WO2018164130A1

WO2018164130A1 - Additive for non-aqueous electrolyte, non-aqueous electrolyte, and power storage device

Info

Publication number: WO2018164130A1
Application number: PCT/JP2018/008603
Authority: WO
Inventors: 翔平藤本; 佑軌河野; 恭幸高井; 藤田　浩司
Original assignee: 住友精化株式会社
Priority date: 2017-03-08
Filing date: 2018-03-06
Publication date: 2018-09-13
Also published as: TW201840548A

Abstract

Disclosed is an additive for a non-aqueous electrolyte, said additive containing a compound represented by formula (1) below. In the formula (1), X indicates a sulphonyl group or a carbonyl group; R1 and R2 indicate a hydrogen atom, an optionally substituted C1-4 alkyl group, etc.; and A indicates an optionally substituted C1-3 divalent hydrocarbon group, or a divalent group comprising an optionally substituted C1-3 divalent hydrocarbon group and an oxygen atom constituting part of a cyclic structure together with the hydrocarbon group.

Description

Non-aqueous electrolyte additive, non-aqueous electrolyte, and electricity storage device

The present invention relates to an additive for non-aqueous electrolyte, a non-aqueous electrolyte, and an electricity storage device.

In recent years, research on non-aqueous electrolyte secondary batteries represented by lithium ion batteries has been conducted extensively as interest in solving environmental problems and realizing a sustainable recycling society has increased. Lithium ion batteries have high working voltage and energy density, and are therefore used as power sources for notebook computers and mobile phones. Since lithium ion batteries have a higher energy density than lead batteries and nickel cadmium batteries, realization of higher capacity of the batteries is expected.

However, the lithium ion battery has a problem that the capacity of the battery decreases as the charge / discharge cycle progresses. The cause of the decrease in capacity is, for example, the decomposition of the electrolyte solution due to the electrode reaction, the decrease in the impregnation property of the electrolyte into the electrode active material layer, and the decrease in the lithium ion intercalation efficiency with a long charge / discharge cycle. It is thought that this is caused by

A method of adding various additives to an electrolytic solution has been studied as a method for suppressing a decrease in battery capacity associated with a charge / discharge cycle. Additives are generally decomposed during the first charge and discharge to form a film called a solid electrolyte interface (SEI) on the electrode surface. Since the SEI is formed in the first charge / discharge cycle, lithium ions can move back and forth through the SEI while suppressing the consumption of electricity for the decomposition of the electrolyte during the subsequent charge / discharge. That is, it is considered that the formation of SEI plays a major role in suppressing the deterioration of the secondary battery when the charge / discharge cycle is repeated and improving the battery characteristics, storage characteristics, load characteristics, and the like.

Examples of the additive for the electrolyte include cyclic monosulfonic acid esters in Patent Documents 1 to 3, sulfur-containing aromatic compounds in Patent Document 4, disulfide compounds in Patent Document 5, and disulfonic acid in Patent Documents 6 to 9. Each ester is disclosed. Patent Documents 10 to 15 disclose electrolytic solutions containing cyclic carbonates or cyclic sulfones.

JP 63-102173 A JP 2000-003724 A JP 11-339850 A JP 05-258753 A Japanese Patent Laid-Open No. 2001-052735 JP 2009-038018 A Japanese Patent Laid-Open No. 2005-203341 JP 2004-281325 A JP 2005-228631 A Japanese Patent Laid-Open No. 04-87156 Japanese Patent Laid-Open No. 10-50342 Japanese Patent Laid-Open No. 08-45545 JP 2001-6729 A JP 63-102173 A Japanese Patent Laid-Open No. 05-074486

A compound having a low lowest unoccupied molecular orbital (LUMO) energy is an excellent electron acceptor and is considered to be able to form a stable SEI on the surface of an electrode such as a nonaqueous electrolyte secondary battery (for example, non Patent Document 1).

Although some of the conventional additives disclosed in Patent Documents 1 to 9 exhibit low LUMO energy, they have a problem that they are chemically unstable and easily deteriorate due to the influence of moisture and temperature. For example, although disulfonic acid ester shows low LUMO energy, it has low stability to moisture and easily deteriorates. Therefore, when it is stored for a long period of time, strict moisture content and temperature management are required. In general, the lithium ion battery is required to have a heat resistant temperature of about 60 ° C. and the lithium ion capacitor is about 80 ° C. Therefore, the improvement of the non-aqueous electrolyte additive used in the electricity storage device at high temperature is It was one of the important issues.

In addition, in the case of an electrolytic solution containing a conventional additive, when the power storage device is used over a long period of time while repeating the charge / discharge cycle, the battery characteristics of the power storage device are likely to be deteriorated. There was a need for improvement.

The electrolyte solutions described in Patent Documents 10 to 14 can suppress irreversible capacity reduction to some extent by SEI generated on the negative electrode surface by electrochemical reductive decomposition. However, although SEI formed by the additive in these electrolytes is excellent in the performance of protecting the electrode, it is not sufficient in terms of strength to withstand long-term use. Therefore, there is a problem that SEI is decomposed during use of the electricity storage device or a crack is generated in the SEI to expose the negative electrode surface, resulting in decomposition of the electrolytic solution and deterioration of battery characteristics. The electrolyte solution using an ethylene carbonate compound described in Patent Document 15 as an additive generates a gas such as carbon dioxide when ethylene carbonate is decomposed on the electrode, leading to a decrease in battery performance. Had a problem. The gas generation is particularly remarkable when a charge / discharge cycle is repeated at a high temperature or for a long time.

Thus, regarding the additive for non-aqueous electrolyte, there is room for further improvement in terms of storage stability, cycle characteristics for maintaining performance when the charge / discharge cycle is repeated, or suppression of gas generation.

The present invention provides a non-aqueous electrolyte additive that has high storage stability and enables improvement of cycle characteristics and suppression of gas generation with respect to an electricity storage device.

The present inventors have found that a compound containing a specific structure exhibits low LUMO energy and is chemically stable. Furthermore, the present inventors can obtain excellent cycle characteristics and suppress gas generation when the compound is used as an additive for a non-aqueous electrolyte in an electricity storage device such as a non-aqueous electrolyte secondary battery. As a result, the present invention has been completed.

That is, this invention provides the additive for non-aqueous electrolyte containing the compound represented by following formula (1).

In the formula (1), X represents a sulfonyl group or a carbonyl group, R ¹ and R ² each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 4 carbon atoms, or an optionally substituted group. A preferred alkenyl group having 2 to 4 carbon atoms, an optionally substituted alkynyl group having 2 to 4 carbon atoms, or an optionally substituted aryl group, wherein A represents an optionally substituted carbon atom having 1 to 3 divalent hydrocarbon group or a divalent hydrocarbon group having 1 to 3 carbon atoms which may be substituted and a divalent group comprising an oxygen atom constituting a cyclic structure together with the hydrocarbon group .

