Electrolyte solution and power storage device using same

Abstract

The electrolyte solution includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The nonaqueous solvent contains a first compound, and the first compound is at least one compound selected from the group consisting of 1, 3-diethyl-4-methyl-1-cyclobutene and a fluorine substituted product thereof. The electricity storage element is configured using the electrolyte solution.

Description

Technical Field

[0001] The present disclosure relates to an electrolytic solution and an electric storage device using the same. Background Art

[0002] Storage elements are used in a variety of applications. For example, electric double layer capacitors and lithium ion capacitors are used as small power sources for backup of semiconductor memories, etc. These capacitors are assumed to be used under severe conditions, so it is important for the electrolyte used to have properties that allow the capacitor to operate stably for a long time in a wide temperature range from low to high temperatures.

[0003] Patent Document 1 discloses an electrolytic solution for an electric double layer capacitor in which tetraethylammonium tetrafluoroborate, which is an aliphatic quaternary ammonium salt, is dissolved as an electrolyte salt in propylene carbonate, which is an organic solvent.

[0004] Patent Document 2 discloses a capacitor electrolyte solution using a quaternary ammonium salt or a lithium salt as an electrolyte salt and a mixed solvent containing acetonitrile as an organic solvent. Acetonitrile is characterized in that its viscosity at room temperature is 0.34 mPa·s, which is a very low viscosity, and therefore, it has a characteristic of being able to reduce the resistance value of the element at low temperatures.

[0005] The above-mentioned propylene carbonate and acetonitrile can also be used as an electrolyte of a non-aqueous electrolyte secondary battery.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2000-114105

[0009] Patent Document 2: International Publication No. 2013 / 146136 Summary of the invention

[0010] One aspect of the present disclosure relates to an electrolyte solution comprising: a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, wherein the non-aqueous solvent contains a first compound, and the first compound is at least one selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene represented by the following formula (1) and its fluorine-substituted product.

[0011]

[0012] Another aspect of the present disclosure relates to an electric storage element including the above-mentioned electrolytic solution.

[0013] Still another aspect of the present disclosure relates to at least one compound selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene and fluorine-substituted products thereof.

[0014] According to the electrolytic solution of the present disclosure, it is possible to provide an electric storage element that can exhibit excellent electric characteristics such as low resistance, particularly at low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a partially cutaway perspective view schematically showing the internal structure of a secondary battery according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0016] Prior to the description of the embodiment, the subject of the prior art is briefly described. The viscosity of propylene carbonate at room temperature is slightly as high as 2.5 mPa·s, and there is a problem that the resistance value of the element becomes high, especially at low temperatures. Although the viscosity of acetonitrile at room temperature is low, there is a possibility of generating hydrogen cyanide gas due to combustion in an accident, etc., and its use is restricted due to safety issues.

[0017] Hereinafter, examples are given to illustrate the embodiments of the electrolyte and storage element of the present disclosure, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes exemplified, but other numerical values ​​and materials can also be applied as long as the effect of the present disclosure is obtained. In the following description, when the lower limit and upper limit of the numerical value involving specific physical properties, conditions, etc. are exemplified, as long as the lower limit does not become above the upper limit, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined. In the case of exemplifying multiple materials, one can be selected from them for use alone, or two or more can be combined for use.

[0018] The storage element includes a non-aqueous electrolyte capacitor, a non-aqueous electrolyte secondary battery, etc. The storage element can be an element that utilizes both a Faraday reaction and a non-Faraday reaction (i.e., has the properties of both a capacitor and a secondary battery). The non-aqueous electrolyte capacitor includes a double-layer capacitor, a lithium-ion capacitor, etc. The non-aqueous electrolyte secondary battery includes a lithium-ion secondary battery, a lithium metal secondary battery, etc. The capacitor can also be referred to as a "capacitor".

