WO2015045389A1

WO2015045389A1 - Electrolyte solution for electricity storage devices such as batteries and capacitors containing salt, wherein alkali metal, alkaline earth metal or aluminum serves as cations, and organic solvent having hetero element, method for producing same, and capacitor provided with said electrolyte solution

Info

Publication number: WO2015045389A1
Application number: PCT/JP2014/004913
Authority: WO
Inventors: 山田　淳夫; 裕貴山田; 智之河合; 雄紀長谷川; 佳浩中垣; 浩平間瀬; 三好　学; 淳一丹羽; 合田　信弘
Original assignee: 国立大学法人東京大学
Priority date: 2013-09-25
Filing date: 2014-09-25
Publication date: 2015-04-02

Abstract

Provided is an electrolyte solution wherein a metal salt and a solvent are present in novel states. An electrolyte solution according to the present invention contains a salt, wherein an alkali metal, an alkaline earth metal or aluminum serves as cations, and an organic solvent having a hetero element. This electrolyte solution is characterized in that with respect to the peak intensity ascribed to the organic solvent in a vibrational spectrum of the electrolyte solution, if Io is the original peak intensity of the organic solvent and Is is the intensity of a shifted peak of the organic solvent, Io and Is satisfy Is > Io.

Description

An electrolyte for a power storage device such as a battery or a capacitor, a salt containing an alkali metal, an alkaline earth metal or aluminum as a cation and an organic solvent having a hetero element, a method for producing the same, and a capacitor including the electrolyte

The present invention relates to an electrolytic solution for a power storage device such as a battery or a capacitor, a salt containing an alkali metal, alkaline earth metal or aluminum as a cation and an organic solvent having a hetero element, a method for producing the same, and the electrolytic solution. It is related with the capacitor which comprises.

Generally, a battery includes a positive electrode, a negative electrode, and an electrolytic solution as main components. An appropriate electrolyte is added to the electrolytic solution in an appropriate concentration range. For example, a lithium salt such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , CF ₃ SO ₃ Li, or (CF ₃ SO ₂ ) ₂ NLi is added as an electrolyte to the electrolyte solution of a lithium ion secondary battery. In general, the concentration of the lithium salt in the electrolytic solution is generally about 1 mol / L.

Actually, Patent Document 1 discloses a lithium ion secondary battery using an electrolytic solution containing LiPF ₆ at a concentration of 1 mol / L. Patent Document 2 discloses a lithium ion secondary battery using an electrolytic solution containing (CF ₃ SO ₂ ) ₂ NLi at a concentration of 1 mol / L. Here, the viscosity of the electrolyte solution described in

Patent Documents

1 and 2 is approximately 5 mPa · s or less.

In addition, for the purpose of improving the performance of the battery, researches for adding various additives to an electrolyte containing a lithium salt have been actively conducted.

For example, Patent Document 3 describes an electrolytic solution in which a small amount of a specific additive is added to an electrolytic solution containing LiPF ₆ at a concentration of 1 mol / L, and a lithium ion secondary battery using this electrolytic solution. Is disclosed. Patent Document 4 also describes an electrolytic solution in which a small amount of phenylglycidyl ether is added to an electrolytic solution containing LiPF ₆ at a concentration of 1 mol / L. A lithium ion secondary battery using this electrolytic solution is disclosed. It is disclosed. Here, the viscosity of the electrolyte solution described in

Patent Documents

3 and 4 is also approximately 5 mPa · s or less.

In general, a capacitor means a capacitor that stores electric charge or discharges electric charge by electrostatic capacity. The mechanism of charge and discharge of electricity in the capacitor is based on the adsorption and desorption of charges to and from the electrode. Since this mechanism of action does not involve an electrochemical reaction, the stability of the capacitor is high and the charge transfer in the capacitor is fast.

Some capacitors include an electrolytic solution, and an electric double layer capacitor is known as such a capacitor. In an electric double layer capacitor, when a potential difference occurs between the electrodes, the anion of the electrolyte is aligned in a layered manner at the interface between the positive electrode and the electrolyte if it is the positive electrode; Liquid cations align in layers. These layer states have a capacitance, and this state is a charged state of the electric double layer capacitor.

In addition to the electric double layer capacitor, a lithium ion capacitor having an improved operating voltage is known as a capacitor having an electrolytic solution. In the lithium ion capacitor, the positive electrode is the same electrode as the electric double layer capacitor, the negative electrode is an electrode made of the same material as the negative electrode of the lithium ion secondary battery, and the electrolyte is for a general lithium ion secondary battery. It means a capacitor that is an electrolytic solution. The negative electrode of the lithium ion capacitor has a high electric capacity because the potential of the negative electrode is lowered by pre-doping in which lithium ions are previously doped.

When charging / discharging the lithium ion capacitor, some of the lithium ions pre-doped on the negative electrode are reversibly doped and dedoped, that is, inserted and desorbed. That is, it can be said that an electrochemical reaction (battery reaction) equivalent to that of the lithium ion secondary battery occurs between the negative electrode of the lithium ion capacitor and the electrolytic solution. On the other hand, charge adsorption / desorption unique to the capacitor occurs between the positive electrode and the electrolytic solution.

The electric capacity (J) that can be used in the capacitor is determined by (electrode capacity) × (voltage) × (voltage) / 2. In order to increase the electric capacity, means for using a material having a large specific surface area for the electrode, means for using an organic solvent-containing electrolyte as the electrolyte, and the like have been studied.

As a specific example of the above means, many attempts have been made to increase the capacity of the electrode by increasing the specific surface area of the carbon material used for the electrode and increasing the charge adsorption sites.

Further, as specific means focusing on the electrolytic solution, capacitors using an ionic liquid as the electrolytic solution are disclosed in Patent Documents 5 to 9. In addition, as disclosed in Patent Documents 10 and 11, the electrolytes of conventional capacitors and lithium ion capacitors include LiPF ₆ and (C ₂ H ₅ ) at a concentration of about 1 mol / L in a solvent such as propylene carbonate. ₄ A solution in which NBF ₄ was dissolved was generally used.

JP 2013-149477 A JP 2013-134922 A JP 2013-145724 A JP 2013-137873 A JP 2004-111294 A JP 2008-10613 A International Publication No. 2004/019356 International Publication No. 2004/027789 International Publication No. 2005/076299 JP-A-11-31637 Japanese Patent Laid-Open No. 10-27733

As described in Patent Documents 1 to 4, it has been common technical knowledge that an electrolyte used in a lithium ion secondary battery conventionally contains a lithium salt at a concentration of approximately 1 mol / L. As described in Patent Documents 3 to 4, the improvement of the electrolytic solution is generally performed by paying attention to an additive separate from the lithium salt.

Contrary to such conventional technical common sense, one aspect of the present invention focuses on the relationship between a metal salt and a solvent in the electrolytic solution, and the electrolytic solution in which the metal salt and the solvent are present in a new state and a method for producing the same The purpose is to provide.

Unlike the conventional points of interest of those skilled in the art, one embodiment of the present invention focuses on the relationship between the density and concentration of the electrolytic solution, and aims to provide a suitable group of electrolytic solutions.

One aspect of the present invention focuses on the viscosity of the electrolytic solution itself, and an object thereof is to provide an electrolytic solution having a viscosity range that has not been conventionally employed.

The ionic liquid is composed of a cation having a large ionic radius and an anion having a large ionic radius, and is in a liquid state at room temperature. Since the electrolyte solution made of an ionic liquid consists only of ions, the ionic concentration of the electrolyte solution made of an ionic liquid is high when compared with an electrolyte solution of the same capacity. For this reason, the capacitance of the capacitor including the electrolytic solution made of the ionic liquid is high because the ionic concentration of the electrolytic solution is high despite the large ionic radius of the ionic liquid. In comparison, there is no fading.

However, there is a limit to the electric capacity of the capacitor equipped with the electrolytic solution made of ionic liquid. Thus, new means for improving the electric capacity of the capacitor have been sought.

One embodiment of the present invention has been made in view of such circumstances, and an object thereof is to provide a capacitor including an electrolytic solution in which a metal salt and a solvent are present in a new state.

The present inventor has intensively studied through many trials and errors. And this inventor discovered that the electrolyte solution which added lithium salt as electrolyte more than usual maintains a solution state contrary to technical common sense. And this inventor discovered that such electrolyte solution acted suitably as electrolyte solution of a battery. Furthermore, when the present inventor has analyzed the above electrolytic solution, it has been found that an electrolytic solution showing a specific relationship in a peak observed in an IR spectrum or a Raman spectrum is particularly advantageous as an electrolytic solution for a battery. One aspect of the invention has been completed.

An electrolytic solution of one embodiment of the present invention is an electrolytic solution containing a salt having alkali metal, alkaline earth metal, or aluminum as a cation and an organic solvent having a hetero element, and the organic solvent in the vibrational spectrum of the electrolytic solution With respect to the derived peak intensity, if the intensity of the original peak of the organic solvent is Io and the intensity of the peak shifted from the original peak of the organic solvent is Is, Is> Io.

In the method for producing an electrolytic solution of one embodiment of the present invention, an organic solvent having a hetero element and a salt having alkali metal, alkaline earth metal, or aluminum as a cation are mixed, the salt is dissolved, and the first electrolysis is performed. A first dissolving step for preparing a solution, and a second dissolving step for adding a salt to the first electrolyte solution under stirring and / or heating conditions to dissolve the salt to prepare a supersaturated second electrolyte solution And a third dissolution step of adding the salt to the second electrolyte solution under stirring and / or heating conditions to dissolve the salt to prepare a third electrolyte solution.

The present inventor conducted intensive studies through many trials and errors without being bound by conventional common general knowledge. As a result, the present inventor has found many suitable ones among electrolytes composed of metal salts and organic solvents, particularly those suitable as electrolytes for lithium ion secondary batteries. Here, the present inventor does not depend on the type of the metal salt and the type of the organic solvent for the relationship between the suitable electrolytic solution and the conventional electrolytic solution, and finds a unique law that depends on the concentration of the metal salt. The attempt was unsuccessful. That is, no linearity regarding the metal salt concentration independent of the type of metal salt and the type of organic solvent was found. Therefore, the present inventor has conducted further studies, and surprisingly, a group of electrolytes having a specific relationship between density and concentration works favorably as a battery electrolyte compared to conventional electrolytes. As a result, one embodiment of the present invention has been completed.

An electrolytic solution of one embodiment of the present invention is an electrolytic solution including a salt having an alkali metal, an alkaline earth metal, or aluminum as a cation and an organic solvent having a hetero element, and the density d (g / cm of the electrolytic solution) ³ ) d / c obtained by dividing the electrolyte concentration by the salt concentration c (mol / L) is 0.15 ≦ d / c ≦ 0.71.

As described above, the present inventor has discovered that an electrolytic solution to which a specific lithium salt is added more than usual maintains a solution state. And this inventor discovered that such electrolyte solution was high viscosity compared with the conventional electrolyte solution, and showed ion conductivity. Furthermore, when the present inventor has analyzed the above electrolytic solution, it has been found that an electrolytic solution exhibiting a specific relationship in viscosity and ionic conductivity is particularly advantageous as an electrolytic solution for a battery. It came to be completed.

An electrolytic solution of one embodiment of the present invention is an electrolytic solution including a salt having an alkali metal, an alkaline earth metal, or aluminum as a cation, and an organic solvent having a hetero element, and the viscosity of the electrolytic solution η (mPa · s ) Is 10 <η <500, and the ionic conductivity σ (mS / cm) of the electrolytic solution is 1 ≦ σ.

As described above, the present inventor has discovered that an electrolytic solution in which a lithium salt as an electrolyte is added more than usual maintains a solution state against technical common sense. And this inventor discovered that such electrolyte solution acted suitably as electrolyte solution of a capacitor. Furthermore, when the present inventor analyzed the above electrolytic solution, it was found that an electrolytic solution exhibiting a specific relationship in a peak observed in an IR spectrum or a Raman spectrum is particularly advantageous as an electrolytic solution of a capacitor. One aspect of the invention has been completed.

The capacitor of the present invention is a capacitor comprising an electrolytic solution containing a salt having alkali metal, alkaline earth metal or aluminum as a cation, and an organic solvent having a hetero element, wherein the electrolytic solution has a vibration spectroscopy spectrum. Regarding the peak intensity derived from the organic solvent, if the intensity of the original peak of the organic solvent is Io and the intensity of the peak shifted from the peak is Is, Is> Io.

The novel electrolytic solution of each aspect of the present invention can improve various battery characteristics. Moreover, the novel capacitor of the present invention exhibits a suitable capacitance.

4 is an IR spectrum of the electrolytic solution of Example 4. 4 is an IR spectrum of the electrolytic solution of Example 3. It is IR spectrum of the electrolyte solution of Example 14. It is IR spectrum of the electrolyte solution of Example 13. 4 is an IR spectrum of the electrolytic solution of Example 11. 7 is an IR spectrum of an electrolytic solution of Comparative Example 7. It is IR spectrum of the electrolyte solution of the comparative example 14. It is IR spectrum of acetonitrile. It is an IR spectrum of (CF ₃ SO ₂ ) ₂ NLi. It is an IR spectrum of (FSO ₂ ) ₂ NLi (2100 to 2400 cm ⁻¹ ). It is IR spectrum of the electrolyte solution of Example 15. It is IR spectrum of the electrolyte solution of Example 16. It is IR spectrum of the electrolyte solution of Example 17. It is IR spectrum of the electrolyte solution of Example 18. 14 is an IR spectrum of the electrolytic solution of Example 19. 14 is an IR spectrum of an electrolytic solution of Comparative Example 15. It is IR spectrum of dimethyl carbonate. It is IR spectrum of the electrolyte solution of Example 20. 2 is an IR spectrum of the electrolytic solution of Example 21. It is IR spectrum of the electrolyte solution of Example 22. 14 is an IR spectrum of an electrolytic solution of Comparative Example 16. It is IR spectrum of ethyl methyl carbonate. It is IR spectrum of the electrolyte solution of Example 23. It is IR spectrum of the electrolyte solution of Example 24. It is IR spectrum of the electrolyte solution of Example 25. 14 is an IR spectrum of an electrolytic solution of Comparative Example 17. It is IR spectrum of diethyl carbonate. It is an IR spectrum of (FSO ₂ ) ₂ NLi (1900-1600 cm ⁻¹ ). It is IR spectrum of the electrolyte solution of Example 26. 4 is an IR spectrum of the electrolytic solution of Example 27. It is a Raman spectrum of the electrolyte solution of Example 12. It is a Raman spectrum of the electrolyte solution of Example 13. It is a Raman spectrum of the electrolyte solution of the comparative example 14. It is a Raman spectrum of the electrolyte solution of Example 15. It is a Raman spectrum of the electrolyte solution of Example 17. It is a Raman spectrum of the electrolyte solution of Example 19. It is a Raman spectrum of the electrolyte solution of the comparative example 15. It is a result of the responsiveness with respect to repetition of the rapid charge / discharge of Evaluation Example 10. It is a DSC chart at the time of making the positive electrode and electrolyte solution of the charging state of the lithium ion secondary battery of Example B in Evaluation Example 11 coexist. It is a DSC chart at the time of making the positive electrode and electrolyte solution of the charge state of the lithium ion secondary battery of the comparative example B in Evaluation Example 11 coexist. It is a charging / discharging curve of the half cell of Example E. It is a charging / discharging curve of the half cell of Example F. It is a charging / discharging curve of the half cell of Example G. It is a charging / discharging curve of the half cell of Example H. It is a charging / discharging curve of the half cell of the comparative example E. 6 is a graph showing a relationship between a potential (3.1 to 4.6 V) and a response current with respect to the half cell of Example I. 6 is a graph showing a relationship between a potential (3.1 to 5.1 V) and a response current with respect to the half cell of Example I. 10 is a graph showing a relationship between a potential (3.1 to 4.6 V) and a response current with respect to the half cell of Example J. 6 is a graph showing a relationship between a potential (3.1 to 5.1 V) and a response current with respect to the half cell of Example J. 6 is a graph showing a relationship between a potential (3.1 to 4.6 V) and a response current with respect to the half cell of Example L. 6 is a graph showing a relationship between a potential (3.1 to 5.1 V) and a response current with respect to the half cell of Example L. 6 is a graph showing a relationship between a potential (3.1 to 4.6 V) and a response current with respect to the half cell of Example M. 10 is a graph showing a relationship between a potential (3.1 to 5.1 V) and a response current with respect to the half cell of Example M. 10 is a graph showing the relationship between the potential (3.1 to 4.6 V) and the response current with respect to the half cell of Comparative Example F. 6 is a graph showing a relationship between a potential (3.0 to 4.5 V) and a response current with respect to the half cell of Example J. 10 is a graph showing a relationship between a potential (3.0 to 5.0 V) and a response current with respect to the half cell of Example J. 6 is a graph showing the relationship between the potential (3.0 to 4.5 V) and the response current with respect to the half cell of Example K. 6 is a graph showing a relationship between a potential (3.0 to 5.0 V) and a response current with respect to the half cell of Example K. 10 is a graph showing a relationship between a potential (3.0 to 4.5 V) and a response current with respect to the half cell of Comparative Example G. 10 is a graph showing a relationship between a potential (3.0 to 5.0 V) and a response current with respect to the half cell of Comparative Example G. It is a graph which shows the voltage curve of the lithium ion secondary battery of Example N in each current rate. It is a graph which shows the voltage curve of the lithium ion secondary battery of the comparative example H in each current rate. It is a complex impedance plane plot of the battery in the evaluation example 18. It is a charging / discharging curve of the capacitor of Example R and Comparative Example J. It is a charging / discharging curve of the capacitor of Example S and Comparative Example K. 6 is a charge / discharge curve of a capacitor of Example S at a cut-off voltage of 0 to 2V. 6 is a charge / discharge curve of the capacitor of Example S at a cut-off voltage of 0 to 2.5V. 6 is a charge / discharge curve of the capacitor of Example S at a cut-off voltage of 0 to 3V. It is a discharge curve of the capacitor of Example S at each cut-off voltage. It is a charging / discharging curve of the lithium ion capacitor of Example T.

Hereinafter, modes for carrying out the present invention will be described. Unless otherwise specified, the numerical range “a to b” described in this specification includes the lower limit “a” and the upper limit “b”. The numerical range can be configured by arbitrarily combining these upper limit value and lower limit value and the numerical values listed in the examples. Furthermore, numerical values arbitrarily selected from the numerical value range can be used as upper and lower numerical values.

An electrolytic solution of one embodiment of the present invention is an electrolytic solution containing a salt having alkali metal, alkaline earth metal, or aluminum as a cation and an organic solvent having a hetero element, and the organic solvent in the vibrational spectrum of the electrolytic solution With regard to the derived peak intensity, if the peak intensity at the peak wave number inherent to the organic solvent is Io, and the peak intensity where the peak inherent to the organic solvent is shifted is Is, Is> Io.

In the conventional electrolytic solution, the relationship between Is and Io is Is <Io.

In addition, the conventional general electrolyte does not satisfy the above relationships.

The capacitor of the present invention is a capacitor comprising an electrolytic solution containing a salt having alkali metal, alkaline earth metal or aluminum as a cation, and an organic solvent having a hetero element, wherein the electrolytic solution has a vibration spectroscopy spectrum. With respect to the peak intensity derived from the organic solvent, if the peak intensity at the original peak wave number of the organic solvent is Io, and the peak intensity at which the peak is wave number shifted is Is, Is> Io.

Hereinafter, “a salt having an alkali metal, an alkaline earth metal or aluminum as a cation” may be referred to as a “metal salt” or simply “salt”, and the electrolytic solution of each aspect of the present invention is collectively referred to as “the electrolytic solution of the present invention”. There are times.

The metal salt may be a compound that is used as an electrolyte, such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiAlCl ₄ or the like, which is usually contained in the electrolyte solution of a battery or capacitor. Examples of the cation of the metal salt include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium, and aluminum. The cation of the metal salt is preferably the same metal ion as the charge carrier of the battery using the electrolytic solution. For example, if the electrolytic solution of the present invention is used as an electrolytic solution for a lithium ion secondary battery, the metal salt cation is preferably lithium.

The chemical structure of the anion of the salt may include at least one element selected from halogen, boron, nitrogen, oxygen, sulfur or carbon. Specific examples of the chemical structure of an anion containing halogen or boron include ClO ₄ , PF ₆ , AsF ₆ , SbF ₆ , TaF ₆ , BF ₄ , SiF ₆ , B (C ₆ H ₅ ) ₄ , and B (oxalate). ₂ , Cl, Br, and I.

The chemical structure of an anion containing nitrogen, oxygen, sulfur or carbon will be specifically described below.

The chemical structure of the salt anion is preferably a chemical structure represented by the following general formula (1), general formula (2), or general formula (3).

(R ¹ X ¹ ) (R ² X ² ) N General formula (1)
(R ¹ is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted with, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, or an alkoxy group which may be substituted with a substituent , An unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, an unsaturated thioalkoxy group that may be substituted with a substituent, CN, SCN, or OCN Is done.
R ² represents hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, an alkoxy group which may be substituted with a substituent, Selected from an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, CN, SCN, OCN The
R ¹ and R ² may be bonded to each other to form a ring.
X ¹ is selected from SO ₂ , C = O, C = S, R ^a P = O, R ^b P = S, S = O, Si = O.
X ² _{^{is, SO 2, C = O,}} C = S, R c P = O, R d P = S, S = O, is selected from Si = O.
R ^a , R ^b , R ^c , and R ^d are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a substituent. An unsaturated alkyl group which may be substituted, an unsaturated cycloalkyl group which may be substituted with a substituent, an aromatic group which may be substituted with a substituent, or a heterocyclic group which may be substituted with a substituent , An alkoxy group that may be substituted with a substituent, an unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, and a non-optionally substituted substituent. Selected from saturated thioalkoxy groups, OH, SH, CN, SCN, OCN.
R ^a , R ^b , R ^c , and R ^d may be bonded to R ¹ or R ² to form a ring. )

R ³ X ³ Y General formula (2)
(R ³ is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted with, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, or an alkoxy group which may be substituted with a substituent , An unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, an unsaturated thioalkoxy group that may be substituted with a substituent, CN, SCN, or OCN Is done.
X ³ is selected from SO ₂ , C = O, C = S, R ^e P = O, R ^f P = S, S = O, and Si = O.
R ^e and R ^f are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a group that may be substituted with a substituent. A saturated alkyl group, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, a heterocyclic group that may be substituted with a substituent, and a substituent An alkoxy group which may be substituted, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, OH , SH, CN, SCN, and OCN.
R ^e and R ^f may combine with R ³ to form a ring.
Y is selected from O and S. )

^{^{^{^{(R 4 X 4) (R}}}} 5 X 5) (R 6 X 6) C Formula (3)
(R ⁴ is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted with, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, or an alkoxy group which may be substituted with a substituent , An unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, an unsaturated thioalkoxy group that may be substituted with a substituent, CN, SCN, or OCN Is done.
R ⁵ represents hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, an alkoxy group which may be substituted with a substituent, Selected from an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, CN, SCN, OCN The
R ⁶ is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, an alkoxy group which may be substituted with a substituent, Selected from an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, CN, SCN, OCN The
Further, any two or three of R ⁴ , R ⁵ and R ⁶ may be bonded to form a ring.
X ⁴ _{^{is, SO 2, C = O,}} C = S, R g P = O, R h P = S, S = O, is selected from Si = O.
X ⁵ is selected from SO ₂ , C = O, C = S, R ⁱ P = O, R ^j P = S, S = O, Si = O.
X ⁶ is selected from SO ₂ , C = O, C = S, R ^k P = O, R ¹ P = S, S = O, Si = O.
R ^g , R ^h , R ⁱ , R ^j , R ^k , and R ^l are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, or a cycloalkyl that may be substituted with a substituent. Group, an unsaturated alkyl group that may be substituted with a substituent, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, or a substituent that is substituted with a substituent A heterocyclic group which may be substituted, an alkoxy group which may be substituted with a substituent, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, and a substituent It is selected from an unsaturated thioalkoxy group which may be substituted, OH, SH, CN, SCN, OCN.
R ^g , R ^h , R ⁱ , R ^j , R ^k , and R ^l may combine with R ⁴ , R ^5, or R ⁶ to form a ring. )

The term “may be substituted with a substituent” in the chemical structure represented by the general formulas (1) to (3) will be described. For example, in the case of “an alkyl group that may be substituted with a substituent”, an alkyl group in which one or more of the hydrogens of the alkyl group are substituted with a substituent, or an alkyl group that does not have a particular substituent Means.

