TW202306961A - Composition, electrolyte solution, electrochemical device, lithium ion secondary battery, module, and compound - Google Patents

Abstract

The disclosure provides a composition capable of reducing generation of gas and an increase in the resistance in an electrochemical device, for example. The composition contains a compound (1) represented by the following formula (1) wherein R ¹⁰¹to R ¹⁰³are each independently a C1-C3 alkyl group, a C2-C3 alkenyl group, or a C2-C3 alkynyl group, and each optionally contain at least one selected from the group consisting of a halogen atom and an oxygen atom; n10 is an integer of 1 to 3; and m10 is 0 or 1; and a compound (2) represented by the following formula (2) wherein R ²⁰¹to R ²⁰³are each independently a C1-C3 alkyl group, a C2-C3 alkenyl group, or a C2-C3 alkynyl group, and each optionally contain at least one selected from the group consisting of a halogen atom and an oxygen atom; n20 is an integer of 1 to 3; and m20 is 0 or 1.

Description

Composition, electrolyte solution, electrochemical device, lithium ion secondary battery, module and compound

The present invention relates to composition, electrolyte solution, electrochemical device, lithium ion secondary battery, module and compound.

Current electrical appliances exhibit a trend of weight reduction and size reduction, which leads to the development of electrochemical devices such as lithium-ion secondary batteries with high energy density. In addition, there is a need for electrochemical devices such as lithium ion secondary batteries, which have improved characteristics when applied to more fields. Improvement of battery characteristics will become increasingly important, especially when lithium-ion secondary batteries are used in automobiles.

Patent Document 1 discloses a flame retardant electrolyte solution containing a predetermined flame retardant additive. Citation List Patent Literature

Patent Document 1: CN 101867065 A

technical problem

The present invention aims to provide a composition and an electrolyte solution each capable of reducing gas generation and resistance increase in an electrochemical device, and an electrochemical device, a lithium ion secondary battery, and a module each including the electrolyte solution. The present invention also aims to provide a novel compound. solution to the problem

其中R ¹⁰¹至R ¹⁰³各自獨立地為C1-C3烷基、C2-C3烯基或C2-C3炔基，且各自視情況含有選自由鹵素原子及氧原子組成之群中之至少一者；n10為1至3之整數；且m10為0或1；以及 由下式(2)表示之化合物(2)： [化學式2]

其中R ²⁰¹至R ²⁰³各自獨立地為C1-C3烷基、C2-C3烯基或C2-C3炔基，且各自視情況含有選自由鹵素原子及氧原子組成之群中之至少一者；n20為1至3之整數；且m20為0或1。 The present invention relates to a composition comprising: Compound (1) represented by the following formula (1): [Chemical Formula 1]

Wherein R ¹⁰¹ to R ¹⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each contains at least one member selected from the group consisting of halogen atoms and oxygen atoms as appropriate; n10 is an integer of 1 to 3; and m10 is 0 or 1; and a compound (2) represented by the following formula (2): [Chemical formula 2]

Wherein R ²⁰¹ to R ²⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each optionally contains at least one member selected from the group consisting of halogen atoms and oxygen atoms; n20 is an integer from 1 to 3; and m20 is 0 or 1.

In formula (1), preferably, R ¹⁰¹ to R ¹⁰³ are independently methyl groups, and m10 and n10 are independently 1.

In formula (2), preferably, R ²⁰¹ to R ²⁰³ are independently methyl groups, and m20 and n20 are independently 1.

The amount of compound (2) is preferably 0.1 to 20% by mass relative to the mass of compound (1).

The composition preferably acts as an additive to the electrolyte solution.

The invention also relates to an electrolyte solution containing the composition.

The amount of compound (1) is preferably 0.0001 to 10% by mass relative to the total mass of the electrolytic solution.

The invention also relates to a method of reducing gas generation from an electrolyte solution, the method comprising: contacting the electrolyte solution with a composition.

The invention also relates to an electrochemical device comprising an electrolyte solution.

The present invention also relates to a lithium ion secondary battery including an electrolyte solution.

The present invention also relates to a module comprising an electrochemical device or a lithium-ion secondary battery.

其中R ²⁰¹至R ²⁰³各自獨立地為C1-C3烷基、C2-C3烯基或C2-C3炔基，且各自視情況含有選自由鹵素原子及氧原子組成之群中之至少一者；n20為1至3之整數；且m20為0或1。 The present invention also relates to compounds represented by the following formula (2): [Chemical formula 3]

Wherein R ²⁰¹ to R ²⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each optionally contains at least one member selected from the group consisting of halogen atoms and oxygen atoms; n20 is an integer from 1 to 3; and m20 is 0 or 1.

In formula (2), preferably, R ²⁰¹ to R ²⁰³ are independently methyl groups, and m20 and n20 are independently 1.

The invention also relates to a method of reducing gas generation from an electrolyte solution, the method comprising: contacting the electrolyte solution with a chemical compound. Advantageous effect of the present invention

The present invention can provide a composition and an electrolyte solution each capable of reducing gas generation and resistance increase in an electrochemical device, and an electrochemical device, a lithium ion secondary battery, and a module each including the electrolyte solution. The present invention also provides a novel compound.

The present invention will be specifically described below.

其中R ¹⁰¹至R ¹⁰³各自獨立地為C1-C3烷基、C2-C3烯基或C2-C3炔基，且各自視情況含有選自由鹵素原子及氧原子組成之群中之至少一者；n10為1至3之整數；且m10為0或1；以及 由下式(2)表示之化合物(2)： [化學式5]

其中R ²⁰¹至R ²⁰³各自獨立地為C1-C3烷基、C2-C3烯基或C2-C3炔基，且各自視情況含有選自由鹵素原子及氧原子組成之群中之至少一者；n20為1至3之整數；且m20為0或1。 The present invention relates to a composition comprising: a compound (1) represented by the following formula (1): [Chemical formula 4]

Wherein R ¹⁰¹ to R ¹⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each contains at least one member selected from the group consisting of halogen atoms and oxygen atoms as appropriate; n10 is an integer of 1 to 3; and m10 is 0 or 1; and a compound (2) represented by the following formula (2): [Chemical formula 5]

Wherein R ²⁰¹ to R ²⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each optionally contains at least one member selected from the group consisting of halogen atoms and oxygen atoms; n20 is an integer from 1 to 3; and m20 is 0 or 1.

The composition of the present invention contains compounds (1) and (2), and therefore, when added to an electrolyte solution of an electrochemical device such as a lithium ion secondary battery, can reduce gas generation, especially during charging and discharging . This effect appears to be achieved by the presence of a film derived from the oxidative decomposition products of compound (1) and/or compound (2) on the positive electrode active material during initial charging, and from components contained in the electrolyte solution ( Gas generation such as carbonate) is thus reduced. The presence of compounds (1) and (2) in the composition of the present invention can also reduce resistance increase in electrochemical devices such as lithium ion secondary batteries.

。 Compound (1) is represented by the following formula (1): [Chemical Formula 6]

.

In formula (1), R ¹⁰¹ to R ¹⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl. The carbon number of the alkyl group is preferably 1 or 2, more preferably 1. The carbon number of the alkenyl group is preferably 2. The number of carbon atoms in the alkynyl group is preferably 2.

The alkyl group, alkenyl group or alkynyl group of R ¹⁰¹ to R ¹⁰³ may contain at least one member selected from the group consisting of a halogen atom and an oxygen atom, and may contain a halogen atom. The halogen atom is preferably any one of a fluorine atom and a chlorine atom, more preferably a fluorine atom. The alkyl, alkenyl or alkynyl groups of R ¹⁰¹ to R ¹⁰³ preferably do not contain oxygen atoms, more preferably do not contain halogen atoms and oxygen atoms.

Each of R ¹⁰¹ to R ¹⁰³ is preferably a C1-C3 alkyl group, more preferably methyl (CH ₃ ) or ethyl (CH ₃ CH ₂ ), still more preferably methyl (CH ₃ ).

In formula (1), n10 is an integer of 1 to 3, preferably 1 or 2, more preferably 1.

In formula (1), m10 is 0 or 1, preferably 1.

Compound (1) is especially preferably compound (1-1) represented by formula (1), wherein R ¹⁰¹ to R ¹⁰³ are methyl (CH ₃ ), n10 is 1, and m10 is 1.

One compound (1) may be used alone, or two or more compounds (1) may be used in combination.

。 Compound (2) is represented by the following formula (2): [Chemical formula 7]

.

In formula (2), R ²⁰¹ to R ²⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl. The carbon number of the alkyl group is preferably 1 or 2, more preferably 1. The carbon number of the alkenyl group is preferably 2. The number of carbon atoms in the alkynyl group is preferably 2.

The alkyl group, alkenyl group or alkynyl group of R ²⁰¹ to R ²⁰³ may contain at least one selected from the group consisting of a halogen atom and an oxygen atom, and may contain a halogen atom. The halogen atom is preferably any one of a fluorine atom and a chlorine atom, more preferably a fluorine atom. The alkyl, alkenyl or alkynyl groups of R ²⁰¹ to R ²⁰³ preferably do not contain oxygen atoms, more preferably do not contain halogen atoms and oxygen atoms.

Each of R ²⁰¹ to R ²⁰³ is preferably a C1-C3 alkyl group, more preferably methyl (CH ₃ ) or ethyl (CH ₃ CH ₂ ), still more preferably methyl (CH ₃ ).

In formula (2), n20 is an integer of 1 to 3, preferably 1 or 2, more preferably 1. The four n20s in formula (2) may be the same or different, and are preferably the same.

In formula (2), m20 is 0 or 1, preferably 1. The two m20 in formula (2) may be the same as or different from each other, and are preferably the same as each other.

Compound (2) is especially preferably compound (2-1) represented by formula (2), wherein R ²⁰¹ to R ²⁰³ are methyl (CH ₃ ), n20 is 1, and m20 is 1.

One compound (2) may be used alone, or two or more compounds (2) may be used in combination.

In a preferred embodiment of the composition of the present invention, compound (1) is compound (1-1) and compound (2) is compound (2-1).

In the composition of the present invention, the amount of the compound (2) is preferably 0.1 to 20% by mass relative to the mass of the compound (1). Compound (2) in an amount within the above range enables further reduction of gas generation and resistance increase in electrochemical devices. Relative to the mass of compound (1), the amount of compound (2) is more preferably 0.5% by mass or higher, more preferably 1.0% by mass or higher, especially preferably 1.3% by mass or higher, and more preferably 15% by mass % or less, more preferably 10% by mass or less, further preferably 9.0% by mass or less, especially preferably 7.0% by mass or less.

In the composition of the present invention, relative to the total mass of the composition, the sum of the amounts of compounds (1) and (2) is preferably 90% by mass or higher, more preferably 95% by mass or higher, even more preferably 99% by mass or higher. Its upper limit may be, but not limited to, 100% by mass.

The composition of the present invention can be suitably used as an additive for an electrolytic solution.

Compound (2) is a novel compound. The present invention also relates to compound (2).

Compound (2) can be produced suitably by a production method comprising combining a compound represented by Cl ₃ P(=O) _m20 (wherein m20 is defined as described above) with HO—(CH ₂ ) in the presence of an amine. The compound represented by _n20 -SiR ²⁰¹ R ²⁰² R ²⁰³ (wherein n20 and R ²⁰¹ to R ²⁰³ are defined as described above) is reacted. This production method can also provide compound (1) at the same time. The ratio of compound (2) can be adjusted by adjusting the amount of amine used. Purification or isolation can be performed by known methods, if necessary.

The present invention also relates to an electrolyte solution containing the aforementioned composition of the present invention. Electrolyte solutions can reduce gas generation in electrochemical devices, especially during charging and discharging. Electrolyte solutions can also reduce resistance increases in electrochemical devices.

In the electrolytic solution of the present invention, the amount of compound (1) is preferably 0.0001 to 10% by mass, more preferably 0.001 to 10% by mass, relative to the total mass of the electrolytic solution. Compound (1) in an amount within the above range enables further reduction of gas generation and resistance increase in electrochemical devices. Relative to the total mass of the electrolytic solution, the amount of compound (1) is still more preferably 0.01% by mass or higher, still more preferably 0.1% by mass or higher, especially preferably 0.5% by mass or higher, and more preferably 5.0% by mass. % by mass or lower, more preferably 3.0% by mass or lower, especially preferably 2.0% by mass or lower.

The amount of compound (2) is as described above for the composition of the present invention.

The invention also relates to a method of reducing gas generation from an electrolyte solution, the method comprising: contacting the electrolyte solution with a composition of the invention. The electrolytic solution to be contacted with the composition may be an electrolytic solution not containing the composition. Contacting can be mixing.

The present invention also relates to a method for reducing gas generation from an electrolyte solution, the method comprising: contacting the electrolyte solution with compound (2). The electrolytic solution to be brought into contact with the compound (2) may be an electrolytic solution not containing the compound (2). Contacting can be mixing.

The electrolyte solution of the present invention preferably contains a solvent.

The solvent preferably includes at least one selected from the group consisting of carbonates and carboxylates.

Carbonates can be cyclic or acyclic carbonates.

The cyclic carbonate can be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

Examples of non-fluorinated cyclic carbonates are non-fluorinated saturated cyclic carbonates. It is preferably a non-fluorinated saturated alkylene carbonate containing a C2-C6 alkylene group, and more preferably a non-fluorinated saturated alkylene carbonate containing a C2-C4 alkylene group.

In order to provide high permittivity and suitable viscosity, the non-fluorinated saturated cyclic carbonate preferably includes at least one selected from the group consisting of: ethyl carbonate, propylene carbonate, cis-2,3-carbonate Pentyl carbonate, cis-2,3-butyl carbonate, 2,3-pentyl carbonate, 2,3-butyl carbonate, 1,2-pentyl carbonate, 1,2-butyl carbonate and Butyl carbonate.

One non-fluorinated saturated cyclic carbonate may be used alone, or two or more thereof may be used in any combination in any ratio.

When a non-fluorinated saturated cyclic carbonate is contained, it is preferably present in an amount of 5 to 90% by volume, more preferably 10 to 60% by volume, more preferably 15 to 45% by volume relative to the volume of the solvent.

Fluorinated cyclic carbonates are cyclic carbonates containing fluorine atoms. Solvents containing fluorinated cyclic carbonates can suitably be used at high voltages. The term "high voltage" herein means a voltage of 4.2 V or higher. The upper limit of "high voltage" is preferably 4.9 V.

The fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

Fluorinated saturated cyclic carbonates are saturated cyclic carbonates containing fluorine atoms. Specific examples thereof include compounds represented by the following formula (A):

（其中X ¹至X ⁴彼此相同或不同，且各自為-H、-CH ₃、-C ₂H ₅、-F、視情況含有醚鍵之氟化烷基或視情況含有醚鍵之氟化烷氧基；選自X ¹至X ⁴中之至少一者為-F、視情況含有醚鍵之氟化烷基或視情況含有醚鍵之氟化烷氧基）。氟化烷基之實例包括-CF ₃、-CF ₂H及-CH ₂F。 [chemical formula 8]

(wherein X ¹ to X ⁴ are the same or different from each other, and each is -H, -CH ₃ , -C ₂ H ₅ , -F, a fluorinated alkyl group optionally containing an ether bond, or a fluorinated alkyl group optionally containing an ether bond Alkoxy; at least one selected from ^X1 to ^X4 is -F, a fluorinated alkyl group optionally containing an ether bond or a fluorinated alkoxy group optionally containing an ether bond). Examples of fluorinated alkyl groups include _-CF3 , _-CF2H and _-CH2F .

When applied to, for example, high-voltage lithium-ion secondary batteries, the presence of fluorinated saturated cyclic carbonate in the electrolyte solution of the present invention can improve the oxidation resistance of the electrolyte solution, resulting in stable and excellent charge and discharge characteristics. The term "ether bond" herein means a bond represented by -O-.

In order to provide good permittivity and oxidation resistance, one or both of X ¹ to X ⁴ is preferably/each is preferably -F, a fluorinated alkyl group optionally containing an ether bond, or a fluorine optionally containing an ether bond alkoxyl.

It is expected that the viscosity will decrease at low temperature, the flash point will increase, and the solubility of the electrolyte salt will be improved. ^X1 to ^X4 are each preferably -H, -F, fluorinated alkyl group (a), or fluorinated alkyl group (b) containing an ether bond or fluorinated alkoxy (c).

The fluorinated alkyl group (a) is a group obtainable by replacing at least one hydrogen atom of the alkyl group with a fluorine atom. The carbon number of the fluorinated alkyl group (a) is preferably 1-20, more preferably 1-17, still more preferably 1-7, especially preferably 1-5. An excessively large carbon number may result in poor low-temperature characteristics and low solubility of electrolyte salts. Too low carbon number can lead to, for example, low solubility of electrolyte salt, low discharge efficiency and increased viscosity.

Examples of the fluorinated alkyl group (a) having 1 carbon number include CFH ₂ -, CF ₂ H-, and CF ₃ -. In order to provide good high-temperature storage properties, CF ₂ H- or CF ₃ - is especially preferred. Best for CF ₃ -.

In order to provide good solubility of the electrolyte salt, preferred examples of the fluorinated alkyl group (a) having a carbon number of 2 or more include a fluorinated alkyl group represented by the following formula (a-1): R ^a1 -R ^a2 - ( a-1) wherein R ^a1 is an alkyl group having a carbon number of 1 or more and optionally containing a fluorine atom; R ^a2 is a C1-C3 alkylene group optionally containing a fluorine atom; and is selected from the group consisting of R ^a1 and R ^a2 At least one of the groups contains a fluorine atom. Each of R ^a1 and R ^a2 may further contain atoms other than carbon, hydrogen, and fluorine atoms.

R ^a1 is an alkyl group having a carbon number of 1 or more and optionally containing a fluorine atom. R ^a1 is preferably a C1-C16 straight chain or branched chain alkyl group. The carbon number of R ^a1 is more preferably 1-6, and still more preferably 1-3.

Specifically, for example, CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, CH ₃ CH ₂ CH ₂ CH ₂ -, and a group represented by the following formula:

[chemical formula 9]

May be mentioned as straight-chain or branched-chain alkyl for R ^a1 .

Examples of R ^a1 as a linear alkyl group containing a fluorine atom include CF ₃ -, CF ₃ CH ₂ -, CF ₃ CF ₂ -, CF ₃ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ -, CF ₃ CH ₂ CF ₂ -, CF ₃ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ -, CF ₃ CH ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ -, CF ₃ CF ₂ CH ₂ CF ₂ -, CF ₃ CH ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CH ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CF 2 CH _{2 CH 2} -, HCF ₂ -, HCF ₂ CH ₂ -, HCF ₂ CF ₂ -, HCF ₂ CH ₂ CH ₂ -, HCF ₂ CF ₂ CH ₂ -, HCF ₂ CH ₂ CF ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ -, HCF ₂ CH ₂ CF ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ CH ₂ - _, HCF ₂ CH ₂ CF ₂ CH ₂ CH ₂ -, HCF ₂ CF 2 CF ₂ CF ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ CH ₂ CH ₂ -, FCH ₂ -, FCH ₂ CH ₂ -, FCH ₂ CF ₂ -, FCH ₂ CF ₂ CH ₂ -, FCH ₂ CF ₂ CF ₂ -, CH ₃ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ -, CH ₃ CF ₂ CF ₂ CF ₂ -, CH ₃ CH ₂ CF ₂ CF ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ CH ₂ CH ₂ -, CH ₃ CH ₂ CF ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ CH ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF _{2CH2CH2- , HCFClCF2CH2- , HCF2CFClCH2- , HCF2CFClCF2CFClCH2- , and HCFClCF2CFClCF2CH2- . _ _}

Examples of R ^a1 as the branched alkyl group containing a fluorine atom include those represented by the following formulae.

， [chemical formula 10]

,

[chemical formula 11]

The presence of branches such as CH ₃ - or CF ₃ - can easily lead to high viscosity. Therefore, the number of such branches is preferably a small number (one) or zero.

R ^a2 is a C1-C3 alkylene group optionally containing a fluorine atom. R ^a2 may be a straight chain or a branched chain. Examples of the minimum structural unit constituting such linear or branched alkylene groups are shown below. R ^a2 consists of one or a combination of these units.

(i) The smallest structural unit of straight chain -CH ₂ -, -CHF-, -CF ₂ -, -CHCl-, -CFCl-, -CCl ₂ -

(ii) The smallest structural unit of the branch chain

[chemical formula 12]

Preferred among these exemplary units are Cl-free structural units because such units can be dehydrochlorinated without a base and thus can be more stable.

R ^a2 as a linear group consists only of any one of the above linear minimum structural units, and is preferably -CH ₂ -, -CH ₂ CH ₂ - or CF ₂ -. In order to further improve the solubility of the electrolyte salt, -CH ₂ - or -CH ₂ CH ₂ - is more preferable.

R ^a2 as a branched chain group includes at least one of the above branched chain minimum structural units. Its preferred example is from -(CX ^a X ^b )- (wherein X ^a is H, F, CH ₃ or CF ₃ ; X ^b is CH ₃ or CF ₃ ; when X ^b is CF ₃ , X ^a is H or CH ₃ ). Such groups can further greatly improve the solubility of electrolyte salts.

For example, _{CF3CF2- , HCF2CF2- , H2CFCF2- , CH3CF2- , CF3CHF- , CH3CF2- , CF3CF2CF2- , HCF2CF 2} CF ₂ -, H ₂ CFCF ₂ CF ₂ -, CH ₃ CF ₂ CF ₂ -, and those represented by the following formula:

， [chemical formula 13]

,

， [chemical formula 14]

,

Mention may be made as preferred examples of the fluorinated alkyl group (a).

The ether bond-containing fluorinated alkyl group (b) is a group obtainable by replacing at least one hydrogen atom of the ether bond-containing alkyl group with a fluorine atom. The carbon number of the fluorinated alkyl group (b) having an ether bond is preferably 2-17. Excessive carbon number can lead to high viscosity of fluorinated saturated cyclic carbonate. This can also lead to the presence of many fluorine-containing groups, poor solubility of electrolyte salts due to reduced permittivity, and poor miscibility with other solvents. Therefore, the carbon number of the fluorinated alkyl group (b) containing an ether bond is preferably 2-10, more preferably 2-7.

The alkylene group constituting the ether portion of the fluorinated alkyl group (b) having an ether bond is a linear or branched chain alkylene group. Examples of the minimum structural unit constituting such linear or branched alkylene groups are shown below.

(i) The smallest structural unit of straight chain -CH ₂ -, -CHF-, -CF ₂ -, -CHCl-, -CFCl-, -CCl ₂ -

(ii) The smallest structural unit of the branch chain

[chemical formula 15]

The alkylene group may consist of one of these smallest structural units, or may consist of a plurality of linear units (i), a plurality of branched units (ii), or a combination of linear units (i) and branched units (ii) constitute. Preferred examples will be mentioned in detail later.

Preferred among these exemplary units are Cl-free structural units because such units can be dehydrochlorinated without a base and thus can be more stable.

A still more preferable example of the fluorinated alkyl group (b) containing an ether bond is a group represented by the following formula (b-1): R ³ -(OR ⁴ ) _n1 - (b-1) wherein R ³ is preferably A C1-C6 alkyl group optionally containing a fluorine atom; ^R4 is preferably a C1-C4 alkylene group optionally containing a fluorine atom; n1 is an integer from 1 to 3; and is selected from the group consisting of ^R3 and ^R4 At least one of them contains a fluorine atom.

Examples of R ³ and R ⁴ include the following groups, and any appropriate combination of these groups can provide the ether bond-containing fluorinated alkyl group (b) represented by formula (b-1). However, the groups are not limited thereto.

(1) R ³ is preferably an alkyl group represented by the following formula: X ^c ₃ C-(R ⁵ ) _n2 -, wherein three X ^c are the same or different from each other, and each is H or F; R ⁵ is optionally a C1-C5 alkylene group containing a fluorine atom; and n2 is 0 or 1.

When n2 is 0, R ³ may be, for example, CH ₃ -, CF ₃ -, HCF ₂ - or H ₂ CF-.

When n2 is 1, specific examples of R ³ as a linear group include CF ₃ CH ₂ -, CF ₃ CF ₂ -, CF ₃ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ -, CF ₃ CH ₂ CF ₂ -, CF ₃ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ -, CF ₃ CH ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ -, CF ₃ CF ₂ CH ₂ CF ₂ -, CF ₃ CH ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CH ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CF 2 CH _{2 CH 2} -, HCF ₂ CH ₂ -, HCF ₂ CF ₂ -, HCF ₂ CH ₂ CH ₂ -, HCF ₂ CF ₂ CH ₂ -, HCF ₂ CH ₂ CF ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ -, HCF 2 CH 2 CF ₂ CH ₂ -, HCF _{2 CF 2 CF 2} CF ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ CH ₂ -, HCF ₂ CH ₂ CF ₂ CH ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ CH ₂ CH ₂ -, FCH ₂ CH ₂ -, FCH ₂ CF ₂ -, FCH ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ -, CH ₃ CH ₂ -, CH ₃ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ -, CH ₃ CH ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ -, CH ₃ CF ₂ CF ₂ CF ₂ -, CH ₃ CH ₂ CF ₂ CF ₂ -, CH ₃ CH ₂ CH ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ C H ₂ -, CH ₃ CF ₂ CF ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ CH ₂ CH ₂ -, CH ₃ CH ₂ CF ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ CH _{2 CH2- , CH3CH2CF2CF2CH2CH2- and CH3CF2CH2CF2CH2CH2- . _ _ _ _ _ _ _}

When n2 is 1, they are represented by the following formula:

[chemical formula 16]

Mention may be made as an example of ^R3 as a branched chain group.

The presence of branches such as CH ₃ - or CF ₃ - can easily lead to high viscosity. Therefore, R ³ is more preferably a linear group.

(2) In -(OR ⁴ ) _n1 - of the formula (b-1), n1 is an integer of 1 to 3, preferably 1 or 2. When n1 is 2 or 3, R ⁴ may be the same as or different from each other.

Preferable specific examples of R ⁴ include the following linear or branched chain groups.

Examples _of linear groups _{include -CH2- ,} -CHF-, -CF2-, _-CH2CH2- , _{-CF2CH2- , -CF2CF2- , -CH2CF2-} , - CH ₂ CH ₂ CH ₂ -, -CH ₂ CH ₂ CF ₂ -, -CH ₂ CF ₂ CH ₂ -, -CH ₂ CF ₂ CF ₂ -, -CF ₂ CH ₂ CH ₂ -, -CF ₂ CF ₂ CH ₂ -, -CF ₂ CH ₂ CF ₂ - and -CF ₂ CF ₂ CF ₂ -.

They are represented by the following formula:

[chemical formula 17]

Mention may be made as examples of branched chain groups.

The fluorinated alkoxy group (c) is a group obtainable by replacing at least one hydrogen atom of the alkoxy group with a fluorine atom. The carbon number of the fluorinated alkoxy group (c) is preferably 1-17, more preferably 1-6.

The fluorinated alkoxy group (c) is especially preferably a fluorinated alkoxy group represented by X ^d ₃ C-(R ⁶ ) _n3 -O-, wherein three X ^d are the same or different from each other, and each is H or F ; R ⁶ is preferably a C1-C5 alkylene group optionally containing a fluorine atom; n3 is 0 or 1; and any one of the three X ^d contains a fluorine atom.

Specific examples of the fluorinated alkoxy group (c) include fluorinated alkoxy groups in which an oxygen atom is bonded to the terminal of the alkyl group mentioned as an example of R ^a1 in formula (a-1).

Each of the fluorinated alkyl group (a), the fluorinated alkyl group (b) and the fluorinated alkoxy group (c) having an ether bond in the fluorinated saturated cyclic carbonate preferably has a fluorine content of 10% by mass or more . An excessively low fluorine content may result in failure to sufficiently achieve the effect of lowering the viscosity at low temperature and the effect of raising the flash point. Therefore, the fluorine content is more preferably 12% by mass or higher, still more preferably 15% by mass or higher. The upper limit thereof is usually 76% by mass. The fluorine content of each of the fluorinated alkyl group (a), the fluorinated alkyl group (b) containing an ether bond, and the fluorinated alkoxy group (c) is a value calculated by the following formula based on the corresponding structural formula: {(number of fluorine atoms×19)/(group formula weight)}×100 (%).

In order to provide good permittivity and oxidation resistance, the fluorine content in the entire fluorinated saturated cyclic carbonate is preferably 10% by mass or higher, more preferably 15% by mass or higher. The upper limit thereof is usually 76% by mass. The fluorine content in the fluorinated saturated cyclic carbonate is the value calculated by the following formula based on the structural formula of the fluorinated saturated cyclic carbonate: {(number of fluorine atoms×19)/(molecular weight of fluorinated saturated cyclic carbonate)}×100 (%).

Specific examples of fluorinated saturated cyclic carbonates include the following.

Specific examples of the fluorinated saturated cyclic carbonate in which at least one selected from ^X1 to ^X4 is -F include those represented by the following formulae.

此等化合物具有高耐受電壓且提供電解質鹽之良好溶解度。 [chemical formula 18]

These compounds have high withstand voltages and provide good solubility of electrolyte salts.

Or, those represented by the following formulae:

[chemical formula 19]

can also be used.

They are represented by the following formula:

[chemical formula 20]

， [chemical formula 21]

,

， [chemical formula 22]

,

Mention may be made as specific examples of fluorinated saturated cyclic carbonates in which at least one selected from ^X1 to ^X4 is a fluorinated alkyl group (a) and the other is -H.

They are represented by the following formula:

， [chemical formula 23]

,

， [chemical formula 24]

,

， [chemical formula 25]

,

， [chemical formula 26]

,

， [chemical formula 27]

,

[chemical formula 28]

Can be used as a fluorinated saturated cyclic carbonate in which at least one selected from ^X1 to ^X4 is a fluorinated alkyl group (b) or a fluorinated alkoxy group (c) containing an ether bond and the other is -H Specific examples are mentioned.

Specifically, the fluorinated saturated cyclic carbonate is preferably any of the following compounds.

[chemical formula 29]

[chemical formula 30]

𠷬-2-酮、5-(1,1-二氟乙基)-4,4-二氟-1,3-二

𠷬-2-酮、4-亞甲基-1,3-二

𠷬-2-酮、4-甲基-5-三氟甲基-1,3-二

𠷬-2-酮、4-乙基-5-氟-1,3-二

𠷬-2-酮、4-乙基-5,5-二氟-1,3-二

𠷬-2-酮、4-乙基-4,5-二氟-1,3-二

𠷬-2-酮、4-乙基-4,5,5-三氟-1,3-二

𠷬-2-酮、4,4-二氟-5-甲基-1,3-二

𠷬-2-酮、4-氟-5-甲基-1,3-二

𠷬-2-酮、4-氟-5-三氟甲基-1,3-二

𠷬-2-酮及4,4-二氟-1,3-二

𠷬-2-酮。Examples of fluorinated saturated cyclic carbonates also include trans-4,5-difluoro-1,3-bis

𠷬-2-one, 5-(1,1-difluoroethyl)-4,4-difluoro-1,3-di

𠷬-2-one, 4-methylene-1,3-di

𠷬-2-one, 4-methyl-5-trifluoromethyl-1,3-di

𠷬-2-one, 4-ethyl-5-fluoro-1,3-di

𠷬-2-one, 4-ethyl-5,5-difluoro-1,3-di

𠷬-2-one, 4-ethyl-4,5-difluoro-1,3-di

𠷬-2-one, 4-ethyl-4,5,5-trifluoro-1,3-di

𠷬-2-one, 4,4-difluoro-5-methyl-1,3-di

𠷬-2-one, 4-fluoro-5-methyl-1,3-di

𠷬-2-one, 4-fluoro-5-trifluoromethyl-1,3-di

𠷬-2-one and 4,4-difluoro-1,3-di

𠷬-2-one.

