JPWO2005042466A1 - Quaternary ammonium salts, electrolytes, electrolytes and electrochemical devices - Google Patents

Abstract

The quaternary ammonium salt of the present invention has the general formula [Chemical Formula 1] [wherein R 1 and R 2 are the same or different and represent a C 1-4 alkyl group. R1 and R2 may be bonded together with a nitrogen atom to which they are bonded to form a saturated heterocyclic ring. R3 and R4 are the same or different and each represents a methyl group or an ethyl group. X- represents an anion. ]. The quaternary ammonium salt of the present invention has a melting point of 10 ° C. or lower, is excellent in solubility in a non-aqueous organic solvent, has a remarkably high electrical conductivity, and can be suitably used as an electrolyte.

Description

  The present invention relates to a quaternary ammonium salt, an electrolyte, an electrolytic solution, and an electrochemical device.

  In recent years, salts having a melting point below room temperature (room temperature molten salts) have been developed. As such a room temperature molten salt, for example, a general formula

[Wherein, R ^1A , R ^2A , R ^3A and R ^4A are the same or different, and are an alkyl group having 1 to 5 carbon atoms or R′—O— (CH ₂ ) _n — (R ′ is a methyl group or an ethyl group). Group, n represents an integer of 1 to 4). Any two groups of R ^1A , R ^2A , R ^3A and R ^4A may form a ring. However, at least one of R ^{1A to} R ^4A is the alkoxyalkyl group. W represents a nitrogen atom or a phosphorus atom, and Y represents a monovalent anion. ]
The aliphatic ammonium salt represented by these is known (patent document 1).

  The aliphatic ammonium salt disclosed in Patent Document 1 is excellent in solubility in a non-aqueous organic solvent and has a property that salt precipitation hardly occurs at low temperatures.

However, although the electric conductivity of a solution obtained by dissolving the aliphatic ammonium salt in a non-aqueous organic solvent can be satisfied to some extent, the electric conductivity of the aliphatic ammonium salt itself is low and has not reached a satisfactory level. In addition, the aliphatic ammonium salt is poor in fluidity due to its high viscosity, and therefore is not suitable for an electrolytic solution of an electric device using a porous electrode that requires permeability.
WO 02/076924 A1

  An object of the present invention is to provide a quaternary ammonium salt having a melting point of 10 ° C. or lower, high electrical conductivity, and excellent solubility in a non-aqueous organic solvent.

  The inventors of the present invention have made extensive studies to develop a quaternary ammonium salt that can solve the above-mentioned problems. As a result, the specific quaternary ammonium salt represented by the following general formula (1), which has no specific description or suggestion in Patent Document 1, has a low melting point of 10 ° C. or lower, and is a non-aqueous organic solvent. It has been found that it has excellent solubility and has a remarkably high electrical conductivity and can be suitably used as an electrolyte. The present invention has been completed based on such findings.

The present invention provides the following quaternary ammonium salt, electrolyte, electrolytic solution, and electrochemical device.
1. General formula

[Wherein, R ¹ and R ² are the same or different and each represents a C _1-4 alkyl group. R ¹ and R ² may be bonded together with the nitrogen atom to which they are bonded to form a saturated heterocyclic ring. R ³ and R ⁴ are the same or different and each represents a methyl group or an ethyl group. X ⁻ represents an anion. ]
A quaternary ammonium salt represented by
2. The quaternary ammonium salt according to 1 above, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a 3- to 5-membered saturated heterocyclic ring.
3. The quaternary ammonium salt according to 2 above, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a pyrrolidine ring.
4). The quaternary ammonium salt according to 1 above, wherein R ¹ and R ² are both methyl groups.
5). Wherein X _{^{-, BF 4 -, AlCl 4 -}} , Al 2 Cl 7 -, PF 6 -, AsF 6 -, N (CF 3 SO 2) 2 -, N (CF 3CF2 SO 2) 2 -, C (CF 3 _{^{SO 2) 3 -, N (}} CF 3 SO 2) (CF 3 CO) -, CF 3 SO 3 -, CH 3 SO 3 -, CH 3 CO 2 -, CF 3 COO -, NO 3 -, C 6 H _The quaternary ammonium salt according to any one of 1 to 4 above, which is ₅ COO ⁻ or C ₆ H ₅ SO ₃ ⁻ , CF3BF3 ⁻ , C2F5BF3 ⁻ or I ⁻ .
6). The quaternary ammonium salt according to 5 above, wherein X ⁻ is BF ₄ ^— or N (CF ₃ SO ₂ ) ₂ ^— .
7). General formula

