JP7051422B2 - Non-aqueous electrolyte and storage device using it - Google Patents

Description

The present invention relates to a non-aqueous electrolytic solution capable of suppressing a well-balanced electrochemical characteristic, particularly gas generation during high-temperature continuous charging and battery voltage drop during high-temperature discharge storage, and a power storage device using the same.

In recent years, power storage devices, particularly lithium secondary batteries, have been widely used for small electronic devices such as mobile phones and notebook personal computers, electric vehicles, and power storage. Recently, among lithium secondary batteries, the proportion of laminated pouch type batteries has been increasing from the viewpoint of increasing the capacity per mass and volume. Therefore, gas swelling due to decomposition of the non-aqueous electrolytic solution often becomes a problem, and development of a non-aqueous electrolytic solution that suppresses gas generation is required.
In the present specification, the term lithium secondary battery is used as a concept including a so-called lithium ion secondary battery.

Patent Document 1 describes that a non-aqueous electrolytic solution containing a phosphoric acid ester, a bisphosphonic acid ester and / or a host acid ester has flame retardancy (self-extinguishing property) and is excellent in charge / discharge characteristics. Is disclosed.

Japanese Patent Application Laid-Open No. 2002-28061

The present inventors have studied in detail the performance of the non-aqueous electrolyte solution of the prior art. As a result, the non-aqueous electrolytic solution containing the bisphosphonic acid ester had the effect of suppressing gas generation during continuous high-temperature charging, but the conventionally disclosed bisphosphonic acid ester had the effect of suppressing gas generation during continuous high-temperature storage. We confirmed the existence of the problem that the battery voltage drops. It is known that when the battery voltage drops extremely, the copper foil generally used as a negative electrode current collector elutes into the electrolytic solution, which adversely affects the battery characteristics.
The present invention provides a non-aqueous electrolytic solution that suppresses both gas generation when a power storage device is continuously charged at a high temperature and a decrease in battery voltage when stored at a high temperature in a discharged state in a well-balanced manner, and a power storage device using the same. Is.

As a result of diligent research to solve the above problems, the present inventors have an effect of suppressing gas generation during continuous high-temperature charging in a non-aqueous electrolytic solution containing a specific bisphosphonic acid ester, while having an effect. The present invention has been completed by finding that it is possible to overcome the problem that the battery voltage drops during high-temperature storage in a discharged state.

That is, the present invention provides the following (1) and (2).

(1) In a non-aqueous electrolytic solution in which an electrolyte salt is dissolved in a non-aqueous solvent, the non-aqueous electrolytic solution contains at least one compound represented by the following general formula (I). Electrolyte.

（Ｒ^１～Ｒ^４はそれぞれ独立に、炭素数１～４のアルキル基を示し、Ｒ^５及びＲ^６はそれぞれ独立に、炭素数１～４のアルキル基を示す。）

(R ¹ to R ⁴ independently indicate an alkyl group having 1 to 4 carbon atoms, and R ⁵ and R ⁶ independently indicate an alkyl group having 1 to 4 carbon atoms.)

(2) In a power storage device including a positive electrode, a negative electrode, and a non-aqueous electrolytic solution in which an electrolyte salt is dissolved in a non-aqueous solvent, the non-aqueous electrolytic solution is the non-aqueous electrolytic solution according to (1) above. A characteristic power storage device.

According to the present invention, it is possible to provide a non-aqueous electrolytic solution capable of suppressing gas generation during high-temperature continuous charging and voltage drop during high-temperature discharge storage in a well-balanced manner, and a storage device such as a lithium battery using the non-aqueous electrolytic solution. ..

The present invention relates to a non-aqueous electrolytic solution and a power storage device using the same.

[Non-water electrolyte]
The non-aqueous electrolyte solution of the present invention is a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent, and is characterized by containing the compound represented by the general formula (I) in the non-aqueous electrolyte solution. do.

The reason why the non-aqueous electrolytic solution of the present invention can suppress gas generation during continuous high-temperature continuous charging and voltage drop during high-temperature storage in a discharged state in a well-balanced manner is not always clear, but it is considered as follows.
The methylene diphosphonate ester such as tetraethyl methylene diphosphonate described in Patent Document 1 has two oxygen atoms in one molecule that form a double bond with a phosphorus atom. Since these two oxygen atoms can form a six-membered ring by coordinating with a metal atom on the surface of the positive electrode inside the power storage device and are relatively stable, a cyclic carbonate or a cyclic carbonate generally used as a solvent for the power storage device can be used. It becomes difficult for the chain carbonate to come into contact with the active point on the surface of the positive electrode. As a result, it is considered that the cyclic carbonate and the chain carbonate can be suppressed from being oxidatively decomposed at the positive electrode, and the gas generation derived from the carbonate solvent decomposition can be suppressed.
However, the present inventors have confirmed that in the non-aqueous electrolytic solution containing the diphosphonic acid ester having methylene described in Patent Document 1, when the power storage device is stored at a high temperature in a discharged state, the battery voltage drops.
As a result of diligent research by the present inventors, it has been found that this problem is likely to be caused by the high activity of the hydrogen atom in the methylene portion adjacent to the electron-withdrawing phosphate ester. ..
Therefore, this problem is solved by using a non-aqueous electrolytic solution containing the compound represented by the general formula (I) in which the hydrogen atom of the methylene moiety is substituted with an alkyl group instead of the conventional methylene diphosphonic acid ester compound. Therefore, they have invented a non-aqueous electrolytic solution capable of suppressing gas generation during continuous charging and battery voltage drop during high-temperature storage in a discharged state in a well-balanced manner.

The compound contained in the non-aqueous electrolytic solution of the present invention is represented by the following general formula (I).