Examples of the substituent in the phrase “may be substituted with a substituent” include an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an unsaturated cycloalkyl group, an aromatic group, a heterocyclic group, a halogen, and OH. SH, CN, SCN, OCN, nitro group, alkoxy group, unsaturated alkoxy group, amino group, alkylamino group, dialkylamino group, aryloxy group, acyl group, alkoxycarbonyl group, acyloxy group, aryloxycarbonyl group, Acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, sulfinyl group, ureido group, phosphoric acid amide group, sulfo group, carboxyl group, Hydroxamic acid group Sulfino group, a hydrazino group, an imino group, and a silyl group. These substituents may be further substituted. When there are two or more substituents, the substituents may be the same or different.

The chemical structure of the salt anion is more preferably a chemical structure represented by the following general formula (4), general formula (5), or general formula (6).

(R ⁷ X ⁷ ) (R ⁸ X ⁸ ) N General formula (4)
(R ⁷ and R ⁸ are each independently C _n H _a F _b Cl _c Br _d I _e (CN) _f (SCN) _g (OCN) _h .
n, a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e + f + g + h.
R ⁷ and R ⁸ may combine with each other to form a ring, in which case 2n = a + b + c + d + e + f + g + h is satisfied.
X ⁷ _{^{is, SO 2, C = O,}} C = S, R m P = O, R n P = S, S = O, is selected from Si = O.
X ⁸ is selected from SO ₂ , C = O, C = S, R ^o P = O, R ^p P = S, S = O, Si = O.
R ^m , R ⁿ , R ^o , and R ^p are each independently substituted with hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a substituent. An unsaturated alkyl group which may be substituted, an unsaturated cycloalkyl group which may be substituted with a substituent, an aromatic group which may be substituted with a substituent, or a heterocyclic group which may be substituted with a substituent , An alkoxy group that may be substituted with a substituent, an unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, and a non-optionally substituted substituent. Selected from saturated thioalkoxy groups, OH, SH, CN, SCN, OCN.
R ^m , R ⁿ , R ^o , and R ^p may combine with R ⁷ or R ⁸ to form a ring. )

R ⁹ X ⁹ Y General formula (5)
^{(R 9} _is a _{_{_{_{C n H a F b Cl c}}}} Br d I e (CN) f (SCN) g (OCN) h.
n, a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e + f + g + h.
X ⁹ _{^{is, SO 2, C = O,}} C = S, R q P = O, R r P = S, S = O, is selected from Si = O.
R ^q and R ^r are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a group that may be substituted with a substituent. A saturated alkyl group, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, a heterocyclic group that may be substituted with a substituent, and a substituent An alkoxy group which may be substituted, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, OH , SH, CN, SCN, and OCN.
R ^q and R ^r may combine with R ⁹ to form a ring.
Y is selected from O and S. )

(R ¹⁰ X ¹⁰ ) (R ¹¹ X ¹¹ ) (R ¹² X ¹² ) C General formula (6)
(R ¹⁰ , R ¹¹ , and R ¹² are each independently C _n H _a F _b Cl _c Br _d I _e (CN) _f (SCN) _g (OCN) _h .
n, a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e + f + g + h.
Any two of R ¹⁰ , R ¹¹ , and R ¹² may combine to form a ring, in which case the group forming the ring satisfies 2n = a + b + c + d + e + f + g + h. Three of R ¹⁰ , R ¹¹ , and R ¹² may combine to form a ring, in which case two of the three satisfy 2n = a + b + c + d + e + f + g + h, and one group satisfies 2n−1 = a + b + c + d + e + f + g + h. Fulfill.
X ¹⁰ _{^{is, SO 2, C = O,}} C = S, R s P = O, R t P = S, S = O, is selected from Si = O.
X ¹¹ _{^{is, SO 2, C = O,}} C = S, R u P = O, R v P = S, S = O, is selected from Si = O.
X ¹² _{^{is, SO 2, C = O,}} C = S, R w P = O, R x P = S, S = O, is selected from Si = O.
R ^s , R ^t , R ^u , R ^v , R ^w , and R ^x are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, or a cycloalkyl that may be substituted with a substituent. Group, an unsaturated alkyl group that may be substituted with a substituent, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, or a substituent that is substituted with a substituent A heterocyclic group which may be substituted, an alkoxy group which may be substituted with a substituent, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, and a substituent It is selected from an unsaturated thioalkoxy group which may be substituted, OH, SH, CN, SCN, OCN.
R ^s , R ^t , R ^u , R ^v , R ^w , and R ^x may combine with R ¹⁰ , R ^11, or R ¹² to form a ring. )

The meaning of the phrase “may be substituted with a substituent” in the chemical structures represented by the general formulas (4) to (6) has been explained in the general formulas (1) to (3). It is synonymous with.

In the chemical structures represented by the general formulas (4) to (6), n is preferably an integer of 0 to 6, more preferably an integer of 0 to 4, and particularly preferably an integer of 0 to 2. In the chemical structures represented by the above general formulas (4) to (6), when R ⁷ and R ⁸ are bonded, or R ¹⁰ , R ¹¹ , and R ¹² are bonded to form a ring. In the formula, n is preferably an integer of 1 to 8, more preferably an integer of 1 to 7, and particularly preferably an integer of 1 to 3.

The chemical structure of the salt anion is more preferably represented by the following general formula (7), general formula (8) or general formula (9).

(R ¹³ SO ₂ ) (R ¹⁴ SO ₂ ) N General formula (7)
(R ¹³ and R ¹⁴ are each independently C _n H _a F _b Cl _c Br _d I _e .
n, a, b, c, d, and e are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e.
R ¹³ and R ¹⁴ may combine with each other to form a ring, in which case 2n = a + b + c + d + e is satisfied. )

R ¹⁵ SO ₃ general formula (8)
^{(R 15} _is a _{_{_{C n H a F b Cl c}}} Br d I e.
n, a, b, c, d, and e are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e. )

(R ¹⁶ SO ₂ ) (R ¹⁷ SO ₂ ) (R ¹⁸ SO ₂ ) C General formula (9)
(R ¹⁶ , R ¹⁷ , and R ¹⁸ are each independently C _n H _a F _b Cl _c Br _d I _e .
n, a, b, c, d, and e are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e.
Any two of R ¹⁶ , R ¹⁷ , and R ¹⁸ may combine to form a ring, in which case the group forming the ring satisfies 2n = a + b + c + d + e. Three of R ¹⁶ , R ¹⁷ and R ¹⁸ may combine to form a ring, in which case two groups out of the three satisfy 2n = a + b + c + d + e, and one group satisfies 2n−1 = a + b + c + d + e. Fulfill. )
In the chemical structures represented by the general formulas (7) to (9), n is preferably an integer of 0 to 6, more preferably an integer of 0 to 4, and particularly preferably an integer of 0 to 2. In the chemical structures represented by the above general formulas (7) to (9), when R ¹³ and R ¹⁴ are bonded or R ¹⁶ , R ¹⁷ , and R ¹⁸ are bonded to form a ring. In the formula, n is preferably an integer of 1 to 8, more preferably an integer of 1 to 7, and particularly preferably an integer of 1 to 3.

In the chemical structures represented by the general formulas (7) to (9), those in which a, c, d, and e are 0 are preferable.

The metal salt is (CF ₃ SO ₂ ) ₂ NLi (hereinafter sometimes referred to as “LiTFSA”), (FSO ₂ ) ₂ NLi (hereinafter sometimes referred to as “LiFSA”), (C ₂ F ₅ SO ₂ ) ₂ NLi, FSO ₂ (CF ₃ SO ₂ ) NLi, (SO ₂ CF ₂ CF ₂ SO ₂ ) NLi, (SO ₂ CF ₂ CF ₂ CF ₂ SO ₂ ) NLi, FSO ₂ (CH ₃ SO ₂ ) NLi FSO ₂ (C ₂ F ₅ SO ₂ ) NLi or FSO ₂ (C ₂ H ₅ SO ₂ ) NLi is particularly preferred.

The metal salt of the present invention may be a combination of an appropriate number of cations and anions described above. One kind of metal salt in the electrolytic solution of the present invention may be used, or a plurality of kinds may be used in combination.

As the organic solvent having a hetero element, an organic solvent in which the hetero element is at least one selected from nitrogen, oxygen, sulfur and halogen is preferable, and an organic solvent in which the hetero element is at least one selected from nitrogen or oxygen Is more preferable. As the organic solvent having a hetero element, an aprotic solvent having no proton donating group such as NH group, NH ₂ group, OH group, and SH group is preferable.

Specific examples of the organic solvent having a hetero element (hereinafter sometimes simply referred to as “organic solvent”) include nitriles such as acetonitrile, propionitrile, acrylonitrile, malononitrile, 1,2-dimethoxyethane, 1, 2-diethoxyethane, tetrahydrofuran, 1,2-dioxane, 1,3-dioxane, 1,4-dioxane, 2,2-dimethyl-1,3-dioxolane, 2-methyltetrahydropyran, 2-methyltetrahydrofuran, crown Ethers such as ether, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolide Amides such as isopropyl isocyanate, n-propyl isocyanate, chloromethyl isocyanate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl formate, ethyl formate, vinyl acetate, methyl acrylate, methyl methacrylate, etc. Esters, glycidyl methyl ether, epoxy butane, epoxy such as 2-ethyloxirane, oxazole, 2-ethyloxazole, oxazoline, oxazole such as 2-methyl-2-oxazoline, ketone such as acetone, methyl ethyl ketone, methyl isobutyl ketone Acid anhydrides such as acetic anhydride and propionic anhydride, sulfones such as dimethyl sulfone and sulfolane, sulfoxides such as dimethyl sulfoxide, 1-nitropropane and 2-nitrate Nitros such as propane, furans such as furan and furfural, cyclic esters such as γ-butyrolactone, γ-valerolactone and δ-valerolactone, aromatic heterocycles such as thiophene and pyridine, tetrahydro-4-pyrone, Examples thereof include heterocyclic rings such as 1-methylpyrrolidine and N-methylmorpholine, and phosphate esters such as trimethyl phosphate and triethyl phosphate.

Examples of the organic solvent include chain carbonates represented by the following general formula (10).

R ¹⁹ OCOOR ²⁰ general formula (10)
(R ¹⁹ and R ²⁰ each independently represent C _n H _a F _b Cl _c Br _d I _e which is a chain alkyl, or C _m H _f F _g Cl _h Br _i I containing a cyclic alkyl in the chemical structure. .n selected from any of _{j, a, b, c,} d, e, m, f, g, h, i, j are each independently an integer of 0 or more, 2n + 1 = a + b + c + d + e, 2m = f + g + h + i + j Meet)

In the chain carbonate represented by the general formula (10), n is preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and particularly preferably an integer of 1 to 2. m is preferably an integer of 3 to 8, more preferably an integer of 4 to 7, and particularly preferably an integer of 5 to 6. Among the chain carbonates represented by the general formula (10), dimethyl carbonate (hereinafter sometimes referred to as “DMC”), diethyl carbonate (hereinafter sometimes referred to as “DEC”), ethylmethyl Carbonate (hereinafter sometimes referred to as “EMC”) is particularly preferred.

As the organic solvent, a solvent having a relative dielectric constant of 20 or more or a donor ether oxygen is preferable. Examples of such an organic solvent include nitriles such as acetonitrile, propionitrile, acrylonitrile, and malononitrile, and 1,2-dimethoxyethane. 1,2-diethoxyethane, tetrahydrofuran, 1,2-dioxane, 1,3-dioxane, 1,4-dioxane, 2,2-dimethyl-1,3-dioxolane, 2-methyltetrahydropyran, 2-methyl Mention may be made of ethers such as tetrahydrofuran and crown ether, N, N-dimethylformamide, acetone, dimethyl sulfoxide and sulfolane, and in particular acetonitrile (hereinafter sometimes referred to as “AN”), 1,2-dimethoxyethane. (Hereafter referred to as “DME”. .) It is preferred.

These organic solvents may be used alone or in combination as an electrolyte.

For reference, the density (g / cm ³ ) of the organic solvent having a hetero element is listed in Table 1.

In the vibrational spectroscopic spectrum of the electrolyte solution of the present invention, the peak intensity derived from the organic solvent contained in the electrolyte solution is denoted by Io, and the peak of the organic solvent inherent peak is shifted (hereinafter, “ If the intensity of “shift peak” is sometimes referred to as “Is”, Is> Io. That is, in the vibrational spectral spectrum chart obtained by subjecting the electrolytic solution of the present invention to vibrational spectral measurement, the relationship between the two peak intensities is Is> Io.

Here, “the original peak of the organic solvent” means a peak observed at the peak position (wave number) when vibration spectroscopy measurement is performed only on the organic solvent. The value of the peak intensity Io inherent in the organic solvent and the value of the shift peak intensity Is are the height or area from the baseline of each peak in the vibrational spectrum.

In the vibrational spectroscopic spectrum of the electrolytic solution of the present invention, when there are a plurality of peaks in which the original peak of the organic solvent is shifted, the relationship may be determined based on the peak from which the relationship between Is and Io is most easily determined. In addition, when a plurality of organic solvents having heteroelements are used in the electrolytic solution of the present invention, an organic solvent that can determine the relationship between Is and Io most easily (the difference between Is and Io is most pronounced) is selected, The relationship between Is and Io may be determined based on the peak intensity. If the peak shift amount is small and the peaks before and after the shift appear to be a gentle mountain, peak separation may be performed using known means to determine the relationship between Is and Io.

Note that in the vibrational spectroscopic spectrum of an electrolytic solution using a plurality of organic solvents having a hetero element, the peak of an organic solvent that is most easily coordinated with a cation (hereinafter sometimes referred to as “preferred coordination solvent”) is another. Shift in preference to. In an electrolytic solution using a plurality of organic solvents having a hetero element, the mass% of the preferential coordination solvent with respect to the entire organic solvent having a hetero element is preferably 40% or more, more preferably 50% or more, and further preferably 60% or more. 80% or more is particularly preferable. Further, in the electrolytic solution using a plurality of organic solvents having a hetero element, the volume% of the preferential coordination solvent with respect to the entire organic solvent having a hetero element is preferably 40% or more, more preferably 50% or more, and 60% or more. Is more preferable, and 80% or more is particularly preferable.

The relationship between the two peak intensities in the vibrational spectrum of the electrolytic solution of the present invention preferably satisfies the condition of Is> 2 × Io, more preferably satisfies the condition of Is> 3 × Io, and Is> 5 × It is more preferable that the condition of Io is satisfied, and it is particularly preferable that the condition of Is> 7 × Io is satisfied. Most preferred is an electrolytic solution in which the intensity Io of the peak inherent in the organic solvent is not observed and the intensity Is of the shift peak is observed in the vibrational spectrum of the electrolytic solution of the present invention. In the electrolytic solution, it means that all the molecules of the organic solvent contained in the electrolytic solution are completely solvated with the metal salt. The electrolyte solution of the present invention is most preferably in a state where all the molecules of the organic solvent contained in the electrolyte solution are completely solvated with the metal salt (Io = 0 state).

In the electrolytic solution of the present invention, it is presumed that the metal salt and the organic solvent (or preferential coordination solvent) having a hetero element have an interaction. Specifically, a metal salt and a hetero element of an organic solvent (or preferential coordination solvent) having a hetero element form a coordination bond, and the organic salt (or preferential coordinating solvent) having a metal salt and a hetero element ) Is estimated to form a stable cluster. From the results of Examples described later, this cluster is presumed to be formed by coordination of two molecules of an organic solvent (or preferential coordination solvent) having a hetero element with one molecule of a metal salt. The Considering this point, the molar range of the organic solvent having a hetero element (or preferential coordination solvent) with respect to 1 mol of the metal salt in the electrolytic solution of the present invention is preferably 1.4 mol or more and less than 3.5 mol. More preferably, it is 0.5 mol or more and 3.1 mol or less, and 1.6 mol or more and 3 mol or less are still more preferable.

Theoretically, the capacitor electrolyte has a higher capacity when the salt concentration is higher. In consideration of these points, the molar range of the organic solvent (or preferential coordination solvent) having a hetero element with respect to 1 mol of the metal salt in the electrolytic solution of the present invention is preferably less than 3.5 mol, and 3.1 mol or less. Is more preferable, and 3 mol or less is still more preferable. As described above, it is preferable that the electrolytic solution of the capacitor has a higher salt concentration. However, the lower limit of the molar range of the organic solvent (or preferential coordination solvent) having a hetero element with respect to 1 mol of the metal salt in the electrolytic solution of the present invention is intentionally set. For example, 1.1 mol or more, 1.4 mol or more, 1.5 mol or more, 1.6 mol or more can be mentioned.

In the electrolytic solution of the present invention, it is presumed that clusters are generally formed by coordination of two molecules of an organic solvent (or preferential coordination solvent) having a hetero element to one molecule of a metal salt. The concentration (mol / L) of the electrolytic solution of the invention depends on the molecular weight of each of the metal salt and the organic solvent and the density when the solution is used. Therefore, it is not appropriate to prescribe the concentration of the electrolytic solution of the present invention.

The concentration (mol / L) of the electrolytic solution of the present invention is individually exemplified in Table 2.

The organic solvent that forms the cluster and the organic solvent that is not involved in the formation of the cluster have different environments. Therefore, in vibrational spectroscopy measurement, the peak derived from the organic solvent forming the cluster is higher than the observed wave number of the peak derived from the organic solvent not involved in the cluster formation (original peak of the organic solvent). Or it is observed shifted to the low wavenumber side. That is, the shift peak corresponds to the peak of the organic solvent forming the cluster.

Examples of the vibrational spectrum include an IR spectrum and a Raman spectrum. Examples of the measurement method for IR measurement include transmission measurement methods such as Nujol method and liquid film method, and reflection measurement methods such as ATR method. As to whether to select an IR spectrum or a Raman spectrum, a spectrum in which the relationship between Is and Io can be easily determined in the vibrational spectrum of the electrolytic solution of the present invention may be selected. The vibrational spectroscopic measurement is preferably performed under conditions that can reduce or ignore the influence of moisture in the atmosphere. For example, IR measurement may be performed under low humidity or no humidity conditions such as a dry room or a glove box, or Raman measurement may be performed with the electrolyte solution in a sealed container.

Here, the peak in the electrolytic solution of the present invention containing LiTFSA as the metal salt and acetonitrile as the organic solvent will be specifically described.

When only acetonitrile is measured by IR, a peak derived from the stretching vibration of the triple bond between C and N is usually observed in the vicinity of 2100 to 2400 cm ⁻¹ .

Here, it is assumed that LiTFSA is dissolved in an acetonitrile solvent at a concentration of 1 mol / L to obtain an electrolytic solution according to conventional technical common sense. Since 1 L of acetonitrile corresponds to about 19 mol, 1 L of conventional electrolyte includes 1 mol of LiTFSA and 19 mol of acetonitrile. Then, in the conventional electrolyte, there are many acetonitriles that are not solvated with LiTFSA (not coordinated with Li) simultaneously with acetonitrile that is solvated with LiTFSA (coordinated with Li). . Now, since the acetonitrile molecule is different between the LiTFSA solvated acetonitrile molecule and the LiTFSA non-solvated acetonitrile molecule, in the IR spectrum, the acetonitrile peaks of both are distinguished and observed. Is done. More specifically, the peak of acetonitrile that is not solvated with LiTFSA is observed at the same position (wave number) as in the case of IR measurement of only acetonitrile, but the peak of acetonitrile that is solvated with LiTFSA. Is observed with the peak position (wave number) shifted to the high wave number side.

Since there are many acetonitriles that are not solvated with LiTFSA in the concentration of the conventional electrolyte, in the vibrational spectrum of the conventional electrolyte, the peak intensity Io of the original acetonitrile and the peak of the original acetonitrile The relationship with the intensity Is of the peak shifted is Is <Io.

On the other hand, the electrolytic solution of the present invention has a higher LiTFSA concentration than the conventional electrolytic solution, and the number of acetonitrile molecules solvated with LiTFSA (forming clusters) in the electrolytic solution is different from that of LiTFSA. More than the number of unsolvated acetonitrile molecules. Then, the relation between the intensity Io of the original peak of the acetonitrile and the intensity Is of the peak obtained by shifting the original peak of acetonitrile in the vibrational spectrum of the electrolytic solution of the present invention is Is> Io.

Table 3 exemplifies the wave numbers of organic solvents that are considered useful for the calculation of Io and Is and their attribution in the vibrational spectrum of the electrolytic solution of the present invention. It should be added that the wave number of the observed peak may be different from the following wave numbers depending on the measurement apparatus, measurement environment, and measurement conditions of the vibrational spectrum.

公知 Known data on the wave number of organic solvents and their attribution may be used as a reference. As references, the Spectroscopical Society of Japan Measurement Series 17, Raman Spectroscopy, Hiroo Higuchi, Atsuko Hirakawa, Academic Publishing Center, pages 231 to 249 are listed. In addition, the calculation using a computer can also predict the wave number of an organic solvent that is considered useful for the calculation of Io and Is and the wave number shift when the organic solvent and the metal salt are coordinated. For example, Gaussian 09 (registered trademark, Gaussian) may be used, and the density functional may be calculated as B3LYP and the basis function as 6-311G ++ (d, p). A person skilled in the art can calculate the Io and Is by selecting the peak of the organic solvent with reference to the description in Table 3, known data, and the calculation result in the computer.

