JP2022024391A - Nonaqueous electrolyte solution, and power storage device arranged by use thereof - Google Patents

Abstract

To provide a nonaqueous electrolyte solution which can suppress a generated gas and the resistance with good balance to enhance the battery characteristic in a power storage device, and a power storage device arranged by use thereof.SOLUTION: A nonaqueous electrolyte solution for a power storage device comprises at least one sulfide compound represented by the general formula (I) below (where R1-R4 independently represent an alkyl group with 1-8 carbon atoms, of which at least one hydrogen atom may be substituted with a fluorine atom, R1 and R2, and/or R3 and R4 may form a ring together with a nitrogen atom adjacent thereto, and n is 1 or 2), and at least one dinitrile compound represented by the general formula (II) below (where L represents an alkylene group with 1-8 carbon atoms).SELECTED DRAWING: None

Description

The present invention relates to a non-aqueous electrolytic solution capable of suppressing generated gas and resistance in a well-balanced manner and improving battery characteristics in a power storage device, and a power storage device using the same.

In recent years, energy storage devices, particularly lithium batteries, have been widely used for small electronic devices such as mobile phones and notebook computers, electric vehicles and power storage. Since the batteries of these electronic devices and automobiles deteriorate due to long-term use, it is necessary to replace the batteries. Therefore, there is a demand for a lithium battery that can suppress deterioration due to repeated charging and discharging, that is, has good cycle characteristics. In the present specification, the term lithium battery is used as a concept including a so-called lithium ion secondary battery.

A lithium battery is mainly composed of a positive electrode and a negative electrode containing a material capable of occluding and releasing lithium, and a non-aqueous electrolytic solution composed of a lithium salt and a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate [EC] and propylene. A carbonate such as carbonate [PC] is used.
Further, as the negative electrode, metallic lithium, a metal compound capable of occluding and releasing lithium (single metal, oxide, alloy with lithium, etc.) and a carbon material are known, and in particular, lithium can be occluded and released. Lithium batteries using carbon materials such as occlusion, artificial graphite, and natural graphite, and silicon materials have been widely put into practical use.
As the positive electrode, a lithium composite metal oxide capable of rapidly increasing and releasing lithium is known, and in particular, a lithium composite metal oxide containing one or more selected from the group consisting of cobalt, manganese and nickel is used. It is used as a lithium battery because it can be charged and discharged stably.

The organic solvent contained in the non-aqueous electrolyte solution of the lithium battery may be decomposed by a high charge state or charge / discharge to generate gas such as carbon monoxide, carbon dioxide and methane. In batteries used for so-called consumer applications such as small electronic devices such as mobile phones and notebook computers, these gases generated from the inside of the batteries may inflate the power storage device and cause a safety problem.

Further, with the development of devices, the demand for rapid charging is increasing, and suppressing the resistance inside the battery is one of the important battery characteristics. In particular, the resistance at the interface between the electrode and the electrolytic solution is a major resistance factor among the resistances in the battery, and it is required to suppress the interface resistance between the positive electrode and the negative electrode and the electrolytic solution.

Patent Document 1 improves the charge / discharge cycle life in a non-aqueous electrolyte secondary battery characterized by containing a positive electrode, a negative electrode containing a specific carbon substance, and a non-aqueous solvent containing a thiuram monosulfide compound. It is stated that.

Patent Document 2 describes that a non-aqueous electrolyte solution containing a thiuram sulfide compound improves the recovery rate after storage of a battery.

Patent Document 3 describes the generation of dendrites by adding a specific thiuram disulfide compound to an organic electrolyte solution in a negative electrode made of lithium or a lithium alloy, a positive electrode, and a lithium secondary battery that requires an organic electrolyte solution. It is described that the cycle characteristics can be significantly improved and the cycle characteristics can be further improved.

Patent Document 4 describes that when an electrolytic solution containing a specific sulfur-containing compound is used, the increase in resistance of the negative electrode is reduced and the decrease in battery capacity after the storage test is suppressed.

Japanese Unexamined Patent Publication No. 2005-011617 Japanese Patent Application Laid-Open No. 2003-187861 Japanese Patent Application Laid-Open No. 6-036797 JP-A-2004-055471

An object of the present invention is to provide a non-aqueous electrolytic solution capable of suppressing generated gas and resistance in a well-balanced manner and improving battery characteristics in a power storage device, and a power storage device using the same.

The present inventors have conducted intensive studies to solve the above problems, and used a non-aqueous electrolytic solution in which a specific sulfide compound and a specific dinitrile compound are dissolved in a non-aqueous solvent to prepare the positive and negative electrode surfaces. We have found that the generation gas and resistance can be suppressed in a well-balanced manner in the power storage device by coating, and the present invention has been completed.

That is, the present invention provides the following (1) to (4).

(1) A non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent contains at least one sulfide compound represented by the following general formula (I) and dinitrile represented by the following general formula (II). A non-aqueous electrolyte solution for a power storage device, which comprises at least one compound.

