secondary battery

Abstract

In a battery using a negative electrode made of metal, the battery life is improved by reducing the amount of gas generated, reducing resistance, and reducing the amount of precipitation of metal elements such as Mn and Ni in the positive electrode in the negative electrode. The secondary battery has a negative electrode in which a fluorine polymer is laminated on a layer containing metal and has a liquid electrolyte, wherein the metal is at least one selected from lithium, sodium, magnesium, and zinc, and the fluorine polymer is a copolymer having a vinylidene fluoride unit (A) and a constituent unit (B) derived from 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 is characterized by containing a fluorinated ether.

Description

Technology Field

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

[0002] In recent years, research and development of alkali metal secondary batteries using alkali metals with high theoretical capacity as the negative electrode has been underway, with the goal of further increasing the energy density of alkali metal secondary batteries, which are represented by lithium secondary batteries.

[0003] However, in the case of secondary batteries using alkali metals, there was a problem that the battery life was shortened when charging and discharging were repeated. In addition, there was also a problem that the battery life was reduced as the transition metal in the positive electrode active material leached out and deposited on the negative electrode.

[0004] Patent Document 1 discloses an electrode surface-coated with a polyvinylidene fluoride polymer on a lithium metal surface.

[0005] Patent Document 2 discloses a composition for forming a protective film containing a vinylidene fluoride-hexafluoropropylene copolymer. It describes forming a protective film by coating such a composition for forming a protective film onto a lithium metal thin film layer.

[0006] Patent document 3 discloses that, in a battery using lithium metal as an electrode, an electrolyte solution containing a fluorinated ether compound is used.

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

[0008] Patent document 5 discloses an electrode surface-coated with a polyvinylidene fluoride polymer on a lithium metal surface.

[0009] Patent documents 6 and 7 disclose manufacturing an electrode using a binder composition containing a polyvinylidene fluoride polymer and an electrode active material. Prior art literature

[0010] International Publication No. 2017 / 140649 Japanese Patent Publication No. 2019-515481 International Publication No. 2020 / 246579 International Publication No. 2014 / 132579 International Publication No. 2021 / 123151 International Publication No. 2018 / 092676 International Publication No. 2021 / 015229 The problem to be solved

[0011] The present disclosure aims to improve battery life in a battery using a negative electrode made of metal by reducing the amount of gas generated, reducing resistance, and reducing the amount of precipitation of metal elements such as Mn and Ni in the positive electrode in the negative electrode. means of solving the problem

[0012] The present disclosure is,

[0013] It is a secondary battery having a negative electrode in which a fluorine polymer is laminated on a metal-containing layer and a liquid electrolyte, and

[0014] The metal is at least one selected from lithium, sodium, magnesium, and zinc, and

[0015] The fluorine polymer comprises vinylidene fluoride units (A) and,

[0016] A copolymer having a constituent unit (B) derived from 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).

[0017] The liquid electrolyte is a secondary battery characterized by containing fluorinated ether.

[0018]

[0019] During the meal, Rf 1The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and the fluorinated alkyl group and the fluorinated alkoxy group may both include an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more.

[0020]

[0021] Rf 2 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and when the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms.

[0022]

[0023] During the meal, 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 with a molecular weight of 500 or less, in which a single bond or main chain consists of 1 to 20 atoms. Y represents an inorganic cation and / or an organic cation.

[0024] The copolymer preferably has a vinylidene fluoride content of 30 to 99.5 mol% based on the total monomer unit.

[0025] The above fluorinated ether is preferably a compound represented by the following general formula (5).

[0026]

[0027] (R is an alkyl group that may contain an ether group, or a fluorinated alkyl group that may contain an ether group)

[0028] The compound represented by the above general formula (5) is preferably at least one compound selected from the group consisting of compounds represented by the following general formula.

[0029]

[0030] The present disclosure is a secondary battery having a negative electrode comprising a laminate in which a fluorine polymer is directly laminated on a current collector, and

[0031] The fluorine polymer comprises vinylidene fluoride units (A) and,

[0032] A copolymer having a constituent unit (B) derived from 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).

[0033] The liquid electrolyte is also a secondary battery characterized by containing fluorinated ether.

[0034]

[0035] During the meal, Rf 1 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and the fluorinated alkyl group and the fluorinated alkoxy group may both include an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more.

[0036]

[0037] Rf 2 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and when the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms.

[0038]

[0039] During the meal, R 1 , R 2 and R 3Each is independently a hydrogen atom, a chlorine atom, or an alkyl group having 1 to 5 carbon atoms. X is an atomic group with a molecular weight of 500 or less, in which a single bond or main chain consists of 1 to 20 atoms. Y represents an inorganic cation and / or an organic cation.

[0040] The copolymer preferably has a vinylidene fluoride content of 30 to 99.5 mol% based on the total monomer unit.

[0041] The above fluorinated ether is preferably a compound represented by the following general formula (5).

[0042]

[0043] (R is an alkyl group that may contain an ether group, or a fluorinated alkyl group that may contain an ether group)

[0044] The compound represented by the above general formula (5) is preferably at least one compound selected from the group consisting of compounds represented by the following general formula.

[0045] Effects of the invention

[0046] According to the present disclosure, effects such as the leaching of transition metals in the positive electrode active material, a reduction in gas generation, a reduction in resistance, and the suppression of deterioration of the positive electrode by reducing the amount of precipitation of metal elements such as Mn and Ni in the negative electrode can be obtained, thereby improving battery life. Specific details for implementing the invention

[0047] The present disclosure will be described in detail below.

[0048] The present disclosure relates to a negative electrode having a coating layer formed by a fluorine-containing polymer having a specific composition, and using a liquid electrolyte containing a fluorinated ether. By forming such a coating layer and also using a specific liquid electrolyte, the aforementioned problem can be particularly suitably improved compared to a secondary battery as described in the aforementioned patent document.

[0049] The negative electrode used in the secondary battery of the present disclosure has a coating layer made of a fluorine polymer as described in detail below. Here, the negative electrode may be formed by directly forming a coating made of a fluorine polymer on a negative electrode material mainly composed of a metal such as lithium metal (first embodiment), or it may be formed by forming a coating layer made of a fluorine polymer on a current collector (second embodiment).

[0050] An electrode having a structure in which a coating layer made of a fluorine polymer is formed on a current collector described as the second embodiment above can also obtain the above-described effect.

[0051] In the second embodiment above, a layer made of a negative electrode material made of metal is not provided on the current collector, and a coating layer made of a fluorine polymer is formed directly to serve as the negative electrode. In this case, when such a negative electrode is laminated with other layers constituting the battery, such as a positive electrode, and then charging is performed, a metal layer such as lithium metal is formed on the current collector due to the electrode reaction during charging. This metal layer is formed between the current collector and the fluorine polymer layer. That is, by performing charging, a negative electrode is formed in which a coating made of a fluorine polymer is formed directly on a layer made of a metal such as lithium metal, and this is the same as the negative electrode of the first embodiment described above.

[0052] Therefore, the effects of the present disclosure are appropriately exerted.

[0053] It is presumed that in the negative electrode of the secondary battery of the present disclosure, a particularly suitable effect is obtained by using a fluorine-containing polymer containing the vinylidene fluoride unit (A) and constituent unit (B) described above, due to the interaction between a specific fluorine polymer layer and lithium ions, which enables uniform metal precipitation and suppresses the occurrence of dendrites.

[0054] Cited literature 6 and 7 disclose the use of a similar polymer in the battery field.

[0055] These are clearly different from the present disclosure in that they do not have a negative electrode in which a fluorine polymer is laminated on a metal layer.

[0056] Below, the polymer used in the present disclosure is described in detail, and then the negative electrode and the battery are described in detail.

[0057] In the present disclosure, the negative electrode is laminated with a fluorine polymer described in detail below. By having such a coating, the above-described effect is obtained. In the following description, a fluorine polymer having tetrafluoroethylene, trifluoroethylene, and chlorotrifluoroethylene as constituent units (B) is hereinafter referred to as fluorine polymer 1.

[0058] In addition, a fluorine polymer having a monomer represented by general formula (1) or a monomer represented by general formula (2) as a constituent unit (B) is hereinafter referred to as fluorine polymer 2, and a fluorine polymer having a monomer represented by general formula (3) as a constituent unit (B) is hereinafter referred to as fluorine polymer 3.

[0059] In addition, the following description does not exclude the use of fluorine polymers such as those corresponding to 2 or more of fluorine polymers 1, 2, and 3. That is, any 2 or more monomers selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, monomers represented by general formula (1), monomers represented by general formula (2), and monomers represented by general formula (3) may be used in combination.

[0060] As explained in detail below, the preferred range of copolymerization ratios varies depending on the copolymerization component used, but overall, it is preferable that the vinylidene fluoride content be 30 to 99.5 mol% with respect to the monomer unit.

[0061] (Fluoropolymer 1)

[0062] Fluoropolymer 1 has a constituent unit based on at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, and chlorotrifluoroethylene.

[0063] The content of VdF units of the fluorine polymer 1 is preferably 57.0 mol% or more with respect to the total monomer units, more preferably 60.0 mol% or more, and even more preferably 63.0 mol% or more. Preferably 95.0 mol% or less, more preferably 90.0 mol% or less, and most preferably 85.0 mol% or less.

[0064] The content of at least one monomer selected from the group consisting of tetrafluoroethylene, trifluoroethylene, and chlorotrifluoroethylene of the fluorine polymer 1 is, with respect to the total monomer unit, preferably 5.0 mol% or more, more preferably 8.0 mol% or more, particularly preferably 10.0 mol% or more, most preferably 15 mol% or more, preferably 43.0 mol% or less, more preferably 40.0 mol% or less, even more preferably 38.0 mol% or less, and particularly preferably 37.0 mol% or less.

[0065] As for the fluorine polymer 1, among them, a fluorine polymer 1 composed 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 is preferred. That is, the fluorine polymer 1 is a binary copolymer composed only of VdF units and TFE units, or a ternary copolymer composed only of VdF units, TFE units, and non-fluorinated monomer units, and it is preferred that the fluorine polymer 1 does not include fluorinated monomer units other than VdF units and TFE units.

[0066] When the fluorine polymer 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, even more preferably 63 / 37 to 88 / 12, and particularly preferably 63 / 37 to 85 / 15.

[0067] The weight average molecular weight (converted to polystyrene) of the fluorine polymer 1 is preferably 161,000 to 276,000, more preferably 322,000 to 253,000, and even more preferably 600,000 to 200,000. The weight average molecular weight can be measured at 50°C using dimethylformamide as a solvent by gel permeation chromatography (GPC).

[0068] The number average molecular weight (converted to polystyrene) of the fluorine polymer 1 is preferably 70,000 to 1,200,000, and more preferably 1,400,000 to 1,100,000. The number average molecular weight can be measured at 50°C using dimethylformamide as a solvent by gel permeation chromatography (GPC).

[0069] The melting point of the fluorine polymer 1 is preferably 100 to 170°C, more preferably 110 to 165°C, and even more preferably 120 to 163°C. The melting point is determined as the temperature corresponding to the maximum value in the heat of fusion curve when the temperature is raised from 30°C to 220°C at a rate of 10°C / min using a differential scanning calorimetry (DSC) device, then lowered to 30°C at a rate of 10°C / min, and then raised again to 220°C at a rate of 10°C / min.

[0070] (Fluoropolymer 2)

[0071] Fluoropolymer 2 is a fluoropolymer having at least one copolymer 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).

[0072]

[0073] During the meal, Rf 1The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and the fluorinated alkyl group and the fluorinated alkoxy group may both include an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more.

[0074]

[0075] Rf 2 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and when the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms.

[0076] A fluorine polymer comprising at least one copolymer 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 it is easy to obtain uniformity during coating.

[0077] The fluorine-containing monomer represented by the general formula (1) is Rf 1 This is a straight-chain or branched-chain fluorinated alkyl group having 1 to 12 carbon atoms, or a straight-chain or branched-chain fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms.

[0078] Rf 1 The fluorinated alkyl group may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 1 The fluorinated alkyl group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable that it does not contain a substituent other than a fluorine atom.

[0079] Also, Rf 1The fluorinated alkoxy group may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 1 The fluorinated alkoxy group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable that it does not contain a substituent other than a fluorine atom.

[0080] Rf 1 The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0081] Rf 1 As, general formula:

[0082] -(Rf 11 ) m -(O) p -(Rf 12 -O) n -Rf 13

[0083] (during food, Rf 11 and Rf 12 is, independently, a straight-chain or branched-chain fluorinated alkylene group having 1 to 4 carbon atoms, Rf 13 A group represented by a straight-chain or branched-chain fluorinated alkyl group having 1 to 4 carbon atoms, where p is 0 or 1, m is an integer from 0 to 4, and n is an integer from 0 to 4 is preferred.

[0084] Rf 11 and Rf 12 The fluorinated alkylene group may be a partially fluorinated alkylene group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkylene group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 11 and Rf 12The fluorinated alkylene group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable that it does not include a substituent other than a fluorine atom. Rf 11 and Rf 12 In each appearance, it may be the same or different.

[0085] Rf 11 As fluorinated alkylene groups, -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-CF2- Examples include, among others, a perfluorinated alkylene group having 1 or 2 carbon atoms is preferred, and -CF2- is more preferred.

[0086] Rf 12 As fluorinated alkylene groups, -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-CF2- Examples include, among others, a perfluorinated alkylene group having 1 to 3 carbon atoms is preferred, and -CF2-, -CF2CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2- or CF2-CF(CF3)- is more preferred.

[0087] Rf 13 As the fluorinated alkyl group, it may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 13 The fluorinated alkyl group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable not to include a substituent other than a fluorine atom (e.g., -CN, -CH2I, -CH2Br, etc.).

[0088] Rf 13 As the fluorinated alkyl group, -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-CF2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CH2-CF2-CF2-CF3, -CHF-CF2-CF2-CF3, Examples include -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3, -CF(CF3)-CF2-CF3, -C(CF3)2-CF3, etc., and among them, -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 is preferred.

[0089] As for p, 0 is desirable.

[0090] m is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0. In addition, when p is 0, it is preferable that m is also 0.

[0091] n is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0092] As a repeating unit,

[0093] -CH2-CF[-CF3]-,

[0094] -CH2-CF[-CF2CF3]-,

[0095] -CH2-CF[-CF2CF2CF3]-,

[0096] -CH2-CF[-CF2CF2CF2CF3]-,

[0097] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CHF-CF3]-,

[0098] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF2-CF3]-,

[0099] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF3]-,

[0100] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CH(CF3)-CF2-CF3]-,

[0101] -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-CF3]-,

[0102] -CH2-CF[-OCF2OCF3]-,

[0103] -CH2-CF[-OCF2CF2CF22OCF3]-,

[0104] -CH2-CF[-CF2OCFOCF3]-,

[0105] -CH2-CF[-CF2OCF2CF2CF2OCF3]-, or,

[0106] -CH2-CF[-O-CF2-CF3]-

[0107] It is desirable,

[0108] -CH2-CF[-CF3]-

[0109] It is more desirable.

[0110] The fluorine-containing monomer (2) represented by the above formula (2) is Rf 2 ...is a straight-chain or branched-chain fluorinated alkyl group having 1 to 12 carbon atoms, or a straight-chain or branched-chain fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms.

[0111] Rf 2 The fluorinated alkyl group may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 2 The fluorinated alkyl group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable that it does not contain a substituent other than a fluorine atom.

[0112] Also, Rf 2 The fluorinated alkoxy group may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 2 The fluorinated alkoxy group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable that it does not contain a substituent other than a fluorine atom.

[0113] Rf 2 The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0114] Rf2 As, general formula:

[0115] -(Rf 21 ) m -(O) p -(Rf 22 -O) n -Rf 23

[0116] (during food, Rf 21 and Rf 22 is, independently, a straight-chain or branched-chain fluorinated alkylene group having 1 to 4 carbon atoms, Rf 23 A group represented by a straight-chain or branched-chain fluorinated alkyl group having 1 to 4 carbon atoms, where p is 0 or 1, m is an integer from 0 to 4, and n is an integer from 0 to 4 is preferred.

[0117] Rf 21 and Rf 22 The fluorinated alkylene group may be a partially fluorinated alkylene group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkylene group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 21 and Rf 22 The fluorinated alkylene group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable that it does not include a substituent other than a fluorine atom. Rf 21 and Rf 22 In each appearance, it may be the same or different.

[0118] Rf 21Examples of 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-, -CHF-CF2-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc. Among these, a perfluorinated alkylene group having 1 or 2 carbon atoms is preferred, and -CF2- is more preferred.

[0119] Rf 22 As fluorinated alkylene groups, -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-CF2- Examples include, among others, a perfluorinated alkylene group having 1 to 3 carbon atoms is preferred, and -CF2-, -CF2CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2- or CF2-CF(CF3)- is more preferred.

[0120] Rf 23 As the fluorinated alkyl group, it may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted by fluorine atoms. In addition, Rf 23The fluorinated alkyl group may have a hydrogen atom substituted by a substituent other than a fluorine atom, but it is preferable not to include a substituent other than a fluorine atom (e.g., -CN, -CH2I, -CH2Br, etc.).

[0121] Rf 23 As the fluorinated alkyl group, -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-CF2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CH2-CF2-CF2-CF3, -CHF-CF2-CF2-CF3, Examples include -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3, -CF(CF3)-CF2-CF3, -C(CF3)2-CF3, etc., and among them, -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 is preferred.

[0122] As for p, 0 is desirable.

[0123] m is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0. In addition, when p is 0, it is preferable that m is also 0.

[0124] n is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0125] As a repeating unit,

[0126] -CHF-CH[-CF3]-,

[0127] -CHF-CH[-CF2CF3]-,

[0128] -CHF-CH[-CF2CF2CF3]-, or,

[0129] -CHF-CH[-CF2CF2CF2CF3]-,

[0130] It is desirable,

[0131] -CHF-CH[-CF3]-

[0132] It is more desirable.

[0133] The above fluorine polymer 2 preferably has a molar ratio of vinylidene fluoride units to copolymer units of 87 / 13 to 20 / 80. In terms of solubility, it is more preferably 85 / 15 to 30 / 70.

[0134] The above fluorine polymer 2 may have constituent units other than vinylidene fluoride units and copolymer units. In this case, the content of other polymers is preferably 50 mol% or less. Additionally, it may consist only of vinylidene fluoride units and copolymer units. The content of other polymers is more preferably 30 mol% or less, and even more preferably 15 mol% or less.

[0135] The above fluorine polymer 2 may use a monomer that provides crosslinking sites as the other monomer.

[0136] The monomer providing the above-mentioned crosslinking site is not particularly limited, for example, general formula:

[0137] CX 12 =CX 1 -Rf 1 CHR 1 X 2

[0138] (during food, X 1 Silver, hydrogen atoms, fluorine atoms, or CH3, Rf 1Silver, fluoroalkylene group, perfluoroalkylene group, fluoro(poly)oxyalkylene group or perfluoro(poly)oxyalkylene group, R 1 Silver, hydrogen atoms, or CH3, X 2 iodine or bromine-containing monomer represented by (which is an iodine or bromine atom), general formula:

[0139] CF2=CFO(CF2CF(CF3)O) m (CF2) n -X 3

[0140] (wherein m is an integer from 0 to 5, n is an integer from 1 to 3, X 3 A monomer represented by a silver, cyano group, carboxyl group, alkoxycarbonyl group, iodine atom, or bromine atom, general formula:

[0141] CH2=CFCF2O(CF(CF3)CF2O) m (CF(CF3)) n -X 4

[0142] (wherein m is an integer from 0 to 5, n is an integer from 1 to 3, X 4 A monomer represented by (which is a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2OH) may be used as another monomer.

[0143] Among these, it is preferable that at least one is 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.

[0144] The above fluorine polymer 2 is preferably a fluorine-containing elastomer. The fluorine-containing elastomer is an amorphous fluorine-based polymer having a low glass transition temperature. Additionally, it may contain repeating units based on monomers that impart crosslinking sites, but in one embodiment of the present disclosure, it does not contain a crosslinking agent.

[0145] The above fluorine-containing elastomer preferably has a glass transition temperature of 25°C or lower. More preferably, the glass transition temperature is 0°C or lower. The glass transition temperature is more preferably -5°C or lower, and most preferably -10°C or lower. Furthermore, it may be -20°C or lower. Here, the glass transition temperature was determined by using a differential scanning calorimeter (X-DSC823e, manufactured by Hitachi Techno Science Co., Ltd.), cooling to -75°C, and then obtaining a DSC curve by increasing the temperature of 10 mg of the sample at 20°C / min; the temperature representing the intersection of the extension of the baseline before and after the second transition of the DSC curve and the tangent at the inflection point of the DSC curve was defined as the glass transition temperature.

[0146] The above fluorine-containing elastomer is preferably amorphous. Being amorphous means that there is no melting point peak in the DSC curve described above.

[0147] Such a low-Tg, amorphous fluorine-containing elastomer is particularly desirable in that it is easily soluble in solvents, provides flexibility to the electrode, and facilitates processing.

[0148] The above-described fluorine-containing elastomer is a copolymer composed of vinylidene fluoride units, the above-described copolymer units, and, optionally, other monomers copolymerizable with these, wherein the molar ratio of vinylidene fluoride units to copolymer units is 99.5 / 0.5 to 80 / 20, and the other monomer units are preferably 0 to 15 mol% of the total monomer units.

[0149] The fluorine-containing elastomer is preferably a copolymer composed solely of vinylidene fluoride, copolymer units, and other monomers.

[0150] The fluorine polymer 2 used in the present disclosure preferably has 0.001 to 10 mol% of constituent units derived from copolymer units (provided that the sum of constituent units derived from vinylidene fluoride and copolymer units is 100 mol%), more preferably 0.01 to 5 mol%, and particularly preferably 0.01 to 3.0 mol%. In addition, it is preferable to have 90 to 99.999 mol% of constituent units derived from vinylidene fluoride, more preferably 95 to 99.75 mol%, and particularly preferably 96 to 99.63 mol%. When the copolymer units are 0.01 mol% or more, the viscosity of the polymer solvent does not become too high, thereby preventing difficulty in coating the polymer solvent.

[0151] The weight average molecular weight (converted to polystyrene) of the fluorine polymer 2 is preferably 161,000 to 276,000, more preferably 322,000 to 253,000, and even more preferably 600,000 to 200,000. The weight average molecular weight can be measured at 50°C using dimethylformamide as a solvent by gel permeation chromatography (GPC).

[0152] The number average molecular weight (converted to polystyrene) of the fluorine polymer 2 is preferably 70,000 to 1,200,000, and more preferably 1,400,000 to 1,100,000. The number average molecular weight can be measured at 50°C using dimethylformamide as a solvent by gel permeation chromatography (GPC).

[0153] The glass transition temperature of the fluorine polymer 2 is preferably 25°C or lower, more preferably 20°C or lower, even more preferably 15°C or lower, even more preferably 0°C or lower, even more preferably -5°C or lower, and most preferably -10°C or lower. The glass transition temperature of the fluorine polymer 2 is preferably -25°C or higher, more preferably -23°C or higher, and even more preferably -20°C or higher. Here, the glass transition temperature is determined by using a differential scanning calorimeter (X-DSC823e, manufactured by Hitachi Techno Science Co., Ltd.), cooling to -75°C, and then obtaining a DSC curve by increasing the temperature of 10 mg of the sample at 20°C / min, and determining the temperature at which the tangent line at the inflection point of the DSC curve intersects the extension of the baseline before and after the second transition of the DSC curve.

[0154] The Mooney viscosity of the fluorine polymer 2 at 121°C (ML1+10(121°C)) is preferably 2 or higher, more preferably 5 or higher, even more preferably 10 or higher, particularly preferably 15 or higher, and may be 200 or lower.

[0155] The Mooney viscosity of the fluorine polymer 2 at 140°C (ML1+10(121°C)) is preferably 2 or higher, more preferably 5 or higher, even more preferably 10 or higher, particularly preferably 15 or higher, and may be 200 or lower.

[0156] Mooney viscosity is a value measured in accordance with ASTM-D1646-15 and JIS K6300-1:2013.

[0157] The above fluorine polymer 2 has a terminal structure of the following inequality:

[0158] 0.01≤([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH])≤0.25

[0159] It is preferable to satisfy (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.

[0160] By making the terminal functional group satisfy the above formula, the adhesion and flexibility are good, and thus it has excellent functionality.

[0161] That is, [-CH2OH] or [-COOH] is desirable because it has high affinity functional groups such as hydroxyl groups and carboxyl groups, and thus has high affinity with the electrolyte.

[0162] Therefore, containing these functional groups in a proportion above a certain level is desirable for excellent adhesion. On the other hand, if the amount of [-CH2OH] or [-COOH] becomes excessive, flexibility decreases. From this perspective, it is desirable that [-CH2OH] or [-COOH] be within the aforementioned range.

[0163] Furthermore, satisfying the above general formula does not mean having all functional groups of [-CH3], [-CF2H], [-CH2OH], [-CH2I], [-OC(O)RH], and [-COOH] among the fluorine polymer 2 terminals, but rather means having the ratio of the number of terminal groups present among these within the range described above.

[0164] The amount of each terminal group of the resin can be determined by analysis using NMR.

[0165] NMR terminal group analysis was measured by the solution NMR method of protons. The analysis sample was prepared by adjusting the solution to 20 wt% using Acetone-d6 as the solvent, and measurements were performed.

[0166] The reference peak is set to the peak top of acetone at 2.05 ppm.

[0167] Measuring device: Varians VNMRS400

[0168] Resonance frequency: 399.74 (Sfrq)

[0169] Pulse width: 45°

[0170] Each end was corresponded to the one at the following peak position.

[0171] [-CH3]: 1.72 to 1.86 ppm

[0172] [-CF2H]: 6.1 to 6.8 ppm

[0173] [-CH2OH]: 3.74 to 3.80 ppm

[0174] [-CH2I]: 3.87 to 3.92 ppm

[0175] [-OC(O)RH]: 1.09 to 1.16 ppm

[0176] [-COOH]: 10 to 15 ppm

[0177] Based on the integral value of each peak specified by the above-described measurement, the amount of functional group is calculated from each peak intensity, and based on the result, it is calculated using the following formula.

[0178] ([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH])

[0179] In addition, the method of making [-CH2OH] or [-COOH] within the aforementioned predetermined range is not particularly limited and can be controlled by known methods (e.g., selection and amount of initiator used).

[0180] In order to ensure good adhesion, flexibility, and solubility in a solvent, the above-mentioned fluorine polymer 2 preferably has a number average molecular weight (Mn) of 7,000 to 5,000,000, a weight average molecular weight (Mw) of 10,000 to 1,000,000, and an Mw / Mn of 1.0 to 30.0, and 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 the GPC method.

[0181] The above fluorine polymer 2 can be manufactured by a general radical polymerization method. The polymerization form may be any of bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, but emulsion polymerization is preferred for ease of industrial implementation.

[0182] In polymerization, a polymerization initiator, a chain transfer agent, a surfactant, and a solvent may be used, and each may be conventionally known. 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.

