WO2014156428A1 - Electrolyte solution for nonaqueous secondary batteries, and nonaqueous secondary battery - Google Patents

Abstract

An electrolyte solution for nonaqueous secondary batteries, which contains an electrolyte, an organic solvent and a specific additive that has a structure expressed as functional group (A), and wherein 20-95% by volume of the organic solvent is configured of a primary chain carbonate compound and the specific additive is contained in an amount of 0.5-10% by mass of the whole electrolyte solution. (In the formula, each of R¹-R³ independently represents a hydrogen atom, a halogen atom or a hydrocarbon group; at least two moieties among the R¹-R³ moieties are hydrocarbon groups; each hydrocarbon group may have a group containing at least one atom that is selected from among an oxygen atom, a nitrogen atom, a sulfur atom and a halogen atom; and * represents a bonding hand.)

Description

Non-aqueous secondary battery electrolyte and non-aqueous secondary battery

The present invention relates to an electrolyte for a non-aqueous secondary battery and a non-aqueous secondary battery.

Conventionally, lithium ion secondary batteries and lithium metal secondary batteries have had a problem of overcharging as an inherent solution. This leads to a situation such as overheating or short-circuiting of the electrode when the secondary battery is fully charged even if the secondary battery is fully charged. In particular, it is a problem peculiar to a lithium secondary battery using an organic electrolyte, and a sufficient response has been desired from the viewpoint of ensuring reliability in use.

In response to this, usually, measures are taken on the side of the electric equipment to which the battery is mounted, and a charging circuit is incorporated, so that the supply of electricity is cut off when full charge is reached. However, even though it is extremely rare, it is assumed that a malfunction or the like occurs in the above circuit, resulting in an overcharged state. Even in such a case, if the non-aqueous electrolyte is improved and overcharge can be suppressed, the reliability can be further improved.

Several additives to be added to the non-aqueous electrolyte have been proposed for the purpose of preventing overcharge as described above. As a typical example, an electrolyte containing an alkylbenzene derivative such as cyclohexylbenzene disclosed in Patent Documents 1 and 2 below is used in combination with a device that cuts off charging when the gas pressure inside the battery exceeds a predetermined pressure. Attempts have been made to improve safety during overcharge.

Japanese Patent No. 3113652 JP 2009-231283 A

As the performance required for the overcharge inhibitor, it is desired that the normal charging potential does not hinder the operation, and that the effect is quickly manifested only at the time of overcharging. A conventional gas generation type overcharge inhibitor, such as cyclohexylbenzene, reacts not only at the time of overcharge but also at the time of normal charge, and when charging and discharging are repeated, resistance increases and capacity deterioration is observed.

Therefore, an object of the present invention is to provide an electrolyte for a non-aqueous secondary battery and a non-aqueous secondary battery that can achieve both high overcharge prevention properties and suppression of deterioration.

The above problem has been solved by the following means.
[1] An electrolytic solution containing an electrolyte, an organic solvent, and a specific additive having a structure represented by the following functional group (A),
20 to 95% by volume of the organic solvent is composed of a primary chain carbonate compound,
An electrolyte for non-aqueous secondary batteries containing 0.5 to 10% by mass of a specific additive in the total electrolyte.

(R ¹ to R ³ each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group. At least two of R ¹ to R ³ are hydrocarbon groups. The hydrocarbon group is an oxygen atom or a nitrogen atom. And a group containing at least one atom selected from a sulfur atom and a halogen atom, * is a bond.)
[2] The electrolyte solution for a non-aqueous secondary battery according to [1], wherein when R ¹ to R ³ are hydrocarbon groups, the hydrocarbon group is an aromatic group or an alkyl group represented by the following formula Rb.
* -CR ^b1 R ^b2 R ^b3 (Rb)
(R ^b1 , R ^b2 , and R ^b3 are each independently a hydrogen atom, a hydrocarbon group, or a group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom. , R ¹ to R ³ are an alkyl group represented by the formula (Rb), and at least one of them is at least one of R ^b1 , R ^b2 and R ^b3 is a hydrogen atom, a hydrocarbon group, or (This is a group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. * Is a bond.)
[3] The electrolyte solution for a non-aqueous secondary battery according to [1] or [2], wherein the number of functional groups (A) of the compound constituting the specific additive is two or more.
[4] The electrolyte solution for a non-aqueous secondary battery according to any one of [1] to [3], wherein the electrolyte solution contains an acid generator having a functional group that generates an acid upon oxidation.
[5] The nonaqueous secondary battery according to any one of [1] to [4], wherein the number and molecular weight of the functional group (A) of the specific additive satisfy the relationship of the following formula (a): Electrolyte.
Number of functional groups (A) in the molecule / molecular weight of the compound × 1000 ≧ 5 (a)
[6] The electrolyte solution for a secondary battery according to any one of [1] to [5], wherein the functional group (A) is represented by the following functional group (B).

[X ¹ is a linking group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. R ¹ ~ ^{R 3} have the same meanings as ^R 1 ~ ^{R 3} in formula (A). ]
[7] The electrolyte for a non-aqueous secondary battery according to any one of [1] to [6], wherein the specific additive is represented by the following formula (A1).

_{[N a} is an integer of 1-6. R _a represents an organic group when _na is 1, and represents a linking group when _na is 2 or more. R ¹ ~ ^{R 3} have the same meanings as ^R 1 ~ ^{R 3} in formula (A). ]
[8] The electrolyte solution for a nonaqueous secondary battery according to [7], wherein the formula (A1) is represented by the following formula (B1).

[ _Nb is an integer of 2 to 6. R _b represents a divalent to hexavalent linking group. X ²¹ is a linking group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. R ¹ ~ ^{R 3} have the same meanings as ^R 1 ~ ^{R 3} in the formula (A1). ]
[9] The electrolyte solution for a non-aqueous secondary battery according to any one of [4] to [8], wherein the acid generator is contained in an amount of 0.1 to 5% by mass in the total electrolyte solution.
[10] In any one of [1] to [9], the primary linear carbonate compound is diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or methyl n-propyl carbonate. The electrolyte solution for non-aqueous secondary batteries as described.
[11] A nonaqueous electrolyte secondary battery comprising the positive electrode, the negative electrode, and the electrolytic solution according to any one of [1] to [10].
[12] The nonaqueous electrolyte secondary battery according to [11], wherein a compound having at least one of nickel and manganese is used as an active material for the positive electrode.
[13] The nonaqueous electrolyte secondary battery according to [11] or [12], wherein lithium titanate (LTO) or a carbon material is used as an active material for the negative electrode.
[14] The specific additive is a compound that generates gas when overcharged, and has an overcharge prevention device that cuts off the current when the internal pressure of the battery exceeds a predetermined pressure [11] to [13] The nonaqueous secondary battery according to any one of the above.
[15] An electrolyte solution for a non-aqueous secondary battery containing a compound that decomposes in a chain upon overcharge and generates a gas, an electrolyte, and an organic solvent.

According to the electrolyte solution for non-aqueous secondary battery and the non-aqueous secondary battery of the present invention, it is possible to achieve both high overcharge prevention and suppression of deterioration in performance.
The above and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.

It is sectional drawing which shows typically the mechanism of the lithium secondary battery which concerns on preferable embodiment of this invention. It is sectional drawing which shows the specific structure of the lithium secondary battery which concerns on preferable embodiment of this invention. It is a partial cross section side view which shows typically the battery lid body with a pressure-sensitive mechanism which concerns on preferable embodiment of this invention. It is sectional drawing which shows typically the structure of CR2032-type coin battery.

The electrolyte solution for a non-aqueous secondary battery of the present invention contains a specific additive, an electrolyte, and a specific organic solvent in specific amounts.

[Specific additives]
The specific additive of the present invention is decomposed by the oxidizing action in the electrolytic solution to generate gas. Although the detailed reaction mechanism in this electrolyte solution includes an unclear point, it is estimated as follows. In response to an increase in electrode potential during overcharge, the organic solvent component or the specific additive in the electrolytic solution may be decomposed to generate an acid (proton) in the system. For example, the proton can act on the carbonyl group in the functional group of formula (A). As a result, electron transfer occurs in the functional group (A), and the component consisting of R ¹ to R ^{3 at} the end is dissociated. When the boiling point of the component is low, it is considered that it is released as a gas. Furthermore, dissociation of the remaining COO groups occurs, and this is released as carbon dioxide, which further increases the amount of gas generated. At this time, it is understood that the component composed of R ¹ to R ³ is an alkene, and protons generated when the alkene is generated are released into the system. This proton further acts on the carbonyl group in the specific additive to advance the gas release reaction described above. That is, it is considered that the chain reaction related to the decomposition of the specific additive proceeds, promptly generating a large amount of gas at the time of overcharge, and leading to the remarkable effect of the present invention. The use of the chain reaction mechanism as described above for the gas generation of the non-aqueous electrolyte is a novel idea that has never been seen before.

The specific additive of the present invention has one or more of the following functional groups (A) in the molecule.

・ R ¹ to R ³
R ¹ to R ³ are each independently a hydrogen atom, a halogen atom or a hydrocarbon group (preferably having a carbon number of 1 to 22), and at least two of them are the above hydrocarbon groups (the carbon atom at the α-position carbon). A hydrocarbon group to be substituted). The hydrocarbon group may have a substituent Z containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom.

