TW201609957A - Electrolyte composition, secondary battery, and method for using secondary battery - Google Patents

Abstract

The present invention pertains to an electrolyte composition containing an (A) component, a (B) component, and a (C) component, a secondary battery obtained using the electrolyte composition, and a method for using the secondary battery, wherein the (A) component is (A-1) a specific polymer compound or (A-2) a specific organic solvent, the (B) component is a salt of a group 1 or group 2 metal from the periodic table, and the (C) component is a zwitterionic compound represented by formula (I). (In the formula, X+ represents a cationic group having one atomic bond, and containing one or more nitrogen atoms or phosphorus atoms, while Y represents a C2-5 alkylene group for bonding to the nitrogen or phosphorus atoms of the X+).

Description

Electrolyte composition, secondary battery, and method of using secondary battery

The present invention relates to an electrolyte composition having ion conductivity and having excellent electrochemical stability, a secondary battery having excellent cycle characteristics and high capacity, and a method of using the secondary battery.

In recent years, secondary batteries such as lithium ion batteries have been required to achieve an increase in energy density, weight reduction, and miniaturization. Therefore, a secondary battery having a higher energy density is researched and developed using a positive electrode active material having a high operating potential.

For example, Patent Document 1 describes a positive electrode active material for a secondary battery containing two specific oxides, which contributes to improvement in cycle characteristics of a secondary battery of 5 V class and reliability of high-temperature operation.

However, in the secondary battery using the positive electrode active material having a high operating potential, the conductive polymer constituting the electrolyte is decomposed at a high voltage, and there is a possibility that the battery performance is lowered or cracking or igniting occurs.

Therefore, an electrolyte composition having ion conductivity and excellent electrochemical stability (in the present invention, a property which is not easily oxidatively decomposed even at a high potential) is required.

Further, in the case of the conventional secondary battery, when the upper limit of the cutoff voltage at the time of charging is increased and the charge and discharge are repeated, the discharge capacity is gradually lowered. because Therefore, in order to reduce the discharge capacity even if the charge and discharge are repeated, the upper limit of the cutoff voltage at the time of charging must be lowered, and a battery having a high capacity cannot be used.

Patent Documents 2 and 3 related to the present invention describe a proton conductor composed of a zwitterionic salt and a proton donor, and a fuel cell having a proton conducting layer composed of the proton conductor.

Prior technical literature

Patent literature

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-138787

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2005-228588 (US2006/0263661A1)

[Patent Document 3] Japanese Patent Publication No. WO2006/025482 (US2007/0231647 A1)

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrolyte composition having ion conductivity and excellent electrochemical stability, and having excellent cycle characteristics (meaning that discharge capacity is not easy even if charge and discharge are repeated) A secondary battery having a low capacity and a high capacity, and a method of using the secondary battery.

In order to solve the above problems, the inventors of the present invention have found that an electrolyte composition having ion conductivity and excellent electrochemical stability has been completed, and the electrolyte composition contains: (A) a specific polymer compound or an organic solvent; (B) a metal salt of Group IA or Group IIA of the periodic table; and a cationic group having a nitrogen atom or a phosphorus atom in the molecule, and a sulfonate anion (C) Zwitterionic compounds.

As described above, according to the present invention, it is possible to provide the electrolyte compositions of the following (1) to (6), the secondary battery of (7), and the method of using the secondary battery of (8).

(1) An electrolyte composition comprising the following components (A), (B), and (C), and (A) component: (A-1) is selected from the group consisting of polyalkylene oxides, polyalkylene carbonates, And at least one polymer compound having a group consisting of a vinyl polymer derived from a repeating unit of an alkylene polyol (meth) acrylate, or (A-2) selected from the group consisting of a carbonate solvent and an ester system At least one organic solvent selected from the group consisting of a solvent, a lactone solvent, an ether solvent, a nitrile solvent, and a sulfur-containing solvent

(B) Ingredients: Metal salts of Group IA or Group IIA of the Periodic Table

(C) component: a zwitterionic compound represented by the following formula (I)

[Chemical] l ⁺ -Y-SO ₃ ^- (I)

(wherein X ⁺ represents a cationic group having 1 or 2 or more nitrogen atoms or phosphorus atoms and having 1 bond, and Y represents a carbon number of 2 to 5 bonded to a nitrogen atom or a phosphorus atom of X ⁺ alkyl).

(2) The electrolyte composition according to (1), wherein the component (A) is at least one selected from the group consisting of polyethylene oxide, ethyl carbonate, and diethyl carbonate.

(3) The electrolyte composition according to (1), wherein the component (B) is a lithium salt.

(4) The electrolyte composition according to (1), wherein the cationic group represented by X ^{+ of the} component (C) is a group represented by any one of the following formulas (II) to (VI).

(wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, and a carbon number with or without an ether bond; 2 to 10 alkenyl groups, or substituted or unsubstituted aryl groups having 6 to 20 carbon atoms. R ² and R ³ each independently represent a hydrogen atom, and have a carbon number of 1 to 10 with or without an ether bond. An alkyl group, a cyano group having 2 to 11 carbon atoms with or without an ether bond, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or a substituted or unsubstituted carbon having 6 to 20 carbon atoms The R ² and R ³ groups may be bonded to each other to form a ring. * is a bond.

(wherein R ⁴ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, or a carbon having or without an ether bond; The number of alkenyl groups is 2 to 10, and R ⁵ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. * is a bond.

(wherein R ⁶ to R ¹⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms with or without an ether bond. * indicates a bond).

(wherein R ¹¹ to R ¹⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. * indicates a bond).

(wherein R ¹⁶ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, and a carbon number with or without an ether bond; 2 to 10 alkenyl groups, or substituted or unsubstituted aryl groups having 6 to 20 carbon atoms. R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom, an alkane having 1 to 10 carbon atoms with or without an ether bond. a cyano group having 2 to 11 carbon atoms with or without an ether bond, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or an substituted or unsubstituted aryl group having 6 to 20 carbon atoms * is the dangling key)

(5) The electrolyte composition according to (1), wherein the content ratio of the component (A) to the component (B) is 100:0.1 by mass ratio of [(A) component: (B) component]. ~100:10,000.

(6) The electrolyte composition according to (1), wherein the content ratio of the component (A) to the component (C) is 100: 0.01 by mass ratio of [(A) component: (C) component]. ~100:100.

(7) A secondary battery comprising a positive electrode, a negative electrode, and the electrolyte composition according to (1).

(8) A method of using a secondary battery according to the above (7), wherein an upper limit of the cutoff voltage during charging is 4.4 to 5.5 V.

According to the present invention, it is possible to provide an electrolyte composition having ion conductivity and excellent electrochemical stability, a secondary battery having excellent cycle characteristics and high capacity, and a method of using the secondary battery.

Fig. 1 is a graph (high potential side) obtained by performing linear sweep voltammetry on the electrolyte composition (1) of Example 1 and the electrolyte composition (11) of Comparative Example 1.

Fig. 2 is a view showing the electricity of the electrolyte composition (1) of Example 1 and Comparative Example 1. The decomposing composition (11) was subjected to linear sweep voltammetry to obtain a graph (low potential side).

Fig. 3 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (2) of Example 2.

Fig. 4 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (3) of Example 3.

Fig. 5 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (4) of Example 4.

Fig. 6 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (5) of Example 5.

Fig. 7 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (6) of Example 6.

Fig. 8 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (7) of Example 7.

Fig. 9 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (8) of Example 8.

Fig. 10 is a graph obtained by performing linear sweep voltammetry on the electrolyte composition (9) of Example 9.

Fig. 11 is a graph (high potential side) obtained by performing linear sweep voltammetry on the electrolyte composition (10) of Example 10 and the electrolyte composition (12) of Comparative Example 2.

Fig. 12 is a graph (low potential side) obtained by performing linear sweep voltammetry on the electrolyte composition (10) of Example 10 and the electrolyte composition (12) of Comparative Example 2.