（式中、Ｒ^１～Ｒ^４はそれぞれ独立に、少なくとも一つの水素原子がフッ素原子で置換されていてもよい炭素数１～８のアルキル基を示し、Ｒ^１とＲ^２および／またはＲ^３とＲ^４が隣接する窒素原子とともに環を形成してもよく、ｎは１または２である。）

(In the formula, R ¹ to R ⁴ each independently represent an alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom may be substituted with a fluorine atom, and R ¹ and R ² and / or R ³ are shown. And R ⁴ may form a ring with adjacent nitrogen atoms, where n is 1 or 2).

（式中、Ｌは炭素数１～８のアルキレン基を示す。）

(In the formula, L represents an alkylene group having 1 to 8 carbon atoms.)

(2) The non-aqueous electrolytic solution according to (1), wherein n is 1 in the general formula (I).

(3) The non-aqueous electrolytic solution according to (1) or (2), wherein the dinitrile compound is succinonitrile, glutaronitrile, adiponitrile, pimeronitrile or suberonitrile.

(4) The non-aqueous electrolyte solution according to any one of (1) to (3) 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. A power storage device characterized by being a water electrolyte.

According to the present invention, in a power storage device, it is possible to provide a non-aqueous electrolytic solution capable of suppressing generated gas and resistance in a well-balanced manner, and a power storage device using the same.

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

[Non-water electrolyte]
The non-aqueous electrolytic solution of the present invention is a non-aqueous electrolytic solution in which an electrolyte salt is dissolved in a non-aqueous solvent, and the non-aqueous electrolytic solution contains at least one sulfide compound represented by the general formula (I). Moreover, it is a non-aqueous electrolytic solution for a power storage device, characterized in that it contains at least one dinitrile compound represented by the general formula (II).

The reason why the non-aqueous electrolytic solution of the present invention improves the battery characteristics of the power storage device is not always clear, but it is considered as follows. Since the sulfide compound represented by the general formula (I) has a high reduction potential and a low oxidation potential as compared with a carbonate solvent generally used as a non-aqueous solvent for a power storage device, the charge / discharge of the power storage device Occasionally, it is considered that a film of a reducing decomposition product is formed on the surface of the negative electrode and a film of an oxidative decomposition product is formed on the surface of the positive electrode. This film has high Li-ion conductivity and suppresses the resistance of the power storage device, but it is considered that the decomposition product itself adhering to the electrode surface causes an increase in gas, and the gas and resistance generated by the power storage device are suppressed in a well-balanced manner. I can't. However, when the dinitrile compound represented by the general formula (II) is also present in the non-aqueous electrolytic solution, the sulfide compound of the general formula (I) is simultaneously incorporated when decomposing on the surface of the positive and negative electrodes, and the general formula is described. A decomposition film having a composition different from that formed by the decomposition of only (I) is formed. It is presumed that this film does not itself cause an increase in gas, and also suppresses gas generation due to solvent decomposition of carbonate and the like. By forming such a film on the surface of the electrode, it is considered that when the non-aqueous electrolytic solution of the present invention is used, the generated gas and resistance in the power storage device can be suppressed in a well-balanced manner.

In the non-aqueous electrolytic solution of the present invention, the content of the sulfide compound represented by the general formula (I) contained in the non-aqueous electrolytic solution is 0.01 to 8% by mass with respect to the total amount of the non-aqueous electrolytic solution. Is preferable because the battery characteristics are improved. Further, 0.05% by mass or more is more preferable, and 0.1% by mass or more is further preferable. Further, 3% by mass or less is more preferable, 1% by mass or less is further preferable, 0.5% by mass or less is particularly preferable, and 0.3% by mass or less is most preferable.

In the non-aqueous electrolytic solution of the present invention, the content of the dinitrile compound represented by the general formula (II) contained in the non-aqueous electrolytic solution is 0.01 to 8% by mass with respect to the total amount of the non-aqueous electrolytic solution. Is preferable because the battery characteristics are improved. Further, 0.05% by mass or more is more preferable, and 0.1% by mass or more is further preferable. Further, 5% by mass or less is more preferable, and 3% by mass or less is further preferable.

In the non-aqueous electrolytic solution of the present invention, if the content of the compound represented by the general formula (I) and the general formula (II) contained in the non-aqueous electrolytic solution is within the above range, the effect is sufficiently exhibited. However, if the content ratio of the sulfide compound of the general formula (I) to the dinitrile compound of the general formula (II) is within a certain range, it is preferable because the battery characteristics are further improved. The content ratio (total content mass of the dinitrile compound of the formula (II) / total content mass of the sulfide compound of the formula (I)) is preferably in the range of 1 to 100, and more preferably in the range of 1 to 50. It is preferably in the range of 2 to 40, more preferably in the range of 4 to 40, and particularly preferably in the range of 4 to 40.

