JP2016173987A - Nonaqueous electrolyte and nonaqueous electrolyte battery arranged by use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a nonaqueous electrolyte which is high in battery's initial efficiency and superior in the capability of suppressing the battery expansion; and a nonaqueous electrolyte battery arranged by use of such a nonaqueous electrolyte.SOLUTION: A nonaqueous electrolyte comprises: at least one aromatic compound expressed by the formula (I). [Rsatisfies the following condition (A) or (B): (A) Ris a hydrocarbon group including at least one halogen-substituted/unsubstituted carbon-carbon unsaturated bond; and (B) Ris a hydrocarbon group which binds to Rand Rto form two ring structures, provided that Rand Rmay directly bind to R.]SELECTED DRAWING: None

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte battery using the same.

  Non-aqueous electrolyte batteries such as lithium secondary batteries are being put to practical use in a wide range of applications from so-called consumer power sources such as mobile phones and notebook computers to in-vehicle power sources for automobiles and the like. However, the demand for higher performance of non-aqueous electrolyte batteries in recent years has been increasing, and in particular, various battery characteristics such as high capacity, low temperature use characteristics, high temperature storage characteristics, cycle characteristics, and overcharge safety. Improvement is demanded.

  The electrolyte used for a non-aqueous electrolyte battery is usually composed mainly of an electrolyte and a non-aqueous solvent. The main components of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone. It is used.

In order to improve battery characteristics such as load characteristics, cycle characteristics, storage characteristics, etc. of these non-aqueous electrolyte batteries, and to improve battery safety during overcharge, various studies have been conducted on non-aqueous solvents, electrolytes, and additives. Has been made.
In Patent Documents 1 to 3, a method of adding various aromatic compounds such as cyclohexylbenzene to the electrolytic solution has been solved, and the problems of improving safety and durability during overcharging have been solved to some extent.

Patent Documents 4 to 7 propose a method of adding tert-butylbenzene, tert-pentylbenzene or the like to the electrolyte solution of the non-aqueous electrolyte secondary battery.
Patent Documents 7 and 8 propose a method of adding 2,2-diphenylpropane or the like to the electrolyte in order to achieve both the cycle characteristics of the nonaqueous electrolyte secondary battery and the safety during overcharge.

JP 2001-15155 A JP 2002-56892 A JP 2003-109660 A Japanese Patent Laid-Open No. 2001-167791 JP 2002-298909 A WO2002 / 59999 JP 2011-154963 A Japanese Patent Laid-Open No. 11-162512

  When the electrolyte containing the aromatic compound described in Patent Documents 1 to 8 is used for a non-aqueous electrolyte secondary battery, safety during overcharge is improved, and durability characteristics such as high-temperature storage and cycle are improved. The However, on the other hand, because of the high reactivity of the compounds, the initial battery characteristics such as initial capacity, efficiency, rate characteristics and initial gas amount, and storage such as capacity, efficiency, rate characteristics and stored gas amount after high temperature storage, etc. Later battery characteristics deteriorated, and the battery was not yet satisfactory.

  In view of the above problems, an object of the present invention is to provide a non-aqueous electrolyte solution having high initial efficiency of a battery and excellent in suppression of battery swelling, and a non-aqueous electrolyte battery using the same.

The present inventors have found that the above problems can be solved by including a compound having a specific structure in the electrolytic solution, and have completed the present invention.
That is, the gist of the present invention is as follows.
(A) A non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte contains at least one aromatic compound represented by the formula (I).

(Where
R ^{1 to} R ⁵ and R ^{9 to} R ¹³ are each independently hydrogen, halogen, or a hydrocarbon group that may be substituted with halogen having 1 to 10 carbon atoms,
R ⁶ and R ⁷ are each independently hydrogen, halogen, or a hydrocarbon group that may be substituted with 1 to 5 carbon atoms halogen,
R ⁸ satisfies the condition (A) or (B).
(A) R ⁸ is a hydrocarbon group having 2 to 15 carbon atoms and having at least one carbon-carbon unsaturated bond, which may be substituted with halogen.
(B) R ⁸ is a hydrocarbon group that combines with R ¹ and R ⁹ to form two ring structures, and the total number of carbon atoms of R ¹ , R ^8, and R ⁹ is 2 or more and 15 or less. R ¹ and R ⁹ may be directly bonded to R ⁸ . )
(B) The non-aqueous electrolyte solution according to (a), wherein R ^{2 to} R ⁵ and R ^{10 to} R ¹³ are hydrogen in the formula (I).
(C) The nonaqueous electrolytic solution according to (a) or (b), wherein, in the formula (I), R ⁶ and R ⁷ are alkyl groups having 1 to 5 carbon atoms.
(D) The non-aqueous electrolyte solution contains the aromatic compound represented by the formula (I) in an amount of 0.1 ppm to 10% by mass, according to any one of (a) to (c). Non-aqueous electrolyte.
(E) The non-aqueous electrolyte solution according to any one of (a) to (d), wherein the non-aqueous electrolyte solution further contains at least one aromatic compound represented by the formula (II).

Where
R ^{17 to} R ²¹ are independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms,
R ²² and R ²³ are each independently a hydrocarbon group having 1 to 12 carbon atoms,
At least two of R ^{17 to} R ²³ may be joined together to form a ring;
However, Formula (II) is (C) and (D):
(C) At least one of R ^{17 to} R ²¹ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
(D) The total number of carbon atoms of R ^{17 to} R ²³ is 3 or more and 20 or less.
Satisfies at least one of the conditions. )
(F) The nonaqueous electrolytic solution according to (e), wherein two of R ¹⁷ , R ²² and R ²³ in the formula (II) are combined to form a ring.
(G) The nonaqueous electrolytic solution according to (e) or (f), wherein the nonaqueous electrolytic solution contains the aromatic compound represented by the formula (II) in an amount of 0.001% by mass to 10% by mass. liquid.
(H) The non-aqueous electrolyte further comprises a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, formula (I) and Aromatic compounds other than formula (II), cyclic carbonate having a carbon-carbon unsaturated bond, fluorine-free carboxylic acid ester, cyclic compound having a plurality of ether bonds, compound having an isocyanuric acid skeleton, monofluorophosphate, The non-aqueous electrolyte solution according to any one of (a) to (g), containing at least one compound selected from the group consisting of difluorophosphate, borate, oxalate and fluorosulfonate .
(R) A nonaqueous electrolyte battery including a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a nonaqueous electrolyte solution, wherein the nonaqueous electrolyte solution is any one of (a) to (h) A non-aqueous electrolyte battery characterized by being a non-aqueous electrolyte solution.

According to the present invention, it is possible to provide a non-aqueous electrolyte battery that has high initial efficiency of the battery and is excellent in suppressing battery swelling, and can achieve downsizing and high performance of the non-aqueous electrolyte battery. .
The reason why the nonaqueous electrolyte battery using the nonaqueous electrolyte solution according to the present invention is excellent in initial characteristics and also excellent in suppressing battery swelling is not clear, but is presumed as follows. However, the present invention is not limited by the following operation principle.

Usually, the aromatic compounds represented by Patent Documents 1 to 8 form a film-like structure when the aromatic ring portion undergoes an oxidation reaction on the positive electrode, thereby improving battery characteristics. However, when the electrolyte solution contains a compound in which a chain saturated hydrocarbon group is bonded to an aromatic ring described in Patent Literatures 1 to 8, a coupling reaction between radicals generated by oxidation of the aromatic ring Is repeated to form a highly conductive coating with a series of aromatic rings on the positive electrode. As a result, the oxidative decomposition of the electrolytic solution is further accelerated, resulting in an increase in storage gas and a decrease in battery capacity. Furthermore, in the compound in which two phenyl groups described in Patent Documents 7 and 8 are bonded via a saturated hydrocarbon group, the oxidation potential shifts to a base due to the electron orbit interaction between the phenyl groups. As a result, the oxidation reaction proceeds intermittently even at a normal operating voltage, and the battery characteristics can be greatly deteriorated.

With respect to such a problem, the present invention has found that the above problem can be solved by incorporating the aromatic compound represented by the formula (I) into the non-aqueous electrolyte solution.
As described below, the aromatic compound represented by the formula (I) has two or more phenyl groups bonded via a hydrocarbon group having at least one carbon-carbon unsaturated bond, or Two or more phenyl groups are bonded via two ring structures.

  In addition to the above radical coupling reaction, this compound can undergo radical polymerization at the unsaturated bond site and ring-opening polymerization reaction at the ring structure. Therefore, since there are a plurality of polymerization patterns, a non-conductive non-conductive film having an intricate and complicated structure is formed, and oxidative decomposition of the electrolytic solution is suppressed. Moreover, since the resulting coating has a complicated structure, the solubility of the coating in the electrolytic solution is greatly reduced. As a result, the presence of a stable protective coating on the positive electrode during durability tests such as high-temperature storage suppresses oxidation side reactions on the positive electrode of the electrolyte component, greatly improving the charge / discharge characteristics of the battery and swelling of the storage. Can be achieved.

  When forming the above-mentioned film, a film having a more complicated structure is formed by having two aromatic rings in one molecule and having an asymmetric structure. However, if the distance between the two aromatic rings is too close, interaction between the aromatic rings occurs, and the oxidation potential shifts to the base. Therefore, an appropriate distance between the aromatic rings is important. Moreover, the probability that the aromatic rings in a molecule | numerator interact can be reduced by suppressing the free rotation of the hydrocarbon group which connects between aromatic rings. Therefore, it is also important to fix the three-dimensional structure by having a carbon-carbon unsaturated bond between the aromatic rings, or to fix the aromatic rings with a ring structure. Furthermore, when the carbon directly bonded to the aromatic ring in the hydrocarbon group connecting the aromatic rings is a quaternary carbon having no hydrogen atom, the degree of rotational freedom of the aromatic ring portion is lowered. As a result, the interaction between aromatic rings in the molecule is difficult to occur, which is important.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments, and can be arbitrarily modified without departing from the gist of the present invention.
1. <Non-aqueous electrolyte>
1-1. Aromatic Compound Represented by Formula (I) The nonaqueous electrolytic solution of the present invention contains an aromatic compound represented by formula (I). In the aromatic compound represented by the formula (I), optical isomers cannot be distinguished, and the isomers can be used alone or as a mixture thereof.

(Where
R ^{1 to} R ⁵ and R ^{9 to} R ¹³ are each independently hydrogen, halogen, or a hydrocarbon group that may be substituted with halogen having 1 to 15 carbon atoms,
R ⁶ and R ⁷ are each independently hydrogen, halogen, or a hydrocarbon group that may be substituted with halogen having 1 to 15 carbon atoms,
R ⁸ satisfies the condition (A) or (B).
(A) R ⁸ is a hydrocarbon group having 2 to 15 carbon atoms and having at least one carbon-carbon unsaturated bond, which may be substituted with halogen.
(B) R ⁸ is a hydrocarbon group that combines with R ¹ and R ⁹ to form two ring structures, and the total number of carbon atoms of R ¹ , R ^8, and R ⁹ is 2 or more and 15 or less. R ¹ and R ⁹ may be directly bonded to R ⁸ . )
As the halogen, fluorine is preferable.

In the formula (I), R ^{1 to} R ⁵ and R ^{9 to} R ¹³ are each independently preferably hydrogen or a hydrocarbon group optionally substituted with 1 to 15 carbon atoms, It is more preferable that ^Further, among R 1 to R ⁵ and ^{R 9 ~R 13, R 2 ~R} 5 and ^R 10 ^{to R 13} is preferably satisfies the condition of. The hydrocarbon group has 1 or more carbon atoms and can have 15 or less carbon atoms, preferably 12 or less, more preferably 5 or less, still more preferably 4 or less, and particularly preferably 2 or less. When in this range, compatibility with the electrolytic solution is more easily ensured.

  Here, the hydrocarbon group represents a group composed of a carbon atom and a hydrogen atom, and corresponds to an aliphatic hydrocarbon group and an aromatic hydrocarbon group. An aliphatic hydrocarbon group is an acyclic or cyclic hydrocarbon group composed of a carbon atom and a hydrogen atom, and represents a group having no aromatic structure. The aromatic hydrocarbon group represents a hydrocarbon group having an aromatic structure composed of carbon atoms and hydrogen atoms.

Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, and an alkynyl group, and an aromatic hydrocarbon group such as an aryl group and an aralkyl group, preferably an aliphatic hydrocarbon group, and more preferably Is an alkyl group. One or more selected from R ^{1 to} R ⁵ and R ^{9 to} R ¹³ and one or more selected from R ^{1 to} R ¹³ are not bonded to each other to form a ring.

Specific examples of the hydrocarbon group in R ^{1 to} R ⁵ and R ^{9 to} R ¹³ include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i -Butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group An alkyl group having 1 to 5 carbon atoms such as vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2- C2-C5 alkenyl groups such as pentenyl, 3-pentenyl, 4-pentenyl; ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butyl An alkynyl group having 2 to 5 carbon atoms such as nyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group; phenyl group, tolyl group, xylyl group, ethylphenyl group Aryl groups such as n-propylphenyl group, i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl group; benzyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, phenethyl group, 2-phenylpropyl group, 2-methyl-2-phenylpropyl group, 3-phenylpropyl group, 3-phenylbutyl group, 3-methyl-3-phenylbutyl group Aralkyl groups having 7 to 12 carbon atoms such as 4-phenylbutyl group, 5-phenylpentyl group and 6-phenylhexyl group are preferred. Good. More preferably, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec- An alkyl group having 1 to 5 carbon atoms such as a pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; and benzyl group, α-methylbenzyl Group, 1-methyl-1-phenylethyl group, phenethyl group, 2-phenylpropyl group, 2-methyl-2-phenylpropyl group, 3-phenylpropyl group, 3-phenylbutyl group, 3-methyl-3-phenyl An aralkyl group having 7 to 12 carbon atoms such as a butyl group, a 4-phenylbutyl group, a 5-phenylpentyl group, and a 6-phenylhexyl group; Or methyl, ethyl, n-propyl, n-butyl, tert-butyl, benzyl, phenethyl, 3-phenylpropyl, 4-phenylbutyl, methyl, tert-butyl. The group is particularly preferred.

In the formula (I), R ⁶ and R ⁷ are each independently preferably hydrogen or a hydrocarbon group optionally substituted with halogen having 1 to 15 carbon atoms, and having 1 to 15 carbon atoms. A hydrocarbon group which may be substituted with a halogen is more preferable, and a hydrocarbon group which is not substituted with a halogen having 1 to 15 carbon atoms is more preferable. The hydrocarbon group has 1 or more carbon atoms and can have 15 or less carbon atoms, preferably 12 or less, more preferably 5 or less, still more preferably 4 or less, and particularly preferably 2 or less. When in this range, compatibility with the electrolytic solution is more easily ensured. Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, and an alkynyl group, and an aromatic hydrocarbon group such as an aryl group and an aralkyl group, preferably an aliphatic hydrocarbon group, and more preferably Is an alkyl group.

Specific examples of the hydrocarbon group in R ⁶ and R ⁷ include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, and tert-butyl group. , N-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, etc. Alkyl group; vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, C2-C5 alkenyl group such as 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group and the like alkynyl group having 2 to 5 carbon atoms; phenyl group, tolyl group, xylyl group, ethylphenyl group, n-propylphenyl group, aryl groups such as i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl group; benzyl group, α-methylbenzyl group, 1-methyl-1-phenyl Ethyl group, phenethyl group, 2-phenylpropyl group, 2-methyl-2-phenylpropyl group, 3-phenylpropyl group, 3-phenylbutyl group, 3-methyl-3-phenylbutyl group, 4-phenylbutyl group, Aralkyl groups having 7 to 12 carbon atoms such as 5-phenylpentyl group and 6-phenylhexyl group are preferred. More preferably, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec- An alkyl group having 1 to 5 carbon atoms such as a pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; and benzyl group, α-methylbenzyl Group, 1-methyl-1-phenylethyl group, phenethyl group, 2-phenylpropyl group, 2-methyl-2-phenylpropyl group, 3-phenylpropyl group, 3-phenylbutyl group, 3-methyl-3-phenyl An aralkyl group having 7 to 12 carbon atoms such as a butyl group, a 4-phenylbutyl group, a 5-phenylpentyl group, and a 6-phenylhexyl group. More preferred are a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Particularly preferred is a methyl group.

In the formula (I), when the condition of (A) is satisfied, the carbon number of R ⁸ is 2 or more, preferably 3 or more, and can be 15 or less, preferably 12 or less, more preferably 5 or less, more preferably 4 or less. When in this range, compatibility with the electrolytic solution is more easily ensured. Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, and an alkynyl group, and an aromatic hydrocarbon group such as an aryl group and an aralkyl group, preferably an aliphatic hydrocarbon group, and more preferably Is an alkenyl group.

The number of carbon atoms in the main chain constituting R ⁸ can be 1 or more, preferably 2 or more, preferably 5 or less, more preferably 4 or less, and 3 or less. More preferably. When it is in this range, the solubility of the film-like compound formed on the positive electrode tends to decrease.
Furthermore, the structural position of the carbon-carbon unsaturated bond is not particularly limited, but it is preferably located between the α-position carbon and the β-position carbon with respect to the phenyl group. This is because the polymerization reaction on the positive electrode tends to proceed remarkably.

Specific examples of R ⁸ include the following structures.

  Of these, the following structure is preferable from the viewpoint of few oxidation side reactions on the positive electrode.

  Further, among these, the following structure is more preferable from the viewpoint of reducing the reduction side reaction on the negative electrode.

  Further, among these, the following structures are particularly preferable.

In the formula (I), when R ⁸ satisfies the condition (B), the total number of carbon atoms of R ¹ , R ⁸ and R ⁹ can be 2 or more, preferably 4 or more, more preferably 5 It can be 15 or less, preferably 12 or less, more preferably 8 or less, and particularly preferably 7 or less. When in this range, compatibility with the electrolytic solution is more easily ensured.
Specific examples of the case where R ⁸ is bonded to R ¹ and R ⁹ to form two ring structures include the following structures.

  Of these, the following structure is preferable from the viewpoint of few oxidation side reactions on the positive electrode.

  Furthermore, among these, the following structures are more preferable.

Examples of the aromatic compound represented by the formula (I) include the following compounds.
≪When R ⁸ satisfies the condition (A) ≫

  Of these, the following compounds are preferred from the viewpoint of reducing the reduction side reaction on the negative electrode and the oxidation side reaction on the positive electrode.

  Further, among these, the following compounds are more preferable from the viewpoint of forming a stable film on the positive electrode.

  Further, among these, the following compounds are particularly preferable from the viewpoint of forming a more stable film on the positive electrode.

≪When R ⁸ satisfies the condition (B) ≫

  Of these, the following compounds are preferred from the viewpoint of reducing the reduction side reaction on the negative electrode and the oxidation side reaction on the positive electrode.

  Further, among these, the following compounds are more preferable from the viewpoint of forming a stable film on the positive electrode.

  Further, among these, the following compounds are particularly preferable from the viewpoint of forming a more stable film on the positive electrode.

In the formula (I), R ⁸ is preferably in the case where the condition of (B) is satisfied from the viewpoint that there are few side reactions at the negative electrode.
The aromatic compound represented by the formula (I) may be used alone or in combination of two or more. In the total amount (100% by mass) of the non-aqueous electrolyte solution, the content of the aromatic compound represented by the formula (I) (the total amount in the case of two or more types) is not particularly limited as long as the ability of the present invention is not impaired. However, it is usually 0.1 mass ppm or more, preferably 0.5 mass ppm or more, more preferably 1 mass ppm or more, still more preferably 2.5 mass ppm or more, and particularly preferably 5 mass ppm or more. Further, it is usually 10% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, still more preferably 0.6% by mass or less, still more preferably 0.2% by mass or less, and particularly preferably 0%. 0.01% by mass or less, and most preferably 0.005% by mass or less. By being in the said range, the effect of this invention is easy to express and the resistance increase of a battery can be prevented.

  In addition, the method of mix | blending the aromatic compound represented by Formula (I) with the electrolyte solution of this invention is not restrict | limited in particular. In addition to the method of directly adding the aromatic compound represented by the formula (I) to the electrolytic solution, a method of generating the aromatic compound represented by the formula (I) in the battery or in the electrolytic solution can be mentioned. Examples of the method for generating the aromatic compound represented by the formula (I) include a method in which a compound other than these compounds is added and a battery component such as an electrolytic solution is generated by oxidation or hydrolysis. Furthermore, a method of generating a battery by applying an electrical load such as charge / discharge is also mentioned.

  In addition, when the aromatic compound represented by the formula (I) is contained in a non-aqueous electrolyte solution and actually used for producing a non-aqueous electrolyte secondary battery, the battery is disassembled and the non-aqueous electrolyte solution is taken out again. In many cases, however, the content thereof is significantly reduced. Therefore, what can be detected even in a very small amount from the non-aqueous electrolyte extracted from the battery is considered to be included in the present invention. In addition, when the aromatic compound represented by the formula (I) is actually used as a non-aqueous electrolyte solution for producing a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte solution disassembled and extracted again Even when only a very small amount of the aromatic compound represented by the formula (I) is contained, it is detected on the positive electrode, the negative electrode, or the separator, which is another component of the non-aqueous electrolyte secondary battery. There are many cases. Therefore, when the aromatic compound represented by the formula (I) is detected from the positive electrode, the negative electrode, and the separator, it can be assumed that the total amount is contained in the nonaqueous electrolytic solution. Under this assumption, the aromatic compound represented by the formula (I) is preferably contained so as to fall within the range described above.

1-2. Aromatic Compound Represented by Formula (II) The nonaqueous electrolytic solution of the present invention further contains an aromatic compound represented by formula (II) in addition to the aromatic compound represented by formula (I). It is preferable. In the aromatic compound represented by the formula (II), optical isomers cannot be distinguished, and the isomers can be used alone or as a mixture thereof.

(Where
R ^{17 to} R ²¹ are independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms,
R ²² and R ²³ are each independently a hydrocarbon group having 1 to 12 carbon atoms,
At least two of R ^{17 to} R ²³ may be combined to form a ring;
However, Formula (II) is (C) and (D):
(C) At least one of R ^{17 to} R ²¹ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
(D) The total number of carbon atoms of R ^{17 to} R ²³ is 3 or more and 20 or less.
Satisfies at least one of the conditions. )
It is an aromatic compound represented by these. When at least two of R ¹⁷ to R ²³ form a ring together, it is preferred that two of R ¹⁷ to R ²³ form a ring together.

R ²² and R ²³ are each independently a hydrocarbon group having 1 to 12 carbon atoms (eg, an alkyl group or an aryl group), and R ²² and R ²³ are combined to form a ring (eg, a hydrocarbon group). A cyclic group) may be formed. From the viewpoint of improving the initial efficiency and solubility and storage characteristics, R ²² and R ²³ are preferably hydrocarbon groups having 1 to 12 carbon atoms, or hydrocarbons formed by combining R ²² and R ²³ together. A cyclic group, more preferably a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, or a hydrocarbon group formed by combining R ²² and R ²³ together 5 An 8-membered cyclic group, more preferably a methyl group, an ethyl group, a cyclohexyl group formed by combining R ²² and R ²³ , a cyclopentyl group,
And most preferably a methyl group, an ethyl group, or a cyclohexyl group formed by combining R ²² and R ²³ .