[0183] As an oil-soluble radical polymerization initiator, it may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropylperoxydicarbonate and disec-butylperoxydicarbonate, peroxyesters such as t-butylperoxyisobutyrate and t-butylperoxypivalate, dialkyl peroxides such as dit-butylperoxide, and also di(ω-hydro-dodecafluoroheptanoyl)peroxide, di(ω-hydro-tetradecafluoroheptanoyl)peroxide, di(ω-hydro-hexadecafluorononanoyl)peroxide, di(perfluorobutyryl)peroxide, di(perfluorophaleryl)peroxide, di(perfluorohexanoyl)peroxide, di(perfluoroheptanoyl)peroxide, di(perfluorooctanoyl)peroxide, di(perfluorononanoyl)peroxide, di(ω-chloro-hexafluorobutyril)peroxide, di(ω-chloro-decafluorohexanoyl)peroxide, di(ω-chloro-tetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyril-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyril-peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, di(undecachlorodotriacontafluorodocosanoyyl)peroxide of di[perfluoro(or fluoro Representative examples include chloroacyl peroxides.

[0184] As a water-soluble radical polymerization initiator, it may be a known water-soluble peroxide, and examples include ammonium salts, potassium salts, sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, percarbonate, etc., t-butyl permaleate, t-butyl hydroperoxide, etc. Reducing agents such as sulfites and sulfites may also be included, and the amount used may be 0.1 to 20 times the amount of peroxide.

[0185] There is no specific limit to the amount of radical polymerization initiator added, but an amount greater than or equal to a concentration of several ppm versus water that does not significantly reduce the polymerization rate should be added all at once, sequentially, or continuously at the beginning of polymerization. The upper limit is the range in which the heat of the polymerization reaction can be dissipated from the surface of the apparatus.

[0186] As for the solvent, it is preferable that it be a solvent that does not have chain mobility. For solution polymerization, dichloropentafluoropropane (R-225) may be used, and for emulsion polymerization and suspension polymerization, water, a mixture of water and an aqueous organic solvent, or a mixture of water and an aqueous organic solvent may be used.

[0187] In the above polymerization, as chain transfer agents, examples include esters such as dimethyl malonicate, diethyl malonicate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as isopentane, methane, ethane, propane, isopropanol, acetone, various mercaptans, carbon tetrachloride, cyclohexane, etc.

[0188] Bromine compounds or iodine compounds may be used as chain transfer agents. As a polymerization method using a bromine compound or an iodine compound, for example, an emulsion polymerization method can be performed in a water medium under pressure in the presence of a bromine compound or an iodine compound under substantially oxygen-free conditions (iodine transfer polymerization method). Representative examples of the bromine compound or iodine compound used include, for example, the general formula:

[0189] R 2 I x Br y

[0190] (In the equation, x and y are integers from 0 to 2, respectively, and also satisfy 1≤x+y≤2, and R 2is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, and may include an oxygen atom.

[0191] Examples of compounds represented by can be found.

[0192] As iodine compounds, for example, 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, Examples include BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1,2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo substituents of benzene, diiodomonobromo substituents, and (2-iodoethyl) and (2-bromoethyl) substituents, and these compounds may be used alone or in combination with each other.

[0193] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, and availability.

[0194] In the case of emulsion polymerization, the polymer obtained by the above-described method can be obtained in a powder state by coagulating the polymerized dispersion, washing it with water, dehydrating it, and drying it. Coagulation can be performed by adding inorganic salts such as aluminum sulfate or inorganic acids, applying mechanical shear force, or freezing the dispersion. In the case of suspension polymerization, the polymer can be obtained in a powder state by recovering it from the polymerized dispersion and drying it. In the case of solution polymerization, the polymer can be obtained by drying the solution containing the polymer as is, or by purifying it by adding a solvent dropwise.

[0195] As for the fluorine polymer 2, one type may be used, or two or more types may be used. In particular, it may be in the form of using two types of copolymers with different molecular structures.

[0196] (Fluoropolymer 3)

[0197] The fluorine polymer used in the present disclosure may contain vinylidene fluoride and a copolymer of the monomer represented by the formula (3) above.

[0198] In the above equation (3), R 1 , R 2 and R 3 Silver, each independently a hydrogen atom, a chlorine atom, or an alkyl group having 1 to 5 carbon atoms, but from the perspective of a polymerization reaction, particularly R 1 , R 2 It is desired that the steric hindrance be a substituent, hydrogen or an alkyl group having 1 to 3 carbon atoms is preferred, and it is preferred that the alkyl group be hydrogen or a methyl group.

[0199] In the above formula (3), X may be an atomic group with a molecular weight of 500 or less in which the single bond or main chain consists of 1 to 20 atoms, but it is preferable that it be 200 or less. In addition, there is no particular limit on the lower limit of the molecular weight in the case of an atomic group, but it is usually 15. This range is desirable in that it can suitably suppress the gelation of the electrode composite slurry.

[0200] In addition, among the above equation (3), X may be a structure represented by the following equation (3-1).

[0201]

[0202] In the above formula (3-1), X' is an atomic group with a molecular weight of 456 or less, in which the main chain consists of 1 to 18 atoms; however, it is more preferable that the main chain consists of 1 to 13 atoms or 1 to 8 atoms, and the molecular weight is preferably 156 or less. Additionally, there is no particular limit on the lower limit of the molecular weight of the atomic group X', but it is typically 14. This range is desirable from the perspective of polymerization. Furthermore, the number of hydrogen atoms is not included in the number of atoms in the main chain. Also, the number of atoms in the main chain refers to the carboxyl group listed to the right of X in formula (3) and the group (R) listed to the left of X. 1 R 2 C=CR 3 -) refers to the number of atoms in the skeletal portion of the chain connecting the smallest number of atoms. Additionally, X may be branched by including a functional group as a side chain. The side chain included in X may be one or multiple.

[0203] In the above general formula (3), Y represents an inorganic cation and / or an organic cation.

[0204] Examples of inorganic cations include H, Li, Na, K, Mg, Ca, Al, and Fe. Examples of organic cations include NH4 and NH3R 15 , NH2R 15 2, NHR 15 3, NR 15 4(R 15Examples of cations include (independently representing an alkyl group having 1 to 4 carbon atoms). As for Y, H, Li, Na, K, Mg, Ca, Al, and NH4 are preferred, H, Li, Na, K, Mg, Al, and NH4 are more preferred, H, Li, Al, and NH4 are even more preferred, and H is particularly preferred. In addition, specific examples of inorganic cations and organic cations are described with symbols and valencies omitted for convenience.

[0205] In addition, the monomer represented by the above formula (3) is preferably a compound containing a polar group. Examples of compounds containing a polar group include compounds containing a carboxyl group, an epoxy group, a hydroxyl group, a sulfonic acid group, etc., and among these, it is preferable that the compound contains a carboxyl group. It is desirable for the compound containing a polar group represented by the above formula (3) to contain a carboxyl group in terms of good bonding between the electrode active material and the current collector.

[0206] As for the polar group-containing compound represented by Formula (3), specifically, examples include acrylic acid (AA), 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, acryloyloxyethyl succinic acid (AES), acryloyloxypropyl succinic acid (APS), and among these, acrylic acid, 2-carboxyethyl acrylate, acryloyloxyethyl succinic acid, and acryloyloxypropyl succinic acid are preferred. In the present disclosure, one or more of the polar group-containing compounds represented by Formula (1) may be included.

[0207] The fluorine polymer 3 used in the present disclosure preferably has 0.01 to 10 mol% of a constituent unit derived from a monomer represented by formula (3) (provided that the sum of the constituent unit derived from vinylidene fluoride and the constituent unit derived from the monomer represented by formula (3) is 100 mol%), more preferably has 0.20 to 7 mol%, and particularly preferably has 0.30 to 4 mol%. In addition, it is preferable to have 90 to 99.99 mol% of a constituent unit derived from vinylidene fluoride, more preferably has 93 to 99.75 mol%, and particularly preferably has 96 to 99.63 mol%. When the constituent unit derived from the monomer represented by formula (3) is 0.01 mol% or more, the proportion within the fluorine polymer of formula (3) does not become too small, thereby allowing for the effect of suppressing gelation of the fluorine polymer solution. In addition, if the constituent unit derived from the monomer represented by (3) is 10 mol% or less, the viscosity does not become too high, so it is possible to prevent the coating from becoming difficult.

[0208] In addition, the amount of vinylidene fluoride units of the fluorine polymer 3 and the amount of monomer units represented by the above formula (3) are, usually, of the copolymer 1 It can be obtained by H NMR spectrum or neutralization titration.

[0209] The fluorine polymer 3 used in the present disclosure may have components of monomers other than vinylidene fluoride and the monomer represented by Formula (3). For example, fluorine monomers copolymerizable with vinylidene fluoride, hydrocarbon monomers such as ethylene and propylene, and monomers copolymerizable with Formula (3) may be used. Examples of fluorine monomers copolymerizable with vinylidene fluoride include vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ethers represented by perfluoromethylvinyl ether. Examples of monomers copolymerizable with Formula (3) include (meth)acrylic acid and (meth)acrylate alkyl compounds represented by (meth)acrylate methyl. Additionally, other monomers may be used as a single type or as two or more types.

[0210] In the case where the above-described fluorine polymer 3 has other monomers, if the total monomer unit constituting the fluorine polymer 3 is 100 mol%, it is preferable to have 0.01 to 10 mol% of other monomer units.

[0211] The fluorine polymer 3 used in the present disclosure has a weight-average molecular weight obtained by GPC (gel permeation chromatography), which is typically in the range of 50,000 to 1,500,000.

[0212] The above fluorine polymer 3 can be obtained by polymerizing at least one of vinylidene fluoride and the monomer represented by Formula (3) using a conventionally known method. The polymerization method is not particularly limited, but examples include suspension polymerization, emulsion polymerization, and solution polymerization. Among these, due to ease of post-treatment, it is preferable that the polymerization method be water-based suspension polymerization or emulsion polymerization. Furthermore, the vinylidene fluoride and the monomer represented by Formula (3) used for polymerization are each well-known compounds, and commercially available products may be used.

[0213] The above fluorine polymer 3 is preferably obtained by copolymerizing 90 to 99.9 parts by mass of vinylidene fluoride and 0.1 to 10 parts by mass of a monomer represented by formula (3), more preferably 95 to 99.9 parts by mass of vinylidene fluoride and 0.1 to 5 parts by mass of a monomer represented by formula (3) (provided that the total of vinylidene fluoride and the monomer represented by formula (3) is 100 parts by mass).

[0214] The intrinsic viscosity ηi of the above fluorine polymer 3 is preferably 0.5 dl / g to 5.0 dl / g, more preferably 1.0 dl / g to 4.0 dl / g, and even more preferably 1.5 dl / g to 3.5 dl / g. An intrinsic viscosity within the above range is desirable in that it facilitates electrode fabrication without causing deterioration in productivity due to a decrease in the solid content of the fluorine resin solution or causing thickness non-uniformity of the electrode when coating the electrode composite.

[0215] In addition, the aforementioned intrinsic viscosity ηi can be obtained by dissolving 80 mg of the polymer in 20 ml of N,N-dimethylformamide and using a Uvelohde viscometer in a constant temperature bath at 30°C according to the following formula.

[0216]

[0217] In the above formula, η is the viscosity of the polymer solution, η0 is the viscosity of the solvent N,N-dimethylformamide, and C is 0.4 g / dl.

[0218] If the intrinsic viscosity is within the above range, it is desirable in that it facilitates electrode fabrication without causing deterioration in productivity due to a decrease in the solid content of the fluoropolymer solution or uneven thickness of the electrode when coating the electrode mixture.

[0219] (Polar)

[0220] In the secondary battery of the present disclosure, the negative electrode preferably comprises a metallic layer of at least one metal element selected from the group consisting of lithium, sodium, magnesium, and zinc.

[0221] In addition, in the first embodiment above, it is essential that the negative electrode comprises a metallic layer of at least one metal element selected from the group consisting of lithium, sodium, magnesium, and zinc.

[0222] In the second embodiment above, at the time the electrode is manufactured, it does not have a metallic layer. The metallic layer of a metal element that is subsequently formed by charging is preferably composed of at least one metal element selected from the group consisting of lithium, sodium, magnesium, and zinc.

[0223] Among these, it is most desirable to use lithium metal alone or an alloy containing it, and it is most desirable to use lithium metal alone.

[0224] The negative electrode can be manufactured using a general method for manufacturing metal foil. In addition, when using alloy materials, a method of forming a thin film layer (negative electrode active material layer) containing the aforementioned negative electrode active material by methods such as deposition, sputtering, or plating is also used.

[0225] The thickness of the negative electrode plate is designed to match the positive electrode plate used and is not particularly limited, but the thickness of the composite layer after subtracting the thickness of the metal foil of the core material is typically 15㎛ or more, preferably 20㎛ or more, more preferably 30㎛ or more, and also typically 300㎛ or less, preferably 280㎛ or less, more preferably 250㎛ or less.

[0226] (Bugukyong House Entire House)

[0227] Examples of materials for the current collector for the negative electrode include metal materials such as aluminum, titanium, tantalum, stainless steel, nickel, copper, or their alloys; and carbon materials such as carbon cloth or carbon paper. Among these, metal materials, particularly aluminum, copper, or their alloys, are preferred.

[0228] Examples of shapes for the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, foamed metal, etc. for metal materials, and carbon plate, carbon thin film, carbon cylinder, etc. Among these, a metal thin film is preferred. In addition, the thin film may be formed into a mesh shape as appropriate. The thickness of the thin film is arbitrary, but is typically 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and typically 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the thin film is thinner than this range, it may lack the strength required as a current collector. Conversely, if the thin film is thicker than this range, handling properties may be compromised.

[0229] In addition, it is desirable to have a conductive agent coated on the surface of the entire current collector to reduce electrical contact resistance. Examples of conductive agents include carbon and precious metals such as gold, platinum, and silver.

[0230] Although the ratio of the thickness of the current collector to the thickness of the negative electrode active material layer is not particularly limited, it is preferable that the value of (thickness of the negative electrode active material layer on one side immediately before the liquid electrolyte injection) / (thickness of the current collector) be 20 or less, more preferably 15 or less, most preferably 10 or less, and also preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. If it exceeds this range, the current collector may generate heat due to Joule heating during high current density charging and discharging. If it falls below this range, the volume ratio of the current collector increases, and the capacity of the battery may decrease.

[0231] The coating made of the above-mentioned fluorine polymer preferably has a coating thickness of 3 to 8 μm before drying. By making it within this range, the effects of the present disclosure can be suitably exhibited.

[0232] (Method for manufacturing negative electrodes)

[0233] The negative electrode of the present disclosure can be manufactured by a method of applying and drying a solution of the polymer described above onto a negative electrode material or a current collector, or by a method of attaching by rolling.

[0234] Examples of solvents used when the polymer is in solution include N-methyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, N-ethyl-2-pyrrolidone and N-butyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, diethylenetriamine, N,N-dimethylaminopropylamine, diethyl ether, propylene oxide, tetrahydrofuran, etc.

[0235] The polymer in the polymer solution is preferably 3 to 40 mass% with respect to the total polymer solution, and more preferably 5 to 15 mass%.

[0236] The density of the coating layer after drying is preferably 0.3 to 3.0 g / cm³, and more preferably 1 to 2 g / cm³.

[0237] The thickness of the coating layer after drying can be calculated from the weight of the fluorine polymer in the polymer solution and the thickness of the coating layer on the negative electrode material or current collector.

[0238] In the second embodiment, a current collector having a coating layer formed thereon is freeze-dried by immersing it in liquid nitrogen, and a sample for cross-sectional observation is prepared by cutting the freeze-dried sample perpendicularly to the coating layer, and the thickness of the coating layer after drying can be measured by observing the cross-section of the coating layer of the sample with a scanning electron microscope (SEM).

[0239] The density of the coating layer after drying can be calculated by determining the weight from the change in weight of the coating layer before and after drying, and dividing it by the volume of the coating layer after drying.

[0240] (battery)

[0241] The present disclosure relates to a secondary battery having the negative electrode described above and a liquid electrolyte containing fluorinated ether as an essential component. Below, the fluorinated ether and the liquid electrolyte containing it will be described in detail. It is particularly advantageous to use an electrolyte containing fluorinated ether and to use the negative electrode described above in that the formation of dendrites can be reduced.

[0242] (fluorinated ether)

[0243] It is preferable that the liquid electrolyte contains less than 90 mass% of fluorinated ether in the total electrolyte solvent.

[0244] Fluorinated ethers are not particularly limited, and any ether compound containing fluorine is not particularly limited.

[0245] As the above-mentioned fluorinated ether, the following general formula (I):

[0246] Rf 4 -O-Rf 5 (I)

[0247] (during food, Rf 4 and Rf 5 is the same or different and is an alkyl group having 1 to 10 carbon atoms or a fluorinated alkyl group having 1 to 10 carbon atoms. provided that Rf 4 and Rf 5 At least one of them is a fluorinated alkyl group.)

[0248] Other fluorinated ethers indicated by [this] may be used. By including other fluorinated ethers, the flame retardancy of the liquid electrolyte is improved, and stability and safety at high temperature and high voltage are enhanced.

[0249] In the above general formula (I), Rf 4and Rf 5 At least one of them needs to be a fluorinated alkyl group having 1 to 10 carbon atoms, but in terms of further improving the flame retardancy of the liquid electrolyte and the stability and safety at high temperature and high voltage, Rf 4 and Rf 5 It is preferable that all of them are fluorinated alkyl groups having 1 to 10 carbon atoms. In this case, Rf 4 and Rf 5 They may be the same, or they may be different from each other.

[0250] Among them, Rf 4 and Rf 5 a, identical or different, Rf 4 α is a fluorinated alkyl group having 3 to 6 carbon atoms, and also, Rf 5 It is more preferable that α is a fluorinated alkyl group having 2 to 6 carbon atoms.

[0251] 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, and also, Rf 4 or Rf 5 If the carbon number is too high, the solubility of the electrolyte salt decreases, adversely affecting compatibility with other solvents, and the rate characteristics are reduced because the viscosity increases. Rf 4 The number of carbon atoms is 3 or 4, Rf 5 When the carbon number is 2 or 3, it is advantageous in that it has excellent boiling point and rate characteristics.

[0252] Examples of such fluorinated ethers include fluorinated ethers represented by the following general formula (10).

[0253] HCF2CF2-OR (10)

[0254] (In the formula, R is an alkyl group that may contain an ether group, or a fluorinated alkyl group that may contain an ether group.)

[0255] In the following, first, a fluorinated ether compound represented by the general formula (10) will be described in detail, and then, a fluorinated ether compound other than the fluorinated ether compound represented by the general formula (10) will also be described (hereinafter, this may be referred to as "other fluorinated ether compounds").

[0256] In the present disclosure, it is acceptable to use a fluorinated ether compound represented by the general formula (10) and "other fluorinated ether compounds" in combination.

[0257] In the compound represented by the above general formula (10), the fluorinated alkyl group is preferably a fluorinated alkyl group having 1 to 10 carbon atoms. Among these, it is more preferable that it is a fluorinated alkyl group having 2 to 6 carbon atoms.

[0258] In the compound represented by the above general formula (10), if the number of carbon atoms in the fluoroalkyl group is too small, the boiling point is lowered and the volatility of the electrolyte increases, and if the number of carbon atoms is too large, the viscosity increases and the output characteristics are degraded.

[0259] The compound represented by the above general formula (10) preferably has a fluorine content of 40 to 75 mass%. When having a fluorine content in this range, the balance of non-flammability and compatibility is particularly excellent. It is also desirable in that it has good oxidation resistance and safety.

[0260] The lower limit of the above fluorine content is more preferably 43 mass%, more preferably 45 mass%, and particularly preferably 50 mass%. The upper limit is more preferably 70 mass%, and more preferably 66 mass%.

[0261] In addition, the fluorine content of the fluorinated ether is a value calculated based on the structural formula of the fluorinated ether by {(number of fluorine atoms × 19) / molecular weight of the fluorinated ether} × 100 (%).

[0262] As R, for example -CH2CF2CF3, -CF2CFHCF3, -CF2CF2CF2H, -CH2CF2CF2H, -CH2CH2CF2CF3, -CH2CF2CFHCF3, -CF2CF2CF2CF2H, -CH2CF2CF2CF2H, -CH2CH2CF2CF2H, -CH2CF(CF3)CF2H, -CF2CF2H, -CH2CF2H, -CH2CF3, -CF2CH3, -CH2-CH3, CH2-CH2-CH3, CH2-CH2-CH2-CH3, -CH2CH2-O-CF2CF2H, -CH2CH2-O-CH3, -CH2CH2-O-CH2CH3, -CH2CH2-O-CF3, -CH2CH2-O-CH2CF3, -CH2CH2-O-CF2CF2H, Examples include -CH2CH2-O-CF2H, -CH2CH2-O-CH2CF2H, etc.

[0263] Specific examples of compounds represented by the above general formula (10) include, for instance, HCF2CF2-O-CH2CF2CF2H, HCF2CF2-O-CH2CF2CF3, HCF2CF2-O-CH2CF3, HCF2-CF2-O-CH2-CH2-CH3, HCF2-CF2-O-CH2-CH2-CH2-CH3, HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, etc.

[0264] It is preferable that the fluorinated ether represented by the above general formula (10) be at least one fluorinated ether selected from the group consisting of fluorinated ethers represented by the following general formulas (12) to (14).

[0265] HCF2CF2-O-CH2CF2CF2H (12)

[0266] HCF2CF2-O-CH2CF2CF3(13)

[0267] HCF2CF2-O-CH2CF3(14)

[0268] In particular, by including a fluorinated ether represented by the above general formulas (12) to (14) as an additive to the liquid electrolyte, it is advantageous in that it lowers the flash point of the electrolyte.

[0269] Examples of other fluorinated ethers (i.e., fluorinated ethers not represented by the general formula (10)) include the following.

[0270] The above-mentioned other fluorinated ethers preferably have a fluorine content of 40 to 75 mass%. When having a fluorine content within this range, the balance of non-flammability and compatibility is particularly excellent. In addition, it is also desirable in that it has good oxidation resistance and safety.

[0271] The lower limit of the above fluorine content is more preferably 45 mass%, more preferably 50 mass%, and particularly preferably 55 mass%. The upper limit is more preferably 70 mass%, and more preferably 66 mass%.

[0272] In addition, the fluorine content of other fluorinated ethers is a value calculated based on the structural formula of other fluorinated ethers by {(number of fluorine atoms × 19) / molecular weight of other fluorinated ethers} × 100 (%).

[0273] Rf 4 Examples include CF3CF2CH2-, CF3CFHCF2-, HCF2CF2CF2-, HCF2CF2CH2-, CF3CF2CH2CH2-, CF3CFHCF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CF2CH2-, HCF2CF2CH2CH2-, HCF2CF(CF3)CH2-, etc. Also, Rf 4 Examples include -CH2CF2CF3, -CF2CFHCF3, -CF2CF2CF2H, -CH2CF2CF2H, -CH2CH2CF2CF3, -CH2CF2CFHCF3, -CF2CF2CF2CF2H, -CH2CF2CF2CF2H, -CH2CH2CF2CF2H, -CH2CF(CF3)CF2H, -CF2CF2H, -CH2CF2H, -CF2CH3, etc.

[0274] Specific examples of the other fluorinated ethers mentioned above include, for example, HCF2CF2CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, C6F 13 OCH3, C6F 13 OC2H5, C8F 17 OCH3, C8F 17 Examples include OC2H5, CF3CFHCF2CH(CH3)OCF2CFHCF3, HCF2CF2OCH(C2H5)2, HCF2CF2OC4H9, HCF2CF2OCH2CH(C2H5)2, and HCF2CF2OCH2CH(CH3)2.

[0275] Among these, including HCF2 at one or both ends can provide other fluorinated ethers with excellent polarity and high boiling points. The boiling point of the other fluorinated ether is preferably 67 to 120°C. More preferably 80°C or higher, and even more preferably 90°C or higher.

[0276] Examples of such other fluorinated ethers include one or more of CF3CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, HCF2CF2CH2OCF2CFHCF3, HCF2CF2CH2OCH2CF2CF2H, CF3CFHCF2CH2OCF2CFHCF3, and HCF2CF2CH2OCF2CF2H.

[0277] Among them, it is preferable to select at least one from the group consisting of HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C) and CF3CF2CH2OCF2CFHCF3 (boiling point 82°C) as it is advantageous in terms of high boiling point, compatibility with other solvents, and good solubility of electrolyte salts, and HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C) is more preferable.

[0278] It is preferable that the content of the above-mentioned fluorinated ether be less than 90 mass% in the liquid electrolyte.

[0279] By keeping it within the specified range, it can be used as a good liquid electrolyte. That is, if the content increases, the concentration of the liquid electrolyte increases, and as the ionic conductivity decreases, the battery life decreases.

[0280] The above lower limit is preferably 3 mass%, and more preferably 5 mass%. The above upper limit is preferably 70 mass%, and more preferably 60 mass%.

[0281] When using a fluorinated ether represented by the above general formula (10), it is preferable to have the content of the fluorinated ether within the range described above.

[0282] (Components other than fluorinated ethers in liquid electrolytes)

[0283] The liquid electrolyte of the present disclosure preferably comprises components other than fluorinated ethers. Components that can be incorporated into such a liquid electrolyte are described in detail below.

[0284] The above solvent preferably comprises at least one selected from the group consisting of carbonates and carboxylic acid esters.

[0285] The above carbonate may be a cyclic carbonate or a chain carbonate.

[0286] The above cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0287] Examples of the above-mentioned non-fluorinated cyclic carbonates include non-fluorinated saturated cyclic carbonates, non-fluorinated saturated alkylene carbonates having alkylene groups having 2 to 6 carbon atoms are preferred, and non-fluorinated saturated alkylene carbonates having alkylene groups having 2 to 4 carbon atoms are more preferred.

[0288] Among these, as the above-mentioned non-fluorinated saturated cyclic carbonate, at least one type selected from 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 is preferred in that it has a high dielectric constant and suitable viscosity.

[0289] The above-mentioned non-fluorinated saturated cyclic carbonates may be used as a single type, or two or more types may be used in any combination and ratio.

[0290] When the above-mentioned non-fluorinated saturated cyclic carbonate is included, the content of the above-mentioned non-fluorinated saturated cyclic carbonate is preferably 5 to 90 volume% with respect to the solvent, more preferably 10 to 60 volume%, and even more preferably 15 to 45 volume%.

[0291] The above-mentioned fluorinated cyclic carbonate is a cyclic carbonate having a fluorine atom. A solvent containing the fluorinated cyclic carbonate can be suitably used even under high voltage.

[0292] In addition, in this specification, "high voltage" refers to a voltage of 4.2V or higher. In addition, the upper limit of the "high voltage" is preferably 4.9V.

[0293] The above-mentioned fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0294] The above-mentioned fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom, specifically, the following general formula (A):

[0295]

[0296] (during food, X 1 To X 4represents, respectively, -H, -CH3, -C2H5, -F, a fluorinated alkyl group that may have an ether bond, or a fluorinated alkoxy group that may have an ether bond, provided that X 1 To X 4 Examples of compounds represented by at least one of which is -F, a fluorinated alkyl group that may have an ether bond, or a fluorinated alkoxy group that may have an ether bond. The above fluorinated alkyl group is -CF3, -CF2H, -CH2F, etc.