Among these, more preferred fluorinated saturated cyclic carbonates are fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethyl ethyl carbonate, (3,3,3-trifluoropropylethylene carbonate) ), 2,2,3,3,3-pentafluoropropylethylcarbonate.

The fluorinated unsaturated cyclic carbonate is a cyclic carbonate containing an unsaturated bond and a fluorine atom, and is preferably a fluorinated ethyl carbonate derivative substituted with a substituent containing an aromatic ring or a carbon-carbon double bond. Specific examples thereof include 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4 -Fluoro-5-vinyl ethyl carbonate, 4-fluoro-4-phenyl ethyl carbonate, 4,4-difluoro-4-vinyl ethyl carbonate, 4,4-difluoro-4- Allyl ethyl carbonate, 4-fluoro-4-vinyl ethyl carbonate, 4-fluoro-4,5-diallyl ethyl carbonate, 4,5-difluoro-4-vinyl carbonate Ethylene, 4,5-difluoro-4,5-divinyl ethyl carbonate and 4,5-difluoro-4,5-diallyl ethyl carbonate.

One fluorinated cyclic carbonate may be used alone, or two or more of them may be used in any ratio in any combination.

When present, the fluorinated cyclic carbonate is preferably present in an amount of 5 to 90% by volume, more preferably 10 to 60% by volume, still more preferably 15 to 45% by volume relative to the solvent.

The acyclic carbonate can be a non-fluorinated acyclic carbonate or a fluorinated acyclic carbonate.

Examples of non-fluorinated acyclic carbonates include hydrocarbon-based acyclic carbonates such as CH ₃ OCOOCH ₃ (dimethyl carbonate, DMC), CH ₃ CH ₂ OCOOCH ₂ CH ₃ (diethyl carbonate Diethyl carbonate, DEC), CH ₃ CH ₂ OCOOCH ₃ (ethyl methyl carbonate, EMC), CH ₃ OCOOCH ₂ CH ₂ CH ₃ (methyl propyl carbonate), methyl butyl carbonate, carbonic acid Ethyl propyl ester, ethyl butyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl isopropyl carbonate, methyl-2-phenyl phenyl carbonate, phenyl-2-phenyl phenyl carbonate, transcarbonate -2,3-pentyl ester, trans-2,3-butyl carbonate and ethylphenyl carbonate. Preferred among these is at least one selected from the group consisting of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate.

One non-fluorinated acyclic carbonate may be used alone, or two or more of them may be used in any ratio in any combination.

When non-fluorinated acyclic carbonate is present, it is preferably present in an amount of 10 to 90% by volume, more preferably 40 to 85% by volume, still more preferably 50 to 80% by volume relative to the solvent.

Fluorinated acyclic carbonates are acyclic carbonates containing fluorine atoms. Solvents containing fluorinated acyclic carbonates can suitably be used at high voltages.

Examples of fluorinated acyclic carbonates are compounds represented by the following formula (B): Rf ² OCOOR ⁷ (B) wherein Rf ² is a C1-C7 fluorinated alkyl group; and R ⁷ is C1 optionally containing a fluorine atom -C7 alkyl.

Rf ² is a C1-C7 fluorinated alkyl group and R ⁷ is a C1-C7 alkyl group optionally containing a fluorine atom. A fluorinated alkyl group is a group obtainable by replacing at least one hydrogen atom of the alkyl group with a fluorine atom. When R ⁷ is an alkyl group containing a fluorine atom, it is a fluorinated alkyl group. In order to provide low viscosity, each of Rf ² and R ⁷ preferably has a carbon number of 1-7, more preferably 1-2. An excessively large carbon number may result in poor low-temperature characteristics and low solubility of electrolyte salts. Too low carbon number can lead to, for example, low solubility of electrolyte salt, low discharge efficiency and increased viscosity.

Examples of the fluorinated alkyl group having a carbon number of 1 include CFH ₂ -, CF ₂ H-, and CF ₃ -. In order to provide high-temperature storage properties, CFH ₂ - or CF ₃ - is especially preferred.

In order to provide good solubility of the electrolyte salt, preferred examples of a fluorinated alkyl group having a carbon number of 2 or more include a fluorinated alkyl group represented by the following formula (d-1): R ^d1 -R ^d2 - (d-1 ) wherein R ^d1 is an alkyl group having a carbon number of 1 or more and optionally containing a fluorine atom; R ^d2 is a C1-C3 alkylene group optionally containing a fluorine atom; and is selected from the group consisting of R ^d1 and R ^d2 At least one of them contains a fluorine atom. Each of ^Rd1 and ^Rd2 may further contain atoms other than carbon, hydrogen and fluorine atoms.

R ^d1 is an alkyl group having a carbon number of 1 or more and optionally containing a fluorine atom. R ^d1 is preferably a C1-C6 straight chain or branched chain alkyl group. The carbon number of R ^d1 is more preferably 1-3.

Specifically, for example, CH ₃ -, CF ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, CH ₃ CH ₂ CH ₂ CH ₂ -, and a group represented by the following formula:

[chemical formula 31]

May be mentioned as straight-chain or branched-chain alkyl for ^Rd1 .

Examples of R ^d1 as a linear alkyl group containing a fluorine atom include CF ₃ -, CF ₃ CH ₂ -, CF ₃ CF ₂ -, CF ₃ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ -, CF ₃ CH ₂ CF ₂ -, CF ₃ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ -, CF ₃ CH ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ -, CF ₃ CF ₂ CH ₂ CF ₂ -, CF ₃ CH ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CH ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CF 2 CH _{2 CH 2} -, HCF ₂ -, HCF ₂ CH ₂ -, HCF ₂ CF ₂ -, HCF ₂ CH ₂ CH ₂ -, HCF ₂ CF ₂ CH ₂ -, HCF ₂ CH ₂ CF ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ -, HCF ₂ CH ₂ CF ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ CH ₂ - _, HCF ₂ CH ₂ CF ₂ CH ₂ CH ₂ -, HCF ₂ CF 2 CF ₂ CF ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ CH ₂ CH ₂ -, FCH ₂ -, FCH ₂ CH ₂ -, FCH ₂ CF ₂ -, FCH ₂ CF ₂ CH ₂ -, FCH ₂ CF ₂ CF ₂ -, CH ₃ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ -, CH ₃ CF ₂ CF ₂ CF ₂ -, CH ₃ CH ₂ CF ₂ CF ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CF ₂ CH ₂ CH ₂ -, CH ₃ CH ₂ CF ₂ CF ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF ₂ CH ₂ CH ₂ -, CH ₃ CF ₂ CH ₂ CF _{2CH2CH2- , HCFClCF2CH2- , HCF2CFClCH2- , HCF2CFClCF2CFClCH2- , and HCFClCF2CFClCF2CH2- . _ _}

Examples of R ^d1 as the branched alkyl group containing a fluorine atom include those represented by the following formulae.

， [chemical formula 32]

,

[chemical formula 33]

The presence of branches such as CH ₃ - or CF ₃ - can easily lead to high viscosity. Therefore, the number of such branches is preferably a small number (one) or zero.

R ^d2 is a C1-C3 alkylene group optionally containing a fluorine atom. R ^d2 may be a straight chain or a branched chain. Examples of the minimum structural unit constituting such linear or branched alkylene groups are shown below. R ^d2 consists of one or a combination of these units.

(i) The smallest structural unit of straight chain -CH ₂ -, -CHF-, -CF ₂ -, -CHCl-, -CFCl-, -CCl ₂ -

(ii) The smallest structural unit of the branch chain

[chemical formula 34]

Preferred among these exemplary units are Cl-free structural units because such units can be dehydrochlorinated without a base and thus can be more stable.

R ^d2 as a linear group consists only of any one of the above linear minimum structural units, and is preferably -CH ₂ -, -CH ₂ CH ₂ - or -CF ₂ -. In order to further improve the solubility of the electrolyte salt, -CH ₂ - or -CH ₂ CH ₂ - is more preferable.

R ^d2 as a branched chain group includes at least one of the above branched chain minimum structural units. Its preferred example is from -(CX ^a X ^b )- (wherein X ^a is H, F, CH ₃ or CF ₃ ; X ^b is CH ₃ or CF ₃ ; when X ^b is CF ₃ , X ^a is H or CH ₃ ). Such groups can further greatly improve the solubility of electrolyte salts.

For example, CF ₃ CF ₂ -, HCF ₂ CF ₂ -, H ₂ CFCF ₂ -, CH ₃ CF ₂ -, CF ₃ CH ₂ -, CF ₃ CF ₂ CF ₂ -, HCF ₂ CF ₂ CF ₂ -, H ₂ CFCF ₂ CF ₂ -, CH ₃ CF ₂ CF ₂ -, and those represented by the following formulae:

， [chemical formula 35]

,

， [chemical formula 36]

,

Specific mention may be made as preferred examples of fluorinated alkyl groups.

The fluorinated alkyl groups of Rf ² and R ⁷ are preferably CF ₃ -, CF ₃ CF ₂ -, (CF ₃ ) ₂ CH-, CF ₃ CH ₂ -, C ₂ F ₅ CH ₂ -, CF ₃ CF ₂ CH ₂ -, HCF ₂ CF ₂ CH ₂ -, CF ₃ CFHCF ₂ CH ₂ -, CFH ₂ -, and CF ₂ H-. In order to provide high nonflammability and good rate characteristics and oxidation resistance, CF ₃ CH ₂ -, CF ₃ CF ₂ CH ₂ -, HCF ₂ CF ₂ CH ₂ -, CFH ₂ -, and CF ₂ H- are more preferable.

When R ⁷ is an alkyl group not containing a fluorine atom, it is a C1-C7 alkyl group. In order to provide low viscosity, the carbon number of R ⁷ is preferably 1-4, more preferably 1-3.

Examples of the alkyl group not containing a fluorine atom include CH ₃ -, CH ₃ CH ₂ -, (CH ₃ ) ₂ CH-, and C ₃ H ₇ -. In order to provide low viscosity and good rate characteristics, CH ₃ - and CH ₃ CH ₂ - are preferred.

The fluorinated acyclic carbonate preferably has a fluorine content of 15 to 70% by mass. Fluorinated acyclic carbonates having a fluorine content within the above range can maintain miscibility with solvents and solubility of salts. The fluorine content is more preferably 20% by mass or more, more preferably 30% by mass or more, especially preferably 35% by mass or more, and more preferably 60% by mass or less, still more preferably 50% by mass or more Low. In the present invention, the fluorine content is the value calculated by the following formula based on the structural formula of fluorinated acyclic carbonate: {(number of fluorine atoms×19)/(molecular weight of fluorinated acyclic carbonate)}×100 (%).

In order to provide low viscosity, the fluorinated acyclic carbonate is preferably any one of the following compounds.

[chemical formula 37]

Especially preferred fluorinated acyclic carbonate is 2,2,2-trifluoroethyl methyl carbonate (F ₃ CH ₂ COC(=O)OCH ₃ ).

One fluorinated acyclic carbonate may be used alone, or two or more of them may be used in any ratio in any combination.

When present, the fluorinated acyclic carbonate is preferably present in an amount of 10 to 90% by volume, more preferably 40 to 85% by volume, still more preferably 50 to 80% by volume relative to the solvent.

The carboxylate may be a cyclic carboxylate or an acyclic carboxylate.

The cyclic carboxylate can be a non-fluorinated cyclic carboxylate or a fluorinated cyclic carboxylate.

Examples of the non-fluorinated cyclic carboxylate include non-fluorinated saturated cyclic carboxylate, and are preferably non-fluorinated saturated cyclic carboxylate containing a C2-C4 alkylene group.

Specific examples of non-fluorinated saturated cyclic carboxylic acid esters containing C2-C4 alkylene include β-propiolactone, γ-butyrolactone, ε-caprolactone, δ-valerolactone, and α-methyl- Gamma-butyrolactone. Especially preferred among these are γ-butyrolactone and δ-valerolactone in order to improve the degree of dissociation of lithium ions and improve the load characteristics.

One non-fluorinated saturated cyclic carboxylic acid ester may be used alone, or two or more thereof may be used in any combination in any ratio.

When a non-fluorinated saturated cyclic carboxylate is present, it is preferably present in an amount of 0 to 90% by volume, more preferably 0.001 to 90% by volume, more preferably 1 to 60% by volume, and especially preferably 5% by volume relative to the solvent. to 40% by volume.

The acyclic carboxylate may be a non-fluorinated acyclic carboxylate or a fluorinated acyclic carboxylate. The solvent containing the acyclic carboxylate makes it possible to further reduce the resistance increase of the electrolytic solution after storage at high temperature.

Examples of non-fluorinated acyclic carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, propionic acid Tertiary butyl ester, tertiary butyl butyrate, secondary butyl propionate, secondary butyl butyrate, n-butyl butyrate, methyl pyrophosphate, ethyl pyrophosphate, tertiary butyl formate, acetic acid tertiary Tributyl, secondary butyl formate, secondary butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl acetate, n-butyl formate, n-butyl pivalate, n-octyl pivalate , 2-(dimethoxyphosphoryl) ethyl acetate, 2-(dimethylphosphoryl) ethyl acetate, 2-(diethoxyphosphoryl) ethyl acetate, 2-(diethyl Phosphoryl) ethyl acetate, isopropyl propionate, isopropyl acetate, ethyl formate, ethyl 2-propynyl oxalate, isopropyl formate, isopropyl butyrate, isobutyl formate, propionic acid Isobutyl ester, isobutyl butyrate and isobutyl acetate.

Among these, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferable, and ethyl propionate and propyl propionate are particularly preferable.

One non-fluorinated acyclic carboxylic acid ester may be used alone, or two or more thereof may be used in any ratio in any combination.

When a non-fluorinated acyclic carboxylate is present, it is preferably present in an amount of 0 to 90% by volume, more preferably 0.001 to 90% by volume, more preferably 1 to 60% by volume, especially preferably 5 to 40% by volume.

Fluorinated acyclic carboxylates are acyclic carboxylates containing fluorine atoms. Solvents containing fluorinated acyclic carboxylates can suitably be used at high voltages.

In order to achieve good miscibility with other solvents and provide good oxidation resistance, preferred examples of fluorinated acyclic carboxylates include those represented by the following formula: R ³¹ COOR ³² (wherein R ³¹ and ^R32 are each independently a C1-C4 alkyl group optionally containing a fluorine atom, and at least one selected from the group consisting of ^R31 and ^R32 contains a fluorine atom).

Examples of R ³¹ and R ³² include non-fluorinated alkyl groups such as methyl (-CH ₃ ), ethyl (-CH ₂ CH ₃ ), propyl (-CH ₂ CH ₂ CH ₃ ), isopropyl (-CH 3 ), CH(CH ₃ ) ₂ ), n-butyl (-CH ₂ CH ₂ CH ₂ CH ₃ ) and tertiary butyl (-C(CH ₃ ) ₃ ); and fluorinated alkyl groups such as -CF ₃ , -CF ₂ H, -CFH ₂ , -CF ₂ CF ₃ , -CF ₂ CF 2 H, -CF ₂ CFH ₂ , -CH ₂ CF ₃ , -CH _{2 CF 2 H, -CH 2 CFH 2 , -CF 2} CF ₂ CF ₃ , -CF ₂ CF ₂ CF ₂ H, -CF ₂ CF ₂ CFH ₂ , -CH ₂ CF ₂ CF ₃ , -CH ₂ CF ₂ CF ₂ H, -CH ₂ CF ₂ CFH ₂ , -CH ₂ CH ₂ CF ₃ , -CH ₂ CH ₂ CF ₂ H, -CH ₂ CH ₂ CFH ₂ , -CF(CF ₃ ) ₂ , -CF(CF ₂ H) ₂ , -CF(CFH ₂ ) ₂ , -CH(CF ₃ ) ₂ , -CH(CF ₂ H) ₂ , -CH(CFH ₂ ) ₂ , -CF(OCH ₃ )CF ₃ , -CF ₂ CF ₂ CF ₂ CF ₃ , -CF ₂ CF ₂ CF ₂ CF ₂ H, -CF ₂ CF ₂ CF ₂ CFH ₂ , -CH ₂ CF ₂ CF ₂ CF ₃ , -CH ₂ CF 2 CF _{2 CF 2} H, -CH ₂ CF 2 CF ₂ CFH ₂ , -CH ₂ CH ₂ CF _{2 CF 3} , -CH ₂ CH ₂ CF ₂ CF ₂ H, -CH ₂ CH ₂ CF ₂ CFH ₂ , -CH ₂ CH ₂ CH ₂ CF ₃ , -CH ₂ CH ₂ CH ₂ CF ₂ H, -CH ₂ CH ₂ CH ₂ CFH ₂ , -CF(CF ₃ )CF ₂ CF ₃ , -CF(CF ₂ H)CF ₂ CF ₃ , -CF(CFH ₂ )CF ₂ CF ₃ , -CF(CF ₃ )CF ₂ CF ₂ H, - CF(CF ₃ )CF ₂ CFH ₂ , -CF(CF ₃ )CH ₂ CF ₃ , -CF(CF ₃ )CH ₂ CF ₂ H, -CF(CF ₃ )CH ₂ CFH ₂ , -CH(CF ₃ ) CF ₂ CF ₃ , -CH(CF ₂ H)CF ₂ CF ₃ , -CH(C FH ₂ )CF ₂ CF ₃ , -CH(CF ₃ )CF ₂ CF ₂ H, -CH(CF ₃ )CF ₂ CFH ₂ , -CH(CF ₃ )CH ₂ CF ₃ , -CH(CF ₃ )CH ₂ CF ₂ H, -CH(CF ₃ )CH ₂ CFH ₂ , -CF ₂ CF(CF ₃ )CF ₃ , -CF ₂ CF(CF ₂ H)CF ₃ , -CF ₂ CF(CFH ₂ )CF ₃ , - CF ₂ CF(CF ₃ )CF ₂ H, -CF ₂ CF(CF ₃ )CFH ₂ , -CH ₂ CF(CF ₃ )CF ₃ , -CH ₂ CF(CF ₂ H)CF ₃ , -CH ₂ CF( CFH ₂ )CF ₃ , -CH ₂ CF(CF ₃ )CF ₂ H, -CH ₂ CF(CF ₃ )CFH ₂ , -CH ₂ CH(CF ₃ )CF ₃ , -CH ₂ CH(CF ₂ H)CF _3. -CH ₂ CH(CFH ₂ )CF ₃ , -CH ₂ CH(CF ₃ )CF ₂ H, -CH ₂ CH(CF ₃ )CFH ₂ , -CF ₂ CH(CF ₃ )CF ₃ , -CF ₂ CH(CF ₂ H)CF ₃ , -CF ₂ CH(CFH ₂ )CF ₃ , -CF ₂ CH(CF ₃ )CF ₂ H, -CF ₂ CH(CF ₃ )CFH ₂ , -C(CF ₃ ) ₃ , -C(CF ₂ H) ₃ and -C(CFH ₂ ) ₃ . In order to improve the miscibility, viscosity and oxidation resistance with other solvents, methyl, ethyl, -CF ₃ , -CF ₂ H, -CF ₂ CF ₃ , -CH ₂ CF ₃ , -CH ₂ CF ₂ H, -CH ₂ CFH ₂ , -CH ₂ CH ₂ CF ₃ , -CH ₂ CF ₂ CF ₃ , -CH ₂ CF ₂ CF ₂ H, and -CH ₂ CF ₂ CFH ₂ .

Specific examples of fluorinated acyclic carboxylic acid esters include one or both or more of the following: CF ₃ CH ₂ C(=O)OCH ₃ (methyl 3,3,3-trifluoropropionate) , HCF ₂ C(=O)OCH ₃ (methyl difluoroacetate), HCF ₂ C(=O)OC ₂ H ₅ (ethyl difluoroacetate), CF ₃ C(=O)OCH ₂ CH ₂ CF ₃ , CF ₃ C(=O)OCH ₂ C ₂ F ₅ , CF ₃ C(=O)OCH ₂ CF ₂ CF ₂ H (2,2,3,3-tetrafluoropropyl trifluoroacetate), CF ₃ C (=O)OCH ₂ CF ₃ , CF ₃ C(=O)OCH(CF ₃ ) ₂ , ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate ester, isopropyl trifluorobutyrate, ethyl trifluoroacetate, tertiary butyl trifluoroacetate, n-butyl trifluoroacetate, methyl tetrafluoro-2-(methoxy)propionate, 2,2 acetic acid -Difluoroethyl ester, 2,2,3,3-tetrafluoropropyl acetate, CH ₃ C(=O)OCH ₂ CF ₃ (2,2,2-trifluoroethyl acetate), acetic acid 1H,1H- Heptafluorobutyl, methyl 4,4,4-trifluorobutyrate, ethyl 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3- 3,3,3-trifluoropropyl trifluoropropionate, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, butyl 2,2-difluoroacetate ester, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate and methyl heptafluorobutyrate. In order to achieve good miscibility with other solvents and good rate characteristics, CF ₃ CH ₂ C(=O)OCH ₃ , HCF ₂ C(=O)OCH ₃ , HCF ₂ C(=O) are preferred among them. OC ₂ H ₅ , CF ₃ C(=O)OCH ₂ C ₂ F ₅ , CF ₃ C(=O)OCH ₂ CF ₂ CF ₂ H, CF ₃ C(=O)OCH ₂ CF ₃ , CF ₃ C( =O)OCH(CF ₃ ) ₂ , ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, isopropyl trifluorobutyrate, trifluoroacetic acid Ethyl ester, tertiary butyl trifluoroacetate, n-butyl trifluoroacetate, methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3 acetic acid, 3-tetrafluoropropyl ester, CH ₃ C(=O)OCH ₂ CF ₃ , 1H,1H-heptafluorobutyl acetate, 4,4,4-trifluorobutyric acid methyl ester, 4,4,4-trifluoro Ethyl butyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropyl 3,3,3-trifluoropropionate, ethyl 3-(trifluoromethyl)butyrate ester, methyl 2,3,3,3-tetrafluoropropionate, butyl 2,2-difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, 2-(trifluoromethyl) -3,3,3-methyl trifluoropropionate and methyl heptafluorobutyrate, more preferably CF ₃ CH ₂ C(=O)OCH ₃ , HCF ₂ C(=O)OCH ₃ , HCF ₂ C( =O)OC ₂ H ₅ and CH ₃ C(=O)OCH ₂ CF ₃ , and especially preferably HCF ₂ C(=O)OCH ₃ , HCF ₂ C(=O)OC ₂ H ₅ and CH ₃ C ₍ =O) _OCH2CF3 .

One fluorinated acyclic carboxylic acid ester may be used alone, or two or more thereof may be used in any ratio in any combination.

When present, the fluorinated acyclic carboxylate is preferably present in an amount of 10 to 90% by volume, more preferably 40 to 85% by volume, still more preferably 50 to 80% by volume relative to the solvent.

The solvent preferably contains at least one selected from the group consisting of cyclic carbonates, acyclic carbonates and acyclic carboxylates, and more preferably contains cyclic carbonates and is selected from acyclic carbonates and noncyclic carboxylic acid esters. At least one member of the group consisting of cyclic carboxylates. The cyclic carbonate is preferably a saturated cyclic carbonate. An electrolyte solution containing a solvent of such a composition enables an electrochemical device to have further improved high-temperature storage characteristics and cycle characteristics.

For the solvent containing cyclic carbonate and at least one selected from the group consisting of acyclic carbonate and acyclic carboxylate, cyclic carbonate and a solvent selected from acyclic carbonate and noncyclic carboxylic acid The total amount of at least one of the ester group is preferably 10 to 100% by volume, more preferably 30 to 100% by volume, and still more preferably 50 to 100% by volume.

For the solvent containing cyclic carbonate and at least one selected from the group consisting of acyclic carbonate and acyclic carboxylate, cyclic carbonate and a solvent selected from acyclic carbonate and noncyclic carboxylic acid At least one of the group of esters preferably provides a volume ratio of 5/95 to 95/5, more preferably 10/90 or higher, more preferably 15/85 or higher, especially preferably 20/80 or higher High, more preferably 90/10 or lower, more preferably 60/40 or lower, especially preferably 50/50 or lower.

The solvent also preferably contains at least one selected from the group consisting of non-fluorinated saturated cyclic carbonate, non-fluorinated non-cyclic carbonate and non-fluorinated non-cyclic carboxylate, more preferably contains non-fluorinated saturated Cyclic carbonate and at least one selected from the group consisting of non-fluorinated acyclic carbonate and non-fluorinated acyclic carboxylate. Electrolyte solutions containing solvents of such composition can be suitably used for electrochemical devices used at relatively low voltages.

For the solvent containing non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of non-fluorinated non-cyclic carbonate and non-fluorinated non-cyclic carboxylate, non-fluorinated saturated cyclic carbonate and the total amount of at least one selected from the group consisting of non-fluorinated acyclic carbonates and non-fluorinated acyclic carboxylates is preferably from 5 to 100% by volume, more preferably from 20 to 100% by volume, and then More preferably 30 to 100% by volume.

For an electrolyte solution containing non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of non-fluorinated non-cyclic carbonate and non-fluorinated non-cyclic carboxylate, the non-fluorinated saturated cyclic carbonate Esters and at least one selected from the group consisting of non-fluorinated acyclic carbonates and non-fluorinated acyclic carboxylates preferably provide a volume ratio of 5/95 to 95/5, more preferably 10/90 or Higher, more preferably 15/85 or higher, especially preferably 20/80 or higher, more preferably 90/10 or lower, more preferably 60/40 or lower, especially preferably 50/50 or lower.

The solvent preferably contains at least one selected from the group consisting of fluorinated saturated cyclic carbonate, fluorinated acyclic carbonate and fluorinated acyclic carboxylate, and more preferably contains fluorinated saturated cyclic carbonate and at least one selected from the group consisting of fluorinated acyclic carbonates and fluorinated acyclic carboxylates. An electrolytic solution containing a solvent of such a composition can be suitably used not only for an electrochemical device used at a relatively high voltage, but also for an electrochemical device used at a relatively low voltage.

For the solvent containing fluorinated saturated cyclic carbonate and at least one selected from the group consisting of fluorinated acyclic carbonate and fluorinated acyclic carboxylate, fluorinated saturated cyclic carbonate and The total amount of at least one of the group consisting of fluorinated acyclic carbonate and fluorinated acyclic carboxylate is preferably 5 to 100% by volume, more preferably 10 to 100% by volume, more preferably 30 to 100% by volume %.

For the solvent containing fluorinated saturated cyclic carbonate and at least one selected from the group consisting of fluorinated acyclic carbonate and fluorinated acyclic carboxylate, fluorinated saturated cyclic carbonate and At least one of the group consisting of fluorinated acyclic carbonates and fluorinated acyclic carboxylates preferably provides a volume ratio of 5/95 to 95/5, more preferably 10/90 or higher, more preferably 15 /85 or higher, especially preferably 20/80 or higher, more preferably 90/10 or lower, still more preferably 60/40 or lower, especially preferably 50/50 or lower.

The solvent used may be an ionic liquid. "ionic liquid" means a liquid containing ions that are a combination of organic cations and anions.

Examples of organic cations include, but are not limited to, imidazolium ions, such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; basepiperidinium ion.

Examples of anions to be used as counterions to any of these organic cations _{include, but are not limited to, PF6 anion, PF3(C2F5)3 anion , PF3 ( CF3 ) 3} anion, _BF4 anion , BF ₂ (CF ₃ ) ₂ anion, BF ₃ (CF ₃ ) anion, bisoxalate borate anion, P(C ₂ O ₄ )F ₂ anion, trifluoromethanesulfonyl (trifluoromethanesulfonyl; Tf) anion, nonafluoro Butanesulfonyl (nonafluorobutanesulfonyl; Nf) anion, bis(fluorosulfonyl)imide anion, bis(trifluoromethylsulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, dicyanide Amine anions and halide anions.

The solvent is preferably a non-aqueous solvent, and the electrolyte solution of the present invention is preferably a non-aqueous electrolyte solution. The solvent is present in an amount of preferably 70 to 99.999% by mass of the electrolytic solution, more preferably 80% by mass or more, and at the same time preferably 92% by mass or less.

The electrolytic solution of the present invention may further contain a compound (3) represented by the following formula (3).

其中 A ^a+為金屬離子、氫離子或鎓離子； a為1至3之整數； b為1至3之整數； p為b/a； n ²⁰³為1至4之整數； n ²⁰¹為0至8之整數； n ²⁰²為0或1； Z ²⁰¹為過渡金屬或週期表之第III族、第IV族或第V族之元素； X ²⁰¹為O、S、C1-C10伸烷基、C1-C10鹵化伸烷基、C6-C20伸芳基或C6-C20鹵化伸芳基，其中伸烷基、鹵化伸烷基、伸芳基及鹵化伸芳基各自視情況在其結構中含有取代基及/或雜原子，且當n ²⁰²為1且n ²⁰³為2至4時，n ²⁰³個X ²⁰¹視情況彼此結合； L ²⁰¹為鹵素原子、氰基、C1-C10烷基、C1-C10鹵化烷基、C6-C20芳基、C6-C20鹵化芳基或-Z ²⁰³Y ²⁰³，其中伸烷基、鹵化伸烷基、伸芳基及鹵化伸芳基各自視情況在其結構中含有取代基及/或雜原子，且當n ²⁰¹為2至8時，n ²⁰¹個L ²⁰¹視情況彼此結合形成環； Y ²⁰¹、Y ²⁰²及Z ²⁰³各自獨立地為O、S、NY ²⁰⁴、烴基或氟化烴基； Y ²⁰³及Y ²⁰⁴各自獨立地為H、F、C1-C10烷基、C1-C10鹵化烷基、C6-C20芳基或C6-C20鹵化芳基，其中烷基、鹵化烷基、芳基及鹵化芳基各自視情況在其結構中含有取代基及/或雜原子，且當存在多個Y ²⁰³或多個Y ²⁰⁴時，其視情況彼此結合形成環。 Formula (3) is as follows: [Chemical formula 38]

Wherein A ^a+ is a metal ion, hydrogen ion or onium ion; a is an integer from 1 to 3; b is an integer from 1 to 3; p is b/a; n ²⁰³ is an integer from 1 to 4; n ²⁰¹ is an integer from 0 to 8 Integer; n ²⁰² is 0 or 1; Z ²⁰¹ is a transition metal or an element of Group III, Group IV or Group V of the periodic table; X ²⁰¹ is O, S, C1-C10 alkylene, C1-C10 Halogenated alkylene, C6-C20 arylylene or C6-C20 halogenated arylylene, wherein alkylene, halogenated alkylene, arylylene and halogenated arylylene each optionally contain a substituent in its structure and/ or a heteroatom, and when n ²⁰² is 1 and n ²⁰³ is 2 to 4, n ²⁰³ X ²⁰¹ are optionally combined with each other; L ²⁰¹ is a halogen atom, cyano, C1-C10 alkyl, C1-C10 halogenated alkyl , C6-C20 aryl, C6-C20 halogenated aryl or -Z ²⁰³ Y ²⁰³ , wherein alkylene, halogenated alkylene, arylylene and halogenated arylylene each contain a substituent in its structure and/or or heteroatoms, and when n ²⁰¹ is 2 to 8, n ²⁰¹ L ²⁰¹ are combined with each other to form a ring as appropriate; Y ²⁰¹ , Y ²⁰² and Z ²⁰³ are each independently O, S, NY ²⁰⁴ , hydrocarbon group or fluorinated hydrocarbon group Y ²⁰³ and Y ²⁰⁴ are each independently H, F, C1-C10 alkyl, C1-C10 halogenated alkyl, C6-C20 aryl or C6-C20 halogenated aryl, wherein alkyl, halogenated alkyl, aryl and halogenated aryl groups optionally contain substituents and/or heteroatoms in their structures, and when there are multiple Y ²⁰³ or multiple Y ²⁰⁴ , they are optionally combined with each other to form a ring.