The density d (g / cm ³ ) in the electrolytic solution of the present invention means a density at 20 ° C. The density d (g / cm ³ ) is preferably d ≧ 1.2 or d ≦ 2.2, more preferably in the range of 1.2 ≦ d ≦ 2.2, and 1.24 ≦ d ≦ 2.0. Is more preferable, the range of 1.26 ≦ d ≦ 1.8 is more preferable, and the range of 1.27 ≦ d ≦ 1.6 is particularly preferable.

In the electrolytic solution of the present invention, d / c is 0.15 ≦ d / c ≦ 0.71, preferably 0.15 ≦ d / c ≦ 0.56, and 0.25 ≦ d / c ≦ 0. Within the range of .56, more preferably within the range of 0.26 ≦ d / c ≦ 0.50, and particularly preferably within the range of 0.27 ≦ d / c ≦ 0.47.

D / c in the electrolytic solution of the present invention can be defined even when a metal salt and an organic solvent are specified. For example, when LiTFSA is selected as the metal salt and DME is selected as the organic solvent, d / c is preferably within the range of 0.42 ≦ d / c ≦ 0.56, and 0.44 ≦ d / c ≦ 0.52 The range of is more preferable. When LiTFSA is selected as the metal salt and AN is selected as the organic solvent, d / c is preferably in the range of 0.35 ≦ d / c ≦ 0.41, and 0.36 ≦ d / c ≦ 0.39. The inside is more preferable. When LiFSA is selected as the metal salt and DME is selected as the organic solvent, d / c is preferably in the range of 0.32 ≦ d / c ≦ 0.46, and in the range of 0.34 ≦ d / c ≦ 0.42. The inside is more preferable. When LiFSA is selected as the metal salt and AN is selected as the organic solvent, d / c is preferably in the range of 0.25 ≦ d / c ≦ 0.31, and in the range of 0.26 ≦ d / c ≦ 0.29. The inside is more preferable. When LiFSA is selected as the metal salt and DMC is selected as the organic solvent, d / c is preferably in the range of 0.32 ≦ d / c ≦ 0.48, and in the range of 0.32 ≦ d / c ≦ 0.46. The inside is more preferable, and the inside of the range of 0.34 ≦ d / c ≦ 0.42 is further preferable. When LiFSA is selected as the metal salt and EMC is selected as the organic solvent, d / c is preferably in the range of 0.34 ≦ d / c ≦ 0.50, and in the range of 0.37 ≦ d / c ≦ 0.45. The inside is more preferable. When LiFSA is selected as the metal salt and DEC is selected as the organic solvent, d / c is preferably in the range of 0.36 ≦ d / c ≦ 0.54, and in the range of 0.39 ≦ d / c ≦ 0.48. The inside is more preferable.

The electrolytic solution of the present invention is different from the conventional electrolytic solution in that the presence environment of the metal salt and the organic solvent is different and the concentration or density of the metal salt is high. When the metal is lithium, the lithium transport number is improved), the reaction rate between the electrode and the electrolyte is improved, the uneven distribution of the salt concentration of the electrolyte that occurs during high-rate charge / discharge of the battery, and the electric double layer capacity is increased. I can expect. Furthermore, in the electrolytic solution of the present invention, most of the organic solvent having a hetero element forms a cluster with a metal salt or has a high density, so the vapor pressure of the organic solvent contained in the electrolytic solution is low. As a result, volatilization of the organic solvent from the electrolytic solution of the present invention can be reduced.

Capacitors have a lower volumetric energy density than batteries. In general, in order to increase the electric capacity of a capacitor, the adsorption site of the capacitor electrode is increased to increase the absolute amount of ions. However, when the adsorption site of the electrode and the electrolytic solution are increased, the volume of the battery increases and the battery itself becomes large.

As described above, the electrolytic solution of the present invention has a higher metal salt concentration than the conventional electrolytic solution. Therefore, the capacitor of the present invention including the electrolytic solution of the present invention has a larger absolute amount of ions that can be aligned at the interface between the electrode and the electrolytic solution than the capacitor including the conventional electrolytic solution. Then, the electric capacity of the capacitor of the present invention is improved as compared with the electric capacity of the capacitor including the conventional electrolyte.

In the electrolytic solution of the present invention, a cluster in which the presence environment of the metal salt and the organic solvent is unique is formed. Here, it is estimated that the radius of the cluster of the electrolyte solution of the present invention is smaller than that of a cation and anion having a large ionic radius constituting a general ionic liquid. Then, since the absolute amount of ions that can be aligned at the interface between the electrode and the electrolyte increases, the capacitance of the capacitor of the present invention is the capacitance of the conventional electrolyte or a capacitor equipped with an electrolyte made of an ionic liquid. Compared with.

Further, since the electrolyte of the present invention is a metal ion, the negative electrode of the capacitor of the present invention can be obtained by using a material such as carbon that can perform an oxidation-reduction reaction by inserting and desorbing metal ions into the negative electrode of the capacitor. Can be a potential in a state where ions are inserted, so that the voltage of the capacitor can be improved. For example, when an electrolytic solution made of a salt using lithium as a cation is used, it becomes an electric double layer capacitor or a lithium ion capacitor by changing the electrode configuration. In particular, a lithium ion capacitor has a merit in terms of voltage, and is one direction responsible for higher energy of the capacitor. Generally, it is necessary for a lithium ion capacitor to include an electrolytic solution containing lithium, but an electrolytic solution used for a normal electric double layer capacitor cannot be used because it does not contain lithium. Therefore, an electrolytic solution for a lithium ion secondary battery is used as the electrolytic solution for the lithium ion capacitor. However, since the electrolytic solution of the present invention in which the cation is lithium contains lithium, it can be applied not only to an electric double layer capacitor but also to a lithium ion capacitor. In the case of using a lithium ion capacitor, a process of doping lithium ions into the electrode in advance is required in order to exhibit more performance. As the doping step, metal lithium may be attached to the electrode, and metal lithium may be doped by immersing and dissolving in an electrolytic solution, or an open collector may be used as disclosed in Japanese Patent No. 4732072. Doping may be performed by placing metallic lithium on the outer peripheral portion and the central portion of the wound type lithium ion capacitor and performing a charging operation. Also, as disclosed in J. Electrochem. Soc. 2012, Volume 159, Issue 8, and Pages A1329-A1334, a transition metal oxide containing excess lithium is added to the positive electrode in advance, and charging is performed. Doping may be performed. Since the transition metal oxide containing excess lithium has a large proportion of lithium in the structure, when the transition metal oxide finishes almost releasing lithium, the particle shape of the transition metal oxide is pulverized. The pulverized particle-shaped transition metal oxide exhibits a lithium adsorption capacity although it has a lower lithium adsorption amount than activated carbon. Therefore, by conducting a conductive treatment on the transition metal oxide containing excess lithium added to the positive electrode of the lithium ion capacitor, the transition metal oxide after lithium release can be used as the adsorption site of the positive electrode. Lithium-excess transition metal oxide has a smaller surface area than carbon used for a general electrode, but has a high density, and therefore may have an advantage in volume energy.

Moreover, the viscosity of the electrolytic solution of the present invention is higher than the viscosity of the conventional electrolytic solution. For this reason, if it is a battery or a capacitor using the electrolyte solution of this invention, even if a battery or a capacitor is damaged, electrolyte solution leakage will be suppressed. Moreover, the capacity | capacitance reduction of the lithium ion secondary battery using the conventional electrolyte solution was remarkable at the time of a high-speed charging / discharging cycle. One reason for this is that due to the uneven Li concentration generated in the electrolyte when rapidly charging and discharging, the electrolyte cannot supply a sufficient amount of Li to the reaction interface with the electrode. The uneven distribution of Li concentration in the electrolytic solution can be considered. However, the metal concentration of the electrolytic solution of the present invention is higher than that of the conventional electrolytic solution. For example, the preferable Li concentration of the electrolytic solution of the present invention is about 2 to 5 times the Li concentration of a general electrolytic solution. Thus, in the electrolytic solution of the present invention containing Li at a high concentration, it is considered that the uneven distribution of Li is reduced, and as a result, the capacity reduction during the high-speed charge / discharge cycle is suppressed. Furthermore, it is thought that the reason for the suppression of the capacity decrease is that the uneven distribution of Li concentration in the electrolytic solution could be suppressed due to the physical properties of the electrolytic solution of the present invention such as high viscosity, high ionic conduction, and high cation transport. In addition, since the electrolytic solution of the present invention has a high viscosity, the liquid retaining property of the electrolytic solution at the electrode interface is improved, and the state where the electrolytic solution is insufficient at the electrode interface (so-called liquid withdrawn state) can be suppressed. This is considered to be one of the reasons that the capacity decrease during the charge / discharge cycle is suppressed.

Regarding the viscosity η (mPa · s) of the electrolytic solution of the present invention, a range of 10 <η <500 is preferable, a range of 12 <η <400 is more preferable, a range of 15 <η <300 is further preferable, and 18 A range of <η <150 is particularly preferable, and a range of 20 <η <140 is most preferable.

Also, the higher the ion conductivity σ (mS / cm) of the electrolytic solution, the easier the ions move in the electrolytic solution. For this reason, such an electrolyte can be an excellent battery electrolyte. The ion conductivity σ (mS / cm) of the electrolytic solution of the present invention is preferably 1 ≦ σ. Regarding the ionic conductivity σ (mS / cm) of the electrolytic solution of the present invention, when a suitable range including the upper limit is shown, a range of 2 <σ <200 is preferable, and a range of 3 <σ <100 is more preferable. The range of 4 <σ <50 is more preferable, and the range of 5 <σ <35 is particularly preferable.

Further, the electrolytic solution of the present invention exhibits a suitable cation transport number (when the metal of the electrolytic solution of the present invention is lithium, the lithium transport number). When showing a preferable cation transport number, 0.4 or more is preferable and 0.45 or more is more preferable.

Incidentally, the electrolytic solution of the present invention contains a metal salt cation in a high concentration. For this reason, in the electrolytic solution of the present invention, the distance between adjacent cations is extremely short. When a cation such as lithium ion moves between the positive electrode and the negative electrode during charge / discharge of the secondary battery, the cation closest to the destination electrode is first supplied to the electrode. And the other cation adjacent to the said cation moves to the place with the said supplied cation. In other words, in the electrolytic solution of the present invention, it is expected that a domino-like phenomenon occurs in which adjacent cations change one by one toward the electrode to be supplied one by one. For this reason, the movement distance of the cation at the time of charging / discharging is short, and it is thought that the movement speed | rate of a cation is high by that much. And it originates in this and it is thought that the reaction rate of the secondary battery which has the electrolyte solution of this invention is high.

The method for producing the electrolytic solution of the present invention will be described. Since the electrolytic solution of the present invention has a higher metal salt content or higher density value than the conventional electrolytic solution, aggregates are obtained by the production method of adding an organic solvent to a solid (powder) metal salt. Therefore, it is difficult to produce a solution electrolyte. Therefore, in the manufacturing method of the electrolyte solution of this invention, it is preferable to manufacture, adding a metal salt gradually with respect to an organic solvent, and maintaining the solution state of electrolyte solution.

Depending on the type of metal salt and organic solvent, the electrolytic solution of the present invention includes a liquid in which the metal salt is dissolved in the organic solvent beyond the conventionally considered saturation solubility. Such a method for producing an electrolytic solution of the present invention includes a first dissolution step of preparing a first electrolytic solution by mixing an organic solvent having a hetero element and a metal salt, dissolving the metal salt, stirring and / or Alternatively, under heating conditions, the metal salt is added to the first electrolyte solution, the metal salt is dissolved to prepare a second electrolyte solution in a supersaturated state, and stirring and / or heating conditions, A third dissolving step of adding the metal salt to the second electrolytic solution, dissolving the metal salt, and preparing a third electrolytic solution;

Here, the “supersaturated state” means a state in which metal salt crystals are precipitated from the electrolyte when the stirring and / or heating conditions are canceled or when crystal nucleation energy such as vibration is applied. Means. The second electrolytic solution is “supersaturated”, and the first electrolytic solution and the third electrolytic solution are not “supersaturated”.

In other words, the above-described method for producing the electrolytic solution of the present invention is a thermodynamically stable liquid state, and passes through the first electrolytic solution containing the conventional metal salt concentration, and then the thermodynamically unstable liquid state. The second electrolytic solution passes through the two electrolytic solutions and becomes a thermodynamically stable new electrolytic third solution, that is, the electrolytic solution of the present invention.

Since the stable third electrolyte solution in a liquid state maintains a liquid state under normal conditions, the third electrolyte solution is composed of, for example, two molecules of an organic solvent for one lithium salt molecule, and a strong distribution between these molecules. It is presumed that the cluster stabilized by the coordinate bond inhibits the crystallization of the lithium salt.

The first dissolution step is a step of preparing a first electrolytic solution by mixing an organic solvent having a hetero atom and a metal salt to dissolve the metal salt.

The first dissolution step is preferably performed under stirring and / or heating conditions. By performing the first dissolution step with a stirrer with a stirrer such as a mixer, the stirring condition may be achieved, or the first dissolution step may be performed using a stirrer and a device (stirrer) that operates the stirrer. Thus, the stirring condition may be used. What is necessary is just to set suitably about stirring speed. About heating conditions, it is preferable to control suitably with thermostats, such as a water bath or an oil bath. Since heat of dissolution is generated when the metal salt is dissolved, it is preferable to strictly control the temperature condition so that the solution temperature does not reach the decomposition temperature of the metal salt when using a heat unstable metal salt. Moreover, the organic solvent cooled beforehand may be used and a 1st melt | dissolution process may be performed on cooling conditions. In order to mix the organic solvent having a hetero atom and the metal salt, the metal salt may be added to the organic solvent having a hetero atom, or the organic solvent having a hetero atom may be added to the metal salt. Considering the generation of heat of dissolution of the metal salt, when using a thermally unstable metal salt, a method of gradually adding the metal salt to the organic solvent having a hetero atom is preferable.

The first dissolution step and the second dissolution step may be performed continuously, or the first electrolytic solution obtained in the first dissolution step is temporarily stored (standing), and after a certain time has passed, You may implement a melt | dissolution process.

The second dissolution step is a step of preparing a supersaturated second electrolyte solution by adding a metal salt to the first electrolyte solution under stirring and / or heating conditions to dissolve the metal salt.

It is essential to perform the second dissolution step under stirring and / or warming conditions in order to prepare a thermodynamically unstable supersaturated second electrolyte solution. By performing the second dissolution step with a stirrer with a stirrer such as a mixer, the stirring condition may be achieved, or the second dissolution step is performed using a stirrer and a device (stirrer) that operates the stirrer. Thus, the stirring condition may be used. About heating conditions, it is preferable to control suitably with thermostats, such as a water bath or an oil bath. Of course, it is particularly preferable to perform the second dissolution step using an apparatus or system having both a stirring function and a heating function. In addition, the warming said by the manufacturing method of the electrolyte solution of this invention points out warming a target object to the temperature more than normal temperature (25 degreeC). The heating temperature is more preferably 30 ° C. or higher, and further preferably 35 ° C. or higher. Further, the heating temperature is preferably lower than the boiling point of the organic solvent.

In the second dissolution step, if the added metal salt is not sufficiently dissolved, increase the stirring speed and / or further heating. Moreover, when the added metal salt is not sufficiently dissolved, a small amount of an organic solvent having a hetero atom may be added to the electrolytic solution in the second dissolution step to promote dissolution of the metal salt. Furthermore, the second dissolving step may be performed under pressure.

Since the crystal of the metal salt is deposited once the second electrolyte obtained in the second dissolution step is allowed to stand, the second dissolution step and the third dissolution step are preferably carried out continuously.

The third dissolution step is a step of preparing a third electrolyte solution by adding a metal salt to the second electrolyte solution under stirring and / or heating conditions to dissolve the metal salt. In the third dissolution step, it is necessary to add a metal salt to the supersaturated second electrolytic solution and dissolve it. Therefore, it is essential to perform the stirring and / or heating conditions as in the second dissolution step. Specific stirring and / or heating conditions are the same as those in the second dissolution step. Similar to the second dissolution step, if the added metal salt does not dissolve sufficiently, an increase in stirring speed and / or further heating is performed. In addition, when the added metal salt is not sufficiently dissolved, a small amount of an organic solvent having a hetero atom may be added to the electrolytic solution to promote dissolution of the metal salt. Furthermore, the third dissolving step may be performed under pressure.

If the molar ratio of the organic solvent and the metal salt added through the first dissolution step, the second dissolution step, and the third dissolution step is about 2: 1, the third electrolytic solution (the electrolytic solution of the present invention) can be manufactured. finish. When the value of d / c of the electrolytic solution in the third dissolution step falls within a desired range, the production of the third electrolytic solution (the electrolytic solution of the present invention) may be terminated. Even when the stirring and / or heating conditions are canceled, the metal salt crystals are not precipitated from the electrolytic solution of the present invention. In view of these circumstances, the electrolytic solution of the present invention is composed of, for example, two molecules of an organic solvent for one molecule of a lithium salt, and is presumed to form a cluster stabilized by a strong coordinate bond between these molecules. Is done.

In producing the electrolytic solution of the present invention, depending on the types of metal salt and organic solvent, the first to third dissolving steps can be performed even if the supersaturated state is not passed at the treatment temperature in each dissolving step. The electrolytic solution of the present invention can be appropriately produced using the specific dissolution means described in 1.

Here, when vibration spectroscopy measurement such as IR measurement or Raman measurement is performed on the first electrolyte solution in the first dissolution step, the original organic solvent derived from the organic solvent contained in the first electrolyte solution is obtained in the vibration spectrum. Both peaks and shift peaks are observed. In the vibrational spectrum of the first electrolyte solution, the original peak intensity of the organic solvent is larger than the shift peak intensity.

As the process proceeds from the first dissolution step to the third dissolution step, the relationship between the original peak intensity of the organic solvent and the shift peak intensity changes. In the vibrational spectrum of the third electrolyte, the shift peak intensity is changed. Becomes larger than the original peak intensity of the organic solvent.

Using this phenomenon, the method for producing an electrolytic solution of the present invention preferably includes a vibrational spectroscopic measurement step of performing vibrational spectroscopic measurement of the electrolytic solution being manufactured. By including a vibrational spectroscopic measurement step in the method for producing an electrolytic solution of the present invention, the degree of coordination (ratio) between the metal salt and the organic solvent in the electrolytic solution or the relationship between Is and Io can be confirmed during the production. In addition, it can be determined whether or not the electrolytic solution in the middle of production has reached the electrolytic solution of one embodiment of the present invention, and when the electrolytic solution in the middle of production has not reached the electrolytic solution of one embodiment of the present invention It is possible to grasp how much metal salt is added to the electrolyte solution of one embodiment of the present invention. As a specific vibration spectroscopic measurement step, for example, a method of sampling a part of each electrolytic solution in the middle of production and using it for vibration spectroscopic measurement, or a method of performing spectroscopic spectroscopic measurement of each electrolytic solution in situ (situ) But it ’s okay. As a method for in-vitro vibrational spectroscopic measurement of an electrolytic solution, a method of introducing an electrolytic solution in the middle of production into a transparent flow cell and performing vibrational spectroscopic measurement, or a method of performing Raman measurement from outside the container using a transparent production vessel Can be mentioned. The vibrational spectroscopic measurement is preferably performed under conditions that can reduce or ignore the influence of moisture in the atmosphere. For example, IR measurement may be performed under low humidity or no humidity conditions such as a dry room or a glove box, or Raman measurement may be performed with the electrolyte solution in a sealed container.

In addition, in the method for producing an electrolytic solution of the present invention, it is preferable to have a density concentration measuring step for measuring values of density and concentration of the electrolytic solution being produced. As a specific measurement process, for example, a method of sampling a part of each electrolytic solution in the middle of production and using it for density and concentration measurement may be used, or the density and concentration of each electrolytic solution may be measured in situ. The method is fine.

Similarly to the above-described vibrational spectroscopic measurement process, the density and concentration of the electrolytic solution can be confirmed during the production by including the density concentration measuring step in the method for producing the electrolytic solution of the present invention. It is possible to determine whether or not the amount of the metal salt has reached the amount of the metal salt in the case where the electrolytic solution in the middle of the production does not reach the amount of the electrolytic solution of the present invention. If it adds, it can be grasped | ascertained whether it reaches the electrolyte solution of 1 aspect of this invention.

Moreover, in the method for producing an electrolytic solution of the present invention, it is preferable to have a viscosity measuring step for measuring the viscosity of the electrolytic solution during production. As a specific viscosity measuring step, for example, a method of sampling a part of each electrolytic solution in the middle of production and using it for viscosity measurement may be used, or each electrolytic solution may be combined in situ by combining an electrolytic solution manufacturing apparatus and a viscosity measuring apparatus. Alternatively, the viscosity may be measured on the spot. By including a viscosity measurement step in the method for producing an electrolytic solution of the present invention, the viscosity in the electrolytic solution can be confirmed during the production, so whether or not the electrolytic solution in the middle of production has reached the electrolytic solution of one embodiment of the present invention. In addition, when the amount of the metal salt is added when the electrolyte in the middle of manufacture does not reach the electrolyte of one embodiment of the present invention, the electrolyte of one embodiment of the present invention is reached. Can be grasped.

Furthermore, in the method for producing an electrolytic solution of the present invention, it is preferable to have an ionic conductivity measurement step for measuring the ionic conductivity of the electrolytic solution during production. As a specific ion conductivity measurement step, for example, a method of sampling a part of each electrolytic solution in the middle of production and using it for ion conductivity measurement may be used, or a combination of an electrolytic solution manufacturing apparatus and an ion conductivity measuring apparatus may be used. A method of measuring the ionic conductivity of each electrolytic solution in situ may be used. By including the ionic conductivity measurement step in the method for producing an electrolytic solution of the present invention, the ionic conductivity in the electrolytic solution can be confirmed during the production, so that the electrolytic solution in the middle of the production has reached the electrolytic solution of one embodiment of the present invention. It is possible to determine whether or not the amount of metal salt added in the case where the electrolyte in the middle of production does not reach the electrolyte of one embodiment of the present invention. It is possible to grasp whether the electrolyte solution is reached.

In the electrolyte solution of the present invention, in addition to the organic solvent having a hetero element, the solvent has a low polarity (low dielectric constant) or a low donor number and does not exhibit a special interaction with a metal salt, that is, the present invention. A solvent that does not affect the formation and maintenance of the clusters in the electrolyte can be added. By adding such a solvent to the electrolytic solution of the present invention, an effect of lowering the viscosity of the electrolytic solution can be expected while maintaining the formation of the cluster of the electrolytic solution of the present invention. In addition, including this case, when the d / c of the finally obtained electrolyte solution changes, the electrolyte solution of one embodiment of the present invention can be positioned as an electrolyte solution in an intermediate manufacturing state.

Specific examples of the solvent that does not exhibit a special interaction with the metal salt include benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, 1-methylnaphthalene, hexane, heptane, and cyclohexane. it can.

In the method for producing an electrolytic solution of the present invention, a step of adding a solvent that does not exhibit a special interaction with the metal salt can be added. This step may be added before or after the first to third dissolution steps, or may be performed during the first to third dissolution steps.

