JP5931572B2 - Non-aqueous secondary battery redox shuttle agent, non-aqueous secondary battery electrolyte and non-aqueous secondary battery - Google Patents

Description

  The present invention relates to a redox shuttle agent for a non-aqueous secondary battery, a non-aqueous electrolyte, and a non-aqueous secondary battery.

  As a non-aqueous secondary battery containing a non-aqueous electrolyte, a lithium ion secondary battery having features such as light weight, high energy density, and long life can be used for portable computers such as notebook computers, mobile phones, digital cameras, and video cameras. It is widely used as a power source for electronic equipment. In addition, with the transition to a low environmental impact society, non-aqueous secondary batteries include hybrid electric vehicles (hereinafter abbreviated as “HEV”) and plug-in HEVs (Plug-in Hybrid Electric Vehicles, hereinafter). (Hereinafter abbreviated as “PHEV”), and also in the field of power storage such as a residential power storage system.

  When mounting non-aqueous secondary batteries in vehicles such as automobiles and residential power storage systems, from the viewpoint of cycle performance and long-term reliability, the constituent materials of the battery include chemical and electrochemical stability, strength, Materials with excellent corrosion resistance are required. Furthermore, non-aqueous secondary batteries are also required to have high output performance as a necessary physical property.

  By the way, suppression of overcharge is mentioned as one of the required characteristics with respect to the non-aqueous electrolyte solution for lithium ion secondary batteries. As an overcharge suppression mechanism in a lithium ion secondary battery, a method using a chemical reaction and a method using an electronic circuit are proposed, and the latter is mainly used practically. However, in the method using an electronic circuit, not only the cost increases as the number of cells increases, but various restrictions are imposed on the product design.

  Therefore, the development of technology to suppress overcharge by chemical reaction is underway, and in particular for non-aqueous electrolytes, a method of adding a redox reagent having an oxidation-reduction potential corresponding to the overcharge potential to the electrolyte is studied. Has been. According to this method, when the reversible reactivity of the oxidation-reduction reagent is good, a suppression mechanism that reciprocates between the positive and negative electrodes and consumes an overcharge current is established.

  Such a redox reagent is called a redox shuttle agent. If the safety device of a lithium ion secondary battery can be simplified by including a redox shuttle agent in the electrolyte, a battery system that is lower in cost than a battery system having an overcharge suppression mechanism using an electronic circuit can be realized. Since extra power consumption by the circuit itself can be suppressed, it is very useful.

  For example, Patent Document 1 reports that ferrocenes function as a redox shuttle agent for a 3V class lithium ion secondary battery. Patent Documents 2 and 3 report that an aromatic compound having a structure in which a methoxy group is introduced into a benzene ring functions as a redox shuttle agent for a lithium ion secondary battery of 4 V class or higher. Furthermore, in Patent Document 4, an aromatic compound substituted with at least one tertiary alkyl group and at least one halogenated alkoxy group functions as a redox shuttle agent of 4V class or higher even when charging and discharging are repeated. It has been reported.

JP-A-1-206571 JP-A-7-302614 Japanese Patent Laid-Open No. 9-17447 Special table 2011-512014 gazette

However, ferrocenes have a redox potential of 3.1 to 3.5 V vs. Since it is Li / Li ^+, it cannot be applied to a non-aqueous secondary battery having a high battery voltage. Moreover, the aromatic compound well-known as a redox shuttle agent is described in the said patent document so that it may function even if it charges / discharges repeatedly with a high battery voltage. However, among those aromatic compounds, those in which a reversible redox potential is actually confirmed by cyclic voltammetry are 3.5 to 4.3 V vs. Limited to Li / Li ⁺ range. In particular, for redox shuttle agents of 4.5 V class or higher, the possibility that an irreversible oxidation reaction has an apparent overcharge suppression effect cannot be denied.

  The present invention was made in view of the above circumstances, and when combined with a positive electrode that operates at a high voltage, a non-aqueous electrolyte solution and a non-aqueous secondary battery in which overcharge is reversibly suppressed, and It aims at providing the redox shuttle agent for non-aqueous secondary batteries used for them.

  As a result of intensive studies to solve the above problems, the present inventors have found that an aromatic compound substituted with two trifluoromethyl groups and two alkoxy groups or halogenated alkoxy groups can be obtained at a high voltage. It has been found that it functions as a working redox shuttle agent, and the present invention has been completed. That is, the present invention is as follows.

（式（１）中、Ｒ¹で表される複数の置換基は、メチル基である。）
［２］下記一般式（１）で表される化合物を含有する非水系二次電池用電解液。

（式（１）中、Ｒ¹で表される置換基は、メチル基である。）
［３］［２］に記載の非水系電解液と、正極と、負極とを備える非水系二次電池。 [1] A redox shuttle agent for a non-aqueous secondary battery comprising a compound represented by the following general formula (1).

(In the formula (1), the plurality of substituents represented by R ¹ are methyl groups .)
[2] An electrolyte solution for a non-aqueous secondary battery containing a compound represented by the following general formula (1).

(In formula (1), the substituent represented by R ¹ is a methyl group .)
[3] A non-aqueous secondary battery comprising the non-aqueous electrolyte solution according to [2], a positive electrode, and a negative electrode.

  According to the present invention, even when combined with a positive electrode that operates at a high voltage, a non-aqueous electrolyte solution and a non-aqueous secondary battery that are reversibly suppressed from overcharging, and a non-aqueous secondary battery used in them. A redox shuttle agent can be provided.

It is sectional drawing which shows roughly an example of the non-aqueous secondary battery of this embodiment.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. In addition, the numerical range described using "-" in this specification includes the numerical value described before and behind that.

  The redox shuttle agent for non-aqueous secondary batteries of the present embodiment (hereinafter also simply referred to as “redox shuttle agent”) is composed of a compound represented by the following general formula (1).

  The non-aqueous electrolyte solution of the present embodiment (hereinafter also simply referred to as “electrolyte solution”) contains a redox shuttle agent described later. Moreover, the non-aqueous secondary battery of this embodiment is a secondary battery provided with the said non-aqueous electrolyte solution with a positive electrode and a negative electrode, for example, consists of a material which can occlude and discharge | release lithium ion as a positive electrode active material. A positive electrode containing one or more materials selected from the group, a negative electrode material capable of inserting and extracting lithium ions as a negative electrode active material, and a negative electrode containing one or more materials selected from the group consisting of metallic lithium And a lithium ion secondary battery.