The compound represented by the formula (1) is a cyclic sulfone compound. Since the cyclic sulfone compound can cause ring-opening polymerization, it is considered to form strong SEI. Furthermore, the compound of the formula (1) containing a carbonyloxy group or a sulfonyloxy group bonded to the ring is considered to exhibit low LUMO energy and exhibit excellent ionic conductivity. Therefore, it is considered that the compound of the formula (1) can form a stable SEI that can withstand long-term use.

According to the present invention, there is provided an additive for non-aqueous electrolyte that has high storage stability and enables improvement of cycle characteristics and suppression of gas generation with respect to an electricity storage device. The additive for non-aqueous electrolyte according to the present invention forms a stable SEI (solid electrolyte interface) on the electrode surface when used in an electricity storage device such as a non-aqueous electrolyte secondary battery or an electric double layer capacitor. Thus, battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance can be improved.

It is sectional drawing which shows one Embodiment of an electrical storage device.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The additive for nonaqueous electrolysis according to the present embodiment contains one or more compounds represented by the following formula (1).

A in the formula (1) may be an alkylene group having 1 to 3 carbon atoms substituted with a halogen atom, or an oxyalkylene group having 1 to 3 carbon atoms which may be substituted with a halogen atom. The oxygen atom in the oxyalkylene group may be bonded to the sulfonyl group in the formula (1). The hydrocarbon group (particularly an alkylene group) contained in A may have 1 or 2 carbon atoms. Specific examples of _{_{_{_{A, -CH 2 -, - CH 2}}}} CH 2 -, - CH 2 CH 2 CH 2 -, - CFHCH 2 -, - CF 2 CH 2 -, - OCH 2 -, and -OCH ₂ CH _2- .

As shown in the following formula (1) ', a carbonyloxy group or a sulfonyloxy group may be bonded to the 3-position of the cyclic sulfone. This compound tends to exhibit particularly low LUMO energy and better ionic conductivity.

Wherein (1) ', X, ^{R 1} and ^{R 2} are X in each formula (1), ^{R 1} and ^{R 2} synonymous.

From the viewpoint that the battery resistance tends to be lower, the compound of the formula (1) may be a compound represented by the following formula (1a) or (1b).

Wherein (1a) and (1b), X, ^{R 1} and ^{R 2} are X in each formula (1), ^{R 1} and ^{R 2} synonymous.

X in the formulas (1), (1) ′, (1a) and (1b) may be a sulfonyl group from the viewpoint of lower battery resistance and further suppression of gas generation. That is, the compound of the formula (1) may be a compound represented by the following formula (2a) or (2b).

With respect to R ¹ and R ^{2 in} formulas (1), (1) ′, (1a), (1b), (2a) and (2b), an alkyl group having 1 to 4 carbon atoms and an alkenyl group having 2 to 4 carbon atoms Group, when the alkynyl group having 2 to 4 carbon atoms is substituted, the substituent is, for example, a halogen atom, an aryl group, a halogenated aryl group (for example, 2-fluorophenyl group, 3-fluorophenyl group, 4 A fluorinated aryl group such as a fluorophenyl group or a perfluorophenyl group), an alkoxy group, a halogenated alkoxy group, or a combination thereof. With respect to R ¹ and R ² , when the aryl group is substituted, the substituent is, for example, a halogen atom, an alkyl group, a halogenated alkyl group (for example, a trifluoromethyl group, 2,2,2-trifluoroethyl) A fluorinated alkyl group such as a group), an alkoxy group, a halogenated alkoxy group, or a combination thereof. For example, R ¹ and R ² are each independently a C 1-4 alkyl group optionally substituted with a halogen atom, an aryl group or a halogenated aryl group, or a carbon optionally substituted with a halogen atom. An alkenyl group having 2 to 4 carbon atoms, an alkynyl group having 2 to 4 carbon atoms which may be substituted with a halogen atom, an aryl group which may be substituted with a halogen atom, an alkyl group or a halogenated alkyl group, or a hydrogen atom It may be.

R ¹ and R ² in the formulas (1), (1) ′, (1a), (1b), (2a) and (2b) are each independently a hydrogen atom from the viewpoint of lowering battery resistance. An alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, an aryl group or a halogenated aryl group, an alkynyl group having 2 to 4 carbon atoms which may be substituted with a halogen atom, or a halogen atom, It may be an aryl group which may be substituted with an alkyl group or an alkyl halide group.

R ¹ and R ² in formulas (1), (1) ′, (1a), (1b), (2a) and (2b) contain groups in which the compounds represented by these formulas have an unsaturated bond Then, from the viewpoint of forming stronger SEI, each independently, a hydrogen atom, an alkenyl group having 2 to 4 carbon atoms that may be substituted with a halogen atom, or 2 to 2 carbon atoms that may be substituted with a halogen atom. It may be an alkynyl group of 4 or an aryl group optionally substituted with a halogen atom, an alkyl group or a halogenated alkyl group.

In R ¹ and R ² in the formulas (1), (1) ′, (1a), (1b), (2a) and (2b), the alkyl group having 1 to 4 carbon atoms may be, for example, a methyl group , Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and t-butyl group. As the alkyl group having 1 to 4 carbon atoms, a methyl group or an isopropyl group can be selected. These may be substituted with a halogen atom, an aryl group or a halogenated aryl group. Examples of the aryl group bonded to the alkyl group having 1 to 4 carbon atoms include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Examples of the alkyl group having 1 to 4 carbon atoms substituted with a halogen atom, an aryl group or a halogenated aryl group include benzyl group, trifluoromethyl group, 1-fluoroethyl group, 2-fluoroethyl group, 1,1 -Difluoroethyl group, 1,2-difluoroethyl group, 2,2-difluoroethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group, 1-fluoro-n-propyl group, 2-fluoro- n-propyl group, 3-fluoro-n-propyl group, 1,1-difluoro-n-propyl group, 1,2-difluoro-n-propyl group, 1,3-difluoro-n-propyl group, 2,2 -Difluoro-n-propyl group, 2,3-difluoro-n-propyl group, 3,3-difluoro-n-propyl group, 3,3,3-trifluoro-n-propyl group, 2 2,3,3,3-pentafluoro-n-propyl group, perfluoro-n-propyl group, 1-fluoroisopropyl group, 2-fluoroisopropyl group, 1,2-difluoroisopropyl group, 2,2-difluoroisopropyl Group, 2,2′-difluoroisopropyl group, 2,2,2,2 ′, 2 ′, 2′-hexafluoroisopropyl group, 1-fluoro-n-butyl group, 2-fluoro-n-butyl group, 3 -Fluoro-n-butyl group, 4-fluoro-n-butyl group, 4,4,4-trifluoro-n-butyl group, perfluoro-n-butyl group, 2-fluoro-tert-butyl group, perfluoro -Tert-butyl group, (2-fluorophenyl) methyl group, (3-fluorophenyl) methyl group, (4-fluorophenyl) methyl group, and (perfluorophene) Le) and methyl group.

