JP2012209482A - Non-aqueous solvent for electrochemical device, nonaqueous electrolyte for electrochemical device and electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous solvent for electrochemical device capable of increasing energy density by increasing charging voltage.SOLUTION: The non-aqueous solvent for electrochemical device includes an N-phosphine-oxide compound. Since the N-phosphine-oxide has a higher oxidation potential, even when the charging voltage is increased, oxidative decomposition occurs more slowly than propylene carbonate. The N-phosphine-oxide is a high-polarity compound in which nitrogen atoms are charged positively and oxygen atoms are charged negatively, and since the solubility of the supporting electrolyte is high, the nonaqueous electrolyte has a high electrical conductivity. Accordingly, the nonaqueous electrolyte is more advantageous than sulfolane for reducing the resistance value of an electrochemical capacitor.

Description

  The present invention relates to a nonaqueous solvent for an electrochemical device, a nonaqueous electrolytic solution for an electrochemical device using the nonaqueous solvent, and an electrochemical device using the nonaqueous electrolytic solution.

  Electrolytic solutions used in electrochemical devices such as electric double layer capacitors and lithium ion capacitors include aqueous electrolytes composed of strong acids or strong alkalis and nonaqueous electrolytes obtained by dissolving a supporting electrolyte in a nonaqueous solvent. . The aqueous electrolyte solution has a merit that the internal resistance of the electrochemical device can be kept low and a merit that it can be manufactured at a low cost. On the other hand, non-aqueous electrolytes can be charged at a higher voltage than electrochemical devices that use aqueous electrolytes, which can increase the energy density, and electrochemical using aqueous electrolytes. There are advantages such as higher operating temperature than devices.

  As the nonaqueous solvent of the nonaqueous electrolytic solution, for example, as shown in Patent Document 1, cyclic carbonates such as ethylene carbonate and propylene carbonate, chain carbonates such as dimethyl carbonate and diethyl carbonate, γ- Examples include cyclic esters such as butyrolactone, nitriles such as acetonitrile, chain ethers such as dimethoxyethane, cyclic ethers such as tetrahydrofuran and dioxane, and sulfur-containing compounds such as sulfolane. Among these, propylene carbonate is another type. More frequently used than non-aqueous solvents. The reason is that the solubility of the supporting electrolyte, such as ammonium salt and phosphonium salt, is good, and it is easy to obtain a balance of heat-resistant temperature, viscosity, dielectric constant, and the like.

  By the way, an electrochemical device using a non-aqueous electrolyte has a problem of improving a charging voltage in order to improve volume energy density and weight energy density.

  The electric double layer capacitor using propylene carbonate as the nonaqueous solvent of the nonaqueous electrolytic solution will be described as an example. When the charging voltage of the electric double layer capacitor is 2.5V, the potential of the positive electrode becomes + 4.25V. The potential of the negative electrode becomes + 1.75V. Since the value of +4.25 V of this positive electrode is a voltage at which propylene carbonate begins to undergo oxidative decomposition, when charged at a voltage higher than 2.5 V, or when this charge is repeated, propylene carbonate oxidizes and decomposes to generate gas. Occurring and increasing the internal resistance and decreasing the capacitance may occur. That is, in order to increase the charging voltage of the electric double layer capacitor, a non-aqueous solvent having a high decomposition potential is required.

  In addition, in a lithium ion capacitor, for example, as disclosed in Patent Document 1, an active material constituting a negative electrode is preliminarily occluded (hereinafter also referred to as “pre-dope”) to obtain a positive electrode and a negative electrode. Although attempts have been made to increase the potential difference, the same oxidative decomposition as described above may occur during charging, leading to an increase in internal resistance and a decrease in capacitance. A nonaqueous solvent having a high decomposition potential is required.

International Publication Number WO2003 / 003395

  An object of the present invention is to provide a non-aqueous solvent for an electrochemical device, a non-aqueous electrolyte solution for an electrochemical device, and an electrochemical device that can increase the charging voltage and improve the energy density.

  The present invention (non-aqueous solvent for electrochemical devices) is characterized by containing an N-oxide compound.

An example of the N-oxide compound is represented by the following formula (1), and R _{1 to} R ₃ in the formula (1) are each a monovalent saturated hydrocarbon group having 2 to 6 carbon atoms or one It is an N-oxide compound which is a saturated hetero atom-containing saturated hydrocarbon group.

前記Ｎ−オキシド化合物の他の一例は、下記式（２）で表され、且つ、該式（２）中のＲ₄が炭素数が３〜６の一価の飽和炭化水素基又は一価のヘテロ原子含有飽和炭化水素基であり、Ｘが二価の飽和炭化水素基で窒素原子と共に環員数５又は６のヘテロ環を形成している、Ｎ−オキシド化合物である。

Another example of the N-oxide compound is represented by the following formula (2), and R ₄ in the formula (2) is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms or a monovalent group. It is an N-oxide compound which is a heteroatom-containing saturated hydrocarbon group, and X is a divalent saturated hydrocarbon group and forms a heterocycle having 5 or 6 ring members together with a nitrogen atom.

前記Ｎ−オキシド化合物の他の一例は、下記式（３）で表され、且つ、該式（３）中のＲ₅が炭素数が１〜６の一価の飽和炭化水素基で、Ｒ₆、Ｒ₇がそれぞれ炭素数が３〜６の一価の飽和炭化水素基である、Ｎ−オキシド化合物である。

Another example of the N- oxide compound is represented by the following formula (3), and, R ₅ in formula (3) is a saturated monovalent hydrocarbon group having 1 to 6 carbon atoms, R ₆ , R ₇ are each an N-oxide compound which is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms.