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

（式中、Ｒ^１～Ｒ^４はそれぞれ独立に、少なくとも一つの水素原子がフッ素原子で置換されていてもよい炭素数１～８のアルキル基を示し、Ｒ^１とＲ^２および／またはＲ^３とＲ^４が隣接する窒素原子とともに環を形成してもよく、ｎは１または２である。）

(In the formula, R ¹ to R ⁴ each independently represent an alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom may be substituted with a fluorine atom, and R ¹ and R ² and / or R ³ are shown. And R ⁴ may form a ring with adjacent nitrogen atoms, where n is 1 or 2).

In the general formula (I), R ¹ to R ⁴ are each independently preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and further preferably an alkyl group having 1 to 2 carbon atoms. ..

Specific examples of R ¹ to R ⁴ include a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group or an n-hexyl group, or an iso-propyl group. Alkyl groups of branched chains such as iso-butyl group, sec-butyl group or tert-butyl group are preferably mentioned, and methyl group, ethyl group, n-propyl group or n-butyl group are preferable, and methyl group or ethyl is preferable. Group is particularly preferred.

Moreover, as a specific example of the case where R ¹ and R ² and / or R ³ and R ⁴ are bonded to each other to form a ring, those having a pyrrolidyl structure or a piperidine structure are preferably mentioned.

As the sulfide compound represented by the general formula (I), n in the formula is more preferably 1.

As the sulfide compound represented by the general formula (I), when n in the formula is 1, specifically, the following compounds are preferably mentioned.

Among the above preferred examples A1 to A10, tetramethylthiuram monosulfide (compound A1), tetraethylthiuram monosulfide (compound A2), tetrapropylthiuram monosulfide (compound A3) or tetrabutylthium monosulfide (compound A4) is more preferable. , Tetramethylthiuram monosulfide (Compound A1) or tetraethylthiuram monosulfide (Compound A2) is particularly preferred.

As the sulfide compound represented by the general formula (I), when n in the formula is 2, specifically, the following compounds are preferably mentioned.

Among the preferred examples A11 to A20, tetramethylthiumum disulfide (Compound A11), tetraethylthiumum disulfide (Compound A12), tetrapropylthiumum disulfide (Compound A13) or tetrabutylthiumum disulfide (Compound A14) is more preferable, and tetramethylthiumum disulfide (Compound A14) is more preferable. Disulfide (Compound A11) or tetraethylthiuram disulfide (Compound A12) is particularly preferred.

Among the preferred examples A1 to A20, A1 to A10 are more preferable, A1 to A4 are further preferable, and A1 or A2 is most preferable.

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

（式中、Ｌは炭素数１～８のアルキレン基を示す。）

(In the formula, L represents an alkylene group having 1 to 8 carbon atoms.)

In the general formula (II), L is preferably an alkylene group having 1 to 6 carbon atoms, and more preferably an alkylene group having 2 to 6 carbon atoms.

Specific examples of the dinitrile compound represented by the general formula (II) include the following compounds.

Among the above specific examples, malononitrile (compound B1), succinonitrile (compound B2), glutaronitrile (compound B3), adiponitrile (compound B4), pimeronitrile (compound B5) or suberonitrile (compound B6) are more preferable. Sinonitrile (Compound B2), Glutaronitrile (Compound B3), Adiponitrile (Compound B4) Pimeronitrile (Compound B5) or Suberonitrile (Compound B6) are even more preferred.

[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 or LiClO ₄ , LiN (SO ₂ F) ₂ [LiFSI], LiN (SO ₂ CF ₃ ) ₂ [LiTFSI], 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 ) Lithium salts containing chain-like fluoroalkyl groups such as F ₇ ) ₃ or LiPF ₅ (iso-C ₃ F ₇ ) or (CF ₂ ) ₂ (SO ₂ ) ₂ NLi or (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 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 is preferable, and LiPF is preferable. It is most preferable to use ₆ . The concentration of each of the electrolyte salts is preferably 4% by mass or more, more preferably 9% by mass or more, further preferably 13% by mass or more, and 28% by mass, based on the total amount of the non-aqueous electrolyte solution. It is preferably less than or equal to, more preferably 23% by mass or less, still more preferably 20% by mass or less.

Further, although these electrolyte salts exhibit sufficient performance even when used alone, the battery characteristics are further improved by combining them with the electrolyte salts. Suitable combinations include LiPF ₆ and further include at least one lithium salt selected from LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ and LiN (SO ₂ F) ₂ in the non-aqueous electrolyte. It is preferable that LiPF ₆ is contained, and LiBF ₄ or LiN (SO ₂ F) ₂ is more preferably contained in the non-aqueous electrolyte solution, and it is particularly preferable that LiN (SO ₂ F) ₂ is contained. The ratio of each of the lithium salts other than LiPF ₆ to the total amount of the non-aqueous electrolytic solution is not particularly limited, but 0.01% by mass or more is preferable because the battery characteristics are improved. It is more preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and most preferably 1% by mass or more. Further, it is preferably 15% by mass or less, more preferably 13% by mass or less.