（Ｒ^１～Ｒ^４はそれぞれ独立に、炭素数１～４のアルキル基を示し、Ｒ^５及びＲ^６はそれぞれ独立に、炭素数１～４のアルキル基を示す。）

(R ¹ to R ⁴ independently indicate an alkyl group having 1 to 4 carbon atoms, and R ⁵ and R ⁶ independently indicate an alkyl group having 1 to 4 carbon atoms.)

When R ¹ to R ⁴ and R ⁵ and R ⁶ in the general formula (I) are these alkyl groups, the non-aqueous electrolytic solution of the present invention is effective during high temperature continuous charging. It is possible to achieve both suppression of gas generation in the above and suppression of battery voltage drop during high temperature storage in a discharged state.

The R ¹ to R ⁴ independently represent an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 3 carbon atoms is preferable, and an alkyl group having 1 to 2 carbon atoms is more preferable.

It is more preferable that all of R ¹ to R ⁴ have the same alkyl group.

Specific examples of R ¹ to R ⁴ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group. Among them, a methyl group, an ethyl group, an n-propyl group, or an iso-propyl group is preferable, and a methyl group or an ethyl group is particularly preferable.

The R ⁵ and R ⁶ independently represent an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 3 carbon atoms is preferable, and an alkyl group having 1 to 2 carbon atoms is more preferable.

The same alkyl group is more preferable for R ⁵ and R ⁶ .

Specific examples of the R ⁵ and R ⁶ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group. Among them, a methyl group, an ethyl group, an n-propyl group, or an iso-propyl group is preferable, and a methyl group or an ethyl group is particularly preferable.

Specific preferred examples of the general formula (I) include the following compounds.

Among the above compounds, tetramethylpropan-2,2-diylbis (phosphonate) (compound A1), tetramethylpentane-3,3-diylbis (phosphonate) (compound A2), tetraethyl propane-2,2-diylbis (phosphonate). (Compound A3), Tetraethyl pentane-3,3-diylbis (Phoenate) (Compound A4), Tetrapropyl Propane-2,2-Diylbis (Phononate) (Compound A5), Tetrapropyl Pentane-3,3-Diylbis (Phononate) (Compound A6), tetraisopropylpropan-2,2-diylbis (phosphonate) (Compound A7), or tetraisopropylpentane-3,3-diylbis (phosphonate) (Compound A8) is particularly preferred. More preferably, tetramethyl propane-2,2-diylbis (phosphonate) (Compound A1), tetramethylpentane-3,3-diylbis (phosphonate) (Compound A2), tetraethyl propane-2,2-diylbis (phosphonate) ( Examples thereof include compound A3) or tetraethylpentane-3,3-diylbis (phosphonate) (compound A4), and these compounds are suitable for reducing steric damage to the alkyl group and acting on the electrode surface.

Although the range of substituents of the diphosphonic acid ester represented by the general formula (I) has been described above, R ¹ to R ⁴ in the general formula (I) are independently alkyl groups having 1 to 4 carbon atoms. If R ⁵ and R ⁶ are independently alkyl groups having 1 to 4 carbon atoms, the non-aqueous electrolytic solution of the present invention can generate gas during continuous charging and can be stored at a high temperature in a discharged state. It is considered that the decrease in battery voltage can be suppressed in a well-balanced manner.

In the non-aqueous electrolytic solution of the present invention, the content of the compound represented by the general formula (I) is preferably 0.001 to 10% by mass in the non-aqueous electrolytic solution. The content is preferably 0.05% by mass or more, more preferably 0.3% by mass or more in the non-aqueous electrolytic solution. The upper limit thereof is preferably 8% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less.

In the non-aqueous electrolyte solution of the present invention, the cycle characteristics can be improved by combining the compound represented by the general formula (I) with the non-aqueous solvent described below, the electrolyte salt, and other additives. It exerts a peculiar effect that the effect of suppressing gas generation is synergistically improved.

[Non-aqueous solvent]
First, in the present specification, the "solvent" refers to a substance for dissolving a solute.
The non-aqueous solvent used in the non-aqueous electrolytic solution of the present invention preferably includes one or more selected from cyclic carbonates, chain esters, lactones, ethers, and amides. Since the electrochemical properties at high temperature are synergistically improved, it is preferable to contain a chain ester, further preferably to contain a chain carbonate, and most preferably to contain both a cyclic carbonate and a chain carbonate. ..

The term "chain ester" is used as a concept including a chain carbonate and a chain carboxylic acid ester.
Further, "chain carbonate" is defined as a linear alkyl carbonate compound.

As the cyclic carbonate, ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 4-fluoro-1,3-dioxolane-2-one (FEC), trans or Sis-4,5-difluoro-1,3-dioxolane-2-one (hereinafter, both are collectively referred to as "DFEC"), vinylene carbonate (VC), vinylethylene carbonate (VEC), and 4-ethynyl-1. , 3-Dioxolane-2-one (EEC), one or more selected from the group is preferably used, such as ethylene carbonate, propylene carbonate, 4-fluoro-1,3-dioxolane-2-one, vinylene. One or more selected from the group consisting of carbonate and 4-ethynyl-1,3-dioxolane-2-one (EEC) is more preferable.

Further, when at least one of the unsaturated bonds such as the carbon-carbon double bond or the carbon-carbon triple bond or the cyclic carbonate having a fluorine atom is used, the cycle characteristics can be improved and gas generation can be further suppressed. Therefore, it is preferable to contain both a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond and a cyclic carbonate having a fluorine atom. The cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond is more preferably VC, VEC or EEC, and the cyclic carbonate having a fluorine atom is further preferably FEC or DFEC.

The content of the cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond is preferably 0.07% by volume or more, more preferably 0, based on the total volume of the non-aqueous solvent. It is 2% by volume or more, more preferably 0.7% by volume or more, and the upper limit thereof is preferably 7% by volume or less, more preferably 4% by volume or less, still more preferably 2.5% by volume or less. This is preferable because the cycle characteristics can be further improved without impairing the Li ion permeability and the gas generation can be suppressed.