前記Ｎ−オキシド化合物の他の一例は、下記式（４）で表され、且つ、該式（４）中のＲ₈が炭素数が３〜６の一価の飽和炭化水素基又は一価のヘテロ原子含有飽和炭化水素基である、Ｎ−オキシド化合物である。

Another example of the N-oxide compound is represented by the following formula (4), and R ₈ in the formula (4) is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms or a monovalent group. It is an N-oxide compound which is a heteroatom-containing saturated hydrocarbon group.

前記Ｎ−オキシド化合物の他の一例は、下記式（５）で表され、且つ、該式（５）中のＲ₉が炭素数が３〜６の一価の飽和炭化水素基又は一価のヘテロ原子含有飽和炭化水素基である、Ｎ−オキシド化合物である。

Another example of the N-oxide compound is represented by the following formula (5), and R ₉ in the formula (5) is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms or a monovalent group. It is an N-oxide compound which is a heteroatom-containing saturated hydrocarbon group.

また、本発明（電気化学デバイス用非水系電解液）は、前記の何れかの非水溶媒と、支持電解質とを含有している、ことをその特徴とする。

Moreover, the present invention (non-aqueous electrolyte solution for electrochemical devices) is characterized by containing any of the non-aqueous solvents described above and a supporting electrolyte.

  Furthermore, the present invention (electrochemical device) is characterized by comprising an electrode and the non-aqueous electrolyte for electrochemical device described above.

  According to the non-aqueous solvent for electrochemical devices, the non-aqueous electrolyte solution for electrochemical devices and the electrochemical device according to the present invention, the energy density can be improved by increasing the charging voltage.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

Side cross-sectional view of electric double layer capacitor Plan view of the electric double layer capacitor shown in FIG. Side sectional view of the electric double layer capacitor shown in FIGS. 1 and 2 with the film package expanded. Examples of N-oxide compounds of formula (1) Examples of N-oxide compounds of formula (2) Examples of N-oxide compounds of formula (3) Examples of N-oxide compounds of formula (4) Examples of N-oxide compounds of formula (5) Table showing experimental results Table showing experimental results Table showing experimental results Side cross-sectional view of lithium ion capacitor Table showing experimental results

<Application to electric double layer capacitors>
Hereinafter, a specific example in which the present invention is applied to a non-aqueous electrolyte for an electric double layer capacitor will be described with reference to FIGS.

<Structure of electric double layer capacitor>
As shown in FIGS. 1 and 2, the electric double layer capacitor includes a positive electrode 10, a negative electrode 20, an electricity storage element B having a separator 30 interposed between the positive electrode 10 and the negative electrode 20, and an electrolyte in a nonaqueous solvent. The dissolved non-aqueous electrolyte, the film package 40 formed of a laminate film and encapsulating the storage element B and the non-aqueous electrolyte, one end connected to the storage element B, and the other end led out from the film package 40 And a pair of terminals 50.

  The positive electrode 10 and the negative electrode 20 are configured by forming polarizable electrode layers 12 and 22 on the surfaces of current collectors 11 and 21 made of a metal foil such as aluminum, and the polarizable electrode layers 12 and 22 are interposed via a separator 30. Are facing each other. The non-aqueous electrolyte solution is impregnated into the polarizable electrode layers 12 and 22 and the separator 30.

  The polarizable electrode layers 12 and 22 are made of, for example, main materials such as polyacene (PAS), polyaniline (PAN), activated carbon, and the like, conductive assistants such as carbon black, graphite, and metal powder, and polytetrafluoroethylene (PTFE). And a binder such as polyvinylidene fluoride (PVDF) and styrene butadiene rubber (SBR) as necessary. As the raw material of activated carbon, sawdust, coconut shell, phenol resin, various heat-resistant plastics, pitch, etc. can be used, for example, polyimide, polyamide, polyamideimide, polyetherimide, polyethersulfone, One kind or two or more kinds of polyether ketone, bismaleimide triazine, aramid, fluororesin, polyphenylene, polyphenylene sulfide and the like can be used. Of course, the material of the polarizable electrode layers 12 and 22 is not limited to the above, and known materials can be used as appropriate.

  The separator 30 is a sheet-like material that can be impregnated with a non-aqueous electrolyte solution, and the sheet-like material is made of, for example, cellulose, polypropylene, polyethylene, fluorine resin, or the like. Of course, the material of the separator 30 is not limited to the above, and known materials can be used as appropriate.

  Incidentally, FIG. 3 shows a state in which the film package 40 of the electric double layer capacitor shown in FIGS. 1 and 2 is expanded and the thickness T1 of the film package 40 is increased to the thickness T2.

<Composition of non-aqueous electrolyte>
The non-aqueous electrolyte is a solution in which a supporting electrolyte is dissolved in a non-aqueous solvent. As the supporting electrolyte, a known supporting electrolyte such as an ammonium salt or a phosphonium salt can be used. Examples of ammonium salts include tetrabutylammonium tetrafluoroborate ((C ₄ H ₉ ) ₄ NBF ₄ ), 4-ethylammonium tetrafluoroborate ((C ₂ H ₅ ) ₄ NBF ₄ ), tetrafluoroborate 3 Ethylmethylammonium ((C ₂ H ₅ ) ₃ CH ₃ NBF ₄ ), tetrafluoroboric acid-1,1′-spirobipyrrolidinium ((C ₄ H ₈ ) ₂ NBF ₄ ), hexafluorophosphoric acid 4 Examples include butylammonium ((C ₄ H ₉ ) ₄ NPF ₆ ), 4-ethylammonium hexafluorophosphate ((C ₂ H ₅ ) ₄ NPF ₆ ), and the like. Examples of phosphonium salts include 4-butylphosphonium tetrafluoroborate ((C ₄ H ₉ ) ₄ PBF ₄ ), 4-ethylphosphonium tetrafluoroborate ((C ₂ H ₅ ) ₄ PBF ₄ ), and hexafluorophosphoric acid. Examples thereof include 4-butylphosphonium ((C ₄ H ₉ ) ₄ PPF ₆ ) and 4-ethylphosphonium hexafluorophosphate ((C ₂ H ₅ ) ₄ PPF ₆ ). The concentration of the supporting electrolyte is, for example, 1.0 mol or more and 2.5 mol or less with respect to 1 liter of the nonaqueous electrolytic solution.