[0019] The electrolyte of one embodiment of the present disclosure is a non-aqueous electrolyte, and has a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent can be an organic solvent. The non-aqueous solvent contains a first compound. The first compound is at least one selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene and its fluorine-substituted product. The first compound has a low viscosity, and the viscosity at room temperature can be less than 0.6 mPa·s. In addition, the first compound does not contain a cyanide group, so even if it burns, no toxic hydrogen cyanide gas is produced. By including the first compound in the non-aqueous solvent, the storage element can also exhibit excellent electrical properties at low temperatures. Specifically, it can provide: a safe non-aqueous electrolyte capacitor, a non-aqueous electrolyte secondary battery, etc. with low internal resistance, excellent conductivity, and no toxic gas generated during combustion.

[0020] 1,3-Diethyl-4-methyl-1-cyclobutene has the formula (1):

[0021]

[0022] The structure shown.

[0023] The first compound is at least one selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene and fluorine-substituted products thereof, wherein the fluorine-substituted product of 1,3-diethyl-4-methyl-1-cyclobutene refers to a compound in which one or more arbitrary hydrogen atoms among the hydrogen atoms of 1,3-diethyl-4-methyl-1-cyclobutene are substituted with fluorine atoms.

[0024] By incorporating the first compound into the nonaqueous solvent, the viscosity of the solvent can be further reduced, and therefore the resistance of the electric storage element at low temperatures can be further reduced.

[0025] The content of the first compound in the non-aqueous solvent is preferably 5% by mass or more and 80% by mass or less. If the content of the first compound is 5% by mass or more, the viscosity of the mixed non-aqueous solvent as a whole is sufficiently reduced, and the improvement of the resistance at low temperature is sufficiently visible. On the contrary, if the content of the first compound is 80% by mass or less, the precipitation of the electrolyte salt (such as a quaternary ammonium salt, a lithium salt, etc.) is suppressed, and the characteristics of the storage element become better.

[0026] The electrolyte disclosed herein may be an electrolyte in which at least one selected from the group consisting of a quaternary ammonium salt and a lithium salt is dissolved in a non-aqueous solvent. The electrolyte of the electric double layer capacitor may contain a quaternary ammonium salt. Lithium ion capacitors, lithium ion secondary batteries, lithium metal secondary batteries, etc. may contain lithium salts.

[0027] The nonaqueous solvent may contain other compounds in addition to the first compound. As the other compound, a second compound which is at least one selected from the group consisting of cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic carbonates, chain carbonates, and cyclic sulfone compounds may be used.

[0028] As cyclic carboxylic acid esters, α-acetone, β-propiolactone, γ-butyrolactone, δ-valerolactone, etc. can be mentioned, and γ-butyrolactone is particularly preferred. As cyclic carboxylic acid esters, methyl acetate, ethyl acetate, methyl propionate, etc. can be mentioned. As cyclic carbonates, vinylene carbonate, propylene carbonate, ethylene carbonate, butylene carbonate, etc. can be mentioned. As chain carbonates, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, etc. can be mentioned. As cyclic sulfone compounds, cyclopentane, alkylcyclopentane, etc. can be mentioned, and 3-methylcyclopentane is particularly preferred.

[0029] As the quaternary ammonium salt, a salt formed of a tetraalkylammonium ion and an anion is desirable.

[0030] As the tetraalkylammonium ion, at least one of tetramethylammonium ion, trimethylethylammonium ion, triethylmethylammonium ion, tetraethylammonium ion, tetrabutylammonium ion, diethyldimethylammonium ion and the like can be used.

[0031] Examples of anions constituting quaternary ammonium salts or lithium salts include Cl - 、BF4 - PF6 - 、ClCO4 - CF3SO3 - 、N(FSO2)2 - 、N(CF3SO2)2 - 、N(C2F5SO2)2 - 、C(CF3SO2)3 - wait.

[0032] Specific examples of quaternary ammonium salts include triethylmethylammonium tetrafluoroborate, and specific examples of lithium salts include LiPF6, LiBF4, LiN(FSO2)2, and the like.

[0033] The preferred lower limit of the concentration of the electrolyte salt in the electrolyte disclosed herein is 0.1 mol / L, and the preferred upper limit is 3.0 mol / L. If the concentration of the electrolyte salt is 0.1 mol / L or more, sufficient conductivity can be ensured. If the concentration of the electrolyte salt is 3.0 mol / L or less, the viscosity of the obtained electrolyte can be suppressed to increase, and a storage element with excellent electrical properties can be obtained. The more preferred lower limit of the concentration of the electrolyte salt is 0.5 mol / L, and the more preferred upper limit is 2 mol / L.