The content of the cyclic carbonate having a fluorine atom is preferably 0.07% by volume or more, more preferably 4% by volume or more, still more preferably 6% by volume or more, and the content thereof with respect to the total volume of the non-aqueous solvent. When the upper limit is preferably 35% by volume or less, more preferably 25% by volume or less, and further 15% by volume or less, the cycle characteristics can be further improved without impairing the Li ion permeability, and gas generation is suppressed. It is preferable because it can be done.

When the non-aqueous solvent contains both a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond and a cyclic carbonate having a fluorine atom, carbon-with respect to the content of the cyclic carbonate having a fluorine atom. The content of the cyclic carbonate having an unsaturated bond such as a carbon double bond or a carbon-carbon triple bond is preferably 0.2% by volume or more, more preferably 3% by volume or more, still more preferably 7% by volume or more. When the upper limit is preferably 40% by volume or less, more preferably 30% by volume or less, and further 15% by volume or less, the cycle characteristics can be improved without impairing the Li ion permeability, and gas generation can be generated. It is particularly preferable because it can be suppressed.

Further, when the non-aqueous solvent contains both an ethylene carbonate and a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond, the cycle characteristics can be improved and gas generation can be suppressed. Preferably, the content of the cyclic carbonate having an unsaturated bond such as an ethylene carbonate and a carbon-carbon double bond or a carbon-carbon triple bond is preferably 3% by volume or more, more preferably 3% by volume, based on the total volume of the non-aqueous solvent. It is 5% by volume or more, more preferably 7% by volume or more, and the upper limit thereof is preferably 45% by volume or less, more preferably 35% by volume or less, still more preferably 25% by volume or less.

One type of these solvents may be used, and when two or more types are used in combination, the cycle characteristics can be improved and gas generation can be suppressed, which is preferable, and three or more types are used in combination. Is particularly preferred. Suitable combinations of these cyclic carbonates include EC and PC, EC and VC, PC and VC, VC and FEC, EC and FEC, PC and FEC, FEC and DFEC, EC and DFEC, PC and DFEC, VC and DFEC. , VEC and DFEC, VC and EEC, EC and EEC, EC and PC and VC, EC and PC and FEC, EC and VC and FEC, EC and VC and VEC, EC and VC and EEC, EC and EEC and FEC, PC And VC and FEC, EC and VC and DFEC, PC and VC and DFEC, EC and PC and VC and FEC, or EC and PC and VC and DFEC, and the like are preferable. Among the above combinations, EC and VC, EC and FEC, PC and FEC, EC and PC and VC, EC and PC and FEC, EC and VC and FEC, EC and VC and EEC, EC and EEC and FEC, PC and A combination of VC and FEC, or EC and PC and VC and FEC is more preferable.

As the chain ester, one or more asymmetric chain carbonates selected from methyl ethyl carbonate (MEC), methyl propyl carbonate (MPC), methyl butyl carbonate, and ethyl propyl carbonate, dimethyl carbonate (DMC), diethyl. One or more symmetric chain carbonates selected from the group consisting of carbonate (DEC), dipropyl carbonate, and dibutyl carbonate, pivalic acid esters such as methyl pivalate, ethyl pivalate, propyl pivalate, methyl propionate. , One or more chain carboxylic acid esters selected from the group consisting of ethyl propionate, propyl propionate, methyl acetate, and ethyl acetate (EA).

Among the chain esters, a chain having a methyl group selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, methyl propionate, methyl acetate, and ethyl acetate (EA). Esters are preferred, and chain carbonates having a methyl group are particularly preferred.

The content of the chain ester in the non-aqueous solvent used in the non-aqueous electrolyte solution of the present invention is not particularly limited, but is preferably used in the range of 60 to 90% by volume with respect to the total volume of the non-aqueous solvent. If the content is 60% by volume or more, the viscosity of the non-aqueous electrolytic solution does not become too high, and if it is 90% by volume or less, the electric conductivity of the non-aqueous electrolytic solution is less likely to decrease and the cycle characteristics are less likely to deteriorate. Therefore, it is preferably in the above range.

The ratio of the cyclic carbonate to the chain ester is preferably 10:90 to 45:55, and 15:85 to 40:60 for the cyclic carbonate: chain ester (volume ratio) from the viewpoint of improving the electrochemical properties at high temperature. Is more preferable, and 20:80 to 35:65 is particularly preferable.

Other non-aqueous solvents include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran and 1,4-dioxane, chains such as 1,2-dimethoxyethane, 1,2-diethoxyethane and 1,2-dibutoxyetane. Suitable examples thereof include one or more selected from amides such as ether, dimethylformamide, sulfones such as sulfolane, and lactones such as γ-butyrolactone (GBL), γ-valerolactone and α-angelica lactone.

The other non-aqueous solvents mentioned above are usually mixed and used in order to achieve appropriate physical characteristics. The combination preferably includes, for example, a combination of a cyclic carbonate, a chain ester and a lactone, a combination of a cyclic carbonate, a chain ester and an ether, and the like, and a combination of a cyclic carbonate, a chain ester and a lactone is more preferable. Among the lactones, it is more preferable to use γ-butyrolactone (GBL).

The content of the other non-aqueous solvent is usually 1% or more, preferably 2% or more, and usually 40% or less, preferably 30% or less, more preferably 20%, based on the total volume of the non-aqueous solvent. It is as follows.

It is preferable to add other additives to the non-aqueous electrolyte solution for the purpose of further improving the cycle characteristics.
Specific examples of other additives include the following compounds (A) to (I).

(A) One or more nitriles selected from acetonitrile, propionitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, and sebaconitrile.

(B) Aromatic compounds having a branched alkyl group such as cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, or 1-fluoro-4-tert-butylbenzene, biphenyl, turphenyl (o-, m-). , P-form), fluorobenzene, methylphenyl carbonate, ethylphenyl carbonate, or aromatic compounds such as diphenyl carbonate.