  The non-aqueous secondary battery of the present embodiment may be, for example, a lithium ion secondary battery, and more specifically, is a lithium ion secondary battery schematically showing a cross-sectional view in FIG. A lithium ion secondary battery 100 shown in FIG. 1 includes a separator 110, a positive electrode 120 and a negative electrode 130 that sandwich the separator 110 from both sides, and a positive electrode assembly that sandwiches a laminate of them (the separator 110, the positive electrode 120, and the negative electrode 130). An electric body 140 (arranged outside the positive electrode 120), a negative electrode current collector 150 (arranged outside the negative electrode 130), and a battery exterior 160 that accommodates them. A laminate in which the positive electrode 120, the separator 110, and the negative electrode 130 are laminated is impregnated with the electrolytic solution according to the present embodiment. As each of these members, those provided in a conventional lithium ion secondary battery can be used except for the positive electrode. For example, those described below may be used.

<1. Non-aqueous electrolyte>
The non-aqueous electrolyte solution according to the present embodiment is not particularly limited as long as it is an electrolyte solution containing a non-aqueous solvent, a salt, and a redox shuttle agent described later, and the non-aqueous solvent and the salt may be known ones. Good. The non-aqueous electrolyte solution of the present embodiment preferably does not contain moisture, but may contain a very small amount of moisture as long as it does not impede the solution of the problem of the present invention. Such water content may be 0 to 100 ppm with respect to the total amount of the non-aqueous electrolyte.

ここで、式（１）中、Ｒ¹で表される複数の置換基は、それぞれ独立に、炭素数１〜４のアルキル基又は炭素数１〜４のフッ素置換アルキル基である。炭素数１〜４のアルキル基としては、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基及びｔｅｒｔ−ブチル基が挙げられる。炭素数１〜４のフッ素置換アルキル基としては、例えば、モノフルオロメチル基、ジフルオロメチル基、２，２，２−トリフルオロエチル基、２，２，３，３−テトラフルオロプロピル基及び２，２，３，４，４，４−ヘキサフルオロブチル基が挙げられる。なお、Ｒ¹で表される複数の置換基は、合成の容易さの観点から、互いに同一であると好ましい。 <1-1. Redox shuttle agent>
As the redox shuttle agent, a compound represented by the following general formula (1) can be used.

Here, in the formula (1), the plurality of substituents represented by R ¹ are each independently an alkyl group having 1 to 4 carbon atoms or a fluorine-substituted alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and tert-butyl group. Examples of the fluorine-substituted alkyl group having 1 to 4 carbon atoms include a monofluoromethyl group, a difluoromethyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3-tetrafluoropropyl group, and 2, 2,3,4,4,4-hexafluorobutyl group may be mentioned. The plurality of substituents represented by R ¹ are preferably the same as each other from the viewpoint of ease of synthesis.

  The compound represented by the general formula (1) has a high oxidation-reduction potential, the π electron is protected by the steric effect of the trifluoromethyl group, and the oxygen atom of the alkoxy group or the fluorine-substituted alkoxy group has an unshared electron pair. Therefore, the π-conjugated plane does not open even in the redox state, and the long-term stability is excellent.

The specific example of the redox shuttle agent in this embodiment is illustrated below.

The redox shuttle agent in this embodiment can also be produced by a conventional method, for example, produced by any one of the three reaction routes represented by the following general formulas (2), (3) and (4). can do. In the formulas (2), (3) and (4), R ¹ has the same meaning as in the general formula (1) and is an alkyl group having 1 to 4 carbon atoms or a fluorine-substituted alkyl having 1 to 4 carbon atoms. It is a group.
[Reaction route 1]

[Reaction route 2]

[Reaction route 3]

First, the manufacturing method of the reaction route 1 shown by the said General formula (2) is demonstrated.
In reaction route 1, 2,5-bistrifluoromethylhydroquinone and N, N-dimethylformamide are mixed, then NaH is added to the mixture, and then iodide R ¹ I is added. After separating the reaction solution with an organic solvent such as dichloromethane and brine, the organic solvent is recovered through washing with water, dried by adding a dehydrating agent. The dehydrating agent is not particularly limited, but is preferably anhydrous sodium sulfate or anhydrous magnesium sulfate. After removing the solvent, the resulting crude product is purified by silica gel column chromatography to obtain the desired compound. Although there is no restriction | limiting in particular as a developing solvent of a silica gel column chromatography, For example, the developing solvent used as chloroform: n-hexane = 1: 4 (volume ratio) is mentioned.

Next, the manufacturing method of the reaction route 2 shown by the said General formula (3) is demonstrated.
In the reaction route 2, 2,5-bistrifluoromethylhydroquinone, potassium carbonate, tri-n-butylamine and acetone are mixed in a nitrogen atmosphere, and then the perfluorobutylsulfonic acid ester C ₄ F ₉ SO is mixed. ₃ R ¹ , for example 2,2,2-trifluoroethyl perfluorobutyl sulfonate, is added dropwise. Although there is no restriction | limiting in particular about the reaction temperature at this time, It is preferable that it is 40-70 degreeC, It is more preferable that it is 50-65 degreeC, It is still more preferable that it is 57-63 degreeC. Thereafter, water is added to stop the reaction, and acetone is removed by concentration under reduced pressure. After cooling, suction filtration and drying, the residue obtained is purified by silica gel column chromatography to obtain the desired compound. Although there is no restriction | limiting in particular as a developing solvent of silica gel column chromatography, For example, the developing solvent made into chloroform: n-hexane = 1: 10 (volume ratio) is mentioned.

Next, the manufacturing method of the reaction route 3 shown by the said General formula (4) is demonstrated.
In the reaction route 3, after mixing methanol and orthoperiodic acid, iodine is added and stirred. Further, 1,4-dialkoxybenzene or 1,4-di (fluorine-substituted alkoxy) benzene is added and stirred. Although there is no restriction | limiting in particular about the reaction temperature at this time, It is preferable that it is 50-80 degreeC, It is more preferable that it is 60-75 degreeC, It is still more preferable that it is 67-73 degreeC. After completion of the reaction, the obtained solution was poured into a mixture of Na ₂ S ₂ O ₅ and water, the precipitate was suction filtered and dried, and the resulting powder was purified by silica gel column chromatography, The intermediate product 2,5-diiodide is obtained. The developing solvent for silica gel column chromatography is not particularly limited, and examples thereof include dichloromethane.

  Next, the above intermediate product, sodium trifluoroacetate, copper iodide, and N, N-dimethylacetamide are mixed and refluxed in a nitrogen atmosphere. Although there is no restriction | limiting in particular about reflux temperature, It is preferable that it is 130-160 degreeC, It is more preferable that it is 140-155 degreeC, It is still more preferable that it is 147-153 degreeC. The obtained solution is cooled and filtered, and after separating with an organic solvent such as dichloromethane and water, the organic solvent is recovered through washing with water, dried by adding a dehydrating agent. The dehydrating agent is not particularly limited, but is preferably anhydrous sodium sulfate or anhydrous magnesium sulfate. After removing the solvent, the resulting crude product is purified by silica gel column chromatography to obtain the desired compound. The developing solvent for silica gel column chromatography is not particularly limited, and examples thereof include dichloromethane.