Examples of A ^a+ include lithium ions, sodium ions, potassium ions, magnesium ions, calcium ions, barium ions, cesium ions, silver ions, zinc ions, copper ions, cobalt ions, iron ions, nickel ions, manganese ions, titanium ions, Lead ions, chromium ions, vanadium ions, ruthenium ions, yttrium ions, lanthanide ions, actinide ions, tetrabutylammonium ions, tetraethylammonium ions, tetramethylammonium ions, triethylmethylammonium ions , triethylammonium ions, pyridinium ions, imidazolium ions, hydrogen ions, tetraethylphosphonium ions, tetramethylphosphonium ions, tetraphenylphosphonium ions, triphenylperium ions and triethyl phosphonium ions.

In applications such as electrochemical devices, A ^a+ is preferably lithium ion, sodium ion, magnesium ion, tetraalkylammonium ion or hydrogen ion, especially lithium ion. The valency a of the cation A ^a+ is an integer of 1 to 3. If the valence number a is greater than 3, the lattice energy is high and the compound (3) is difficult to dissolve in a solvent. Therefore, the valency a is more preferably 1 when good solubility is required. The valency b of the anion is also an integer of 1 to 3, especially preferably 1. The constant p expressing the ratio between cations and anions is naturally defined by the ratio b/a between their valences.

Next, the ligand in formula (3) is described. The ligand herein means an organic or inorganic group that binds to Z ²⁰¹ in formula (3).

Z ²⁰¹ is preferably Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf or Sb, more preferably Al, B or P.

X ²⁰¹ is O, S, C1-C10 alkylene, C1-C10 halogenated alkylene, C6-C20 arylylene or C6-C20 halogenated arylylene. Each of these alkylene and arylylene groups may have substituents and/or heteroatoms in the structure. Specifically, instead of a hydrogen atom in an alkylene or arylylene, the structure may have a halogen atom, a linear or cyclic alkyl, aryl, alkenyl, alkoxy, aryloxy, sulfonyl, amine group, cyano group, carbonyl group, acyl group, amido group or hydroxyl group as a substituent; or instead of a carbon atom in an alkylene or arylene group, the structure may have nitrogen, sulfur or oxygen introduced therein. When n ²⁰² is 1 and n ²⁰³ is 2 to 4, n ²⁰³ X ²⁰¹ can be combined with each other. One such example is a ligand such as ethylenediaminetetraacetic acid.

L ²⁰¹ is a halogen atom, cyano group, C1-C10 alkyl, C1-C10 halogenated alkyl, C6-C20 aryl, C6-C20 halogenated aryl or -Z ²⁰³ Y ²⁰³ (Z ²⁰³ and Y ²⁰³ will be described later ). Similar to X ²⁰¹ , each of the alkyl group and the aryl group may have a substituent and/or a heteroatom in the structure, and when n ²⁰¹ is 2 to 8, n ²⁰¹ pieces of L ²⁰¹ are optionally combined with each other to form a ring. L ²⁰¹ is preferably a fluorine atom or a cyano group. This is because fluorine atoms can improve the solubility and dissociation of salts of anionic compounds, thereby improving ion conductivity. This is also because fluorine atoms can improve oxidation resistance and reduce the occurrence of side reactions.

Y ²⁰¹ , Y ²⁰² and Z ²⁰³ are each independently O, S, NY ²⁰⁴ , hydrocarbon group or fluorinated hydrocarbon group. Each of Y ²⁰¹ and Y ²⁰² is preferably O, S or NY ²⁰⁴ , more preferably O. Compound (3) typically has a bond between Y ²⁰¹ and Z ²⁰¹ and a bond between Y ²⁰² and Z ²⁰¹ in the same ligand. Such ligands form a chelate structure with Z ²⁰¹ . This chelate has the effect of improving the heat resistance, chemical stability and hydrolysis resistance of this compound. The constant n ²⁰² of the ligand is 0 or 1. In particular, n ²² is preferably 0, since the chelating ring becomes a five-membered ring, resulting in the most strongly exerted chelating effect and improved stability. The term "fluorinated hydrocarbon group" herein means a group obtainable by replacing at least one hydrogen atom of a hydrocarbon group with a fluorine atom.

Y ²⁰³ and Y ²⁰⁴ are each independently H, F, C1-C10 alkyl, C1-C10 halogenated alkyl, C6-C20 aryl or C6-C20 halogenated aryl. Each of these alkyl and aryl groups may contain substituents or heteroatoms in the structure. When a plurality of Y ²⁰³ or a plurality of Y ²⁰⁴ are present, they are combined with each other to form a ring as the case may be.

The constant n ²⁰³ related to the number of ligands is an integer from 1 to 4, preferably 1 or 2, more preferably 2. The constant n ²⁰¹ related to the number of ligands is an integer from 0 to 8, preferably an integer from 0 to 4, more preferably 0, 2 or 4. In addition, when n ²⁰³ is 1, n ²⁰¹ is preferably 2; and when n ²⁰³ is 2, n ²⁰¹ is preferably 0.

In formula (3), the alkyl group, halogenated alkyl group, aryl group, and halogenated aryl group include those having any other functional groups such as branches, hydroxyl groups, and ether bonds.

（其中A ^a+、a、b、p、n ²⁰¹、Z ²⁰¹及L ²⁰¹如上文所描述定義），或由下式表示之化合物： [化學式40]

（其中A ^a+、a、b、p、n ²⁰¹、Z ²⁰¹及L ²⁰¹如上文所描述定義）。 Compound (3) is preferably a compound represented by the following formula: [Chemical Formula 39]

(wherein A ^a+ , a, b, p, n ²⁰¹ , Z ²⁰¹ and L ²⁰¹ are defined as described above), or a compound represented by the following formula: [Chemical formula 40]

(wherein A ^a+ , a, b, p, n ²⁰¹ , Z ²⁰¹ and L ²⁰¹ are defined as described above).

； 由下式表示之二氟草酸硼酸鋰（lithium difluorooxalatoborate；LiDFOB）： [化學式42]

； 由下式表示之二氟草酸亞膦酸鋰（lithium difluorooxalatophosphanite；LiDFOP）： [化學式43]

； 由下式表示之四氟草酸亞膦酸鋰（lithium tetrafluorooxalatophosphanite；LITFOP）： [化學式44]

； 及 由下式表示之雙(草酸)二氟亞膦酸鋰： [化學式45]

。 Compound (3) may be lithium oxalate borate. Examples thereof include lithium bis(oxalato)borate (LiBOB) represented by the following formula: [Chemical Formula 41]

; lithium difluorooxalatoborate (LiDFOB) represented by the following formula: [Chemical Formula 42]

; Lithium difluorooxalatophosphite (LiDFOP) represented by the following formula: [Chemical Formula 43]

; Lithium tetrafluorooxalatophosphite (LITFOP) represented by the following formula: [Chemical Formula 44]

; and lithium bis(oxalate)difluorophosphinate represented by the following formula: [Chemical Formula 45]

.

Examples of compound (3) also include dicarboxylic acid complex salts containing boron as a complex central element, such as bis(malonate)lithium borate, difluoro(malonate)lithium borate, bis(methylmalonate) ) lithium borate, lithium difluoro(methylmalonate)borate, lithium bis(dimethylmalonate)borate and lithium difluoro(dimethylmalonate)borate.

Examples of compound (3) also include dicarboxylate zirconium salts containing phosphorus as a complex central element, such as lithium tris(oxalate)phosphate, lithium tris(malonate)phosphate, lithium difluorobis(malonate)phosphate , lithium tetrafluoro(malonate)phosphate, lithium tri(methylmalonate)phosphate, lithium difluorobis(methylmalonate)phosphate, lithium tetrafluoro(methylmalonate)phosphate, tri(two Lithium methylmalonate)phosphate, lithium difluorobis(dimethylmalonate)phosphate and lithium tetrafluoro(dimethylmalonate)phosphate.

Examples of compound (3) also include dicarboxylate zirconium salts containing aluminum as a complex central element, such as LiAl(C ₂ O ₄ ) ₂ and LiAlF ₂ (C ₂ O ₄ ).

More preferred among these are lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium tris(oxalate)phosphate, difluorobis(oxalate)borate, Lithium phosphate and lithium tetrafluoro(oxalate)phosphate. Compound (3) is especially preferably lithium bis(oxalate)borate.

In order to provide much better cycle characteristics, the amount of compound (3) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, while preferably 10% by mass or less, with respect to the solvent, more preferably 3% by mass or less.

The electrolyte solution of the present invention preferably further contains an electrolyte salt other than the compound (3). Examples of the electrolyte salt used include lithium salts, ammonium salts, and metal salts, and any of electrolyte salts to be used in the electrolyte solution, such as liquid salts (ionic liquids), inorganic polymer salts, and organic polymer salts.

The electrolyte salt used in the electrolyte solution of the lithium ion secondary battery is preferably a lithium salt. Any lithium salt can be used. Specific examples thereof include the following: Inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO 4 _, LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , LiWF ₇ , LiAsF ₆ , LiAlCl ₄ , LiI, LiBr, LiCl, LiB ₁₀ Cl ₁₀ , Li ₂ SiF ₆ , Li ₂ PFO ₃ and LiPO ₂ F ₂ ; Lithium tungstate such as LiWOF ₅ ; Lithium carboxylate such as HCO ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CO ₂ Li and CF ₃ CF ₂ CF ₂ CF ₂ CO ₂ Li; Lithium salts such as FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF 2 SO ₃ Li, CF ₃ CF ₂ CF _{2 SO 3} Li, CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ Li, lithium methylsulfate, lithium ethylsulfate (C ₂ H ₅ OSO ₃ Li) and lithium 2,2,2-trifluoroethylsulfate; lithium imides such as LiN(FCO) ₂ , LiN(FCO)(FSO ₂ ), LiN(FSO ₂ ) ₂ , LiN(FSO ₂ )(CF ₃ SO ₂ ), LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ . Lithium bisperfluoroethanesulfonyl imide, lithium cyclic 1,2-perfluoroethanedisulfonyl imide, lithium cyclic 1,3-perfluoropropanedisulfonyl imide, cyclic 1,2 -Lithium ethanedisulfonyl imide, cyclic lithium 1,3-propanedisulfonyl imide, cyclic lithium 1,4-perfluorobutanedisulfonyl imide, LiN(CF ₃ SO ₂ )(FSO ₂ ) , LiN(CF ₃ SO ₂ )(C ₃ F ₇ SO ₂ ), LiN(CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ ) and LiN(POF ₂ ) ₂ ; methyllithium salts such as LiC(FSO ₂ ) ₃ , LiC(CF ₃ SO ₂ ) ₃ and LiC(C ₂ F ₅ SO ₂ ) ₃ ; and fluorine-containing organic lithium salts, such as salts represented by the following formula: LiPF _a (C _n F _2n+1 ) _{6- a} (where a is an integer from 0 to 5; and n is an integer from 1 to 6), such as LiPF ₃ (C ₂ F ₅ ) ₃ , LiPF ₃ (CF ₃ ) ₃ , LiP F ₃ (isoC ₃ F ₇ ) ₃ , LiPF ₅ (isoC ₃ F ₇ ), LiPF ₄ (CF ₃ ) ₂ and LiPF ₄ (C ₂ F ₅ ) ₂ , and LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ , and LiSCN, LiB(CN) ₄ , LiB(C ₆ H ₅ ) ₄ , Li ₂ (C ₂ O ₄ ), LiP( C ₂ O ₄ ) ₃ and Li ₂ B ₁₂ F _b H _12-b (where b is an integer from 0 to 3).

In order to achieve the effect of improving properties such as output characteristics, high-rate charge and discharge characteristics, high-temperature storage characteristics, and cycle characteristics, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , LiPO ₂ F ₂ are particularly preferable among them. , FSO ₃ Li, CF ₃ SO ₃ Li, LiN(FSO ₂ ) ₂ , LiN(FSO ₂ )(CF ₃ SO ₂ ), LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , Cyclic lithium 1,2-perfluoroethanedisulfonyl imide, cyclic lithium 1,3-perfluoropropanedisulfonyl imide, LiC(FSO ₂ ) ₃ , LiC(CF ₃ SO ₂ ) ₃ , LiC( C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) ₃ and the like. Most preferred is at least one lithium salt selected from the group consisting of LiPF ₆ , LiN(FSO ₂ ) ₂ and LiBF ₄ .

One of these electrolyte salts may be used alone, or two or more of them may be used in combination. In the combined use of two or more of them, the preferred examples include the combination of LiPF ₆ and LiBF ₄ and the combination of LiPF ₆ and LiPO ₂ F ₂ , C ₂ H ₅ OSO ₃ Li or FSO ₃ Li, which Each has the effect of improving high-temperature storage characteristics, load characteristics, and cycle characteristics.

In this case, LiBF ₄ , LiPO ₂ F ₂ , C ₂ H ₅ OSO ₃ Li, or FSO ₃ Li may be present in 100% by mass of the entire electrolytic solution in any amount that does not significantly impair the effect of the present invention. The amount thereof is usually 0.01% by mass or more, preferably 0.1% by mass or more, and the upper limit thereof is usually 30% by mass or less, preferably 20% by mass or more, relative to the total mass of the electrolytic solution of the present invention Low, more preferably 10% by mass or less, more preferably 5% by mass or less.

In another example, an inorganic lithium salt and an organic lithium salt are used in combination. Such combinations have the effect of reducing deterioration caused by high temperature storage. The organic lithium salt is preferably CF ₃ SO ₃ Li, LiN(FSO ₂ ) ₂ , LiN(FSO ₂ )(CF ₃ SO ₂ ), LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , Cyclic lithium 1,2-perfluoroethanedisulfonyl imide, cyclic lithium 1,3-perfluoropropanedisulfonyl imide, LiC(FSO ₂ ) ₃ , LiC(CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) ₃ or the like. In this case, the proportion of the organolithium salt is preferably 0.1% by mass or more, especially preferably 0.5% by mass or more, while preferably 30% by mass or less, and especially preferably Preferably 20% by mass or less.

The electrolyte salt in the electrolyte solution may have any concentration that does not impair the effects of the present invention. In order to make the conductivity of the electrolyte solution within a favorable range and ensure good battery performance, the total molar concentration of lithium in the electrolyte solution is preferably 0.3 mol/L or higher, more preferably 0.4 mol/L or higher, and even more preferably 0.5 mol/L or higher, and preferably 3 mol/L or lower, more preferably 2.5 mol/L or lower, still more preferably 2.0 mol/L or lower.

Too low a total molar concentration of lithium can lead to insufficient conductivity of the electrolyte solution, while too high a concentration can lead to increased viscosity and subsequently reduced conductivity, impairing battery performance.

The electrolyte salt used in the electrolyte solution of the electric double layer capacitor is preferably an ammonium salt. Examples of the ammonium salt include the following salts (IIa) to (IIe). (IIa) Tetraalkyl quaternary ammonium salt Preferable examples thereof include tetraalkyl quaternary ammonium salts represented by the following formula (IIa):

（其中R ^1a、R ^2a、R ^3a及R ^4a彼此相同或不同，且各自為視情況含有醚鍵之C1-C6烷基；且X ^-為陰離子）。為了改良抗氧化性，銨鹽中之任何或所有氫原子亦較佳經氟原子及/或C1-C4含氟烷基置換。 [chemical formula 46]

(wherein R ^1a , R ^2a , R ^3a and R ^4a are the same or different from each other, and each is a C1-C6 alkyl group optionally containing an ether bond; and X ^- is an anion). In order to improve the oxidation resistance, any or all of the hydrogen atoms in the ammonium salt are also preferably replaced by fluorine atoms and/or C1-C4 fluorine-containing alkyl groups.

Preferred specific examples thereof include A tetraalkyl quaternary ammonium salt represented by the following formula (IIa-1):

（其中R ^1a、R ^2a及X ^-如上文所描述定義；x及y彼此相同或不同，且各自為0至4之整數，其中x+y=4），及 由下式(IIa-2)表示之含烷基醚基之三烷基銨鹽： [chemical formula 47]

(wherein R ^1a , R ^2a and X ^- are defined as described above; x and y are the same or different from each other, and each is an integer from 0 to 4, wherein x+y=4), and by the following formula (IIa-2) Trialkyl ammonium salts containing alkyl ether groups represented by:

（其中R ^5a為C1-C6烷基；R ^6a為C1-C6二價烴基；R ^7a為C1-C4烷基；z為1或2；且X ^-為陰離子）。引入烷基醚使得能夠降低黏度。 [chemical formula 48]

(wherein R ^5a is a C1-C6 alkyl group; R ^6a is a C1-C6 divalent hydrocarbon group; R ^7a is a C1-C4 alkyl group; z is 1 or 2; and X ^- is an anion). The introduction of alkyl ethers makes it possible to reduce the viscosity.

Anion X ^- can be an inorganic anion or an organic anion. Examples of inorganic anions include AlCl ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , TaF ₆ ⁻ , I ⁻ and SbF ₆ ⁻ . Examples of organic anions include bisoxalate borate anion, difluorooxalate borate anion, tetrafluorooxalate phosphate anion, difluorobisoxalate phosphate anion, CF ₃ COO ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ^- and (C ₂ F ₅ SO ₂ ) ₂ N ^- .

In order to achieve good oxidation resistance and ion dissociation, BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ and SbF ₆ ⁻ are preferred.

Preferred specific examples of tetraalkyl quaternary ammonium salts to be used include Et ₄ NBF ₄ , Et ₄ NClO ₄ , Et ₄ NPF ₆ , Et ₄ NAsF ₆ , Et ₄ NSbF ₆ , Et ₄ NCF ₃ SO ₃ , Et ₄ N(CF ₃ SO ₂ ) ₂ N, Et ₄ NC ₄ F ₉ SO ₃ , Et ₃ MeNBF ₄ , Et ₃ MeNClO ₄ , Et ₃ MeNPF ₆ , Et ₃ MeNAsF ₆ , Et ₃ MeNSbF ₆ , Et ₃ MeNCF ₃ SO ₃ , Et ₃ MeN(CF ₃ SO ₂ ) ₂ N and Et ₃ MeNC ₄ F ₉ SO ₃ . Specifically, Et ₄ NBF ₄ , Et ₄ NPF ₆ , Et ₄ NSbF ₆ , Et ₄ NAsF ₆ , Et ₃ MeNBF ₄ and N,N-diethyl-N-methyl-N-(2-methoxy Ethyl)ammonium salts may be mentioned as examples.

(IIb) Spirocyclic dipyrrolidinium salt Its preferred examples include A spirocyclic dipyrrolidinium salt represented by the following formula (IIb-1):

（其中R ^8a及R ^9a彼此相同或不同，且各自為C1-C4烷基；X ^-為陰離子；n1為0至5之整數；且n2為0至5之整數）， 由下式(IIb-2)表示之螺環二吡咯啶鎓鹽： [chemical formula 49]

(wherein R ^8a and R ^9a are the same or different from each other, and each is a C1-C4 alkyl; X ^- is an anion; n1 is an integer from 0 to 5; and n2 is an integer from 0 to 5), by the following formula (IIb- 2) Spiral dipyrrolidinium salt represented by:

（其中R ^10a及R ^11a彼此相同或不同，且各自為C1-C4烷基；X ^-為陰離子；n3為0至5之整數；且n4為0至5整數），及 由下式(IIb-3)表示之螺環二吡咯啶鎓鹽： [chemical formula 50]

(wherein R ^10a and R ^11a are the same or different from each other, and each is a C1-C4 alkyl; X ^- is an anion; n3 is an integer from 0 to 5; and n4 is an integer from 0 to 5), and by the following formula (IIb- 3) Spiral dipyrrolidinium salt represented by:

（其中R ^12a及R ^13a彼此相同或不同，且各自為C1-C4烷基；X ^-為陰離子；n5為0至5之整數；且n6為0至5整數）。為了改良抗氧化性，螺環二吡咯啶鎓鹽中之任何或所有氫原子亦較佳經氟原子及/或C1-C4含氟烷基置換。 [chemical formula 51]

(wherein R ^12a and R ^13a are the same or different from each other, and each is a C1-C4 alkyl group; X ^- is an anion; n5 is an integer from 0 to 5; and n6 is an integer from 0 to 5). In order to improve the oxidation resistance, any or all of the hydrogen atoms in the spirocyclic dipyrrolidinium salt are also preferably replaced by fluorine atoms and/or C1-C4 fluorine-containing alkyl groups.

Preferred specific examples of the anion X ^- are the same as those mentioned for the salt (IIa). In order to achieve good dissociation and low internal resistance at high voltage, preferred among these are BF ₄ ⁻ , PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ or (C ₂ F ₅ SO ₂ ) ₂ N ⁻ .

可作為螺環二吡咯啶鎓鹽之較佳特定實例提及。 For example, those represented by the following formula: [Chemical formula 52]

As preferred specific examples of spirocyclic dipyrrolidinium salts may be mentioned.

These spirocyclic dipyrrolidinium salts are excellent in solubility in solvents, oxidation resistance and ion conductivity.

(IIc) imidazolium salt Preferable examples thereof include imidazolium salts represented by the following formula (IIc):

其中R ^14a及R ^15a彼此相同或不同，且各自為C1-C6烷基；且X ^-為陰離子。 為了改良抗氧化性，咪唑鎓鹽中之任何或所有氫原子亦較佳經氟原子及/或C1-C4含氟烷基置換。 [chemical formula 53]

Wherein R ^14a and R ^15a are the same or different from each other, and each is a C1-C6 alkyl group; and X ^- is an anion. In order to improve the oxidation resistance, any or all of the hydrogen atoms in the imidazolium salt are also preferably replaced by fluorine atoms and/or C1-C4 fluorine-containing alkyl groups.

Preferred specific examples of the anion X ^- are the same as those mentioned for the salt (IIa).

For example, one of the following formulas:

可作為其較佳特定實例提及。 [chemical formula 54]

It can be mentioned as a preferred specific example thereof.

This imidazolium salt is excellent because of its low viscosity and good solubility.

(IId) N-Alkylpyridinium salts Preferable examples thereof include N-alkylpyridinium salts represented by the following formula (IId):

其中R ^16a為C1-C6烷基；且X ^-為陰離子。 為了改良抗氧化性，N-烷基吡啶鎓鹽中之任何或所有氫原子亦較佳經氟原子及/或C1-C4含氟烷基置換。 [chemical formula 55]

Wherein R ^16a is a C1-C6 alkyl group; and X ^- is an anion. In order to improve the oxidation resistance, any or all of the hydrogen atoms in the N-alkylpyridinium salt are also preferably replaced by fluorine atoms and/or C1-C4 fluorine-containing alkyl groups.

Preferred specific examples of the anion X ^- are the same as those mentioned for the salt (IIa).

For example, those represented by the following formulae:

， 可作為其較佳特定實例提及。 [chemical formula 56]

, can be mentioned as a preferred specific example thereof.

These N-alkylpyridinium salts are excellent because of their low viscosity and good solubility.

(IIe) N,N-dialkylpyrrolidinium salt Preferable examples thereof include N,N-dialkylpyrrolidinium salts represented by the following formula (IIe):

其中R ^17a及R ^18a彼此相同或不同，且各自為C1-C6烷基；且X ^-為陰離子。 為了改良抗氧化性，N,N-二烷基吡咯啶鎓鹽中之任何或所有氫原子亦較佳經氟原子及/或C1-C4含氟烷基置換。 [chemical formula 57]

Wherein R ^17a and R ^18a are the same or different from each other, and each is a C1-C6 alkyl group; and X ^- is an anion. In order to improve the oxidation resistance, any or all hydrogen atoms in the N,N-dialkylpyrrolidinium salt are also preferably replaced by fluorine atoms and/or C1-C4 fluorine-containing alkyl groups.

Preferred specific examples of the anion X ^- are the same as those mentioned for the salt (IIa).

For example, those represented by the following formulae:

， [chemical formula 58]

,

可作為其較佳特定實例提及。 [chemical formula 59]

It can be mentioned as a preferred specific example thereof.

These N,N-dialkylpyrrolidinium salts are excellent because of their low viscosity and good solubility.

Preferred among these ammonium salts are those represented by formula (IIa), (IIb) or (IIc) because they can have good solubility, oxidation resistance and ion conductivity. More preferably they are represented by the following formula:

其中Me為甲基；Et為乙基；且X ^-、x及y如式(IIa-1)中所定義。 [chemical formula 60]

wherein Me is methyl; Et is ethyl; and X ⁻ , x and y are as defined in formula (IIa-1).

Lithium salts can be used as electrolyte salts for electric double layer capacitors. Preferable examples thereof include LiPF ₆ , LiBF ₄ , LiN(FSO ₂ ) ₂ , LiAsF ₆ , LiSbF ₆ , and LiN(SO ₂ C ₂ H ₅ ) ₂ .

To further increase capacity, magnesium salts can be used. Preferable examples of magnesium salts include Mg(ClO ₄ ) ₂ and Mg(OOC ₂ H ₅ ) ₂ . Ammonium salts serving as electrolyte salts are preferably used at a concentration of 0.7 mol/L or higher. Ammonium salts at a concentration lower than 0.7 mol/L may not only lead to poor low-temperature characteristics, but also lead to high initial internal resistance. The concentration of electrolyte salt is more preferably 0.9 mol/L or higher. In order to provide good low-temperature characteristics, the upper limit of the concentration is preferably 2.0 mol/L or lower, more preferably 1.5 mol/L or lower. When the ammonium salt is triethyl methyl ammonium tetrafluoroborate (TEMABF ₄ ), the concentration is preferably 0.7 to 1.5 mol/L to provide excellent low temperature properties. When the ammonium salt is spirobipyrrolidinium tetrafluoroborate (SBPBF ₄ ), the concentration is preferably 0.7 to 2.0 mol/L.

（其中X ²¹為含有至少H或C之基團；n ²¹為1至3之整數；Y ²¹及Z ²¹彼此相同或不同，且各自為含有至少H、C、O或F之基團；n ²²為0或1；且Y ²¹及Z ²¹視情況彼此結合形成環）。含有化合物(4)之電解質溶液即使在高溫下儲存時亦可使得容量保持率之降低少得多，且可使得產生之氣體量增加少得多。 The electrolytic solution of the present invention preferably further contains a compound (4) represented by the following formula (4): [Chemical formula 61]

(wherein X ²¹ is a group containing at least H or C; n ²¹ is an integer from 1 to 3; Y ²¹ and Z ²¹ are the same or different from each other, and each is a group containing at least H, C, O or F; n ²² is 0 or 1; and Y ²¹ and Z ²¹ are optionally combined with each other to form a ring). The electrolytic solution containing compound (4) can cause much less decrease in capacity retention even when stored at high temperature, and can cause much less increase in gas generation.

When n ²¹ is 2 or 3, two or three X ²¹ may be the same or different from each other. When there are a plurality of Y ²¹ and a plurality of Z ²¹ , the plurality of Y ²¹ may be the same as or different from each other and the plurality of Z ²¹ may be the same or different from each other.

X ²¹ is preferably a group represented by -CY ²¹ Z ²¹ - (wherein Y ²¹ and Z ²¹ are defined as described above), or a group represented by -CY ²¹ ═CZ ²¹ - (wherein Y ²¹ and Z ²¹ are as described above Definition) represents the group.

Y ²¹ preferably includes at least one selected from the group consisting of H-, F-, CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, CF ₃ -, CF ₃ CF ₂ - , CH ₂ FCH ₂ - and CF ₃ CF ₂ CF ₂ -. Z ²¹ preferably includes at least one selected from the group consisting of H-, F-, CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, CF ₃ -, CF ₃ CF ₂ - , CH ₂ FCH ₂ - and CF ₃ CF ₂ CF ₂ -.

Alternatively, Y ²¹ and Z ²¹ may combine with each other to form a carbocyclic or heterocyclic ring, which may contain unsaturated bonds and may have aromaticity. The carbon number of the ring is preferably 3-20.

Next, specific examples of compound (4) are described. In the following examples, the term "analog" means an acid anhydride obtainable by substituting a part of the structure of an acid anhydride mentioned as an example with another structure within the scope of the present invention. Examples thereof include dimers, trimers, and tetramers each composed of a plurality of acid anhydrides, structural isomers such as structural isomers having substituents having the same number of carbon atoms but also having branches, and substituents and anhydrides Structural isomers with different binding sites.

Specific examples of acid anhydrides having a 5-membered ring structure include succinic anhydride, methylsuccinic anhydride (4-methylsuccinic anhydride), dimethylsuccinic anhydride (such as 4,4-dimethylsuccinic anhydride, 4,5-dimethylsuccinic anhydride), 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4, 5-divinylsuccinic anhydride, phenylsuccinic anhydride (4-phenylsuccinic anhydride), 4,5-diphenylsuccinic anhydride, 4,4-diphenylsuccinic anhydride, citraconic anhydride, Maleic anhydride, methylmaleic anhydride (4-methylmaleic anhydride), 4,5-dimethylmaleic anhydride, phenylmaleic anhydride (4-phenyl maleic anhydride), 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methyl itaconic anhydride, 5,5-dimethyl itaconic anhydride, phthalic anhydride and 3 , 4,5,6-tetrahydrophthalic anhydride and its analogues.

Specific examples of acid anhydrides having a 6-membered ring structure include cyclohexanedicarboxylic anhydride (such as cyclohexane-1,2-dicarboxylic anhydride), 4-cyclohexene-1,2-dicarboxylic anhydride, glutaric anhydride , glutaric anhydride and 2-phenylglutaric anhydride and their analogs.

烯-2,3-二甲酸酐、環戊烷四甲酸二酐、焦蜜石酸酐及二乙醇酸酐及其類似物。Specific examples of anhydrides with different ring structures include 5-nor

ene-2,3-dicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, pyromelite anhydride, diglycolic anhydride and the like.

Specific examples of acid anhydrides having a ring structure and substituted with a halogen atom include monofluorosuccinic anhydride (such as 4-fluorosuccinic anhydride), 4,4-difluorosuccinic anhydride, 4,5-difluorosuccinic anhydride, 4,4,5-trifluorosuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride (4,4,5,5-tetrafluorosuccinic anhydride), 4-fluoromaleic anhydride, 4,5-difluoromaleic anhydride, trifluoromethylmaleic anhydride, 5-fluoroiconic anhydride and 5,5-difluoroiconic anhydride and their analogs.

烯-2,3-二甲酸酐、苯基丁二酸酐、2-苯基戊二酸酐、順丁烯二酸酐、甲基順丁烯二酸酐、三氟甲基順丁烯二酸酐、苯基順丁烯二酸酐、丁二酸酐、甲基丁二酸酐、二甲基丁二酸酐、三氟甲基丁二酸酐、單氟丁二酸酐及四氟丁二酸酐。更佳為順丁烯二酸酐、甲基順丁烯二酸酐、三氟甲基順丁烯二酸酐、丁二酸酐、甲基丁二酸酐、三氟甲基丁二酸酐及四氟丁二酸酐，且再更佳為順丁烯二酸酐及丁二酸酐。Among these, preferred compounds (4) are glutaric 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-nor

ene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, phenyl Maleic anhydride, succinic anhydride, methylsuccinic anhydride, dimethylsuccinic anhydride, trifluoromethylsuccinic anhydride, monofluorosuccinic anhydride, and tetrafluorosuccinic anhydride. More preferred are maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, trifluoromethylsuccinic anhydride and tetrafluorosuccinic anhydride , and more preferably maleic anhydride and succinic anhydride.