(C) Select from methyl isocyanate, ethyl isocyanate, butyl isocyanate, phenyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylenedi isocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate. One or more isocyanate compounds.

(D) 2-Propinyl Methyl Carbonate, Acetate 2-Propinyl, Formic Acid 2-Propinyl, Methacrylate 2-Propinyl, Methanesulfonic Acid 2-Propinyl, Vinyl Sulfonic Acid 2-Propinyl, 2- (Methanesulfonyloxy) Propionic Acid 2- One or more triple bond-containing compounds selected from propynyl, di (2-propynyl) oxalate, 2-butin-1,4-diyldimethanesulfonate, and 2-butin-1,4-diyldiformate.

(E) 1,3-Propane sultone, 1,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-propensultone, or 2,2-dioxide-1,2-oxathiolane-4- Sultone such as ylacetate, cyclic sulphite such as ethylene sulphite, cyclic sulphate such as ethylene sulphate, butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate, methylenemethanedisulfonate, etc. Sulfonate of, and one or more S = O groups selected from vinyl sulfone compounds such as divinyl sulfone, 1,2-bis (vinylsulfonyl) ethane, or bis (2-vinylsulfonylethyl) ether. Compound.

The type of the cyclic acetal compound (F) is not particularly limited as long as it is a compound having an "acetal group" in the molecule. Specifically, a cyclic acetal compound such as 1,3-dioxolane, 1,3-dioxane, or 1,3,5-trioxane.

(G) One or two phosphorus-containing compounds selected from ethyl 2- (diethoxyphosphoryl) acetate and 2-propynyl 2- (diethoxyphosphoryl) acetate.

The type of the (H) carboxylic acid anhydride is not particularly limited as long as it is a compound having an "C (= O) -OC (= O) group" in the molecule. Specifically, chain carboxylic acid anhydrides such as acetic anhydride and propionic anhydride, succinic anhydride, maleic anhydride, 3-allyl succinic anhydride, glutaric anhydride, itaconic anhydride, or 3-sulfo-. Cyclic acid anhydrides such as propionic anhydride.

(I) The type of the phosphazene compound is not particularly limited as long as it is a compound having an "N = PN group" in the molecule. Specifically, a cyclic phosphazene compound such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, or ethoxyheptafluorocyclotetraphosphazene.

Among the above, it is preferable to include at least one selected from (A) nitrile, (B) aromatic compound, and (C) isocyanate compound because the electrochemical properties at high temperature are further improved.

Among the nitriles (A), one or more selected from succinonitrile, glutaronitrile, adiponitrile, and pimeronitrile are more preferable.

(B) Among aromatic compounds, one or two selected from biphenyl, terphenyl (o-, m-, p-form), fluorobenzene, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene. The above is more preferable, and one or more selected from biphenyl, o-terphenyl, fluorobenzene, cyclohexylbenzene, and tert-amylbenzene are particularly preferable.

Among the isocyanate compounds (C), one or more selected from hexamethylene diisocyanate, octamethylene diisocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate are more preferable.

The content of the compounds (A) to (C) is preferably 0.01 to 7% by mass in the non-aqueous electrolytic solution. In this range, the film is sufficiently formed without becoming too thick, the cycle characteristics can be improved, and gas generation can be suppressed. The content is more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and the upper limit thereof is more preferably 5% by mass or less, further preferably 3% by mass or less in the non-aqueous electrolytic solution. ..

Further, a cyclic or chain S = O group-containing compound selected from (D) triple bond-containing compound, (E) sulton, cyclic sulfate, sulfonic acid ester, and vinyl sulfone, (F) cyclic acetal compound, (G). It is preferable to include a phosphorus-containing compound, (H) cyclic acid anhydride, and (I) cyclic phosphazene compound because the cycle characteristics can be improved and gas generation can be suppressed.

(D) Examples of the triple bond-containing compound include 2-propynyl methyl carbonate, 2-propynyl methacrylate, 2-propynyl methanesulfonic acid, 2-propynyl vinylsulfonic acid, di (2-propynyl) oxalate, and 2-butin-1. , 4-Diyl Dimethanesulfonate, preferably one or more, preferably 2-propinyl methanesulfonic acid, 2-propinyl vinylsulfonic acid, di (2-propynyl) oxalate, and 2-butin-1,4-. One or more selected from diyldimethanesulfonates are more preferred.

(E) A cyclic or chain S = O group-containing compound selected from sultone, cyclic sulphite, cyclic sulfate, sulfonic acid ester, and vinyl sulfone (provided as a triple bond-containing compound and any of the above general formulas). It is preferable to use (does not include the specific compound to be used).

Examples of the cyclic S = O group-containing compound include 1,3-propane sultone, 1,3-butane sultone, 1,4-butane sultone, 2,4-butane sultone, 1,3-propene sultone, and 2,2-dioxide-. One or more selected from 1,2-oxathiolan-4-yl acetate, methylene methanedisulfonate, ethylene sulphite, and ethylene sulphate are preferably used.

Examples of the chain S = O group-containing compound include butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate, dimethylmethanedisulfonate, pentafluorophenylmethanesulfonate, and divinylsulfone. And one or more selected from bis (2-vinylsulfonylethyl) ethers are preferred.

Among the cyclic or chain S = O group-containing compounds, 1,3-propanesulfone, 1,4-butanesulfone, 2,4-butanesulfone, 2,2-dioxide-1,2-oxathiolan-4-yl acetate. , Ethylene sulphate, pentafluorophenyl methanesulfonate, and one or more selected from divinyl sulfone are more preferred.

As the cyclic acetal compound (F), 1,3-dioxolane or 1,3-dioxane is preferable, and 1,3-dioxane is more preferable.

As the phosphorus-containing compound (G), ethyl 2- (diethoxyphosphoryl) acetate or 2-propynyl 2- (diethoxyphosphoryl) acetate is preferable, and 2-propynyl 2- (diethoxyphosphoryl) acetate is more preferable.