R ^{17 to} R ²¹ are each independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group, an aryl group, and an aralkyl group). They may be joined together to form a ring (for example, a cyclic group which is a hydrocarbon group). From the viewpoint of improving initial efficiency, solubility and storage characteristics, hydrogen, fluorine, unsubstituted or halogen-substituted hydrocarbon group having 1 to 12 carbon atoms is preferable, and hydrogen, fluorine, unsubstituted or fluorine-substituted is more preferable. A hydrocarbon group having 1 to 10 carbon atoms, more preferably hydrogen, fluorine, tert-butyl group, tert-pentyl group, tert-hexyl group, tert-heptyl group, methyl group, ethyl group, propyl group, Butyl group, trifluoromethyl group, nonafluoro tert-butyl group, 1-methyl-1-phenyl-ethyl group, 1-ethyl-1-phenyl-propyl group, particularly preferably hydrogen, fluorine, tert-butyl group, 1-methyl-1-phenyl-ethyl group, most preferably hydrogen, tert-butyl group, 1-methyl-1- Eniru - an ethyl group.

Any one of R ^{17 to} R ²¹ may be combined with R ²² to form a ring (for example, a cyclic group that is a hydrocarbon group). Preferably, R ¹⁷ and R ²² are combined to form a ring (for example, a cyclic group that is a hydrocarbon group). In this case, R ²³ is preferably an alkyl group. Compounds in which R ²³ is a methyl group and R ¹⁷ and R ²³ together form a ring include 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl-1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane and the like.

Formula (II) is represented by (C) and (D):
(C) At least one of R ^{17 to} R ²¹ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
(D) The total number of carbon atoms of R ^{17 to} R ²³ is 3 or more and 20 or less.
Satisfies at least one of the conditions.

In addition, it is preferable that Formula (II) satisfy | fills (D) from the point of the solubility to electrolyte solution. However, Formula (II) may satisfy both (C) and (D).
As for (C), if at least one of R ^{16 to} R ²¹ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, a ring is formed even if the other is a hydrogen atom You may do it. From the viewpoint of solubility in the electrolytic solution, the carbon number of the unsubstituted or halogen-substituted hydrocarbon group is preferably 1 or more and 10 or less, more preferably 1 or more and 5 or less, still more preferably 1 or more and 3 or less, and still more preferably. 1 or 2, most preferably 1.

Regarding (D), if the total number of carbon atoms of R ^{17 to} R ²³ is 3 or more and 20 or less, at least two of R ^{17 to} R ²³ may be combined to form a ring. When at least two of R ^{17 to} R ²³ are combined to form a ring, in calculating the total number of carbon atoms, carbon that does not correspond to R ^{17 to} R ²³ among the carbons forming the ring (R for ¹⁷ to R ^21, carbon atoms constituting the benzene ring to which they are ^attached, for ^{R 22} and ^{R 23,} carbon atoms in the benzyl position) is set to be not counted. The total number of carbon atoms is preferably 3 or more and 14 or less, more preferably 3 or more and 10 or less, from the viewpoint of solubility in the electrolytic solution. For example, as a compound in which R ²³ is a methyl group and R ¹⁷ and R ²³ together form a ring, 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl Examples include -1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane, which satisfies the condition (D).

  By adding the aromatic compound represented by formula (II), the film formed by the aromatic compound represented by formula (I) can be further complicated. In the aromatic compound represented by the formula (II), the aromatic rings are present via carbon atoms, and since the carbon atom is a quaternary carbon, the aromatic compound represented by the formula (I) is a structure. The above properties are different. Therefore, when the aromatic compound represented by the formula (II) is involved in the film formation reaction of the aromatic compound represented by the formula (I), the polymerization reaction pattern is further increased and the resulting coating is further complicated. As a result, a more remarkable improvement effect can be brought about.

Examples of the aromatic compound represented by the formula (II) include the following.
R ¹⁷ and R ²³ are independently a hydrocarbon group having 1 to 20 carbon atoms (provided that the sum of R ²² and R ²³ is 3 to 20 carbon atoms), and R ^{17 to} R ²¹ are A compound that is hydrogen (fills (C)).
2,2-diphenylbutane, 3,3-diphenylpentane, 3,3-diphenylhexane, 4,4-diphenylheptane, 5,5-diphenyloctane, 6,6-diphenylnonane, 1,1-diphenyl-1, 1-ditert-butyl-methane.

A compound in which R ²² and R ²³ are combined to form a ring, and R ^{1 to} R ⁵ are hydrogen (satisfy (C)).
1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1-diphenyl-4-methylcyclohexane.
The following compounds may be used (they may be overlapped with the above-exemplified compounds, but will be represented by a structural formula)

A compound in which at least one of R ^{17 to} R ²¹ is halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (which satisfies (C)).
1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene.
The following compounds may be used (they may be overlapped with the above-exemplified compounds, but will be represented by a structural formula)

R ²³ is a hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group having 1 to 20 carbon atoms, preferably a methyl group), and R ¹⁷ and R ²² together form a ring. Compound (which satisfies (D)).
1-phenyl-1,3,3-trimethylindane.
The following compounds may be used (they may be overlapped with the above-exemplified compounds, but will be represented by a structural formula)

Among these, from the viewpoint of reducing properties on the initial negative electrode,
2,2-diphenylbutane, 3,3-diphenylpentane, 1,1-diphenyl-1,1-ditert-butyl-methane, 1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1- Diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene, 1-phenyl-1,3 , 3-trimethylindane.
The following compounds can also be mentioned as preferable ones (they may be overlapped with the above-mentioned preferable compounds, but will be represented by the structural formula).

More preferred is
2,2-diphenylbutane, 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1 -Methyl-1-phenylethyl) -benzene, 1-phenyl-1,3,3-trimethylindane.

  The following compounds are also mentioned as more preferable ones (they may be overlapped with the more preferable compounds described above, but will be represented by the structural formula).

More preferred are 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl- 1-phenylethyl) -benzene, 1-phenyl-1,3,3-trimethylindane.
The following compounds are also mentioned as more preferable ones (they may be overlapped with the above-mentioned more preferable compounds, but will be shown by the structural formula).

  Particularly preferred are 1,1-diphenylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene, 1-phenyl. -1,3,3-trimethylindane, which is represented by the following structural formula.

  Most preferred is a 1-phenyl-1,3,3-trimethylindane compound, which is represented by the following structural formula.

  The aromatic compound represented by the formula (II) may be used alone or in combination of two or more. In the total amount (100% by mass) of the non-aqueous electrolyte solution, the amount of the aromatic compound represented by the formula (II) (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably Is 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less, more Preferably it is 5 mass% or less, More preferably, it is 3 mass% or less, Most preferably, it is 2.5 mass% or less.

By being in the said range, the effect of this invention is easy to express and the resistance increase of a battery can be prevented.
The mass ratio of the aromatic compound represented by the formula (I) and the aromatic compound represented by the formula (II) can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100, more preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100 to 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3. Fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphorus-containing organic compound, organic compound having cyano group, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (I) and formula (II), carbon- A cyclic carbonate having a carbon unsaturated bond, a fluorine-free carboxylic acid ester, a cyclic compound having a plurality of ether bonds, and a compound having an isocyanuric acid skeleton An embodiment of the present invention is an aromatic carboxylic acid represented by the above formula (I) Ester, fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphorus-containing organic compound, organic compound having cyano group, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (I) and formula (II) , Cyclic carbonate having a carbon-carbon unsaturated bond, fluorine It can contain at least one compound selected from the group consisting of non-containing carboxylic acid esters, cyclic compounds having a plurality of ether bonds, and compounds having an isocyanuric acid skeleton.

Among them, a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group, an aromatic compound other than the formula (I) and the formula (II), a cyclic carbonate having a carbon-carbon unsaturated bond, At least one compound selected from the group consisting of a fluorine-free carboxylic acid ester and a cyclic compound having a plurality of ether bonds forms a good composite film on the negative electrode, and the battery after initial battery characteristics and durability test Fluorine-containing cyclic carbonate, organic compound having cyano group, aromatic compound other than formula (I) and formula (II), cyclic carbonate having carbon-carbon unsaturated bond, and carboxylic acid ester More preferably, at least one compound selected from the group consisting of: a fluorine-containing cyclic car At least one compound selected from the group consisting of nates, cyclic carbonates having carbon-carbon unsaturated bonds, and carboxylic acid esters is more preferred, and at least selected from fluorine-containing cyclic carbonates or cyclic carbonates having carbon-carbon unsaturated bonds. One compound is particularly preferred. The reason for this is that these compounds that form a relatively low molecular weight film on the negative electrode have a dense negative electrode film, so that the aromatic compound represented by the formula (I) is efficiently deteriorated due to a side reaction. Can be suppressed. In this way, side reactions can be effectively suppressed, resistance increase can be suppressed, volume changes can be suppressed by suppressing side reactions during initial and high temperature durability, safety after high temperature durability can be ensured, and rate characteristics can be improved. The method for blending the above compound with the electrolytic solution of the present invention is not particularly limited. In addition to the method of adding the above compound directly to the electrolytic solution, a method of generating the above compound in the battery or in the electrolytic solution can be mentioned. Examples of a method for generating the compound include a method in which a compound other than these compounds is added to generate a battery component such as an electrolytic solution by oxidation or hydrolysis. Furthermore, a method of generating a battery by applying an electrical load such as charge / discharge is also mentioned.

  In addition, when the above compound is contained in a non-aqueous electrolyte solution and actually used for the production of a non-aqueous electrolyte secondary battery, even if the battery is disassembled and the non-aqueous electrolyte solution is taken out again, the content thereof is In many cases, it is significantly reduced. Therefore, what can be detected even in a very small amount from the non-aqueous electrolyte extracted from the battery is considered to be included in the present invention. In addition, when the above compound is actually used as a non-aqueous electrolyte for the preparation of a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte obtained by disassembling and re-extracting the battery contains a very small amount of the compound. Even if it is not, it is often detected on the positive electrode, the negative electrode, or the separator, which is another component of the non-aqueous electrolyte secondary battery. Therefore, when the above compounds are detected from the positive electrode, the negative electrode, and the separator, it can be assumed that the total amount is contained in the non-aqueous electrolyte. Under this assumption, it is preferable that the specific compound is included in a range described later.

Below, the aspect in which the electrolyte solution of this invention contains the said compound is demonstrated. Regarding the aromatic compound represented by the formula (I) to be combined with the above compound, the above description regarding the aromatic compound represented by the formula (I) is applied including examples and preferred examples. Moreover, in the aspect containing a certain compound, the compound other than that in the said compound may be contained.
1-3-1. Fluorine-containing cyclic carbonate The electrolytic solution of the present invention can further contain a fluorine-containing cyclic carbonate. The fluorine-containing cyclic carbonate is not particularly limited as long as it is a cyclic carbonate having a fluorine atom. In the electrolytic solution of the present invention, the aromatic compound represented by the above formula (I) and the fluorine-containing cyclic carbonate interact with each other to form a composite interface protective film on the negative electrode. It is considered that the high temperature storage characteristics can be improved. At the same time, excellent initial rate characteristics can be imparted to the battery.

  Examples of the fluorine-containing cyclic carbonate include a fluorinated product of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. For example, a fluorinated product of ethylene carbonate (hereinafter referred to as “fluorinated ethylene carbonate”) And derivatives thereof. Examples of the fluorinated derivative of ethylene carbonate include fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Of these, fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferred.

Examples of the fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4, 5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene Carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethyl Le ethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

Among these, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferable because they give high ionic conductivity to the electrolyte and easily form a stable interface protective film.
A fluorinated cyclic carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. The amount of the fluorinated cyclic carbonate (total amount in the case of two or more types) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% in 100% by mass of the electrolytic solution. % By mass or more, still more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, most preferably 1.2% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass. Or less, more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably 2% by mass or less. In addition, when fluorinated cyclic carbonate is used as the non-aqueous solvent, the amount is 100% by volume in the non-aqueous solvent, preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more. Moreover, it is preferably 50% by volume or less, more preferably 35% by volume or less, and still more preferably 25% by volume or less.

  Further, as the fluorine-containing cyclic carbonate, a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter sometimes referred to as “fluorinated unsaturated cyclic carbonate”) may be used. If the fluorine number which a fluorinated unsaturated cyclic carbonate has is one or more, it will not restrict | limit in particular. The number of fluorines can be 6 or less, preferably 4 or less, and more preferably 1 or 2.

Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives, fluorinated ethylene carbonate derivatives substituted with an aromatic ring or a substituent having a carbon-carbon double bond.
Fluorinated vinylene carbonate derivatives include 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-5- And vinyl vinylene carbonate.

  Examples of the fluorinated ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5. -Vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate 4,5-diflu B-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4- Examples thereof include phenylethylene carbonate.

Among them, as the fluorinated unsaturated cyclic carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro -4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4 , 4-Difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4 Fluoro-4,5-diallyl carbonate, 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl carbonate is preferred because it forms a stable interface protective coating.

  The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited. The molecular weight is preferably 50 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the fluorinated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the fluorinated unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

A fluorinated unsaturated cyclic carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of the fluorinated unsaturated cyclic carbonate (the total amount in the case of two or more) is 100% by mass of the electrolyte solution, preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0. 0.1% by mass or more, particularly preferably 0.2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less, and particularly preferably 3% by mass. It is as follows. Within this range, the non-aqueous electrolyte battery tends to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics deteriorate, the amount of gas generated increases, and the discharge capacity maintenance ratio decreases. Easy to avoid.

The mass ratio of the aromatic compound represented by the above formula (I) and the fluorine-containing cyclic carbonate is 0.
. 0001: 100-1000000: 100, preferably 0.0005: 100-100: 100, more preferably 0.001: 100-10: 100, still more preferably 0.002: 100-1: 100. Particularly preferably, it is 0.003: 100 to 0.5: 100, and most preferably 0.005: 100 to 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-2. Sulfur-containing organic compound The electrolytic solution of the present invention can further contain a sulfur-containing organic compound. The sulfur-containing organic compound is not particularly limited as long as it is an organic compound having at least one sulfur atom in the molecule, but is preferably an organic compound having an S═O group in the molecule. Sulfonated esters, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites and cyclic sulfites. However, those corresponding to fluorosulfonate are 1-3-2. It is not included in a sulfur-containing organic compound, but is included in a fluorosulfonate that is an electrolyte described later.

In the electrolytic solution of the present invention, by using the aromatic compound represented by the formula (I) and the sulfur-containing organic compound in combination, the battery using this electrolytic solution can improve the initial efficiency, Battery characteristics can be further improved by reducing the storage gas.
Among these, a chain sulfonate ester, a cyclic sulfonate ester, a chain sulfate ester, a cyclic sulfate ester, a chain sulfite ester and a cyclic sulfite ester are preferable, and a compound having an S (═O) ₂ group is more preferable.

These esters may have a substituent. Here, the substituent is a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, preferably a carbon atom. , A group composed of one or more atoms selected from the group consisting of a hydrogen atom, an oxygen atom and a halogen atom, more preferably one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom and an oxygen atom It is a structured group. Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups or alkoxy groups; cyano groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; carboxy groups; An acyloxy group; an alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group. Of these, preferably a halogen atom; an alkoxy group; an unsubstituted or halogen-substituted alkyl group, alkenyl group or alkynyl group; an isocyanato group; a cyano group; an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group; More preferably a halogen atom, an unsubstituted alkyl group, or an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group or an acyloxy group, and more preferably a halogen atom, an unsubstituted alkyl group, or an alkoxycarbonyl group. The illustrations and preferred examples relating to these substituents apply to the substituents in the definition of A ¹² and A ¹³ in formula (2-1) and A ¹⁴ in formula (2-2) described later.

More preferred are chain sulfonic acid esters and cyclic sulfonic acid esters, among which chain sulfonic acid esters represented by formula (2-1) and cyclic sulfonic acid esters represented by formula (2-2) are preferred. The cyclic sulfonate ester represented by the formula (2-2) is more preferable.
1-3-2-1. Chain sulfonate ester represented by formula (2-1)

(Where
A ¹² is an n ²¹ valent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent,
A ¹³ is a hydrocarbon group having 1 to 12 carbon atoms that may have a substituent,
n ²¹ is an integer of 1 to 4,
When n ²¹ is 2, A ¹² and A ¹³ may be the same or different. )
In Formula (2-1), A ¹² and A ¹³ do not form a ring together, and thus Formula (2-1) is a chain sulfonate.

n ²¹ is preferably from 1 to 3 of an integer, more preferably 1 to 2 integer 2 is more preferable.
As the n ²¹ valent hydrocarbon group having 1 to ¹² carbon atoms in A ¹² ,
Monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, alkynyl groups and aryl groups;
A divalent hydrocarbon group such as an alkylene group, an alkenylene group, an alkynylene group and an arylene group;
Trivalent hydrocarbon groups such as alkanetriyl groups, alkenetriyl groups, alkynetriyl groups and arenetriyl groups;
Tetravalent hydrocarbon groups such as alkanetetrayl group, alkenetetrayl group, alkynetetrayl group and arenetetrayl group;
Etc.

Of these, divalent hydrocarbon groups such as an alkylene group, alkenylene group, alkynylene group, and arylene group are preferable, and an alkylene group is more preferable. These correspond to the case where n ²¹ is 2.
Among the n ²¹ valent hydrocarbon groups having 1 to 12 carbon atoms, the monovalent hydrocarbon groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl. Group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2- A C1-C5 alkyl group such as dimethylpropyl group; vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group An alkenyl group having 2 to 5 carbon atoms such as 2-pentenyl group, 3-pentenyl group, 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl And an alkynyl group having 2 to 5 carbon atoms such as a group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group and the like.

  Examples of the divalent hydrocarbon group include an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group; a vinylene group, a 1-propenylene group, a 2-propenylene group, Alkenylene groups having 2 to 5 carbon atoms such as 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group; ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene And alkynylene groups having 2 to 5 carbon atoms such as 2-pentynylene group, preferably alkylene groups having 1 to 5 carbon atoms such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group. More preferably, carbon such as ethylene group, trimethylene group, tetramethylene group, pentamethylene group, etc. A number 2 to 5 of the alkylene group, more preferably a trimethylene group, a tetramethylene group, an alkylene group having 3 to 5 carbon atoms, such as pentamethylene group.

Examples of the trivalent and tetravalent hydrocarbon groups include trivalent and tetravalent hydrocarbon groups corresponding to the monovalent hydrocarbon group.
The n ²¹ valent hydrocarbon group having 1 to 12 carbon atoms and having a substituent in A ¹² is a combination of the above substituent and the n ²¹ valent hydrocarbon group having 1 to 12 carbon atoms. Means group. A ¹² is preferably an n ²¹ valent hydrocarbon group having 1 to 5 carbon atoms and having no substituent.

The hydrocarbon group having 1 to 12 carbon atoms in A ¹³ is preferably a monovalent hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group and an aryl group, and more preferably an alkyl group.
Examples of the hydrocarbon group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n -C1-C5 alkyl groups such as pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group Preferably methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, more preferably methyl group, ethyl group, n-propyl group, still more preferably ethyl. Group, n-propyl group.

The hydrocarbon group having 1 to 12 carbon atoms and having a substituent in A ¹³ means a group in which the above substituent and the hydrocarbon group having 1 to 12 carbon atoms are combined. A ¹³ is preferably a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent, more preferably a hydrocarbon group having 1 to 5 carbon atoms having a substituent, More preferred is an alkyl group having an alkoxycarbonyl group as a substituent. Among them, methoxycarbonylmethyl group, ethoxycarbonylmethyl group, 1-methoxycarbonylethyl group, 1-ethoxycarbonylethyl group, 2-methoxycarbonylethyl group, 2-ethoxycarbonylethyl group, 1-methoxycarbonylpropyl group, 1-ethoxy A carbonylpropyl group, a 2-methoxycarbonylpropyl group, a 2-ethoxycarbonylpropyl group, a 3-methoxycarbonylpropyl group, and a 3-ethoxycarbonylpropyl group are preferable, and a 1-methoxycarbonylethyl group and a 1-ethoxycarbonylethyl group are more preferable. It is.

  The battery using the electrolytic solution of the present invention further including the chain sulfonate represented by the formula (2-1) is excellent in the initial gas suppression effect and the storage gas suppression effect. The content of the chain sulfonic acid ester represented by the formula (2-1) (the total content in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the electrolytic solution. , Preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.5% by mass or more, and 10% by mass or less. Preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Most preferably, it is 1.5 mass% or less. Within this range, the high temperature storage characteristics are good.

  1-3-2-2. Cyclic sulfonic acid ester represented by formula (2-2)

(Where
A ¹⁴ is a divalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent. )
Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms in A ¹⁴ include an alkylene group, an alkenylene group, an alkynylene group, and an arylene group, preferably an alkylene group and an alkenylene group.

Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms include alkylene groups having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group; a vinylene group and a 1-propenylene group. , 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group and the like, alkenylene group having 2 to 5 carbon atoms;
Examples thereof include alkynylene groups having 2 to 5 carbon atoms such as ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group.

Among these, preferably an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group, a vinylene group, a 1-propenylene group, a 2-propenylene group, and a 1-butenylene group. C 2-5 alkenylene groups such as 2-butenylene group, 1-pentenylene group and 2-pentenylene group, more preferably alkylene having 3 to 5 carbon atoms such as trimethylene group, tetramethylene group and pentamethylene group. Group and 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group, etc., and alkenylene groups having 3 to 5 carbon atoms, more preferably trimethylene group, 1-propenylene group and 2-propenylene group.

The divalent hydrocarbon group having 1 to 12 carbon atoms and having a substituent in A ¹⁴ is a group in which the above substituent and the divalent hydrocarbon group having 1 to 12 carbon atoms are combined. Means that. A ¹⁴ is preferably a divalent hydrocarbon group having 1 to 5 carbon atoms and having no substituent.
A battery using the electrolytic solution of the present invention further containing a cyclic sulfonic acid ester represented by the formula (2-2) has a low initial capacity loss and a good capacity recovery rate after high-temperature storage. Furthermore, safety during overcharge can be further improved. The content of the cyclic sulfonic acid ester represented by the formula (2-2) (the total content in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the electrolytic solution, Preferably it is 0.01 mass% or more, More preferably, it is 0.1 mass% or more, More preferably, it is 0.3 mass% or more, Most preferably, it is 0.5 mass% or more, and it is 10 mass% or less. Preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Most preferably, it is 1.5 mass% or less.

