Electrolyte solution, electrochemical device, secondary battery, and lithium ion secondary battery

Abstract

The purpose of the present disclosure is to provide an electrolyte solution with which an electrochemical device having excellent battery characteristics can be obtained even when a negative electrode having a material containing an alkali metal is used. The present disclosure is an electrolyte solution for a battery provided with a negative electrode having a material containing an alkali metal, the electrolyte solution containing a solvent containing a compound (1) represented by general formula (1): # imgabs0 # (1) (in the formula, R101 and R102 are each independently a non-fluorinated alkyl group having 1-3 carbon atoms, and R103 to R106 are each independently a hydrogen atom or a halogen atom. (In the formula, at least one of R103-R106 represents a halogen atom. ).

Description

Technical Field

[0001] The present disclosure relates to an electrolyte, an electrochemical device, a secondary battery, and a lithium-ion secondary battery. Background Art

[0002] With the recent trend toward lighter and smaller electrical products, the development of electrochemical devices such as lithium-ion secondary batteries with high energy density is advancing. Furthermore, as the application areas of these electrochemical devices expand, there is a desire for improved performance. Especially with the future use of lithium-ion secondary batteries in automotive applications, improving battery performance is becoming increasingly important.

[0003] Patent Document 1 describes the use of a battery having a lithium metal negative electrode comprising the formula I:R 1 -OR 2 -OR 3 (R 1 and R 3 is a fluoroalkyl group, R 2 An electrolyte of a fluorinated diether represented by (an alkyl group which may be fluorinated).

[0004] Prior art literature Patent Literature Patent Document 1: International Publication No. 2022 / 128233 Summary of the Invention Technical problem to be solved by the invention When an alkali metal is used for a negative electrode, there is a problem that dendrites of the alkali metal are formed on the negative electrode, which easily degrades battery characteristics.

[0005] An object of the present disclosure is to provide an electrolyte solution capable of obtaining an electrochemical device having excellent battery characteristics even when a negative electrode having a material containing an alkali metal is used.

[0006] Technical solutions to technical problems The present disclosure (1) is an electrolyte for a battery, wherein the negative electrode of the battery comprises a material containing an alkali metal, and the electrolyte comprises a solvent, wherein the solvent comprises the following general formula (1): [Chemistry 1] (Where R 101 and R 102 are independently non-fluorinated alkyl groups having 1 to 3 carbon atoms, R 103 ~R 106 are independently hydrogen atoms or halogen atoms. 103 ~R 106 At least one of the atoms is a halogen atom. ) is a compound (1).

[0007] The present disclosure (2) is the electrolyte solution according to the present disclosure (1), wherein the compound (1) is at least one selected from the group consisting of compounds represented by the following formulae.

[0008] [Chemistry 2] The present disclosure (3) is the electrolyte solution according to the present disclosure (1) or (2), wherein the content of the compound (1) is 0.01 to 80% by volume relative to the solvent.

[0009] The present disclosure (4) is an electrolyte solution in combination with any one of the present disclosures (1) to (3), wherein the alkali metal is at least one selected from lithium, sodium, and potassium.

[0010] The present disclosure (5) is an electrochemical device comprising an electrolyte solution in any combination with any one of the present disclosures (1) to (4).

[0011] The present disclosure (6) is a secondary battery comprising an electrolyte solution in any combination with any one of the present disclosures (1) to (4).

[0012] The present disclosure (7) is a lithium ion secondary battery comprising an electrolyte solution in any combination with any one of the present disclosures (1) to (4).

[0013] Effects of the Invention According to the present disclosure, it is possible to provide an electrolyte solution capable of obtaining an electrochemical device having excellent battery characteristics even when a negative electrode having a material containing an alkali metal is used. DETAILED DESCRIPTION

[0014] Hereinafter, the present disclosure will be described in detail.

[0015] The present disclosure relates to an electrolyte for a battery, wherein the negative electrode of the battery comprises a material containing an alkali metal, and the electrolyte comprises a solvent, wherein the solvent comprises the following general formula (1): [Chemistry 3] (Where R 101 and R 102 are independently non-fluorinated alkyl groups having 1 to 3 carbon atoms, R 103 ~R 106 are independently hydrogen atoms or halogen atoms. 103 ~R 106 At least one of them is a halogen atom.) The compound (1) shown.

[0016] The electrolyte solution disclosed herein can improve battery characteristics (eg, cycle characteristics, high-temperature storage characteristics) of electrochemical devices such as alkali metal ion secondary batteries using a negative electrode having a material containing an alkali metal, because the solvent contains the compound (1).

[0017] The electrolyte disclosed in the present invention can also improve the dissolution and precipitation performance of alkali metals.

[0018] Compound (1) is represented by the general formula (1): [Chemistry 4] .

[0019] In the general formula (1), R 101 and R 102 Each of the non-fluorinated alkyl groups is independently a non-fluorinated alkyl group having 1 to 3 carbon atoms. The non-fluorinated alkyl group preferably has 2 or less carbon atoms, more preferably 1 carbon atom.

[0020] Examples of the non-fluorinated alkyl group include a methyl group (CH 3 ), an ethyl group (CH 3 CH 2 ), a propyl group (CH 3 CH 2 CH 2 ), and an isopropyl group ((CH 3 ) 2 CH). Preferred are a methyl group and an ethyl group, and more preferred is a methyl group.

[0021] In the general formula (1), R 103 ~R 106 are independently a hydrogen atom or a halogen atom, R 103 ~R 106 At least one of them is a halogen atom. As the number of halogens increases, the acidity increases, which can further improve the battery characteristics. Therefore, it is preferred that R 103 ~R 106 At least two of them are halogen atoms, more preferably R 103 ~R 106 At least three of them are halogen atoms, and most preferably R 103 ~R 106 All are halogen atoms.

[0022] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. A fluorine atom and a chlorine atom are preferred, and a fluorine atom is more preferred.

[0023] Examples of the compound (1) include compounds represented by the following formula.

[0024] [Chemistry 5] Among them, the compound (1) is preferably a compound represented by the following formula.

[0025] [Chemistry 6] As compound (1), a compound represented by the following formula is more preferred.

[0026] [Chemistry 7] As compound (1), the compound represented by the following formula is most preferred.

[0027] [Chemistry 8] The compound (1) may be used alone or in combination of two or more.

[0028] In the electrolyte solution of the present disclosure, the content of compound (1) is preferably 0.01 to 80% by volume relative to the solvent. By setting the content of compound (1) within the above range, the battery characteristics of the electrochemical device and the elution and deposition performance of alkali metals can be further improved.

[0029] The content of compound (1) is more preferably 0.1% by volume or more, further preferably 1.0% by volume or more, further more preferably 5.0% by volume or more, further more preferably 10% by volume or more, further more preferably 20% by volume or more, further more preferably 30% by volume or more, particularly preferably 35% by volume or more, and most preferably 40% by volume or more, and more preferably 70% by volume or less, further preferably 60% by volume or less, particularly preferably 50% by volume or less, and most preferably 45% by volume or less, relative to the above-mentioned solvent.

[0030] The above-mentioned solvent contains compound (1) and preferably further contains at least one selected from carbonate esters and carboxylic acid esters.

[0031] The carbonate esters may be cyclic carbonate esters or chain carbonate esters.

[0032] The cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0033] Examples of the non-fluorinated cyclic carbonate include non-fluorinated saturated cyclic carbonates, preferably non-fluorinated saturated alkylene carbonates having an alkylene group having 2 to 6 carbon atoms, and more preferably non-fluorinated saturated alkylene carbonates having an alkylene group having 2 to 4 carbon atoms.

[0034] Among them, as the above-mentioned non-fluorinated saturated cyclic carbonate, from the viewpoint of high dielectric constant and suitable viscosity, it is preferably at least one selected from 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.

[0035] The above-mentioned non-fluorinated saturated cyclic carbonate may be used alone or in combination of two or more in any ratio.

[0036] When the non-fluorinated saturated cyclic carbonate is contained, the content of the non-fluorinated saturated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume based on the solvent.

[0037] The fluorinated cyclic carbonate is a fluorine-containing cyclic carbonate. A solvent containing the fluorinated cyclic carbonate can be preferably used even at high voltage.

[0038] In this specification, "high voltage" refers to a voltage of 4.2 V or higher. The upper limit of the "high voltage" is preferably 5.5 V, and more preferably 5.4 V.

[0039] The fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0040] The fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom, and specifically, the following general formula (A) can be mentioned: [Chemistry 9] (Where X 1 ~X 4 are the same or different and represent -H, -CH3, -C2H5, -F, a fluoroalkyl group which may have an ether bond, or a fluoroalkoxy group which may have an ether bond. 1 ~X 4 At least one of them is -F, a fluoroalkyl group which may have an ether bond, or a fluoroalkoxy group which may have an ether bond. The above-mentioned fluoroalkyl group refers to -CF3, -CF2H, -CH2F, etc.

[0041] When the electrolyte solution of the present disclosure is used in a high-voltage lithium-ion secondary battery or the like, the electrolyte solution containing the fluorinated saturated cyclic carbonate has improved oxidation resistance, and stable and excellent charge and discharge characteristics can be obtained.

[0042] In addition, in this specification, an "ether bond" is a bond represented by -O-.

[0043] From the viewpoint of good dielectric constant and oxidation resistance, X is preferred. 1 ~X 4 One or two of them are -F, a fluoroalkyl group which may have an ether bond, or a fluoroalkoxy group which may have an ether bond.

[0044] From the perspective of being able to expect a decrease in viscosity at low temperatures, an increase in flash point, and even an improvement in the solubility of the electrolyte salt, X 1 ~X 4 Preferred are -H, -F, a fluoroalkyl group (a), a fluoroalkyl group having an ether bond (b), or a fluoroalkoxy group (c).

[0045] The fluoroalkyl group (a) is a group obtained by replacing at least one hydrogen atom of an alkyl group with a fluorine atom. The number of carbon atoms in the fluoroalkyl group (a) is preferably 1 to 20, more preferably 1 to 17, further preferably 1 to 7, and particularly preferably 1 to 5.

[0046] If the number of carbon atoms is too large, problems such as reduced low-temperature characteristics or reduced solubility of the electrolyte salt may occur; if the number of carbon atoms is too small, reduced solubility of the electrolyte salt, reduced discharge efficiency, and even increased viscosity may be observed.

[0047] Among the fluoroalkyl groups (a), examples of the fluoroalkyl group having 1 carbon atom include CFH2-, CF2H-, and CF3-. In particular, CF2H- or CF3- is preferred in terms of high-temperature storage characteristics, and CF3- is most preferred.

[0048] Among the fluoroalkyl groups (a), the group having 2 or more carbon atoms preferably includes the following general formula (a-1) from the viewpoint of good solubility of the electrolyte salt: R a1 -R a2 - (a-1) (Where R a1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom; R a2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; wherein R a1 and R a2 At least one of them has a fluorine atom. ) is a fluorinated alkyl group represented by.

[0049] It should be noted that R a1 and R a2 It may also contain atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0050] R a1 It is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. a1 , preferably a linear or branched alkyl group having 1 to 16 carbon atoms. a1 The number of carbon atoms in the alkyl group is more preferably 1 to 6, and even more preferably 1 to 3.

[0051] As R a1Specifically, examples of the linear or branched alkyl group include CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-, [Chemistry 10] wait.

[0052] In addition, in R a1 In the case of a linear alkyl group having a fluorine atom, examples include: CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2CH2-, CF3CF2CH2CH2 CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2 CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2C F2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3 CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2C H2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HFCClCF2CFClCF2CH2-, etc.

[0053] In addition, in Ra1 In the case of a branched alkyl group having a fluorine atom, preferably: [Chemistry 11] [Chemistry 12] However, if there are side chains such as CH3- and CF3-, the viscosity tends to be high, so the number of side chains is preferably small (1) or zero.

[0054] R a2 It is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom. a2 It may be linear or branched. Some examples of the minimum structural units constituting such linear or branched alkylene groups are shown below. a2 They are composed of them individually or in combination.

[0055] (i) The smallest linear structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2- (ii) Branched chain minimum structural unit: [Chemistry 13] Among the above examples, it is preferable to be composed of a structural unit that does not contain Cl, from the viewpoint of not causing a de-HCl reaction by a base and being more stable.

[0056] In R a2 In the case of a linear chain, it is composed only of the above-mentioned linear minimum structural unit, among which -CH2-, -CH2CH2- or -CF2- are preferred. From the viewpoint of further improving the solubility of the electrolyte salt, -CH2- or -CH2CH2- is more preferred.

[0057] In R a2 In the case of a branched chain, it is a group comprising at least one of the minimum structural units of the branched chain, and a preferred example thereof is the general formula: -(CX a X b )- (X a is H, F, CH3 or CF3; X b is CH3 or CF3. b In the case of CF3, X a These units can further improve the solubility of the electrolyte salt.

[0058] Preferred fluoroalkyl groups (a) include CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CHF-, CH3CF2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-, [Chemistry 14] [Chemistry 15] wait.

[0059] The fluoroalkyl group (b) having an ether bond is a group in which at least one of the hydrogen atoms of the alkyl group having an ether bond is replaced by a fluorine atom. The number of carbon atoms in the fluoroalkyl group (b) having an ether bond is preferably 2 to 17. If the number of carbon atoms is too large, the viscosity of the fluorinated saturated cyclic carbonate becomes higher; in addition, due to the increase in the number of fluorinated groups, a decrease in the solubility of the electrolyte salt caused by a decrease in the dielectric constant and a decrease in the compatibility with other solvents are sometimes observed. From this viewpoint, the number of carbon atoms in the fluoroalkyl group (b) having an ether bond is more preferably 2 to 10, and even more preferably 2 to 7.

[0060] The alkylene group constituting the ether portion of the fluoroalkyl group (b) having an ether bond may be a linear or branched alkylene group. Some examples of the minimum structural unit constituting such a linear or branched alkylene group are shown below.

[0061] (i) The smallest linear structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2- (ii) Branched chain minimum structural unit: [Chemistry 16] The alkylene group may be composed of these minimum structural units alone, or may be composed of linear (i) groups, branched (ii) groups, or a combination of linear (i) and branched (ii) groups. Preferred specific examples are described below.

[0062] Among the above examples, it is preferable to be composed of a structural unit that does not contain Cl, from the viewpoint of not causing a de-HCl reaction by a base and being more stable.

[0063] More preferred examples of the fluoroalkyl group (b) having an ether bond include those represented by the general formula (b-1): R 3 -(OR 4 ) n1 - (b-1) (Where R 3 is an alkyl group which may have a fluorine atom and preferably has 1 to 6 carbon atoms; R 4 is an alkylene group which may have a fluorine atom and preferably has 1 to 4 carbon atoms; n1 is an integer of 1 to 3; wherein R 3 and R 4 At least one of which has a fluorine atom).

[0064] As R 3 and R 4 The following groups can be exemplified, and they can be appropriately combined to constitute the fluorinated alkyl group (b) having an ether bond represented by the general formula (b-1), but the group is not limited to these groups.

[0065] (1) As R 3 , preferably the general formula: X c 3C-(R 5 ) n2 - (3 X c Same or different, all H or F; R 5 is an alkylene group having 1 to 5 carbon atoms and optionally containing a fluorine atom; n2 is an alkyl group represented by 0 or 1).

[0066] When n2 is 0, as R 3 , examples include CH3-, CF3-, HCF2- and H2CF-.

[0067] As a specific example when n2 is 1, as R 3It is a straight-chain group, and examples thereof include CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2CH2-, CF3CF2CH2CH2 -, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3C F2CF2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2C F2CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2CF2CH2CH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, CH3CF2-, CH3CH2-, CH3CF2CH2-, CH3CF2CF2-, CH3CH2 CH2-, CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CH2CH2CH2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CH2CF2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, etc.

[0068] As n2 is 1, and R 3 The branched group includes: [Chemistry 17] wait.

[0069] Among them, if there is a side chain such as CH3- or CF3-, the viscosity tends to be high, so R is more preferred. 3 It is a straight-chain group.

[0070] (2) In the above general formula (b-1), -(OR 4 ) n1 -, n1 is an integer of 1 to 3, preferably 1 or 2. It should be noted that when n1 = 2 or 3, R 4 Can be the same or different.

[0071] As R 4 Preferred specific examples include the following linear or branched groups.

[0072] Examples of the straight-chain group include -CH2-, -CHF-, -CF2-, -CH2CH2-, -CF2CH2-, -CF2CF2-, -CH2CF2-, -CH2CH2CH2-, -CH2CH2CF2-, -CH2CF2CH2-, -CF2CH2CH2-, -CF2CF2CH2-, -CF2CH2CF2-, -CF2CH2CF2-, -CF2CH2CF2-, and the like.

[0073] Examples of branched groups include: [Chemistry 18] wait.

[0074] The fluoroalkoxy group (c) is a group in which at least one of the hydrogen atoms in an alkoxy group is replaced by a fluorine atom. The fluoroalkoxy group (c) preferably has 1 to 17 carbon atoms, and more preferably has 1 to 6 carbon atoms.

[0075] As the fluoroalkoxy group (c), the general formula: X d 3C-(R 6 ) n3 -O- (3 X d Same or different, all H or F; R 6 It is preferably an alkylene group having 1 to 5 carbon atoms and optionally containing a fluorine atom; n3 is 0 or 1; wherein 3 X d At least one of them contains a fluorine atom).

[0076] Specific examples of the fluoroalkoxy group (c) include: a1 The exemplified fluoroalkoxy group is a fluoroalkoxy group in which an oxygen atom is bonded to the terminal of an alkyl group.

[0077] The fluorine content of the fluoroalkyl (a) in the above-mentioned fluorinated saturated cyclic carbonate, the fluoroalkyl (b) with ether bond and fluoroalkoxy (c) is preferably more than 10 mass %.If fluorine content is too low, then may not fully obtain the effect of the viscosity reducing low temperatures, the effect of raising flash-point.From this viewpoint, above-mentioned fluorine content is more preferably more than 12 mass %, further preferably more than 15 mass %.The upper limit is generally 76 mass %.

[0078] The fluorine content of the fluoroalkyl group (a), the fluoroalkyl group having an ether bond (b), and the fluoroalkoxy group (c) is a value calculated based on the structural formula of each group according to {(number of fluorine atoms × 19) / formula weight of each group} × 100 (%).

[0079] Furthermore, from the viewpoint of good dielectric constant and oxidation resistance, the fluorine content of the fluorinated saturated cyclic carbonate as a whole is preferably 10% by mass or more, more preferably 15% by mass or more, with the upper limit usually being 76% by mass.

[0080] The fluorine content of the fluorinated saturated cyclic carbonate is a value calculated based on the structural formula of the fluorinated saturated cyclic carbonate as {(number of fluorine atoms×19) / molecular weight of the fluorinated saturated cyclic carbonate}×100 (%).

[0081] Specific examples of the fluorinated saturated cyclic carbonate include the following.

[0082] As X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate wherein at least one of the groups is -F include: [Chemistry 19] These compounds have high withstand voltage and good solubility of electrolyte salts.

[0083] In addition, you can also use [Chemistry 20] wait.

[0084] As X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate wherein at least one of the fluorinated alkyl groups (a) is a fluorinated alkyl group and all the others are -H include: [Chemistry 21] [Chemistry 22] [Chemistry 23] wait.

[0085] As X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate wherein at least one of the fluorinated alkyl groups (b) or the fluorinated alkoxy group (c) is a fluorinated alkyl group having an ether bond, and the rest are all -H groups include: [Chemistry 24] [Chemistry 25] [Chemistry 26] [Chemistry 27] [Chemistry 28] [Chemistry 29] wait.

[0086] Among them, the fluorinated saturated cyclic carbonate is preferably any one of the following compounds.

[0087] [Chemistry 30] [Chemistry 31] Examples of the fluorinated saturated cyclic carbonates include trans-4,5-difluoro-1,3-dioxolane-2-one, 5-(1,1-difluoroethyl)-4,4-difluoro-1,3-dioxolane-2-one, 4-methylene-1,3-dioxolane-2-one, 4-methyl-5-trifluoromethyl-1,3-dioxolane-2-one, 4-ethyl-5-fluoro-1,3-dioxolane-2-one, 4-ethyl-5,5-difluoro-1,3-dioxolane-2-one, and 4-methyl-5-trifluoromethyl-1,3-dioxolane-2-one. ,3-dioxolane-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolane-2-one, 4-ethyl-4,5,5-trifluoro-1,3-dioxolane-2-one, 4,4-difluoro-5-methyl-1,3-dioxolane-2-one, 4-fluoro-5-methyl-1,3-dioxolane-2-one, 4-fluoro-5-trifluoromethyl-1,3-dioxolane-2-one, 4,4-difluoro-1,3-dioxolane-2-one, etc.

[0088] Among these fluorinated saturated cyclic carbonates, more preferred are fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethylethylene carbonate (3,3,3-trifluoropropylene carbonate), and 2,2,3,3,3-pentafluoropropylethylene carbonate.

[0089] The fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom, and is preferably a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond. Specifically, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, etc. can be mentioned.

[0090] The above-mentioned fluorinated cyclic carbonates may be used alone or in combination of two or more in any combination and ratio.

[0091] When the fluorinated cyclic carbonate is contained, the content of the fluorinated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume relative to the solvent.

[0092] The aforementioned chain carbonate may be a non-fluorinated chain carbonate or a fluorinated chain carbonate.

[0093] Examples of the non-fluorinated chain carbonate include 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 hydrocarbon chain carbonates such as ethylphenyl carbonate. Among these, at least one selected from ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate is preferred.

[0094] The non-fluorinated chain carbonates may be used alone or in combination of two or more in any proportion.

[0095] When the non-fluorinated chain carbonate is contained, the content of the non-fluorinated chain carbonate is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume relative to the solvent.

[0096] The fluorinated chain carbonate is a chain carbonate having a fluorine atom. A solvent containing a fluorinated chain carbonate can be preferably used even at a high voltage.