Compound (4) preferably includes at least one member selected from the group consisting of compound (5-1) represented by the following formula (5-1):

（其中X ³¹至X ³⁴彼此相同或不同，且各自為含有至少H、C、O或F之基團）；及由下式(5-2)表示之化合物(5-2)： [chemical formula 62]

(wherein X ³¹ to X ³⁴ are the same or different from each other, and each is a group containing at least H, C, O or F); and a compound (5-2) represented by the following formula (5-2):

（其中X ⁴¹及X ⁴²彼此相同或不同，且各自為含有至少H、C、O或F之基團）。 [chemical formula 63]

(wherein X ⁴¹ and X ⁴² are the same or different from each other, and each is a group containing at least H, C, O or F).

X ³¹ to X ³⁴ are the same or different from each other, and preferably include at least one member selected from the group consisting of alkyl, fluorinated alkyl, alkenyl and fluorinated alkenyl. The carbon number of each of X ³¹ to X ³⁴ is preferably 1-10, more preferably 1-3.

X ³¹ to X ³⁴ are the same or different from each other, and preferably include at least one selected from the group consisting of H-, F-, CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, CF ₃ -, CF ₃ CF ₂ -, CH ₂ FCH ₂ -, and CF ₃ CF ₂ CF ₂ -.

X ⁴¹ and X ⁴² are the same or different from each other, and preferably include at least one selected from the group consisting of alkyl, fluorinated alkyl, alkenyl and fluorinated alkenyl. The carbon number of each of X ⁴¹ and X ⁴² is preferably 1-10, more preferably 1-3.

X ⁴¹ and X ⁴² are the same or different from each other, and preferably include at least one selected from the group consisting of H-, F-, CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, CF ₃ -, CF ₃ CF ₂ -, CH ₂ FCH ₂ -, and CF ₃ CF ₂ CF ₂ -.

Compound (5-1) is preferably any one of the following compounds.

[chemical formula 64]

Compound (5-2) is preferably any one of the following compounds.

[chemical formula 65]

In order to have much less decrease in capacity retention and much less increase in gas generation even when stored at high temperature, the electrolyte solution preferably contains 0.0001 to 15% by mass of the compound (4) relative to the electrolyte solution. The amount of compound (4) is more preferably 0.01 to 10 mass%, still more preferably 0.1 to 3 mass%, especially preferably 0.1 to 1.0 mass%.

In order to cause much less decrease in capacity retention rate and much less increase in gas generation even when stored at high temperature, the electrolyte solution containing both compounds (5-1) and (5-2) When preferably containing 0.08 to 2.50 mass % of compound (5-1) and 0.02 to 1.50 mass % of compound (5-2), more preferably 0.80 to 2.50 mass % of compound (5-1) and 0.08 to 1.50 mass % Compound (5-2).

（其中R ^a及R ^b各自獨立地為氫原子、氰基（CN）、鹵素原子、烷基或可藉由用鹵素原子置換烷基之至少一個氫原子而獲得的基團；且n為1至10之整數）； [化學式67]

（其中R ^c為氫原子、鹵素原子、烷基、可藉由用鹵素原子置換烷基之至少一個氫原子而獲得的基團，或由NC-R ^c1-X ^c1-（其中R ^c1為伸烷基，X ^c1為氧原子或硫原子）表示之基團；R ^d及R ^e各自獨立地為氫原子、鹵素原子、烷基或可藉由用鹵素原子置換烷基之至少一個氫原子而獲得的基團；且m為1至10之整數）； [化學式68]

（其中R ^f、R ^g、R ^h及R ⁱ各自獨立地為含有氰基（CN）之基團、氫原子（H）、鹵素原子、烷基或可藉由用鹵素原子置換烷基之至少一個氫原子而獲得的基團；選自由R ^f、R ^g、R ^h及R ⁱ組成之群中之至少一者為含有氰基之基團；且l為1至3之整數）。 此可改良電化學裝置之高溫儲存特性。可單獨使用一種腈化合物，或可以任何比率以任何組合使用其中之兩者或更多者。 The electrolytic solution of the present invention may contain at least one member selected from the group consisting of compounds represented by the following formulas (1a), (1b) and (1c): [Chemical formula 66]

(where R ^a and R ^b are each independently a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom; and n is 1 to an integer of 10); [chemical formula 67]

(wherein R ^c is a hydrogen atom, a halogen atom, an alkyl group, a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom, or by NC-R ^c1 -X ^c1 - (wherein R ^c1 is an extended Alkyl, X ^c1 is a group represented by an oxygen atom or a sulfur atom); R ^d and R ^e are each independently a hydrogen atom, a halogen atom, an alkyl group, or can be formed by replacing at least one hydrogen atom of the alkyl group with a halogen atom. obtained group; and m is an integer of 1 to 10); [chemical formula 68]

(Wherein R ^f , R ^g , Rh and R ⁱ are each independently a group containing cyano ( ^CN ), hydrogen atom (H), halogen atom, alkyl or at least a hydrogen atom; at least one selected from the group consisting of R ^f , R ^g , ^Rh and R ⁱ is a group containing a cyano group; and l is an integer of 1 to 3). This can improve the high temperature storage characteristics of the electrochemical device. One nitrile compound may be used alone, or two or more of them may be used in any ratio in any combination.

In formula (1a), R ^a and R ^b are each independently a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom . Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Preferred among these is a fluorine atom. The alkyl group is preferably a C1-C5 alkyl group. Specific examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl. Examples of groups obtainable by substituting at least one hydrogen atom of an alkyl group with a halogen atom are groups obtainable by substituting at least one hydrogen atom of the aforementioned alkyl group with the aforementioned halogen atom. When R ^a and R ^b are an alkyl group or a group each obtainable by replacing at least one hydrogen atom of the alkyl group with a halogen atom, R ^a and R ^b may be combined with each other to form a ring structure (such as a cyclohexane ring ). Each of R ^a and R ^b is preferably a hydrogen atom or an alkyl group.

In formula (1a), n is an integer of 1 to 10. When n is 2 or more, all n R ^a may be identical to each other, or at least a part thereof may be different from others. The same applies to R ^b . In the formula, n is preferably an integer of 1-7, more preferably an integer of 2-5.

Preferred as the nitrile compound represented by the formula (1a) are dinitrile and tricarbonitrile. Specific examples of dinitriles include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, dodecanedinitrile, Methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tertiary butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethyl Dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylbutanedinitrile Nitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, dicyclohexyl-1,1-dicarbonitrile, dicyclohexyl-2,2-dicarbonitrile, dicyclohexyl-3 ,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diiso Butyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3, 3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile Glutaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanoctane, 2,8-dicyanononane, 1,6-dicyano Decane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3, 3'-(Ethyldithio)dipropionitrile, 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, Nitrile and phthalonitrile. Especially preferred among these are succinonitrile, glutaronitrile and adiponitrile. Specific examples of tricarbonitrile include pentatricarbonitrile, propanetricarbonitrile, 1,3,5-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, heptanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1, 3,5-pentanetricarbonitrile, cyclohexanetricarbonitrile, tricyanoethylamine, tricyanoethoxypropane, tricyanoethylene, and tris(2-cyanoethyl)amine. Especially preferred are 1,3,6-hexanetricarbonitrile and cyclohexanetricarbonitrile, most preferably cyclohexanetricarbonitrile.

In formula (1b), R ^c is a hydrogen atom, a halogen atom, an alkyl group, a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom, or a group obtained by NC-R ^c1 -X ^c1 -( wherein R ^c1 is an alkylene group; and X ^c1 is a group represented by an oxygen atom or a sulfur atom); R ^d and R ^e are each independently a hydrogen atom, a halogen atom, an alkyl group or an alkyl group that can be replaced by a halogen atom A group derived from at least one hydrogen atom. Examples of the halogen atom, the alkyl group, and the group obtainable by replacing at least one hydrogen atom of the alkyl group with a halogen atom include those mentioned for formula (1a) as examples thereof. R ^c1 in NC-R ^c1 -X ^c1 - is an alkylene group. The alkylene group is preferably a C1-C3 alkylene group. Each of R ^c , R ^d and ^Re is preferably independently a hydrogen atom, a halogen atom, an alkyl group, or a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom. At least one selected from R ^c , R ^d and ^Re is preferably a halogen atom or a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom, more preferably a fluorine atom or a group obtainable by using A group obtained by replacing at least one hydrogen atom of an alkyl group with a fluorine atom. When R ^d and R ^e are each an alkyl group or a group obtainable by replacing at least one hydrogen atom of an alkyl group with a halogen atom, R ^d and R ^e may be combined with each other to form a ring structure (such as a cyclohexane ring ).

In formula (1b), m is an integer of 1 to 10. When m is 2 or more, all m pieces of R ^d may be identical to each other, or at least a part thereof may be different from others. The same applies to R ^e . In the formula, m is preferably an integer of 2-7, more preferably an integer of 2-5.

Examples of the nitrile compound represented by the formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, tris Methylacetonitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile , 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile , 3,3'-thiodipropionitrile, pentafluoropropionitrile, methoxyacetonitrile and benzonitrile. Especially preferred among these is 3,3,3-trifluoropropionitrile.

In formula (1c), R ^f , R ^g , Rh and R ⁱ are each independently a group containing a cyano group ( ^CN ), a hydrogen atom, a halogen atom, an alkyl group, or an alkyl group that can be replaced by a halogen atom. A group derived from at least one hydrogen atom. Examples of the halogen atom, the alkyl group, and the group obtainable by replacing at least one hydrogen atom of the alkyl group with a halogen atom include those mentioned for formula (1a) as examples thereof. Examples of the group containing a cyano group include a cyano group and a group obtainable by replacing at least one hydrogen atom of an alkyl group with a cyano group. Examples of the alkyl group in this case include those mentioned as examples of the formula (1a). At least one selected from R ^f , R ^g , ^Rh and R ⁱ is a group containing a cyano group. Preferably, each of at least two selected from R ^f , R ^g , ^Rh and R ⁱ is a group containing a cyano group. More preferably, each of R ^h and R ⁱ is a group containing a cyano group. When R ^h and R ⁱ are each a group containing a cyano group, R ^f and R ^g are preferably a hydrogen atom.

In formula (1c), l is an integer of 1 to 3. When 1 is 2 or more, all 1 of ^Rf may be the same as each other, or at least a part thereof may be different from others. The same applies to R ^g . In this formula, l is preferably an integer of 1 or 2.

Examples of the nitrile compound represented by the formula (1c) include 3-hexenedinitrile, hexadiene dinitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3- Methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, and 2-hexenenitrile. Preferred are 3-hexenedinitrile and hexenedinitrile, especially preferred is 3-hexenedinitrile.

The nitrile compound is preferably present in an amount of 0.2 to 7% by mass relative to the electrolytic solution. This can further improve the high temperature storage characteristics and safety of the electrochemical device under high voltage. The lower limit of the total amount of nitrile compounds is more preferably 0.3% by mass, still more preferably 0.5% by mass. The upper limit thereof is more preferably 5% by mass, still more preferably 2% by mass, especially preferably 0.5% by mass.

The electrolytic solution of the present invention may contain an isocyanate group-containing compound (hereinafter also abbreviated as "isocyanate"). The isocyanate used may be any isocyanate. Examples of isocyanates include monoisocyanates, diisocyanates and triisocyanates.

Specific examples of monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanate Hexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, isocyanatocyclohexane, methoxy Carbonyl isocyanate, ethoxycarbonyl isocyanate, propoxycarbonyl isocyanate, butoxycarbonyl isocyanate, methoxysulfonyl isocyanate, ethoxysulfonyl isocyanate, propoxysulfonyl isocyanate, butoxysulfonyl isocyanate, fluorosulfonyl Isocyanate, methyl isocyanate, butyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, and ethyl isocyanate.

Specific examples of diisocyanates include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanate Heptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropene , 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane , 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1, 6-Diisocyanato-3-hexene, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, diiso Cresyl cyanate, xylyl diisocyanate, methylene diisocyanate, 1,2-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl) base) cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1 ,4-Diisocyanatocyclohexane, dicyclohexylmethane-1,1'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate , dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, bicyclo[2.2.1]heptane-2,5-diylbis(methyl=isocyanate), bicyclo[2.2.1] Heptane-2,6-diylbis(methyl=isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate Methyl ester, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, octamethylene diisocyanate and tetramethylene diisocyanate.

-2,4,6(1H,3H,5H)-三酮及4-(異氰酸基甲基)八亞甲基=二異氰酸酯。Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-triisocyanatoundecane Isocyanatomethylbenzene, 1,3,5-tris(6-isocyanatohex-1-yl)-1,3,5-tris

-2,4,6(1H,3H,5H)-trione and 4-(isocyanatomethyl)octamethylene=diisocyanate.

-2,4,6(1H,3H,5H)-三酮、二異氰酸2,4,4-三甲基六亞甲酯及二異氰酸2,2,4-三甲基六亞甲酯。自技術視角來看，其可促進穩定膜狀結構之形成且因此可更適合地使用。Preferred among these are 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, and Hexane, 1,3,5-paraffin(6-isocyanatohex-1-yl)-1,3,5-tri

-2,4,6(1H,3H,5H)-trione, 2,4,4-trimethylhexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate methyl ester. From a technical point of view, it can promote the formation of stable membranous structures and can therefore be used more suitably.

The isocyanate may be present in any amount that does not significantly impair the effectiveness of the present invention. The amount is preferably, but not limited to, 0.001% by mass or more and 1.0% by mass or less relative to the electrolytic solution. The isocyanate in an amount not less than this lower limit can provide a non-aqueous electrolyte secondary battery with a sufficient effect of improving cycle characteristics. The isocyanate in an amount not greater than the upper limit can eliminate the initial increase in resistance of the nonaqueous electrolyte secondary battery. The amount of isocyanate is more preferably 0.01 mass % or more, still more preferably 0.1 mass % or more, especially preferably 0.2 mass % or more, and more preferably 0.8 mass % or less, still more preferably 0.7 mass % or Lower, especially preferably 0.6% by mass or lower.

The electrolytic solution of the present invention may contain a cyclic sulfonate. The cyclic sulfonate can be any cyclic sulfonate. Examples of cyclic sulfonate include saturated cyclic sulfonate, unsaturated cyclic sulfonate, saturated cyclic disulfonate and unsaturated cyclic disulfonate.

Specific examples of saturated cyclic sulfonate esters include 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3- Fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone, 2-methyl-1,3-propane sultone, 3-methyl-1,3 -Propane sultone, 1,3-butane sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2- Methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone and 2,4-butanesulfonic acid Lactone.

Specific examples of unsaturated cyclic sulfonates include 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone , 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2 -Fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2- Methyl-1-propene-1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2 -Methyl-2-propene-1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene -1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1, 4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-fluoro-2-butene-1 ,4-sultone, 2-fluoro-2-butene-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene- 1,4-sultone, 1,3-propene sultone, 1-fluoro-3-butene-1,4-sultone, 2-fluoro-3-butene-1,4-sultone , 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1-methyl-1-butene-1,4-sulfone Lactone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1 ,4-sultone, 1-methyl-2-butene-1,4-sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2- Butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3-butene-1,4-sultone, 2-methyl 3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone and 4-methyl-3-butene-14-sultone.

In terms of easy availability and in order to facilitate the formation of a stable film-like structure, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro- 1,3-propane sultone, 3-fluoro-1,3-propane sultone and 1-propene-1,3-sultone. The cyclic sulfonate may be present in any amount that does not significantly impair the effect of the present invention. The amount is preferably, but not limited to, 0.001% by mass or more and 3.0% by mass or less relative to the electrolytic solution.

The cyclic sulfonic acid ester in an amount not less than this lower limit can provide a sufficient effect of improving cycle characteristics to a nonaqueous electrolyte secondary battery. The cyclic sulfonate ester in an amount not greater than this upper limit can eliminate an increase in the cost of producing a nonaqueous electrolyte secondary battery. The amount of cyclic sulfonic acid ester is more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, especially preferably 0.2% by mass or more, and more preferably 2.5% by mass or less, still more preferably 2.0% by mass or less, especially preferably 1.8% by mass or less.

The electrolytic solution of the present invention may further contain polyethylene oxide having a weight average molecular weight of 2000 to 4000 and having -OH, -OCOOH or -COOH at one end. The presence of such compounds can improve the stability at the interface with the respective electrodes, thereby improving the characteristics of the electrochemical device. Examples of polyethylene oxide include polyethylene oxide monoalcohol, polyethylene oxide carboxylate, polyethylene oxide diol, polyethylene oxide dicarboxylate, polyethylene oxide triol, and polyethylene oxide tricarboxylate. One of these may be used alone, or two or more of them may be used in combination. In order to provide better properties of the electrochemical device, a mixture of polyethylene oxide monoalcohol and polyethylene oxide glycol and a mixture of polyethylene carboxylate and polyethylene dicarboxylate are preferred.

Polyethylene oxide with an excessively small weight average molecular weight can be easily oxidized and decomposed. The weight average molecular weight is more preferably 3,000 to 4,000. The weight average molecular weight can be measured in terms of polystyrene equivalent by gel permeation chromatography (GPC).

Polyethylene oxide is preferably present in the electrolyte solution in an amount of 1×10 ^-6 to 1×10 ^-2 mol/kg. An excessively large amount of polyethylene oxide may result in poor characteristics of the electrochemical device. The amount of polyethylene oxide is more preferably 5 x 10 ^-6 mol/kg or higher.

The electrolytic solution of the present invention may further contain any one of other components such as fluorinated saturated cyclic carbonate, unsaturated cyclic carbonate, overcharge inhibitor, and known various additives as an additive. This can reduce damage to the properties of the electrochemical device.

𠷬-2-酮）。可單獨使用一種氟化飽和環狀碳酸酯，或可以任何比率以任何組合使用其中之兩者或更多者。Examples of the fluorinated saturated cyclic carbonate include compounds represented by the aforementioned formula (A). Preferred among these are fluoroethylene carbonate, difluoroethyl carbonate, monofluoromethyl ethyl carbonate, trifluoromethyl ethyl carbonate, 2,2,3,3,3-pentacarbonate Fluoropropylethylidene (4-(2,2,3,3,3-pentafluoro-propyl)-[1,3]di

𠷬-2-one). One kind of fluorinated saturated cyclic carbonate may be used alone, or two or more thereof may be used in any ratio in any combination.

The fluorinated saturated cyclic carbonate is preferably present in an amount of 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, still more preferably 0.1 to 3% by mass relative to the electrolyte solution.

Examples of unsaturated cyclic carbonates include vinylene carbonate compounds; ethylene carbonate compounds substituted with substituents containing aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds; phenyl carbonate compounds; vinylene carbonate compounds compounds; allyl carbonate compounds; and catechol carbonate compounds.

Examples of vinylene carbonate compounds include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, carbonic acid Vinyl vinylene ester, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, 4-fluorovinyl carbonate, 4-fluoro-5-carbonate Methyl vinylene ester, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, ethynyl ethylene carbonate, propargyl ethyl carbonate, methyl vinyl carbonate and dimethyl vinyl carbonate.

𠷬-2-酮、4,5-二亞甲基-1,3-二

𠷬-2-酮及碳酸4-甲基-5-烯丙基伸乙酯。Specific examples of ethylene carbonate compounds substituted with substituents containing aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4- Methyl-5-vinylethylene, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynyl carbonate Ethyl carbonate, 4-vinyl-5-ethynyl ethyl carbonate, 4-allyl-5-ethynyl ethyl carbonate, phenyl ethyl carbonate, 4,5-diphenyl ethyl carbonate, 4 -Phenyl-5-vinylethylene, 4-allyl-5-phenylethylene carbonate, allylethylcarbonate, 4,5-diallylethylcarbonate, 4-methyl-carbonate 5-allylethylene ester, 4-methylene-1,3-bis

𠷬-2-one, 4,5-dimethylene-1,3-di

𠷬-2-one and 4-methyl-5-allylethylcarbonate.

The unsaturated cyclic carbonate is preferably vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, carbonic acid Allyl vinylene ester, 4,5-diallyl vinylene carbonate, vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, vinylene carbonate Propyl ethylene, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate , 4,5-diethynyl ethyl carbonate, 4-methyl-5-ethynyl ethyl carbonate and 4-vinyl-5-ethynyl ethyl carbonate. In order to form a more stable interface protective film, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are particularly preferred, and vinylene carbonate is most preferable.

The unsaturated cyclic carbonate may have any molecular weight that does not significantly impair the effects of the present invention. The molecular weight is preferably 50 or higher and 250 or lower. An unsaturated cyclic carbonate having a molecular weight within this range can easily secure its solubility in an electrolytic solution, and can easily cause sufficient achievement of the effects of the present invention. The molecular weight of the unsaturated cyclic carbonate is more preferably 80 or higher and 150 or lower.

The unsaturated cyclic carbonate can be produced by any production method, and can be produced by an appropriately selected known method.

One kind of unsaturated cyclic carbonate may be used alone, or two or more thereof may be used in any ratio in any combination.

The unsaturated cyclic carbonate may be present in any amount that does not significantly impair the effects of the present invention. The amount of the unsaturated cyclic carbonate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, based on 100% by mass of the electrolytic solution. The amount is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less. The unsaturated cyclic carbonate in an amount within the above range allows an electrochemical device containing an electrolytic solution to easily exhibit a sufficient effect of improving cycle characteristics, and can easily avoid impairment of high-temperature storage characteristics, generation of a large amount of gas, and discharge capacity retention rate reduction.

In addition to the aforementioned non-fluorinated unsaturated cyclic carbonates, fluorinated unsaturated cyclic carbonates can also be suitably used as the unsaturated cyclic carbonates. Fluorinated unsaturated cyclic carbonates are cyclic carbonates containing unsaturated bonds and fluorine atoms. The number of fluorine atoms in the fluorinated unsaturated cyclic carbonate may be any number from 1 or greater. The number of fluorine atoms is usually 6 or less, preferably 4 or less, most preferably 1 or 2.

Examples of fluorinated unsaturated cyclic carbonates include fluorinated vinylene carbonate derivatives and fluorinated ethylene carbonate derivatives substituted with substituents containing aromatic rings or carbon-carbon double bonds.

Examples of fluorinated vinylene carbonate derivatives include 4-fluorovinyl carbonate, 4-fluoro-5-methylvinyl carbonate, 4-fluoro-5-phenylvinyl carbonate, 4-allyl -5-fluorovinyl ester and 4-fluoro-5-vinyl vinyl carbonate.

Examples of fluorinated ethyl carbonate derivatives substituted with substituents containing aromatic rings or carbon-carbon double bonds include 4-fluoro-4-vinyl ethyl carbonate, 4-fluoro-4-allyl ethyl carbonate , 4-fluoro-5-vinyl ethyl carbonate, 4-fluoro-5-allyl ethyl carbonate, 4,4-difluoro-4-vinyl ethyl carbonate, 4,4-difluoro-4 - Allyl ethylene ester, 4,5-difluoro-4-vinyl ethylene carbonate, 4,5-difluoro-4-allyl ethylene carbonate, 4-fluoro-4,5-divinyl ethylene carbonate Ethyl ester, 4-fluoro-4,5-diallyl ethyl carbonate, 4,5-difluoro-4,5-divinyl ethyl carbonate, 4,5-difluoro-4,5- Diallylethylene, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate and 4,5 -Difluoro-4-phenylethylidene.

In order to form a stable interface protective film, it is better to use fluorinated unsaturated cyclic carbonate as 4-fluorovinyl carbonate, 4-fluoro-5-methylvinyl carbonate, 4-fluoro-5-carbonic acid Vinyl vinylene ester, 4-allyl-5-fluorovinyl carbonate, 4-fluoro-4-vinyl ethyl carbonate, 4-fluoro-4-allyl ethyl carbonate, 4-fluoro-5 carbonate -vinyl ethylene, 4-fluoro-5-allyl ethyl carbonate, 4,4-difluoro-4-vinyl ethyl carbonate, 4,4-difluoro-4-allyl ethyl carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluorocarbonate -4,5-diallyl ethylene, 4,5-difluoro-4,5-diallyl ethyl carbonate and 4,5-difluoro-4,5-diallyl ethyl carbonate.

The fluorinated unsaturated cyclic carbonate may have any molecular weight that does not significantly impair the effect of the present invention. The molecular weight is preferably 50 or higher and 500 or lower. A fluorinated unsaturated cyclic carbonate having a molecular weight within this range can easily ensure the solubility of the fluorinated unsaturated cyclic carbonate in an electrolytic solution.

Fluorinated unsaturated cyclic carbonates can be produced by any method, and can be produced by any known method appropriately selected. The molecular weight is more preferably 100 or higher and 200 or lower.

One fluorinated unsaturated cyclic carbonate may be used alone, or two or more thereof may be used in any ratio in any combination. Any amount of fluorinated unsaturated cyclic carbonate may be contained that does not significantly impair the effect of the present invention. The amount of the fluorinated unsaturated cyclic carbonate is usually preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, and preferably at the same time 5% by mass or less, more preferably 4% by mass or less, more preferably 3% by mass or less. The fluorinated unsaturated cyclic carbonate in an amount within this range enables an electrochemical device containing an electrolytic solution to exhibit the effect of sufficiently improving cycle characteristics, and can easily avoid deterioration of high-temperature storage characteristics, generation of a large amount of gas, and discharge capacity retention rate reduced situation.

The electrolyte solution of the present invention may contain a triple bond-containing compound. This compound may be of any type as long as it contains one or more triple bonds in the molecule. Specific examples of compounds containing triple bonds include the following compounds: Hydrocarbon compounds such as 1-pentyne, 2-pentyne, 1-hexyne, 2-hexyne, 3-hexyne, 1-heptyne, 2-heptyne, 3-heptyne, 1-octyne, 2- -octyne, 3-octyne, 4-octyne, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-dodedecyne, 2-dodecayne, 3-dodecyne Alkyne, 4-dodecyne, 5-dodecyne, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butyne, 4-benzene Base-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentyne, 5-phenyl-1-pentyne, 1-phenyl-1-hexyne, 6-benzene Base-1-hexyne, diphenylacetylene, 4-ethynyltoluene and dicyclohexylacetylene;

Monocarbonates such as 2-propynyl methyl carbonate, 2-propynyl ethyl carbonate, 2-propynyl propyl carbonate, 2-propynyl butyl carbonate, 2-propynylphenyl carbonate, 2-propynylcyclohexyl carbonate, di-2-propynyl carbonate, 1-methyl-2-propynyl methyl carbonate, 1,1-dimethyl-2-propynyl methyl carbonate , 2-butynyl methyl carbonate, 3-butynyl methyl carbonate, 2-pentynyl methyl carbonate, 3-pentynyl methyl carbonate and 4-pentynyl methyl carbonate; dicarbonates, Such as 2-butyne-1,4-diol dimethyl carbonate, 2-butyne-1,4-diol diethyl carbonate, 2-butyne-1,4-diol dipropylene carbonate Esters, 2-butyne-1,4-diol dibutyl dicarbonate, 2-butyne-1,4-diol diphenyl carbonate and 2-butyne-1,4-diol dicarbonate cyclohexyl ester;

Monocarboxylates such as 2-propynyl acetate, 2-propynyl propionate, 2-propynyl butyrate, 2-propynyl benzoate, 2-propynyl cyclohexylcarboxylate, 1,1-acetate -Dimethyl-2-propynyl ester, 1,1-dimethyl-2-propynyl propionate, 1,1-dimethyl-2-propynyl butyrate, 1,1-dibenzoate Methyl-2-propynyl ester, 1,1-dimethyl-2-propynyl cyclohexyl carboxylate, 2-butynyl acetate, 3-butynyl acetate, 2-pentynyl acetate, 3- Pentynyl Acrylate, 4-Pentynyl Acrylate, Methyl Acrylate, Ethyl Acrylate, Propyl Acrylate, Vinyl Acrylate, 2-Propyl Acrylate, 2-Butenyl Acrylate, 3-Butenyl Acrylate, Methacrylic Acid Methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl methacrylate, 2-propenyl methacrylate, 2-butenyl methacrylate, 3-butenyl methacrylate, 2-propene Methyl alkynoate, ethyl 2-propiolate, propyl 2-propiolate, vinyl 2-propiolate, 2-propenyl 2-propiolate, 2-butenyl 2-propiolate, 2-propiolate 3-butenyl ester, 2-butynoate methyl ester, 2-butynoate ethyl ester, 2-butynoate propyl ester, 2-butynoate vinyl ester, 2-butynoate 2- Acrylate, 2-butynoate 2-butenyl ester, 2-butynoate 3-butenyl ester, 3-butynoate methyl ester, 3-butynoate ethyl ester, 3-butynoate propyl ester, 3 -Vinyl butynoate, 2-propenyl 3-butynoate, 2-butenyl 3-butynoate, 3-butenyl 3-butynoate, methyl 2-pentynoate, 2-pentynoate Ethyl ynoate, Propyl 2-Pentynoate, Vinyl 2-Pentynoate, 2-Propyl 2-Pentynoate, 2-Butenyl 2-Pentynoate, 3-Butylate 2-Pentynoate Enyl ester, 3-pentynoic acid methyl ester, 3-pentynoic acid ethyl ester, 3-pentynoic acid propyl ester, 3-pentynoic acid vinyl ester, 3-pentynoic acid 2-propenyl ester, 3-pentynoic acid 2-butenyl ester, 3-pentynoic acid 3-butenyl ester, 4-pentynoic acid methyl ester, 4-pentynoic acid ethyl ester, 4-pentynoic acid propyl ester, 4-pentynoic acid vinyl ester, 4 - 2-propenyl pentynoate, 2-butenyl 4-pentynoate and 3-butenyl 4-pentynoate, fumarate, methyl trimethylacetate and ethyl trimethylacetate base ester;

噻𠷬-2-氧化物（1,2-環己烷二醇，乙酸2,2-二氧化物-1,2-

噻𠷬-4-基酯及乙酸2,2-二氧化物-1,2-

噻𠷬-4-基酯；Dicarboxylates such as 2-butyne-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol diol Butyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne-1,4-diol dicyclohexane carboxylate, hexahydrobenzo[1,3,2 ]two

Thiothiol-2-oxide (1,2-cyclohexanediol, acetic acid 2,2-dioxide-1,2-

Thiothiol-4-yl ester and 2,2-dioxide-1,2-acetate

Thiothiol-4-yl ester;

Diesters of oxalates such as methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, propyl 2-propynyl oxalate, vinyl 2-propynyl oxalate, allyl 2-propynyl oxalate , Di-2-propynyl oxalate, 2-butynyl methyl oxalate, 2-butynyl ethyl oxalate, 2-butynyl propyl oxalate, 2-butynyl vinyl oxalate, 2- Allyl butynyl oxalate, Di-2-butynyl oxalate, Methyl 3-butynyl oxalate, Ethyl 3-butynyl oxalate, Propyl 3-butynyl oxalate, 3-Butynyl oxalate Vinyl oxalate, allyl 3-butynyl oxalate and di-3-butynyl oxalate;

Phosphine oxides, such as methyl(2-propynyl)(vinyl)phosphine oxide, divinyl(2-propynyl)phosphine oxide, bis(2-propynyl)(vinyl)phosphine oxide Bis(2-propenyl)2(-propynyl)phosphine oxide, bis(2-propynyl)(2-propenyl)phosphine oxide, bis(3-butenyl)(2-propenyl) Alkynyl)phosphine oxide and bis(2-propynyl)(3-butenyl)phosphine oxide;

Phosphonites, such as 2-propynyl methyl(2-propenyl)phosphinate, 2-propynyl 2-butenyl(methyl)phosphonite, bis(2-propenyl)phosphinate 2-propynyl acid, 2-propynyl bis(3-butenyl)phosphonite, 1,1-dimethyl-2-propynyl methyl(2-propenyl)phosphonite, 2 -Butenyl(methyl)phosphonite 1,1-dimethyl-2-propynyl, bis(2-propenyl)phosphonite 1,1-dimethyl-2-propynyl, di 1,1-Dimethyl-2-propynyl (3-butenyl)phosphonite, 2-propenyl methyl(2-propynyl)phosphonite, methyl(2-propynyl) 3-butenyl phosphonite, 2-propenyl bis(2-propynyl) phosphonite, 3-butenyl bis(2-propynyl) phosphonite, 2-propynyl (2- 2-propenyl)phosphonite and 3-butenyl 2-propynyl(2-propenyl)phosphonite;

Phosphonates, such as 2-propynyl 2-propenyl phosphonic acid methyl ester, 2-butenyl phosphonic acid methyl (2-propynyl) ester, 2-propenyl phosphonic acid (2-propynyl) ) (2-propenyl) ester, 3-butenylphosphonic acid (3-butenyl) (2-propynyl) ester, 2-propenylphosphonic acid (1,1-dimethyl-2-propane Alkynyl) (methyl) ester, 2-butenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl) ester, 2-propenylphosphonic acid (1,1-dimethyl -2-propynyl)(2-propenyl)ester, 3-butenylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl)ester, methylphosphine Acid (2-propynyl)(2-propenyl) ester, methylphosphonic acid (3-butenyl) (2-propynyl) ester, methylphosphonic acid (1,1-dimethyl-2 -propynyl)(2-propenyl)ester, methylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl)ester, ethylphosphonic acid (2-propynyl) Base) (2-propenyl) ester, ethylphosphonic acid (3-butenyl) (2-propynyl) ester, ethylphosphonic acid (1,1-dimethyl-2-propynyl) ( 2-propenyl) ester and (3-butenyl)(1,1-dimethyl-2-propynyl) ethylphosphonate; and

Phosphate esters such as (methyl)(2-propenyl)(2-propynyl)phosphate, (ethyl)(2-propenyl)(2-propynyl)phosphate, (2-butene)phosphate base) (methyl) (2-propynyl) ester, (2-butenyl) (ethyl) (2-propynyl) phosphate, (1,1-dimethyl-2-propynyl) phosphate base) (methyl) (2-propenyl) ester, (1,1-dimethyl-2-propynyl) (ethyl) (2-propenyl) phosphate, (2-butenyl) phosphate (1,1-Dimethyl-2-propynyl)(methyl)ester and (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl)phosphate.