[0034] The manufacturing method of the electrolyte of the present invention is as described later. First, the non-aqueous solvent and the electrolyte salt (quaternary ammonium salt, lithium salt, etc.) are dehydrated. Afterwards, in a low humidity environment such as a glove box, at least one electrolyte salt selected from the group consisting of a quaternary ammonium salt and a lithium salt is added to the non-aqueous solvent to dissolve it.

[0035] Furthermore, storage elements using the electrolyte prepared herein are also included in the present invention. For example, an electric double layer capacitor comprises: a pair of polarized electrodes, a separator sandwiched between the electrodes, an electrolyte, and a container that seals them. A lithium ion capacitor comprises: a polarized positive electrode, a negative electrode capable of inserting / de-inserting lithium ions, an electrolyte, a separator sandwiched between the electrodes, and a container for storing them. A lithium ion secondary battery comprises: a positive electrode capable of inserting / de-inserting lithium ions, a negative electrode capable of inserting / de-inserting lithium ions, an electrolyte, a separator sandwiched between the electrodes, and a container for storing them.

[0036] As an example of a storage element, Figure 1 The structure of the nonaqueous electrolyte secondary battery will be described. Figure 1 This is a schematic perspective view of a partially cut-away rectangular nonaqueous electrolyte secondary battery.

[0037] The secondary battery comprises: a battery case 4 having a bottom and a square shape, an electrode group 1 and a non-aqueous electrolyte (not shown) housed in the battery case 4. The electrode group 1 comprises: a long strip-shaped negative electrode, a long strip-shaped positive electrode and a separator sandwiched therebetween. The electrode group 1 is formed by winding the negative electrode, the positive electrode and the separator around a flat winding core and pulling out the winding core.

[0038] One end of the negative electrode lead 3 is attached to the negative electrode collector of the negative electrode by welding or the like. One end of the positive electrode lead 2 is attached to the positive electrode collector of the positive electrode by welding or the like. The other end of the negative electrode lead 3 is electrically connected to the negative electrode terminal 6 provided on the sealing plate 5 via the gasket 7. The other end of the positive electrode lead 2 is electrically connected to the battery case 4 which also serves as the positive terminal. A resin frame is arranged on the upper part of the electrode group 1 to separate the electrode group 1 from the sealing plate 5 and to separate the negative electrode lead 3 from the battery case 4. The opening of the battery case 4 is sealed by the sealing plate 5.

[0039] In the present disclosure, as another embodiment, it includes the following selected from the formula (1):

[0040]

[0041] At least one compound selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene and fluorine-substituted products thereof.

[0042] Furthermore, in the present disclosure, as another embodiment, it includes a method selected from the formula (1):

[0043]

[0044] An electrolyte solution additive comprising at least one member selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene and fluorinated derivatives thereof.

[0045] [Example]

[0046] Hereinafter, the present disclosure will be specifically described based on Examples and Comparative Examples, but the present disclosure is not limited to the following Examples.

[0047] [Method for producing 1,3-diethyl-4-methyl-1-cyclobutene]

[0048] 1,3-Diethyl-4-methyl-1-cyclobutene is synthesized via a cyclobutene ring-forming reaction based on a [2+2] cycloaddition reaction of alkynes with alkenes.

[0049] In an inert gas atmosphere, dichloromethane (1.2 L) was added to [1,1-bis(diphenylphosphino)ferrocene]cobalt(II) dichloride (12.5 g, 0.023 mol) after heat drying, and the mixture was stirred at 0°C for 5 minutes. Then, trimethylaluminum-toluene solution (2M) (66.6 g, 0.462 mol) was slowly added, and the mixture was stirred at 0°C for 15 minutes. After the reaction vessel was carefully vented, 1-butyne gas was introduced in small amounts at a time while maintaining 0°C, and the mixture was stirred for 30 minutes. After the reaction solution was brought to -30°C, cis-2-pentene (32.4 g, 0.462 mol) was slowly added dropwise over 30 minutes, and the mixture was stirred at room temperature for 3 hours. The reaction solution was diluted with pentane, quenched in methanol, and then filtered through celite. The solvent was distilled off from the filtrate under reduced pressure. The obtained residue was purified by silica gel column chromatography (pentane 100%) to obtain 1,3-diethyl-4-methyl-1-cyclobutene (43.0 g, 0.346 mol) in a yield of 75%.