Fig. 13 is a graph showing the results of the constant current charge and discharge test 1 performed using the electrolyte composition (14) of Example 12 and the electrolyte composition (12) of Comparative Example 2, respectively.

Fig. 14 is a graph showing the constant current charge and discharge test 2 using the electrolyte compositions (11), (4), (5) and the electrolyte composition (11) of Comparative Examples 1 of Examples 2, 4 and 5, respectively. The chart of the results.

Fig. 15 is a graph showing the results of constant current charge and discharge test 2 performed using the electrolyte compositions (8) and (13) of Examples 8 and 11, and the electrolyte composition (11) of Comparative Example 1, respectively.

Fig. 16 is a graph showing the results of constant current charge and discharge test 3 performed using the electrolyte composition (14) of Example 12 and the electrolyte composition (12) of Comparative Example 2, respectively.

Form for implementing the invention

Hereinafter, the present invention will be described in detail with reference to 1) an electrolyte composition, 2) a secondary battery, and a method of using the same.

1) Electrolyte composition

The electrolyte composition of the present invention contains the following components (A), (B) and (C).

(A) component: (A-1) is selected from the group consisting of a polyalkylene oxide, a polyalkylene carbonate, and a vinyl polymer having a repeating unit derived from an alkylene polyol (meth) acrylate. At least one polymer compound or (A-2) selected from the group consisting of a carbonate solvent, an ester solvent, a lactone solvent, and an ether At least one organic solvent selected from the group consisting of a solvent, a nitrile solvent, and a sulfur-containing solvent

(B) Ingredients: Group IA or Group IIA metal salts of the periodic table

(C) component: a zwitterionic compound represented by the following formula (I)

[(A) ingredient]

The component (A) constituting the electrolyte composition of the present invention is selected from the group consisting of (A-1) polyalkylene oxide, polyalkylene carbonate, and having a repeat derived from a stretch alkyl polyol (meth) acrylate. At least one polymer compound of the group consisting of the ethylene polymer of the unit, or selected from the group consisting of (A-2) carbonate solvent, ester solvent, lactone solvent, ether solvent, nitrile solvent, and At least one organic solvent of the group consisting of sulfur-based solvents.

In the electrolyte composition of the present invention, the component (A) is used as an ion-conducting medium.

The polymer compound of the component (A-1) is selected from the group consisting of a polyalkylene oxide, a polyalkylene carbonate, and a vinyl polymer having a repeating unit derived from a stretch alkyl polyol (meth) acrylate. At least one of the group is formed.

The polyalkylene oxide as the component (A-1) includes a compound represented by the following formula (VII).

[7] R ^b O-(R ^a -O) _p -RC (VII)

(In the formula, R ^a represents an alkylene group having 2 to 10 carbon atoms. R ^b and R ^c each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. p is an arbitrary natural number. p is When it is 2 or more, a plurality of R ^a groups may be the same or different from each other. When the compound represented by the formula (VII) is a copolymer, it may be a block copolymer or a random copolymer).

The alkyl group of R ^{a has a} carbon number of 2 to 10, preferably 2 to 5, more preferably 2 or 3.

Examples of the alkylene group of R ^a include an ethylidene group, a triethylidene group, a propenyl group, and a tetraethylidene group.

^Examples of the alkyl group of R ^b and R ^c include a methyl group, an ethyl group, a n-propyl group, a n-butyl group, and a t-butyl group.

Examples of the compound represented by the formula (VII) include polyalkylene oxides in which both molecules of the molecule are hydrogen atoms, such as polyethylene oxide, polypropylene oxide, and ethylene oxide-propylene oxide copolymer; a polyalkylene oxide monoalkyl ether such as ethane monomethyl ether, polypropylene oxide monomethyl ether or a methyl ether oxide propylene oxide copolymer; polyethylene oxide dimethyl ether; A polyalkylene oxide dialkyl ether such as a polypropylene oxide or a dimethyl ether of an ethylene oxide-propylene oxide copolymer.

Among these, the compound represented by the formula (VII) is preferably a compound represented by the following formula (VIII).

[Chemical 8] HO-(EO) _q -(PO) _r -H (VIII)

(wherein EO represents an oxygen extended ethyl group (-CH ₂ CH ₂ -O-), and PO represents an oxygen extended propyl [-CH(CH ₃ )-CH ₂ -O-]. q, r system satisfies q ≧0, r≧0, and q+r≧2 integers).

Further, in the formula (VIII), the -(EO) _q -, -(PO) _r - systems each indicate the presence or absence of a repeating unit and its amount, rather than the order of presentation. Therefore, the compound represented by the formula (VIII) includes a homopolymer composed only of repeating units of EO, a homopolymer composed only of repeating units of PO, a repeating unit derived from EO, and a repeating unit of PO. A random copolymer composed of the above, and a block copolymer composed of a repeating unit of EO and a repeating unit of PO.

The polyalkylene oxide system can be synthesized by a known production method such as a polymerization reaction of an alkylene oxide using an organic aluminum catalyst. Further, the commercially available product can be directly used as the component (A-1).

The polyalkylene carbonate as the component (A-1) includes a compound represented by the following formula (IX).

[9] R ^e O-[R ^d -OC(=O)-O] _s -R ^f (IX)

(wherein R ^d represents an alkylene group having 2 to 10 carbon atoms. R ^e and R ^f each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. s is an arbitrary natural number. s is When it is 2 or more, a plurality of R ^d groups may be the same or different from each other. When two or more R ^d are contained, the compound represented by the formula (IX) may be a block copolymer or a random copolymer).

The alkyl group of R ^{d has} a carbon number of 2 to 10, preferably 2 to 5, more preferably 2 or 3.

Examples of the alkylene group of R ^d include an ethylidene group, a triethylidene group, a propenyl group, and a tetraethylidene group.

^Examples of the alkyl group of R ^e and R ^f include a methyl group, an ethyl group, a n-propyl group and the like.

The compound represented by the formula (IX) may, for example, be a polyvinyl carbonate or a polypropylene carbonate.

The polyalkylene carbonate can be synthesized, for example, by a known production method such as a method of reacting carbon dioxide with an epoxide in the presence of a zinc-based catalyst. Further, commercially available products can be directly used as the component (A-1).

The ethylene-based polymer having a repeating unit derived from an alkylene polyol (meth) acrylate as the component (A-1) is exemplified by the following formula (X)

(wherein R ^g represents a hydrogen atom or a methyl group, ^Rh represents an alkylene group having 2 to 10 carbon atoms, and R ⁱ represents an alkyl group having 1 to 10 carbon atoms. t represents an arbitrary integer. The ^Rh groups may be the same or different from each other. When two or more ^Rh is contained, the chain represented by (OR ^h ) _t may be a block copolymerized chain or a monomer represented by a random copolymer chain. Hereinafter, there is a polymer obtained by polymerization in the case of a monomer (α).

The alkyl group of R ^{h has} a carbon number of 2 to 10, preferably 2 to 5, more preferably 2 or 3.

Examples of the alkylene group of R ^h include an exoethyl group, a tri-ethyl group, a propenyl group, and a tetraethylidene group.

The alkyl group of R ⁱ may, for example, be a methyl group, an ethyl group or a n-propyl group.

Examples of the monomer (α) include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 2-methoxypropyl (meth)acrylate. 2-Ethyl propyl methacrylate, diethylene glycol monomethyl ether (meth) acrylate, diethylene glycol monoethyl ether (meth) acrylate, methoxy polyethylene glycol (methyl) Acrylate (repeating unit number is 2 to 100), ethoxypolyethylene glycol (meth) acrylate (repeating unit number is 2 to 100), and the like.

The monomer (α) can be used singly or in combination of two or more.

The ethylene-based polymer of the component (A-1) may be copolymerized with a monomer other than the monomer (α) capable of copolymerization (hereinafter, referred to as a monomer (β)). Things.