[0097] Examples of the fluorinated chain carbonate include those represented by the general formula (B): Rf 2 OCOOR 7 (B) (Where Rf 2 is a fluoroalkyl group having 1 to 7 carbon atoms, R 7 It is an alkyl group having 1 to 7 carbon atoms and optionally containing a fluorine atom. ) is a compound represented by.

[0098] Rf 2 is a fluoroalkyl group having 1 to 7 carbon atoms, R 7 It is an alkyl group having 1 to 7 carbon atoms and optionally containing a fluorine atom.

[0099] The fluoroalkyl group is a group in which at least one hydrogen atom of an alkyl group is replaced by a fluorine atom. 7 In the case of an alkyl group containing a fluorine atom, it is a fluorinated alkyl group.

[0100] From the perspective of low viscosity, Rf 2 and R 7 The number of carbon atoms in is preferably 1-7, more preferably 1-2.

[0101] If the number of carbon atoms is too large, it may sometimes cause problems such as reduced low-temperature characteristics or reduced solubility of the electrolyte salt; if the number of carbon atoms is too small, it may sometimes cause reduced solubility of the electrolyte salt, reduced discharge efficiency, or even increased viscosity.

[0102] Examples of the fluoroalkyl group having 1 carbon atom include CFH2-, CF2H-, and CF3-. In particular, CFH2- or CF3- is preferred in terms of high-temperature storage characteristics.

[0103] As the fluoroalkyl group having 2 or more carbon atoms, from the viewpoint of good solubility of the electrolyte salt, preferably, the following general formula (d-1) can be exemplified: R d1 -R d2 - (d-1) (Where R d1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom; R d2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; wherein R d1 and R d2 At least one of them has a fluorine atom).

[0104] It should be noted that R d1and R d2 It may also contain atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0105] R d1 It is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. d1 , preferably a linear or branched alkyl group having 1 to 6 carbon atoms. d1 The number of carbon atoms is more preferably 1 to 3.

[0106] As R d1 Specifically, examples of the linear or branched alkyl group include CH3-, CF3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-, [Chemistry 32] wait.

[0107] In addition, in R d1In the case of a linear alkyl group having a fluorine atom, examples include: CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2CH2-, CF3CF2CH2CH2 CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2 CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2C F2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3 CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2C H2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HFCClCF2CFClCF2CH2-, etc.

[0108] In addition, in R d1 In the case of a branched alkyl group having a fluorine atom, preferably: [Chemistry 33] [Chemistry 34] However, if there are side chains such as CH3- and CF3-, the viscosity tends to be high, so the number of side chains is preferably small (1) or zero.

[0109] R d2 It is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom. d2 It may be linear or branched. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below. d2 They are composed of them individually or in combination.

[0110] (i) The smallest linear structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2- (ii) Branched chain minimum structural unit: [Chemistry 35] Among the above examples, it is preferable to be composed of a structural unit that does not contain Cl, from the viewpoint of not causing a de-HCl reaction by a base and being more stable.

[0111] In R d2 In the case of a linear group, it is a group consisting only of the above-mentioned linear minimum structural unit, among which -CH2-, -CH2CH2- or -CF2- are preferred. From the viewpoint of further improving the solubility of the electrolyte salt, -CH2- or -CH2CH2- is more preferred.

[0112] In R d2 In the case of a branched chain, it is a group comprising at least one of the minimum structural units of the branched chain, and a preferred example thereof is the general formula: -(CX a X b )- (X a is H, F, CH3 or CF3; X b is CH3 or CF3. b In the case of CF3, X a These groups can further improve the solubility of the electrolyte salt.

[0113] Specific examples of preferred fluoroalkyl groups include CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CH2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-, [Chemistry 36] [Chemistry 37] wait.

[0114] Among them, as Rf 2 and R 7 The fluoroalkyl groups are preferably CF3-, CF3CF2-, (CF3)2CH-, CF3CH2-, C2F5CH2-, CF3CF2CH2-, HCF2CF2CH2-, CF3CFHCF2CH2-, CFH2-, and CF2H-. From the viewpoint of high flame retardancy, good rate characteristics, and good oxidation resistance, CF3CH2-, CF3CF2CH2-, HCF2CF2CH2-, CFH2-, and CF2H- are more preferred.

[0115] In R 7 In the case of an alkyl group not containing a fluorine atom, it is an alkyl group having 1 to 7 carbon atoms. 7 The number of carbon atoms is preferably 1 to 4, more preferably 1 to 3.

[0116] Examples of the alkyl group not containing a fluorine atom include CH3-, CH3CH2-, (CH3)2CH-, and C3H7-. Among them, CH3- and CH3CH2- are preferred because they have low viscosity and good rate characteristics.

[0117] The fluorine content of the fluorinated linear carbonate is preferably 15 to 70% by mass. If the fluorine content is within the above range, compatibility with the solvent and the solubility of the salt can be maintained. The fluorine content is more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 35% by mass or more, more preferably 60% by mass or less, and further preferably 50% by mass or less.

[0118] It should be noted that in this disclosure, the fluorine content is based on the structural formula of the above-mentioned fluorinated chain carbonate. {(number of fluorine atoms × 19) / molecular weight of fluorinated chain carbonate} × 100(%) Calculated value.

[0119] As the fluorinated chain carbonate, any one of the following compounds is preferred from the viewpoint of low viscosity.

[0120] [Chemistry 38] As the fluorinated chain carbonate, methyl 2,2,2-trifluoroethyl carbonate (F3CH2COC(=O)OCH3) is particularly preferred.

[0121] The above-mentioned fluorinated chain carbonates may be used alone or in combination of two or more in any combination and ratio.

[0122] When the fluorinated chain carbonate is contained, the content of the fluorinated chain carbonate is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume relative to the solvent.

[0123] The carboxylate ester may be a cyclic carboxylate ester or a chain carboxylate ester.

[0124] The cyclic carboxylate may be a non-fluorinated cyclic carboxylate or a fluorinated cyclic carboxylate.

[0125] Examples of the non-fluorinated cyclic carboxylic acid ester include non-fluorinated saturated cyclic carboxylic acid esters, and are preferably non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group having 2 to 4 carbon atoms.

[0126] Specific examples of the non-fluorinated saturated cyclic carboxylic acid ester having an alkylene group having 2 to 4 carbon atoms include: β -Propiolactone, c -Butyrolactone, e -caprolactone, δ-valerolactone, α methyl- c -Butyrolactone. c -Butyrolactone and Δ-valerolactone are particularly preferred from the viewpoint of increasing the degree of lithium ion dissociation and improving load characteristics.

[0127] The non-fluorinated saturated cyclic carboxylic acid esters may be used alone or in combination of two or more in any ratio.

[0128] When the non-fluorinated saturated cyclic carboxylic acid ester is contained, the content of the non-fluorinated saturated cyclic carboxylic acid ester is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, further preferably 1 to 60% by volume, particularly preferably 5 to 40% by volume, based on the solvent.

[0129] The chain carboxylate may be a non-fluorinated chain carboxylate or a fluorinated chain carboxylate. When the solvent contains the chain carboxylate, an increase in resistance of the electrolyte after high-temperature storage can be further suppressed.

[0130] Examples of the non-fluorinated chain carboxylic acid ester include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, tert-butyl propionate, tert-butyl butyrate, sec-butyl propionate, sec-butyl butyrate, n-butyl butyrate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl acetate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl acetate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl acetate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, sec-butyl acetate, tert-butyl formate, tert-butyl acetate ... ethyl 2-(dimethylphosphoryl)acetate, ethyl 2-(diethoxyphosphoryl)acetate, ethyl 2-(diethylphosphoryl)acetate, isopropyl propionate, isopropyl acetate, ethyl formate, 2-propynylethyl oxalate, isopropyl formate, isopropyl butyrate, isobutyl formate, isobutyl propionate, isobutyl butyrate, isobutyl acetate, etc.

[0131] Among them, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and ethyl propionate and propyl propionate are particularly preferred.

[0132] The non-fluorinated chain carboxylic acid esters may be used alone or in combination of two or more in any combination and ratio.

[0133] When the non-fluorinated chain carboxylic acid ester is contained, the content of the non-fluorinated chain carboxylic acid ester is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, further preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume relative to the solvent.

[0134] The fluorinated chain carboxylic acid ester is a chain carboxylic acid ester having a fluorine atom. A solvent containing the fluorinated chain carboxylic acid ester can be preferably used even at a high voltage.

[0135] As the fluorinated chain carboxylic acid ester, the following general formula is preferred from the viewpoint of good compatibility with other solvents and oxidation resistance: R 31 COOR 32 (Where R 31 and R 32 are independently an alkyl group having 1 to 4 carbon atoms and optionally containing a fluorine atom, R 31 and R 32 At least one of contains a fluorine atom. ) is a fluorinated chain carboxylic acid ester.

[0136] As R 31 and R 32, for example, the following can be cited: unfluorinated alkyl groups such as methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), n-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, -CH2CF(CF3)CF2H, -CH2CF(CF3)CFH2, -CH2CH(CF3)CF3, -CH2CH(CF2H)CF3, -CH2CH(CFH2)CF3, -CH2CH(CF3)CF2H,-CH2CH(CF3)CFH2, -CF2CH(CF3)CF3, -CF2CH(CF2H)CF3, -CF2CH(CFH2)CF3, -CF2CH(CF3)CF2H, -CF2CH(CF3)CFH2, -C(CF3)3, -C(CF2H)3, -C(CFH2)3 and other fluoroalkyl groups. Among them, methyl, ethyl, -CF3, -CF2H, -CF2CF3, -CH2CF3, -CH2CF2H, -CH2CFH2, -CH2CH2CF3, -CH2CF2CF3, -CH2CF2CF2H, -CH2CF2CFH2 are particularly preferred from the viewpoint of good compatibility with other solvents, viscosity and oxidation resistance.

[0137] Specific examples of the fluorinated chain carboxylic acid esters include CF3CH2C(=O)OCH3(methyl 3,3,3-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 trifluorobutyrate, and 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), 2,2,3,3,4,4,4-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, butyl 2,2-difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, methyl heptafluorobutyrate, etc., one or more thereof.

[0138] Among them, from the viewpoint of good compatibility with other solvents and rate characteristics, preferred are: 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, 2,2, 3,3,4,4,4-heptafluorobutyl ester, 4,4,4-trifluorobutyric acid methyl ester, 4,4,4-trifluorobutyric acid ethyl ester, 3,3,3-trifluoropropionic acid ethyl ester, 3,3,3-trifluoropropionic acid-3,3,3-trifluoropropyl ester, 3-(trifluoromethyl)butyric acid ethyl ester, 2,3,3,3-tetrafluoropropionic acid methyl ester, 2,2-difluorobutyl acetate, 2,2,3,3-tetrafluoropropionic acid methyl ester, 2-(trifluoromethyl)butyric acid ethyl ester 3,3,3-trifluoropropionate, methyl heptafluorobutyrate, more preferably CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CH3C(=O)OCH2CF3, particularly preferably HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CH3C(=O)OCH2CF3.

[0139] The above-mentioned fluorinated chain carboxylic acid esters may be used alone or in combination of two or more in any combination and ratio.

[0140] When the fluorinated chain carboxylic acid ester is contained, the content of the fluorinated chain carboxylic acid ester is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume relative to the solvent.

[0141] Above-mentioned solvent is preferably comprised at least a kind selected from above-mentioned cyclic carbonate, above-mentioned chain carbonate and above-mentioned chain carboxylate, more preferably comprises above-mentioned cyclic carbonate and at least a kind selected from above-mentioned chain carbonate and above-mentioned chain carboxylate.Above-mentioned cyclic carbonate is preferably saturated cyclic carbonate.

[0142] The electrolyte solution containing the solvent of the above composition can further improve the high-temperature storage characteristics and cycle characteristics of the electrochemical device.

[0143] In the case where the above-mentioned solvent comprises the above-mentioned cyclic carbonate and at least one selected from the above-mentioned chain carbonate and the above-mentioned chain carboxylic ester, the above-mentioned cyclic carbonate and at least one selected from the above-mentioned chain carbonate and the above-mentioned chain carboxylic ester are in total amount, preferably comprise 10~100 volume %, more preferably comprise 30~100 volume %, further preferably comprise 50~100 volume %.

[0144] Under the situation that above-mentioned solvent comprises above-mentioned cyclic carbonate and at least one being selected from above-mentioned linear carbonate and above-mentioned linear carboxylic ester, as above-mentioned cyclic carbonate and at least one volume ratio being selected from above-mentioned linear carbonate and above-mentioned linear carboxylic ester, preferably 5 / 95~95 / 5; More preferably more than 10 / 90, further preferably more than 15 / 85, particularly preferably more than 20 / 80; More preferably below 90 / 10, further preferably below 60 / 40, particularly preferably below 50 / 50.

[0145] In addition, above-mentioned solvent is also preferably comprised and is selected from above-mentioned non-fluorinated saturated cyclic carbonate, above-mentioned non-fluorinated chain carbonate and above-mentioned non-fluorinated chain carboxylic acid ester at least a kind, more preferably comprise above-mentioned non-fluorinated saturated cyclic carbonate and be selected from above-mentioned non-fluorinated chain carbonate and above-mentioned non-fluorinated chain carboxylic acid ester at least a kind.The electrolytic solution that contains the solvent of above-mentioned composition can suitably be used for the electrochemical device that uses under lower voltage.

[0146] In the case where the above-mentioned solvent comprises the above-mentioned non-fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned non-fluorinated chain carbonate and the above-mentioned non-fluorinated chain carboxylic ester, the above-mentioned non-fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned non-fluorinated chain carbonate and the above-mentioned non-fluorinated chain carboxylic ester are in total amount, preferably comprise 5~100 volume %, more preferably comprise 20~100 volume %, further preferably comprise 30~100 volume %.

[0147] When the above-mentioned electrolyte comprises the above-mentioned non-fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned non-fluorinated chain carbonate and the above-mentioned non-fluorinated chain carboxylic acid ester, the volume ratio of the above-mentioned non-fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned non-fluorinated chain carbonate and the above-mentioned non-fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5; more preferably 10 / 90 or more, further preferably 15 / 85 or more, particularly preferably 20 / 80 or more; more preferably 90 / 10 or less, further preferably 60 / 40 or less, particularly preferably 50 / 50 or less.

[0148] In addition, above-mentioned solvent is also preferably comprised at least a kind that is selected from above-mentioned fluorinated saturated cyclic carbonate, above-mentioned fluorinated chain carbonate and above-mentioned fluorinated chain carboxylic ester, more preferably comprised at least a kind that is selected from above-mentioned fluorinated saturated cyclic carbonate and above-mentioned fluorinated chain carboxylic ester.The electrolytic solution that contains the solvent of above-mentioned composition not only can be applicable to the electrochemical device that uses under lower voltage, also can be applicable to the electrochemical device that uses under higher voltage.

[0149] In the case where the above-mentioned solvent contains the above-mentioned fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned fluorinated chain carbonate and the above-mentioned fluorinated chain carboxylic ester, the above-mentioned fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned fluorinated chain carbonate and the above-mentioned fluorinated chain carboxylic ester are measured in total amount, preferably comprising 5 to 100 volume %, more preferably comprising 10 to 100 volume %, further preferably comprising 30 to 100 volume %.

[0150] In the case where the above-mentioned solvent comprises the above-mentioned fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned fluorinated chain carbonate and the above-mentioned fluorinated chain carboxylic ester, the volume ratio of the above-mentioned fluorinated saturated cyclic carbonate and at least one selected from the above-mentioned fluorinated chain carbonate and the above-mentioned fluorinated chain carboxylic ester is preferably 5 / 95 to 95 / 5; more preferably 10 / 90 or more, further preferably 15 / 85 or more, particularly preferably 20 / 80 or more; more preferably 90 / 10 or less, further preferably 60 / 40 or less, particularly preferably 50 / 50 or less.

[0151] In addition, ionic liquids can also be used as the above-mentioned solvents. "Ionic liquid" refers to a liquid composed of ions composed of a combination of organic cations and anions.

[0152] The organic cation is not particularly limited, and examples thereof include imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0153] There are no particular limitations on the anions that counteract these organic cations, and for example, PF6 anion, PF3(C2F5)3 anion, PF3(CF3)3 anion, BF4 anion, BF2(CF3)2 anion, BF3(CF3) anion, bisoxalatoborate anion, P(C2O4)F2 anion, Tf(trifluoromethanesulfonyl) anion, Nf(nonafluorobutanesulfonyl) anion, bis(fluorosulfonyl)imide anion, bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, dicyanamide anion, and halide anion can be used.

[0154] The above-mentioned solvent is preferably a non-aqueous solvent, and the electrolyte disclosed in the present invention is preferably a non-aqueous electrolyte.

[0155] The content of the solvent in the electrolyte solution is preferably 70 to 99.999% by mass, more preferably 80% by mass or more, and more preferably 92% by mass or less.

[0156] The electrolyte solution of the present disclosure may further contain a compound (2) represented by the following general formula (2).

[0157] General formula (2): [Chemistry 39] (Where A a+ is a metal ion, a hydrogen ion or an onium ion. a is an integer from 1 to 3, b is an integer from 1 to 3, p is b / a, n203 is an integer from 1 to 4, n201 is an integer from 0 to 8, n202 is 0 or 1, Z 201 A transition metal is an element of Group III, Group IV or Group V of the periodic table.

[0158] X 201 is O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (the alkylene group, the halogenated alkylene group, the arylene group, and the halogenated arylene group may have a substituent or a heteroatom in their structure. In addition, when n202 is 1 and n203 is 2 to 4, n203 X 201 can be bonded to each other).

[0159] L 201 is a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms (an alkylene group, a haloalkylene group, an arylene group, and a haloarylene group may have a substituent or a heteroatom in their structure. In addition, when n201 is 2 to 8, n201 L 201 may be bonded to each other to form a ring) or -Z 203 Y 203 .

[0160] Y 201 、Y 202 and Z 203 Each independently is O, S, NY 204 , hydrocarbon group or fluorinated hydrocarbon group. 203 and Y 204Each is independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (the alkyl group, the halogenated alkyl group, the aryl group, and the halogenated aryl group may have a substituent or a heteroatom in their structure. When there are multiple Y 203 or Y 204 In the case of , they may be bonded to each other to form a ring).

[0161] As A a＋ , examples include lithium ion, sodium ion, potassium ion, magnesium ion, calcium ion, barium ion, cesium ion, silver ion, zinc ion, copper ion, cobalt ion, iron ion, nickel ion, manganese ion, titanium ion, lead ion, chromium ion, vanadium ion, ruthenium ion, yttrium ion, lanthanide ion, actinide ion, tetrabutylammonium ion, tetraethylammonium ion, tetramethylammonium ion, triethylmethylammonium ion, triethylammonium ion, pyridinium ion, imidazolium ion, hydrogen ion, tetraethylphosphonium ion, tetramethylphosphonium ion, tetraphenylphosphonium ion, triphenylsulfonium ion, and triethylsulfonium ion.

[0162] In the case of electrochemical devices, A a＋ Preferred are lithium ions, sodium ions, magnesium ions, tetraalkylammonium ions, and hydrogen ions, and lithium ions are particularly preferred. a+ The valence a of the cation is an integer from 1 to 3. If it is greater than 3, the lattice energy increases, making it difficult to dissolve in the solvent. Therefore, when solubility is required, a valence of 1 is more preferred. The valence b of the anion is also an integer from 1 to 3, with 1 being particularly preferred. The constant p, which represents the ratio of the valences of the cation to the anion, is necessarily determined by the ratio of their valences, b / a.

[0163] Next, the ligand portion of the general formula (2) will be described. In this specification, the ligand portion of the general formula (2) and Z 201 The bonded organic or inorganic moiety is called a ligand.

[0164] Z 201 Preferred are Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf or Sb, more preferably Al, B or P.

[0165] X 201represents O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene groups and arylene groups may have substituents or heteroatoms in their structures. Specifically, instead of hydrogen on the alkylene group and the arylene group, there may be a halogen atom, a chain or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group, an acyl group, an amide group, or a hydroxyl group as a substituent. It may also be a structure in which nitrogen, sulfur, or oxygen is introduced to replace the carbon on the alkylene group and the arylene group. In addition, when n202 is 1 and n203 is 2 to 4, n203 X 201 As an example, ligands such as ethylenediaminetetraacetic acid can be mentioned.

[0166] L 201 represents a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms, or -Z 203 Y 203 (About Z 203 、Y 203 The alkyl and aryl groups are also related to X. 201 Similarly, the structure may have a substituent or a heteroatom. In addition, when n201 is 2 to 8, n201 L 201 They may be bonded to each other to form a ring. 201 , preferably a fluorine atom or a cyano group. This is because, in the case of a fluorine atom, the solubility and dissociation degree of the salt of the anionic compound are improved, which is accompanied by an increase in ionic conductivity. In addition, the oxidation resistance is improved, thereby suppressing the occurrence of side reactions.

[0167] Y 201 、Y 202 and Z 203 Each independently represents O, S, NY 204 , hydrocarbon group or fluorinated hydrocarbon group. 201 and Y 202 Preferably O, S or NY 204 , more preferably O. As a characteristic of compound (2), there is a 201 and Y 202 and Z 201 bonding, so these ligands are bound to Z 201 The chelate structure is formed. Through the chelation effect, the heat resistance, chemical stability and hydrolysis resistance of the compound are improved. The constant n2O2 in the ligand is 0 or 1, but in particular, when n2O2 is 0, the chelate ring is a five-membered ring, so the chelate effect is most strongly exerted, the stability is increased, and it is therefore preferred.

[0168] In this specification, a fluorinated hydrocarbon group is a group in which at least one hydrogen atom of a hydrocarbon group is replaced by a fluorine atom.

[0169] Y 203 and Y 204 Each of them is independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms. These alkyl and aryl groups may have a substituent or a heteroatom in their structure. In addition, in Y 203 or Y 204 When there are multiple ligands, they may be bonded to each other to form a ring.