[0050] (Viscosity measurement)

[0051] The viscosity of 1,3-diethyl-4-methyl-1-cyclobutene synthesized as described above at room temperature (25°C) was measured using a viscometer RSM-MV1 manufactured by SMILECo. The viscosity was 0.49 mPa·s and 0.6 mPa·s or less. This value is lower than the viscosity of propylene carbonate, which is commonly used as a solvent for electrolyte, which is 2.5 mPa·s. In addition, diethyl carbonate and dimethyl carbonate are also frequently used as low-viscosity solvents, but their viscosities are 0.8 mPa·s and 0.6 mPa·s, respectively, which are lower than these.

[0052] Comparative Example 1

[0053] Triethylmethylammonium tetrafluoroborate was added to propylene carbonate so as to have a concentration of 1.0 mol / L to obtain an electrolyte solution for a capacitor.

[0054] Comparative Example 2

[0055] Triethylmethylammonium tetrafluoroborate was added to a solvent in which 90 parts by weight of propylene carbonate and 10 parts by weight of dimethyl carbonate were mixed so as to have a concentration of 1.0 mol / L, thereby obtaining an electrolyte solution for a capacitor.

[0056] 《Example 1》

[0057] Triethylmethylammonium tetrafluoroborate was added to a solvent in which 90 parts by weight of propylene carbonate and 10 parts by weight of 1,3-diethyl-4-methyl-1-cyclobutene were mixed so as to have a concentration of 1.0 mol / L, thereby obtaining an electrolyte solution for a capacitor.

[0058] <Fabrication of laminated battery cells>

[0059] Prepare an aluminum sheet with a width of 30 mm and a thickness of 20 μm as a current collector, and coat activated carbon with a thickness of 80 μm on both sides as an electrode. Next, cut the electrode into 20×72 mm, and weld the electrode lead wire on the surface of the aluminum of the current collector. A separator formed of cellulose with a thickness of 50 μm is sandwiched by a pair of electrodes and placed in a container made of aluminum laminated film, and an electrolyte is injected in a dry room to impregnate the electrode. After that, the container is sealed to make a laminated battery cell of a capacitor.

[0060] <Measurement of internal resistance>

[0061] A voltage of 3.0 V was applied to the prepared capacitor, and its internal resistance was measured at -30°C.

[0062] Table 1 shows the relative values ​​of the measured internal resistance values ​​of each laminated battery cell at -30°C and the internal resistance value of Comparative Example 1.

[0063] [Table 1]

[0064] Relative value with Comparative Example 1 Comparative Example 1 1.0 Comparative Example 2 0.94 Example 1 0.89

[0065] From the results in Table 1, it is understood that in Example 1 using 1,3-diethyl-4-methyl-1-cyclobutene, the internal resistance value is lower than that in Comparative Example 1 using only propylene carbonate.

[0066] Moreover, it can be seen that, as in the case of Comparative Example 2, the internal resistance value is also lower than that of the system in which dimethyl carbonate is added to propylene carbonate.

[0067] <Manufacturing of secondary batteries>

[0068] (negative electrode)

[0069] The negative electrode active material (graphite) was mixed with sodium carboxymethylcellulose (CMC-Na) and styrene-butadiene rubber (SBR) at a mass ratio of 97.5:1:1.5, and after adding water, a mixer (manufactured by PRIMIX Corporation, TKHIVISMIX) was used to stir the mixture to prepare a negative electrode mixture slurry. 2 The negative electrode mixture slurry was applied so that the mass of the negative electrode mixture became 190 g, and after the coating was dried, it was rolled to form a copper foil with a density of 1.5 g / cm 3 The negative electrode of the negative electrode mixture layer.