In addition to the organic solvent having a hetero element, a flame retardant solvent can be added to the electrolytic solution of the present invention. By adding a flame retardant solvent to the electrolytic solution of the present invention, the safety of the electrolytic solution of the present invention can be further increased. Examples of the flame retardant solvent include halogen solvents such as carbon tetrachloride, tetrachloroethane, and hydrofluoroether, and phosphoric acid derivatives such as trimethyl phosphate and triethyl phosphate.

In the method for producing an electrolytic solution of the present invention, a step of adding the flame retardant solvent can be added. This step may be added before or after the first to third dissolution steps, or may be performed during the first to third dissolution steps.

Furthermore, when the electrolytic solution of the present invention is mixed with a polymer or an inorganic filler to form a mixture, the mixture contains the electrolytic solution and becomes a pseudo solid electrolyte. By using the pseudo solid electrolyte as the battery electrolyte, leakage of the electrolyte in the battery or capacitor can be suppressed.

As the polymer, a polymer used for a battery such as a lithium ion secondary battery or a general chemically crosslinked polymer can be employed. In particular, a polymer that can absorb an electrolyte such as polyvinylidene fluoride and polyhexafluoropropylene and gel can be used, and a polymer such as polyethylene oxide in which an ion conductive group is introduced.

Specific polymers include polymethyl acrylate, polymethyl methacrylate, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyethylene glycol dimethacrylate, polyethylene glycol acrylate, polyglycidol, polytetrafluoroethylene, polyhexafluoropropylene, Polycarboxylic acid such as polysiloxane, polyvinyl acetate, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyitaconic acid, polyfumaric acid, polycrotonic acid, polyangelic acid, carboxymethylcellulose, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene , Polycarbonate, unsaturated polyester copolymerized with maleic anhydride and glycols, Polyethylene oxide derivative having a group, a copolymer of vinylidene fluoride and hexafluoropropylene can be exemplified. Further, as the polymer, a copolymer obtained by copolymerizing two or more monomers constituting the specific polymer may be selected.

Polysaccharides are also suitable as the polymer. Specific examples of the polysaccharide include glycogen, cellulose, chitin, agarose, carrageenan, heparin, hyaluronic acid, pectin, amylopectin, xyloglucan, and amylose. Moreover, you may employ | adopt the material containing these polysaccharides as said polymer, The agar containing polysaccharides, such as agarose, can be illustrated as the said material.

The inorganic filler is preferably an inorganic ceramic such as oxide or nitride.

Inorganic ceramics have hydrophilic and hydrophobic functional groups on the surface. Therefore, when the functional group attracts the electrolytic solution, a conductive path can be formed in the inorganic ceramic. Furthermore, the inorganic ceramics dispersed in the electrolytic solution can form a network between the inorganic ceramics by the functional groups and serve to contain the electrolytic solution. With such a function of the inorganic ceramics, it is possible to more suitably suppress the leakage of the electrolytic solution in the battery. In order to suitably exhibit the above functions of the inorganic ceramics, the inorganic ceramics preferably have a particle shape, and particularly preferably have a particle size of nano level.

Examples of the inorganic ceramics include general alumina, silica, titania, zirconia, and lithium phosphate. Further, the inorganic ceramic itself may be lithium conductive, and specifically, Li ₃ N, LiI, LiI—Li ₃ N—LiOH, LiI—Li ₂ S—P ₂ O ₅ , LiI—Li ₂ S —P ₂ S ₅ , LiI—Li ₂ S—B ₂ S ₃ , Li ₂ O—B ₂ S ₃ , Li ₂ O—V ₂ O ₃ —SiO ₂ , Li ₂ O—B ₂ O ₃ —P ₂ O ₅ , Li ₂ O—B ₂ O ₃ —ZnO, Li ₂ O—Al ₂ O ₃ —TiO ₂ —SiO ₂ —P ₂ O ₅ , LiTi ₂ (PO ₄ ) ₃ , Li—βAl ₂ O ₃ , LiTaO ₃ Can be illustrated.

Glass ceramics may be employed as the inorganic filler. Since glass ceramics can contain an ionic liquid, the same effect can be expected for the electrolytic solution of the present invention. Glass ceramics include a compound represented by xLi ₂ S- (1-x) P ₂ S ₅ , a compound obtained by substituting a part of S of the compound with another element, and a P of the compound. An example in which the part is replaced with germanium can be exemplified.

In the method for producing an electrolytic solution of the present invention, a step of mixing the third electrolytic solution with the polymer and / or the inorganic filler can be added.

Since the electrolytic solution of the present invention described above exhibits excellent ionic conductivity, it is suitably used as an electrolytic solution for power storage devices such as batteries and capacitors. The electrolytic solution of the present invention is particularly preferably used as an electrolytic solution for a secondary battery, and particularly preferably used as an electrolytic solution for a lithium ion secondary battery. Moreover, it is preferable that the electrolyte solution of this invention is used as an electrolyte solution of an electric double layer capacitor or a lithium ion capacitor.

Hereinafter, a lithium ion secondary battery using the electrolytic solution of the present invention will be described.

The lithium ion secondary battery of the present invention employs a negative electrode having a negative electrode active material capable of occluding and releasing lithium ions, a positive electrode having a positive electrode active material capable of occluding and releasing lithium ions, and a lithium salt as a metal salt. The electrolytic solution of the present invention is provided.

As the negative electrode active material, a material capable of inserting and extracting lithium ions can be used. Accordingly, there is no particular limitation as long as it is a simple substance, alloy, or compound that can occlude and release lithium ions. For example, as a negative electrode active material, Li, group 14 elements such as carbon, silicon, germanium and tin, group 13 elements such as aluminum and indium, group 12 elements such as zinc and cadmium, group 15 elements such as antimony and bismuth, magnesium , Alkaline earth metals such as calcium, and group 11 elements such as silver and gold may be employed alone. When silicon or the like is used for the negative electrode active material, a silicon atom reacts with a plurality of lithiums, so that it becomes a high-capacity active material. However, there is a problem that volume expansion and contraction due to insertion and extraction of lithium becomes significant. In order to reduce the fear, it is also preferable to employ an alloy or compound in which another element such as a transition metal is combined with a simple substance such as silicon as the negative electrode active material. Specific examples of the alloy or compound include tin-based materials such as Ag—Sn alloy, Cu—Sn alloy and Co—Sn alloy, carbon-based materials such as various graphites, SiO _x (disproportionated into silicon simple substance and silicon dioxide). Examples thereof include silicon-based materials such as 0.3 ≦ x ≦ 1.6), silicon alone, or composites obtained by combining silicon-based materials and carbon-based materials. Further, as the negative electrode active material, oxides such as Nb ₂ O ₅ , TiO ₂ , Li ₄ Ti ₅ O ₁₂ , WO ₂ , MoO ₂ , Fe ₂ O ₃ , or Li _3-x M _x N (M = A nitride represented by (Co, Ni, Cu) may be employed. One or more of these materials can be used as the negative electrode active material.

The negative electrode has a current collector and a negative electrode active material layer bound to the surface of the current collector.

A current collector refers to a chemically inert electronic high conductor that keeps a current flowing through an electrode during discharge or charging of a lithium ion secondary battery. As the current collector, at least one selected from silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and stainless steel, etc. Metal materials can be exemplified. The current collector may be covered with a known protective layer. What collected the surface of the electrical power collector by the well-known method may be used as an electrical power collector.

The current collector can take the form of a foil, a sheet, a film, a linear shape, a rod shape, a mesh, or the like. Therefore, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector. When the current collector is in the form of foil, sheet or film, the thickness is preferably in the range of 1 μm to 100 μm.

The negative electrode active material layer contains a negative electrode active material and, if necessary, a binder and / or a conductive aid.

The binder plays a role of connecting the active material and the conductive auxiliary agent to the surface of the current collector.

Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, and alkoxysilyl group-containing resins. be able to.

Also, a polymer having a hydrophilic group may be employed as the binder. Examples of the hydrophilic group of the polymer having a hydrophilic group include a phosphate group such as a carboxyl group, a sulfo group, a silanol group, an amino group, a hydroxyl group, and a phosphate group. Among them, a polymer containing a carboxyl group in the molecule such as polyacrylic acid (PAA), carboxymethyl cellulose (CMC) and polymethacrylic acid, or a polymer containing a sulfo group such as poly (p-styrenesulfonic acid) is preferable.

Polymers containing a large amount of carboxyl groups and / or sulfo groups, such as polyacrylic acid or a copolymer of acrylic acid and vinyl sulfonic acid, are water-soluble. Therefore, the polymer having a hydrophilic group is preferably a water-soluble polymer, and a polymer containing a plurality of carboxyl groups and / or sulfo groups in one molecule is preferable.

The polymer containing a carboxyl group in the molecule can be produced by, for example, a method of polymerizing an acid monomer or adding a carboxyl group to the polymer. Acid monomers include acrylic acid, methacrylic acid, vinyl benzoic acid, crotonic acid, pentenoic acid, angelic acid, tiglic acid, etc., acid monomers having one carboxyl group in the molecule, itaconic acid, mesaconic acid, citraconic acid, fumaric acid Examples include maleic acid, 2-pentenedioic acid, methylene succinic acid, allyl malonic acid, isopropylidene succinic acid, 2,4-hexadiene diacid, acetylenedicarboxylic acid, and other acid monomers having two or more carboxyl groups in the molecule. Is done. A copolymer obtained by polymerizing two or more kinds of monomers selected from these may be used.

For example, a polymer composed of a copolymer of acrylic acid and itaconic acid as described in JP-A-2013-065493, and containing an acid anhydride group formed by condensation of carboxyl groups in the molecule It is also preferable to use as a binder. The structure derived from a highly acidic monomer having two or more carboxyl groups in one molecule is considered to facilitate trapping of lithium ions and the like before the electrolytic solution decomposition reaction occurs during charging. Furthermore, the acidity is not excessively increased because there are more carboxyl groups and the acidity is higher than polyacrylic acid and polymethacrylic acid, and a predetermined amount of the carboxyl groups are changed to acid anhydride groups. Therefore, a secondary battery having a negative electrode formed using this binder has improved initial efficiency and improved input / output characteristics.

The blending ratio of the binder in the negative electrode active material layer is preferably a negative electrode active material: binder = 1: 0.005 to 1: 0.3 in mass ratio. This is because when the amount of the binder is too small, the moldability of the electrode is lowered, and when the amount of the binder is too large, the energy density of the electrode is lowered.

Conductive aid is added to increase the conductivity of the electrode. Therefore, the conductive auxiliary agent may be added arbitrarily when the electrode conductivity is insufficient, and may not be added when the electrode conductivity is sufficiently excellent. The conductive auxiliary agent may be any chemically inert electronic high conductor, such as carbon black, graphite, acetylene black, ketjen black (registered trademark), or vapor grown carbon fiber (Vapor Grown Carbon). Fiber: VGCF) and various metal particles are exemplified. These conductive assistants can be added to the active material layer alone or in combination of two or more. The blending ratio of the conductive assistant in the negative electrode active material layer is preferably negative electrode active material: conductive assistant = 1: 0.01 to 1: 0.5 in terms of mass ratio. This is because if the amount of the conductive aid is too small, an efficient conductive path cannot be formed, and if the amount of the conductive aid is too large, the formability of the negative electrode active material layer is deteriorated and the energy density of the electrode is lowered.

The positive electrode used for the lithium ion secondary battery has a positive electrode active material capable of inserting and extracting lithium ions. The positive electrode has a current collector and a positive electrode active material layer bound to the surface of the current collector. The positive electrode active material layer includes a positive electrode active material and, if necessary, a binder and / or a conductive aid. The positive electrode current collector is not particularly limited as long as it is a metal that can withstand a voltage suitable for the active material to be used. For example, silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin , Indium, titanium, ruthenium, tantalum, chromium, molybdenum, and metal materials such as stainless steel.

When the potential of the positive electrode is 4 V or higher with respect to lithium, it is preferable to use aluminum as the current collector.

Specifically, the positive electrode current collector is preferably made of aluminum or an aluminum alloy. Here, aluminum refers to pure aluminum, and aluminum having a purity of 99.0% or more is referred to as pure aluminum. An alloy obtained by adding various elements to pure aluminum is referred to as an aluminum alloy. Examples of the aluminum alloy include Al—Cu, Al—Mn, Al—Fe, Al—Si, Al—Mg, AL—Mg—Si, and Al—Zn—Mg.

Specific examples of aluminum or aluminum alloy include, for example, A1000 series alloys (pure aluminum series) such as JIS A1085 and A1N30, A3000 series alloys (Al-Mn series) such as JIS A3003 and A3004, JIS A8079, A8021, etc. A8000-based alloy (Al-Fe-based).

The current collector may be covered with a known protective layer. What collected the surface of the electrical power collector by the well-known method may be used as an electrical power collector.

The binder for the positive electrode and the conductive additive are the same as those described for the negative electrode.

As the positive electrode active material, the layered compound Li _a Ni _b Co _c Mn _d _De O _f (0.2 ≦ a ≦ 1.2, b + c + d + e = 1, 0 ≦ e <1, D is Li, Fe, Cr, At least one element selected from Cu, Zn, Ca, Mg, S, Si, Na, K, Al, Zr, Ti, P, Ga, Ge, V, Mo, Nb, W, La, 1.7 ≦ f ≦ 2.1) and Li ₂ MnO ₃ . Further, as a positive electrode active material, a solid solution composed of a spinel such as LiMn ₂ O ₄ and a mixture of a spinel and a layered compound, LiMPO ₄ , LiMVO ₄ or Li ₂ MSiO ₄ (wherein M is Co, Ni, Mn, And a polyanionic compound represented by (selected from at least one of Fe). Furthermore, as the positive electrode active material, tavorite compound (the M a transition metal) LiMPO ₄ F, such as LiFePO ₄ F represented by, Limbo ₃ such LiFeBO ₃ (M is a transition metal) include borate-based compound represented by be able to. Any metal oxide used as the positive electrode active material may have the above composition formula as a basic composition, and a metal element contained in the basic composition may be substituted with another metal element. Moreover, you may use as a positive electrode active material the thing which does not contain a charge carrier (for example, lithium ion which contributes to charging / discharging). For example, sulfur alone (S), a compound in which sulfur and carbon are compounded, a metal sulfide such as TiS ₂ , an oxide such as V ₂ O ₅ and MnO ₂ , a compound containing polyaniline and anthraquinone, and these aromatics in the chemical structure In addition, conjugated materials such as conjugated diacetate-based organic substances and other known materials can also be used. Further, a compound having a stable radical such as nitroxide, nitronyl nitroxide, galvinoxyl, phenoxyl, etc. may be adopted as the positive electrode active material. When using a positive electrode active material that does not contain a charge carrier such as lithium, it is necessary to add a charge carrier to the positive electrode and / or the negative electrode in advance by a known method. The charge carrier may be added in an ionic state or in a non-ionic state such as a metal. For example, when the charge carrier is lithium, it may be integrated by attaching a lithium foil to the positive electrode and / or the negative electrode.

In order to form an active material layer on the surface of the current collector, a current collecting method such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method can be used. An active material may be applied to the surface of the body. Specifically, an active material layer-forming composition containing an active material and, if necessary, a binder and a conductive aid is prepared, and an appropriate solvent is added to the composition to make a paste, and then the collection is performed. After applying to the surface of the electric body, it is dried. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. In order to increase the electrode density, the dried product may be compressed.

A separator is used for a lithium ion secondary battery as required. The separator separates the positive electrode and the negative electrode and allows lithium ions to pass while preventing a short circuit of current due to contact between the two electrodes. As separators, natural resins such as polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, polyaramid (Aromatic polymer), polyester, polyacrylonitrile, etc., polysaccharides such as cellulose, amylose, fibroin, keratin, lignin, suberin, etc. Examples thereof include porous bodies, nonwoven fabrics, and woven fabrics using one or more electrically insulating materials such as polymers and ceramics. The separator may have a multilayer structure. Since the electrolytic solution of the present invention has a slightly high viscosity and a high polarity, a membrane in which a polar solvent such as water can easily penetrate is preferable. Specifically, a film in which a polar solvent such as water soaks into 90% or more of the existing voids is more preferable.

A separator is sandwiched between the positive electrode and the negative electrode as necessary to form an electrode body. The electrode body may be either a stacked type in which the positive electrode, the separator and the negative electrode are stacked, or a wound type in which the positive electrode, the separator and the negative electrode are sandwiched. After connecting the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal connected to the outside using a current collecting lead or the like, the electrolyte solution of the present invention is added to the electrode body to form lithium ions. A secondary battery may be used. Moreover, the lithium ion secondary battery of this invention should just be charged / discharged in the voltage range suitable for the kind of active material contained in an electrode.

The shape of the lithium ion secondary battery of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate shape can be adopted.

The lithium ion secondary battery of the present invention may be mounted on a vehicle. The vehicle may be a vehicle that uses electric energy from a lithium ion secondary battery for all or a part of its power source, and may be, for example, an electric vehicle or a hybrid vehicle. When a lithium ion secondary battery is mounted on a vehicle, a plurality of lithium ion secondary batteries may be connected in series to form an assembled battery. Examples of devices equipped with lithium ion secondary batteries include various home appliances driven by batteries such as personal computers and portable communication devices, office devices, and industrial devices in addition to vehicles. Furthermore, the lithium ion secondary battery of the present invention includes wind power generation, solar power generation, hydroelectric power generation and other power system power storage devices and power smoothing devices, power supplies for ships and / or auxiliary power supply sources, aircraft, Power supply for spacecraft and / or auxiliary equipment, auxiliary power supply for vehicles that do not use electricity as a power source, power supply for mobile home robots, power supply for system backup, power supply for uninterruptible power supply, You may use for the electrical storage apparatus which stores temporarily the electric power required for charge in the charging station for electric vehicles.

Hereinafter, the electric double layer capacitor and the lithium ion capacitor will be described.

The electric double layer capacitor and the lithium ion capacitor of the present invention include the electrolytic solution of the present invention, a pair of electrodes, and a separator.

The electrode is composed of a current collector and a carbon-containing layer formed on the current collector and containing a carbon material.

A current collector refers to a chemically inert electronic high conductor that keeps current flowing through an electrode during discharge or charging of electricity. The current collector may be any one used for ordinary electric double layer capacitors or lithium ion capacitors. Silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium , At least one selected from ruthenium, tantalum, chromium and molybdenum, and metal materials such as stainless steel. The current collector may be covered with a known protective film.

The carbon-containing layer contains a carbon material and, if necessary, a binder (dispersant) and a conductive aid.
As a carbon material, what is necessary is just to be used for a normal electric double layer capacitor, and activated carbon manufactured from various raw materials can be mentioned. The activated carbon preferably has a large specific surface area. In addition, it is a material used in redox capacitors whose capacity increases due to adsorption / desorption of anions such as conductive polymers such as polyacene and 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO). May be.

However, since the carbon material of the carbon-containing layer of the negative electrode of the lithium ion capacitor needs to be a material that can occlude and release lithium ions, it becomes a graphite-containing material such as natural graphite or artificial graphite.

The binder plays a role of binding the carbon material and the conductive additive to the surface of the current collector.

The binder is not particularly limited as long as it is used for ordinary electric double layer capacitors or lithium ion capacitors, and includes fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, and thermoplastic resins such as polypropylene and polyethylene. Examples thereof include imide resins such as polyimide and polyamideimide, and alkoxysilyl group-containing resins. The blending ratio of the binder in the carbon-containing layer is preferably a mass ratio of carbon material: binder = 1: 0.005 to 1: 0.3.

Conductive aid is added to increase the conductivity of the electrode. Therefore, the conductive auxiliary agent may be added arbitrarily when the electrode conductivity is insufficient, and may not be added when the electrode conductivity is sufficiently excellent. As the conductive auxiliary agent, any material may be used as long as it is used for a normal electric double layer capacitor or a lithium ion capacitor, and carbon black, natural graphite, artificial graphite, acetylene black, ketjen black (registered trademark), which are carbonaceous fine particles, Examples include vapor grown carbon fiber (Vapor Grown Carbon Fiber: VGCF) and various metal particles. These conductive assistants can be added to the carbon-containing layer singly or in combination of two or more. The blending ratio of the conductive assistant in the carbon-containing layer is preferably a mass ratio of carbon material: conductive assistant = 1: 0.01 to 1: 0.5.

Further, the carbon-containing layer of the positive electrode of the lithium ion capacitor may contain lithium oxide, a mixture of lithium oxide and activated carbon, or carbon-coated lithium oxide. Examples of the lithium oxide include Li _a MO ₄ (5 ≦ a ≦ 6, where M is one or more transition metals). Specifically, Li ₅ FeO ₄ , Li ₆ MnO ₄ , A lithium oxide having an inverted fluorite structure such as Li ₆ CoO ₄ can be given. These lithium oxides correspond to the “transition metal oxides containing excess lithium” described above. The transition metal oxide containing excess lithium is preferably uniformly dispersed in the carbon-containing layer of the positive electrode.

In order to form a carbon-containing layer on the surface of the current collector, a current collecting method such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method can be used. A carbon material or the like may be applied to the surface of the body. Specifically, a carbon material and, if necessary, a binder, a conductive additive, a solid solution of lithium oxide and activated carbon, and a composition for forming a carbon-containing layer containing carbon-coated lithium oxide are prepared. An appropriate solvent is added to the product to form a paste, which is applied to the surface of the current collector and then dried. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. As a preferred method for producing a positive electrode having a carbon-containing layer containing a transition metal oxide containing excess lithium, an appropriate solvent is added to a mixture of a carbon material such as activated carbon and a transition metal oxide containing excess lithium. A method of forming a paste and then applying it to the surface of the positive electrode current collector and then drying it can be mentioned.

The separator is for separating a pair of electrodes from each other and preventing a short circuit of current due to contact between both electrodes. The separator may be any material used for ordinary electric double layer capacitors or lithium ion capacitors, and synthetic resins such as polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, polyaramid (Aromatic polyamide), polyester, polyacrylonitrile, and the like. Polysaccharides such as cellulose and amylose, natural polymers such as fibroin, keratin, lignin, and suberin, porous materials using one or more electrical insulating materials such as glass fibers and ceramics, non-woven fabrics, woven fabrics, etc. Can do. The separator may have a multilayer structure. Since the electrolytic solution of the present invention has a slightly high viscosity and a high polarity, a membrane in which a polar solvent such as water can easily penetrate is preferable. Specifically, a film in which a polar solvent such as water soaks into 90% or more of the existing voids is more preferable. The thickness of the separator is preferably 5 to 100 μm, more preferably 10 to 80 μm, and particularly preferably 20 to 60 μm.