Examples of the hydrocarbon group include alkyl groups (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms), and alkenyl groups (preferably having 2 to 12 carbon atoms, more preferably Is an alkynyl group (preferably 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms, particularly preferably 2 to 4 carbon atoms), a cycloalkyl group (Preferably 3 to 12 carbon atoms, more preferably 3 to 6 carbon atoms) and aryl groups (preferably 6 to 22 carbon atoms, more preferably 6 to 10 carbon atoms). Of these, an alkyl group is preferable.
R ¹ to R ³ may combine with each other to form a ring. Examples of the ring formed at this time include a cycloalkyl group (preferably having 3 to 12 carbon atoms, more preferably 3 to 6 carbon atoms), and among them, a cyclohexyl group is preferable.

As the substituent Z, an alkoxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an aryloxy group (preferably having 6 to 12 carbon atoms, more preferably Has 6 to 10 carbon atoms), an alkoxycarbonyl group (preferably 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms, particularly preferably 2 to 4 carbon atoms), an amino group (preferably 0 to 12 carbon atoms, More preferably 0 to 6 carbon atoms, particularly preferably 0 to 3 carbon atoms), an acyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), acyloxy A group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), a carbamoyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly Good Preferably 1 to 3 carbon atoms), an acylamino group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an alkylthio group (preferably 1 to 12 carbon atoms, More preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms, an arylthio group (preferably 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, an alkylsulfonyl group (preferably 1 to 12 carbon atoms). More preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), arylsulfonyl groups (preferably 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms), silyl groups (preferably 1 carbon atoms). To 12, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), halogen atoms (eg, fluorine, chlorine, bromine), halogenated alkyl groups (preferably 1 to 12 carbon atoms). More preferably 1 to 6 carbon atoms, particularly preferably a group selected from C 1-3) carbon atoms.

* Is a bond.

As R ¹ to R ³ , at least two of them are preferably the alkyl group defined above or the aryl group defined above. When the alkyl group is an aralkyl group, it preferably has 7 to 12 carbon atoms as defined above.

When R ¹ to R ³ are hydrocarbon groups, a linking group (L) may be present in the substituent (for example, alkyl chain), and examples of the linking group (L) include O, S, NR (R is an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 22 carbon atoms), CO, COO, SO ₂ , and combinations thereof.

When R ¹ to R ³ are hydrocarbon groups, the hydrocarbon group is preferably an aromatic group or an alkyl group represented by the following formula Rb.

* -CR ^b1 R ^b2 R ^b3 (Rb)

R ^b1 , R ^b2 , and R ^b3 are each independently a hydrogen atom, a hydrocarbon group, or a group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom. Provided that when R ¹ to R ³ are alkyl groups represented by the formula (Rb), at least one of R ^b1 , R ^b2 and R ^b3 is a hydrogen atom, a hydrocarbon group, or , A group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. In other words, at least one of the hydrocarbon groups represented by the formula (Rb) has a group other than at least one halogen atom-containing group at the β position (C in the formula (Rb)), and the β position It is preferable that a hydrogen atom is present in the group.
Even when R ¹ to R ³ are aromatic groups, at least one of the aromatic groups preferably has a hydrogen atom.

When R ^b1 , R ^b2 and R ^b3 are hydrocarbon groups, preferred examples thereof include those exemplified as the preferred hydrocarbons of R ¹ to R ³ . As the group containing a halogen atom or at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom, the substituent Z is preferred.

* Is a bond.

In the specific additive, the number of the functional group (A) of the compound is not particularly limited, but is preferably 2 or more. There is no particular upper limit, but it is practical that it is 6 or less.

In this invention, it is preferable that the number and molecular weight in the molecule | numerator of the functional group (A) of the said specific additive satisfy | fill the relationship of following formula (a). However, when the C═O group is shared by two functional groups such as A-1 and A-3 described later, the number of functional groups is 1. This parameter indicates the ratio of the functional group capable of generating gas to the added amount (mass) of the additive, and serves as an index indicating the amount of gas generated per unit mass. That is, it is suggested that the larger this parameter, the higher the gas generation capacity per unit mass. The right side of the formula (a) is 5, but is more preferably 6.5.

Number of functional groups (A) in the molecule / molecular weight of the compound × 1000 ≧ 5
(A)

Among the functional groups (A), as a preferred embodiment thereof, groups represented by the following functional groups (B) can be mentioned.

X ¹ is a linking group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. Examples of the linking group include the examples of the linking group (L). Among these, O, S, and NR (R is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms) are preferable. R ¹ to R ³ are groups having the same definitions as in the formula (A).

The specific additive is preferably represented by the following formula (A1).

n _a is an integer of 1 to 6. The groups defined in plural by na may be the same or different.

R _a represents an organic group when _na is 1, and represents a linking group when _na is 2 or more.
Examples of the organic group include an alkoxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), and an aryloxy group (preferably having 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms), an amino group (preferably 0 to 12 carbon atoms, more preferably 0 to 6 carbon atoms, particularly preferably 0 to 3 carbon atoms), an acyloxy group (preferably 1 to 12 carbon atoms, more preferably Has 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms, an alkyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms), an alkenyl group ( Preferably it has 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms, particularly preferably 2 to 4 carbon atoms, and an alkynyl group (preferably 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms, particularly preferably Carbon number To 4), a cycloalkyl group (preferably having 3 to 12 carbon atoms, more preferably 3 to 6 carbon atoms), an aryl group (preferably having 6 to 22 carbon atoms, more preferably 6 to 10 carbon atoms), an alkyl halide And groups (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms). Of these, an alkoxy group, an aryloxy group, and an amino group are preferable.

Examples of the linking group include an alkane linking group having 1 to 12 carbon atoms, a cycloalkane linking group having 3 to 12 carbon atoms, an aryl linking group having 6 to 24 carbon atoms, a heteroaryl linking group having 3 to 12 carbon atoms, and an oxy linking group. (—O—), thio linking group (—S—), phosphinidene linking group (—PR—: R is as defined above), silyl linking group (—SiRR′—: R, R ′ are (Synonyms) carbonyl linking group, imino linking group (—NR—: R is synonymous with the above organic group and may be a moiety of formulas (A) to (B). ), Or a combination thereof, among which an alkane linking group having 1 to 7 carbon atoms, an aryl linking group having 6 to 24 carbon atoms, an oxy linking group, and an imino linking group. , A thio linking group or a combination thereof Door is preferable. Here, the linking group means a divalent or higher valent group of the above group, and the alkane linking group refers to an alkylene group (divalent), alkanetriyl group (trivalent), alkanetetrayl group (tetravalent). Including meaning. These linking groups may further have the above-described substituent Z, or may be through the linking group (L).

Of these, R _a is preferably R _a '-X ^1- *. R _a ′ is a divalent to tetravalent alkane linking group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms), a divalent to tetravalent aryl linking group (preferably having 6 to 14 carbon atoms, and more). Preferably, it has 6 to 10 carbon atoms, and a divalent to tetravalent alkane linking group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms) having 1 to 8 linking groups (L) interposed therebetween is preferable. . X ¹ has the same meaning as the above formula (B). * Represents a bond. At this time, R _a ′ may constitute a linking group in the form of # —R _a ′ —X ¹ —R _a ′ — #. # Represents the bonding site to the _{R a} '-X ^1, # - total number is equal to _{n a} of.

R ¹ to R ³ are groups having the same definitions as in the formula (A).

The above formula (A1) is preferably represented by the following formula (B1).

n _b is an integer of 2 to 6.

R _b represents a divalent to hexavalent linking group. Preferable examples of the linking group include the linking groups exemplified for _Ra . Among these, R _a '-* or # -R _a ' -X ¹ -R _a '-# is preferable. * Represents the bonding position to X ^21, the number of coupling positions is equal to nb. # Denotes the bonding position to X ^21, a total number of the binding position is equal to nb.

X ²¹ is a linking group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. Its Preferred are the same as X ^1.

R ¹ to R ³ are groups having the same definitions as in the formula (A).
Furthermore, the specific additive is preferably any one of the following formulas (c-1) to (c-4). In the formula, R ^AB is a substituent of the formula (A) or (B). T ¹ is a hydrogen atom, a substituent of the formula (A) or (B), or an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, particularly preferably 1 to 3 carbon atoms). . L ^A is an alkylene group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms) or an arylene group (preferably having 6 to 14 carbon atoms, more preferably 6 to 10 carbon atoms) is. X ³ is a single bond or an alkylene group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, particularly preferably 1 to 3 carbon atoms).

Specific examples of the specific additive are shown below, but the present invention is not construed as being limited thereto.

The concentration of the specific additive in the electrolyte solution is not particularly limited, but from the viewpoint of promoting sufficient gas generation during overcharge without impeding charge / discharge during normal charging of the battery, 0.5 mass% or more, preferably 1 mass% or more, particularly preferably 2 mass% or more. The upper limit is 10% by mass or less, more preferably 8% by mass or less, further preferably less than 5% by mass, and particularly preferably 4.5% by mass or less. By setting it to the above lower limit or more, good overcharge prevention properties (gas generation properties) can be obtained. By setting it to the upper limit value or less, it is possible to obtain good stability and maintainability of performance without hindering the operation of the battery. In particular, this lower limit is important, and unlike a normal functional additive, it is required to apply a sufficient amount in order to secure the amount of gas generated.