In order to more stably form a negative electrode film in an electrolytic solution, preferred among these are compounds containing an alkynyloxy group.

For improved storage properties, compounds such as 2-propynylmethyl carbonate, di-2-propynyl carbonate, 2-butyne-1,4-diol dimethyl carbonate, acetic acid 2-propynyl ester, 2-butyne-1,4-diol diacetate, 2-propynyl methyl oxalate and di-2-propynyl oxalate.

One compound containing a triple bond may be used alone, or two or more of them may be used in any combination in any ratio. The triple bond-containing compound may be present in any amount that does not significantly impair the effects of the present invention relative to the entire electrolyte solution of the present invention. With respect to the electrolytic solution of the present invention, the compound generally contains the following concentration: 0.01% by mass or higher, preferably 0.05% by mass or higher, more preferably 0.1% by mass or higher, and usually 5% by mass or lower, relatively Preferably 3% by mass or less, more preferably 1% by mass or less. Compounds satisfying the above range can further improve effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics.

The electrolytic solution of the present invention may contain an overcharge inhibitor in order to effectively reduce bursting or burning of batteries in the case of, for example, overcharging of an electrochemical device containing the electrolytic solution.

Examples of overcharge inhibitors include aromatic compounds, including unsubstituted or alkyl-substituted triphenyl derivatives such as biphenyl, o-, m-, and p-triphenyl, unsubstituted or alkyl-substituted Partial hydrogenation products of triphenyl derivatives, cyclohexylbenzene, tertiary butylbenzene, tertiary pentylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl Base-3-phenylindenane, cyclopentylbenzene, cyclohexylbenzene, cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, tertiary butylbenzene, tertiary Amylbenzene, tertiary hexylbenzene and anisole; partially fluorinated products of aromatic compounds, such as 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, o-cyclohexyl Fluorobenzene, p-cyclohexylfluorobenzene, fluorobenzene, fluorotoluene and trifluorotoluene; fluorine-containing anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 1,6 - difluoroanisole, 2,6-difluoroanisole and 3,5-difluoroanisole; aromatic acetates such as 3-propylphenyl acetate, 2-ethylphenyl acetate, Benzylphenyl acetate, methylphenyl acetate, benzyl acetate and phenethylphenyl acetate; aromatic carbonates, such as diphenyl carbonate and methylphenyl carbonate, toluene derivatives, such as toluene and di Toluene, and unsubstituted or alkyl-substituted biphenyl derivatives such as 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl and o-cyclohexylbiphenyl. Preferred among these are aromatic compounds such as biphenyl, alkylbiphenyl, triphenyl, partially hydrogenated triphenyl, cyclohexylbenzene, tertiary butylbenzene, tertiary pentylbenzene, diphenyl ether and diphenyl Furan, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindenane, 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, Methylphenyl acetate, benzyl acetate, diphenyl carbonate, and methylphenyl carbonate. One of these compounds may be used alone, or two or more of them may be used in combination. In order to use the combination of two or more of them to achieve a good balance between overcharge suppression characteristics and high-temperature storage characteristics, it is preferably a combination of cyclohexylbenzene and tertiary butylbenzene or tertiary pentylbenzene, or at least one oxygen-free aromatic compound selected from the group consisting of biphenyl, alkylbiphenyl, triphenyl, partially hydrogenated triphenyl, cyclohexylbenzene, tertiary butylbenzene, tertiary pentylbenzene and the like and A combination of at least one oxygen-containing aromatic compound selected from the group consisting of diphenyl ether, dibenzofuran, and the like.

The electrolytic solution used in the present invention may contain carboxylic anhydride. The carboxylic anhydride is preferably a compound represented by the following formula (6). The carboxylic anhydride can be produced by any method which can be appropriately selected from known methods.

在式(6)中，R ⁶¹及R ⁶²各自獨立地為具有1或更大且15或更小之碳數且視情況含有取代基之烴基。 [chemical formula 69]

In formula (6), R ⁶¹ and R ⁶² are each independently a hydrocarbon group having a carbon number of 1 or more and 15 or less and optionally containing a substituent.

Each of R ⁶¹ and R ⁶² can be any monovalent hydrocarbon group. For example, each of them may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or may be a bond of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. Aliphatic hydrocarbon groups may be saturated and may contain unsaturated bonds (carbon-carbon double bonds or carbon-carbon triple bonds). Aliphatic hydrocarbyl groups can be acyclic or cyclic. In the case of an acyclic group, it may be linear or branched. The group may be an acyclic group and a bond of a cyclic group. R ⁶¹ and R ⁶² may be the same as or different from each other.

When the hydrocarbon groups of R ⁶¹ and R ⁶² contain substituents, the substituents may be of any type as long as they do not exceed the scope of the present invention. Examples thereof include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom. Preferably it is a fluorine atom. Examples of substituents other than halogen atoms include substituents containing functional groups such as ester groups, cyano groups, carbonyl groups or ether groups. Preferred are cyano and carbonyl. The hydrocarbyl groups of R ⁶¹ and R ⁶² may contain only one of these substituents or may contain two or more of them. When two or more substituents are contained, these substituents may be the same as or different from each other.

The carbon number of the hydrocarbon group of R ⁶¹ and R ⁶² is usually 1 or more, and usually 15 or less, preferably 12 or less, more preferably 10 or less, and more preferably 9 or less. When R ⁶¹ and R ⁶² combine with each other to form a divalent hydrocarbon group, the carbon number of the divalent hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 13 or less, more preferably 10 or less, and then Preferably 8 or less. When the hydrocarbon groups of R ⁶¹ and R ⁶² contain substituents containing carbon atoms, the carbon numbers of the entire R ⁶¹ and R ⁶² including the substituents preferably meet the above range.

Next, specific examples of the acid anhydride represented by formula (6) are described. In the following examples, the term "analogue" means an acid anhydride obtainable by replacing a part of the structure of the acid anhydride mentioned as an example with another structure within the scope of the present invention. Examples thereof include dimers, trimers, and tetramers each composed of a plurality of acid anhydrides, structural isomers such as structural isomers having substituents having the same number of carbon atoms but also having branches, and substituents and anhydrides Structural isomers with different binding sites.

First, specific examples of acid anhydrides in which R ⁶¹ and R ⁶² are identical to each other are described.

Specific examples of acid anhydrides wherein R ^{and R} are linear alkyl groups include acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutyric anhydride, 3-methyl butyric anhydride, 2,2-dimethyl butyric anhydride, 2,3-dimethyl butyric anhydride, 3,3-dimethyl butyric anhydride, 2,2,3-trimethyl butyric anhydride, 2 , 3,3-trimethylbutyric anhydride, 2,2,3,3-tetramethylbutyric anhydride and 2-ethylbutyric anhydride and their analogs.

Specific examples of anhydrides wherein R ^{and R} are cyclic alkyl include cyclopropane formic anhydride, cyclopentane formic anhydride, and cyclohexane formic anhydride and the like.

Specific examples of anhydrides wherein R ^and R are ^alkenyl include acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, 2,3-dimethacrylic anhydride, 3,3-dimethacrylic anhydride anhydride, 2,3,3-trimethacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3,3-diphenylacrylic anhydride, 3- Butene anhydride, 2-methyl-3-butene anhydride, 2,2-dimethyl-3-butene anhydride, 3-methyl-3-butene anhydride, 2-methyl-3-methyl- 3-butene anhydride, 2,2-dimethyl-3-methyl-3-butene anhydride, 3-pentene anhydride, 4-pentene anhydride, 2-cyclopentene formic anhydride, 3-cyclopentene Formic anhydride and 4-cyclopentene formic anhydride and their analogs.

Specific examples of anhydrides wherein R and R ^{are alkynyl include} propynoic anhydride, 3-phenylpropynoic anhydride, 2-butynoic anhydride, 2-pentynoic anhydride, 3-butynoic anhydride, 3-pentynoic anhydride and 4-pentynoic anhydride and its analogues.

Specific examples of acid anhydrides wherein R ^and R ^are aryl include benzoic anhydride, 4-methylbenzoic anhydride, 4-ethylbenzoic anhydride, 4-tertiary butylbenzoic anhydride, 2-methylbenzoic anhydride, Formic anhydride, 2,4,6-trimethylbenzoic anhydride, 1-naphthoic anhydride and 2-naphthoic anhydride and their analogs.

Examples of acid anhydrides substituted with fluorine atoms are mainly listed below as examples of acid anhydrides in which R ⁶¹ and R ⁶² are substituted with halogen atoms. Anhydrides obtainable by replacing any or all of their fluorine atoms with chlorine, bromine or iodine atoms are also included in the exemplary compounds.

Examples of acid anhydrides wherein R ^{and R} are linear alkyl substituted by halogen include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, 2-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2 ,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrapropionic anhydride, 2,3,3,3- Tetrapropionic anhydride, 3-fluoropropionic anhydride, 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic anhydride, perfluoropropionic anhydride and the like.

Examples of anhydrides wherein R ^{and R} are halogen-substituted cyclic alkyl include 2-fluorocyclopentanecarboxylic anhydride, 3-fluorocyclopentanecarboxylic anhydride, and 4-fluorocyclopentanecarboxylic anhydride and the like .

Examples of anhydrides wherein R ^{and R} are halogen-substituted alkenyl include 2-fluoroacrylic anhydride, 3-fluoroacrylic anhydride, 2,3-difluoroacrylic anhydride, 3,3-difluoroacrylic anhydride, 2, 3,3-trifluoroacrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, 3-(trifluoromethyl)acrylic anhydride, 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3,3 - Tris(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 3-(4-fluorophenyl)acrylic anhydride, 2,3-bis(4-fluorophenyl)acrylic anhydride, 3,3-bis(4-fluorophenyl)acrylic anhydride, 2-fluoro-3-butene anhydride, 2,2-difluoro-3-butene anhydride, 3-fluoro-2-butene anhydride, 4- Fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride and 3,3,4-trifluoro-3-butenoic anhydride and the like.

Examples of anhydrides wherein R ^{and R} are halogen-substituted alkynyl include 3-fluoro-2-propynoic anhydride, 3-(4-fluorophenyl)-2-propynoic anhydride, 3-(2,3 ,4,5,6-pentafluorophenyl)-2-propynoic anhydride, 4-fluoro-2-butynoic anhydride, 4,4-difluoro-2-butynoic anhydride and 4,4,4-trifluoro -2-Butynoic anhydride and its analogues.

Examples of anhydrides wherein R and ^R are halogen-substituted aryl include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride and 4 ^- trifluorobenzoic anhydride, and analog.

Examples of acid anhydrides wherein R ^and R ^each contain substituents containing functional groups such as esters, nitriles, ketones, ethers, or the like include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, acetic anhydride, oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutyric anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride and 4-methoxybenzoic anhydride and its analogues.

Subsequently, specific examples of acid anhydrides in which R ⁶¹ and R ⁶² are different from each other are described below.

R ⁶¹ and R ⁶² may be in any combination of those mentioned above as examples and their analogs. Representative examples are given below.

Examples of combinations of linear alkyl groups include acetic acid propionic anhydride, acetic acid butyric anhydride, butyric acid propionic anhydride, and acetic acid 2-methylpropionic anhydride.

Examples of combinations of linear alkyl groups and cyclic alkyl groups include acetic acid cyclopentanoic anhydride, acetic acid cyclohexanoic anhydride, and cyclopentanoic acid propionic anhydride.

Examples of combinations of linear alkyl and alkenyl groups include acetic acrylic anhydride, acetic 3-methacrylic anhydride, acetic 3-butenoic anhydride, and acrylic propionic anhydride.

Examples of combinations of straight-chain alkyl and alkynyl groups include acetic acid propiolic anhydride, acetic acid 2-butynoic anhydride, acetic acid 3-butynoic anhydride, acetic acid 3-phenylpropiolic anhydride, and acetic acid propiolic anhydride.

Examples of combinations of linear alkyl and aryl groups include acetic anhydride benzoic anhydride, acetic acid 4-methylbenzoic anhydride, acetic acid 1-naphthoic anhydride, and benzoic anhydride propionic acid.

Examples of combinations of linear alkyl groups and hydrocarbon groups containing functional groups include acetic acid fluoroacetic anhydride, acetic acid trifluoroacetic anhydride, acetic acid 4-fluorobenzoic anhydride, fluoroacetic acid propionic anhydride, acetate alkyl oxalic anhydride, acetic acid 2-cyano Acetic anhydride, acetic acid 2-oxopropionic anhydride, acetic acid methoxyacetic anhydride, and methoxyacetic acid anhydride.

Examples of combinations of cyclic alkyl groups include cyclopentanoic acid cyclohexanoic anhydride.

Examples of combinations of cyclic alkyl and alkenyl groups include acrylate cyclopentanoic anhydride, 3-methacrylate cyclopentanoic anhydride, 3-butenoic acid cyclopentanoic anhydride, and acrylate cyclohexanoic anhydride.

Examples of combinations of cyclic alkyl and alkynyl groups include propiolic acid cyclopentanoic anhydride, 2-butynoic acid cyclopentanoic anhydride, and propiolic acid cyclohexanoic anhydride.

Examples of combinations of cyclic alkyl and aryl groups include benzoic acid cyclopentanoic anhydride, 4-methylbenzoic acid cyclopentanoic anhydride, and benzoic acid cyclohexanoic anhydride.

Examples of combinations of cyclic alkyl groups and functional group-containing hydrocarbon groups include fluoroacetic acid cyclopentanoic anhydride, cyclopentanoic acid trifluoroacetic anhydride, cyclopentanoic acid 2-cyanoacetic anhydride, cyclopentanoic acid methoxyacetic anhydride, and cyclohexyl Acid Fluoroacetic Anhydride.

Examples of combinations of alkenyl groups include acrylic acid 2-methacrylic anhydride, acrylic acid 3-methacrylic anhydride, acrylic acid 3-butene anhydride, and 2-methacrylic acid 3-methacrylic anhydride.

Examples of combinations of alkenyl and alkynyl groups include propiolic anhydride acrylate, 2-butynoic anhydride acrylic acid, and propiolic anhydride 2-methacrylate.

Examples of combinations of alkenyl and aryl groups include acrylic benzoic anhydride, acrylic 4-methylbenzoic anhydride, and 2-methacrylic benzoic anhydride.

Examples of combinations of alkenyl and functional group-containing hydrocarbon groups include acrylic fluoroacetic anhydride, acrylic trifluoroacetic anhydride, acrylic 2-cyanoacetic anhydride, acrylic methoxyacetic anhydride, and 2-methacrylic fluoroacetic anhydride.

Examples of combinations of alkynyl groups include propiolic acid 2-butynoic anhydride, propiolic acid 3-butynoic anhydride, and 2-butynoic acid 3-butynoic anhydride.

Examples of combinations of alkynyl and aryl groups include propiolic anhydride benzoate, propiolic anhydride 4-methylbenzoate, and 2-butynoic anhydride benzoate.

Examples of combinations of alkynyl and functional group-containing hydrocarbon groups include propiolic acid fluoroacetic anhydride, propiolic acid trifluoroacetic anhydride, propiolic acid 2-cyanoacetic anhydride, propiolic acid methoxyacetic anhydride, and 2-butyroic acid Alkynoic acid fluoroacetic anhydride.

Examples of combinations of aryl groups include benzoic acid 4-methylbenzoic anhydride, benzoic acid 1-naphthoic anhydride, and 4-methylbenzyl-1-naphthoic anhydride.

Examples of combinations of aryl and functional group-containing hydrocarbon groups include fluoroacetic anhydride benzoate, trifluoroacetic anhydride benzoate, 2-cyanoacetic anhydride benzoate, methoxyacetic anhydride benzoate, and fluoromethylbenzoate Acetic anhydride.

Examples of combinations of hydrocarbon groups each containing a functional group include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, and trifluoroacetic acid 2-cyanoacetic anhydride.

Among acid anhydrides with acyclic structure, acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentane formic anhydride, cyclohexane formic anhydride, acrylic anhydride, 2-methacrylic anhydride, 3-formic acid anhydride are preferred. Acrylic anhydride, 2,3-dimethacrylic anhydride, 3,3-dimethacrylic anhydride, 3-butene anhydride, 2-methyl-3-butene anhydride, propynoic anhydride, 2-butynoic anhydride , benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tertiary butylbenzoic anhydride, trifluoroacetic anhydride, 3,3,3-trifluoropropionic anhydride, 2-( Trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride and acetic anhydride Oxyformic anhydride. More preferably acrylic anhydride, 2-methacrylic anhydride, 3-methacrylic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tertiary butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride and ethoxyformic anhydride.

These compounds are preferable because they can properly form a bond with lithium oxalate to provide a film with excellent durability, thereby improving especially charge and discharge rate characteristics, input and output characteristics, and impedance characteristics after an endurance test.

The carboxylic anhydride may have any molecular weight that does not significantly impair the effect of the present invention. The molecular weight is usually 90 or higher, preferably 95 or higher, while usually 300 or lower, preferably 200 or lower. Carboxylic anhydrides with a molecular weight within the above range can reduce the viscosity increase of the electrolyte solution and can produce a reasonable film density, appropriately improving durability.

Carboxylic anhydrides can be formed by any manufacturing method that can be selected from known methods. The non-aqueous electrolyte solution of the present invention may contain one of the above-described carboxylic acid anhydrides alone, or may contain two or more of them in any ratio and in any combination.

With respect to the electrolytic solution of the present invention, any amount of carboxylic anhydride that does not significantly impair the effect of the present invention may be contained. With respect to the electrolytic solution of the present invention, carboxylic acid anhydride is usually contained at a concentration of 0.01% by mass or more, preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less. The carboxylic anhydride in the amount within the above range can easily achieve the effect of improving cycle characteristics and has good reactivity, and can easily improve battery characteristics.

𠷬、二

烷、2,5,8,11-四氧雜十二烷、2,5,8,11,14-五氧雜十五烷、乙氧基甲氧基乙烷、三甲氧基甲烷、乙二醇二甲醚及乙基乙二醇二甲醚； 酮化合物，諸如二甲基酮、二乙基酮及3-戊酮； 酸酐，諸如2-烯丙基丁二酸酐； 酯化合物，諸如草酸二甲酯、草酸二乙酯、草酸乙基甲酯、草酸二(2-丙炔基)酯、2-丙炔基草酸甲酯、丁二酸二甲酯、戊二酸二(2-丙炔基)酯、甲酸甲酯、甲酸乙酯、甲酸2-丙炔酯、二甲酸2-丁炔-1,4-二酯、甲基丙烯酸2-丙炔酯及丙二酸二甲酯； 醯胺化合物，諸如乙醯胺、N-甲基甲醯胺、N,N-二甲基甲醯胺及N,N-二甲基乙醯胺； 含硫化合物，諸如硫酸伸乙酯、硫酸伸乙烯酯、亞硫酸伸乙酯、氟磺酸甲酯、氟磺酸乙酯、甲磺酸甲酯、甲磺酸乙酯、白消安（busulfan）、環丁烯碸、二苯基碸、N,N-二甲基甲磺醯胺、N,N-二乙基甲磺醯胺、乙烯基磺酸甲酯、乙烯基磺酸乙酯、乙烯基磺酸烯丙酯、乙烯基磺酸炔丙酯、烯丙基磺酸甲酯、烯丙基磺酸乙酯、烯丙基磺酸烯丙酯、烯丙基磺酸炔丙酯、1,2-雙(乙烯基磺醯氧基)乙烷、丙二磺酸酐、磺基丁酸酐、磺基苯甲酸酐、磺基丙酸酐、乙二磺酸酐、甲二磺酸亞甲酯、甲磺酸2-丙炔酯、亞硫酸戊烯酯、甲磺酸五氟苯酯、硫酸丙烯酯、亞硫酸丙烯酯、丙磺內酯、亞硫伸丁基酯、二甲磺酸丁烷-2,3-二酯、二甲烷磺酸2-丁炔-1,4-二酯、2-丙炔基磺酸乙烯酯、雙(2-乙烯基磺醯基乙基)醚、5-乙烯基-六氫-1,3,2-苯并二

硫醇-2-氧化物、2-(甲磺醯基氧基)丙酸2-丙炔酯、5,5-二甲基-1,2-

噻𠷬-4-酮2,2-二氧化物、3-磺基-丙酸酐、甲二磺酸三亞甲酯、2-甲基四氫呋喃、甲二磺酸三亞甲酯、四亞甲基亞碸、甲二磺酸二亞甲酯、二氟乙基甲基碸、雙乙烯碸、1,2-雙(乙烯磺醯基)乙烷、伸乙二磺酸甲酯、伸乙二磺酸乙酯、硫酸伸乙酯及噻吩1-氧化物； 含氮化合物，諸如1-甲基-2-吡咯啶酮、1-甲基-2-哌啶酮、3-甲基-2-

唑啶酮、1,3-二甲基-2-咪唑啶酮、N-甲基丁二醯亞胺、硝基甲烷、硝基乙烷及乙二胺； 含磷化合物，諸如亞磷酸三甲基酯、亞磷酸三乙酯、亞磷酸三苯酯、磷酸三甲酯、磷酸三乙酯、磷酸三苯酯、二甲基膦酸甲酯、二乙基膦酸乙酯、二甲基膦酸乙烯酯、二乙基膦酸乙烯酯、二乙基膦醯基乙酸乙酯、二甲基亞膦酸甲酯、二乙基亞膦酸乙酯、氧化三甲膦、氧化三乙膦、磷酸雙(2,2-二氟乙基)2,2,2-三氟乙酯、磷酸雙(2,2,3,3-四氟丙基)2,2,2-三氟乙酯、磷酸雙(2,2,2-三氟乙基)甲酯、磷酸雙(2,2,2-三氟乙基)乙酯、磷酸雙(2,2,2-三氟乙基)2,2-二氟乙酯、磷酸雙(2,2,2-三氟乙基)2,2,3,3-四氟丙酯、磷酸三丁酯、磷酸三(2,2,2-三氟乙基)酯、磷酸三(1,1,1,3,3,3-六氟丙-2-基)酯、磷酸三辛酯、磷酸2-苯基苯二甲酯、磷酸2-苯基苯二乙酯、磷酸(2,2,2-三氟乙基)(2,2,3,3-四氟丙基)甲酯、乙酸甲基2-(二甲氧基磷醯基)酯、乙酸甲基2-(二甲基磷醯基)酯、乙酸甲基2-(二乙氧基磷醯基)酯、乙酸甲基2-(二乙基磷醯基)酯、亞甲基雙膦酸甲酯、亞甲基雙膦酸乙酯、伸乙基雙膦酸甲酯、伸乙基雙膦酸乙酯、伸丁基雙膦酸甲酯、伸丁基雙膦酸乙酯、2-(二甲氧基磷醯基)乙酸2-丙炔酯、2-(二甲基磷醯基)乙酸2-丙炔酯、2-(二乙氧基磷醯基)乙酸2-丙炔酯、2-(二乙基磷醯基)乙酸2-丙炔酯、磷酸三(三甲基矽基)酯、磷酸三(三乙基矽基)酯、磷酸三(三甲氧基矽基)酯、亞磷酸三(三甲基矽基)酯、亞磷酸三(三乙基矽基)酯、亞磷酸三(三甲氧基矽基)酯及多磷酸三甲基矽基酯； 含硼化合物，諸如硼酸三(三甲基矽基)酯及硼酸三(三甲氧基矽基)酯；及 矽烷化合物，諸如二甲氧基鋁氧基三甲氧基矽烷、二乙氧基鋁氧基三乙氧基矽烷、二丙氧基鋁氧基三乙氧基矽烷、二丁氧基鋁氧基三甲氧基矽烷、二丁氧基鋁氧基三乙氧基矽烷、四(三甲基矽氧基)鈦、四(三乙基矽氧基)鈦和四甲基矽烷。可單獨使用此等化合物中之一者，或可組合使用其中之兩者或更多者。此等助劑可改良高溫儲存後之容量保持特性及循環特性。 此等中作為不同助劑較佳的為含磷化合物，且尤其較佳磷酸三(三甲基矽基)酯及亞磷酸三(三甲基矽基)酯。 The electrolyte solution of the present invention may further contain various known additives. Examples of different additives include hydrocarbon compounds such as pentane, heptane, octane, nonane, decane, cycloheptane, benzene, furan, naphthalene, 2-phenylbicyclohexyl, cyclohexane, 2,4, 8,10-tetraoxaspiro[5.5]undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane; fluorine-containing aromatic compounds such as fluorine Benzene, difluorobenzene, hexafluorobenzene, trifluorotoluene, monofluorobenzene, 1-fluoro-2-cyclohexylbenzene, 1-fluoro-4-tertiary butylbenzene, 1-fluoro-3-cyclohexylbenzene, 1-fluoro-2-cyclohexylbenzene and biphenyl fluoride; carbonate compounds such as tetrahydrofuran diol carbonate, spiro-bis-dimethyl carbonate and methoxyethyl-methyl carbonate; ether compounds such as di

𠷬, two

alkane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentoxapentadecane, ethoxymethoxyethane, trimethoxymethane, ethylene di Alcohol dimethyl ether and ethyl glycol dimethyl ether; Ketone compounds, such as dimethyl ketone, diethyl ketone, and 3-pentanone; Anhydrides, such as 2-allyl succinic anhydride; Esters, such as oxalic acid Dimethyl oxalate, diethyl oxalate, ethyl methyl oxalate, bis(2-propynyl) oxalate, 2-propynyl methyl oxalate, dimethyl succinate, bis(2-propynyl glutarate) Alkynyl) esters, methyl formate, ethyl formate, 2-propynyl formate, 2-butyne-1,4-dicarboxylate, 2-propynyl methacrylate and dimethyl malonate; Amide compounds, such as acetamide, N-methylformamide, N,N-dimethylformamide and N,N-dimethylacetamide; sulfur-containing compounds, such as ethyl sulfate, sulfuric acid vinylene ester, ethyl sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, cyclobutene, diphenylsulfonate , N,N-dimethylmethanesulfonamide, N,N-diethylmethanesulfonamide, methyl vinyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, vinyl sulfonate propargyl allyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl sulfonate, propargyl allyl sulfonate, 1,2-bis(vinylsulfonyloxy base) ethane, propanedisulfonic anhydride, sulfobutyric anhydride, sulfobenzoic anhydride, sulfopropionic anhydride, ethanedisulfonic anhydride, methylene methanesulfonate, 2-propynyl methanesulfonate, sulfurous acid Pentenyl ester, pentafluorophenyl methanesulfonate, propylene sulfate, propylene sulfite, propene sultone, sulfinyl butyl ester, butane-2,3-dimethanesulfonate, dimethanesulfonate Acid 2-butyne-1,4-diester, vinyl 2-propynylsulfonate, bis(2-vinylsulfonylethyl)ether, 5-vinyl-hexahydro-1,3,2 - Benzodi

Mercaptan-2-oxide, 2-propynyl 2-(methylsulfonyloxy)propionate, 5,5-dimethyl-1,2-

Thiol-4-one 2,2-dioxide, 3-sulfo-propionic anhydride, trimethylene methanedisulfonate, 2-methyltetrahydrofuran, trimethylene methanedisulfonate, tetramethylene methylene , Dimethylene methanedisulfonate, difluoroethyl methyl sulfonate, bisethylene disulfonate, 1,2-bis(vinylsulfonyl)ethane, methyl ethylene disulfonate, ethyl ethylene disulfonate esters, ethyl sulfate and thiophene 1-oxides; nitrogen-containing compounds such as 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 3-methyl-2-

Pazolidone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide, nitromethane, nitroethane, and ethylenediamine; phosphorus-containing compounds such as trimethylphosphite base ester, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, methyl dimethyl phosphonate, ethyl diethyl phosphonate, dimethyl phosphine Vinyl Diethylphosphonate, Vinyl Diethylphosphonate, Ethyl Diethylphosphonoacetate, Methyl Dimethylphosphonite, Ethyl Diethylphosphonite, Trimethylphosphine Oxide, Triethylphosphine Oxide, Phosphoric Acid Bis(2,2-difluoroethyl)2,2,2-trifluoroethyl ester, bis(2,2,3,3-tetrafluoropropyl)2,2,2-trifluoroethyl phosphate, phosphoric acid Bis(2,2,2-trifluoroethyl)methyl ester, bis(2,2,2-trifluoroethyl)ethyl phosphate, bis(2,2,2-trifluoroethyl)2,2 phosphate -Difluoroethyl ester, bis(2,2,2-trifluoroethyl) 2,2,3,3-tetrafluoropropyl phosphate, tributyl phosphate, tris(2,2,2-trifluoroethyl) phosphate base) ester, tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate, trioctyl phosphate, 2-phenylbenzenedimethyl phosphate, 2-phenylbenzene phosphate Diethyl ester, (2,2,2-trifluoroethyl)(2,2,3,3-tetrafluoropropyl)methyl phosphate, methyl 2-(dimethoxyphosphoryl) acetate, Methyl 2-(dimethylphosphoryl) acetate, methyl 2-(diethoxyphosphoryl) acetate, methyl 2-(diethylphosphoryl) acetate, methylenebis Methyl phosphonate, ethyl methylene bisphosphonate, methyl ethyl bisphosphonate, ethyl ethyl bisphosphonate, methyl ethyl bisphosphonate, ethyl ethyl bisphosphonate, 2-(Dimethoxyphosphoryl)acetate 2-propynyl ester, 2-(dimethylphosphoryl)acetate 2-propynyl ester, 2-(diethoxyphosphoryl)acetate 2-propynyl ester Alkyne esters, 2-(diethylphosphoryl) acetate, 2-propynyl acetate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate ) ester, tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, tris(trimethoxysilyl) phosphite and trimethylsilyl polyphosphate; containing boron Compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate; and silane compounds such as dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytrimethoxysilane, Ethoxysilane, Dipropoxyaluminumoxytriethoxysilane, Dibutoxyaluminumoxytrimethoxysilane, Dibutoxyaluminumoxytriethoxysilane, Tetrakis(trimethylsiloxane base) titanium, tetrakis(triethylsilyloxy)titanium and tetramethylsilane. One of these compounds may be used alone, or two or more of them may be used in combination. These additives can improve the capacity retention characteristics and cycle characteristics after high temperature storage. Among these, preferred as various additives are phosphorus-containing compounds, and especially preferred are tris(trimethylsilyl)phosphate and tris(trimethylsilyl)phosphite.