[0297] When the above-mentioned fluorinated saturated cyclic carbonate is included, when the liquid electrolyte of the present disclosure is applied to a high-voltage lithium-ion secondary battery, the oxidation resistance of the liquid electrolyte is improved, and stable and excellent charge / discharge characteristics are obtained.

[0298] Additionally, in this specification, "ether bond" is a bond indicated by -O-.

[0299] In terms of good dielectric constant and oxidation resistance, X 1 To X 4 It is preferable that one or two of the groups are -F, a fluorinated alkyl group that may have an ether bond, or a fluorinated alkoxy group that may have an ether bond.

[0300] In terms of expecting a decrease in viscosity at low temperatures, an increase in the flash point, and furthermore, an improvement in the solubility of electrolyte salts, X 1 To X 4 It is preferable that the fluorinated alkyl group (a), the fluorinated alkyl group having an ether bond (b), or the fluorinated alkoxy group (c).

[0301] The above fluorinated alkyl group (a) is formed by substituting at least one hydrogen atom 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, even more preferably 1 to 7, and particularly preferably 1 to 5. If the number of carbon atoms becomes too large, there is a risk that the low-temperature properties will deteriorate or the solubility of the electrolyte salt will decrease, and if the number of carbon atoms becomes too small, there may be a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, and further an increase in viscosity.

[0302] Among the above fluorinated alkyl groups (a), those having one carbon atom include CFH2-, CF2H-, and CF3-. In particular, CF2H- or CF3- is preferred for high-temperature preservation characteristics, and CF3- is most preferred.

[0303] Among the above fluorinated alkyl groups (a), those having 2 or more carbon atoms are as follows: general formula (a-1):

[0304] R 8 -R 9 - (a-1)

[0305] (during food, R 8 An alkyl group having 1 or more carbon atoms that may have a fluorine atom; R 9 is an alkylene group having 1 to 3 carbon atoms that may have a fluorine atom; provided, R 1 and R 2 A fluorinated alkyl group represented by (at least one of which has a fluorine atom) can be preferably exemplified in that it has good solubility in the electrolyte salt.

[0306] Also, R 1 and R 2 It may also have other atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0307] R 8 It is an alkyl group having one or more carbon atoms that may contain silver or fluorine atoms. R 8As for, a straight-chain or branched-chain alkyl group having 1 to 16 carbon atoms is preferred. R 8 As for the number of carbon atoms, 1 to 6 is more preferable, and 1 to 3 is even more preferable.

[0308] R 8 As, specifically, as a straight-chain or branched-chain alkyl group, CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0309]

[0310] You can lift the back.

[0311] Also, R 8In the case of a straight-chain alkyl group having this fluorine atom, CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CF2CH2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CF2CH2CH2CH2-, CF3CF2CF2CH2CH2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CF2CH2CH2CH2-, CF3CF2CF2CF2CH2CH2-, CF3CF2CF2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HCFClCF2CFClCF2CH2-, etc.

[0312] Also, R 8 In the case where it is a branched-chain alkyl group having this fluorine atom,

[0313]

[0314]

[0315] The following can be preferably cited. However, since viscosity tends to increase if it has branches such as CH3- or CF3-, it is more preferable that the number be small (1) or zero.

[0316] R 9 is an alkylene group having 1 to 3 carbon atoms that may have a fluorine atom. R 9 It may be in the form of a straight chain or a branched chain. An example of the minimum structural unit constituting such a straight or branched alkylene group is shown below. R 9 It consists of these alone or in combination.

[0317] (i) Minimum structural unit in a linear chain:

[0318] -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0319] (ii) Minimum structural unit of a branched chain:

[0320]

[0321] In addition, among the examples above, it is preferable to be composed of a constituent unit that does not contain Cl, as this prevents the deHCl reaction caused by a base and is more stable.

[0322] R 9 In the case of a straight chain, it comprises only the minimum structural unit of the straight chain described above, and among them, -CH2-, -CH2CH2-, or -CF2- is preferred. -CH2- or -CH2CH2- is more preferred in that it can further improve the solubility of the electrolyte salt.

[0323] R 9 In the case of a branched chain structure, it is formed by including at least one minimum structural unit of the branched chain structure described above, and the general formula -(CX a X b )-(X ais H, F, CH3 or CF3; X b is CH3 or CF3. However, X b If is CF3, X a It can preferably be exemplified by being represented as H or CH3). These can particularly further improve the solubility of electrolyte salts.

[0324] As a preferred fluorinated alkyl group (a), for example, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CHF-, CH3CF2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0325]

[0326]

[0327] You can lift the back.

[0328] The fluorinated alkyl group (b) having an ether bond is formed by substituting at least one hydrogen atom of the alkyl group having an ether bond with a fluorine atom. The fluorinated alkyl group (b) having an ether bond preferably has 2 to 17 carbon atoms. If the number of carbon atoms is too high, the viscosity of the fluorinated saturated cyclic carbonate increases, and furthermore, due to the increased number of fluorine-containing groups, a decrease in the solubility of the electrolyte salt due to a decrease in dielectric constant or a decrease in compatibility with other solvents may be observed. From this perspective, the number of carbon atoms of the fluorinated alkyl group (b) having an ether bond is more preferably 2 to 10, and even more preferably 2 to 7.

[0329] The alkylene group constituting the ether portion of the fluorinated alkyl group (b) having the above ether bond may be a straight-chain or branched-chain alkylene group. An example of a minimum structural unit constituting such a straight-chain or branched-chain alkylene group is shown below.

[0330] (i) Minimum structural unit in a linear chain:

[0331] -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0332] (ii) Minimum structural unit of a branched chain:

[0333]

[0334] The alkylene group may consist of these minimum structural units alone, or may consist of straight chains (i) together, branched chains (ii) together, or a combination of straight chains (i) and branched chains (ii). Preferred embodiments are described below.

[0335] In addition, among the examples above, it is preferable to be composed of a constituent unit that does not contain Cl, as this prevents the deHCl reaction caused by a base and is more stable.

[0336] As a more desirable fluorinated alkyl group (b) having an ether bond, general formula (b-1):

[0337] R 10 -(OR 11 ) n2 - (b-1)

[0338] (during food, R 10 An alkyl group having 1 to 6 carbon atoms, which may have a fluorine atom; R 11 An alkylene group having 1 to 4 carbon atoms, which may have a fluorine atom; n2 is an integer from 1 to 3; provided that R 3 and R 4 Examples include those represented as having at least one fluorine atom.

[0339] R 10 and R 11 The following examples may be provided, and by appropriately combining them, a fluorinated alkyl group (b) having an ether bond represented by the general formula (b-1) may be formed, but is not limited to these.

[0340] (1) R 10 As, general formula: X c3C-(R 12 ) n3 -(3 X c is the same or different and all H or F; R 12 is an alkylene group that may have a fluorine atom having 1 to 5 carbon atoms; n3 is preferably an alkyl group represented by 0 or 1).

[0341] If n3 is 0, R 10 Examples include CH3-, CF3-, HCF2-, and H2CF-.

[0342] As a specific example where n3 is 1, R 10As this linear one, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CF2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2CF2CH2CH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, CH3CF2-, CH3CH2-, CH3CF2CH2-, CH3CF2CF2-, CH3CH2CH2-, CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CH2CH2CH2-, CH3CF2CH2CF2CH2-, Examples include CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CH2CF2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, etc.

[0343] n3 is 1, and also R 10 As for this branched chain structure,

[0344]

[0345] You can lift the back.

[0346] However, since viscosity tends to increase if it has branches called CH3- or CF3-, R 10 It is more desirable that this is a linear chain.

[0347] (2) -(OR of the above general formula (b-1) 4 ) n2 - In this case, n2 is an integer from 1 to 3, preferably 1 or 2. Also, when n2=2 or 3, R 11 It may be the same or different.

[0348] R 11 As a preferred embodiment, the following linear or branched chain type may be exemplified.

[0349] Examples of linear chains include -CH2-, -CHF-, -CF2-, -CH2CH2-, -CF2CH2-, -CF2CF2-, -CH2CF2-, -CH2CH2CH2-, -CH2CH2CF2-, -CH2CF2CH2-, -CH2CF2CF2-, -CF2CH2CH2-, -CF2CF2CH2-, -CF2CH2CF2-, etc.

[0350] As for branched chain types,

[0351]

[0352] You can lift the back.

[0353] The above-mentioned fluorinated alkoxy group (c) is formed by substituting at least one hydrogen atom of the alkoxy group with a fluorine atom. The above-mentioned fluorinated alkoxy group (c) preferably has 1 to 17 carbon atoms. More preferably, it has 1 to 6 carbon atoms.

[0354] As for the above fluorinated alkoxy group (c), general formula: X d 3C-(R 13 ) n3 -O-(3 X's d is the same or different and all are H or F; R 13is preferably an alkylene group having a fluorine atom having 1 to 5 carbon atoms; n3 is 0 or 1; and only 3 X d Fluorinated alkoxy groups, represented as (which contain a fluorine atom), are particularly desirable.

[0355] As a specific example of the above-mentioned fluorinated alkoxy group (c), R in the above-mentioned general formula (a-1) 8 Examples include fluorinated alkoxy groups in which an oxygen atom is bonded to the terminal of the alkyl group exemplified as such.

[0356] In the above-mentioned fluorinated saturated cyclic carbonate, 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 preferably 10 mass% or more. If the fluorine content is too low, there is a risk that the effect of reducing viscosity at low temperatures or raising the flash point at low temperatures may not be sufficiently obtained. In this regard, the fluorine content is more preferably 12 mass% or more, and even more preferably 15 mass% or more. The upper limit is typically 76 mass%.

[0357] 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 calculated by {(number of fluorine atoms × 19) / formula of each group} × 100 (%) based on the structural formula of each group.

[0358] In addition, regarding good dielectric constant and oxidation resistance, the fluorine content of the entire fluorinated saturated cyclic carbonate is preferably 10 mass% or more, and more preferably 15 mass% or more. The upper limit is typically 76 mass%.

[0359] In addition, the fluorine content of the above-mentioned fluorinated saturated cyclic carbonate is a value calculated by {(number of fluorine atoms × 19) / molecular weight of fluorinated saturated cyclic carbonate} × 100 (%) based on the structural formula of the fluorinated saturated cyclic carbonate.

[0360] Specifically, the above-mentioned fluorinated saturated cyclic carbonates include, for example, the following.

[0361] X 1 To X 4 As a specific example of a fluorinated saturated cyclic carbonate in which at least one of the is -F,

[0362]

[0363] Examples include these compounds. These compounds have high dielectric strength and good solubility in electrolyte salts.

[0364] In addition,

[0365]

[0366] The back can also be used.

[0367] X 1 To X 4 A specific example of a fluorinated saturated cyclic carbonate in which at least one is a fluorinated alkyl group (a) and the remainder are all -H is:

[0368]

[0369]

[0370]

[0371] You can lift the back.

[0372] X 1 To X 4 A specific example of a fluorinated saturated cyclic carbonate in which at least one is a fluorinated alkyl group (b) having an ether bond or a fluorinated alkoxy group (c), and the remainder are all -H, is:

[0373]

[0374]

[0375]

[0376]

[0377]

[0378]

[0379] You can lift the back.

[0380] Among these, the above-mentioned fluorinated saturated cyclic carbonate is preferably any of the following compounds.

[0381]

[0382]

[0383] In addition to the above, the fluorinated saturated cyclic carbonates include trans-4,5-difluoro-1,3-dioxolan-2-one, 5-(1,1-difluoroethyl)-4,4-difluoro-1,3-dioxolan-2-one, 4-methylene-1,3-dioxolan-2-one, 4-methyl-5-trifluoromethyl-1,3-dioxolan-2-one, 4-ethyl-5-fluoro-1,3-dioxolan-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one, 4-ethyl-4,5,5-trifluoro-1,3-dioxolan-2-one, 4,4-difluoro-5-methyl-1,3-dioxolan-2-one, Examples include 4-fluoro-5-methyl-1,3-dioxolan-2-one, 4-fluoro-5-trifluoromethyl-1,3-dioxolan-2-one, 4,4-difluoro-1,3-dioxolan-2-one, etc.

[0384] Among the above fluorinated saturated cyclic carbonates, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethylethylene carbonate (3,3,3-trifluoropropylene carbonate), and 2,2,3,3,3-pentafluoropropylethylene carbonate are more preferred.

[0385] The above-mentioned fluorinated unsaturated cyclic carbonate is a cyclic carbonate having unsaturated bonds and fluorine atoms, and is preferably a fluorinated ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon double bond. Specifically, examples include 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-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, etc.

[0386] The above-mentioned fluorinated cyclic carbonates may be used as a single type, or two or more types may be used in any combination and ratio.

[0387] When the above-mentioned fluorinated cyclic carbonate is included, the content of the above-mentioned fluorinated cyclic carbonate is preferably 5 to 90 volume% with respect to the solvent, more preferably 10 to 60 volume%, and even more preferably 15 to 45 volume%.

[0388] The above chain carbonate may be a non-fluorinated chain carbonate or a fluorinated chain carbonate.

[0389] Examples of the above-mentioned non-fluorinated chain carbonates include hydrocarbon chain carbonates such as 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, and ethyl phenyl carbonate. Among these, it is preferable that at least one is selected from the group consisting of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate.

[0390] The above-mentioned non-fluorinated chain carbonates may be used as a single type, or two or more types may be used in any combination and ratio.

[0391] When the above-mentioned non-fluorinated chain carbonate is included, the content of the above-mentioned non-fluorinated chain carbonate is preferably 10 to 90 volume% with respect to the solvent, more preferably 40 to 85 volume%, and even more preferably 50 to 80 volume%.

[0392] The above-mentioned fluorinated chain carbonate is a chain carbonate having fluorine atoms. A solvent containing the fluorinated chain carbonate can be suitably used even under high voltage.

[0393] As the above-mentioned fluorinated chain carbonate, general formula (B):

[0394] Rf 3 OCOOR 14 (B)

[0395] (during food, Rf 3 Silver, a fluorinated alkyl group having 1 to 7 carbon atoms, and R 14Examples of compounds represented by α is an alkyl group that may include fluorine atoms having 1 to 7 carbon atoms.

[0396] Rf 3 Silver, a fluorinated alkyl group having 1 to 7 carbon atoms, and R 14 is an alkyl group that may include a fluorine atom having 1 to 7 carbon atoms.

[0397] The above fluorinated alkyl group is one in which at least one of the hydrogen atoms of the alkyl group is substituted with a fluorine atom. R 14 If it is an alkyl group containing a fluorine atom, it becomes a fluorinated alkyl group.

[0398] Rf 3 and R 14 In terms of low viscosity, it is preferable that the carbon number is 1 to 7, and more preferable that it is 1 to 2.

[0399] If the number of carbon atoms becomes too large, there is a risk that low-temperature characteristics may deteriorate or the solubility of the electrolyte salt may decrease; conversely, if the number of carbon atoms is too small, a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, and even an increase in viscosity may occur.

[0400] Examples of fluorinated alkyl groups having one carbon atom include CFH2-, CF2H-, CF3-, etc. In particular, CFH2- or CF3- is preferred due to high-temperature storage properties.

[0401] As a fluorinated alkyl group having 2 or more carbon atoms, the following general formula (d-1):

[0402] R 1 -R 2 - (d-1)

[0403] (during food, R 1 An alkyl group having 1 or more carbon atoms that may have a fluorine atom; R 2 is an alkylene group having 1 to 3 carbon atoms that may have a fluorine atom; provided, R 1 and R 2A fluorinated alkyl group represented by (at least one of which has a fluorine atom) can be preferably exemplified in that it has good solubility in the electrolyte salt.

[0404] Also, R 1 and R 2 It may also have other atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0405] R 1 It is an alkyl group having one or more carbon atoms that may contain silver or fluorine atoms. R 1 As for, a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms is preferred. R 1 As for the number of carbon atoms, 1 to 3 is more preferable.

[0406] R 1 As, specifically, as a straight-chain or branched-chain alkyl group, CH3-, CF3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0407]

[0408] You can lift the back.

[0409] Also, R 1In the case of a straight-chain alkyl group having this fluorine atom, CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CF2CH2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CF2CF2CH2CH2CH2-, CF3CF2CF2CH2CH2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CF2CH2CH2CH2-, CF3CF2CF2CF2CH2CH2-, CF3CF2CF2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HCFClCF2CFClCF2CH2-, etc.

[0410] Also, R 1 In the case where it is a branched-chain alkyl group having this fluorine atom,

[0411]

[0412]

[0413] The following can be preferably cited. However, since viscosity tends to increase if it has branches such as CH3- or CF3-, it is more preferable that the number be small (1) or zero.

[0414] R 2 is an alkylene group having 1 to 3 carbon atoms that may have a fluorine atom. R 2 It may be in the form of a straight chain or a branched chain. An example of the minimum structural unit constituting such a straight or branched alkylene group is shown below. R 2 It consists of these alone or in combination.

[0415] (i) Minimum structural unit in a linear chain:

[0416] -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0417] (ii) Minimum structural unit of a branched chain:

[0418]

[0419] In addition, among the examples above, it is preferable to be composed of a constituent unit that does not contain Cl, as this prevents the deHCl reaction caused by a base and is more stable.

[0420] R 2 In the case of a straight chain, it comprises only the minimum structural unit of the straight chain described above, and among them, -CH2-, -CH2CH2-, or -CF2- is preferred. -CH2- or -CH2CH2- is more preferred in that it can further improve the solubility of the electrolyte salt.

[0421] R 2 In the case of a branched chain structure, it is formed by including at least one minimum structural unit of the branched chain structure described above, and the general formula -(CX a X b )-(X ais H, F, CH3 or CF3; X b is CH3 or CF3. However, X b If is CF3, X a It can preferably be exemplified by being represented as H or CH3). These can particularly further improve the solubility of electrolyte salts.

[0422] As preferred fluorinated alkyl groups, specifically, for example, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CH2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0423]

[0424]

[0425] You can lift the back.

[0426] Among them, Rf 3 and R 14 As for the fluorinated alkyl groups, CF3-, CF3CF2-, (CF3)2CH-, CF3CH2-, C2F5CH2-, CF3CF2CH2-, HCF2CF2CH2-, CF3CFHCF2CH2-, CFH2-, and CF2H- are preferred, and CF3CH2-, CF3CF2CH2-, HCF2CF2CH2-, CFH2-, and CF2H- are more preferred in that they have high flame retardancy and good rate characteristics and oxidation resistance.

[0427] R 14 If α is an alkyl group that does not contain a fluorine atom, it is an alkyl group having 1 to 7 carbon atoms. R 14 In terms of low viscosity, it is preferable that the carbon number is 1 to 4, and more preferable that it is 1 to 3.

[0428] Examples of alkyl groups that do not contain the above-mentioned fluorine atoms include CH3-, CH3CH2-, (CH3)2CH-, C3H7-, etc. Among these, CH3- and CH3CH2- are preferred because they have low viscosity and good rate characteristics.

[0429] The above-described fluorinated chain carbonate preferably has a fluorine content of 15 to 70 mass%. If the fluorine content is within the range described above, compatibility with solvents and solubility of salts can be maintained. The above-described fluorine content is more preferably 20 mass% or more, more preferably 30 mass% or more, particularly preferably 35 mass% or more, more preferably 60 mass% or less, and more preferably 50 mass% or less.

[0430] In addition, in the present disclosure, the fluorine content is based on the structural formula of the fluorinated chain carbonate,

[0431] {(Number of fluorine atoms × 19) / Molecular weight of fluorinated chain carbonate} × 100 (%)

[0432] It is a value calculated by.

[0433] As for the above-mentioned fluorinated chain carbonate, it is preferable to be any of the following compounds in that it has low viscosity.

[0434]

[0435] As the above-mentioned fluorinated chain carbonate, methyl 2,2,2-trifluoroethyl carbonate (F3CH2COC(=O)OCH3) is particularly preferred.

[0436] The above-mentioned fluorinated chain carbonates may be used as a single type, or two or more types may be used in any combination and ratio.

[0437] When the above-mentioned fluorinated chain carbonate is included, the content of the above-mentioned fluorinated chain carbonate is preferably 10 to 90 volume% with respect to the solvent, more preferably 40 to 85 volume%, and even more preferably 50 to 80 volume%.

[0438] The above carboxylic acid ester may be a cyclic carboxylic acid ester or a chain carboxylic acid ester.

[0439] The above cyclic carboxylic acid ester may be a non-fluorinated cyclic carboxylic acid ester or a fluorinated cyclic carboxylic acid ester.

[0440] Examples of the above-mentioned non-fluorinated cyclic carboxylic acid esters 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.

[0441] Specific examples of non-fluorinated saturated cyclic carboxylic acid esters 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 these, γ-butyrolactone and δ-valerolactone are particularly preferred in terms of improving lithium ion dissociation and load characteristics.

[0442] The above-mentioned non-fluorinated saturated cyclic carboxylic acid esters may be used alone, or two or more may be used in any combination and ratio.

[0443] When the above-mentioned non-fluorinated saturated cyclic carboxylic acid ester is included, the content of the above-mentioned non-fluorinated saturated cyclic carboxylic acid ester is preferably 0 to 90 volume% with respect to the solvent, more preferably 0.001 to 90 volume%, even more preferably 1 to 60 volume%, and particularly preferably 5 to 40 volume%.

[0444] The above chain carboxylic acid ester may be a non-fluorinated chain carboxylic acid ester or a fluorinated chain carboxylic acid ester. When the above solvent contains the above chain carboxylic acid ester, the increase in resistance after high-temperature storage of the liquid electrolyte can be further suppressed.

[0445] As the above-mentioned non-fluorinated chain carboxylic acid ester, for example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, tert-butylpropionate, tert-butylbutyrate, sec-butylpropionate, sec-butylbutyrate, n-butylbutyrate, methyl pyrophosphate, ethyl pyrophosphate, tert-butylformate, tert-butylacetate, sec-butylformate, sec-butylacetate, n-hexylpivalate, n-propylformate, n-propylacetate, n-butylformate, n-butylpivalate, n-octylpivalate, ethyl 2-(dimethoxyphosphoryl)acetate, ethyl 2-(dimethylphosphoryl)acetate, Examples include ethyl 2-(diethoxyphosphoryl)acetate, ethyl 2-(diethylphosphoryl)acetate, isopropylpropionate, isopropylacetate, ethyl formate, ethyl 2-propynyl oxalate, isopropyl formate, isopropylbutyrate, isobutyl formate, isobutylpropionate, isobutylbutyrate, isobutyl acetate, etc.

[0446] Among these, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and particularly preferably ethyl propionate and propyl propionate.

[0447] The above-mentioned non-fluorinated chain carboxylic acid ester may be used alone, or two or more may be used in any combination and ratio.

[0448] When the above-mentioned non-fluorinated chain carboxylic acid ester is included, the content of the above-mentioned non-fluorinated chain carboxylic acid ester is preferably 0 to 90 volume% with respect to the solvent, more preferably 0.001 to 90 volume%, even more preferably 1 to 60 volume%, and particularly preferably 5 to 40 volume%.

[0449] The above-mentioned 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 under high voltage.

[0450] As the above-mentioned fluorinated chain carboxylic acid ester, the following general formula:

[0451] R 31 COOR 32

[0452] (during food, R 31 and R 32 is an alkyl group that may independently include a fluorine atom having 1 to 4 carbon atoms, and R 31 and R 32 A fluorinated chain carboxylic acid ester represented by (at least one of which contains a fluorine atom) is preferred in that it has good compatibility with other solvents and oxidation resistance.

[0453] R 31 and R 32As, for example, non-fluorinated alkyl groups such as methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), normal butyl (-CH2CH2CH2CH3), tert-butyl (-C(CH3)3); -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,Examples include fluorinated alkyl groups such as -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, etc. Among these, methyl groups, ethyl groups, -CF3, -CF2H, -CF2CF3, -CH2CF3, -CH2CF2H, -CH2CFH2, -CH2CH2CF3, -CH2CF2CF3, -CH2CF2CF2H, and -CH2CF2CFH2 are particularly preferred in that they have good compatibility with other solvents, viscosity, and oxidation resistance.

[0454] Specific examples of the above-mentioned fluorinated chain carboxylic acid esters include, for example, CF3CH2C(=O)OCH3(3,3,3-methyl trifluoropropionate), HCF2C(=O)OCH3(methyl difluoroacetate), HCF2C(=O)OC2H5(ethyl difluoroacetate), CF3C(=O)OCH2CH2CF3, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H(2,2,3,3-tetrafluoropropyl trifluoroacetate), CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, 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(2,2,2-trifluoroethyl acetate), 1H,1H-heptafluorobutyl acetate, 4,4,4-methyl trifluorobutyrate, 4,4,4-ethyl trifluorobutyrate, 3,3,3-ethyl trifluoropropionate, 3,3,3-trifluoropropyl trifluoropropionate, 3-(trifluoromethyl)ethyl butyrate, 2,3,3,3-methyl tetrafluoropropionate, 2,2-butyl difluoroacetate, 2,2,3,3-methyl tetrafluoropropionate, One or more examples may include 2-(trifluoromethyl)-3,3,3-methyl trifluoropropionate, methyl heptafluorobutyrate, etc.

[0455] 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 heptafluoroisobutyrate, 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,1H-heptafluorobutyl acetate, 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, 2,2-butyl difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, and methyl heptafluorobutyrate are preferred in that they have good compatibility with other solvents and rate characteristics, and CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, and CH3C(=O)OCH2CF3 are more It is desirable, and HCF2C(=O)OCH3, HCF2C(=O)OC2H5, and CH3C(=O)OCH2CF3 are particularly desirable.

[0456] The above-mentioned fluorinated chain carboxylic acid ester may be used alone, or two or more may be used in any combination and ratio.

[0457] When the above-mentioned fluorinated chain carboxylic acid ester is included, the content of the above-mentioned fluorinated chain carboxylic acid ester is preferably 10 to 90 volume% with respect to the solvent, more preferably 40 to 85 volume%, and even more preferably 50 to 80 volume%.

[0458] The solvent preferably comprises at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester, and more preferably comprises at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester. The cyclic carbonate is preferably a saturated cyclic carbonate.

[0459] A liquid electrolyte containing a solvent of the above composition can further improve the high-temperature storage characteristics or cycle characteristics of an electrochemical device.

[0460] When the solvent comprises at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester, it is preferable to include a total of 10 to 100 volume% of the at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester, more preferable to include 30 to 100 volume%, and even more preferable to include 50 to 100 volume%.

[0461] When the solvent comprises at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester, the volume ratio of the at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or higher, even more preferably 15 / 85 or higher, particularly preferably 20 / 80 or higher, more preferably 90 / 10 or lower, even more preferably 60 / 40 or lower, and particularly preferably 50 / 50 or lower.

[0462] The solvent is also preferably selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated chain carbonate, and the non-fluorinated chain carboxylic acid ester, and is more preferably selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated chain carbonate, and the non-fluorinated chain carboxylic acid ester. A liquid electrolyte containing a solvent of the above composition can be suitably used in electrochemical devices used at relatively low voltages.