[0170] Furthermore, the constant n203 related to the number of ligands is an integer of 1 to 4, preferably 1 or 2, and more preferably 2. Furthermore, the constant n201 related to the number of ligands is an integer of 0 to 8, preferably an integer of 0 to 4, and more preferably 0, 2, or 4. Furthermore, when n203 is 1, n201 is preferably 2, and when n203 is 2, n201 is preferably 0.

[0171] In the general formula (2), the alkyl group, the halogenated alkyl group, the aryl group, and the halogenated aryl group also include groups having other functional groups such as a branched chain, a hydroxyl group, and an ether bond.

[0172] Compound (2) preferably has the general formula: [Chemistry 40] (where A a+ 、a、b、p、n201、Z 201 and L 201 As described above), or a compound of the general formula: [Chemistry 41] (where A a+ 、a、b、p、n201、Z 201 and L 201 As described above).

[0173] Examples of compound (2) include lithium oxalatoborate salts, and the following formula is mentioned: [Chemistry 42] The lithium bis(oxalato)borate (LIBOB) shown in FIG. 1 has the following formula: [Chemistry 43] The lithium difluorooxalatoborate (LIDFOB) shown is of the following formula: [Chemistry 44] The lithium difluorooxalatophosphate (LIDFOP) shown in FIG. [Chemistry 45] The lithium tetrafluorooxalatophosphate (LITFOP) shown in FIG. [Chemistry 46] As shown in the lithium difluorobisoxalato phosphate, etc.

[0174] In addition, examples of compound (2) include dicarboxylic acid complex salts in which the central element of the complex is boron, such as 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.

[0175] In addition, examples of compound (2) include dicarboxylic acid complex salts in which the central element of the complex is phosphorus, such as 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, and lithium tetrafluoro(dimethylmalonato)phosphate.

[0176] In addition, examples of the compound (2) include dicarboxylic acid complex salts in which the central element of the complex is aluminum, such as LiAl(C2O4)2 and LiAlF2(C2O4).

[0177] Among them, lithium dioxalatoborate, lithium difluoro(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate are more preferably used from the viewpoint of easy availability and contribution to the formation of a stable film-like structure.

[0178] As the compound (2), lithium bisoxalatoborate is particularly preferred.

[0179] From the viewpoint of obtaining further excellent cycle characteristics, the content of compound (2) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and preferably 10% by mass or less, more preferably 3% by mass or less, relative to the solvent.

[0180] The electrolyte solution disclosed herein may not substantially contain Compound (2). Substantially not containing Compound (2) means that the content of Compound (2) is less than 0.01% by mass relative to the above-mentioned solvent. The content of Compound (2) may be less than 0.001% by mass relative to the above-mentioned solvent.

[0181] The electrolyte solution disclosed herein preferably further comprises an electrolyte salt (excluding compound (2)). As the electrolyte salt, in addition to alkali metal salts, ammonium salts, and metal salts other than alkali metal salts (e.g., light metal salts other than alkali metal salts), any salt that can be used in an electrolyte solution, such as a liquid salt (ionic liquid), an inorganic polymer salt, or an organic polymer salt, can be used.

[0182] Examples of electrolyte salts for electrochemical device electrolytes include the following compounds: MPF6, MBF4, MClO4, MAsF6, MB(C6H5)4, MCH3SO3, MCF3SO3, MAlCl4, M2SiF6, MCl, and MBr. (In the formula, M is at least one metal selected from Li, Na, and K, preferably one metal selected from Li, Na, and K, and more preferably Li or Na.) By using these alkali metal salts, excellent battery capacity, cycle characteristics, and storage characteristics can be obtained. Among them, at least one selected from MPF6, MBF4, MClO4, and MAsF6 is preferred, with MPF6 being more preferred. By using these alkali metal salts, the internal resistance can be further reduced, and a higher effect can be obtained.

[0183] As the electrolyte salt of the electrolyte solution for lithium ion secondary batteries, a lithium salt is preferable.

[0184] As the lithium salt, any lithium salt can be used, and specifically, the following lithium salts can be mentioned. For example, LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiTaF6, LiWF7, LiAsF6, LiAlCl4, LiI, LiBr, LiCl, LiB 10 Cl 10 , Li2SiF6, Li2PFO3, LiPO2F2 and other inorganic lithium salts; Lithium tungstates such as LiWOF5; Lithium carboxylates such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li; Lithium salts having an S=O group, such as FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li, lithium methyl sulfate, lithium ethyl sulfate (C2H5OSO3Li), and lithium 2,2,2-trifluoroethyl sulfate; LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2) 2、 Lithium imide salts such as LiN(C2F5SO2)2, bis(perfluoroethanesulfonyl)imide lithium, cyclic 1,2-perfluoroethanedisulfonyl imide lithium, cyclic 1,3-perfluoropropanedisulfonyl imide lithium, cyclic 1,2-ethanedisulfonyl imide lithium, cyclic 1,3-propanedisulfonyl imide lithium, cyclic 1,4-perfluorobutanedisulfonyl imide lithium, LiN(CF3SO2)(FSO2), LiN(CF3SO2)(C3F7SO2), LiN(CF3SO2)(C4F9SO2), and LiN(POF2)2; Methylated lithium salts such as LiC(FSO2)3, LiC(CF3SO2)3, and LiC(C2F5SO2)3; In addition, the formula: LiPF a (C n F 2n＋1 ) 6-a (wherein a is an integer from 0 to 5, and n is an integer from 1 to 6) (for example, LiPF3(C2F5)3, LiPF3(CF3)3, LiPF3(iso-C3F7)3, LiPF5(iso-C3F7), LiPF4(CF3)2, LiPF4(C2F5)2), LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, LiBF2(C2F5SO2)2, and fluorine-containing organic lithium salts such as LiSCN, LiB(CN)4, LiB(C6H5)4, Li2(C2O4), LiP(C2O4)3, Li2B 12 F b H 12-b (b is an integer from 0 to 3), etc.

[0185] Among them, from the viewpoint of having the effects of improving output characteristics, high-rate charge and discharge characteristics, high-temperature storage characteristics, cycle characteristics, etc., LiPF6, LiBF4, LiSbF6, LiTaF6, LiPO2F2, FSO3Li, CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethanedisulfonyl imide lithium, cyclic 1,3-perfluoropropanedisulfonyl imide lithium, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, etc. are particularly preferred, and at least one lithium salt selected from LiPF6, LiN(FSO2)2 and LiBF4 is most preferred.

[0186] These electrolyte salts can be used alone or in combination of two or more. When two or more are used in combination, preferred examples are the combination of LiPF6 and LiBF4; and the combination of LiPF6 and LiPO2F2, C2H5OSO3Li, or FSO3Li, which have the effect of improving high-temperature storage characteristics, load characteristics, and cycle characteristics.

[0187] In this case, the amount of LiBF4, LiPO2F2, C2H5OSO3Li or FSO3Li incorporated relative to 100% by mass of the entire electrolyte is not limited and is arbitrary as long as it does not significantly impair the effects of the present disclosure. It is generally 0.01% by mass or more, preferably 0.1% by mass or more, relative to the electrolyte of the present disclosure; and is generally 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0188] In addition, another example is the use of an inorganic lithium salt and an organic lithium salt, which has the effect of suppressing degradation caused by high-temperature storage. As the organic lithium salt, preferably CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethanedisulfonyl imide lithium, cyclic 1,3-perfluoropropanedisulfonyl imide lithium, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, etc. In this case, the ratio of the organic lithium salt to the total mass 100% of the electrolyte is preferably 0.1% or more, particularly preferably 0.5% or more; and preferably 30% or less, particularly preferably 20% or less.

[0189] As the electrolyte salt of the electrolyte solution for sodium ion secondary batteries, sodium salt is preferred.

[0190] As the sodium salt, any sodium salt can be used, and specifically, the following sodium salts can be mentioned. For example: NaPF6, NaBF4, NaClO4, NaAlF4, NaSbF6, NaTaF6, NaWF7, NaAsF6, NaAlCl4, NaI, NaBr, NaCl, NaB 10 Cl 10 , Na2SiF6, Na2PFO3, NaPO2F2 and other inorganic sodium salts; Sodium tungstates such as NaWOF5; Sodium salts of carboxylates such as HCO2Na, CH3CO2Na, CH2FCO2Na, CHF2CO2Na, CF3CO2Na, CF3CH2CO2Na, CF3CF2CO2Na, CF3CF2CF2CO2Na, CF3CF2CF2CF2CO2Na, etc.; Sodium salts having an S=O group, such as FSO3Na, CH3SO3Na, CH2FSO3Na, CHF2SO3Na, CF3SO3Na, CF3CF2SO3Na, CF3CF2CF2SO3Na, CF3CF2CF2CF2SO3Na, sodium methylsulfate, sodium ethylsulfate (C2H5OSO3Na), and sodium 2,2,2-trifluoroethylsulfate; Sodium imide salts such as NaN(FCO)2, NaN(FCO)(FSO2), NaN(FSO2)2, NaN(FSO2)(CF3SO2), NaN(CF3SO2)2, NaN(C2F5SO2)2, sodium bis(perfluoroethanesulfonyl imide), sodium cyclic 1,2-perfluoroethanedisulfonyl imide, sodium cyclic 1,3-perfluoropropanedisulfonyl imide, sodium cyclic 1,2-ethanedisulfonyl imide, sodium cyclic 1,3-propanedisulfonyl imide, sodium cyclic 1,4-perfluorobutanedisulfonyl imide, NaN(CF3SO2)(FSO2), NaN(CF3SO2)(C3F7SO2), NaN(CF3SO2)(C4F9SO2), and NaN(POF2)2; Methylated sodium salts such as NaC(FSO2)3, NaC(CF3SO2)3, and NaC(C2F5SO2)3; and Formula: NaPF a (C n F 2n＋1 ) 6-a(wherein a is an integer from 0 to 5, and n is an integer from 1 to 6) (for example, NaPF3(C2F5)3, NaPF3(CF3)3, NaPF3(iso-C3F7)3, NaPF5(iso-C3F7), NaPF4(CF3)2, NaPF4(C2F5)2), NaPF4(CF3SO2)2, NaPF4(C2F5SO2)2, NaBF3CF3, NaBF3C2F5, NaBF3C3F7, NaBF2(CF3)2, NaBF2(C2F5)2, NaBF2(CF3SO2)2, NaBF2(C2F5SO2)2, and fluorine-containing organic sodium salts such as NaSCN, LiB(CN)4, NaB(C6H5)4, Na2(C2O4), NaP(C2O4)3, Na2B 12 F b H 12-b (b is an integer from 0 to 3), etc.

[0191] Among them, from the viewpoint of having the effect of improving output characteristics, high-rate charge and discharge characteristics, high-temperature storage characteristics, cycle characteristics, etc., NaPF6, NaBF4, NaSbF6, NaTaF6, NaPO2F2, FSO3Na, CF3SO3Na, NaN(FSO2)2, NaN(FSO2)(CF3SO2), NaN(CF3SO2)2, NaN(C2F5SO2)2, cyclic 1,2-perfluoroethanedisulfonyl imide sodium, cyclic 1,3-perfluoropropanedisulfonyl imide sodium, NaC(FSO2)3, NaC(CF3SO2)3, NaC(C2F5SO2)3, NaBF3CF3, NaBF3C2F5, NaPF3(CF3)3, NaPF3(C2F5)3, etc. are particularly preferred, and at least one sodium salt selected from NaPF6, NaN(FSO2)2 and NaBF4 is most preferred.

[0192] The concentration of these electrolyte salts in the electrolyte solution is not particularly limited as long as it does not impair the effects of the present disclosure. From the perspective of maintaining the conductivity of the electrolyte solution within a good range and ensuring good battery performance, the total molar concentration of lithium or sodium in the electrolyte solution is preferably 0.3 mol / L or higher, more preferably 0.4 mol / L or higher, and even more preferably 0.5 mol / L or higher; and preferably 3 mol / L or lower, more preferably 2.5 mol / L or lower, and even more preferably 2.0 mol / L or lower.

[0193] If the total molar concentration of lithium or sodium is too low, the conductivity of the electrolyte may be insufficient. On the other hand, if the concentration is too high, the viscosity increases, thereby reducing the conductivity and thus the battery performance.

[0194] The electrolyte of the present disclosure preferably further comprises the general formula (3): [Chemistry 47] (Where X 21 is a group containing at least H or C; n21 is an integer from 1 to 3; Y 21 and Z 21 are the same or different and are groups containing at least H, C, O or F; n22 is 0 or 1; Y 21 and Z 21 If the electrolyte solution contains compound (3), the capacity retention rate is unlikely to further decrease and the amount of gas generated is unlikely to further increase even when stored at high temperatures.

[0195] When n21 is 2 or 3, 2 or 3 X 21 Can be the same or different.

[0196] In the presence of multiple Y 21 and Z 21 In the case of multiple Y 21 and Z 21 Can be the same or different.

[0197] As X 21 , preferably -CY 21 Z 21 -(where Y 21 and Z 21 as above) or -CY 21 =CZ 21 -(where Y 21 and Z 21 As described above).

[0198] As Y 21 , preferably at least one selected from H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0199] As Z 21 , preferably at least one selected from H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0200] Or, Y 21 and Z 21 They may be bonded to each other to include an unsaturated bond, and may form a carbocyclic or heterocyclic ring which may have aromaticity. The number of carbon atoms in the ring is preferably 3 to 20.

[0201] Next, specific examples of compound (3) are described. It should be noted that in the following examples, "analogs" refer to acid anhydrides obtained by replacing a portion of the structure of the exemplified acid anhydride with another structure within the scope of the present disclosure. For example, dimers, trimers, and tetramers composed of multiple acid anhydrides can be mentioned; or substances with the same number of carbon atoms in the substituents but structural isomers such as branching, substances with different substituents bonded to the acid anhydride, etc.

[0202] Specific examples of the acid anhydride forming a five-membered ring structure include succinic anhydride, methylsuccinic anhydride (4-methylsuccinic anhydride), dimethylsuccinic anhydride (4,4-dimethylsuccinic anhydride, 4,5-dimethylsuccinic anhydride, etc.), 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4,5-divinylsuccinic anhydride, phenylsuccinic anhydride (4-phenylsuccinic anhydride), 4,5 -diphenylsuccinic anhydride, 4,4-diphenylsuccinic anhydride, citraconic anhydride, maleic anhydride, methylmaleic anhydride (4-methylmaleic anhydride), 4,5-dimethylmaleic anhydride, phenylmaleic anhydride (4-phenylmaleic anhydride), 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, 5,5-dimethylitaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, and the like, and analogs thereof.

[0203] Specific examples of the acid anhydride forming a six-membered ring structure include cyclohexanedicarboxylic anhydride (cyclohexane-1,2-dicarboxylic anhydride, etc.), 4-cyclohexene-1,2-dicarboxylic anhydride, glutaric anhydride, glutaconic anhydride, 2-phenylglutaric anhydride, and analogs thereof.

[0204] Specific examples of other acid anhydrides forming a ring structure include 5-norbornene-2,3-dicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride, diglycolic anhydride, and analogs thereof.

[0205] Specific examples of the acid anhydride having a cyclic structure and substituted with a halogen atom include monofluorosuccinic anhydride (such as 4-fluorosuccinic anhydride), 4,4-difluorosuccinic anhydride, 4,5-difluorosuccinic anhydride, 4,4,5-trifluorosuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride (4,4,5,5-tetrafluorosuccinic anhydride), 4-fluoromaleic anhydride, 4,5-difluoromaleic anhydride, trifluoromethylmaleic anhydride, 5-fluoroitaconic anhydride, 5,5-difluoroitaconic anhydride, and analogs thereof.

[0206] Among these, preferred compounds (3) include glutaric anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, phenylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, dimethylsuccinic anhydride, trifluoromethylsuccinic anhydride, monofluorosuccinic anhydride, and tetrafluorosuccinic anhydride; more preferred are maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, trifluoromethylsuccinic anhydride, and tetrafluorosuccinic anhydride; and even more preferred are maleic anhydride and succinic anhydride.

[0207] Compound (3) is preferably selected from the general formula (4): [Chemistry 48] (Where X 31 ~X 34 The compound (4) represented by the formula (5) is the same or different and is a group containing at least H, C, O or F: [Chemistry 49] (Where X 41 and X 42 The compound (5) is at least one of the compounds (5) represented by (a group containing at least H, C, O or F, which is the same or different).

[0208] As X 31 ~X 34 , which are the same or different, are preferably at least one selected from the group consisting of alkyl, fluoroalkyl, alkenyl and fluoroalkenyl. 31 ~X 34 The number of carbon atoms in is preferably 1-10, more preferably 1-3.

[0209] As X 31 ~X 34 , the same or different, more preferably at least one selected from H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0210] As X 41 and X 42 , which are the same or different, are preferably at least one selected from the group consisting of alkyl, fluoroalkyl, alkenyl and fluoroalkenyl. 41 and X 42 The number of carbon atoms in is preferably 1-10, more preferably 1-3.

[0211] As X 41 and X 42 , the same or different, more preferably at least one selected from H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0212] The compound (4) is preferably any one of the following compounds.

[0213] [Chemistry 50] The compound (5) is preferably any one of the following compounds.

[0214] [Chemistry 51] The electrolyte preferably contains 0.0001 to 15% by mass of compound (3) relative to the electrolyte, from the viewpoint that the capacity retention rate is unlikely to further decrease and the amount of gas generated is unlikely to further increase even when stored at high temperatures. The content of compound (3) is more preferably 0.01 to 10% by mass, further preferably 0.1 to 3% by mass, and particularly preferably 0.1 to 1.0% by mass.

[0215] In the case where the above-mentioned electrolyte contains both compounds (4) and (5), from the viewpoint that the capacity retention rate is unlikely to further decrease and the amount of gas generated is unlikely to further increase when stored at high temperatures, the above-mentioned electrolyte preferably contains 0.08 to 2.50 mass% of compound (4) and 0.02 to 1.50 mass% of compound (5), and more preferably contains 0.80 to 2.50 mass% of compound (4) and 0.08 to 1.50 mass% of compound (5) relative to the above-mentioned electrolyte.

[0216] The electrolyte solution of the present disclosure may contain at least one selected from the group consisting of nitrile compounds represented by the following general formulae (1a), (1b), and (1c).

[0217] [Chemistry 52] (Where R a and R b Each independently represents a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least a portion of the hydrogen atoms of an alkyl group are replaced by a halogen atom. n represents an integer from 1 to 10. [Chemistry 53] (Where R crepresents a hydrogen atom, a halogen atom, an alkyl group, a group in which at least a part of the hydrogen atoms of an alkyl group are replaced by a halogen atom, or NC-R c1 -X c1 -(R c1 represents an alkylene group, X c1 represents an oxygen atom or a sulfur atom. d and R e Each independently represents a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a portion of the hydrogen atoms of an alkyl group are replaced by halogen atoms. m represents an integer from 1 to 10. [Chemistry 54] (Where R f 、R g 、R h and R i Each independently represents a group containing a cyano group (CN), a hydrogen atom (H), a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is replaced by a halogen atom. f 、R g 、R h and R i At least one of the groups is a group containing a cyano group. l represents an integer from 1 to 3. This can improve the high-temperature storage characteristics of the electrochemical device. The above-mentioned nitrile compounds can be used alone or in combination of two or more in any combination and ratio.

[0218] In the above general formula (1a), R a and R b Each is independently a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is replaced by a halogen atom.

[0219] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, among which a fluorine atom is preferred.

[0220] The alkyl group is preferably an alkyl group having 1 to 5 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group.

[0221] Examples of the group in which at least a part of the hydrogen atoms of an alkyl group are replaced by halogen atoms include groups in which at least a part of the hydrogen atoms of the above-mentioned alkyl group are replaced by the above-mentioned halogen atoms.

[0222] In R a and R b In the case of an alkyl group or a group in which at least a part of the hydrogen atoms of an alkyl group are replaced by halogen atoms, R a and R bThey may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0223] R a and R b A hydrogen atom or an alkyl group is preferred.

[0224] In the above general formula (1a), n is an integer of 1 to 10. When n is 2 or more, n R a They may all be the same or at least partly different. b n is preferably an integer of 1 to 7, more preferably an integer of 2 to 5.

[0225] As the nitrile compound represented by the above general formula (1a), dinitriles and trinitriles are preferred.

[0226] Specific examples of dinitriles include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, octanedinitrile, azelaic acid dicarbonitrile, sebacate, undecane dicarbonitrile, dodecane dicarbonitrile, 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, dicyclohexane-1,1-dicarbonitrile, dicyclohexane-2,2-dicarbonitrile, dicyclohexane-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexane dicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl-2,3-dimethylsuccinonitrile, Butyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyano octane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3′-(ethylenedioxy)dipropionitrile, 3,3′-(ethylenedisulfide)dipropionitrile, 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, butyronitrile, phthalonitrile, etc. Among these, succinonitrile, glutaronitrile, and adiponitrile are particularly preferred.

[0227] Specific examples of the trinitrile include pentaerythritol, propane tricarbonitrile, 1,3,5-hexane tricarbonitrile, 1,3,6-hexane tricarbonitrile, heptane tricarbonitrile, 1,2,3-propane tricarbonitrile, 1,3,5-pentane tricarbonitrile, cyclohexane tricarbonitrile, tricyanoethylamine, tricyanoethoxypropane, tricyanoethylene, tris(2-cyanoethyl)amine, and the like. 1,3,6-hexane tricarbonitrile and cyclohexane tricarbonitrile are particularly preferred, and cyclohexane tricarbonitrile is most preferred.

[0228] In the above general formula (1b), R c A hydrogen atom, a halogen atom, an alkyl group, a group in which at least a part of the hydrogen atoms of an alkyl group is replaced by a halogen atom, or NC-R c1 -X c1 -(R c1 represents an alkylene group, X c1 represents an oxygen atom or a sulfur atom. ) represented by a group, R d and R e Each is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group is replaced by a halogen atom.