R ¹ and R ² in formulas (1), (1) ′, (1a), (1b), (2a) and (2b) have 2 to 4 carbon atoms which may be substituted with the halogen atom Examples of the alkenyl group include vinyl group, allyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, isobutenyl group, 1-fluorovinyl group, 2-fluorovinyl. Group, 1,2-difluorovinyl group, 1,1-difluoro-1-propenyl group, 2,2-difluorovinyl group, perfluorovinyl group, 1-fluoroallyl group, 2-fluoroallyl group, 3-fluoroallyl Group, perfluoroallyl group and the like. As the alkenyl group having 2 to 4 carbon atoms, an allyl group or a 2-propenyl group can be selected.

R ¹ and R ² in formulas (1), (1) ′, (1a), (1b), (2a) and (2b) have 2 to 4 carbon atoms which may be substituted with the halogen atom Examples of the alkynyl group include 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 3-fluoro-1-propynyl group, and 3,3-difluoro-1-propynyl. Group, perfluoro-1-propynyl group, 1-fluoro-2-propynyl group, 1,1-difluoro-2-propynyl group, 3-fluoro-1-butynyl group, 4-fluoro-1-butynyl group, 3, Examples include 4-difluoro-1-butynyl group, 4,4-difluoro-1-butynyl group, and perfluoro-1-butynyl group. As the alkynyl group having 2 to 4 carbon atoms, a 2-propynyl group can be selected.

R ¹ and R ² in formulas (1), (1) ′, (1a), (1b), (2a) and (2b) are substituted with the halogen atom, alkyl group or halogenated alkyl group. Examples of the aryl group that may be used include phenyl group, tolyl group, xylyl group, naphthyl group, 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2,3-difluorophenyl group, 2,4 -Difluorophenyl group, 3,5-difluorophenyl group, 2,4,6-trifluorophenyl group, perfluorophenyl group, 3-fluoro-2-methylphenyl group, 4-fluoro-2-methylphenyl group, 5 -Fluoro-2-methylphenyl group, 6-fluoro-2-methylphenyl group, 2-fluoro-3-methylphenyl group, 4-fluoro-3-methylphenyl Group, 5-fluoro-3-methylphenyl group, 6-fluoro-3-methylphenyl group, 2-fluoro-4-methylphenyl group, 3-fluoro-4-methylphenyl group, 2-trifluoromethylphenyl group, 3-trifluoromethylphenyl group, 4-trifluoromethylphenyl group, 2- (2,2,2-trifluoroethyl) phenyl group, 3- (2,2,2-trifluoroethyl) phenyl group, 4- (2,2,2-trifluoroethyl) phenyl group, perfluorotolyl group, 2-fluoronaphthalen-1-yl group, 3-fluoronaphthalen-1-yl group, 4-fluoronaphthalen-1-yl group, 5 -Fluoronaphthalen-1-yl group, 6-fluoronaphthalen-1-yl group, 7-fluoronaphthalen-1-yl group, 8-fluoronaphthalene-1 Yl group, 1-fluoronaphthalen-2-yl group, 3-fluoronaphthalen-2-yl group, 4-fluoronaphthalen-2-yl group, 5-fluoronaphthalen-2-yl group, 6-fluoronaphthalene-2- Yl group, 7-fluoronaphthalen-2-yl group, 8-fluoronaphthalen-2-yl group, perfluoronaphthyl group and the like. These may be substituted with a halogen atom, and examples thereof include a 4-fluorophenyl group.

In A, R ¹ and R ² in the formulas (1), (1) ′, (1a), (1b), (2a) and (2b), “may be substituted with a halogen atom” It means that at least one hydrogen atom of each group may be substituted with a halogen atom. Examples of the halogen atom include an iodine atom, a bromine atom, and a fluorine atom. From the viewpoint that battery resistance tends to be lower, a fluorine atom can be selected as the halogen atom.

R ¹ and R ² in the formulas (1), (1) ′, (1a), (1b), (2a) and (2b) are more excellent in ionic conductivity of the compounds represented by these formulas. In view of the above, each independently may be a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, an aryl group or a halogenated aryl group.

R ¹ and R ² in the formulas (1), (1) ′, (1a), (1b), (2a) and (2b) are each independently from the viewpoint of improving cycle characteristics and suppressing gas generation. An alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, an aryl group or a halogenated aryl group, an alkenyl group having 2 to 4 carbon atoms which may be substituted with a halogen atom, or a halogen atom, It may be an aryl group which may be substituted with an alkyl group or an alkyl halide group.

Examples of the compound represented by the formula (1) include the following formulas (11), (12), (13), (14), (15), (16), (17), (18), (19 ), (20), (21), (22), (23) or (24). In these formulas, Ph represents a phenyl group, and n represents an integer of 1 to 5.

The compound of formula (1) exhibits low LUMO energy and is susceptible to electrochemical reduction. Therefore, non-aqueous electrolytes containing these as additives for non-aqueous electrolytes form stable SEI on the electrode surface when used in power storage devices such as non-aqueous electrolyte secondary batteries and cycle. Battery characteristics such as characteristics, charge / discharge capacity, and internal resistance can be improved. Moreover, since the compound of Formula (1) is stable with respect to moisture and temperature changes, the additive for nonaqueous electrolyte and nonaqueous electrolyte containing them can be stored at room temperature for a long time. is there.

The lowest unoccupied molecular orbital (LUMO) energy of the compound represented by the formula (1) may be −3.0 eV or more, or 0.0 eV or less. When the LUMO energy is −3.0 eV or more, SEI showing high resistance is hardly formed on the negative electrode due to excessive decomposition of the compound. When the LUMO energy is 0.0 eV or less, more stable SEI can be more easily formed on the negative electrode surface. From the same viewpoint, the LUMO energy may be −2.0 eV or more, or −0.1 eV or less. Those skilled in the art can find a compound exhibiting LUMO energy within these numerical ranges within the range defined by the formula (1) without undue trial and error.