As the cyclic acid anhydride, succinic anhydride, maleic anhydride, or 3-allyl succinic anhydride is preferable, and succinic anhydride or 3-allyl succinic anhydride is more preferable.

(I) As the cyclic phosphazene compound, a cyclic phosphazene compound such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, or phenoxypentafluorocyclotriphosphazene is preferable, and methoxypentafluorocyclotriphosphazene or ethoxypentafluorocyclocyclo Triphosphazene is more preferred.

The content of the compounds (D) to (I) is preferably 0.001 to 5% by mass in the non-aqueous electrolytic solution. In this range, the film is sufficiently formed without becoming too thick, the cycle characteristics can be further improved, and gas generation can be suppressed. The content is more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, and the upper limit thereof is more preferably 3% by mass or less, further preferably 2% by mass or less in the non-aqueous electrolytic solution. ..

Further, for the purpose of further improving the electrochemical properties at high temperature, the non-aqueous electrolyte solution further contains a lithium salt having a oxalic acid skeleton, a lithium salt having a phosphoric acid skeleton, and a lithium salt having an S = O group. It preferably contains one or more selected lithium salts.
Specific examples of the lithium salt include lithium bis (oxalat) borate [LiBOB], lithium difluoro (oxalat) borate [LiDFOB], lithium tetrafluoro (oxalat) phosphate [LiTFOP], and lithium difluorobis (oxalat) phosphate [LiDFOP]. Lithium salt having at least one oxalic acid skeleton selected from, lithium salt having a phosphoric acid skeleton such as LiPO ₂ F ₂ and Li ₂ PO ₃ F, lithium trifluoro ((methanesulfonyl) oxy) borate [LiTFMSB], Select from Lithium Pentafluoro ((methanesulfonyl) oxy) phosphate [LiPFMSP], Lithium Methyl Sulfate [LMS], Lithium Ethyl Sulfate [LES], Lithium 2,2,2-Trifluoroethyl Sulfate [LFES], and FSO ₃ Li Lithium salts having one or more S = O groups are preferably mentioned, and lithium salts selected from LiBOB, LiDFOB, LiTFOP, LiDFOP, LiPO ₂ F ₂ , LiTFMSB, LMS, LES, LFES, and FSO ₃ Li can be used. It is more preferable to include it.

The proportion of the lithium salt in the non-aqueous solvent is preferably 0.001 M or more and 0.5 M or less. Within this range, the cycle characteristics can be further improved and gas generation can be suppressed. It is preferably 0.01 M or more, more preferably 0.03 M or more, and particularly preferably 0.04 M or more. The upper limit is more preferably 0.4 M or less, and particularly preferably 0.2 M or less. (However, M indicates mol / L.)

(Electrolyte salt)
Preferred examples of the electrolyte salt used in the present invention include the following lithium salts.
Lithium salts include inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiN (SO ₂ F) ₂ [LiFSI], LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiCF ₃ SO ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₃ (C ₂ F ₅ ) ₃ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (iso-C ₃ F ₇ ) ₃ , Lithium salts containing chain-like fluoroalkyl groups such as LiPF ₅ (iso-C ₃ F ₇ ), (CF ₂ ) ₂ (SO ₂ ) ₂ NLi, (CF ₂ ) ₃ (SO ₂ ) ₂ Lithium salts having a cyclic fluorinated alkylene chain such as NLi are preferably mentioned, and at least one lithium salt selected from these is preferably mentioned, and one or more of these are preferably mixed. Can be used.
Among these, one or more selected from LiPF ₆ , LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , and LiN (SO ₂ F) ₂ [LiFSI]. Is preferable, and it is most preferable to use LiPF ₆ . The concentration of the electrolyte salt is usually preferably 0.3 M or more, more preferably 0.7 M or more, still more preferably 1.1 M or more with respect to the above-mentioned non-aqueous solvent. The upper limit thereof is preferably 2.5 M or less, more preferably 2.0 M or less, and even more preferably 1.6 M or less.
In addition, a suitable combination of these electrolyte salts includes LiPF ₆ , and at least one lithium selected from LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ F) ₂ [LiFSI]. It is preferable that the salt is contained in the non-aqueous electrolyte solution, and when the ratio of the lithium salt other than LiPF ₆ in the non-aqueous solvent is 0.001 M or more, the cycle characteristics are improved and gas is generated. The suppressive effect is also enhanced. If it is 1.0 M or less, there is little concern that the cycle characteristics will deteriorate, which is preferable. It is preferably 0.01 M or more, particularly preferably 0.03 M or more, and most preferably 0.04 M or more. The upper limit is preferably 0.8 M or less, more preferably 0.6 M or less, and particularly preferably 0.4 M or less.

[Manufacturing of non-aqueous electrolyte solution]
The non-aqueous electrolyte solution of the present invention is prepared by, for example, mixing the above-mentioned non-aqueous solvent and adding the above-mentioned electrolyte salt and the compound represented by the general formula (I) to the above-mentioned non-aqueous electrolyte solution. Obtainable.
At this time, it is preferable that the compound added to the non-aqueous solvent and the non-aqueous electrolytic solution to be used is purified in advance within a range that does not significantly reduce the productivity, and has as few impurities as possible.

The non-aqueous electrolyte solution of the present invention can be used for the following first to fourth power storage devices, and as the non-aqueous electrolyte, not only a liquid one but also a gelled one can be used. Further, the non-aqueous electrolyte solution of the present invention can also be used for a solid polymer electrolyte. Of these, it is preferably used for a first power storage device (that is, for a lithium battery) or a fourth power storage device (that is, for a lithium ion capacitor) that uses a lithium salt as an electrolyte salt, and is preferably used for a lithium battery. More preferably, it is most suitable for use as a lithium secondary battery.

