WO2015037382A1

WO2015037382A1 - Electrolyte solution and secondary battery

Info

Publication number: WO2015037382A1
Application number: PCT/JP2014/071281
Authority: WO
Inventors: 信也須藤; 伊紀子島貫; 川崎　大輔; 石川　仁志
Original assignee: 日本電気株式会社
Priority date: 2013-09-13
Filing date: 2014-08-12
Publication date: 2015-03-19
Also published as: JPWO2015037382A1

Abstract

The purpose of the present invention is to provide an electrolyte solution which is capable of suppressing gas generation. One embodiment of the present invention is an electrolyte solution which contains a supporting salt, a nonaqueous solvent that dissolves the supporting salt, a chain disulfone compound represented by formula (1), and an acid anhydride. This embodiment of the present invention is able to provide an electrolyte solution which has excellent capacitance retention rate and is capable of suppressing gas generation.

Description

Electrolyte and secondary battery

The present invention relates to an electrolytic solution and a secondary battery including the electrolytic solution.

Along with the rapid market expansion of mobile tablet terminals, smartphones, electric cars, stationary storage systems, etc., secondary batteries with excellent performance are required.

One method for improving the performance of the secondary battery is to suppress the decomposition reaction of the electrolyte by forming a protective film on the electrode surface. For example, a method of forming a film on the electrode surface by adding an additive to the electrolytic solution has been proposed.

Patent Document 1 discloses a lithium ion secondary battery having an electrolytic solution containing a chain disulfonic acid ester compound and a cyclic monosulfonic acid ester compound or a chain disulfonic acid ester compound.

Patent Document 2 discloses at least one compound selected from a cyclic carbonate compound having an unsaturated bond and an acid anhydride, a sulfur-containing organic compound, a fluorine-containing aromatic compound having 9 or less carbon atoms, and an aliphatic hydrocarbon compound. And a secondary battery having an electrolytic solution containing at least one compound selected from fluorine-containing aliphatic hydrocarbon compounds.

Patent Document 3 has an electrolyte containing an aprotic solvent and a chain disulfonic acid ester compound, and has a negative electrode containing an oxide that absorbs and releases alkali metal or alkaline earth metal as a negative electrode active material. A secondary battery is described.

Patent Document 4 discloses a secondary battery having a positive electrode including a lithium-containing composite oxide having an electrolytic solution containing an aprotic solvent and a chain disulfonic acid ester compound and having a charge / discharge region at 4.3 V or higher. Is described.

Patent Document 5 contains a monofluorophosphate and / or a difluorophosphate, and further includes a compound represented by a predetermined formula, a nitrile compound, an isocyanate compound, a phosphazene compound, a disulfonic acid ester compound, a sulfide compound, and a disulfide. A nonaqueous electrolytic solution containing at least one compound selected from the group consisting of a compound, an acid anhydride, a lactone compound having a substituent at the α-position, and a compound having a carbon-carbon triple bond is described.

Patent Document

6 or 7 describes an electrolytic solution containing a sulfonic acid ester compound represented by a predetermined formula.

Patent Document 8 describes a secondary battery having an electrolytic solution containing a chain disulfonic acid ester compound.

Patent Document 9 describes a secondary battery having an electrolytic solution containing a chain disulfonic acid ester compound represented by the formula (II).

Patent Document 10 discloses a cyclic sulfonic acid ester compound having two sulfonyl groups.

Non-Patent Documents 1 to 3 disclose a method for producing a chain disulfonic acid ester compound.

JP 2006-324194 A JP 2003-331915 A Japanese Patent Laid-Open No. 2005-203341 JP 2005-203342 A JP 2008-277004 A JP 2007-73318 A JP 2013-109930 A JP 2006-244776 JP 2011-187235 A Japanese Patent Publication No. 5-44946

However, there is a demand for higher performance of secondary batteries, and various battery characteristics are required to be improved.

An object of the present invention is to provide an electrolytic solution that has an excellent capacity retention rate and can suppress gas generation.

One of the embodiments is
An electrolytic solution containing a supporting salt, a nonaqueous solvent that dissolves the supporting salt, a chain disulfone compound represented by the following formula (1), and an acid anhydride.

(In the formula (1), n is an integer of 1, 2 or 3. R ₁ and R ₂ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or An unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, —SO ₂ X ₁ (X ₁ Is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), -SY ₁ (Y ₁ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), -COZ (Z is A hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), or a halogen atom, R ₃ and R ₄ each independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. Group, substituted or unsubstituted carbon number An alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted phenoxy group, a hydroxy group, a halogen atom, —NX ₂ X ₃ (X ₂ and X ₃ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), or —NY ₂ CONY ₃ Y ₄ (Y ₂ to Y ₄ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms).

One of the embodiments is a secondary battery having the above electrolytic solution.

According to this embodiment, it is possible to provide an electrolytic solution that has an excellent capacity retention rate and can suppress gas generation.

It is a schematic sectional drawing which shows the structural example of the secondary battery of this embodiment.

Hereinafter, embodiments of the present invention will be described.

[1] Electrolytic Solution The electrolytic solution of the present embodiment includes a supporting salt, a nonaqueous solvent that dissolves the supporting salt, a chain disulfone compound represented by the formula (1), and an acid anhydride.

When the chain disulfone compound is added to the electrolytic solution, the capacity retention rate of the secondary battery can be improved, but it has been found that gas generation accompanying charging / discharging increases and the volume increase of the battery increases. . In this embodiment, by adding an acid anhydride to an electrolytic solution containing a chain disulfone compound, even when the chain disulfone compound is included, gas generation can be suppressed while maintaining the effect of improving the capacity retention rate. I understood.

The following reason can be considered as a mechanism of the synergistic effect which suppresses gas generation by adding an acid anhydride to the electrolyte solution containing a chain | strand-shaped disulfone compound. As described above, the chain disulfone compound represented by the formula (1) is decomposed by an electrochemical oxidation-reduction reaction during the charge / discharge reaction to form a film on the surface of the negative electrode, and decomposes the electrolytic solution and the supporting salt. Although the chain disulfone compound alone can be suppressed, gas generation accompanying charge / discharge increases. Therefore, if an acid anhydride is further added to the electrolyte solution in addition to the chain disulfone compound, the acid anhydride will be decomposed before the chain disulfonic acid at the first charge, and excessive decomposition of the chain disulfone compound will occur. Is suppressed. Moreover, in addition to chain | strand-shaped disulfonic acid, an acid anhydride contributes also in formation of a film | membrane, and a favorable film | membrane is formed. As a result, it is considered that the electrolytic solution of the present embodiment can suppress gas generation while maintaining the effect of improving the capacity retention rate. In addition, the above theory is estimation and does not restrict | limit this invention.

Hereinafter, the components of the present invention will be described.