The electric double layer capacitor or lithium ion capacitor of the present invention may be manufactured according to a normal method for manufacturing an electric double layer capacitor or lithium ion capacitor. In addition, in order to pre-dope lithium ions into the negative electrode of the lithium ion capacitor of the present invention, metal lithium may be used in the same manner as the pre-doping of a general lithium ion capacitor. Here, if the carbon-containing layer of the positive electrode of the lithium ion capacitor of the present invention contains lithium oxide or carbon-covered lithium oxide, lithium ion pre-doping is performed using these lithium oxides. Can do. And what desorbed lithium ion from lithium oxide or carbon covering lithium oxide can function as an active material of a positive electrode.

The shape of the capacitor of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate shape can be employed.

The capacitor of the present invention may be mounted on a vehicle. The vehicle may be a vehicle that uses electric energy generated by a capacitor for all or a part of its power source. For example, the vehicle may be an electric vehicle or a hybrid vehicle. In addition to the vehicle, the device on which the capacitor is mounted includes various home appliances, office devices, industrial devices, and the like that are driven by a power storage device, such as personal computers and portable communication devices. Furthermore, the capacitor of the present invention is a power generation device for wind power generation, solar power generation, hydroelectric power generation, and other power systems, power smoothing device, power supply for ships and / or auxiliary equipment, aircraft, spacecraft, etc. Power supply source for power and / or auxiliary equipment, auxiliary power source for vehicles not using electricity as a power source, power source for mobile home robots, power source for system backup, power source for uninterruptible power supply, charging for electric vehicles You may use for the electrical storage apparatus which stores temporarily the electric power required for charge in a station.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, this invention is not limited by these Examples. In the following, unless otherwise specified, “part” means part by mass, and “%” means mass%.

Example 1
The electrolytic solution of the present invention was produced as follows.

About 5 mL of 1,2-dimethoxyethane, which is an organic solvent, was placed in a flask equipped with a stir bar and a thermometer. Under stirring conditions, (CF ₃ SO ₂ ) ₂ NLi, which is a lithium salt, was gradually added to 1,2-dimethoxyethane in the flask so as to keep the solution temperature at 40 ° C. or lower and dissolved. When about 13 g of (CF ₃ SO ₂ ) ₂ NLi was added, the dissolution of (CF ₃ SO ₂ ) ₂ NLi temporarily stagnated. Therefore, the flask was put into a thermostat, and the solution temperature in the flask was 50 ° C. (CF ₃ SO ₂ ) ₂ NLi was dissolved. When about 15 g of (CF ₃ SO ₂ ) ₂ NLi was added, the dissolution of (CF ₃ SO ₂ ) ₂ NLi stagnated again, so 1 drop of 1,2-dimethoxyethane was added with a pipette (CF ₃ SO ₂ ) ₂ NLi dissolved. Further, (CF ₃ SO ₂ ) ₂ NLi was gradually added, and the entire amount of predetermined (CF ₃ SO ₂ ) ₂ NLi was added. The resulting electrolyte was transferred to a 20 mL volumetric flask and 1,2-dimethoxyethane was added until the volume was 20 mL. This was used as the electrolytic solution of Example 1 (third electrolytic solution).

The electrolytic solution that exceeds the concentration at the time when the dissolution of (CF ₃ SO ₂ ) ₂ NLi stagnated corresponds to the supersaturated second electrolytic solution.

The obtained electrolytic solution had a volume of 20 mL, and (CF ₃ SO ₂ ) ₂ NLi contained in this electrolytic solution was 18.38 g. The concentration of (CF ₃ SO ₂ ) ₂ NLi in the electrolytic solution of Example 1 was 3.2 mol / L, and the density was 1.39 g / cm ³ . The density was measured at 20 ° C. In the electrolyte solution of Example 1, 1.6 molecules of 1,2-dimethoxyethane are contained per 1 molecule of (CF ₃ SO ₂ ) ₂ NLi.

The above production was carried out in a glove box under an inert gas atmosphere.

(Example 2)
Using 16.08 g of (CF ₃ SO ₂ ) ₂ NLi, the concentration of (CF ₃ SO ₂ ) ₂ NLi was 2.8 mol / L and the density was 1.36 g / cm in the same manner as in Example 1. ³ was produced. In the electrolytic solution of Example 2, 2.1 molecules of 1,2-dimethoxyethane are contained per 1 molecule of (CF ₃ SO ₂ ) ₂ NLi.

Example 3
About 5 mL of acetonitrile, which is an organic solvent, was placed in a flask equipped with a stir bar. Under stirring conditions, (CF ₃ SO ₂ ) ₂ NLi, which is a lithium salt, was gradually added to and dissolved in acetonitrile in the flask. When 24.11 g of (CF ₃ SO ₂ ) ₂ NLi was added in total, the mixture was stirred overnight. The resulting electrolyte was transferred to a 20 mL volumetric flask and acetonitrile was added until the volume was 20 mL. This was used as the electrolytic solution of Example 3. The production was performed in a glove box under an inert gas atmosphere.

The concentration of (CF ₃ SO ₂ ) ₂ NLi in the electrolytic solution of Example 3 was 4.2 mol / L, and the density was 1.52 g / cm ³ . In the electrolyte solution of Example 3, 1.9 molecules of acetonitrile are contained with respect to (CF ₃ SO ₂ ) ₂ NLi1 molecules.

Example 4
Using 19.52 g of (CF ₃ SO ₂ ) ₂ NLi, the electrolytic solution of Example 4 in which the concentration of (CF ₃ SO ₂ ) ₂ NLi is 3.4 mol / L is produced in the same manner as in Example 3. did. In the electrolyte solution of Example 4, 3 molecules of acetonitrile are contained with respect to 1 molecule of (CF ₃ SO ₂ ) ₂ NLi.

(Example 5)
In the same manner as in Example 3, an electrolytic solution of Example 5 in which the concentration of (CF ₃ SO ₂ ) ₂ NLi was 3.0 mol / L and the density was 1.31 g / cm ³ was produced.

(Example 6)
The same procedure as in Example 3 except that sulfolane was used as the organic solvent, the concentration of (CF ₃ SO ₂ ) ₂ NLi was 3.0 mol / L, and the density was 1.57 g / cm ³ The electrolyte solution of Example 6 was produced.

(Example 7)
The concentration of (CF ₃ SO ₂ ) ₂ NLi is 3.2 mol / L and the density is 1.49 g / cm ³ in the same manner as in Example 3 except that dimethyl sulfoxide is used as the organic solvent. The electrolyte solution of Example 7 was manufactured.

(Example 8)
The concentration of (FSO ₂ ) ₂ NLi was 4 in the same manner as in Example 3 except that 14.97 g of (FSO ₂ ) ₂ NLi was used as the lithium salt and 1,2-dimethoxyethane was used as the organic solvent. An electrolytic solution of Example 8 having a density of 0.0 mol / L and a density of 1.33 g / cm ³ was produced. In the electrolytic solution of Example 8, 1.5 molecules of 1,2-dimethoxyethane are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

Example 9
Implementation using 13.47 g of (FSO ₂ ) ₂ NLi in the same manner as in Example 8 with a concentration of (FSO ₂ ) ₂ NLi of 3.6 mol / L and a density of 1.29 g / cm ³ The electrolyte solution of Example 9 was produced. In the electrolyte solution of Example 9, 1.9 molecules of 1,2-dimethoxyethane are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 10)
In the same manner as in Example 8, the electrolyte solution of Example 10 in which the concentration of (FSO ₂ ) ₂ NLi was 2.4 mol / L and the density was 1.18 g / cm ³ was produced.

(Example 11)
The electrolyte solution of Example 11 in which the concentration of (FSO ₂ ) ₂ NLi is 5.4 mol / L in the same manner as in Example 3 except that 20.21 g of (FSO ₂ ) ₂ NLi was used as the lithium salt. Manufactured. In the electrolyte solution of Example 11, ₂ molecules of acetonitrile are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

Example 12
Implementation wherein 18.71 g of (FSO ₂ ) ₂ NLi was used and the concentration of (FSO ₂ ) ₂ NLi was 5.0 mol / L and the density was 1.40 g / cm ³ in the same manner as in Example 11. The electrolyte solution of Example 12 was produced. In the electrolyte solution of Example 12, 2.1 molecules of acetonitrile are contained with respect to (FSO ₂ ) ₂ NLi1 molecule.

(Example 13)
Implementation using 16.83 g of (FSO ₂ ) ₂ NLi in the same manner as in Example 11, with a concentration of (FSO ₂ ) ₂ NLi of 4.5 mol / L and a density of 1.34 g / cm ³ The electrolyte solution of Example 13 was produced. In the electrolyte solution of Example 13, 2.4 molecules of acetonitrile are contained per (FSO ₂ ) ₂ NLi1 molecule.

(Example 14)
Using 15.72 g of (FSO ₂ ) ₂ NLi, an electrolytic solution of Example 14 having a concentration of (FSO ₂ ) ₂ NLi of 4.2 mol / L was produced in the same manner as in Example 11. In the electrolyte solution of Example 14, 3 molecules of acetonitrile are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 15)
About 5 mL of dimethyl carbonate, which is an organic solvent, was placed in a flask equipped with a stir bar. Under stirring conditions, (FSO ₂ ) ₂ NLi, which is a lithium salt, was gradually added to dimethyl carbonate in the flask and dissolved. When (FSO ₂ ) ₂ NLi was added in a total amount of 14.64 g, the mixture was stirred overnight. The resulting electrolyte was transferred to a 20 mL volumetric flask and dimethyl carbonate was added until the volume was 20 mL. This was used as the electrolytic solution of Example 15. The production was performed in a glove box under an inert gas atmosphere.

The concentration of (FSO ₂ ) ₂ NLi in the electrolytic solution of Example 15 was 3.9 mol / L, and the density was 1.44 g / cm ³ . In the electrolyte solution of Example 15, _two molecules of dimethyl carbonate are contained with respect to one molecule of (FSO ₂ ) ₂ NLi.

(Example 16)
Dimethyl carbonate was added to the electrolyte solution of Example 15 for dilution to obtain an electrolyte solution of Example 16 having a (FSO ₂ ) ₂ NLi concentration of 3.4 mol / L. In the electrolyte solution of Example 16, 2.5 molecules of dimethyl carbonate are contained with respect to (FSO ₂ ) ₂ NLi1 molecules.

(Example 17)
Dimethyl carbonate was added to the electrolyte solution of Example 15 for dilution to obtain an electrolyte solution of Example 17 having a (FSO ₂ ) ₂ NLi concentration of 2.9 mol / L. In the electrolyte solution of Example 17, 3 molecules of dimethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi. The density of the electrolytic solution of Example 17 was 1.36 g / cm ³ .

(Example 18)
Dimethyl carbonate was added to the electrolyte solution of Example 15 for dilution to obtain an electrolyte solution of Example 18 having a (FSO ₂ ) ₂ NLi concentration of 2.6 mol / L. In the electrolytic solution of Example 18, 3.5 molecules of dimethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 19)
Dimethyl carbonate was added to the electrolyte solution of Example 15 and diluted to obtain an electrolyte solution of Example 19 having a (FSO ₂ ) ₂ NLi concentration of 2.0 mol / L. In the electrolytic solution of Example 19, 5 molecules of dimethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 20)
About 5 mL of ethyl methyl carbonate, which is an organic solvent, was placed in a flask equipped with a stir bar. Under stirring conditions, (FSO ₂ ) ₂ NLi, which is a lithium salt, was gradually added to and dissolved in ethyl methyl carbonate in the flask. When 12.81 g of (FSO ₂ ) ₂ NLi was added in total, the mixture was stirred overnight. The obtained electrolytic solution was transferred to a 20 mL volumetric flask, and ethyl methyl carbonate was added until the volume became 20 mL. This was used as the electrolytic solution of Example 20. The production was performed in a glove box under an inert gas atmosphere.

The concentration of (FSO ₂ ) ₂ NLi in the electrolytic solution of Example 20 was 3.4 mol / L, and the density was 1.35 g / cm ³ . In the electrolytic solution of Example 20, _two molecules of ethyl methyl carbonate are contained with respect to one molecule of (FSO ₂ ) ₂ NLi.

(Example 21)
The electrolyte solution of Example 20 was diluted by adding ethyl methyl carbonate to obtain the electrolyte solution of Example 21 having a concentration of (FSO ₂ ) ₂ NLi of 2.9 mol / L. In the electrolytic solution of Example 21, 2.5 molecules of ethyl methyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 22)
The electrolyte solution of Example 20 was diluted by adding ethyl methyl carbonate to obtain the electrolyte solution of Example 22 having a (FSO ₂ ) ₂ NLi concentration of 2.2 mol / L. In the electrolyte solution of Example 22, 3.5 molecules of ethyl methyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 23)
About 5 mL of diethyl carbonate, which is an organic solvent, was placed in a flask equipped with a stirring bar. Under stirring conditions, (FSO ₂ ) ₂ NLi, which is a lithium salt, was gradually added to and dissolved in diethyl carbonate in the flask. When 11.37 g of the total amount of (FSO ₂ ) ₂ NLi was added, the mixture was stirred overnight. The resulting electrolyte was transferred to a 20 mL volumetric flask and diethyl carbonate was added until the volume was 20 mL. This was used as the electrolytic solution of Example 23. The production was performed in a glove box under an inert gas atmosphere.

The concentration of (FSO ₂ ) ₂ NLi in the electrolytic solution of Example 23 was 3.0 mol / L, and the density was 1.29 g / cm ³ . In the electrolytic solution of Example 23, _two molecules of diethyl carbonate are contained with respect to one molecule of (FSO ₂ ) ₂ NLi.

(Example 24)
Diethyl carbonate was added to the electrolytic solution of Example 23 for dilution to obtain an electrolytic solution of Example 24 having a (FSO ₂ ) ₂ NLi concentration of 2.6 mol / L. In the electrolytic solution of Example 24, 2.5 molecules of diethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 25)
Diethyl carbonate was added to the electrolyte solution of Example 23 for dilution to obtain an electrolyte solution of Example 25 having a (FSO ₂ ) ₂ NLi concentration of 2.0 mol / L. In the electrolytic solution of Example 25, 3.5 molecules of diethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Example 26)
An electrolytic solution of Example 26 having a LiBF ₄ concentration of 4.9 mol / L was produced in the same manner as in Example 15, except that 9.23 g of LiBF ₄ was used as the lithium salt. In the electrolyte solution of Example 26, two molecules of dimethyl carbonate are contained with respect to one molecule of LiBF ₄ . The density of the electrolyte solution of Example 26 was 1.30 g / cm ³ .

(Example 27)
An electrolytic solution of Example 27 in which the concentration of LiPF ₆ was 4.4 mol / L was produced in the same manner as in Example 15 except that 13.37 g of LiPF ₆ was used as the lithium salt. In the electrolytic solution of Example 27, two molecules of dimethyl carbonate are contained with respect to one molecule of LiPF ₆ . The density of the electrolyte solution of Example 27 was 1.46 g / cm ³ .

(Comparative Example 1)
Using 1,2-dimethoxyethane as the organic solvent, the concentration of (CF ₃ SO ₂ ) ₂ NLi is 1.6 mol / L and the density is 1.18 g / cm ³ in the same manner as in Example 3. The electrolytic solution of Comparative Example 1 was produced.

(Comparative Example 2)
In the same manner as in Comparative Example 1, an electrolytic solution of Comparative Example 2 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 1.2 mol / L and a density of 1.09 g / cm ³ was produced.

(Comparative Example 3)
In the same manner as in Comparative Example 1, an electrolytic solution of Comparative Example 3 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 1.0 mol / L and a density of 1.06 g / cm ³ was produced. In the electrolytic solution of Comparative Example 3, 8.3 molecules of 1,2-dimethoxyethane are contained per 1 molecule of (CF ₃ SO ₂ ) ₂ NLi.

(Comparative Example 4)
In the same manner as in Comparative Example 1, an electrolytic solution of Comparative Example 4 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 0.5 mol / L and a density of 0.96 g / cm ³ was produced.

(Comparative Example 5)
In the same manner as in Comparative Example 1, an electrolytic solution of Comparative Example 5 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 0.2 mol / L and a density of 0.91 g / cm ³ was produced.

(Comparative Example 6)
In the same manner as in Comparative Example 1, an electrolytic solution of Comparative Example 6 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 0.1 mol / L and a density of 0.89 g / cm ³ was produced.

(Comparative Example 7)
In the same manner as in Example 3, an electrolytic solution of Comparative Example 7 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 1.0 mol / L and a density of 0.96 g / cm ³ was produced. In the electrolytic solution of Comparative Example 7, 16 molecules of acetonitrile are contained per 1 molecule of (CF ₃ SO ₂ ) ₂ NLi.

(Comparative Example 8)
In the same manner as in Example 6, an electrolytic solution of Comparative Example 8 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 1.0 mol / L and a density of 1.38 g / cm ³ was produced.

(Comparative Example 9)
In the same manner as in Example 7, an electrolytic solution of Comparative Example 9 having a (CF ₃ SO ₂ ) ₂ NLi concentration of 1.0 mol / L and a density of 1.22 g / cm ³ was produced.

(Comparative Example 10)
In the same manner as in Example 8, an electrolytic solution of Comparative Example 10 in which the concentration of (FSO ₂ ) ₂ NLi was 2.0 mol / L and the density was 1.13 g / cm ³ was produced.

(Comparative Example 11)
In the same manner as in Example 8, an electrolytic solution of Comparative Example 11 having a (FSO ₂ ) ₂ NLi concentration of 1.0 mol / L and a density of 1.01 g / cm ³ was produced. In the electrolyte solution of Comparative Example 11, 8.8 molecules of 1,2-dimethoxyethane are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Comparative Example 12)
In the same manner as in Example 8, an electrolytic solution of Comparative Example 12 having a concentration of (FSO ₂ ) ₂ NLi of 0.5 mol / L and a density of 0.94 g / cm ³ was produced.

(Comparative Example 13)
In the same manner as in Example 8, an electrolytic solution of Comparative Example 13 having a (FSO ₂ ) ₂ NLi concentration of 0.1 mol / L and a density of 0.88 g / cm ³ was produced.

(Comparative Example 14)
In the same manner as in Example 12, an electrolytic solution of Comparative Example 14 having a concentration of (FSO ₂ ) ₂ NLi of 1.0 mol / L and a density of 0.91 g / cm ³ was produced. In the electrolytic solution of Comparative Example 14, 17 molecules of acetonitrile are contained with respect to 1 molecule of (FSO ₂ ) ₂ NLi.

(Comparative Example 15)
Dimethyl carbonate was added to the electrolyte solution of Example 15 for dilution, and the electrolyte solution of Comparative Example 15 having a (FSO ₂ ) ₂ NLi concentration of 1.1 mol / L and a density of 1.16 g / cm ³ was obtained. Manufactured. In the electrolyte solution of Comparative Example 15, 10 molecules of dimethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Comparative Example 16)
The electrolytic solution of Comparative Example 16 was diluted by adding ethyl methyl carbonate to the electrolytic solution of Example 20, and the concentration of (FSO ₂ ) ₂ NLi was 1.1 mol / L and the density was 1.12 g / cm ^3. Manufactured. In the electrolytic solution of Comparative Example 16, 8 molecules of ethyl methyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Comparative Example 17)
The electrolyte solution of Comparative Example 17 was diluted by adding diethyl carbonate to the electrolyte solution of Example 23, and the concentration of (FSO ₂ ) ₂ NLi was 1.1 mol / L and the density was 1.08 g / cm ^3. Manufactured. In the electrolytic solution of Comparative Example 17, 7 molecules of diethyl carbonate are contained per 1 molecule of (FSO ₂ ) ₂ NLi.

(Comparative Example 18)
A mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio 3: 7) (hereinafter sometimes referred to as “EC / DEC”) was used as the organic solvent, and 3.04 g of LiPF ₆ was used as the lithium salt. In the same manner as in Example 3, an electrolytic solution of Comparative Example 18 having a LiPF ₆ concentration of 1.0 mol / L was produced.

Tables 4 and 5 show a list of electrolyte solutions of Examples and Comparative Examples. A blank in the table means uncalculated.

Tables 6 and 7 show a list of density and d / c of the electrolyte solutions of Examples and Comparative Examples. A blank in the table means unmeasured or uncalculated.

(Evaluation Example 1: IR measurement)
Example 3, Example 4, Example 11, Example 13, Example 14, Example 7, Comparative Example 14, Electrolyte of Comparative Example 14, and acetonitrile, (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi The IR measurement was performed under the following conditions. IR spectra in the range of 2100 to 2400 cm −1 are shown in FIGS. 1 to 10, respectively. The horizontal axis in the figure is the wave number (cm ⁻¹ ), and the vertical axis is the absorbance (reflection absorbance).

IR measurement was performed on the electrolytic solutions of Examples 15 to 25 and Comparative Examples 15 to 17, and dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate under the following conditions. IR spectra in the range of 1900 to 1600 cm ⁻¹ are shown in FIGS. 11 to 27, respectively. In addition, FIG. 28 shows an IR spectrum in the range of 1900 to 1600 cm ⁻¹ for (FSO ₂ ) ₂ NLi. The horizontal axis in the figure is the wave number (cm ⁻¹ ), and the vertical axis is the absorbance (reflection absorbance).

Furthermore, IR measurement was performed on the electrolytic solutions of Example 26 and Example 27 under the following conditions. IR spectra in the range of 1900 to 1600 cm ⁻¹ are shown in FIGS. 29 to 30, respectively. The horizontal axis in the figure is the wave number (cm ⁻¹ ), and the vertical axis is the absorbance (reflection absorbance).

IR measurement conditions Device: FT-IR (Bruker Optics)
Measurement conditions: ATR method (using diamond)
Measurement atmosphere: Inert gas atmosphere

In the vicinity of 2250 cm ⁻¹ of the IR spectrum of acetonitrile shown in FIG. 8, a characteristic peak derived from the stretching vibration of the triple bond between C and N of acetonitrile was observed. Note that no special peak was observed in the vicinity of 2250 cm ⁻¹ of the IR spectrum of (CF ₃ SO ₂ ) ₂ NLi shown in FIG. 9 and the IR spectrum of (FSO ₂ ) ₂ NLi shown in FIG.

In the IR spectrum of the electrolyte solution of Example 4 shown in FIG. 1, there is a slight characteristic peak (Io = 0.00699) derived from the stretching vibration of the triple bond between C and N of acetonitrile in the vicinity of 2250 cm ^−1. ) Observed. More IR spectrum of FIG. 1, 2250 cm characteristic peaks peak intensity derived from the stretching vibration of the triple bond between the vicinity of ^-1 acetonitrile near 2280 cm ^-1 shifted to the high frequency side C and N Is = 0 .05828. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 8 × Io.

The IR spectrum of the electrolyte solution of Example 3 shown in FIG. 2, not the peak derived from acetonitrile observed around 2250 cm ^-1, acetonitrile near 2280 cm ^-1 shifted from the vicinity of 2250 cm ^-1 to the high frequency side C And a characteristic peak derived from the stretching vibration of the triple bond between N and N was observed at a peak intensity Is = 0.05234. The relationship between the peak intensities of Is and Io was Is> Io.