[Non-aqueous solvent]
As used herein, the term "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. In order to improve the battery characteristics, 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.

Examples of the cyclic carbonate include a cyclic carbonate having a fluorine atom, a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond, and a cyclic carbonate not containing a fluorine atom and an unsaturated bond. Specific examples of the cyclic carbonate having a fluorine atom and the cyclic carbonate having an unsaturated bond include 4-fluoro-1,3-dioxolane-2-one [FEC], trans or cis-4,5-difluoro-1,3. -Dioxolane-2-one [DFEC], vinylene carbonate [VC], vinylethylene carbonate [VEC] or 4-ethynyl-1,3-dioxolane-2-one [EEC], and the like, as well as fluorine atoms and unsaturated bonds. Specific examples of the carbonate not containing the above include ethylene carbonate [EC], propylene carbonate [PC], 1,2-butylene carbonate, 2,3-butylene carbonate and the like.

As the cyclic carbonate having a fluorine atom, FEC or DFEC is preferable, and FEC is particularly preferable. Further, as the cyclic carbonate having an unsaturated bond such as the carbon-carbon double bond or the carbon-carbon triple bond, VC, VEC or EEC is preferable, and VC is particularly preferable.

As the cyclic carbonate containing no fluorine atom and unsaturated bond, EC or PC is preferable, and EC is particularly preferable.

The total content of the cyclic carbonate is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 90% by mass, based on the total amount of the non-aqueous electrolytic solution. Below, it is more preferably 70% by mass or less, further preferably 50% by mass or less, and most preferably 40% by mass or less, because the battery characteristics are further improved without impairing the Li ion permeability.

The cyclic carbonate may be used alone or in combination of two or more. In particular, in the electrolytic solution of the present invention, one or more selected from the cyclic carbonate having a fluorine atom and the cyclic carbonate having an unsaturated bond, and one selected from the cyclic carbonate not containing the fluorine atom and the unsaturated bond. It is preferable to use the above in combination because the battery characteristics are further improved.

In particular, it is most preferable to use FEC in combination with one or more selected from the cyclic carbonates containing no fluorine atom and unsaturated bond because the resistance of the negative electrode coating can be further suppressed.

When the cyclic carbonate is used in combination, its mass ratio ((cyclic carbonate having a fluorine atom or a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond) / (fluorine atom and) The cyclic carbonate)) containing no unsaturated bond is preferably 1 or less, and more preferably 0.5 or less. Further, the content of the cyclic carbonate containing no fluorine atom and unsaturated bond when combined is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on the total amount of the non-aqueous electrolytic solution. Further preferably, it is 0.5% by mass or more, more preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, without impairing the Li ion permeability. It is preferable because the characteristics are improved.

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 two selected from methyl ethyl carbonate [MEC], methyl propyl carbonate [MPC], methyl isopropyl carbonate [MIPC], methyl butyl carbonate, ethyl propyl carbonate and methyl fluoroethyl carbonate [FMEC]. One or more symmetric chain carbonates selected from the above asymmetric chain carbonate, dimethyl carbonate [DMC], diethyl carbonate [DEC], dipropyl carbonate and dibutyl carbonate or methyl pivalate, ethyl pivalate, pivalic acid. One selected from pivalic acid esters such as propyl, methyl propionate [MP], ethyl propionate [EP], propyl propionate [PP], methyl acetate [MA], ethyl acetate [EA] and propyl acetate [PA]. Alternatively, two or more kinds of chain carboxylic acid esters are preferably mentioned.

Among the chain esters, it has a methyl group selected from dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, methyl fluoroethyl carbonate, methyl propionate, methyl acetate, ethyl acetate and propyl acetate. A chain ester is preferable, and a chain carbonate having a methyl group is particularly preferable.

The content of the chain ester in the non-aqueous solvent used in the non-aqueous electrolytic solution of the present invention is not particularly limited, but is preferably used in the range of 5 to 90% by mass with respect to the total amount of the non-aqueous electrolytic solution. When the content is 5% by mass or more, the viscosity of the non-aqueous electrolytic solution does not become too high, more preferably 10% by mass or more, further preferably 30% by mass or more, and particularly preferably 50% by mass or more. Is. Further, if it is preferably 90% by mass or less, more preferably 85% by mass or less, there is little possibility that the electric conductivity of the non-aqueous electrolyte solution will decrease and the capacity retention rate after the cycle will decrease, so that it is within the above range. preferable.

The ratio of the cyclic carbonate to the chain ester is preferably 10:90 to 50:50, preferably 30:70 to 40:60, from the viewpoint of improving the capacity retention rate after the cycle. Is particularly preferable.

Other non-aqueous solvents include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran or 1,4-dioxane, chains such as 1,2-dimethoxyethane, 1,2-diethoxyethane or 1,2-dibutoxyetane. One or more selected from amides such as ether, dimethylformamide, sulfones such as sulfolane and lactones such as γ-butyrolactone [GBL], γ-valerolactone or α-angelica lactone are preferably mentioned.