[0463] When the solvent comprises at least one selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated chain carbonate, and the non-fluorinated chain carboxylic acid ester, it is preferable to include a total of 5 to 100 volume% of the at least one selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated chain carbonate, and the non-fluorinated chain carboxylic acid ester, more preferable to include 20 to 100 volume%, and even more preferable to include 30 to 100 volume%.

[0464] When the above liquid electrolyte comprises at least one selected from the group consisting of the above non-fluorinated saturated cyclic carbonate, the above non-fluorinated chain carbonate, and the above non-fluorinated chain carboxylic acid ester, the volume ratio of the at least one selected from the group consisting of the above non-fluorinated saturated cyclic carbonate, the above non-fluorinated chain carbonate, and the above non-fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or higher, even more preferably 15 / 85 or higher, particularly preferably 20 / 80 or higher, more preferably 90 / 10 or lower, even more preferably 60 / 40 or lower, and particularly preferably 50 / 50 or lower.

[0465] The above solvent is also preferably selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester, and is more preferably selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester. A liquid electrolyte containing a solvent of the above composition can be suitably used not only in electrochemical devices used at relatively low voltages but also in electrochemical devices used at relatively high voltages.

[0466] When the solvent comprises at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester, it is preferable to include a total of 5 to 100 volume% of the at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester, more preferable to include 10 to 100 volume%, and even more preferable to include 30 to 100 volume%.

[0467] When the solvent comprises at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester, the volume ratio of the at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or higher, even more preferably 15 / 85 or higher, particularly preferably 20 / 80 or higher, more preferably 90 / 10 or lower, even more preferably 60 / 40 or lower, and particularly preferably 50 / 50 or lower.

[0468] In addition, an ionic liquid may be used as the solvent. An "ionic liquid" is a liquid containing ions that combine organic cations and anions.

[0469] Examples of organic cations include, although not specifically limited, imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0470] As anions that serve as counters to these organic cations, examples may be used, although not specifically limited, such as 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, dicyanoamine anion, and halide anion.

[0471] The above solvent is preferably a non-aqueous solvent, and the liquid electrolyte of the present disclosure is preferably a non-aqueous liquid electrolyte.

[0472] The content of the above solvent is preferably 70 to 99.999 mass% of the liquid electrolyte, more preferably 80 mass% or more, and more preferably 92 mass% or less.

[0473] The liquid electrolyte of the present disclosure may also include a compound (8) represented by the general formula (8).

[0474] General formula (8):

[0475]

[0476] (during food, A a+ Silver metal ion, hydrogen ion, or 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 Silver is a transition metal, an element of Group III, IV, or V of the periodic table.

[0477] X 201 Silver, O, S, an alkylene group having 1 to 10 carbon atoms, an alkylene halide group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or an arylene halide group having 6 to 20 carbon atoms (the alkylene group, the alkylene halide group, the arylene group, and the arylene halide group may have substituents or heteroatoms in their structure, and also when n202 is 1 and n203 is 2 to 4, n 203 x 201 Each may be combined).

[0478] L 201Silver, halogen atom, cyano group, alkyl group having 1 to 10 carbon atoms, alkyl halide group having 1 to 10 carbon atoms, aryl group having 6 to 20 carbon atoms, aryl halide group having 6 to 20 carbon atoms (alkylene group, alkylene halide group, arylene group, and arylene halide group may have substituents or heteroatoms in their structure, and also when n201 is 2 to 8, n201 L 201 (each may combine to form a ring) or -Z 203 Y 203 . Y 201 , Y 202 and Z 203 are, each independent, O, S, NY 204 , hydrocarbon group or fluorinated hydrocarbon group. Y 203 and Y 204 Each is independent of H, F, an alkyl group having 1 to 10 carbon atoms, an alkyl halide group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryl halide group having 6 to 20 carbon atoms (alkyl groups, alkyl halide groups, aryl groups, and aryl halides may have substituents or heteroatoms in their structure, and Y 203 or Y 204 If multiple units exist, each may combine to form a ring.

[0479] A a +Examples include lithium ions, sodium ions, potassium ions, magnesium ions, calcium ions, barium ions, cesium ions, silver ions, zinc ions, copper ions, cobalt ions, iron ions, nickel ions, manganese ions, titanium ions, lead ions, chromium ions, vanadium ions, ruthenium ions, yttrium ions, lanthanoid ions, actinoid ions, tetrabutylammonium ions, tetraethylammonium ions, tetramethylammonium ions, triethylmethylammonium ions, triethylammonium ions, pyridinium ions, imidazolium ions, hydrogen ions, tetraethylphosphonium ions, tetramethylphosphonium ions, tetraphenylphosphonium ions, triphenylsulfonium ions, triethylsulfonium ions, etc.

[0480] When used for purposes such as electrochemical devices, A a + Silver, lithium ions, sodium ions, magnesium ions, tetraalkylammonium ions, and hydrogen ions are preferred, and lithium ions are particularly preferred. A a + The valence a of the cation is an integer from 1 to 3. If it is greater than 3, the crystal lattice energy increases, which causes a problem in that it becomes difficult to dissolve in a solvent. Therefore, 1 is more preferable when solubility is required. The valence b of the anion is likewise an integer from 1 to 3, and 1 is particularly preferred. The constant p, which represents the ratio of the cation to the anion, is inevitably determined by the ratio of the valences of the two ions, b / a.

[0481] Next, the part of the ligand of general formula (8) is described. In this specification, Z in general formula (8) 201 The organic or inorganic part that is bonded to is called a ligand.

[0482] Z 201It is preferable that it be Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf, or Sb, and more preferable that it be Al, B, or P.

[0483] X 201 It represents silver, O, S, an alkylene group having 1 to 10 carbon atoms, an alkylene halide group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or an arylene halide group having 6 to 20 carbon atoms. These alkylene groups and arylene groups may have substituents or heteroatoms in their structure. Specifically, they may have halogen atoms, chain or cyclic alkyl groups, aryl groups, alkenyl groups, alkoxy groups, aryloxy groups, sulfonyl groups, amino groups, cyano groups, carbonyl groups, acyl groups, amide groups, or hydroxyl groups as substituents in place of hydrogen on the alkylene and arylene groups, or they may have a structure in which nitrogen, sulfur, or oxygen is introduced in place of carbon on the alkylene and arylene groups. In addition, n 202 ga is 1 and n 203 When this is 2 to 4, n203 X 201 Each of them may be bonded. An example of such a ligand is ethylenediaminetetraacetic acid.

[0484] L 201 Silver, halogen atom, cyano group, alkyl group having 1 to 10 carbon atoms, alkyl halide group having 1 to 10 carbon atoms, aryl group having 6 to 20 carbon atoms, aryl halide group having 6 to 20 carbon atoms, or -Z 203 Y 203 (Z 203 , Y 203 (Described later) represents. The alkyl and aryl groups here, X 201 Likewise, it may contain substituents or heteroatoms in its structure, and also, when n201 is 2 to 8, n201 L 201 Each may combine to form a ring. L 201As such, a fluorine atom or a cyano group is preferred. In the case of a fluorine atom, the solubility or degree of dissociation of the salt of the anionic compound is improved, and consequently, the ionic conductivity is improved. In addition, oxidation resistance is improved, and thereby the occurrence of side reactions can be suppressed.

[0485] Y 201 , Y 202 and Z 203 are, each independent, O, S, NY 204 , represents a hydrocarbon group or a fluorinated hydrocarbon group. Y 201 and Y 202 는, O, S, or NY 204 It is preferable that it is O, and more preferable that it is O. As a characteristic of compound (8), Y within the same ligand 201 and Y 202 Z by 201 Because of the bonding with, these ligands are Z 201 It forms a chelate structure. Due to the effect of this chelate, the heat resistance, chemical stability, and hydrolytic resistance of this compound are improved. The constant n2O2 in this ligand is 0 or 1; in particular, when it is 0, this chelating ring becomes a pentagonal ring, so the chelating effect is most strongly exerted and stability is increased, which is desirable.

[0486] Additionally, in this specification, a fluorinated hydrocarbon group is a group in which at least one hydrogen atom of the hydrocarbon group is substituted with a fluorine atom.

[0487] Y 203 and Y 204 Each is independent and is H, F, an alkyl group having 1 to 10 carbon atoms, an alkyl halide group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryl halide group having 6 to 20 carbon atoms, and these alkyl groups and aryl groups may have substituents or heteroatoms in their structure, and also Y 203 or Y 204If there are multiple units, each may combine to form a ring.

[0488] In addition, a constant n related to the number of the aforementioned ligands 203 ...is an integer from 1 to 4, preferably 1 or 2, and more preferably 2. In addition, a constant n related to the number of the aforementioned ligands. 201 Silver is an integer from 0 to 8, preferably an integer from 0 to 4, and more preferably 0, 2, or 4. Also, n 203 When this is 1, n 201 2, n 203 When this is 2, n 201 It is desirable that it be 0.

[0489] In general formula (8), the alkyl group, alkyl halide group, aryl group, and aryl halide group may also have other functional groups such as branches, hydroxyl groups, or ether bonds.

[0490] As for compound (8), general formula:

[0491]

[0492] (during food, A a + , a, b, p, n201, Z 201 and L 201 is a compound represented by (as previously mentioned), or, general formula:

[0493]

[0494] (during food, A a + , a, b, p, n201, Z 201 and L 201 It is preferable that it be a compound represented as (as previously mentioned).

[0495] As for compounds (8), lithium oxalatoborate salts can be used, and the following formula:

[0496]

[0497] Lithium bis(oxalato)borate (LIBOB), denoted by the following formula:

[0498]

[0499] Lithium difluorooxalatoborate (LIDFOB), represented as

[0500] As for compound (8), also, the following formula:

[0501]

[0502] Lithium difluorooxalatophosphanite (LIDFOP) represented by the following formula:

[0503]

[0504] Lithium tetrafluorooxalatophosphanite (LITFOP) represented by the following formula:

[0505]

[0506] Examples include lithium bis(oxalato)difluorophosphanite, which is represented as such.

[0507] Other specific examples of dicarboxylic acid complex salts in which the complex center element is boron include lithium bis(malonato)borate, lithium difluoro(malonato)borate, lithium bis(methylmalonato)borate, lithium difluoro(methylmalonato)borate, lithium bis(dimethylmalonato)borate, and lithium difluoro(dimethylmalonato)borate.

[0508] Specific examples of dicarboxylic acid complex salts in which the complex center element is phosphorus include lithium tris(oxalato)phosphate, lithium tris(malonato)phosphate, lithium difluorobis(malonato)phosphate, lithium tetrafluoro(malonato)phosphate, lithium tris(methylmalonato)phosphate, lithium difluorobis(methylmalonato)phosphate, lithium tetrafluoro(methylmalonato)phosphate, lithium tris(dimethylmalonato)phosphate, lithium difluorobis(dimethylmalonato)phosphate, lithium tetrafluoro(dimethylmalonato)phosphate, and the like.

[0509] Specific examples of dicarboxylic acid complex salts in which the complex center element is aluminum include LiAl(C2O4)2 and LiAlF2(C2O4).

[0510] Among them, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate are more suitablely used in that they contribute to ease of availability and the formation of stable film-like structures.

[0511] As for the compound (8), lithium bis(oxalato)borate is particularly preferred.

[0512] As for the content of compound (8), it is preferable to have 0.001 mass% or more with respect to the solvent, more preferably 0.01 mass% or more, more preferably 10 mass% or less, and more preferably 3 mass% or less, in order to obtain even better cycle characteristics.

[0513] The liquid electrolyte of the present disclosure also preferably comprises an electrolyte salt (except for compounds (1) and (8)). As the electrolyte salt, any salt that can be used in a liquid electrolyte may be used, such as a liquid salt (ionic liquid), an inorganic polymer-type salt, an organic polymer-type salt, in addition to a lithium salt, an ammonium salt, and a metal salt.

[0514] As an electrolyte salt for a liquid electrolyte for a lithium-ion secondary battery, a lithium salt is preferred. Any lithium salt may be used, and specifically, the following may be cited. For example, LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiTaF6, LiWF7, LiAsF6, LiAlCl4, LiI, LiBr, LiCl, LiB 10 Cl 10 Inorganic lithium salts such as Li2SiF6, Li2PFO3, LiPO2F2, etc.;

[0515] Lithium tungstates such as LiWOF5;

[0516] Lithium carboxylate salts such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li, etc.

[0517] Lithium salts having an S=O group, such as FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li, lithium methyl sulfate, lithium ethyl sulfate (C2H5OSO3Li), lithium 2,2,2-trifluoroethyl sulfate, etc.;

[0518] Lithium imide salts such as LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium bisperfluoroethanesulfonylimide, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, lithium cyclic 1,2-ethanedisulfonylimide, lithium cyclic 1,3-propanedisulfonylimide, lithium cyclic 1,4-perfluorobutanedisulfonylimide, LiN(CF3SO2)(FSO2), LiN(CF3SO2)(C3F7SO2), LiN(CF3SO2)(C4F9SO2), LiN(POF2)2, etc.;

[0519] Lithium methide salts such as LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, etc.

[0520] Others, Formula: LiPF a (C n F 2n+1 )6 -aSalts represented by (wherein a is an integer from 0 to 5 and n is an integer from 1 to 6) (e.g., fluorine-containing organic lithium salts such as 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., LiSCN, LiB(CN)4, LiB(C6H5)4, Li2(C2O4), LiP(C2O4)3, Li2B 12 F b H 12 -b Examples include (b is an integer from 0 to 3).

[0521] Among these, LiPF6, LiBF4, LiSbF6, LiTaF6, LiPO2F2, FSO3Li, CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, etc. are particularly desirable in that they have the effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, cycle characteristics, etc., and at least one type selected from the group consisting of LiPF6, LiN(FSO2)2, and LiBF4 Lithium salts are the most desirable.

[0522] These electrolyte salts may be used alone or in combination of two or more. A preferred example of using two or more in combination is the combination of LiPF6 and LiBF4, or the combination of LiPF6 and LiPO2F2, C2H5OSO3Li, or FSO3Li, which has the effect of improving high temperature storage characteristics, load characteristics, and cycle characteristics.

[0523] In this case, there is no limitation on the amount of LiBF4, LiPO2F2, C2H5OSO3Li, or FSO3Li mixed with respect to the total liquid electrolyte of 100 mass%, and as long as it does not significantly impair the effects of the present disclosure, the amount is typically 0.01 mass% or more, preferably 0.1 mass% or more, with respect to the liquid electrolyte of the present disclosure, and is also typically 30 mass% or less, preferably 20 mass% or less, more preferably 10 mass% or less, and even more preferably 5 mass% or less.

[0524] In addition, another example is the combined use of inorganic lithium salts and organic lithium salts, and the combined use of these two has the effect of suppressing degradation caused by high-temperature storage. As for the organic lithium salt, it is preferable to use CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, 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 to the total 100 mass% of the liquid electrolyte is preferably 0.1 mass% or more, particularly preferably 0.5 mass% or more, and also preferably 30 mass% or less, particularly preferably 20 mass% or less.

[0525] The concentration of these electrolyte salts in the liquid electrolyte is not particularly limited as long as it does not impair the effects of the present disclosure. In order to ensure good battery performance and to maintain the electrical conductivity of the liquid electrolyte in a good range, 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 even more preferably 0.5 mol / L or more, and is also preferably 4.0 mol / L or less, more preferably 3.8 mol / L or less, and even more preferably 3.5 mol / L or less.

[0526] If the total molar concentration of lithium is too low, the electrical conductivity of the liquid electrolyte may be insufficient; on the other hand, if the concentration is too high, the electrical conductivity may decrease due to increased viscosity, which may lead to a decrease in battery performance.

[0527] As the electrolyte salt for the liquid electrolyte of an electric double layer capacitor, an ammonium salt is preferred.

[0528] Examples of the above ammonium salts include (IIa) to (IIe) below.

[0529] (IIa) Tetraalkyl quaternary ammonium salt

[0530] General formula (IIa):

[0531]

[0532] (during food, R 1a , R 2a , R 3a and R 4a is an alkyl group that is identical or different and may all include an ether bond having 1 to 6 carbon atoms; X - is anion)

[0533] Tetraalkyl quaternary ammonium salts represented by [formula] can be preferably exemplified. In addition, it is also preferable that some or all of the hydrogen atoms of this ammonium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms, in that oxidation resistance is improved.

[0534] As a specific example, general formula (IIa-1):

[0535]

[0536] (during food, R 1a , R 2a and X - is the same as above; x and y are the same or different and are integers from 0 to 4, and also x+y=4)

[0537] Tetraalkyl quaternary ammonium salt represented by, general formula (IIa-2):

[0538]

[0539] (during food, 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 - is anion)

[0540] A trialkylammonium salt containing an alkyl ether group represented by,

[0541] Examples include the above. By introducing alkyl ether groups, a reduction in viscosity can be achieved.

[0542] Negative Ion X - It may be an inorganic or an organic anion. As an inorganic anion, for example, AlCl4 - , BF4 - , PF6 - , AsF6 - , TaF6 - , I - , SbF6 - Examples of organic anions include, for instance, bis-oxalatoborate anion, difluorooxalatoborate anion, tetrafluorooxalatophosphate anion, difluorobis-oxalatophosphate anion, CF3COO-, CF3SO3-, (CF3SO2)2N-, (C2F5SO2)2N-, etc.

[0543] Among these, BF4 is good in terms of oxidation resistance or ion dissociation properties. - , PF6 - , AsF6 - , SbF6 - It is desirable.

[0544] Suitable specific examples of tetraalkyl quaternary ammonium salts include Et4NBF4, Et4NC1O4, Et4NPF6, Et4NAsF6, Et4NSbF6, Et4NCF3SO3, Et4N(CF3SO2)2N, Et4NC4F9SO3, Et3MeNBF4, Et3MeNC1O4, Et3MeNPF6, Et3MeNAsF6, Et3MeNSbF6, Et3MeNCF3SO3, Et3MeN(CF3SO2)2N, and Et3MeNC4F9SO3. In particular, Et4NBF4, Et4NPF6, Et4NSbF6, Et4NAsF6, Et3MeNBF4, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium salts, etc.

[0545] (IIb) Spirophanate bipyrrolidinium salt

[0546] General formula (IIb-1):

[0547]

[0548] (during food, R 8a and R 9a is the same or different, and all are alkyl groups having 1 to 4 carbon atoms; X - is an anion; n1 is an integer from 0 to 5; n2 is an integer from 0 to 5)

[0549] Spirocyclic bipyrrolidinium salt represented by, general formula (IIb-2):

[0550]

[0551] (during food, R 10a and R 11a is the same or different, and all are alkyl groups having 1 to 4 carbon atoms; X - is an anion; n3 is an integer from 0 to 5; n4 is an integer from 0 to 5)

[0552] Spirocyclic bipyrrolidinium salt represented by, or, general formula (IIb-3):

[0553]

[0554] (during food, R 12a and R 13a is the same or different, and all are alkyl groups having 1 to 4 carbon atoms; X - is an anion; n5 is an integer from 0 to 5; n6 is an integer from 0 to 5)

[0555] Preferably, a spirocyclic bipyrrolidinium salt represented as such can be cited. In addition, it is also preferable that some or all of the hydrogen atoms of this spirocyclic bipyrrolidinium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms, in order to improve oxidation resistance.

[0556] Negative Ion X - A preferred embodiment of is the same as in the case of (IIa). In particular, BF4-, PF-, in terms of high dissociability and low internal resistance under high voltage 6- , (CF3SO2)2N- or (C2F5SO2)2N- is preferred.

[0557] Preferred embodiments of the Spirophanate bipyrrolidinium salt include, for example

[0558]

[0559] You can lift the back.

[0560] This spiro-based bipyrrolidinium salt is excellent in terms of solvent solubility, oxidation resistance, and ion conductivity.

[0561] (IIc) Imidazolium salt

[0562] General formula (IIc):

[0563]

[0564] (during food, R 14a and R 15a is the same or different, and is all an alkyl group having 1 to 6 carbon atoms; X- is anion)

[0565] An imidazolium salt represented by [this] can be preferably exemplified. In addition, it is also preferable that some or all of the hydrogen atoms of this imidazolium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms, in that oxidation resistance is improved.

[0566] Negative Ion X - A preferred embodiment of is the same as (IIa).

[0567] As a preferred embodiment, for example

[0568]

[0569] You can lift the back.

[0570] This imidazolium salt is excellent in that it has low viscosity and good solubility.

[0571] (IId): N-alkylpyridinium salt

[0572] General formula (IId):

[0573]

[0574] (during food, R 16a is an alkyl group having 1 to 6 carbon atoms; X - is anion)

[0575] An N-alkylpyridinium salt represented by [formula] can be preferably exemplified. In addition, it is also preferable that some or all of the hydrogen atoms of this N-alkylpyridinium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms, in that oxidation resistance is improved.

[0576] Negative Ion X - A preferred embodiment of is the same as (IIa).

[0577] As a preferred embodiment, for example

[0578]

[0579] You can lift the back.

[0580] This N-alkylpyridinium salt is excellent in that it has low viscosity and good solubility.

[0581] (IIe) N,N-dialkylpyrrolidinium salt

[0582] General formula (IIe):

[0583]

[0584] (during food, R 17a and R 18a is the same or different, and is all an alkyl group having 1 to 6 carbon atoms; X - is anion)

[0585] An N,N-dialkylpyrrolidinium salt represented by [formula] can be preferably exemplified. In addition, it is also preferable that some or all of the hydrogen atoms of this N,N-dialkylpyrrolidinium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms, in that oxidation resistance is improved.

[0586] Negative Ion X - A preferred embodiment of is the same as (IIa).

[0587] As a preferred embodiment, for example

[0588]

[0589]

[0590] You can lift the back.

[0591] This N,N-dialkylpyrrolidinium salt is excellent in that it has low viscosity and good solubility.

[0592] Among these ammonium salts, (IIa), (IIb), and (IIc) are preferred in that they have good solubility, oxidation resistance, and ion conductivity, and further

[0593]

[0594] (In the formula, Me is a methyl group; Et is an ethyl group; X - , x, y are the same as in Equation (IIa-1)

[0595] It is desirable.

[0596] In addition, lithium salts may be used as electrolyte salts for electric double-layer capacitors. Examples of preferred lithium salts include LiPF6, LiBF4, LiN(FSO2)2, LiAsF6, LiSbF6, and LiN(SO2C2H5)2.

[0597] In addition, magnesium salts may be used to increase the capacity. As magnesium salts, for example, Mg(ClO4)2, Mg(OOC2H5)2, etc. are preferred.

[0598] When the electrolyte salt is the above ammonium salt, the concentration is preferably 0.7 mol / liter or higher. If it is less than 0.7 mol / liter, not only will the low-temperature characteristics deteriorate, but there is also a risk that the initial internal resistance will increase. It is more preferable that the concentration of the above electrolyte salt is 0.9 mol / liter or higher.

[0599] The upper limit of the above concentration is preferably 2.0 mol / liter or less in terms of low-temperature characteristics, and more preferably 1.5 mol / liter or less.

[0600] When the above ammonium salt is triethylmethylammonium tetrafluoroborate (TEMABF4), the concentration is preferably 0.7 to 1.5 mol / liter, as it has excellent low-temperature properties.

[0601] In addition, in the case of spirobipyrrolidinium tetrafluoride (SBPBF4), it is preferable to have a concentration of 0.7 to 2.0 mol / liter.

[0602] The liquid electrolyte of the present disclosure is, general formula (2):

[0603]

[0604] (during food, X 21 is a group comprising at least H or C, n21 is an integer from 1 to 3, Y 21 and Z 21 is, identical or different, a group containing at least H, C, O or F, n22 is 0 or 1, Y21 and Z 21 It is preferable to further include a compound (2) represented by (which may combine with each other to form a ring). If the liquid electrolyte includes the compound (2), even when stored at high temperatures, it is difficult for the capacity retention rate to decrease further and for the amount of gas generated to increase further.

[0605] If n21 is 2 or 3, 2 or 3 X 21 It may be the same or different.

[0606] Y 21 and Z 21 If this plural exists, Y that exists in the plural 21 and Z 21 It may be the same or different.

[0607] X 21 As, -CY 21 Z 21 -(In the food, Y 21 and Z 21 is as stated above) or -CY 21 =CZ 21 -(In the food, Y 21 and Z 21 It is preferable to use a device represented as (as stated above).

[0608] Y 21 As such, at least one type selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is preferred.

[0609] Z 21 As such, at least one type selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is preferred.

[0610] Or, Y 21 and Z 21The carbon atoms can be combined with each other to form a carbon ring or a heterocyclic ring that may include unsaturated bonds and may have aromatic properties. The number of carbon atoms in the ring is preferably 3 to 20.

[0611] Next, specific examples of compound (2) will be described. In addition, in the following examples, "analogous" refers to an acid anhydride obtained by substituting a part of the structure of the acid anhydride being exemplified with another structure to the extent that it does not deviate from the spirit of the present disclosure. Examples include dimers, trimers, and tetramers containing multiple acid anhydrides, or structurally different ones such as having branched chains even though the number of carbon atoms of the substituents is the same, or different sites where the substituents are bonded to the acid anhydride.

[0612] Specific examples of acid anhydrides forming a five-membered ring structure include succinic anhydride, methyl succinic anhydride (4-methyl succinic anhydride), dimethyl succinic anhydride (4,4-dimethyl succinic anhydride, 4,5-dimethyl succinic anhydride, etc.), 4,4,5-trimethyl succinic anhydride, 4,4,5,5-tetramethyl succinic anhydride, 4-vinyl succinic anhydride, 4,5-divinyl succinic anhydride, phenyl succinic anhydride (4-phenyl succinic anhydride), 4,5-diphenyl succinic anhydride, 4,4-diphenyl succinic anhydride, citraconic acid, maleic anhydride, methyl maleic anhydride (4-methyl maleic anhydride), 4,5-dimethyl maleic anhydride, and phenyl maleic acid. Examples include anhydrides (4-phenylmaleic anhydride), 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, 5,5-dimethylitaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, etc., and analogs thereof.

[0613] Specific examples of acid anhydrides forming a six-membered ring structure include cyclohexanedicarboxylic acid anhydride (cyclohexane-1,2-dicarboxylic acid anhydride, etc.), 4-cyclohexene-1,2-dicarboxylic acid anhydride, glutaric acid anhydride, glutaconic acid anhydride, 2-phenylglutaric acid anhydride, etc., and analogs thereof.

[0614] Specific examples of acid anhydrides forming other cyclic structures include 5-norbornene-2,3-dicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic acid anhydride, diglycolic acid anhydride, etc., and analogs thereof.

[0615] Specific examples of acid anhydrides substituted with halogen atoms that form a cyclic structure include monofluorosuccinic anhydride (4-fluorosuccinic anhydride, etc.), 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, etc., and analogs thereof.

[0616] As for the compound (2), among them, 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, tetrafluorosuccinic anhydride, etc. are preferred, and anhydrous Maleic acid, methyl maleic anhydride, trifluoromethyl maleic anhydride, succinic anhydride, methyl succinic anhydride, trifluoromethyl succinic anhydride, and tetrafluorosuccinic anhydride are more preferable, and maleic anhydride and succinic anhydride are even more preferable.