[Wherein, R ¹ and R ² are the same or different and each represents a C _1-4 alkyl group. R ¹ and R ² may be bonded together with the nitrogen atom to which they are bonded to form a saturated heterocyclic ring. R ³ and R ⁴ are the same or different and each represents a methyl group or an ethyl group. X ⁻ represents an anion. ]
An electrolyte comprising a quaternary ammonium salt represented by:
8). 8. The electrolyte according to 7 above, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a quaternary ammonium salt which is a 3- to 5-membered saturated heterocyclic ring.
9. 9. The electrolyte according to 8 above, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a quaternary ammonium salt which is a pyrrolidine ring.
10. 8. The electrolyte as described in 7 above, which comprises a quaternary ammonium salt in which R ¹ and R ² are both methyl groups.
11. Wherein X _{^{-, BF 4 -, AlCl 4 -}} , Al 2 Cl 7 -, PF 6 -, AsF 6 -, N (CF 3 SO 2) 2 -, N (CF 3CF2 SO 2) 2 -, C (CF 3 _{^{SO 2) 3 -, N (}} CF 3 SO 2) (CF 3 CO) -, CF 3 SO 3 -, CH 3 SO 3 -, CH 3 CO 2 -, CF 3 COO -, NO 3 -, C 6 H ₅ COO ^{- _{also, C 6 H 5 SO 3 -}} , CF3BF3 -, C2F5BF3 - or I ^- a is electrolyte according to any one of the above 7-10 consisting of quaternary ammonium salts.
12 12. The electrolyte according to 11 above, comprising a quaternary ammonium salt in which X ⁻ is BF ₄ ^— or N (CF ₃ SO ₂ ) ₂ ^— .
13. The electrolyte solution containing the 1 type (s) or 2 or more types of the electrolyte in any one of said 7-12.
14 14. The electrolytic solution according to 13 above, comprising at least one of the electrolytes according to any one of 7 to 12 above and an organic solvent.
15. 15. The electrolytic solution according to 14 above, wherein the organic solvent is at least one selected from the group consisting of cyclic carbonates, chain carbonates, nitrile compounds, and sulfone compounds.
16. 16. The electrolytic solution according to 15 above, wherein the organic solvent is at least one selected from the group consisting of propylene carbonate, ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate.
17. 14. An electrochemical device comprising the electrolytic solution according to 13 above.
18. 18. The electrochemical device according to 17 above, wherein the electrochemical device is an electric double layer capacitor or a secondary battery.

Quaternary ammonium salt In this specification, examples of the C _1-4 alkyl group represented by R ¹ and R ² include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl. Groups and the like. A preferred C _1-4 alkyl group is a methyl group.

Examples of the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded include a 3- to 5-membered saturated heterocyclic ring. A preferred saturated heterocyclic ring is a pyrrolidine ring.

  Specific quaternary ammonium cations include bis (methoxymethyl) dimethylammonium cation, N, N- (dimethoxymethyl) -N-ethyl-N-methylammonium cation, N, N- (dimethoxymethyl) -N-propyl. -N-methylammonium cation, N, N- (dimethoxymethyl) -N-butyl-N-methylammonium cation, bis (methoxymethyl) diethylammonium cation, N- (ethoxymethyl) -N- (methoxymethyl) -N , N-dimethylammonium cation, N- (ethoxymethyl) -N- (methoxymethyl) -N-ethyl-N-methylammonium cation, bis (ethoxymethyl) dimethylammonium cation, N, N- (diethoxymethyl)- N-ethyl-N-methylammonium carbonate ON, bis (methoxymethyl) pyrrolidinium cation, bis (ethoxymethyl) pyrrolidinium cation, N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium cation, bis (methoxymethyl) aziridinium cation, Bis (ethoxymethyl) aziridinium cation, N- (ethoxymethyl) -N- (methoxymethyl) aziridinium cation, bis (methoxymethyl) azetidinium cation, bis (ethoxymethyl) azetidinium cation, N- (Ethoxymethyl) -N- (methoxymethyl) azetidinium cation and the like.