[0229] Examples of the halogen atom, the alkyl group, and the group in which at least a part of the hydrogen atoms of the alkyl group are replaced by a halogen atom include the groups exemplified for the above-mentioned general formula (1a).

[0230] The above NC-R c1 -X c1 -R in c1 The alkylene group is preferably an alkylene group having 1 to 3 carbon atoms.

[0231] R c 、R d and R e Each of them is independently preferably a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of an alkyl group are replaced by a halogen atom.

[0232] R c 、R d and R e At least one of them is preferably a halogen atom or a group in which at least a part of the hydrogen atoms of an alkyl group are substituted with a halogen atom, and more preferably a fluorine atom or a group in which at least a part of the hydrogen atoms of an alkyl group are substituted with a fluorine atom.

[0233] In R d and R e In the case of an alkyl group or a group in which at least a part of the hydrogen atoms of an alkyl group are replaced by halogen atoms, R d and R e They may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0234] In the above general formula (1b), m is an integer of 1 to 10. When m is 2 or more, m R d They may all be the same or at least partly different. e m is preferably an integer of 2 to 7, and more preferably an integer of 2 to 5.

[0235] Examples of the nitrile compound represented by the general formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanecarbonitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3′-oxydipropionitrile, 3,3′-thiodipropionitrile, pentafluoropropionitrile, methoxyacetonitrile, and benzonitrile. Among them, 3,3,3-trifluoropropionitrile is particularly preferred.

[0236] 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 a part of the hydrogen atoms of an alkyl group are replaced by a halogen atom.

[0237] Examples of the halogen atom, the alkyl group, and the group in which at least a part of the hydrogen atoms of the alkyl group are replaced by a halogen atom include the groups exemplified for the above-mentioned general formula (1a).

[0238] Examples of the group containing a cyano group include, in addition to a cyano group, a group in which at least a part of hydrogen atoms of an alkyl group is replaced by a cyano group. Examples of the alkyl group in this case include the groups exemplified for the above general formula (1a).

[0239] R f 、R g 、R h and R i At least one of them is a group containing a cyano group. f 、R g 、R h and R i At least two of them are cyano-containing groups, more preferably R h and R i is a group containing a cyano group. h and R i In the case of a group containing a cyano group, R f and R g Preferred is a hydrogen atom.

[0240] In the above general formula (1c), l is an integer of 1 to 3. When l is 2 or more, one R f They may all be the same or at least partly different. g l is preferably an integer of 1 to 2.

[0241] Examples of the nitrile compound represented by the general formula (1c) include 3-hexenedicononitrile, 2,4-hexadienedicononitrile (mucononitrile), maleonitrile, fumaric acid nitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, and 2-hexenenitrile. 3-hexenedicononitrile and 2,4-hexadienedicononitrile are preferred, and 3-hexenedicononitrile is particularly preferred.

[0242] The content of the nitrile compound is preferably 0.2 to 7% by mass relative to the electrolyte. This can further improve the high-temperature storage characteristics and safety of the electrochemical device under high voltage. The lower limit of the total content of the nitrile compound is more preferably 0.3% by mass, more preferably 0.5% by mass. The upper limit is more preferably 5% by mass, more preferably 2% by mass, and particularly preferably 0.5% by mass.

[0243] The electrolyte of the present disclosure may contain a compound having an isocyanate group (hereinafter sometimes referred to as "isocyanate"). The isocyanate is not particularly limited, and any isocyanate can be used. Examples of isocyanates include monoisocyanates, diisocyanates, and triisocyanates.

[0244] Specific examples of the monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, isocyanatocyclohexane, methoxycarbonyl isocyanate, ethoxycarbonyl isocyanate, propoxycarbonyl isocyanate, butoxycarbonyl isocyanate, methoxysulfonyl isocyanate, ethoxysulfonyl isocyanate, propoxysulfonyl isocyanate, butoxysulfonyl isocyanate, fluorosulfonyl isocyanate, methyl isocyanate, butyl isocyanate, phenyl isocyanate, 2-isocyanoethyl acrylate, 2-isocyanoethyl methacrylate, and ethyl isocyanate.

[0245] Specific examples of diisocyanates include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropylene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-propene, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate diisocyanate), xylene diisocyanate, tolylenediisocyanate, 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 esters, dicyclohexylmethane-3,3′-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate, 2,5-bis(isocyanatemethyl)bicyclo[2.2.1]heptane, 2,6-bis(isocyanatemethyl)bicyclo[2.2.1]heptane, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, octamethylene diisocyanate, tetramethylene diisocyanate, and the like.

[0246] Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-triisocyanatomethylbenzene, 1,3,5-tris(6-isocyanatohexane-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 4-(isocyanatomethyl)octamethylene diisocyanate.

[0247] Among them, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohexane-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,4,4-trimethylhexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate are industrially readily available and can suppress the production cost of the electrolyte to a low level, so they are preferred. In addition, from a technical point of view, they can also contribute to the formation of a stable film-like structure and are more preferably used.

[0248] The content of isocyanate is not particularly limited, and may be any as long as the effect of the present disclosure is not significantly impaired. It is preferably 0.001% by mass or more and 1.0% by mass or less relative to the electrolyte. If the content of isocyanate is above the lower limit, it is possible to bring about a sufficient effect of improving the cycle characteristics of the non-aqueous electrolyte secondary battery. In addition, if it is below the upper limit, the initial resistance increase of the non-aqueous electrolyte secondary battery can be avoided. The content of isocyanate is more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more; and, more preferably 0.8% by mass or less, further preferably 0.7% by mass or less, particularly preferably 0.6% by mass or less.

[0249] The electrolyte solution disclosed herein may further include a cyclic sulfonate. The cyclic sulfonate is not particularly limited, and any cyclic sulfonate may be used. Examples of cyclic sulfonates include saturated cyclic sulfonates, unsaturated cyclic sulfonates, saturated cyclic disulfonates, and unsaturated cyclic disulfonates.

[0250] Specific examples of saturated cyclic sulfonic acid esters include 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone, 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1,3-butane sultone, 1,4-butane sultone, Sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone, 2,4-butane sultone, etc.

[0251] Specific examples of the unsaturated cyclic sulfonic acid ester include 1-propylene-1,3-sultone, 2-propylene-1,3-sultone, 1-fluoro-1-propylene-1,3-sultone, 2-fluoro-1-propylene-1,3-sultone, 3-fluoro-1-propylene-1,3-sultone, 1-fluoro-2-propylene-1,3-sultone, 2-fluoro-2-propylene-1,3-sultone, 3-fluoro-2-propylene-1,3-sultone, 1-methyl-1-propylene-1,3-sultone, 2-methyl-1-propylene-1,3-sultone, Esters, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-Fluoro-2-butene-1,4-sultone, 2-Fluoro-2-butene-1,4-sultone, 3-Fluoro-2-butene-1,4-sultone, 4-Fluoro-2-butene-1,4-sultone, 1,3-Propene sultone, 1-Fluoro-3-butene-1,4-sultone, 2-Fluoro-3-butene-1,4-sultone, 3-Fluoro-3-butene-1,4-sultone, 4-Fluoro-3-butene-1,4-sultone, 1-Methyl-1-butene-1,4-sultone, 2-Methyl-1-butene-1,4-sultone , 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone, 1-methyl-2-butene-1,4-sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3-butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, 4-methyl-3-butene-1,4-sultone, etc.

[0252] Among these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, and 1-propylene-1,3-sultone are more preferably used due to their ease of availability and their contribution to the formation of a stable film-like structure. The content of the cyclic sulfonic acid ester is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure, but is preferably 0.001% by mass to 3.0% by mass relative to the electrolyte solution.

[0253] If the cyclic sulfonate content is above this lower limit, the non-aqueous electrolyte secondary battery can achieve a sufficient improvement in cycle characteristics. Furthermore, if it is below this upper limit, an increase in the manufacturing cost of the non-aqueous electrolyte secondary battery can be avoided. The cyclic sulfonate content is more preferably 0.01% by mass or greater, even more preferably 0.1% by mass or greater, and particularly preferably 0.2% by mass or greater; and more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.8% by mass or less.

[0254] The electrolyte solution of the present disclosure may further contain polyoxyethylene having a weight average molecular weight of 2000 to 4000 and having -OH, -OCOOH or -COOH at the terminal.

[0255] By including such a compound, the stability of the electrode interface is improved, and the characteristics of the electrochemical device can be improved.

[0256] Examples of the polyoxyethylene include polyoxyethylene monool, polyoxyethylene formic acid, polyoxyethylene diol, polyoxyethylene dicarboxylic acid, polyoxyethylene triol, and polyoxyethylene trimeric acid. These may be used alone or in combination of two or more.

[0257] Among these, a mixture of polyoxyethylene monool and polyoxyethylene diol, and a mixture of polyvinyl formic acid and polyethylene dicarboxylic acid are preferred in terms of improving the characteristics of the electrochemical device.

[0258] If the weight average molecular weight of the polyoxyethylene is too small, it may be easily oxidatively decomposed. The weight average molecular weight is more preferably 3,000 to 4,000.

[0259] The weight average molecular weight can be measured in terms of polystyrene by gel permeation chromatography (GPC).

[0260] The content of the above-mentioned polyoxyethylene in the electrolyte is preferably 1×10 -6 ~1×10 -2 If the content of the above-mentioned polyoxyethylene is too high, the characteristics of the electrochemical device may be impaired.

[0261] The content of the above-mentioned polyoxyethylene is more preferably 5×10 -6 mol / kg or above.

[0262] The electrolyte solution disclosed herein may further contain a fluorinated saturated cyclic carbonate, an unsaturated cyclic carbonate, an overcharge preventer, and other known auxiliary agents as additives, thereby suppressing degradation of the characteristics of the electrochemical device.

[0263] As the fluorinated saturated cyclic carbonate, the compound represented by the above-mentioned general formula (A) can be mentioned. Among them, fluorinated ethylene carbonate, difluoroethylene carbonate, monofluoromethyl ethylene carbonate, trifluoromethyl ethylene carbonate, and 2,2,3,3,3-pentafluoropropyl ethylene carbonate (4-(2,2,3,3,3-pentafluoropropyl)-[1,3]dioxolane-2-one) are preferred. The fluorinated saturated cyclic carbonate can be used alone or in any combination and ratio.

[0264] The content of the fluorinated saturated cyclic carbonate is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 3% by mass, relative to the electrolyte solution.

[0265] Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, and catechol carbonates.

[0266] Examples of the vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, 4-fluorovinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluorovinylene carbonate, ethynyl ethylene carbonate, propargyl ethylene carbonate, methyl vinylene carbonate, and dimethyl vinylene carbonate.

[0267] Specific examples of ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl- 5-Ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-methylene-1,3-dioxolane-2-one, 4,5-dimethylene-1,3-dioxolane-2-one, 4-methyl-5-allylethylene carbonate, etc.

[0268] Wherein, as unsaturated cyclic carbonate, preferably: vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate.In addition, vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate can form a more stable interface protection film, so they are particularly preferred, and most preferably vinylene carbonate.

[0269] The molecular weight of unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged, it can be any molecular weight.Molecular weight is preferably more than 50 and below 250. If within the scope, then easily ensure that the unsaturated cyclic carbonate is relative to the solubility of electrolyte, easily give full play to the effect of the present disclosure.The molecular weight of unsaturated cyclic carbonate is more preferably more than 80, in addition, more preferably below 150.

[0270] The method for producing the unsaturated cyclic carbonate is not particularly limited, and any known method can be selected for production.

[0271] The unsaturated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio.

[0272] The content of above-mentioned unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged, then it can be any content.The content of above-mentioned unsaturated cyclic carbonate is preferably more than 0.001 mass % in electrolyte 100 mass %, more preferably more than 0.01 mass %, more preferably more than 0.1 mass %.In addition, above-mentioned content is preferably below 5 mass %, more preferably below 4 mass %, more preferably below 3 mass %.As long as within the above scope, then the electrochemical device using electrolyte easily shows sufficient cycle characteristics improving effect, in addition, easily avoid high temperature storage characteristic reduction, gas generation amount becomes many, discharge capacity retention rate reduces such situation.

[0273] As the unsaturated cyclic carbonate, in addition to the above-mentioned non-fluorinated unsaturated cyclic carbonate, a fluorinated unsaturated cyclic carbonate can also be preferably used.

[0274] Fluorinated unsaturated cyclic carbonate is a cyclic carbonate with unsaturated bond and fluorine atom. As long as the quantity of the fluorine atom possessed by fluorinated unsaturated cyclic carbonate is more than 1, then there is no particular restriction.Wherein, the fluorine atom is generally below 6, is preferably below 4, most preferably is 1 or 2.

[0275] Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives and fluorinated ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon double bond.

[0276] Examples of the fluorovinylene carbonate derivative include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, and 4-fluoro-5-vinylvinylene carbonate.

[0277] Examples of the fluoroethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5- Difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, and the like.

[0278] Among them, as the fluorinated unsaturated cyclic carbonate, the following compounds are more preferably used because they form a stable interface protective film: 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-allylcarbonate Ethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate.

[0279] The molecular weight of fluorinated unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged, and can be any molecular weight.Molecular weight is preferably more than 50, and is below 500.As long as it is the scope, then easily ensure that fluorinated unsaturated cyclic carbonate is relative to the solubility of electrolyte.

[0280] The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and any known method can be selected for production. The molecular weight is more preferably 100 or more and more preferably 200 or less.

[0281] Fluorinated unsaturated cyclic carbonate can be used alone as one, or in any combination and ratio and in combination with two or more. In addition, the content of fluorinated unsaturated cyclic carbonate is not particularly limited, as long as the effect of the present disclosure is not significantly damaged, it is any content. The content of fluorinated unsaturated cyclic carbonate is usually in 100% by mass of electrolyte, preferably more than 0.001% by mass, more preferably more than 0.01% by mass, further preferably more than 0.1% by mass; and preferably less than 5% by mass, more preferably less than 4% by mass, further preferably less than 3% by mass. As long as it is within the range, the electrochemical device using the electrolyte easily shows sufficient cycle characteristics to improve the effect, in addition, it is easy to avoid the situation where high temperature storage characteristics decrease, gas generation amount becomes more, and discharge capacity retention rate decreases.

[0282] The electrolyte solution of the present disclosure may further contain a compound having a triple bond. The compound may be any compound having one or more triple bonds in its molecule, and its type is not particularly limited.

[0283] Specific examples of the compound having a triple bond include the following compounds.

[0284] Hydrocarbon compounds such as 1-pentyne, 2-pentyne, 1-hexyne, 2-hexyne, 3-hexyne, 1-heptyne, 2-heptyne, 3-heptyne, 1-octyne, 2-octyne, 3-octyne, 4-octyne, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-dodecyne, 2-dodecyne, 3-dodecyne, 4-dodecyne, 5-dodecyne, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butyne, 4-phenyl-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentyne, 5-phenyl-1-pentyne, 1-phenyl-1-hexyne, 6-phenyl-1-hexyne, diphenylacetylene, 4-ethynyltoluene, and dicyclohexylacetylene; 2-Propynyl methyl carbonate, 2-propynyl ethyl carbonate, 2-propynyl propyl carbonate, 2-propynyl butyl carbonate, 2-propynyl phenyl carbonate, 2-propynyl cyclohexyl carbonate, di(2-propynyl) carbonate, 1-methyl-2-propynyl methyl carbonate, 1,1-dimethyl-2-propynyl methyl carbonate, 2-butynyl methyl carbonate, 3-butynyl methyl carbonate, 2-pentynyl methyl carbonate, Monocarbonates such as 3-pentynyl methyl carbonate and 4-pentynyl methyl carbonate; dicarbonates such as 2-butyne-1,4-diol dimethyl dicarbonate, 2-butyne-1,4-diol diethyl dicarbonate, 2-butyne-1,4-diol dipropyl dicarbonate, 2-butyne-1,4-diol dibutyl dicarbonate, 2-butyne-1,4-diol diphenyl dicarbonate, and 2-butyne-1,4-diol dicyclohexyl dicarbonate; 2-Propynyl acetate, 2-Propynyl propionate, 2-Propynyl butyrate, 2-Propynyl benzoate, 2-Propynyl cyclohexanecarboxylate, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-propynyl propionate, 1,1-dimethyl-2-propynyl butyrate, 1,1-dimethyl-2-propynyl benzoate, 1,1-dimethyl-2-propynyl cyclohexanecarboxylate, 2-Butynyl acetate, 3-Butynyl acetate, 2-Pentynyl acetate, 3-Pentynyl acetate, 4-Pentynyl acetate, Methyl acrylate, Ethyl acrylate Ester, propyl acrylate, vinyl acrylate, 2-propylene acrylate, 2-butylene acrylate, 3-butylene acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl methacrylate, 2-propylene methacrylate, 2-butylene methacrylate, 3-butylene methacrylate, methyl 2-propiolate, ethyl 2-propiolate, propyl 2-propiolate, vinyl 2-propiolate, 2-propylene 2-propiolate, 2-butylene 2-propiolate, 3-butylene 2-propiolate, 2-butylene Methyl butynoate, ethyl 2-butynoate, propyl 2-butynoate, vinyl 2-butynoate, 2-propenyl 2-butynoate, 2-butenyl 2-butynoate, 3-butenyl 2-butynoate, methyl 3-butynoate, ethyl 3-butynoate, propyl 3-butynoate, vinyl 3-butynoate, 2-propenyl 3-butynoate, 2-butenyl 3-butynoate, 3-butenyl 2-pentynoate, ethyl 2-pentynoate, propyl 2-pentynoate, vinyl 2-pentynoate, 2-propenyl 2-pentynoate, 2-pentynoate Monocarboxylic acid esters such as 2-butenyl acetyloate, 3-butenyl acetyloate, methyl 3-pentynoate, ethyl 3-pentynoate, propyl 3-pentynoate, vinyl 3-pentynoate, 2-propenyl 3-pentynoate, 2-butenyl 3-pentynoate, 3-butenyl 3-pentynoate, methyl 4-pentynoate, ethyl 4-pentynoate, propyl 4-pentynoate, vinyl 4-pentynoate, 2-propenyl 4-pentynoate, 2-butenyl 4-pentynoate, and 3-butenyl 4-pentynoate; fumarate esters, methyl pivalate, and ethyl pivalate; Dicarboxylic acid esters such as 2-butyne-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol dibutyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne-1,4-diol dicyclohexanecarboxylate, hexahydrobenzo[1,3,2]dioxathiolane-2-oxide (1,2-cyclohexanediol, 2,2-dioxo-1,2-oxathiolane-4-yl acetate, 2,2-dioxo-1,2-oxathiolane-4-yl acetate; Oxalic acid diesters such as 2-propynyl methyl oxalate, 2-propynyl ethyl oxalate, 2-propynyl propyl oxalate, 2-propynyl vinyl oxalate, allyl 2-propynyl oxalate, di(2-propynyl) oxalate, 2-butynyl methyl oxalate, 2-butynyl ethyl oxalate, 2-butynyl propyl oxalate, 2-butynyl vinyl oxalate, allyl 2-butynyl oxalate, di(2-butynyl) oxalate, 3-butynyl methyl oxalate, 3-butynyl ethyl oxalate, 3-butynyl propyl oxalate, 3-butynyl vinyl oxalate, allyl 3-butynyl oxalate, and di(3-butynyl) oxalate; Phosphine oxides such as methyl(2-propynyl)(vinyl)phosphine oxide, divinyl(2-propynyl)phosphine oxide, bis(2-propynyl)(vinyl)phosphine oxide, bis(2-propenyl)(2-propynyl)phosphine oxide, bis(2-propenyl)(2-propynyl)phosphine oxide, bis(3-butenyl)(2-propynyl)phosphine oxide, and bis(2-propynyl)(3-butenyl)phosphine oxide; 2-Propynyl methyl (2-propenyl) phosphinate, 2-propynyl 2-butenyl (methyl) phosphinate, 2-propynyl di(2-propenyl) phosphinate, 2-propynyl di(3-butenyl) phosphinate, 1,1-dimethyl-2-propynyl methyl (2-propenyl) phosphinate, 1,1-dimethyl-2-propynyl 2-butenyl (methyl) phosphinate, 1,1-dimethyl-2-propynyl di(2-propenyl) phosphinate , and phosphinates such as 1,1-dimethyl-2-propynyl di(3-butenyl)phosphinate, 2-propenyl methyl(2-propynyl)phosphinate, 3-butenyl methyl(2-propynyl)phosphinate, 2-propenyl di(2-propynyl)phosphinate, 3-butenyl di(2-propynyl)phosphinate, 2-propenyl 2-propynyl(2-propenyl)phosphinate, and 3-butenyl 2-propynyl(2-propenyl)phosphinate; 2-Propylenephosphonic acid (methyl) (2-propynyl) ester, 2-butenylphosphonic acid (methyl) (2-propynyl) ester, 2-propenylphosphonic acid (2-propynyl) (2-propenyl) ester, 3-butenylphosphonic acid (3-butenyl) (2-propynyl) ester, 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl) ester, 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl) ester, 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl) ester, and 3-butenylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl) Phosphonic acid esters such as (1,1-dimethyl-2-propynyl) (2-propenyl) methylphosphonate, (3-butenyl) (2-propynyl) methylphosphonate, (1,1-dimethyl-2-propynyl) (2-propenyl) methylphosphonate, (3-butenyl) (1,1-dimethyl-2-propynyl) methylphosphonate, (2-propynyl) (2-propenyl) ethylphosphonate, (3-butenyl) (2-propynyl) ethylphosphonate, (1,1-dimethyl-2-propynyl) (2-propenyl) ethylphosphonate and (3-butenyl) (1,1-dimethyl-2-propynyl) ethylphosphonate; Phosphates such as (methyl)(2-propenyl)(2-propynyl) phosphate, (ethyl)(2-propenyl)(2-propynyl) phosphate, (2-butenyl)(methyl)(2-propynyl) phosphate, (2-butenyl)(ethyl)(2-propynyl) phosphate, (1,1-dimethyl-2-propynyl)(methyl)(2-propenyl) phosphate, (1,1-dimethyl-2-propynyl)(ethyl)(2-propenyl) phosphate, (2-butenyl)(1,1-dimethyl-2-propynyl)(methyl) phosphate, and (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl) phosphate; Among these, compounds having an alkynyloxy group are preferred because they can form a negative electrode coating more stably in an electrolyte solution.