[First power storage device (lithium battery)]
The lithium secondary battery, which is the first power storage device of the present invention, comprises the non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a positive electrode, a negative electrode, and a non-aqueous solvent. Components other than the non-aqueous electrolyte solution, such as positive electrodes and negative electrodes, can be used without particular limitation.
For example, as the positive electrode active material for a lithium secondary battery, a composite metal oxide with lithium containing one or more selected from the group consisting of cobalt, manganese, and nickel is used. These positive electrode active materials can be used alone or in combination of two or more.
Examples of such a lithium composite metal oxide include LiCoO ₂ , LiCo _1-x M _x O ₂ (where M is Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Zn, and One or more elements selected from Cu, 0.001 ≤ x ≤ 0.05), LiMn ₂ O ₄ , LiNiO ₂ , LiCo _1-x Ni _x O ₂ (0.01 <x <1), LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 Mn _0.3 O ₂ , LiNi _0.8 Mn _0.1 Co _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , Li ₂ MnO ₃ and LiMO ₂ (M is a transition metal such as Co, Ni, Mn, Fe), and LiNi _1/2 Mn _3/2 . One or more kinds selected from _O4 are preferably mentioned, and two or more kinds are more preferable. Further, LiCoO ₂ and LiMn ₂ O ₄ , LiCoO ₂ and LiNiO ₂ , and LiMn ₂ O ₄ and LiNiO ₂ may be used in combination.

When a lithium composite metal oxide operating at a high charging voltage is used, the cycle characteristics tend to deteriorate due to the reaction with the electrolytic solution during charging, but the lithium secondary battery according to the present invention suppresses the deterioration of these electrochemical characteristics. can do.
In particular, in the case of a positive electrode active material containing Ni, the catalytic action of Ni causes decomposition of the non-aqueous solvent on the surface of the positive electrode, and the resistance of the battery tends to increase. In particular, the electrochemical characteristics tend to deteriorate in a high temperature environment, but the lithium secondary battery according to the present invention is preferable because it can suppress the deterioration of these electrochemical characteristics. In particular, when the ratio of the atomic concentration of Ni to the atomic concentration of all transition metal elements in the positive electrode active material exceeds 30 atomic%, the above effect becomes remarkable, and 50 atomic% or more is more preferable. , 75% or more is particularly preferable. Specifically, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.8 Mn _0.1 Co _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ and the like are preferably mentioned.

Further, a lithium-containing olivine-type phosphate can also be used as the positive electrode active material. In particular, a lithium-containing olivine-type phosphate containing at least one selected from iron, cobalt, nickel and manganese is preferable. Specific examples thereof include LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMnPO ₄ , and the like.
Some of these lithium-containing olivine-type phosphates may be replaced with other elements, and some of iron, cobalt, nickel and manganese may be replaced with Co, Mn, Ni, Mg, Al, B, Ti, V and Nb. , Cu, Zn, Mo, Ca, Sr, W, Zr and the like, can be replaced with one or more elements, or can be coated with a compound or carbon material containing these other elements. Of these, LiFePO ₄ or LiMnPO ₄ is preferred.
Further, the lithium-containing olivine-type phosphate can also be used, for example, by mixing with the above-mentioned positive electrode active material.

The positive electrodes for lithium primary batteries include CuO, Cu ₂ O, Ag ₂ O, Ag ₂ CrO ₄ , CuS, CuSO ₄ , TiO ₂ , TiS ₂ , SiO ₂ , SnO, V ₂ O ₅ , V ₆ O ₁₂ , VO _x , Nb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ Pb ₂ O ₅ , Sb ₂ O ₃ , CrO ₃ , Cr ₂ O ₃ , MoO ₃ , WO ₃ , SeO ₂ , MnO ₂ , Mn ₂ O ₃ , Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , Ni ₂ O ₃ , NiO, CoO ₃ , CoO, and other oxides or chalcogen compounds of one or more metal elements, SO ₂ , SOCL ₂ , etc. Examples thereof include sulfur compounds and fluorocarbon (fluorinated graphite) represented by the general formula (CF _x ) _n . Of these, MnO ₂ , _{V2O 5 ,} fluorographite and the like are preferable.

The conductive agent for the positive electrode is not particularly limited as long as it is an electron conductive material that does not cause a chemical change. Examples thereof include natural graphite (scaly graphite and the like), graphite such as artificial graphite, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black and the like carbon black and the like. Further, graphite and carbon black may be appropriately mixed and used. The amount of the conductive agent added to the positive electrode mixture is preferably 1 to 10% by mass, and particularly preferably 2 to 5% by mass.

For the positive electrode, the positive electrode active material is made of a conductive agent such as acetylene black or carbon black, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), a styrene / butadiene copolymer (SBR), acrylonitrile and butadiene. Mix with a binder such as copolymer (NBR), carboxymethyl cellulose (CMC), or ethylene propylene dienter polymer, add a high boiling point solvent such as 1-methyl-2-pyrrolidone, and knead to make a positive mixture. After that, this positive electrode mixture is applied to an aluminum foil of a current collector, a lath plate made of stainless steel, etc., dried and pressure-molded, and then vacuumed at a temperature of about 50 ° C to 250 ° C for about 2 hours. It can be produced by heat-treating with.
The density of the portion of the positive electrode excluding the current collector is usually 1.5 g / cm ³ or more, preferably 2 g / cm ³ or more, and more preferably 3 g / cm ³ in order to further increase the capacity of the battery. The above is more preferably 3.6 g / cm ³ or more. The upper limit is preferably 4 g / cm ³ or less.