In the IR spectrum of the electrolyte solution of Example 14 shown in FIG. 3, there is a slight characteristic peak (Io = 0.997) derived from the stretching vibration of the triple bond between C and N of acetonitrile in the vicinity of 2250 cm ^−1. ) Observed. More IR spectrum of FIG. 3, 2250 cm characteristic peaks peak intensity derived from the stretching vibration of the triple bond between the vicinity of ^-1 acetonitrile near 2280 cm ^-1 shifted to the high frequency side C and N Is = 0 .08288. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 8 × Io.

In the IR spectrum of the electrolyte solution of Example 13 shown in FIG. 4, the same intensity peak as that in the IR chart of FIG. 3 was observed at the same wave number. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 11 × Io.

The IR spectrum of the electrolyte solution of Example 11 shown in Figure 5, is not a peak derived from acetonitrile observed around 2250 cm ^-1, acetonitrile near 2280 cm ^-1 shifted from the vicinity of 2250 cm ^-1 to the high frequency side C And a characteristic peak derived from the stretching vibration of the triple bond between N and N was observed at the peak intensity Is = 0.07350. The relationship between the peak intensities of Is and Io was Is> Io.

In the IR spectrum of the electrolyte solution of Comparative Example 7 shown in FIG. 6, a characteristic peak derived from the stretching vibration of the triple bond between C and N of acetonitrile is observed in the vicinity of 2250 cm ^{−1 in} the IR spectrum of FIG. = 0.04441. More IR spectrum of FIG. 6, 2250 cm characteristic peaks peak intensity derived from the stretching vibration of the triple bond between the vicinity of ^-1 acetonitrile near 2280 cm ^-1 shifted to the high frequency side C and N Is = 0 .03018. The relationship between peak intensities of Is and Io was Is <Io.

In the IR spectrum of the electrolytic solution of Comparative Example 14 shown in FIG. 7, a characteristic peak derived from the stretching vibration of the triple bond between C and N of acetonitrile is observed in the vicinity of 2250 cm ^{−1 in} the IR spectrum of FIG. = 0.04975. More IR spectrum of Figure 7, 2250 cm characteristic peaks peak intensity derived from the stretching vibration of the triple bond between the vicinity of ^-1 acetonitrile near 2280 cm ^-1 shifted to the high frequency side C and N Is = 0 .03804. The relationship between peak intensities of Is and Io was Is <Io.

In the vicinity of 1750 cm ⁻¹ of the IR spectrum of dimethyl carbonate shown in FIG. 17, a characteristic peak derived from the stretching vibration of the double bond between C and O of dimethyl carbonate was observed. Note that no special peak was observed in the vicinity of 1750 cm ^{−1 in} the IR spectrum of (FSO ₂ ) ₂ NLi shown in FIG.

In the IR spectrum of the electrolyte solution of Example 15 shown in FIG. 11, there is a slight characteristic peak (Io = 0) derived from stretching vibration of the double bond between C and O of dimethyl carbonate around 1750 cm ^−1. 16628) was observed. More IR spectrum of Figure 11, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O of dimethyl carbonate in the vicinity of 1717 cm ^-1 shifted from the vicinity of 1750 cm ^-1 to a lower wavenumber side = 0.48032. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.89 × Io.

In the IR spectrum of the electrolyte solution of Example 16 shown in FIG. 12, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of dimethyl carbonate in the vicinity of 1750 cm ^−1. 18129) was observed. More IR spectrum of Figure 12, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O of dimethyl carbonate in the vicinity of 1717 cm ^-1 shifted from the vicinity of 1750 cm ^-1 to a lower wavenumber side = 0.52005 was observed. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.87 × Io.

In the IR spectrum of the electrolyte solution of Example 17 shown in FIG. 13, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of dimethyl carbonate in the vicinity of 1750 cm ^−1. 20293) was observed. More IR spectrum of Figure 13, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O of dimethyl carbonate in the vicinity of 1717 cm ^-1 shifted from the vicinity of 1750 cm ^-1 to a lower wavenumber side = 0.53091. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.62 × Io.

In the IR spectrum of the electrolyte solution of Example 18 shown in FIG. 14, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of dimethyl carbonate around 1750 cm ^−1. 23891) was observed. More IR spectrum of Figure 14, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O of dimethyl carbonate in the vicinity of 1717 cm ^-1 shifted from the vicinity of 1750 cm ^-1 to a lower wavenumber side = 0.53098. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.22 × Io.

In the IR spectrum of the electrolyte solution of Example 19 shown in FIG. 15, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of dimethyl carbonate in the vicinity of 1750 cm ^−1. 30514) was observed. More IR spectrum of Figure 15, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O of dimethyl carbonate in the vicinity of 1717 cm ^-1 shifted from the vicinity of 1750 cm ^-1 to a lower wavenumber side = 0.50223. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 1.65 × Io.

In the IR spectrum of the electrolytic solution of Comparative Example 15 shown in FIG. 16, a characteristic peak derived from stretching vibration of a double bond between C and O of dimethyl carbonate (Io = 0.48204) is around 1750 cm ^−1. ) Observed. More IR spectrum of Figure 16, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O of dimethyl carbonate in the vicinity of 1717 cm ^-1 shifted from the vicinity of 1750 cm ^-1 to a lower wavenumber side = 0.39244. The relationship between peak intensities of Is and Io was Is <Io.

In the vicinity of 1745 cm ⁻¹ of the IR spectrum of ethyl methyl carbonate shown in FIG. 22, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethyl methyl carbonate was observed.

In the IR spectrum of the electrolyte solution of Example 20 shown in FIG. 18, a characteristic peak derived from stretching vibration of double bond between C and O of ethylmethyl carbonate is slightly observed around 1745 cm ⁻¹ (Io = 0.13582) was observed. Further, in the IR spectrum of FIG. 18, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethylmethyl carbonate is observed at about 1711 cm ⁻¹ shifted from the vicinity of 1745 cm ⁻¹ to the lower wavenumber side. Observed at Is = 0.45888. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 3.38 × Io.

In the IR spectrum of the electrolyte solution of Example 21 shown in FIG. 19, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethylmethyl carbonate is slightly observed near 1745 cm ⁻¹ (Io = 0.15151) was observed. Further, in the IR spectrum of FIG. 19, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethylmethyl carbonate is observed near 1711 cm ⁻¹ shifted from the vicinity of 1745 cm ⁻¹ to the lower wavenumber side. Observed at Is = 0.48779. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 3.22 × Io.

In the IR spectrum of the electrolyte solution of Example 22 shown in FIG. 20, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethylmethyl carbonate is slightly observed near 1745 cm ⁻¹ (Io = 0.20191) was observed. Further, in the IR spectrum of FIG. 20, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethylmethyl carbonate is observed near 1711 cm ⁻¹ shifted from the vicinity of 1745 cm ⁻¹ to the lower wavenumber side. Observed at Is = 0.408407. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.40 × Io.

The IR spectrum of the electrolyte solution of Comparative Example 16 shown in Figure 21, the characteristic peak derived from stretching vibration of double bonds between C and O ethyl methyl carbonate in the vicinity of 1745 cm ^-1 is (Io = 0. 41907) was observed. Furthermore, in the IR spectrum of FIG. 21, a characteristic peak derived from the stretching vibration of the double bond between C and O of ethylmethyl carbonate is observed near 1711 cm ⁻¹ shifted from the vicinity of 1745 cm ⁻¹ to the lower wavenumber side. Observed at Is = 0.33929. The relationship between peak intensities of Is and Io was Is <Io.

In the vicinity of 1742 cm ⁻¹ of the IR spectrum of diethyl carbonate shown in FIG. 27, a characteristic peak derived from the stretching vibration of the double bond between C and O of diethyl carbonate was observed.

In the IR spectrum of the electrolyte solution of Example 23 shown in FIG. 23, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of diethyl carbonate in the vicinity of 1742 cm ^−1. 11202) was observed. Further, in the IR spectrum of FIG. 23, a characteristic peak derived from the stretching vibration of the double bond between C and O of diethyl carbonate is observed near the peak intensity Is near 1706 cm ⁻¹ shifted from the vicinity of 1742 cm ⁻¹ to the low wavenumber side. = 0.42925. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 3.83 × Io.

In the IR spectrum of the electrolyte solution of Example 24 shown in FIG. 24, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of diethyl carbonate in the vicinity of 1742 cm ^−1. 15231) was observed. Furthermore, in the IR spectrum of FIG. 24, a characteristic peak derived from the stretching vibration of the double bond between C and O of diethyl carbonate is observed near 1706 cm ⁻¹ shifted from the vicinity of 1742 cm ⁻¹ to the low wavenumber side. = 0.45679. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 3.00 × Io.

In the IR spectrum of the electrolyte solution of Example 25 shown in FIG. 25, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of diethyl carbonate in the vicinity of 1742 cm ^−1. 20337) was observed. Furthermore, in the IR spectrum of FIG. 25, a characteristic peak derived from the stretching vibration of the double bond between C and O of diethyl carbonate is observed near the peak intensity Is near 1706 cm ⁻¹ shifted from the vicinity of 1742 cm ⁻¹ to the low wavenumber side. = 0.43841. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.16 × Io.

In the IR spectrum of the electrolyte solution of Comparative Example 17 shown in FIG. 26, there is a characteristic peak (Io = 0.39636) derived from the stretching vibration of the double bond between C and O of diethyl carbonate in the vicinity of 1742 cm ^−1. ) Observed. More IR spectrum of Figure 26, characteristic peaks peak intensity Is derived from stretching vibration of double bonds between C and O in diethyl carbonate in the vicinity of 1709 cm ^-1 shifted from the vicinity of 1742 cm ^-1 to a lower wavenumber side = 0.31129. The relationship between peak intensities of Is and Io was Is <Io.

In the IR spectrum of the electrolyte solution of Example 26 shown in FIG. 29, a characteristic peak derived from the stretching vibration of the double bond between C and O of dimethyl carbonate is slightly observed at around 1747 cm ⁻¹ (Io = 0). 24305) was observed. Further, in the IR spectrum of FIG. 29, a characteristic peak derived from the stretching vibration of the double bond between C and O of dimethyl carbonate is observed at about 1719 cm ⁻¹ shifted from the vicinity of 1747 cm ⁻¹ to the low wavenumber side. = 0.42654. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 1.75 × Io.

In the IR spectrum of the electrolyte solution of Example 27 shown in FIG. 30, there is a slight characteristic peak (Io = 0) derived from the stretching vibration of the double bond between C and O of dimethyl carbonate in the vicinity of 1743 cm ^−1. 18779) was observed. Further, in the IR spectrum of FIG. 30, a characteristic peak derived from the stretching vibration of the double bond between C and O of dimethyl carbonate is observed near 1717 cm ⁻¹ shifted from the vicinity of 1743 cm ⁻¹ to the low wavenumber side. = 0.49461. The relationship between the peak intensities of Is and Io was Is> Io, and Is = 2.63 × Io.

(Evaluation Example 2: Ionic conductivity)
The ionic conductivity of the electrolyte solutions of Examples 1 to 3, 8, 9, 12, 13, 15, 17, 20, 23, 26, and 27 was measured under the following conditions. The results are shown in Table 8.

Ionic conductivity measurement conditions In an Ar atmosphere, an electrolytic solution was sealed in a glass cell with a platinum constant and a known cell constant, and impedance at 30 ° C. and 1 kHz was measured. The ion conductivity was calculated from the impedance measurement result. As the measuring instrument, Solartron 147055BEC (Solartron) was used.

The electrolyte solutions of Examples 1 to 3, 8, 9, 12, 13, 15, 17, 20, 23, 26, and 27 all exhibited ion conductivity. Therefore, it can be understood that any of the electrolyte solutions of the present invention can function as various electrolyte solutions.

(Evaluation Example 3: Viscosity)
The viscosities of the electrolyte solutions of Examples 1 to 3, 8, 9, 12, 13, 15, 17, 20, 23 and Comparative Examples 3, 7, 11, 14 to 17 were measured under the following conditions. The results are shown in Table 9.

Viscosity measurement conditions Using a falling ball viscometer (Lovis 2000M manufactured by Anton Paar GmbH (Anton Paar)), an electrolytic solution was sealed in a test cell under an Ar atmosphere, and the viscosity was measured at 30 ° C.

The viscosity of the electrolyte solution of each example was significantly higher than the viscosity of the electrolyte solution of each comparative example. Therefore, if the battery uses the electrolytic solution of the present invention, leakage of the electrolytic solution is suppressed even if the battery is damaged. Moreover, if the capacitor uses the electrolytic solution of the present invention, even if the capacitor is damaged, electrolytic solution leakage is suppressed.

(Evaluation Example 4: Volatility)
The volatility of the electrolyte solutions of Examples 2, 3, 13, 15, and 17 and Comparative Examples 3, 7, 14, and 15 was measured by the following method.

About 10 mg of the electrolytic solution was put in an aluminum pan and placed in a thermogravimetric apparatus (TA Instruments, SDT600), and the weight change of the electrolytic solution at room temperature was measured. The volatilization rate was calculated by differentiating the weight change (mass%) with time. The maximum volatilization rate was selected and shown in Table 10.

The maximum volatilization rate of the electrolytes of Examples 2, 3, 13, 15, and 17 was significantly smaller than the maximum volatilization rate of Comparative Examples 3, 7, 14, and 15. Therefore, even if the battery using the electrolytic solution of the present invention is damaged, the volatilization rate of the electrolytic solution is small, so that rapid volatilization of the organic solvent to the outside of the battery is suppressed. In addition, even if the capacitor using the electrolytic solution of the present invention is damaged, the volatilization rate of the electrolytic solution is low, so that rapid volatilization of the organic solvent to the outside of the capacitor is suppressed.

(Evaluation Example 5: Combustibility)
The combustibility of the electrolyte solutions of Example 3 and Comparative Example 7 was tested by the following method.

3 drops of the electrolytic solution was dropped on the glass filter with a pipette, and the electrolytic solution was held on the glass filter. The glass filter was held with tweezers, and the glass filter was brought into contact with flame.

The electrolyte solution of Example 3 did not ignite even after indirect flame for 15 seconds. On the other hand, the electrolyte solution of Comparative Example 7 burned out in about 5 seconds.

It was confirmed that the electrolytic solution of the present invention is difficult to burn.

(Evaluation Example 6: Li transportation rate)
The Li transport numbers of the electrolyte solutions of Examples 2 and 13 and Comparative Examples 14 and 18 were measured under the following conditions. The results are shown in Table 11.

Li transport number measurement conditions An NMR tube containing an electrolyte solution was applied to a PFG-NMR apparatus (ECA-500, JEOL), and ⁷ Li, ¹⁹ F was used as a target while changing the magnetic field pulse width. The diffusion coefficient of Li ions and anions in each electrolyte was measured. The Li transport number was calculated by the following formula.
Li transport number = (Li ion diffusion coefficient) / (Li ion diffusion coefficient + anion diffusion coefficient)

The Li transport number of the electrolyte solutions of Examples 2 and 13 was significantly higher than the Li transport number of the electrolyte solutions of Comparative Examples 14 and 18. Here, the Li ion conductivity of the electrolytic solution can be calculated by multiplying the ionic conductivity (total ionic conductivity) contained in the electrolytic solution by the Li transport number. If it does so, it can be said that the electrolyte solution of this invention has the high transport rate of lithium ion (cation) compared with the conventional electrolyte solution which shows comparable ionic conductivity.

Moreover, about the electrolyte solution of Example 13, Li transport number at the time of changing temperature was measured according to the said Li transport number measurement conditions. The results are shown in Table 12.

From the results of Table 12, it can be seen that the electrolytic solution of the present invention maintains a suitable Li transport number regardless of the temperature. It can be said that the electrolytic solution of the present invention maintains a liquid state even at a low temperature.

(Evaluation Example 7: Low temperature test)
The electrolyte solutions of Examples 15, 17, 20, and 23 were put in containers, filled with an inert gas, and sealed. These were stored in a freezer at −30 ° C. for 2 days. Each electrolyte was observed after storage. None of the electrolytes were solidified and maintained in a liquid state, and no salt deposition was observed.

(Evaluation Example 8: Raman spectrum measurement)
For the electrolyte solutions of Example 12, Example 13, Comparative Example 14, and Example 15, Example 17, Example 19, and Comparative Example 15, Raman spectrum measurement was performed under the following conditions. FIGS. 31 to 37 show Raman spectra in which peaks derived from the anion portion of the metal salt of each electrolytic solution were observed. In the figure, the horizontal axis represents the wave number (cm ⁻¹ ), and the vertical axis represents the scattering intensity.

Raman spectrum measurement conditions Equipment: Laser Raman spectrophotometer (NRS series, JASCO Corporation)
Laser wavelength: 532 nm
The electrolyte was sealed in a quartz cell under an inert gas atmosphere and used for measurement.

The Raman spectra of the electrolytes of Examples 12, 13 and Comparative Example 14 shown in FIGS. 31 to 33 have a characteristic spectrum derived from (FSO ₂ ) ₂ N of LiFSA dissolved in acetonitrile at 700 to 800 cm ^−1. A strong peak was observed. Here, it can be seen from FIGS. 31 to 33 that the peak shifts to the higher wavenumber side as the LiFSA concentration increases. As the electrolyte concentration increases, (FSO ₂ ) ₂ N corresponding to the anion of the salt interacts with Li. In other words, when the concentration is low, Li and the anion become SSIP (Solvent-separated ion pairs). ) State is mainly formed, and it is assumed that a CIP (Contact ion pairs) state and an AGG (aggregate) state are mainly formed as the concentration is increased. It can be considered that such a change in the state was observed as a peak shift of the Raman spectrum.

Embodiment shown in FIGS. 34-37 15, Example 17, Example 19, to 700 ~ 800 cm ^-1 in the Raman spectrum of the electrolyte solution of Comparative Example 15, the LiFSA dissolved in dimethyl carbonate _(FSO _{2) 2} N A characteristic peak derived from was observed. Here, it can be seen from FIGS. 34 to 37 that the peak shifts to the higher wavenumber side as the LiFSA concentration increases. This phenomenon is similar to that discussed in the preceding paragraph, in accordance with the electrolytic solution is highly concentrated, corresponds to the anion of the salt (FSO ₂₎ 2 _N is ready to interact with Li, and, in this state It can be considered that the change was observed as a peak shift of the Raman spectrum.

(Example A)
A half cell using the electrolytic solution of Example 13 was produced as follows.

90 parts by mass of graphite having an average particle diameter of 10 μm as an active material and 10 parts by mass of polyvinylidene fluoride as a binder were mixed. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone to prepare a slurry. A copper foil having a thickness of 20 μm was prepared as a current collector. The slurry was applied in a film form on the surface of the copper foil using a doctor blade. The copper foil coated with the slurry was dried to remove N-methyl-2-pyrrolidone, and then the copper foil was pressed to obtain a bonded product. The obtained joined product was heat-dried at 120 ° C. for 6 hours with a vacuum dryer to obtain a copper foil on which an active material layer was formed. This was the working electrode.

The counter electrode was metal Li.

A half cell is constructed by storing Whatman glass fiber filter paper having a thickness of 400 μm as a separator sandwiched between a working electrode, a counter electrode, and both, and an electrolyte of Example 13 in a battery case (CR2032 type coin cell case manufactured by Hosen Co., Ltd.). did. This was designated as the half cell of Example A.

(Comparative Example A)
A half cell of Comparative Example A was produced in the same manner as in Example A except that the electrolytic solution of Comparative Example 18 was used as the electrolytic solution.

(Evaluation Example 9: Rate characteristics)
The rate characteristics of the half cells of Example A and Comparative Example A were tested by the following method.

The half cell is charged at a rate of 0.1 C, 0.2 C, 0.5 C, 1 C, and 2 C (1 C means a current value required to fully charge or discharge the battery in one hour at a constant current). After the discharge, discharge was performed, and the capacity (discharge capacity) of the working electrode at each speed was measured. In this description, the counter electrode is regarded as a negative electrode and the working electrode is regarded as a positive electrode. The ratio (rate characteristic) of the capacity at other rates to the capacity of the working electrode at the 0.1 C rate was calculated. The results are shown in Table 13.

The half cell of Example A shows excellent rate characteristics because the decrease in capacity is suppressed compared to the half cell of Comparative Example A at any rate of 0.2C, 0.5C, 1C, and 2C. It was. It was confirmed that the secondary battery using the electrolytic solution of the present invention exhibits excellent rate characteristics.

(Evaluation Example 10: Responsiveness to repeated rapid charge / discharge)
With respect to the half cells of Example A and Comparative Example A, changes in capacity and voltage were observed when charging and discharging were repeated three times at a 1C rate. The results are shown in FIG.

The half cell of Comparative Example A has a tendency to increase the polarization when a current is passed at a rate of 1 C as charging and discharging are repeated, and the capacity obtained before reaching 2 V to 0.01 V rapidly decreases. On the other hand, even if charging and discharging were repeated, the half cell of Example A maintained the capacity suitably with almost no increase or decrease in polarization as can be confirmed from the overlapping of the three curves in FIG. The reason why the polarization increased in Comparative Example A is that the electrolyte solution cannot supply a sufficient amount of Li to the reaction interface with the electrode due to the uneven Li concentration generated in the electrolyte solution when charging and discharging are rapidly repeated. That is, uneven distribution of the Li concentration of the electrolytic solution can be considered. In Example A, it is considered that the uneven distribution of Li concentration in the electrolyte solution could be suppressed by using the electrolyte solution of the present invention having a high Li concentration. It was confirmed that the secondary battery using the electrolytic solution of the present invention exhibits excellent responsiveness to rapid charge / discharge. Moreover, it can be said that the graphite-containing electrode exhibits excellent responsiveness to rapid charge / discharge in the presence of the electrolytic solution of the present invention.

In addition, as described above, since the lithium ion capacitor involves an electrochemical reaction (battery reaction) between the negative electrode and the electrolytic solution that is equal to that of the lithium ion secondary battery during charging and discharging, the electrochemical generated between the negative electrode and the electrolytic solution. The reaction (battery reaction) requires reversibility and speed. Here, the reversibility and speed of the electrochemical reaction (battery reaction) that occurs between the negative electrode and the electrolyte solution required for the lithium ion capacitor can be evaluated in the evaluation examples for the half cell described above or below. From the results in Table 13, it can be said that the graphite-containing electrode of the lithium ion capacitor exhibits excellent rate characteristics and reversibility in the presence of the electrolytic solution of the present invention.

(Example B)
A lithium ion secondary battery using the electrolytic solution of Example 13 was produced as follows.

94 parts by mass of a lithium-containing metal oxide having a layered rock salt structure represented by LiNi _5/10 Co _2/10 Mn _3/10 O _{2 as} a positive electrode active material, 3 parts by mass of acetylene black as a conductive auxiliary agent, and a binder 3 parts by mass of polyvinylidene fluoride as an agent was mixed. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone to prepare a slurry. An aluminum foil having a thickness of 20 μm was prepared as a positive electrode current collector. The slurry was applied to the surface of the aluminum foil using a doctor blade so as to form a film. The aluminum foil coated with the slurry was dried at 80 ° C. for 20 minutes to remove N-methyl-2-pyrrolidone by volatilization. Thereafter, this aluminum foil was pressed to obtain a bonded product. The obtained joined product was heat-dried at 120 ° C. for 6 hours with a vacuum dryer to obtain an aluminum foil on which a positive electrode active material layer was formed. This was used as a positive electrode.