On the other hand, the non-aqueous solvent contains at least an N-oxide compound. As an example of the N-oxide compound, an N-oxide compound of the formula (1) is contained, and R _{1 to} R ₃ in the formula (1) are monovalent saturated hydrocarbons having 2 to 6 carbon atoms, respectively. Or a monovalent heteroatom-containing saturated hydrocarbon group.

式（１）のＮ−オキシド化合物の具体例は図４に示した通りであり、同図４の例１〜例５は、Ｒ₁〜Ｒ₃のそれぞれが炭素数２〜６の一価の飽和炭化水素基である例を示し、例６〜例８は、Ｒ₁〜Ｒ₃のそれぞれが炭素数２〜６の一価のヘテロ原子含有飽和炭化水素基である例を示す。

Specific examples of the N-oxide compound of the formula (1) are as shown in FIG. 4, and Examples 1 to 5 in FIG. 4 are monovalent monovalent C 2-6 in R _{1 to} R ₃ . The example which is a saturated hydrocarbon group is shown, and Examples 6 to 8 show examples in which each of R _{1 to} R ₃ is a monovalent heteroatom-containing saturated hydrocarbon group having 2 to 6 carbon atoms.

Further, as another example of the N-oxide compound, the N-oxide compound of the formula (2) is contained, and R ₄ in the formula (2) is a monovalent saturated hydrocarbon having 3 to 6 carbon atoms. Or a monovalent heteroatom-containing saturated hydrocarbon group, and X is a divalent saturated hydrocarbon group that forms a 5- or 6-membered heterocyclic ring together with a nitrogen atom.

式（２）のＮ−オキシド化合物の具体例は図５に示した通りであり、同図５の例９〜例１２及び例１４〜例１７は、Ｒ₄が炭素数が３〜６の一価の飽和炭化水素基で、Ｘが二価の飽和炭化水素基で、結合している窒素原子と共に環員数５又は６のヘテロ環を形成している例を示し、例１３及び例１８は、Ｒ₄が炭素数が３〜６の一価のヘテロ原子含有飽和炭化水素基で、Ｘが二価の飽和炭化水素基で、結合している窒素原子と共に環員数５又は６のヘテロ環を形成している例を示す。

Specific examples of the N- oxide compound of formula (2) is as shown in FIG. 5, Examples 9 to 12 and Examples 14 to Example 17 of FIG. 5 shows one R ₄ is a 3-6 carbon atoms A valent saturated hydrocarbon group, wherein X is a divalent saturated hydrocarbon group and forms a heterocyclic ring having 5 or 6 ring members together with the nitrogen atom bonded thereto, Examples 13 and 18 are R ₄ is a monovalent heteroatom-containing saturated hydrocarbon group having 3 to 6 carbon atoms, X is a divalent saturated hydrocarbon group, and forms a heterocycle having 5 or 6 ring members together with the nitrogen atom to which R ₄ is bonded. An example is shown.

Further, as another example of the N-oxide compound, the N-oxide compound of the formula (3) is contained, and R ₅ in the formula (3) is a monovalent saturated hydrocarbon having 1 to 6 carbon atoms. R ₆ and R ₇ are each a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms.

式（３）のＮ−オキシド化合物の具体例は図６に示した通りであり、同図６の例１９〜例２２は、Ｒ₅が炭素数が１〜６の一価の飽和炭化水素基で、Ｒ₆、Ｒ₇がそれぞれ炭素数が３〜６の一価の飽和炭化水素基である例を示す。

Specific examples of the N-oxide compound of the formula (3) are as shown in FIG. 6. Examples 19 to 22 of FIG. 6 are monovalent saturated hydrocarbon groups in which R ₅ has 1 to 6 carbon atoms. In the examples, R ₆ and R ₇ are each a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms.

Furthermore, as another example of the N-oxide compound, the N-oxide compound of the formula (4) is contained, and R ₈ in the formula (4) is a monovalent saturated hydrocarbon having 3 to 6 carbon atoms. Or a monovalent heteroatom-containing saturated hydrocarbon group.

式（４）のＮ−オキシド化合物の具体例は図７に示した通りであり、同図７の例２３〜例２６は、Ｒ₈が炭素数が３〜６の一価の飽和炭化水素基である例を示し、例２７はＲ₈が炭素数が３〜６の一価のヘテロ原子含有飽和炭化水素基である例を示す。

Specific examples of the N-oxide compound of the formula (4) are as shown in FIG. 7. Examples 23 to 26 in FIG. 7 are monovalent saturated hydrocarbon groups in which R ₈ has 3 to 6 carbon atoms. Example 27 shows an example where R ₈ is a monovalent heteroatom-containing saturated hydrocarbon group having 3 to 6 carbon atoms.

Furthermore, as another example of the N-oxide compound, the N-oxide compound of the formula (5) is contained, and R ₉ in the formula (5) is a monovalent saturated hydrocarbon having 3 to 6 carbon atoms. Or a monovalent heteroatom-containing saturated hydrocarbon group.

式（５）のＮ−オキシド化合物の具体例は図８に示した通りであり、同図８の例２８〜例３１は、Ｒ₉が炭素数が３〜６の一価の飽和炭化水素基である例を示し、例３２はＲ₉が炭素数が３〜６の一価のヘテロ原子含有飽和炭化水素基である例を示す。

Specific examples of the N-oxide compound of the formula (5) are as shown in FIG. 8, and Examples 28 to 31 of FIG. 8 are monovalent saturated hydrocarbon groups having ₉ to 6 carbon atoms in R _9. Example 32 shows an example where R ₉ is a monovalent heteroatom-containing saturated hydrocarbon group having 3 to 6 carbon atoms.