In this specification, “lowest unoccupied molecular orbital (LUMO) energy” is a value calculated by combining the semi-empirical molecular orbital calculation method PM3 and the density functional method B3LYP method. Specifically, LUMO energy can be calculated using Gaussian 03 (Revision B.03, software manufactured by Gaussian, USA).

Those skilled in the art can synthesize the compound of formula (1) by combining the usual reactions using available raw materials. For example, the compound of formula (1a), which is one of the specific examples, can be synthesized by a method of reacting 3-hydroxysulfolane with a halide such as sulfamoyl chloride.

Specific examples in the case of producing the compound of the formula (1a) are shown below. First, 3-hydroxysulfolane and triethylamine are dissolved in an organic solvent, and then a sulfamoyl chloride compound is added dropwise and stirred at room temperature for 2 hours. Thereafter, the obtained reaction product is washed with water and the oil layer is concentrated, whereby the target compound can be obtained.

The additive for non-aqueous electrolyte according to this embodiment may contain the compound represented by the formula (1) alone or may contain two or more kinds. The compound represented by the formula (1) may be used in combination with other general components as long as the effect of the present invention is not significantly inhibited. Examples of other general components include a negative electrode protective agent, a positive electrode protective agent, a flame retardant, and an overcharge preventing agent.

The non-aqueous electrolyte according to the present embodiment contains the additive for non-aqueous electrolyte, a non-aqueous solvent, and an electrolyte. The content of the additive for nonaqueous electrolyte (or the compound represented by formula (1)) in this nonaqueous electrolyte is 0.005% by mass or more based on the total mass of the nonaqueous electrolyte. Or 10% by mass or less. When the content is 0.005% by mass or more, stable SEI is easily formed by an electrochemical reaction on the electrode surface. When the content is 10% by mass or less, the non-aqueous electrolyte additive can be easily dissolved in the non-aqueous solvent. Moreover, by not excessively increasing the content of the additive for non-aqueous electrolyte, an increase in the viscosity of the non-aqueous electrolyte can be suppressed and sufficient ion mobility can be ensured. If the mobility of ions is not sufficiently ensured, the conductivity of the non-aqueous electrolyte cannot be sufficiently ensured, and the charge / discharge characteristics of the electricity storage device may be hindered. From the same viewpoint, the content of the non-aqueous electrolyte additive (or the compound represented by the formula (1)) may be 0.01% by mass or more, or 0.1% by mass or more. It may be 0.5% by mass or more. From the same viewpoint, the content of the additive for non-aqueous electrolyte (or the compound represented by the formula (1)) may be 5% by mass or less, or 2.0% by mass or less.

In the non-aqueous electrolyte, the additive for non-aqueous electrolyte (the compound represented by the formula (1)) according to this embodiment may be used in combination with another compound that forms SEI. Other compounds that form SEI include cyclic carbonate compounds, nitrile compounds, isocyanate compounds, C≡C group-containing compounds, SO group-containing compounds, phosphorus-containing compounds, acid anhydrides, cyclic phosphazene compounds, boron-containing compounds, and silicon. Examples thereof include compounds.

Examples of the cyclic carbonate compound include 4-fluoro-1,3-dioxolan-2-one (FEC), trans or cis-4,5-difluoro-1,3-dioxolan-2-one (DFEC), vinylene carbonate ( VC), vinyl ethylene carbonate (VEC), 4-ethynyl-1,3-dioxolan-2-one (EEC), and the like. As the cyclic carbonate compound, VC, FEC, VEC or a combination thereof may be used.

Examples of the nitrile compound include acetonitrile, propionitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, and sebaconitrile. As the nitrile compound, succinonitrile, adiponitrile, or a combination thereof may be used.

Examples of the isocyanate compound include methyl isocyanate, ethyl isocyanate, butyl isocyanate, phenyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylene diisocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl. And methacrylate.

Examples of the C≡C group-containing compound include 2-propynyl methyl carbonate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, and 2-propynyl vinyl sulfonate. 2- (methanesulfonyloxy) propionic acid-2-propynyl, di (2-propynyl) oxalate, methyl-2-propynyl oxalate, ethyl-2-propynyl oxalate, di (2-propynyl) glutarate, Examples include 2-butyne-1,4-diyldimethanesulfonate, 2-butyne-1,4-diyldiformate, and 2,4-hexadiyne-1,6-diyldimethanesulfonate.

Examples of the SO group-containing compound include 1,3-propane sultone (PS), 1,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-propene sultone, 2,2-dioxide-1 , 2-oxathiolan-4-yl acetate, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxide, etc., sultone, ethylene sulfite, ethylene sulfate, hexahydrobenzo [1,3 , 2] dioxathiolane-2-oxide (also referred to as 1,2-cyclohexanediol cyclic sulfite) and cyclic sulfites such as 5-vinyl-hexahydro-1,3,2-benzodioxathiol-2-oxide, Butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate Sulfonate, methylenemethane disulfonate, sulfonate esters such as 1,3-propanedisulfonic anhydride, divinyl sulfone, 1,2-bis (vinylsulfonyl) ethane, and bis (2-vinylsulfonylethyl) ether It is done.

Examples of the phosphorus-containing compound include trimethyl phosphate, tributyl phosphate, and trioctyl phosphate, tris (2,2,2-trifluoroethyl) phosphate, bis (2,2,2-trifluoroethyl) methyl phosphate, Bis (2,2,2-trifluoroethyl) phosphate, bis (2,2,2-trifluoroethyl) phosphate, 2,2-difluoroethyl phosphate, bis (2,2,2-trifluoroethyl phosphate) ) 2,2,3,3-tetrafluoropropyl, bis (2,2-difluoroethyl) phosphate 2,2,2-trifluoroethyl, bis (2,2,3,3-tetrafluoropropyl) phosphate 2,2,2-trifluoroethyl and phosphoric acid (2,2,2-trifluoroethyl) (2,2,3,3-tetrafluoropropyl) methyl, tris phosphate (1,1,1, , 3,3-hexafluoropropan-2-yl), methyl methylene bisphosphonate, ethyl methylene bisphosphonate, methyl ethylene bisphosphonate, ethyl ethylene bisphosphonate, methyl butylene bisphosphonate, ethyl butylene bisphosphonate, methyl 2- (dimethylphosphoryl) ) Acetate, ethyl 2- (dimethylphosphoryl) acetate, methyl 2- (diethylphosphoryl) acetate, ethyl 2- (diethylphosphoryl) acetate, 2-propynyl 2- (dimethylphosphoryl) acetate, 2-propynyl 2- (diethylphosphoryl) Acetate, methyl 2- (dimethoxyphosphoryl) acetate, ethyl 2- (dimethoxyphosphoryl) acetate, methyl 2- (diethoxyphosphoryl) acetate, ethyl 2- (dietoxy) Phosphoryl) acetate, 2-propynyl 2- (dimethoxyphosphoryl) acetate, 2-propynyl 2- (diethoxyphosphoryl) acetate, methyl pyrophosphate, and ethyl, and the like pyrophosphate.