98 parts by mass of natural graphite as a negative electrode active material, 1 part by mass of styrene butadiene rubber as a binder and 1 part by mass of carboxymethyl cellulose were mixed. This mixture was dispersed in an appropriate amount of ion-exchanged water to prepare a slurry. A copper foil having a thickness of 20 μm was prepared as a negative electrode current collector. The slurry was applied in a film form on the surface of the copper foil using a doctor blade. The copper foil coated with the slurry was dried to remove water, and then the copper foil was pressed to obtain a bonded product. The obtained joined product was dried by heating at 100 ° C. for 6 hours with a vacuum dryer to obtain a copper foil on which a negative electrode active material layer was formed. This was used as a negative electrode.

As a separator, experimental filter paper (Toyo Filter Paper Co., Ltd., cellulose, thickness 260 μm) was prepared.

A separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then the electrolyte solution of Example 13 was injected into the bag-like laminated film. Thereafter, the remaining one side was sealed to obtain a lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. This battery was referred to as a lithium ion secondary battery of Example B.

(Comparative Example B)
A lithium ion secondary battery of Comparative Example B was produced in the same manner as in Example B, except that the electrolytic solution of Comparative Example 18 was used as the electrolytic solution.

(Evaluation Example 11: Thermal stability)
The thermal stability of the electrolyte solution with respect to the charged positive electrode of the lithium ion secondary battery of Example B and Comparative Example B was evaluated by the following method.

The lithium ion secondary battery was fully charged under the constant charging and constant voltage conditions of 4.2V. The fully charged lithium ion secondary battery was disassembled and the positive electrode was taken out. 3 mg of the positive electrode and 1.8 μL of the electrolytic solution were placed in a stainless steel pan, and the pan was sealed. Using a sealed pan, under a nitrogen atmosphere, the heating rate was 20 ° C / min. The differential scanning calorimetry was performed under the conditions described above, and the DSC curve was observed. A Rigaku DSC8230 was used as a differential scanning calorimeter. FIG. 39 is a DSC chart of the lithium ion secondary battery of Example B in which the charged positive electrode and the electrolyte solution coexist. FIG. 39 shows the charged state positive electrode of the lithium ion secondary battery in Comparative Example B and the electrolyte solution. FIG. 40 shows DSC charts in the case of the above.

As is apparent from the results of FIGS. 39 and 40, the DSC curve in the case where the charged positive electrode and the electrolyte solution coexist in the lithium ion secondary battery of Example B showed almost no endothermic peak. On the other hand, an exothermic peak was observed around 300 ° C. in the DSC curve when the positive electrode in the charged state of the lithium ion secondary battery of Comparative Example B and the electrolyte were present. This exothermic peak is presumed to have occurred as a result of the reaction between the positive electrode active material and the electrolytic solution.

From these results, the lithium ion secondary battery using the electrolytic solution of the present invention has a lower reactivity between the positive electrode active material and the electrolytic solution than the lithium ion secondary battery using the conventional electrolytic solution, It turns out that it is excellent in thermal stability.

(Example C)
A lithium ion secondary battery of Example C using the electrolytic solution of Example 13 was produced as follows.

The positive electrode was produced in the same manner as the positive electrode of the lithium ion secondary battery of Example B.

A cellulose nonwoven fabric having a thickness of 20 μm was prepared as a separator.

A separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then the electrolyte solution of Example 13 was injected into the bag-like laminated film. Thereafter, the remaining one side was sealed to obtain a lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. This battery was referred to as a lithium ion secondary battery of Example C.

(Example D)
A lithium ion secondary battery of Example D using the electrolytic solution of Example 13 was produced as follows.

90 parts by mass of natural graphite as a negative electrode active material and 10 parts by mass of polyvinylidene fluoride as a binder were mixed. This mixture was dispersed in an appropriate amount of ion-exchanged water to prepare a slurry. A copper foil having a thickness of 20 μm was prepared as a negative electrode current collector. The slurry was applied in a film form on the surface of the copper foil using a doctor blade. The copper foil coated with the slurry was dried to remove water, and then the copper foil was pressed to obtain a bonded product. The obtained joined product was heat-dried at 120 ° C. for 6 hours with a vacuum dryer to obtain a copper foil on which a negative electrode active material layer was formed. This was used as a negative electrode.

A separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then the electrolyte solution of Example 13 was injected into the bag-like laminated film. Thereafter, the remaining one side was sealed to obtain a lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. This battery was referred to as a lithium ion secondary battery of Example D.

(Comparative Example C)
A lithium ion secondary battery of Comparative Example C was produced in the same manner as Example C except that the electrolytic solution of Comparative Example 18 was used.

(Comparative Example D)
A lithium ion secondary battery of Comparative Example D was produced in the same manner as Example D except that the electrolytic solution of Comparative Example 18 was used.
(Evaluation Example 12: Input / output characteristics of a lithium ion secondary battery)
The output characteristics of the lithium ion secondary batteries of Examples C and D and Comparative Examples C and D were evaluated under the following conditions.

(1) Evaluation of input characteristics at 0 ° C. or 25 ° C. and SOC 80% Evaluation conditions were a state of charge (SOC) 80%, 0 ° C. or 25 ° C., a working voltage range 3V-4.2V, and a capacity 13.5 mAh. The input characteristics were evaluated three times for each battery for a 2-second input and a 5-second input.

Also, based on the volume of each battery, the battery output density (W / L) at 25 ° C. for 2 seconds was calculated.

Table 14 shows the evaluation results of the input characteristics. “2-second input” in Table 14 means an input after 2 seconds from the start of charging, and “5-second input” means an input after 5 seconds from the start of charging.

As shown in Table 14, the input of the battery of Example C was significantly higher than the input of the battery of Comparative Example C regardless of the temperature difference. Similarly, the input of the battery of Example D was significantly higher than the input of the battery of Comparative Example D.

Also, the battery input density of the battery of Example C was significantly higher than the battery input density of the battery of Comparative Example C. Similarly, the battery input density of the battery of Example D was significantly higher than the battery input density of the battery of Comparative Example D.

(2) Evaluation of output characteristics at 0 ° C. or 25 ° C. and SOC 20% Evaluation conditions were a state of charge (SOC) 20%, 0 ° C. or 25 ° C., operating voltage range 3V-4.2V, and capacity 13.5 mAh. SOC 20%, 0 ° C. is a region where output characteristics are difficult to be obtained, for example, when used in a refrigerator room. The output characteristics were evaluated three times for each battery for the 2-second output and 5-second output.

Also, based on the volume of each battery, the battery output density (W / L) at 25 ° C. for 2 seconds output was calculated.

Table 14 shows the evaluation results of the output characteristics. In Table 14, “2 seconds output” means an output 2 seconds after the start of discharge, and “5 seconds output” means an output 5 seconds after the start of discharge.

As shown in Table 14, the output of the battery of Example C was significantly higher than the output of the battery of Comparative Example C, regardless of the difference in temperature. Similarly, the output of the battery of Example D was significantly higher than the output of the battery of Comparative Example D.

Also, the battery output density of the battery of Example C was significantly higher than the battery output density of the battery of Comparative Example C. Similarly, the battery output density of the battery of Example D was significantly higher than the battery output density of the battery of Comparative Example D.

(Example E)
A half cell using the electrolytic solution of Example 13 was produced as follows.

90 parts by mass of graphite having an average particle diameter of 10 μm as an active material and 10 parts by mass of polyvinylidene fluoride as a binder were mixed. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone to prepare a slurry. A copper foil having a thickness of 20 μm was prepared as a current collector. The slurry was applied in a film form on the surface of the copper foil using a doctor blade. The copper foil coated with the slurry was dried to remove N-methyl-2-pyrrolidone, and then the copper foil was pressed to obtain a bonded product. The obtained joined product was heat-dried at 120 ° C. for 6 hours with a vacuum dryer to obtain a copper foil on which an active material layer was formed. This was the working electrode. In addition, the mass of the active material per 1 cm ^{2 of} copper foil was 1.48 mg. Further, the density of graphite and polyvinylidene fluoride before pressing was 0.68 g / cm ³ , and the density of the active material layer after pressing was 1.025 g / cm ³ .

The counter electrode was metal Li.

A working case, a counter electrode, 400 μm-thick ｍWhatman glass fiber filter paper sandwiched between them, and the electrolyte solution of Example 13 were used in a battery case with a diameter of 13.82 mm (CR2032-type coin cell case manufactured by Hosen Co., Ltd.). And a half cell was constructed. This was designated as the half cell of Example E.

(Example F)
A half cell of Example F was produced in the same manner as in Example E except that the electrolytic solution of Example 15 was used as the electrolytic solution.

(Example G)
A half cell of Example G was produced in the same manner as in Example E, except that the electrolytic solution of Example 20 was used as the electrolytic solution.

(Example H)
A half cell of Example H was produced in the same manner as in Example E except that the electrolytic solution of Example 23 was used as the electrolytic solution.

(Comparative Example E)
A half cell of Comparative Example E was produced in the same manner as in Example E, except that the electrolytic solution of Comparative Example 18 was used as the electrolytic solution.

(Evaluation Example 13: Rate characteristics)
The rate characteristics of the half cells of Examples E to H and Comparative Example E were tested by the following method. The half cell is charged at a rate of 0.1 C, 0.2 C, 0.5 C, 1 C, and 2 C (1 C means a current value required to fully charge or discharge the battery in one hour at a constant current). After the discharge, discharge was performed, and the capacity (discharge capacity) of the working electrode at each speed was measured. In this description, the counter electrode is regarded as a negative electrode and the working electrode is regarded as a positive electrode. The ratio (rate characteristic) of the capacity at other rates to the capacity of the working electrode at the 0.1 C rate was calculated. The results are shown in Table 15.

In the half cells of Examples E to H, the decrease in capacity is suppressed at the rates of 0.2C, 0.5C, and 1C, and in Examples E and F, the rate of 2C is also reduced compared to the half cell of Comparative Example E. It was confirmed that it showed excellent rate characteristics. In addition, it can be said that the graphite-containing electrode exhibits excellent rate characteristics in the presence of the electrolytic solution of the present invention.

(Evaluation Example 14: Capacity maintenance rate)
The capacity retention rates of the half cells of Examples E to H and Comparative Example E were tested by the following method.

Each half cell is charged with a 2.0V-0.01V charge / discharge cycle in which CC charging (constant current charging) is performed to 25 ° C. and voltage 2.0V, and CC discharging (constant current discharging) is performed to voltage 0.01V. Perform 3 cycles at a discharge rate of 0.1C, then charge and discharge 3 cycles at each charge / discharge rate in the order of 0.2C, 0.5C, 1C, 2C, 5C, 10C, and finally 3 at 0.1C. Cycle charge / discharge was performed. The capacity retention rate (%) of each half cell was determined by the following formula.
Capacity maintenance rate (%) = B / A × 100
A: Discharge capacity of the second working electrode in the first 0.1 C charge / discharge cycle B: Discharge capacity of the second working electrode in the last 0.1 C charge / discharge cycle Table 16 shows the results. In this description, the counter electrode is regarded as a negative electrode and the working electrode is regarded as a positive electrode.

All of the half cells performed a charge / discharge reaction satisfactorily and exhibited a suitable capacity retention rate. In particular, the capacity retention rates of the half cells of Examples F, G, and H were remarkably excellent. In addition, it can be said that the graphite-containing electrode exhibits an excellent capacity retention rate in the presence of the electrolytic solution of the present invention.

(Evaluation Example 15: Reversibility of charge / discharge)
The half cells of Examples E to H and Comparative Example E are subjected to CC charging (constant current charging) to 25 ° C. and a voltage of 2.0 V, and CC discharging (constant current discharging) to a voltage of 0.01 V is 2.0 V-0. A charge / discharge cycle of .01V was performed for 3 cycles at a charge / discharge rate of 0.1C. The charge / discharge curves of each half cell are shown in FIGS.

41 to 45, it can be seen that the half cells of Examples E to H are reversibly charged and discharged similarly to the half cell of Comparative Example E using a general electrolytic solution. In addition, it can be said that the graphite-containing electrode is reversibly charged and discharged in the presence of the electrolytic solution of the present invention.

Example I
A half cell using the electrolytic solution of Example 13 was produced as follows.
An aluminum foil (JIS A1000 series) having a diameter of 13.82 mm, an area of 1.5 cm ² and a thickness of 20 μm was used as a working electrode, and the counter electrode was metal Li. As the separator, Whatman glass filter nonwoven fabric having a thickness of 400 μm: product number 1825-055 was used.
The working electrode, the counter electrode, the separator, and the electrolyte solution of Example 13 were accommodated in a battery case (CR2032-type coin cell case manufactured by Hosen Co., Ltd.) to form a half cell. This was designated as the half cell of Example I.

(Example J)
A half cell of Example J was produced in the same manner as the half cell of Example I except that the electrolyte solution of Example 15 was used.

(Example K)
A half cell of Example K was produced in the same manner as the half cell of Example I except that the electrolyte solution of Example 17 was used.

(Example L)
A half cell of Example L was produced in the same manner as the half cell of Example I except that the electrolytic solution of Example 20 was used.

(Example M)
A half cell of Example M was produced in the same manner as the half cell of Example I except that the electrolyte solution of Example 23 was used.

(Comparative Example F)
A half cell of Comparative Example F was produced in the same manner as the half cell of Example I except that the electrolytic solution of Comparative Example 18 was used.

(Comparative Example G)
A half cell of Comparative Example G was produced in the same manner as the half cell of Example I except that the electrolytic solution of Comparative Example 15 was used.

(Evaluation Example 16: Cyclic voltammetry evaluation with working electrode Al)
For the half cells of Examples I to J, L to M and Comparative Example F, cyclic voltammetry evaluation was performed for 5 cycles under conditions of 3.1 V to 4.6 V and 1 mV / s, and then 3.1 V to 5 Cyclic voltammetry evaluation was performed for 5 cycles under the conditions of 1 V and 1 mV / s. Graphs showing the relationship between the potential and the response current for the half cells of Examples I to J, L to M, and Comparative Example F are shown in FIGS.

Further, for the half cells of Examples J and K and Comparative Example G, cyclic voltammetry evaluation was performed for 10 cycles under the conditions of 3.0 V to 4.5 V and 1 mV / s, and then 3.0 V to 5. Cyclic voltammetry evaluation for 10 cycles was performed under the conditions of 0 V and 1 mV / s. Graphs showing the relationship between the potential and the response current for the half cells of Examples J and K and Comparative Example G are shown in FIGS.

FIG. 54 shows that in the half cell of Comparative Example F, a current flows from 3.1 V to 4.6 V after the second cycle, and the current increases as the potential increases. Also, from FIGS. 59 and 60, in the half cell of Comparative Example G as well, the current flows from 3.0 V to 4.5 V after the second cycle, and the current increases as the potential increases. This current is presumed to be the oxidation current of Al due to the corrosion of the working electrode aluminum.

On the other hand, it can be seen from FIGS. 46 to 53 that in the half cells of Examples I to J and L to M, almost no current flows from 3.1 V to 4.6 V after two cycles. Although a slight increase in current was observed as the potential increased at 4.3 V or higher, the amount of current decreased as the cycle was repeated, and the steady state was reached. In particular, in the half cells of Examples J and L to M, no significant increase in current was observed up to a high potential of 5.1 V, and a decrease in the amount of current was observed as the cycle was repeated.

Also, from FIGS. 55 to 58, it can be seen that also in the half cells of Examples J and K, almost no current flows from 3.0 V to 4.5 V after two cycles. In particular, after the third cycle, there is almost no increase in current up to 4.5V. In the half cell of Example K, an increase in current is observed after 4.5 V, which is a high potential, which is much smaller than the current value after 4.5 V in the half cell of Comparative Example G. . For the half cell of Example J, there was almost no increase in current from 4.5V to 5.0V, and a decrease in the amount of current was observed as the cycle was repeated.

From the results of cyclic voltammetry evaluation, it can be said that the corrosiveness of each electrolyte solution of Example 13, Example 15, Example 17, Example 20 and Example 23 to aluminum is low even under high potential conditions exceeding 5V. That is, it can be said that each electrolyte solution of Example 13, Example 15, Example 17, Example 20 and Example 23 is a preferable electrolyte solution for batteries and capacitors using aluminum as a current collector or the like.

Example N
A lithium ion secondary battery of Example N was obtained in the same manner as in Example A except that the electrolytic solution of Example 12 was used as the electrolytic solution.

(Comparative Example H)
A lithium ion secondary battery of Comparative Example H was obtained in the same manner as in Example N except that the electrolytic solution of Comparative Example 18 was used as the electrolytic solution.

(Evaluation Example 17: Rate characteristics at low temperature)
Using the lithium ion secondary batteries of Example N and Comparative Example H, the rate characteristics at −20 ° C. were evaluated as follows. The results are shown in FIGS. 61 and 62.
(1) Current is passed in the direction in which lithium occlusion proceeds to the negative electrode (evaluation electrode).
(2) Voltage range: 2 V → 0.01 V (vs. Li ^/ Li ⁺ )
(3) Rate: 0.02C, 0.05C, 0.1C, 0.2C, 0.5C (current stopped after reaching 0.01V)
1C represents a current value required to fully charge or discharge the battery in one hour at a constant current.

61 and 62, the voltage curve of the lithium ion secondary battery of Example N at each current rate shows a higher voltage than the voltage curve of the lithium ion secondary battery of Comparative Example H. Recognize. In the presence of the electrolytic solution of the present invention, it can be said that the graphite-containing electrode exhibits excellent rate characteristics even in a low temperature environment. That is, it was confirmed that the lithium ion secondary battery and the lithium ion capacitor using the electrolytic solution of the present invention exhibit excellent rate characteristics even in a low temperature environment.

(Example O)
A lithium ion secondary battery of Example O using the electrolytic solution of Example 13 was produced as follows.

90 parts by mass of a lithium-containing metal oxide having a layered rock salt structure represented by LiNi _5/10 Co _2/10 Mn _3/10 O _{2 as} a positive electrode active material, 8 parts by mass of acetylene black as a conductive auxiliary agent, and a binder 2 parts by mass of polyvinylidene fluoride as an agent was mixed. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone to prepare a slurry. An aluminum foil having a thickness of 20 μm was prepared as a positive electrode current collector. The slurry was applied to the surface of the aluminum foil using a doctor blade so as to form a film. The aluminum foil coated with the slurry was dried at 80 ° C. for 20 minutes to remove N-methyl-2-pyrrolidone by volatilization. Thereafter, this aluminum foil was pressed to obtain a bonded product. The obtained joined product was heat-dried at 120 ° C. for 6 hours with a vacuum dryer to obtain an aluminum foil on which a positive electrode active material layer was formed. This was used as a positive electrode.

A separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then the electrolyte solution of Example 13 was injected into the bag-like laminated film. Thereafter, the remaining one side was sealed to obtain a lithium ion secondary battery in which the four sides were hermetically sealed and the electrode plate group and the electrolyte were sealed. This battery was referred to as the lithium ion secondary battery of Example O.

(Example P)
A lithium ion secondary battery of Example P was obtained in the same manner as in Example O except that the electrolytic solution of Example 15 was used as the electrolytic solution.

(Example Q)
A lithium ion secondary battery of Example Q was obtained in the same manner as in Example O except that the electrolytic solution of Example 17 was used as the electrolytic solution.

(Comparative Example I)
A lithium ion secondary battery of Comparative Example I was obtained in the same manner as in Example O except that the electrolytic solution of Comparative Example 18 was used as the electrolytic solution.

(Evaluation Example 18: Internal resistance of battery)
The lithium ion secondary batteries of Examples O to Q and Comparative Example I were prepared, and the internal resistance of the batteries was evaluated.
For each lithium ion secondary battery, CC charge / discharge, that is, constant current charge / discharge was repeated at room temperature in the range of 3.0 V to 4.1 V (vs. Li standard). Then, the AC impedance after the first charge / discharge and the AC impedance after 100 cycles were measured. Based on the obtained complex impedance plane plot, the reaction resistances of the electrolytic solution, the negative electrode, and the positive electrode were each analyzed. As shown in FIG. 63, two circular arcs were seen in the complex impedance plane plot. The arc on the left side of the figure (that is, the side where the real part of the complex impedance is small) is called the first arc. The arc on the right side in the figure is called the second arc. The reaction resistance of the negative electrode was analyzed based on the size of the first arc, and the reaction resistance of the positive electrode was analyzed based on the size of the second arc. The resistance of the electrolytic solution was analyzed based on the leftmost plot in FIG. 63 continuous with the first arc. The analysis results are shown in Table 17 and Table 18. Table 17 shows the resistance (so-called solution resistance) of the electrolytic solution after the first charge / discharge, the reaction resistance of the negative electrode, and the reaction resistance of the positive electrode, and Table 18 shows each resistance after 100 cycles.

As shown in Table 17 and Table 18, in each lithium ion secondary battery, the negative electrode reaction resistance and the positive electrode reaction resistance after 100 cycles tend to be lower than the respective resistances after the first charge / discharge. After 100 cycles shown in Table 18, the negative electrode reaction resistance and the positive electrode reaction resistance of the lithium ion secondary batteries of Examples O to Q were the negative electrode reaction resistance and the positive electrode reaction resistance of the lithium ion secondary battery of Comparative Example I. Low compared to

In addition, the solution resistance of the electrolyte solution in the lithium ion secondary batteries of Examples O and Q and Comparative Example I is substantially the same, and the solution resistance of the electrolyte solution in the lithium ion secondary battery of Example P is the same as that of Example O, Higher than Q and Comparative Example I. Moreover, the solution resistance of each electrolyte solution in each lithium ion secondary battery is the same after the first charge / discharge and after 100 cycles. For this reason, it is considered that the durability deterioration of each electrolytic solution does not occur, and the difference between the negative electrode reaction resistance and the positive electrode reaction resistance generated in the comparative examples and examples described above is not related to the durability deterioration of the electrolyte solution but the electrode. It is thought to have occurred in itself.

The internal resistance of the lithium ion secondary battery can be comprehensively determined from the solution resistance of the electrolytic solution, the reaction resistance of the negative electrode, and the reaction resistance of the positive electrode. Based on the results of Table 17 and Table 18, from the viewpoint of suppressing the increase in internal resistance of the lithium ion secondary battery, the lithium ion secondary batteries of Examples P and Q are the most durable, and then Example O It can be said that the lithium ion secondary battery is excellent in durability.

(Evaluation Example 19: Battery cycle durability)
For the lithium ion secondary batteries of Examples O to Q and Comparative Example I, CC charge / discharge was repeated at room temperature in the range of 3.0 V to 4.1 V (vs. Li standard), and the discharge capacity at the time of initial charge and discharge was 100. The discharge capacity at the cycle and the discharge capacity at the 500th cycle were measured. And the capacity | capacitance maintenance factor (%) of each lithium ion secondary battery at the time of 100 cycles and 500 cycles was computed by making the capacity | capacitance of each lithium ion secondary battery at the time of initial charge / discharge into 100%. The results are shown in Table 19.