The various adjuvants may be present in any amount which does not significantly impair the effect of the invention. The amount of the various auxiliary agents is preferably 0.01% by mass or more and 5% by mass or less based on 100% by mass of the electrolyte solution. The various auxiliary agents in amounts within this range can easily exhibit their effects sufficiently, and can easily avoid a situation where battery characteristics such as high-load discharge characteristics are impaired. The amount of the different additives is more preferably 0.1% by mass or more, more preferably 0.2% by mass or more, more preferably 3% by mass or less, and more preferably 1% by mass or less.

Within the scope of not impairing the effect of the present invention, the electrolytic solution of the present invention may further contain any one of the following as additives: cyclic carboxylate, acyclic carboxylate, ether compound, nitrogen-containing compound, boron-containing Compounds, organosilicon-containing compounds, fire retardants (flame retardants), surfactants, additives for increasing permittivity, improvers for cycle characteristics and rate characteristics, and compounds based on 碸.

Examples of cyclic carboxylic acid esters include cyclic carboxylic acid esters having 3 to 12 total carbons in the structural formula. Specific examples thereof include γ-butyrolactone, γ-valerolactone, γ-caprolactone, ε-caprolactone, and 3-methyl-γ-butyrolactone. In order to improve the characteristics of the electrochemical device due to the improved dissociation degree of lithium ions, γ-butyrolactone is especially preferred.

In general, the cyclic carboxylic acid ester as an additive is preferably present in an amount of 0.1% by mass or more, more preferably 1% by mass or more, based on 100% by mass of the solvent. The cyclic carboxylate in an amount within this range can easily improve the conductivity of the electrolytic solution, thereby improving the large-current discharge characteristics of the electrochemical device. The amount of cyclic carboxylic acid ester is also preferably 10% by mass or less, more preferably 5% by mass or less. Such an upper limit enables the electrolyte solution to have a viscosity within an appropriate range, may make it possible to avoid a decrease in electrical conductivity, may reduce the increase in resistance of the negative electrode, and may enable the electrochemical device to have high-current discharge characteristics within a favorable range.

The cyclic carboxylate to be suitably used may also be a fluorinated cyclic carboxylate (fluorine-containing lactone). Examples of fluorine-containing lactones include fluorine-containing lactones represented by the following formula (C):

[chemical formula 70]

Wherein X ¹⁵ to X ²⁰ are the same or different from each other, and each is -H, -F, -Cl, -CH ₃ or a fluorinated alkyl group; and at least one selected from X ¹⁵ to X ²⁰ is a fluorinated alkyl group .

Examples of fluorinated alkyl groups from X ¹⁵ to X ²⁰ include -CFH ₂ , -CF ₂ H, -CF ₃ , -CH ₂ CF ₃ , -CF ₂ CF ₃ , -CH ₂ CF ₂ CF _{3 ,} and -CF(CF ₃ ) ₂ . In order to achieve the effects of high oxidation resistance and improved safety, -CH ₂ CF ₃ and -CH ₂ CF ₂ CF ₃ are preferred.

Only when at least one selected from X ¹⁵ to X ²⁰ is a fluorinated alkyl group, one or more of X ¹⁵ to X ²⁰ can be treated with -H, -F, -Cl, -CH ₃ or fluorinated alkyl base replacement. In order to provide good solubility of the electrolyte salt, the number of substituents is preferably 1-3, more preferably 1 or 2.

Substitution of fluorinated alkyl groups can be at any of the above positions. In order to provide good synthesis yield, the substitution site is preferably X ¹⁷ and/or X ¹⁸ . Specifically, X ¹⁷ or X ¹⁸ is preferably a fluorinated alkyl group, especially -CH ₂ CF ₃ or -CH ₂ CF ₂ CF ₃ . The substituents of X ¹⁵ to X ²⁰ other than the fluorinated alkyl group are -H, -F, -Cl or CH ₃ . In order to provide good solubility of the electrolyte salt, -H is preferred.

In addition to those represented by the above formula, the fluorine-containing lactone may also be a fluorine-containing lactone represented by the following formula (D):

[chemical formula 71]

Wherein one of A or B is CX ²²⁶ X ²²⁷ (wherein X ²²⁶ and X ²²⁷ are the same or different from each other, and each is -H, -F, -Cl, -CF ₃ , -CH ₃ , or alkylene, wherein the hydrogen atom is optionally replaced by a halogen atom and which optionally contains a heteroatom in the chain) and the other is an oxygen atom; Rf ¹² is a fluorinated alkyl or fluorinated alkoxy optionally containing an ether linkage; X ²²¹ and X ²²² are the same or different from each other, and are each -H, -F, -Cl, -CF ₃ or CH ₃ ; X ²²³ to X ²²⁵ are the same or different from each other, and are each -H, -F, -Cl or alkane wherein the hydrogen atoms are optionally replaced by halogen atoms and which optionally contain heteroatoms in the chain; and n=0 or 1.

A preferred example of the fluorine-containing lactone represented by formula (D) is a 5-membered ring structure represented by the following formula (E):

[chemical formula 72]

(wherein A, B, Rf ¹² , X ²²¹ , X ²²² and X ²²³ are as defined in formula (D)), because it can be easily synthesized and can have good chemical stability. In addition, regarding the combination of A and B, fluorine-containing lactones represented by the following formula (F):

[chemical formula 73]

(wherein Rf ¹² , X ²²¹ , X ²²² , X ²²³ , X ²²⁶ and X ²²⁷ are as defined in formula (D)) and a fluorine-containing lactone represented by the following formula (G):

[chemical formula 74]

(wherein Rf ¹² , X ²²¹ , X ²²² , X ²²³ , X ²²⁶ and X ²²⁷ are as defined in formula (D)).

In order to provide excellent characteristics (such as high permittivity and high withstand voltage) in particular, and to improve the characteristics of the electrolyte solution of the present invention, for example, to provide good solubility of electrolyte salts and to reduce internal resistance well, it can be mentioned that the They are represented by the following formula:

。 氟化環狀羧酸酯之存在可引起例如改良離子導電性、改良安全性及改良高溫下穩定性之效果。 [chemical formula 75]

. The presence of fluorinated cyclic carboxylates can lead to effects such as improved ionic conductivity, improved safety, and improved stability at high temperatures.

Examples of the acyclic carboxylate include those having a total carbon number of 3 to 7 in the structural formula. Specific examples thereof include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propionic acid n-propyl, isobutyl propionate, n-butyl propionate, methyl butyrate, isobutyl propionate, tertiary butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, Isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate and isopropyl isobutyrate.

In order to improve ionic conductivity due to viscosity reduction, preferred among these are methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate ester, isopropyl propionate, methyl butyrate and ethyl butyrate.

The ether compound is preferably a C2-C10 acyclic ether or a C3-C6 cyclic ether. Examples of C2-C10 acyclic ethers include dimethyl ether, diethyl ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, diethoxymethane, dimethoxyethane, methane Oxyethoxyethane, diethoxyethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol, diethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, triethylene glycol dimethyl ether, triethylene glycol, tetraethylene glycol, tetraethylene glycol dimethyl ether and diisopropyl ether.

In addition, the ether compound may also suitably be a fluorinated ether. An example of a fluorinated ether is a fluorinated ether (I) represented by the following formula (I): Rf ³ —O—Rf ⁴ (I) (wherein Rf ³ and Rf ⁴ are the same or different from each other, and each is a C1-C10 alkane group or C1-C10 fluorinated alkyl group; and at least one selected from the group consisting of Rf ³ and Rf ⁴ is a fluorinated alkyl group). The presence of the fluorinated ether (I) gives the electrolyte solution improved nonflammability and improved stability and safety at high temperature and high voltage.

In formula (I), at least one selected from the group consisting of Rf ³ and Rf ⁴ is a C1-C10 fluorinated alkyl group. In order to make the electrolyte solution have further improved nonflammability and further improved stability and safety under high temperature and high voltage, both Rf ³ and Rf ⁴ are preferably C1-C10 fluorinated alkyl groups. In this case, Rf ³ and Rf ⁴ may be the same as or different from each other. Especially preferably, Rf ³ and Rf ⁴ are the same or different from each other, and Rf ³ is a C3-C6 fluorinated alkyl group and Rf ⁴ is a C2-C6 fluorinated alkyl group.

If the sum of the carbon numbers of Rf ³ and Rf ⁴ is too small, the boiling point of the fluorinated ether may be too low. An excessively large carbon number of Rf ³ or Rf ⁴ may result in low solubility of the electrolyte salt, may start to adversely affect miscibility with other solvents, and may result in high viscosity, making rate characteristics poor. In order to achieve excellent boiling point and rate characteristics, advantageously, Rf ³ has 3 or 4 carbons and Rf ⁴ has 2 or 3 carbons.

The fluorinated ether (I) preferably has a fluorine content of 40 to 75% by mass. Fluorinated ethers (I) having a fluorine content within this range result in a particularly good balance between non-flammability and miscibility. The above range is also preferable for good oxidation resistance and safety. The lower limit of the fluorine content is more preferably 45% by mass, still more preferably 50% by mass, especially preferably 55% by mass. The upper limit thereof is more preferably 70% by mass, still more preferably 66% by mass. The fluorine content of the fluorinated ether (I) is a value calculated by the following formula based on the structural formula of the fluorinated ether (I): {(number of fluorine atoms×19)/(molecular weight of fluorinated ether (I))}×100 (%).

Examples of Rf ³ include CF ₃ CF ₂ CH ₂ -, CF ₃ CFHCF ₂ -, HCF ₂ CF ₂ CF ₂ -, HCF ₂ CF ₂ CH ₂ -, CF ₃ CF ₂ CH ₂ CH ₂ -, CF ₃ CFHCF ₂ CH ₂ -, HCF ₂ CF ₂ CF ₂ CF ₂ -, HCF ₂ CF ₂ CF ₂ CH ₂ -, HCF ₂ CF ₂ CH ₂ CH ₂ -, and HCF ₂ CF(CF ₃ )CH ₂ -. Examples of Rf ⁴ include -CH ₂ CF ₂ CF ₃ , -CF ₂ CFHCF ₃ , -CF ₂ CF ₂ CF ₂ H, -CH ₂ CF ₂ CF ₂ H, -CH ₂ CH ₂ CF ₂ CF ₃ , -CH ₂ CF ₂ CFHCF ₃ , -CF ₂ CF ₂ CF ₂ CF ₂ H, -CH ₂ CF ₂ CF ₂ CF ₂ H, -CH ₂ CH ₂ CF ₂ CF ₂ H, -CH ₂ CF(CF ₃ )CF ₂ H, -CF ₂ CF ₂ H, -CH ₂ CF ₂ H and -CF ₂ CH ₃ .

_{Specific examples of fluorinated ethers ( I ) include HCF2CF2CH2OCF2CF2H , CF3CF2CH2OCF2CF2H , HCF2CF2CH2OCF2CFHCF3 , CF3CF2CH _ 2} OCF ₂ CFHCF ₃ , C ₆ F ₁₃ OCH ₃ , C ₆ F ₁₃ OC ₂ H ₅ , C ₈ F ₁₇ OCH ₃ , C ₈ F ₁₇ OC ₂ H ₅ , CF ₃ CFHCF ₂ CH(CH ₃ )OCF ₂ CFHCF _3. HCF ₂ CF ₂ OCH(C ₂ H ₅ ) ₂ , HCF ₂ CF ₂ OC ₄ H ₉ , HCF ₂ CF ₂ OCH ₂ CH(C ₂ H ₅ ) ₂ and HCF ₂ CF ₂ OCH ₂ CH(CH ₃ ) ₂ .

In particular, those with _HCF2- or _CF3CFH- at one or each end can provide fluorinated ethers (I) with excellent polarizability and high boiling point. The boiling point of the fluorinated ether (I) is preferably from 67°C to 120°C, more preferably 80°C or higher, still more preferably 90°C or higher.

Such fluorinated ethers ₍ I) may include one or two or more of the following: CF ₃ CH ₂ OCF ₂ CFHCF ₃ , CF ₃ CF ₂ CH ₂ OCF 2 CFHCF ₃ , HCF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ , HCF ₂ CF ₂ CH ₂ OCH ₂ CF ₂ CF ₂ H, CF _{3 CFHCF 2} CH ₂ OCF ₂ CFHCF ₃ , HCF ₂ CF ₂ CH ₂ OCF 2 CF ₂ H, CF ₃ CF ₂ CH ₂ OCF ₂ CF ₂ H and its analogues. Advantageously, in order to achieve a high boiling point and good miscibility with other solvents and provide good solubility of electrolyte salts, the fluorinated ether (I) preferably includes at least one selected from the group consisting of: HCF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ (boiling point: 106°C), CF ₃ CF ₂ CH ₂ OCF ₂ CFHCF ₃ (boiling point: 82°C), HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H (boiling point: 92°C) and CF ₃ CF ₂ CH ₂ OCF ₂ CF ₂ H (boiling point: 68°C), more preferably at least one selected from the group consisting of HCF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ (boiling point: 106°C) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H (boiling point: 92°C).

烷、1,3-二

烷、2-甲基-1,3-二

烷、4-甲基-1,3-二

烷、1,4-二

烷、變甲醛、2-甲基-1,3-二

𠷬、1,3-二

𠷬、4-甲基-1,3-二

𠷬、2-(三氟乙基)二

𠷬、2,2,-雙(三氟甲基)-1,3-二

𠷬及其氟化化合物。為了達成與鋰離子高度溶合之能力且改良離子解離度，較佳為二甲氧基甲烷、二乙氧基甲烷、乙氧基甲氧基甲烷、乙二醇正丙醚、乙二醇二正丁醚、二乙二醇二甲醚及冠醚。為了達成低黏度且提供高離子導電性，尤其較佳為二甲氧基甲烷、二乙氧基甲烷及乙氧基甲氧基甲烷。Examples of C3-C6 cyclic ethers include 1,2-bis

Alkane, 1,3-bis

Alkane, 2-methyl-1,3-di

Alkane, 4-methyl-1,3-bis

Alkane, 1,4-bis

Alkane, metaformaldehyde, 2-methyl-1,3-di

𠷬, 1,3-di

𠷬, 4-methyl-1,3-di

𠷬, 2-(trifluoroethyl) di

𠷬、2,2,-bis(trifluoromethyl)-1,3-bis

𠷬 and its fluorinated compounds. In order to achieve a high solubility with lithium ions and improve ion dissociation, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol n-propyl ether, and ethylene glycol di-n-propyl ether are preferred. Butyl ether, diethylene glycol dimethyl ether and crown ether. In order to achieve low viscosity and provide high ionic conductivity, dimethoxymethane, diethoxymethane and ethoxymethoxymethane are especially preferred.

唑啶酮、1,3-二甲基-2-咪唑啶酮及N-甲基丁二醯亞胺。由式(1a)、(1b)及(1c)表示之腈化合物不包括於上述含氮化合物中。Examples of the nitrogen-containing compound include nitrile, fluorine-containing nitrile, carboxylic acid amide, fluorine-containing carboxylic acid amide, sulfonamide, fluorine-containing sulfonamide, acetamide, and formamide. In addition, 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 3-methyl-2-

Pazolidone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide. Nitrile compounds represented by formulas (1a), (1b) and (1c) are not included in the above nitrogen-containing compounds.

Examples of boron-containing compounds include borate esters, such as trimethyl borate and triethyl borate, borate ethers, and borate alkyl esters.

Examples of organosilicon-containing compounds include (CH ₃ ) ₄ -Si, (CH ₃ ) ₃ -Si-Si(CH ₃ ) ₃ and silicone oil.

Examples of fireproofing agents (flame retardants) include organic phosphates and phosphazene-based compounds. Examples of organic phosphates include fluorine-containing alkyl phosphates, non-fluorine-containing alkyl phosphates, and aryl phosphates. In order to achieve a flame-retardant effect even in a small amount, fluorine-containing alkyl phosphate is particularly preferable.

Examples of phosphazene-based compounds include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, Triphosphazene, ethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

Specific examples of fluorine-containing alkyl phosphates include fluorine-containing dialkyl phosphates disclosed in JP H11-233141 A, cyclic alkyl phosphates disclosed in JP H11-283669 A, and fluorine-containing trialkyl phosphates .

Preferable examples of flame retardants (flame retardants) include (CH ₃ O) ₃ P=O, (CF ₃ CH ₂ O) ₃ P=O, (HCF ₂ CH ₂ O) ₃ P=O, (CF ₃ CF ₂ CH ₂ ) ₃ P=O and (HCF ₂ CF ₂ CH ₂ ) ₃ P=O.

The surfactant may be any one of cationic surfactant, anionic surfactant, nonionic surfactant and amphoteric surfactant. In order to provide good cycle characteristics and rate characteristics, the surfactant is preferably a surfactant containing fluorine atoms.

Preferable examples of such surfactants containing fluorine atoms include fluorine-containing carboxylates represented by the following formula (30): Rf ⁵ COO ⁻ M ⁺ (30) (wherein Rf ⁵ is C3- C10 fluorine-containing alkyl group; M ⁺ is Li ⁺ , Na ⁺ , K ⁺ or NHR' ₃ ⁺ , wherein R' is the same or different from each other, and each is H or C1-C3 alkyl), and the following formula (40) The fluorine-containing sulfonate represented by: Rf ⁶ SO ₃ ^- M ⁺ (40) (wherein Rf ⁶ is a C3-C10 fluorine-containing alkyl group containing an ether bond as the case may be; M ⁺ is Li ⁺ , Na ⁺ , K ⁺ or NHR ' ₃ ⁺ , wherein R' are the same or different from each other, and each is H or C1-C3 alkyl).

In order to reduce the surface tension of the electrolytic solution without impairing charge and discharge cycle characteristics, the surfactant is preferably present in an amount of 0.01 to 2% by mass of the electrolytic solution.

Examples of additives for increasing permittivity include cyclobutane, methylcyclobutane, γ-butyrolactone, and γ-valerolactone.

烷。Examples of improvers of cycle characteristics and rate characteristics include methyl acetate, ethyl acetate, tetrahydrofuran, and 1,4-bis

alkyl.

The electrolyte solution of the present invention can be combined with a polymer material and thus formed into a gel-like (plasticized) gel electrolyte solution.

Examples of such polymer materials include known polyethylene oxide and polypropylene oxide and their modified products (see JP H08-222270 A, JP 2002-100405 A); polyacrylate-based polymers, polyacrylonitrile and Fluororesin, such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer (see JP H04-506726 T, JP H08-507407 T, JP H10-294131 A); and any of these fluorine resins Those and any compound of hydrocarbon resin (see JP H11-35765 A, JP H11-86630 A). Specifically, polyvinylidene fluoride or vinylidene fluoride-hexafluoropropylene copolymer is preferably used as the polymer material of the gel electrolyte.

The electrolytic solution of the present invention may also contain ion-conductive compounds disclosed in Japanese Patent Application No. 2004-301934.

This ion-conductive compound is an amorphous fluorine-containing polyether compound having a fluorine-containing group at a side chain and is represented by the following formula (101): A-(D)-B (101) wherein D is represented by the following formula (201) : -(D1) _n -(FAE) _m -(AE) _p -(Y) _q - (201) [wherein D1 is an ether unit containing a fluoroether group at the side chain and represented by the following formula (2a):

[chemical formula 76]

(wherein Rf is a fluorine-containing ether group optionally containing a crosslinkable functional group; and ^R10 is a group or bond connecting Rf and the main chain); FAE is an ether unit containing a fluorinated alkyl group at the side chain and consists of The following formula (2b) represents:

[chemical formula 77]

(wherein Rfa is a hydrogen atom or optionally a fluorinated alkyl group containing a crosslinkable functional group; and ^R is a group or bond connecting Rfa and the main chain); AE is an ether unit represented by the following formula (2c):

[chemical formula 78]

(wherein R ^is a hydrogen atom, an alkyl group optionally containing a crosslinkable functional group, an aliphatic cyclic hydrocarbon group optionally containing a crosslinkable functional group, or an aromatic hydrocarbon group optionally containing a crosslinkable functional group; and R ¹² is a group or bond connecting R ¹³ and the main chain); Y is a unit containing at least one of the following formulas (2d-1) to (2d-3):

[chemical formula 79]

n is an integer from 0 to 200; m is an integer from 0 to 200; p is an integer from 0 to 10000; q is an integer from 1 to 100; n+m is not 0; and The bonding sequence of D1, FAE, AE and Y is not specified]; and A and B are the same or different from each other, and each is a hydrogen atom, an alkyl group optionally containing a fluorine atom and/or a crosslinkable functional group, a phenyl group optionally containing a fluorine atom and/or a crosslinkable functional group, -COOH group, -OR (wherein R is a hydrogen atom or an alkyl group optionally containing a fluorine atom and/or a crosslinkable functional group), an ester group or a carbonate group, and when one end of D is an oxygen atom, Each of A and B is not a -COOH group, -OR, ester group and carbonate group.

The electrolyte solution of the present invention may contain a phosphorus-based compound. Preferred as the pyrene-based compound are C3-C6 cyclic pyrenes and C2-C6 acyclic pyrenes. The number of sulfonyl groups in one molecule is preferably 1 or 2.

Examples of cyclic thiols include monopyrone compounds such as trimethylene pyrone, tetramethylene pyridine, and hexamethylene pylon; Two. In order to provide good permittivity and viscosity, more preferred among these are tetramethylene phosphonium, tetramethylene diphosphonium, hexamethylene diphosphonium and hexamethylene diphosphonium, especially preferably tetramethylene phosphonium (Cyclotin).

Cyclobutane is preferably cyclobutane and/or cyclobutane derivatives (hereinafter also abbreviated as "cyclobutane", including cyclobutane). The cyclobutane derivatives are preferably those in which one or more hydrogen atoms bonded to any carbon atom constituting the cyclobutane ring are replaced with a fluorine atom or an alkyl group.

In order to achieve high ion conductivity and high input and output, preferred among these are 2-methylcyclobutane, 3-methylcyclobutane, 2-fluorocyclobutane, 3-fluorocyclobutane, 2 ,2-Difluorocyclobutane, 2,3-difluorocyclobutane, 2,4-difluorocyclobutane, 2,5-difluorocyclobutane, 3,4-difluorocyclobutane, 2 -Fluoro-3-methylcyclobutane, 2-fluoro-2-methylcyclobutane, 3-fluoro-3-methylcyclobutane, 3-fluoro-2-methylcyclobutane, 4-fluoro -3-Methylcyclobutane, 4-fluoro-2-methylcyclobutane, 5-fluoro-3-methylcyclobutane, 5-fluoro-2-methylcyclobutane, 2-fluoromethyl Cyclobutane, 3-fluoromethylcyclobutane, 2-difluoromethylcyclobutane, 3-difluoromethylcyclobutane, 2-trifluoromethylcyclobutane, 3-trifluoromethylcyclobutane Butane, 2-fluoro-3-(trifluoromethyl)cyclobutane, 3-fluoro-3-(trifluoromethyl)cyclobutane, 4-fluoro-3-(trifluoromethyl)cyclobutane , 3-cyclobutene, 5-fluoro-3-(trifluoromethyl)cyclobutene, and analogs thereof.

Examples of acyclic thiols include dimethyl ketone, ethyl methyl ketone, diethyl ketone, n-propyl methyl ketone, n-propyl ethyl ketone, di-n-propyl methyl ketone, isopropyl methyl ketone, Isopropyl ethyl ketone, diisopropyl ketone, n-butyl methyl ketone, n-butyl ethyl ketone, tertiary butyl methyl ketone, tertiary butyl ethyl ketone, monofluoromethyl methyl ketone, difluoromethane Difluoroethylmethylphosphonium, trifluoromethylmethylphosphonium, monofluoroethylmethylphosphonium, difluoroethylmethylphosphonium, trifluoroethylmethylphosphonium, pentafluoroethylmethylphosphonium, ethylmonofluoromethylphosphonium Ethyl phosphonium, ethyl difluoromethyl ketone, ethyl trifluoromethyl ketone, perfluoroethyl methyl ketone, ethyl trifluoroethyl ketone, ethyl pentafluoroethyl ketone, bis(trifluoroethyl) Phosphate, perfluorodiethylphenidium, fluoromethyl-n-propylphosphonium, difluoromethyl-n-propylphosphonium, trifluoromethyl-n-propylphosphonium, fluoromethyl-isopropylphosphonium, difluoromethyl Isopropyl Phenyl, Trifluoromethyl Isopropyl Pyrone, Trifluoroethyl-n-Propyl Pyrone, Trifluoroethyl Isopropyl Pyrone, Pentafluoroethyl-n-Propyl Pyrone, Pentafluoroethyl Isopropyl Phenyl trifluoroethyl-n-butylphosphonium, trifluoroethyl-tertiary butylphosphonium, pentafluoroethyl-n-butylphosphonium and pentafluoroethyl-tertiary butylphosphonium.

In order to achieve high ion conductivity and high input and output, preferred among these are dimethylphosphonium, ethylmethylphosphonium, diethylphosphonium, n-propylmethylphosphonium, isopropylmethylphosphonium, n-propylmethylphosphonium, Butylmethylphosphonium, tertiary butylmethylphosphonium, monofluoromethylmethylphosphonium, difluoromethylmethylphosphonium, trifluoromethylmethylphosphonium, monofluoroethylmethylphosphonium, difluoroethylmethylphosphonium, Trifluoroethylmethylphosphonium, pentafluoroethylmethylphosphonium, ethyl monofluoromethylphosphonium, ethyldifluoromethylphosphonium, ethyl trifluoromethylphosphonium, ethyltrifluoroethylmethylphosphonium, ethyl Pentafluoroethylphosphonium, trifluoromethyl-n-propylphosphonium, trifluoromethyl-isopropylphosphonium, trifluoroethyl-n-butylphosphonium, trifluoroethyl-tertiary butylphosphonium, trifluoromethyl -n-Butylphosphonium, trifluoromethyl-tertiary butylphosphonium and their analogues.

The phosphine-based compound may be present in any amount that does not significantly impair the effect of the present invention. Based on 100% by volume of solvent, the amount is usually 0.3% by volume or higher, preferably 0.5% by volume or higher, more preferably 1% by volume or higher, while usually 40% by volume or lower, preferably 35% by volume % by volume or lower, more preferably 30% by volume or lower. The phosphine-based compound in an amount within the above range can easily achieve the effects of improving cycle characteristics and durability such as storage characteristics, can produce an appropriate viscosity range of a non-aqueous electrolyte solution, can eliminate a decrease in conductivity, and can produce non-aqueous electrolytic solutions. Appropriate ranges of input and output characteristics and charge and discharge rate characteristics of aqueous electrolyte secondary batteries.

In order to improve the output characteristics, the electrolytic solution of the present invention also preferably contains compound ( ₇ ) as an additive, and the compound is at least one. When the compound (7) is used as an additive, the above electrolyte salt is preferably a compound other than the compound (7).

Examples of lithium fluorophosphate include lithium monofluorophosphate (LiPO ₃ F) and lithium difluorophosphate (LiPO ₂ F ₂ ). Examples of lithium salts containing S=O groups include lithium monofluorosulfonate (FSO ₃ Li), lithium methyl sulfate (CH ₃ OSO ₃ Li), lithium ethyl sulfate (C ₂ H ₅ OSO ₃ Li), and sulfuric acid Lithium 2,2,2-trifluoroethyl ester. Among them, preferred compounds (7) are LiPO ₂ F ₂ , FSO ₃ Li and C ₂ H ₅ OSO ₃ Li.

Compound (7) is preferably present in an amount of 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, still more preferably 0.1 to 10% by mass, especially preferably 0.1 to 7% by mass, relative to the electrolyte solution.

The electrolytic solution of the present invention may further contain various additives as necessary. Examples of different additives include metal oxides and glasses.

The electrolyte solution of the present invention preferably contains 1 to 1000 ppm hydrogen fluoride (HF). The presence of HF can promote the formation of the film of the aforementioned additives. An excessively small amount of HF tends to impair the ability to form a film on the negative electrode, thereby impairing the characteristics of the electrochemical device. An excessive amount of HF tends to impair the oxidation resistance of the electrolyte solution due to the influence of HF. Even when HF is contained in an amount within the above range, the electrolytic solution of the present invention does not cause weakening of capacity recovery of electrochemical devices after high-temperature storage. The amount of HF is more preferably 5 ppm or more, still more preferably 10 ppm or more, especially preferably 20 ppm or more. The amount of HF is also more preferably 200 ppm or less, further preferably 100 ppm or less, further preferably 80 ppm or less, especially preferably 50 ppm or less. The amount of HF can be determined by neutralization titration.

The electrolyte solution of the present invention is preferably prepared by any method using the aforementioned components.

The electrolytic solution of the present invention can be suitably applied to electrochemical devices such as lithium ion secondary batteries, lithium ion capacitors, hybrid capacitors, and electric double layer capacitors. Hereinafter, a nonaqueous electrolyte battery comprising the electrolyte solution of the present invention is described. The nonaqueous electrolyte battery may have a known structure and typically includes a positive electrode and a negative electrode capable of occluding and releasing ions such as lithium ions, and the electrolytic solution of the present invention. Such an electrochemical device including the electrolyte solution of the present invention is also an aspect of the present invention.

Examples of electrochemical devices include lithium ion secondary batteries, lithium ion capacitors, capacitors (such as hybrid capacitors and electric double layer capacitors), radical batteries, solar cells (especially dye-sensitized solar cells), lithium ion primary batteries, fuel cells , Various electrochemical sensors, electrochromic components, electrochemical exchange components, aluminum electrolytic capacitors and tantalum electrolytic capacitors. Preferred are lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors. A module including an electrochemical device is also an aspect of the present invention.

The present invention also relates to a lithium ion secondary battery comprising the electrolyte solution of the present invention. A lithium ion secondary battery preferably includes a positive electrode, a negative electrode, and the above electrolyte solution.

＜Positive electrode＞ The positive electrode includes a positive electrode active material layer containing a positive electrode active material and a current collector.

The positive electrode active material can be any material that can electrochemically occlude and release lithium ions. Examples thereof include lithium-containing transition metal composite oxides, lithium-containing transition metal phosphate compounds, sulfur-based materials, and conductive polymers. Among these, preferred as positive electrode active materials are lithium-containing transition metal composite oxides and lithium-containing transition metal phosphate compounds. Especially preferred are lithium-containing transition metal composite oxides that generate high voltage.