[0285] Furthermore, from the viewpoint of improving storage characteristics, compounds such as 2-propynyl methyl carbonate, di(2-propynyl) carbonate, 2-butyne-1,4-diol dimethyl dicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, 2-propynyl methyl oxalate, and di(2-propynyl) oxalate are particularly preferred.

[0286] The above-mentioned compound with triple bond can be used alone as one, or in any combination and ratio and in combination with two or more. The compound with triple bond is not limited in the amount of the electrolyte disclosed herein as a whole, as long as it does not significantly damage the effect of the present disclosure, and relative to the electrolyte disclosed herein, it contains usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less. When the above range is met, the effects such as output characteristics, load characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

[0287] The electrolyte solution of the present disclosure may contain an overcharge inhibitor in order to effectively suppress battery rupture or fire when an electrochemical device using the electrolyte solution becomes overcharged or the like.

[0288] Examples of the overcharge preventer include unsubstituted or alkyl-substituted terphenyl derivatives such as biphenyl, o-terphenyl, m-terphenyl, and p-terphenyl, partially hydrogenated unsubstituted or alkyl-substituted terphenyl derivatives, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, cyclopentylbenzene, cyclohexylbenzene, isopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, tert-butylbenzene, tert-amylbenzene, tert-hexylbenzene, and aromatic compounds such as anisole; 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, fluorotoluene, and trifluoromethane. Partially fluorinated products of the above aromatic compounds such as toluene; fluorinated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 1,6-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; aromatic acetates such as 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, and phenylethylphenyl acetate; aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate; toluene derivatives such as toluene and xylene; unsubstituted or alkyl-substituted biphenyl derivatives such as 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and o-cyclohexylbiphenyl; Among them, preferred are aromatic compounds such as biphenyl, alkylbiphenyls, terphenyls, partially hydrogenated terphenyls, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, diphenyl ether, and dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, diphenyl carbonate, and methylphenyl carbonate. These may be used alone or in combination of two or more. When two or more are used in combination, a combination of cyclohexylbenzene and tert-butylbenzene or tert-amylbenzene is particularly preferred from the perspective of balancing overcharge prevention and high-temperature storage properties; or a combination of at least one oxygen-free aromatic compound selected from biphenyl, alkylbiphenyls, terphenyls, partially hydrogenated terphenyls, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene with at least one oxygen-containing aromatic compound selected from diphenyl ether and dibenzofuran.

[0289] In the electrolyte used in the present disclosure, carboxylic anhydride (excluding compound (3)) may also be used. As the carboxylic anhydride, a compound represented by the following general formula (6) is preferred. The method for producing the carboxylic anhydride is not particularly limited, and any known method can be selected for production.

[0290] [Chemistry 55] (In general formula (6), R 61 、R 62 Each independently represents a hydrocarbon group having 1 to 15 carbon atoms which may have a substituent. R 61 、R 62 As long as it is a monovalent hydrocarbon group, its type is not particularly limited. For example, it can be an aliphatic hydrocarbon group, it can also be an aromatic hydrocarbon group, or it can be a group formed by bonding an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group can be a saturated hydrocarbon group, or it can contain an unsaturated bond (carbon-carbon double bond or carbon-carbon triple bond). In addition, the aliphatic hydrocarbon group can be chain-shaped or cyclic. In the case of a chain-shaped group, it can be straight-chain or branched. In addition, it can also be a group formed by bonding a chain-shaped group and a cyclic group. It should be noted that R 61 and R 62 They can be the same or different from each other.

[0291] In addition, in R 61 、R 62 When the hydrocarbon group has a substituent, the type of the substituent is not particularly limited as long as it does not violate the main purpose of the present disclosure. Examples include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, preferably fluorine atoms. In addition, substituents other than halogen atoms include substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups, preferably cyano groups and carbonyl groups. 61 、R 62 The hydrocarbon group may have only one of the above-mentioned substituents or may have two or more. When having two or more substituents, these substituents may be the same or different from each other.

[0292] R 61 、R 62 The number of carbon atoms of each hydrocarbon group is usually 1 or more and usually 15 or less, preferably 12 or less, more preferably 10 or less, and further preferably 9 or less. 61 With R 62 When the divalent hydrocarbon group is bonded to each other, the number of carbon atoms in the divalent hydrocarbon group is usually 1 or more and usually 15 or less, preferably 13 or less, more preferably 10 or less, and further preferably 8 or less. 61 、R 62 When the hydrocarbon group has a substituent containing a carbon atom, it is preferred that R including the substituent 61 、R 62 The total number of carbon atoms satisfies the above range.

[0293] Next, specific examples of the acid anhydride represented by the general formula (6) are described. It should be noted that in the following examples, "analogs" refer to acid anhydrides obtained by replacing a portion of the structure of the exemplified acid anhydride with another structure within the scope of the present disclosure. For example, dimers, trimers, and tetramers composed of multiple acid anhydrides, substances with the same number of carbon atoms in the substituents but structural isomers such as branching, substances with different substituents bonded to the acid anhydride, etc. can be cited.

[0294] First, the following is an example of R 61 、R 62 Specific examples of the same acid anhydride.

[0295] As R 61 、R 62 Specific examples of the acid anhydride having a chain alkyl group include acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutyric anhydride, 3-methylbutyric anhydride, 2,2-dimethylbutyric anhydride, 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, 2,2,3-trimethylbutyric anhydride, 2,3,3-trimethylbutyric anhydride, 2,2,3,3-tetramethylbutyric anhydride, 2-ethylbutyric anhydride, and analogs thereof.

[0296] As R 61 、R 62 Specific examples of the acid anhydride having a cyclic alkyl group include cyclopropanecarboxylic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, and analogs thereof.

[0297] As R 61 、R 62 Specific examples of the alkenyl acid anhydride include acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 2,3,3-trimethylacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3,3-diphenylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, 2,2-dimethyl-3-butenoic anhydride, 3-methyl-3-butenoic anhydride, 2-methyl-3-methyl-3-butenoic anhydride, 2,2-dimethyl-3-methyl-3-butenoic anhydride, 3-pentenoic anhydride, 4-pentenoic anhydride, 2-cyclopentenecarboxylic anhydride, 3-cyclopentenecarboxylic anhydride, 4-cyclopentenecarboxylic anhydride, and analogs thereof.

[0298] As R 61 、R 62 Specific examples of the acid anhydride which is an alkynyl group include propiolic anhydride, 3-phenylpropiolic anhydride, 2-butynoic anhydride, 2-pentynoic anhydride, 3-butynoic anhydride, 3-pentynoic anhydride, 4-pentynoic anhydride, and the like, and analogs thereof.

[0299] As R 61 、R 62 Specific examples of the acid anhydride which is an aryl group include benzoic anhydride, 4-methylbenzoic anhydride, 4-ethylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 2-methylbenzoic anhydride, 2,4,6-trimethylbenzoic anhydride, 1-naphthoic anhydride, 2-naphthoic anhydride, and analogs thereof.

[0300] In addition, as R 61 、R 62 Examples of acid anhydrides substituted with halogen atoms include acid anhydrides mainly substituted with fluorine atoms. However, acid anhydrides obtained by replacing some or all of these fluorine atoms with chlorine atoms, bromine atoms, or iodine atoms are also included in the exemplified compounds.

[0301] As R 61 、R 62 Examples of the acid anhydride of the chain alkyl group substituted with a halogen atom include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, 2-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrapropionic anhydride, 2,3,3,3-tetrapropionic anhydride, 3-fluoropropionic anhydride, 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic anhydride, perfluoropropionic anhydride, and analogs thereof.

[0302] As R 61 、R 62 Examples of the acid anhydride of a cyclic alkyl group substituted with a halogen atom include 2-fluorocyclopentanecarboxylic anhydride, 3-fluorocyclopentanecarboxylic anhydride, 4-fluorocyclopentanecarboxylic anhydride, and analogs thereof.

[0303] As R 61 、R 62 Examples of the acid anhydride of the alkenyl group substituted with a halogen atom include 2-fluoroacrylic anhydride, 3-fluoroacrylic anhydride, 2,3-difluoroacrylic anhydride, 3,3-difluoroacrylic anhydride, 2,3,3-trifluoroacrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, 3-(trifluoromethyl)acrylic anhydride, 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3,3-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, 2-fluoro-3-butenoic anhydride, 2,2-difluoro-3-butenoic anhydride, 3-fluoro-2-butenoic anhydride, 4-fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride, 3,3,4-trifluoro-3-butenoic anhydride, and analogs thereof.

[0304] As R61 、R 62 Examples of the acid anhydride of the alkynyl group substituted with a halogen atom include 3-fluoro-2-propiolic anhydride, 3-(4-fluorophenyl)-2-propiolic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propiolic anhydride, 4-fluoro-2-butynoic anhydride, 4,4-difluoro-2-butynoic anhydride, 4,4,4-trifluoro-2-butynoic anhydride, and the like, and analogs thereof.

[0305] As R 61 、R 62 Examples of the acid anhydride of the aryl group substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and the like, and analogs thereof.

[0306] As R 61 、R 62 Examples of acid anhydrides containing a substituent having a functional group such as an ester, nitrile, ketone, or ether include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutyric anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and analogs thereof.

[0307] Next, the following is an example of R 61 、R 62 Specific examples of different acid anhydrides.

[0308] As R 61 、R 62 , all combinations of the above examples and their analogs can be considered, and representative examples are given below.

[0309] Examples of combinations of chain alkyl groups include acetic propionic anhydride, acetic butyric anhydride, butyric propionic anhydride, and acetic 2-methylpropionic anhydride.

[0310] Examples of the combination of a chain alkyl group and a cyclic alkyl group include acetic acid cyclopentane anhydride, acetic acid cyclohexane anhydride, and cyclopentane propionic anhydride.

[0311] Examples of the combination of a chain alkyl group and an alkenyl group include acetic anhydride, acetic anhydride-3-methacrylic anhydride, acetic anhydride-3-butenoic anhydride, and acrylic anhydride-propionic anhydride.

[0312] Examples of the combination of a chain alkyl group and an alkynyl group include acetic anhydride propiolic acid, acetic anhydride-2-butiolic acid, acetic anhydride-3-butiolic acid, acetic anhydride-3-phenylpropiolic acid, and propiolic anhydride propionate.

[0313] Examples of the combination of a chain alkyl group and an aryl group include acetic anhydride, acetic 4-methylbenzoic anhydride, acetic 1-naphthoic anhydride, and benzoic propionic anhydride.

[0314] Examples of combinations of a chain alkyl group and a hydrocarbon group having a functional group include acetic fluoroacetic anhydride, acetic trifluoroacetic anhydride, acetic 4-fluorobenzoic anhydride, acetic fluoropropionic anhydride, acetic alkyl oxalic anhydride, acetic 2-cyanoacetic anhydride, acetic 2-oxopropionic anhydride, acetic methoxyacetic anhydride, and methoxyacetic propionic anhydride.

[0315] Examples of combinations of cyclic alkyl groups include cyclopentanecarboxylic acid and cyclohexanecarboxylic anhydride.

[0316] Examples of the combination of a cyclic alkyl group and an alkenyl group include cyclopentane acrylate anhydride, 3-cyclopentane methacrylate anhydride, cyclopentane 3-butenoate anhydride, and cyclohexane acrylate anhydride.

[0317] Examples of the combination of a cyclic alkyl group and an alkynyl group include propiolic acid cyclopentane anhydride, 2-butynoic acid cyclopentane anhydride, and propiolic acid cyclohexane anhydride.

[0318] Examples of the combination of a cyclic alkyl group and an aryl group include benzoic acid cyclopentane anhydride, 4-methylbenzoic acid cyclopentane anhydride, and benzoic acid cyclohexane anhydride.

[0319] Examples of the combination of a cyclic alkyl group and a hydrocarbon group having a functional group include fluoroacetic acid cyclopentanecarboxylic anhydride, cyclopentanecarboxylic acid trifluoroacetic anhydride, cyclopentanecarboxylic acid 2-cyanoacetic anhydride, cyclopentanecarboxylic acid methoxyacetic anhydride, and cyclohexanecarboxylic acid fluoroacetic anhydride.

[0320] Examples of combinations of alkenyl groups include acrylic acid, 2-methacrylic anhydride, acrylic acid, 3-methacrylic anhydride, acrylic acid, 3-butenoic anhydride, and 2-methacrylic acid, 3-methacrylic anhydride.

[0321] Examples of the combination of an alkenyl group and an alkynyl group include acrylic acid propiolic anhydride, acrylic acid 2-butynic anhydride, and 2-methacrylic acid propiolic anhydride.

[0322] Examples of the combination of an alkenyl group and an aryl group include acrylic acid benzoic anhydride, acrylic acid 4-methylbenzoic anhydride, and 2-methacrylic acid benzoic anhydride.

[0323] Examples of the combination of an alkenyl group and a hydrocarbon group having a functional group include acrylic acid fluoroacetic anhydride, acrylic acid trifluoroacetic anhydride, acrylic acid 2-cyanoacetic anhydride, acrylic acid methoxyacetic anhydride, and 2-methacrylic acid fluoroacetic anhydride.

[0324] Examples of combinations of alkynyl groups include propiolic acid-2-butynoic anhydride, propiolic acid-3-butynoic anhydride, and 2-butynoic acid-3-butynoic anhydride.

[0325] Examples of the combination of an alkynyl group and an aryl group include benzoic acid propiolic anhydride, 4-methylbenzoic acid propiolic anhydride, and benzoic acid 2-butynic anhydride.

[0326] Examples of the combination of an alkynyl group and a hydrocarbon group having a functional group include propiolic acid fluoroacetic anhydride, propiolic acid trifluoroacetic anhydride, propiolic acid 2-cyanoacetic anhydride, propiolic acid methoxyacetic anhydride, and 2-butynolic acid fluoroacetic anhydride.

[0327] Examples of combinations of aryl groups include 4-methylbenzoic anhydride benzoic acid, 1-naphthoic anhydride benzoic acid, and 1-naphthoic anhydride 4-methylbenzoic acid.

[0328] Examples of the combination of an aryl group and a hydrocarbon group having a functional group include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, and 4-methylbenzoic acid fluoroacetic anhydride.

[0329] Examples of combinations of hydrocarbon groups having a functional group include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, and trifluoroacetic acid 2-cyanoacetic anhydride.

[0330] Among the acid anhydrides forming a chain structure, acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, propiolic anhydride, 2-butynic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, trifluoroacetic anhydride, 3,3,3 -trifluoropropionic anhydride, 2-(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride; more preferably acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride.

[0331] These compounds form a film having excellent durability by appropriately forming a bond with lithium oxalate salt, and are particularly preferred from the viewpoint of being able to improve charge and discharge rate characteristics, input and output characteristics, and impedance characteristics after a durability test.

[0332] The molecular weight of the carboxylic anhydride is not limited and can be any value as long as it does not significantly impair the effects of the present disclosure. It is generally 90 or greater, preferably 95 or greater; on the other hand, it is generally 300 or less, preferably 200 or less. When the molecular weight of the carboxylic anhydride is within the above range, the increase in viscosity of the electrolyte solution can be suppressed, and the film density is optimized, thereby appropriately improving durability.

[0333] The carboxylic anhydride may be produced by any known method. The non-aqueous electrolyte solution of the present disclosure may contain any one of the carboxylic anhydrides alone or two or more of them in any combination and ratio.

[0334] In addition, the content of the above-mentioned carboxylic anhydride relative to the electrolyte of the present disclosure is not particularly limited, and can be any content as long as it does not significantly impair the effects of the present disclosure. It is desirable to contain a concentration of generally 0.01% by mass or more, preferably 0.1% by mass or more, and generally 5% by mass or less, preferably 3% by mass or less, relative to the electrolyte of the present disclosure. If the content of the carboxylic anhydride is within the above range, it is easy to exert the effect of improving the cycle characteristics, and the reactivity is good, therefore, it is easy to improve the battery characteristics.

[0335] Other known additives may be used in the electrolyte of the present disclosure. Examples of such additives include hydrocarbon compounds such as pentane, heptane, octane, nonane, decane, cycloheptane, benzene, furan, naphthalene, 2-phenylbicyclohexane, cyclohexane, 2,4,8,10-tetraoxaspiro[5.5]undecane, and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane; Fluorinated aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, trifluorotoluene, monofluorobenzene, 1-fluoro-2-cyclohexylbenzene, 1-fluoro-4-tert-butylbenzene, 1-fluoro-3-cyclohexylbenzene, 1-fluoro-2-cyclohexylbenzene, and fluorobiphenyl; Carbonate compounds such as anhydroerythritol carbonate (erythritan carbonate), spirobis-dimethylene carbonate, and methoxyethyl-methyl carbonate; Ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxopentadecane, ethoxymethoxyethane, trimethoxymethane, glyme, and ethyl monoglyme; Ketone compounds such as dimethyl ketone, diethyl ketone, and 3-pentanone; Anhydrides such as 2-allylsuccinic anhydride; Ester compounds such as dimethyl oxalate, diethyl oxalate, ethyl methyl oxalate, di(2-propynyl) oxalate, 2-propynyl methyl oxalate, dimethyl succinate, di(2-propynyl) glutarate, methyl formate, ethyl formate, 2-propynyl formate, 2-butyne-1,4-diyl dicarboxylate, 2-propynyl methacrylate, and dimethyl malonate; Acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide and other amide compounds; Ethylene sulfate, vinylene sulfate, ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, cyclobutane, diphenyl sulfone, 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 anhydride, sulfobutyric anhydride, sulfobenzoic anhydride, sulfopropionic anhydride, ethanedisulfonic anhydride, methylene methanedisulfonate, 2-propynyl methanesulfonate, amylene sulfite, pentafluorophenyl methanesulfonate, propylene sulfate, propylene sulfite, propane sultone, butylene sulfite, (butylene sulfite) Sulfur-containing compounds such as (1,2-propynyl) 2-(methanesulfonyloxy)propionate, (2-butyne-1,4-diyl) dimethanesulfonate, (2-propynyl) vinylsulfonate, bis(2-vinylsulfonylethyl) ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiole-2-oxide, 2-propynyl-2-(methanesulfonyloxy)propionate, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxide, 3-sulfo-propionic anhydride, methanedisulfonic acid trimethylene 2-methyltetrahydrofuran, methanedisulfonic acid trimethylene, tetramethylene sulfoxide, methanedisulfonic acid dimethylene ester, difluoroethyl methyl sulfone, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, methyl ethanedisulfonate, ethyl ethanedisulfonate, ethylene sulfate, and thiophene-1-oxide; Nitrogen-containing compounds such as 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide, nitromethane, nitroethane, and ethylenediamine; Trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, ethyl diethylphosphonoacetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide, bis(2,2-difluoroethyl) 2,2,2-trifluoroethyl phosphate, bis(2,2,3,3-tetrafluoropropyl) 2,2,2-trifluoroethyl phosphate Fluoroethyl esters, 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-phenylphenyl dimethyl phosphate , 2-phenylphenyl diethyl phosphate, (2,2,2-trifluoroethyl) (2,2,3,3-tetrafluoropropyl) methyl phosphate, 2-(dimethoxyphosphoryl) methyl acetate, 2-(dimethylphosphoryl) methyl acetate, 2-(diethoxyphosphoryl) methyl acetate, 2-(diethylphosphoryl) methyl acetate, methyl methylenebisphosphonate, ethyl methylenebisphosphonate, methyl ethylenebisphosphonate, ethyl ethylenebisphosphonate, methyl butylenebisphosphonate, ethyl butylenebisphosphonate, 2- Phosphorus-containing compounds such as 2-(dimethoxyphosphoryl)propynyl acetate, 2-(dimethylphosphoryl)propynyl acetate, 2-(diethoxyphosphoryl)propynyl acetate, 2-(diethylphosphoryl)propynyl acetate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, tris(trimethoxysilyl) phosphite, and trimethylsilyl polyphosphate; Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate; Silane compounds such as trimethylaluminium orthosilicate dimethylolate, triethylaluminium orthosilicate diethanolate, triethylaluminium orthosilicate dipropylate, trimethylaluminium orthosilicate dibutylate, triethylaluminium orthosilicate dibutylate, tetrakis(trimethylsiloxy)titanium, tetrakis(triethylsiloxy)titanium, and tetramethylsilane; These additives can be used alone or in combination of two or more. By adding these additives, the capacity retention characteristics after high-temperature storage and the cycle characteristics can be improved.

[0336] Among the above-mentioned other auxiliary agents, phosphorus-containing compounds are preferred, and tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite are preferred.

[0337] The amount of other auxiliary agents is not particularly limited and can be any amount as long as it does not significantly impair the effects of the present disclosure. The amount of other auxiliary agents is preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the electrolyte. As long as it is within this range, it is easy to fully demonstrate the effects of other auxiliary agents and it is easy to avoid situations such as reduction in battery characteristics such as high-load discharge characteristics. The amount of other auxiliary agents is more preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 3% by mass or less, and more preferably 1% by mass or less.

[0338] The electrolyte of the present invention may further contain cyclic and chain carboxylates, ether compounds (excluding compound (1), nitrogen-containing compounds, boron-containing compounds, organic silicon compounds, non-flammable (flame retardant) agents, surfactants, high dielectric constant additives, cycle characteristics and rate characteristics improvers, sulfone compounds, etc. as additives within the scope of not impairing the effects of the present invention.