<Linear disulfone compound>
The chain disulfone compound in the present embodiment is represented by the following formula (1).

In the present specification, “fluoroalkyl group” and “fluoroalkoxy group” each represent a group in which at least one hydrogen atom bonded to a carbon atom of a corresponding alkyl group or alkoxy group is substituted with a fluorine atom.

“Fluoroalkyl group” and “fluoroalkoxy group” are concepts including “perfluoroalkyl group” and “perfluoroalkoxy group”, respectively. The “perfluoroalkyl group” and “perfluoroalkoxy group” represent groups in which all of the hydrogen atoms bonded to the carbon atoms of the corresponding alkyl group and alkoxy group are substituted with fluorine atoms, respectively.

In the formula (1), n is preferably 1 or 2, and more preferably 1.

In formula (1), R ₁ and R ₂ are independent for each carbon atom to which they are bonded.
Examples of the substituent for R ₁ and R ₂ include halogen atoms such as a chlorine atom, a fluorine atom, a bromine atom, and an iodine atom, a hydroxy group, an amino group, an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. Examples thereof include an alkoxy group, a fluoroalkyl group having 1 to 4 carbon atoms, and a fluoroalkoxy group having 1 to 4 carbon atoms. R ₁ and R ₂ may each independently have one substituent and may have a plurality of substituents.

Examples of the substituent for R ₃ and R ₄ include a halogen atom such as a chlorine atom, a fluorine atom, a bromine atom, and an iodine atom, a hydroxy group, an amino group, an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. An alkoxy group, a fluoroalkyl group having 1 to 4 carbon atoms, a fluoroalkoxy group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms or a group containing —SO ₂ — in an alkoxy group having 1 to 4 carbon atoms (For example, —OSO ₂ CH ₂ SO ₂ Cl) is introduced. R ₃ and R ₄ may each independently have one substituent and may have a plurality of substituents.

When a carbon atom is contained in the substituent, this carbon atom is not included in the number of “carbon number” in the description such as “substituted or unsubstituted alkyl group having 1 to 5 carbon atoms”.

In R ₁ and R ₂ , the alkyl group, alkoxy group, fluoroalkyl group, and fluoroalkoxy group may be linear or branched. In R ₃ and R ₄ , the alkyl group, alkoxy group, fluoroalkyl group, and fluoroalkoxy group may be linear or branched.

Further, the substituent in the “fluoroalkyl group” or “fluoroalkoxy group” is a substituent other than a fluorine atom.

As the chain disulfone compound, one kind may be used alone, or two or more kinds may be used in combination.

In the chain disulfone compound represented by the formula (1), n is preferably 1, and is preferably a compound represented by the following formula (2).

In the formula _{_{(2), R 1 ~ R}} 4 are the same as _R 1 ~ _{R 4} described for the above equation (1).

The chain disulfone compound represented by the formula (1) or (2) is an acyclic compound and can be produced without a cyclization reaction at the time of synthesis. For example, referring to Non-Patent Documents 1 to 3 Can be synthesized. It can also be obtained as a by-product of the synthesis of the cyclic disulfonic acid ester disclosed in Patent Document 10. As described above, since the chain disulfone compound represented by the formula (1) is easy to synthesize, there is a possibility that an inexpensive electrolytic solution can be provided.

R ₁ and R _{2 in} formula (1) or (2) are the ease of film formation on the electrode, the stability of the compound, the ease of handling, the solubility in a solvent, the ease of synthesis of the compound, From the viewpoint of price and the like, each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a halogen atom, or —SO ₂ X ₁ (X ₁ represents a substituted or unsubstituted carbon number of 1 to 5 It is preferable that it represents an alkyl group. R ₁ and R ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms. preferable. R ₁ and R ₂ are more preferably each independently a hydrogen atom or a methyl group. R ₁ and R ₂ are each particularly preferably a hydrogen atom. In particular, when n is 1, if R ₁ and R ₂ are hydrogen atoms, a methylene moiety sandwiched between two sulfonyl groups is activated, and reductive decomposition and film formation on the negative electrode are likely to occur.

R ₃ and R _{4 in} formula (1) or (2) are each independently substituted or unsubstituted carbon from the viewpoints of stability of the compound, ease of synthesis of the compound, solubility in a solvent, price, and the like. An alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted phenoxy group, a hydroxy group, a halogen atom, or —NX ₂ X ₃ (X ₂ and X ₃ are Each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms). R ₃ and R ₄ are each independently a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted carbon group having 1 to 5 carbon atoms. More preferably, it is a 5 fluoroalkyl group, a substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, or a substituted or unsubstituted phenoxy group. R ₃ and R ₄ are more preferably each independently a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms or a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms. Further, it is particularly preferable that one or both of R ₃ and R ₄ is a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms. For the same reason, the substituted or unsubstituted alkyl group having 1 to 5 carbon atoms is preferably a methyl group or an ethyl group, and the substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms is preferably a methoxy group or An ethoxy group is preferred.

The compound represented by the formula (1), particularly the compound represented by the formula (2) has a small LUMO because it has two sulfonyl groups, and solvent molecules and monosulfonic acids generally used in electrolytes. It has a smaller LUMO value than the ester. Therefore, the compound is easily reduced. For example, the following compound No. The LUMO of 1 is −0.86 eV, which is a small value, according to semiempirical molecular orbital calculation. For this reason, the compound No. 1 is preceded by a solvent (LUMO: about 1.2 eV) composed of cyclic carbonates and chain carbonates. 1 reduction film is formed on the negative electrode. And it is thought that the film | membrane formed in the negative electrode plays the role which suppresses decomposition | disassembly of a solvent molecule. Since the film suppresses the decomposition of the solvent molecules, a highly resistant solvent molecule decomposition film is hardly formed on the negative electrode. Therefore, improvement in battery characteristics can be expected. In addition, the compound represented by the formula (2) has a form in which an electron-withdrawing sulfonyl group is bonded to a carbon atom via a methylene group, and reduction on the negative electrode by activation of the carbon atom of the methylene group. It is considered that decomposition and film formation are likely to occur.

Specific examples of the chain disulfone compound represented by the formula (1) are shown below, but the present invention is not particularly limited thereto.

A chain disulfone compound may be used individually by 1 type, or may use 2 or more types together.
The content of the chain disulfone compound represented by the formula (1) in the electrolytic solution is not particularly limited, but is preferably 0.005 to 10% by mass. When the content of the chain disulfone compound is 0.005% by mass or more, a film forming effect can be sufficiently obtained. Moreover, when content of a chain | strand-shaped disulfone compound is 10 mass% or less, the increase in the viscosity of electrolyte solution and the increase in resistance accompanying it can be suppressed. The content of the chain disulfone compound in the electrolytic solution is more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more. preferable. The content of the chain disulfone compound in the electrolytic solution is more preferably 8% by mass or less, further preferably 5% by mass or less, and particularly preferably 3% by mass or less.