[0070] (positive electrode)

[0071] Lithium nickel composite oxide (LiNi 0.8 Co 0.18 Al 0.02 O2) was mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 95:2.5:2.5, and after adding N-methyl-2-pyrrolidone (NMP), a mixer (manufactured by PRIMIX Corporation, TKHIVISMIX) was used to stir to prepare a slurry of the positive electrode mixture. Next, the slurry of the positive electrode mixture was applied to the surface of the aluminum foil, and after the coating was dried, it was rolled to form a 3.6 g / cm2 film on both sides of the aluminum foil. 3 The positive electrode of the positive electrode mixture layer.

[0072] 《Comparative Example 3》

[0073] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 20:70:10 to prepare a non-aqueous electrolyte. LiPF6 was used as the lithium salt. The concentration of LiPF6 in the electrolyte was set to 1.2 mol / L.

[0074] 《Example 4》

[0075] Ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and 1,3-diethyl-4-methyl-1-cyclobutene were mixed in a volume ratio of 18:63:9:10 to prepare a non-aqueous electrolyte. LiPF6 was used as the lithium salt. The concentration of LiPF6 in the electrolyte was set to 1.2 mol / L.

[0076] The electrode group is prepared by installing a tab on each electrode, and winding the positive electrode and the negative electrode into a spiral shape with the tab located at the outermost periphery. The electrode group is embedded in an outer shell made of an aluminum laminate film, vacuum dried at 105°C for 2 hours, and then injected with a non-aqueous electrolyte to seal the opening of the outer shell to obtain a secondary battery.

[0077] <Measurement of discharge capacity (battery capacity)>

[0078] In the secondary battery prepared as described above, constant current charging was performed at a current of 0.3 It (800 mA) under a -5°C environment until the voltage reached 4.2 V, and then constant voltage charging was performed at a constant voltage of 4.2 V until the current reached 0.015 It (40 mA). Thereafter, constant current discharge was performed at a current of 0.3 It (800 mA) until the voltage reached 2.75 V. The discharge capacity at this time was determined as the battery capacity.

[0079] Table 2 shows the relative values ​​of the battery capacity at -5°C of each secondary battery measured in this way and the battery capacity of Comparative Example 3.

[0080] [Table 2]

[0081] Relative value with Comparative Example 3 Comparative Example 3 1.0 Example 4 1.1

[0082] The results in Table 2 show that in Example 4 using 1,3-diethyl-4-methyl-1-cyclobutene, the battery capacity is larger than that in Comparative Example 3 using an electrolyte solution not containing such a compound.

[0083] It is understood that by using the electrolyte material according to the present disclosure, the internal resistance of the element can be reduced and the operating characteristics at low temperatures can be improved.

[0084] "appendix"

[0085] According to the description of the above embodiments, the following technology is disclosed.

[0086] (Technology 1)

[0087] An electrolyte solution comprising: a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent,

[0088] The non-aqueous solvent comprises a first compound,

[0089] The first compound is at least one selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene represented by the following formula (1) and fluorine-substituted products thereof.

[0090]

[0091] (Technique 2)

[0092] The electrolyte solution according to technology 1, wherein the content of the first compound in the nonaqueous solvent is 5 mass % or more and 80 mass % or less.

[0093] (Technique 3)

[0094] The electrolyte solution according to the technique 1 or 2, wherein the nonaqueous solvent further contains a second compound selected from the group consisting of cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic carbonates, chain carbonates, and cyclic sulfone compounds.

[0095] (Technique 4)

[0096] The electrolytic solution according to any one of techniques 1 to 3, wherein the electrolyte salt includes at least one selected from the group consisting of quaternary ammonium salts and lithium salts.

[0097] (Technique 5)

[0098] The electrolyte according to technology 4, wherein the quaternary ammonium salt comprises a salt formed of a tetraalkylammonium ion and an anion.

[0099] (Technique 6)

[0100] The electrolyte according to technology 5, wherein the tetraalkylammonium ion is at least one selected from the group consisting of tetramethylammonium ion, trimethylethylammonium ion, triethylmethylammonium ion, tetraethylammonium ion, tetrabutylammonium ion and diethyldimethylammonium ion.