[0339] Examples of the cyclic carboxylic acid esters include those having a total carbon number of 3 to 12 in their structural formulas. Specifically, c -Butyrolactone, c -Valerolactone, c -caprolactone, e -caprolactone, 3-methyl- c Among them, from the perspective of improving the characteristics of electrochemical devices due to the improvement of the degree of lithium ion dissociation, c -Butyrolactone is particularly preferred.

[0340] As the coordination amount of the cyclic carboxylic acid ester of additive, it is usually preferably more than 0.1 mass % in 100 mass % of solvent, more preferably more than 1 mass %. If it is this scope, then it is easy to improve the specific conductivity of electrolyte, improve the high current discharge characteristics of electrochemical device. In addition, the coordination amount of cyclic carboxylic acid ester is preferably below 10 mass %, more preferably below 5 mass %. By setting the upper limit like this, it is easy to make the viscosity of electrolyte in an appropriate range, avoid the reduction of specific conductivity, suppress the increase of negative electrode resistance, and make the high current discharge characteristics of electrochemical device in a good range.

[0341] In addition, as the above-mentioned cyclic carboxylic acid ester, a fluorinated cyclic carboxylic acid ester (fluorinated lactone) can also be used appropriately. As the fluorinated lactone, for example, the following formula (C) can be mentioned: [Chemistry 56] (Where X 15 ~X 20 The same or different, are -H, -F, -Cl, -CH3 or fluoroalkyl; wherein, X 15 ~X20 At least one of which is a fluoroalkyl group) The fluorinated lactones shown.

[0342] As X 15 ~X 20 The fluoroalkyl group in the group includes, for example, -CFH2, -CF2H, -CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, -CF(CF3)2, etc. From the viewpoint of high oxidation resistance and the effect of improving safety, -CH2CF3 and -CH2CF2CF3 are preferred.

[0343] If X 15 ~X 20 At least one of them is a fluoroalkyl group, then -H, -F, -Cl, -CH3 or a fluoroalkyl group can be 15 ~X 20 The substitution may be performed at only one site or at multiple sites. From the viewpoint of good solubility of the electrolyte salt, the substitution is preferably performed at 1 to 3 sites, more preferably 1 to 2 sites.

[0344] The substitution position of the fluoroalkyl group is not particularly limited, but from the viewpoint of good synthesis yield, X 17 and / or X 18 , especially X 17 or X 18 Is a fluoroalkyl group, preferably -CH2CF3, -CH2CF2CF3. X other than a fluoroalkyl group 15 ~X 20 It is -H, -F, -Cl or CH 3 , and is preferably -H from the viewpoint of good solubility of the electrolyte salt.

[0345] As the fluorinated lactone, in addition to the fluorinated lactone represented by the above formula, for example, the following formula (D) can also be mentioned: [Chemistry 57] (wherein, either A or B is CX 226 X 227 (X 226 and X 227 are the same or different, are -H, -F, -Cl, -CF3, -CH3 or an alkylene group in which the hydrogen atom may be replaced by a halogen atom and may contain a heteroatom in the chain), and the other is an oxygen atom; Rf 12 is a fluoroalkyl or fluoroalkoxy group which may have an ether bond; X 221 and X 222 The same or different are -H, -F, -Cl, -CF3 or CH3; X 223 ~X 225The same or different, all of which are -H, -F, -Cl or alkyl groups in which the hydrogen atom may be replaced by a halogen atom and may contain heteroatoms in the chain; n = 0 or 1) The fluorinated lactones shown, etc.

[0346] As the fluorinated lactone represented by formula (D), preferably, from the viewpoint of easy synthesis and good chemical stability, the following formula (E) can be mentioned: [Chemistry 58] (Where A, B, Rf 12 、X 221 、X 222 and X 223 Same as formula (D) The 5-membered ring structure shown; further, according to the combination of A and B, there is the following formula (F): [Chemistry 59] (Where Rf 12 、X 221 、X 222 、X 223 、X 226 and X 227 Same as formula (D) The fluorinated lactone shown, and the following formula (G): [Chemistry 60] (Where Rf 12 、X 221 、X 222 、X 223 、X 226 and X 227 Same as formula (D) The fluorinated lactones shown.

[0347] Among these substances, from the viewpoint of improving the characteristics of the electrolyte solution in the present disclosure in terms of being able to exhibit excellent properties such as a high dielectric constant and a high withstand voltage, and having good solubility of the electrolyte salt and effectively achieving a reduction in internal resistance, the following can be mentioned: [Chemistry 61] wait.

[0348] By containing a fluorinated cyclic carboxylic acid ester, effects such as improved ion conductivity, improved safety, and improved stability at high temperatures can be obtained.

[0349] Examples of the chain carboxylic acid esters include those having a total of 3 to 7 carbon atoms in their structural formulas. Specific examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isobutyl propionate, n-butyl propionate, methyl butyrate, isobutyl propionate, tert-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, and isopropyl isobutyrate.

[0350] Among them, from the viewpoint of improving ion conductivity by reducing viscosity, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, and the like are preferred.

[0351] As the ether compound, chain ethers having 2 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms are preferred.

[0352] Examples of the 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, and diisopropyl ether.

[0353] Furthermore, as the ether compound, fluorinated ether can also be preferably used.

[0354] Examples of the fluoroethers include those represented by the following general formula (I): Rf 3 -O-Rf 4 (I) (Where Rf 3 and Rf 4 are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms. 3 and Rf 4 At least one of them is a fluoroalkyl group.) The inclusion of fluoroether (I) can improve the flame retardancy of the electrolyte solution and enhance the stability and safety at high temperature and high voltage.

[0355] In the above general formula (I), as long as Rf 3 and Rf 4 At least one of the alkyl groups may be a fluoroalkyl group having 1 to 10 carbon atoms. However, from the perspective of further improving the flame retardancy of the electrolyte and the stability and safety at high temperature and high voltage, Rf is preferably3 and Rf 4 At the same time, it is a fluoroalkyl group having 1 to 10 carbon atoms. In this case, Rf 3 and Rf 4 They can be the same or different from each other.

[0356] Among them, Rf is more preferred 3 and Rf 4 Same or different, Rf 3 is a fluoroalkyl group having 3 to 6 carbon atoms, and Rf 4 It is a fluorinated alkyl group having 2 to 6 carbon atoms.

[0357] If Rf 3 and Rf 4 If the total number of carbon atoms of Rf is too small, the boiling point of the fluoroether becomes too low; in addition, if 3 or Rf 4 If the number of carbon atoms in the electrolyte is too large, the solubility of the electrolyte salt decreases, and the compatibility with other solvents begins to be adversely affected. In addition, the viscosity increases, so the rate characteristics decrease. When Rf 3 The number of carbon atoms is 3 or 4, Rf 4 When the number of carbon atoms is 2 or 3, it is advantageous in that the boiling point and rate characteristics are excellent.

[0358] The fluorine content of the fluoroether (I) is preferably 40 to 75% by mass. A fluorine content within this range provides a particularly good balance between non-flammability and compatibility. Furthermore, it is also preferred from the perspective of good oxidation resistance and safety.

[0359] The lower limit of the fluorine content is more preferably 45% by mass, further preferably 50% by mass, and particularly preferably 55% by mass, while the upper limit is more preferably 70% by mass, further preferably 66% by mass.

[0360] The fluorine content of the fluoroether (I) is a value calculated based on the structural formula of the fluoroether (I) according to {(number of fluorine atoms×19) / molecular weight of the fluoroether (I)}×100 (%).

[0361] As Rf 3 , for example, CF3CF2CH2-, CF3CFHCF2-, HCF2CF2CF2-, HCF2CF2CH2-, CF3CF2CH2CH2-, CF3CFHCF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CF2CH2-, HCF2CF2CH2CH2-, HCF2CF(CF3)CH2-, etc. In addition, as Rf 4For example, -CH2CF2CF3, -CF2CFHCF3, -CF2CF2CF2H, -CH2CF2CF2H, -CH2CH2CF2CF3, -CH2CF2CFHCF3, -CF2CF2CF2CF2H, -CH2CF2CF2CF2H, -CH2CH2CF2CF2H, -CH2CF(CF3)CF2H, -CF2CF2H, -CH2CF2H, -CF2CH3, etc. can be mentioned.

[0362] Specific examples of the fluoroether (I) include HCF2CF2CH2OCF2CF2H, CF3CF2CH2OCF2CF2H, HCF2CF2CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, C6F 13 OCH3、C6F 13 OC2H5、C8F 17 OCH3、C8F 17 OC2H5, CF3CFHCF2CH(CH3)OCF2CFHCF3, HCF2CF2OCH(C2H5)2, HCF2CF2OC4H9, HCF2CF2OCH2CH(C2H5)2, HCF2CF2OCH2CH(CH3)2, etc.

[0363] Among them, when HCF2- or CF3CFH- is contained at one or both ends, polarizability is excellent and a high boiling point fluoroether (I) can be formed. The boiling point of fluoroether (I) is preferably 67 to 120°C, more preferably 80°C or higher, and even more preferably 90°C or higher.

[0364] Examples of such fluorinated ethers (I) include one or more of CF3CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, HCF2CF2CH2OCF2CFHCF3, HCF2CF2CH2OCH2CF2CF2H, CF3CFHCF2CH2OCF2CFHCF3, HCF2CF2CH2OCF2CF2H, and CF3CF2CH2OCF2CF2H.

[0365] Among them, from the viewpoint of advantages in terms of high boiling point, compatibility with other solvents and good solubility of electrolyte salts, it is preferred to select at least one selected from HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C), CF3CF2CH2OCF2CFHCF3 (boiling point 82°C), HCF2CF2CH2OCF2CF2H (boiling point 92°C) and CF3CF2CH2OCF2CF2H (boiling point 68°C), and more preferably at least one selected from HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C) and HCF2CF2CH2OCF2CF2H (boiling point 92°C).

[0366] Examples of the 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, trioxane, 2-methyl-1,3-dioxolane, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-(trifluoroethyl)dioxolane, 2,2-bis(trifluoromethyl)-1,3-dioxolane, and fluorinated compounds thereof. Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, and crown ether are preferred in terms of their high solvating ability for lithium ions and improved ion dissociation degree; dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are particularly preferred in terms of their low viscosity and high ion conductivity.

[0367] Examples of the nitrogen-containing compounds include nitriles, fluorine-containing nitriles, carboxylic acid amides, fluorine-containing carboxylic acid amides, sulfonic acid amides, fluorine-containing sulfonic acid amides, acetamide, and formamide. Furthermore, 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide can also be used. However, the nitrile compounds represented by the general formulas (1a), (1b), and (1c) are not included in the nitrogen-containing compounds.

[0368] Examples of the boron-containing compound include boric acid esters such as trimethyl borate and triethyl borate, boric acid ethers, and alkylboranes.

[0369] Examples of the organic silicon-containing compound include (CH 3 ) 4 —Si, (CH 3 ) 3 —Si—Si(CH 3 ) 3 , and silicone oil.

[0370] Examples of the non-combustible (flame retardant) agent include phosphates or phosphazene compounds. Examples of the phosphates include fluorine-containing alkyl phosphates, non-fluorine-containing alkyl phosphates, and aryl phosphates. Fluorine-containing alkyl phosphates are preferred because they can produce a non-combustible effect even in small amounts.

[0371] Examples of the phosphazene compounds include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0372] Specific examples of the fluorine-containing alkyl phosphate include fluorine-containing dialkyl phosphate disclosed in Japanese Patent Application Laid-Open No. 11-233141, cyclic alkyl phosphate disclosed in Japanese Patent Application Laid-Open No. 11-283669, and fluorine-containing trialkyl phosphate.

[0373] As the above-mentioned non-flammable (flame retardant) agent, preferred are (CH3O)3P=O, (CF3CH2O)3P=O, (HCF2CH2O)3P=O, (CF3CF2CH2)3P=O, (HCF2CF2CH2)3P=O and the like.

[0374] The surfactant may be any of a cationic surfactant, anionic surfactant, nonionic surfactant, and amphoteric surfactant. From the viewpoint of good cycle characteristics and rate characteristics, a surfactant containing a fluorine atom is preferred.

[0375] As such a fluorine-containing surfactant, for example, the following formula (30) is preferred: Rf 5 COO - M + (30) (Where Rf 5 is a fluorinated alkyl group having 3 to 10 carbon atoms and which may contain an ether bond; M + For Li + 、Na + , K + or NHR′3 + (R' are the same or different and are H or an alkyl group with 1 to 3 carbon atoms) The fluorinated carboxylate shown in the following formula (40): Rf 6 SO3 - M + (40) (Where Rf 6 is a fluorinated alkyl group having 3 to 10 carbon atoms and which may contain an ether bond; M + For Li + 、Na + , K + or NHR′3 + (R' are the same or different and are H or an alkyl group with 1 to 3 carbon atoms) Fluorinated sulfonates, etc.

[0376] From the viewpoint of being able to reduce the surface tension of the electrolyte solution without deteriorating the charge-discharge cycle characteristics, the content of the surfactant in the electrolyte solution is preferably 0.01 to 2% by mass.

[0377] Examples of the dielectric constant-enhancing additive include sulfolane, methylsulfolane, c -Butyrolactone, c -Valerolactone, etc.

[0378] Examples of the cycle characteristics and rate characteristics improving agent include methyl acetate, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0379] In addition, the electrolyte solution of the present disclosure can be further combined with a polymer material to form a gel electrolyte solution in a gel state (plasticized).

[0380] As such polymer materials, there can be mentioned conventionally known polyoxyethylene, polyoxypropylene, and their modified bodies (Japanese Patent Publication No. 8-222270, Japanese Patent Publication No. 2002-100405); fluororesins such as polyacrylate polymers, polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene copolymers (Japanese Patent Publication No. 4-506726, Japanese Patent Publication No. 8-507407, Japanese Patent Publication No. 10-294131); and composites of these fluororesins with hydrocarbon resins (Japanese Patent Publication No. 11-35765, Japanese Patent Publication No. 11-86630). In particular, polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers are preferably used as polymer materials for gel electrolytes.

[0381] Furthermore, the electrolyte solution of the present disclosure may contain an ion-conductive compound described in Japanese Patent Application No. 2004-301934.

[0382] The ion-conductive compound is an amorphous fluorinated polyether compound having a fluorinated group in a side chain represented by formula (101): A-(D)-B (101) [Wherein, D is formula (201): -(D1) n -(FAE) m -(AE) p -(Y) q - (201) (wherein, D1 is an ether unit having a fluorine-containing ether group in the side chain represented by formula (2a): [Chemistry 62] (wherein, Rf is a fluorine-containing ether group which may have a crosslinkable functional group, R 10 is a group or bond that bonds Rf to the main chain); FAE is an ether unit having a fluoroalkyl group in the side chain represented by formula (2b): [Chemistry 63] (wherein, Rfa is a hydrogen atom or a fluoroalkyl group which may have a crosslinkable functional group; R 11 is a group or bond that bonds Rfa to the main chain); AE is an ether unit represented by formula (2c): [Chemistry 64] (Where R 13 is a hydrogen atom, an alkyl group which may have a crosslinkable functional group, an aliphatic cyclic hydrocarbon group which may have a crosslinkable functional group, or an aromatic hydrocarbon group which may have a crosslinkable functional group; R 12 To R 13 groups or bonds bonded to the main chain); Y is a unit comprising at least one of formulae (2d-1) to (2d-3): [Chemistry 65] n is an integer of 0 to 200; m is an integer of 0 to 200; p is an integer of 0 to 10,000; q is an integer of 1 to 100; wherein n+m is not 0, and the bonding order of D1, FAE, AE and Y is not particularly specified); A and B are the same or different and are a hydrogen atom, an alkyl group which may contain a fluorine atom and / or a crosslinking functional group, a phenyl group which may contain a fluorine atom and / or a crosslinking functional group, a -COOH group, -OR (R is a hydrogen atom or an alkyl group which may contain a fluorine atom and / or a crosslinking functional group), an ester group or a carbonate group (wherein, when the end of D is an oxygen atom, A and B are not -COOH groups, -OR, ester groups and carbonate groups)].

[0383] The electrolyte solution of the present disclosure may further contain a sulfone compound. The sulfone compound is preferably a cyclic sulfone having 3 to 6 carbon atoms or a chain sulfone having 2 to 6 carbon atoms. The number of sulfonyl groups in one molecule is preferably 1 or 2.

[0384] Examples of the cyclic sulfone include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones; and disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0385] As sulfolanes, preferably sulfolane and / or sulfolane derivatives (hereinafter, including sulfolane, sometimes referred to as "sulfolanes"). As sulfolane derivatives, preferably one or more of the hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted by a fluorine atom or an alkyl group.

[0386] Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methylsulfolane, 4-fluoro- -fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3-(trifluoromethyl)sulfolane, 3-fluoro-3-(trifluoromethyl)sulfolane, 4-fluoro-3-(trifluoromethyl)sulfolane, 3-sulfolene, 5-fluoro-3-(trifluoromethyl)sulfolane, and the like.

[0387] Examples of the chain sulfone include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl sulfone, tert-butyl methyl sulfone, tert-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl Trifluoromethyl sulfone, perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, bis(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl n-propyl sulfone, difluoromethyl n-propyl sulfone, trifluoromethyl n-propyl sulfone, fluoromethyl isopropyl sulfone, difluoromethyl isopropyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl n-propyl sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl n-butyl sulfone, trifluoroethyl tert-butyl sulfone, pentafluoroethyl n-butyl sulfone, pentafluoroethyl tert-butyl sulfone, etc.

[0388] Among them, from the viewpoint of high ion conductivity and high input and output, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, trifluoromethyl n-propyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl n-butyl sulfone, trifluoroethyl tert-butyl sulfone, trifluoromethyl n-butyl sulfone, trifluoromethyl tert-butyl sulfone, and the like are preferred.

[0389] The content of the sulfone compound is not particularly limited and may be any value as long as it does not significantly impair the effects of the present disclosure. The content is typically 0.3% by volume or more, preferably 0.5% by volume or more, and more preferably 1% by volume or more, based on 100% by volume of the solvent; and typically 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less. If the content of the sulfone compound is within the above range, it is easy to achieve the effect of improving durability, such as cycle characteristics and storage characteristics. Furthermore, the viscosity of the non-aqueous electrolyte can be kept within an appropriate range, preventing a decrease in conductivity, and enabling the input / output characteristics and charge / discharge rate characteristics of the non-aqueous electrolyte secondary battery to be kept within an appropriate range.

[0390] From the viewpoint of improving output characteristics, the electrolyte of the present disclosure preferably further contains as an additive at least one compound (7) selected from lithium fluorophosphate salts (excluding LiPF6) and lithium salts having an S=O group.

[0391] When compound (7) is used as an additive, it is preferable to use a compound other than compound (7) as the electrolyte salt.

[0392] Examples of the lithium fluorophosphate salts include lithium monofluorophosphate (LiPO 3 F) and lithium difluorophosphate (LiPO 2 F 2 ).

[0393] Examples of the lithium salts having an S═O group include lithium monofluorosulfonate (FSO 3 Li), lithium methyl sulfate (CH 3 OSO 3 Li), lithium ethyl sulfate (C 2 H 5 OSO 3 Li), and lithium 2,2,2-trifluoroethyl sulfate.

[0394] Among the compounds (7), LiPO2F2, FSO3Li, and C2H5OSO3Li are preferred.

[0395] The content of compound (7) is preferably 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, further preferably 0.1 to 10% by mass, and particularly preferably 0.1 to 7% by mass relative to the electrolyte solution.

[0396] Other additives may be added to the electrolyte solution of the present disclosure as needed. Examples of other additives include metal oxides and glass.

[0397] The content of hydrogen fluoride (HF) in the electrolyte disclosed herein is preferably 1 to 1000 ppm. By containing HF, the film formation of the above-mentioned additives can be promoted. If the HF content is too little, the film forming ability on the negative electrode is reduced, and there is a tendency for the characteristics of the electrochemical device to be reduced. In addition, if the HF content is too much, there is a tendency for the oxidation resistance of the electrolyte to be reduced due to the influence of HF. Even if the electrolyte disclosed herein contains HF in the above-mentioned range, it will not reduce the high-temperature storage capacity recovery rate of the electrochemical device.

[0398] The HF content is more preferably 5 ppm or more, further preferably 10 ppm or more, and particularly preferably 20 ppm or more. Furthermore, the HF content is more preferably 200 ppm or less, further preferably 100 ppm or less, further more preferably 80 ppm or less, and particularly preferably 50 ppm or less.

[0399] The HF content can be determined by neutralization titration.

[0400] The electrolyte of the present disclosure can be prepared by any method using the above-mentioned components.

[0401] The electrolyte disclosed herein is used in a battery having a negative electrode comprising an alkali metal. The alkali metal may be a single alkali metal. The alkali metal is preferably at least one selected from lithium, sodium, and potassium, more preferably at least one selected from lithium and sodium, and particularly preferably lithium.

[0402] Examples of the battery include secondary batteries such as lithium ion secondary batteries, sodium ion secondary batteries, and potassium ion secondary batteries. Lithium ion secondary batteries and sodium ion secondary batteries are preferred, and lithium ion secondary batteries are more preferred.

[0403] An electrochemical device comprising the electrolyte of the present disclosure is also an aspect of the present disclosure.

[0404] The secondary battery can adopt a known structure, typically comprising a positive electrode and a negative electrode capable of absorbing and releasing ions (e.g., lithium ions, sodium ions, etc.), and the electrolyte disclosed above. In addition, a secondary battery comprising the electrolyte disclosed herein is also an aspect of the present disclosure. A lithium-ion secondary battery comprising the electrolyte disclosed herein is also an aspect of the present disclosure.

[0405] Hereinafter, a secondary battery including the electrolytic solution of the present disclosure will be described.

[0406] The secondary battery preferably includes a positive electrode, a negative electrode, and the electrolyte solution.

[0407] <Positive electrode> The positive electrode is preferably composed of a positive electrode active material layer containing a positive electrode active material and a current collector.