<Acid anhydride>
The acid anhydride in this embodiment is a compound having at least one acid anhydride structure in one molecule, and the type of acid anhydride is not limited. The acid anhydride may be a compound having a plurality of acid anhydride structures in one molecule. Examples of the acid anhydride in the present embodiment include an anhydride of carboxylic acid, an anhydride of sulfonic acid, and an anhydride of carboxylic acid and sulfonic acid.

Specific examples of carboxylic acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, succinic anhydride, crotonic anhydride, trifluoroacetic anhydride, pentafluoropropionic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride , Glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6- Tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, phthalic anhydride, pyromellitic anhydride, fluorosuccinic anhydride, tetrafluoro And succinic anhydride. These may be used alone or in combination of two or more.

Specific examples of the sulfonic acid anhydride include methanesulfonic acid anhydride, ethanesulfonic acid anhydride, propanesulfonic acid anhydride, butanesulfonic acid anhydride, pentanesulfonic acid anhydride, hexanesulfonic acid anhydride, vinylsulfonic acid anhydride. Benzenesulfonic acid anhydride, trifluoromethanesulfonic acid anhydride, 2,2,2-trifluoroethanesulfonic acid anhydride,
Pentafluoroethanesulfonic anhydride, 1,2-ethanedisulfonic anhydride, 1,3-propanedisulfonic anhydride, 1,4-butanedisulfonic anhydride, 1,2-benzenedisulfonic anhydride, tetrafluoro -1,2-ethanedisulfonic anhydride, hexafluoro-1,3-propanedisulfonic anhydride, octafluoro-1,4-butanedisulfonic anhydride, 3-fluoro-1,2-benzenedisulfonic anhydride 4-fluoro-1,2-

benzenedisulfonic anhydride

3,4,5,6-tetrafluoro-1,2-benzenedisulfonic anhydride and the like. These may be used alone or in combination of two or more.

Specific examples of carboxylic acid and sulfonic acid anhydrides include acetic acid methanesulfonic acid anhydride, ethane sulfonic acid anhydride, acetic acid propane sulfonic acid anhydride, propionic acid methanesulfonic acid anhydride, propionic acid ethanesulfonic acid anhydride , Propionic acid propanesulfonic acid anhydride, trifluoroacetic acid methanesulfonic acid anhydride, trifluoroacetic acid ethanesulfonic acid anhydride, trifluoroacetic acid propanesulfonic acid anhydride, acetic acid trifluoromethanesulfonic acid anhydride, acetic acid 2,2,2 -Trifluoroethanesulfonic anhydride, pentafluoroethanesulfonic acid anhydride, trifluoromethanesulfonic anhydride, trifluoroacetic acid 2,2,2-trifluoroethanesulfonic anhydride, pentafluorotrifluoroacetate No ethanesulfonic acid 3-sulfopropionic anhydride, 2-methyl-3-sulfopropionic anhydride, 2,2-dimethyl-3-sulfopropionic anhydride, 2-ethyl-3-sulfopropionic anhydride, 2, 2-diethyl-3-sulfopropionic anhydride, 2-fluoro-3-sulfopropionic anhydride, 2,2-difluoro-3-sulfopropionic anhydride, 2,2,3,3-tetrafluoro-3 -Sulfopropionic anhydride, 2-sulfobenzoic anhydride, 3-fluoro-2-sulfobenzoic anhydride, 4-fluoro-2-sulfobenzoic anhydride, 5-fluoro-2-sulfobenzoic anhydride 6-fluoro-2-sulfobenzoic anhydride, 3,6-difluoro-2-sulfobenzoic anhydride, 3,4,5,6-tetrafluoro-2-sulfobenzoic anhydride, 3- Trifluoromethyl-2-sulfobenzoic anhydride, 4-trifluoromethyl-2-sulfobenzoic anhydride, 5-trifluoromethyl-2-sulfobenzoic anhydride, 6-trifluoromethyl-2-sulfobenzoic acid An acid anhydride etc. are mentioned. These may be used alone or in combination of two or more.

The acid anhydride is preferably a carboxylic acid anhydride. The carboxylic acid anhydride is preferably a cyclic carboxylic acid anhydride represented by the following formula (I) or (II) or a chain carboxylic acid anhydride represented by the following formula (III). The cyclic carboxylic acid anhydride represented by (I) or (II) is more preferred, and the cyclic carboxylic acid anhydride represented by the following formula (II) is more preferred.

(In formula (I), R ₁₁ represents a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms, a substituted or unsubstituted carbon group having 5 to 12 carbon atoms, and A cycloalkanediyl group, a substituted or unsubstituted benzenediyl group, or a divalent group having 2 to 6 carbon atoms to which an alkylene group is bonded via an ether bond).

(In the formula (II), R ₁₀₃ represents a single bond, a double bond, a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 3 carbon atoms, an oxygen atom, or A divalent group having 2 to 4 carbon atoms to which an alkylene group is bonded via an ether bond).

In the formula (I) or (II), the alkylene group and alkenylene group of R ₁₁ and R ₁₀₃ may be linear or branched.
In the formula (I), the number of carbon atoms of the alkylene group represented by R ₁₁ is preferably 1, 2, 3 or 4. The carbon number of the alkenylene group of R ₁₁ is preferably 2, 3 or 4.
In the formula (I), the number of carbon atoms of the cycloalkanediyl group represented by R ₁₁ is preferably 5, 6, 7, 8, 9, or 10.
In the formula (I), R ₁₁ is preferably a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms or a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms.

In the formula (I) or (II), the substituent of R ₁₁ or R ₁₀₃ is, for example, an alkyl group having 1 to 5 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group), carbon C2-C6 alkenyl group (for example, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group), C1-C5 alkoxy group (for example, methoxy group, ethoxy group, n-propoxy group) , Iso-propoxy group, n-butoxy group, tert-butoxy group), amino group (including dimethylamino group and methylamino group), carboxy group, hydroxy group, vinyl group, cyano group, or halogen atom (for example, chlorine Atom, bromine atom). R ₁₁ or R ₁₀₃ may have one substituent or a plurality of substituents.

Note that when R ₁₀₃ is a single bond or a double bond, a single bond or a double bond is formed between carbon atoms adjacent to R ₁₀₃ .

In formula (II), R ₁₀₃ is preferably a single bond, a double bond, a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, or a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms. .

Specific examples of the cyclic carboxylic acid anhydride represented by the formula (I) include the following compounds.

(In Formula (III), R ₁₀₁ and R ₁₀₂ are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a substituted or unsubstituted group, A heterocyclic group having 4 to 12 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms.