[Acid generator]
The electrolytic solution according to the present invention preferably contains an acid generator having a functional group that generates an acid upon oxidation. Specifically, the functional group that generates an acid upon oxidation is preferably a functional group that generates a cation radical by oxidation and releases H ⁺ by a subsequent reaction. Thereby, the said additive decomposes | disassembles in a chain and can generate | occur | produce a gas rapidly. The functional group that generates an acid is not particularly limited, and examples thereof include an aryl group (preferably having 6 to 22 carbon atoms, more preferably 6 to 10 carbon atoms), a heterocyclic group, and the like.

Specific examples of the acid generator include heterocyclic compounds, biphenyl compounds, and alkyl-substituted benzene compounds. The heterocyclic compound may have a substituent on the heterocyclic ring, and a preferable substituent is an alkoxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms). An acyloxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms). Particularly preferably 1 to 4 carbon atoms), a cycloalkyl group (preferably 3 to 12 carbon atoms, more preferably 3 to 6 carbon atoms), an aryl group (preferably 6 to 22 carbon atoms, more preferably 6 carbon atoms). To 10).
Examples of the heterocyclic compound include 3- to 7-membered S-containing, N-containing, and O-containing heterocyclic compounds (the number of carbon atoms constituting the ring is preferably 3 to 6, and more preferably 4 to 6). Of these, pyrazole, triazole, furan, pyrrole, thiophene, indole, triazine, imidazole and the like are preferable, and these compounds may have a substituent T described later.
The biphenyl compound has a partial structure in which two benzene rings are bonded by a single bond, and the benzene ring may have a substituent, and preferred substituents are alkyl groups having 1 to 4 carbon atoms (for example, Methyl, ethyl, propyl, t-butyl, etc.) and aryl groups having 6 to 10 carbon atoms (eg, phenyl, naphthyl, etc.).
Specific examples of the biphenyl compound include biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, 4-methylbiphenyl, 4-ethylbiphenyl, and 4-tert-butylbiphenyl.
The alkyl-substituted benzene compound is preferably a benzene compound substituted with an alkyl group having 1 to 10 carbon atoms, and specific examples include cyclohexylbenzene, t-amylbenzene, and t-butylbenzene.

In the present invention, the acid generator may not be added, and the decomposition of the specific additive may proceed in the electrolyte during overcharge. In this decomposition, the reaction may proceed through the above-described reaction mechanism or another reaction mechanism. However, according to the chain reaction, even when an acid generator is added, the amount can be suppressed to a very small amount. Therefore, the acid generator may be added in a very small amount, and the addition amount thereof is preferably 10% by mass or less, more preferably 5% by mass or less, in the total amount of the electrolyte solution (including the electrolyte), It is more preferably 3% by mass or less, and particularly preferably 1% by mass or less. The lower limit is not particularly limited, but when added, for the purpose of obtaining the effect, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and 0.3% by mass. The above is particularly preferable.

The ratio of the additive to the acid generator, and the ratio of additive / acid generator (by mass) is preferably 0.01 to 1000, more preferably 1 to 100, and more preferably 5 to 10. More preferably.

(Organic solvent)
As the organic solvent used in the present invention, an organic solvent in which 20 to 95% by volume is composed of a primary chain carbonate compound is used. The reason for this is to contain the primary chain carbonate to lower the viscosity and improve the battery performance. Examples of the primary chain carbonate compound include organic solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (methyl n-propyl carbonate), ethylene glycol dimethyl carbonate, Examples thereof include ethylene glycol diethyl carbonate and propylene glycol dimethyl carbonate. These may be used alone or in combination of two or more. The amount of the primary linear carbonate compound is further preferably 25% by volume or more, and more preferably 30% by volume or more. The upper limit is preferably 90% by volume or less, more preferably 80% by volume or less, and particularly preferably 70% by volume or less.

The organic solvent that can be used in combination is not particularly limited, but is preferably an aprotic organic solvent, and more preferably an aprotic organic solvent having 2 to 10 carbon atoms. The organic solvent is preferably a compound having an ether group, a carbonyl group, an ester group, or a carbonate group. The said compound may have a substituent and the postscript substituent T is mentioned as the example.

Examples of organic solvents that can be combined include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3- Dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate, trimethyl Ethyl acetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N, N'-dimethyli Dazorijinon, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, dimethyl sulfoxide phosphate and the like. These may be used alone or in combination of two or more.
The amount of organic solvent that can be used in combination preferably constitutes the remainder of the amount of the primary linear carbonate compound.

(Functional additives)
The electrolytic solution of the present invention preferably contains various functional additives. Examples of the function manifested by this additive include improved flame retardancy, improved cycle characteristics, and improved capacity characteristics. Examples of functional additives that are preferably applied to the electrolyte of the present invention are shown below.

<Imide compound (A)>
As the imide compound, a sulfonimide compound having a perfluoro group is preferable from the viewpoint of oxidation resistance, and specifically, a perfluorosulfoimide lithium compound may be mentioned.
Specific examples of the imide compound include the following structures, and Cex1 and Cex2 are more preferable.

<Halogen-containing compound (B)>
The halogen atom contained in the halogen-containing compound is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a fluorine atom. The number of halogen atoms is preferably 1 to 6, more preferably 1 to 3. The halogen-containing compound is preferably a carbonate compound substituted with a fluorine atom, a polyether compound having a fluorine atom, or a fluorine-substituted aromatic compound.
The halogen-substituted carbonate compound may be either linear or cyclic. From the viewpoint of ion conductivity, a cyclic carbonate compound having a high coordination property of an electrolyte salt (for example, lithium ion) is preferable, and a 5-membered cyclic carbonate compound is particularly preferable. preferable.
Preferred specific examples of the halogen-substituted carbonate compound are shown below. Among these, compounds of Bex1 to Bex4 are particularly preferable, and Bex1 is particularly preferable.

<Polymerizable compound (C)>
The polymerizable compound is preferably a compound having a carbon-carbon double bond, and is selected from carbonate compounds having a double bond such as vinylene carbonate and vinyl ethylene carbonate, acrylate groups, methacrylate groups, cyanoacrylate groups, and αCF ₃ acrylate groups. A compound having a group and a compound having a styryl group are preferable, and a carbonate compound having a double bond or a compound having two or more polymerizable groups in the molecule is more preferable.

<Phosphorus-containing compound (D)>
As a phosphorus containing compound, a phosphate ester compound and a phosphazene compound are preferable. Preferable examples of the phosphate ester compound include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and tribenzyl phosphate. As the phosphorus-containing compound, a compound represented by the following formula (D2) or (D3) is also preferable.

In the formula, R ^D4 to R ^D11 each represent a monovalent substituent. Among the monovalent substituents, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a halogen atom such as fluorine, chlorine or bromine is preferable. At least one of the substituents of R ^D4 to R ^D11 is preferably a fluorine atom, more preferably a substituent composed of an alkoxy group, an amino group, or a fluorine atom.

<Sulfur-containing compound (E)>
As the sulfur-containing compound, a compound having —SO ₂ —, —SO ₃ —, —OS (═O) O— bond is preferable, and cyclic sulfur-containing compounds such as propane sultone, propene sultone, ethylene sulfite, and sulfonic acid Esters are preferred.

As the sulfur-containing cyclic compound, compounds represented by the following formulas (E1) and (E2) are preferable.

In the formula, X ^E1 and X ^E2 each independently represent —O— or —C (Ra) (Rb) —. Here, Ra and Rb each independently represent a hydrogen atom or a substituent. As the substituent, an alkyl group having 1 to 8 carbon atoms, a fluorine atom, and an aryl group having 6 to 12 carbon atoms are preferable. α represents an atomic group necessary for forming a 5- to 6-membered ring. The skeleton of α may contain a sulfur atom, an oxygen atom, etc. in addition to a carbon atom. α may be substituted, and examples of the substituent include a substituent T, preferably an alkyl group, a fluorine atom, and an aryl group.

<Silicon-containing compound (F)>
As the silicon-containing compound, a compound represented by the following formula (F1) or (F2) is preferable.

R ^F1 represents an alkyl group, an alkenyl group, an acyl group, an acyloxy group, or an alkoxycarbonyl group.
R ^F2 represents an alkyl group, an alkenyl group, an alkynyl group, or an alkoxy group.
A plurality of R ^F1 and R ^{F2 in} one formula may be different or the same.

<Nitrile compound (G)>
As the nitrile compound, a compound represented by the following formula (G) is preferable.

In the formula, R ^G1 to R ^G3 each independently represent a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, a carbamoyl group, a sulfonyl group, or a phosphonyl group. As examples of the preferable substituents, examples of the substituent T can be referred to, and among them, a compound in which any one of R ^G1 to R ^G3 has a plurality of cyano groups is preferable.

-Ng represents an integer of 1-8.

Specific examples of the compound represented by the formula (G) include acetonitrile, propionitrile, isobutyronitrile, succinonitrile, malononitrile, glutaronitrile, adiponitrile, 2-methylglutanonitrile, hexanetricarbonitrile, propane. Tetracarbonitrile and the like are preferable. Particularly preferred are succinonitrile, malononitrile, glutaronitrile, adiponitrile, 2-methylglutanonitrile, hexanetricarbonitrile, and propanetetracarbonitrile.

<Metal complex compound (H)>
As the metal complex compound, a transition metal complex or a rare earth complex is preferable. Of these, complexes represented by any of the following formulas (H-1) to (H-3) are preferred.