[0408] As the above-mentioned positive electrode active material, there is no particular limitation as long as it is a substance that can electrochemically absorb and release alkali metal ions. For example, it is preferably a substance containing an alkali metal and at least one transition metal. As specific examples, transition metal composite oxides containing alkali metals and transition metal phosphate compounds containing alkali metals can be mentioned. Among them, as the positive electrode active material, transition metal composite oxides containing alkali metals that can generate high voltage are particularly preferred. As the above-mentioned alkali metal ions, lithium ions, sodium ions, potassium ions, etc. can be mentioned. In a preferred embodiment, the alkali metal ions can be lithium ions or sodium ions. That is, in this embodiment, the alkali metal ion secondary battery is a lithium ion secondary battery or a sodium ion secondary battery.

[0409] Examples of the alkali metal-containing transition metal composite oxide include Formula (3-1): M a Mn 2-b M 1 b O4 (wherein, M is at least one metal selected from Li, Na, and K; 0.9≤a; 0≤b≤1.5; M 1 a lithium-manganese spinel composite oxide represented by at least one metal selected from Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, Formula (3-2): MNi 1-c M 2 c O2 (wherein, M is at least one metal selected from Li, Na and K; 0≤c≤0.5; M 2 a lithium-nickel composite oxide represented by at least one metal selected from Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge), or Formula (3-3): MCo 1-d M 3 d O2 (wherein, M is at least one metal selected from Li, Na and K; 0≤d≤0.5; M 3is at least one metal selected from Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge) Among the above, M is preferably one metal selected from Li, Na and K, and more preferably Li or Na.

[0410] Among them, MCoO2, MMnO2, MNiO2, MMn2O4, MNiO2, and MMn2O4 are preferred from the viewpoint of providing a secondary battery with high energy density and high output. 0.8 Co 0.15 Al 0.05 O2、MNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, or MNi 0.8 Mn 0.1 Co 0.1 O2, etc., preferably a compound represented by the following formula (3-4).

[0411] MNi h Co i Mn j M 5 k O2 (3-4) (wherein, M is at least one metal selected from Li, Na and K, 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, (h+i+j+k)=1.0, 0≤h≤1.0, 0≤i≤1.0, 0≤j≤1.0, and 0≤k≤0.2. Examples of the alkali metal-containing transition metal phosphate compound include the following formula (70): M e M 4 f (PO4) g (wherein, M is at least one metal selected from Li, Na and K, M 4 represents at least one selected from V, Ti, Cr, Mn, Fe, Co, Ni, and Cu, and 0.5≤e≤3, 1≤f≤2, and 1≤g≤3). Among the above, M is preferably a metal selected from Li, Na, and K, and more preferably Li or Na.

[0412] As the transition metal in the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferred; as specific examples, there can be mentioned iron phosphates such as LiFePO4, Li3Fe2(PO4)3, LiFeP2O7; cobalt phosphates such as LiCoPO4; lithium-containing transition metal phosphate compounds in which a part of the transition metal atoms serving as the main body of these lithium transition metal phosphate compounds are replaced by other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc.

[0413] As the lithium-containing transition metal phosphate compound, one having an olivine structure is preferred.

[0414] Other positive electrode active materials include MFePO4, MNi 0.8 Co 0.2 O2, M 1.2 Fe 0.4 Mn 0.4 O2、MNi 0.5 Mn 1.5 O4, MV3O6, M2MnO3, etc. Especially MNi 0.5 Mn 1.5 Positive electrode active materials such as O4 are preferred in that their crystal structure is not destroyed when the secondary battery is operated at a voltage exceeding 4.4 V or a voltage above 4.6 V. Therefore, electrochemical devices such as secondary batteries using positive electrode materials containing the above-exemplified positive electrode active materials are preferred because their residual capacity is not easily reduced, the resistance increase rate is not easily changed, and the battery performance is not easily degraded even when operated at high voltages.

[0415] Other positive electrode active materials include M2MnO3 and MM 6 O2 (wherein, M is at least one metal selected from Li, Na and K, M 6 Solid solution materials of transition metals such as Co, Ni, Mn, and Fe, etc.

[0416] As the above-mentioned solid solution material, for example, a general formula Mx[Mn(1-y)M 7 y] alkali metal manganese oxide represented by Oz. Here, M in the formula is at least one metal selected from Li, Na and K, M 7 It is composed of at least one metal element other than M and Mn, for example, one or more elements selected from Co, Ni, Fe, Ti, Mo, W, Cr, Zr and Sn. In addition, the values of x, y and z in the formula are in the range of 1<x<2, 0≤y<1, and 1.5<z<3. 1.2 Mn0.5 Co 0.14 Ni 0.14 A manganese-containing solid solution material such as O2, in which LiNiO2 or LiCoO2 is solid-dissolved in a matrix of Li2MnO3, is preferred from the viewpoint of being able to provide an alkali metal ion secondary battery having a high energy density.

[0417] In addition, if lithium phosphate is included in the positive electrode active material, the continuous charging characteristics are improved, so it is preferred. There is no restriction on the use of lithium phosphate, and it is preferred to use the above-mentioned positive electrode active material and lithium phosphate in combination. As the amount of lithium phosphate used, the lower limit is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass or more, relative to the total of the above-mentioned positive electrode active material and lithium phosphate; the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less.

[0418] Alternatively, a material having a different composition attached to the surface of the above-mentioned positive electrode active material may be used. Examples of the surface-attached material include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0419] These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, dissolving or suspending them in a solvent, impregnating them into the positive electrode active material, and then drying them; dissolving or suspending a surface-attaching substance precursor in a solvent, impregnating them into the positive electrode active material, and then reacting them by heating or the like; adding them to the positive electrode active material precursor and simultaneously calcining them. In the case of carbon attachment, a method in which the carbon is mechanically attached in the form of, for example, activated carbon can also be used.

[0420] The amount of surface-attached material, by mass relative to the positive electrode active material, is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more as a lower limit; and preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less as an upper limit. Surface-attached material can inhibit the oxidation reaction of the electrolyte on the surface of the positive electrode active material, thereby improving battery life. However, if the amount of surface-attached material is too small, the effect cannot be fully realized; if it is too large, it hinders the entry and exit of lithium ions, thereby sometimes increasing resistance.

[0421] The shape of the particles of the positive electrode active material may be agglomerate, polyhedron, sphere, ellipsoid, plate, needle, column, etc. Primary particles may be aggregated to form secondary particles.

[0422] The tap density of the positive electrode active material is preferably 0.5 g / cm 3 More than 0.8 g / cm 3 More preferably, 1.0 g / cm 3 Above. If the tap density of the positive electrode active material is lower than the above lower limit, the amount of dispersion medium required when the positive electrode active material layer is formed increases, and the amount of conductive material and binder required increases. Sometimes the filling rate of the positive electrode active material into the positive electrode active material layer is restricted, and the battery capacity is restricted. By using a composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, the larger the tap density, the better, and there is no particular upper limit. However, if it is too large, sometimes the diffusion of lithium ions using the electrolyte in the positive electrode active material layer as a medium is limited, and the load characteristics are sometimes easily reduced. Therefore, the upper limit is preferably 4.0 g / cm 3 Below, more preferably 3.7g / cm 3 Below, more preferably 3.5g / cm 3 the following.

[0423] It should be noted that in the present disclosure, the tap density is determined as follows: 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass measuring cylinder and tapped 200 times with an amplitude of about 20 mm. The powder packing density (tap density) at this time is g / cm 3 As the tap density.

[0424] The median diameter d50 of the positive electrode active material particles (secondary particle diameter when primary particles aggregate to form secondary particles) is preferably 0.3 m m or more, more preferably 0.5 m m or more, more preferably 0.8 m m or more, most preferably 1.0 m m or more; and preferably 30 m m or less, more preferably 27 m m or less, more preferably 25 m m or less, most preferably 22 mm or less. If it is below the above lower limit, a product with a high tap density may not be obtained; if it is above the upper limit, the diffusion of lithium within the particles takes time, which may lead to a decrease in battery performance. In addition, when the positive electrode of the battery is produced, that is, when the active material, conductive material, binder, etc. are slurried with a solvent and coated into a thin film, problems such as pull-out streaks may sometimes occur. Here, the filling property when producing the positive electrode can be further improved by mixing two or more positive electrode active materials having different median diameters d50.

[0425] It should be noted that in the present disclosure, the median diameter d50 is measured using a known laser diffraction / scattering particle size distribution measuring device. When using LA-920 manufactured by HORIBA as a particle size distribution meter, a 0.1% by mass sodium hexametaphosphate aqueous solution is used as the dispersion medium used during the measurement, and after 5 minutes of ultrasonic dispersion, the measurement refractive index is set to 1.24 for measurement.

[0426] When the primary particles aggregate to form secondary particles, the average primary particle size of the positive electrode active material is preferably 0.05 m m or more, more preferably 0.1 m m or more, more preferably 0.2 m m or more; the upper limit is preferably 5 m m or less, more preferably 4 m m or less, more preferably 3 m m or less, most preferably 2 m m or less. Exceeding this upper limit makes it difficult to form spherical secondary particles, which may adversely affect powder packing properties. Alternatively, the specific surface area is significantly reduced, increasing the likelihood of reduced battery performance, such as output characteristics. Conversely, below this lower limit, crystals generally fail to develop, which may lead to problems such as poor reversibility during charge and discharge.

[0427] It should be noted that in the present disclosure, the primary particle size can be measured by observation using a scanning electron microscope (SEM). Specifically, for 50 random primary particles in a photograph at a magnification of 10,000 times, the longest value of the line segments formed by the left and right boundaries of the primary particles intersecting a horizontal straight line is obtained, and the average value is calculated.

[0428] The BET specific surface area of the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 / g or more, and the upper limit is preferably 50m 2 / g or less, more preferably 40m 2 / g or less, more preferably 30m 2If the BET specific surface area is smaller than this range, the battery performance is likely to decrease; if it is larger than this range, it is difficult to increase the tap density, which may easily cause problems in coating properties when forming the positive electrode active material layer.

[0429] In addition, in the present disclosure, the BET specific surface area is defined as a value obtained by measuring using a surface area meter (e.g., a fully automatic surface area measuring device manufactured by Ohkura Riken Co. Ltd.), pre-drying the sample at 150° C. for 30 minutes under nitrogen flow, and then measuring it by a nitrogen adsorption BET 1-point method based on a gas flow method using a nitrogen-helium mixed gas in which the relative pressure of nitrogen relative to atmospheric pressure is accurately adjusted to 0.3.

[0430] 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. Therefore, the particles of the positive electrode active material preferably mainly contain secondary particles.

[0431] The average particle size of the secondary particles of the positive electrode active material is preferably 40 m m or less, and containing 0.5 to 7.0% by volume of an average primary particle size of 1 m Microparticles with an average primary particle size of 1 m or less. m Microparticles with a diameter of 1 μm or less have a larger contact area with the electrolyte, which can accelerate the diffusion of lithium ions between the electrode and the electrolyte, thereby improving the output performance of the battery.

[0432] As a method for producing the positive electrode active material, a conventional method for producing an inorganic compound is used. In particular, various methods can be considered to produce a spherical or ellipsoidal active material, for example, the following method can be mentioned: dissolving or crushing the raw material of the transition metal and dispersing it in a solvent such as water, adjusting the pH while stirring, producing a spherical precursor, drying it as needed, adding a lithium source such as LiOH, Li2CO3, LiNO3, and calcining it at a high temperature to obtain the active material.

[0433] In order to manufacture the positive electrode, the above-mentioned positive electrode active materials can be used alone, or two or more of different compositions can be used in any combination or ratio. As a preferred combination in this case, LiCoO2, LiNi 0.33 Co 0.33 Mn 0.33 O2, such as LiMn2O4 or a combination of substances in which a part of Mn is replaced by other transition metals, or LiCoO2 or a combination of substances in which a part of Co is replaced by other transition metals.

[0434] From the perspective of high battery capacity, the content of the above-mentioned positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, and more preferably 80 to 99% by mass. In addition, the content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. In addition, the upper limit is preferably 99% by mass or less, and more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the capacitance is sometimes insufficient. On the contrary, if the content is too high, the strength of the positive electrode is sometimes insufficient.

[0435] The positive electrode active material layer preferably further contains a binder, a thickener, and a conductive material.

[0436] As the above-mentioned binder, any binder can be used as long as it is a material that is safe for the solvent and electrolyte used in the manufacture of the electrode, for example, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, nitrocellulose, etc.; rubber polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), ethylene-propylene rubber, etc.; styrene-butadiene-styrene block copolymer or its hydrogenated product; EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer or its hydrogenated product, etc.; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, propylene- α Soft resinous polymers such as olefin copolymers; fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymers, and tetrafluoroethylene-ethylene copolymers; polymer compositions having ion conductivity for alkali metal ions (particularly lithium and sodium ions). These may be used alone or in combination of two or more in any combination and ratio.

[0437] About the content of binder, as the ratio of the binder in the positive electrode active material layer, it is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more; and, it is usually 80% by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. If the ratio of binder is too low, the positive electrode active material cannot be fully maintained, the mechanical strength of the positive electrode is insufficient, and sometimes the battery performance such as cycle characteristics deteriorates. On the other hand, if it is too high, it sometimes leads to a reduction in battery capacity and conductivity.

[0438] Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, polyvinyl pyrrolidone, and salts thereof. One type may be used alone, or two or more types may be used in any combination and ratio.

[0439] The ratio of thickener to active material is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more; and, usually 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. If it is lower than this range, the coating property is sometimes significantly reduced. If it is greater than this range, the proportion of active material in the positive electrode active material layer is reduced, sometimes resulting in a problem of reduced battery capacity or an increased resistance between positive electrode active materials.

[0440] As the above-mentioned conductive material, any known conductive material can be used. As specific examples, metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, etc.; carbon materials such as amorphous carbon such as needle coke, carbon nanotubes, fullerene, VGCF, etc. It should be noted that they can be used alone or in any combination and proportion. The conductive material is usually 0.01% by mass or more in the positive electrode active material layer, preferably 0.1% by mass or more, more preferably 1% by mass or more; and, it is usually used in an amount containing 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less. If the content is below this range, the conductivity is sometimes insufficient. On the contrary, if the content is above this range, the battery capacity is sometimes reduced.

[0441] Examples of materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, nickel, and their alloys; and carbon materials such as carbon cloth and carbon paper. Among these, metals are preferred, and aluminum or its alloys are particularly preferred.

[0442] As the shape of the current collector, in the case of metal materials, metal foil, metal cylinder, metal coil, metal plate, expanded metal mesh, punched metal mesh, foamed metal, etc. can be mentioned; in the case of carbon materials, carbon plate, carbon film, carbon cylinder, etc. can be mentioned. Among them, metal foil is preferred. It should be noted that the film can be formed into a mesh shape as appropriate. The thickness of the film is arbitrary, usually 1 m m or more, preferably 3 m m or more, more preferably 5 m m or more; and usually 1 mm or less, preferably 100 m m or less, more preferably 50 mIf the film is thinner than this range, the strength required as a current collector may be insufficient. On the other hand, if the film is thicker than this range, the handling properties may be impaired.

[0443] Furthermore, coating the surface of the current collector with a conductive additive is preferred from the perspective of reducing the contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive additive include carbon or noble metals such as gold, platinum, and silver.

[0444] The ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, but the value of (the thickness of the positive electrode active material layer on one side when the electrolyte is to be injected) / (the thickness of the current collector) is preferably 20 or less, more preferably 15 or less, and most preferably 10 or less; and preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. If it is greater than this range, the current collector may generate heat due to Joule heat during high current density charging and discharging. If it is less than this range, the volume ratio of the current collector to the positive electrode active material increases, and the capacity of the battery may sometimes decrease.

[0445] The positive electrode can be manufactured by conventional methods. For example, a method of adding the aforementioned binder, thickener, conductive material, solvent, etc. to the aforementioned positive electrode active material to prepare a slurry of the positive electrode mixture is mentioned, which is then coated on a current collector, dried, and then pressed to achieve high density.

[0446] The density increase can be achieved by hand pressing, roller pressing, etc. The density of the positive electrode active material layer is preferably 1.5 g / cm 3 More than 2 g / cm 3 More preferably, 2.2 g / cm 3 More than; and, preferably 5g / cm 3 Below, more preferably 4.5g / cm 3 Below, more preferably 4g / cm 3 If the value exceeds this range, the electrolyte permeability near the current collector / active material interface decreases, and the charge and discharge characteristics at high current density are particularly degraded, sometimes preventing high output. If the value falls below this range, the conductivity between the active materials decreases, the battery resistance increases, and sometimes preventing high output.

[0447] As a solvent for forming the slurry, as long as it is a solvent that can dissolve or disperse the positive electrode active material, the conductive material, the binder, and the thickener used as needed, its type is not particularly limited, and any of aqueous solvents and organic solvents can be used. As aqueous solvents, for example, water, mixed solvents of alcohol and water, etc. can be mentioned. As organic solvents, for example, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide, etc.

[0448] As the organic solvent, a solvent represented by the general formula (60) can also be used.

[0449] General formula (60): [Chemistry 66] (Where R 1 、R 2 and R 3 are independently H or a monovalent substituent, wherein R 1 、R 2 and R 3 The total number of carbon atoms is 6 or more, R 1 、R 2 and R 3 At least one of them is an organic group having a carbonyl group. 1 、R 2 and R 3 Any two of them can be bonded to form a ring.) The solvent represented by the general formula (60) is preferably at least one selected from 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP), acryloylmorpholine, N-cyclohexyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 3-butoxy-N,N-dimethylpropionamide, N,N,N′,N′-tetraethyl urea, N,N-dimethylacetoacetamide, N-octyl-2-pyrrolidone and N,N-diethylacetamide.

[0450] As the solvent, water or at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and the solvent represented by the general formula (60) is preferred from the viewpoint of excellent coating properties, and more preferably selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP), acryloylmorpholine, N-cyclohexyl-2-pyrrolidone, N-vinyl- At least one selected from the group consisting of 2-pyrrolidone, 3-butoxy-N,N-dimethylpropionamide, N,N,N′,N′-tetraethyl urea, N,N-dimethylacetoacetamide, N-octyl-2-pyrrolidone and N,N-diethylacetamide, more preferably at least one selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone and N-butyl-2-pyrrolidone, and particularly preferably at least one selected from the group consisting of N-methyl-2-pyrrolidone and N,N-dimethylacetamide.

[0451] When using the electrolyte disclosed in the present invention, from the viewpoint of high output and improved stability at high temperature, it is preferred that the area of the positive electrode active material layer is increased relative to the outer surface area of the battery outer casing. Specifically, the sum of the electrode areas of the positive electrode is preferably 15 times or more, and more preferably 40 times or more, relative to the surface area of the outer packaging of the secondary battery in terms of area ratio. The outer surface area of the battery outer casing refers to the total area calculated from the length, width and thickness of the shell portion filled with the power generation element excluding the protruding portion of the terminal in the case of a bottomed rectangular parallelepiped shape. In the case of a bottomed cylindrical shape, it is the geometric surface area of the shell portion filled with the power generation element excluding the protruding portion of the terminal approximated as a cylinder. The sum of the electrode areas of the positive electrode refers to the geometric surface area of the positive electrode mixture layer relative to the mixture layer containing the negative electrode active material. In a structure in which the positive electrode mixture layer is formed on both sides with a current collector foil, it refers to the sum of the areas of each face calculated separately.

[0452] The thickness of the positive electrode plate is not particularly limited, but from the perspective of high capacity and high output, the lower limit of the thickness of the composite layer obtained by deducting the thickness of the core metal foil is preferably 10 mm for one side of the current collector. m m or more, more preferably 20 m m or more; and preferably 500 m m or less, more preferably 450 m m or less.

[0453] Alternatively, a material having a different composition attached to the surface of the positive electrode plate may be used. Examples of the surface-attached material include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0454] Negative electrode The negative electrode is preferably composed of a negative electrode active material layer containing a negative electrode active material and a current collector.

[0455] As the negative electrode active material, a material containing an alkali metal is used. The alkali metal may be a simple alkali metal. The alkali metal is preferably at least one selected from lithium, sodium, and potassium, more preferably at least one selected from lithium and sodium, and particularly preferably lithium.

[0456] Other materials capable of electrochemically absorbing and releasing alkali metal ions may also be used together with the above-mentioned alkali metals. Examples of the above-mentioned other materials include materials selected from carbonaceous materials such as artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolysis vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon and silicon alloys; Li4Ti5O 12 Among them, a material containing at least a portion of a carbonaceous material or a silicon-containing compound can be particularly preferably used.

[0457] The negative electrode active material used in the present disclosure preferably contains silicon among its constituent elements. By including silicon among its constituent elements, a high-capacity battery can be produced.

[0458] The silicon-containing material is preferably silicon particles, particles having a structure in which silicon microparticles are dispersed in a silicon-based compound, silicon oxide particles represented by the general formula SiOx (0.5 ≤ x ≤ 1.6), or a mixture thereof. By using these, a negative electrode mixture for a lithium-ion secondary battery having higher initial charge and discharge efficiency, high capacity, and excellent cycle characteristics can be obtained.

[0459] Silicon oxide, as used herein, is a general term for amorphous silicon oxides. Silicon oxide before disproportionation is represented by the general formula SiOx (0.5 ≤ x ≤ 1.6). x is preferably 0.8 ≤ x < 1.6, and more preferably 0.8 ≤ x < 1.3. Silicon oxide can be obtained, for example, by cooling and precipitating silicon monoxide gas generated by heating a mixture of silicon dioxide and metallic silicon.

[0460] Regarding particles having a structure in which silicon microparticles are dispersed in a silicon-based compound, for example, they can be obtained by calcining a mixture of silicon microparticles and a silicon-based compound, or by heat-treating silicon oxide particles before disproportionation represented by the general formula SiOx in an inert, non-oxidizing atmosphere such as argon at a temperature of 400°C or higher, preferably 800 to 1100°C, to cause a disproportionation reaction. In particular, the material obtained by the latter method is preferred because silicon microcrystals can be uniformly dispersed. By the disproportionation reaction described above, the size of silicon nanoparticles can be made 1 to 100 nm. It should be noted that the silicon oxide in the particles having a structure in which silicon nanoparticles are dispersed in silicon oxide is preferably silicon dioxide. It should be noted that the silicon nanoparticles (crystals) dispersed in the amorphous silicon oxide can be confirmed by transmission electron microscopy.