Examples of the acid anhydride include acetic anhydride, propionic anhydride, succinic anhydride, maleic anhydride, 3-allyl succinic anhydride, glutaric anhydride, itaconic anhydride, and 3-sulfo-propionic anhydride. .

Examples of the cyclic phosphazene compound include methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

Examples of the compound having a silicon atom include hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, hexaphenylcyclotrisiloxane, 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane, octamethylcyclotrisiloxane. Tetrasiloxane, decamethylcyclopentasiloxane, trimethylfluorosilane, triethylfluorosilane, tripropylfluorosilane, phenyldimethylfluorosilane, triphenylfluorosilane, vinyldimethylfluorosilane, vinyldiethylfluorosilane, vinyldiphenylfluorosilane, trimethoxyfluoro Silane, triethoxyfluorosilane, dimethyldifluorosilane, diethyldifluorosilane, divinyldifluorosilane, ethylvinyldifluor Silane, methyl trifluorosilane, ethyl trifluorosilane, hexamethyldisiloxane, 1,3-diethyltetramethyldisiloxane, hexaethyldisiloxane, octamethyltrisiloxane, methoxytrimethylsilane, ethoxytrimethylsilane, dimethoxydimethylsilane, tri Methoxymethylsilane, tetramethoxysilane, bis (trimethylsilyl) peroxide, trimethylsilyl acetate, triethylsilyl acetate, trimethylsilyl propionate, trimethylsilyl methacrylate, trimethylsilyl trifluoroacetate, trimethylsilyl methanesulfonate, trimethylsilyl ethanesulfonate, triethylsilyl methanesulfonate , Trimethylsilyl fluoromethanesulfonate, bis (trimethylsilyl) sulfur , Tris (trimethylsiloxy) boron, tris (trimethylsilyl) phosphate, and tris (trimethylsilyl) phosphite, and the like.

Examples of the compound having a boron atom include boroxine, trimethylboroxine, trimethoxyboroxine, triethylboroxine, triethoxyboroxine, triisopropylboroxine, triisopropoxyboroxine, tri-n-propylboroxine, tri-n- Examples include propoxyboroxine, tri-n-butylboroxine, tri-n-butyloxyboroxine, triphenylboroxine, triphenoxyboroxine, tricyclohexylboroxine, and tricyclohexoxyboroxine.

When the compound represented by the formula (1) and the cyclic carbonate compound are used in combination, the content of the cyclic carbonate compound is 0.001 to 10% by mass based on the total mass of the non-aqueous electrolyte. May be. When the content of the cyclic carbonate compound is within this range, the SEI does not become too thick, and the stability of the SEI at a higher temperature increases. The content of the cyclic carbonate compound may be 0.01% by mass or more, or 0.5% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the nitrile compound are used in combination, the content of the nitrile compound may be 0.001 to 10% by mass based on the total mass of the non-aqueous electrolyte. Good. When the content of the nitrile compound is within this range, the SEI does not become too thick, and the stability of the SEI at a higher temperature increases. The content of the nitrile compound may be 0.01% by mass or more, or 0.5% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the isocyanate compound are used in combination, the content of the isocyanate compound may be 0.01 to 5% by mass based on the total mass of the non-aqueous electrolyte. Good. When the content of the isocyanate compound is within this range, the SEI does not become too thick, and the stability of the SEI at higher temperatures increases. The content of the isocyanate compound may be 0.5% by mass or more or 3% by mass or less based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the C≡C group-containing compound are used in combination, the content of the C≡C group-containing compound is 0.01 based on the total mass of the non-aqueous electrolyte. It may be up to 5% by weight. When the content of the C≡C group-containing compound is within this range, the SEI does not become too thick, and the stability of the SEI at higher temperatures increases. The content of the C≡C group-containing compound may be 0.1% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the SO group-containing compound are used in combination, the content of the SO group-containing compound is 0.001 to 5% by mass based on the total mass of the non-aqueous electrolyte. It may be. When the content of the SO group-containing compound is within this range, the SEI does not become too thick, and the stability of the SEI at higher temperatures increases. The content of the SO group-containing compound may be 0.01% by mass or more, or 0.1% by mass or more based on the total mass of the non-aqueous electrolyte.

When the compound represented by the formula (1) and the phosphorus-containing compound are used in combination, the content of the phosphorus-containing compound is 0.001 to 5% by mass based on the total mass of the nonaqueous electrolytic solution. May be. When the content of the phosphorus-containing compound is within this range, the SEI does not become too thick, and the stability of the SEI at higher temperatures increases. The content of the phosphorus-containing compound may be 0.01% by mass or more, or 0.1% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the cyclic phosphazene compound are used in combination, the content of the cyclic phosphazene compound is 0.001 to 5% by mass based on the total mass of the non-aqueous electrolyte. May be. When the content of the cyclic phosphazene compound is within this range, the SEI does not become too thick, and the stability of the SEI at a higher temperature increases. The content of the cyclic phosphazene compound may be 0.01% by mass or more, or 0.1% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the acid anhydride are used in combination, the content of the acid anhydride is 0.001 to 5% by mass based on the total mass of the non-aqueous electrolyte. May be. When the content of the acid anhydride is within this range, the SEI does not become too thick, and the stability of the SEI at higher temperatures increases. The content of the acid anhydride may be 0.01% by mass or more, or 0.5% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the boron-containing compound are used in combination, the content of the boron-containing compound is 0.001 to 5% by mass based on the total mass of the non-aqueous electrolyte. May be. In this range, the SEI does not become too thick and the stability of the SEI at higher temperatures is increased. The content of the boron-containing compound may be 0.01% by mass or more, or 0.1% by mass or more based on the total mass of the nonaqueous electrolytic solution.

When the compound represented by the formula (1) and the silicon-containing compound are used in combination, the content of the silicon-containing compound is 0.01 to 5% by mass based on the total mass of the non-aqueous electrolyte. May be. When the content of the silicon-containing compound is within this range, the SEI does not become too thick, and the stability of the SEI at higher temperatures increases. The content of the silicon-containing compound may be 0.1% by mass or more, or 0.5% by mass or more based on the total mass of the nonaqueous electrolytic solution.