In R ₁₀₁ and R ₁₀₂ of the formula (III), the number of carbon atoms of the alkyl group is preferably 1, 2, 3, 4 or 5, and more preferably 1, 2, 3 or 4. The aryl group preferably has 6, 7, 8, 9, or 10 carbon atoms. The number of carbon atoms of the heterocyclic group is preferably 4, 5, 6, 7, 8, 9 or 10, and more preferably 4, 5, 6, 7 or 8. The number of carbon atoms in the alkenyl group is preferably 2, 3, 4 or 5, and more preferably 2, 3 or 4. Moreover, the alkyl group or alkenyl group may be linear or branched.

Examples of the substituent for R ₁₀₁ and R ₁₀₂ include an alkyl group having 1 to 5 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group), and a cycloalkyl group having 3 to 6 carbon atoms (for example, Cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group), alkenyl group having 2 to 6 carbon atoms (for example, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group), 1 to 5 carbon atoms Alkoxy groups (for example, methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, tert-butoxy group), alkylcarbonyl group having 2 to 6 carbon atoms, aryl having 7 to 11 carbon atoms Carbonyl group, alkoxycarbonyl group having 2 to 6 carbon atoms (for example, methoxycarbonyl group, ethoxycarbonyl group, tert-but Sicarbonyl group), aryloxycarbonyl group having 7 to 11 carbon atoms, alkylcarbonyloxy group having 2 to 6 carbon atoms, arylcarbonyloxy group having 7 to 11 carbon atoms, aryl group having 6 to 12 carbon atoms (for example, phenyl Group, naphthyl group), aryloxy group having 6 to 10 carbon atoms (for example, phenoxy group, naphthoxy group), alkylthio group having 1 to 5 carbon atoms (for example, methylthio group, ethylthio group, n-propylthio group, iso-propylthio group) Group, n-butylthio group, tert-butylthio group), arylthio group having 6 to 10 carbon atoms (for example, phenylthio group, naphthylthio group), alkylthiocarbonyl group having 2 to 6 carbon atoms, arylthiocarbonyl having 7 to 11 carbon atoms Group, alkylsulfinyl group having 1 to 5 carbon atoms, arylsulfinyl group having 6 to 10 carbon atoms Group, alkylsulfonyl group having 1 to 5 carbon atoms, arylsulfonyl group having 6 to 10 carbon atoms, heteroatom-containing aromatic ring group having 4 to 8 carbon atoms (for example, furyl group, thienyl group), amino group (dimethylamino) Group, including a methylamino group), a carboxy group, a hydroxy group, a cyano group, or a halogen atom (for example, a chlorine atom or a bromine atom). R ₁₀₁ and R ₁₀₂ may each independently have one substituent, and may have a plurality of substituents.

An acid anhydride can be used alone or in combination of two or more.

In the formula (III), R ₁₀₁ and R ₁₀₂ are preferably each independently an alkyl group having 1 to 5 carbon atoms. The alkyl group may be linear or branched. The alkyl group preferably has 1, 2, 3 or 4 carbon atoms.

Specific examples of the chain carboxylic acid anhydride represented by the formula (III) include the following compounds.

As the cyclic carboxylic acid anhydride, succinic anhydride and maleic anhydride are preferable.

As the chain carboxylic acid anhydride, acetic anhydride, propionic anhydride, and butyric anhydride are preferable.

The content of the acid anhydride in the electrolytic solution is not particularly limited, but is preferably 0.005 to 10% by mass. When the content of the acid anhydride is 0.005% by mass, a synergistic effect between the chain disulfone compound and the acid anhydride can be effectively obtained. Moreover, when content of an acid anhydride is 10 mass% or less, it can suppress that the membrane | film | coat by decomposition | disassembly of an acid anhydride is formed thick, and can reduce influence on battery characteristics, such as a capacity | capacitance maintenance factor. The content of the acid anhydride in the electrolytic solution is more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more. . The content of the acid anhydride in the electrolytic solution is more preferably 8% by mass or less, further preferably 5% by mass or less, and particularly preferably 3% by mass or less.

In this embodiment, the molar ratio B / A between the concentration A of the chain disulfone compound in the electrolyte and the concentration B of the acid anhydride in the electrolyte is preferably in the range of 1/10 to 5/1. More preferably, it is in the range of 1/9 to 4/1.

Further, the total content C of the concentration A of the chain disulfone compound in the electrolytic solution and the concentration B of the acid anhydride electrolytic solution is preferably in the range of 1.0 mol / L or less, and is preferably 0.75 mol / L. More preferably, it is in the following range, and further preferably in the range of 0.5 mol / L or less. By setting the concentration A of the chain disulfone compound and the concentration B of the acid anhydride in such a range, the effect of suppressing gas generation can be obtained more effectively while obtaining the effect of improving or maintaining the capacity retention rate. Can do.

In addition, the electrolyte solution may contain other additives other than the chain disulfone compound and the acid anhydride, if necessary. Examples of other additives include an overcharge inhibitor and a surfactant.

<Nonaqueous solvent>
The non-aqueous solvent is not particularly limited, and examples thereof include carbonates such as cyclic carbonates and chain carbonates, aliphatic carboxylic acid esters, γ-lactones, cyclic ethers, and chain ethers. And fluorine derivatives thereof. These can be used individually by 1 type or in combination of 2 or more types.

Examples of cyclic carbonates include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC).

Examples of chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC).

Examples of the aliphatic carboxylic acid esters include methyl formate, methyl acetate, and ethyl propionate.

Examples of γ-lactones include γ-butyrolactone.
Examples of cyclic ethers include tetrahydrofuran and 2-methyltetrahydrofuran.

Examples of chain ethers include 1,2-diethoxyethane (DEE), ethoxymethoxyethane (EME), and the like.

Other non-aqueous solvents include, for example, dimethyl sulfoxide, 1,3-dioxolane, formamide, acetamide, dimethylformamide, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivatives , Sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, N-methylpyrrolidone, fluorinated carboxylic acid ester, methyl-2 , 2,2-trifluoroethyl carbonate, methyl-2,2,3,3,3-pentafluoropropyl carbonate, trifluoromethyl ethylene carbonate, monofluoromethyl ethyl Emissions carbonate, difluoromethyl ethylene carbonate, 4,5-difluoro-1,3-dioxolan-2-one, mono-fluoroethylene carbonate, and the like. These can be used individually by 1 type or in combination of 2 or more types.