Examples of the monomer (β) include a (meth)acrylate monomer other than the monomer (α), an α-olefin monomer, and other vinyl monomers.

Examples of the (meth)acrylate monomer other than the monomer (α) include methyl (meth)acrylate, ethyl (meth)acrylate, and n-propyl (meth)acrylate. ) alkyl acrylate.

Examples of the α-olefin-based monomer include ethylene, propylene, and isobutylene.

Examples of the other vinyl monomer include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

When the ethylene-based polymer as the component (A-1) is used, the content of the repeating unit derived from the monomer (α) is preferably from 20 to 100% by mass in the total repeating unit, and is preferably from 25 to 50% by mass. good.

The ethylene-based polymer which is a component (A-1) can be produced, for example, by a known polymerization method such as a method of polymerizing a monomer using a radical polymerization initiator in the presence or absence of a solvent. Further, it is also possible to directly use a commercially available product as the component (A-1).

The mass average molecular weight of the component (A-1) is not particularly limited, but is usually 500 to 6,000,000, preferably 600 to 1,500,000, preferably 700 to 50,000, and particularly preferably 800 to 10,000.

The mass average molecular weight of the component (A-1) is a standard polystyrene conversion measured by a gel permeation chromatography (GPC) method using N,N-dimethylformamide, tetrahydrofuran or chloroform as a solvent. value.

The organic solvent of the component (A-2) is at least one selected from the group consisting of a carbonate solvent, an ester solvent, a lactone solvent, an ether solvent, a nitrile solvent, and a sulfur-containing solvent.

Examples of the carbonate-based solvent of the component (A-2) include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl ethyl carbonate, and carbonic acid. Ethyl methyl ester, ethyl carbonate, propylene carbonate, butylene carbonate, vinyl carbonate, and the like.

Examples of the ester solvent include methyl acetate, ethyl acetate, and n-propyl acetate.

Examples of the lactone-based solvent of the component (A-2) include γ-butyrolactone, valerolactone, mevalonolactone, and caprolactone.

Examples of the ether solvent include cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran; dibutyl ether, 1,2-dimethoxyethane, and 1,2-dibutoxyethane; A chain ether such as 4-dioxane.

Examples of the nitrile-based solvent include acetonitrile and propionitrile.

Examples of the sulfur-containing solvent include cyclobutyl hydrazine and dimethyl hydrazine.

The component (A) can be used alone or in combination of two or more.

Among these, as the component (A), since an electrolyte composition having excellent electrochemical stability can be obtained, it is selected from the group consisting of polyethylene oxide, ethyl carbonate, and diethyl carbonate. At least one of them is preferred.

The oxidation potential of the component (A) is preferably 3.5 V or more, and more preferably 4.0 to 6.5 V. When the oxidation potential of the component (A) is within the above range, an electrolyte composition having excellent electrochemical stability can be obtained.

In the present invention, the so-called oxidation potential means that when it is set to a high potential, it is electrified. The potential that exceeds the range of stability and the current becomes larger.

[(B) ingredients]

The component (B) constituting the electrolyte composition of the present invention is a metal salt of Group IA or Group IIA of the periodic table.

In the electrolyte composition of the present invention, the component (B) is used as an ion source.

Examples of the metal ion constituting the salt of the metal include alkali metal ions such as lithium ions, sodium ions, and potassium ions; magnesium ions; alkaline earth metal ions such as calcium ions and barium ions.

Examples of the anion constituting the metal salt include (CH ₂ FSO ₂ ) ₂ N ^- [bis(fluoromethanesulfonyl)amine anion], (CF ₃ SO ₂ ) ₂ N ^- [bis(trifluoromethanesulfonate)醯 醯 醯 醯 imine anion], (C ₂ F ₅ SO ₂ ) ₂ N ^- [bis (pentafluoroethanesulfonyl) quinone imine anion], (FSO ₂ ) ₂ N ^- [bis (fluorosulfonyl)醯imino anion], (CF ₃ SO ₂ ) ₃ C ^- [paras(trifluoromethanesulfonyl) methyl ion], trifluoromethanesulfonate ion, hexafluorophosphate ion, tetrafluoroborate ion, four Cyanoborate ion, perchloric acid ion, hexafluoroarsenate ion, and the like.

The metal salt is preferably a lithium salt, a sodium salt, a potassium salt, a magnesium salt or a calcium salt, and a lithium salt is preferred.

Examples of the lithium salt include lithium bis(fluoromethanesulfonyl) quinone imide (LiN(SO ₂ CH ₂ F) ₂ ), lithium bis(trifluoromethanesulfonyl) ruthenium hydride (LiN (SO ₂ CF) ₃ ) ₂ ), lithium bis(pentafluoroethanesulfonyl) phthalide (LiN(SO ₂ C ₂ F ₅ ) ₂ ), lithium bis(sulfonyl) ruthenium (LiN(SO ₂ F) ₂ ) , ginseng (trifluoromethanesulfonyl) methylated lithium (LiC(SO ₂ CF ₃ ) ₃ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF) ₄ ) lithium tetracyanoborate (LiB(CN) ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), and the like.

In the present invention, the metal salts of Group IA or Group IIA of the periodic table may be used alone or in combination of two or more.

In the electrolyte composition of the present invention, the content ratio of the component (A) to the component (B) is preferably 100:0.1 to 100:10,000 by mass ratio of [(A) component: (B) component]. Preferably, it is 100:1~100:1000.

When the content ratio of the component (A) to the component (B) is within the above range, it is easy to obtain an electrolyte composition having sufficient ion conductivity.

[(C) ingredient]

The component (C) constituting the electrolyte composition of the present invention is a zwitterionic compound represented by the following formula (I). The electrolyte composition of the present invention has excellent electrochemical stability by containing the component (C). In addition, the secondary battery using the electrolyte composition containing the component (C) has excellent cycle characteristics even when the upper limit of the off-voltage at the time of charging is raised to 4.4 V or more.

[Chemical 13] X ⁺ -Y-SO ₃ ^- (I)

In the formula (I), the X ⁺ system contains 1 or 2 or more nitrogen atoms or phosphorus atoms, and represents a cationic group having one bond, and Y represents a carbon number bonded to a nitrogen atom or a phosphorus atom of X ⁺ 2 5 alkyl groups.

The carbon number of the cationic group represented by X ⁺ is preferably from 1 to 40, preferably from 3 to 30, more preferably from 6 to 20, and particularly preferably from 9 to 15.

The cationic group represented by X ⁺ may be a group represented by any one of the following formulas (II) to (VI).

[Chemistry 14]

(wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, and a carbon number with or without an ether bond; 2 to 10 alkenyl groups, or substituted or unsubstituted aryl groups having 6 to 20 carbon atoms. R ² and R ³ each independently represent a hydrogen atom, an alkane having 1 to 10 carbon atoms with or without an ether bond. a cyano group having 2 to 11 carbon atoms with or without an ether bond, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or an substituted or unsubstituted aryl group having 6 to 20 carbon atoms R ² and R ³ may also be bonded to each other to form a ring. * is a bond.

(wherein R ⁴ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, or a carbon having or without an ether bond; The number of alkenyl groups is 2 to 10, and R ⁵ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. * is a dangling bond.

(wherein R ⁶ to R ¹⁰ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. * indicates a bond).

(wherein R ¹¹ to R ¹⁵ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms with or without an ether bond. * means a bond).

(wherein R ¹⁶ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, and a carbon number with or without an ether bond; 2 to 10 alkenyl groups, or substituted or unsubstituted aryl groups having 6 to 20 carbon atoms. R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom, an alkane having 1 to 10 carbon atoms with or without an ether bond. a cyano group having 2 to 11 carbon atoms with or without an ether bond, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or an substituted or unsubstituted aryl group having 6 to 20 carbon atoms * is the key to indicate).

In the formulae (II) to (VI), the carbon number of the alkyl group of the alkyl group having 1 to 10 carbon atoms of the R ¹ to R ¹⁸ having or having no ether bond is preferably 1 to 8 and 1 to 5 It is better.