<Explanation of Experimental Examples 1 to 40 and Comparative Examples 1 to 6>
9 and 10 show Experimental Examples 1 to 40 and Comparative Examples 1 to 6 using an N-oxide compound alone as a nonaqueous solvent.

(Experimental example 1)
As the non-aqueous electrolyte, the non-aqueous solvent is the N-oxide compound of Example 1 and the supporting electrolyte is triethylmethylammonium tetrafluoroborate (TEMAF ₄ ), which is 1.2 liters per liter of the non-aqueous electrolyte. A non-aqueous electrolyte solution was prepared and sealed in an electric double layer capacitor in which the polarizable electrode layers 12 and 22 of the positive electrode 10 and the negative electrode 20 were made of PAS, and the evaluation described below was performed.

(Experimental example 2)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the nonaqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 2 as the nonaqueous electrolytic solution.

(Experimental example 3)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 3 was prepared.

(Experimental example 4)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was prepared by changing the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 4.

(Experimental example 5)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 5 was prepared.

(Experimental example 6)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte prepared by changing the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 6 was prepared.

(Experimental example 7)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 7 was prepared.

(Experimental example 8)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 8 was prepared.

(Experimental example 9)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the nonaqueous electrolytic solution prepared by changing the nonaqueous solvent in Experimental Example 1 to the N-oxide compound in Example 9 was prepared.

(Experimental example 10)
Evaluation as described below was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 10 was prepared.

(Experimental example 11)
Evaluation as described below was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 11 was prepared.

(Experimental example 12)
Evaluation as described below was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 12 was prepared.

(Experimental example 13)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte prepared by changing the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 13 was prepared.

(Experimental example 14)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 14 was prepared.

(Experimental example 15)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 15 was prepared.

(Experimental example 16)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the nonaqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 16 as the nonaqueous electrolytic solution.

(Experimental example 17)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 17.

(Experiment 18)
Evaluation as described below was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 18 was prepared.

(Experimental example 19)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte prepared by changing the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 19 was prepared.

(Experiment 20)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 20 was prepared.

(Experimental example 21)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 21.

(Experimental example 22)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 22 was prepared.

(Experimental example 23)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 23 was prepared.

(Experimental example 24)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 24.

(Experimental example 25)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 25.

(Experimental example 26)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 26 was prepared.

(Experiment 27)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 27.

(Experimental example 28)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 28.

(Experimental example 29)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 29.

(Experimental example 30)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte prepared by changing the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 30 was prepared.

(Experimental example 31)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 1 was changed to the N-oxide compound in Example 31 was prepared.

(Experimental example 32)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 1 to the N-oxide compound of Example 32.

(Experimental example 33)
The following evaluation was performed in the same manner as in Experimental Example 1 except that a non-aqueous electrolytic solution prepared by changing the supporting electrolyte of Experimental Example 1 to tetraethylammonium tetrafluoroborate (TEABF ₄ ) was prepared.

(Experimental example 34)
The nonaqueous electrolyte solution was prepared by changing the nonaqueous solvent of Experimental Example 1 to the N-oxide compound of Example 3 and changing the supporting electrolyte to tetraethylammonium tetrafluoroborate (TEABF ₄ ). The following evaluation was performed in the same manner as in Experimental Example 1.

(Experimental example 35)
As the non-aqueous electrolyte solution, except that the non-aqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 9 and the supporting electrolyte was changed to 4-ethylammonium tetrafluoroborate (TEABF ₄ ) The following evaluation was performed in the same manner as in Experimental Example 1.

(Experimental example 36)
As the nonaqueous electrolyte solution, except that the nonaqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 19 and the supporting electrolyte was changed to tetraethylammonium tetrafluoroborate (TEABF ₄ ), The following evaluation was performed in the same manner as in Experimental Example 1.

(Experimental example 37)
As described in Experimental Example 1, the following evaluation was made except that a non-aqueous electrolytic solution prepared by changing the supporting electrolyte of Experimental Example 1 to tetrafluoroboric acid-1,1′-spirobipyrrolidinium (SBPBF ₄ ) was prepared. Went.

(Experiment 38)
As the non-aqueous electrolyte, the non-aqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 3, and the supporting electrolyte was changed to tetrafluoroboric acid-1,1′-spirobipyrrolidinium (SBPBF ₄ ). The following evaluation was performed in the same manner as in Experimental Example 1 except that a modified one was prepared.

(Experimental example 39)
As the non-aqueous electrolyte, the non-aqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 9, and the supporting electrolyte was tetrafluoroboric acid-1,1′-spirobipyrrolidinium (SBPBF ₄ ). The following evaluation was performed in the same manner as in Experimental Example 1 except that a modified one was prepared.

(Experimental example 40)
As the non-aqueous electrolyte, the non-aqueous solvent of Experimental Example 1 was changed to the N-oxide compound of Example 19, and the supporting electrolyte was tetrafluoroboric acid-1,1′-spirobipyrrolidinium (SBPBF ₄ ). The following evaluation was performed in the same manner as in Experimental Example 1 except that a modified one was prepared.

(Comparative Example 1)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the nonaqueous electrolytic solution prepared by changing the nonaqueous solvent in Experimental Example 1 to propylene carbonate (PC) was prepared.

(Comparative Example 2)
The following evaluation was performed in the same manner as in Experimental Example 1 except that the nonaqueous electrolytic solution prepared by changing the nonaqueous solvent in Experimental Example 1 to sulfolane (SL) was prepared.