The non-aqueous solvent preferably contains carbonates. The carbonates include cyclic carbonates or chain carbonates. Since carbonates have a large relative dielectric constant, the ion dissociation property of the electrolytic solution is improved, and further, the viscosity of the electrolytic solution is lowered, so that the ion mobility is improved. However, when carbonates having a carbonate structure are used as the non-aqueous solvent for the electrolytic solution, the carbonates tend to decompose and generate gas containing CO ₂ . In particular, in the case of a laminated laminate type secondary battery, when gas is generated inside the battery, the problem of blistering appears prominently and tends to lead to performance degradation. Therefore, in this embodiment, by adding the compound of this embodiment to a non-aqueous solvent containing carbonates, the SEI film formed by the chain disulfone compound and the acid anhydride suppresses decomposition of the carbonates. Gas generation can be suppressed. Therefore, in the present embodiment, the electrolytic solution preferably contains carbonates as a non-aqueous solvent in addition to the chain disulfone compound and the acid anhydride. With such a configuration, even when carbonates are used as a non-aqueous solvent, gas generation can be reduced, and a secondary battery having excellent performance can be provided. The content of carbonates in the electrolytic solution is, for example, 30% by mass or more, preferably 50% by mass or more, and more preferably 70% by mass or more.

<Supporting salt>
As the supporting salt, is not particularly limited, for _{_{_{example, LiPF 6, LiAsF 6, LiAlCl}}} 4, LiClO 4, LiBF 4, LiSbF 6, LiCF 3 SO 3, LiC 4 F 9 SO 3, Li (CF 3 And lithium salts such as SO ₂ ) ₂ and LiN (CF ₃ SO ₂ ) ₂ . A supporting salt can be used individually by 1 type or in combination of 2 or more types.

The concentration of the supporting salt in the electrolytic solution is preferably 0.5 to 1.5 mol / l. By setting the concentration of the supporting salt within this range, it becomes easy to adjust the density, viscosity, electrical conductivity, and the like to an appropriate range.

[2] Negative Electrode The secondary battery of the present embodiment includes a negative electrode having a negative electrode active material. The negative electrode active material can be bound on the negative electrode current collector by a negative electrode binder. As the negative electrode, for example, one in which a negative electrode active material layer including a negative electrode active material and a negative electrode binder is formed on a negative electrode current collector can be used.

Although it does not restrict | limit especially as a negative electrode active material, For example, the metal (a) which can be alloyed with lithium metal, lithium, the metal oxide (b) which can occlude and discharge | release lithium ion, or occlude lithium ion And carbon material (c) that can be released. A negative electrode active material can be used individually by 1 type or in combination of 2 or more types.

Examples of the metal (a) include Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, or alloys of two or more thereof. It is done. Two or more of these metals or alloys may be used in combination. These metals or alloys may contain one or more non-metallic elements. Among these, it is preferable to use silicon, tin, or an alloy thereof as the negative electrode active material. By using silicon or tin as the negative electrode active material, a lithium secondary battery excellent in weight energy density and volume energy density can be provided.

Examples of the metal oxide (b) include silicon oxide, aluminum oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and composites thereof. Among these, it is preferable to use silicon oxide as the negative electrode active material. The metal oxide (b) can contain one or more elements selected from nitrogen, boron and sulfur in a range of, for example, 0.1 to 5% by mass.

Examples of the carbon material (c) include graphite, amorphous carbon, diamond-like carbon, carbon nanotube, or a composite thereof.

The negative electrode binder is not particularly limited, and examples thereof include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and styrene-butadiene copolymer rubber. , Polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamideimide, polyacrylic acid and the like.

The negative electrode can be produced, for example, by forming a negative electrode active material layer containing a negative electrode active material and a negative electrode binder on a negative electrode current collector. This negative electrode active material layer can be formed by a general slurry coating method. Specifically, a negative electrode can be obtained by preparing a slurry containing a negative electrode active material, a negative electrode binder, and a solvent, applying the slurry onto a negative electrode current collector, drying, and pressing as necessary. it can. Examples of the method for applying the negative electrode slurry include a doctor blade method, a die coater method, and a dip coating method. A negative electrode can also be obtained by forming a negative electrode active material layer in advance and then forming a thin film of copper, nickel or an alloy thereof as a current collector by a method such as vapor deposition or sputtering.

Also, as the negative electrode binder, a water-dispersed polymer can be used. The negative electrode binder can be used in an aqueous dispersion state. Examples of the water-dispersed polymer include styrene butadiene polymer, acrylic acid polymer, polytetrafluoroethylene, polyacrylate, and polyurethane. These polymers can be used by dispersing in water. More specifically, examples of the water-dispersed polymer include natural rubber (NR), styrene butadiene rubber (SBR), acrylonitrile / butadiene copolymer rubber (NBR), and methyl methacrylate / butadiene copolymer rubber (MBR). Chloroprene rubber (CR), acrylic rubber (ABR), styrene butadiene / styrene copolymer (SBS), butyl rubber (IIR), thiocol, urethane rubber, silicon rubber, or fluorine rubber. These can be used individually by 1 type or in combination of 2 or more types.

Moreover, when using an aqueous dispersion polymer as a negative electrode binder, it is preferable to use an aqueous thickener. Examples of the aqueous thickener include methyl cellulose, carboxymethyl cellulose (CMC), carboxymethyl cellulose sodium salt, carboxymethyl cellulose lithium salt, hydroxyethyl cellulose, polyethylene oxide, polyvinyl alcohol (PVA), polyvinyl pyrrolidone, sodium polyacrylate, polyacrylic acid. , Polyethylene glycol, or polyethylene oxide. These can be used individually by 1 type or in combination of 2 or more types.
The amount of the negative electrode binder is preferably 5 to 25 parts by mass with respect to 100 parts by mass of the negative electrode active material.

The content of the water-based thickener is, for example, 0.1 to 5.0 parts by weight, preferably 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the negative electrode active material.

Although water is preferably used as the dispersion medium, in addition to water, a water-soluble solvent such as an alcohol solvent, an amine solvent, a carboxylic acid solvent, or a ketone solvent may be included as the dispersion medium.

The negative electrode can be produced, for example, as follows. First, a negative electrode active material, an aqueous thickener, an aqueous dispersion polymer, and water are kneaded to prepare a negative electrode slurry. Next, this aqueous slurry is applied to a negative electrode current collector, dried, and pressed to produce a negative electrode.

The amount of water contained in the negative electrode active material layer after producing the negative electrode is preferably 50 to 1000 ppm. Further, the amount of water contained in the negative electrode active material layer is more preferably 500 ppm or less.

The amount of water contained in the negative electrode active material layer can be controlled by, for example, a drying process after the negative electrode active material layer is formed.

As the negative electrode current collector, aluminum, nickel, stainless steel, chromium, copper, silver, and alloys thereof are preferable in view of electrochemical stability. Examples of the shape include a foil, a flat plate, and a mesh.

The negative electrode active material layer may contain a conductive aid such as carbon from the viewpoint of improving conductivity.