The transition metal of the lithium-containing transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu or the like. Specific examples thereof include lithium cobalt composite oxides (such as LiCoO ₂ ), lithium nickel composite oxides (such as LiNiO ₂ ), lithium manganese composite oxides (such as LiMnO ₂ , LiMn ₂ O ₄ and Li ₂ MnO ₄ ), and by With another element (such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn or W) Those obtained by substituting some of the transition metal atoms which are the main components of these lithium transition metal composite oxides. Specific examples of those composite oxides obtained by substitution include LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _{0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.6} Co _0.2 Mn _0.2 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.45 Co _0.10 Al _0.45 O ₂ , LiMn _1.8 Al _0.2 O ₄ and LiMn _1.5 Ni _0.5 O ₄ .

The lithium-containing transition metal composite oxide is preferably any one of LiMn _1.5 Ni _0.5 O ₄ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , each of which has high Energy Density. In the case of a high voltage of 4.4 V or higher, LiMn _1.5 Ni _0.5 O ₄ is preferable.

In order to provide a high-capacity lithium ion secondary battery, LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , and LiNi _0.85 Co _0.10 Al _0.05 O ₂ are preferable among lithium-containing transition metal composite oxides.

The transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu or the like. Specific examples thereof include iron phosphate (such as LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ and LiFeP ₂ O ₇ ), cobalt phosphate (such as LiCoPO ₄ ), and by using another element (such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb or Si) are obtained by substituting some of the transition metal atoms which are the main components of these lithium transition metal phosphate compounds. wait.

Examples of lithium-containing transition metal composite oxides include lithium manganese spinel composite oxides represented by the following formula: Li _a Mn _2-b M ¹ _b O ₄ (where 0.9≦a; 0≦b≦1.5; and M ¹ is at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge), consisting of Lithium-nickel composite oxide represented by the following formula: LiNi _1-c M ² _c O ₂ (where 0≦c≦0.5; and M ² is at least one metal selected from the group consisting of: Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge), and lithium cobalt composite oxide represented by the following formula: LiCo _1-d M ³ _d O ₂ (where 0≦d≦0.5; and ^M3 is at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B , Ga, In, Si and Ge).

In order to provide high-power lithium-ion secondary batteries with high energy density, LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ or LiNi _1/3 Co _1/3 Mn are preferred _1/3 O ₂ .

Other examples of positive electrode active materials include LiFePO ₄ , LiNi _0.8 Co _0.2 O ₂ , Li _1.2 Fe _0.4 Mn _0.4 O ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiV ₃ O ₆ , and Li ₂ MnO ₃ .

Examples of sulfur-based materials include materials containing sulfur atoms. Preferably it is at least one selected from the group consisting of elemental sulfur, metal sulfides and organic sulfur compounds, more preferably elemental sulfur. The metal sulfides may be metal polysulfides. The organic sulfur compound may be an organic polysulfide.

Examples of metal sulfides include compounds represented by LiS _x (0<x≦8), compounds represented by Li ₂ S _x (0<x≦8), compounds having a 2D layered structure such as TiS ₂ and MoS ₂ ) and chevrel compounds with a strong 3D framework structure, such as those represented by the following formula: Me _x Mo ₆ S ₈ (where Me is a transition metal such as Pb, Ag or Cu).

Examples of organic sulfur compounds include sulfurized carbon compounds.

Each of the organosulfur compounds can be supported on a material having pores such as carbon, and thus be used as a carbon composite material. In order to provide much better cycle performance and further reduce overvoltage, relative to the mass of the carbon composite material, the amount of sulfur contained in the carbon composite material is preferably 10 to 99% by mass, more preferably 20% by mass or higher, and then More preferably 30% by mass or more, especially preferably 40% by mass or more, while preferably 85% by mass or less. In the case where the positive electrode active material is elemental sulfur, the amount of sulfur contained in the positive electrode active material is equal to the amount of elemental sulfur contained.

Examples of conductive polymers include p-doped conductive polymers and n-doped conductive polymers. Examples of conductive polymers include polyacetylene-based polymers, polyphenylene-based polymers, heterocyclic polymers, ionic polymers, ladder polymers, and network polymers.

In order to improve continuous charge characteristics, the positive electrode active material preferably contains lithium phosphate. Lithium phosphate can be used in any manner, and is preferably blended with the positive electrode active material. The lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, relative to the sum of the amounts of the positive electrode active material and lithium phosphate. The upper limit thereof is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 5% by mass or less.

A substance having a composition different from that of the positive electrode active material may be attached to the surface of the positive electrode active material. Examples of substances attached to surfaces include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, sulfuric acid Potassium, magnesium, calcium, and aluminum sulfates; carbonates, such as lithium, calcium, and magnesium carbonates; and carbon.

Such substances can be attached to the surface of the positive electrode active material by, for example, methods of dissolving or suspending the substance in a solvent, impregnating the solution or suspension into the positive electrode active material, and drying the impregnated material; A method of dissolving or suspending a precursor in a solvent, impregnating the solution or suspension into a positive electrode active material, and heating the material and the precursor to cause a reaction therebetween; or adding a substance to the precursor of the positive electrode active material and A method of simultaneously sintering materials. In the case of attached carbon, the carbonaceous material, for example in the form of activated carbon, can then be mechanically attached to the surface.

For the amount of the substance attached to the surface in terms of mass relative to the amount of the positive electrode active material, the lower limit is preferably 0.1 ppm or higher, more preferably 1 ppm or higher, still more preferably 10 ppm or higher, And its upper limit is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less. Substances attached to the surface can reduce oxidation of the electrolyte solution on the surface of the positive electrode active material, thereby improving battery life. Too small an amount of substance may not sufficiently provide this effect. Excessive amounts may hinder the entry and exit of lithium ions, thereby increasing resistance.

The particles of the positive electrode active material may have any shape conventionally used, such as a bulk shape, a polyhedral shape, a spherical shape, an ellipsoidal shape, a plate shape, a needle shape or a cylindrical shape. Primary particles can coalesce to form secondary particles.

The tap density of the positive electrode active material is usually 1.5 g/cm ³ or higher, preferably 2.0 g/cm ³ or higher, more preferably 2.5 g/cm ³ or higher, most preferably 3.0 g/cm ³ or higher high. A positive electrode active material with a compaction density lower than the lower limit can lead to an increase in the amount of dispersion medium required to form a positive electrode active material layer and an increase in the amount of conductive materials and binders required, and limit the positive electrode activity in the positive electrode active material layer. The filling fraction of the material leads to the limitation of the battery capacity. The metal composite oxide powder with high tap density enables the formation of a positive electrode active material layer with high density. Tapping is generally preferred to be as high as possible, with no upper limit. The upper limit thereof is usually 4.5 g/cm ³ or lower, preferably 4.3 g/cm ³ or lower. In the present invention, the tap density is measured as the powder packing density (tap density) when 5 to 10 g of positive electrode active material powder is charged into a 10 ml glass graduated cylinder and the graduated cylinder is tapped 200 times with a stroke of about 20 mm g/cm ³ .

The median diameter d50 (or the secondary particle diameter when the primary particles coalesce to form secondary particles) of the particles of the positive electrode active material is preferably 0.3 μm or greater, more preferably 0.5 μm or greater, even more preferably 0.8 μm or more, preferably 1.0 μm or more, preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, most preferably 22 μm or less. Particles with a median particle size below the lower limit may not provide a product with high tap density. Particles with a median particle size larger than the upper limit may lead to prolonged diffusion of lithium in the particles, impairing battery performance and in the formation of the positive electrode of the battery (i.e., when the active material and components such as conductive materials and binders are When formed as a slurry and the slurry is applied, for example, in the form of a film) streaks are produced. Mixing two or more positive electrode active materials having different median particle diameters d50 can further improve the ease of loading in positive electrode formation.

In the present invention, the median particle diameter d50 is measured using a known laser diffraction/scattering particle size distribution analyzer. In the case of using LA-920 (Horiba Co., Ltd.) as the particle size distribution analyzer, the dispersion medium used in the measurement is a 0.1% by mass sodium hexametaphosphate aqueous solution and the refractive index measured after 5 minutes of ultrasonic dispersion is set to 1.24.

When primary particles coalesce to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or larger, more preferably 0.1 μm or larger, still more preferably 0.2 μm or larger. The upper limit thereof is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, most preferably 2 μm or less. Primary particles having an average primary particle diameter larger than the upper limit may be difficult to form spherical secondary particles, thereby adversely affecting powder loading. In addition, the specific surface area of such primary particles may be greatly reduced, possibly impairing battery performance such as output characteristics. In contrast, primary particles having an average primary particle size below the lower limit may generally be insufficiently grown crystals, resulting in poor charge and discharge reversibility, for example.

In the present invention, the primary particle size is measured by scanning electron microscopy (SEM) observation. Specifically, the primary particle size is measured as follows. First take a photo with a magnification of 10000×. Select any 50 primary particles and measure the maximum length between the left and right boundary lines of each primary particle along the horizontal line. Next, the average value of the maximum length was calculated, which was defined as the primary particle diameter.

The BET specific surface area of the positive electrode active material is preferably 0.1 m ² /g or greater, more preferably 0.2 m ² /g or greater, still more preferably 0.3 m ² /g or greater. The upper limit thereof is preferably 50 m ² /g or less, more preferably 40 m ² /g or less, still more preferably 30 m ² /g or less. A positive electrode active material with a BET specific surface area smaller than the above range may easily impair battery performance. A positive electrode active material with a BET specific surface area greater than the above range may be less likely to have increased compaction, thereby easily causing difficulty in applying materials in the formation of the positive electrode active material layer.

In the present invention, the BET specific surface area is defined by the value measured by single-point BET nitrogen adsorption using the air flow method using a surface area analyzer (such as a fully automatic surface area measuring device, Ohkura Riken Co., Ltd.), under nitrogen gas Samples pre-dried at 150°C for 30 minutes and a nitrogen-helium gas mixture in a flow where the nitrogen pressure is precisely adjusted to 0.3 relative to atmospheric pressure.

When the lithium ion secondary battery of the present invention is used as a large lithium ion secondary battery for hybrid vehicles or distributed power generation, it is required to achieve high output. Therefore, the particles of the positive electrode active material are preferably composed mainly of secondary particles. The particles of the positive electrode active material preferably include 0.5 to 7.0% by volume of fine particles having an average secondary particle diameter of 40 μm or less and an average primary particle diameter of 1 μm or less. The presence of fine particles with an average primary particle size of 1 μm or less expands the contact area with the electrolyte solution, and enables lithium ions to diffuse more rapidly between the electrode and the electrolyte solution, thereby improving the output performance of the battery.

The positive electrode active material can be produced by any usual method for producing inorganic compounds. In particular, spherical or ellipsoidal active materials can be fabricated by various methods. For example, the transition metal material substance is dissolved or crushed and dispersed in a solvent such as water, and the pH of the solution or dispersion is adjusted under stirring to form a spherical precursor. The precursor is recovered and dried if necessary. Next, a Li source such as LiOH, Li ₂ CO ₃ , or LiNO ₃ is added thereto, and the mixture is sintered at a high temperature, thereby providing an active material.

In the production of the positive electrode, one of the aforementioned positive electrode active materials may be used alone, or two or more of them having different compositions may be used in any combination in any ratio. In this case, preferred examples of the combination include a combination of LiCoO ₂ and LiMn ₂ O ₄ , in which a part of Mn may be replaced by different transition metals (such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ ), and a combination with LiCoO ₂ , A part of Co may be replaced by different transition metals as appropriate.

In order to achieve a high battery capacity, the amount of the positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, more preferably 80 to 99% by mass. The amount of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, especially preferably 84% by mass or more. The upper limit thereof is preferably 99% by mass or less, more preferably 98% by mass or less. An excessively small amount of the positive electrode active material in the positive electrode active material layer may result in insufficient capacitance. In contrast, an excessive amount thereof may result in insufficient positive electrode strength.

The positive electrode mixture preferably further contains a binder, a thickener and a conductive material. The binder can be any material that is not affected by the solvents to be used in the manufacture of electrodes and electrolyte solutions. Examples thereof include resinous polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethylmethacrylate, aramid, chitosan, alginic acid, polyacrylic acid, polyamide Amines, cellulose, and nitrocellulose; rubbery polymers such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, fluoroelastomers, acrylonitrile- Butadiene rubber (acrylonitrile-butadiene rubber; NBR) and ethylene-propylene rubber; styrene-butadiene-styrene block copolymers and their hydrogenated products; thermoplastic elastic polymers, such as ethylene-propylene-diene terpolymers Copolymers (ethylene-propylene-diene terpolymer; EPDM), styrene-ethylene-butadiene-styrene copolymers and styrene-isoprene-styrene block copolymers and their hydrogenated products; soft resin polymers , such as p-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; fluoropolymers, such as polyvinylidene fluoride, polytetrafluoroethylene , vinylidene fluoride copolymers and tetrafluoroethylene-ethylene copolymers; and polymer compositions with ion conductivity of alkali metal ions (especially lithium ions). One of these may be used alone, or two or more of them may be used in any combination in any ratio.

The amount of the binder expressed as the ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more. The ratio is also usually 80% by mass or less, preferably 60% by mass or less, still more preferably 40% by mass or less, most preferably 10% by mass or less. Too low a ratio of the binder may fail to sufficiently hold the positive electrode active material and result in insufficient mechanical strength of the positive electrode, thereby impairing battery performance such as cycle characteristics. In contrast, an excessively high ratio can lead to a decrease in battery capacity and conductivity.

Examples of thickeners include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, simple starch phosphate, casein, polyvinylpyrrolidone and salts thereof . One of these agents may be used alone, or two or more of them may be used in any combination in any ratio.

The ratio of the thickener to the active material is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, while usually 5% by mass or less, preferably 3% by mass % or lower, more preferably 2% by mass or lower. Thickeners in proportions below the above ranges can result in significantly poorer ease of application. A thickener at a ratio higher than the above range may result in a low ratio of active materials in the positive electrode active material layer, resulting in low battery capacity and high resistance between positive electrode active materials.

The conductive material can be any known conductive material. Specific examples thereof include metal materials such as copper and nickel, and carbon materials such as graphite (including natural graphite and artificial graphite), carbon black (including acetylene black, Ketjen black, channel black, furnace black, lamp black and hot black) and amorphous carbon (including needle coke), carbon nanotubes, Fu and VGCF. One of these materials may be used alone, or two or more of them may be used in any ratio in any combination. In the positive electrode active material layer, the amount of the conductive material is usually 0.01% by mass or higher, preferably 0.1% by mass or higher, more preferably 1% by mass or higher, and usually 50% by mass or lower, preferably 0.1% by mass or higher. Preferably 30% by mass or less, more preferably 15% by mass or less. The conductive material in an amount smaller than the above range may result in insufficient conductivity. In contrast, a conductive material in an amount greater than the above range may result in low battery capacity.

The solvent used to form the slurry may be any solvent that can dissolve or disperse therein the positive electrode active material, conductive material, and binder, and optionally a thickener. The solvent may be an aqueous solvent or an organic solvent. Examples of aqueous media include water and solvent mixtures of alcohols and water. Examples of organic media include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclic Hexanone; Esters, such as methyl acetate and methyl acrylate; Amines, such as diethylenetriamine and N,N-dimethylaminopropylamine; Ethers, such as diethyl ether, propylene oxide and tetrahydrofuran (tetrahydrofuran; THF); Amides, such as N-methylpyrrolidone (N-methylpyrrolidone; NMP), dimethylformamide, and dimethylacetamide; and aprotic polar solvents, such as hexamethylphosphoramide and dimethylimide碸.

Examples of materials for the current collector of the positive electrode include metallic materials such as aluminum, titanium, tantalum, stainless steel, and nickel and alloys thereof; and carbon materials such as carbon cloth and carbon paper. Any metallic material is preferred, especially aluminum or its alloys.

In the case of metallic materials, the current collector may be in the form of a metal foil, metal cylinder, metal coil, metal plate, metal film, expanded metal plate, stamped metal, foamed metal or the like. In the case of carbon materials, this may be in the form of carbon plates, carbon films, carbon cylinders or the like. Preferred among these is a metal film. The membrane may be in the form of a net if desired. The film may have any thickness, and the thickness is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, while usually 1 mm or less, preferably 100 μm or less, more Preferably 50 μm or less. A film having a thickness smaller than the above range may have insufficient strength as a current collector. In contrast, a film having a thickness greater than the above range may have poor handling properties.

In order to reduce the electrical contact resistance between the current collector and the positive electrode active material layer, the current collector also preferably has a conductive aid applied on its surface. Examples of conductive aids include carbon and noble metals such as gold, platinum and silver.

The ratio between the thickness of the current collector and the positive electrode active material layer may be any value, and the ratio {(thickness of the positive electrode active material layer on the side immediately before injection of the electrolytic solution)/(thickness of the current collector)} is preferable 20 or lower, better 15 or lower, best 10 or lower. The ratio is also preferably 0.5 or higher, more preferably 0.8 or higher, most preferably 1 or higher. A current collector and a positive electrode active material layer exhibiting a ratio higher than the above range may cause the current collector to generate heat due to Joule heating during high current density charge and discharge. A current collector and positive electrode active material layer exhibiting a ratio below the above range may result in an increase in the volume ratio of the current collector to the positive electrode active material, thereby reducing battery capacity.

The positive electrode can be produced by a usual method. An example of the manufacturing method is a method in which a positive electrode active material is mixed with the aforementioned binder, thickener, conductive material, solvent, and other components to form a slurry-like positive electrode mixture, and then this mixture is applied to a current collector , dried, and pressed for densification.

For example, compaction can be achieved using a hand press or a roller press. The density of the positive electrode active material layer is preferably 1.5 g/cm ³ or higher, more preferably 2 g/cm ³ or higher, still more preferably 2.2 g/cm ³ or higher, and more preferably 5 g/cm ³ or lower, more preferably 4.5 g/cm ³ or lower, more preferably 4 g/cm ³ or lower. A positive electrode active material layer with a density higher than the above range may result in low permeability of the electrolyte solution toward the vicinity of the interface between the current collector and the active material, and poor charge and discharge characteristics especially at high current densities, thereby failing to provide high output . A positive electrode active material layer having a density lower than the above range may cause poor conductivity between active materials and increase battery resistance, thereby failing to provide high output.

In order to improve stability at high output and high temperature in the case of using the electrolytic solution of the present invention, the area of the positive electrode active material layer is preferably large relative to the external area of the case of the battery. Specifically, the total area of the positive electrode is preferably 15 times or more, more preferably 40 times or more, larger than the outer surface area of the case of the secondary battery. For a closed square case, the outer surface area of the case of the battery herein means the total area calculated from the dimensions of the length, width and thickness of the part of the case enclosing the power generating element, excluding the protruding part of the terminal. For a closed cylindrical case, the outer surface area of the case of the battery herein means the geometrical surface area of the approximate cylinder of the case portion enclosing the power generating element except for the protruding portion of the terminal. The total area of the positive electrode herein means the geometrical surface area of the positive electrode mixture layer opposite to the mixture layer including the negative electrode active material. For structures comprising a current collector foil and a positive electrode mixture layer on both sides of the current collector, the total area of the positive electrode is the sum of the calculated areas on the respective sides.

The positive electrode plate can have any thickness. In order to achieve high capacity and high output, in addition to the thickness of the base metal foil, the lower limit of the thickness of the mixture layer on the collector side is preferably 10 μm or more, more preferably 20 μm or more, and more preferably 500 μm or less, more preferably 450 μm or less.

A substance having a composition different from that of the positive electrode plate may be attached to the surface of the positive electrode plate. Examples of substances attached to surfaces include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, sulfuric acid Potassium, magnesium, calcium, and aluminum sulfates; carbonates, such as lithium, calcium, and magnesium carbonates; and carbon.

＜Negative electrode＞ The negative electrode includes a negative electrode active material layer containing a negative electrode active material and a current collector.

The negative electrode material can be any material that can electrochemically store and release lithium ions. Specific examples thereof include carbon materials, alloy materials, lithium-containing metal composite oxide materials, and conductive polymers. One of these may be used alone, or two or more of them may be used in any combination.

Examples of negative electrode active materials include carbonaceous materials that can occlude and release lithium, such as pyrolysis products of organic matter under various pyrolysis conditions, artificial graphite and natural graphite; metal oxide materials that can occlude and release lithium, such as Tin oxide and silicon oxide; lithium metal; various lithium alloys; and lithium-containing metal composite oxide materials. Two or more of these negative electrode active materials may be blended with each other for use.

The carbonaceous material that can occlude and release lithium is preferably artificial graphite produced by high-temperature treatment of easily graphitizable pitch from various materials, purified natural graphite, or by treating such graphite with pitch or other organic substances. Material obtained by surface treatment and subsequent carbonization of surface treated graphite. In order to achieve a good balance between initial irreversible capacity and high current density charge and discharge characteristics, the carbonaceous material is preferably selected from natural graphite, artificial graphite, artificial carbonaceous substance or artificial graphite substance at 400°C to 3200°C A carbonaceous material obtained by performing one or more heat treatments; the negative electrode active material layer is allowed to include at least two or more carbonaceous substances with different crystallinity and/or between carbonaceous substances with different crystallinity A carbonaceous material having an interface; and a carbonaceous material allowing the negative electrode active material layer to have an interface between at least two or more carbonaceous substances having different orientations. One of these carbonaceous materials may be used alone, or two or more of them may be used in any ratio in any combination.

Carbonaceous materials obtained by one or more thermal treatments of artificial carbonaceous substances or artificial graphite substances at 400°C to 3200°C include coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based Pitches and those prepared by oxidation of these pitches; needle cokes, pitch cokes and carbon materials prepared by partial graphitization of these cokes; pyrolysis products of organic matter such as furnace black, acetylene black and carbon fibers based on pitches ; carbonizable organic substances and carbides thereof; and solutions prepared by dissolving carbonizable organic substances in low molecular weight organic solvents such as benzene, toluene, xylene, quinoline or n-hexane, and carbides thereof.

The metal material (excluding lithium-titanium composite oxide) to be used as the negative electrode active material may be any compound that can occlude and release lithium, and examples thereof include pure lithium, pure metals and alloys constituting lithium alloys, and oxidized compounds, carbides, nitrides, silicides, sulfides and phosphides. Pure metals and alloys constituting lithium alloys are preferably materials containing any one of the metals and semi-metal elements of Group 13 and Group 14, more preferably aluminum, silicon and tin (hereinafter referred to as "specific metal elements" ) of pure metals and alloys and compounds containing any of these atoms. One of these materials may be used alone, or two or more of them may be used in combination in any ratio.

Examples of the negative electrode active material containing at least one atom selected from specific metal elements include pure metals of any specific metal element, alloys of two or more specific metal elements, one or two or more specific metal elements Alloys of one or two or more other metal elements, compounds and composite compounds containing one or two or more specific metal elements, such as oxides, carbides, nitrides, silicides, and sulfides of compounds and phosphides. Such pure metals, alloys or metal compounds used as negative electrode active materials can lead to high capacity batteries.

Examples thereof further include compounds in which any one of the above complex compounds is zigzag-bonded with several elements, such as pure metals, alloys, and non-metallic elements. In particular, in the case of eg silicon or tin, alloys of this element and metals which do not act as negative electrodes can be used. For example, in the case of tin, a complex compound may be used that includes a combination of 5 or 6 elements including tin, metals that serve as negative electrodes (excluding silicon), metals that do not serve as negative electrodes, and non-metallic elements.

Specific examples thereof include pure Si, SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi _{2 , MoSi 2 ,} CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₆ Si, FeSi ₂ , MnSi ₂ , NbSi _2. TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0<v≦2), LiSiO, pure tin, SnSiO ₃ , LiSnO, Mg ₂ Sn and SnO _w (0<w≦2). Examples thereof further include a composite material of Si or Sn serving as the first constituent element and the second and third constituent elements. For example, the second constituent element is at least one selected from the group consisting of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, and zirconium. For example, the third constituent element is at least one member selected from the group consisting of boron, carbon, aluminum and phosphorus. In order to achieve high battery capacity and excellent battery characteristics, the metal material is preferably pure silicon or tin (which may contain trace impurities), SiOv (0<v≦2), SnOw (0≦w≦2), Si-Co -C composite material, Si-Ni-C composite material, Sn-Co-C composite material or Sn-Ni-C composite material.

The lithium-containing metal composite oxide material to be used as the negative electrode active material may be any material that can occlude and release lithium. In order to achieve good high current density charge and discharge characteristics, preferably a material containing titanium and lithium, more preferably a lithium-containing metal composite oxide material containing titanium, and even more preferably a composite oxide of lithium and titanium (hereinafter abbreviated as "lithium-titanium composite oxide"). In other words, use of a spinel-structured lithium-titanium composite oxide in the negative electrode active material for an electrolyte battery is particularly preferable because it can significantly reduce output resistance.

Preferred examples of lithium-titanium composite oxides include compounds represented by the following formula: Li _x Ti _y M _z O ₄ wherein M is at least one element selected from the group consisting of: Na, K, Co, Al, Fe, Ti , Mg, Cr, Ga, Cu, Zn and Nb. In order to achieve a good balance of battery performance, among the above compositions, it is particularly preferred to satisfy any of the following compositions: (i) 1.2≦x≦1.4, 1.5≦y≦1.7, z=0 (ii) 0.9 ≦x≦1.1, 1.9≦y≦2.1, z=0 (iii) 0.7≦x≦0.9, 2.1≦y≦2.3, z=0.

Particularly preferred representative compositions of the compound are Li _4/3 Ti _5/3 O ₄ corresponding to composition (i), Li 1 Ti 2 O 4 corresponding to composition (ii) and Li ₁ Ti ₂ O ₄ corresponding to composition (iii) ) of Li _4/5 Ti _11/5 O ₄ . Preferable examples of the structure satisfying Z≠0 include Li _4/3 Ti _4/3 Al _1/3 O ₄ .

The negative electrode mixture preferably further contains a binder, a thickener and a conductive material.

Examples of the binder include the same binders as those mentioned for the positive electrode. Relative to the negative electrode active material, the ratio of the binder is preferably 0.1% by mass or higher, more preferably 0.5% by mass or higher, especially preferably 0.6% by mass or higher, while preferably 20% by mass or lower, More preferably 15% by mass or less, still more preferably 10% by mass or less, especially preferably 8% by mass or less. A binder whose ratio relative to the negative electrode active material is higher than the above range may result in an increased ratio of the binder, which cannot contribute to the battery capacity, resulting in low battery capacity. A binder with a ratio lower than the above range may result in a decrease in the strength of the negative electrode.

Specifically, in the case of using a rubber-like polymer typified by SBR as a main component, the ratio of the binder is usually 0.1% by mass or more, preferably 0.5% by mass or more, relative to the negative electrode active material High, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. In the case of using a fluoropolymer typified by polyvinylidene fluoride as a main component, the ratio of the binder to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more , more preferably 3% by mass or more, while usually 15% by mass or less, preferably 10% by mass or less, more preferably 8% by mass or less.

Examples of the thickener include the same thickeners as those mentioned for the positive electrode. Relative to the negative electrode active material, the ratio of the thickener is usually 0.1% by mass or higher, preferably 0.5% by mass or higher, more preferably 0.6% by mass or higher, while usually 5% by mass or lower, It is preferably 3% by mass or less, more preferably 2% by mass or less. A thickener whose ratio relative to the negative electrode active material is lower than the above range may result in markedly poor ease of application. A thickener having a ratio higher than the above range may result in a small ratio of the negative electrode active material in the negative electrode active material layer, resulting in low battery capacity and high resistance between the negative electrode active materials.

Examples of the conductive material of the negative electrode include metal materials such as copper and nickel; and carbon materials such as graphite and carbon black.

The solvent used to form the slurry may be any solvent that can dissolve or disperse the negative electrode active material and binder, and optionally a thickener and conductive material. The solvent may be an aqueous solvent or an organic solvent. Examples of aqueous solvents include water and alcohols. Examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyl triamine, N,N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphoramide, dimethylsulfoxide, benzene, di Toluene, quinoline, pyridine, methylnaphthalene and hexane.

Examples of materials for the current collector of the negative electrode include copper, nickel, and stainless steel. Copper foil is preferred for ease of processing the material into films and to minimize cost.

The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, while usually 100 μm or less, preferably 50 μm or less. Too thick a negative electrode current collector can lead to an undue reduction in the capacity of the overall battery, while too thin a current collector can be difficult to handle.

The negative electrode can be produced by a usual method. An example of a manufacturing method is a method in which a negative electrode material is mixed with the aforementioned binder, thickener, conductive material, solvent, and other components to form a slurry-like mixture, and then this mixture is applied to a current collector, dried, and pressed for densification. In the case of using an alloy material, a thin film layer (negative electrode active material layer) containing the above negative electrode active material can be produced by vapor deposition, sputtering, electroplating or the like.

The electrode formed from the negative electrode active material may have any structure. The density of the negative electrode active material present on the current collector is preferably 1 g·cm ⁻³ or higher, more preferably 1.2 g·cm ⁻³ or higher, especially preferably 1.3 g·cm ⁻³ or higher, At the same time, preferably 2.2 g·cm ^-3 or lower, more preferably 2.1 g·cm ^-3 or lower, more preferably 2.0 g·cm ^-3 or lower, especially preferably 1.9 g·cm ^-3 or lower . The negative electrode active material present on the current collector with a density higher than the above range may cause destruction of the negative electrode active material particles, resulting in high initial Irreversible capacity and poor high current density charge and discharge characteristics. A negative electrode active material having a density lower than the above range may result in poor electrical conductivity between the negative electrode active materials, high battery resistance, and low capacity per unit volume.

The thickness of the negative electrode plate is a matter of design according to the positive electrode plate to be used, and may be any value. The thickness of the mixture layer excluding the thickness of the base metal foil is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, while usually 300 μm or less, preferably 280 μm or Smaller, preferably 250 μm or smaller.

A substance having a composition different from that of the negative electrode plate may be attached to the surface of the negative electrode plate. Examples of substances attached to surfaces include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, sulfuric acid Potassium, magnesium sulfate, calcium sulfate, and aluminum sulfate; and carbonates, such as lithium carbonate, calcium carbonate, and magnesium carbonate.

＜Partition＞ The lithium ion secondary battery of the present invention preferably further includes a separator. The separator may be formed of any known material and may have any known shape as long as the resulting separator is stable to the electrolytic solution and excellent in liquid retaining ability. The separator is preferably in the form of a porous sheet or non-woven fabric formed of a material that is stable to the electrolyte solution of the present invention, such as resin, glass fiber, or inorganic, and has excellent liquid retention capacity.

Examples of materials for resin or fiberglass separators include polyolefins such as polyethylene and polypropylene, aramid, polytetrafluoroethylene, polyether sulfide, and glass filters. One of these materials can be used alone, or two or more can be used in any combination in any ratio, such as polypropylene/polyethylene double layer film or polypropylene/polyethylene/polypropylene triple layer film form. In order to achieve good permeability of electrolyte solution and good shut-off effect, the separator is preferably a porous sheet or non-woven fabric formed of polyolefin such as polyethylene or polypropylene.

The separator may have any thickness, and the thickness is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, while usually 50 μm or less, preferably 40 μm or less, More preferably 30 μm or less. A separator thinner than the above range may have poor insulation and mechanical strength. A separator thicker than the above range may not only result in poor battery performance, such as poor rate characteristics, but may also result in low energy density of the entire electrolyte battery.

The separator as a porous separator such as a porous sheet or non-woven fabric may have any porosity. The porosity is usually 20% or higher, preferably 35% or higher, more preferably 45% or higher, while usually 90% or lower, preferably 85% or lower, more preferably 75% or lower . Separators with porosity below the above range tend to have high membrane resistance, resulting in poor rate characteristics. A separator with a porosity higher than the above range tends to have low mechanical strength, resulting in poor insulation.