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. , It is more preferable to use GBL among the lactones.

The content of the other non-aqueous solvent is usually preferably 1% by mass or more, more preferably 2% by mass or more, and usually preferably 40% by mass or less, more preferably more, based on the total amount of the non-aqueous electrolytic solution. Is 30% by mass or less, particularly preferably 20% by mass or less. Within the concentration range, there is little possibility that the electrical conductivity will decrease and that the battery characteristics will decrease due to the decomposition of the solvent.

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

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

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

(B) Selected 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.

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

(C) 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-diyl dimethanesulfonate and 2-butin-1,4-diyl diformate.

Triple bond-containing compounds 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. One or more selected from dimethanesulfonates are preferred, from 2-propinyl methanesulphonic acid, 2-propinyl vinylsulfonic acid, di (2-propynyl) oxalate and 2-butin-1,4-diyldimethanessulfonate. One or more selected species are more preferred.

(D) 1,3-Propane sultone (PS), 1,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-propensultone or 2,2-dioxide-1,2-oxathiolane- Sultone such as 4-ylacetate, cyclic sulphite such as ethylene sulphite, sulfonic acid esters such as butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate or methylenemethanedisulfonate and divinyl. One or more S = O group-containing compounds selected from sultone and vinyl sulfonates such as 1,2-bis (vinylsulfonyl) ethane or bis (2-vinylsulfonylethyl) ether.

The S = O group-containing compound can be classified into a cyclic S = O group-containing compound and a chain S = O group-containing compound, and among the cyclic S = O group-containing compounds, 1,3-propane. Sultone, 1,3-butane sultone, 1,4-butane sultone, 2,4-butane sultone, 1,3-propensultone, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, methylene methanedisulfonate and ethylene One or more selected from sulfite is preferably mentioned. Among the chain S = O group-containing compounds, butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate, dimethylmethanedisulfonate, pentafluorophenylmethanesulfonate, 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. , Pentafluorophenylmethane sulfonate and one or more selected from divinyl sulfone are more preferred.

(E) A cyclic acetal compound having an "acetal group" in the molecule. The type is not particularly limited as long as the molecule contains an "acetal group". Specific examples thereof include cyclic acetal compounds such as 1,3-dioxolane, 1,3-dioxane or 1,3,5-trioxane.

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

(F) Trimethyl phosphate, tributyl phosphate, trioctyl phosphate, tris phosphate (2,2,2-trifluoroethyl), ethyl 2- (diethoxyphosphoryl) acetate and 2-propynyl 2- (diethoxyphosphoryl) One or more phosphorus-containing compounds selected from acetate.

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

(G) "C (= O) -OC (= O) group", "C (= O) -OS (= O) ₂ groups" or "S (= O) ₂ -O" in the molecule An acid anhydride having "-S (= O) ₂ groups". Specific examples thereof include chain carboxylic acid anhydrides such as acetic anhydride or propionic anhydride or succinic anhydride, maleic anhydride, 3-allyl succinic anhydride, glutaric anhydride, itaconic anhydride, 1,2-oxathiolane. One or more cyclic acid anhydrides selected from -5-one 2,2-dioxide and 1,2,6-oxadithian 2,2,6,6-tetraoxide.

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.

(H) A phosphazene compound having an "N = PN group" in the molecule. The type is not particularly limited as long as the molecule contains "N = PN group". Specific examples thereof include cyclic phosphazene compounds such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene or ethoxyheptafluorocyclotetraphosphazene.

As the cyclic phosphazene compound, a cyclic phosphazene compound such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene or phenoxypentafluorocyclotriphosphazene is preferable, and methoxypentafluorocyclotriphosphazene or ethoxypentafluorocyclotriphosphazene is more preferable. ..

(I) A lithium salt compound having a oxalic acid skeleton different from the electrolyte salt or a lithium salt compound having a phosphoric acid skeleton. Specific examples thereof include lithium bis (oxalat) borate [LiBOB], lithium difluoro (oxalat) borate [LiDFOB], lithium tetrafluoro (oxalat) phosphate [LiTFOP], or lithium difluorobis (oxalat) phosphate [LiDFOP]. A lithium salt having an acid skeleton or a lithium salt compound having a phosphoric acid skeleton such as LiPO ₂ F ₂ or Li ₂ PO ₃ F.

As the lithium salt compound having an oxalate skeleton, one or more selected from bis (oxalat) borate [LiBOB], lithium difluoro (oxalat) borate [LiDFOB] and lithium difluorobis (oxalate) phosphate [LiDFOP] are preferable. , One or more selected from bis (oxalat) borate [LiBOB] and lithium difluorobis (oxalate) phosphate [LiDFOP] are more preferred.

As the lithium salt compound having a phosphoric acid skeleton, one or more selected from LiPO ₂ F ₂ and Li ₂ PO ₃ F is preferable, and LiPO ₂ F ₂ is more preferable.