[0617] Compound (2) is the general formula (3):

[0618]

[0619] (during food, X 31 To X 34 is a compound (3) represented by a group that is the same or different and includes at least H, C, O or F, and a general formula (4):

[0620]

[0621] (during food, X 41 and X 42 It is preferable that it be at least one selected from the group consisting of compounds (4) represented by a group including at least H, C, O or F, which are the same or different.

[0622] X 31 To X 34 As for the group, at least one selected from the group consisting of alkyl groups, fluorinated alkyl groups, alkenyl groups, and fluorinated alkenyl groups is preferred, whether identical or different.

[0623] X 31 To X 34 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0624] X 31 To X 34 As such, at least one type selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2- is more preferable, being identical or different.

[0625] X 41 and X 42 As such, at least one selected from the group consisting of alkyl groups, fluorinated alkyl groups, alkenyl groups, and fluorinated alkenyl groups, which is the same or different, is preferred. X 41 and X 42 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0626] X 41 and X 42 As such, at least one type selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2- is more preferable, being identical or different.

[0627] It is preferable that the compound (3) be any of the following compounds.

[0628]

[0629] It is preferable that the compound (4) be any of the following compounds.

[0630]

[0631] It is preferable that the above liquid electrolyte contains 0.0001 to 15 mass% of compound (2) with respect to the above liquid electrolyte, in that the capacity retention rate is less likely to decrease and the amount of gas generated is less likely to increase even when stored at high temperatures. As for the content of compound (2), 0.01 to 10 mass% is more preferable, 0.1 to 3 mass% is more preferable, and 0.1 to 1.0 mass% is particularly preferable.

[0632] When the above liquid electrolyte contains both compounds (3) and (4), even when stored at high temperature, the capacity retention rate is less likely to decrease further and the amount of gas generated is less likely to increase further. Therefore, it is preferable that the above liquid electrolyte contains 0.08 to 2.50 mass% of compound (3) and 0.02 to 1.50 mass% of compound (4) with respect to the above liquid electrolyte, and it is more preferable that it contains 0.80 to 2.50 mass% of compound (3) and 0.08 to 1.50 mass% of compound (4).

[0633] The liquid electrolyte of the present disclosure may include at least one selected from the group consisting of nitrile compounds represented by the following general formulas (1a), (1b) and (1c).

[0634]

[0635] (during food, R a and R b Each represents, independently, a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a halogen atom. n represents an integer from 1 to 10.)

[0636]

[0637] (during food, R c is a hydrogen atom, a halogen atom, an alkyl group, a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, or, NC-R c1-X c1 -(R c1 alkylene group, X c1 It represents a group indicated by (representing an oxygen atom or a sulfur atom). R d and R e Each represents, independently, a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. m represents an integer from 1 to 10.)

[0638]

[0639] (during food, R f , R g , R h and R i Each represents, independently, a group containing a cyano group (CN), a hydrogen atom (H), a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a halogen atom. provided that R f , R g , R h and R i At least one of them is a group containing a cyano group. l represents an integer from 1 to 3.)

[0640] By doing so, the high-temperature preservation characteristics of the electrochemical device can be improved. The nitrile compound may be used alone, or two or more may be used in any combination and ratio.

[0641] 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 some of the hydrogen atoms of an alkyl group are substituted with a halogen atom.

[0642] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. Among these, fluorine atoms are preferred.

[0643] As for the alkyl group, it is preferable to have 1 to 5 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, etc.

[0644] As a group in which at least some hydrogen atoms of an alkyl group are substituted with halogen atoms, examples include a group in which at least some hydrogen atoms of the above-described alkyl group are substituted with the above-described halogen atoms. R a and R b If ga is an alkyl group, or a group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms, R a and R b They may combine with each other to form a ring structure (e.g., a cyclohexane ring).

[0645] R a and R b It is preferable that it be a hydrogen atom or an alkyl group.

[0646] In the above general formula (1a), n is an integer from 1 to 10. When n is 2 or greater, n R a They may all be identical, or at least some parts may be different. R b The same applies to . n is preferably an integer from 1 to 7, and more preferably an integer from 2 to 5.

[0647] As for the nitrile compound represented by the above general formula (1a), dinitrile and tricarbonitrile are preferred.

[0648] Specific examples of dinitrile include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, Bicyclohexyl-1,1-dicarbonitrile, Bicyclohexyl-2,2-dicarbonitrile, Bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl-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-dicyanopentan, Examples include 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononan, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3,3'-(ethylenedithio)dipropionitrile, 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, butanitrile, phthalonitrile, etc. Among these, particularly preferred are succinonitrile, glutaronitrile, and adiponitrile.

[0649] In addition, specific examples of tricarbonitrile include pentanetricarbonitrile, propanetricarbonitrile, 1,3,5-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, heptanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, cyclohexanetricarbonitrile, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, tris(2-cyanoethyl)amine, etc. Particularly preferred are 1,3,6-hexanetricarbonitrile and cyclohexanetricarbonitrile, and most preferred is cyclohexanetricarbonitrile.

[0650] In the above general formula (1b), R c is a hydrogen atom, a halogen atom, an alkyl group, a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, or, NC-R c1 -X c1 -(R c1 alkylene group, X c1 It is a group represented by (representing an oxygen atom or a sulfur atom), and R d and R e Each is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a halogen atom.

[0651] For the halogen atom, the alkyl group, and the group in which at least some of the hydrogen atoms of the alkyl group are substituted with the halogen atom, examples of the general formula (1a) above can be given.

[0652] The above NC-R c1 -X c1 R in - c1 It is an alkylene group. As for the alkylene group, an alkylene group having 1 to 3 carbon atoms is preferred.

[0653] R c , R d and R ePreferably, each independently is a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a halogen atom. R c , R d and R e At least one of is preferably a halogen atom, or a group in which at least some hydrogen atoms of an alkyl group are substituted with a halogen atom, and more preferably a fluorine atom, or a group in which at least some hydrogen atoms of an alkyl group are substituted with a fluorine atom. R d and R e If ga is an alkyl group, or a group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms, R d and R e They may combine with each other to form a ring structure (e.g., a cyclohexane ring).

[0654] In the above general formula (1b), m is an integer from 1 to 10. If m is 2 or greater, m R d They may all be identical, or at least some parts may be different. R e The same applies to m. m is preferably an integer from 2 to 7, and more preferably an integer from 2 to 5.

[0655] As nitrile compounds represented by the above general formula (1b), acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanitrile, 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, Examples include 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, pentafluoropropionitrile, methoxyacetonitrile, benzonitrile, etc. Among these, 3,3,3-trifluoropropionitrile is particularly preferred.

[0656] In the above general formula (1c), R f , R g , R h and R i Each 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 some of the hydrogen atoms of an alkyl group are substituted with a halogen atom.

[0657] As for the halogen atom, the alkyl group, and the group in which at least some of the hydrogen atoms of the alkyl group are substituted with the halogen atom, examples of the above general formula (1a) may be provided. As for the group containing the cyano group, in addition to the cyano group, examples of the group in which at least some of the hydrogen atoms of the alkyl group are substituted with the cyano group may be provided. As for the alkyl group in this case, examples of the above general formula (1a) may be provided.

[0658] R f , R g , R h and R i At least one of them is a group containing a cyano group. Preferably, Rf , R g , R h and R i At least two of them are groups containing cyano groups, and more preferably, R h and R i It is a group containing a cyano group. R h and R i If ga is a group containing a cyano group, R f and R g It is preferable that it be a hydrogen atom.

[0659] In the above general formula (1c), l is an integer from 1 to 3. If l is 2 or more, l R f They may all be identical, or at least some parts may be different. R g The same applies to l. l is preferably an integer between 1 and 2.

[0660] Examples of nitrile compounds represented by the above general formula (1c) include 3-hexendinitrile, mucononitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, 2-hexendinitrile, etc., and 3-hexendinitrile and mucononitrile are preferred, and 3-hexendinitrile is particularly preferred.

[0661] The content of the above nitrile compound is preferably 0.2 to 7 mass% with respect to the liquid electrolyte. This allows for further improvement in the high-temperature preservation characteristics and safety of the electrochemical device at high voltage. The lower limit of the total content of the above nitrile compound is more preferably 0.3 mass%, and even more preferably 0.5 mass%. The upper limit is more preferably 5 mass%, even more preferably 2 mass%, and particularly preferably 0.5 mass%.

[0662] The liquid electrolyte of the present disclosure may include a compound having an isocyanate group (hereinafter abbreviated as "isocyanate"). The isocyanate is not particularly limited and any isocyanate may be used. Examples of isocyanates include monoisocyanates, diisocyanates, triisocyanates, etc.

[0663] Specific examples of monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, isocyanatocyclohexane, methoxycarbonylisocyanate, ethoxycarbonylisocyanate, propoxycarbonylisocyanate, butoxycarbonylisocyanate, methoxysulfonylisocyanate, ethoxysulfonylisocyanate, propoxysulfonylisocyanate, butoxysulfonylisocyanate, fluorosulfonylisocyanate, methylisocyanate, butylisocyanate. Examples include phenyl isocyanate, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, ethyl isocyanate, etc.

[0664] 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-diisocyanatopropene, 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, and 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, Tolylene diisocyanate, 1,2-Bis(isocyanatomethyl)cyclohexane, 1,3-Bis(isocyanatomethyl)cyclohexane, 1,4-Bis(isocyanatomethyl)cyclohexane, 1,2-Diisocyanatocyclohexane, 1,3-Diisocyanatocyclohexane, 1,4-Diisocyanatocyclohexane, Dicyclohexylmethane-1,1'-Diisocyanate, Dicyclohexylmethane-2,2'-Diisocyanate, Examples include dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-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, etc.

[0665] Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylenediisocyanate, 1,3,5-triisocyanatemethylbenzene, 1,3,5-tris(6-isocyanatohexa-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4-(isocyanatomethyl)octamethylene-diisocyanate, etc.

[0666] Among them, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohexa-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,4,4-trimethylhexamethylenediisocyanato, and 2,2,4-trimethylhexamethylenediisocyanato are industrially readily available and are desirable in that they keep the manufacturing cost of the liquid electrolyte low, and also contribute to the formation of a stable film-like structure from a technical perspective, making them more suitable for use.

[0667] The content of isocyanate is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure, but is preferably 0.001 mass% or more and 1.0 mass% or less with respect to the liquid electrolyte. If the content of isocyanate is above this lower limit, it can bring about a sufficient effect of improving cycle characteristics in a non-aqueous liquid electrolyte secondary battery. In addition, if it is below this upper limit, an increase in the initial resistance of the non-aqueous liquid electrolyte secondary battery can be avoided. The content of isocyanate is more preferably 0.01 mass% or more, even more preferably 0.1 mass% or more, particularly preferably 0.2 mass% or more, and also more preferably 0.8 mass% or less, even more preferably 0.7 mass% or less, and particularly preferably 0.6 mass% or less.

[0668] The liquid electrolyte of the present disclosure may include a cyclic sulfonic acid ester. As for the cyclic sulfonic acid ester, any cyclic sulfonic acid ester may be used without particular limitation. Examples of cyclic sulfonic acid esters include saturated cyclic sulfonic acid esters, unsaturated cyclic sulfonic acid esters, saturated cyclic disulfonic acid esters, unsaturated cyclic disulfonic acid esters, etc.

[0669] Specific examples of saturated cyclic sulfonic acid esters include 1,3-propanesulfone, 1-fluoro-1,3-propanesulfone, 2-fluoro-1,3-propanesulfone, 3-fluoro-1,3-propanesulfone, 1-methyl-1,3-propanesulfone, 2-methyl-1,3-propanesulfone, 3-methyl-1,3-propanesulfone, 1,3-butanesulfone, 1,4-butanesulfone, 1-fluoro-1,4-butanesulfone, 2-fluoro-1,4-butanesulfone, 3-fluoro-1,4-butanesulfone, 4-fluoro-1,4-butanesulfone, 1-methyl-1,4-butanesulfone, 2-methyl-1,4-butanesulfone, 3-methyl-1,4-butanesulfone, 4-methyl-1,4-butanesulfone. Examples include 2,4-butan sultons.

[0670] Specific examples of unsaturated cyclic sulfonic acid esters include 1-propene-1,3-sulfone, 2-propene-1,3-sulfone, 1-fluoro-1-propene-1,3-sulfone, 2-fluoro-1-propene-1,3-sulfone, 3-fluoro-1-propene-1,3-sulfone, 1-fluoro-2-propene-1,3-sulfone, 2-fluoro-2-propene-1,3-sulfone, 3-fluoro-2-propene-1,3-sulfone, 1-methyl-1-propene-1,3-sulfone, 2-methyl-1-propene-1,3-sulfone, 3-methyl-1-propene-1,3-sulfone, 1-methyl-2-propene-1,3-sulfone, 2-methyl-2-propene-1,3-sulfone, 3-methyl-2-propene-1,3-sulfone, 1-butene-1,4-sulfone, 2-butene-1,4-sulfone, 3-butene-1,4-sulfone, 1-fluoro-1-butene-1,4-sulfone, 2-fluoro-1-butene-1,4-sulfone, 3-fluoro-1-butene-1,4-sulfone, 4-fluoro-1-butene-1,4-sulfone, 1-fluoro-2-butene-1,4-sulfone, 2-fluoro-2-butene-1,4-sulfone, 3-fluoro-2-butene-1,4-sulfone, 4-fluoro-2-butene-1,4-sulfone, 1,3-propenesulfone, 1-fluoro-3-butene-1,4-sulfone, 2-fluoro-3-butene-1,4-sulfone, Examples include 3-fluoro-3-butene-1,4-sulfone, 4-fluoro-3-butene-1,4-sulfone, 1-methyl-1-butene-1,4-sulfone, 2-methyl-1-butene-1,4-sulfone, 3-methyl-1-butene-1,4-sulfone, 4-methyl-1-butene-1,4-sulfone, 1-methyl-2-butene-1,4-sulfone, 2-methyl-2-butene-1,4-sulfone, 3-methyl-2-butene-1,4-sulfone, 4-methyl-2-butene-1,4-sulfone, 1-methyl-3-butene-1,4-sulfone, 2-methyl-3-butene-1,4-sulfone, 3-methyl-3-butene-1,4-sulfone, 4-methyl-3-butene-14-sulfone.

[0671] Among these, 1,3-propanesulfone, 1-fluoro-1,3-propanesulfone, 2-fluoro-1,3-propanesulfone, 3-fluoro-1,3-propanesulfone, and 1-propene-1,3-sulfone are more suitably used in that they contribute to ease of availability and the formation of a stable film-like structure. The content of the cyclic sulfonic acid ester is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure, but is preferably 0.001 mass% or more and 3.0 mass% or less with respect to the liquid electrolyte.

[0672] If the content of cyclic sulfonic acid ester is above this lower limit, it can bring about a sufficient effect of improving cycle characteristics in a non-aqueous liquid electrolyte secondary battery. In addition, if it is below this upper limit, an increase in the manufacturing cost of the non-aqueous liquid electrolyte secondary battery can be avoided. The content of cyclic sulfonic acid ester is more preferably 0.01 mass% or more, even more preferably 0.1 mass% or more, particularly preferably 0.2 mass% or more, and also more preferably 2.5 mass% or less, even more preferably 2.0 mass% or less, and particularly preferably 1.8 mass% or less.

[0673] The liquid electrolyte of the present disclosure may also contain polyethylene oxide having a weight average molecular weight of 2,000 to 40,000 and having -OH, -OCOOH, or -COOH at the terminals.

[0674] By including these compounds, the stability of the electrode interface can be improved, and the characteristics of the electrochemical device can be enhanced.

[0675] Examples of the above polyethylene oxide include polyethylene oxide monool, polyethylene oxide carboxylic acid, polyethylene oxide diol, polyethylene oxide dicarboxylic acid, polyethylene oxide triol, polyethylene oxide tricarboxylic acid, etc. These may be used alone or in combination of two or more types. Among these, a mixture of polyethylene oxide monool and polyethylene oxide diol, and a mixture of polyethylene carboxylic acid and polyethylene dicarboxylic acid are preferred in that the characteristics of the electrochemical device are improved.

[0676] If the weight-average molecular weight of the polyethylene oxide is too small, there is a risk that it will be prone to oxidative decomposition. The weight-average molecular weight is more preferably 3,000 to 40,000. The weight-average molecular weight can be measured by polystyrene conversion using gel permeation chromatography (GPC).

[0677] The content of the above polyethylene oxide is 1×10 in the liquid electrolyte. -6 Up to 1×10 -2 It is preferable that the amount be mol / kg. If the content of the polyethylene oxide is too high, there is a risk that it may impair the properties of the electrochemical device.

[0678] The content of the above polyethylene oxide is 5×10 -6 It is more desirable to have a mol / kg or higher.

[0679] The liquid electrolyte of the present disclosure may also contain, as an additive, a fluorinated saturated cyclic carbonate, an unsaturated cyclic carbonate, an overcharge prevention agent, other known auxiliary agents, etc. By doing so, the degradation of the characteristics of the electrochemical device can be suppressed.

[0680] Examples of fluorinated saturated cyclic carbonates include compounds represented by the general formula (A) described above. Among these, fluoroethylene carbonate, difluoroethylene carbonate, monofluoromethylethylene carbonate, trifluoromethylethylene carbonate, and 2,2,3,3,3-pentafluoropropylethylene carbonate (4-(2,2,3,3,3-pentafluoro-propyl)-[1,3]dioxolane-2-one) are preferred. One type of fluorinated saturated cyclic carbonate may be used alone, or two or more types may be used in any combination and ratio.

[0681] The content of the above-mentioned fluorinated saturated cyclic carbonate is preferably 0.001 to 10 mass% with respect to the liquid electrolyte, more preferably 0.01 to 5 mass%, and even more preferably 0.1 to 3 mass%.

[0682] Examples of unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates, etc.

[0683] Examples of 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, ethynylethylene carbonate, propargylethylene carbonate, methyl vinylene carbonate, dimethyl vinylene carbonate, etc.

[0684] Specific examples of ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond or a carbon-carbon triple bond include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene 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. Examples include 4-methylene-1,3-dioxolan-2-one, 4,5-dimethylene-1,3-dioxolan-2-one, 4-methyl-5-allylethylene carbonate, etc.

[0685] Among these, as unsaturated cyclic carbonates, 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, vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, and 4-vinyl-5-ethynylethylene carbonate are preferred. In addition, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate also form a stable interfacial protective film, so they are particularly desirable, and vinylene carbonate is the most desirable.

[0686] The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure. The molecular weight is preferably 50 or more and 250 or less. Within this range, it is easy to ensure the solubility of the unsaturated cyclic carbonate in a liquid electrolyte, and thus the effects of the present disclosure are easily expressed. The molecular weight of the unsaturated cyclic carbonate is more preferably 80 or more, and more preferably 150 or less.

[0687] The method for manufacturing unsaturated cyclic carbonates is not particularly limited, and it is possible to manufacture them by arbitrarily selecting a known method.

[0688] Unsaturated cyclic carbonates may be used as a single type, or two or more types may be used in any combination and ratio.

[0689] The content of the above unsaturated cyclic carbonate is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure. The content of the above unsaturated cyclic carbonate is preferably 0.001 mass% or more of 100 mass% of the liquid electrolyte, more preferably 0.01 mass% or more, and even more preferably 0.1 mass% or more. Furthermore, the content is preferably 5 mass% or less, more preferably 4 mass% or less, and even more preferably 3 mass% or less. Within the above range, the electrochemical device using the liquid electrolyte is likely to exhibit a sufficient effect of improving cycle characteristics, and it is also easy to avoid situations such as deterioration of high-temperature retention characteristics, increased gas generation, and reduced discharge capacity retention rate.

[0690] As for unsaturated cyclic carbonates, in addition to the non-fluorinated unsaturated cyclic carbonates described above, fluorinated unsaturated cyclic carbonates can also be suitably used.

[0691] Fluorinated unsaturated cyclic carbonates are cyclic carbonates having unsaturated bonds and fluorine atoms. The number of fluorine atoms in the fluorinated unsaturated cyclic carbonates is not particularly limited as long as it is one or more. Among these, the number of fluorine atoms is typically six or fewer, preferably four or fewer, and one or two is most preferable.

[0692] Examples of fluorinated unsaturated cyclic carbonates include fluorinated vinylene carbonate derivatives, fluorinated ethylene carbonate derivatives substituted with aromatic rings or substituents having carbon-carbon double bonds.

[0693] Examples of fluorinated vinylene carbonate derivatives include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, etc.

[0694] Fluorinated ethylene carbonate derivatives substituted with an aromatic ring or a substituent having 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-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, Examples include 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, etc.

[0695] Among them, as fluorinated unsaturated cyclic carbonates, 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 suitable for use because they form a stable interfacial protective film.

[0696] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure. The molecular weight is preferably 50 or more, and also 500 or less. Within this range, it is easy to ensure the solubility of the fluorinated unsaturated cyclic carbonate in a liquid electrolyte.

[0697] The method for manufacturing the fluorinated unsaturated cyclic carbonate is not particularly limited, and it is possible to manufacture it by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

[0698] Fluorinated unsaturated cyclic carbonates may be used alone or two or more may be used in any combination and ratio. Furthermore, the content of fluorinated unsaturated cyclic carbonates is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure. The content of fluorinated unsaturated cyclic carbonates is typically 0.001 mass% or more, more preferably 0.01 mass% or more, and even more preferably 0.1 mass% or more, in 100 mass% of the liquid electrolyte; additionally, it is preferably 5 mass% or less, more preferably 4 mass% or less, and even more preferably 3 mass% or less. Within this range, the electrochemical device using the liquid electrolyte is likely to exhibit a sufficient effect of improving cycle characteristics, and it is also easy to avoid situations such as a decrease in high-temperature retention characteristics, an increase in gas generation, and a decrease in the discharge capacity retention rate.

[0699] The liquid electrolyte of the present disclosure may include a compound having a triple bond. As long as the compound has one or more triple bonds within its molecule, the type thereof is not particularly limited.

[0700] Specific examples of compounds having a triple bond include, for instance, the following compounds.

[0701] 1-pentene, 2-pentene, 1-hexine, 2-hexine, 3-hexine, 1-heptine, 2-heptine, 3-heptine, 1-octine, 2-octine, 3-octine, 4-octine, 1-nonine, 2-nonine, 3-nonine, 4-nonine, 1-dodecin, 2-dodecin, 3-dodecin, 4-dodecin, 5-dodecin, phenylacetylene, 1-phenyl-1-propine, 1-phenyl-2-propine, 1-phenyl-1-butine, 4-phenyl-1-butine, 4-phenyl-1-butine, 1-phenyl-1-pentene, 5-phenyl-1-pentene, 1-phenyl-1-hexine, 6-phenyl-1-hexine, diphenylacetylene, 4-ethynyltoluene, Hydrocarbon compounds such as dicyclohexylacetylene;

[0702] Monocarbonates such as 2-propynylmethylcarbonate, 2-propynylethylcarbonate, 2-propynylpropylcarbonate, 2-propynylbutylcarbonate, 2-propynylphenylcarbonate, 2-propynylcyclohexylcarbonate, di-2-propynylcarbonate, 1-methyl-2-propynylmethylcarbonate, 1,1-dimethyl-2-propynylmethylcarbonate, 2-butynylmethylcarbonate, 3-butynylmethylcarbonate, 2-pentinylmethylcarbonate, 3-pentinylmethylcarbonate, 4-pentinylmethylcarbonate; Dicarbonates such as 2-butin-1,4-diol dimethyl dicarbonate, 2-butin-1,4-diol diethyl dicarbonate, 2-butin-1,4-diol dipropyl dicarbonate, 2-butin-1,4-diol dibutyl dicarbonate, 2-butin-1,4-diol diphenyl dicarbonate, 2-butin-1,4-diol dicyclohexyl dicarbonate;

[0703] 2-propynyl acetate, 2-propynyl propionic acid, 2-propynyl butyric acid, 2-propynyl benzoic acid, 2-propynyl cyclohexylcarboxylic acid, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-propynyl propionic acid, 1,1-dimethyl-2-propynyl butyric acid, 1,1-dimethyl-2-propynyl benzoic acid, 1,1-dimethyl-2-propynyl cyclohexylcarboxylic acid, 2-butynyl acetate, 3-butynyl acetate, 2-fenthynyl acetate, 3-fenthynyl acetate, 4-fenthynyl acetate, methyl acrylate, ethyl acrylate, propyl acrylate, vinyl acrylate, 2-propenyl acrylic acid, 2-butenyl acrylic acid, 3-butenyl acrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, Vinyl methacrylate, 2-propene methacrylate, 2-butenyl methacrylate, 3-butenyl methacrylate, methyl 2-propanate, ethyl 2-propanate, propyl 2-propanate, 2-vinyl methacrylate, 2-propene 2-propanate, 2-butenyl 2-propanate, 3-butenyl 2-propanate, methyl 2-butylate, ethyl 2-butylate, propyl 2-butylate, 2-vinyl 2-butylate, 2-propene 2-butylate, 2-butenyl 2-butylate, 3-butenyl 2-butylate, methyl 3-butylate, ethyl 3-butylate, propyl 3-butylate, 3-vinyl methacrylate, 2-propene 3-butylate, 2-butenyl 2-butylate, 3-butenyl 3-butylate, Monocarboxylic acid esters such as 2-methyl pentate, 2-ethyl pentate, 2-propyl pentate, 2-vinyl pentate, 2-propenyl pentate, 2-butenyl pentate, 2-3-butenyl pentate, 3-methyl pentate, 3-ethyl pentate, 3-propyl pentate, 3-vinyl pentate, 3-propenyl pentate, 3-butenyl pentate, 3-3-butenyl pentate, 4-methyl pentate, 4-ethyl pentate, 4-propyl pentate, 4-vinyl pentate, 4-propenyl pentate, 4-butenyl pentate, 4-butenyl pentate, 4-butenyl pentate, fumaric acid esters, methyl trimethylacetate, ethyl trimethylacetate;

[0704] Dicarboxylic acid esters such as 2-butin-1,4-diol diacetate, 2-butin-1,4-diol dipropionate, 2-butin-1,4-diol dibutyrate, 2-butin-1,4-diol dibenzoate, 2-butin-1,4-diol dicyclohexanecarboxylate, hexahydrobenzo[1,3,2]dioxathiolan-2-oxide(1,2-cyclohexanediol, 2,2-dioxide-1,2-oxathiolan-4-ylacetate, 2,2-dioxide-1,2-oxathiolan-4-ylacetate;

[0705] Oxalic acid diesters such as methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, propyl 2-propynyl oxalate, 2-propynylvinyl oxalate, allyl 2-propynyl oxalate, di-2-propynyl oxalate, 2-butynylmethyl oxalate, 2-butynylethyl oxalate, 2-butynylpropyl oxalate, 2-butynylvinyl oxalate, allyl 2-butynyl oxalate, di-2-butynyl oxalate, 3-butynylmethyl oxalate, 3-butynylethyl oxalate, 3-butynylpropyl oxalate, 3-butynylvinyl oxalate, allyl 3-butynyl oxalate, di-3-butynyl oxalate, etc.;

[0706] 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-propynyl)(2-propenyl)phosphine oxide, di(3-butenyl)(2-propynyl)phosphine oxide, and di(2-propynyl)(3-butenyl)phosphine oxide;

[0707] 2-propynyl methyl(2-propenyl)phosphinic acid, 2-propynyl 2-butenyl(methyl)phosphinic acid, 2-propynyl di(2-propenyl)phosphinic acid, 2-propynyl di(3-butenyl)phosphinic acid, 1,1-dimethyl-2-propynyl methyl(2-propenyl)phosphinic acid, 1,1-dimethyl-2-propynyl 2-butenyl(methyl)phosphinic acid, 1,1-dimethyl-2-propynyl di(2-propenyl)phosphinic acid, and 1,1-dimethyl-2-propynyl di(3-butenyl)phosphinic acid, 2-propenyl methyl(2-propynyl)phosphinic acid, 3-butenyl methyl(2-propynyl)phosphinic acid, 2-propenyl di(2-propynyl)phosphinic acid, 3-butenyl di(2-propynyl)phosphinic acid, Phosphic acid esters such as 2-propynyl(2-propenyl)phosphinic acid 2-propenyl, and 2-propynyl(2-propenyl)phosphinic acid 3-butenyl;

[0708] 2-methyl 2-propynyl propenyl phosphonic acid, 2-methyl (2-propynyl) butenylphosphonic acid, 2-propenyl phosphonic acid (2-propynyl)(2-propenyl), 3-butenylphosphonic acid (3-butenyl)(2-propynyl), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl)(methyl), 2-butenylphosphonic acid (1,1-dimethyl-2-propynyl)(methyl), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), and 3-butenylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl), methylphosphonic acid (2-propynyl)(2-propenyl), methylphosphonic acid (3-butenyl)(2-propynyl), Phosphonic acid esters such as methylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), methylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl), ethylphosphonic acid (2-propynyl)(2-propenyl), ethylphosphonic acid (3-butenyl)(2-propynyl), ethylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), and ethylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl);

[0709] Phosphate esters such as phosphate (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), and phosphate (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl).