As shown in Table 19, the lithium ion secondary batteries of Examples O to Q were 100 equivalent to the lithium ion secondary battery of Comparative Example I containing EC, although it did not contain EC as a material for SEI. The capacity retention rate during the cycle was shown. This is presumably because the positive electrode and negative electrode in the lithium ion secondary batteries of Examples O to Q have films derived from the electrolytic solution of the present invention. And about the lithium ion secondary battery of Example P, the very high capacity | capacitance maintenance factor was shown also after 500 cycles progress, and it was excellent in especially durability. From this result, it can be said that when DMC is selected as the organic solvent of the electrolytic solution, durability is further improved as compared with the case where AN is selected.

(Example R)
The capacitor of the present invention was manufactured as follows.

MDLC-105N2 manufactured by Hosen Co., Ltd. was used as the positive and negative electrodes of the capacitor of the present invention. A coin-type cell was created with the electrolyte solution of Example 11 soaked in a glass filter and the positive electrode and the negative electrode. This cell was used as the capacitor of Example R. The positive electrode and the negative electrode were vacuum-dried at 120 ° C. for 24 hours before cell preparation, and the cell preparation was performed in an inert gas atmosphere in a glove box adjusted to a dew point of −70 ° C. or less.

(Comparative Example J)
A capacitor of Comparative Example J was produced in the same manner as in Example R, except that 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) amide was used as the electrolytic solution.

(Evaluation Example 20)
The capacitors of Example R and Comparative Example J were tested as follows.
Each capacitor was charged and discharged 10 times at a current density of 100 mA / g and a cut-off voltage of 0 to 1 V, and this was used as conditioning. FIG. 64 shows the final charge / discharge curve of conditioning in each capacitor.
From FIG. 64, it can be seen that the capacitor of Example R has a larger capacity than the capacitor of Comparative Example J.
In addition, the capacitors of Example R and Comparative Example J that had been charged and discharged were charged and discharged at a current density of 100, 500, 1000, and 2000 mA / g at a cut-off voltage of 0 to 2 V. The results are shown in Table 20.

The capacitor of Example R exhibited a capacity equal to or greater than that of Comparative Example J. In particular, the capacitor of Example R showed sufficient capacity even at high rate charge / discharge.

(Example S)
MDLC-105N2 manufactured by Hosen Co., Ltd. was prepared as the positive and negative electrodes of the capacitor. A coin-type cell was prepared using the electrolytic solution of Example 26, a cellulose nonwoven fabric having a thickness of 20 μm, the positive electrode, and the negative electrode. This cell was used as the capacitor of Example S. The positive electrode and the negative electrode were vacuum-dried at 120 ° C. for 24 hours before cell preparation, and the cell preparation was performed in an inert gas atmosphere in a glove box adjusted to a dew point of −70 ° C. or less.

(Comparative Example K)
A capacitor of Comparative Example K was produced in the same manner as Example S, except that 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide was used as the electrolyte.

(Evaluation Example 21)
The following tests were conducted on the capacitors of Example S and Comparative Example K.
Each capacitor was charged and discharged 10 times at a current density of 100 mA / g and a cut-off voltage of 0 to 1 V. Each capacitor subjected to the charge / discharge was charged / discharged at a cut-off voltage of 0 to 2.5 V and a current density of 100 mA / g. The results are shown in FIG. The charge / discharge efficiency is the ratio of the discharge capacity to the charge capacity. In the same manner as described above, the capacitor of Example S was charged and discharged at a current density of 100 mA / g at a cut-off voltage of 0 to 2 V, 0 to 2.5 V, 0 to 3 V, and 0 to 4 V. Charge-discharge curves of cut-off voltages 0 to 2 V, 0 to 2.5 V, and 0 to 3 V are shown in FIGS. 66 to 68, each discharge curve is shown in FIG. 69, and each discharge capacity is shown in Table 22.

From FIG. 65, it can be seen that the charging curve of the capacitor of Comparative Example K deviates from a straight line during charging. In the charging curve, it can be seen that the slope of the charging curve particularly when the voltage exceeds 2 V is small, and the voltage is difficult to increase. This phenomenon is presumed to be because the applied current is used for unwanted irreversible reactions such as decomposition of the electrolyte. Furthermore, it can be seen from the results in Table 21 that the charge / discharge efficiency of the capacitor of Comparative Example K is inferior. On the other hand, since the charging curve of the capacitor of Example S is a straight line and the charge / discharge efficiency is 100%, in the capacitor of Example S, the applied current is used for irreversible reactions such as decomposition of the electrolyte. Therefore, it can be considered that the capacitor works as a capacitor capacity, and it can be said that the capacitor of Example S operates stably.

As shown in FIGS. 66 to 69, the capacitor of Example S operated suitably at each potential. In particular, it is worthy of special mention that the capacitor of Example S was suitably operated even at the charging potential of 4V. From the results of Table 22, it can be seen that the discharge capacity of the capacitor of Example S suitably increases as the charging potential increases.

(Example T)
The lithium ion capacitor of the present invention was manufactured as follows.
The negative electrode was manufactured as follows.

Natural graphite, polyvinylidene fluoride, and N-methyl-2-pyrrolidone were added and mixed to prepare a slurry-like negative electrode mixture. The composition ratio of each component (solid content) in the slurry was graphite: polyvinylidene fluoride = 90: 10 (mass ratio).

When the natural graphite powder used here was subjected to Raman spectrum analysis (apparatus: RMP-320 manufactured by JASCO Corporation: excitation wavelength λ = 532 nm, grating: 1800 gr / mm, resolution: 3 cm ⁻¹ ), the obtained Raman spectrum G The G / D ratio, which is the intensity ratio of -band and D-band peaks, was 12.3.

This slurry-like negative electrode mixture was applied to the surface of an electrolytic copper foil (current collector) having a thickness of 20 μm using a doctor blade, thereby forming a negative electrode active material layer on the copper foil. Then, it dried at 80 degreeC for 20 minute (s), and the organic solvent was volatilized and removed from the negative electrode active material layer. After drying, the current collector and the negative electrode active material layer were firmly and closely joined with a roll press. This was vacuum-dried at 120 ° C. for 6 hours to form a negative electrode having a negative electrode active material layer weight per unit area of 0.9 mg / cm ² and a density of 0.5 g / cm ³ .

A cell was produced with the negative electrode, the electrolyte solution of Example 15, a cellulose nonwoven fabric having a thickness of 20 μm, and the same positive electrode as the positive electrode of the capacitor of Example R, and this cell was designated as the lithium ion capacitor of Example T. .

(Evaluation example 22)
The lithium ion capacitor of Example T was tested as follows.
The capacitor was charged and discharged at a current density of 20 mA / g and a cut-off voltage of 0 to 1 V until the charge / discharge curve was stabilized. The capacitor charged and discharged is charged to 4.5 V at a current density of 20 mA / g, held for 2 hours at a voltage of 4.5 V, and then discharged to 2.5 V at a current density of 20 mA / g. Charging / discharging was performed several times until the charging / discharging curve of the capacitor was stabilized. The last charge / discharge curve is shown in FIG.

70 shows that the lithium ion capacitor of Example T suitably operated as a lithium ion capacitor at a high potential. The lithium ion capacitor of Example T uses graphite for the negative electrode and uses the electrolytic solution of the present invention containing a lithium salt at a high concentration. Here, in general, a lithium ion capacitor using graphite as a negative electrode is required to be previously doped with lithium ions in order to lower the negative electrode potential. However, the lithium ion capacitor of Example T using the electrolytic solution of the present invention stably operated as a lithium ion capacitor at a high potential, even though the negative graphite was not pre-doped with lithium ions. This is because the lithium ion capacitor is operated at a high potential in an environment using the electrolytic solution of the present invention in which lithium ions are present in a large excess in comparison with the conventional electrolytic solution. It can be said that the graphite of the negative electrode is gradually doped. That is, the lithium ion capacitor of the present invention has the advantage that lithium pre-doping from outside the system is unnecessary. In addition, as shown in the following Example U, the lithium ion capacitor of the present invention can be manufactured even by performing lithium pre-doping performed in a normal lithium ion capacitor.

As described above, by using the electrolytic solution of the present invention for a lithium ion capacitor using graphite as the negative electrode, the lithium ions in the electrolytic solution of the present invention can be converted into graphite by charge / discharge without pre-doping the graphite with lithium ions. It was proved that the negative electrode potential of the capacitor was lowered to become a lithium ion capacitor. Here, it is widely known that graphite can insert and desorb cations and anions contained in an electrolyte depending on potential. Therefore, it is possible to provide a capacitor of the type in which anions are inserted and removed from the positive electrode, that is, a capacitor using graphite as the positive electrode.

(Example U)
The lithium ion capacitor of the present invention when lithium pre-doping is performed in a normal lithium ion capacitor can be manufactured as follows.

The negative electrode is manufactured as follows.
Natural graphite, polyvinylidene fluoride, and N-methyl-2-pyrrolidone are added and mixed to prepare a slurry-like negative electrode mixture. The composition ratio of each component (solid content) in the slurry is graphite: polyvinylidene fluoride = 90: 10 (mass ratio).

This slurry-like negative electrode mixture is applied to the surface of an electrolytic copper foil (current collector) having a thickness of 20 μm by using a doctor blade to form a negative electrode active material layer on the copper foil. Thereafter, drying is performed at 80 ° C. for 20 minutes, and the organic solvent is volatilized and removed from the negative electrode active material layer. After drying, the current collector and the negative electrode active material layer are tightly bonded tightly with a roll press. This is vacuum-dried at 120 ° C. for 6 hours to form a negative electrode having a negative electrode active material layer weight per unit area of 0.9 mg / cm ² and a density of 0.5 g / cm ³ . Metal lithium is pressure-bonded to the negative electrode active material layer of the negative electrode, and a cell is prepared with this, the electrolytic solution of Comparative Example 18, and a known carbon electrode, and a cell for lithium pre-doping is obtained. The lithium pre-doping cell is charged and discharged several cycles, the cell is disassembled in a discharged state (a state where lithium is doped into the negative electrode active material), and the lithium pre-doped negative electrode is taken out.

A cell was prepared with a lithium pre-doped negative electrode, an electrolyte solution of Example 15 immersed in a glass filter, and the same positive electrode as the positive electrode of the capacitor of Example R above. An ion capacitor is used.

Claims

An electrolyte solution comprising a salt having alkali metal, alkaline earth metal or aluminum as a cation, and an organic solvent having a hetero element,
Regarding the peak intensity derived from the organic solvent in the vibrational spectrum of the electrolyte solution, when the intensity of the original peak of the organic solvent is Io and the intensity of the peak shifted from the peak is Is, Is> Io. Characteristic electrolyte.
An electrolyte solution comprising a salt having alkali metal, alkaline earth metal or aluminum as a cation, and an organic solvent having a hetero element,
D / c obtained by dividing the density d (g / cm 3 ) of the electrolytic solution by the salt concentration c (mol / L) of the electrolytic solution is 0.15 ≦ d / c ≦ 0.71 .
An electrolyte solution comprising a salt having alkali metal, alkaline earth metal or aluminum as a cation, and an organic solvent having a hetero element,
The electrolyte solution, wherein the electrolyte solution has a viscosity η (mPa · s) of 10 <η <500, and the electrolyte solution has an ionic conductivity σ (mS / cm) of 1 ≦ σ.
4. The electrolytic solution according to claim 1, wherein the cation of the salt is lithium.
The electrolytic solution according to any one of claims 1 to 4, wherein the chemical structure of the anion of the salt contains at least one element selected from halogen, boron, nitrogen, oxygen, sulfur or carbon.
6. The electrolytic solution according to claim 1, wherein the chemical structure of the anion of the salt is represented by the following general formula (1), general formula (2), or general formula (3).
(R 1 X 1 ) (R 2 X 2 ) N General formula (1)
(R 1 is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted with, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, or an alkoxy group which may be substituted with a substituent , An unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, an unsaturated thioalkoxy group that may be substituted with a substituent, CN, SCN, or OCN Is done.
R 2 represents hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, an alkoxy group which may be substituted with a substituent, Selected from an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, CN, SCN, OCN The
R 1 and R 2 may be bonded to each other to form a ring.
X 1 is selected from SO 2 , C = O, C = S, R a P = O, R b P = S, S = O, Si = O.
X 2 is, SO 2, C = O, C = S, R c P = O, R d P = S, S = O, is selected from Si = O.
R a , R b , R c , and R d are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a substituent. An unsaturated alkyl group which may be substituted, an unsaturated cycloalkyl group which may be substituted with a substituent, an aromatic group which may be substituted with a substituent, or a heterocyclic group which may be substituted with a substituent , An alkoxy group that may be substituted with a substituent, an unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, and a non-optionally substituted substituent. Selected from saturated thioalkoxy groups, OH, SH, CN, SCN, OCN.
R a , R b , R c , and R d may be bonded to R 1 or R 2 to form a ring. )
R 3 X 3 Y General formula (2)
(R 3 is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted with, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, or an alkoxy group which may be substituted with a substituent , An unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, an unsaturated thioalkoxy group that may be substituted with a substituent, CN, SCN, or OCN Is done.
X 3 is selected from SO 2 , C = O, C = S, R e P = O, R f P = S, S = O, and Si = O.
R e and R f are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a group that may be substituted with a substituent. A saturated alkyl group, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, a heterocyclic group that may be substituted with a substituent, and a substituent An alkoxy group which may be substituted, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, OH , SH, CN, SCN, and OCN.
R e and R f may combine with R 3 to form a ring.
Y is selected from O and S. )
(R 4 X 4) (R 5 X 5) (R 6 X 6) C Formula (3)
(R 4 is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted with, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, or an alkoxy group which may be substituted with a substituent , An unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, an unsaturated thioalkoxy group that may be substituted with a substituent, CN, SCN, or OCN Is done.
R 5 represents hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, an alkoxy group which may be substituted with a substituent, Selected from an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, CN, SCN, OCN The
R 6 is hydrogen, halogen, an alkyl group which may be substituted with a substituent, a cycloalkyl group which may be substituted with a substituent, an unsaturated alkyl group which may be substituted with a substituent, or a substituent. An unsaturated cycloalkyl group which may be substituted, an aromatic group which may be substituted with a substituent, a heterocyclic group which may be substituted with a substituent, an alkoxy group which may be substituted with a substituent, Selected from an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, CN, SCN, OCN The
Further, any two or three of R 4 , R 5 and R 6 may be bonded to form a ring.
X 4 is, SO 2, C = O, C = S, R g P = O, R h P = S, S = O, is selected from Si = O.
X 5 is selected from SO 2 , C = O, C = S, R i P = O, R j P = S, S = O, Si = O.
X 6 is selected from SO 2 , C = O, C = S, R k P = O, R 1 P = S, S = O, Si = O.
R g , R h , R i , R j , R k , and R l are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, or a cycloalkyl that may be substituted with a substituent. Group, an unsaturated alkyl group that may be substituted with a substituent, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, or a substituent that is substituted with a substituent A heterocyclic group which may be substituted, an alkoxy group which may be substituted with a substituent, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, and a substituent It is selected from an unsaturated thioalkoxy group which may be substituted, OH, SH, CN, SCN, OCN.
R g , R h , R i , R j , R k , and R l may combine with R 4 , R 5, or R 6 to form a ring. )
The electrolytic solution according to any one of claims 1 to 6, wherein the chemical structure of the anion of the salt is represented by the following general formula (4), general formula (5), or general formula (6).
(R 7 X 7 ) (R 8 X 8 ) N General formula (4)
(R 7 and R 8 are each independently C n H a F b Cl c Br d I e (CN) f (SCN) g (OCN) h .
n, a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e + f + g + h.
R 7 and R 8 may combine with each other to form a ring, in which case 2n = a + b + c + d + e + f + g + h is satisfied.
X 7 is, SO 2, C = O, C = S, R m P = O, R n P = S, S = O, is selected from Si = O.
X 8 is selected from SO 2 , C = O, C = S, R o P = O, R p P = S, S = O, Si = O.
R m , R n , R o , and R p are each independently substituted with hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a substituent. An unsaturated alkyl group which may be substituted, an unsaturated cycloalkyl group which may be substituted with a substituent, an aromatic group which may be substituted with a substituent, or a heterocyclic group which may be substituted with a substituent , An alkoxy group that may be substituted with a substituent, an unsaturated alkoxy group that may be substituted with a substituent, a thioalkoxy group that may be substituted with a substituent, and a non-optionally substituted substituent. Selected from saturated thioalkoxy groups, OH, SH, CN, SCN, OCN.
R m , R n , R o , and R p may combine with R 7 or R 8 to form a ring. )
R 9 X 9 Y General formula (5)
(R 9 is a C n H a F b Cl c Br d I e (CN) f (SCN) g (OCN) h.
n, a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e + f + g + h.
X 9 is, SO 2, C = O, C = S, R q P = O, R r P = S, S = O, is selected from Si = O.
R q and R r are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, a cycloalkyl group that may be substituted with a substituent, or a group that may be substituted with a substituent. A saturated alkyl group, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, a heterocyclic group that may be substituted with a substituent, and a substituent An alkoxy group which may be substituted, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, an unsaturated thioalkoxy group which may be substituted with a substituent, OH , SH, CN, SCN, and OCN.
R q and R r may combine with R 9 to form a ring.
Y is selected from O and S. )
(R 10 X 10) (R 11 X 11) (R 12 X 12) C Formula (6)
(R 10 , R 11 , and R 12 are each independently C n H a F b Cl c Br d I e (CN) f (SCN) g (OCN) h .
n, a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e + f + g + h.
Any two of R 10 , R 11 , and R 12 may combine to form a ring, in which case the group forming the ring satisfies 2n = a + b + c + d + e + f + g + h. Further, three of R 10 , R 11 and R 12 may combine to form a ring, in which case two groups out of the three satisfy 2n = a + b + c + d + e + f + g + h, and one group satisfies 2n−1 = a + b + c + d + e + f + g + h. Fulfill.
X 10 is, SO 2, C = O, C = S, R s P = O, R t P = S, S = O, is selected from Si = O.
X 11 is, SO 2, C = O, C = S, R u P = O, R v P = S, S = O, is selected from Si = O.
X 12 is, SO 2, C = O, C = S, R w P = O, R x P = S, S = O, is selected from Si = O.
R s , R t , R u , R v , R w , and R x are each independently hydrogen, halogen, an alkyl group that may be substituted with a substituent, or a cycloalkyl that may be substituted with a substituent. Group, an unsaturated alkyl group that may be substituted with a substituent, an unsaturated cycloalkyl group that may be substituted with a substituent, an aromatic group that may be substituted with a substituent, or a substituent that is substituted with a substituent A heterocyclic group which may be substituted, an alkoxy group which may be substituted with a substituent, an unsaturated alkoxy group which may be substituted with a substituent, a thioalkoxy group which may be substituted with a substituent, and a substituent It is selected from an unsaturated thioalkoxy group which may be substituted, OH, SH, CN, SCN, OCN.
R s , R t , R u , R v , R w , and R x may combine with R 10 , R 11, or R 12 to form a ring. )
The electrolytic solution according to any one of claims 1 to 7, wherein the chemical structure of the anion of the salt is represented by the following general formula (7), general formula (8), or general formula (9).
(R 13 SO 2 ) (R 14 SO 2 ) N General formula (7)
(R 13 and R 14 are each independently C n H a F b Cl c Br d I e .
n, a, b, c, d, and e are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e.
R 13 and R 14 may combine with each other to form a ring, in which case 2n = a + b + c + d + e is satisfied. )
R 15 SO 3 general formula (8)
(R 15 is a C n H a F b Cl c Br d I e.
n, a, b, c, d, and e are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e. )
(R 16 SO 2 ) (R 17 SO 2 ) (R 18 SO 2 ) C General formula (9)
(R 16 , R 17 , and R 18 are each independently C n H a F b Cl c Br d I e .
n, a, b, c, d, and e are each independently an integer of 0 or more, and satisfy 2n + 1 = a + b + c + d + e.
Any two of R 16 , R 17 , and R 18 may combine to form a ring, in which case the group forming the ring satisfies 2n = a + b + c + d + e. Three of R 16 , R 17 and R 18 may combine to form a ring, in which case two groups out of the three satisfy 2n = a + b + c + d + e, and one group satisfies 2n−1 = a + b + c + d + e. Fulfill. )
The salt is (CF 3 SO 2 ) 2 NLi, (FSO 2 ) 2 NLi, (C 2 F 5 SO 2 ) 2 NLi, FSO 2 (CF 3 SO 2 ) NLi, (SO 2 CF 2 CF 2 SO 2 ) The electrolytic solution according to any one of claims 1 to 8, which is NLi or (SO 2 CF 2 CF 2 CF 2 SO 2 ) NLi.
10. The electrolytic solution according to claim 1, wherein the hetero element of the organic solvent is at least one selected from nitrogen, oxygen, sulfur and halogen.
The electrolyte solution according to any one of claims 1 to 10, wherein the organic solvent is an aprotic solvent.
The electrolytic solution according to any one of claims 1 to 11, wherein the organic solvent is selected from acetonitrile or 1,2-dimethoxyethane.
The electrolytic solution according to any one of claims 1 to 11, wherein the organic solvent is selected from chain carbonates represented by the following general formula (10).
R 19 OCOOR 20 general formula (10)
(R 19 and R 20 each independently represent C n H a F b Cl c Br d I e which is a chain alkyl, or C m H f F g Cl h Br i I containing a cyclic alkyl in the chemical structure. .n selected from any of j, a, b, c, d, e, m, f, g, h, i, j are each independently an integer of 0 or more, 2n + 1 = a + b + c + d + e, 2m = f + g + h + i + j Meet)
The electrolytic solution according to any one of claims 1 to 11, wherein the organic solvent is selected from dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.
The electrolyte solution according to any one of claims 1 to 14, wherein the electrolyte solution is a battery electrolyte.
The electrolytic solution according to any one of claims 1 to 15, wherein the electrolytic solution is an electrolytic solution for a secondary battery.
The electrolytic solution according to any one of claims 1 to 16, wherein the electrolytic solution is an electrolytic solution for a lithium ion secondary battery.
A capacitor comprising the electrolytic solution according to claim 1.
A first dissolution step of mixing an organic solvent having a hetero element and a salt having alkali metal, alkaline earth metal or aluminum as a cation, dissolving the salt, and preparing a first electrolytic solution;
A second dissolving step of adding the salt to the first electrolyte under stirring and / or heating conditions, dissolving the salt, and preparing a second electrolyte in a supersaturated state;
The manufacturing method of the electrolyte solution characterized by including the 3rd melt | dissolution process of adding the said salt to the said 2nd electrolyte solution under stirring and / or heating conditions, melt | dissolving the said salt, and preparing a 3rd electrolyte solution.