In the formula, X ^H and Y ^H are a methyl group, an n-butyl group, a bis (trimethylsilyl) amino group, and a thioisocyanate group, respectively, and X ^H and Y ^H are condensed to form a cyclic alkenyl group (butadiene group). (Positional metallacycle) may be formed. In the formula, ^MH represents a transition element or a rare earth element. Specifically, ^MH is preferably Fe, Ru, Cr, V, Ta, Mo, Ti, Zr, Hf, Y, La, Ce, Sw, Nd, Lu, Er, Yb, and Gd. m ^H and n ^H are integers satisfying 0 ≦ m ^H + n ^H ≦ 3. n ^H + m ^H is preferably 1 or more. When n ^H and m ^H are 2 or more, the 2 or more groups defined therein may be different from each other.

The metal complex compound is also preferably a compound having a partial structure represented by the following formula (H-4).

M ^H — (NR ^1H R ^2H ) q ^H Formula (H-4)

In the formula, ^MH represents a transition element or a rare earth element and is synonymous with formulas (H-1) to (H-3).

R ^1H and R ^2H are hydrogen, an alkyl group (preferably having a carbon number of 1 to 6), an alkenyl group (preferably having a carbon number of 2 to 6), an alkynyl group (preferably having a carbon number of 2 to 6), and an aryl group (preferably having a carbon number). Represents a heteroaryl group (preferably having a carbon number of 3 to 6), an alkylsilyl group (preferably having a carbon number of 1 to 6), or a halogen. R ^1H and R ^2H may be linked to each other. R ^1H and R ^2H may each be connected to form a ring. Preferable examples of R ^1H and R ^2H include examples of the substituent T described later. Of these, a methyl group, an ethyl group, and a trimethylsilyl group are preferable.
q ^H represents an integer of 1 to 4, preferably an integer of 2 to 4. More preferably, it is 2 or 4. When q ^H is 2 or more, where a plurality of groups as defined may be the same or different from each other.

The metal complex compound is also preferably a compound represented by any of the following formulas.

・ M ^h
The central metal ^M h is, Ti, Zr, ZrO, Hf , V, Cr, Fe, Ce is particularly preferred, Ti, Zr, Hf, V , Cr is the most preferred.

・ R ^3h , R ^5h , R ^7h to R ^10h
These represent substituents. Of these, an alkyl group, an alkoxy group, an aryl group, an alkenyl group, and a halogen atom are preferable. An alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and 2 carbon atoms. More preferred are alkenyl groups of 6 to 6 and are preferably methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, perfluoromethyl, methoxy, phenyl, ethenyl.

・ R ^33h , R ^55h
R ^33h and R ^55h represent a hydrogen atom or a substituent of R ^3h .

・ Y ^h
Y ^h is preferably an alkyl group having 1 to 6 carbon atoms or a bis (trialkylsilyl) amino group, and more preferably a methyl group or a bis (trimethylsilyl) amino group.

^{· L h, m h, o} h
l ^h , m ^h , and o ^h represent an integer of 0 to 3, and an integer of 0 to 2 is preferable. When l ^h , m ^h , and o ^h are 2 or more, the plurality of structural portions defined therein may be the same as or different from each other.

・ L ^h
L ^h is preferably an alkylene group or an arylene group, more preferably a cycloalkylene group having 3 to 6 carbon atoms or an arylene group having 6 to 14 carbon atoms, and further preferably cyclohexylene or phenylene.

The electrolytic solution of the present invention may contain at least one selected from the above, a negative electrode film forming agent, a flame retardant, an overcharge preventing agent and the like. The content ratio of these functional additives in the nonaqueous electrolytic solution is not particularly limited, but is preferably 0.001% by mass to 10% by mass with respect to the entire nonaqueous electrolytic solution (including the electrolyte). By adding these compounds, it is possible to suppress the rupture of the battery at the time of abnormality due to overcharge, or to improve the capacity maintenance characteristic and cycle characteristic after high temperature storage.

The above exemplary compounds may have an arbitrary substituent T.
Examples of the substituent T include the following.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl group (Preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl, etc.), cycloalkyl group (Preferably a cycloalkyl group having 3 to 20 carbon atoms such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms such as phenyl, 1-naphthyl, etc. 4-methoxyphenyl, 2-chlorophenyl, -Methylphenyl, etc.), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, preferably a 5- or 6-membered heterocyclic group having at least one oxygen atom, sulfur atom, nitrogen atom, For example, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl and the like, an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy , Benzyloxy, etc.), aryloxy groups (preferably aryloxy groups having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), alkoxycarbonyl groups (preferably carbon A number 2 to 20 alkoxycarbonyl group such as ethoxycarbonyl 2-ethylhexyloxycarbonyl, etc.), amino groups (preferably containing amino groups having 0 to 20 carbon atoms, alkylamino groups, arylamino groups, such as amino, N, N-dimethylamino, N, N-diethylamino, N -Ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfonamido groups having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl etc.), acyl groups (preferably carbon atoms) 1 to 20 acyl groups such as acetyl, propionyl, butyryl and benzoyl), acyloxy groups (preferably 1 to 20 carbon atoms such as acetyloxy and benzoyloxy), carbamoyl groups (preferably carbon atoms) 1 to 20 carbamoyl groups such as N, N-dimethylcarbamoyl, N— Phenylcarbamoyl, etc.), acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms, such as acetylamino, benzoylamino, etc.), sulfonamido groups (preferably sulfamoyl groups having 0 to 20 carbon atoms, such as methanesulfonamide, Benzenesulfonamide, N-methylmethanesulfonamide, N-ethylbenzenesulfonamide, etc.), alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, such as methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio group (preferably Is an arylthio group having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc., an alkyl or arylsulfonyl group (preferably an alkyl having 1 to 20 carbon atoms) Or an arylsulfonyl group such as methylsulfonyl, ethylsulfonyl, and benzenesulfonyl), a hydroxyl group, a cyano group, and a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), and more preferably an alkyl group. , Alkenyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, amino group, acylamino group, hydroxyl group or halogen atom, particularly preferably alkyl group, alkenyl group, heterocyclic group, alkoxy group Group, alkoxycarbonyl group, amino group, acylamino group or hydroxyl group.
In addition, each of the groups listed as the substituent T may be further substituted with the substituent T described above.

In the present specification, when a compound or a substituent / linking group includes an alkyl group / alkylene group, an alkenyl group / alkenylene group, etc., these may be cyclic or chain-like, and may be linear or branched, It may be substituted as described above or may be unsubstituted. Moreover, when an aryl group, a heterocyclic group, etc. are included, they may be monocyclic or condensed and may be similarly substituted or unsubstituted.

(Electrolytes)
The electrolyte used in the electrolytic solution of the present invention is preferably a salt of a metal ion belonging to Group 1 or Group 2 of the Periodic Table. The material is appropriately selected depending on the intended use of the electrolytic solution. For example, lithium salt, potassium salt, sodium salt, calcium salt, magnesium salt and the like can be mentioned. When used in a secondary battery or the like, lithium salt is preferable from the viewpoint of output. When the electrolytic solution of the present invention is used as an electrolyte of a non-aqueous electrolytic solution for a lithium secondary battery, a lithium salt may be selected as a metal ion salt. The lithium salt is not particularly limited as long as it is a lithium salt usually used for an electrolyte of a non-aqueous electrolyte solution for a lithium secondary battery. For example, those described below are preferable.

(L-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; perhalogenates such as LiClO ₄ , LiBrO ₄ , LiIO ₄ ; inorganic chloride salts such as LiAlCl ₄ etc.

(L-2) Fluorine-containing organic lithium salt: perfluoroalkane sulfonate such as LiCF ₃ SO ₃ ; LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , Perfluoroalkanesulfonylimide salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); perfluoroalkanesulfonylmethide salts such as LiC (CF ₃ SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF _{3 )], Li [PF 4 (} CF 2 CF 2 CF 2 CF 3) 2], Li [PF 3 (CF 2 CF 2 CF 2 CF 3) 3] fluoroalkyl fluoride such as potash Acid salts, and the like.

(L-3) Oxalatoborate salt: lithium bis (oxalato) borate, lithium difluorooxalatoborate and the like.
Among these, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , Li (Rf ¹ SO ₃ ), LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ), preferably LiPF ₆ , LiBF ₄ , LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) More preferred are imide salts. Here, Rf ¹ and Rf ² each represent a perfluoroalkyl group.
In addition, the electrolyte used for electrolyte solution may be used individually by 1 type, or may combine 2 or more types arbitrarily.
The content of the electrolyte (metal ions belonging to Group 1 or Group 2 of the periodic table or a metal salt thereof) in the electrolytic solution is added in an amount that provides a preferable salt concentration described below in the method for preparing the electrolytic solution. The salt concentration is appropriately selected depending on the intended use of the electrolytic solution, but is generally 10% to 50% by mass, more preferably 15% to 30% by mass, based on the total mass of the electrolytic solution. In addition, when evaluating as an ion density | concentration, what is necessary is just to calculate by salt conversion with the metal applied suitably.

[Method for preparing electrolytic solution]
The electrolyte solution for a non-aqueous secondary battery of the present invention is prepared by a conventional method by dissolving the above components in the non-aqueous electrolyte solvent, including an example in which a lithium salt is used as a metal ion salt.

In the present invention, “non-water” means that water is not substantially contained, and a trace amount of water may be contained as long as the effects of the invention are not hindered. In view of obtaining good characteristics, the water content is preferably 200 ppm (mass basis) or less, more preferably 100 ppm or less, and even more preferably 20 ppm or less. Although there is no lower limit in particular, it is practical that it is 1 ppm or more considering inevitable mixing. The viscosity of the electrolytic solution of the present invention is not particularly limited, but it is preferably 10 to 0.1 mPa · s, more preferably 5 to 0.5 mPa · s at 25 ° C.
In the present invention, the viscosity of the electrolytic solution is based on the value measured by the following measuring method unless otherwise specified.