The negative electrode slurry may contain other components as necessary, and examples of the other components include a surfactant and an antifoaming material. When the negative electrode slurry contains a surfactant, the dispersion stability of the negative electrode binder can be improved. Moreover, foaming at the time of apply | coating the slurry containing surfactant can be suppressed because a negative electrode slurry contains an antifoamer.

[3] Positive Electrode The secondary battery of this embodiment includes a positive electrode having a positive electrode active material. The positive electrode active material can be bound on the positive electrode current collector by a positive electrode binder. As the positive electrode, a positive electrode in which a positive electrode active material layer including a positive electrode active material and a positive electrode binder is formed on a positive electrode current collector can be used.

The positive electrode active material is not particularly limited, and examples thereof include lithium composite oxide and lithium iron phosphate. Further, at least part of the transition metal of these lithium composite oxides may be replaced with another element. Alternatively, a lithium composite oxide having a plateau at 4.2 V or more at the metal lithium counter electrode potential can be used. Examples of the lithium composite oxide include spinel type lithium manganese composite oxide, olivine type lithium containing composite oxide, and reverse spinel type lithium containing composite oxide.

Examples of the lithium composite oxide include lithium manganate having a layered structure such as LiMnO ₂ and Li _x Mn ₂ O ₄ (0 <x <2), lithium manganate having a spinel structure, or lithium manganate A part of Mn is replaced with at least one element selected from the group consisting of Li, Mg, Al, Co, B, Ti and Zn; lithium cobaltate such as LiCoO ₂ or part of Co of lithium cobaltate Is replaced with at least one element selected from the group consisting of Ni, Al, Mn, Mg, Zr, Ti, and Zn; lithium nickelate such as LiNiO ₂ or a part of Ni in lithium nickelate is Co, Al Replaced with at least one element selected from the group consisting of Mn, Mg, Zr, Ti, Zn; LiN i _1/3 Co _1/3 Mn _1/3 O ₂ or other specific transition metals such as lithium transition metal oxides, or some of the transition metals of the lithium transition metal oxides may be Co, Al, Mn And those substituted with at least one element selected from the group consisting of Mg, Zr; and those lithium transition metal oxides in which Li is excessive in comparison with the stoichiometric composition. In particular, as the lithium composite oxide, Li _α Ni _β Co _γ Al _δ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0.2), or Li _α Ni _β Co _γ Mn _δ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.4, γ ≦ 0.4), or a part of transition metals of these composite oxides may be Al, Mg, Zr. Those substituted with at least one element selected from the group consisting of: These lithium composite oxides may be used alone or in combination of two or more.

As the lithium composite oxide, a compound represented by the following formula is preferably exemplified.

Li _a (M _x Mn _2-x ) O ₄

(In the above formula, x satisfies 0 <x <2, a satisfies 0 <a <1.2, and M is at least one element selected from the group consisting of Ni, Co, Fe, Cr and Cu. .)

As the positive electrode active material, an active material that operates at a potential of 4.5 V or higher with respect to lithium (hereinafter also referred to as a 5 V class active material) can be used from the viewpoint that a high voltage can be obtained. When a 5V class active material is used, gas generation due to decomposition of the electrolytic solution or the like is likely to occur, but gas generation can be suppressed by using the electrolytic solution containing the compound of the present embodiment.

As the 5V class active material, for example, a lithium manganese composite oxide represented by the following formula (A) can be used.

Li _a (M _x Mn _2-xy Y _y ) (O _4-w Z _w ) (A)

(In formula (A), 0.4 ≦ x ≦ 1.2, 0 ≦ y, x + y <2, 0 ≦ a ≦ 1.2, and 0 ≦ w ≦ 1. M is Co, Ni, Fe, Cr. And Y is at least one selected from the group consisting of Li, B, Na, Mg, Al, Ti, Si, K and Ca, and Z is F and Cl. At least one selected from the group consisting of:

Also, as the 5V class active material, a spinel compound represented by the following formula (B) is preferably used among such metal complex oxides from the viewpoint of obtaining a sufficient capacity and extending the life.

LiNi _x Mn _2-xy A _y O ₄ (B)

(In the formula (B), 0.4 <x <0.6, 0 ≦ y <0.3, A is at least one selected from the group consisting of Li, B, Na, Mg, Al, Ti and Si. is there.).

In the formula (B), it is more preferable that 0 ≦ y <0.2.

As an active material that operates at a potential of 4.5 V or higher with respect to lithium, an olivine-type positive electrode active material can be given. Examples of the olivine-type 5V active material include LiCoPO ₄ and LiNiPO ₄ .

In addition, as an active material that operates at a potential of 4.5 V or more with respect to lithium, Si composite oxide can be given. As such Si complex oxide, the compound shown by a following formula (C) is mentioned, for example.

Li ₂ MSiO ₄ (C)

(In formula (C), M is at least one selected from the group consisting of Mn, Fe and Co).

Further, the active material that operates at a potential of 4.5 V or more with respect to lithium may have a layered structure. As a 5V class active material containing a layered structure, the compound shown by following formula (D) is mentioned, for example.

_{_{_{Li (M1 x M2 y Mn 2}}} -x-y) O 2 (D)

(In Formula (D), M1 is at least one selected from the group consisting of Ni, Co, and Fe. M2 is at least one selected from the group consisting of Li, Mg, and Al. 0.1 <x <0.5, 0.05 <y <0.3).

As the 5V class active material, lithium metal composite oxides represented by the following (E) to (G) can be used.

LiMPO ₄ (E)

(In formula (E), M is at least one selected from the group consisting of Co and Ni).

Li (M _y Mn _z ) O ₂ (F)

(In formula (F), 0.1 ≦ y ≦ 0.5, 0.33 ≦ z ≦ 0.7, and M is at least one selected from the group consisting of Li, Co, and Ni.) .

_{_{_{_{Li (Li x M y Mn z}}}} ) O 2 (G)

(In Formula (G), 0.1 ≦ x <0.3, 0.1 ≦ y ≦ 0.4, 0.33 ≦ z ≦ 0.7, and M is composed of Li, Co, and Ni. At least one selected from the group).

The positive electrode can be manufactured as follows, for example. First, a positive electrode slurry containing a positive electrode active material, a positive electrode binder, and a solvent (and a conductive auxiliary material if necessary) is prepared. This positive electrode slurry is applied onto a positive electrode current collector, dried, and pressurized as necessary to form a positive electrode active material layer on the positive electrode current collector, thereby producing a positive electrode.