X ^- is the anion represented by, for _{^{example, BF 4 -, AlCl 4 -}} , Al 2 Cl 7 -, PF 6 -, AsF 6 -, N (CF 3 SO 2) 2 -, N (CF 3CF2 SO 2 _{^{) 2 -, C (CF 3}} SO 2) 3 -, N (CF 3 SO 2) (CF 3 CO) -, CF 3 SO 3 -, CH 3 SO 3 -, CH 3 CO 2 -, CF 3 COO - _{^{, NO 3 -, C 6 H}} 5 COO -, C 6 H 5 SO 3 -, CF3BF3 -, C2F5BF3 -, I - , and the like. Preferred anions are BF ₄ ^— and N (CF ₃ SO ₂ ) ₂ ^— .

  Preferred quaternary ammonium salts include, for example, bis (methoxymethyl) dimethylammonium tetrafluoroborate, N, N- (dimethoxymethyl) -N-ethyl-N-methylammonium tetrafluoroborate, N, N- (dimethoxymethyl) ) -N-propyl-N-methylammonium tetrafluoroborate, N, N- (dimethoxymethyl) -N-butyl-N-methylammonium tetrafluoroborate, bis (methoxymethyl) diethylammonium tetrafluoroborate, N- (ethoxy Methyl) -N- (methoxymethyl) -N, N-dimethylammonium tetrafluoroborate, N- (ethoxymethyl) -N- (methoxymethyl) -N-ethyl-N-methylammonium tetrafluoroborate, bis (ethoxymethyl) E) Dimethylammonium tetrafluoroborate, N, N- (diethoxymethyl) -N-ethyl-N-methylammonium tetrafluoroborate, bis (methoxymethyl) pyrrolidinium tetrafluoroborate, bis (ethoxymethyl) pyrrolidinium Tetrafluoroborate, N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate, bis (methoxymethyl) aziridinium tetrafluoroborate, N- (ethoxymethyl) -N- (methoxymethyl) azi Lizinium tetrafluoroborate, bis (methoxymethyl) azetidinium tetrafluoroborate, N- (ethoxymethyl) -N- (methoxymethyl) azetidinium tetrafluoroborate, bis (methoxymethyl) dimethylammo Umbistrifluoromethanesulfonylimide, N, N- (dimethoxymethyl) -N-ethyl-N-methylammonium bistrifluoromethanesulfonylimide, N, N- (dimethoxymethyl) -N-propyl-N-methylammonium bistrifluoromethane Sulfonylimide, N, N- (dimethoxymethyl) -N-butyl-N-methylammonium bistrifluoromethanesulfonylimide, bis (methoxymethyl) diethylammonium bistrifluoromethanesulfonylimide, N- (ethoxymethyl) -N- (methoxy Methyl) -N, N-dimethylammonium bistrifluoromethanesulfonylimide, N- (ethoxymethyl) -N- (methoxymethyl) -N-ethyl-N-methylammonium bistrifluoromethanesulfone Nilimide, bis (ethoxymethyl) dimethylammonium bistrifluoromethanesulfonylimide, N, N- (diethoxymethyl) -N-ethyl-N-methylammonium bistrifluoromethanesulfonylimide, bis (methoxymethyl) pyrrolidinium bistrifluoromethane Sulfonylimide, bis (ethoxymethyl) pyrrolidinium bistrifluoromethanesulfonylimide, N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium bistrifluoromethanesulfonylimide, bis (methoxymethyl) aziridinium bistrifluoromethane Sulfonylimide, N- (ethoxymethyl) -N- (methoxymethyl) aziridinium bistrifluoromethanesulfonylimide, bis (methoxymethyl) azetidinium bis Trifluoromethane sulfonyl imide, N- etc. (ethoxymethyl) -N- (methoxymethyl) azetidinium bis trifluoromethanesulfonyl imide.

  The quaternary ammonium salt of the present invention is produced by various methods. The typical method is demonstrated using the following reaction formula.

[Wherein, R ¹ , R ² , R ³ , R ⁴ and X ⁻ are the same as above. X ¹ represents a halogen atom. M represents a hydrogen atom or a metal atom. ]
By reacting the tertiary amine represented by the general formula (2) and the compound represented by the general formula (3), a quaternary ammonium salt represented by the general formula (4) is produced. A quaternary ammonium salt of the general formula (1) can be produced by a salt exchange reaction between the quaternary ammonium salt represented by the general formula (4) and the general formula (5).