<Measurement method of viscosity>
The viscosity is a value measured by the following method. 1 mL of a sample is put into a rheometer (CLS 500) and measured using a Steel Cone (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °. The sample is kept warm in advance until the temperature becomes constant at the measurement start temperature, and the measurement starts thereafter. The measurement temperature is 25 ° C.

[Secondary battery]
In this invention, it is preferable to set it as the non-aqueous secondary battery containing the said non-aqueous electrolyte. As a preferred embodiment, a lithium ion secondary battery will be described with reference to FIG. 1 schematically showing the mechanism. The lithium ion secondary battery 10 of this embodiment includes the electrolyte solution 5 for a non-aqueous secondary battery of the present invention and a positive electrode C capable of inserting and releasing lithium ions (a positive electrode current collector 1 and a positive electrode active material layer 2). And a negative electrode A (negative electrode current collector 3, negative electrode active material layer 4) capable of inserting and releasing lithium ions or dissolving and depositing lithium ions. In addition to these essential members, considering the purpose of use of the battery, the shape of the potential, etc., a separator 9 disposed between the positive electrode and the negative electrode, a current collecting terminal (not shown), an outer case, etc. (Not shown). If necessary, a protective element may be attached to at least one of the inside of the battery and the outside of the battery. By adopting such a structure, lithium ion transfer a and b occurs in the electrolytic solution 5, charging α and discharging β can be performed, and operation or power storage is performed via the operation mechanism 6 via the circuit wiring 7. It can be performed. Hereinafter, the configuration of the lithium secondary battery which is a preferred embodiment of the present invention will be described in more detail.

(Battery shape)
The battery shape to which the lithium secondary battery of the present embodiment is applied is not particularly limited, and examples thereof include a bottomed cylindrical shape, a bottomed square shape, a thin shape, a sheet shape, and a paper shape. Any of these may be used. Further, it may be of a different shape such as a horseshoe shape or a comb shape considering the shape of the system or device to be incorporated. Among them, from the viewpoint of efficiently releasing the heat inside the battery to the outside, a square shape such as a bottomed square shape or a thin shape having at least one surface that is relatively flat and has a large area is preferable.

In the case of a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging or discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 is an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18.

In the bottomed square shape, the ratio of the area S of the largest surface (the product of the width and height of the outer dimensions excluding the terminal portion, unit cm ² ) to the thickness T (unit cm) of the battery outer shape The 2S / T value is preferably 100 or more, and more preferably 200 or more. By increasing the maximum surface, it is possible to improve characteristics such as cycle performance and high-temperature storage even for high-power and large-capacity batteries, and increase the heat dissipation efficiency during abnormal heat generation. It is possible to suppress the state of “rupture”.

(Members constituting the battery)
The lithium secondary battery according to the present embodiment is configured to include the electrolytic solution 5, the positive electrode and negative electrode electrode mixtures C and A, and the separator basic member 9, based on FIG. 1. Hereinafter, each of these members will be described.

(Electrode mixture)
The electrode mixture is obtained by applying a dispersion of an active material and a conductive agent, a binder, a filler, etc. on a current collector (electrode substrate). In a lithium battery, the active material is a positive electrode active material. It is preferable to use a negative electrode mixture in which the positive electrode mixture and the active material are a negative electrode active material. Next, each component in the dispersion (electrode composition) constituting the electrode mixture will be described.

-Positive electrode active material It is preferable to use a transition metal oxide for the positive electrode active material, and in particular, it has a transition element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, V). Is preferred. Further, mixed element M ^b (elements of the first (Ia) group of the metal periodic table other than lithium, elements of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si , P, B, etc.) may be mixed. Examples of the transition metal oxide include specific transition metal oxides including those represented by any of the following formulas (MA) to (MC), or other transition metal oxides such as V ₂ O ₅ and MnO _2. Is mentioned. As the positive electrode active material, a particulate positive electrode active material may be used. Specifically, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but the specific transition metal oxide is preferably used.

The transition metal oxides, oxides containing the above transition element M ^a is preferably exemplified. At this time, a mixed element M ^b (preferably Al) or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the amount of the transition metal. That the molar ratio of li / ^{M a} was synthesized were mixed so that 0.3 to 2.2, more preferably.

[Transition metal oxide represented by formula (MA) (layered rock salt structure)]
As the lithium-containing transition metal oxide, those represented by the following formula are preferable.
Li _a M ¹ O _b (MA)

Wherein, ^{M 1} is as defined above Ma. a represents 0 to 1.2 (preferably 0.2 to 1.2), and preferably 0.6 to 1.1. b represents 1 to 3 and is preferably 2. A part of M ¹ may be substituted with the mixed element M ^b . The transition metal oxide represented by the above formula (MA) typically has a layered rock salt structure.

The transition metal oxide is more preferably one represented by the following formulas.
_{(MA-1) Li g CoO} k
_{(MA-2) Li g NiO} k
_{(MA-3) Li g MnO} k
_{(MA-4) Li g Co} j Ni 1-j O k
_{(MA-5) Li g Ni} j Mn 1-j O k
_{(MA-6) Li g Co} j Ni i Al 1-j-i O k
_{(MA-7) Li g Co} j Ni i Mn 1-j-i O k

Here, g has the same meaning as a. j represents 0.1 to 0.9. i represents 0 to 1; However, 1-ji is 0 or more. k has the same meaning as b above. Specific examples of the transition metal compound include LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate) LiNi _0.85 Co _0.01 Al _0.05 O ₂ (nickel cobalt aluminum acid Lithium [NCA]), LiNi _0.33 Co _0.33 Mn _0.33 O ₂ (lithium nickel manganese cobaltate [NMC]), LiNi _0.5 Mn _0.5 O ₂ (lithium manganese nickelate).

The transition metal oxide represented by the formula (MA) partially overlaps, but when represented by changing the notation, those represented by the following are also preferable examples.
_{(I) Li g Ni x Mn} y Co z O 2 (x> 0.2, y> 0.2, z ≧ 0, x + y + z = 1)
Representative:
_{Li g Ni 1/3 Mn 1/3 Co 1/3} O 2
Li _g Ni _1/2 Mn _1/2 O _{2
(Ii) Li g Ni x Co} y Al z O 2 (x> 0.7, y>0.1,0.1>z> 0.05, x + y + z = 1)
Representative:
_{Li g Ni 0.8 Co 0.15 Al 0.05} O 2

[Transition metal oxide represented by formula (MB) (spinel structure)]
Among the lithium-containing transition metal oxides, those represented by the following formula (MB) are also preferable.
Li _c M ² ₂ O _d (MB)

Wherein, ^{M 2} is as defined above Ma. c represents 0 to 2 (preferably 0.2 to 2), and preferably 0.6 to 1.5. d represents 3 to 5 and is preferably 4.

The transition metal oxide represented by the formula (MB) is more preferably one represented by the following formulas.
_{(MB-1) Li m Mn} 2 O n
_{(MB-2) Li m Mn} p Al 2-p O n
_{(MB-3) Li m Mn} p Ni 2-p O n

m is synonymous with c. n is synonymous with d. p represents 0-2. Specific examples of the transition metal compound are LiMn ₂ O ₄ and LiMn _1.5 Ni _0.5 O ₄ .

Preferred examples of the transition metal oxide represented by the formula (MB) include those represented by the following.
(A) LiCoMnO ₄
(B) Li ₂ FeMn ₃ O ₈
(C) Li ₂ CuMn ₃ O ₈
(D) Li ₂ CrMn ₃ O ₈
(E) Li ₂ NiMn ₃ O ₈
Of these, an electrode containing Ni is more preferable from the viewpoint of high capacity and high output.

[Transition metal oxide represented by formula (MC)]
As the lithium-containing transition metal oxide, it is also preferable to use a lithium-containing transition metal phosphor oxide, and among them, one represented by the following formula (MC) is also preferable.
Li _e M ³ (PO ₄ ) _f ... (MC)

In the formula, e represents 0 to 2, preferably 0.1 to 1.15, and more preferably 0.5 to 1.5. f represents 1 to 5, and preferably 0.5 to 2.

The M ³ represents one or more elements selected from V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. The ^{M 3} are, in addition to the mixing element ^{M b} above, Ti, Cr, Zn, Zr, may be substituted by other metals such as Nb. Specific examples include, for example, olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and Li _3. Monoclinic Nasicon type vanadium phosphate salts such as V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate) can be mentioned.
The a, c, g, m, and e values representing the composition of Li are values that change due to charge and discharge, and are typically evaluated as values in a stable state when Li is contained. In the above formulas (a) to (e), the composition of Li is shown as a specific value, but this also varies depending on the operation of the battery.

In the present invention, the positive electrode active material is preferably a material that can maintain normal use at a positive electrode potential (Li / Li ⁺ standard) of 3.5 V or higher, more preferably 3.8 V or higher, and more preferably 4 V or higher. More preferably, it is 4.2 V or more. Although there is no upper limit in particular, it is practical that it is 5V or less. By setting it as the above range, cycle characteristics and high rate discharge characteristics can be improved.
Here, being able to maintain normal use means that even when charging is performed at that voltage, the electrode material does not deteriorate and cannot be used, and this potential is also referred to as a normal usable potential.
The positive electrode potential during charging / discharging (Li / Li ⁺ reference) is (positive electrode potential) = (negative electrode potential) + (battery voltage). When lithium titanate is used as the negative electrode, the negative electrode potential is 1.55V. When graphite is used as the negative electrode, the negative electrode potential is 0.1V. The battery voltage is observed during charging and the positive electrode potential is calculated.