Examples of the alkyl group having no ether bond include a methyl group, an ethyl group, a n-propyl group, and a positive alkyl group. Butyl and the like.

The alkyl group having an ether bond may, for example, be a group represented by the following formula.

R ¹⁹ -OZ ¹ -* R ²⁰ -OZ ² -OZ ³ -*

(wherein R ¹⁹ represents an alkyl group having 1 to 8 carbon atoms, Z ¹ represents an alkylene group having 2 to 9 carbon atoms, and the total number of carbon atoms of R ¹⁹ and Z ¹ is 3 to 10. R ²⁰ represents An alkyl group having 1 to 6 carbon atoms, a Z ² group representing an alkylene group having 2 to 7 carbon atoms, a Z ³ group representing an alkylene group having 2 to 7 carbon atoms, and a total of carbon numbers of R ²⁰ , Z ² and Z ³ It is 5~10. * indicates the key).

The carbon number of the cyanoalkyl group having 2 to 11 carbon atoms of R ¹ to R ⁴ and R ¹⁶ to R ¹⁸ having or not having an ether bond is preferably 2 to 9 and preferably 2 to 6.

Examples of the cyanoalkyl group having no ether bond include a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, and a 4-cyanobutyl group.

The cyanoalkyl group having an ether bond may, for example, be a group represented by the following formula.

R ²¹ -OZ ⁴ -* R ²² -OZ ⁵ -OZ ⁶ -*

(wherein R ²¹ represents a cyanoalkyl group having 2 to 9 carbon atoms, Z ⁴ represents an alkylene group having 2 to 9 carbon atoms, and the total number of carbon atoms of R ²¹ and Z ⁴ is 4 to 11. R ^{22 is a} system. A cyano group having a carbon number of 2 to 7, a Z ⁵ group representing an alkylene group having 2 to 7 carbon atoms, a Z ⁶ group representing an alkylene group having 2 to 7 carbon atoms, and a carbon number of R ²² , Z ⁵ and Z ⁶ The total is 6~11. * indicates the key).

The carbon number of the alkenyl group having 2 to 10 carbon atoms of R ¹ to R ⁴ and R ¹⁶ to R ¹⁸ having or not having an ether bond is preferably 2 to 9 and preferably 2 to 6.

Examples of the alkenyl group having no ether bond include a vinyl group, an allyl group, a 1-butenyl group, a 2-butenyl group, and a 1-pentenyl group.

The alkenyl group having an ether bond may, for example, be a group represented by the following formula.

[Chem. 21] R ²³ -OZ ⁷ -* R ²⁴ -OZ ⁸ -OZ ⁹ -*

(wherein R ²³ represents an alkenyl group having 2 to 8 carbon atoms, Z ⁷ represents an alkylene group having 2 to 8 carbon atoms, and the carbon number of R ²³ and Z ⁷ is 4 to 10 in total. R ²⁴ represents carbon 2 to 6 alkenyl groups, Z ⁸ represents an alkylene group having 2 to 6 carbon atoms, Z ⁹ represents an alkylene group having 2 to 6 carbon atoms, and the total carbon number of R ²⁴ , Z ⁸ and Z ⁹ is 6 ~10.* indicates the key).

The carbon number of the aryl group of R ¹ to R ³ , R ¹⁶ to R ¹⁸ or the unsubstituted aryl group having 6 to 20 carbon atoms is preferably 6 to 10.

Examples of the unsubstituted aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

Examples of the substituent of the substituted aryl group include an alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; and an alkoxy group having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group.

In addition, examples of the ring formed by bonding R ² and R ³ include a nitrogen-containing 5-membered ring such as a pyrrolidine ring, and a nitrogen-containing 6-membered ring such as a piperazine ring, a piperidine ring or a morpholine ring.

In the formula (I), Y is a C 2 to 5 alkyl group bonded to a nitrogen atom or a phosphorus atom of X ⁺ .

Examples of the alkylene group of Y include a linear alkyl group such as an ethyl group, a trimethylene group, a tetramethylene group, and a pentamethylene group; propane-1,2-diyl group and butane-1, A branched chain alkyl group having a 3-diyl group or the like.

The method for producing the zwitterionic compound as the component (C) is not particularly limited. For example, as shown in the following formula, X ⁺ is a zwitterionic compound (3) represented by the above formula (II), which can be obtained by reacting the corresponding amine compound (1) with a sultone compound (2). .

(In the above formula, R ¹ , R ² and R ^{3 have the} same meanings as described above, and n is 0, 1, 2 or 3).

Examples of the amine compound (1) include trimethylamine, triethylamine, and tri-n-butylamine.

These amine compounds can be produced and obtained by the synthesis method described in the examples. Further, as the amine compound, a commercially available product can also be used.

Examples of the sultone compound (2) include 1,2-ethane sultone, 1,3-propane sultone, 1,4-butane sultone, and 2,4-butane sulfonate. Ester, 1,5-pentane sultone.

These conventional compounds can be obtained by well-known methods. Further, as the sultone compound, a commercially available product can also be used.

In the reaction of the amine compound (1) with the sultone compound (2), the amount of the sultone compound (2) to be used is preferably 0.8 to 1.2 equivalents, more preferably 0.9 to the amine compound (1). 1.1 equivalents. By using the amount of the sultone compound (2) in the above range, the step of removing the unreacted material or shortening can be omitted. Go to the time needed.

The reaction of the amine compound (1) with the sultone compound (2) can be carried out without a solvent or in the presence of an inert solvent.

Examples of the inert solvent to be used include an ether solvent such as tetrahydrofuran or diglyme; a nitrile solvent such as acetonitrile or propionitrile; and a ketone solvent such as acetone or methyl ethyl ketone; An aromatic hydrocarbon solvent such as toluene or xylene; a halogenated hydrocarbon solvent such as chloroform;

When an inert solvent is used, the amount thereof to be used is not particularly limited, and is usually 100 parts by mass or less, based on 1 part by mass of the amine compound (1).

The reaction temperature is not particularly limited, but is usually 0 to 200 ° C, preferably 10 to 100 ° C, and more preferably 20 to 60 ° C. Further, the reaction can be carried out under normal pressure conditions, or the reaction can be carried out under pressure.

The reaction time is not particularly limited and is usually from 12 to 332 hours, preferably from 24 to 168 hours.

From the viewpoint of preventing oxidation caused by oxygen and moisture in the air from causing a decrease in yield due to hydrolysis of the sultone compound (2), the reaction is preferably carried out under an inert gas atmosphere.

The progress of the reaction can be confirmed by a usual analytical means such as gas chromatography, high-speed liquid chromatography, thin layer chromatography, NMR, or IR.

After completion of the reaction, the obtained zwitterionic compound can be purified and isolated by a known purification method such as solvent washing, recrystallization, or column chromatography.

Further, the compound represented by the following formulas (XI) to (XIV) can be used instead of the amine compound (1), and the same reaction can be carried out to produce the above formula. (III) to (VI) a zwitterionic compound having a cationic group.

In the formulae (XI) to (XIV), R ⁴ to R ¹⁸ represent the same meaning as described above.

The compound represented by the formula (XI) to (XIV) can be produced by using the synthesis method described in the examples and the like. Further, a commercially available product can also be used.

In the electrolyte composition of the present invention, the content ratio of the component (A) to the component (C) is preferably from 100:0.01 to 100:100 in terms of the mass ratio of the [(A) component: (B) component]. Preferably, it is 100: 0.1 to 100:50.

When the content ratio of the component (A) to the component (C) is within the above range, it is easy to obtain an electrolyte composition having sufficient ion conductivity and having excellent electrochemical stability. Further, the secondary battery containing the electrolyte composition has more excellent cycle characteristics.

The electrolyte composition of the present invention has excellent electrochemical stability.