[0461] The physical properties of the silicon-containing particles can be appropriately selected according to the target composite particles. For example, the average particle size is preferably 0.1 to 50 m m, the lower limit is more preferably 0.2 m m or more, more preferably 0.5 m m or more. The upper limit is more preferably 30 m m or less, more preferably 20 m In addition, the average particle size in the present invention is represented by the weight average particle size obtained by particle size distribution measurement based on the laser diffraction method.

[0462] The BET specific surface area is preferably 0.5 to 100 m 2 / g, more preferably 1 to 20 m 2 / g. If the BET specific surface area is 0.5m 2 / g or more, there is no need to worry about the reduction of adhesion when applied to the electrode and the reduction of battery characteristics. 2 / g or less, the proportion of silicon dioxide on the particle surface becomes large, and when used as a negative electrode material for a secondary battery, the battery capacity does not decrease.

[0463] By carbon-coating the silicon-containing particles to impart conductivity, improved battery performance can be observed. Examples of methods for imparting conductivity include mixing with conductive particles such as graphite, coating the surface of the silicon-containing particles with a carbon coating, and a combination of these. Carbon coating is preferred, and chemical vapor deposition (CVD) is more preferred.

[0464] In order to increase the capacity of the electrode mixture obtained, the content of the above-mentioned negative electrode active material is preferably more than 40 mass % in the electrode mixture, more preferably more than 50 mass %, and particularly preferably more than 60 mass %. In addition, the upper limit is preferably below 99 mass %, more preferably below 98 mass %.

[0465] The negative electrode active material layer may contain a conductive auxiliary agent.

[0466] Any known conductive material can be used as the conductive additive. 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 amorphous carbon such as needle coke, carbon nanotubes, fullerene, and VGCF. These materials may be used alone or in combination of two or more in any combination and ratio.

[0467] The conductive additive is typically present in an electrode mixture at a concentration of 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 1% by mass or more. The conductive additive is typically used in an amount of 50% by mass or less, preferably 30% by mass or less, and more preferably 15% by mass or less. If the content is below this range, conductivity may be insufficient. Conversely, if the content is above this range, battery capacity may be reduced.

[0468] The negative electrode active material layer may further contain a thermoplastic resin. Examples of thermoplastic resins include vinylidene fluoride, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, and polyethylene oxide. One type may be used alone, or two or more types may be used in any combination and ratio.

[0469] The ratio of the thermoplastic resin to the negative electrode active material is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.10% by mass or more; and is usually 3.0% by mass or less, preferably 2.5% by mass or less, more preferably 2.0% by mass or less. By adding a thermoplastic resin, the mechanical strength of the electrode can be improved. In addition, if this range is exceeded, the proportion of the electrode active material in the negative electrode active material layer decreases, sometimes resulting in a problem of reduced battery capacity or increased resistance between active materials.

[0470] The negative electrode active material layer preferably contains a binder.

[0471] As the above-mentioned binder, the same substances as the binders that can be used in the positive electrode can be cited. The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 0.6% by mass or more; and preferably 20% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, and particularly preferably 8% by mass or less. If the ratio of the binder to the negative electrode active material exceeds the above range, the ratio of the binder that does not contribute to the battery capacity increases, sometimes resulting in a decrease in the battery capacity. In addition, if it is below the above range, it sometimes leads to a decrease in the strength of the negative electrode.

[0472] In particular, when the main component contains a rubber-like polymer represented by SBR, the ratio of the binder to the negative electrode active material is generally 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 0.6% by mass or more; and is generally 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. In addition, when the main component contains a fluorine-based polymer represented by polyvinylidene fluoride, the ratio of the binder to the negative electrode active material is generally 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more; and is generally 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

[0473] The negative electrode active material layer may contain a thickener.

[0474] As the above-mentioned thickener, the same substances as the thickeners that can be used in the positive electrode can be cited. The ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more; and usually 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. If the ratio of the thickener to the negative electrode active material is lower than the above range, the coating properties are sometimes significantly reduced. In addition, if the above range is exceeded, the proportion of the negative electrode active material in the negative electrode active material layer is reduced, and sometimes there is a problem of reduced battery capacity or increased resistance between the negative electrode active materials.

[0475] The negative electrode mixture of the present disclosure may further contain other components such as a leveling agent and a reinforcing material.

[0476] The negative electrode active material layer can be prepared, for example, by mixing a binder and a solvent, then adding the negative electrode active material to the resulting mixture and further mixing to form a slurry-like negative electrode mixture. The resulting negative electrode mixture is then evenly coated on a current collector such as metal foil or metal mesh, dried, and pressed as needed to form a thin negative electrode active material layer on the current collector, thereby forming a thin film electrode. Alternatively, the negative electrode mixture can be prepared by first mixing the negative electrode active material and the binder, and then adding the solvent.

[0477] As the above-mentioned solvent, an organic solvent is preferable.

[0478] Examples of the organic solvent include nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and dimethylformamide; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; ester solvents such as ethyl acetate and butyl acetate; and ether solvents such as tetrahydrofuran and dioxane. β -methoxy-N,N-dimethylpropionamide, β -n-Butoxy-N,N-dimethylpropionamide, β -n-Hexyloxy-N,N-dimethylpropionamide, etc. β -Alkoxypropionamides; and low-boiling-point general organic solvents such as mixed solvents thereof.

[0479] As the organic solvent, a solvent represented by the general formula (60) can also be used.

[0480] General formula (60): [Chemistry 67] (Where R 1 、R 2 and R 3 are independently H or a monovalent substituent, wherein R 1 、R 2 and R 3 The total number of carbon atoms is 6 or more, R 1 、R 2 and R 3 At least one of them is an organic group having a carbonyl group. 1 、R 2 and R 3 Any two of them can be bonded to form a ring.) The solvent represented by the general formula (60) is preferably at least one selected from 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP), acryloylmorpholine, N-cyclohexyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 3-butoxy-N,N-dimethylpropionamide, N,N,N′,N′-tetraethyl urea, N,N-dimethylacetoacetamide, N-octyl-2-pyrrolidone and N,N-diethylacetamide.

[0481] As the solvent, from the viewpoint of excellent coating properties, at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and the solvent represented by the general formula (60) is preferred, and more preferably selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP), acryloylmorpholine, N-cyclohexyl-2-pyrrolidone, N-vinyl-2 -pyrrolidone, 3-butoxy-N,N-dimethylpropionamide, N,N,N′,N′-tetraethyl urea, N,N-dimethylacetoacetamide, N-octyl-2-pyrrolidone and N,N-diethylacetamide, further preferably at least one selected from N-methyl-2-pyrrolidone, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropionamide, N-ethyl-2-pyrrolidone and N-butyl-2-pyrrolidone, particularly preferably at least one selected from N-methyl-2-pyrrolidone and N,N-dimethylacetamide.

[0482] The amount of the solvent in the negative electrode mixture can be determined in consideration of coating properties on the current collector, thin film forming properties after drying, etc. Generally, the ratio of the binder to the solvent is 0.5:99.5 to 20:80 by mass.

[0483] The negative electrode includes a negative electrode active material layer and a current collector. The negative electrode active material layer is formed using the above-mentioned negative electrode mixture and can be provided on one side or both sides of the current collector.

[0484] Examples of the current collector included in the negative electrode of the present disclosure include metal foils or metal meshes made of iron, stainless steel, copper, aluminum, nickel, titanium, and the like, and carbon materials such as carbon cloth and carbon paper. Among them, copper foil is preferred.

[0485] The negative electrode can be suitably produced by applying the negative electrode mixture to a current collector using the above-mentioned production method. After the negative electrode mixture is applied, the coating film can be dried, optionally heat-treated, and the resulting dried coating film can be pressed.

[0486] As the shape of the current collector, in the case of metal materials, metal foil, metal cylinder, metal coil, metal plate, expanded metal mesh, punched metal mesh, foamed metal, etc. can be mentioned; in the case of carbon materials, carbon plate, carbon film, carbon cylinder, etc. can be mentioned. Among them, metal foil is preferred. It should be noted that the film can be formed into a mesh shape as appropriate. The thickness of the film is arbitrary, usually 1 m m or more, preferably 3 m m or more, more preferably 5 m m or more; and, usually 1 mm or less, preferably 100 m m or less, more preferably 50 m If the film is thinner than this range, the strength required as a current collector may be insufficient. On the other hand, if the film is thicker than this range, the handling properties may be impaired.

[0487] The thickness of the negative electrode plate is designed to match the positive electrode plate used and is not particularly limited. However, the thickness of the composite layer after deducting the thickness of the core metal foil is preferably 15 m m or more, preferably 20 m m or more, more preferably 30 m m or more; and, usually 300 m m or less, preferably 280 m m or less, more preferably 250 m m or less.

[0488] <Isolators> The secondary battery of the present disclosure preferably further includes a separator.

[0489] The material and shape of the separator are not particularly limited, as long as they are stable in the electrolyte and have excellent liquid retention. Known materials and shapes can be used. Preferred separators are those made of materials that are stable in the electrolyte disclosed herein, such as resins, glass fibers, inorganic materials, and porous sheets or nonwoven fabrics with excellent liquid retention.

[0490] Materials for the resin and glass fiber separators include polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters. Polypropylene / polyethylene double-layer membranes and polypropylene / polyethylene / polypropylene triple-layer membranes can be used alone or in any combination and ratio. For improved electrolyte permeability and shutdown effects, the separators are preferably porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene.

[0491] The thickness of the spacer is arbitrary, but is usually 1 m m or more, preferably 5 mm or more, more preferably 8 m m or more; and, usually 50 m m or less, preferably 40 m m or less, more preferably 30 m If the separator is too thin outside the above range, the insulation and mechanical strength may be reduced. If it is too thick outside the above range, not only may the battery performance such as rate characteristics be reduced, but the energy density of the electrolyte battery as a whole may also be reduced.

[0492] Furthermore, when using porous materials such as porous sheets and non-woven fabrics as separators, the porosity of the separator is arbitrary, but is generally 20% or more, preferably 35% or more, and more preferably 45% or more; and is generally 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too low outside the above range, the membrane resistance tends to increase, and the rate characteristics tend to deteriorate. In addition, if the porosity is too high outside the above range, the mechanical strength of the separator tends to decrease, and the insulation properties tend to decrease.

[0493] The average pore size of the separator is also arbitrary, but is usually 0.5 m m or less, preferably 0.2 m m or less; and, usually 0.05 m If the average pore diameter is larger than the above range, short circuits are likely to occur. If the average pore diameter is smaller than the above range, the membrane resistance may increase and the rate characteristics may decrease.

[0494] On the other hand, as inorganic materials, oxides such as aluminum oxide and silicon dioxide; nitrides such as aluminum nitride and silicon nitride; and sulfates such as barium sulfate and calcium sulfate can be used, and materials in the form of particles or fibers can be used.

[0495] As the form, nonwoven fabric, woven fabric, microporous membrane and other film shapes can be used. In the case of a film shape, a pore size of 0.01 to 1 is preferably used. m m, thickness 5 to 50 m In addition to the above-mentioned independent film shape, a separator can also be used in which a composite porous layer containing the above-mentioned inorganic particles is formed on the surface of the positive electrode and / or the negative electrode using a resin binder. For example, a separator can be used in which a fluororesin is used as a binder on both sides of the positive electrode to form a composite porous layer containing the above-mentioned inorganic particles. m m aluminum oxide particles are formed into a porous layer.

[0496] Battery Design The electrode group may be either a stacked structure formed by sandwiching the aforementioned positive and negative plates with the aforementioned separator, or a spirally wound structure formed by sandwiching the aforementioned separator with the aforementioned positive and negative plates. The proportion 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.

[0497] If the electrode group occupancy rate is below the above range, the battery capacity will decrease. If it is above the above range, the void space will be reduced, and the battery's high temperature may cause component expansion, or the vapor pressure of the electrolyte liquid component may increase, leading to increased internal pressure. This will reduce various battery characteristics such as repeated charge and discharge performance and high-temperature storage, and may even cause the vent valve used to release internal pressure to operate.

[0498] The current collecting structure is not particularly limited, but in order to more effectively achieve the effect of the electrolyte disclosed herein on improving the charge-discharge characteristics at high current density, a structure that reduces the resistance of the wiring and bonding portions is preferably employed. When the internal resistance is reduced in this manner, the effects obtained by using the electrolyte disclosed herein can be particularly well utilized.

[0499] In the case of the aforementioned stacked electrode assembly, a suitable structure is one in which the metal core portions of the electrode layers are bundled and welded to the terminals. As the area of a single electrode increases, internal resistance increases, so it is also suitable to provide multiple terminals within the electrode to reduce resistance. In the case of the aforementioned wound electrode assembly, multiple lead structures are provided on each of the positive and negative electrodes and bundled to the terminals to reduce internal resistance.

[0500] The material of the outer casing is not particularly limited as long as it is a material that is stable with respect to the electrolyte used. Specifically, metals such as nickel-plated steel plates, stainless steel, aluminum or aluminum alloys, magnesium alloys, or laminated films of resin and aluminum foil can be used. From the perspective of lightweighting, metals such as aluminum or aluminum alloys and laminated films are preferably used.

[0501] In the case of using an exterior case made of a metal material, examples include an exterior case formed by laser welding, resistance welding, or ultrasonic welding to melt and join metals to form a sealed structure; or an exterior case formed by using the above-mentioned metal materials via a resin sealing gasket to form a caulked structure (in Japanese: かしめ構造). In the case of using an exterior case made of the above-mentioned laminated film, examples include an exterior case formed by heat-sealing resin layers to form a sealed structure. To improve the sealing performance, a resin different from the resin used in the laminated film may be sandwiched between the above-mentioned resin layers. In particular, when forming a sealed structure by heat-sealing resin layers via a current collector terminal, a metal-resin joint is formed, so a resin having a polar group or a modified resin into which a polar group is introduced is suitable as the spacer resin.

[0502] The shape of the lithium-ion secondary battery of the present disclosure is arbitrary, and examples include cylindrical, square, laminated, coin-shaped, large-sized, and other shapes. It should be noted that the shapes and configurations of the positive electrode, negative electrode, and separator can be changed according to the shape of each battery.

[0503] The embodiments have been described above, but it can be understood that various changes can be made to the form and details without departing from the gist and scope of the claims.

[0504] Examples Hereinafter, examples are given to describe the present disclosure in more detail, but the present disclosure is not limited to these examples.

[0505] The following shows compounds (A-1) to (A-5) used as Solvent 1.

[0506] (A-1) [Chemical formula 68] (A-2) [Chemical formula 69] (A-3) [Chemical formula 70] (A-4) [Chemical formula 71] (A-5) [Chemical formula 72] The following shows compounds (B-1) to (B-4) used as Solvent 1.

[0507] (B-1) [Chemistry 73] (B-2) [Chemistry 74] (B-3) [Chemistry 75] (B-4) [Chemistry 76] The compounds used as the solvent 2 are shown below.

[0508] EC ethylene carbonate The compounds used as solvent 3 are shown below.

[0509] EMC Ethyl Methyl Carbonate (C-1) CF2CF2CH2OCF2CHF2 (Examples 1 to 12 and Comparative Examples 1 to 5) [Preparation of electrolyte] Solvent 1, solvent 2, and solvent 3 shown in Table 1 were mixed in the volume ratio shown in Table 1, and LiN(FSO 2 ) 2 (LiFSI) was added to the mixture to give a concentration of 1.0 mol / L to prepare a non-aqueous electrolyte.

[0510] [Production of positive electrode] 97 parts by mass of LiNi as the positive electrode active material was added 0.8 Mn 0.1 Co 0.1 O2, 1.5 parts by mass of acetylene black as a conductive additive, and 1.5 parts by mass of polyvinylidene fluoride (8% by mass NMP solution) as a binder were mixed using a disperser to form a slurry. The resulting slurry was applied to aluminum foil and dried, rolled using a press, and then cut into a specified shape to prepare the positive electrode.

[0511] [Production of negative electrode] A lithium metal foil serving as a negative electrode active material was cut into a predetermined size to prepare a negative electrode.

[0512] [Battery Production] The prepared negative electrode is placed opposite to the above-mentioned positive electrode through a microporous polyethylene film (separator), and the non-aqueous electrolyte obtained above is injected. After the above-mentioned non-aqueous electrolyte fully penetrates the separator, etc., it is sealed and pre-charged and aged to prepare a button battery.

[0513] (Measurement of Battery Characteristics) [Save Test] The secondary battery manufactured as described above was subjected to a pre-cycle test at 25°C. The pre-cycle is to charge to 4.3V in a constant voltage and constant current mode with a current equivalent to 0.2C (the current value in the constant current mode is 0.01C). Then, constant current discharge is performed at a rate of 0.2C to 2.5V. The above cycle is repeated 3 times. Then, the battery is charged to 4.3V in a constant voltage and constant current mode with a constant current of 0.1C (the current value in the constant current mode is 0.01C). Then, the battery is stored in an environment of 80°C for 48 hours. After 48 hours, the battery is discharged to 2.5V at a constant current of 0.1C. The capacity obtained at this time is taken as the residual capacity, and the capacity value obtained in Comparative Example 1 is set to 1 to obtain the results of other embodiments. 1C represents the current value for discharging the base capacity of the battery for 1 hour. For example, 0.2C represents a current value of 1 / 5 thereof.

[0514] The results are shown in Table 1.

[0515] (Determination of lithium dissolution performance) [Battery Production] The battery test used a HS battery manufactured by Hohsen Co., Ltd. Lithium foil was punched into a 13mm diameter, and a separator impregnated with electrolyte was placed on top. Copper foil was also punched into a 15mm diameter and placed on the separator. The battery was sealed to complete the process. Battery assembly was performed in an argon atmosphere glove box.

[0516] [Dissolution and precipitation test] 10 coulombs of Li was electrodeposited on the copper foil so that lithium was deposited on the copper foil side. Then, 1 coulomb of Li was dissolved out of the copper foil to compare the dissolution performance. Specifically, the current density was 1.0 mA / cm at a temperature of 35°C. 2 The battery is charged and discharged with a current value of 10000 until the charge and discharge capacity reaches 0.2778 mAh (1 coulomb), and the cycle is terminated when the charge and discharge polarization exceeds 0.2 V. A greater number of cycles means that the lithium dissolution and precipitation proceed more smoothly.

[0517] The results are shown in Table 1.

[0518] [Table 1] (Example 13 and Comparative Example 6) [Preparation of electrolyte] Solvent 1, solvent 2, and solvent 3 shown in Table 2 were mixed in the volume ratio shown in Table 2, and NaN(FSO 2 ) 2 (NaFSI) was added to the mixture to give a concentration of 1.0 mol / L to prepare a non-aqueous electrolyte.

[0519] [Production of positive electrode] 97 parts by mass of NaCoO2 as the positive electrode active material and 1.5 parts by mass of polyvinylidene fluoride (8% by mass NMP solution) as the binder were added and mixed using a disperser to form a slurry. The resulting slurry was applied to aluminum foil and dried, rolled using a press, and then cut into a specified size to serve as the positive electrode.

[0520] [Production of negative electrode] The negative electrode is prepared by cutting the sodium metal foil into a predetermined size.

[0521] [Battery Production] The prepared negative electrode is placed opposite to the above-mentioned positive electrode through a microporous polyethylene film (separator), and the non-aqueous electrolyte obtained above is injected. After the above-mentioned non-aqueous electrolyte fully penetrates the separator, etc., it is sealed and pre-charged and aged to prepare a button battery.

[0522] (Measurement of Battery Characteristics) [Cycle characteristics] The obtained aluminum laminate battery was subjected to constant current-constant voltage charging (hereinafter referred to as CC / CV charging) (0.1C cut-off) to 4.2V at a current equivalent to 0.2C at 25°C, and then discharged to 3V at a constant current of 0.2C, which was regarded as one cycle, and three cycles were performed. Then, at 45°C, CC / CV charging (0.1C cut-off) was performed to 3.8V at a current equivalent to 1.0C, and then discharged to 1.5V at a constant current of 1.0C, which was regarded as one cycle, and the initial discharge capacity was obtained from the discharge capacity. The cycle was repeated to determine the discharge capacity after 300 cycles. The ratio of the discharge capacity after 300 cycles to the initial discharge capacity was determined and used as the capacity retention rate (%).

[0523] Capacity retention (%) = (discharge capacity after 300 cycles) ÷ (initial discharge capacity at 1.0C) × 100 The results are expressed as relative values with the result of Comparative Example 6 being set as 1.

[0524] The results are shown in Table 2.

[0525] [Table 2]

Claims

1. An electrolyte for a battery, characterized in that, the negative electrode of the battery has a material containing an alkali metal, the electrolyte contains a solvent, the solvent contains a compound (1) represented by the following general formula (1): In the formula, R 101 and R 102 are independently unfluorinated alkyl groups having 1 to 3 carbon atoms, and R 103 to R 106 are independently a hydrogen atom or a halogen atom, wherein at least one of R 103 to R 106 is a halogen atom.

2. The electrolyte according to claim 1, wherein, the compound (1) is at least one selected from the compounds represented by the following formulas, 。 3. The electrolyte according to claim 1 or 2, wherein, the content of the compound (1) is 0.01 to 80% by volume based on the solvent.

4. The electrolyte according to any one of claims 1 to 3, wherein, the alkali metal is at least one selected from lithium, sodium, and potassium.

5. An electrochemical device, characterized in that, it includes the electrolyte according to any one of claims 1 to 4.

6. A secondary battery, characterized in that, it includes the electrolyte according to any one of claims 1 to 4.

7. A lithium-ion secondary battery, characterized in that, it includes the electrolyte according to any one of claims 1 to 4.

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