 100 = Resistance increase rate (%)

[1126] <Determination of the elution amount of transition metals in the positive electrode>

[1127] The battery after the storage capacity measurement was disassembled, the negative electrode was cleaned with DMC, and the transition metal precipitated on the negative electrode was taken out. The DMC solution containing the transition metal was quantitatively analyzed by ICP emission analysis to determine the amount of transition metal dissolved. It should be noted that the amount of Mn dissolved from the positive electrode is assumed to be the amount of precipitation on the negative electrode. The results are shown in Table 2.

[1128] (Thickness of the coating layer after drying)

[1129] The thickness of the coating layer after drying was calculated from the weight parts of the fluoropolymer in the protective film-forming composition and the thickness of the coating layer on the lithium metal foil.

[1130] (Density of the coating layer after drying)

[1131] The weight of the coating layer was calculated from the weight change before and after drying, and the weight was divided by the volume of the coating layer after drying to calculate the density of the coating layer after drying.

[1132]

[1133] The results in Tables 1 and 2 show that the secondary battery of the present invention has excellent effects in terms of capacity retention, gas generation, resistance increase rate, Mn dissolution, and Ni dissolution, and suppresses deterioration of the negative electrode, thereby achieving an effect of improving battery life.

[1134] Industrial Applicability

[1135] The secondary battery of the present disclosure can be used as various common secondary batteries.

Claims

1. A secondary battery comprising a negative electrode having a fluoropolymer laminated on a layer containing a metal and a liquid electrolyte, wherein: The metal is at least one selected from lithium, sodium, magnesium and zinc, The fluoropolymer is a copolymer having a vinylidene fluoride unit (A) and a structural unit (B) derived from at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, a monomer represented by the general formula (1), a monomer represented by the general formula (2) and a monomer represented by the general formula (3). The liquid electrolyte contains a fluorinated ether, [Chemistry 1] In the formula, Rf 1 A linear or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, wherein the fluorinated alkyl group and the fluorinated alkoxy group may contain an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more; [Chemistry 2] R 2 A linear or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, wherein the fluorinated alkyl group and the fluorinated alkoxy group may contain an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more; [Chemistry 3] In the formula, R 1 , R 2 and R 3 Each is independently a hydrogen atom, a chlorine atom or an alkyl group having 1 to 5 carbon atoms; X is an atomic group having a molecular weight of 500 or less and having a single bond or a main chain composed of 1 to 20 atoms; and Y represents an inorganic cation and / or an organic cation.

2. The secondary battery according to claim 1, wherein In the copolymer, the content of vinylidene fluoride is 30 mol% to 99.5 mol% based on all monomer units.

3. The secondary battery according to claim 1 or 2, wherein: The fluorinated ether is a compound represented by the following general formula (5): [Chemistry 4] HCF2CF2-OR (5) R is an alkyl group which may contain an ether group, or a fluorinated alkyl group which may contain an ether group.

4. The secondary battery according to claim 3, wherein: The compound represented by the general formula (5) is at least one compound selected from the group consisting of compounds represented by the following general formula: [Chemistry 5] ·HCF2-CF2-O-CH2-CF2-CF2H ·HCF2-CF2-O-CH2-CH2-CH3 ·HCF2-CF2-O-CH2-CH2-CH2-CH3 ·HCF2-CF2-O-CH2-CF3 ·HCF2-CF2-O-CH2-CH2-O-CF2-CF2H.

5. A secondary battery comprising a negative electrode comprising a laminate in which a fluoropolymer is directly laminated on a current collector, wherein: The fluoropolymer is a copolymer having a vinylidene fluoride unit (A) and a structural unit (B) derived from at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, a monomer represented by the general formula (1), a monomer represented by the general formula (2) and a monomer represented by the general formula (3). The liquid electrolyte contains a fluorinated ether, [Chemistry 6] In the formula, Rf 1 A linear or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, wherein the fluorinated alkyl group and the fluorinated alkoxy group may contain an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more; [Chemistry 7] R 2 A linear or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, wherein the fluorinated alkyl group and the fluorinated alkoxy group may contain an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more; [Chemistry 8] In the formula, R 1 , R 2 and R 3 Each is independently a hydrogen atom, a chlorine atom or an alkyl group having 1 to 5 carbon atoms; X is an atomic group having a molecular weight of 500 or less and having a single bond or a main chain composed of 1 to 20 atoms; and Y represents an inorganic cation and / or an organic cation.

6. The secondary battery according to claim 5, wherein: In the copolymer, the content of vinylidene fluoride is 30 mol% to 99.5 mol% based on all monomer units.

7. The secondary battery according to claim 5 or 6, wherein: The fluorinated ether is a compound represented by the following general formula (5): [Chemistry 9] HCF2CF2-OR (5) R is an alkyl group which may contain an ether group, or a fluorinated alkyl group which may contain an ether group.

8. The secondary battery according to claim 7, wherein: The compound represented by the general formula (5) is at least one compound selected from the group consisting of compounds represented by the following general formula: [Chemistry 10] ·HCF2-CF2-O-CH2-CF2-CF2H ·HCF2-CF2-O-CH2-CH2-CH3 ·HCF2-CF2-O-CH2-CH2-CH2-CH3 ·HCF2-CF2-O-CH2-CF3 ·HCF2-CF2-O-CH2-CH2-O-CF2-CF2H.

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