Examples of the sulfur-containing organic compound include the following.
≪Chain sulfonate ester≫
Fluorosulfonic acid esters such as methyl fluorosulfonate and ethyl fluorosulfonate;
Methyl methanesulfonate, ethyl methanesulfonate, 2-propynyl methanesulfonate, 3-butynyl methanesulfonate, busulfan, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2- (Methanesulfonyloxy) propionate 2-propynyl, 2- (methanesulfonyloxy) propionate 3-butynyl, methanesulfonyloxyacetate methyl, methanesulfonyloxyacetate ethyl, methanesulfonyloxyacetate 2-propynyl and methanesulfonyloxyacetate 3- Methanesulfonic acid esters such as butynyl;
Methyl vinyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl sulfonate, propargyl allyl sulfonate and 1,2-bis (vinyl sulfonyloxy) ) Alkenyl sulfonic acid esters such as ethane;
Methanedisulfonic acid methoxycarbonylmethyl, methanedisulfonic acid ethoxycarbonylmethyl, methanedisulfonic acid 1-methoxycarbonylethyl, methanedisulfonic acid 1-ethoxycarbonylethyl, 1,2-ethanedisulfonic acid methoxycarbonylmethyl, 1,2-ethanedisulfonic acid Ethoxycarbonylmethyl, 1-methoxycarbonylethyl 1,2-ethanedisulfonate, 1-ethoxycarbonylethyl 1,2-ethanedisulfonate, methoxycarbonylmethyl 1,3-propanedisulfonate, ethoxycarbonyl 1,3-propanedisulfonate Methyl, 1,3-propanedisulfonic acid 1-methoxycarbonylethyl, 1,3-propanedisulfonic acid 1-ethoxycarbonylethyl, 1,3-butanedisulfonic acid methoxycarbonyl Methyl, 1,3-butane disulfonic acid ethoxycarbonylmethyl, 1,3-butane disulfonic acid 1-methoxycarbonyl-ethyl, alkyl disulfonic acid esters, such as 1,3-butane disulfonic acid 1-ethoxycarbonylethyl;
≪Cyclic sulfonate ester≫
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene -1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2
-Propene-1,3-sultone, 2-fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone 2-methyl-1-propene-1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene Sultone compounds such as -1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1,4-butane sultone and 1,5-pentane sultone;
Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;
1,2,3-oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazol-2,2-dioxide 5H-1,2,3-oxathiazol-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide, 1, 2,3-oxathiazinane-2,2-dioxide, 3-methyl-1,2,3-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine-2,2-dioxide and Nitrogen-containing compounds such as 1,2,4-oxathiazinane-2,2-dioxide.

  1,2,3-oxathiaphoslane-2,2-dioxide, 3-methyl-1,2,3-oxathiaphoslane-2,2-dioxide, 3-methyl-1,2,3-oxathi Aphoslane-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphoslane-2,2,3-trioxide, 1,2,4-oxathiaphoslane-2,2-dioxide 1,2,5-oxathiaphoslane-2,2-dioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan- 2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosphinan-2,2,3- Trioxide, 1,2,4-oxathiaphosphie Down-dioxide, 1,2,5-oxathiazolium phosphinothricin Nan-2,2-dioxide and 1,2,6-oxa-thia phosphinothricin Nan -2,2-containing phosphorus compounds such as dioxide.

≪Chain sulfate ester≫
Dialkyl sulfate compounds such as dimethyl sulfate, ethyl methyl sulfate and diethyl sulfate.
≪Cyclic sulfate ester≫
1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, 1,3-butylene sulfate, 1,4-butylene sulfate, 1, Alkylene sulfate compounds such as 2-pentylene sulfate, 1,3-pentylene sulfate, 1,4-pentylene sulfate, and 1,5-pentylene sulfate.

≪Chainous sulfite ester≫
Dialkyl sulfite compounds such as dimethyl sulfite, ethyl methyl sulfite and diethyl sulfite.
≪Cyclic sulfite ester≫
1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, 1,2-butylene sulfite, 1,3-butylene sulfite, 1,4-butylene sulfite, 1, Alkylene sulfite compounds such as 2-pentylenesulfite, 1,3-pentylenesulfite, 1,4-pentylenesulfite and 1,5-pentylenesulfite.

Of these, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl 2- (methanesulfonyloxy) propionate, 1-methoxycarbonylethyl propanedisulfonate, propanedisulfone 1-ethoxycarbonylethyl acid, 1-methoxycarbonylethyl butanedisulfonate, 1-ethoxycarbonylethyl butanedisulfonate, 1,3-propane sultone, 1-propene-1,3-sultone, 1,4-butane sultone, 1, 2-Ethylene sulfate, 1,2-ethylene sulfite, methyl methanesulfonate, and ethyl methanesulfonate are preferable from the viewpoint of improving storage characteristics. 1-methoxycarbonylethyl propanedisulfonate, 1-ethanepropanedisulfonate Xicarbonylethyl, 1-methoxycarbonylethyl butanedisulfonate, 1-ethoxycarbonylethyl butanedisulfonate, 1,3-propane sultone, 1-propene-1,3-sultone, 1,2-ethylene sulfate, 1,2 -Ethylene sulfite is more preferable, and 1,3-propane sultone and 1-propene-1,3-sultone are more preferable.

A sulfur containing organic compound may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios.
The content of the sulfur-containing organic compound (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably in 100% by mass of the electrolytic solution. 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably Is 3% by mass or less, more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic compound represented by the above formula (I) and the sulfur-containing organic compound can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100. Preferably 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100 to 0. .1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-3. Phosphorus-containing organic compound The electrolytic solution of the present invention can further contain a phosphorus-containing organic compound. The phosphorus-containing organic compound is not particularly limited as long as it is an organic compound having at least one phosphorus atom in the molecule. A battery using the electrolytic solution of the present invention containing a phosphorus-containing organic compound has suppressed gas generation after high-temperature storage, has a good recovery rate, and has good initial charge / discharge efficiency.

As a phosphorus containing organic compound, phosphoric acid ester, phosphonic acid ester, phosphinic acid ester, and phosphorous acid ester are preferable, More preferably, they are phosphoric acid ester and phosphonic acid ester, More preferably, they are phosphonic acid ester. These esters may have a substituent. Here, the substituent is a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, preferably a carbon atom. , A group composed of one or more atoms selected from the group consisting of a hydrogen atom, an oxygen atom and a halogen atom. Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups or alkoxy groups; cyano groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; carboxy groups; An acyloxy group; an alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group. Of these, preferred are a halogen atom; an alkoxy group; an alkoxycarbonyloxy group; an acyl group; a carboxyl group and an acyloxy group, more preferably a halogen atom and an acyloxy group, and still more preferably an acyloxy group. Examples of the acyloxy group include an acetoxy group, a propionyloxy group, a butyryloxy group, an acryloyloxy group, a methacryloyloxy group, and a crotonyloxy group, and an acryloyloxy group is preferable. The illustrations and preferred examples relating to these substituents are applied to the substituents in the definition of A ^{6 to} A ⁸ in the formula (3-1) described later.

More preferred are phosphoric acid esters and phosphonic acid esters, among which phosphoric acid esters represented by the formula (3-1) and phosphonic acid esters represented by the formula (3-2) are preferable.
1-3-3-1. Phosphate ester represented by formula (3-1)

(Where
A ⁶ , A ⁷ and A ⁸ are each independently an alkyl group, an alkenyl group or an alkynyl group having 1 to 5 carbon atoms which may have a substituent, provided that A ^{6 to} A ⁸ At least one of them has a carbon-carbon unsaturated bond. )
Examples of the alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert- Alkyl groups such as butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; vinyl Group, 1-propenyl group, 2-propenyl group (allyl group), isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, Alkenyl groups such as 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group (propargyl group), 1-butynyl group, 2-butynyl Alkynyl groups such as 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group, methyl group, ethyl group, n-propyl group, n-butyl group, n -Pentyl group, vinyl group, 2-propenyl group (allyl group), 3-butenyl group, 4-pentenyl group, 2-propynyl group (propargyl group), 3-butynyl group and 4-pentynyl group are preferred, methyl group, An ethyl group, a 2-propenyl group (allyl group) and a 2-propynyl group (propargyl group) are more preferable, and a methyl group, an ethyl group and a 2-propenyl group (allyl group) are still more preferable.

In addition, the C1-C5 alkyl group, alkenyl group, or alkynyl group which has a substituent is the group which combined the said substituent and the said C1-C5 alkyl group, alkenyl group, or alkynyl group. And preferably a 2-acryloyloxymethyl group and a 2-acryloyloxyethyl group.
Examples of the compound represented by the formula (3-1) include the following.

<Compound having one carbon-carbon unsaturated bond>
Compounds having a vinyl group, such as dimethyl vinyl phosphate, diethyl vinyl phosphate, dipropyl vinyl phosphate, dibutyl vinyl phosphate and dipentyl vinyl phosphate;
Compounds having an allyl group such as allyl dimethyl phosphate, allyl diethyl phosphate, allyl dipropyl phosphate, allyl dibutyl phosphate and allyl dipentyl phosphate;
Compounds having a propargyl group such as propargyl dimethyl phosphate, propargyl diethyl phosphate, propargyl dipropyl phosphate, propargyl dibutyl phosphate and propargyl dipentyl phosphate;
2-acryloyloxymethyl dimethyl phosphate, 2-acryloyloxymethyl diethyl phosphate, 2-acryloyloxymethyl dipropyl phosphate, 2-acryloyloxymethyl dibutyl phosphate and 2-acryloyloxymethyl dipentyl phosphate Compound;
It has 2-acryloyloxyethyl groups such as 2-acryloyloxyethyl dimethyl phosphate, 2-acryloyloxyethyl diethyl phosphate, 2-acryloyloxyethyl dipropyl phosphate, 2-acryloyloxyethyl dibutyl phosphate and 2-acryloyloxyethyl dipentyl phosphate. Compound;
<Compound having two carbon-carbon unsaturated bonds>
Compounds having a vinyl group such as methyl divinyl phosphate, ethyl divinyl phosphate, propyl divinyl phosphate, butyl divinyl phosphate and pentyl divinyl phosphate;
Compounds having an allyl group, such as diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl butyl phosphate and diallyl pentyl phosphate;
Compounds having a propargyl group, such as dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, dipropargyl butyl phosphate and dipropargyl pentyl phosphate;
Bis (2-acryloyloxymethyl) methyl phosphate, bis (2-acryloyloxymethyl) ethyl phosphate, bis (2-acryloyloxymethyl) propyl phosphate, bis (2-acryloyloxymethyl) butyl phosphate and bis (2-acryloyloxy) Compounds having a 2-acryloyloxymethyl group such as methyl) pentyl phosphate;
Bis (2-acryloyloxyethyl) methyl phosphate, bis (2-acryloyloxyethyl) ethyl phosphate, bis (2-acryloyloxyethyl) propyl phosphate, bis (2-acryloyloxyethyl) butyl phosphate and bis (2-acryloyloxy) Compounds having a 2-acryloyloxyethyl group such as ethyl) pentyl phosphate;
<Compound having three carbon-carbon unsaturated bonds>
Trivinyl phosphate, triallyl phosphate, tripropargyl phosphate, tris (2-acryloyloxymethyl) phosphate, tris (2-acryloyloxyethyl) phosphate, etc. Among these, 3 carbon-carbon unsaturated bonds are formed from the viewpoint of improving battery characteristics. The compound which has one is preferable, and a triallyl phosphate and a tris (2-acryloyloxyethyl) phosphate are more preferable.

  1-3-3-2. Phosphonate represented by formula (3-2)

(Where
A ⁹ , A ¹⁰ and A ¹¹ are each independently an unsubstituted or halogen-substituted alkyl group having 1 to 5 carbon atoms, an alkenyl group or an alkynyl group,
n ³² is an integer of 0 to 6. )
Examples of the alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert- Alkyl groups such as butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; vinyl Group, 1-propenyl group, 2-propenyl group (allyl group), isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, Alkenyl groups such as 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group (propargyl group), 1-butynyl group, 2-butynyl Alkynyl groups such as 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group, methyl group, ethyl group, n-propyl group, n-butyl group, n -Pentyl group, vinyl group, 2-propenyl group (allyl group), 3-butenyl group, 4-pentenyl group, 2-propynyl group (propargyl group), 3-butynyl group and 4-pentynyl group are preferred, methyl group, An ethyl group, a 2-propenyl group (allyl group) and a 2-propynyl group (propargyl group) are more preferable, and a methyl group, an ethyl group and a 2-propynyl group (propargyl group) are still more preferable.

Examples of the phosphonic acid ester represented by the formula (3-2) include the following compounds.
<Compound with n ³² = 0 in Formula (3-2)>
Trimethyl phosphonoformate, methyl diethylphosphonoformate, methyl dipropylphosphonoformate, methyl dibutylphosphonoformate, triethyl phosphonoformate, ethyl dimethylphosphonoformate, ethyl dipropylphosphonoformate, ethyl Dibutyl phosphonoformate, tripropyl phosphonoformate, propyl dimethylphosphonoformate, propyl diethylphosphonoformate, propyl dibutylphosphonoformate, tributyl phosphonoformate, butyl dimethylphosphonoformate, butyl diethylphospho Noformate, butyl dipropylphosphonoformate, methyl bis (2,2,2-trifluoroethyl) phosphonoformate, ethyl bis (2 2,2-trifluoroethyl) phosphonoacetate formate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate and the like.

<Compound with n ³² = 1 in Formula (3-2)>
Trimethyl phosphonoacetate, methyl diethyl phosphonoacetate, methyl dipropyl phosphonoacetate, methyl dibutyl phosphonoacetate, triethyl phosphonoacetate, ethyl dimethylphosphonoacetate, ethyl dipropylphosphonoacetate, ethyl dibutylphosphonoacetate, tripropyl Phosphonoacetate, propyl dimethylphosphonoacetate, propyl diethylphosphonoacetate, propyl dibutylphosphonoacetate, tributyl phosphonoacetate, butyldimethylphosphonoacetate, butyldiethylphosphonoacetate, butyldipropylphosphonoacetate, methylbis (2 , 2,2-trifluoroethyl) phosphonoacetate, ethyl bis (2,2,2-trifluoroethyl) phos No acetate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate, allyl dimethylphosphonoacetate, allyl diethylphosphonoacetate, 2 -Propynyl dimethylphosphonoacetate, 2-propynyl diethylphosphonoacetate, etc.

<Compound with n ³² = 2 in Formula (3-2)>
Trimethyl 3-phosphonopropionate, methyl 3- (diethylphosphono) propionate, methyl 3- (dipropylphosphono) propionate, methyl 3- (dibutylphosphono) propionate, triethyl 3-phosphonopropionate, ethyl 3- (dimethylphosphono) propionate, ethyl 3- (dipropylphosphono) propionate, ethyl 3- (dibutylphosphono) propionate, tripropyl 3-phosphonopropionate, propyl 3- (dimethylphosphono) propionate, Propyl 3- (diethylphosphono) propionate, propyl 3- (dibutylphosphono) propionate, tributyl 3-phosphonopropionate, butyl 3- (dimethylphosphono) propionate, butyl 3- (diethylphosphono) prop Pionate, butyl 3- (dipropylphosphono) propionate, methyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, ethyl 3- (bis (2,2,2-trifluoroethyl) phosphono ) Propionate, propyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, butyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate and the like.

<Compound with n ³² = 3 in Formula (3-2)>
Trimethyl 4-phosphonobutyrate, methyl 4- (diethylphosphono) butyrate, methyl 4- (dipropylphosphono) butyrate, methyl 4- (dibutylphosphono) butyrate, triethyl 4-phosphonobutyrate, ethyl 4- (Dimethylphosphono) butyrate, ethyl 4- (dipropylphosphono) butyrate, ethyl 4- (dibutylphosphono) butyrate, tripropyl 4-phosphonobutyrate, propyl 4- (dimethylphosphono) butyrate, propyl 4- (Diethylphosphono) butyrate, propyl 4- (dibutylphosphono) butyrate, tributyl 4-phosphonobutyrate, butyl 4- (dimethylphosphono) butyrate, butyl 4- (diethylphosphono) butyrate, butyl 4- (di Propylphosphono) butyrate and the like.

From the viewpoint of improving battery characteristics, compounds of n ³² = 0, 1, 2 are preferable, compounds of n ³² = 0, 1 are more preferable, compounds of n ³² = 1 are further preferable, and among compounds of n ³² = 1, compound a ⁹ to a ¹¹ is a saturated hydrocarbon group is preferred.
In particular, trimethyl phosphonoacetate, triethyl phosphonoacetate, 2-propynyl dimethylphosphonoacetate, and 2-propynyl diethylphosphonoacetate are preferable.

A phosphorus containing organic compound may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.
The phosphorus-containing organic compound (total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% in 100% by mass of the electrolytic solution. % By mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass. % Or less, more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic compound represented by the above formula (I) and the phosphorus-containing organic compound can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100, Preferably 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100 to 0. .1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-4. Organic Compound Having Cyano Group The electrolytic solution of the present invention can contain an organic compound having a cyano group. A battery using the electrolytic solution of the present invention having a cyano group has a small initial capacity loss and suppresses gas generation after high-temperature storage. The organic compound having a cyano group is not particularly limited as long as it is an organic compound having at least one cyano group in the molecule, but preferably the formula (4-1), the formula (4-2) and the formula It is a compound represented by (4-3), More preferably, it is a compound represented by Formula (4-1) and Formula (4-2), More preferably, it is represented by Formula (4-2). It is a compound.

In addition, when the organic compound having a cyano group is also a cyclic compound having a plurality of ether bonds, it may belong to a cyclic compound having a plurality of ether bonds.
In the electrolytic solution of the present invention, the combined use of the aromatic compound represented by the formula (I) and the organic compound having a cyano group improves the initial charge / discharge efficiency in a battery using this electrolytic solution. Thus, the charge / discharge efficiency after storage can be improved.

1-3-4-1. Compound represented by formula (4-1) A ¹ -CN (4-1)
(In the formula, A represents a hydrocarbon group having 2 to 20 carbon atoms.)
The molecular weight of the compound represented by Formula (4-1) is not particularly limited. The molecular weight is preferably 55 or more, more preferably 65 or more, still more preferably 80 or more, preferably 310 or less, more preferably 185 or less, and further preferably 155 or less. If it is this range, it will be easy to ensure the solubility of the compound represented by Formula (4-1) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The manufacturing method of the compound represented by Formula (4-1) is not particularly limited, and can be manufactured by arbitrarily selecting a known method.

In the formula (4-1), examples of the hydrocarbon group having 2 to 20 carbon atoms include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and the like. An ethyl group, an n-propyl group, an iso-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, tert-amyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, Alkyl group such as undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; vinyl group, 1-propenyl group, isopropenyl group, 1-butenyl, Alkenyl groups such as 1-pentenyl group; ethynyl group, 1-propynyl group, 1-butynyl group, 1-pentynyl group An alkynyl group of: phenyl group, tolyl group, ethylphenyl group, n-propylphenyl group, i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl group, Aryl groups such as a trifluoromethylphenyl group, a xylyl group, a benzyl group, a phenethyl group, a methoxyphenyl group, an ethoxyphenyl group, and a trifluoromethoxyphenyl group are preferred.

Of these, a straight chain or branched alkyl group having 2 to 15 carbon atoms and an alkenyl group having 2 to 4 carbon atoms are more preferable from the viewpoint that the ratio of the cyano group to the whole molecule is large and the effect of improving battery characteristics is high. Further, a linear or branched alkyl group having 2 to 12 carbon atoms is more preferable, and a linear or branched alkyl group having 4 to 11 carbon atoms is particularly preferable.
Examples of the compound represented by the formula (4-1) include propionitrile, butyronitrile, pentanenitrile, hexanenitrile, heptanenitrile, octanenitrile, pelargononitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclopentanecarbonitrile, Cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitryl, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2 -Pentenenitrile, 2-hexenenitrile and the like.

Among them, pentanenitrile, octanenitrile, decanenitrile, dodecanenitrile and crotononitrile are preferable from the viewpoint of stability of the compound, battery characteristics, and production, pentanenitrile, decanenitrile, dodecanenitrile and crotononitrile are more preferable, Pentanenitrile, decanenitrile and crotononitrile are preferred.
The compound represented by Formula (4-1) may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. The amount of the compound represented by the formula (4-1) (the total amount in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the nonaqueous electrolytic solution, and preferably is 0.00. 01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less. Is 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

1-3-4-2. Compound represented by formula (4-2) NC-A ² -CN (4-2)
(Where
A ² is an organic group having 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom. )
The organic group having 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom is a carbon atom and a hydrogen atom. In addition to an organic group composed of atoms, an organic group that may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, or a halogen atom is included. In the organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom, a part of the skeleton carbon atom in the group composed of the carbon atom and the hydrogen atom is substituted with these atoms. Or an organic group having a substituent composed of these atoms.

The molecular weight of the compound represented by Formula (4-2) is not particularly limited. The molecular weight is preferably 65 or more, more preferably 80 or more, still more preferably 90 or more, preferably 270 or less, more preferably 160 or less, and still more preferably 135 or less. If it is this range, it will be easy to ensure the solubility of the compound represented by Formula (4-2) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The method for producing the compound represented by the formula (4-2) is not particularly limited, and can be produced by arbitrarily selecting a known method.

As A ² in the compound represented by the formula (4-2), an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, a cycloalkenylene group or a derivative thereof, an arylene Group or derivative thereof, carbonyl group or derivative thereof, sulfonyl group or derivative thereof, sulfinyl group or derivative thereof, phosphonyl group or derivative thereof, phosphinyl group or derivative thereof, amide group or derivative thereof, imide group or derivative thereof, ether group or Examples thereof include a derivative thereof, a thioether group or a derivative thereof, a borinic acid group or a derivative thereof, a borane group or a derivative thereof.

Among these, from the viewpoint of improving battery characteristics, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, an arylene group or a derivative thereof is preferable. A ² is more preferably an alkylene group having 2 to 5 carbon atoms which may have a substituent.
Examples of the compound represented by the formula (4-2) include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, Isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3, 3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bi Cyclohexyl-2,2 Dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl -3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2 , 2,4,4-Tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4-dicyano Pentane, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, , 2-Didianobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′-(ethylenedithio) dipropionitrile, and 3, Examples include 9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane.

  Of these, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10 -Tetraoxaspiro [5,5] undecane and fumaronitrile are preferred from the viewpoint of improving storage characteristics. Furthermore, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, glutaronitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane are The effect of improving the storage characteristics is particularly excellent, and the deterioration due to the side reaction at the electrode is small, which is more preferable. Usually, in dinitrile compounds, the smaller the molecular weight, the larger the proportion of cyano groups in one molecule and the higher the viscosity of the molecule, while the higher the molecular weight, the higher the boiling point of the compound. Therefore, succinosuccinonitrile, glutaronitrile, adiponitrile, and pimelonitrile are more preferable from the viewpoint of improving working efficiency.

The compound represented by Formula (4-2) may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. The amount of the compound represented by the formula (4-2) (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass in 100% by mass of the electrolytic solution. % Or more, more preferably 0.1% by weight or more, still more preferably 0.3% by weight or more, particularly preferably 0.6% by weight or more, and can be 10% by weight or less, preferably 5% It is not more than mass%, more preferably not more than 3 mass%, still more preferably not more than 2 mass%, particularly preferably not more than 1.5 mass%, and most preferably not more than 1.0 mass%. Within this range, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

  1-3-4-3. Compound represented by formula (4-3)

(Where
A ³ is an organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of hydrogen atom, carbon atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom and halogen atom, n ⁴³ is an integer of 0 or more and 5 or less. )
The organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom is a carbon atom and In addition to an organic group composed of a hydrogen atom, an organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom is included. In the organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom, a part of the skeleton carbon atom in the group composed of the carbon atom and the hydrogen atom is substituted with these atoms. Or an organic group having a substituent composed of these atoms.