  The content of the redox shuttle agent in the non-aqueous electrolyte solution of the present embodiment is preferably 0.1 to 20% by mass, and 0.5 to 10% by mass with respect to the total amount of the non-aqueous electrolyte solution. It is more preferable. If the content is 0.1% by mass or more, the effect of preventing overcharge due to the circulation action of the oxidation-reduction reaction can be obtained more effectively, and if the content is 20% by mass or less, there is little decrease in ionic conductivity and input / output. The influence on the battery characteristics such as characteristics and battery life is reduced.

<1-2. Non-aqueous solvent>
There is no restriction | limiting in particular as a non-aqueous solvent, For example, an aprotic solvent is mentioned, Aprotic polar solvent is preferable. Specific examples of such a non-aqueous solvent include, for example, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, trans-2,3-butylene carbonate, cis-2,3-butylene carbonate, and 1,2-pentylene. Cyclic carbonates typified by lencarbonate, trans-2,3-pentylene carbonate, cis-2,3-pentylene carbonate, trifluoromethylethylene carbonate, fluoroethylene carbonate, 1,2-difluoroethylene carbonate; γ-butyrolactone Lactones typified by γ-valerolactone; sulfur compounds typified by sulfolane and dimethyl sulfoxide; cyclic ethers typified by tetrahydrofuran, 1,4-dioxane and 1,3-dioxane; methyl ethyl carbonate Carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate, chain carbonate represented by methyl trifluoroethyl carbonate; acetonitrile, propionitrile , Butyronitrile, valeronitrile, benzonitrile, acrylonitrile and other mononitriles; methoxyacetonitrile, alkoxy group-substituted nitriles typified by 3-methoxypropionitrile; chain carboxylic acid esters typified by methylpropionate; dimethoxyethane The chain ether represented is mentioned. Moreover, the halide represented by these fluorides is also mentioned. These are used singly or in combination of two or more.

  In order to increase the ionization degree of the salt that contributes to charging / discharging of the non-aqueous secondary battery, the non-aqueous solvent preferably contains one or more cyclic aprotic polar solvents, and more preferably contains one or more cyclic carbonates. preferable. Moreover, in order to make all the functions of the solubility, conductivity, and ionization degree of the salt good, a mixed solvent of two or more aprotic polar solvents is preferable. Examples of the aprotic polar solvent serving as a component of the mixed solvent include those described above, and examples of the mixed solvent include a mixed solvent of a cyclic carbonate and a chain carbonate.

<1-3. Salt>
The salt is not particularly limited as long as it is used for an electrolyte solution of a non-aqueous secondary battery, and any salt may be used. The salt is preferably contained in the nonaqueous electrolytic solution of the present embodiment at a concentration of 0.1 to 3 mol / L, and more preferably 0.5 to 2 mol / L. When the salt concentration is within this range, the conductivity of the electrolytic solution is kept higher, and at the same time, the charge / discharge efficiency of the nonaqueous secondary battery is kept higher.

Although the salt in this embodiment does not have a restriction | limiting in particular, It is preferable that it is an inorganic lithium salt. Here, the “inorganic lithium salt” is a lithium salt soluble in acetonitrile that does not contain a carbon atom in the anion, and the “organic lithium salt” described later is lithium soluble in acetonitrile containing a carbon atom in the anion. Salt. The inorganic lithium salt is not particularly limited as long as it is used as a normal non-aqueous electrolyte, and may be any one. Specific examples of such inorganic lithium salts include, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , Li ₂ B ₁₂ F _b H _12-b [B is an integer of 0 to 3], for example, a lithium salt bonded to a polyvalent anion containing no carbon atom.

These inorganic lithium salts are used singly or in combination of two or more. Among these, when an inorganic lithium salt having a fluorine atom is used as the inorganic lithium salt, a passive film is formed on the surface of the metal foil that is the positive electrode current collector, which is preferable from the viewpoint of suppressing an increase in internal resistance. Further, when an inorganic lithium salt having a phosphorus atom is used as the inorganic lithium salt, it is more preferable because free fluorine atoms are easily released, and LiPF ₆ is particularly preferable.

  The content of the inorganic lithium salt in the non-aqueous electrolyte solution of the present embodiment is preferably 0.1 to 40% by mass, and preferably 1 to 30% by mass with respect to the total amount of the non-aqueous electrolyte solution. More preferably, it is more preferably 5 to 25% by mass.

The salt in the present embodiment may further contain an organic lithium salt in addition to the inorganic lithium salt. In addition, when using together organic lithium salt with inorganic lithium salt with high ion conductivity, following formula (5):
0 ≦ X <1 (5)
It is preferable to satisfy the condition represented by. Here, in said formula (5), X shows the molar ratio of the organic lithium salt with respect to the inorganic lithium salt contained in a non-aqueous electrolyte solution. When the molar ratio of the organic lithium salt to the inorganic lithium salt contained in the nonaqueous electrolytic solution is within this range, the high ion conduction performance of the inorganic lithium salt can be preferentially functioned.

  The content of the organic lithium salt in the non-aqueous electrolyte solution of the present embodiment is preferably 0.1 to 30% by mass, and 0.2 to 20% by mass with respect to the total amount of the non-aqueous electrolyte solution. Is more preferable, and it is still more preferable that it is 0.5-15 mass%. When the content of the organic lithium salt is within this range, a balance between the function and solubility of the electrolytic solution can be ensured.

Specific examples of the organic lithium salt include LiN (SO ₂ C _m F _{2m + 1} ) ₂ such as LiN (SO ₂ CF ₃ ) ₂ and LiN (SO ₂ C ₂ F ₅ ) _{2, where} m is 1 to 8. An organic lithium salt represented by LiPF _n (C _p F _{2p + 1} ) _6-n such as LiPF ₅ (CF ₃ ), _where n is an integer of 1 to 5, and p is an integer of 1 to 8. Organic lithium salt represented by LiBF _q (C _s F _{2s + 1} ) _4-q such as LiBF ₃ (CF ₃ ), where q is an integer of 1 to 3, and s is an integer of 1 to 8 Lithium salt; lithium bis (oxalato) borate (LiBOB) represented by LiB (C ₂ O ₄ ) ₂ ; lithium salt of borate having a halogenated organic acid as a ligand; LiBF ₂ (C ₂ O ₄ ) Lithium oxalate difluoroborate (LiODFB) represented by: LiB (C ₃ O ₄ H ₂ ) ₂ Examples thereof include organic lithium salts such as lithium tetrafluorooxalatophosphate represented by s (malonate) borate (LiBMB); LiPF ₄ (C ₂ O ₄ ).