The positive electrode binder is not particularly limited, and for example, the same as the negative electrode binder can be used. From the viewpoint of versatility and low cost, polyvinylidene fluoride is preferred. The content of the positive electrode binder is preferably in the range of 1 to 25 parts by mass with respect to 100 parts by mass of the positive electrode active material from the viewpoint of the binding force and energy density which are in a trade-off relationship. The range is more preferably in the range of 2 to 10 parts by mass. Examples of binders other than polyvinylidene fluoride (PVdF) include, for example, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polytetrafluoroethylene, Examples include polypropylene, polyethylene, polyimide, or polyamideimide. As the solvent, for example, N-methyl-2-pyrrolidone (NMP) can be used.

The positive electrode current collector is not particularly limited, and examples thereof include aluminum, titanium, tantalum, nickel, silver, and alloys thereof. Examples of the shape of the positive electrode current collector include a foil, a flat plate, and a mesh. As the positive electrode current collector, an aluminum foil can be suitably used.

In the production of the positive electrode, a conductive auxiliary material may be added for the purpose of reducing the impedance. Examples of the conductive auxiliary material include carbonaceous fine particles such as graphite, carbon black, and acetylene black.

[4] Separator The separator is not particularly limited. For example, a porous film such as polypropylene or polyethylene or a nonwoven fabric can be used. Moreover, as a separator, the ceramic coat separator which formed the coating containing a ceramic in the polymer base material used as a separator can also be used. Moreover, what laminated | stacked them can also be used as a separator.

[5] Exterior Body The exterior body is not particularly limited, and for example, a laminate film can be used. For example, in the case of a laminated laminate type secondary battery, a laminated film such as polypropylene or polyethylene coated with aluminum or silica can be used.

In the case of a secondary battery using a laminate film as the exterior body, the distortion of the electrode laminate becomes very large when gas is generated, compared to a secondary battery using a metal can as the exterior body. This is because the laminate film is more easily deformed by the internal pressure of the secondary battery than the metal can. Furthermore, when sealing a secondary battery using a laminate film as an exterior body, the internal pressure of the battery is usually lower than the atmospheric pressure, so there is no extra space inside, and if gas is generated, it is immediately It tends to lead to battery volume change and electrode stack deformation. However, the secondary battery according to the present embodiment can overcome such problems by using the electrolytic solution of the present embodiment.

[6] Secondary Battery The structure of the secondary battery according to the present embodiment is not particularly limited by the present invention. For example, an electrode laminate in which a positive electrode and a negative electrode are arranged to face each other and an electrolytic solution are provided. The structure included in the exterior body can be given.

Hereinafter, a laminated laminate type lithium ion secondary battery will be described as an example. FIG. 1 is a schematic configuration diagram illustrating an example of a basic configuration of the secondary battery according to the present embodiment. In the positive electrode, the positive electrode active material layer 1 is formed on the positive electrode current collector 3. In the negative electrode, the negative electrode active material layer 2 is formed on the negative electrode current collector 4. The positive electrode and the negative electrode are disposed to face each other with the separator 5 interposed therebetween. The separator 5 is laminated and disposed substantially parallel to the positive electrode active material layer 1 and the negative electrode active material layer 2. A pair of positive and negative electrodes and an electrolytic solution are enclosed in

outer casings

6 and 7. A positive electrode tab 9 connected to the positive electrode and a negative electrode tab 8 connected to the negative electrode are provided so as to be exposed from the exterior body. The shape of the secondary battery according to the present embodiment is not particularly limited, and examples thereof include a laminate outer shape, a cylindrical shape, a square shape, a coin shape, and a button shape.

Hereinafter, the embodiments of the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

Example 1
<Negative electrode>
Graphite was used as the negative electrode active material. 96: 2: 1: This negative electrode active material, styrene-butadiene copolymer rubber (SBR) as a negative electrode binder, carboxymethyl cellulose (CMC) as a thickener, and acetylene black as a conductive auxiliary material. Weighed at a mass ratio of 1. In addition, as SBR, the rubber particle dispersion (solid content 40 mass%) was used, and it measured and used so that the solid content of the binder might become the said mass ratio.

And these were mixed with water and the negative electrode slurry was prepared. After applying the negative electrode slurry to a copper foil having a thickness of 10 μm, heat treatment was performed in a nitrogen atmosphere and drying was performed to prepare a negative electrode.

<Positive electrode>
As the positive electrode active material, a mixture in which LiMn ₂ O ₄ and LiNi _0.5 Co _0.2 Mn _0.3 O ₂ were mixed at a mass ratio of 25:75 was used. This positive electrode active material, carbon black as a conductive auxiliary material, and polyvinylidene fluoride as a positive electrode binder were weighed at a mass ratio of 90: 5: 5. These were mixed with N-methylpyrrolidone to prepare a positive electrode slurry. The positive electrode slurry was applied to an aluminum foil having a thickness of 20 μm, dried, and further pressed to produce a positive electrode.

<Electrode laminate>
The obtained positive electrode and negative electrode were laminated via a polypropylene porous film as a separator. The ends of the positive electrode current collector not covered with the positive electrode active material and the negative electrode current collector not covered with the negative electrode active material were welded. Furthermore, the positive electrode terminal made from aluminum and the negative electrode terminal made from nickel were each welded to the welding location, and the electrode laminated body which has a planar laminated structure was obtained.

<Electrolyte>
A mixed solvent of EC and DEC (volume ratio: EC / DEC = 30/70) was used as the non-aqueous solvent. And said compound No. as a chain | strand-shaped disulfone compound represented by Formula (1). As a supporting salt, the above compound (201) as an acid anhydride is used as a supporting salt so that the content in the electrolytic solution is 0.5% by mass so that the content of 1 in the electrolytic solution is 1.7% by mass. LiPF ₆ was added to each of the mixed solvents so that the concentration in the electrolytic solution was 1 mol / L to prepare an electrolytic solution.

<Secondary battery>
The electrode laminate was accommodated in an aluminum laminate film as an exterior body, and an electrolyte solution was injected into the exterior body. Thereafter, the outer package was sealed while reducing the pressure to 0.1 atm, and a lithium ion secondary battery was produced.

<Evaluation>
(Volume increase in first charge / discharge)
The manufactured secondary battery was charged up to 4.15 V and discharged up to 3.0 V once in a thermostat kept at 25 ° C. And the volume increase amount of the secondary battery before and after the charging / discharging was evaluated. The volume was measured using the Archimedes method.

The “volume increase amount” was calculated as a relative value as follows. First, “volume increase rate (%)” was calculated by {(volume after charge / discharge) / (volume before start of charge / discharge) −1} × 100 (unit:%). And the relative value when the volume increase rate in the comparative example 1 was set to 1 was calculated, and it was set as the volume increase amount.
(Capacity maintenance rate at 45 ° C)
Next, the manufactured secondary battery was subjected to a charge and discharge test in a voltage range of 3.0 V to 4.15 V in a thermostat kept at 45 ° C., and the capacity retention rate (%) was evaluated. As a standard for the current value, Ic was the current that used up the initial discharge amount of the battery in one hour. Charging was performed at a current value Ic up to 4.15 V, followed by constant voltage charging for 2.5 hours in total. The discharge was a constant current discharge to 3.0 V at a current value Ic.