As the negative electrode active material for a lithium secondary battery, a lithium metal, a lithium alloy, and a carbon material capable of storing and releasing lithium [graphitized carbon and a (002) plane spacing of 0.37 nm or more). Graphite-resistant carbon, graphite with (002) surface spacing of 0.34 nm or less], tin (elemental substance), tin compound, silicon (elemental substance), silicon compound, lithium titanate such as Li ₄ Ti ₅ O ₁₂ Compounds and the like can be used alone or in combination of two or more.
Among these, it is more preferable to use a highly crystalline carbon material such as artificial graphite or natural graphite in terms of the occlusion and release capacity of lithium ions, and the interplanar spacing (d ₀₀₂ ) of the lattice plane (002) is 0. It is particularly preferable to use a carbon material having a graphite-type crystal structure of 340 nm (nanometer) or less, particularly 0.335 to 0.337 nm.
A plurality of flat graphite fine particles are repeatedly subjected to mechanical actions such as compressive force, frictional force, and shearing force on artificial graphite particles having a massive structure in which they are assembled or bonded in a non-parallel manner, for example, scaly natural graphite particles. It is obtained from the X-ray diffraction measurement of the negative electrode sheet when the density of the portion of the negative electrode excluding the current collector is pressure-molded to a density of 1.5 g / cm ³ or more by using the spheroidized graphite particles. When the ratio I (110) / I (004) of the peak intensity I (110) on the (110) plane and the peak intensity I (004) on the (004) plane of the graphite crystal is 0.01 or more, it is further from the positive electrode active material. It is preferable because it improves the metal elution amount and the charge storage characteristics, more preferably 0.05 or more, and further preferably 0.1 or more. Further, the upper limit is preferably 0.5 or less, more preferably 0.3 or less, because the crystallinity may be lowered and the discharge capacity of the battery may be lowered due to excessive treatment.
Further, it is preferable that the highly crystalline carbon material (core material) is coated with a carbon material having a lower crystallinity than the core material because the cycle characteristics are further improved. The crystallinity of the coated carbon material can be confirmed by TEM.
When a highly crystalline carbon material is used, it reacts with a non-aqueous electrolyte solution during charging and tends to deteriorate the cycle characteristics due to an increase in interfacial resistance. However, the lithium secondary battery according to the present invention has good cycle characteristics. Become.

Examples of the metal compound capable of storing and releasing lithium as a negative electrode active material include Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni and Cu. , Zn, Ag, Mg, Sr, Ba and the like, and examples thereof include compounds containing at least one kind of metal element. These metal compounds may be used in any form such as elemental substances, alloys, oxides, nitrides, sulfides, borides, alloys with lithium, etc., but any simple substance, alloys, oxides, alloys with lithium, etc. It is preferable because the capacity can be increased. Among them, those containing at least one element selected from Si, Ge and Sn are preferable, and those containing at least one element selected from Si and Sn are particularly preferable because the capacity of the battery can be increased.

The negative electrode is kneaded with a conductive agent, a binder, and a high boiling point solvent similar to those for producing the positive electrode to obtain a negative electrode mixture, and then this negative electrode mixture is applied to a copper foil or the like of a current collector. It can be produced by drying, pressure molding, and then heat-treating under vacuum at a temperature of about 50 ° C. to 250 ° C. for about 2 hours.
The density of the portion of the negative electrode excluding the current collector is usually 1.1 g / cm ³ or more, preferably 1.5 g / cm ³ or more, and particularly preferably 1.7 g in order to further increase the capacity of the battery. / Cm ³ or more. The upper limit is preferably 2 g / cm ³ or less.

Moreover, as a negative electrode active material for a lithium primary battery, a lithium metal or a lithium alloy can be mentioned.

The structure of the lithium battery is not particularly limited, and a coin-type battery having a single-layer or multi-layer separator, a cylindrical battery, a square battery, a laminated battery, or the like can be applied.
The separator for a battery is not particularly limited, but a single-layer or laminated microporous film of polyolefin such as polypropylene or polyethylene, a woven fabric, a non-woven fabric or the like can be used.

The lithium secondary battery in the present invention has excellent cycle characteristics even when the charge termination voltage is 4.2 V or more, particularly 4.3 V or more, and further, the characteristics are good even when the charge termination voltage is 4.4 V or more. The discharge termination voltage is usually 2.8 V or more, further 2.5 V or more, but the lithium secondary battery in the present invention can be 2.0 V or more. The current value is not particularly limited, but is usually used in the range of 0.1 to 30C. Further, the lithium battery in the present invention can be charged and discharged at −40 to 100 ° C., preferably −10 to 80 ° C.

In the present invention, as a measure against an increase in the internal pressure of the lithium battery, a method of providing a safety valve on the battery lid or making a notch in a member such as a battery can or a gasket can be adopted. Further, as a safety measure for preventing overcharging, a current cutoff mechanism that senses the internal pressure of the battery and cuts off the current can be provided on the battery lid.

[Second electricity storage device (electric double layer capacitor)]
The second storage device is a storage device that stores energy by utilizing the electric double layer capacity at the interface between the electrolytic solution and the electrode. An example of the present invention is an electric double layer capacitor. The most typical electrode active material used in this power storage device is activated carbon. The double layer capacity increases roughly in proportion to the surface area.

[Third power storage device]
The third storage device is a storage device that stores energy by utilizing the doping / dedoping reaction of the electrodes. Examples of the electrode active material used in this power storage device include metal oxides such as ruthenium oxide, iridium oxide, tungsten oxide, molybdenum oxide and copper oxide, and π-conjugated polymers such as polyacene and polythiophene derivatives. Capacitors using these electrode active materials can store energy associated with the doping / dedoping reaction of the electrodes.

[Fourth power storage device (lithium ion capacitor)]
The fourth storage device is a storage device that stores energy by utilizing the intercalation of lithium ions with a carbon material such as graphite, which is a negative electrode. It is called a lithium ion capacitor (LIC). Examples of the positive electrode include those using an electric double layer between an activated carbon electrode and an electrolytic solution, and those using a dope / dedoping reaction of a π-conjugated polymer electrode. The electrolytic solution contains at least a lithium salt such as LiPF ₆ .