The n ⁴³ is an integer of 0 or more and 5 or less, preferably 0 or more and 3 or less, more preferably 0 or more and 1 or less, and particularly preferably 0.
In addition, A ³ is preferably an organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. It is more preferably an organic group having 1 or more and 12 or less carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom and an oxygen atom, and may have a substituent. More preferably, it is an aliphatic hydrocarbon group of 12 or less.

Here, the substituent represents a group composed of one or more atoms selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom and halogen atom.
Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups, alkoxy groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; carboxyl groups; alkoxycarbonyl groups; An alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group, preferably a halogen atom; an alkoxy group or an unsubstituted or halogen-substituted alkyl group; More preferably a halogen atom or an unsubstituted or halogen-substituted alkyl group, and still more preferably an unsubstituted alkyl group.

The aliphatic hydrocarbon group is not particularly limited, but may have 1 or more carbon atoms, preferably 2 or more, more preferably 3 or more, and 12 or less, preferably 8 Below, more preferably 6 or less.
Examples of the aliphatic hydrocarbon group, in response to n ^43, alkanetriyl, alkanetetrayl groups, alkane pen tile group, alkanetetrayl groups, alkene tri-yl group, alkene tetrayl group, alkene pen tile group, alkene Examples thereof include a tetrayl group, an alkyne triyl group, an alkyne tetrayl group, an alkyne pentile group, and an alkyne tetrayl group.

Of these, saturated hydrocarbon groups such as alkanetriyl groups, alkanetetrayl groups, alkanepentyl groups, and alkanetetrayl groups are more preferable, and alkanetriyl groups are more preferable.
Furthermore, the compound represented by the above formula (4-3) is more preferably a compound represented by the formula (4-3 ′).

(Wherein, ^{A 4} and ^{A 5} are as defined in the above ^{A 3.)}
The above A ⁴ and A ⁵ are more preferably a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent.
As the hydrocarbon group, methylene group, ethylene group, trimethylene group, tetraethylene group, pentamethylene group, vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group 2-pentenylene group, ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group, 2-pentynylene group and the like.

Among these, a methylene group, an ethylene group, a trimethylene group, a tetraethylene group, and a pentamethylene group are preferable, and a methylene group, an ethylene group, and a trimethylene group are more preferable.
A ⁴ and A ⁵ are preferably not the same as each other but different.
The molecular weight of the compound represented by Formula (4-3) is not particularly limited. The molecular weight is preferably 90 or more, more preferably 120 or more, further preferably 150 or more, preferably 450 or less, more preferably 300 or less, and further preferably 250 or less. If it is this range, it will be easy to ensure the solubility of the compound represented by Formula (4-3) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The manufacturing method of the compound represented by Formula (4-3) is not particularly limited, and can be manufactured by arbitrarily selecting a known method.

  Examples of the compound represented by the formula (4-3) include the following compounds.

  Of these,

Is preferable from the viewpoint of improving the storage characteristics.
The organic compound which has a cyano group may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios.
The amount of the compound represented by formula (4-3) (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass in 100% by mass of the electrolytic solution. % Or more, more preferably 0.1% by weight or more, still more preferably 0.3% by weight or more, particularly preferably 0.6% by weight or more, and can be 10% by weight or less, preferably 5% It is not more than mass%, more preferably not more than 3 mass%, still more preferably not more than 2 mass%, particularly preferably not more than 1.5 mass%, and most preferably not more than 1.0 mass%. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

The mass ratio of the aromatic compound represented by formula (I) and the organic compound having a cyano group may be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100, More preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100 to 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-5. The organic compound which has an isocyanate group The electrolyte solution of this invention can contain the organic compound which has an isocyanate group. The organic compound having an isocyanate group is not particularly limited as long as it is an organic compound having at least one isocyanate group in the molecule. The number of isocyanate groups is preferably 1 or more and 4 or less, more preferably 2 or more and 3 or less, and still more preferably 2 in one molecule.

  In the electrolytic solution of the present invention, by using the aromatic compound represented by the formula (I) and the compound having an isocyanate group in combination, in a battery using this electrolytic solution, while maintaining load characteristics, at high temperature storage While the generation of gas can be suppressed, gas can be generated during overcharging to ensure safety. The organic compound having an isocyanate group is preferably a linear or branched alkylene group, a cycloalkylene group, a structure in which a cycloalkylene group and an alkylene group are linked, an aromatic hydrocarbon group, an aromatic hydrocarbon group and an alkylene group. , Ether structure (—O—), ether structure (—O—) and alkylene group linked structure, carbonyl group (—C (═O) —), carbonyl group and alkylene group linked structure , A sulfonyl group (—S (═O) —), a structure in which a sulfonyl group and an alkylene group are linked, or a compound having a structure in which these are halogenated, and the like. Chain or branched alkylene group, cycloalkylene group, structure in which cycloalkylene group and alkylene group are linked, aromatic hydrocarbon Or an aromatic hydrocarbon group and an isocyanate group in a structure in which alkylene groups are linked a compound bound, more preferably a compound that the isocyanate group is bonded to a structure in which a cycloalkylene group and an alkylene group are linked. The molecular weight of the organic compound having an isocyanate group is not particularly limited. The molecular weight is preferably 80 or more, more preferably 115 or more, still more preferably 170 or more, and 300 or less, more preferably 230 or less. If it is this range, it will be easy to ensure the solubility of the organic compound which has an isocyanate group with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the organic compound having an isocyanate group is not particularly limited, and can be produced by arbitrarily selecting a known method. Moreover, you may use a commercial item.

Examples of the organic compound having an isocyanate group include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, tertiary butyl isocyanate, pentyl isocyanate hexyl isocyanate, cyclohexyl isocyanate, vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, propargyl isocyanate, phenyl. An organic compound having one isocyanate group such as isocyanate or fluorophenyl isocyanate;
Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-diisocyanate Natopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5 -Diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanato) Methyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1 ′ -Diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-
4,4′-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (
Methyl isocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methyl isocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, 1,5- Organic compounds having two isocyanate groups such as diisocyanatopentane-1,5-dione, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate;
Etc.

Among these, monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1]
Heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2 Organic compounds having two isocyanate groups, such as 1,4,4-trimethylhexamethylene diisocyanate, are preferable from the viewpoint of improving storage characteristics, and hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4 , 4'-diisocyanate, bicyclo [
2.2.1] Heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexa Methylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate are more preferred, and 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1 More preferred are heptane-2,5-diylbis (methylisocyanate) and bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate).

  The organic compound having an isocyanate group may be a trimer compound derived from a compound having at least two isocyanate groups in the molecule, or an aliphatic polyisocyanate obtained by adding a polyhydric alcohol thereto. Examples thereof include biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of the following formulas (5-1) to (5-4).

(In the formula, R ^{51 to} R ⁵⁴ and R ⁵⁴ ′ are independently a divalent hydrocarbon group (for example, a tetramethylene group or a hexamethylene group), and R ⁵³ ′ is independently a trivalent group. Hydrocarbon group.)
Organic compounds having at least two isocyanate groups in the molecule also include so-called blocked isocyanates that are blocked with a blocking agent to enhance storage stability. Examples of the blocking agent include alcohols, phenols, organic amines, oximes, and lactams. Specific examples include n-butanol, phenol, tributylamine, diethylethanolamine, methyl ethyl ketoxime, and ε-caprolactam. Etc.

For the purpose of promoting a reaction based on an organic compound having an isocyanate group and obtaining a higher effect, a metal catalyst such as dibutyltin dilaurate or the like, 1,8-diazabicyclo [5.4
. 0] It is also preferable to use an amine catalyst such as undecene-7 in combination.
The organic compound which has an isocyanate group may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios.

The amount of the organic compound having an isocyanate group (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably in 100% by mass of the electrolytic solution. Is 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more Preferably it is 3 mass% or less, More preferably, it is 2 mass% or less, Most preferably, it is 1.5 mass% or less, Most preferably, it is 1.0 mass% or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic compound represented by the above formula (I) and the organic compound having an isocyanate group may be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100. More preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100. ~ 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-6. Silicon-containing compound The electrolytic solution of the present invention may contain a silicon-containing compound. The silicon-containing compound is not particularly limited as long as it is a compound having at least one silicon atom in the molecule. In the electrolytic solution of the present invention, by using the aromatic compound represented by the formula (I) and the silicon-containing compound in combination, the initial volume change rate is further reduced, the rate capacity ratio after high-temperature storage and the safety during overcharge Can be improved.

  As the silicon-containing compound, a compound represented by the following formula (6) is preferable.

(Where
R ⁶¹ , R ⁶² and R ⁶³ are each independently a hydrogen atom, a halogen atom or a hydrocarbon group having 10 or less carbon atoms,
X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a silicon atom. )
For the hydrocarbon group, the examples and preferred examples of the hydrocarbon group in the formula (I) are applied. R ⁶¹ , R ⁶² and R ⁶³ are preferably hydrogen atom, fluorine atom, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert. -A butyl group and a phenyl group, more preferably a methyl group.

X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a silicon atom, and preferably an organic group containing at least an oxygen atom or a silicon atom. Here, the organic group refers to a group composed of one or more atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, silicon atoms, sulfur atoms, phosphorus atoms and halogen atoms. Represent. Examples of the organic group include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, a CN group, an isocyanato group, a fluoro group, an alkylsulfonic acid group, and a trialkylsilyl group. A part of the monovalent organic group may be substituted with a halogen atom. The carbon number of the organic group can be 1 or more, preferably 3 or more, more preferably 5 or more, and 15 or less, preferably 12
Below, more preferably 8 or less.

Of these, alkylsulfonic acid groups, trialkylsilyl groups, boric acid groups, phosphoric acid groups and phosphorous acid groups are preferred.
Examples of the silicon-containing compound include the following compounds.
Tris borate (trimethylsilyl), tris borate (trimethoxysilyl), tris borate (triethylsilyl), tris borate (triethoxysilyl), tris borate (dimethylvinylsilyl) and tris borate (diethylvinylsilyl) Boric acid compounds such as: Tris phosphate (trimethylsilyl), Tris phosphate (triethylsilyl), Tris phosphate (tripropylsilyl), Tris phosphate (triphenylsilyl), Tris phosphate (trimethoxysilyl), Phosphoric acid Phosphoric acid compounds such as tris (triethoxysilyl), tris (triphenoxysilyl) phosphate, tris (dimethylvinylsilyl) phosphate and tris (diethylvinylsilyl) phosphate;
Tris phosphite (trimethylsilyl), Tris phosphite (triethylsilyl), Tris phosphite (tripropylsilyl), Tris phosphite (triphenylsilyl), Tris phosphite (trimethoxysilyl), Phosphorous acid Phosphite compounds such as tris (triethoxysilyl), tris phosphite (triphenoxysilyl), tris phosphite (dimethylvinylsilyl) and tris phosphite (diethylvinylsilyl);
Sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate;
Hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, 1,1,2,2-tetraethyldisilane, 1,2-diphenyltetramethyldisilane and 1,1,2,2-tetraphenyl Disilane compounds such as disilane;
Etc.

  Of these, tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite, trimethylsilyl methanesulfonate, trimethylsilyl tetrafluoromethanesulfonate, hexamethyldisilane, hexaethyldisilane, 1,2- Diphenyltetramethyldisilane and 1,1,2,2-tetraphenyldisilane are preferred, and tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite and hexamethyldisilane are more preferred.

In addition, these silicon containing compounds may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The silicon-containing compound (total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass in 100% by mass of the electrolytic solution. % Or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass. Hereinafter, it is more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic compound represented by the above formula (I) and the silicon-containing compound can be 0.0001: 100-1000000: 100, preferably 0.0005: 100-100: 100, more preferably Is 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, and most preferably 0.005: 100 to 0.100. 1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-7. Aromatic compounds other than formulas (I) and (II) The electrolyte solution of the present invention may contain an aromatic compound other than formulas (I) and (II).
The aromatic compound other than the formulas (I) and (II) is not particularly limited as long as it is an organic compound other than the formula (II) having an aromatic ring in the molecule. It is an aromatic compound having at least one substituent represented by (7). By adding an aromatic compound other than the formulas (I) and (II) to the electrolytic solution of the present invention, the safety of the battery using the electrolytic solution is further improved during overcharge and imparts good high-temperature storage characteristics. can do.

(Where
The substituent X ⁷¹ represents an organic group which may have a halogen atom, a halogen atom or a hetero atom. The organic group which may have a hetero atom is a linear, branched or cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, a group having a carboxylic acid ester structure, a group having a carbonate structure, a phosphorus atom , A group having a sulfur atom, and a group having a silicon atom. In addition, each substituent may be further substituted with a halogen atom, a hydrocarbon group, an aromatic group, a halogen-containing hydrocarbon group, a halogen-containing aromatic group, or the like. Further, the number n ⁷¹ of the substituent X ⁷¹ is 1 or more and 6 or less, and when having a plurality of substituents, each substituent may be the same or different, and may form a ring. )
Among these, a linear, branched or cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, a group having a carboxylic acid ester structure, and a group having a carbonate structure are preferable from the viewpoint of battery characteristics. More preferably, it is a group having a straight chain, branched chain or cyclic saturated hydrocarbon group having 3 to 12 carbon atoms and a carboxylate structure.

The number n ⁷¹ of the substituents X ⁷¹ is preferably 1 or more 5 or less, more preferably 1 to 3, still more preferably 1 to 2, particularly preferably 1.
X ⁷¹ represents a halogen atom, a halogen atom or an organic group which may have a hetero atom.
Examples of the halogen atom include chlorine, fluorine and the like, preferably fluorine.

  Examples of the organic group having no hetero atom include linear, branched, and cyclic saturated hydrocarbon groups having 3 to 12 carbon atoms. The linear and branched groups include those having a ring structure. It is. Specific examples of linear, branched, and cyclic saturated hydrocarbon groups having 1 to 12 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and pentyl. Group, tert-pentyl group, cyclopentyl group, cyclohexyl group, butylcyclohexyl group, and the like. The number of carbon atoms is preferably 3 or more and 12 or less, more preferably 3 or more and 10 or less, still more preferably 3 or more and 8 or less, still more preferably 3 or more and 6 or less, and most preferably 3 or more and 5 or less.

Examples of the hetero atom constituting the organic group having a hetero atom include an oxygen atom, a sulfur atom, a phosphorus atom, and a silicon atom. Examples of the group having an oxygen atom include a group having a carboxylic ester structure and a group having a carbonate structure. Examples of those having a sulfur atom include groups having a sulfonate structure. Examples of those having a phosphorus atom include a group having a phosphate ester structure, a group having a phosphonate ester structure, and the like. Examples of the group having a silicon atom include a group having a silicon-carbon structure.

Examples of the aromatic compound represented by the formula (7) include the following.
As ^X71 being a halogen atom or an organic group which may have a halogen atom, chlorobenzene, fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride, etc. And preferred are fluorobenzene and hexafluorobenzene. More preferred is fluorobenzene.

As X ⁷¹ is a hydrocarbon group having 1 to 12 carbon atoms,
2,2-diphenylpropane, 1,4-diphenylcyclohexane, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4- Phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, propylbenzene, butylbenzene, tert-butylbenzene, tert-amylbenzene, and the like, preferably 2,2-diphenylpropane, 1,4-diphenylcyclohexane, Cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexa , Trans-1-butyl-4-phenylcyclohexane, toluene, ethylbenzene, propylbenzene, butylbenzene, tert-butylbenzene, tert-amylbenzene, and more preferably 2,2-diphenylpropane, cyclopentylbenzene, cyclohexylbenzene 1,1-diphenylcyclohexane, tert-butylbenzene, and tert-amylbenzene, and more preferably cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene.

As ^X71 is a group having a carboxylate structure,
Phenyl acetate, benzyl acetate, 2-phenylethyl acetate, 3-phenylpropyl acetate, 4-phenylbutyl acetate, phenyl propionate, benzyl propionate, 2-phenylethyl propionate, 3-phenylpropyl propionate, 4-propionate 4- Phenyl butyl, phenyl butyrate, benzyl butyrate, 2-phenylethyl butyrate, 3-phenylpropyl butyrate, 4-phenylbutyl butyrate, methyl phenylacetate, ethyl phenylacetate, propylphenylacetate, butylphenylacetate, phenylphenylacetate, phenylphenylacetate 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, 4-phenylbutyl phenylacetate, methyl 2,2-dimethyl-phenylacetate, ethyl 2,2-dimethyl-phenylacetate, 2,2-dimethyl-phenyl Propyl nyl acetate, 2,2-dimethyl-phenyl acetate butyl, 2,2-dimethyl-phenyl acetate phenyl, 2,2-dimethyl-phenyl acetate benzyl, 2,2-dimethyl-phenyl acetate 2-phenylethyl, 2,2 -3-phenylpropyl dimethyl-phenylacetate, 4-phenylbutyl 2,2-dimethyl-phenylacetate, methyl 3-phenylpropionate, ethyl 3-phenylpropionate, propyl 3-phenylpropionate, butyl 3-phenylpropionate , Phenyl 3-phenylpropionate, benzyl 3-phenylpropionate, 2-phenylethyl 3-phenylpropionate, 3-phenylpropyl 3-phenylpropionate, 4-phenylbutyl 3-phenylpropionate, methyl 4-phenylbutyrate 4-phenylbutyric acid ethyl Propyl 4-phenylbutyrate, butyl 4-phenylbutyrate, phenyl 4-phenylbutyrate, benzyl 4-phenylbutyrate, 2-phenylethyl 4-phenylbutyrate, 3-phenylpropyl 4-phenylbutyrate, 4-phenylbutyrate Butyl, methyl 5-phenyl valerate, ethyl 5-phenyl valerate, propyl 5-phenyl valerate, butyl 5-phenyl valerate, phenyl 5-phenyl valerate, benzyl 5-phenyl valerate, 5-phenyl valerate 2 -Phenylethyl, 3-phenylpropyl 5-phenylvalerate, 4-phenylbutyl 5-phenylvalerate, methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, propyl 1-phenylcyclopentanecarboxylate 1-phenylcyclopentanecarboxylic acid buty 1-phenylcyclopentanecarboxylic acid phenyl, 1-phenylcyclopentanecarboxylic acid benzyl, 1-phenylcyclopentanecarboxylic acid 2-phenylethyl, 1-phenylcyclopentanecarboxylic acid 3-phenylpropyl, 1-phenylcyclopentanecarboxylic acid 4-phenylbutyl acid, 2,2-bis (4-acetoxyphenyl) propane, and the like, preferably 2-phenylethyl acetate, 3-phenylpropyl acetate, 4-phenylbutyl acetate, 2-phenylethyl propionate 3-phenylpropyl propionate, 4-phenylbutyl propionate, 2-phenylethyl butyrate, 3-phenylpropyl butyrate, 4-phenylbutyl butyrate, methyl phenylacetate, ethyl phenylacetate, propylphenylacetate, butylphenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, 4-phenylbutyl phenylacetate, methyl 2,2-dimethyl-phenylacetate, ethyl 2,2-dimethyl-phenylacetate, propyl 2,2-dimethyl-phenylacetate 2,2-dimethyl-phenylacetic acid butyl, 2,2-dimethyl-phenylacetic acid 2-phenylethyl, 2,2-dimethyl-phenylacetic acid 3-phenylpropyl, 2,2-dimethyl-phenylacetic acid 4-phenylbutyl, Methyl 3-phenylpropionate, ethyl 3-phenylpropionate, propyl 3-phenylpropionate, butyl 3-phenylpropionate, 2-phenylethyl 3-phenylpropionate, 3-phenylpropyl 3-phenylpropionate, 3- 4-phenylbutyl phenylpropionate Methyl 4-phenylbutyrate, ethyl 4-phenylbutyrate, propyl 4-phenylbutyrate, butyl 4-phenylbutyrate, 2-phenylethyl 4-phenylbutyrate, 3-phenylpropyl 4-phenylbutyrate, 4-phenylbutyl 4-phenylbutyrate Methyl 5-phenylvalerate, ethyl 5-phenylvalerate, propyl 5-phenylvalerate, butyl 5-phenylvalerate, 2-phenylethyl 5-phenylvalerate, 3-phenylpropyl 5-phenylvalerate, 5 4-phenylbutyl phenylvalerate, methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, propyl 1-phenylcyclopentanecarboxylate, butyl 1-phenylcyclopentanecarboxylate, 1-phenylcyclopentane 2-phenylethyl carboxylate, 1 -3-phenylpropyl phenylcyclopentanecarboxylate, more preferably 2-phenylethyl acetate, 3-phenylpropyl acetate, methyl phenylacetate, ethyl phenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate 2,2-dimethyl-phenylacetic acid methyl, 2,2-dimethyl-phenylacetic acid ethyl, 2,2-dimethyl-phenylacetic acid 2-phenylethyl, 2,2-dimethyl-phenylacetic acid 3-phenylpropyl, 3-phenylpropoxy Methyl onate, ethyl 3-phenylpropionate, 2-phenylethyl 3-phenylpropionate, 3-phenylpropyl 3-phenylpropionate, methyl 5-phenylvalerate, ethyl 5-phenylvalerate, 5-phenylvalerate 2-phenylethyl, 5-pheny 3-phenylpropyl valerate, methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, 2-phenylethyl 1-phenylcyclopentanecarboxylate, 3-phenylpropyl 1-phenylcyclopentanecarboxylate And more preferably 2-phenylethyl acetate, 3-phenylpropyl acetate, methyl phenylacetate, ethyl phenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, methyl 2,2-dimethyl-phenylacetate, 2 , 2-dimethyl-phenyl ethyl acetate, 2,2-dimethyl-phenyl acetate 2-phenylethyl, 2,2-dimethyl-phenyl acetate 3-phenylpropyl, methyl 3-phenylpropionate, ethyl 3-phenylpropionate, 3-phenyl 2-phenylethyl lopionate, 3-phenylpropyl 3-phenylpropionate, methyl 5-phenylvalerate, ethyl 5-phenylvalerate, 2-phenylethyl 5-phenylvalerate, 3-phenylpropyl 5-phenylvalerate 1-phenylcyclopentanecarboxylic acid methyl, 1-phenylcyclopentanecarboxylic acid ethyl, 1-phenylcyclopentanecarboxylic acid 2-phenylethyl, 1-phenylcyclopentanecarboxylic acid 3-phenylpropyl.