As the non-aqueous solvent, an aprotic solvent can be selected from the viewpoint of keeping the viscosity of the obtained non-aqueous electrolyte low. The aprotic solvent is at least one selected from the group consisting of cyclic carbonate, chain carbonate, aliphatic carboxylic acid ester, lactone, lactam, cyclic ether, chain ether, sulfone, nitrile, and halogen derivatives thereof. May be. As the aprotic solvent, a cyclic carbonate or a chain carbonate can be selected, and a combination of a cyclic carbonate and a chain carbonate can also be selected.

Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, and FEC. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Examples of the aliphatic carboxylic acid ester include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, and methyl trimethyl acetate. Examples of the lactone include γ-butyrolactone. Examples of the lactam include ε-caprolactam and N-methylpyrrolidone. Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane and the like. Examples of the chain ether include 1,2-diethoxyethane, ethoxymethoxyethane, and the like. Examples of the sulfone include sulfolane. Examples of the nitrile include acetonitrile. Examples of the halogen derivative include 4-fluoro-1,3-dioxolane-2-one, 4-chloro-1,3-dioxolan-2-one, 4,5-difluoro-1,3-dioxolane-2- ON etc. are mentioned. These non-aqueous solvents may be used alone or in combination of two or more.

The electrolyte may be a lithium salt that serves as a source of lithium ions. _{_{_{Electrolyte, LiAlCl 4, LiBF 4, LiPF}}} 6, LiClO 4, LiAsF 6 and may be at least one selected from the group consisting of LiSbF _6. From the viewpoint of having a high degree of dissociation and an ability to increase the ionic conductivity of the electrolytic solution and further suppressing the performance deterioration of the electricity storage device due to long-term use due to the oxidation-reduction characteristics, LiBF ₄ and / or LiPF are used as the electrolyte. ₆ may be selected. These electrolytes may be used alone or in combination of two or more.

When the electrolyte is LiBF ₄ and / or LiPF ₆ , one or more cyclic carbonates and chain carbonates may be combined as the non-aqueous solvent. In particular, LiBF ₄ and / or LiPF ₆ may be combined with ethylene carbonate and diethyl carbonate.

The concentration of the electrolyte in the non-aqueous electrolyte may be 0.1 to 2.0 mol / L based on the volume of the non-aqueous electrolyte. When the concentration of the electrolyte is 0.1 mol / L or more, more excellent discharge characteristics or charge characteristics can be obtained. When the concentration of the electrolyte is 2.0 mol / L or less, the viscosity of the nonaqueous electrolytic solution is difficult to increase, and thus sufficient ion mobility can be secured. From the same viewpoint, the electrolyte concentration may be 0.5 to 1.5 mol / L.

In the nonaqueous electrolytic solution according to the present embodiment, the electrolyte (first lithium salt) and a second lithium salt different from the electrolyte may be used in combination. Examples of the second lithium salt include lithium difluorophosphate, lithium bisoxalatoborate (LiBOB), lithium tetrafluoro (oxalato) phosphate (LiTFOP), lithium difluorooxalatoborate (LiDFOB), and lithium difluorobisoxalatophosphate. (LiDFOP), lithium tetrafluoroborate, lithium bisfluorosulfonylimide, lithium tetrafluoro (oxalato) phosphate, lithium salt having a phosphate skeleton such as Li ₂ PO ₃ F, and lithium trifluoro ((methanesulfonyl) Oxy) borate, lithium pentafluoro ((methanesulfonyl) oxy) phosphate, lithium methyl sulfate, lithium ethyl sulfate,

lithium

2,2 2-trifluoroethyl sulfate, and lithium salts having an S (= O) groups of the lithium fluorosulfonic acid and the like. The second lithium salt is lithium difluorophosphate, lithium bisoxalatoborate, lithium tetrafluoro (oxalato) phosphate, lithium difluorooxalatoborate, lithium difluorobisoxalate phosphate, lithium methyl sulfate, lithium ethyl sulfate, and fluorosulfone One or more lithium salts selected from the group consisting of lithium acid may be included.

The concentration of the second lithium salt in the non-aqueous electrolyte may be 0.001 to 1.0 mol / L based on the volume of the non-aqueous electrolyte. When the concentration of the second lithium salt is 0.001 mol / L or more, more excellent charge / discharge characteristics can be obtained under high temperature conditions. When the concentration of the second lithium salt is 1.0 mol / L or less, the viscosity of the non-aqueous electrolyte is difficult to increase, and thus ion mobility can be sufficiently ensured. From the same viewpoint, the concentration of the second lithium salt may be 0.01 to 0.8 mol / L or 0.01 to 0.5 mol / L.

The electricity storage device according to this embodiment is composed of the non-aqueous electrolyte and mainly a positive electrode and a negative electrode. Specific examples of the electricity storage device include a non-aqueous electrolyte secondary battery (such as a lithium ion battery) and an electric double layer capacitor (such as a lithium ion capacitor). The nonaqueous electrolytic solution according to the present embodiment is particularly useful in applications of lithium ion batteries and lithium ion capacitors.

FIG. 1 is a cross-sectional view schematically showing an embodiment of an electricity storage device. An electricity storage device 1 shown in FIG. 1 is a non-aqueous electrolyte secondary battery. The electricity storage device 1 includes a positive electrode plate 4 (positive electrode), a negative electrode plate 7 (negative electrode) facing the positive electrode plate 4, a nonaqueous electrolytic solution 8 disposed between the positive electrode plate 4 and the negative electrode plate 7, and nonaqueous And a separator 9 provided in the electrolytic solution 8. The positive electrode plate 4 includes a positive electrode current collector 2 and a positive electrode active material layer 3 provided on the nonaqueous electrolyte solution 8 side. The negative electrode plate 7 includes a negative electrode current collector 5 and a negative electrode active material layer 6 provided on the nonaqueous electrolyte solution 8 side. As the nonaqueous electrolytic solution 8, the nonaqueous electrolytic solution according to the above-described embodiment can be used. In FIG. 1, a non-aqueous electrolyte secondary battery is shown as the electricity storage device, but the electricity storage device to which the non-aqueous electrolyte can be applied is not limited to this, and other electricity storage devices such as an electric double layer capacitor. It may be.

The positive electrode current collector 2 and the negative electrode current collector 5 may be metal foils made of a metal such as aluminum, copper, nickel, and stainless steel, for example.

The positive electrode active material layer 3 contains a positive electrode active material. The positive electrode active material may be a lithium-containing composite oxide. Specific examples of the lithium-containing composite _{_{_{oxide, LiMnO 2, LiFeO 2, LiCoO}}} 2, LiMn 2 O 4, Li 2 FeSiO 4, LiNi 1/3 Co 1/3 Mn 1/3, LiNi 0.5 Co 0.2 Mn _0.3 , LiNi _0.6 Co _0.2 Mn _0.2 , LiNi _0.8 Co _0.1 Mn _0.1 , LiNi _x Co _y M _z O ₂ (where 0.01 <x <1, (0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y + z = 1, and M is at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb, Fe, Cu, and Al.) And LiFePO ₄ .