Moreover, the organic lithium salt represented by the following general formula (6a), (6b), and (6c) can also be used.
LiC (SO ₂ R ² ) (SO ₂ R ³ ) (SO ₂ R ⁴ ) (6a)
LiN (SO ₂ OR ⁵ ) (SO ₂ OR ⁶ ) (6b)
LiN (SO ₂ R ⁷ ) (SO ₂ OR ⁸ ) (6c)
Here, in the formula, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ may be the same as or different from each other, and are perfluoroalkyl having 1 to 8 carbon atoms. Indicates a group.

  These organic lithium salts are used singly or in combination of two or more, and organic lithium salts having a boron atom are preferred because of their structural stability. In addition, the organic lithium salt having an organic ligand has an internal structure including a positive electrode because the organic ligand is involved in an electrochemical reaction and forms a protective film called Solid Electrolyte Interface (SEI) on the electrode surface. This is preferable from the viewpoint of suppressing an increase in resistance. As such an organic lithium salt, specifically, LiBOB, a borate lithium salt having a halogenated organic acid as a ligand, LiODFB, and LiBMB are preferable, and LiBOB and LiODFB are particularly preferable.

  The nonaqueous electrolytic solution of the present embodiment may further contain an ionic compound composed of a salt formed of an organic cation species other than lithium ions and an anionic species. When the ionic compound is contained in the non-aqueous electrolyte solution of this embodiment, there is an effect of further suppressing an increase in the internal resistance of the battery.

  Examples of the cation of the ionic compound include tetraethylammonium, tetrabutylammonium, triethylmethylammonium, trimethylethylammonium, dimethyldiethylammonium, trimethylpropylammonium, trimethylbutylammonium, trimethylpentylammonium, trimethylhexylammonium, trimethyloctylammonium, and diethyl. Quaternary ammonium cations such as methylmethoxyethylammonium; 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1-hexyl-3-methyl Imidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-methyl-3-propylimidazolium, etc. Pyridinium cations such as 1-ethylpyridinium, 1-butylpyridinium and 1-hexylpyridinium; Piperidinium cations such as 1-methyl-1-propylpiperidinium and 1-butyl-1-methylpiperidinium; Pyrrolidinium cations such as 1-ethyl-1-methylpyrrolidinium, 1-methyl-1-propylpyrrolidinium, 1-butyl-1-methylpyrrolidinium; sulfonium cations such as diethylmethylsulfonium and triethylsulfonium; A quaternary phosphonium cation is mentioned. Among these cations, a cation having a nitrogen atom is preferable from the viewpoint of electrochemical stability, and a pyridinium cation is more preferable.

The anion of the ionic compound may be one usually employed as a counter ion of the above cation. For example, BF ₄ ⁻ , PF ₆ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ , N (SO ₂ C ₂ F ₅ ) ₂ ⁻ and SO ₃ CF ₃ ^— . Among these anions, PF ₆ ^{− which} is excellent in suppressing dissociation of ions and increase in internal resistance is preferable.

<1-4. Additives>
The non-aqueous electrolyte solution of the present embodiment may contain an additive that protects the electrode. The additive in the present embodiment is not particularly limited as long as it does not inhibit the solution of the problem according to the present invention, and substantially overlaps with a substance that plays a role as a solvent for dissolving a salt, that is, the above non-aqueous solvent. May be. Further, the additive is preferably a substance that contributes to the performance improvement of the non-aqueous electrolyte solution and non-aqueous secondary battery of the present embodiment, but also includes substances that are not directly involved in the electrochemical reaction, One component is used alone, or two or more components are used in combination.

  Specific examples of the additive include, for example, 4-fluoro-1,3-dioxolan-2-one, 4,4-difluoro-1,3-dioxolan-2-one, cis-4,5-difluoro-1, 3-dioxolan-2-one, trans-4,5-difluoro-1,3-dioxolan-2-one, 4,4,5-trifluoro-1,3-dioxolan-2-one, 4,4,5 , 5-tetrafluoro-1,3-dioxolan-2-one, fluoroethylene carbonate represented by 4,4,5-trifluoro-5-methyl-1,3-dioxolan-2-one; vinylene carbonate, 4 , 5-Dimethyl vinylene carbonate, cyclic carbonate containing unsaturated bond typified by vinyl ethylene carbonate; γ-butyrolactone, γ-valerolactone, γ-caprolacto , Δ-valerolactone, δ-caprolactone, lactone represented by ε-caprolactone; cyclic ether represented by 1,2-dioxane; methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl formate , Ethyl acetate, ethyl propionate, ethyl butyrate, n-propyl formate, n-propyl acetate, n-propyl propionate, n-propyl butyrate, isopropyl formate, isopropyl acetate, isopropyl propionate, isopropyl Butyrate, n-butyl formate, n-butyl acetate, n-butyl propionate, n-butyl butyrate, isobutyl formate, isobutyl acetate, isobutyl propionate, isobutyl butyrate, se -Butyl formate, sec-butyl acetate, sec-butyl propionate, sec-butyl butyrate, tert-butyl formate, tert-butyl acetate, tert-butyl propionate, tert-butyl butyrate, methyl pivalate , N-butyl pivalate, n-hexyl pivalate, n-octyl pivalate, dimethyl oxalate, ethyl methyl oxalate, diethyl oxalate, diphenyl oxalate, malonic acid ester, fumaric acid ester, maleic acid ester Acid esters; amides represented by N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide; ethylene sulfite, propylene sulfite, butylene sulfite, pentenser Cyclic sulfur compounds typified by sulfite, sulfolane, 3-methylsulfolane, 3-sulfolene, 1,3-propane sultone, 1,4-butane sultone, 1,3-propanediol sulfate, tetramethylene sulfoxide, thiophene 1-oxide An aromatic compound typified by monofluorobenzene, biphenyl, and fluorinated biphenyl; a nitro compound typified by nitromethane; a Schiff base; a Schiff base complex; and an oxalato complex. These are used singly or in combination of two or more.