The electrolyte composition of the present invention has excellent electrochemical stability because, for example, when performing linear sweep voltammetry under the conditions described in the examples, the oxidation potential of the mixture of the components (A) and (B) is compared. The oxidation potential of the electrolyte composition of the present invention becomes a high value.

The oxidation potential of the electrolyte composition of the present invention is preferably 4.3 V or more. It is better to use 4.6~6.5V.

As described above, the electrolyte composition of the present invention has ion conductivity and excellent electrochemical stability.

Therefore, the electrolyte composition of the present invention is suitably used as an electrolyte material such as a secondary battery using a positive electrode active material having a high operating potential.

2) Secondary battery and method of use thereof

The secondary battery of the present invention has a positive electrode, a negative electrode, and an electrolyte composition of the present invention.

The positive electrode system usually includes a positive electrode current collector and a positive electrode active material layer.

The current collecting system maintains the active material layer and simultaneously serves as an electron exchange with the active material.

The material constituting the positive electrode current collector is not particularly limited. For example, a metal material such as aluminum, nickel, iron, stainless steel, titanium, or copper, and a conductive polymer can be given.

The positive electrode active material layer is a layer formed on the surface of the positive electrode current collector, and here, the positive electrode active material is contained. Examples of the positive electrode active material include inorganic activities such as LiMn ₂ O ₄ , LiCoO ₂ , LiNiO ₂ , Li(Ni-Mn-Co)O _{2 ,} and some of these transition metals are substituted with other elements. substance.

The positive electrode active material layer may contain an additive in addition to the positive electrode active material.

Examples of such an additive include a binder such as polyvinylidene fluoride, a synthetic rubber binder, and an epoxy resin; a conductive auxiliary agent such as carbon black, graphite, or vapor-grown carbon fiber; and (B) of the present invention. An electrolyte salt such as a component; an ion conductive polymer such as a polyethylene oxide (PEO) polymer or a polypropylene oxide (PPO) polymer.

The negative electrode system usually contains a negative electrode current collector and a negative electrode active material layer. Further, the negative electrode may be composed only of the negative electrode active material layer (that is, the negative electrode active material layer also serves as a negative electrode current collector).

The material constituting the negative electrode current collector is the same as that disclosed as the material of the positive electrode current collector.

The negative electrode active material layer is a layer formed on the surface of the negative electrode current collector, and contains a negative electrode active material here. Examples of the negative electrode active material include carbon materials such as graphite, soft carbon, and hard carbon; lithium-transition metal composite oxides such as Li ₄ Ti ₅ O ₁₂ ; and antimony materials such as antimony monomers, antimony oxides, and antimony alloys. Lithium metal; lithium-metal alloy such as lithium-tin or lithium-rhenium alloy; monomer, alloy, compound such as tin material; or a composite material obtained by using these materials in combination.

The negative electrode active material layer may contain an additive in addition to the negative electrode active material. As such an additive, the same thing as the additive in the positive electrode active material layer is mentioned.

In the secondary battery of the present invention, the electrolyte composition of the present invention exists between the positive electrode and the negative electrode to serve as ion conduction.

The secondary battery of the present invention may have a separator between the positive electrode and the negative electrode. The separator has a function of electrically insulating the positive electrode from the negative electrode and preventing short-circuiting, and only allows ions to move. Examples of the material constituting the separator include a porous body formed of an insulating plastic such as polyethylene, polypropylene, or polyimide, and inorganic fine particles such as cerium oxide gel.

The method for producing the secondary battery of the present invention is not particularly limited, and can be produced in accordance with a known method.

Because the secondary battery of the present invention contains a zwitterionic compound [(C) Since the component is added, even if the charge/discharge is repeated and the upper limit of the cutoff voltage at the time of charging is increased, the discharge capacity is less likely to occur.

When the secondary battery of the present invention is used, it is preferable to use the upper limit of the cutoff voltage at the time of charging to be between 4.4 and 5.5 V.

As described above, the secondary battery of the present invention has excellent cycle characteristics even when the upper limit of the cutoff voltage at the time of charging is increased, and is a secondary battery having a higher capacity.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited at all by the following examples.

The parts and % in each case are the quality basis as long as they are not notified in advance.

[Manufacturing Example 1] Production of zwitterionic compound (1)

To the pressure vessel, 6.13 g (83.8 mmol) of diethylamine and 5.0 g (42.5 mmol) of 5-chlorovaleronitrile were added, and the whole contents were heated and reacted at 140 ° C for 48 hours.

After completion of the reaction, the reaction liquid was distilled under reduced pressure to give a crude product. Next, by using an alumina column chromatography [developing solvent: ethyl acetate / n-hexane mixed solvent (1/1, vol / vol)], 4-cyanobutyldiethylamine was obtained. . (Yield: 2.57 g, yield: 39.4%)

Next, in a three-necked flask equipped with a dropping funnel, 2.57 g (16.7 mmol) of 4-cyanobutyldiethylamine and 10 ml of acetone were added, and while stirring the contents, the 1,3-propane sulfone was slowly added at 25 °C. The ester was 2.04 g (16.7 mmol), and after the addition was completed, the whole was stirred at the same temperature for 96 hours.

After completion of the reaction, the precipitated white solid was obtained by filtration, and washed with acetone and dried to obtain a zwitterionic compound (1) represented by the following formula. Production Amount: 3.97g, yield: 86.1%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (1) are shown below.

_{^{1 H-NMR (CDCl 3,}} 500MHz): δ (ppm) = 1.87 (m, 2H), 2.46-2.49 (t, J = 0.15Hz, 2H), 3.02 (s, 9H), 3.43 (m, 6H) , 3.50 (m, 6H)

Anal Calc. for C ₁₂ H ₂₄ N ₂ O ₃ S, %: C, 52.15; H, 8.75; N, 10.14; S, 11.60; Found, %: C, 52.28; H, 8.64; N, 10.08; 11.62

[Production Example 2] Production of zwitterionic compound (2)

10 g (53.9 mol) of tributylamine and 10 ml of acetone were added to a two-necked flask equipped with a dropping funnel, and while stirring the contents, 1,3-propane sultone 6.59 g was slowly added at 25 ° C ( 54.0 mmol) After completion of the addition, the whole contents were stirred at 40 ° C for 168 hours.

After completion of the reaction, the precipitated white solid was obtained by filtration, and washed with acetone and dried to obtain a zwitterionic compound (2) represented by the following formula. (Yield: 9.11 g, yield: 54.9%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (2) are shown below.

¹ H-NMR (D ₂ O, 500 MHz): δ (ppm) = 0.90-0.93 (t, J = 7.4 Hz, 9H), 1.30-1.37 (sext, J = 7.4 Hz, 6H) 1.60-1.67 (m, 6H)2.07-2.14(m,2H),2.91-2.93 (t,J=7.1Hz,2H), 3.19-3.22(m,6H),3.34-3.37(m,2H)

Anal Calc. for C ₁₅ H ₃₃ NO ₃ S, %: C, 58.57; H, 10.82; N, 4.56; S, 10.43; Found, %: C, 58.79; H, 10.30; N, 4.50; S, 10.61

[Manufacturing Example 3] Production of zwitterionic compound (3)

In a pressure-resistant container, 19.4 g (148 mmol) of dibutylamine and 7.0 g (74.0 mmol) of 2-chloroethyl methyl ether were added, and the whole contents were heated and reacted at 140 ° C for 48 hours.

After completion of the reaction, the reaction liquid was distilled under reduced pressure to give a crude product. Next, it was purified by using alumina column chromatography [developing solvent: ethyl acetate / n-hexane mixed solvent (1/1, vol / vol)] to obtain dibutyl (2-methoxy group). Ethyl)amine. (yield: 4.0 g, yield: 26.6%)

Next, in a three-necked flask equipped with a dropping funnel, 4.0 g (21.7 mmol) of dibutyl(2-methoxyethyl)amine and 10 ml of acetone were added, and while stirring the contents, 3.4 g of 3.4 g was slowly added at 25 ° C ( 27.8 mmol), after the addition was completed, the whole contents were stirred at the same temperature for 96 hours.