The separator can also have any average pore size. The average pore size is usually 0.5 μm or less, preferably 0.2 μm or less, while usually 0.05 μm or more. Separators with an average pore size larger than the above range may easily cause short circuits. A separator with an average pore size smaller than the above range may have high membrane resistance, resulting in poor rate characteristics.

Examples of inorganic substances include oxides, such as aluminum oxide and silicon dioxide; nitrides, such as aluminum nitride and silicon nitride; and sulfates, such as barium sulfate and calcium sulfate, each in particle or fiber form.

The separator is in the form of a film, such as a non-woven, woven or microporous membrane. The membrane advantageously has a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm. Instead of the above independent film, the separator may have a structure in which a composite porous layer containing particles of the above inorganic substance is disposed on the surface of one or each of the positive electrode and the negative electrode using a resin binder. For example, alumina particles with 90% particle diameters less than 1 μm can be applied to the respective surfaces of the positive electrode using a fluororesin used as a binder to form a porous layer.

＜Battery Design＞ The electrode group may be a laminated structure including the above positive electrode plate and negative electrode plate with the above separator in between, or a wound structure including the above positive electrode plate and negative electrode plate in a spiral shape with the above separator in between . The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group ratio) is usually 40% or more, preferably 50% or more, while usually 90% or less, preferably 80% or less .

An electrode group ratio below the above range may result in low battery capacity. An electrode group ratio above the above range can result in a small void space in the battery. Therefore, if the temperature of the battery rises to a high temperature and thus the components expand and the liquid part of the electrolyte solution exhibits a high vapor pressure to increase the internal pressure, battery characteristics such as charge and discharge repeatability and high-temperature storage capability may be impaired, and may Actuate the gas release valve to release the internal pressure outward.

The current collecting structure can be any structure. In order to more effectively improve the high current density charge and discharge performance of the electrolytic solution of the present invention, the current collecting structure is preferably a structure that reduces the resistance at the wiring portion and the bonding portion. Such a reduction in internal resistance can be brought about particularly advantageously by the effect achieved with the electrolyte solution of the present invention.

In an electrode group having a laminated structure, the metal core portions of the respective electrode layers are preferably bound and soldered to the terminals. When the electrode area is large, the internal resistance is high. Therefore, multiple terminals may preferably be placed in the electrodes in order to reduce resistance. In an electrode group having a wound structure, multiple lead structures may be disposed on each of the positive and negative electrodes and bound to the terminals. This reduces internal resistance.

The housing can be made of any material that is stable to the electrolyte solution to be used. Specific examples thereof include metals such as nickel-plated steel sheets, stainless steel, aluminum and aluminum alloys, and magnesium alloys, and layered films (laminated films) of resins and aluminum foils. In order to reduce the weight, metals such as aluminum or aluminum alloys or laminated films are advantageously used.

The case made of metal may have a sealing structure formed by welding metal by laser welding, resistance welding, or ultrasonic welding, or a caulking structure using metal with a resin spacer in between. A case made of a laminated film may have a sealed structure formed by heat-melting resin layers. In order to improve the sealability, a resin different from that of the laminated film may be disposed between the resin layers. In particular, in the case of forming a sealed structure by thermally fusing a resin layer having a collector terminal therebetween, the metal and the resin will be bonded. Therefore, the resin to be placed between the resin layers is advantageously a resin having a polar group or a modified resin into which a polar group is introduced.

The lithium ion secondary battery of the present invention may have any shape, such as a cylindrical shape, a square shape, a layer shape, a coin shape, or a large-sized shape. The shape and structure of the positive electrode, the negative electrode, and the separator may vary according to the shape of the battery.

In a preferred embodiment, the lithium ion secondary battery includes a positive electrode, a negative electrode and the aforementioned electrolyte solution, the positive electrode includes a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material, and the positive electrode active material contains Mn . A lithium ion secondary battery including a positive electrode active material layer including a Mn-containing positive electrode active material can have much better high-temperature storage characteristics.

In order to provide a high-power lithium-ion secondary battery with high energy density, LiMn _1.5 Ni _0.5 O ₄ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ and LiNi _0.6 Co _0.2 Mn _0.2 O are preferable as positive electrode active materials containing Mn. ₂ .

In order to provide a high-capacity lithium ion secondary battery, the positive electrode active material containing Mn is preferably any one of LiNi _0.6 Co _0.2 Mn _0.2 O ₂ and LiNi _0.8 Co _0.1 Mn _0.1 O ₂ .

The amount of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, especially preferably 84% by mass or more. The upper limit of the amount is preferably 99% by mass or less, more preferably 98% by mass or less. An excessively small amount of the positive electrode active material in the positive electrode active material layer may result in insufficient capacitance. In contrast, an excessive amount thereof may result in insufficient positive electrode strength.

The positive electrode active material layer may further contain a conductive material, a thickener, and a binder.

The binder can be any material that is not affected by the solvents to be used in the manufacture of electrodes and electrolyte solutions. Examples include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene-acrylic acid copolymer, ethylene- Methacrylic acid copolymer, polyethylene terephthalate, polymethyl methacrylate, polyimide, aramid, cellulose, nitrocellulose, acrylonitrile-butadiene rubber (NBR) , fluoroelastomer, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer and its hydrogenated product, ethylene-propylene-diene terpolymer (EPDM), styrene-ethylene-butanediene Ethylene-ethylene copolymer, styrene-isoprene-styrene block copolymer and its hydrogenated product, p-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, Propylene-α-olefin copolymer, fluorinated polyvinylidene fluoride, tetrafluoroethylene-ethylene copolymer, and polymer compositions with ion conductivity of alkali metal ions (especially lithium ions). One of these substances may be used alone, or two or more of them may be used in any ratio in any combination.

The amount of the binder expressed as the ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more. The ratio is also usually 80% by mass or less, preferably 60% by mass or less, still more preferably 40% by mass or less, most preferably 10% by mass or less. Too low a ratio of the binder may fail to sufficiently hold the positive electrode active material and result in insufficient mechanical strength of the positive electrode, thereby impairing battery performance such as cycle characteristics. In contrast, an excessively high ratio can lead to a decrease in battery capacity and conductivity.

Examples of thickeners include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, simple starch phosphate, casein and salts thereof. One of these agents may be used alone, or two or more of them may be used in any combination in any ratio.

The ratio of the thickener to the active material is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, while usually 5% by mass or less, preferably 3% by mass % or lower, more preferably 2% by mass or lower. Thickeners in proportions below the above ranges can result in significantly poorer ease of application. A thickener at a ratio higher than the above range may result in a low ratio of active materials in the positive electrode active material layer, resulting in low battery capacity and high resistance between positive electrode active materials.

The conductive material can be any known conductive material. Specific examples thereof include metal materials such as copper and nickel, and carbon materials such as graphite (including natural graphite and artificial graphite), carbon black (including acetylene black), and amorphous carbon (including needle coke). One of these materials may be used alone, or two or more of them may be used in any ratio in any combination. In the positive electrode active material layer, the amount of the conductive material is usually 0.01% by mass or higher, preferably 0.1% by mass or higher, more preferably 1% by mass or higher, and usually 50% by mass or lower, preferably Preferably 30% by mass or less, more preferably 15% by mass or less. The conductive material in an amount smaller than the above range may result in insufficient conductivity. In contrast, a conductive material in an amount greater than the above range may result in low battery capacity.

In order to further improve high-temperature storage characteristics, the positive electrode current collector is preferably formed of a valve metal or an alloy thereof. Examples of valve metals include aluminum, titanium, tantalum and chromium. The positive electrode current collector is more preferably formed of aluminum or an aluminum alloy.

In order to further improve the high-temperature storage characteristics of the lithium-ion secondary battery, the portion in contact with the electrolytic solution in the portion electrically coupled to the positive electrode collector is also preferably formed of a valve metal or an alloy thereof. In particular, the battery case and the components housed in the battery case, such as lead wires and safety valves, are preferably formed of a valve metal or an alloy thereof that is electrically coupled to the positive electrode current collector and is in contact with the non-aqueous electrolyte solution . Stainless steel coated with valve metal or alloys thereof may also be used.

The positive electrode can be manufactured by the aforementioned method. An example of the manufacturing method is a method in which the positive electrode active material is mixed with the aforementioned binder, thickener, conductive material, solvent, and other components to form a paste-like positive electrode mixture, and then this mixture is applied to the positive electrode Current collectors, dried, and pressed for densification.

The structure of the negative electrode is as described above.

A module including the lithium ion secondary battery of the present invention is an aspect of the present invention.

An electric double layer capacitor may include a positive electrode, a negative electrode, and the aforementioned electrolytic solution. At least one selected from the group consisting of a positive electrode and a negative electrode is a polarizable electrode in an electric double layer capacitor. Examples of polarizable electrodes and non-polarizable electrodes include the following electrodes specifically disclosed in JP H09-7896 A.

A polarizable electrode mainly containing activated carbon to be used in the present invention preferably contains non-activated carbon having a large specific surface area and a conductive material providing electronic conductivity, such as carbon black. Polarizable electrodes can be formed by various methods. For example, a polarizable electrode comprising activated carbon and carbon black can be prepared by mixing activated carbon powder, carbon black, and phenolic resin, molding the mixture, and then sintering and activating the mixture in an atmosphere of inert gas and water vapor. manufacture. Preferably, the polarizable electrode is bonded to the current collector using, for example, a conductive adhesive.

Alternatively, a polarizable electrode may also be formed by kneading activated carbon powder, carbon black, and a binder in the presence of alcohol, forming the mixture into a sheet, and then drying the sheet. For example, the adhesive to be used may be polytetrafluoroethylene. Alternatively, a polarizable electrode integrated with a current collector can be prepared by mixing activated carbon powder, carbon black, a binder, and a solvent to form a slurry, applying this slurry to the metal foil of the current collector, and then drying the slurry. manufacture.

Electric double layer capacitors may have polarizable electrodes mainly containing activated carbon as individual electrodes. In addition, an electric double layer capacitor may have a structure using a non-polarized electrode on one side. Examples of such structures include a structure in which a positive electrode mainly containing an electrode active material such as a metal oxide is combined with a polarizable negative electrode mainly containing activated carbon; and a structure in which mainly carbon capable of reversibly occluding and releasing lithium ions is contained A structure in which a negative electrode of a material or a negative electrode of lithium metal or lithium alloy is combined with a polarizable positive electrode mainly containing activated carbon.

Instead of or in combination with activated carbon, any carbonaceous material may be used, such as carbon black, graphite, expanded graphite, porous carbon, carbon nanotubes, carbon nanohorns, and Ketjen black.

The non-polarized electrode is preferably an electrode mainly containing a carbon material capable of reversibly storing and releasing lithium ions, wherein the carbon material is pre-made to store lithium ions. In this case, the electrolyte used is a lithium salt. Electric double layer capacitors with such structures can achieve much higher withstand voltages exceeding 4 V.

The solvent used to prepare the slurry in electrode manufacture is preferably a solvent that dissolves the binder. Depending on the type of adhesive, the solvent is suitably selected from N-methylpyrrolidone, dimethylformamide, toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, ortho Dimethyl phthalate, ethanol, methanol, butanol and water.

Examples of the activated carbon used for the polarizable electrode include phenol resin type activated carbon, coconut shell type activated carbon and petroleum coke type activated carbon. In order to achieve a large capacity, it is preferable to use petroleum coke-type activated carbon or phenol resin-type activated carbon. Examples of methods of activating activated carbon include steam activation and molten KOH activation. In order to achieve a larger capacity, it is preferable to use activated carbon prepared by activation with molten KOH.

Preferable examples of the conductive agent for the polarizable electrode include carbon black, Ketjen black, acetylene black, natural graphite, artificial graphite, metal fiber, conductive titanium oxide, and ruthenium oxide. In order to achieve good electrical conductivity (i.e., low internal resistance), and since too large an amount of conductive agent can lead to a decrease in product capacity, the amount of conductive agent (such as carbon black) used for polarizable electrodes is preferably activated carbon and conductive 1 to 50% by mass of the sum of doses.

In order to provide an electric double-layer capacitor having a large capacity and low internal resistance, activated carbon for a polarizable electrode preferably has an average particle diameter of 20 μm or less and a specific surface area of 1500 to 3000 m ² /g. Preferable examples of carbon materials for providing electrodes mainly containing carbon materials capable of reversibly occluding and releasing lithium ions include natural graphite, artificial graphite, graphitized mesocarbon microspheres, graphitized whiskers, vapor-grown carbon fibers, Sintered furfuryl alcohol resin and sintered phenolic resin.

The current collector can be any current collector that is resistant to chemical and electrochemical corrosion. Preferred examples of current collectors for polarizable electrodes mainly containing activated carbon include stainless steel, aluminum, titanium and tantalum. Particularly preferred materials are stainless steel and aluminum in terms of properties and cost of the resulting electric double layer capacitor. Preferable examples of current collectors for electrodes mainly containing carbon materials capable of reversibly occluding and releasing lithium ions include stainless steel, copper, and nickel.

Examples of methods for enabling a carbon material capable of reversibly occluding and releasing lithium ions to occlude lithium ions in advance include: (1) a method of mixing powdered lithium into a carbon material capable of reversibly occluding and releasing lithium ions; (2) Lithium foil is placed on an electrode including a carbon material capable of reversibly occluding and releasing lithium ions and a binder so that the lithium foil is in electrical contact with the electrode, and the electrode is immersed in an electrolyte solution containing a lithium salt dissolved therein to A method for ionizing lithium and allowing a carbon material to absorb lithium ions; and (3) placing an electrode comprising a carbon material capable of reversibly occluding and releasing lithium ions and a binder on the negative side and lithium metal on the positive side , A method in which an electrode is immersed in a non-aqueous electrolyte solution containing a lithium salt as an electrolyte, and an electric current is provided so that the carbon material electrochemically absorbs ionized lithium.

Examples of known electric double layer capacitors include wound electric double layer capacitors, laminated electric double layer capacitors, and coin type electric double layer capacitors. Electric double layer capacitors may also be of any of these types.

For example, a wound electric double layer capacitor can be assembled as follows. The positive electrode and the negative electrode of the laminate (electrode), each including a current collector and an electrode layer, are wound with a separator therebetween to provide a wound element. This coiled element is placed in a housing, for example made of aluminium. The shell is filled with an electrolyte solution, preferably a non-aqueous electrolyte solution, and then sealed with a rubber sealant.

Separators formed of known materials and of known construction can be used. Examples thereof include polyethylene porous films, non-woven fabrics of polytetrafluoroethylene and polypropylene fibers, glass fibers or cellulose fibers.

According to any known method, the electric double-layer capacitor can be produced in the form of a laminated electric double-layer capacitor in which a positive electrode and a negative electrode in the form of sheets are stacked with an electrolytic solution and a separator therebetween; or in the form of a coin-type electric double-layer capacitor, Wherein the positive electrode and the negative electrode are fixed in the shape of a coin by a spacer, with an electrolyte solution and a separator therebetween.

The electrolytic solution of the present invention is suitable as an electrolytic solution for large-scale lithium-ion secondary batteries of hybrid vehicles or distributed power generation, and as an electrolytic solution for electric double-layer capacitors. Example

The present invention has been described with reference to examples, but the invention is not intended to be limited by these examples.

Synthesis Example 1 First, trimethylsilylmethanol (2.6 mL, 0.0208 mol) was measured and transferred to a container equipped with a condenser, dropping funnel, and thermometer, which was connected to a HCl trap. Subsequently, 7 mL of toluene was added thereto, followed by triethylamine (2.34 mL, 0.0234 mol). Subsequently, phosphorus oxychloride (0.61 mL, 0.006 mol) in toluene was added dropwise to the reaction mixture at 0-5 °C. After the phosphorus oxychloride addition was complete, the reaction temperature was increased to 70°C and the reaction was stirred overnight. After the reaction was complete, the triethylamine salt was filtered, and the solvent was evaporated. The product was then extracted in toluene and washed with brine solution. The collected organic layer was then dried over sodium sulfate, and the solvent was removed to recover the product (yield = 1.81 g, 77.58%). Products were characterized using ¹ H, ³¹ P, ¹³ C, ²⁹ Si NMR, GC-MS and GC-FID. The product was obtained in high purity (up to 94%, measured by GC-FID) without any distillation. The product was analyzed by GC-FID and found to be a composition containing 94% by mass of Compound A and 1.5% by mass of Compound B.

Synthesis Example 2 First, trimethylsilylmethanol (2.6 mL, 0.0208 mol) was measured and transferred to a vessel equipped with a condenser, dropping funnel and thermometer, which was connected to the HCl trap. Subsequently, 7 mL of toluene was added thereto, followed by addition of triethylamine (3.03 g, 0.03 mol). Subsequently, phosphorus oxychloride (0.61 mL, 0.006 mol) in toluene was added dropwise to the reaction mixture at 0-5 °C. After the phosphorus oxychloride addition was complete, the reaction temperature was increased to 70°C and the reaction was stirred overnight. After the reaction was complete, the triethylamine salt was filtered, and the solvent was evaporated. The product was then extracted in toluene and washed with brine solution. The collected organic layer was then dried over sodium sulfate, and the solvent was removed to recover the product (yield = 1.53 g, 65.9%). The product was analyzed by GC-FID and found to be a composition containing 86% by mass of Compound A and 8.5% by mass of Compound B.

Examples 1 to 14 and Comparative Example 1 (Preparation of Electrolyte Solution) Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 30/70, and LiPF ₆ was added to the mixture , so that the concentration of LiPF ₆ is 1.0 mol/L. Thus, a basic electrolyte solution was prepared. This basic electrolyte solution was further mixed with the additives shown in Table 1 at the concentrations shown in Table 1, thereby obtaining a nonaqueous electrolyte solution. For compounds A and B, the composition obtained in Synthesis Example 1 was used in Examples 1 to 7, and the composition obtained in Synthesis Example 2 was used in Examples 8 to 14. The amounts of Compounds A and B shown in Table 1 are each relative to the total mass of the electrolytic solution.

(Manufacture of aluminum laminated lithium-ion secondary battery) (Manufacture of positive electrode) First, 93% by mass of LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (NMC) as a positive electrode active material and 3% by mass of acetylene black as a conductive material and 4% by mass of polyvinylidene fluoride (polyvinylidene fluoride; PVdF) serving as a binder were mixed in an N-methylpyrrolidone solvent to form a slurry. The resulting slurry was applied to one surface of a 15 μm thick aluminum foil previously applied with a conductive aid, and dried. The workpiece was then rolled using a press and cut to provide a sheet comprising an active material layer with a width of 50 mm and a length of 30 mm and an uncoated portion of a width of 5 mm and a length of 9 mm. This piece was used as a positive electrode.

(manufacturing negative electrode) First, an aqueous dispersion of 98 parts by mass of carbonaceous material (graphite) and 1 part by mass of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose: 1 mass %) and 1 part by mass of styrene-butadiene Aqueous dispersions of rubber (concentration of styrene-butadiene rubber: 50% by mass) were mixed, and these dispersions acted as thickeners and binders, respectively. The components are mixed using a disperser to form a slurry. The resulting paste was applied to 10 μm thick copper foil and dried. The work piece was rolled using a press and cut to provide a piece comprising an active material layer with a width of 52 mm and a length of 32 mm and an uncoated portion of a width of 5 mm and a length of 9 mm. This piece was used as a negative electrode.

(manufacturing of aluminum laminated battery cells) The above-mentioned positive electrode and negative electrode were placed facing each other with a 20 μm thick porous polyethylene film (separator) in between. The non-aqueous electrolyte solution prepared above is filled thereinto, and the non-aqueous electrolyte solution is allowed to sufficiently penetrate into components such as separators. The workpiece is then sealed, pre-charged and aged to create a lithium-ion secondary battery.

(Measurement of battery characteristics) (amount of gas produced) The lithium ion secondary battery manufactured above was subjected to constant current/constant voltage charge (constant current/constant voltage charge; below) at a current corresponding to 1 C and 25° C. in a state sandwiched and compressed between the plates. In this paper, it is called CC/CV charging) (0.1 C cut-off) to 4.2 V, and then discharged to 3 V at a constant current of 1 C. This was counted as one cycle, and this charge and discharge cycle was repeated 200 times. Here, 1 C means the current value at which the reference capacity of the battery is discharged within one hour. For example, 0.2 C means 1/5 of this current value. Before and after the cycle, the volume of the battery was measured by the Archimedes' method, and the amount of gas generated was calculated by the following formula. (volume after the 200th cycle) - (initial volume) = gas volume produced (mL) The results are shown in Table 1, where the value in Comparative Example 1 was regarded as 1.

(percent increase in IV resistance) After evaluating the initial discharge capacity, the battery was charged at a constant current of 1 C at 25° C. so as to have a capacity half of the initial discharge capacity. Then the battery was discharged at 1.0 C, and the voltage at the 10th second was measured. The resistance is calculated from the voltage drop during discharge, which is defined as the IV resistance. The IV resistance measured with the battery after evaluating the initial discharge capacity was defined as the initial IV resistance, and the IV resistance measured with the battery after 200 charge and discharge cycles was defined as the post-cycle IV resistance. Calculate the percentage increase in IV resistance by the following calculation method. (IV resistance increase percentage)=(IV resistance after cycle)/(initial IV resistance)×100 The results are shown in Table 1, where the value in Comparative Example 1 was regarded as 1.

Examples 15 to 28 and Comparative Example 2 (Preparation of Electrolyte Solution) Mix fluoroethylene carbonate (fluoroethylene carbonate; FEC) and 2,2,2-trifluoroethyl methyl carbonate at a volume ratio of 30/70, and LiPF ₆ was added to the mixture so that the concentration of LiPF ₆ was 1.0 mol/L. Thus, a basic electrolyte solution was prepared. This basic electrolyte solution was further mixed with the additives shown in Table 2 at the concentrations shown in Table 2, thereby obtaining a nonaqueous electrolyte solution. For compounds A and B, the composition obtained in Synthesis Example 1 was used in Examples 15 to 21, and the composition obtained in Synthesis Example 2 was used in Examples 22 to 28. The amounts of Compounds A and B shown in Table 2 are each relative to the total mass of the electrolytic solution.

(Manufacture of aluminum laminated lithium ion secondary battery) (Manufacture of positive electrode) First, 93% by mass of LiNi _0.5 Mn _1.5 O ₄ (LNMO) as a positive electrode active material, 3% by mass of acetylene black as a conductive material, and 4 Mass % Polyvinylidene fluoride (PVdF) serving as a binder is mixed in an N-methylpyrrolidone solvent to form a slurry. The resulting slurry was applied to one surface of a 15 μm thick aluminum foil previously applied with a conductive aid, and dried. The workpiece was then rolled using a press and cut to provide a sheet comprising an active material layer with a width of 50 mm and a length of 30 mm and an uncoated portion of a width of 5 mm and a length of 9 mm. This piece was used as a positive electrode.

(manufacturing negative electrode) First, an aqueous dispersion of 98 parts by mass of carbonaceous material (graphite) and 1 part by mass of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose: 1 mass %) and 1 part by mass of styrene-butadiene Aqueous dispersions of rubber (concentration of styrene-butadiene rubber: 50% by mass) were mixed, and these dispersions acted as thickeners and binders, respectively. The components are mixed using a disperser to form a slurry. The resulting paste was applied to 10 μm thick copper foil and dried. The work piece was rolled using a press and cut to provide a piece comprising an active material layer with a width of 52 mm and a length of 32 mm and an uncoated portion of a width of 5 mm and a length of 9 mm. This piece was used as a negative electrode.

(manufacturing of aluminum laminated battery cells) The above-mentioned positive electrode and negative electrode were placed facing each other with a 20 μm thick porous polyethylene film (separator) in between. The non-aqueous electrolyte solution prepared above is filled thereinto, and the non-aqueous electrolyte solution is allowed to sufficiently penetrate into components such as separators. The workpiece is then sealed, pre-charged and aged to create a lithium-ion secondary battery.

(Measurement of battery characteristics) (amount of gas produced) The lithium ion secondary battery manufactured above was subjected to constant current/constant voltage charging (hereinafter referred to as CC/CV charging) at a current corresponding to 1 C and 25° C. in a state sandwiched and compressed between plates. ) (0.1 C cut-off) to 4.9 V, and then discharged to 3 V at a constant current of 1 C. This was counted as one cycle, and this charge and discharge cycle was repeated 200 times. Before and after the cycle, the volume of the battery was measured by the Archimedes method, and the amount of gas generated was calculated by the following formula. (volume after the 200th cycle) - (initial volume) = gas volume produced (mL) The results are shown in Table 2, where the value in Comparative Example 2 was regarded as 1.

(percent increase in IV resistance) After evaluating the initial discharge capacity, the battery was charged at a constant current of 1 C at 25° C. so as to have a capacity half of the initial discharge capacity. Then the battery was discharged at 1.0 C, and the voltage at the 10th second was measured. The resistance is calculated from the voltage drop during discharge, which is defined as the IV resistance. The IV resistance measured with the battery after evaluating the initial discharge capacity was defined as the initial IV resistance, and the IV resistance measured with the battery after 200 charge and discharge cycles was defined as the post-cycle IV resistance. Calculate the percentage increase in IV resistance by the following calculation method. (IV resistance increase percentage)=(IV resistance after cycle)/(initial IV resistance)×100 The results are shown in Table 2, where the value in Comparative Example 2 was regarded as 1.

[Table 1] Solvent 1 (volume%) Solvent 2 (volume%) Additive 1 (quality%) Additive 2 (quality%) Gas amount (relative value, wherein the value of Comparative Example 1 is regarded as 1) Increase percentage (%) (relative value, wherein the value of Comparative Example 1 is regarded as 1) Example 1 EC 30 EMC 70 A 0.00094 B 0.000015 0.61 0.59 Example 2 EC 30 EMC 70 A 0.0094 B 0.00015 0.60 0.57 Example 3 EC 30 EMC 70 A 0.094 B 0.0015 0.59 0.56 Example 4 EC 30 EMC 70 A 0.47 B 0.0075 0.56 0.53 Example 5 EC 30 EMC 70 A 0.94 B 0.015 0.55 0.52 Example 6 EC 30 EMC 70 A 4.7 B 0.075 0.57 0.55 Example 7 EC 30 EMC 70 A 9.4 B 0.15 0.61 0.59 Example 8 EC 30 EMC 70 A 0.00086 B 0.000085 0.64 0.62 Example 9 EC 30 EMC 70 A 0.0086 B 0.00085 0.63 0.60 Example 10 EC 30 EMC 70 A 0.086 B 0.0085 0.62 0.59 Example 11 EC 30 EMC 70 A 0.43 B 0.0425 0.59 0.57 Example 12 EC 30 EMC 70 A 0.86 B 0.085 0.58 0.55 Example 13 EC 30 EMC 70 A 4.3 B 0.425 0.60 0.58 Example 14 EC 30 EMC 70 A 8.6 B 0.85 0.64 0.61 Comparative Example 1 EC 30 EMC 70 - - - - 1.00 1.00

[Table 2] Solvent 1 (volume%) Solvent 2 (volume%) Additive 1 (quality%) Additive 2 (quality%) Gas amount (relative value, wherein the value of Comparative Example 2 is regarded as 1) Increase percentage (%) (relative value, wherein the value of Comparative Example 2 is regarded as 1) Example 15 F-1 30 F-2 70 A 0.00094 B 0.000015 0.50 0.50 Example 16 F-1 30 F-2 70 A 0.0094 B 0.00015 0.48 0.48 Example 17 F-1 30 F-2 70 A 0.094 B 0.0015 0.47 0.46 Example 18 F-1 30 F-2 70 A 0.47 B 0.0075 0.45 0.44 Example 19 F-1 30 F-2 70 A 0.94 B 0.015 0.46 0.45 Example 20 F-1 30 F-2 70 A 4.7 B 0.075 0.47 0.47 Example 21 F-1 30 F-2 70 A 9.4 B 0.15 0.49 0.48 Example 22 F-1 30 F-2 70 A 0.00086 B 0.000085 0.53 0.53 Example 23 F-1 30 F-2 70 A 0.0086 B 0.00085 0.51 0.51 Example 24 F-1 30 F-2 70 A 0.086 B 0.0085 0.50 0.49 Example 25 F-1 30 F-2 70 A 0.43 B 0.0425 0.48 0.47 Example 26 F-1 30 F-2 70 A 0.86 B 0.085 0.49 0.48 Example 27 F-1 30 F-2 70 A 4.3 B 0.425 0.50 0.50 Example 28 F-1 30 F-2 70 A 8.6 B 0.85 0.52 0.51 Comparative Example 2 F-1 30 F-2 70 - - - - 1.00 1.00

化合物B： [化學式81]

The abbreviations in the table are as follows. EC: Ethyl carbonate EMC: Ethyl methyl carbonate F-1: Ethyl fluorocarbonate F-2: 2,2,2-trifluoroethyl methyl carbonate Compound A: [Chemical Formula 80]

Compound B: [Chemical Formula 81]

The results shown in Table 1 and Table 2 clearly show that the embodiment of the composition of the present invention containing the combination of A and B helps to reduce gas generation from the electrolyte (Examples 1 to 14 vs. Comparative Example 1, and Examples 15 to 28 are compared with Example 2). In other words, compositions of the invention containing a combination of A and B increase the stability of the electrolyte, and thus the stability of the electrochemical cell. Therefore, the composition of the present invention enables electrochemical cells to have greater operating durability, provide higher operating efficiency, and ensure energy saving.

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Claims (14)

A composition comprising: Compound (1) represented by the following formula (1): [Chemical Formula 1]

Wherein R ¹⁰¹ to R ¹⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each contains at least one member selected from the group consisting of halogen atoms and oxygen atoms as appropriate; n10 is an integer of 1 to 3; and m10 is 0 or 1; and a compound (2) represented by the following formula (2): [Chemical formula 2]

Wherein R ²⁰¹ to R ²⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each optionally contains at least one member selected from the group consisting of halogen atoms and oxygen atoms; n20 is an integer from 1 to 3; and m20 is 0 or 1. The composition according to claim 1, wherein in the formula (1), R ¹⁰¹ to R ¹⁰³ are independently methyl groups, and m10 and n10 are independently 1. The composition according to claim 1 or 2, wherein in the formula (2), R ²⁰¹ to R ²⁰³ are independently methyl groups, and m20 and n20 are independently 1. The composition according to any one of claims 1 to 3, wherein the amount of the compound (2) is 0.1 to 20% by mass relative to the mass of the compound (1). Such as the composition of any one of claims 1 to 4, Wherein the composition acts as an additive of the electrolyte solution. An electrolytic solution comprising the composition according to any one of claims 1 to 5. Such as the electrolyte solution of claim item 6, Wherein relative to the total mass of the electrolyte solution, the amount of the compound (1) is 0.0001 to 10% by mass. A method of reducing gas generation from an electrolyte solution, the method comprising: contacting the electrolyte solution with the composition according to any one of claims 1-5. An electrochemical device comprising the electrolyte solution according to claim 6 or 7. A lithium ion secondary battery, which comprises the electrolytic solution according to claim 6 or 7. A module comprising the electrochemical device according to claim 9 or the lithium ion secondary battery according to claim 10. A compound represented by the following formula (2): [Chemical formula 3]

Wherein R ²⁰¹ to R ²⁰³ are each independently C1-C3 alkyl, C2-C3 alkenyl or C2-C3 alkynyl, and each optionally contains at least one member selected from the group consisting of halogen atoms and oxygen atoms; n20 is an integer from 1 to 3; and m20 is 0 or 1. The compound of claim 12, wherein in the formula (2), R ²⁰¹ to R ²⁰³ are independently methyl groups, and m20 and n20 are independently 1. A method of reducing gas generation from an electrolyte solution, the method comprising: contacting the electrolyte solution with the compound according to claim 12 or 13.