In the nonaqueous secondary battery of the present invention, the average particle size of the positive electrode active material used is not particularly limited, but is preferably 0.1 μm to 50 μm. The specific surface area is not particularly limited, but is preferably 0.01 m ² / g to 50 m ² / g by the BET method. Further, the pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.

A well-known pulverizer or classifier is used to make the positive electrode active substance have a predetermined particle size. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. The positive electrode active material obtained by the above firing method may be used after washing with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

The blending amount of the positive electrode active material is not particularly limited, but is preferably 60 to 98% by mass, and 70 to 95% by mass in 100% by mass of the solid component in the dispersion (mixture) for constituting the active material layer. % Is more preferable.
・ Negative electrode active material The negative electrode active material is not particularly limited as long as it can reversibly insert and release lithium ions. Carbonaceous materials, metal oxides such as tin oxide and silicon oxide, metal composite oxides, Examples thereof include lithium alloys such as lithium alone and lithium aluminum alloys, and metals capable of forming an alloy with lithium such as Sn and Si. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Of these, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of safety. Further, the metal composite oxide is not particularly limited as long as it can occlude and release lithium, but it preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. .

The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.

These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has a face spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473. The carbonaceous material does not have to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.

As the metal oxide and metal composite oxide applied as the negative electrode active material, an amorphous oxide is particularly preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferably used. It is done. The term “amorphous” as used herein means an X-ray diffraction method using CuKα rays, which has a broad scattering band having a peak in the region of 20 ° to 40 ° in terms of 2θ, and is a crystalline diffraction line. You may have. The strongest intensity of crystalline diffraction lines seen from 2 ° to 40 ° to 70 ° is 100 times the diffraction line intensity at the peak of the broad scattering band seen from 2 ° to 20 °. It is preferable that it is 5 times or less, and it is particularly preferable not to have a crystalline diffraction line.

Among the group of compounds consisting of the above amorphous oxide and chalcogenide, amorphous metal oxides and chalcogenides are more preferable, and elements in groups 13 (IIIB) to 15 (VB) of the periodic table are preferable. Particularly preferred are oxides and chalcogenides composed of one kind of Al, Ga, Si, Sn, Ge, Pb, Sb, Bi or a combination of two or more kinds thereof. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , such as SnSiS ₃ may preferably be mentioned. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

The average particle size of the negative electrode active material is preferably 0.1 μm to 60 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill or a sieve is preferably used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.

The chemical formula of the compound obtained by the above firing method can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method, and from a mass difference between powders before and after firing as a simple method.

Examples of the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centering on Sn, Si, and Ge include carbon materials that can occlude and release lithium ions or lithium metal, lithium, lithium alloys, lithium A metal that can be alloyed with is preferable.

The electrolyte solution of the present invention is preferably a high potential negative electrode (electrode potential of 1.0 V or higher, more preferably 1.2 V or higher, particularly preferably 1.5 V or higher. Specifically, lithium-titanium oxide, potential 1 .55V vs. Li metal) and in combination with a low potential negative electrode (preferably carbon material, silicon-containing material, potential about 0.1 V vs. Li metal). . Further, metal or metal oxide negative electrodes (preferably Si, Si oxide, Si / Si oxide, Sn, Sn oxide, SnB _x P _y O _z , Cu, which can be alloyed with lithium, which are being developed for higher capacity) / Sn and a plurality of these composites), and a battery using a composite of these metals or metal oxides and a carbon material as a negative electrode.

The negative electrode active material used in the nonaqueous secondary battery of the present invention preferably contains a titanium atom. More specifically, since Li ₄ Ti ₅ O ₁₂ has a small volume fluctuation at the time of occlusion and release of lithium ions, it has excellent rapid charge / discharge characteristics, suppresses electrode deterioration, and improves the life of lithium ion secondary batteries. This is preferable. By combining a specific negative electrode and a specific electrolyte, the stability of the secondary battery is improved even under various usage conditions.

-Conductive material As the conductive material, any electronic conductive material that does not cause a chemical change in the configured secondary battery may be used, and any known conductive material may be used. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, aluminum, silver (Japanese Patent Laid-Open No. Sho 63-63)) 148, 554), etc.), conductive fibers such as metal fibers or polyphenylene derivatives (described in JP-A-59-20971) can be included as a single kind or a mixture thereof. Among these, the combined use of graphite and acetylene black is particularly preferable. The addition amount of the conductive agent is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.

-Binders Examples of binders include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Among them, for example, starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose. Water-soluble, such as sodium alginate, polyacrylic acid, sodium polyacrylate, polyvinylphenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylonitrile, polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer Polymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinyl Redene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, etc. ) (Meth) acrylic ester copolymer containing acrylic ester, (meth) acrylic ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer , Acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluoro rubber, polyethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate Polyurethane resins, polyester resins, phenolic resins, emulsion (latex) or a suspension such as an epoxy resin is preferable, a latex of polyacrylate, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride is more preferable.

Binders can be used alone or in combination of two or more. When the amount of the binder added is small, the holding power and cohesive force of the electrode mixture are weakened. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit mass decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by mass, and more preferably 2 to 10% by mass.

-Filler The electrode compound material may contain the filler. As the material for forming the filler, any fibrous material that does not cause a chemical change in the secondary battery of the present invention can be used. Usually, fibrous fillers made of materials such as olefin polymers such as polypropylene and polyethylene, glass, and carbon are used. The addition amount of the filler is not particularly limited, but is preferably 0 to 30% by mass in the dispersion.

-Current collector As the positive / negative electrode current collector, an electron conductor that does not cause a chemical change in the nonaqueous electrolyte secondary battery of the present invention is used. As the current collector of the positive electrode, in addition to aluminum, stainless steel, nickel, titanium, etc., the surface of aluminum or stainless steel is preferably treated with carbon, nickel, titanium, or silver. Among them, aluminum and aluminum alloys are preferable. More preferred.

As the negative electrode current collector, aluminum, copper, stainless steel, nickel and titanium are preferable, and aluminum, copper and copper alloy are more preferable.

As the shape of the current collector, a film sheet shape is usually used, but a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 μm to 500 μm. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.
An electrode mixture of the lithium secondary battery is formed by a member appropriately selected from these materials.

(Separator)
The separator used in the non-aqueous secondary battery of the present invention is particularly a material that has mechanical strength for electrically insulating the positive electrode and the negative electrode, ion permeability, and oxidation / reduction resistance at the contact surface between the positive electrode and the negative electrode. There is no limit. As such a material, a porous polymer material, an inorganic material, an organic-inorganic hybrid material, glass fiber, or the like is used. These separators preferably have a shutdown function for ensuring safety, that is, a function of closing the gap at 80 ° C. or higher to increase resistance and blocking current, and the closing temperature is 90 ° C. or higher and 180 ° C. or lower. It is preferable.

The shape of the holes of the separator is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. The ratio of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.

The polymer material may be a single material such as a cellulose nonwoven fabric, polyethylene, or polypropylene, or may be a material using two or more composite materials. What laminated | stacked the 2 or more types of microporous film which changed the hole diameter, the porosity, the obstruction | occlusion temperature of a hole, etc. is preferable.

As the inorganic substance, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those having a particle shape or fiber shape are used. As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. As the thin film shape, those having a pore diameter of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm are preferably used. In addition to the above-described independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, alumina particles having a 90% particle diameter of less than 1 μm are formed on both surfaces of the positive electrode as a porous layer using a fluororesin binder.

(Production of non-aqueous secondary battery)
As described above, the shape of the nonaqueous secondary battery of the present invention can be applied to any shape such as a sheet shape, a square shape, and a cylinder shape. A positive electrode active material or a mixture of negative electrode active materials is mainly used after being applied (coated), dried and compressed on a current collector.

Hereinafter, with reference to FIG. 2, a configuration and a manufacturing method thereof will be described using the bottomed cylindrical lithium secondary battery 100 as an example. In a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging and discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 shows an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18. In addition, in the figure, 20 is an insulating plate, 22 is a sealing plate, 24 is a positive electrode current collector, 26 is a gasket, 28 is a pressure sensitive valve body, and 30 is a current interruption element. In addition, although the illustration in the enlarged circle has changed hatching in consideration of visibility, each member corresponds to the whole drawing by reference numerals.

First, a negative electrode active material is mixed with a binder or filler used as desired in an organic solvent to prepare a slurry or paste negative electrode mixture. The obtained negative electrode mixture is uniformly applied over the entire surface of both surfaces of the metal core as a current collector, and then the organic solvent is removed to form a negative electrode mixture layer. Further, the laminate of the current collector and the negative electrode composite material layer is rolled with a roll press or the like to prepare a predetermined thickness to obtain a negative electrode sheet (electrode sheet). At this time, the application method of each agent, the drying of the applied product, and the method of forming the positive and negative electrodes may be in accordance with conventional methods.