As X ⁷¹ is a group having a carbonate structure,
2,2-bis (4-methoxycarbonyloxyphenyl) propane, 1,1-bis (4-methoxycarbonyloxyphenyl) cyclohexane, diphenyl carbonate, methylphenyl carbonate, ethylphenyl carbonate,
2-tert-butylphenylmethyl carbonate, 2-tert-butylphenylethyl carbonate, bis (2-tert-butylphenyl) carbonate, 4-tert-butylphenylmethyl carbonate, 4-tert-butylphenylethyl carbonate, bis (4 -Tert-butylphenyl) carbonate, benzylmethyl carbonate, benzylethyl carbonate, dibenzyl carbonate and the like, preferably 2,2-bis (4-methoxycarbonyloxyphenyl) propane, 1,1-bis (4-methoxy) Carbonyloxyphenyl) cyclohexane, diphenyl carbonate, and methylphenyl carbonate, more preferably diphenyl carbonate and methylphenyl carbonate, and even more preferable. It is methyl phenyl carbonate.

As ^X71 is a group having a sulfonate structure,
Methyl phenyl sulfonate, ethyl phenyl sulfonate, diphenyl sulfonate,
Examples include phenylmethyl sulfonate, 2-tert-butylphenyl methyl sulfonate, 4-tert-butylphenyl methyl sulfonate, cyclohexyl phenyl methyl sulfonate, and the like, preferably methyl phenyl sulfonate, diphenyl sulfonate, 2-tert-butylphenyl methyl sulfonate, 4 -Tert-butylphenyl methyl sulfonate and cyclohexyl phenyl methyl sulfonate, more preferably methyl phenyl sulfonate, 2-tert-butylphenyl methyl sulfonate, 4-tert-butylphenyl methyl sulfonate and cyclohexyl phenyl methyl sulfonate.

As ^X71 is a group having a silicon-carbon structure,
Examples include trimethylphenylsilane, diphenylsilane, diphenyltetramethyldisilane, and the like, preferably trimethylphenylsilane.
As ^X71 is a group having a phosphate structure,
Triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylphenyl) phosphate, tris (4-tert-butylphenyl) phosphate, tris (2-tert-amylphenyl) phosphate, tris ( 3-tert-amylphenyl) phosphate, tris (4-tert-amylphenyl) phosphate, tris (2-cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, diethyl (4 -Methylbenzyl) phosphonate and the like, preferably triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylpheny). ) Phosphate, tris (4-tert-butylphenyl) phosphate, tris (2-tert-amylphenyl) phosphate, tris (3-tert-amylphenyl) phosphate, tris (4-tert-amylphenyl) phosphate, tris (2 -Cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, more preferably tris (2-tert-butylphenyl) phosphate, tris (4-tert-butylphenyl) Phosphate, tris (2-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate.

As X ⁷¹ is a group having a phosphonic acid ester structure,
Dimethylphenylphosphonate, diethylphenylphosphonate, methylphenylphenylphosphonate, ethylphenylphenylphosphonate, diphenylphenylphosphonate, dimethyl- (4-fluorophenyl) -phosphonate, dimethylbenzylphosphonate, diethylbenzylphosphonate, methylphenylbenzylphosphonate, ethylphenylbenzylphosphonate , Diphenylbenzylphosphonate, dimethyl- (4-fluorobenzyl) phosphonate, diethyl- (4-fluorobenzyl) phosphonate and the like, preferably dimethylphenylphosphonate, diethylphenylphosphonate, dimethyl- (4-fluorophenyl) phosphonate, Dimethyl benzyl phosphonate, diethyl benzyl phosphonate, di Methyl- (4-fluorobenzyl) phosphonate, diethyl- (4-fluorobenzyl) phosphonate, more preferably dimethylphenylphosphonate, diethylphenylphosphonate, dimethylbenzylphosphonate, diethylbenzylphosphonate, dimethyl- (4-fluorobenzyl) phosphonate , Diethyl- (4-fluorobenzyl) phosphonate.

Moreover, as aromatic compounds other than formula (I) and (II), the fluorinated body of the said aromatic compound is also contained. In particular,
Partially fluorinated compounds having hydrocarbon groups such as trifluoromethylbenzene, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, trifluoromethylbenzene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2- Partially fluorinated products of carboxylic acid ester structures such as fluorophenyl acetate and 4-fluorophenyl acetate; trifluoromethoxybenzene, 2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, 2 , 5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole, partially fluorinated compounds having an ether structure such as 4-trifluoromethoxyanisole, etc. Preferably a partially fluorinated product having a hydrocarbon group such as trifluoromethylbenzene, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2-fluorophenylacetate , Partially fluorinated compounds having a carboxylic acid ester structure such as 4-fluorophenylacetate; ether structures such as trifluoromethoxybenzene 2-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, 4-trifluoromethoxyanisole A partially fluorinated compound having a hydrocarbon group, more preferably a partially fluorinated compound having a hydrocarbon group such as 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, etc .; Partially fluorinated products of carboxylic acid ester structures such as phenyl acetate and 4-fluorophenyl acetate; trifluoromethoxybenzene, 2-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, 4-trifluoromethoxyanisole, etc. A partially fluorinated compound having an ether structure of

  Aromatic compounds other than formulas (I) and (II) may be used alone or in combination of two or more in any combination and ratio. The amount of the aromatic compound other than the formulas (I) and (II) (the total amount in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the electrolytic solution, and preferably is 0.00. 01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, most preferably 1% by mass or more, and most preferably 1.5% by mass. It can be 10% by mass or less, preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass or less. If it is within this range, the effects of the present invention are easily exhibited, and it is easy to prevent an increase in battery resistance.

The mass ratio of the aromatic compound represented by the formula (I) and the aromatic compound other than the formulas (I) and (II) can be 0.0001: 100 to 1000000: 100, preferably 0. .0005: 100 to 100: 100, more preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, and particularly preferably 0.003.
: 100 to 0.5: 100, most preferably 0.005: 100 to 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-8. Cyclic carbonate having a carbon-carbon unsaturated bond Cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter also referred to as “unsaturated cyclic carbonate”) is a cyclic having a carbon-carbon double bond or a carbon-carbon triple bond. If it is carbonate, there will be no restriction | limiting in particular. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate. A battery using the electrolytic solution of the present invention containing an unsaturated cyclic carbonate is excellent in initial irreversible capacity and post-storage characteristics. The cyclic carbonate having a fluorinated carbon-carbon unsaturated bond is included in the fluorine-containing cyclic carbonate.

Examples of the unsaturated cyclic carbonate include a cyclic carbonate having a carbon-carbon unsaturated bond and a five-membered ring structure, a cyclic carbonate having a carbon-carbon unsaturated bond and a six-membered ring structure, A cyclic carbonate having a carbon-carbon unsaturated bond and having a five-membered ring structure is preferred.
Examples of the cyclic carbonate having a carbon-carbon unsaturated bond and having a five-membered ring structure include vinylene carbonates, aromatic rings, or ethylene substituted with a substituent having a carbon-carbon double bond or carbon-carbon triple bond. Examples thereof include carbonates and catechol carbonates, and examples of the cyclic carbonate having a carbon-carbon unsaturated bond and a six-membered ring structure include 4H-1,3-dioxin-2-ones.

As vinylene carbonates, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4 , 5-diallyl vinylene carbonate and the like.

  Examples of ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate. 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-allyl-5- Ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4 5-diallyl carbonate, 4-methyl-5-allyl carbonate and the like.

As specific examples of 4H-1,3-dioxin-2-ones,
4H-1,3-dioxin-2-one, 4-methyl-4H-1,3-dioxin-2-one, 5-methyl-4H-1,3-dioxin-2-one, 6-methyl-4H- 1,3-dioxin-2-one, 4,5-dimethyl-4H-1,3-dioxin-2-one, 4,6-dimethyl-4H-1,3-dioxin-2-one, 5,6- Dimethyl-4H-1,3-dioxin-2-one, 4-phenyl-4H-1,3-dioxin-2-one, 5-phenyl-4H-1,3-dioxin-2-one, 6-phenyl- 4H-1,3-dioxin-2-one and the like can be mentioned.

Specific examples of trimethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond or a carbon-carbon triple bond include:
4-vinyl-1,3-dioxan-2-one, 4,5-divinyl-1,3-dioxan-2-one, 4-methyl-5-vinyl-1,3-dioxan-2-one, 4- Allyl-5-vinyl-1,3-dioxan-2-one, ethynyl-1,3-dioxan-2-one, 4,5-diethynyl-1,3-dioxan-2-one, 4-methyl-5 Ethynyl-1,3-dioxan-2-one, 4-vinyl-5-ethynyl-1,3-dioxan-2-one, 4-allyl-5-ethynyl-1,3-dioxan-2-one, 4- Phenyl-1,3-dioxan-2-one, 4,5-diphenyl-1,3-dioxan-2-one, 4-phenyl-5-vinyl-1,3-dioxan-2-one, 4-allyl- 5-phenyl-1,3-dioxan-2-one, 4- Lil-1,3-dioxan-2-one, 4,5-diallyl-1,3-dioxan-2-one, 4-methyl-5-allyl-1,3-dioxan-2-one, and the like.

Among them, particularly preferable unsaturated cyclic carbonates for use in combination with the aromatic compound represented by the formula (I) include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5- Vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethyl Le ethylene carbonate include 4-vinyl-5-ethynyl-ethylene carbonate. Vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are particularly preferable because they form a more stable interface protective film.

  The molecular weight of the unsaturated cyclic carbonate is preferably 86 or more, and is preferably 250 or less, more preferably 150 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily. The production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.

An unsaturated cyclic carbonate may be used individually by 1 type, or may have 2 or more types by arbitrary combinations and ratios.
The amount of unsaturated cyclic carbonate (total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0% in 100% by mass of the electrolytic solution. 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass, more preferably 4% by mass. It is not more than mass%, more preferably not more than 3 mass%, particularly preferably not more than 2 mass%, most preferably not more than 1.5 mass%. Within this range, the non-aqueous electrolyte battery is likely to exhibit a sufficient cycle characteristics improvement effect, avoids the situation where the high-temperature storage characteristics decrease, the amount of gas generated increases, and the discharge capacity maintenance ratio decreases. It's easy to do.

The mass ratio of the aromatic compound represented by the formula (I) and the unsaturated cyclic carbonate may be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100. Preferably 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100 to 0. .1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-9. Fluorine-free carboxylic acid ester The electrolyte solution of the present invention may contain a fluorine-free carboxylic acid ester. In the electrolytic solution of the present invention, the high temperature storage characteristics of the battery can be improved by using the aromatic compound represented by the formula (I) and the fluorine-free carboxylic acid ester in combination. The fluorine-free carboxylic acid ester is not particularly limited as long as it is a carboxylic acid ester having no fluorine atom in the molecule, but is preferably a fluorine-free chain carboxylic acid ester. The total carbon number of the fluorine-free chain carboxylic acid ester is preferably 3 or more and 7 or less, more preferably 4 or more and 6 or less, and still more preferably 5.

Examples of the fluorine-free chain carboxylic acid ester include the following.
Methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-propionate Butyl, isobutyl propionate, tert-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, isobutyl butyrate, tert-butyl butyrate, methyl isobutyrate, ethyl isobutyrate, iso N-propyl butyrate, isopropyl isobutyrate, n-butyl isobutyrate, isobutyl isobutyrate, tert-butyl isobutyrate, methyl valerate, ethyl valerate, n-propyl valerate, isopropyl valerate, n-butyl valerate, Isobutyl valerate, valerate-ter -Butyl, methyl hydroangelate, ethyl hydroangelate, n-propyl hydroangelate, isopropyl hydroangelate, n-butyl hydroangelate, isobutyl hydroangelate, tert-butyl hydroangelate, methyl isovalerate, Ethyl isovalerate, n-propyl isovalerate, isopropyl isovalerate, n-butyl isovalerate, isobutyl isovalerate, isotert-butyl isovalerate, methyl pivalate, ethyl pivalate, n-propyl pivalate , Isopropyl pivalate, n-butyl pivalate, isobutyl pivalate, tert-butyl pivalate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, Acrylic acid tert-butyl, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, methyl crotonate, ethyl crotonate, n-crotonate -Propyl, isopropyl crotonate, n-butyl crotonate, isobutyl crotonate, tert-butyl crotonate, methyl 3-butenoate, ethyl 3-butenoate, n-propyl 3-butenoate, isopropyl 3-butenoate, N-butyl 3-butenoate, isobutyl 3-butenoate, tert-butyl 3-butenoate, methyl 4-pentenoate, ethyl 4-pentenoate, n-propyl 4-pentenoate, isopropyl 4-pentenoate, 4 -N-butyl pentenoate, isobu 4-pentenoate Chill, 4-pentenoate-tert-butyl, methyl 3-pentenoate, ethyl 3-pentenoate, n-propyl 3-pentenoate, isopropyl 3-pentenoate, n-butyl 3-pentenoate, isobutyl 3-pentenoate Tert-butyl 3-pentenoate, methyl 2-pentenoate, ethyl 2-pentenoate, n-propyl 2-pentenoate, isopropyl 2-pentenoate, n-butyl 2-pentenoate, isobutyl 2-pentenoate, 2-pentenoic acid-tert-butyl, 2-propionic acid methyl, 2-propionic acid ethyl, 2-propionic acid n-propyl, 2-propionic acid isopropyl, 2-propionic acid n-butyl, 2-propionic acid isobutyl, 2 -Propionic acid-tert-butyl, methyl 3-butyrate, ethyl 3-butyrate, n-propyl 3-butyrate, 3 Isopropyl butyrate, n-butyl 3-butyrate, isobutyl 3-butyrate, 3-tert-butyl butyrate, methyl 2-butyrate, ethyl 2-butyrate, n-propyl 2-butyrate, 2-butyne Isopropyl acid, 2-butynoic acid n-butyl, 2-butynoic acid isobutyl, 2-butynoic acid-tert-butyl, 4-pentynoic acid methyl, 4-pentynoic acid ethyl, 4-pentynoic acid n-propyl, 4-pentynoic acid Isopropyl, 4-pentynoic acid n-butyl, 4-pentynoic acid isobutyl, 4-pentynoic acid-tert-butyl, 3-pentynoic acid methyl, 3-pentynoic acid ethyl, 3-pentynoic acid n-propyl, isopropyl 3-pentynoate , 3-pentynoic acid n-butyl, 3-pentynoic acid isobutyl, 3-pentynoic acid-tert-butyl, 2-pentynoic acid methyl , 2-pentyne ethyl, 2-pentyne acid n- propyl, 2-pentyne isopropyl, 2-pentyne acid n- butyl, 2-pentyne isobutyl, 2-pentyne acid -tert- butyl.

  Among these, since there are few side reactions at the negative electrode, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, n-butyl propionate, Methyl butyrate, ethyl butyrate, n-propyl butyrate, n-butyl butyrate, methyl valerate, ethyl valerate, n-propyl valerate, n-butyl valerate, methyl pivalate, ethyl pivalate, n-propyl pivalate, N-Butyl pivalate is preferred, and from the viewpoint of improving ionic conductivity due to a decrease in viscosity of the electrolyte, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n propionate n -Propyl and n-butyl propionate are more preferred, methyl propionate, ethyl propionate, propionic acid - propyl, n- butyl propionate are more preferable, and ethyl propionate, propionic acid n- propyl particularly preferred.

The fluorine-free carboxylic acid ester may be used alone or in combination of two or more in any combination and ratio.
The amount of the fluorine-free carboxylic acid ester (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably in 100% by mass of the electrolytic solution. Is 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Most preferably, it is 1 mass% or less. Further, the blending amount when the fluorine-free carboxylic acid ester is used as a non-aqueous solvent is preferably 1% by volume or more, more preferably 5% by volume or more, and further preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. Further, it is more preferably 20% by volume or more, and it can be contained at 50% by volume or less, more preferably 45% by volume or less, still more preferably 40% by volume or less. Within such a range, increase in negative electrode resistance is suppressed, and output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics can be easily controlled.

  The mass ratio of the aromatic compound represented by the above formula (I) and the fluorine-free carboxylic acid ester can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100. More preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100. ~ 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-10. Cyclic compound having a plurality of ether bonds The cyclic compound having a plurality of ether bonds is not particularly limited as long as it is a cyclic compound having a plurality of ether bonds in the molecule, but is preferably a compound represented by the formula (10) It is. The cyclic compound having a plurality of ether bonds contributes to the improvement of the high-temperature storage characteristics of the battery. In the electrolytic solution of the present invention, it is good when used together with the aromatic compound represented by the formula (I) The initial characteristics can be maintained.

(Where
A ^{15 to} A ²⁰ independently represent a hydrogen atom, a fluorine atom, or a hydrocarbon group having 1 to 5 carbon atoms that may have a substituent. n ¹⁰¹ is an integer of 1 or more and 4 or less, and when n ¹⁰¹ is an integer of 2 or more, the plurality of A ¹⁷ and A ¹⁸ may be the same or different. )
Two members selected from A ^{15 to} A ²⁰ may be bonded to each other to form a ring. In this case, it is preferable to form a ring structure with A ¹⁷ and A ¹⁸ . The total number of carbon atoms of A ^{15 to} A ²⁰ is preferably 0 or more and 8 or less, more preferably 0 or more and 4 or less, still more preferably 0 or more and 2 or less, and particularly preferably 0 or more and 1 or less.

  As the substituent, a halogen atom, which may be substituted with a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, and a cyano group, an isocyanato group, an ether group, a carbonate group, a carbonyl group, Examples thereof include a carboxy group, an alkoxycarbonyl group, an acyloxy group, a sulfonyl group, a phosphantriyl group, and a phosphoryl group. Of these, a halogen atom, an alkoxy group, an alkyl group, an alkenyl group, an alkynyl group, which may be substituted with a halogen atom, an isocyanato group, a cyano group, an ether group, a carbonyl group, an alkoxycarbonyl group, an acyloxy group More preferably an alkyl group not substituted with a halogen atom, a cyano group, and an ether group.

In formula (10), n ¹⁰¹ is preferably an integer of 1 or more, 3 or less, more preferably an integer of 1 or more and 2 or less, and even more preferably n ¹⁰¹ is 2.
The hydrocarbon group having 1 to 5 carbon atoms in A ^{15 to} A ²⁰ is a monovalent hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, and an aryl group;
And divalent hydrocarbon groups such as an alkylene group, an alkenylene group, an alkynylene group, and an arylene group. Of these, an alkyl group and an alkylene group are preferable, and an alkyl group is more preferable. As a specific example,
Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl An alkyl group having 1 to 5 carbon atoms such as a group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group;
Vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group An alkenyl group having 2 to 5 carbon atoms, such as a group;
Carbon such as ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group and 4-pentynyl group An alkynyl group of 2 or more and 5 or less;
Alkylene groups having 1 to 5 carbon atoms, such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group;
An alkenylene group having 2 to 5 carbon atoms, such as a vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group;
Examples thereof include alkynylene groups having 2 to 5 carbon atoms such as ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group. Of these, an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group is preferable, and an ethylene group, a trimethylene group, a tetramethylene group, and a pentane are more preferable. An alkylene group having 2 to 5 carbon atoms, such as a methylene group, and more preferably an alkylene group having 3 to 5 carbon atoms, such as a trimethylene group, a tetramethylene group, and a pentamethylene group.

The hydrogen atom, fluorine atom, or hydrocarbon group having 1 to 5 carbon atoms in A ^{15 to} A ²⁰ is a group in which a hydrogen atom, a fluorine atom, or the above substituent is combined with the hydrocarbon group having 1 to 5 carbon atoms. Preferably, it is a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms which does not have a substituent, and an alkylene group having an ether structure in which part of the carbon chain of the alkylene group is substituted with an ether group. More preferably a hydrogen atom.

  Examples of the compound represented by the formula (10) include the following compounds.

  Above all,

Etc. are preferred.

Is more preferable.
The cyclic compound which has a some ether bond may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios. The amount of the cyclic compound having a plurality of ether bonds (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, in 100% by mass of the electrolytic solution. More preferably, it is 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less. More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Especially preferably, it is 1.5 mass% or less, Most preferably, it is 1.0 mass% or less. Within the above range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

The mass ratio of the aromatic compound represented by the formula (I) and the cyclic compound having a plurality of ether bonds can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100. : 100, more preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005. : 100 to 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-3-11. Compound having isocyanuric acid skeleton
The electrolytic solution of the present invention can contain a compound having an isocyanuric acid skeleton. The compound having an isocyanuric acid skeleton is not particularly limited as long as it has an isocyanuric acid skeleton, but is preferably a compound represented by the following formula (11).

(Where
R ^{111 to} R ¹¹³ are each independently a carbon number composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom and a halogen atom. 1 or more and 12 or less organic group is represented. )
R ^{111 to} R ¹¹³ are not bonded to each other to form a ring.

  Here, an organic group having 1 to 12 carbon atoms composed of at least one atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom and a halogen atom; Means an organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom or a halogen atom in addition to an organic group composed of a carbon atom and a hydrogen atom. An organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom or a halogen atom is an organic group in which a part of the carbon atoms of the skeleton is substituted with these atoms, or these It is meant to include an organic group having a substituent composed of atoms.

R ^{111 to} R ¹¹³ are preferably a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and more preferably 1 carbon atom which may have a substituent. These are hydrocarbon groups of 5 or less.
Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups, alkoxy groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; carboxyl groups; alkoxycarbonyl groups; An alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group, preferably a halogen atom; an alkoxy group or an unsubstituted or halogen-substituted alkyl group; More preferably a halogen atom or an unsubstituted or halogen-substituted alkyl group, and still more preferably an unsubstituted alkyl group.

Further, preferably at least one of ^R 111 ^{to R 113} is a carbon - an organic group having a carbon unsaturated bond or a cyano group, more ^preferably, at least one carbon of R 111 ^{to R 113} - carbonless An organic group having a saturated bond.
The hydrocarbon group is preferably an alkyl group, an alkenyl group, an alkynyl group or an aryl group, more preferably an alkyl group or an alkenyl group.

Specific examples of the hydrocarbon group having 1 to 10 carbon atoms include
Alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group; vinyl group, 1-propenyl group, 2-propenyl group (allyl group) ), 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group and the like alkenyl groups;
Alkynyl such as ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group and 4-pentynyl group Group;
Aryl groups such as phenyl, tolyl, benzyl and phenethyl;
Etc.

  Of these, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, a cyclopropyl group, a cyclopentyl group, or a cyclohexyl group, or a vinyl group or 1-propenyl is preferable. Group, 2-propenyl group (allyl group), 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, etc. More preferably, methyl group, ethyl group, n-propyl group, n-butyl group, vinyl group, 1-propenyl group, 2-propenyl group (allyl group), 1-butenyl group, 2-butenyl group, 3 -It is a butenyl group, More preferably, they are an ethyl group, n-propyl group, and 2-propenyl group (allyl group).

  In addition, the C1-C10 hydrocarbon group which may have a substituent represents the group which combined the said substituent and the said C1-C10 hydrocarbon group, for example, Examples include 2-methylallyl group (methallyl group), 2-cyanoethyl group, 2-acryloyloxyethyl group, 2-methacryloyloxyethyl group, etc., preferably 2-methylallyl group (methallyl group), 2-acryloyloxyethyl group. And more preferably a 2-propenyl group (allyl group). However, a hydrocarbon group having 1 to 10 carbon atoms and having no substituent is preferable.

  As the compound used in the present invention, a compound represented by the formula (11) is used, and specific examples thereof include compounds having the following structure.

  Preferably, the compound of the following structures is mentioned.