(Comparative Example 3)
As a non-aqueous electrolyte solution, except that the non-aqueous solvent of Experimental Example 1 was changed to propylene carbonate (PC) and the supporting electrolyte was changed to tetraethylammonium tetrafluoroborate (TEABF ₄ ) The evaluation described below was conducted in the same manner as in Example 1.

(Comparative Example 4)
Experimental examples except that the nonaqueous solvent of Experimental Example 1 was changed to sulfolane (SL) and the supporting electrolyte was changed to tetraethylammonium tetrafluoroborate (TEABF ₄ ) as the nonaqueous electrolytic solution. The evaluation described below was performed in the same manner as in 1.

(Comparative Example 5)
As the non-aqueous electrolyte, the non-aqueous solvent of Experimental Example 1 was changed to propylene carbonate (PC), and the supporting electrolyte was changed to tetrafluoroboric acid-1,1′-spirobipyrrolidinium (SBPBF ₄ ). The following evaluation was performed in the same manner as in Experimental Example 1 except that the sample was prepared.

(Comparative Example 6)
As the non-aqueous electrolyte, the non-aqueous solvent of Experimental Example 1 was changed to sulfolane (SL), and the supporting electrolyte was changed to tetrafluoroboric acid-1,1′-spirobipyrrolidinium (SBPBF ₄ ). The following evaluation was performed in the same manner as in Experimental Example 1 except that the sample was prepared.

<Description of evaluation method>
The “initial value / capacitance” and “initial value / impedance (1 kHz)” in FIGS. 9 and 10 enclose the non-aqueous electrolytes of Examples 1 to 40 and Comparative Examples 1 to 6. The values obtained by measuring the capacitance and impedance (measurement frequency: 1 kHz) with an LCR meter in the same atmosphere after leaving the electric double layer capacitors in an atmosphere at 25 ° C. for 12 hours are shown.

  Further, “after reliability test / capacitance change rate” and “after reliability test / impedance change rate” in FIGS. 9 and 10 are “initial value / capacitance” and “initial value / impedance (1 kHz). ) ”, A reliability test was performed in which a charging voltage of 3.3 V was continuously applied for 500 hours in an atmosphere at 70 ° C., and thereafter the capacitance and impedance (measurement frequency: 1 kHz) were measured by an LCR meter in an atmosphere at 25 ° C. ), And each measured value is divided by the values of “initial value / capacitance” and “initial value / impedance (1 kHz)”, and the value is expressed as a percentage.

  Further, “after reliability test / package thickness change rate” in FIG. 9 and FIG. 10 is the same as the thickness T2 (see FIG. 3) of the film package 40 after the reliability test. (See 1), and the percentage values are shown.

<Explanation of evaluation results>
As can be seen from FIG. 9 and FIG. 10, the nonaqueous electrolytic solution (Experimental Examples 1 to 40) using an N-oxide compound as the nonaqueous solvent used propylene carbonate (PC) as the nonaqueous solvent. There is a tendency that the capacitance change rate, the impedance change rate, and the package thickness change rate after the reliability test are remarkably smaller than the non-aqueous electrolyte solutions (Comparative Example 1, Comparative Example 3 and Comparative Example 5). The reason why such a result was obtained is not clear, but is presumed as follows.

  That is, when a charging voltage of 3.3 V is applied to the electric double layer capacitor, the potential of the positive electrode 10 increases to, for example, +4.65 V and the potential of the negative electrode decreases to, for example, +1.35 V. Since the oxidation potential of is higher than that of propylene carbonate (PC), there is little or no occurrence of oxidative decomposition of the non-aqueous solvent even when a charging voltage of 3.3 V is applied, thereby changing the capacitance after the reliability test It is considered that the rate, impedance change rate, and package thickness change rate were suppressed. Moreover, it is thought that the N-oxide compound has a low reduction potential and is electrochemically stable.

  Further, as can be seen from FIG. 9 and FIG. 10, the non-aqueous electrolyte solution using the N-oxide compound as the non-aqueous solvent (Experimental Examples 1 to 40) uses sulfolane (SL) as the non-aqueous solvent. The initial impedance and the impedance change rate after the reliability test tend to be smaller than the non-aqueous electrolyte solutions (Comparative Example 2, Comparative Example 4 and Comparative Example 6). The reason why such a result was obtained is not clear, but is presumed as follows.

  That is, the N-oxide compound which is a non-aqueous solvent is a highly polar compound in which nitrogen atoms are positively charged and oxygen atoms are negatively charged, and the electroconductivity of the non-aqueous electrolyte is high because the solubility of the supporting electrolyte is high. It is considered that the initial impedance and the impedance change rate after the reliability test were suppressed.

  As described above, the non-aqueous electrolyte using the N-oxide compound alone as the non-aqueous solvent is useful for increasing the charging voltage and improving the energy density as compared with the conventional non-aqueous electrolyte. I understand.

<Explanation of Experimental Example 41 to Experimental Example 44, Comparative Example 7 and Comparative Example 8>
FIG. 11 shows Experimental Examples 41 to 44 and Comparative Examples 7 and 8 using a mixed solvent of an N-oxide compound and a known nonaqueous solvent as the nonaqueous solvent.

(Experimental example 41)
As the non-aqueous electrolyte, the non-aqueous solvent was a mixed solvent of 90% by weight of the N-oxide compound of Example 23 and 10% by weight of dimethyl sulfone (DMS), and 3 ethylmethylammonium tetrafluoroborate (TEMABF) as the supporting electrolyte. ₄ ) prepared by dissolving 1.2 mol of 1 liter of non-aqueous electrolyte solution, and preparing the non-aqueous electrolyte solution as an electric double layer in which the polarizable electrode layers 12 and 22 of the positive electrode 10 and the negative electrode 20 are made of PAS. The evaluation was performed after sealing in a capacitor.