Examples 1-2 and Comparative Examples 1-2
[Manufacturing of lithium-ion secondary battery]
LiNi _0.5 Mn _0.3 Co _0.2 O ₂ ; 90% by mass, acetylene black (conductive agent); 3% by mass, KS-4 (conductive agent); 3% by mass is mixed, and polyvinylidene fluoride (polyvinylidene fluoride) is prepared in advance. Binder); 4% by mass was added to the solution dissolved in 1-methyl-2-pyrrolidone and mixed to prepare a positive mixture paste. This positive electrode mixture paste was applied to both sides of an aluminum foil (current collector), dried and pressure-treated, and cut to a predetermined size to prepare a rectangular positive electrode sheet. The density of the portion of the positive electrode excluding the current collector was 2.5 g / cm ³ . Further, graphite (negative electrode active material); 98% by mass, carboxymethyl cellulose (thickener); 1% by mass, and butadiene copolymer (binding agent); 1% by mass are added to water and mixed to mix the negative electrode. A mixture paste was prepared. This negative electrode mixture paste was applied to both sides of a copper foil (current collector), dried and pressure-treated, and cut to a predetermined size to prepare a negative electrode sheet. The density of the portion of the negative electrode excluding the current collector was 1.4 g / cm ³ . Then, the positive electrode sheet, the separator made of a microporous film in which the polyolefin was laminated, and the negative electrode sheet were laminated in this order, and the non-aqueous electrolytic solutions having the compositions shown in Tables 1 and 2 were added to prepare a laminated battery.

[Evaluation of gas generation during continuous high temperature charging]
Using the battery produced by the above method, the battery was charged in a constant temperature bath at 60 ° C. with a constant current and constant voltage of 1C to a final voltage of 4.4V for 3 hours, and stored at 4.4V for 4 days. .. Then, after continuous charging, it was placed in a constant temperature bath at 25 ° C. and once discharged to a final voltage of 2.75 V under a constant current of 1 C. The amount of gas generated during continuous charging was measured by the Archimedes method. The amount of gas generated was based on the case where the amount of gas generated in Comparative Example 1 was 100%, and the relative amount of gas generated was investigated.
In addition, the battery after continuous charging shall be charged in a constant temperature bath at 45 ° C. for 2 hours with a constant current and constant voltage of 1C to a cutoff voltage of 4.2V, and discharged to a cutoff voltage of 2.75V under a constant current of 1C. The capacity after continuous charging was measured by.
The battery characteristics are shown in Table 1.
[Evaluation of high temperature discharge storage characteristics]
Using the battery produced by the above method, the battery was charged in a constant temperature bath at 60 ° C. at a constant current and constant voltage of 1 C to a final voltage of 3.5 V for 1 hour, and stored for 1 day. The high temperature discharge storage characteristics were determined by the following rate of voltage change.
Rate of voltage change (%) = (voltage after high temperature discharge storage / voltage before high temperature discharge storage) x 100
In the present specification, the state of 3.5 V is defined as a discharge state.
The battery characteristics are shown in Table 2.

In Table 1 above, in Example 1 using the non-aqueous electrolytic solution of the present invention, the amount of gas generated during continuous high-temperature charging is significantly reduced as compared with Comparative Example 1. Further, in Table 2, in Example 2 using the non-aqueous electrolytic solution of the present invention, the voltage change during high-temperature discharge storage is smaller than that of the non-aqueous electrolytic solution of Comparative Example 2 containing tetraethyl methylene diphosphonate. From these results, it can be said that the non-aqueous electrolytic solution of the present invention can suppress gas generation during continuous high-temperature charging and a decrease in battery voltage during high-temperature storage in a discharged state in a well-balanced manner.
From the results of Example 2 and Comparative Example 2, it is strongly suggested that the voltage change during high-temperature discharge storage is derived from the presence or absence of a hydrogen atom in the methylene portion of the bisphosphonic acid ester, and R5 and R5 in the general formula ⁽ I). When R ⁶ is an alkyl group having 1 to 4 carbon atoms, the non-aqueous electrolytic solution of the present invention can achieve both suppression of gas generation and suppression of battery voltage drop during high-temperature storage in a discharged state. Conceivable. Further, after high-temperature continuous charging of the lithium ion secondary battery prepared by adding VC corresponding to 1% by mass with respect to the non-aqueous electrolytic solution to the non-aqueous electrolytic solution used in Example 1 under the same conditions as in Example 1. The capacity of is improved by 10% from the capacity of Example 1, and the battery characteristics are further improved by combining with VC.

The power storage device using the non-aqueous electrolyte solution of the present invention is useful as a power storage device such as a lithium secondary battery having excellent electrochemical characteristics when the battery is used at a high voltage.

Claims (4)

A non-aqueous electrolyte solution for a power storage device containing a compound represented by the following general formula (I) in a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent.

(R ¹ to R ⁴ independently indicate an alkyl group having 1 to 4 carbon atoms, and R ⁵ and R ⁶ independently indicate an alkyl group having 1 to 4 carbon atoms.) In the compound represented by the general formula (I), R ¹ to R ⁴ are independently methyl groups or ethyl groups, and R ⁵ and R ⁶ are independently methyl groups or ethyl groups, respectively. The non-aqueous electrolyte solution according to claim 1. The compounds represented by the general formula (I) are tetramethyl propane-2,2-diylbis (phosphonate), tetramethylpentane-3,3-diylbis (phosphonate), tetraethyl propane-2,2-diylbis (phosphonate), and the like. The non-aqueous electrolyte solution according to claim 1, wherein the non-aqueous electrolyte solution is one or more selected from the group consisting of tetraethylpentane-3,3-diylbis (phosphonate). The non-aqueous electrolytic solution according to any one of claims 1 to 3, wherein the storage device comprises a non-aqueous electrolytic solution in which an electrolyte salt is dissolved in a positive electrode, a negative electrode, and a non-aqueous solvent. A power storage device characterized by being a liquid.