  More preferably, the compound of the following structures is mentioned.

  Particularly preferred are compounds having the following structures.

  Most preferably, the compound of the following structure is mentioned.

  Among these most preferable compounds, compounds having the following structure are preferable from the viewpoint of the ability to form a negative electrode film.

There is no restriction | limiting in particular also in a manufacturing method regarding the compound which has an isocyanuric acid frame | skeleton, It is possible to select and manufacture a well-known method arbitrarily.
The compound represented by the compound having an isocyanuric acid skeleton may be used alone or in combination of two or more in any combination and ratio. The amount of the compound having an isocyanuric acid skeleton (total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably in 100% by mass of the electrolytic solution. 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.4% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Especially preferably, it is 1 mass% or less, Most preferably, it is 0.5 mass% or less. Within this range, the reduction reaction prevents the electrode reaction from being inhibited by excessively covering the negative electrode surface. In addition, since the action at the electrode interface proceeds more suitably, the battery characteristics can be optimized.

The mass ratio of the aromatic compound represented by the above formula (I) and the compound having an isocyanuric acid skeleton can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100. More preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100. ~ 0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-4. Electrolyte There is no restriction | limiting in particular in electrolyte, What is well-known as electrolyte can be used arbitrarily. In the case of a lithium secondary battery, a lithium salt is usually used. Specifically, inorganic lithium salts such as LiPF ₆ , LiBF _4, LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , LiWF ₇ ; lithium tungstates such as LiWOF ₅ ; HCO ₂ Li, CH ₃ CO ₂ Li, _{CH 2 FCO 2 Li, CHF 2} CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 Carboxylic acid lithium salts such as CF ₂ CO ₂ Li; FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF _{3 CF 2 CF 2 SO 3 Li,} CF 3 CF 2 CF 2 CF 2 SO 3 sulfonate lithium salt such as Li _{; LiN (FCO) 2, LiN} (FCO) (FSO 2), LiN (FSO 2) 2, LiN (FSO 2) (CF 3 SO 2), LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO _{2) 2,} lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2) lithium imide such as Salts; lithium methide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ ; lithium (such as lithium bis (malonato) borate, lithium difluoro (malonato) borate) Malonato) borate salts; lithium tris (malonato) phosphate, lithium difluorobis (malonato) Sufeto, lithium (Maronato) phosphate salts such as lithium tetrafluoro (Maronato) phosphate; _{other, LiPF 4 (CF 3) 2} , LiPF 4 (C 2 F 5) 2, LiPF 4 (CF 3 SO 2) 2, LiPF 4 (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ ( Fluorine-containing organic lithium salts such as CF ₃ SO ₂ ) ₂ and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ; Lithium oxalate borate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
And lithium oxalate phosphate salts such as lithium tetrafluorooxalato phosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate; and the like.

Among them, LiPF ₆ , LiSbF ₆ , LiTaF ₆ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _3, lithium difluorooxalatoborate, lithium Bis (oxalato) borate, lithium difluorobis (oxalato) phosphate, etc. Rate charge and discharge characteristics, high-temperature storage characteristics, particularly preferred from the viewpoint that an effect of improving the cycle characteristics and the like.

  The concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolyte solution is in a good range, and good battery performance is ensured. In view of this, the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, still more preferably 0.5 mol / L or more, and preferably Is 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less. If it is this range, since there is not too little lithium which is a charged particle and a viscosity can be made into an appropriate range, it will become easy to ensure favorable electrical conductivity.

  When two or more electrolytes are used in combination, at least one of them is preferably a salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate. Of these, lithium salts are preferred. The salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate can be 0.01% by mass or more, preferably 0.1% by mass. % Or more, and can be 20% by mass or less, preferably 10% by mass or less.

The electrolyte preferably contains one or more selected from the group consisting of monofluorophosphates, difluorophosphates, borates, oxalates and fluorosulfonates and one or more other salts. Other salts include the lithium salts exemplified above, and in particular LiPF ₆ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , and LiPF ₃ (C ₂ F ₅ ) ₃ are preferable, and LiPF ₆ is more preferable. The other salt may be 0.01% by mass or more, preferably 0.1% by mass or more, and 20% by mass from the viewpoint of ensuring an appropriate balance between the conductivity and viscosity of the electrolytic solution. Or less, preferably 15% by mass or less, more preferably 10% by mass or less.

  The total amount of the electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, still more preferably 0.5 mol / L or more in the non-aqueous electrolyte from the viewpoint of ensuring good battery performance. Moreover, it is preferably 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less, and particularly preferably 1.5 mol / L or less.

1-4-1. Monofluorophosphate, difluorophosphate Monofluorophosphate and difluorophosphate are not particularly limited as long as each salt has at least one monofluorophosphate or difluorophosphate structure in the molecule. In the electrolytic solution of the present invention, the volume after the initial charge / discharge of the battery is obtained by using the aromatic compound represented by the above formula (I) and at least one selected from monofluorophosphate and difluorophosphate. The change is remarkably suppressed, and the safety during overcharge can be further improved. In addition, the combined use can reduce the initial irreversible capacity of the battery and improve the discharge storage characteristics. At the same time, the battery can have excellent high temperature cycling characteristics.

The counter cation in the monofluorophosphate and difluorophosphate is not particularly limited, and lithium, sodium, potassium, magnesium, calcium, NR ¹²¹ R ¹²² R ¹²³ R ¹²⁴ (wherein R ^{121 to} R ¹²⁴ are independently And ammonium represented by a hydrogen atom or an organic group having 1 to 12 carbon atoms. The organic group having 1 to 12 carbon atoms represented by R ^{121 to} R ¹²⁴ of the ammonium is not particularly limited. For example, the organic group may be substituted with a halogen atom, an alkyl group, a halogen atom, or an alkyl group. A cycloalkyl group that may be substituted, an aryl group that may be substituted with a halogen atom or an alkyl group, a nitrogen-containing heterocyclic group that may have a substituent, and the like. Among these, R ^{121 to} R ¹²⁴ are preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, a nitrogen atom-containing heterocyclic group, or the like. As a counter cation, lithium, sodium, and potassium are preferable, and lithium is particularly preferable.

  Examples of monofluorophosphate and difluorophosphate include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. Lithium monofluorophosphate and lithium difluorophosphate are preferred, and lithium difluorophosphate is more preferred.

Monofluorophosphate and difluorophosphate may be used singly or in combination of two or more in any combination and ratio.
One or more amounts selected from monofluorophosphate and difluorophosphate (total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, More preferably, it is 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and can be 5% by mass or less, preferably 3% by mass or less. More preferably, it is 2 mass% or less, More preferably, it is 1.5 mass% or less, Most preferably, it is 1 mass% or less. Within this range, the effect of improving the initial irreversible capacity is remarkably exhibited.

  The mass ratio of one or more selected from the aromatic compound represented by the above formula (I), the monofluorophosphate and the salt can be 0.0001: 100 to 1000000: 100, preferably 0.0005. : 100 to 100: 100, more preferably 0.001: 100 to 10: 100, still more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably Is 0.005: 100-0.1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-4-2. Borate Borate is not particularly limited as long as it is a salt having at least one boron atom in the molecule. However, what corresponds to oxalate is 1-4-2. Not borate but 1-4-3 described later. Included in oxalate.
In the electrolytic solution of the present invention, by using the aromatic compound represented by the formula (I) and borate in combination, the volume change after the initial charge / discharge is suppressed, and a battery having good high-temperature cycle characteristics is obtained. It is done. At the same time, the battery can have good overcharge safety.

Examples of the counter cation in the borate include lithium, sodium, potassium, magnesium, calcium, rubidium, cesium, and barium, and lithium is particularly preferable.
As the borate, a lithium salt is preferable, and a lithium borate salt can also be suitably used. For example, LiBF ₄ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) _{2 and the} like. Among these, LiBF ₄ is more preferable because it has an effect of improving initial charge / discharge efficiency, high-temperature cycle characteristics, and the like.

A borate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of borate (the total amount in the case of two or more) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably Is 0.3% by mass or more, particularly preferably 0.5% by mass or more, and can be 10.0% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass. % Or less, more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less. Within this range, side reactions of the battery negative electrode are suppressed and resistance is hardly increased.

  The mass ratio of the aromatic compound represented by the above formula (I) and borate can be 0.0001: 100-1000000: 100, preferably 0.0005: 100-100: 100, more preferably Is 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, and most preferably 0.005: 100 to 0.100. 1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-4-3. Oxalate The oxalate is not particularly limited as long as it is a compound having at least one oxalic acid structure in the molecule. The battery using the electrolytic solution of the present invention containing oxalate has a small initial charge / discharge volume change rate, and the swelling of the battery after high-temperature cycle is suppressed. The oxalate is represented by the following formula (12). Preferred metal salts are: This salt is a salt having an oxalato complex as an anion.

(Where
M ¹ is an element selected from the group consisting of Group 1, Group 2 and aluminum (Al) in the periodic table;
M ² is an element selected from the group consisting of transition metals, groups 13, 14 and 15 of the periodic table,
R ⁹¹ is a group selected from the group consisting of halogen, an alkyl group having 1 to 11 carbon atoms, and a halogen-substituted alkyl group having 1 to 11 carbon atoms,
a and b are positive integers;
c is 0 or a positive integer;
d is an integer of 1-3. )
M ¹ is preferably lithium, sodium, potassium, magnesium, or calcium, and particularly preferably lithium, from the viewpoint of battery characteristics when the electrolytic solution of the present invention is used for a lithium secondary battery.

M ² is particularly preferably boron or phosphorus from the viewpoint of electrochemical stability when used in a lithium secondary battery.
^Examples of R ⁹¹ include fluorine, chlorine, methyl group, trifluoromethyl group, ethyl group, pentafluoroethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, and the like. A trifluoromethyl group is preferred.

Examples of the metal salt represented by the formula (12) include the following.
Lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
Lithium oxalate phosphate salts such as lithium tetrafluorooxalato phosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate;
Of these, lithium bis (oxalato) borate and lithium difluorobis (oxalato) phosphate are preferred, and lithium bis (oxalato) borate is more preferred.

One oxalate may be used alone, or two or more oxalates may be used in any combination and ratio.
The amount of oxalate (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably. Is 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably It is 2% by mass or less, particularly preferably 1% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

The mass ratio of the aromatic compound represented by the above formula (I) and the oxalate can be 0.0001: 100-1000000: 100, preferably 0.0005: 100-100: 100, more preferably Is 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, and most preferably 0.005: 100 to 0.100. 1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-4-4. Fluorosulfonate The fluorosulfonate is not particularly limited as long as it is a salt having at least one fluorosulfonic acid structure in the molecule. In the electrolytic solution of the present invention, by using the aromatic compound represented by the above formula (II) and the fluorosulfonate together, the initial irreversible capacity of the battery can be reduced and the high-temperature cycle characteristics can be improved. This battery also ensures safety during overcharge.

The counter cation in the fluorosulfonate is not particularly limited, and lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ¹³¹ R ¹³² R ¹³³ R ¹³⁴ (wherein R ^{131 to} R ¹³⁴ are: Each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms). For illustrative and preferred examples of R ¹³¹ to R ¹³⁴ may, ^R 131 ^{to R 134} in the 1-2-2 is applied. As a counter cation, lithium, sodium, and potassium are preferable, and lithium is particularly preferable.

  Examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, and lithium fluorosulfonate is preferable. An imide salt having a fluorosulfonic acid structure such as lithium bis (fluorosulfonyl) imide can also be used as the fluorosulfonic acid salt.

A fluorosulfonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The content of fluorosulfonate (total amount in the case of two or more types) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, More preferably, it is 0.3% by mass or more, particularly preferably 0.5% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, Preferably it is 2 mass% or less, Most preferably, it is 1 mass% or less. Within this range, there are few side reactions in the battery and resistance is hardly increased.

  The mass ratio of the aromatic compound represented by the above formula (I) and the fluorosulfonate can be 0.0001: 100 to 1000000: 100, preferably 0.0005: 100 to 100: 100, Preferably 0.001: 100 to 10: 100, more preferably 0.002: 100 to 1: 100, particularly preferably 0.003: 100 to 0.5: 100, most preferably 0.005: 100 to 0. .1: 100. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-5. Non-aqueous solvent
There is no restriction | limiting in particular about the nonaqueous solvent in this invention, It is possible to use a well-known organic solvent. Specific examples include cyclic carbonates having no fluorine atom, chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, and sulfone compounds.

In this specification, the volume of the non-aqueous solvent is a measured value at 25 ° C., but the measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.
1-5-1. The cyclic carbonate which does not have a fluorine atom As a cyclic carbonate which does not have a fluorine atom, the cyclic carbonate which has a C2-C4 alkylene group is mentioned.

Specific examples of the cyclic carbonate having an alkylene group having 2 to 4 carbon atoms and having no fluorine atom include ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.
The cyclic carbonate which does not have a fluorine atom may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  The blending amount of the cyclic carbonate not having a fluorine atom is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. However, the blending amount when one kind is used alone is 100% by volume of the nonaqueous solvent. Among them, the content is 5% by volume or more, more preferably 10% by volume or more. By setting this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte is avoided, and the high current discharge characteristics, stability against the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery are in a good range. And it will be easier. Moreover, it is 95 volume% or less, More preferably, it is 90 volume% or less, More preferably, it is 85 volume% or less. By setting it as this range, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the load characteristics of the non-aqueous electrolyte battery are easily set in a favorable range.

1-5-2. Chain carbonate As the chain carbonate, a chain carbonate having 3 to 7 carbon atoms is preferable, and a dialkyl carbonate having 3 to 7 carbon atoms is more preferable.
Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl n-propyl carbonate, n-butyl methyl carbonate, isobutyl methyl carbonate, tert -Butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, tert-butyl ethyl carbonate and the like.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferable. is there.
Further, chain carbonates having a fluorine atom (hereinafter sometimes referred to as “fluorinated chain carbonate”) can also be suitably used.

The number of fluorine atoms contained in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or may be bonded to different carbons.
Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate and derivatives thereof, fluorinated ethyl methyl carbonate and derivatives thereof, and fluorinated diethyl carbonate and derivatives thereof.

Fluorinated dimethyl carbonate and derivatives thereof include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate, and the like. It is done.
Fluorinated ethyl methyl carbonate and derivatives thereof include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2 -Trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate, etc. are mentioned.

  Fluorinated diethyl carbonate and its derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2- Trifluoroethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2, Examples include 2,2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, and the like.

  A chain carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. The blending amount of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the viscosity of the non-aqueous electrolyte solution is set in an appropriate range, the decrease in ionic conductivity is suppressed, and the large current discharge characteristics of the non-aqueous electrolyte battery are easily set in a favorable range. Further, the chain carbonate is preferably 90% by volume or less, more preferably 85% by volume or less, in 100% by volume of the nonaqueous solvent. By setting the upper limit in this way, it is easy to avoid a decrease in electrical conductivity resulting from a decrease in dielectric constant of the nonaqueous electrolyte solution, and to make the large current discharge characteristics of the nonaqueous electrolyte solution battery in a favorable range.

1-5-3. Cyclic carboxylic acid ester As the cyclic carboxylic acid ester, those having 3 to 12 carbon atoms are preferable.
Specific examples include gamma butyrolactone, gamma valerolactone, gamma caprolactone, epsilon caprolactone, and the like. Among these, gamma butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

A cyclic carboxylic acid ester may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of the cyclic carboxylic acid ester is usually 5% by volume or more, more preferably 10% by volume or more, in 100% by volume of the non-aqueous solvent. If it is this range, it will become easy to improve the electrical conductivity of a non-aqueous electrolyte solution, and to improve the large current discharge characteristic of a non-aqueous electrolyte battery. Moreover, the compounding quantity of cyclic carboxylic acid ester becomes like this. Preferably it is 50 volume% or less, More preferably, it is 40 volume% or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

1-5-4. Ether compound As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms in which part of hydrogen may be substituted with fluorine is preferable. As the chain ether having 3 to 10 carbon atoms,
Diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2, 2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2-
Trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoroethyl) ) Ether, ethyl-n-propyl ether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-tetra Fluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propylether, (2-fluoroethyl) (3-fluoro- n-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3, -Tetrafluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propyl ether (2,2,2-trifluoroethyl) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3 -Pentafluoro-n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether , (1,1,2,2-tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3, 3-tetrafluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propylether , (N-propyl) (3-fluoro-n-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3, 3-tetrafluoro-n-propyl) ether, (n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, (3 -Fluoro-n-propyl ) (3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n) -Propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro- n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3,3-pentafluoro- n-propyl) ether, di (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2,2,3,3 3-pentafluoro-n-propyl) ether, di ( , 2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-trifluoro) Ethoxy) methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2,2-trifluoroethoxy) methane, ethoxy (1, 1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) methane, (2-fluoroethoxy) (1,1 , 2,2-Tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2 2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2- Fluoroethoxy) ethane, methoxy (2,2,2-trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy ( 2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2-fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2- Trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane , Di (2,2,2-trifluoroethoxy) ethane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2) -Tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,4-dioxane, and the like, and fluorinated compounds thereof.
Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether have high solvating ability to lithium ions and improve ion dissociation. Of these, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferable because they have low viscosity and give high ionic conductivity.

An ether compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The compounding amount of the ether compound is usually in 100% by volume of the non-aqueous solvent, preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 15% by volume or more, and preferably 70% by volume or less. More preferably, it is 60 volume% or less, More preferably, it is 50 volume% or less. If it is this range, it is easy to ensure the improvement effect of the lithium ion dissociation degree of chain ether, and the improvement of the ionic conductivity derived from a viscosity fall. It is easy to avoid a situation where the capacity is reduced due to co-insertion.

1-5-5. Sulfone compound As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.
Examples of the cyclic sulfone having 3 to 6 carbon atoms include trimethylene sulfones, tetramethylene sulfones and hexamethylene sulfones which are monosulfone compounds;
Examples include disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones.

Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.
As the sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter sometimes referred to as “sulfolanes” including sulfolane) are preferable. The sulfolane derivative is preferably one in which one or more hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group.

Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methyl sulfolane, 2- Trifluoromethyl sulfolane, 3-trifluoromethyl sulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3
-(Trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane, 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ionic conductivity and high input / output characteristics. .

In addition, as the chain sulfone having 2 to 6 carbon atoms,
Dimethylsulfone, ethylmethylsulfone, diethylsulfone, n-propylmethylsulfone, n-propylethylsulfone, di-n-propylsulfone, isopropylmethylsulfone, isopropylethylsulfone, diisopropylsulfone, n-butylmethylsulfone, n-butylethyl Sulfone, tert-butylmethylsulfone, tert-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, trifluoroethylmethylsulfone, pentafluoro Ethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone Perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, tri Fluoromethyl-n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoro Ethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-tert-butyl sulfone, pen Trifluoroethyl -n- butyl sulfone, pentafluoroethyl -tert- butyl sulfone, and the like.

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone Trifluoroethyl-n-butylsulfone, trifluoroethyl-tert-butylsulfone, trifluoromethyl-n-butylsulfone, trifluoromethyl-tert-butylsulfone, etc. have high ionic conductivity and high input / output characteristics. preferable.

A sulfone type compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The compounding amount of the sulfone compound is usually 0.3% by volume or more, more preferably 1% by volume or more, still more preferably 5% by volume or more in 100% by volume of the non-aqueous solvent, and preferably 40%. Volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less. Within this range, durability improvement effects such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be set to an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging an aqueous electrolyte battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

1-5-6. Composition of non-aqueous solvent As the non-aqueous solvent of the present invention, one of the above-exemplified non-aqueous solvents may be used alone, or two or more thereof may be used in any combination and ratio.
For example, one preferred combination of non-aqueous solvents is a combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate.

  Among them, the total of the cyclic carbonate having no fluorine atom and the chain carbonate in the nonaqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, and still more preferably 90% by volume or more, The ratio of the cyclic carbonate having no fluorine atom to the total of the cyclic carbonate and the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more. Preferably it is 50 volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less, Most preferably, it is 25 volume% or less.

When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent may be improved.
For example, as a preferable combination of a cyclic carbonate having no fluorine atom and a chain carbonate,
Ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate and diethyl carbonate and ethyl methyl carbonate, ethylene carbonate And dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  Among the combinations of cyclic carbonates and chain carbonates having no fluorine atom, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable, in particular, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, Those containing ethylene carbonate, symmetric chain carbonates and asymmetric chain carbonates such as ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate have cycle characteristics and large current discharge characteristics. This is preferable because of a good balance.

Among them, the asymmetric chain carbonate is preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
A combination in which propylene carbonate is further added to the combination of these ethylene carbonates and chain carbonates is also a preferable combination.
In the case of containing propylene carbonate, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, particularly preferably 95: 5 to 50:50. Furthermore, the proportion of propylene carbonate in the entire non-aqueous solvent is preferably 0.1% by volume or more, more preferably 1% by volume or more, still more preferably 2% by volume or more, and preferably 20% by volume or less, more preferably Is 8% by volume or less, more preferably 5% by volume or less.

It is preferable to contain propylene carbonate in this concentration range because the low temperature characteristics may be further improved while maintaining the combination characteristics of ethylene carbonate and chain carbonate.
When dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 25% by volume or more. Preferably it is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less. The load characteristics of the battery may be improved.

Above all, it contains dimethyl carbonate and ethyl methyl carbonate, and by increasing the content ratio of dimethyl carbonate over the content ratio of ethyl methyl carbonate, the electric conductivity of the electrolyte can be maintained, but the battery characteristics after high temperature storage are improved. This is preferable.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate in all non-aqueous solvents (dimethyl carbonate / ethyl methyl carbonate) is 1.1 or more in terms of improving the electric conductivity of the electrolyte and improving the battery characteristics after storage. Is preferably 1.5 or more, more preferably 2.5 or more. The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics at low temperatures.

In the combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate, a cyclic carboxylic acid ester, a chain carboxylic acid ester, a cyclic ether, a chain ether, a sulfur-containing organic solvent, You may mix other solvents, such as a phosphorus organic solvent and an aromatic fluorine-containing solvent.
1-6. Auxiliary Agent In the electrolyte battery of the present invention, an auxiliary agent may be appropriately used in addition to the above compound depending on the purpose. Examples of the auxiliary agent include auxiliary agents shown below.