(Experimental example 42)
As the non-aqueous electrolyte, the non-aqueous solvent is a mixed solvent of 80% by weight of the N-oxide compound of Example 23 and 20% by weight of ethyl methyl sulfone (EMS), and the supporting electrolyte is 3 ethyl methyl ammonium tetrafluoroborate ( A solution prepared by dissolving 1.2 mol of TEMABF ₄ ) with respect to 1 liter of a non-aqueous electrolyte solution is prepared, and the non-aqueous electrolyte solution is an electric two-phase electrode layer 12, 22 of the positive electrode 10 and the negative electrode 20. The evaluation was conducted after enclosing in a multilayer capacitor.

(Experimental example 43)
As the non-aqueous electrolyte, the non-aqueous solvent is a mixed solvent of 80% by weight of the N-oxide compound of Example 23 and 20% by weight of ethyl isopropyl sulfone (EIPS), and the supporting electrolyte is 3-ethylmethylammonium tetrafluoroborate ( A solution prepared by dissolving 1.2 mol of TEMABF ₄ ) with respect to 1 liter of a non-aqueous electrolyte solution is prepared, and the non-aqueous electrolyte solution is an electric two-phase electrode layer 12, 22 of the positive electrode 10 and the negative electrode 20. The evaluation was conducted after enclosing in a multilayer capacitor.

(Experimental example 44)
As the non-aqueous electrolyte, the non-aqueous solvent is a mixed solvent of 80% by weight of the N-oxide compound of Example 23 and 20% by weight of sulfolane (SL), and the supporting electrolyte is 3-ethylmethylammonium tetrafluoroborate (TEMAF _4). ) Is dissolved in 1.2 mol per liter of non-aqueous electrolyte, and the non-aqueous electrolyte is used as an electric double layer capacitor in which the polarizable electrode layers 12 and 22 of the positive electrode 10 and the negative electrode 20 are made of PAS. The following evaluation was performed.

(Comparative Example 7)
The following evaluation was performed in the same manner as in Experimental Example 41, except that the non-aqueous electrolyte was prepared by using only ethyl isopropyl sulfone (EIPS) as the non-aqueous solvent of Experimental Example 41.

(Comparative Example 8)
The following evaluation was performed in the same manner as in Experimental Example 41 except that the non-aqueous electrolyte was prepared by using only sulfolane (SL) as the non-aqueous solvent of Experimental Example 41.

<Description of evaluation method>
“Initial value / capacitance” and “initial value / impedance (1 kHz)” in FIG. 11 are the electric double layer capacitors enclosing the non-aqueous electrolytes of Examples 41 to 44 and Comparative Examples 7 and 8, respectively. Is a value obtained by measuring the capacitance and impedance (measurement frequency: 1 kHz) with an LCR meter in the atmosphere after standing for 12 hours in a 25 ° C. atmosphere.

  Further, “after reliability test / capacitance change rate” and “after reliability test / impedance change rate” in FIG. 11 are “initial value / capacitance” and “initial value / impedance (1 kHz)”. After the measurement, a reliability test is performed in which a charging voltage of 3.3 V is continuously applied for 500 hours in an atmosphere at 70 ° C., and then the capacitance and impedance (measurement frequency: 1 kHz) are measured with an LCR meter in an atmosphere at 25 ° C. Each measured value is divided by the values of “initial value / capacitance” and “initial value / impedance (1 kHz)”, and the value is expressed as a percentage.

  Further, “after reliability test / package thickness change rate” in FIG. 11 is the same as the thickness T2 (see FIG. 3) of the film package 40 after the reliability test (see FIG. 1). ), And the percentage value is shown.

<Explanation of evaluation results>
As can be seen from FIG. 11, the non-aqueous electrolyte solution (Experimental Examples 41 to 44) using a mixed solvent of an N-oxide compound and a known non-aqueous solvent as the non-aqueous solvent is sulfolane as the non-aqueous solvent. The initial impedance tends to be smaller than that of the non-aqueous electrolyte using (SL) (Comparative Example 8). The reason why such a result was obtained is not clear, but is presumed as follows.

  That is, the N-oxide compound contained in the nonaqueous solvent is a highly polar compound in which the nitrogen atom is positively charged and the oxygen atom is negatively charged, and the solubility of the supporting electrolyte is high. It is considered that the electrical conductivity is high and the initial impedance is thereby suppressed. Moreover, it is thought that the viscosity of the non-aqueous electrolyte is lowered due to the presence of the N-oxide compound, which also affects the result.

  In this way, the non-aqueous electrolyte using a mixed solvent of an N-oxide compound and a known non-aqueous solvent as the non-aqueous solvent increases the charging voltage and improves the energy density compared to the conventional non-aqueous electrolyte. It will be understood that it is useful for

<Application to lithium ion capacitors>
Hereinafter, a specific example in which the present invention is applied to a non-aqueous electrolyte for a lithium ion capacitor will be described with reference to FIGS. 12 and 13.

<Structure of lithium ion capacitor>
As shown in FIG. 12, the lithium ion capacitor is similar to the electric double layer capacitor in that the storage element B having the positive electrode 10, the negative electrode 20, and the separator 30, the non-aqueous electrolyte, the film package 40, and the pair Terminal 50. The potential difference between the positive electrode 10 and the negative electrode 20 before charging of the lithium ion capacitor is about 3V.

Where this lithium ion capacitor differs from the electric double layer capacitor,
-Negative electrode 20 is formed by forming active material layer 23 instead of polarizable electrode layer 22 on the surface of current collector 21 made of, for example, copper metal foil-Film of storage element B and non-aqueous electrolyte solution The lithium metal sheet (not shown) is arranged in the vicinity of the negative electrode 20 when encapsulating in the package 40. The nonaqueous electrolytic solution is impregnated in the polarizable electrode layer 12, the active material layer 23, and the separator 30.