The negative electrode active material layer 6 contains a negative electrode active material. The negative electrode active material may be a material that can occlude and release lithium, for example. Specific examples of such materials include crystalline carbon (such as natural graphite and artificial graphite), amorphous carbon, carbon materials such as carbon-coated graphite and resin-coated graphite, indium oxide, silicon oxide, tin oxide, zinc oxide and Metal materials such as an oxide material such as lithium oxide, lithium metal, and a metal that can form an alloy with lithium can be given. Specific examples of the metal capable of forming an alloy with lithium include Cu, Sn, Si, Co, Mn, Fe, Sb, and Ag. A binary or ternary alloy containing these metals and lithium can also be used as the negative electrode active material. These negative electrode active materials may be used alone or in combination of two or more.

From the viewpoint of increasing the energy density, a carbon material such as graphite and a Si-based active material such as Si, Si alloy, or Si oxide may be combined as the negative electrode active material. From the viewpoint of achieving both cycle characteristics and high energy density, graphite and a Si-based active material may be combined as the negative electrode active material. Regarding such a combination, the ratio of the mass of the Si-based active material to the total mass of the carbon material and the Si-based active material is 0.5% by mass to 95% by mass, 1% by mass to 50% by mass, or 2 It may be not less than 40% by mass.

The positive electrode active material layer 3 and the negative electrode active material layer 6 may further contain a binder. Examples of the binder include polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, carboxymethyl cellulose, polytetrafluoro Examples thereof include ethylene, polypropylene, polyethylene, polyimide, polyamideimide, polyacrylic acid, polyvinyl alcohol, acrylic acid-polyacrylonitrile, polyacrylamide, polymethacrylic acid, and copolymers thereof. The binder may be the same or different between the positive electrode active material layer and the negative electrode active material layer.

The positive electrode active material layer 3 and the negative electrode active material layer 6 may further include a conductive auxiliary material for the purpose of reducing resistance. Examples of the conductive auxiliary material include carbonaceous fine particles such as graphite, carbon black, acetylene black, and ketjen black, and carbon fibers.

The separator 9 may be, for example, a single-layer or laminated microporous film, woven fabric, or non-woven porous film made of polyethylene, polypropylene, fluororesin, or the like.

Specific forms such as the shape and thickness of each member constituting the electricity storage device can be appropriately set by those skilled in the art. The configuration of the power storage device is not limited to the embodiment of FIG. 1 and can be changed as appropriate.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

1. Preparation of non-aqueous electrolyte (Example 1)
Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume composition ratio of EC: DEC = 30: 70 to obtain a mixed nonaqueous solvent. LiPF ₆ as an electrolyte was dissolved in the obtained mixed non-aqueous solvent so as to have a concentration of 1.0 mol / L. To the obtained solution, the compound 11 shown in Table 1 was added as an additive for a non-aqueous electrolyte to prepare a non-aqueous electrolyte. The content ratio of the additive for non-aqueous electrolyte (compound 11) was 0.5% by mass based on the total mass of the non-aqueous electrolyte.

(Example 2)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the content ratio of Compound 11 was 1.0% by mass.

(Example 3)
The nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 13 shown in Table 1 and the content ratio was 1.0% by mass. did.

Example 4
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 14 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 5)
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 15 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 6)
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 16 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 7)
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 17 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 8)
The nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 18 shown in Table 1 and the content ratio was 1.0% by mass. did.

Example 9
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 19 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 10)
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 20 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 11)
The nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 21 shown in Table 1 and the content ratio was 1.0% by mass. did.

(Example 12)
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from compound 11 to compound 23a shown in Table 1 and the content ratio was 1.0% by mass. did.

(Comparative Example 1)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that Compound 11 was not added.

(Comparative Example 2)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolytic solution was changed from Compound 11 to 1,3-propane sultone and the content ratio was 1.0% by mass. .

(Comparative Example 3)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolytic solution was changed from compound 11 to vinylene carbonate (VC) and the content ratio was 1.0% by mass.

(Comparative Example 4)
A nonaqueous electrolytic solution was prepared in the same manner as in Comparative Example 3 except that the content of vinylene carbonate (VC) was 2.0% by mass.

(Comparative Example 5)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolytic solution was changed from Compound 11 to fluoroethylene carbonate (FEC) and the content ratio was 1.0% by mass. .

(Comparative Example 6)
A nonaqueous electrolytic solution was prepared in the same manner as in Comparative Example 5 except that the content ratio of fluoroethylene carbonate (FEC) was 2.0% by mass.

(Comparative Example 7)
A nonaqueous electrolyte solution was prepared in the same manner as in Example 1 except that the additive for nonaqueous electrolyte solution was changed from Compound 11 to sulfolane and the content ratio was 1.0% by mass.

2. Evaluation (measurement of LUMO energy)
The LUMO (lowest unoccupied molecular orbital) energies of compounds 11, 13-21 and 23a used in the examples were determined by semi-empirical molecular orbital calculation with Gaussian 03 software. The calculated LUMO energy is shown in Table 1.

(Stability)
The compounds 11, 13 to 21 and 23a used in the examples and the fluoroethylene carbonate (FEC) used in Comparative Examples 5 and 6 were used in a constant temperature and humidity environment at a temperature of 40 ± 2 ° C. and a humidity of 75 ± 5%. The sample was subjected to a storage test for 90 days. The ¹ H-nuclear magnetic resonance spectrum ( ¹ H-NMR) of each additive for the non-aqueous electrolyte before and after the storage test was measured, and the stability of each compound was evaluated according to the following criteria. Table 2 shows the stability evaluation results.
A: There was no peak change in the ¹ H-NMR spectrum before and after the storage test.
B: A slight peak change in the ¹ H-NMR spectrum was confirmed before and after the storage test.
C: A clear peak change in the ¹ H-NMR spectrum was confirmed before and after the storage test.

As shown in Table 2, the fluoroethylene carbonate (FEC) used in Comparative Examples 5 and 6 was considered to be partially hydrolyzed and had poor stability. On the other hand, the compounds used in the examples were excellent in stability with almost no change in the peak of ¹ H-NMR spectrum.