[0101] (Technique 7)

[0102] The electrolyte according to technology 5 or 6, wherein the anion is selected from Cl - 、BF4 - PF6 - 、ClCO4 - CF3SO3 - 、N(FSO2)2 - 、N(CF3SO2)2 - 、N(C2F5SO2)2 - and C(CF3SO2)3 - At least one of the group consisting of.

[0103] (Technology 8)

[0104] The electrolyte according to technique 4, wherein the quaternary ammonium salt is triethylmethylammonium tetrafluoroborate,

[0105] The aforementioned lithium salt is LiPF6.

[0106] (Technique 9)

[0107] The electrolytic solution according to any one of techniques 1 to 8, wherein the concentration of the electrolyte salt in the electrolytic solution is 0.1 mol / L or more and 3.0 mol / L or less.

[0108] (Technology 10)

[0109] The electrolytic solution according to any one of techniques 1 to 8, wherein the concentration of the electrolyte salt in the electrolytic solution is 0.5 mol / L or more and 2.0 mol / L or less.

[0110] (Technology 11)

[0111] A power storage element comprising the electrolytic solution according to any one of techniques 1 to 10.

[0112] (Technology 12)

[0113] At least one compound selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene represented by the following formula (1) and fluorine-substituted products thereof.

[0114]

[0115] (Technology 13)

[0116] An electrolyte additive comprising at least one selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene represented by the following formula (1) and fluorine-substituted products thereof.

[0117]

[0118] Industrial Applicability

[0119] The electrolyte solution disclosed in the present invention is used in a storage element such as a non-aqueous electrolyte capacitor and a non-aqueous electrolyte secondary battery. The storage element disclosed in the present invention is useful as a main power source for mobile communication equipment, portable electronic equipment, and the like.

[0120] Description of Reference Numerals

[0121] 1 electrode group

[0122] 2 Positive lead

[0123] 3 Negative lead

[0124] 4Battery housing

[0125] 5 Sealing plate

[0126] 6 Negative terminal

[0127] 7 Gaskets.

Claims

1. An electrolyte solution comprising: a non-aqueous solvent, and an electrolyte salt dissolved in the non-aqueous solvent, The non-aqueous solvent comprises a first compound, The first compound is at least one selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene represented by the following formula (1) and fluorine-substituted products thereof, 2. The electrolyte according to claim 1, wherein The content of the first compound in the nonaqueous solvent is 5 mass % or more and 80 mass % or less.

3. The electrolyte according to claim 1, wherein The nonaqueous solvent further contains a second compound selected from the group consisting of cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic carbonate esters, chain carbonate esters, and cyclic sulfone compounds.

4. The electrolyte according to claim 1, wherein The electrolyte salt includes at least one selected from the group consisting of quaternary ammonium salts and lithium salts.

5. The electrolyte according to claim 4, wherein The quaternary ammonium salt includes a salt formed from a tetraalkylammonium ion and an anion.

6. The electrolyte according to claim 5, wherein The tetraalkylammonium ion is at least one selected from the group consisting of a tetramethylammonium ion, a trimethylethylammonium ion, a triethylmethylammonium ion, a tetraethylammonium ion, a tetrabutylammonium ion, and a diethyldimethylammonium ion.

7. The electrolyte according to claim 5, wherein The anion is selected from Cl - 、BF4 - PF6 - 、ClCO4 - CF3SO3 - 、N(FSO2)2 - 、N(CF3SO2)2 - 、N(C2F5SO2)2 - and C(CF3SO2)3 - At least one of the group consisting of.

8. The electrolyte according to claim 4, wherein The quaternary ammonium salt is triethylmethylammonium tetrafluoroborate, The lithium salt is LiPF6.

9. The electrolyte according to claim 4, wherein In the electrolytic solution, a concentration of the electrolyte salt is 0.1 mol / L or more and 3.0 mol / L or less.

10. The electrolyte according to claim 4, wherein In the electrolytic solution, a concentration of the electrolyte salt is 0.5 mol / L or more and 2.0 mol / L or less. 11 . An electric storage element comprising the electrolytic solution according to claim 1 .

12. At least one compound selected from the group consisting of 1,3-diethyl-4-methyl-1-cyclobutene represented by the following formula (1) and fluorine-substituted products thereof,

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