  Although there is no restriction | limiting in particular about content of the additive in the non-aqueous electrolyte solution of this embodiment, It is preferable that it is 0.1-30 mass% with respect to the whole quantity of the non-aqueous electrolyte solution of this embodiment. More preferably, it is 1-10 mass%. In this embodiment, the additive contributes to the development of high cycle performance, but on the other hand, the contribution to high output performance in a low temperature environment has not been confirmed. Although the deterioration of the electrolyte solution according to the present embodiment is suppressed as the amount of the additive is increased, the high output characteristic in a low temperature environment is improved as the amount of the additive is decreased. Therefore, if the content of the additive is within the above range, the superior performance based on the high ionic conductivity of the non-aqueous electrolyte solution can be more sufficiently obtained without impairing the basic function as a non-aqueous secondary battery. It can be demonstrated. By preparing the electrolytic solution with such a composition, all of the cycle performance of the electrolytic solution, the high output performance in a low temperature environment, and other battery characteristics can be further improved.

<1-5. Dinitrile Compound>
The nonaqueous electrolytic solution of the present embodiment may further contain a dinitrile compound, that is, a compound having two nitrile groups in the molecule. The dinitrile compound has the effect of reducing corrosion of metal parts such as battery cans and electrodes. The reason is considered to be that a protective film that suppresses corrosion is formed on the surface of the metal part with reduced corrosion by using the dinitrile compound. However, the mechanism that exhibits the effect is not limited to this.

  The dinitrile compound is not particularly limited as long as it does not hinder the solution of the problem according to the present invention, but preferably has a methylene chain, more preferably 1 to 12 in methylene chain, linear or branched. Either may be sufficient. Examples of the dinitrile compound include succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanooctane, and 1,9-dicyanononane. , 1,10-dicyanodecane, 1,11-dicyanoundecane, linear dinitrile compounds such as 1,12-dicyanododecane; tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile 2,2,4,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,6-dicyanoheptane, 2,7-dicyanooctane Branched dinitrile compounds such as 2,8-dicyanononane and 1,6-dicyanodecane; , 2-dicyanobenzene, 1,3-dicyanobenzene, aromatic dinitrile compounds such as 1,4-dicyano benzene. These are used singly or in combination of two or more.

  The content of the dinitrile compound in the non-aqueous electrolyte solution of the present embodiment is not particularly limited, but the non-aqueous electrolyte solution is an inorganic lithium salt with respect to the total amount of components contained in the non-aqueous electrolyte solution excluding the organic lithium salt. Is preferably 0.01 to 1 mol / L, preferably 0.02 to 0.5 mol / L with respect to the total amount of components contained in the non-aqueous electrolyte solution excluding the lithium salt. Is more preferable, and it is still more preferable that it is 0.05-0.3 mol / L. When the content of the dinitrile compound is within the above range, the cycle performance can be further improved without impairing the basic function as a non-aqueous secondary battery.

The dinitrile compound tends to have a low dipole moment when the number of methylene chains is an even number, but surprisingly a higher addition effect was experimentally recognized than when the number of methylene chains was an odd number. Therefore, the dinitrile compound preferably contains one or more compounds selected from the group consisting of compounds represented by the following general formula (7).
NC- (CR ⁹ R ¹⁰ ) _2a -CN (7)
Here, in Formula (7), R < ⁹ > and R < ¹⁰ > show a hydrogen atom or an alkyl group each independently, and a shows the integer of 1-6. The alkyl group is preferably one having 1 to 10 carbon atoms.

<2. Positive electrode and positive electrode current collector>
A positive electrode will not be specifically limited if it acts as a positive electrode of a non-aqueous secondary battery, A well-known thing may be used.

It is preferable that the positive electrode contains one or more materials selected from the group consisting of materials capable of inserting and extracting lithium ions as the positive electrode active material, because high voltage and high energy density tend to be obtained. . Examples of such materials include lithium-containing compounds represented by the following general formulas (8a) and (8b), and metal chalcogenides having a tunnel structure and a layered structure.
Li _x MO ₂ (8a)
Li _y M ₂ O ₄ (8b)
Here, in the formula, M represents one or more metals selected from transition metals, x represents a number from 0 to 1, and y represents a number from 0 to 2.

Examples of the lithium-containing compound include lithium cobalt oxide typified by LiCoO ₂ ; lithium manganese oxide typified by LiMnO ₂ , LiMn ₂ O ₄ and Li ₂ Mn ₂ O ₄ ; lithium nickel typified by LiNiO ₂ Oxide; represented by Li _z MO ₂ (M represents two or more elements selected from the group consisting of Ni, Mn, Co, Al, and Mg, and z represents a number greater than 0.9 and less than 1.2). And lithium-containing composite metal oxides.

Any lithium-containing compound may be used as long as it contains lithium. For example, the lithium-containing compound includes a composite oxide containing lithium and a transition metal element, a phosphate compound containing lithium and a transition metal element, and lithium and a transition metal element. Silicate metal compounds (for example, Li _{t Mu} SiO ₄ , M is as defined in the above formula (8a), t is a number from 0 to 1, and u is a number from 0 to 2). From the viewpoint of obtaining a higher voltage, lithium, cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr), vanadium ( V) and composite oxides containing at least one transition metal element selected from the group consisting of titanium (Ti) and phosphate compounds are preferred.

More specifically, the lithium-containing compound is preferably a metal oxide having lithium, a metal chalcogenide having lithium, and a metal phosphate compound having lithium. For example, the lithium-containing compounds are represented by the following general formulas (9a) and (9b), respectively. The compound which is made is mentioned. Among these, a metal oxide having lithium and a metal chalcogenide having lithium are more preferable.
^{_{Li v M I O 2 (9a}} )
Li _w M ^II PO ₄ (9b)
Here, in the formula, M ^I and M ^II each represent one or more transition metal elements, and the values of v and w vary depending on the charge / discharge state of the battery, but usually v is 0.05 to 1.10, w Indicates a number from 0.05 to 1.10.

  The compound represented by the general formula (9a) generally has a layered structure, and the compound represented by the general formula (9b) generally has an olivine structure. In these compounds, for the purpose of stabilizing the structure, a part of the transition metal element is substituted with Al, Mg, other transition metal elements or included in the crystal grain boundary, a part of the oxygen atom And those substituted with a fluorine atom or the like. Furthermore, what coat | covered the other positive electrode active material to at least one part of the positive electrode active material surface is mentioned.

Examples of the metal chalcogenide having a tunnel structure and a layered structure are represented by MnO ₂ , FeO ₂ , FeS ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , TiS ₂ , MoS ₂ and NbSe _2. Examples include oxides, sulfides, and selenides of metals other than lithium.

  Examples of other positive electrode active materials include sulfur and conductive polymers represented by polyaniline, polythiophene, polyacetylene, and polypyrrole.

  A positive electrode active material is used individually by 1 type or in combination of 2 or more types.