After the completion of the reaction, the volatile component was distilled off under reduced pressure from the reaction mixture, and the residue was purified using an alumina column chromatography [developing solvent: chloroform/methanol mixed solvent (50/1, vol/vol)]. The zwitterionic compound (3) represented by the following formula is obtained. (yield: 3.58, yield: 53.7%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (3) are shown below.

¹ H-NMR (D ₂ O, 500 MHz): δ (ppm) = 0.97-1.00 (t, J = 7.3 Hz, 6H), 1.36-1.43 (sext, J = 7.3 Hz, 4H), 1.69-1.72 (m) , 4H) 2.18 (m, 2H) 2.86 (t, J = 6.2 Hz, 2H) 3.28-3.31 (t, J = 7.6 Hz, 4H), 3.37 (s, 3H), 3.65-3.66 (m, 2H), 3.69-3.72 (m, 2H), 3.84 (m, 2H)

Anal Calc. for C ₁₄ H ₃₃ NO ₄ S, %: C, 54.34; H, 10.10; N, 4.53; S, 10.36; Found, %: C, 54.72; H, 9.63; N, 4.60; S, 10.54

[Production Example 4] Production of zwitterionic compound (4)

In a two-necked flask equipped with a dropping funnel, 6.0 g (29.7 mol) of tributylphosphine and 10 ml of chloroform were added in a nitrogen atmosphere, and 1,3-propane sultone 3.6 g was gradually added at 25 ° C while stirring the contents. (29.7 mmol), after completion of the addition, the whole contents were stirred at 40 ° C for 168 hours.

After completion of the reaction, the volatile component was distilled off under reduced pressure from the reaction mixture, and the residue was washed with ethyl acetate and dried to give the zwitterionic compound (4). (Yield: 9.11 g, yield: 54.9%)

[化27]

The ¹ H-NMR spectrum data of the zwitterionic compound (4) is shown below.

¹ H-NMR (CDCl ₃ , 500 MHz): δ (ppm) = 0.96-0.98 (t, J = 7.1, 9H), 1.5 (m, 12H), 2.04-2.12 (sext, J = 8.6 Hz, 2H), 2.23 (m, 6H), 2.66 (m, 6H), 2.91-2.93 (t, J = 6.6 Hz, 2H)

[Production Example 5] Production of zwitterionic compound (5)

In a two-necked flask equipped with a dropping funnel, 10 g of 1-butylimidazole (80.5 mmol) and 15 ml of chloroform were added, and the contents were stirred while gradually adding 1,3-propane sultone at 9.degree. g (80.5 mmol), after completion of the addition, the whole contents were stirred at 25 ° C for 48 hours.

After completion of the reaction, the chloroform layer was removed by decantation, and acetonitrile and acetone were added to the residue in this order, and the crystals were precipitated by standing. The obtained crystal was obtained by filtration, and the zwitterionic compound (5) represented by the following formula was obtained as a colorless plate crystal. (yield 17.9g, yield 90.1%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (5) are shown below.

¹ H-NMR (CD ₃ OD, 500 MHz): δ (ppm) = 1.34-1.42 (quin, J = 7.5 Hz, 2H), 1.85-1.91 (quin, J = 7.5 Hz, 2H), 2.30-2.36 (quin , J=7.1Hz, 2H), 2.79-2.82 (t, J=7.1Hz, 2H), 4.22-4.25 (t, J=7.4Hz, 2H), 4.42-4.44 (t, J=7.1Hz, 2H) , 7.65-7.66 (t, J = 1.8 Hz, 1H), 6.9-7.70 (t, J = 1.8 Hz, 1H), 9.03 (s, 1H)

Anal Calc. for C ₁₀ H ₁₈ N ₂ O ₃ S, %: C, 48.76; H, 7.37; N, 11.37; S, 13.02; Found, %: C, 48.7; H, 7.29; N, 11.36; 13.06

[Production Example 6] Production of zwitterionic compound (6)

In a two-necked flask equipped with a cooling tube, 4.68 g (88.2 mmol) of acrylonitrile, 5.00 g (73.4 mmol) of imidazole, and 5 ml of methanol were added, and the whole contents were stirred at 55 ° C for 4 hours.

After the completion of the reaction, the volatile component was distilled off from the reaction mixture under reduced pressure, and the residue obtained was purified using an alumina column chromatography [developing solvent: chloroform/methanol mixed solvent (50/1, vol/vol)]. 2-cyanoethylimidazole was obtained as a colorless, transparent liquid. (yield 8.43g, yield 94.6%)

In Production Example 1, a zwitterionic compound (6) represented by the following formula was obtained in the same manner as in Production Example 1 except that 2-cyanoethylimidazole was used instead of 4-cyanobutyldiethylamine. (yield 16.0 g, yield 89.9%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (6) are shown below.

¹ H-NMR (D ₂ O, 500 MHz): δ (ppm) = 2.33 - 2.39 (quin, J = 7.2 Hz, 2H), 2.93 - 2.96 (quin, J = 7.2 Hz, 2H), 3.17 - 3.20 (tJ = 6.3 Hz, 2H), 4.42-4.44 (t, J = 7.1 Hz, 2H), 4.59 - 4.62 (t, J = 6.3 Hz, 2H), 7.65 (m, 2H)

Anal Calc. for C ₉ H ₁₃ N ₃ O ₃ S, %: C, 44.43; H, 5.39; N, 17.27; S, 13.18; Found, %: C, 43.97; H, 5.55; N, 17.09; 13.28

[Production Example 7] Production of zwitterionic compound (7)

In a three-necked flask equipped with a dropping funnel, 2.82 g of sodium hydride was added under a nitrogen atmosphere, and 40 ml of tetrahydrofuran was dried, and the contents were stirred to obtain sodium hydride. Next, 4.00 g (58.8 mmol) of imidazole was added and stirred at room temperature for 1 hour. Subsequently, 9.8 g (60.6 mmol) of 5-bromopentanenitrile was slowly added while stirring the contents, and second, the temperature in the system was raised and the entire contents were heated under reflux for 48 hours.

After the reaction was completed, tetrahydrofuran was distilled off from the reaction liquid using a rotary evaporator. After the residue was suspended in chloroform and the insolubles were separated by filtration, the filtrate was washed with purified water and dried over anhydrous magnesium sulfate. The chloroform was distilled off from the filtrate using a rotary evaporator, and the residue was purified by colorless chromatography using an alumina column chromatography [developing solvent: chloroform/methanol mixed solvent (50/1, vol/vol)]. In a liquid manner, 6.25 g of 1-(4-cyanobutyl)imidazole was obtained (yield 59.6%).

In a two-necked flask equipped with a dropping funnel, the obtained 1-(4-cyanobutyl)imidazole (29.4 mmol) and chloroform (15 ml) were added, and the contents were slowly added at 25 ° C while stirring. 3.59 g (29.4 mmol) of 3-propane sultone was further stirred at 25 ° C for 48 hours.

After the reaction is completed, the chloroform layer is removed by decantation, and acetonitrile and acetone are used. The residue was added to the residue in this order, and the crystals were precipitated by standing. The obtained crystal was obtained by filtration, and the zwitterionic compound (7) represented by the following formula was obtained as a colorless plate crystal. (yield 11.2g, yield 89.6%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (7) are shown below.