In the present embodiment, a cylindrical battery is taken as an example, but the present invention is not limited to this, for example, after the positive and negative electrode sheets produced by the above method are overlapped via a separator, After processing into a sheet battery as it is, or inserting it into a rectangular can after being folded and electrically connecting the can and the sheet, injecting an electrolyte and sealing the opening using a sealing plate A square battery may be formed.

In any of the embodiments, the safety valve can be used as a sealing plate for sealing the opening. In addition to the safety valve, the sealing member may be provided with various conventionally known safety elements. For example, a fuse, bimetal, PTC element, or the like is preferably used as the overcurrent prevention element.

In addition to the above safety valve, as a countermeasure against the increase in the internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.

For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are preferably used.

A known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used as a welding method for the cap, can, sheet, and lead plate. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

(Pressure sensitive mechanism)
The non-aqueous secondary battery according to the present invention preferably has a pressure-sensitive mechanism (a mechanism that cuts off current when a predetermined pressure or higher is reached). Although the pressure-sensitive mechanism uses a pressure-sensitive valve as described above, various devices such as a device that detects a pressure change by a pressure-sensitive sensor and interrupts energization can be employed. FIG. 3 is a partial cross-sectional side view showing another example of the pressure-sensitive valve.
As shown in FIG. 3, the current interrupting sealing body 50 is composed of a stainless steel positive electrode cap 51 formed in an inverted dish shape (cap shape) and a stainless steel bottom plate 54 formed in a dish shape. The The positive electrode cap 51 includes a convex portion 52 that bulges toward the outside of the battery, and a flat flange portion 53 that forms the bottom side of the convex portion 52, and a plurality of gas vents are formed at the corners of the convex portion 52. A hole 52a is provided. On the other hand, the bottom plate 54 includes a concave portion 55 that bulges toward the inside of the battery, and a flat flange portion 56 that constitutes the bottom side portion of the concave portion 55. A gas vent hole 55 a is provided at the corner of the recess 55.
Housed in the positive electrode cap 51 and the bottom plate 54 is a power lead-out plate 57 that deforms when the gas pressure inside the battery rises and exceeds a predetermined pressure. The power lead-out plate 57 includes a concave portion 57a and a flange portion 57b, and is formed of, for example, an aluminum foil having a thickness of 0.2 mm and a surface unevenness of 0.005 mm. The lowest portion of the recess 57 a is disposed in contact with the upper surface of the recess 55 of the bottom plate 54, and the flange portion 57 b is sandwiched between the flange portion 53 of the positive electrode cap 51 and the flange portion 56 of the bottom plate 54. . The positive electrode cap 51 and the bottom plate 54 are sealed in a liquid-tight manner by a sealing body insulating gasket 59 made of polypropylene (PP).
A PTC (Positive Temperature Coefficient) thermistor element 58 is disposed at a part of the upper portion of the flange portion 57b. When an overcurrent flows in the battery and an abnormal heat generation phenomenon occurs, the resistance value of the PTC thermistor element 58 increases. Increase to reduce overcurrent. Then, when the gas pressure inside the battery rises and exceeds a predetermined pressure, the recess 57a of the power lead-out plate 57 is deformed, so that the contact between the power lead-out plate 57 and the concave portion 55 of the bottom plate 54 is cut off and an overcurrent or short circuit occurs. The current is interrupted.
By using the electrolyte for a non-aqueous secondary battery according to the present invention, in the secondary battery having the pressure-sensitive mechanism, more gas is instantly generated at the time of overcharging, and accurate and quick interruption of current is possible. And

It is preferable that the specific aromatic compound of the present invention does not generate gas during normal charging but generates an effective amount of gas during overcharging. Here, “to generate an effective amount of gas at the time of overcharging” means that the results of the gas generation amount test and the charge life test at the time of overcharging in the examples described later are equivalent to the examples.

<Confirming the meaning of the terms here> Normal charging means a state in which charging is performed within the design voltage of the battery. For example, in a generally used constant current-constant voltage charging method, a method is used in which a constant current charge is performed until a set voltage is reached, and then a full charge is performed while the set voltage is maintained. The positive electrode potential during normal charging in the present application represents the positive electrode potential at the set voltage. On the other hand, overcharge refers to a state in which the battery is charged at a voltage exceeding the design voltage of the battery due to some factor.

[Applications of non-aqueous secondary batteries]

Secondary batteries called lithium batteries are secondary batteries that use the insertion and extraction of lithium for charge / discharge reactions (lithium ion secondary batteries), and secondary batteries that use precipitation and dissolution of lithium (lithium metal secondary batteries). ). In the present invention, application as a lithium ion secondary battery is preferable.
Since the nonaqueous secondary battery of the present invention can produce a secondary battery with good cycle performance, it is applied to various applications. Although there is no particular limitation on the application mode, for example, when installed in an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile phone Copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, memory card, etc. It is done. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.

In particular, it is preferable to be applied to applications that require high capacity and high rate discharge characteristics, particularly from the viewpoint of exhibiting the advantages of overcharge safety and high rate discharge characteristics. For example, in power storage facilities and the like that are expected to increase in capacity in the future, high safety is essential, and further compatibility of battery performance is required. In addition, electric vehicles are equipped with high-capacity secondary batteries and are expected to be charged every day at home, and even greater safety is required against overcharging (NEDO Technology Development Organization, Fuel Cell / Hydrogen Technology Development Department, Energy Storage Technology Development Office “NEDO Next-Generation Automotive Storage Battery Technology Development Roadmap 2008” (June 2009)). In addition, when starting and accelerating, it is necessary to discharge at a high rate, and it is important that the high-rate discharge capacity does not deteriorate even after repeated charging and discharging. According to the present invention, it is possible to exhibit the excellent effect correspondingly to such a usage pattern.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited thereto.
(Preparation of electrolyte)
Specific additives and other additives as required were added to the electrolytic solutions shown in Table A in the amounts shown in the table to prepare electrolytic solutions for each test. The water content measured by the Karl Fischer method (JISK0113) was 20 ppm or less.

EC: ethylene carbonate EMC: ethyl methyl carbonate PC: propylene carbonate

Evaluation Method <Production of Battery (1)> In the Case of Negative Electrode LTO The positive electrode is an active material: lithium nickel manganese cobaltate (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ) 85% by mass, conductive auxiliary agent: carbon black 7% by mass, binder: produced by 8% by mass of PVDF, negative electrode is active material: 94% by mass of lithium titanate (Li ₄ Ti ₅ O ₁₂ ), conductive auxiliary agent: 3% by mass of carbon black, binder: 3% by mass of PVDF It was made with. The separator is made of cellulose and has a thickness of 50 μm. Using the positive and negative electrodes and separators described above, 2032 type coin batteries (diameter: 20 mm, height: 3.2 mm, top cover, bottom cover: 250 μm made of SUS, FIG. 3) were prepared for each test electrolyte. Initialized with conditions.

<Initialization of battery (1)>
The battery was charged at a constant current of 0.2 C until the battery voltage became 2.55 V (positive electrode potential 4.1 V) in a thermostat at 30 ° C., and then charged at a constant voltage of 0.12 mA or charged for 2 hours. Next, 0.2 C constant current discharge was performed in a thermostat at 30 ° C. until the battery voltage reached 1.2 V (positive electrode potential 2.75 V). This operation was repeated twice. The following items were evaluated using the 2032 type battery produced by the above method.

(Evaluation of expansion rate of coin cell during overcharge [Expansion rate 1])
Using the coin battery obtained above, constant current charging is performed at 0.2 C, charging is performed until the battery capacity reaches 120% of the charging capacity of the battery voltage of 2.65 V (positive electrode potential 4.2 V). The expansion coefficient was calculated using the following formula. The larger the expansion rate of the coin battery, the better the amount of gas generated during overcharge.
[(Battery thickness after test (mm) −Battery thickness before test (mm))
/ Battery thickness before test (mm)] × 100 (%)
... Formula (A)
5: 10% or more 4: 8% or more and less than 10% 3: 5% or more and less than 8% 2: 2% or more and less than 5% 1: less than 2%

(Evaluation of storage stability of coin battery [Expansion rate 2])
Evaluation was performed by calculating the expansion rate of the coin battery when the coin battery obtained above was left in a constant temperature bath at 80 ° C. for 48 hours by the equation (1).
Less than 5: 1% 4: 1% or more but less than 3% 3: 3% or more but less than 5% 2: 5% or more but less than 10% 1: 10% or more The smaller the expansion rate of the coin battery, the more stable it is for the electrolyte. It represents that it is good.

(Expansion rate evaluation of coin cell after cycle test [Expansion rate 3])
Using the coin battery obtained above, in a constant temperature bath at 40 ° C., constant current charging was performed until the battery voltage reached 2.65 V (positive electrode potential 4.2 V) at 0.2 C, and then the battery voltage 1 at 0.2 C. Evaluation was performed by calculating the expansion rate of the coin battery by the equation (a) when the operation of performing constant current discharge until .2 V (positive electrode potential 2.75 V) was repeated 300 times. The smaller the expansion rate of the coin battery, the more stable it is with respect to charging / discharging within the normal operating range, which is better.
5: Less than 1% 4: 1% or more and less than 3% 3: 3% or more and less than 5% 2: 5% or more and less than 10% 1: 10% or more

Tests starting with C are comparative examples * Formula (a) = number of functional groups (A) / molecular weight of compound × 1000
Expansion coefficient 1: Expansion coefficient evaluation of coin battery during overcharge 2: Expansion coefficient evaluation expansion coefficient during storage at high temperature (80 ° C.) 2: Expansion coefficient evaluation additive / acid generator for coin battery after cycle test: () Is the amount added (% by mass relative to the total amount of the electrolyte)

<Production of Battery (2)> In the case of negative electrode carbon The positive electrode is active material: lithium nickel manganese cobaltate (LiNi1 / 3Mn1 / 3Co1 / 3O2) 85 mass%, conductive auxiliary agent: carbon black 7 mass%, binder: PVDF 8 mass The negative electrode was prepared with active material: 86% by mass of graphite, conductive auxiliary agent: 6% by mass of carbon black, and binder: 8% by mass of PVDF. The separator was replaced with a polypropylene 25 μm thickness. Using the above positive and negative electrodes and separator, each test No. A 2032 type coin battery (diameter: 20 mm, height: 3.2 mm, top lid, bottom lid: 250 μm made of SUS, FIG. 3) was prepared and evaluated for the following items.