  The number average particle diameter (primary particle diameter) of the positive electrode active material is preferably 0.05 μm to 100 μm, more preferably 1 μm to 10 μm. The number average particle size of the positive electrode active material can be measured by a wet particle size measuring device (for example, a laser diffraction / scattering particle size distribution meter, a dynamic light scattering particle size distribution meter). Alternatively, 100 particles observed with a transmission electron microscope are randomly extracted and analyzed with image analysis software (for example, image analysis software manufactured by Asahi Kasei Engineering Co., Ltd., trade name “A Image-kun”). It can also be obtained by calculating an average. In this case, when the number average particle diameter differs between measurement methods for the same sample, a calibration curve created for the standard sample may be used.

  The positive electrode is obtained, for example, as follows. That is, first, a positive electrode mixture-containing slurry is prepared by dispersing, in a solvent, a positive electrode mixture prepared by adding a conductive additive, a binder, or the like to the positive electrode active material as necessary. Here, the solid content concentration in the positive electrode mixture-containing slurry is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass. Next, this positive electrode mixture-containing slurry is applied to a positive electrode current collector and dried to form a positive electrode active material layer. A positive electrode mixture layer is formed by compressing the positive electrode active material layer obtained after drying with a roll press or the like. The thickness of the positive electrode mixture after compression is preferably 10 to 300 μm, more preferably 20 to 280 μm, still more preferably 30 to 250 μm.

  Examples of the conductive aid include carbon black typified by graphite, acetylene black and ketjen black, and carbon fiber. The number average particle size (primary particle size) of the conductive assistant is preferably 10 nm to 10 μm, more preferably 20 nm to 1 μm, and is measured in the same manner as the number average particle size of the positive electrode active material. Examples of the binder include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid, styrene butadiene rubber, and fluorine rubber. Moreover, there is no restriction | limiting in particular as a solvent, Although a conventionally well-known thing may be used, For example, N-methyl- 2-pyrrolidone, dimethylformamide, dimethylacetamide, and water are mentioned.

  As a positive electrode electrical power collector, it is comprised with metal foil, such as aluminum foil, nickel foil, or stainless steel foil, for example. Moreover, the carbon coat may be given or it may be processed into the mesh form. The thickness of the positive electrode current collector is preferably 5 to 40 μm, more preferably 7 to 35 μm, and still more preferably 9 to 30 μm.

<3. Negative electrode and negative electrode current collector>
A negative electrode will not be specifically limited if it acts as a negative electrode of a non-aqueous secondary battery, A well-known thing may be used.

The negative electrode preferably contains at least one material selected from the group consisting of a material capable of inserting and extracting lithium ions as a negative electrode active material and metallic lithium. In addition to metallic lithium, examples of such materials include amorphous carbon (hard carbon), artificial graphite, natural graphite, pyrolytic carbon, coke, glassy carbon, fired bodies of organic polymer compounds, mesocarbon microbeads, carbon Examples thereof include carbon materials represented by fibers, activated carbon, graphite, carbon colloid, and carbon black. Among these, examples of the coke include pitch coke, needle coke, and petroleum coke. Further, the fired body of the organic polymer compound is obtained by firing and polymerizing a polymer material such as a phenol resin or a furan resin at an appropriate temperature. In addition to carbon, the carbon material may contain different elements or different compounds such as O, B, P, N, S, Si, SiC, SiO, SiO ₂ , and B ₄ C. As content of a different element or a different compound, 0-10 mass% is preferable.

  Further, examples of the material capable of inserting and extracting lithium ions include a material containing an element capable of forming an alloy with lithium. This material may be a single metal or a semi-metal, an alloy or a compound, and may have at least a part of one or more of these phases. Good.

  In the present specification, the “alloy” includes an alloy having one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. In addition, the alloy may have a nonmetallic element as long as the alloy has metallic properties as a whole. In the alloy structure, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of these coexist.

  Examples of metal elements and metalloid elements capable of forming an alloy with lithium include titanium (Ti), tin (Sn), lead (Pb), aluminum (Al), indium (In), silicon (Si), and zinc ( Zn), antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr) and yttrium (Y). .

  Among these, the metal elements and metalloid elements of Group 4 or 14 in the long-period periodic table are preferable, and titanium, silicon, which have a high ability to occlude and release lithium and can obtain a high energy density are particularly preferable. And tin.

  As an alloy of tin, for example, as a second constituent element other than tin, silicon, magnesium (Mg), nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium (Ti), germanium, bismuth, Examples thereof include those having one or more elements selected from the group consisting of antimony and chromium (Cr).

  Examples of the silicon alloy include, as the second constituent element other than silicon, tin, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium. Those having one or more elements selected from the above are listed.

  Examples of the titanium compound, the tin compound, and the silicon compound include those having oxygen (O) or carbon (C), and in addition to titanium, tin, or silicon, the second constituent element described above is included. It may be.

The negative electrode is 0.4 to 3 V vs. negative electrode active material. You may contain the metal compound which can occlude lithium ion in the range of Li / Li ^<+ >. Examples of such metal compounds include metal oxides, metal sulfides, and metal nitrides.

Examples of the metal oxide include titanium oxide, lithium titanium oxide (lithium titanium-containing composite oxide), tungsten oxide (for example, WO ₃ ), amorphous tin oxide (for example, SnB _0.4 P _0.6 O _3.1 ), and tin silicon. An oxide (for example, SnSiO ₃ ) and silicon oxide (SiO) can be mentioned. Among these, titanium oxide and lithium titanium oxide are preferable.

Examples of the lithium titanium oxide include spinel lithium titanate {for example, Li _{4 + a} Ti ₅ O ₁₂ (a can be changed within the range of −1 ≦ a ≦ 3 by charge / discharge reaction)}, ramsdellite structure. Lithium titanate {for example, Li _{2 + b} Ti ₃ O ₇ (b can be changed within the range of −1 ≦ b ≦ 3 by charge / discharge reaction)}.

As the titanium oxide, any one containing or not containing Li before charging / discharging can be used. Examples of titanium oxides that do not contain Li before charging / discharging, that is, during synthesis, include, for example, titanium oxide (eg, TiO ₂ , H ₂ Ti ₁₂ O ₂₅ ), Ti and P, V, Sn, Cu, Ni, and Fe. Titanium composite oxide containing at least one element selected can be mentioned. As TiO ₂ , anatase type and low crystalline one having a heat treatment temperature of 300 to 500 ° C. is preferable. Examples of the titanium composite oxide include TiO ₂ —P ₂ O ₅ , TiO ₂ —V ₂ O ₅ , TiO ₂ —P ₂ O ₅ —SnO ₂ , TiO ₂ —P ₂ O ₅ —MeO (Me is Cu, At least one element selected from the group consisting of Ni and Fe). The titanium composite oxide has a low crystallinity, and preferably has a microstructure in which a crystal phase and an amorphous phase coexist, or an amorphous phase exists alone. With such a microstructure, cycle performance can be greatly improved.