[0710] Among these, compounds having alkynyloxy groups are preferred because they form a negative electrode film more stably in a liquid electrolyte.

[0711] In addition, compounds such as 2-propynylmethylcarbonate, di-2-propynylcarbonate, 2-butyne-1,4-diol dimethyl dicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, methyl 2-propynyl oxalate, and di-2-propynyl oxalate are particularly desirable for improving preservation properties.

[0712] The compound having the triple bond described above may be used alone, or two or more may be used in any combination and ratio. There is no limitation on the amount of the compound having the triple bond to be incorporated into the entire liquid electrolyte of the present disclosure, and as long as the effects of the present disclosure are not significantly impaired, it is optional but is contained in the liquid electrolyte of the present disclosure at a concentration of typically 0.01 mass% or more, preferably 0.05 mass% or more, more preferably 0.1 mass% or more, and typically 5 mass% or less, preferably 3 mass% or less, more preferably 1 mass% or less. When the above range is satisfied, the effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature retention characteristics are further improved.

[0713] In the liquid electrolyte of the present disclosure, an overcharge prevention agent may be used to effectively suppress the rupture or ignition of the battery when an electrochemical device using the liquid electrolyte becomes overcharged or otherwise.

[0714] As an overcharge inhibitor, an aromatic compound such as biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, an alkyl-substituted or terphenyl derivative, a partial hydride of an unsubstituted or alkyl-substituted terphenyl derivative, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, cyclopentylbenzene, cyclohexylbenzene, cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, t-butylbenzene, t-amylbenzene, t-hexylbenzene, anisole, etc. Partially fluorinated compounds of the above aromatic compounds, such as 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene-fluorobenzene, fluorotoluene, and benzotrifluoride; fluorine-containing 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-propylphenylacetate, 2-ethylphenylacetate, benzylphenylacetate, methylphenylacetate, benzylacetate, and phenethylphenylacetate; Examples include aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate, toluene derivatives such as toluene and xylene, and unsubstituted or alkyl-substituted biphenyl derivatives such as 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and o-cyclohexylbiphenyl. Among these, biphenyl, alkylbiphenyl, terphenyl, a partially hydrogenated terphenyl, aromatic compounds such as cyclohexylbenzene, t-butylbenzene, t-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, and methylphenyl carbonate are preferred. One of these may be used alone, or two or more may be used in combination.In the case of using two or more types in combination, it is particularly desirable to use at least one selected from oxygen-free aromatic compounds such as a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, a partial hydrogenated form of terphenyl, cyclohexylbenzene, t-butylbenzene, and t-amylbenzene, and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran in combination, in terms of the balance between overcharge prevention properties and high-temperature storage properties.

[0715] The liquid electrolyte used in the battery of the present disclosure may be a carboxylic acid anhydride (except for compound (2)). A compound represented by the following general formula (6) is preferred. The method of manufacturing the carboxylic acid anhydride is not particularly limited, and it is possible to manufacture it by arbitrarily selecting a known method.

[0716]

[0717] (of general formula (6), R 61 , R 62 Each represents, independently, a hydrocarbon group having 1 to 15 carbon atoms that may have substituents.

[0718] R 61 , R 62 As long as it is a monovalent hydrocarbon group, its type is not particularly limited. For example, it may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or may contain unsaturated bonds (carbon-carbon double bonds or carbon-carbon triple bonds). Furthermore, the aliphatic hydrocarbon group may be chain-like or cyclic; in the case of a chain, it may be a straight chain or a branched chain. Furthermore, it may be a combination of a chain and a cyclic group. Also, R 61 and R 62 They may be the same or different.

[0719] Also, R 61 , R 62 When the hydrocarbon group of has a substituent, the type of substituent is not particularly limited unless it is contrary to the spirit of the present disclosure, but examples include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, and preferably fluorine atoms. Alternatively, as substituents other than halogen atoms, substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups may be examples, and preferably cyano groups and carbonyl groups. R 61 , R 62 The hydrocarbon group of may have only one of these substituents or two or more. If it has two or more substituents, these substituents may be the same or different from each other.

[0720] R 61 , R 62 The number of carbon atoms in each hydrocarbon group is typically 1 or more, and is also typically 15 or less, preferably 12 or less, more preferably 10 or less, and even more preferably 9 or less. R 1 and R 2 In cases where they combine to form a divalent hydrocarbon group, the number of carbon atoms in the divalent hydrocarbon group is typically 1 or more, and is also typically 15 or less, preferably 13 or less, more preferably 10 or less, and even more preferably 8 or less. In addition, R 61 , R 62 In the case where the hydrocarbon group of has a substituent containing a carbon atom, R including that substituent 61 , R 62 It is desirable that the total number of carbon atoms satisfies the above range.

[0721] Next, specific examples of acid anhydrides represented by the general formula (6) above will be described. In addition, in the following examples, "analogous" refers to an acid anhydride obtained by substituting a part of the structure of the acid anhydride being exemplified with a different structure to the extent that it does not deviate from the spirit of the present disclosure. Examples include dimers, trimers, and tetramers containing multiple acid anhydrides, or structurally different ones having branched chains, even though the number of carbon atoms of the substituents is the same, or different sites where the substituents bind to the acid anhydride.

[0722] First, R 61 , R 62 Specific examples of the same acid anhydride are given below.

[0723] R 61 , R 62 Specific examples of acid anhydrides having a chain-like alkyl group include acetic anhydride, propionic anhydride, butanoic anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2,2-dimethylbutanoic anhydride, 2,3-dimethylbutanoic anhydride, 3,3-dimethylbutanoic anhydride, 2,2,3-trimethylbutanoic anhydride, 2,3,3-trimethylbutanoic anhydride, 2,2,3,3-tetramethylbutanoic anhydride, 2-ethylbutanoic anhydride, etc., and analogs thereof.

[0724] R 61 , R 62 Specific examples of acid anhydrides in which g is a cyclic alkyl group include cyclopropanecarboxylic acid anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, etc., and analogs thereof.

[0725] R 61 , R 62Specific examples of acid anhydrides in which g is an alkenyl group include acrylic acid anhydride, 2-methylacrylic acid anhydride, 3-methylacrylic acid anhydride, 2,3-dimethylacrylic acid anhydride, 3,3-dimethylacrylic acid anhydride, 2,3,3-trimethylacrylic acid anhydride, 2-phenylacrylic acid anhydride, 3-phenylacrylic acid anhydride, 2,3-diphenylacrylic acid anhydride, 3,3-diphenylacrylic acid anhydride, 3-butene acid anhydride, 2-methyl-3-butene acid anhydride, 2,2-dimethyl-3-butene acid anhydride, 3-methyl-3-butene acid anhydride, 2-methyl-3-methyl-3-butene acid anhydride, 2,2-dimethyl-3-methyl-3-butene acid anhydride, and 3-pentene acid. Examples include anhydrides, 4-pentene anhydrides, 2-cyclopentene carboxylic acid anhydrides, 3-cyclopentene carboxylic acid anhydrides, 4-cyclopentene carboxylic acid anhydrides, etc., and analogs thereof.

[0726] R 61 , R 62 Specific examples of acid anhydrides in which the alkynyl group is propinic anhydride, 3-phenylpropinic anhydride, 2-butyric anhydride, 2-pentyric anhydride, 3-butyric anhydride, 3-pentyric anhydride, 4-pentyric anhydride, etc., and analogs thereof may be cited.

[0727] R 61 , R 62 Specific examples of acid anhydrides that are aryl groups 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, etc., and analogs thereof.

[0728] Also, R 61 , R 62 Examples of acid anhydrides substituted with halogen atoms are provided below, but acid anhydrides obtained by substituting some or all of these fluorine atoms with chlorine atoms, bromine atoms, or iodine atoms are also included in the example compounds.

[0729] R 61 , R 62 Examples of acid anhydrides that are chain alkyl groups substituted with halogen atoms 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, etc., and analogs thereof.

[0730] R 61 , R 62 Examples of acid anhydrides that are cyclic alkyl groups substituted with halogen atoms include 2-fluorocyclopentanecarboxylic acid anhydride, 3-fluorocyclopentanecarboxylic acid anhydride, 4-fluorocyclopentanecarboxylic acid anhydride, etc., and analogs thereof.

[0731] R 61 , R 62Examples of acid anhydrides in which the alkenyl group is 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-tris(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, Examples include 2-fluoro-3-butene anhydride, 2,2-difluoro-3-butene anhydride, 3-fluoro-2-butene anhydride, 4-fluoro-3-butene anhydride, 3,4-difluoro-3-butene anhydride, 3,3,4-trifluoro-3-butene anhydride, etc., and analogs thereof.

[0732] R 61 , R 62 Examples of acid anhydrides that are alkynyl groups substituted with halogen atoms include 3-fluoro-2-propinic anhydride, 3-(4-fluorophenyl)-2-propinic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propinic anhydride, 4-fluoro-2-butyric anhydride, 4,4-difluoro-2-butyric anhydride, 4,4,4-trifluoro-2-butyric anhydride, etc., and analogs thereof.

[0733] R 61 , R 62 Examples of acid anhydrides in which the aryl group is substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, etc., and analogs thereof.

[0734] R 61 , R 62Examples of acid anhydrides having substituents having functional groups such as esters, nitriles, ketones, and ethers include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutanoic anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, etc., and analogs thereof.

[0735] Continuing, R 61 , R 62 Specific examples of different acid anhydrides are given below.

[0736] R 61 , R 62 As such, all combinations of the examples listed above and their analogues can be considered, and representative examples are given below.

[0737] Examples of combinations of chain alkyl groups include acetic acid propionic anhydride, acetic acid butocarbonate anhydride, butocarbonate propionic anhydride, acetic acid 2-methylpropionic anhydride, etc.

[0738] Examples of combinations of chain alkyl groups and cyclic alkyl groups include cyclopentanoic acid anhydride, cyclohexanoic acid anhydride, cyclopentanoic acid propionic acid anhydride, etc.

[0739] Examples of combinations of chain alkyl groups and alkenyl groups include acrylic anhydride, 3-methylacrylic anhydride, 3-butene anhydride, propionic anhydride, etc.

[0740] Examples of combinations of chain alkyl groups and alkynyl groups include acetic acid propic anhydride, acetic acid 2-butyric acid anhydride, acetic acid 3-butyric acid anhydride, acetic acid 3-phenylpropic acid anhydride, propionic acid propic acid anhydride, etc.

[0741] Examples of combinations of chain alkyl groups and aryl groups include benzoic anhydride, 4-methylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, propionic anhydride, etc.

[0742] Examples of combinations of chain-type alkyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride, trifluoroacetic anhydride, 4-fluorobenzoic anhydride, propionic fluoroacetic anhydride, alkyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, methoxyacetic anhydride, propionic methoxyacetic anhydride, etc.

[0743] Examples of combinations of cyclic alkyl groups include cyclopentanoic acid, cyclohexanoic acid anhydride, etc.

[0744] Examples of combinations of cyclic alkyl groups and alkenyl groups include cyclopentanoic acid anhydride, 3-methylacrylate cyclopentanoic acid anhydride, 3-buteneate cyclopentanoic acid anhydride, cyclohexanoic acid anhydride, etc.

[0745] Examples of combinations of cyclic alkyl groups and alkynyl groups include cyclopentanoic anhydride propinate, cyclopentanoic anhydride 2-butyrate, cyclohexanoic anhydride propinate, etc.

[0746] Examples of combinations of cyclic alkyl groups and aryl groups include cyclopentanoic anhydride benzoate, 4-methylbenzoate cyclopentanoic anhydride, cyclohexanoic anhydride benzoate, etc.

[0747] Examples of combinations of hydrocarbon groups having cyclic alkyl groups and functional groups include cycloacetic acid cyclopentanoic anhydride, cyclopentanoic acid trifluoroacetic anhydride, cyclopentanoic acid 2-cyanoacetic anhydride, cyclopentanoic acid methoxyacetic anhydride, cyclohexanoic acid fluoroacetic anhydride, etc.

[0748] Examples of combinations of alkenyl groups include 2-methylacrylic anhydride, 3-methylacrylic anhydride, 3-butene anhydride, 2-methylacrylic anhydride, and others.

[0749] Examples of combinations of alkenyl and alkynyl groups include acrylic acid propinic anhydride, 2-butyric acid anhydride, 2-methylacrylic acid propinic anhydride, etc.

[0750] Examples of combinations of alkenyl and aryl groups include benzoic acid anhydride, 4-methylbenzoic acid anhydride, 2-methylacrylic acid benzoic acid anhydride, etc.

[0751] Examples of combinations of alkenyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride of acrylic acid, trifluoroacetic anhydride of acrylic acid, 2-cyanoacetic anhydride of acrylic acid, methoxyacetic anhydride of acrylic acid, 2-methylacrylic acid fluoroacetic anhydride, etc.

[0752] Examples of combinations of alkynyl groups include 2-butyric anhydride, 3-butyric anhydride, 2-butyric anhydride, etc.

[0753] Examples of combinations of alkynyl and aryl groups include propinic anhydride of benzoate, 4-methylbenzoate propinic anhydride, 2-butyric anhydride of benzoate, etc.

[0754] Examples of combinations of alkynyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride of propinate, trifluoroacetic anhydride of propinate, 2-cyanoacetic anhydride of propinate, methoxyacetic anhydride of propinate, 2-fluoroacetic anhydride of butyrate, etc.

[0755] Examples of combinations of aryl groups include 4-methylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, 4-methylbenzoic anhydride, and others.

[0756] Examples of combinations of hydrocarbon groups having aryl groups and functional groups include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, 4-methylbenzoic acid fluoroacetic anhydride, etc.

[0757] Examples of combinations of hydrocarbon groups having functional groups include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, trifluoroacetic acid 2-cyanoacetic anhydride, etc.

[0758] Among the acid anhydrides forming the above chain structure, preferably, acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, etc., acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 3-butenetic anhydride, 2-methyl-3-butenetic anhydride, propinic anhydride, 2-butenetic 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, and more preferably, acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic 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.

[0759] These compounds are desirable in that they can improve charge / discharge rate characteristics, input / output characteristics, and impedance characteristics, particularly after a durability test, by forming a durable film by appropriately forming a bond with lithium oxalate salt.

[0760] In addition, there is no limitation on the molecular weight of the above-mentioned carboxylic acid anhydride, and it is optional as long as it does not significantly impair the effects of the present disclosure, but is typically 90 or more, preferably 95 or more, while typically 300 or less, preferably 200 or less. If the molecular weight of the carboxylic acid anhydride is within the above range, the increase in viscosity of the liquid electrolyte can be suppressed, and durability can be appropriately improved because the film density is optimized.

[0761] In addition, there are no particular restrictions on the method of manufacturing the above-described carboxylic acid anhydride, and it is possible to manufacture it by arbitrarily selecting a known method. The carboxylic acid anhydride described above may be contained as a single type in the non-aqueous liquid electrolyte of the present disclosure, or two or more types may be contained in any combination and ratio.

[0762] In addition, there are no particular limitations on the content of the carboxylic acid anhydride in the liquid electrolyte of the present disclosure, and it is optional as long as it does not significantly impair the effects of the present disclosure; however, it is preferable to include it in the liquid electrolyte of the present disclosure at a concentration of typically 0.01 mass% or more, preferably 0.1 mass% or more, and typically 5 mass% or less, preferably 3 mass% or less. When the content of the carboxylic acid anhydride is within the above range, the effect of improving cycle characteristics becomes easier to manifest, and since the reactivity is suitable, the battery characteristics become easier to improve.

[0763] Other known auxiliary agents may be used in the liquid electrolyte of the present disclosure. As other auxiliary agents, hydrocarbon compounds such as pentane, heptane, octane, nonane, decane, cycloheptane, benzene, furan, naphthalene, 2-phenylbicyclohexyl, cyclohexane, 2,4,8,10-tetraoxaspiro[5.5]undecane, and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane;

[0764] Fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride, monofluorobenzene, 1-fluoro-2-cyclohexylbenzene, 1-fluoro-4-tert-butylbenzene, 1-fluoro-3-cyclohexylbenzene, 1-fluoro-2-cyclohexylbenzene, and fluorinated biphenyls;

[0765] Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate, etc.;

[0766] Ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxapentadecane, ethoxymethoxyethane, trimethoxymethane, glyme, ethyl monoglyme, etc.

[0767] Ketone compounds such as dimethyl ketone, diethyl ketone, and 3-pentanone;

[0768] Acid anhydrides such as 2-allyl anhydride and succinic acid;

[0769] Ester compounds such as dimethyl oxalate, diethyl oxalate, ethylmethyl 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-diyldiformate, 2-propynyl methacrylate, dimethyl malonicate, etc.

[0770] Amid compounds such as acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide;

[0771] Ethylene sulfate, vinylene sulfate, ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulpan, sulfonen, diphenylsulfone, N,N-dimethylmethanesulfonamide, N,N-diethylmethanesulfonamide, methyl vinylsulfonate, ethyl vinylsulfonate, allyl vinylsulfonate, propargyl vinylsulfonate, methyl allylsulfonate, ethyl allylsulfonate, allyl allylsulfonate, propargyl allylsulfonate, 1,2-bis(vinylsulfonyloxy)ethane, propanedisulfonic acid anhydride, sulfobutyric acid anhydride, sulfobenzoic acid anhydride, sulfopropionic acid anhydride, ethanedisulfonic acid anhydride, methylenemethanedisulfonate, 2-propynyl methanesulfonate, pentenesulfite, pentafluorophenylmethanesulfonate, propylene sulfate, Propylene sulfite, propane sulfone, butylene sulfite, butane-2,3-diyl dimethanesulfonate, 2-butyne-1,4-diyl dimethanesulfonate, vinylsulfonic acid 2-propynyl, bis(2-vinylsulfonylethyl)ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiol-2-oxide, 2-(methanesulfonyloxy)propionic acid 2-propynyl, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxide, 3-sulfo-propionic anhydride trimethylenemethanedisulfonate 2-methyltetrahydrofuran, trimethylenemethanedisulfonate, tetramethylene sulfoxide, dimethylenemethanedisulfonate, difluoroethylmethylsulfone, divinylsulfone, 1,2-bis(vinylsulfonyl)ethane, Sulfur-containing compounds such as methyl ethylenebissulfonate, ethyl ethylenebissulfonate, ethylenesulfate, thiophene 1-oxide, etc.;

[0772] Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide, nitromethane, nitroethane, ethylenediamine, etc.;

[0773] Trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl phosphonic acid, diethyl phosphonic acid, dimethyl vinylphosphonic acid, diethyl vinylphosphonic acid, diethyl phosphonoacetate, 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, 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, Tris(2,2,2-trifluoroethyl) phosphate, tris(1,1,1,3,3,3-hexafluoropropane-2-yl) phosphate, trioctyl phosphate, 2-phenylphenyldimethyl phosphate, 2-phenylphenyldiethyl phosphate, phosphate (2,2,2-trifluoroethyl)(2,2,3,3-tetrafluoropropyl)methyl, methyl 2-(dimethoxyphosphoryl)acetate, methyl 2-(dimethylphosphoryl)acetate, methyl 2-(diethoxyphosphoryl)acetate, methyl 2-(diethylphosphoryl)acetate, methyl methylenebisphosphonate, ethyl methylenebisphosphonate, methyl ethylenebisphosphonate, ethyl ethylenebisphosphonate, methyl butylenebisphosphonate, ethyl butylenebisphosphonate, 2-propynyl 2-(dimethoxyphosphoryl) acetate, 2-propynyl 2-(dimethylphosphoryl) acetate, Phosphorus-containing compounds such as 2-propynyl 2-(diethoxyphosphoryl) acetate, 2-propynyl 2-(diethylphosphoryl) acetate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, tris(trimethoxysilyl) polyphosphate, and trimethylsilyl polyphosphate;

[0774] Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate;

[0775] Silane compounds such as dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytrimethoxysilane, titanium tetrakis(trimethylsiloxide), titanium tetrakis(triethylsiloxide), tetramethylsilane, etc.;

[0776] Examples include the above. These may be used individually or in combination of two or more types. By adding these auxiliary agents, capacity retention characteristics or cycle characteristics after high-temperature storage can be improved. Among the above other auxiliary agents, phosphorus-containing compounds are preferred, and tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphoric acid are preferred.

[0777] The amount of other auxiliary agents is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure. The amount of other auxiliary agents is preferably 0.01 mass% or more and 5 mass% or less in 100 mass% of the liquid electrolyte. Within this range, it is easy to fully express the effects of the other auxiliary agents and easy to avoid situations where the characteristics of the battery, such as high-load discharge characteristics, are degraded. The amount of other auxiliary agents is more preferably 0.1 mass% or more, even more preferably 0.2 mass% or more, and even more preferably 3 mass% or less, and even more preferably 1 mass% or less.

[0778] The liquid electrolyte used in the battery of the present disclosure may further contain, to the extent that it does not impair the effects of the present disclosure, cyclic and chain carboxylic acid esters, ether compounds, nitrogen-containing compounds, boron-containing compounds, organosilicon-containing compounds, non-flammable (flame retardant) agents, surfactants, high-performance additives, cycle and rate characteristic improvers, sulfone compounds, etc. as additives.

[0779] Examples of the above-mentioned cyclic carboxylic acid esters include those having a total number of carbon atoms in their structural formulas ranging from 3 to 12. Specifically, examples include gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, epsilon-caprolactone, 3-methyl-γ-butyrolactone, etc. Among these, gamma-butyrolactone is particularly preferred in terms of improving the characteristics of electrochemical devices derived from the enhancement of the degree of lithium ion dissociation.

[0780] The amount of cyclic carboxylic acid ester incorporated as an additive is typically 0.1 mass% or more, more preferably 1 mass% or more, in 100 mass% of the solvent. Within this range, it becomes easier to improve the electrical conductivity of the liquid electrolyte and enhance the high-current discharge characteristics of the electrochemical device. Additionally, the amount of cyclic carboxylic acid ester incorporated is preferably 10 mass% or less, more preferably 5 mass% or less. By setting an upper limit in this way, the viscosity of the liquid electrolyte is kept within an appropriate range, thereby avoiding a decrease in electrical conductivity, suppressing an increase in negative electrode resistance, and making it easier to achieve high-current discharge characteristics of the electrochemical device within a good range.

[0781] In addition, as the above cyclic carboxylic acid ester, a fluorinated cyclic carboxylic acid ester (fluorine-containing lactone) may also be suitably used. As for the fluorine-containing lactone, for example, the following formula (C):

[0782]

[0783] (during food, X 15 To X 20 are identical or different, all -H, -F, -Cl, -CH3 or fluorinated alkyl groups; provided that X 15 To X 20 At least one of them is a fluorinated alkyl group)

[0784] Examples include fluorine-containing lactones represented by .

[0785] X 15 To X 20Examples of fluorinated alkyl groups include -CFH2, -CF2H, -CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, -CF(CF3)2, etc., and -CH2CF3 and -CH2CF2CF3 are preferred in that they have high oxidation resistance and an effect of improving safety.

[0786] X 15 To X 20 If at least one of is a fluorinated alkyl group, -H, -F, -Cl, -CH3 or the fluorinated alkyl group is X 15 To X 20 It may be substituted at only one location or at multiple locations. Preferably, it is at 1 to 3 locations, more preferably at 1 to 2 locations, where the solubility of the electrolyte salt is good.

[0787] Although the substitution position of the fluorinated alkyl group is not particularly limited, X in terms of good synthesis yield 17 and / or X 18 This, especially X 17 or X 18 This fluorinated alkyl group, in particular -CH2CF3 and -CH2CF2CF3, is preferred. X other than the fluorinated alkyl group 15 To X 20 It is -H, -F, -Cl, or CH3, and -H is preferred in particular because of its good solubility in electrolyte salts.

[0788] As for fluorine-containing lactones, in addition to those represented by the above formula, for example, the following formula (D):

[0789]

[0790] (In the formula, either A or B is CX 226 X 227 (X 226 and X 227is identical or different, all are -H, -F, -Cl, -CF3, -CH3 or alkylene groups where a hydrogen atom may be substituted with a halogen atom or contain heteroatoms in the chain), and the other is an oxygen atom; Rf 12 is a fluorinated alkyl group or fluorinated alkoxy group that may have an ether bond; X 221 and X 222 is the same or different, all -H, -F, -Cl, -CF3 or CH3; X 223 To X 225 Examples include alkyl groups that are identical or different, and in which -H, -F, -Cl or hydrogen atoms may be substituted with halogen atoms or contain heteroatoms in the chain; and fluorine-containing lactones represented by n=0 or 1).

[0791] As for the fluorine-containing lactone represented by formula (D), the following formula (E):

[0792]

[0793] (Among the food, A, B, Rf 12 , X 221 , X 222 and X 223 is identical to Equation (D)

[0794] A five-membered ring structure represented by can be cited as preferable due to its ease of synthesis and good chemical stability, and furthermore, by a combination of A and B, the following formula (F):

[0795]

[0796] (during food, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 is identical to Equation (D)

[0797] Fluorine-containing lactones represented by, and the following formula (G):

[0798]

[0799] (during food, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 is identical to Equation (D)

[0800] There are fluorine-containing lactones represented by .