“Capacity maintenance ratio (%)” was calculated by (discharge capacity after 200 cycles) / (discharge capacity after 5 cycles) × 100 (unit:%).

The results are shown in Table 1.

(Example 2)
A secondary battery was prepared and evaluated in the same manner as in Example 1 except that the compound (301) was used instead of the compound (201) as the acid anhydride. The results are shown in Table 1.

Example 3
A secondary battery was prepared and evaluated in the same manner as in Example 1 except that the compound (202) was used instead of the compound (201) as the acid anhydride. The results are shown in Table 1.

Example 4
As a chain disulfone compound, Compound No. In place of Compound No. 1 A secondary battery was prepared and evaluated in the same manner as in Example 1 except that 2. The results are shown in Table 1.

(Comparative Example 1)
A secondary battery was prepared and evaluated in the same manner as in Example 1 except that the acid anhydride was not used. The results are shown in Table 1.

(Comparative Example 2)
A secondary battery was prepared and evaluated in the same manner as in Example 1 except that the chain disulfone compound and the acid anhydride were not used. The results are shown in Table 1.

This application claims priority based on Japanese Patent Application No. 2013-190747 filed on September 13, 2013, the entire disclosure of which is incorporated herein.

As mentioned above, although this invention was demonstrated with reference to embodiment and an Example, this invention is not limited to the said embodiment and Example. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

The secondary battery according to the embodiment of the present invention includes, for example, an electric vehicle, a plug-in hybrid vehicle, a driving device such as an electric motorcycle and an electric assist bicycle, tools such as an electric tool, an electronic device such as a portable terminal and a laptop computer, The present invention can be applied to storage batteries for household power storage systems and solar power generation systems.

DESCRIPTION OF SYMBOLS 1 Positive electrode active material layer 2 Negative electrode active material layer 3 Positive electrode collector 4 Negative electrode collector 5 Separator 6 Laminate exterior 7 Laminate exterior 8 Negative electrode tab 9 Positive electrode tab

Claims

An electrolytic solution comprising a supporting salt, a nonaqueous solvent that dissolves the supporting salt, a chain disulfone compound represented by the following formula (1), and an acid anhydride;

(In the formula (1), n is an integer of 1, 2 or 3. R 1 and R 2 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or An unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, —SO 2 X 1 (X 1 Is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), -SY 1 (Y 1 is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), -COZ (Z is A hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), or a halogen atom, R 3 and R 4 each independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. Group, substituted or unsubstituted carbon number An alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted phenoxy group, a hydroxy group, a halogen atom, —NX 2 X 3 (X 2 and X 3 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), or —NY 2 CONY 3 Y 4 (Y 2 to Y 4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms).
The electrolytic solution according to claim 1, wherein n is 1 in the formula (1).
In the formula (1), R 1 and R 2 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms. Each of R 3 and R 4 independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted carbon group having 1 to 5 carbon atoms; The electrolytic solution according to claim 1 or 2, which is a 5 fluoroalkyl group, a substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, or a substituted or unsubstituted phenoxy group.
The electrolytic solution according to any one of claims 1 to 3, wherein the acid anhydride is a carboxylic acid anhydride.
The electrolytic solution according to claim 4, wherein the carboxylic acid anhydride is a cyclic carboxylic acid anhydride represented by the following formula (I):

(In formula (I), R 11 represents a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms, a substituted or unsubstituted carbon group having 5 to 12 carbon atoms, and A cycloalkanediyl group, a substituted or unsubstituted benzenediyl group, or a divalent group having 2 to 6 carbon atoms to which an alkylene group is bonded via an ether bond).
6. The electrolytic solution according to claim 5, wherein in the formula (I), R 11 is a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms or a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms.
The electrolytic solution according to claim 4, wherein the carboxylic acid anhydride is a chain carboxylic acid anhydride represented by the following formula (III):

(In Formula (III), R 101 and R 102 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a substituted or unsubstituted group, A heterocyclic group having 4 to 12 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms.
The electrolytic solution according to any one of claims 1 to 3, wherein the acid anhydride is a sulfonic acid anhydride.
The electrolytic solution according to any one of claims 1 to 3, wherein the acid anhydride is an anhydride of carboxylic acid and sulfonic acid.
10. The electrolytic solution according to claim 1, wherein the content of the chain disulfone compound in the electrolytic solution is 0.005 to 10% by mass.
11. The electrolytic solution according to claim 1, wherein the content of the acid anhydride in the electrolytic solution is 0.005 to 10% by mass.
The molar ratio B / A between the concentration A of the chain disulfone compound in the electrolyte and the concentration B of the acid anhydride in the electrolyte is in the range of 1/10 to 5/1. The electrolyte solution in any one.
In the formula (1), n is 1,
The electrolytic solution according to claim 1, wherein the acid anhydride is a carboxylic acid anhydride.
In the formula (1), R 1 and R 2 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms. Each of R 3 and R 4 independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted carbon group having 1 to 5 carbon atoms; The electrolytic solution according to claim 13, which is a 5 fluoroalkyl group, a substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, or a substituted or unsubstituted phenoxy group.
The electrolytic solution according to claim 13 or 14, wherein the carboxylic acid anhydride is a cyclic carboxylic acid anhydride represented by the following formula (I).

(In formula (I), R 11 represents a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms, a substituted or unsubstituted carbon group having 5 to 12 carbon atoms, and A cycloalkanediyl group, a substituted or unsubstituted benzenediyl group, or a divalent group having 2 to 6 carbon atoms to which an alkylene group is bonded via an ether bond).
16. The electrolytic solution according to claim 15, wherein in the formula (I), R 11 is a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms or a substituted or unsubstituted alkenylene group having 2 to 5 carbon atoms.
The content of the chain disulfone compound in the electrolytic solution is 0.005 to 10% by mass,
The electrolytic solution according to claim 16, wherein the content of the acid anhydride in the electrolytic solution is 0.005 to 10% by mass.
The electrolysis according to claim 17, wherein the molar ratio B / A of the concentration A of the chain disulfone compound in the electrolytic solution and the concentration B of the acid anhydride in the electrolytic solution is in the range of 1/10 to 5/1. liquid.
The electrolytic solution according to claim 13 or 14, wherein the carboxylic acid anhydride is a chain carboxylic acid anhydride represented by the following formula (III).

(In Formula (III), R 101 and R 102 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a substituted or unsubstituted group, A heterocyclic group having 4 to 12 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms.
A secondary battery comprising the electrolytic solution according to any one of claims 1 to 19.