A known auxiliary agent can be used for the electrolytic solution of the present invention. As auxiliary agents, carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride Carboxylic anhydrides such as diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] Spiro compounds such as undecane; sulfur-containing compounds such as N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; trimethyl phosphite, triethyl phosphite, triphenyl phosphite, Trimethyl phosphate, triethyl phosphate, triphosphate Phosphorus-containing compounds such as phenyl, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, ethyl diethylphosphonoacetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide; Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide; heptane, octane, Hydrocarbon compounds such as nonane, decane, cycloheptane; 2-propynyl 2- (diethoxyphosphoryl) acetate, 1-methyl-2-propynyl 2- (diethoxyphosphoryl) acetate, 1,1-dimethyl-2-propiyl Nyl 2- (diethoxyphosphoryl) acetate, pentafluorophenyl methanesulfonate, pentafluorophenyl trifluoromethanesulfonate, pentafluorophenyl acetate, pentafluorophenyl trifluoroacetate, methyl pentafluorophenyl carbonate, 2- (methanesulfonyloxy) propionic acid 2-propynyl, 2-methyl 2- (methanesulfonyloxy) propionate, 2-ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl methanesulfonyloxyacetate, 2-methylmethanesulfonyloxyacetate, methanesulfonyloxyacetic acid 2-ethyl, lithium ethyl methyloxycarbonylphosphonate, lithium ethyl ethyloxycarbonylphosphonate, lithium ethyl 2-propynyl Oxycarbonylphosphonate, lithium ethyl 1-methyl-2-propynyloxycarbonylphosphonate, lithium ethyl 1,1-dimethyl-2-propynyloxycarbonylphosphonate, lithium methyl sulfate, lithium ethyl sulfate, lithium 2-propynyl sulfate, lithium 1-methyl 2-propynyl sulfate, lithium 1,1-dimethyl-2-propynyl sulfate, lithium 2,2,2-trifluoroethyl sulfate, methyl trimethylsilyl sulfate, ethyl trimethylsilyl sulfate, 2-propynyl trimethylsilyl sulfate, dilithium ethylene disulfate, 2- Butyne-1,4-diyl dimethanesulfonate, 2-butyne-1,4-diyl di Tansulfonate, 2-butyne-1,4-diyl diformate, 2-butyne-1,4-diyl diacetate, 2-butyne-1,4-diyl dipropionate, 4-hexadiyne-1,6-diyl dimethanesulfonate, 2-propynyl methanesulfonate, 1-methyl-2-propynyl methanesulfonate, 1,1-dimethyl-2-propynyl methanesulfonate, 2-propynyl ethanesulfonate, 2-propynyl vinylsulfonate, methyl 2-propynyl carbonate, ethyl 2-propynyl Carbonate, bis (2-propynyl)
Carbonate, methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, bis (2-propynyl) oxalate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, di (2-propynyl) glutarate, 2,2-dioxide -1,2-oxathiolan-4-yl acetate, 2,2-dioxide-1,2-oxathiolan-4-yl propionate, 5-methyl-1,2-oxathiolan-4-one 2,2-dioxide, 5, 5-Dimethyl-1,2-oxathiolane-4-one 2,2-dioxide, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2- (2-isocyanatoethoxy) ethyl Acry 2- (2-isocyanatoethoxy) ethyl methacrylate, 2- (2-isocyanatoethoxy) ethyl crotonate, 2-allyl succinic anhydride, 2- (1-penten-3-yl) succinic anhydride, 2 -(1-hexen-3-yl) succinic anhydride, 2- (1-hepten-3-yl) succinic anhydride, 2- (1-octen-3-yl) succinic anhydride, 2- (1-nonene) -3-yl) succinic anhydride, 2- (3-buten-2-yl) succinic anhydride, 2- (2-methylallyl) succinic anhydride, 2- (3-methyl-3-buten-2-yl) Examples thereof include succinic anhydride. These may be used individually by 1 type, or may use 2 or more types together. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved.

  The amount of the other auxiliary agent is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The other auxiliary agent is preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte solution. Within this range, the effects of other auxiliaries can be sufficiently exhibited, and it is easy to avoid a situation in which battery characteristics such as high-load discharge characteristics deteriorate. The blending amount of other auxiliaries is more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, more preferably 3% by mass or less, still more preferably 1% by mass or less. .

2. Battery Configuration The electrolyte battery of the present invention is suitable for use as an electrolyte for secondary batteries, for example, lithium secondary batteries, among non-aqueous electrolyte batteries. Hereinafter, a non-aqueous electrolyte battery using the electrolytic solution of the present invention will be described.
The electrolyte battery of the present invention can take a known structure, and typically includes a negative electrode and a positive electrode capable of occluding and releasing ions (for example, lithium ions), and the above-described electrolyte of the present invention. .

2-1. Negative electrode The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like. These may be used alone or in combination of two or more.

<Negative electrode active material>
Examples of the negative electrode active material include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like.
As a carbonaceous material used as a negative electrode active material,
(1) natural graphite,
(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous material and an artificial graphite material at least once in the range of 400 to 3200 ° C;
(3) a carbonaceous material in which the negative electrode active material layer is composed of at least two kinds of carbonaceous materials having different crystallinity and / or has an interface in contact with the different crystalline carbonaceous materials,
(4) A carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two different orientations and / or has an interface in contact with the carbonaceous materials having different orientations,
Is preferably a good balance between initial irreversible capacity and high current density charge / discharge characteristics. Moreover, the carbonaceous materials (1) to (4) may be used singly or in combination of two or more in any combination and ratio.

  The artificial carbonaceous material and artificial graphite material of (2) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, and those obtained by oxidizing these pitches, needle coke, pitch coke and Carbon materials that are partially graphitized, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials and their carbides, or carbonizable organic materials are benzene, toluene, xylene, quinoline And a solution dissolved in a low-molecular organic solvent such as n-hexane, and carbides thereof.

  As an alloy material used as the negative electrode active material, as long as lithium can be occluded / released, lithium alone, simple metals and alloys forming lithium alloys, or oxides, carbides, nitrides, silicides, sulfides thereof Any of compounds such as products or phosphides may be used and is not particularly limited. The single metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / metalloid elements (that is, excluding carbon), more preferably aluminum, silicon and tin (hereinafter referred to as “ Simple metals) and alloys or compounds containing these atoms (sometimes abbreviated as “specific metal elements”). These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  As the negative electrode active material having at least one kind of atom selected from the specific metal element, a single metal element of any one specific metal element, an alloy composed of two or more specific metal elements, one type or two or more specific metal elements Other alloys composed of one or more metal elements, and compounds containing one or more specific metal elements, and oxides, carbides, nitrides, silicides, sulfides or phosphorus of the compounds And complex compounds such as compounds. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

  In addition, a compound in which these complex compounds are complexly bonded to several kinds of elements such as a simple metal, an alloy, or a nonmetallic element is also included. Specifically, for example, in silicon and tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. For example, in the case of tin, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not operate as a negative electrode, and a nonmetallic element may be used. it can.

Among these negative electrode active materials, since the capacity per unit mass when a battery is made is large, a single metal of any one specific metal element, an alloy of two or more specific metal elements, an oxide of a specific metal element In particular, carbides, nitrides and the like are preferable, and silicon and / or tin simple metals, alloys, oxides, carbides, nitrides, and the like are particularly preferable from the viewpoint of capacity per unit mass and environmental load.

  The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but a material containing titanium and lithium is preferable from the viewpoint of high current density charge / discharge characteristics, A lithium-containing composite metal oxide material containing titanium is more preferable, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as “lithium titanium composite oxide”). That is, it is particularly preferable to use a lithium titanium composite oxide having a spinel structure in a negative electrode active material for a non-aqueous electrolyte battery because the output resistance is greatly reduced.

In addition, lithium or titanium of the lithium titanium composite oxide is at least selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. Those substituted with one kind of element are also preferred.
The metal oxide is a lithium titanium composite oxide represented by the formula (A), and in the formula (A), 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, 0 ≦ It is preferable that z ≦ 1.6 because the structure upon doping and dedoping of lithium ions is stable.

_{Li x Ti y M z O 4} (A)
[In the formula (A), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. ]
Among the compositions represented by the above formula (A),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
This structure is particularly preferable because of a good balance of battery performance.

Particularly preferred representative compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O in (c). ₄ . As for the structure of Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.
<Physical properties of carbonaceous materials>
When using a carbonaceous material as a negative electrode active material, it is desirable to have the following physical properties.

(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction by the Gakushin method of carbonaceous materials is preferably 0.335 nm or more, and is usually 0.360 nm or less. 350 nm or less is preferable, and 0.345 nm or less is more preferable. Further, the crystallite size (Lc) of the carbonaceous material obtained by X-ray diffraction by the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(Volume-based average particle size)
The mass-based average particle diameter of the carbonaceous material is a volume-based average particle diameter (median diameter) determined by a laser diffraction / scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and 7 μm. The above is particularly preferable, and is usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably 25 μm or less.

If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to loss of initial battery capacity. On the other hand, when the above range is exceeded, when an electrode is produced by coating, an uneven coating surface tends to be formed, which may be undesirable in the battery production process.
The volume-based average particle size is measured by dispersing the carbon powder in a 0.2% by mass aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This is carried out using a meter (LA-700 manufactured by Horiba Ltd.).

(Raman R value, Raman half width)
The Raman R value of the carbonaceous material is a value measured using an argon ion laser Raman spectrum method, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1.5 or less, preferably 1.2 or less, more preferably 1 or less, and particularly preferably 0.5 or less.

Further, the Raman half-width in the vicinity of 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and usually 100 cm ⁻¹ or less, and 80 cm ⁻¹ or less. Preferably, 60 cm ⁻¹ or less is more preferable, and 40 cm ⁻¹ or less is particularly preferable.
The Raman R value and the Raman half width are indices indicating the crystallinity of the surface of the carbonaceous material, but the carbonaceous material has appropriate crystallinity from the viewpoint of chemical stability, and Li enters through charge and discharge. It is preferable that the crystallinity is such that the sites between the layers are not lost, that is, the charge acceptability is not lowered. In the case where the density of the negative electrode is increased by press after applying to the current collector, it is preferable to take account of this because crystals tend to be oriented in a direction parallel to the electrode plate. When the Raman R value or the Raman half width is in the above range, a suitable film can be formed on the negative electrode surface to improve the storage characteristics, cycle characteristics, and load characteristics, and the efficiency associated with the reaction with the nonaqueous electrolyte solution Reduction and gas generation can be suppressed.

The measurement of the Raman spectrum, using a Raman spectrometer (manufactured by JASCO Corporation Raman spectrometer), the sample is naturally dropped into the measurement cell and filled, and while irradiating the sample surface in the cell with argon ion laser light, This is done by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity IIA of the peak PA around 1580 cm ^-1, and measuring the intensity IIB of the peak PB around 1360 cm ^-1, and calculates the intensity ratio R (R = IIB / IIA) .

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half-width analysis: Background processing ・ Smoothing processing: Simple average, 5 points of convolution (BET specific surface area)
BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · ^{g -1} or more, 0.7 m ² · ^{g -1} or more, 1. 0 m ² · ^{g -1} or more, and particularly preferably 1.5 m ² · ^{g -1} or more, generally not more than 100 m ² · ^{g -1,} preferably ^{25 m} 2 · ^{g -1} or less, 15 m ² · g ^-1 more preferably less, ^{10 m} 2 · ^{g -1} or less are especially preferred.

When the value of the BET specific surface area is in the above range, precipitation of lithium on the electrode surface can be suppressed, while gas generation due to reaction with the non-aqueous electrolyte can be suppressed.
The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately prepared so that the value of the relative pressure is 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used.

(Roundness)
When the circularity is measured as the degree of the sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”, and is theoretical when the circularity is 1. Become a true sphere. The circularity of the particles having a particle size of 3 to 40 μm in the range of the carbonaceous material is desirably closer to 1, and is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. As the high current density charge / discharge characteristics are larger, the filling property is improved and the resistance between the particles can be suppressed as the circularity is larger, so that the high current density charge / discharge characteristics are improved. Therefore, it is preferable that the circularity is as high as the above range.

  The circularity is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample was dispersed in a 0.2% by mass aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. The detection range is specified as 0.6 to 400 μm, and the particle size is measured in the range of 3 to 40 μm.

  The method for improving the circularity is not particularly limited, but a sphere-shaped sphere is preferable because the shape of the interparticle void when the electrode body is formed is preferable. Examples of spheroidizing treatment include a method of mechanically approaching a sphere by applying a shearing force and a compressive force, a mechanical / physical processing method of granulating a plurality of fine particles by the binder or the adhesive force of the particles themselves, etc. Is mentioned.

(Tap density)
The tap density of the carbonaceous material is usually 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and more preferably 1 g · cm ⁻³ or more. Particularly preferable, 2 g · cm ⁻³ or less is preferable, 1.8 g · cm ⁻³ or less is more preferable, and 1.6 g · cm ⁻³ or less is particularly preferable. When the tap density is in the above range, battery capacity can be ensured and increase in resistance between particles can be suppressed.

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the mass at that time and the mass of the sample.
(Orientation ratio)
The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. When the orientation ratio is in the above range, excellent high-density charge / discharge characteristics can be ensured. The upper limit of the above range is the theoretical upper limit value of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. Set the molded body obtained by filling 0.47 g of the sample into a molding machine with a diameter of 17 mm and compressing it with 58.8MN · m ^{-2 so} that it is flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the (110) diffraction and (004) diffraction peak intensities of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree / measurement range and step angle / measurement time:
(110) face: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) face: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds (aspect ratio (powder))
The aspect ratio of the carbonaceous material is usually 1 or more and usually 10 or less, preferably 8 or less, and more preferably 5 or less. Within the above range, streaking during electrode plate formation is suppressed, and more uniform coating is possible, so that excellent high current density charge / discharge characteristics can be ensured. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the carbonaceous material.

  The aspect ratio is measured by magnifying and observing the carbonaceous material particles with a scanning electron microscope. Carbonaceous material particles when three-dimensional observation is performed by selecting arbitrary 50 graphite particles fixed to the end face of a metal having a thickness of 50 μm or less and rotating and tilting the stage on which the sample is fixed. The longest diameter A and the shortest diameter B orthogonal thereto are measured, and the average value of A / B is obtained.

<Configuration and production method of negative electrode>
Any known method can be used for producing the electrode as long as the effects of the present invention are not significantly impaired. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to a negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.

In the case of using an alloy-based material, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a technique such as vapor deposition, sputtering, or plating is also used.
(Current collector)
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.

  In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, and a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.

The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less, from the viewpoint of securing battery capacity and handling properties.
(Thickness ratio between current collector and negative electrode active material layer)
The ratio of the thickness of the current collector to the negative electrode active material layer is not particularly limited, but the value of “(the thickness of the negative electrode active material layer on one side immediately before the nonaqueous electrolyte injection) / (thickness of the current collector)” However, 150 or less is preferable, 20 or less is more preferable, 10 or less is particularly preferable, 0.1 or more is preferable, 0.4 or more is further preferable, and 1 or more is particularly preferable. When the ratio of the thickness of the current collector to the negative electrode active material layer is in the above range, battery capacity can be secured and heat generation of the current collector during high current density charge / discharge can be suppressed.

(Binder)
The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used during electrode production.
Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, Rubber polymers such as NBR (acrylonitrile / butadiene rubber) and ethylene / propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate , Soft resinous polymers such as ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, etc. And a polymer composition having ion conductivity of alkali metal ions (particularly lithium ions). These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10 mass% or less is still more preferable, and 8 mass% or less is especially preferable. When the ratio of the binder to the negative electrode active material is within the above range, the battery capacity and the strength of the negative electrode can be sufficiently secured.

  In particular, when a rubbery polymer typified by SBR is contained as a main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0 .6% by mass or more is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Moreover, when the main component contains a fluorine-based polymer typified by polyvinylidene fluoride, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. Preferably, it is usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as necessary. Alternatively, either an aqueous solvent or an organic solvent may be used.
Examples of the aqueous solvent include water and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N- Examples include dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like.

In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the thickener and slurry it using a latex such as SBR. In addition, these solvent may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.
(Thickener)
A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, when using a thickener, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Moreover, it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is still more preferable. When the ratio of the thickener to the negative electrode active material is in the above range, it is possible to suppress a decrease in battery capacity and an increase in resistance, and it is possible to ensure good coatability.

(Electrode density)
The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more, and 1.2 g · cm ⁻³ or more. but more preferably, particularly preferably 1.3 g · ^{cm -3} or more, preferably 2.2 g · ^{cm -3} or less, more preferably 2.1 g · ^{cm -3} or less, 2.0 g · ^{cm -3} or less Further preferred is 1.9 g · cm ⁻³ or less. When the density of the negative electrode active material existing on the current collector is in the above range, the negative electrode active material particles are prevented from being destroyed, and an increase in initial irreversible capacity or to the vicinity of the current collector / negative electrode active material interface. While the deterioration of the high current density charge / discharge characteristics due to the reduced permeability of the non-aqueous electrolyte solution can be suppressed, the decrease in battery capacity and the increase in resistance can be suppressed.

(Thickness of negative electrode plate)
The thickness of the negative electrode plate is designed according to the positive electrode plate to be used, and is not particularly limited. However, the thickness of the composite layer obtained by subtracting the thickness of the metal foil of the core is usually 15 μm or more, preferably 20 μm or more. More preferably, it is 30 μm or more, and usually 300 μm or less, preferably 280 μm or less, more preferably 250 μm or less.

(Surface coating of negative electrode plate)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said negative electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

2-2. Positive electrode <Positive electrode active material>
The positive electrode active material used for the positive electrode is described below.
(composition)
The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. For example, a material containing lithium and at least one transition metal is preferable. Specific examples include lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.

V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable as the transition metal of the lithium transition metal composite oxide. Specific examples include lithium-cobalt composite oxides such as LiCoO ₂ and LiNiO ₂ . Lithium / nickel composite oxides, LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO _{4 and} other lithium / manganese composite oxides, LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O lithium-nickel-manganese-cobalt composite oxides such as _2, a part of Na of the subject become transition metal atoms in these lithium transition metal complex oxide, K, B, F, Al , Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W, and the like. The substituted materials include LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiN
i _0.45 Co _0.10 Al _0.45 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4 and the} like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , Iron phosphates such as LiFeP ₂ O _7, cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn, Fe , Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other elements.

  In addition, it is preferable to include lithium phosphate in the positive electrode active material because continuous charge characteristics are improved. Although there is no restriction | limiting in the use of lithium phosphate, It is preferable to mix and use said positive electrode active material and lithium phosphate. The lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass with respect to the total of the positive electrode active material and lithium phosphate. %, And the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 5% by mass or less.

(Surface coating)
Moreover, you may use what the substance of the composition different from this adhered to the surface of the said positive electrode active material. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

  For example, these surface adhering substances are dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, and dried. After the surface adhering substance precursor is dissolved or suspended in a solvent and added to the positive electrode active material, It can be made to adhere to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and firing simultaneously. In addition, when making carbon adhere, the method of making carbonaceous adhere mechanically later in the form of activated carbon etc. can also be used, for example.

  The amount of the surface adhering substance is, by mass, with respect to the positive electrode active material, preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more, and the upper limit, preferably 20% or less, more preferably as the lower limit. Is used at 10% or less, more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the electrolyte solution on the surface of the positive electrode active material and can improve the battery life. However, when the amount of the adhering quantity is too small, the effect is not sufficiently manifested. If it is too high, resistance may increase in order to inhibit the entry and exit of lithium ions.

In the present invention, a material in which a material having a composition different from that of the positive electrode active material is attached to the surface of the positive electrode active material is also referred to as a “positive electrode active material”.
(shape)
Examples of the shape of the particles of the positive electrode active material include a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, and a column shape as conventionally used. Moreover, primary particles may aggregate to form secondary particles.

(Tap density)
The tap density of the positive electrode active material is preferably 0.5 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 1.0 g / cm ³ or more. When the tap density of the positive electrode active material is within the above range, the amount of the dispersion medium and the necessary amount of the conductive material and the binder necessary for forming the positive electrode active material layer can be suppressed. As a result, the filling rate of the positive electrode active material and the battery Capacity can be secured. By using a complex oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. In general, the tap density is preferably as high as possible, and there is no particular upper limit. However, the tap density is preferably 4.0 g / cm ³ or less, more preferably 3.7 g / cm ³ or less, and still more preferably 3.5 g / cm ³ or less. When it is within the above range, it is possible to suppress a decrease in load characteristics.

In the present invention, the tap density is defined as the powder packing density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is put in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. Ask.
(Median diameter d50)
The median diameter d50 of the positive electrode active material particles (secondary particle diameter when primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably. Is 0.8 μm or more, most preferably 1.0 μm or more, and the upper limit is preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, and most preferably 22 μm or less. Within the above range, a high tap density product can be obtained and battery performance degradation can be suppressed. On the other hand, when producing a positive electrode for a battery, that is, when an active material, a conductive material, a binder, etc. are slurried with a solvent and applied in a thin film form Problems such as streaking can be prevented. Here, by mixing two or more positive electrode active materials having different median diameters d50, it is possible to further improve the filling property at the time of producing the positive electrode.

In the present invention, the median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. When LA-920 manufactured by HORIBA is used as a particle size distribution analyzer, a 0.1% by mass sodium hexametaphosphate aqueous solution is used as a dispersion medium for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. Measured.
(Average primary particle size)
When primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.8. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and most preferably 2 μm or less. When it is in the above range, powder filling property and specific surface area can be ensured and deterioration of battery performance can be suppressed, while reversibility of charge and discharge can be ensured by obtaining appropriate crystallinity. .

In the present invention, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles and obtained by taking the average value. It is done.
(BET specific surface area)
BET specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more, more preferably 0.2 m ² / g or more, further preferably 0.3 m ² / g or more, the upper limit is ^{50 m} 2 / g or less , Preferably 40 m ² / g or less, more preferably 30 m ² / g or less. When the BET specific surface area is in the above range, the battery performance can be secured and the applicability of the positive electrode active material can be kept good.

In the present invention, the BET specific surface area is determined by using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 150 ° C. for 30 minutes under nitrogen flow, and then atmospheric pressure. It is defined by a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas accurately prepared so that the value of the relative pressure of nitrogen to 0.3 is 0.3.
(Method for producing positive electrode active material)
As a manufacturing method of the positive electrode active material, a general method is used as a manufacturing method of the inorganic compound. In particular, various methods are conceivable for producing a spherical or elliptical active material. For example, a transition metal raw material is dissolved or ground and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, dried as necessary, and then added with a Li source such as LiOH, Li ₂ CO ₃ , LiNO _{3 and the} like, and then fired at a high temperature to obtain an active material. .

For the production of the positive electrode, the positive electrode active material may be used alone, or one or more of the different compositions may be used in any combination or ratio. As a preferable combination in this case, a combination of LiCoO ₂ and LiMn ₂ O ₄ such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ or a part of this Mn substituted with another transition metal or the like Or a combination with LiCoO ₂ or a part of this Co substituted with another transition metal or the like.

<Configuration and manufacturing method of positive electrode>
The structure of the positive electrode will be described below. In the present invention, the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. Manufacture of the positive electrode using a positive electrode active material can be performed by a conventional method. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form are pressure-bonded to a positive electrode current collector, or these materials are liquid media A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.

The content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less. Within the above range, the electric capacity of the positive electrode active material in the positive electrode active material layer can be secured, and the strength of the positive electrode can be maintained. The positive electrode active material layer obtained by coating and drying is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material. Density of the positive electrode active material layer is preferably 1.5 g / cm ³ or more as a lower limit, more preferably 2 g / cm ^3, and even more preferably at 2.2 g / cm ³ or more, the upper limit is preferably 5 g / cm ³ or less, more preferably 4.5 g / cm ³ or less, and still more preferably 4 g / cm ³ or less. Within the above range, good charge / discharge characteristics can be obtained, and an increase in electrical resistance can be suppressed.