[0801] Among these, the characteristics as a liquid electrolyte in the present disclosure are improved in that it can particularly exhibit excellent characteristics such as high dielectric constant and high breakdown voltage, and in addition, the solubility of the electrolyte salt and the reduction of internal resistance are good.

[0802]

[0803] You can lift the back.

[0804] By incorporating fluorinated cyclic carboxylic acid esters, effects such as improved ionic conductivity, improved safety, and improved stability at high temperatures are obtained.

[0805] Examples of the above chain carboxylic acid esters include those having a total number of carbon atoms in their structural formulas of 3 to 7. Specifically, examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isobutyl propionate, n-butyl propionate, methyl butyrate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, isopropyl isobutyrate, etc.

[0806] Among these, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, and ethyl butyrate are preferred in terms of improving ionic conductivity due to viscosity reduction.

[0807] As the above ether compounds, chain ethers having 2 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms are preferred.

[0808] Examples of chain ethers 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, diisopropyl ether, etc.

[0809] Examples of cyclic ethers 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, metaformaldehyde, 2-methyl-1,3-dioxolane, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-(trifluoroethyl)dioxolane, 2,2-bis(trifluoromethyl)-1,3-dioxolane, etc., 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 in that they have high solvation ability for lithium ions, thereby improving the degree of ion dissociation, and particularly preferably, they are dimethoxymethane, diethoxymethane, and ethoxymethoxymethane in that they have low viscosity and impart high ion conductivity.

[0810] Examples of the above nitrogen-containing compounds include nitriles, fluorine-containing nitriles, carboxylamides, fluorine-containing carboxylamides, sulfonamides and fluorine-containing sulfonamides, acetamides, formamides, etc. Additionally, 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazilidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide, etc. may also be used. However, nitrile compounds represented by the above general formulas (1a), (1b), and (1c) are not included in the above nitrogen-containing compounds.

[0811] Examples of the above boron-containing compounds include boric acid esters such as trimethylborate and triethylborate, boric acid ethers, and alkyl borates.

[0812] Examples of the above-mentioned organosilicon-containing compounds include (CH3)4-Si, (CH3)3-Si-Si(CH3)3, silicone oil, etc.

[0813] Examples of the above-mentioned non-combustible (flame retardant) agents include phosphate esters or phosphazene-based compounds. Examples of the above-mentioned phosphate esters include fluorine-containing alkyl phosphate esters, non-fluorine-containing alkyl phosphate esters, aryl phosphate esters, etc. Among these, fluorine-containing alkyl phosphate esters are preferred in that they can exhibit a non-combustible effect in a small amount.

[0814] Examples of the above phosphazene compounds include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, ethoxyheptafluorocyclotetraphosphazene, etc.

[0815] Examples of the above fluorine-containing alkyl phosphate esters include, specifically, the fluorine-containing dialkyl phosphate ester described in Japanese Patent Publication No. Hei 11-233141, the cyclic alkyl phosphate ester described in Japanese Patent Publication No. Hei 11-283669, or the fluorine-containing trialkyl phosphate ester.

[0816] As the above-mentioned non-combustible (flame-retardant) agent, (CH3O)3P=O, (CF3CH2O)3P=O, (HCF2CH2O)3P=O, (CF3CF2CH2)3P=O, (HCF2CF2CH2)3P=O, etc. are preferred.

[0817] As the above surfactant, any of cationic surfactants, anionic surfactants, nonionic surfactants, or amphoteric surfactants may be used, but it is preferable that it contains fluorine atoms in order to improve cycle characteristics and rate characteristics.

[0818] The content of the above surfactant is preferably 0.01 to 2 mass% in the liquid electrolyte, in that it can lower the surface tension of the liquid electrolyte without degrading the charge-discharge cycle characteristics.

[0819] Examples of the above-mentioned high-potency additives include sulfolane, methylsulfolane, γ-butyrolactone, γ-valerolactone, etc.

[0820] Examples of the above cycle characteristic and rate characteristic improving agents include methyl acetate, ethyl acetate, tetrahydrofuran, 1,4-dioxane, etc.

[0821] In addition, the liquid electrolyte used in the battery of the present disclosure may also be combined with a polymer material to form a gel-like (plasticized) gel liquid electrolyte.

[0822] Examples of such polymer materials include conventionally known polyethylene oxide or polypropylene oxide and modified versions thereof (Japanese Patent Publication No. Hei 8-222270, Japanese Patent Publication No. 2002-100405); fluorine resins such as polyacrylate-based polymers, polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene copolymers (Japanese Patent Publication No. Hei 4-506726, Japanese Patent Publication No. Hei 8-507407, Japanese Patent Publication No. Hei 10-294131); and composites of these fluorine resins and hydrocarbon-based resins (Japanese Patent Publication No. Hei 11-35765, Japanese Patent Publication No. Hei 11-86630). In particular, it is preferable to use polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers as polymer materials for gel electrolytes.

[0823] In addition, the liquid electrolyte used in the battery of the present disclosure may also include the ion-conducting compound described in the specification of Japanese Patent Application No. 2004-301934.

[0824] This ion-conducting compound is, Formula (101):

[0825] A-(D)-B (101)

[0826] [In the formula, D is formula (201):

[0827] -(D1) n -(FAE) m -(AE) p -(Y) q - (201)

[0828] (Among the formulas, D1 is, formula (2a):

[0829]

[0830] (In the formula, Rf is a fluorine-containing ether group that may have a crosslinkable functional group; R 10 (a group or bonding hand that binds Rf to the main chain)

[0831] An ether unit having a fluorine-containing ether group in a side chain represented by;

[0832] FAE is, Equation (2b):

[0833]

[0834] (In the formula, Rfa is a fluorinated alkyl group that may have a hydrogen atom or a crosslinkable functional group; R 11 (group or bonding hand that binds RFA to the main chain)

[0835] An ether unit having a fluorinated alkyl group in a side chain represented by;

[0836] AE is, Equation (2c):

[0837]

[0838] (during food, R 13 A hydrogen atom, an alkyl group that may have a crosslinkable functional group, an aliphatic cyclic hydrocarbon group that may have a crosslinkable functional group, or an aromatic hydrocarbon group that may have a crosslinkable functional group; R 12 is R 13 (a group or bonding hand that combines the main chain)

[0839] Ether unit indicated by;

[0840] Y is, Equations (2d-1) to (2d-3):

[0841]

[0842] A unit comprising at least one of the following:

[0843] n is an integer from 0 to 200; m is an integer from 0 to 200; p is an integer from 0 to 10000; q is an integer from 1 to 100; provided that n+m is not 0, and the combination order of D1, FAE, AE, and Y is not specified);

[0844] A and B are the same or different, and are an alkyl group that may contain a hydrogen atom, a fluorine atom and / or a crosslinkable functional group, a phenyl group that may contain a fluorine atom and / or a crosslinkable functional group, a -COOH group, -OR (where R is an alkyl group that may contain a hydrogen or fluorine atom and / or a crosslinkable functional group), an ester group or a carbonate group (provided that if the terminal end of D is an oxygen atom, it is not a -COOH group, -OR, an ester group, or a carbonate group)]

[0845] It is an amorphous fluorine-containing polyether compound having a fluorine-containing group in the side chain represented by .

[0846] The liquid electrolyte used in the battery of the present disclosure may include a sulfone compound. As for 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.

[0847] Examples of cyclic sulfones include monosulfone compounds such as trimethylenesulfones, tetramethylenesulfones, and hexamethylenesulfones; and disulfone compounds such as trimethylenedisulfones, tetramethylenedisulfones, and hexamethylenedisulfones. Among these, in terms of dielectric constant and viscosity, tetramethylenesulfones, tetramethylenedisulfones, hexamethylenesulfones, and hexamethylenedisulfones are more preferred, and tetramethylenesulfones (sulfolanes) are particularly preferred.

[0848] As for sulforaids, sulforaids and / or sulforaid derivatives (hereinafter, sulforaids may also be abbreviated as "sulforaids") are preferred. As for sulforaid derivatives, it is preferred that one or more hydrogen atoms bonded to carbon atoms constituting the sulforaid ring are substituted with fluorine atoms or alkyl groups.

[0849] Among them, 2-methylsulforan, 3-methylsulforan, 2-fluorosulforan, 3-fluorosulforan, 2,2-difluorosulforan, 2,3-difluorosulforan, 2,4-difluorosulforan, 2,5-difluorosulforan, 3,4-difluorosulforan, 2-fluoro-3-methylsulforan, 2-fluoro-2-methylsulforan, 3-fluoro-3-methylsulforan, 3-fluoro-2-methylsulforan, 4-fluoro-3-methylsulforan, 4-fluoro-2-methylsulforan, 5-fluoro-3-methylsulforan, 5-fluoro-2-methylsulforan, 2-fluoromethylsulforan, 3-fluoromethylsulforan, 2-difluoromethylsulforan, 3-difluoromethylsulforan, 2-trifluoromethylsulforan, 3-trifluoromethylsulforan, 2-fluoro-3-(trifluoromethyl)sulfolane, 3-fluoro-3-(trifluoromethyl)sulfolane, 4-fluoro-3-(trifluoromethyl)sulfolane, 3-sulforene, 5-fluoro-3-(trifluoromethyl)sulfolane, etc. are desirable in that they have high ion conductivity and high input / output.

[0850] In addition, as chain sulfones, dimethylsulfone, ethylmethylsulfone, diethylsulfone, n-propylmethylsulfone, n-propylethylsulfone, di-n-propylsulfone, isopropylmethylsulfone, isopropylethylsulfone, diisopropylsulfone, n-butylmethylsulfone, n-butylethylsulfone, t-butylmethylsulfone, t-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, trifluoroethylmethylsulfone, pentafluoroethylmethylsulfone, ethyl monofluoromethylsulfone, ethyl difluoromethylsulfone, ethyl trifluoromethylsulfone, perfluoroethylmethylsulfone, ethyl trifluoroethylsulfone, ethyl pentafluoroethylsulfone, di(trifluoroethyl)sulfone, perfluorodiethylsulfone, fluoromethyl-n-propylsulfone, difluoromethyl-n-propylsulfone, Examples include trifluoromethyl-n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoroethylisopropylsulfone, trifluoroethyl-n-butylsulfone, trifluoroethyl-t-butylsulfone, pentafluoroethyl-n-butylsulfone, and pentafluoroethyl-t-butylsulfone.

[0851] Among them, dimethylsulfone, ethylmethylsulfone, diethylsulfone, n-propylmethylsulfone, isopropylmethylsulfone, n-butylmethylsulfone, t-butylmethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, trifluoroethylmethylsulfone, pentafluoroethylmethylsulfone, ethyl monofluoromethylsulfone, ethyl difluoromethylsulfone, ethyl trifluoromethylsulfone, ethyl trifluoroethylsulfone, ethyl pentafluoroethylsulfone, trifluoromethyl-n-propylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-butylsulfone, trifluoroethyl-t-butylsulfone, trifluoromethyl-n-butylsulfone, trifluoromethyl-t-butylsulfone, and trifluoromethyl-t-butylsulfone are preferred in that they have high ionic conductivity and high input / output.

[0852] The content of the sulfone compound is not particularly limited and is optional as long as it does not significantly impair the effects of the present disclosure, but is typically 0.3 volume% or more, preferably 0.5 volume% or more, more preferably 1 volume% or more in 100 volume% of the solvent, and is also typically 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 an effect of improving durability, such as cycle characteristics or storage characteristics, and also the viscosity of the non-aqueous liquid electrolyte can be set to an appropriate range to avoid a decrease in electrical conductivity, and the input / output characteristics or charge / discharge rate characteristics of the non-aqueous liquid electrolyte secondary battery can be set to an appropriate range.

[0853] In order to improve output characteristics, the liquid electrolyte used in the battery of the present disclosure may also include, 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.

[0854] In addition, when using compound (7) as an additive, it is preferable to use a compound other than compound (7) as the electrolyte salt described above.

[0855] Examples of the above lithium fluorophosphate salts include lithium monofluorophosphate (LiPO3F) and lithium difluorophosphate (LiPO2F2).

[0856] Examples of lithium salts having the above S=O group include lithium monofluorosulfonic acid (FSO3Li), lithium methylsulfate (CH3OSO3Li), lithium ethylsulfate (C2H5OSO3Li), 2,2,2-trifluoroethylsulfate, etc.

[0857] Among the compounds (7), LiPO2F2, FSO3Li, and C2H5OSO3Li are preferred.

[0858] The content of compound (7) is preferably 0.001 to 20 mass% with respect to the liquid electrolyte, more preferably 0.01 to 15 mass%, even more preferably 0.1 to 10 mass%, and particularly preferably 0.1 to 7 mass%.

[0859] In the liquid electrolyte used in the battery of the present disclosure, other additives may also be incorporated as needed. Examples of other additives include metal oxides, glass, etc.

[0860] The liquid electrolyte used in the battery of the present disclosure preferably has a hydrogen fluoride (HF) content of 5 to 200 ppm. By containing HF, the film formation of the aforementioned additive can be promoted. If the HF content is too low, the ability to form a film on the negative electrode is reduced, and the characteristics of the electrochemical device tend to deteriorate. In addition, if the HF content is too high, the oxidation resistance of the liquid electrolyte tends to decrease due to the influence of HF. Even if the liquid electrolyte used in the battery of the present disclosure contains HF within the above range, it does not reduce the high-temperature retention recovery capacity rate of the electrochemical device.

[0861] The HF content is more preferably 10 ppm or more, and even more preferably 20 ppm or more. The HF content is also more preferably 100 ppm or less, even more preferably 80 ppm or less, and particularly preferably 50 ppm or less.

[0862] The HF content can be measured by the neutralization titration method.

[0863] The liquid electrolyte used in the battery of the present disclosure can be prepared by any method using the components described above.

[0864] (Straight play)

[0865] In the battery of the present disclosure, the positive electrode may be composed of a positive electrode active material layer including a positive electrode active material and a current collector, although it is not particularly limited.

[0866] The above positive electrode active material is not particularly limited as long as it is capable of electrochemically absorbing and releasing at least one metal ion selected from lithium, sodium, magnesium, and zinc, but, for example, a material containing an alkali metal and at least one transition metal is preferred. Specific examples include alkali metal-containing transition metal composite oxides, alkali metal-containing transition metal phosphate compounds, sulfur-based materials, conductive polymers, etc.

[0867] Among these, as a positive electrode active material, an alkali metal-containing transition metal composite oxide that generates particularly high voltage is preferred. Examples of the alkali metal ions include lithium ions and sodium ions. In a preferred embodiment, the alkali metal ion may be a lithium ion. That is, in this embodiment, the alkali metal ion secondary battery is a lithium ion secondary battery.

[0868] As the above alkali metal-containing transition metal complex oxide, for example

[0869] Formula: MaMn2 - b M 1 b O4

[0870] (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 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,

[0871] Formula: MNi1 - c M 2c O2

[0872] (wherein M is at least one metal selected from the group consisting of Li and Na; 0≤c≤0.5; M 2 is an alkali metal-nickel complex 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,

[0873] Formula: MCo1 - d M 3 d O2

[0874] (wherein M is at least one metal selected from the group consisting of Li and Na; 0≤d≤0.5; M 3 (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)

[0875] Examples include alkali metal-cobalt complex oxides represented by . In the above, M is preferably one metal selected from the group consisting of Li and Na, is Li or Na, and more preferably is Li.

[0876] Among them, MCoO2, MMnO2, MNiO2, MMn2O4, and MNi0 are capable of providing high-energy density and high-output secondary batteries. . 8Co0 . 15 Al0 . 05 O2, or MNi1 / 3Co1 / 3Mn1 / 3O2, etc. is preferred, and it is preferred to be a compound represented by the following general formula (3).

[0877] MNi h Co i Mnj M 5 k O2(3)

[0878] (among the food, M is, M 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, and (h+i+j+k)=1.0, 0≤h≤1.0, 0≤i≤1.0, 0≤j≤1.5, 0≤k≤0.2.)

[0879] As the above alkali metal-containing transition metal phosphate compound, for example, the following formula (4)

[0880] M e M 4 f (PO4) g

[0881] (In the formula, M is at least one metal selected from the group consisting of Li and Na, and M 4 represents at least one selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni, and Cu, and may be an example of a compound represented by 0.5≤e≤3, 1≤f≤2, 1≤g≤3). In the above, M is preferably one metal selected from the group consisting of Li and Na, and more preferably Li.

[0882] As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferred. Specific examples include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, cobalt phosphates such as LiCoPO4, and those in which some of the transition metal atoms forming the main component of these lithium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si. It is preferable for the above lithium-containing transition metal phosphate compound to have an olivine-type structure.

[0883] Other positive electrode active materials include MFePO4 and MNI0 . 8Co0 . 2O2, M 1. 2Fe0 . 4Mn0 . 4O2, MNi 0.5 Mn 1.5 O2, MV3O6, M2MnO3, MMnO3 You can lift the back . In particular, M2MnO3, MNi0 . 5Mn1 . Positive electrode active materials such as 5O2 are desirable in that their crystal structure does not collapse when the secondary battery is operated at a voltage exceeding 4.4V or at a voltage of 4.6V or higher. Accordingly, an electrochemical device such as a secondary battery using a positive electrode material including the positive electrode active material exemplified above is desirable in that the remaining capacity is unlikely to decrease and the resistance increase rate is unlikely to change even when stored at high temperatures, and the battery performance does not deteriorate even when operated at high voltages.

[0884] 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 6Solid solution materials with transition metals such as silver, Co, Ni, Mn, and Fe can also be cited.

[0885] As the above solid solution material, for example, the general formula Mx[Mn(1-y)M 7 It is an alkali metal manganese oxide represented by y]Oz. Here, M in the formula is at least one metal selected from the group consisting of Li and Na, and M 7 It includes at least one metallic element other than silver, M, and Mn, and includes one or more elements selected from the group consisting of, for example, Co, Ni, Fe, Ti, Mo, W, Cr, Zr, and Sn. In addition, the values ​​of x, y, and z in the formula are 0.5 <x<2, 0≤y<1, 1.5<z<3의 범위이다. 그 중에서도, Li 1.2 Mn 0.5 Co 0.14 Ni 0.14 A manganese-containing solid solution material based on Li2MnO3, such as O2, incorporating LiNiO2 or LiCoO2 is desirable in that it can provide an alkali metal ion secondary battery with high energy density.

[0886] In addition, it is desirable to include lithium phosphate in the positive electrode active material as this improves continuous charging characteristics. Although there are no restrictions on the use of lithium phosphate, it is preferable to use a mixture of the above-mentioned positive electrode active material and lithium phosphate. The amount of lithium phosphate used is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more with respect to the total of the above-mentioned positive electrode active material and lithium phosphate, with a lower limit of preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more, and an upper limit of preferably 10 mass% or less, more preferably 8 mass% or less, and even more preferably 5 mass% or less.

[0887] As the above sulfur-based material, examples include materials containing sulfur atoms, 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 metal sulfide may be a metal polysulfide. The organic sulfur compound may be an organic polysulfide.

[0888] As the above metal sulfide, LiS x (0 <x≤8)로 표시되는 화합물; Li2S x (0 <x≤8)로 표시되는 화합물; TiS2나 MoS2등의 이차원 층상 구조를 갖는 화합물; 일반식 Me x Examples include Chevrell compounds having a robust three-dimensional skeletal structure represented by Mo6S8 (Me is various transition metals including Pb, Ag, and Cu).

[0889] Examples of the above organic sulfur compounds include carbon sulfide compounds.

[0890] The above organic sulfur compound may be supported on a porous material such as carbon and used as a carbon composite material. As for the sulfur content included in the carbon composite material, 10 to 99 mass% is preferred with respect to the carbon composite material, 20 mass% or more is more preferred, 30 mass% or more is more preferred, 40 mass% or more is particularly preferred, and 85 mass% or less is preferred, as this further improves cycle performance and reduces overpotential.

[0891] When the above positive electrode active material is the above sulfur element, the sulfur content included in the above positive electrode active material is equivalent to the content of the above sulfur element.

[0892] Examples of conductive polymers include p-doped conductive polymers and n-doped conductive polymers. Examples of conductive polymers include polyacetylene-based, polyphenylene-based, heterocyclic polymers, ionic polymers, ladder and network polymers, etc.

[0893] In addition, a material with a different composition may be attached to the surface of the above positive electrode active material. Examples of surface-attached materials 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; and carbon.

[0894] These surface-attaching materials can be attached to the surface of the corresponding positive electrode active material by, for example, by dissolving or suspending them in a solvent and adding them as an impregnation to the corresponding positive electrode active material and drying; by dissolving or suspending a surface-attaching material precursor in a solvent and adding it as an impregnation to the corresponding positive electrode active material, followed by a reaction by heating, etc.; or by adding them to a positive electrode active material precursor and simultaneously calcining. In addition, when carbon is attached, a method of later mechanically attaching carbonaceous material in the form of, for example, activated carbon may also be used.

[0895] As for the amount of surface-attached material, in terms of mass relative to the positive electrode active material, it is used in a lower limit of preferably 0.1 ppm or more, more preferably 1 ppm or more, even more preferably 10 ppm or more, and in an upper limit of preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. Although the oxidation reaction of the liquid electrolyte on the surface of the positive electrode active material can be suppressed by the surface-attached material and the battery life can be improved, if the amount of attachment is too small, the effect is not sufficiently manifested, and if it is too large, resistance may increase because it hinders the entry and exit of lithium ions.

[0896] The particle shapes of the positive electrode active material can be lumpy, polyhedral, spherical, elliptical, plate-like, needle-like, columnar, etc., as used in the past. In addition, primary particles may aggregate to form secondary particles.

[0897] The tap density of the positive electrode active material is preferably 0.5 g / cm³ or higher, more preferably 0.8 g / cm³ or higher, and even more preferably 1.0 g / cm³ or higher. If the tap density of the positive electrode active material falls below the above lower limit, the amount of dispersion medium required during the formation of the positive electrode active material layer increases, and the amount of conductive material or binder required increases, which constrains the filling rate of the positive electrode active material in the positive electrode active material layer and may constrain the battery capacity. By using a composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, a higher tap density is preferable, and there is no specific upper limit; however, if it is too high, the diffusion of lithium ions using the liquid electrolyte as a medium within the positive electrode active material layer becomes rate-limited, and the load characteristics may easily deteriorate; therefore, the upper limit is preferably 4.0 g / cm³ or lower, more preferably 3.7 g / cm³ or lower, and even more preferably 3.5 g / cm³ or lower.

[0898] In addition, in the present disclosure, the tap density is determined as the powder packing density (tap density) g / cm³ when 5 to 10 g of positive electrode active material powder is placed in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm.

[0899] The median diameter d50 of the particles of the positive electrode active material (the diameter of the secondary particles in cases where primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more; additionally, it is preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If it falls below the lower limit, a high-tap density product may not be obtained, and if it exceeds the upper limit, lithium diffusion within the particles takes time, which may lead to a decrease in battery performance or cause problems such as streaking when manufacturing the positive electrode of the battery, that is, when slurrying the active material with a conductive material or binder with a solvent and coating it as a thin film. Here, by mixing two or more types of the above positive electrode active materials having different median diameters d50, the chargeability during the manufacturing of the positive electrode can be further improved.

[0900] In addition, in the present disclosure, the median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. When using HORIBA LA-920 as the particle size distribution meter, a 0.1 mass% aqueous sodium hexametaphosphate solution is used as the dispersion medium during measurement, and the measurement is performed by setting the refractive index to 1.24 after 5 minutes of ultrasonic dispersion.

[0901] In cases where primary particles aggregate 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 even more preferably 0.2 μm or more, and the upper limit is preferably 5 μm or less, more preferably 4 μm or less, even more 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 adversely affects the powder packing properties or significantly reduces the specific surface area, so there is a high possibility that battery performance, such as output characteristics, will deteriorate. Conversely, if the lower limit is lowered, problems such as reduced reversibility of charge and discharge may occur because crystals are typically underdeveloped.

[0902] In addition, in the present disclosure, the primary particle size is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the longest value of the intercept by the left and right boundary lines of the primary particle with respect to a straight line in the horizontal direction is obtained for any 50 primary particles, and the average value is taken.

[0903] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m² / g or more, more preferably 0.2 m² / g or more, and even more preferably 0.3 m² / g or more, and the upper limit is preferably 50 m² / g or less, more preferably 40 m² / g or less, and even more preferably 30 m² / g or less. If the BET specific surface area is smaller than this range, battery performance is likely to degrade, and if it is larger, it becomes difficult to increase the tap density, which may cause problems with coating properties when forming the positive electrode active material layer.

[0904] In addition, in the present disclosure, the BET specific surface area is defined as a value measured by the nitrogen adsorption BET 1-point method by the gas flow method, using a surface area meter (e.g., an automatic surface area measuring device manufactured by Okura Riken), a sample is pre-dried at 150°C for 30 minutes under nitrogen flow, and then a nitrogen-helium mixed gas is accurately adjusted so that the relative pressure of nitrogen with respect to atmospheric pressure is 0.3.

[0905] 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, so it is preferable that the particles of the positive electrode active material consist mainly of secondary particles.

[0906] It is preferable that the particles of the positive electrode active material contain 0.5 to 7.0 volume% of fine particles having an average particle size of secondary particles of 40 μm or less and an average primary particle size of 1 μm or less. By including fine particles with an average primary particle size of 1 μm or less, the contact area with the liquid electrolyte is increased, thereby allowing for faster diffusion of lithium ions between the electrode and the liquid electrolyte, and as a result, the output performance of the battery can be improved.

[0907] As a method for manufacturing positive electrode active materials, general methods for manufacturing inorganic compounds are used. In particular, various methods can be considered to produce spherical or elliptical active materials. For example, a method may be used in which a transition metal raw material is dissolved or ground and dispersed in a solvent such as water, a spherical precursor is produced and recovered by adjusting the pH while stirring, and then dried as necessary, followed by the addition of a Li source such as LiOH, Li2CO3, or LiNO3 and calcination at a high temperature to obtain the active material.

[0908] For the manufacture of the positive electrode, the above-described positive electrode active material may be used alone, or two or more materials of different compositions may be used in combination or in any ratio. In this case, a preferred combination is LiCoO2 and LiNiO2. . 33 Co0 . 33 Mn0 . 33 Examples include combinations of LiMn2O4 such as O2, or in which part of this Mn is substituted with other transition metals, or combinations of LiCoO2 or in which part of this Co is substituted with other transition metals.

[0909] The content of the positive electrode active material is preferably 50 to 99.5 mass% of the positive electrode composite, and more preferably 80 to 99 mass%, in terms of high battery capacity. In addition, the content of the positive electrode active material in the positive electrode active material layer is preferably 80 mass% or more, more preferably 82 mass% or more, and particularly preferably 84 mass% or more. In addition, the upper limit is preferably 99 mass% or less, and more preferably 98 mass% or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electrical capacity may become insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0910] The above positive electrode composite also preferably includes a binder, a thickener, and a conductive material.