The content of each of the compounds (A) and (B) is preferably 0.01 to 7% by mass with respect to the total amount of the non-aqueous electrolytic solution. In this range, the film is sufficiently formed without becoming too thick, the battery characteristics can be improved, and gas generation can be suppressed. The content is more preferably 0.05% by mass or more, particularly preferably 0.1% by mass or more, more preferably 5% by mass or less, and 3% by mass with respect to the total amount of the non-aqueous electrolytic solution. The following are particularly preferred.

The content of each of the compounds (C) to (H) is preferably 0.001 to 8% by mass with respect to the total amount of the non-aqueous electrolytic solution. In this range, the film is sufficiently formed without becoming too thick, and the battery characteristics can be further improved. The content is more preferably 0.01% by mass or more, particularly preferably 0.1% by mass or more, and 6% by mass or less with respect to the total amount of the non-aqueous electrolytic solution. It is more preferable, and 5% by mass or less is particularly preferable.

The ratio of each of the lithium salt compounds (I) in the non-aqueous electrolytic solution is preferably 0.01% by mass or more and 5% by mass or less with respect to the total amount of the non-aqueous electrolytic solution. Within this range, the battery characteristics can be further improved and gas generation can be suppressed. It is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.4% by mass or more with respect to the total amount of the non-aqueous electrolytic solution. Further, it is more preferably 3% by mass or less, and particularly preferably 2% by mass or less, based on the total amount of the non-aqueous electrolytic solution.

[Manufacturing of non-aqueous electrolyte solution]
The non-aqueous electrolyte solution of the present invention is, for example, mixed with the above-mentioned non-aqueous solvent, and is represented by the above-mentioned formula (I) and the above-mentioned formula (II) with respect to the above-mentioned electrolyte salt and the above-mentioned non-aqueous electrolyte solution. It can be obtained by adding a compound.
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 third 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. Among them, it is preferable to use it for a first power storage device (that is, for a lithium battery) or a third power storage device (that is, for a lithium ion capacitor) that uses a lithium salt as an electrolyte salt, and it is preferable to use it for a lithium battery. More preferably, it is most suitable for use as a lithium secondary battery.

[First power storage device (lithium battery)]
In the present specification, the lithium battery is a general term for a lithium primary battery and a lithium secondary battery. Further, in the present specification, the term lithium secondary battery is used as a concept including a so-called lithium ion secondary battery. The lithium battery, which is the power storage device of the present invention, comprises the positive electrode, the negative electrode, and the non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent. Components other than the non-aqueous electrolyte can be used without particular limitation.

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 lithium composite metal oxides include LiCoO ₂ , LiCo _1-x M _x O ₂ (where M is Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Zn and Cu). One or more elements selected from, 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 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) solid solution and LiNi _1/2 Mn _3/2 O ₄ selected from 1 More than one species is preferred, and more than one species is more preferred. 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.

Further, since the positive electrode active material containing Ni has a large theoretical Li storage amount, it is preferable to use it as the positive electrode active material of the power storage device. However, in the positive electrode active material containing Ni, the non-aqueous solvent is decomposed on the surface of the positive electrode due to the catalytic action of Ni, and the resistance of the battery tends to increase. In particular, the battery characteristics tend to deteriorate in a high temperature environment, but the lithium secondary battery according to the present invention can suppress the deterioration of these battery characteristics. From the viewpoint of improving the capacity of the power storage device, the above effect becomes remarkable 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%. Therefore, 50% or more is more preferable, and 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.

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, and can be substituted with one or more elements, or coated with a compound or a 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.

Among the positive electrode active materials, the electrolytic solution of the present invention can suppress resistance and particularly suppress generated gas with respect to the positive electrode active material containing Co. For example, LiCoO ₂ , LiCo _1-x M _x O ₂ (where M is one or more elements selected from Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Zn and Cu. , 0.001 ≤ x ≤ 0.05), 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 and LiNi _0.8 Co _0.15 Al _0.05 O ₂ are preferred, particularly LiCo O ₂ , LiCo _1-x M _x O ₂ (where M is Sn, Mg, Fe). , Ti, Al, Zr, Cr, V, Ga, Zn and Cu, one or more elements, 0.001 ≦ x ≦ 0.05).

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 a conductive agent such as acetylene black or carbon black, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), a styrene and butadiene copolymer (SBR), and acrylonitrile and butadiene. It is mixed with a binder such as a polymer (NBR), carboxymethyl cellulose (CMC), or ethylene propylene dienter polymer, and a high boiling point solvent such as 1-methyl-2-pyrrolidone is added thereto and kneaded to form 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 at a temperature of about 50 ° C to 250 ° C and under vacuum for about 2 hours. It can be produced by heat treatment.

Negative negative active materials for lithium secondary batteries include lithium metals, lithium alloys, and carbon materials capable of storing and releasing lithium [graphitized carbon and (002) plane spacing of 0.37 nm (nanometer). ) Or more graphitized carbon, (002) graphite with a surface spacing of 0.34 nm or less], elemental metals and alloys [tin, silicon, etc.] and metal compounds [tin oxide, silicon oxide, titanium acid, etc.] It can be used alone or in combination of two or more selected from [lithium oxide, etc.].