¹ H-NMR (D ₂ O, 500 MHz): δ (ppm) = 1.64-1.68 (quin, J = 7.5 Hz, 2H), 1.93-1.99 (quin, J = 7.4 Hz, 2H), 2.36-2.39 (t , J=7.0Hz, 2H), 4.00-4.03 (t, J=6.9Hz, 2H), 6.92-6.93 (t, J=1.2Hz, 1H), 7.07-7.08 (t, J=1.0Hz, 1H) , 7.47(s,1H)

Anal Calc. for C ₁₁ H ₁₇ N ₃ O ₃ S, %: C, 48.69; H, 6.32; N, 15.49; S, 11.82; Found, %: C, 48.41; H, 6.19; N, 15.38; 11.97

[Production Example 8] Production of zwitterionic compound (8)

In Production Example 7, a zwitterionic compound (8) represented by the following formula was obtained in the same manner as in Production Example 7 except that 7-bromoheptonitrile was used instead of 5-bromopentanenitrile. (yield 5.52g, yield 62.7%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (8) are shown below.

¹ H-NMR (D ₂ O, 500 MHz): δ (ppm) = 1.29-1.35 (quin, J = 7.6 Hz, 2H), 1.41-1.47 (quin, J = 7.6 Hz, 2H), 1.60-1.66 (quin , J=7.3Hz, 2H), 1.86-1.92 (quin, J=7.4Hz, 2H), 2.28-2.34 (quin, J=7.3Hz, 2H), 2.43-2.46 (t, J=7.1Hz, 2H) , 2.88-2.91 (t, J = 7.4 Hz, 2H), 4.19 - 4.22 (t, J = 7.1 Hz, 2H), 4.34 - 4.37 (t, J = 7.1 Hz, 2H), 7.51 - 7.52 (t, J =1.8Hz,1H),7.53-7.54(t,J=1.8Hz,1H),8.82(s,1H)

Anal Calc. for C ₁₃ H ₂₁ N ₃ O ₃ S, %: C, 52.15; H, 7.07; N, 14.64; S, 10.71; Found, %: C, 51.91; H, 7.48; N, 13.85; 10.62

[Manufacturing Example 9] Production of zwitterionic compound (9)

1-(2-hydroxyethyl)imidazole 5.00 g (44.6 mmol), 1,4-dioxane 5 ml, and 1.25 ml of a 25% potassium hydroxide aqueous solution in a two-necked flask equipped with a dropping funnel. The contents were stirred for 5 minutes. 2.60 g (49.1 mmol) of acrylonitrile was slowly added while stirring, and stirring was further continued at 25 ° C for 24 hours.

After completion of the reaction, 1,4-dioxane and unreacted acrylonitrile were distilled off from the reaction liquid using a rotary evaporator. The residue was suspended in chloroform, and the obtained chloroform solution was washed with purified water, and the chloroform layer was dried over anhydrous magnesium sulfate. The chloroform was distilled off from the filtrate using a rotary evaporator, and the residue was purified by colorless chromatography using an alumina column chromatography [developing solvent: chloroform/methanol mixed solvent (50/1, vol/vol)]. In a liquid manner, 3.10 g of 1-[2-(2-cyanoethoxy)ethyl]imidazole was obtained (yield 42.1%).

The obtained 2-[2-(2-cyanoethoxy)ethyl]imidazole 2.68 g (16.2 mmol) and acetone 10 ml were added to a two-necked flask equipped with a dropping funnel, and the contents were stirred. Slowly add 1,3-propane sultone at 25 ° C 1.98 g (16.2 mmol), after completion of the addition, stirring was further continued at 25 ° C for 4 days.

After completion of the reaction, the precipitate thus obtained was collected by filtration, and the obtained precipitate was washed with acetone and then recrystallized using acetonitrile. Activated carbon was added to a solution obtained by dissolving the obtained crystal in methanol, and the mixture was heated under reflux for 24 hours. After the activated carbon was separated by filtration, methanol was distilled off from the filtrate using a rotary evaporator, and a zwitterionic compound (9) represented by the following formula was obtained as a colorless crystal. (yield 13.5g, yield 77.9%)

The ¹ H-NMR spectrum data and elemental analysis results of the zwitterionic compound (9) are shown below.

¹ H-NMR (D ₂ O, 500 MHz): δ (ppm) = 2.28-2.33 (quin, J = 7.3 Hz, 2H), 2.71-2.73 (t, J = 5.9 Hz, 2H), 2.88-2.91 (t , J = 7.4 Hz, 2H), 3.71-3.74 (t, J = 5.85 Hz, 2H), 3.89 - 3.91 (t, J = 4.8 Hz, 2H), 4.34 - 4.37 (t, J = 7.1 Hz, 2H) , 4.40-4.42 (t, J = 4.8 Hz, 2H), 7.55 (s, 2H)

Anal Calc. for C ₁₁ H ₁₇ N ₃ O ₄ S, %: C, 45.98; H, 5.96; N, 14.62; S, 11.16; Found, %: C, 46.04; H, 5.95; N, 14.65; 11.23

[Example 1]

1500 mg of polyethylene oxide (manufactured by ALDRICH Co., Ltd., mass average molecular weight: 1,000), lithium bis(trifluoromethanesulfonyl) phthalimide (manufactured by Kanto Chemical Co., Ltd.), 1170 mg, and zwitterionic compound obtained in Production Example 1. (1) 60 mg was added to 3 ml of dehydrated acetonitrile, and the whole contents were stirred for 24 hours. Subsequently, The acetonitrile was distilled off under reduced pressure, and the obtained residue was dried under vacuum at 70 ° C for 48 hours to obtain an electrolyte composition (1).

[Embodiment 2]

In the same manner as in Example 1, except that 66 mg of the zwitterionic compound (2) obtained in Production Example 2 was used instead of the zwitterionic compound (1), the electrolyte composition (2) was obtained.

[Example 3]

In the same manner as in Example 1, except that 65 mg of the amphoteric ionic compound (3) obtained in Production Example 3 was used instead of the zwitterionic compound (1), the electrolyte composition (3) was obtained.

[Example 4]

In the same manner as in Example 1, except that 53 mg of the amphoteric compound (4) obtained in Production Example 4 was used instead of the zwitterionic compound (1), the electrolyte composition (4) was obtained.

[Example 5]

In the same manner as in Example 1, except that 70 mg of the zwitterionic compound (5) obtained in Production Example 5 was used instead of the zwitterionic compound (1), the electrolyte composition (5) was obtained.

[Embodiment 6]

In the same manner as in Example 1, except that 52 mg of the zwitterionic compound (6) obtained in Production Example 6 was used instead of the zwitterionic compound (1), the electrolyte composition (6) was obtained.

[Embodiment 7]

In Example 1, except that 58 mg of the amphiphilic separation obtained in Production Example 7 was used. The electrolyte compound (7) was obtained in the same manner as in Example 1 except that the sub-compound (7) was used instead of the zwitterionic compound (1).

[Embodiment 8]

In the same manner as in Example 1, except that 64 mg of the zwitterionic compound (8) obtained in Production Example 8 was used instead of the zwitterionic compound (1), the electrolyte composition (8) was obtained.

[Embodiment 9]

In the same manner as in Example 1, except that 62 mg of the zwitterionic compound (9) obtained in Production Example 9 was used instead of the zwitterionic compound (1), the electrolyte composition (9) was obtained.

[Embodiment 10]

By an organic electrolyte (Kishida Chemical Co., Ltd., product name: LBG-96553, solvent: ethyl carbonate and diethyl carbonate are mixed solvents in a volume ratio of 1:1, electrolyte: LiPF ₆ , electrolyte The molar concentration of the molar concentration: 1 mol/l) was added so as to be a concentration of 2.25 mass% in the zwitterionic compound (9) obtained in Production Example 9, and the mixture was stirred for 24 hours to obtain an electrolyte composition (10).

[Comparative Example 1]

In the same manner as in Example 1, except that the zwitterionic compound (1) was not added, the electrolyte composition (11) was obtained.

[Comparative Example 2]

An organic electrolyte (manufactured by Kishida Chemical Co., Ltd., product name: LBG-96553) was used as the electrolyte composition (12).

For the electricity obtained in Examples 1 to 10 and Comparative Examples 1 and 2 The degreased compositions (1) to (12) were subjected to linear sweep voltammetry (LSV) using the following methods.