Examples of those containing Li before charge / discharge, that is, titanium oxide containing lithium from the time of synthesis, include Li _c TiO ₂ (c is 0 ≦ c ≦ 1.1).

Examples of the metal sulfide include titanium sulfide (eg, TiS ₂ ), molybdenum sulfide (eg, MoS ₂ ), and iron sulfide (eg, FeS, FeS ₂ , Li _g FeS ₂ (g is 0 ≦ g ≦ 1)). It is done. Examples of the metal nitride include lithium cobalt nitride (for example, Li _d Co _e N, 0 <d <4, 0 <e <0.5).

In the non-aqueous secondary battery of this embodiment, from the viewpoint that the battery voltage can be increased, the negative electrode has 0.4 V vs. lithium ion as the negative electrode active material. It is preferable to contain a material that occludes at a lower potential than Li / Li ⁺ . Examples of such materials include amorphous carbon (hard carbon), artificial graphite, natural graphite, graphite, pyrolytic carbon, coke, glassy carbon, a fired body of an organic polymer compound, mesocarbon microbeads, carbon fiber, In addition to carbon materials such as activated carbon, graphite, carbon colloid and carbon black, metallic lithium, metal oxide, metal nitride, lithium alloy, tin alloy, silicon alloy, intermetallic compound, organic compound, inorganic compound, metal complex And organic polymer compounds.

  A negative electrode active material is used individually by 1 type or in combination of 2 or more types.

  The number average particle diameter (primary particle diameter) of the negative electrode active material is preferably 0.1 μm to 100 μm, more preferably 1 μm to 10 μm. The number average particle size of the negative electrode active material is measured in the same manner as the number average particle size of the positive electrode active material.

  A negative electrode is obtained as follows, for example. That is, first, a negative electrode mixture-containing slurry is prepared by dispersing, in a solvent, a negative electrode mixture prepared by adding a conductive additive or a binder to the negative electrode active material as necessary. Here, the solid content concentration in the negative electrode mixture-containing slurry is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass. Next, this negative electrode mixture-containing slurry is applied to a negative electrode current collector and dried to form a negative electrode active material layer. A negative electrode mixture layer is formed by compressing the negative electrode active material layer obtained after drying with a roll press or the like. The negative electrode mixture thickness after compression is preferably 10 to 300 μm, more preferably 20 to 280 μm, and still more preferably 30 to 250 μm.

  Examples of the conductive aid include carbon black typified by graphite, acetylene black and ketjen black, and carbon fiber. The number average particle size (primary particle size) of the conductive assistant is preferably 10 nm to 10 μm, more preferably 20 nm to 1 μm, and is measured in the same manner as the number average particle size of the positive electrode active material. Examples of the binder include PVDF, PTFE, polyacrylic acid, styrene butadiene rubber, and fluorine rubber. Moreover, there is no restriction | limiting in particular as a solvent, Although a conventionally well-known thing may be used, For example, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, water etc. are mentioned.

  As a negative electrode electrical power collector, metal foils, such as copper foil, nickel foil, or stainless steel foil, are comprised, for example. Moreover, the carbon coat may be given or it may be processed into the mesh form. The thickness of the negative electrode current collector is preferably 5 to 40 μm, more preferably 6 to 35 μm, and still more preferably 7 to 30 μm.

<4. Separator>
The non-aqueous secondary battery of the present embodiment preferably includes a separator between the positive electrode and the negative electrode from the viewpoint of providing safety such as prevention of short circuit between the positive and negative electrodes and shutdown. The separator may be the same as that provided for a known non-aqueous secondary battery, and is preferably an insulating thin film having high ion permeability and excellent mechanical strength. Examples of the separator include a woven fabric, a nonwoven fabric, and a synthetic resin microporous membrane. Among these, a synthetic resin microporous membrane is preferable. As the synthetic resin microporous membrane, for example, a microporous membrane containing polyethylene or polypropylene as a main component or a polyolefin microporous membrane such as a microporous membrane containing both of these polyolefins is preferably used. As the nonwoven fabric, a porous film made of a heat-resistant resin such as ceramic, polyolefin, polyester, polyamide, liquid crystal polyester, or aramid is used.

  The separator may be a single microporous membrane or a laminate of a plurality of microporous membranes, or may be a laminate of two or more microporous membranes.

<5. Battery exterior>
Although the battery exterior in the non-aqueous secondary battery of this embodiment is not specifically limited, Any battery exterior of a battery can and a laminate film exterior body can also be used. As the battery can, for example, a metal can made of steel or aluminum can be used. As a laminate film exterior body, for example, two laminated films composed of a three-layer structure of heat-melting resin / metal film / resin are stacked with the heat-melting resin side facing inward, and the ends are sealed by heat sealing. Can be used. In addition, when using a laminate film exterior body, a positive electrode terminal (or a lead tab connected to the positive electrode terminal) and a negative electrode terminal (or a lead tab connected to the negative electrode terminal) are connected to the positive electrode current collector and the negative electrode current collector, respectively. The laminate film exterior body may be sealed with the end of the (or lead tab) being pulled out of the exterior body.

<6. Manufacturing method of battery>
The non-aqueous secondary battery of this embodiment is produced by a known method using the above-described non-aqueous electrolyte, positive electrode, negative electrode, and, if necessary, a separator. For example, a plurality of positive electrodes in which a positive electrode and a negative electrode are wound in a laminated state with a separator interposed therebetween to be formed into a laminate having a wound structure, or they are alternately laminated by bending or laminating a plurality of layers. Or a laminate in which a separator is interposed between the electrode and the negative electrode. Next, the laminated body is accommodated in a battery case (battery exterior), the electrolytic solution according to the present embodiment is injected into the case, and the laminated body is immersed in the electrolytic solution and sealed. A non-aqueous secondary battery having a configuration can be manufactured. Alternatively, an electrolyte membrane containing a gelled electrolyte solution is prepared in advance, and a positive electrode, a negative electrode, an electrolyte membrane, and a separator as necessary are formed by bending or stacking as described above, and then a battery case A non-aqueous secondary battery can also be produced by being housed inside. The shape of the non-aqueous secondary battery of the present embodiment is not particularly limited, and for example, a cylindrical shape, an elliptical shape, a rectangular tube shape, a button shape, a coin shape, a flat shape, a laminate shape, and the like are suitably employed.