(Conductive material)
A known conductive material can be arbitrarily used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and ratios. The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and the upper limit is usually 50% by mass or less, preferably It is used so as to contain 30% by mass or less, more preferably 15% by mass or less. Sufficient electrical conductivity and battery capacity can be ensured within the above range.

(Binder)
The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material that can be dissolved or dispersed in the liquid medium used during electrode production may be used. , Polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose, and other resin polymers; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber, isoprene rubber Rubber polymers such as butadiene rubber and ethylene-propylene rubber; styrene / butadiene / styrene block copolymers or hydrogenated products thereof, EP
Thermoplastic elastomeric polymers such as DM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / ethylene copolymer, styrene / isoprene / styrene block copolymer, or hydrogenated products thereof; Syndiotac Soft resinous polymers such as tic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated Fluorine polymers such as polyvinylidene fluoride and polytetrafluoroethylene / ethylene copolymers; polymer compositions having ion conductivity of alkali metal ions (particularly lithium ions), and the like. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and the upper limit is usually 80% by mass or less, preferably Is 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. When the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. On the other hand, if it is too high, battery capacity and conductivity may be reduced.

(Slurry forming solvent)
As the solvent for forming the slurry, the positive electrode active material, the conductive material, the binder, and a solvent capable of dissolving or dispersing the thickener used as necessary are particularly limited to the type. There is no restriction, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous medium include water and a mixed medium of alcohol and water. Examples of the organic medium include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; Esters such as methyl acetate and methyl acrylate; Amines such as diethylenetriamine and N, N-dimethylaminopropylamine; Ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) and dimethyl Examples include amides such as formamide and dimethylacetamide; aprotic polar solvents such as hexamethylphosphalamide and dimethyl sulfoxide.

  In particular, when an aqueous medium is used, it is preferable to make a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. When a thickener is further added, the ratio of the thickener to the active material is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more. The upper limit is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. When it is in the above range, good coatability can be obtained, and a decrease in battery capacity and an increase in resistance can be suppressed.

(Current collector)
The material of the positive electrode current collector is not particularly limited, and a known material can be arbitrarily used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. Of these, metal materials, particularly aluminum, are preferred.

Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, and foam metal in the case of a metal material. A thin film, a carbon cylinder, etc. are mentioned. Of these, metal thin films are preferred. In addition, you may form a thin film suitably in mesh shape. Although the thickness of the thin film is arbitrary, from the viewpoint of strength and handleability as a current collector, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and the upper limit is usually 1 mm or less, preferably 100 μm or less. More preferably, it is 50 μm or less.

Moreover, it is also preferable from the viewpoint of reducing the electronic contact resistance between the current collector and the positive electrode active material layer that a conductive additive is applied to the surface of the current collector. Examples of the conductive assistant include noble metals such as carbon, gold, platinum, and silver.
The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is 20 The lower limit is preferably 15 or less, most preferably 10 or less, and the lower limit is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. Above this range, the current collector may generate heat due to Joule heat during high current density charge / discharge. Within the above range, heat generation of the current collector during high current density charge / discharge can be suppressed, and battery capacity can be secured.

(Electrode area)
When using the electrolytic solution of the present invention, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case from the viewpoint of increasing the stability at high output and high temperature. Specifically, the sum of the electrode areas of the positive electrode with respect to the surface area of the exterior of the secondary battery is preferably 15 times or more, more preferably 40 times or more. The outer surface area of the outer case is the total area obtained by calculation from the vertical, horizontal, and thickness dimensions of the case part filled with the power generation element excluding the protruding part of the terminal in the case of a bottomed square shape. . In the case of a bottomed cylindrical shape, the geometric surface area approximates the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder. The total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material. , The sum of the areas where each surface is calculated separately.

(Thickness of positive plate)
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer obtained by subtracting the metal foil thickness of the core material is preferably as a lower limit with respect to one side of the current collector. Is 10 μm or more, more preferably 20 μm or more, and the upper limit is preferably 500 μm or less, more preferably 450 μm or less.

(Positive electrode surface coating)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said positive electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

2-3. Separator Normally, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the electrolytic solution of the present invention is usually used by impregnating this separator.
The material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. Among them, a resin, glass fiber, inorganic material, etc., which is formed of a material that is stable with respect to the electrolytic solution of the present invention, is used, and it is preferable to use a porous sheet or a nonwoven fabric-like material excellent in liquid retention. .

  As materials for the resin and glass fiber separator, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used individually by 1 type, and 2 or more types may be used together by arbitrary combinations and ratios, and what was laminated | stacked may be used. A specific example of a laminate of two or more kinds in any combination includes a three-layer separator in which polypropylene, polyethylene, and polypropylene are laminated in this order.

The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. Within the above range, insulation and mechanical strength can be secured, while battery performance such as rate characteristics and energy density can be secured.
Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Moreover, it is 90% or less normally, 85% or less is preferable and 75% or less is still more preferable. When the porosity is in the above range, insulation and mechanical strength can be secured, while film resistance can be suppressed and good rate characteristics can be obtained.

  Moreover, although the average pore diameter of a separator is also arbitrary, it is 0.5 micrometer or less normally, 0.2 micrometer or less is preferable, and it is 0.05 micrometer or more normally. If the average pore diameter exceeds the above range, a short circuit tends to occur. When the average pore diameter is in the above range, the film resistance can be suppressed and good rate characteristics can be obtained while preventing a short circuit. On the other hand, as inorganic materials, 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. In the thin film shape, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above-mentioned 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, a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

2-4. Battery design <Electrode group>
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed through the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape through the separator. Either is acceptable. The ratio of the mass of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. . When the electrode group occupancy is in the above range, the battery capacity can be secured, the charge / discharge repeatability and the high temperature storage accompanying the increase in internal pressure are suppressed, and further the operation of the gas release valve is prevented. Can do.

<Current collection structure>
The current collecting structure is not particularly limited, but is preferably a structure that reduces the resistance of the wiring portion and the joint portion. In the case where the electrode group has the above laminated structure, a structure formed by bundling the metal core portions of the electrode layers and welding them to the terminals is preferably used. When the area of one electrode increases, the internal resistance increases. Therefore, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance. When the electrode group has the winding structure described above, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode, respectively, and bundling the terminals.

<Exterior case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, a nickel-plated steel plate, stainless steel, aluminum, an aluminum alloy, a metal such as a magnesium alloy, or a laminated film (laminate film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.

  In an exterior case using metals, the metal is welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed sealed structure, or a caulking structure using the above metals via a resin gasket. Things. Examples of the outer case using the laminate film include a case where a resin-sealed structure is formed by heat-sealing resin layers. In order to improve sealing performance, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a sealed structure, a metal and a resin are joined, so that a resin having a polar group or a modified group having a polar group introduced as an intervening resin is used. Resins are preferably used. The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

<Protective element>
As a protective element, PTC (Positive Temperature Coefficient) whose resistance increases when abnormal heat generation or excessive current flows, temperature fuse, thermistor, shuts off the current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature at abnormal heat generation A valve (current cutoff valve) or the like can be used. It is preferable to select a protective element that does not operate under normal use at a high current, and it is more preferable that the protective element is designed so as not to cause abnormal heat generation or thermal runaway even without the protective element.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.
Some compounds used in this example are shown below.

  Structural formulas of some of the compounds used in the comparative examples are shown below.

<Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-3>
The production methods and evaluation methods of the batteries of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-3 are shown below.
(Example 1-1)
[Production of positive electrode]
90% by mass of lithium / nickel / cobalt / manganese composite oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ) as a positive electrode active material, 7% by mass of acetylene black as a conductive material, and polyfluoride as a binder. 3% by mass of vinylidene chloride (PVdF) was mixed with a disperser in an N-methylpyrrolidone solvent to form a slurry. This was uniformly applied to one side of an aluminum foil having a thickness of 15 μm, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Amorphous coated graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethyl cellulose as thickener (concentration of 1% by weight of sodium carboxymethyl cellulose), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber) 50% by mass) and mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become a mass ratio of amorphous covering graphite: Carboxymethylcellulose sodium: styrene butadiene rubber = 97.5: 1.5: 1.

[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (capacity ratio 3: 4: 3) contains LiPF ₆ as an electrolyte at a rate of 1.0 mol / L. To make a basic electrolyte. Furthermore, 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added so that the content in the nonaqueous electrolytic solution was 0.6 mass ppm, and the non-existing example of Example 1-1 was not performed. An aqueous electrolyte was prepared.

[Production of secondary battery]
The positive electrode, the negative electrode, and a polypropylene separator were laminated in the order of the negative electrode, the separator, and the positive electrode to prepare a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, the non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a non-aqueous electrolyte secondary battery.

[Initial characteristic evaluation]
A non-aqueous electrolyte secondary battery was immersed in an ethanol bath to measure buoyancy. In a state of being sandwiched between glass plates in order to enhance the adhesion between the electrodes, the battery was charged to 4.1 V with a constant current corresponding to 0.3 C at 25 ° C., and then discharged to 3 V with a constant current of 0.3 C. The ratio between the charge capacity and the discharge capacity at this time was defined as the initial charge / discharge efficiency. Subsequently, after charging to 4.2 V with a constant current corresponding to 0.3 C, the battery was stabilized by performing 3 cycles of charging / discharging to discharge to 3 V with a constant current of 0.3 C.

Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and, for example, 0.3C represents a current value of 1/3 thereof.
[High temperature storage characteristics evaluation]
After stabilizing the battery as described above, the non-aqueous electrolyte secondary battery prepared by the above method is charged to 4.2 V at a constant current of 0.3 C, and then charged until the current value reaches 0.05 C. The battery thus obtained was left in a constant temperature bath at 60 ° C. for 10 days. Thereafter, the battery was immersed in an ethanol bath at 25 ° C., and buoyancy was measured. The difference in buoyancy before initial charge / discharge and after storage at high temperature was defined as battery swelling after storage at high temperature. It is preferable that the battery bulge after storage at high temperature is smaller because the dead space of the battery can be reduced.

Using the produced non-aqueous electrolyte secondary battery, initial characteristic evaluation and high-temperature storage characteristic evaluation were performed. The evaluation results are shown in Table 1 as relative values when Comparative Example 1-1 is 100.0%. The same applies to the following.
(Example 1-2)
The non-aqueous electrolyte solution was the same as that of Example 1-1 except that 2 mass ppm of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added to the electrolyte solution of Example 1-1. A secondary battery was fabricated, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.

(Example 1-3)
In the electrolyte solution of Example 1-1, non-aqueous system was carried out in the same manner as in Example 1-1 except that 0.001% by mass of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added. An electrolyte secondary battery was fabricated, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.
(Example 1-4)
In the electrolyte solution of Example 1-1, non-aqueous system was carried out in the same manner as in Example 1-1 except that 0.1% by mass of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added. An electrolyte secondary battery was fabricated, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.

(Example 1-5)
In the electrolyte solution of Example 1-1, non-aqueous system was carried out in the same manner as in Example 1-1 except that 0.5% by mass of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added. An electrolyte secondary battery was fabricated, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.
(Example 1-6)
In the electrolyte solution of Example 1-1, non-aqueous system was performed in the same manner as in Example 1-1 except that 0.7% by mass of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added. An electrolyte secondary battery was fabricated, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.

(Comparative Example 1-1)
In the electrolyte solution of Example 1-1, non-aqueous electrolyte solution 2 was prepared in the same manner as in Example 1-1 except that 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was not added. A secondary battery was prepared, and initial characteristic evaluation and high-temperature storage characteristic evaluation were performed. The evaluation results are shown in Table 1.
(Comparative Example 1-2)
In the electrolytic solution of Example 1-1, the same as Example 1-1 except that 0.001% by mass of cyclohexylbenzene was added instead of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane. Thus, a non-aqueous electrolyte secondary battery was prepared, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.

(Comparative Example 1-3)
In the electrolytic solution of Example 1-1, the same as Example 1-1 except that 0.1% by mass of cyclohexylbenzene was added instead of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane. Thus, a non-aqueous electrolyte secondary battery was prepared, and initial characteristics evaluation and high-temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1.

As is clear from Table 1, Examples 1-1 to 1-6 containing the compound represented by the formula (I) according to the present invention are more initially charged than Comparative Example 1-1 in which no additive is added. It excels in both improvement of discharge efficiency and suppression of battery swelling after high-temperature storage. On the other hand, Comparative Examples 1-2 and 1-3 in which an aromatic compound that is not a compound represented by Formula (I) is added have lower initial charge / discharge efficiency than Comparative Example 1-1 in which no additive is added. However, the battery swelling increased after high temperature storage. Therefore, it is considered that the aromatic compound having the specific structure represented by the formula (I) of the present invention has a particularly excellent property improving effect.

<Examples 2-1 to 2-4, Comparative Example 2-1>
The production methods and evaluation methods of the batteries of Examples 2-1 to 2-4 and Comparative Example 2-1 are shown below.
(Example 2-1)
[Production of positive electrode]
It was produced in the same manner as Example 1-1.

[Production of negative electrode]
It was produced in the same manner as Example 1-1.
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (capacity ratio 3: 4: 3) contains LiPF ₆ as an electrolyte at a rate of 1.0 mol / L. To make a basic electrolyte. Furthermore, 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added so that the content in the nonaqueous electrolytic solution was 0.6 mass ppm, and the non-existing example of Example 1-1 was not performed. An aqueous electrolyte was prepared.

[Production of secondary battery]
The positive electrode, the negative electrode, and a polypropylene separator were laminated in the order of the negative electrode, the separator, and the positive electrode to prepare a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, the non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a non-aqueous electrolyte secondary battery.

[Initial characteristic evaluation]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the volume before charge / discharge was determined from the buoyancy at that time. In a state where the battery is sandwiched between glass plates in order to enhance the adhesion between the electrodes, the battery is charged to 4.1 V with a constant current corresponding to 0.3 C at 25 ° C., and then to 3 V with a constant current of 0.3 C. Discharged. The ratio between the charge capacity and the discharge capacity at this time was defined as the initial charge / discharge efficiency. Next, after charging to 4.1 V with a constant current corresponding to 0.3 C, the battery was left in a constant temperature bath at 60 ° C. for 12 hours. Subsequently, after charging to 4.2 V at a constant current corresponding to 0.3 C at 25 ° C., the battery was stabilized by performing 3 cycles of charging / discharging to discharge to 3 V at a constant current of 0.3 C. Thereafter, the battery was immersed in an ethanol bath, and the volume after charge / discharge was determined from the buoyancy at that time. And the difference of the buoyancy before and after charging / discharging was made into the initial stage battery swelling.

Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and, for example, 0.3C represents a current value of 1/3 thereof.
Using the produced non-aqueous electrolyte secondary battery, initial characteristic evaluation and high-temperature storage characteristic evaluation were performed. The evaluation results are shown in Table 2 as relative values when Comparative Example 2-1 is 100.0%. The same applies to the following.

(Example 2-2)
In the electrolyte solution of Example 2-1, 1-phenyl-1,3,3-trimethylindane was added so that the content in the non-aqueous electrolyte solution was 1% by mass, followed by 3,3,3 ′. Example 3 except that 0.6 mass ppm of 3,3'-tetramethyl-1,1'-spirobiindane was added.
The non-aqueous electrolyte secondary battery was prepared in the same manner as in -1, and the initial characteristics were evaluated. The evaluation results are shown in Table 2.

(Example 2-3)
The non-aqueous electrolyte solution was the same as in Example 2-1, except that 2 mass ppm of 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was added to the electrolyte solution of Example 2-1. A secondary battery was fabricated and evaluated for initial characteristics. The evaluation results are shown in Table 2.
(Example 2-4)
In the electrolyte solution of Example 2-1, 1-phenyl-1,3,3-trimethylindane was added so that the content in the non-aqueous electrolyte solution was 1% by mass, followed by 3,3,3 ′. A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 2-1, except that 2 mass ppm of 3,3′-tetramethyl-1,1′-spirobiindane was added, and initial characteristics were evaluated. The evaluation results are shown in Table 2.
(Comparative Example 2-1)
In the electrolyte solution of Example 2-1, non-aqueous electrolyte solution 2 was prepared in the same manner as in Example 2-1, except that 3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane was not added. A secondary battery was prepared and the initial characteristics were evaluated. The evaluation results are shown in Table 2.

  As is apparent from Table 2, Examples 2-1 to 2-4 according to the present invention are superior in both the improvement of the initial charge / discharge efficiency and the suppression of the initial battery swelling than Comparative Example 2-1 in which no additive is added. ing. Moreover, Example 2-2 and Example 2-4 which used the compound represented by Formula (II) in addition to the compound represented by Formula (I) of this invention are represented by Formula (I). Compared to Example 2-1 and Example 2-3 to which only an aromatic compound is added, the initial charge / discharge efficiency and the initial battery swelling are further improved. Therefore, when the compound represented by the formula (I) and the compound represented by the formula (II) are used in combination, it is considered that the battery characteristics are higher than when the compound of the formula (I) is used alone.

<Example 3-1 and Comparative example 3-1>
The production methods and evaluation methods of the batteries of Example 3-1 and Comparative Example 3-1 are shown below.
(Example 3-1)
[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO2) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, an N-methylpyrrolidone solvent The slurry was mixed with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). Dissolved in proportion. Then, 2.0% by mass of monofluoroethylene carbonate and 2.0% by mass of vinylene carbonate were dissolved as additives to obtain a basic electrolyte solution. Further, 0.2% by mass of 2,4-diphenyl-4-methyl-1-pentene was added to prepare a nonaqueous electrolytic solution of Example 3-1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Initial characteristic evaluation]
In a state where the non-aqueous electrolyte secondary battery is sandwiched between glass plates in order to improve the adhesion between the electrodes, the battery is charged at a constant current for 6 hours at 25 ° C. with a current corresponding to 0.05 C, and then 3 for 0.2 C. A constant current discharge was performed up to 0.0V. The ratio between the charge capacity and the discharge capacity at this time was defined as the initial charge / discharge efficiency. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05 C cut) to 4.1 V with a current corresponding to 0.2 C, it was left under conditions of 45 ° C. and 72 hours. . Then, it discharged to 3.0V with a constant current of 0.2C. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics.

Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.
[High temperature storage characteristics evaluation in discharged state]
After the non-aqueous electrolyte secondary battery after the initial characteristics evaluation is subjected to constant current-constant voltage discharge (also referred to as “CC-CV discharge”) (0.005 C cut) at 25 ° C. to 3.0 V at 25 ° C. Then, it was immersed in an ethanol bath, and the battery volume before storage was determined from the buoyancy at that time. Thereafter, high-temperature storage was performed at 60 ° C. for 14 days. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the change from the battery volume before storage was defined as battery swelling after high-temperature storage in a discharged state. In addition, since the one where a battery swelling after a high temperature preservation | save is small can reduce the dead space of a battery, it is preferable.

Using the produced non-aqueous electrolyte secondary battery, initial characteristic evaluation and high-temperature storage characteristic evaluation in a discharged state were performed. The evaluation results are shown in Table 3 as relative values when Comparative Example 3-1 is 100.0%. The same applies to the following.
[Comparative Example 3-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 3-1, except that the electrolyte solution of Example 3-1 did not contain 2,4-diphenyl-4-methyl-1-pentene. It produced and said evaluation was implemented.

As is apparent from Table 3, Example 3-1 containing the compound represented by formula (I) according to the present invention has improved initial charge and discharge efficiency than Comparative Example 3-1, in which no additive was added. In addition, it is excellent in both the effect of suppressing battery swelling after high temperature storage in a discharged state. Therefore, it is considered that the aromatic compound having the specific structure represented by the formula (I) of the present invention has a particularly excellent property improving effect.

  Since the non-aqueous electrolyte battery using the electrolytic solution of the present invention is excellent in the initial characteristics and the characteristics after high-temperature storage, it can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. , Electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, motor, automobile, motorcycle, motorbike, bicycle, lighting equipment, toy, game equipment, clock, electric tool, strobe, camera, load leveling Power supply, natural energy storage power supply, lithium ion capacitor, and the like.

Claims (9)

A non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte contains at least one aromatic compound represented by the formula (I).

(Where
R ^{1 to} R ⁵ and R ^{9 to} R ¹³ are each independently hydrogen, halogen, or a hydrocarbon group that may be substituted with halogen having 1 to 10 carbon atoms,
R ⁶ and R ⁷ are each independently hydrogen, halogen, or a hydrocarbon group that may be substituted with 1 to 5 carbon atoms halogen,
R ⁸ satisfies the condition (A) or (B).
(A) R ⁸ is a hydrocarbon group having 2 to 15 carbon atoms and having at least one carbon-carbon unsaturated bond, which may be substituted with halogen.
(B) R ⁸ is a hydrocarbon group that combines with R ¹ and R ⁹ to form two ring structures, and the total number of carbon atoms of R ¹ , R ^8, and R ⁹ is 2 or more and 15 or less. R ¹ and R ⁹ may be directly bonded to R ⁸ . ) The non-aqueous electrolyte solution of Claim 1 whose R < ² > -R < ⁵ > and R < ¹⁰ > -R < ¹³ > are hydrogen in the said formula (I). The non-aqueous electrolyte solution of Claim 1 or 2 whose R < ⁶ > and R < ⁷ > is a C1-C5 alkyl group in the said formula (I).   The non-aqueous electrolyte solution according to any one of claims 1 to 3, wherein the non-aqueous electrolyte solution contains the aromatic compound represented by the formula (I) in an amount of 0.1 ppm to 10 mass%. . The nonaqueous electrolytic solution according to any one of claims 1 to 4, wherein the nonaqueous electrolytic solution further contains at least one aromatic compound represented by the formula (II).

Where
R ^{17 to} R ²¹ are independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms,
R ²² and R ²³ are each independently a hydrocarbon group having 1 to 12 carbon atoms,
At least two of R ^{17 to} R ²³ may be joined together to form a ring;
However, Formula (II) is (C) and (D):
(C) At least one of R ^{17 to} R ²¹ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
(D) The total number of carbon atoms of R ^{17 to} R ²³ is 3 or more and 20 or less.
Satisfies at least one of the conditions. ) The non-aqueous electrolyte solution according to claim 5, wherein two of R ¹⁷ , R ²² and R ²³ in the formula (II) are combined to form a ring.   The non-aqueous electrolyte solution according to claim 5 or 6, wherein the non-aqueous electrolyte solution contains the aromatic compound represented by the formula (II) in an amount of 0.001% by mass to 10% by mass.   The non-aqueous electrolyte further includes a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, formulas (I) and (II) ) Other aromatic compounds, cyclic carbonates having a carbon-carbon unsaturated bond, fluorine-free carboxylic acid esters, cyclic compounds having a plurality of ether bonds, compounds having an isocyanuric acid skeleton, monofluorophosphates, difluorophosphoric acids The nonaqueous electrolytic solution according to any one of claims 1 to 7, comprising at least one compound selected from the group consisting of salts, borates, oxalates, and fluorosulfonates.   A non-aqueous electrolyte battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is a non-aqueous electrolyte solution according to any one of claims 1 to 8. A non-aqueous electrolyte battery characterized by the above.