  The active material layer 23 includes, for example, non-graphitizable carbon, graphite, tin oxide, silicon oxide, and other main materials, conductive assistants such as carbon black and metal powder, polytetrafluoroethylene (PTFE), and polyfluoride. Binders such as vinylidene chloride (PVDF) and styrene butadiene rubber (SBR) are included as necessary. Of course, the material of the active material layer 23 is not limited to the above, and a known material can be used as appropriate.

  The lithium of the lithium metal sheet is dissolved in the non-aqueous electrolyte, and the lithium ions are pre-doped in the active material layer 23 of the negative electrode 20, whereby the potential of the negative electrode 20 is, for example, compared with the potential of the positive electrode 10 in a state before charging. It will be about 3V lower.

<Composition of non-aqueous electrolyte>
The non-aqueous electrolyte is a solution in which a supporting electrolyte is dissolved in a non-aqueous solvent. As the supporting electrolyte, a known supporting electrolyte, that is, a supporting electrolyte capable of providing Li ⁺ as a cation and supplying PF ₆ ⁺ , BF ₄ ^- or the like as an anion can be used. Moreover, the well-known ionic liquid which can provide a lithium ion as a cation can also be used. The concentration of the supporting electrolyte is, for example, 1.0 mol or more and 2.0 mol or less with respect to 1 liter of the nonaqueous electrolytic solution.

  On the other hand, the non-aqueous solvent contains at least one of N-oxide compounds. Since the N-oxide compound is as described above, the description thereof is omitted here.

<Explanation of Experimental Example 45 to Experimental Example 53 and Comparative Example 9 to Comparative Example 10>
FIG. 13 shows Experimental Examples 45 to 53 and Comparative Examples 9 and 10 using an N-oxide compound alone as a nonaqueous solvent.

(Experimental example 45)
As the non-aqueous electrolyte solution, a non-aqueous solvent is prepared by dissolving the N-oxide compound of Example 1 and 1.2 mol of LiPF ₆ as the supporting electrolyte in 1 liter of the non-aqueous electrolyte solution. The aqueous electrolyte was encapsulated in a lithium ion capacitor in which the polarizable electrode layer 12 of the positive electrode 10 was made of PAS and the active material layer 23 of the negative electrode 20 was made of non-graphitizable carbon, and the following evaluation was performed.

(Experimental example 46)
The following evaluation was performed in the same manner as in Experimental Example 45, except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 45 to the N-oxide compound of Example 2.

(Experimental example 47)
The following evaluation was performed in the same manner as in Experimental Example 45 except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 45 was changed to the N-oxide compound in Example 3 was prepared.

(Experimental example 48)
The following evaluation was performed in the same manner as in Experimental Example 45, except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 45 was changed to the N-oxide compound in Example 6 was prepared.

(Experimental example 49)
The following evaluation was performed in the same manner as in Experimental Example 45, except that a non-aqueous electrolyte was prepared by changing the non-aqueous solvent of Experimental Example 45 to the N-oxide compound of Example 9.

(Experimental example 50)
The following evaluation was performed in the same manner as in Experimental Example 45 except that a non-aqueous electrolyte was prepared by changing the non-aqueous solvent of Experimental Example 45 to the N-oxide compound of Example 14.

(Experimental example 51)
The following evaluation was performed in the same manner as in Experimental Example 45, except that a non-aqueous electrolyte was prepared by changing the non-aqueous solvent of Experimental Example 45 to the N-oxide compound of Example 19.

(Experimental example 52)
The following evaluation was performed in the same manner as in Experimental Example 45, except that the non-aqueous electrolyte was changed from the non-aqueous solvent of Experimental Example 45 to the N-oxide compound of Example 23.

(Experimental example 53)
The following evaluation was performed in the same manner as in Experimental Example 45, except that a non-aqueous electrolyte was prepared by changing the non-aqueous solvent of Experimental Example 45 to the N-oxide compound of Example 28.

(Comparative Example 9)
The following evaluation was performed in the same manner as in Experimental Example 45, except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 45 was changed to propylene carbonate (PC) was prepared.

(Comparative Example 10)
The following evaluation was performed in the same manner as in Experimental Example 45, except that a nonaqueous electrolytic solution in which the nonaqueous solvent in Experimental Example 45 was changed to sulfolane (SL) was prepared.

<Description of evaluation method>
“Initial value / capacitance” and “initial value / internal resistance” in FIG. 13 represent the lithium ion capacitors enclosing the non-aqueous electrolytes of Examples 45 to 53, Comparative Example 9 and Comparative Example 10, respectively. The values obtained by measuring the capacitance and the internal resistance with an LCR meter in the same atmosphere after standing for 12 hours in a 25 ° C. atmosphere are shown.

  In addition, “After Reliability Test / Capacitance Change Rate” and “After Reliability Test / Internal Resistance Change Rate” in FIG. 13 measure “Initial Value / Capacitance” and “Initial Value / Internal Resistance”. After that, a reliability test was performed in which a charging voltage of 4.5 V was continuously applied for 500 hours in an atmosphere of 60 ° C., and thereafter the capacitance and internal resistance were measured with an LCR meter in an atmosphere of 25 ° C. Are divided by the values of “initial value / capacitance” and “initial value / internal resistance”, respectively, and are expressed as percentages.

  Further, “after reliability test / package thickness change rate” in FIG. 13 is the same as the thickness T2 (see FIG. 3) of the film package 40 after the reliability test (see FIG. 1). ), And the percentage value is shown.

<Explanation of evaluation results>
As can be seen from FIG. 13, the nonaqueous electrolytic solution using the N-oxide compound as the nonaqueous solvent (Experimental Example 45 to Experimental Example 53) is nonaqueous electrolytic using propylene carbonate (PC) as the nonaqueous solvent. The capacitance change rate, resistance change rate, and package thickness change rate after the reliability test tend to be much smaller than the liquid (Comparative Example 9). The reason (guess) for obtaining such a result is as described above.