  Although the non-aqueous secondary battery of this embodiment can function as a battery by the first charge, it is stabilized when a part of the non-aqueous electrolyte is decomposed during the first charge. Although there is no restriction | limiting in particular about the method of initial charge in this embodiment, It is preferable that initial charge is performed at 0.001-0.3C, It is more preferable to be performed at 0.002-0.25C, 0.003 It is particularly preferred to be carried out at ~ 0.2C. In addition, it is also preferable that the initial charging is performed via the constant voltage charging in the middle. In addition, the constant current which discharges rated capacity in 1 hour is 1C. By setting the voltage range in which the lithium salt is involved in the electrochemical reaction to be long, SEI is formed on the electrode surface, which has an effect of suppressing an increase in internal resistance including the positive electrode. In addition, since the reaction product is not firmly fixed only on the negative electrode, and in some form it has a good effect on other members such as the positive electrode and the separator, the electrochemical property of the lithium salt dissolved in the electrolyte It is very effective to perform the first charge in consideration of the reaction.

  The non-aqueous secondary battery of this embodiment can also be used as a battery pack by connecting a plurality of non-aqueous secondary batteries in series or in parallel. In addition, from the viewpoint of managing the charge / discharge state of the battery pack, the operating voltage range per unit is preferably 2 to 5 V, more preferably 2.5 to 5 V, and 2.75 V to 5 V. It is particularly preferred.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said embodiment. The present invention can be variously modified without departing from the gist thereof.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. Various characteristics of the nonaqueous secondary battery were measured and evaluated as follows.

(1-1) Measurement of oxidation-reduction potential A redox shuttle agent was dissolved in acetonitrile at 0.005 mol / L and tetra-n-butylammonium perchlorate as a supporting electrolyte was dissolved at 0.1 mol / L, and nitrogen bubbling was performed until immediately before the measurement. Glassy carbon as the working electrode, Ag / Ag ⁺ as the reference electrode, and Pt wire as the counter electrode are immersed in the above solution, and the above three are placed in an electrochemical analyzer (product name “ALS610-2B” manufactured by BAS Co., Ltd.). An electrode was connected, and a value obtained by open circuit potential-time was defined as an initial potential. Thereafter, cyclic voltammetry measurement was performed to extract the electrode response while continuously changing the potential, with the potential sweep rate set to 0.1 V / sec, the sweep upper limit potential set to 1 V, and the sweep lower limit potential set to 0 V. The average value of the potential at which the oxidation current is maximized and the potential at which the reduction current is maximized was defined as the oxidation-reduction potential. The measurement potential was corrected to the ferrocene standard using the measurement result of the ferrocene standard solution, and further converted to the lithium standard (vs. Li / Li ⁺ ).

[Example 1]
10 mL of methanol and 1.45 g of orthoperiodic acid were placed in a 100 mL eggplant flask and stirred for 10 minutes. Thereafter, 3.20 g of iodine was added and the mixture was further stirred for 10 minutes. Next, 1.35 g of 1,4-dimethoxybenzene was added, followed by stirring at 70 ° C. for 4 hours. After completion of the reaction, the obtained solution was poured into a mixture of 2.50 g of Na ₂ S ₂ O ₅ and 25 mL of water and subjected to suction filtration. The resulting crude product was subjected to silica gel column chromatography (development). Solvent: Dichloromethane) to obtain 3.31 g (yield 85%) of 1,4-dimethoxy-2,5-diiodobenzene as an intermediate product of a light orange solid. Formation of an intermediate product was confirmed by mass spectrum and ¹ H-NMR.

Under a nitrogen atmosphere, in a 100 mL two-necked eggplant flask, 1.56 g of 1,4-dimethoxy-2,5-diiodobenzene, 4.35 g of sodium trifluoroacetate, 3.05 g of copper iodide, and 30 mL of N, N -Dimethylacetamide was added and refluxed at 150 ° C. The obtained solution was cooled and filtered, then separated with dichloromethane and water, washed with water, the organic solvent was recovered, and dried over anhydrous sodium sulfate. After removing the solvent, the obtained crude product was purified by silica gel column chromatography (developing solvent: dichloromethane) to obtain 0.903 g (yield: 82.0%) of the desired product as a white solid. Formation of 1,4-dimethoxy-2,5-bis (trifluoromethyl) benzene was confirmed by mass spectrum and ¹ H-NMR. The identification results were as follows.
¹ H NMR (CDCl ₃ , TMS, 300 MHz): δ (ppm) = 3.827 (s, 6H, H _Me ), 7.194 (s, 2H, H _Ph )

When this compound was used as a redox shuttle agent, the redox potential was measured by the method described in (1-1) above. As a result, the redox potential was 4.7 V vs. Li / Li ⁺ .

[Comparative Example 1]
Under a nitrogen atmosphere, 1.78 g of 2,5-di-tert-butylhydroquinone, 2.53 g of potassium carbonate, 150 μL of tri-tert-butylamine, and 25 mL of acetone are placed in a 200 mL three-necked eggplant flask. 27 mL of 2,2,2-trifluoroethyl perfluorobutyl sulfonate was added dropwise over 2 hours and stirred at 60 ° C. for 24 hours. Thereafter, 40 mL of water was added to stop the reaction, and acetone was removed by concentration under reduced pressure. After cooling, the crude product obtained by suction filtration and drying was purified by silica gel column chromatography (developing solvent: chloroform: n-hexane = 1: 10) to give 0.652 g of the desired product as a white solid (yield 21). 0.1%). Formation of 1,4-di-tert-butyl-2,5-bis (2,2,2-trifluoroethoxy) benzene was confirmed by mass spectrum and ¹ H-NMR.

When this compound was used as a redox shuttle agent, the redox potential was measured by the method described in (1-1) above. As a result, the redox potential was 4.3 V vs. Li / Li ⁺ .

  The redox shuttle agent for non-aqueous secondary battery, non-aqueous electrolyte, and non-aqueous secondary battery of the present invention include, for example, a hybrid vehicle, a plug-in hybrid in addition to portable devices such as a mobile phone, a portable audio, a personal computer, and an IC tag. It is also expected to be used in rechargeable batteries for automobiles such as automobiles and electric cars, as well as residential power storage systems.

  DESCRIPTION OF SYMBOLS 100 ... Lithium ion secondary battery, 110 ... Separator, 120 ... Positive electrode, 130 ... Negative electrode, 140 ... Positive electrode collector, 150 ... Negative electrode collector, 160 ... Battery exterior.

Claims (3)

The redox shuttle agent for non-aqueous secondary batteries which consists of a compound represented by following General formula (1).

(In the formula (1), the plurality of substituents represented by R ¹ are methyl groups .) The electrolyte solution for non-aqueous secondary batteries containing the compound represented by following General formula (1).

(In the formula (1), the plurality of substituents represented by R ¹ are methyl groups .)   A non-aqueous secondary battery comprising the non-aqueous electrolyte solution according to claim 2, a positive electrode, and a negative electrode.

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