Among the carbon materials, it is more preferable to use a highly crystalline carbon material such as artificial graphite or natural graphite in terms of occlusion and release capacity of lithium ions, and the interplanar spacing (d ₀₀₂ ) of the lattice plane (002) is more preferable. It is particularly preferable to use a carbon material having a graphite-type crystal structure having a graphite-type crystal structure of 0.340 nm 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 of I (110) / I (004) is preferably 0.5 or less, more preferably 0.3 or less, because excessive treatment may reduce the crystallinity and the discharge capacity of the battery. preferable.
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 capacity retention rate after the cycle is 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 electrolytic solution during charging and tends to reduce the capacity retention rate after a cycle due to an increase in interfacial resistance. Later capacity retention will be good.

In addition, as metal simple substances and alloys capable of occluding and releasing lithium as a negative electrode active material, Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, Ti, In, Mn, Fe, Co, Ni , Cu, Zn, Ag, Mg, Sr, Ba and the like, and examples thereof include metals containing at least one kind of metal element. These metals may be used in any form such as simple substances, alloys, alloys with lithium, and the like. Among them, at least one metal selected from Si, Ge and Sn is preferable, and at least one metal selected from Si and Sn is particularly preferable because the capacity of the battery can be increased.

Metal compounds capable of occluding and releasing lithium as a negative electrode active material include Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, Ti, In, Mn, Fe, Co, Ni, Cu and Zn. , Ag, Mg, Sr, Ba and other metal-containing oxides, nitrides, sulfides, borides and the like. Among them, a metal compound containing Si element and Ti element is preferable because it improves battery characteristics. Among the metal compounds containing the Si element, SiO _x , which is a composite material of Si and SiO ₂ , is preferable because it can further improve the battery characteristics including the cycle retention rate. The range of x is 0 <x <2. Among the metal compounds containing the Ti element, the titanium-containing metal oxide containing Li ₄ Ti ₅ O ₁₂ and TiNb ₂ O ₇ as the main components has small expansion and contraction during charging and discharging and is flame-retardant. It is preferable in terms of enhancing safety.

The negative electrode active material for a lithium secondary battery is not particularly limited as long as it can store and release lithium ions, but is a metal oxide (SiO _x ) containing a lithium metal, a carbon material, a silicon metal, and a Si element. It is preferable to use one or a combination of two or more selected from metal oxides containing Ti elements (Li ₄ Ti ₅ O ₁₂ , TiNb ₂ O ₇ , etc.), and it is selected from carbon materials, silicon metals, and SiO _x . It is more preferable to use one kind alone or a combination of two or more kinds.

When the negative electrode active material is used in combination with a carbon material and SiO _x , the weight ratio of SiO _x is not particularly limited, but the entire negative electrode mixture containing the negative electrode active material, the conductive agent, the binder, and the high boiling point solvent is used. 30% by mass or less is preferable, 10% by mass or less is more preferable, and 5% by mass or less is further preferable.

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 form 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 1.3 g / cm ³ or more, and particularly preferably 1.5 g in order to further increase the capacity of the battery. It is preferably / cm ³ or more, and preferably 2 g / cm ³ or less.

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 battery separator 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.

[Second power 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. Preferred electrode materials used in this power storage device are materials containing C atoms and materials containing Si atoms, and specific examples thereof include activated carbon and silicon. The double layer capacity increases roughly in proportion to the surface area.

[Third storage device (lithium ion capacitor)]
The third 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, or a material containing Si atoms. 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 .
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.

Example 1
LiCoO ₂ (LCO); 94% by mass, acetylene black (conductive agent); 3% by mass is mixed, and polyvinylidene fluoride (binding agent); 3% by mass is dissolved in 1-methyl-2-pyrrolidone in advance. It was added to the existing solution and mixed to prepare a positive electrode mixture paste. This positive electrode mixture paste was applied to one side of an aluminum foil (current collector), dried and pressure-treated, and cut to a predetermined size to prepare a positive electrode sheet. The density of the portion of the positive electrode excluding the current collector was 3.6 g / cm ³ .
In addition, 98% by mass of artificial graphite (negative electrode active material), carboxymethyl cellulose (thickener); 1%, copolymer of butadiene (binding agent); 1% by mass is added to water and mixed to form a negative electrode 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 1.5 g / cm ³ .
The non-aqueous electrolyte solution was prepared so that the ratio of EC and MEC in volume ratio was EC: MEC = 3: 7 (volume ratio), and the amount of LiPF ₆ as the electrolyte salt was 1 mol / L. In addition to the electrolyte solvent, VC is 1% by mass based on the total amount of the non-aqueous electrolyte solution, PS is 1% by mass based on the total amount of the non-aqueous electrolyte solution, and FEC is 1% by mass based on the total amount of the non-aqueous electrolyte solution. The reference electrolytic solution was prepared by adding it so as to be%. Further, tetramethylthiuram monosulfide (the compound A1) was added to the reference electrolytic solution in an amount of 0.1% by mass based on the total amount of the non-aqueous electrolytic solution, and adiponitrile (the compound B4) was added to the total amount of the non-aqueous electrolytic solution. In addition to 5% by mass, the non-aqueous electrolytic solution of Example 1 was prepared. When the non-aqueous electrolytic solution of Example 1 is expressed by mass ratio, EC: MEC: LiPF ₆ : VC: PS: FEC: tetramethylthiuram monosulfide: adiponitrile = 30.3: 54.1: 12.1 :. The ratio is 1.0: 1.0: 1.0: 0.1: 0.5 (mass ratio).
The positive electrode sheet, the separator made of a microporous polyethylene film, and the negative electrode sheet were laminated in this order, and the prepared non-aqueous electrolytic solution was added to prepare a laminated battery.