Measuring device: ALS company, product name 606C

Measuring temperature: 40 ° C

Scan potential range: 0~6V

Action pole: platinum plate

Counter electrode: lithium foil

Scanning speed: 1mV/s

(test methods)

A coin-type lithium foil was placed in a bipolar battery (manufactured by Toyo Systems Co., Ltd.), and a glass filter (GA-55 manufactured by ADVANTEC Co., Ltd.) was placed as a separator thereon. After the electrolyte compositions (1) to (12) were each sufficiently infiltrated into the glass filter, a platinum disk was placed on the separator. After the bipolar cell was sealed, the working electrode was attached to the platinum disk side, and the counter electrode and the reference electrode were mounted on the lithium foil side.

Next, the potential was scanned under the above conditions using an electrochemical measuring instrument (manufactured by ALS, 606C).

The results obtained are shown in Figures 1-12. In the first to twelfth figures, the horizontal axis represents voltage and the vertical axis represents current. Further, in the graphs of Figs. 1 to 12, the scales of the vertical axis are the same.

Figures 1 through 12 show the following situations.

Compared with the electrolyte compositions (11) and (12) of Comparative Examples 1 and 2, the electrolyte compositions (1) to (10) of Examples 1 to 10 were small and excellent in flow current even at a high potential. Electrical stability.

In particular, the electrolyte compositions (1) and (10) show that the potential of the reduction current flows is low even on the low potential side, and the electrochemically stable potential range is characterized by a wide potential window.

[Example 11]

In the same manner as in Example 1, except that 128 mg of the amphoteric compound (9) obtained in Production Example 9 was used instead of the amphoteric compound (1), the electrolyte composition (13) was obtained.

[Embodiment 12]

In Example 10, the zwitterionic compound (2) obtained in Production Example 2 was added in place of the zwitterionic compound (9) so as to have a concentration of 5 mass%, and stirred for 24 hours to obtain an electrolyte composition (14).

Using the electrolyte compositions obtained in Examples 2, 4, 5, 8, 11, 12 and Comparative Examples 1 and 2, a constant current charge and discharge test was carried out by the following method.

(Constant current charge and discharge test 1)

31.9 g of lithium cobaltate (manufactured by RARE METAL CORPORATION) and 2.25 g of acetylene black (manufactured by Electrochemical Co., Ltd., DENKABLACK) were mixed while being ground on a mortar, and secondly, a PVDF (polyvinylidene fluoride) solution was added. 27.5 g of N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.), which was prepared by KUREHA.Battery.Materials. Japan, KF Polymer #1120, solid content: 12%, was mixed. The obtained mixture was stirred with a homogenizer for 30 minutes to obtain a positive electrode active material dispersion.

The obtained positive electrode active material dispersion liquid was applied onto an aluminum foil using an applicator, and the obtained coating film was dried at 80 ° C for 1 hour. This product was pressed at 0.02 MPa/cm ² at 70 ° C for 1 hour to prepare an electrode sheet.

Next, a charge and discharge test was performed under the following conditions using a measuring apparatus (VMP-300) manufactured by Biologic Corporation.

Measuring temperature: 40 ° C

Cutoff voltage: 3.0~4.6V

Positive electrode: lithium cobaltate electrode (previous electrode sheet)

Negative electrode: lithium foil

Separator: Glass filter (made by ADVANTEC, GA-55)

Current density: 778μA/cm ²

Further, a glass filter as a separator is used to infiltrate into the electrolyte composition.

(Constant current charge and discharge test 2)

The test was carried out in the same manner as in the constant current charge and discharge test 1, except that the current density was changed to 156 μA/cm ² .

(Constant current charge and discharge test 3)

The test was carried out in the same manner as in the constant current charge and discharge test except that the electrode sheet obtained by using Li(Ni-Mn-Co)O ₂ was used as the positive electrode instead of lithium cobaltate.

The results of the constant current charge and discharge test are shown in Figures 13-16. Further, Fig. 13 is a graph showing the results of the current charge and discharge test 1, Figs. 14 and 15 are the results of the constant current charge and discharge test 2, and Fig. 16 is a graph showing the results of the current charge and discharge test 3. In the figure, the horizontal axis represents the number of charge and discharge cycles, and the vertical axis represents the discharge capacity.

The following situation is known from Fig. 13~16.

Compared with the comparative example, in the case where the charging and discharging were repeated in the examples, it was possible to suppress the decrease in the discharge capacity. Thus, the secondary electricity of the electrolyte composition of the present invention is used. In the cell, even when the upper limit of the cut-off voltage at the time of charging is increased to 4.6 V and the charge and discharge are repeated, the discharge capacity is less likely to be lowered.

Claims (8)

An electrolyte composition comprising the following components (A), (B) and (C), (A): (A-1) selected from the group consisting of polyalkylene oxides, polyalkylene carbonates, and having a source At least one polymer compound of the group consisting of the ethylene polymer of the repeating unit of the alkyl polyol (meth) acrylate, or (A-2) is selected from the group consisting of a carbonate solvent and an ester solvent. At least one organic solvent (B) component of the group consisting of an ester solvent, an ether solvent, a nitrile solvent, and a sulfur-containing solvent: a metal salt (C) component of Group IA or Group IIA of the periodic table: The zwitterionic compound [Chemical Formula 1] X ⁺ -Y-SO ₃ ^- (I) represented by the following formula (I): wherein X ⁺ represents a nitrogen atom or a phosphorus atom containing 1 or 2 or more and has 1 The cationic group of the bond, and Y represents an alkyl group having 2 to 5 carbon atoms bonded to a nitrogen atom or a phosphorus atom of X ⁺ ). The electrolyte composition according to claim 1, wherein the component (A) is at least one selected from the group consisting of polyethylene oxide, ethyl carbonate, and diethyl carbonate. The electrolyte composition according to claim 1, wherein the component (B) is a lithium salt. The electrolyte composition according to claim 1, wherein the cationic group represented by X ^{+ of the} component (C) is a group represented by any one of the following formulas (II) to (VI). (wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, and a carbon number with or without an ether bond; 2 to 10 alkenyl groups, or substituted or unsubstituted aryl groups having 6 to 20 carbon atoms, and R ² and R ³ each independently represent a hydrogen atom, a carbon number of 1 to 10 having or without an ether bond. An alkyl group, a cyano group having 2 to 11 carbon atoms with or without an ether bond, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or a substituted or unsubstituted carbon having 6 to 20 carbon atoms a group, R ² and R ³ are said to be bonded to each other to form a ring, and * is a bond; (wherein R ⁴ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, or a carbon having or without an ether bond; 2 to 20 alkenyl groups, R ⁵ represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms with or without an ether bond, and * represents a bond) (wherein R ⁶ to R ¹⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms with or without an ether bond, and * represents a bond); (wherein R ¹¹ to R ¹⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms with or without an ether bond, and * represents a bond); (wherein R ¹⁶ represents an alkyl group having 1 to 10 carbon atoms with or without an ether bond, a cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond, and a carbon number with or without an ether bond; 2 to 10 alkenyl groups, or substituted or unsubstituted aryl groups having 6 to 20 carbon atoms, and R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom, an alkane having 1 to 10 carbon atoms with or without an ether bond. a cyano group having 2 to 11 carbon atoms with or without an ether bond, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or an substituted or unsubstituted aryl group having 6 to 20 carbon atoms , * indicates the key). The electrolyte composition according to claim 1, wherein the content ratio of the component (A) to the component (B) is 100:0.1 by mass ratio of [(A) component: (B) component]. ~100:10,000. The electrolyte composition according to claim 1, wherein the content ratio of the component (A) to the component (C) is 100: 0.01 by mass ratio of [(A) component: (C) component]. ~100:100. A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte composition as described in claim 1 of the patent application. A method of using a secondary battery is the method of using the secondary battery according to claim 7, wherein the upper limit of the cutoff voltage during charging is 4.4 to 5.5V.