[0911] As the above-mentioned binder, any material that is safe with respect to the solvent or liquid electrolyte used during electrode manufacturing may be used, for example, resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, nitrocellulose; rubbery polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or its hydrogenated derivative; thermoplastic elastomeric polymers such as EPDM (ethylene-propylene-diene ternary copolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer or its hydrogenated derivative; Examples include soft resinous polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; fluorinated polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymer, and tetrafluoroethylene-ethylene copolymer; and polymer compositions having ion conductivity of alkali metal ions (especially lithium ions). These may be used individually, or two or more may be used in any combination and ratio.

[0912] The content of the binder is, as a ratio of the binder in the positive electrode active material layer, typically 0.1 mass% or more, preferably 1 mass% or more, more preferably 1.5 mass% or more, and typically 80 mass% or less, preferably 60 mass% or less, more preferably 40 mass% or less, and most preferably 10 mass% or less. If the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained, resulting in insufficient mechanical strength of the positive electrode and potentially deteriorating battery performance such as cycle characteristics. On the other hand, if it is too high, it may lead to a decrease in battery capacity or conductivity.

[0913] Examples of the above-mentioned thickeners include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, polyvinylpyrrolidone, and salts thereof. One type may be used alone, or two or more types may be used in any combination and ratio.

[0914] The ratio of the thickener to the active material is typically 0.1 mass% or more, preferably 0.2 mass% or more, more preferably 0.3 mass% or more, and is also typically 5 mass% or less, preferably 3 mass% or less, more preferably 2 mass% or less. If it falls below this range, the coating performance may be significantly reduced. If it exceeds this range, the proportion of the active material occupying the positive electrode active material layer decreases, which may cause problems such as a decrease in battery capacity or an increase in resistance between positive electrode active materials.

[0915] As the above conductive material, any known conductive material may be used. Specific examples include 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, and thermal black, and carbon materials such as needle coke, carbon nanotubes, fullerene, and amorphous carbon such as VGCF. Furthermore, one of these may be used alone, or two or more may be used in any combination and ratio. The conductive material is used in the positive electrode active material layer in an amount of typically 0.01 mass% or more, preferably 0.1 mass% or more, more preferably 1 mass% or more, and typically 50 mass% or less, preferably 30 mass% or less, more preferably 15 mass% or less. If the content is lower than this range, the conductivity may become insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

[0916] As a solvent for forming the slurry, there are no particular restrictions on its type as long as it is a solvent capable of dissolving or dispersing the positive electrode active material, conductive material, binder, and, if necessary, the thickener; either aqueous or organic solvents may be used. Examples of aqueous solvents include water and a mixture of alcohol and water. Examples of organic solvents include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and 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; and ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF). Examples include amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; and non-protonic polar solvents such as hexamethylphosphalamide and dimethyl sulfoxide.

[0917] Examples of materials for the positive electrode current collector include metal materials such as aluminum, titanium, tantalum, stainless steel, nickel, or their alloys; and carbon materials such as carbon cloth or carbon paper. Among these, metal materials, particularly aluminum or its alloys, are preferred.

[0918] Examples of shapes for the current collector include, in the case of metal materials, metal foil, metal cylinder, metal coil, metal plate, metal thin film, metal composite foil, expanded metal, punched metal, foamed metal, etc., and in the case of carbon materials, carbon plate, carbon thin film, carbon cylinder, etc. Among these, a metal thin film is preferred. In addition, the thin film may be formed into a mesh shape as appropriate. The thickness of the thin film is arbitrary, but is typically 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and typically 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the thin film is thinner than this range, it may lack the strength required as a current collector. Conversely, if the thin film is thicker than this range, handling properties may be compromised.

[0919] In addition, it is desirable to have a conductive aid coated on the surface of the current collector to reduce the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of conductive aids include carbon and precious metals such as gold, platinum, and silver.

[0920] Although the ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, it is preferable that the value of (thickness of the positive electrode active material layer on one side immediately before the liquid electrolyte injection) / (thickness of the current collector) be 20 or less, more preferably 15 or less, most preferably 10 or less, and also preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. If it exceeds this range, the current collector may generate heat due to Joule heating during high current density charging and discharging. If it falls below this range, the volume ratio of the current collector to the positive electrode active material increases, and the capacity of the battery may decrease.

[0921] The manufacturing of the positive electrode can be done by conventional methods. For example, a method may be used in which the aforementioned binder, thickener, conductive material, solvent, etc. are added to the positive electrode active material to form a slurry-type positive electrode mixture, which is then coated onto a current collector, dried, and then pressed to increase density.

[0922] The above high-density can be achieved by means of a hand press, a roller press, etc. The density of the positive electrode active material layer is preferably 1.5 g / cm³ or more, more preferably 2 g / cm³ or more, and even more preferably 2.2 g / cm³ or more, and is also preferably 5 g / cm³ or less, more preferably 4.5 g / cm³ or less, and even more preferably 4 g / cm³ or less. If it exceeds this range, the permeability of the liquid electrolyte near the current collector / active material interface decreases, and in particular, charge / discharge characteristics at high current densities deteriorate, and high output may not be obtained. Furthermore, if it falls below this range, the conductivity between active materials decreases, and battery resistance increases, and high output may not be obtained.

[0923] When using the liquid electrolyte used in the battery of the present disclosure or the liquid electrolyte used in the alkali metal secondary battery of the present disclosure, it is desirable to make the area of ​​the positive electrode active material layer larger relative to the outer surface area of ​​the battery casing in order to increase high output and stability at high temperatures. Specifically, it is desirable that the total area of ​​the positive electrode relative to the surface area of ​​the secondary battery casing be at least 15 times in terms of area ratio, and furthermore, it is more desirable that it be at least 40 times. The outer surface area of ​​the battery casing refers to the total area calculated from the length, width, and thickness of the case portion charged with the power generation element, excluding the terminal protrusion portion, in the case of a rectangular shape with a bottom. In the case of a cylindrical shape with a bottom, it is the geometric surface area approximated as a cylinder for the case portion charged with the power generation element, excluding the terminal protrusion portion. The total area of ​​the positive electrode refers to the geometric surface area of ​​the positive electrode composite layer facing the composite layer containing the negative electrode active material, and in a structure formed by forming the positive electrode composite layer on both sides through a current collector foil, it refers to the total area calculated for each side.

[0924] Although 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 obtained by subtracting the thickness of the metal foil of the core material is preferably 10 μm or more, more preferably 20 μm or more as a lower limit for one side of the current collector, and also preferably 500 μm or less, more preferably 450 μm or less.

[0925] In addition, a material with a composition different from this may be attached to the surface of the above positive electrode plate. Examples of surface-attached materials 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; and carbon.

[0926] (Separator)

[0927] The secondary battery of the present disclosure is also preferably equipped with a separator.

[0928] The material or shape of the separator described above is not particularly limited and known materials may be used as long as they are stable with respect to the liquid electrolyte and have excellent liquid retention properties. Among these, it is preferable to use a resin, glass fiber, inorganic material, etc., formed from a material that is stable with respect to the liquid electrolyte used in the battery of the present disclosure or the liquid electrolyte used in the alkali metal secondary battery of the present disclosure, and to use a porous sheet or non-woven material having excellent liquid retention properties.

[0929] As materials for resins and glass fiber separators, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, glass filters, etc., may be used. These materials, such as polypropylene / polyethylene two-layer films and polypropylene / polyethylene / polypropylene three-layer films, may be used as a single type or two or more types may be used in any combination and ratio.

[0930] Among these, the separator is preferably a porous sheet or nonwoven fabric made of polyolefins such as polyethylene and polypropylene, in that it has good permeability of the liquid electrolyte and shutdown effect.

[0931] The thickness of the separator is arbitrary, but is typically 1 μm or more, preferably 5 μm or more, and more preferably 8 μm or more. Additionally, it is typically 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is too thin compared to the above range, the insulation properties or mechanical strength may decrease. Furthermore, if it is too thick compared to the above range, not only may battery performance such as rate characteristics decrease, but the energy density of the liquid electrolyte battery as a whole may also decrease.

[0932] In addition, when a porous material such as a porous sheet or nonwoven fabric is used as a separator, the porosity of the separator is optional, but is typically 20% or more, preferably 35% or more, and more preferably 45% or more, and is typically 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too small compared to the above range, the film resistance increases and the rate characteristics tend to deteriorate. In addition, if it is too large compared to the above range, the mechanical strength of the separator decreases and the insulation performance tends to decrease.

[0933] In addition, the average hole diameter of the separator is arbitrary, but is typically 0.5 μm or less, preferably 0.2 μm or less, and is also typically 0.05 μm or more. If the average hole diameter exceeds the above range, short circuits are likely to occur. In addition, if it falls below the above range, the film resistance increases and rate characteristics may deteriorate.

[0934] Meanwhile, as inorganic materials, oxides such as alumina or silicon dioxide, nitrides such as aluminum nitride or silicon nitride, and sulfates such as barium sulfate or calcium sulfate are used, and they are used in the form of particles or fibers.

[0935] As for the form, a thin film shape such as a nonwoven fabric, a woven fabric, or a microporous film is used. As for the thin film shape, a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is suitably used. In addition to the above independent thin film shape, a separator may be used in which a composite porous layer containing the inorganic particles is formed on the surface of the positive electrode and / or negative electrode using a resin binder.

[0936] For example, a porous layer can be formed on both sides of the positive electrode using fluoropolymer resin as a binder, with 90% of the alumina particles having a particle size of less than 1 μm.

[0937] (Battery Design)

[0938] The electrode group may be of a stacked structure formed by interposing the positive electrode plate and the negative electrode plate with the separator, or a structure formed by interposing the positive electrode plate and the negative electrode plate with the separator and winding them in a spiral shape. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy rate) is typically 40% or more, preferably 50% or more, and typically 90% or less, preferably 80% or less.

[0939] If the electrode group occupancy rate falls below the above range, the battery capacity decreases. Furthermore, if it exceeds the above range, the void space is reduced, and as the battery becomes high temperature, the components expand or the vapor pressure of the liquid electrolyte component increases, causing the internal pressure to rise. This degrades various characteristics of the battery, such as charge-discharge cycle performance and high-temperature retention, or, furthermore, may cause the gas release valve to activate to release the internal pressure.

[0940] Although the current collection structure is not particularly limited, in order to more effectively realize the improvement of high current density charge / discharge characteristics by the liquid electrolyte used in the battery of the present disclosure or the liquid electrolyte used in the alkali metal secondary battery of the present disclosure, it is preferable to have a structure that reduces the resistance of the wiring portion or the junction portion. When internal resistance is reduced in this way, the effect of using the liquid electrolyte used in the battery of the present disclosure or the liquid electrolyte used in the alkali metal secondary battery of the present disclosure is exhibited particularly well.

[0941] In the case where the electrode group has the above-mentioned laminated structure, a structure formed by binding the metal core portions of each electrode layer together and welding them to terminals is suitably used. When the surface area of ​​a single electrode increases, the internal resistance increases, so providing multiple terminals within the electrode to reduce the resistance is also suitably used. In the case where the electrode group has the above-mentioned wound structure, the internal resistance can be lowered by providing multiple lead structures on the positive electrode and the negative electrode, respectively, and binding them to terminals.

[0942] The material of the outer casing is not particularly limited as long as it is a material that is stable with respect to the liquid electrolyte used. Specifically, metals such as nickel-plated steel sheets, stainless steel, aluminum or aluminum alloys, and magnesium alloys, or laminated films of resin and aluminum foil are used. From the perspective of weight reduction, metals such as aluminum or aluminum alloys and laminated films are suitably used.

[0943] Examples of exterior cases using metals include those that form a sealed structure by welding metals together using laser welding, resistance welding, or ultrasonic welding, or those that form a caulking structure using the said metals with a resin gasket interposed. Examples of exterior cases using the said laminate film include those that form a sealed structure by thermally fusing resin layers together. To improve sealability, a resin different from the resin used in the laminate film may be interposed between the said resin layers. In particular, when a sealed structure is formed by thermally fusing resin layers with a current collection terminal interposed, since the metal and resin are bonded, a resin having polar groups or a modified resin having polar groups introduced is suitably used as the interposed resin.

[0944] The shape of the secondary battery of the present disclosure is arbitrary, and examples include cylindrical, prismatic, laminated, coin, and large shapes. In addition, the shape and configuration of the positive electrode, negative electrode, and separator can be changed and used according to the shape of each battery.

[0945] Examples

[0946] The present disclosure will be explained in detail below based on examples. In the following examples, unless otherwise specifically stated, "parts" and "%" represent "parts by mass" and "mass%", respectively.

[0947] · Types of fluoropolymers

[0948] Polymer A:

[0949] Fluoropolymer containing vinylidene fluoride (VdF) units and tetrafluoroethylene (TFE) units

[0950] VdF / TFE=81 / 19(mol%)

[0951] Weight-average molecular weight: 970,000

[0952] Melting point: 128℃

[0953] Polymer B:

[0954] Fluoropolymer containing VdF units and trifluoroethylene (TrFE) units

[0955] VdF / TrFE=80 / 20(mol%)

[0956] Weight-average molecular weight: 720,000

[0957] Melting point: 165℃

[0958] Polymer C:

[0959] Fluoropolymer containing VdF units, TrFE units, and chlorotrifluoroethylene (CTFE) units

[0960] VdF / TrFE / CTFE=65 / 28 / 7(mol%)

[0961] Weight-average molecular weight: 650,000

[0962] Melting point: 170℃

[0963] Polymer D:

[0964] Fluoropolymer containing VdF units and acrylic acid units

[0965] VdF / Acrylic acid = 99 / 1 (mol%)

[0966] Weight-average molecular weight: 1,120,000

[0967] Melting point: 161℃

[0968] Polymer E:

[0969] Fluoropolymer containing VdF units and 2,3,3,3-tetrafluoropropene units

[0970] VdF / 2,3,3,3-tetrafluoropropene=77 / 23

[0971] Weight-average molecular weight: 480,000

[0972] Tg: -13℃

[0973] Mooney viscosity: ML1+10(121℃)): 25

[0974] Polymer F:

[0975] Fluoropolymer containing VdF units and perfluoro-(2,9,9-trihaloid-5-trifluoromethyl-3,6-dioxa-8-heptene)(AEHF-1) units

[0976] VdF / AEHF-1=81.4 / 18.6

[0977] Weight-average molecular weight: 950,000

[0978] Tg: -27℃

[0979] Mooney viscosity: (ML1+10(121℃)): 15

[0980] In addition, AEHF-1 is a compound represented by the following general formula.

[0981]

[0982] Polymer G: (Polymer of the comparative example)

[0983] Fluoropolymer containing VdF units and hexafluoropropylene (HFP) units

[0984] VdF / HFP=95:5

[0985] Weight-average molecular weight: 870,000

[0986] Melting point: 141℃

[0987] · Types of fluoride ethers

[0988] (E-1) HCF2-CF2-O-CH2-CF2-CF2H

[0989] (E-2) HCF2-CF2-O-CH2-CH2-CH3

[0990] (E-3) HCF2-CF2-O-CH2-CH2-CH2-CH3

[0991] (E-4) HCF2-CF2-O-CH2-CF3

[0992] (E-5) HCF2-CF2-O-CH2-CH2-O-CF2-CF2H

[0993] (E-6) CF3-CF2-CH2-O-CH2-CF2-CF3

[0994] · Lithium salt

[0995] LiPF6

[0996] LiFSI: Lithium bis(fluorosulfonyl)imide

[0997] LiBOB: Lithium bis(oxalato)borate

[0998] · Cyclic carbonate

[0999] EC: Ethylene carbonate

[1000] FEC: Fluoroethylene carbonate

[1001] ·Chain carbonate

[1002] EMC: Ethylmethyl carbonate

[1003] DMC: Dimethyl carbonate

[1004] · Other solvents

[1005] GBL: γ-butyrolactone

[1006] DME: Dimethoxyethane

[1007] (Method for measuring weight-average molecular weight)

[1008] It was measured by gel permeation chromatography (GPC). It was calculated from data (reference: polystyrene) measured using Tosho AS-8010, CO-8020, a column (three GMHHR-H connected in series), and Shimadzu Seisakusho RID-10A, with dimethylformamide (DMF) flowing as the solvent at a flow rate of 1.0 ml / min.

[1009] (Method of measuring Tg)

[1010] Using a differential scanning calorimeter (X-DSC823e manufactured by Hitachi Techno Science Co., Ltd.), a DSC curve was obtained by heating 10 mg of the sample at 20°C / min, and the temperature representing the intersection of the extension of the baseline before and after the second transition of the DSC curve and the tangent at the inflection point of the DSC curve was defined as the glass transition temperature (Tg).

[1011] (Method for measuring Mooney viscosity)

[1012] Mooney Viscosity (ML1+10(121℃, 140℃))

[1013] Measurements were taken in accordance with ASTM-D1646-15 and JIS K6300-1:2013.

[1014] Measuring instrument: ALPHA TECHNOLOGIES MV2000E

[1015] Rotor speed: 2 rpm

[1016] Measured temperature: 121℃, 140℃

[1017] (Examples 1 to 17, Comparative Examples 1 to 6)

[1018] (Potting for the whole house)

[1019] A protective film-forming composition was obtained by dissolving 8 parts by weight of various fluorine polymers in N-methyl-2-pyrrolidone (NMP), a solvent.

[1020] The above protective film-forming composition was coated to a thickness of 5 μm on a copper foil (15 μm) serving as a negative electrode current collector using a doctor blade. The coated composition was dried at approximately 100°C. An electrode was fabricated by cutting it 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 / cm³. In addition, in Comparative Examples 2 and 3, a copper foil without the coating was used as an electrode.

[1021] Separately, a positive electrode composition was obtained by mixing LiCoO2, a conductive agent (Super-P, Timcal Ltd.), polyvinylidene fluoride (PVdF), and NMP. In the positive electrode composition, the mixing weight ratio of LiCoO2, the conductive agent, and PVDF is 97:1.5:1.5.

[1022] The above positive electrode composition was coated onto 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 produce an electrode.

[1023] A laminate cell was manufactured by interposing a polyethylene / polypropylene separator between the positive electrode obtained by the above process and the negative electrode current collector foil. Here, various electrolytes were obtained between the positive electrode and the negative electrode from combinations of Li salt and solvent listed in Table 1.

[1024] High-temperature preservation characteristics evaluation test

[1025] The coin cell manufactured above was charged with a constant current-constant voltage (hereinafter referred to as CC / CV charging) (0.1C cut) to 4.4V at 25°C with a current equivalent to 0.2C, and then discharged to 3V with a constant current of 0.2C. This was considered one cycle, and the initial discharge capacity was calculated from the discharge capacity of the third cycle. Here, 1C represents the current value for discharging the standard capacity of the battery for one hour, and for example, 0.2C represents one-fifth of that current value. After performing CC / CV charging (0.1C cut) to 4.4V again, high-temperature storage was performed at 65°C for 36 hours. After sufficiently cooling the battery, the volume was measured by the Archimedes method, and the amount of gas generated was calculated from the change in volume before and after storage. Next, the remaining capacity after high-temperature storage was measured by discharging to 3V at 0.2C at 25℃, and the ratio of the remaining capacity to the initial discharge capacity was calculated and set as the storage capacity retention rate (%).

[1026] (Remaining capacity) / (Initial discharge capacity) × 100 = Retention capacity retention rate (%)

[1027] <IV 저항의 평가>

[1028] The battery, for which the initial discharge capacity evaluation was completed, was charged at 25°C with a constant current of 0.2C to half the initial discharge capacity. It was then discharged at 25°C with a constant current of 2.0C, and the voltage at 10 seconds was measured. The resistance was calculated from the voltage drop during discharge and was set as the IV resistance. The resistance increase rate (%) was calculated from the resistance before and after high-temperature storage.

[1029] (Resistance after high-temperature storage) / (Resistance before high-temperature storage) × 100 = Resistance increase rate (%)

[1030] <Measurement of the amount of transition metal leaching from the positive electrode>

[1031] After measuring the storage capacity, the cell was disassembled, and the negative electrode was cleaned with DMC to remove the transition metal precipitated on the negative electrode. The amount of transition metal leached was determined by quantifying Ni in the transition metal-containing DMC solution using ICP emission analysis. Additionally, the amount of Ni leached from the positive electrode is assumed to be the amount precipitated on the negative electrode. The results are shown in Table 1.

[1032] (Thickness of the coating layer after drying)

[1033] The thickness of the coating layer after drying was calculated from the weight of the fluorine polymer in the protective film-forming composition and the thickness of the coating layer before drying.

[1034] (Density of the coating layer after drying)

[1035] The weight was calculated from the change in weight of the coating layer before and after drying, and the density of the coating layer after drying was calculated by dividing it by the volume of the coating layer after drying.

[1036]

[1037] (Examples 18 to 26, Comparative Examples 7 to 10)

[1038] (Coating on Li metal)

[1039] A protective film-forming composition was obtained by dissolving 8 parts by weight of various fluorine polymers in N-methyl-2-pyrrolidone (NMP), a solvent.

[1040] The above protective film-forming composition was coated onto a lithium metal thin film (thickness: about 15 μm) with a doctor blade to a thickness of about 8 μm. The coated product was dried at about 25°C and then heat-treated under vacuum at about 40°C to produce a lithium negative electrode with a protective film formed on the lithium metal. The electrode was fabricated by cutting it into a size of 20 mm × 20 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 / cm³.

[1041] Separately, LiNi0 . 8Mn0 . 1Co0 . A positive electrode composition was obtained by mixing LiCoO2, a conductive agent (Super-P, Timcal Ltd.), polyvinylidene fluoride (PVdF), and NMP. In the positive electrode composition, the mixing weight ratio of LiCoO2, the conductive agent, and PVDF is 97.5:1.25:1.25.

[1042] The above positive electrode composition was coated onto 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 produce an electrode.

[1043] A laminated cell was manufactured by interposing a polyethylene / polypropylene separator between the positive electrode obtained by the above process and the lithium metal negative electrode. Here, various electrolytes were obtained between the positive and negative electrodes from combinations of Li salts and solvents listed in Table 2.

[1044] High-temperature preservation characteristics evaluation test

[1045] The coin cell manufactured above was charged with a constant current-constant voltage (hereinafter referred to as CC / CV charging) (cut at 0.1C) to 4.3V at 25°C with a current equivalent to 0.2C, and then discharged to 3V with a constant current of 0.2C. This was considered one cycle, and the initial discharge capacity was calculated from the discharge capacity of the third cycle. Here, 1C represents the current value for discharging the standard capacity of the battery for one hour, and for example, 0.2C represents one-fifth of that current value. After performing CC / CV charging (cut at 0.1C) to 4.3V again, high-temperature storage was performed at 45°C for 48 hours. After sufficiently cooling the battery, the volume was measured by the Archimedes method, and the amount of gas generated was calculated from the change in volume before and after storage. Next, the remaining capacity after high-temperature storage was measured by discharging to 3V at 0.2C at 25℃, and the ratio of the remaining capacity to the initial discharge capacity was calculated and set as the storage capacity retention rate (%).

[1046] (Remaining capacity) / (Initial discharge capacity) × 100 = Retention capacity retention rate (%)

[1047] <IV 저항의 평가>

[1048] The battery, for which the initial discharge capacity evaluation was completed, was charged at 25°C with a constant current of 0.2C to half the initial discharge capacity. It was then discharged at 25°C with a constant current of 2.0C, and the voltage at 10 seconds was measured. The resistance was calculated from the voltage drop during discharge and was set as the IV resistance. The resistance increase rate (%) was calculated from the resistance before and after high-temperature storage.

[1049] (Resistance after high-temperature storage) / (Resistance before high-temperature storage) × 100 = Resistance increase rate (%)

[1050] <Measurement of the amount of transition metal leaching from the positive electrode>

[1051] After measuring the storage capacity, the cell was disassembled, and the negative electrode was cleaned with DMC to remove the transition metal precipitated on the negative electrode. The amount of transition metal leached was determined by quantifying Mn in the transition metal-containing DMC solution using ICP emission analysis. Additionally, the amount of Mn leached from the positive electrode is assumed to be the amount precipitated on the negative electrode. The results are shown in Table 2.

[1052] (Thickness of the coating layer after drying)

[1053] The thickness of the coating layer after drying was calculated from the weight part of the fluorine polymer in the protective film-forming composition and the thickness of the coating layer on the lithium metal foil.

[1054] (Density of the coating layer after drying)

[1055] The weight was calculated from the change in weight of the coating layer before and after drying, and the density of the coating layer after drying was calculated by dividing it by the volume of the coating layer after drying.

[1056]

[1057] From the results of Tables 1 and 2, it can be determined that the secondary battery of the present disclosure has excellent effects in terms of capacity retention rate, gas generation amount, resistance increase rate, Mn leaching amount, and Ni leaching amount, and that the deterioration of the negative electrode is suppressed, thereby obtaining the effect of improving battery life. Industrial applicability

[1058] The secondary battery of the present disclosure can be used as various general secondary batteries.

Claims

Claim 1 A secondary battery having a negative electrode having a fluorine polymer 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, and the fluorine polymer is a copolymer having a vinylidene fluoride unit (A) and a constituent unit (B) derived from 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 is characterized by containing a fluorinated ether. During the meal, Rf 1 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and the fluorinated alkyl group and the fluorinated alkoxy group may both include an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more. Rf 2 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and when the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms. During the meal, 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 with a molecular weight of 500 or less, in which a single bond or main chain consists of 1 to 20 atoms. Y represents an inorganic cation or an organic cation. Claim 2 In claim 1, the copolymer is a secondary battery having a vinylidene fluoride content of 30 to 99.5 mol% with respect to the total monomer unit. Claim 3 A secondary battery according to claim 1 or 2, wherein the fluorinated ether is a compound represented by the following general formula (5). (R is an alkyl group containing or not containing an ether group, or a fluorinated alkyl group containing or not containing an ether group) Claim 4 In paragraph 3, the compound represented by the above general formula (5) is at least one compound selected from the group consisting of compounds represented by the following general formula, a secondary battery. Claim 5 A secondary battery having a negative electrode comprising a laminate in which a fluorine polymer is directly laminated on a current collector, wherein the fluorine polymer is a copolymer having a vinylidene fluoride unit (A) and a constituent unit (B) derived from 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 is characterized by containing a fluorinated ether. During the meal, Rf 1 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and the fluorinated alkyl group and the fluorinated alkoxy group may both include an oxygen atom (-O-) between carbon atoms when the number of carbon atoms is 2 or more. Rf 2 The group is a straight-chain or branched fluoroalkyl group or a fluorinated alkoxy group having 1 to 12 carbon atoms, and when the fluorinated alkyl group and the fluorinated alkoxy group both have 2 or more carbon atoms, they may include an oxygen atom (-O-) between carbon-carbon atoms. During the meal, 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 with a molecular weight of 500 or less, in which a single bond or main chain consists of 1 to 20 atoms. Y represents an inorganic cation or an organic cation. Claim 6 In claim 5, the copolymer is a secondary battery having a vinylidene fluoride content of 30 to 99.5 mol% with respect to the total monomer unit. Claim 7 A secondary battery according to claim 5 or 6, wherein the fluorinated ether is a compound represented by the following general formula (5). (R is an alkyl group containing or not containing an ether group, or a fluorinated alkyl group containing or not containing an ether group) Claim 8 In claim 7, the compound represented by the above general formula (5) is at least one compound selected from the group consisting of compounds represented by the following general formula, a secondary battery.

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