Examples 2-4
A laminated battery was produced in the same manner as in Example 1 except that the non-aqueous electrolytic solution prepared in Example 1 was changed to the non-aqueous electrolytic solution having the composition shown in Table 1.

Comparative Examples 1 to 3
A laminated battery was produced in the same manner as in Example 1 except that the non-aqueous electrolytic solution prepared in Example 1 was changed to the non-aqueous electrolytic solution having the composition shown in Table 1.

[Evaluation of battery characteristics]
The battery produced by the above method was charged in a constant temperature bath at 45 ° C. with a constant current of 0.2 C to a final voltage of 4.2 V, and discharged to a discharge voltage of 2.7 V under a constant current of 0.2 C. Next, the battery was charged to a final voltage of 4.2 V with a constant current of 0.2 C, allowed to stand in an open circuit state for 24 hours, and discharged to a discharge voltage of 2.7 V under a constant current of 0.2 C. It was charged again with a constant current of 0.2 C to a cutoff voltage of 4.2 V, and discharged to a discharge voltage of 2.7 V under a constant current of 0.2 C. The volume of gas generated after charging and discharging was measured by the Archimedes method, and the resistance was measured by the AC impedance method. The battery characteristics are shown in Table 1. The AC resistance value in the table indicates the resistance value of the actual axis at 25 MHz.

In Table 1, only the compound represented by the general formula (II) is contained based on Comparative Example 1 using the electrolytic solution containing neither the compound represented by the general formula (I) nor the compound represented by the general formula (II). In Comparative Example 2 using the electrolytic solution, an increase in AC resistance and generated gas was observed. Further, also in Comparative Example 3 containing only the compound of the general formula (I), an increase in the generated gas was observed although the AC resistance decreased as compared with Comparative Example 1.
On the other hand, in Examples 1 to 4 using the non-aqueous electrolytic solution of the present invention, the AC resistance and the generated gas are suppressed in a well-balanced manner. In particular, the compounds represented by the general formulas (I) and the general formulas (II) of Comparative Examples 2 and 3 alone have an increased amount of generated gas as compared with Comparative Example 1, but they are contained together. In all of Examples 1 to 4, the generated gas is reduced as compared with Comparative Example 1, the formed film itself does not cause the gas increase, and the gas generation due to the decomposition of the solvent such as carbonate is also suppressed. Guessed. By forming such a film on the electrode surface, it is considered that when the non-aqueous electrolytic solution of the present invention is used, the generated gas and resistance in the power storage device can be suppressed in a well-balanced manner, which is a specific effect of the present invention. I can say.

By using the non-aqueous electrolytic solution of the present invention, it is possible to obtain a storage device having excellent electrochemical characteristics in a wide temperature range. In particular, when used as a non-aqueous electrolyte for power storage devices such as lithium secondary batteries installed in hybrid electric vehicles, plug-in hybrid electric vehicles, battery electric vehicles, etc., storage devices whose electrochemical characteristics do not easily deteriorate over a wide temperature range. Can be obtained.

Claims (4)

In a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent, at least one sulfide compound represented by the following general formula (I) is contained, and at least a dinitrile compound represented by the following general formula (II) is contained. A non-aqueous electrolyte solution for a power storage device, which is characterized by containing a kind.

(In the formula, R ¹ to R ⁴ each independently represent an alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom may be substituted with a fluorine atom, and R ¹ and R ² and / or R ³ are shown. And R ⁴ may form a ring with adjacent nitrogen atoms, where n is 1 or 2).

(In the formula, L represents an alkylene group having 1 to 8 carbon atoms.) The non-aqueous electrolytic solution according to claim 1, wherein n is 1 in the general formula (I). The non-aqueous electrolytic solution according to claim 1 or 2, wherein the dinitrile compound is succinonitrile, glutaronitrile, adiponitrile, pimeronitrile or suberonitrile. The non-aqueous electrolyte solution according to any one of claims 1 to 3 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. A power storage device characterized by that.