<Initialization of battery (1)>
The battery was charged at a constant current of 0.2 C until the battery voltage reached 4.0 V (positive electrode potential 4.1 V) in a thermostat at 30 ° C., and then charged at a constant voltage of 0.12 mA or charged for 2 hours. Next, 0.2 C constant current discharge was performed in a thermostat at 30 ° C. until the battery voltage reached 2.65 V (positive electrode potential 2.75 V). This operation was repeated twice. The following items were evaluated using the 2032 type battery produced by the above method.

(Evaluation of expansion rate of coin cell during overcharge [Expansion rate 1])
Using the coin battery obtained above, constant current charging is performed at 0.2 C, charging is performed until the battery capacity reaches 120% of the charging capacity of the battery voltage 4.1 V (positive electrode potential 4.2 V), and the coin battery The expansion coefficient was calculated using the following formula. The larger the expansion rate of the coin battery, the better the amount of gas generated during overcharge.
[(Battery thickness after test (mm) −Battery thickness before test (mm))
/ Battery thickness before test (mm)] × 100 (%) Formula (A)
5: 10% or more 4: 8% or more and less than 10% 3: 5% or more and less than 8% 2: 2% or more and less than 5% 1: less than 2%

(Evaluation of storage stability of coin battery [Expansion rate 2])
Evaluation was performed by calculating the expansion rate of the coin battery when the coin battery obtained above was left in a constant temperature bath at 80 ° C. for 48 hours by the equation (1).
Less than 5: 1% 4: 1% or more but less than 3% 3: 3% or more but less than 5% 2: 5% or more but less than 10% 1: 10% or more The smaller the expansion rate of the coin battery, the more stable it is for the electrolyte. It represents that it is good.

(Expansion rate evaluation of coin cell after cycle test [Expansion rate 3])
Using the coin battery obtained above, in a constant temperature bath at 40 ° C., after constant current charging at 0.2 C until the battery voltage was 4.1 V (positive electrode potential 4.2 V), the battery voltage was 2 at 0.2 C. Evaluation was performed by calculating the expansion rate of the coin battery by the equation (a) when the operation of performing constant current discharge until .65 V (positive electrode potential 2.75 V) was repeated 300 times. The smaller the expansion rate of the coin battery, the more stable it is with respect to charging / discharging within the normal operating range, which is better.
5: Less than 1% 4: 1% or more and less than 3% 3: 3% or more and less than 5% 2: 5% or more and less than 10% 1: 10% or more

From the above results, according to the electrolyte for a non-aqueous secondary battery according to the present invention, high overcharge prevention (gas generation during overcharge), which is a contradictory characteristic, and suppression of deterioration in performance (during normal charge) It can be seen that a high storage stability of the battery can be realized.

The same experiment as in Test 101 (Additive A-1 (3 parts by mass)) was performed by changing the solvent composition of the electrolytic solution as follows (S1 ′, S1 ″). All were grades of 3-4.

DMC: Dimethyl carbonate DEC: Diethyl carbonate

From the above results, it can be seen that a desired effect can be obtained by blending various primary chain carbonates with the solvent of the electrolytic solution.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.
This application claims priority based on Japanese Patent Application No. 2013-062958 filed in Japan on March 25, 2013, which is hereby incorporated herein by reference. Capture as part.

C positive electrode (positive electrode composite)
1 Positive electrode conductive material (current collector)
2 Positive electrode active material layer A Positive electrode (positive electrode mixture)
3 Negative electrode conductive material (current collector)
4 Negative electrode active material layer 5 Nonaqueous electrolyte 6 Operating means 7 Wiring 9 Separator 10 Lithium ion secondary battery 12 Separator 14 Positive electrode sheet 16 Negative electrode sheet 18 Exterior can 20 also serving as negative electrode Insulating plate 22 Sealing plate 24 Positive electrode current collector 26 Gasket 28 Pressure-sensitive valve body 30 Current interrupting element 100 Bottomed cylindrical lithium secondary battery 50 Current interrupting sealing body 51 Positive electrode cap 52 Convex part 52a Gas vent hole 53 Flange part 54 Bottom plate 55 Concave part 56 Flange part 57 Power outlet plate 57a Concave part 57
57b Flange part 58 PTC thermistor element 59 Insulating gasket 61 for sealing body Negative electrode terminal (upper cover)
62 Negative electrode 63 Separator (including electrolyte)
64 Gasket (sealing material)
65 Positive electrode 66 Positive electrode tube (bottom cover)

Claims (15)

1. An electrolyte solution containing an electrolyte, an organic solvent, and a specific additive having a structure represented by the following functional group A,
   20 to 95% by volume of the organic solvent is composed of a primary chain carbonate compound,
   An electrolyte solution for a non-aqueous secondary battery containing the specific additive in an amount of 0.5 to 10% by mass in the total electrolyte solution.
   

   

   R ¹ to R ³ each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group. At least two of R ¹ to R ³ are the hydrocarbon groups. The hydrocarbon group may have a group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom. * Is a bond.
2. The electrolyte solution for a non-aqueous secondary battery according to claim 1, wherein when R ¹ to R ³ are hydrocarbon groups, the hydrocarbon group is an aromatic group or an alkyl group represented by the following formula Rb.
   * -CR ^b1 R ^b2 R ^b3 ... Rb
   R ^b1 , R ^b2 , and R ^b3 are each independently a hydrogen atom, a hydrocarbon group, or a group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a halogen atom. Provided that when at least one of R ¹ to R ³ is an alkyl group represented by the formula Rb, at least one of R ^b1 , R ^b2 , and R ^b3 is a hydrogen atom, a hydrocarbon group, or oxygen A group containing at least one atom selected from an atom, a nitrogen atom, and a sulfur atom. * Is a bond.
3. The electrolyte solution for a non-aqueous secondary battery according to claim 1 or 2, wherein the number of the functional groups A of the compound constituting the specific additive is two or more.
4. The electrolyte solution for a non-aqueous secondary battery according to any one of claims 1 to 3, wherein the electrolyte solution contains an acid generator having a functional group that generates an acid upon oxidation.
5. The electrolyte solution for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein the number and molecular weight of the functional group A of the specific additive satisfy the relationship of the following formula a.
   Number of functional groups A in the molecule / molecular weight of the compound × 1000 ≧ 5
   ... a
6. The electrolyte solution for a secondary battery according to any one of claims 1 to 5, wherein the functional group A is represented by the following functional group B.
   

   

   [X ¹ is a linking group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. R ¹ ~ ^{R 3} have the same meanings as ^R 1 ~ ^{R 3} in Formula A. ]
7. The electrolyte solution for a non-aqueous secondary battery according to any one of claims 1 to 6, wherein the specific additive is represented by the following formula A1.
   

   

   _{[N a} is an integer of 1-6. R _a represents an organic group when _na is 1, and represents a linking group when _na is 2 or more. R ¹ ~ ^{R 3} have the same meanings as ^R 1 ~ ^{R 3} in Formula A. ]
8. The electrolyte for a non-aqueous secondary battery according to claim 7, wherein the formula A1 is represented by the following formula B1.
   

   

   [ _Nb is an integer of 2 to 6. R _b represents a divalent to hexavalent linking group. X ²¹ is a linking group containing at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. R ¹ ~ ^{R 3} have the same meanings as ^R 1 ~ ^{R 3} in Formula A1. ]
9. The electrolyte solution for a non-aqueous secondary battery according to any one of claims 4 to 8, wherein the acid generator is contained in an amount of 0.1 to 5% by mass in the total electrolyte solution.
10. 10. The electrolyte solution for a non-aqueous secondary battery according to claim 1, wherein the primary linear carbonate compound is diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, or methyl n-propyl carbonate.
11. A non-aqueous electrolyte secondary battery comprising the positive electrode, the negative electrode, and the electrolytic solution according to any one of claims 1 to 10.
12. The nonaqueous electrolyte secondary battery according to claim 11, wherein a compound having at least one of nickel and manganese is used as an active material of the positive electrode.
13. The nonaqueous electrolyte secondary battery according to claim 11 or 12, wherein lithium titanate or a carbon material is used as an active material of the negative electrode.
14. The overcharge prevention device according to any one of claims 11 to 13, wherein the specific additive is a compound that generates a gas during overcharge, and has an overcharge prevention device that cuts off current when a pressure inside the battery exceeds a predetermined pressure. A non-aqueous secondary battery according to item.
15. An electrolyte solution for a non-aqueous secondary battery, comprising a compound that decomposes in a chain during overcharge and generates a gas, an electrolyte, and an organic solvent.
    

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