  Further, as can be seen from FIG. 13, the non-aqueous electrolyte solution using N-oxide compound as the non-aqueous solvent (Experimental Example 45 to Experimental Example 53) is non-aqueous system using sulfolane (SL) as the non-aqueous solvent. The initial internal resistance and the rate of change of internal resistance after the reliability test tend to be smaller than the electrolytic solution (Comparative Example 10). The reason (guess) for obtaining such a result is as described above.

  As described above, the non-aqueous electrolyte using the N-oxide compound alone as the non-aqueous solvent is useful for increasing the charging voltage and improving the energy density as compared with the conventional non-aqueous electrolyte. I understand.

<Application to other electrochemical devices>
(1) The N-oxide compound can also be used as a non-aqueous solvent for a non-aqueous electrolyte solution of a lithium ion secondary battery. That is, as nonaqueous solvents for nonaqueous electrolytes, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate (DEC) , Chain carbonates such as methylpropyl carbonate and methylisopropyl carbonate, cyclic esters such as γ-butyrolactone (γBL), γ-valerolactone (γVL), 3-methyl-γ-butyrolactone, 2-methyl-γ-butyrolactone, Chain esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate, methyl valerate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, 2-methylteto Cyclic ethers such as hydrofuran, 3-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, chain ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, and dipropyl ether; Nitriles such as acetonitrile (AN), propanenitrile (PN), glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, and sulfur-containing compounds such as sulfolane (SL), ethylmethylsulfone (EMS), dimethylsulfoxide, etc. In a conventional lithium ion secondary battery using one or a plurality of mixed solvents of the compounds, the N-oxide compound is mixed with the non-aqueous solvent, or the N-oxide is used as the non-aqueous solvent. Even if the oxide compound is used alone, the charging power of the lithium ion secondary battery It is possible to improve the energy density enhanced.

  (2) The N-oxide compound can also be used as a non-aqueous solvent for a non-aqueous electrolyte solution of a redox capacitor. That is, as nonaqueous solvents for nonaqueous electrolytes, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate (DEC) , Chain carbonates such as methylpropyl carbonate and methylisopropyl carbonate, cyclic esters such as γ-butyrolactone (γBL), γ-valerolactone (γVL), 3-methyl-γ-butyrolactone, 2-methyl-γ-butyrolactone, Chain esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate, methyl valerate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, 2-methylteto Cyclic ethers such as hydrofuran, 3-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, chain ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, and dipropyl ether; Nitriles such as acetonitrile (AN), propanenitrile (PN), glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, and sulfur-containing compounds such as sulfolane (SL), ethylmethylsulfone (EMS), dimethylsulfoxide, etc. In a conventional redox capacitor using one or a plurality of mixed solvents of the compounds, the non-aqueous solvent is mixed with the N-oxide compound, or the N-oxide compound is used as the non-aqueous solvent. Even if used alone, the charging voltage of the redox capacitor It can be improved Umate energy density.

  The present invention is not limited to electric double layer capacitors, lithium ion capacitors, lithium ion secondary batteries, and redox capacitors, but can be widely used for various electrochemical devices using non-aqueous electrolytes, and the same effects as described above can be obtained. it can.

  DESCRIPTION OF SYMBOLS 10 ... Positive electrode, 11 ... Current collector, 12 ... Polarizable electrode layer, 20 ... Negative electrode, 21 ... Current collector, 22 ... Polarizable electrode layer, 23 ... Active material layer, 30 ... Separator, 40 ... Film package, 50 ... terminal, B ... electric storage element.

Claims (8)

  A nonaqueous solvent for an electrochemical device containing an N-oxide compound. The non-aqueous solvent for an electrochemical device according to claim 1,
The N-oxide compound is represented by the following formula (1), and R _{1 to} R ₃ in the formula (1) are each a monovalent saturated hydrocarbon group having a carbon number of 2 to 6 or a monovalent group. A nonaqueous solvent for electrochemical devices, which is a heteroatom-containing saturated hydrocarbon group.

The non-aqueous solvent for an electrochemical device according to claim 1,
The N-oxide compound is represented by the following formula (2), and R ₄ in the formula (2) is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms or a monovalent heteroatom-containing saturated. A nonaqueous solvent for an electrochemical device, which is a hydrocarbon group, and X is a divalent saturated hydrocarbon group and forms a heterocycle having 5 or 6 ring members together with a nitrogen atom.

The non-aqueous solvent for an electrochemical device according to claim 1,
The N-oxide compound is represented by the following formula (3), and R ₅ in the formula (3) is a monovalent saturated hydrocarbon group having 1 to 6 carbon atoms, and R ₆ and R ₇ are A nonaqueous solvent for electrochemical devices, each of which is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms.

The non-aqueous solvent for an electrochemical device according to claim 1,
The N-oxide compound is represented by the following formula (4), and R ₈ in the formula (4) is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms or a monovalent heteroatom-containing saturated. A non-aqueous solvent for electrochemical devices, which is a hydrocarbon group.

The non-aqueous solvent for an electrochemical device according to claim 1,
The N-oxide compound is represented by the following formula (5), and R ₉ in the formula (5) is a monovalent saturated hydrocarbon group having 3 to 6 carbon atoms or monovalent heteroatom-containing saturation. A non-aqueous solvent for electrochemical devices, which is a hydrocarbon group.

  The nonaqueous electrolyte solution for electrochemical devices containing the nonaqueous solvent of any one of Claims 1-6, and a supporting electrolyte.   An electrochemical device comprising an electrode and the nonaqueous electrolytic solution according to claim 7.

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