(Preparation of non-aqueous electrolyte secondary battery)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ as a positive electrode active material and carbon black as a conductivity imparting agent were dry mixed. The obtained mixture was uniformly dispersed in N-methyl-2-pyrrolidone (NMP) in which polyvinylidene fluoride (PVDF) was dissolved as a binder to prepare a slurry. The obtained slurry was applied to both surfaces of an aluminum metal foil (square shape, thickness 20 μm). After removing NMP and drying the coating film, the whole was pressed to obtain a positive electrode sheet having an aluminum metal foil as a positive electrode current collector and a positive electrode active material layer formed on both surfaces thereof. The solid content ratio in the positive electrode active material layer of the obtained positive electrode sheet was a mass ratio, and was positive electrode active material: conductivity imparting agent: PVDF = 92: 4: 4.
As the negative electrode sheet, a commercially available graphite-coated electrode sheet (manufactured by Hosen Co., Ltd., trade name: electrode sheet negative electrode single layer) was used.
In each of the non-aqueous electrolytes obtained in the examples and comparative examples, a negative electrode sheet, a polyethylene separator, a positive electrode sheet, a polyethylene separator, and a negative electrode sheet were laminated in this order to produce a battery element. This battery element was inserted into a bag formed of a laminate film having aluminum (thickness: 40 μm) and a resin layer covering both sides of the battery element so that the ends of the positive electrode sheet and the negative electrode sheet protrude from the bag. Subsequently, each nonaqueous electrolyte solution obtained in the Examples and Comparative Examples was injected into the bag. The bag was vacuum-sealed to obtain a sheet-like nonaqueous electrolyte secondary battery. Furthermore, in order to improve the adhesiveness between electrodes, the sheet-like nonaqueous electrolyte secondary battery was sandwiched between glass plates and pressurized.

(Evaluation of discharge capacity maintenance ratio and internal resistance ratio)
With respect to the obtained nonaqueous electrolyte secondary battery, at 25 ° C., the charge rate was 0.3 C, the discharge rate was 0.3 C, the charge end voltage was 4.2 V, and the discharge end voltage was 2.5 V. A charge / discharge cycle test was conducted. Table 3 shows the discharge capacity retention rate (%) after 200 cycles and the internal resistance ratio after 200 cycles.
The “discharge capacity retention rate (%)” after 200 cycles is the ratio (percentage) of the discharge capacity (mAh) after the 200 cycle test to the discharge capacity (mAh) after the 10 cycle test. The “internal resistance ratio” after 200 cycles represents the resistance after the 200 cycle test as a relative value when the resistance before the cycle test is 1.

(Measurement of gas generation amount)
Separately from the batteries used in the cycle test, non-aqueous electrolyte secondary batteries having the same configuration including the electrolytes of the examples and comparative examples were prepared. This battery was charged to 4.2 V at 25 ° C. with a current corresponding to 0.2 C, and then discharged to 3 V with a current corresponding to 0.2 C for 3 cycles to stabilize the battery. Next, after charging the battery to 4.2 V again at a charge rate of 0.3 C, the battery was stored at a high temperature of 60 ° C. and 168 hours. Then, it cooled to room temperature, measured the volume of the battery by Archimedes method, and calculated | required the gas generation amount from the volume change before and behind a preservation | save.

From Table 3 and Table 4, the non-aqueous electrolyte secondary battery using the non-aqueous electrolyte of each example containing the compound 11, 13 to 21 or 23a which is the compound of the formula (1) is the non-aqueous electrolyte of the comparative example. Compared with the non-aqueous electrolyte secondary battery using the electrolytic solution, it can be seen that both the discharge capacity maintenance rate during the cycle test and the suppression of gas generation accompanying charging are superior. Moreover, it was confirmed that the compound of Formula (1) is excellent also in the point that there is little increase in internal resistance by a charging / discharging cycle.

DESCRIPTION OF SYMBOLS 1 ... Power storage device (nonaqueous electrolyte secondary battery), 2 ... Positive electrode current collector, 3 ... Positive electrode active material layer, 4 ... Positive electrode plate, 5 ... Negative electrode current collector, 6 ... Negative electrode active material layer, 7 ... Negative electrode Plate, 8 ... non-aqueous electrolyte, 9 ... separator.

Claims

The additive for non-aqueous electrolyte containing the compound represented by following formula (1).

[In the formula (1), X represents a sulfonyl group or a carbonyl group, R 1 and R 2 each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 4 carbon atoms, An optionally substituted alkenyl group having 2 to 4 carbon atoms, an alkynyl group having 2 to 4 carbon atoms which may be substituted, or an aryl group which may be substituted; A divalent hydrocarbon group having 1 to 3 carbon atoms, or a divalent hydrocarbon group having 1 to 3 carbon atoms which may be substituted, and a divalent group consisting of an oxygen atom constituting a cyclic structure together with the hydrocarbon group Show. ]
The additive for non-aqueous electrolyte according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (1a).

Wherein (1a), R 1, R 2 and X have the same meanings as R 1, R 2 and X in the formula (1). ]
The additive for non-aqueous electrolyte according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (1b).

Wherein (1b), R 1, R 2 and X have the same meanings as R 1, R 2 and X in the formula (1). ]
R 1 and R 2 each independently represents an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, an aryl group or a halogenated aryl group, and 2 carbon atoms which may be substituted with a halogen atom. An alkenyl group having 4 to 4, an alkynyl group having 2 to 4 carbon atoms which may be substituted with a halogen atom, an aryl group which may be substituted with a halogen atom, an alkyl group or a halogenated alkyl group, or a hydrogen atom The additive for a non-aqueous electrolyte according to any one of claims 1 to 3.
The additive for non-aqueous electrolyte according to claim 4, wherein the halogen atom is a fluorine atom, the halogenated aryl group is a fluorinated aryl group, and the halogenated alkyl group is a fluorinated alkyl group.
The additive for non-aqueous electrolyte according to any one of claims 1 to 5, wherein X in the formula (1) is a sulfonyl group.
A non-aqueous electrolyte containing the additive for non-aqueous electrolyte according to any one of claims 1 to 6, a non-aqueous solvent, and an electrolyte.
The nonaqueous electrolytic solution according to claim 7, wherein the nonaqueous solvent contains a cyclic carbonate and a chain carbonate.
The nonaqueous electrolytic solution according to claim 7 or 8, wherein the electrolyte contains a lithium salt.
An electricity storage device comprising the nonaqueous electrolytic solution according to any one of claims 7 to 9, and a positive electrode and a negative electrode.
A lithium ion battery comprising the nonaqueous electrolytic solution according to any one of claims 7 to 9, and a positive electrode and a negative electrode.
A lithium ion capacitor comprising the nonaqueous electrolytic solution according to any one of claims 7 to 9, and a positive electrode and a negative electrode.