  In General formula (5), M contains alkali metal atoms, such as H or Na, K, and Li, alkaline-earth metal atoms, such as Ca, Mg, and Ba, and metal atoms, such as Ag.

  The tertiary amine represented by the general formula (2) and the compound represented by the general formula (3) used as starting materials are both known substances.

  The tertiary amine of the general formula (2) is synthesized according to a known method. Such methods are described, for example, in CMMcLeod und GMRobinson, J. Chem. Soc., 119, 1470 (1921), GMRobinson und R. Robinson, J. Chem. Soc., 123, 532 (1923), Stewert , TD; Bradly, WEJAm. Chem. Soc., 1932, 54, 4172-4183, and the like.

  The tertiary amine represented by the general formula (2) is generally synthesized using a secondary amine, formaldehyde, alcohol and alkali carbonate as raw materials.

  These raw materials use 0.5 to 3 mol, preferably 0.6 to 1.5 mol of 10 to 38 wt% formaldehyde aqueous solution or paraformaldehyde, and 0.5 to 0.5 mol of alcohol with respect to 1 mol of secondary amine. -7 mol, preferably 2-5 mol, and alkali carbonate 0.2-3 mol, preferably 0.4-1 mol.

  The reaction temperature is suitably -5 to 25 ° C when an aqueous formaldehyde solution is used, and 60 to 100 ° C when paraformaldehyde is used. The reaction is generally completed in about several hours to 24 hours.

  The tertiary amine represented by the general formula (2) is easily isolated from the reaction mixture by a conventional isolation means such as extraction, rectification and the like.

  Examples of the compound represented by the general formula (3) include chloromethyl methyl ether, bromomethyl methyl ether, iodomethyl methyl ether, chloromethyl ethyl ether, bromomethyl ethyl ether, iodomethyl ethyl ether, and the like.

  The reaction of the tertiary amine represented by the general formula (2) and the compound represented by the general formula (3) is performed without a solvent or in a suitable solvent.

  As the solvent to be used, known solvents can be used as long as they can dissolve the tertiary amine represented by the general formula (2) and the compound represented by the general formula (3) and do not adversely affect the reaction. Can be widely used. Examples of such solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; methanol, ethanol, isopropanol, n-butanol, tert-butanol, and the like. Examples include lower alcohols; ketones such as acetone and methyl ethyl ketone; ethers such as diethyl ether and diisopropyl ether; aliphatic hydrocarbons such as n-hexane and n-heptane; and alicyclic hydrocarbons such as cyclohexane. Among these, aromatic hydrocarbons such as toluene, halogenated hydrocarbons such as dichloromethane, and ketones such as acetone are preferable. Such a solvent can be used individually by 1 type or in mixture of 2 or more types. These solvents are preferably anhydrous solvents.

  The compound represented by the general formula (3) is usually used in an amount of 0.3 to 5 mol, preferably 0.6 to 1.2 mol, per 1 mol of the tertiary amine (2). The reaction is usually performed at −10 to 25 ° C. and is generally completed in about several hours to 24 hours.

  The reaction of the quaternary ammonium salt represented by the general formula (4) obtained by the above reaction and the compound of the general formula (5) is performed by a normal salt exchange reaction.

The compound represented by the general formula (5) used as a raw material is a known compound, for example, CF ₃ SO ₃ H, CF ₃ SO ₃ Li, CF ₃ SO ₃ Na, CF ₃ SO ₃ K, HN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , NaN (CF ₃ SO ₂ ) ₂ , KN (CF ₃ SO ₂ ) ₂ , HN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO _{2) 2, NaN (CF 3} CF 2 SO 2) 2, KN (CF 3 CF 2 SO 2) 2, HC (CF 3 SO 2) 3, LiC (CF 3 SO 2) 3, NaC (CF 3 SO 2 ) ₃ , KC (CF ₃ SO ₂ ) ₃ , HN (CF ₃ SO ₂ ) (CF ₃ CO), LiN (CF ₃ SO ₂ ) (CF ₃ CO), NaN (CF ₃ SO ₂ ) (CF ₃ CO) , KN _(CF 3 SO _{) (CF 3 CO), HBF} 4, LiBF 4, NaBF 4, KBF 4, AgBF 4, HPF 6, LiPF 6, NaPF 6, KPF 6, AgPF 6, CF 3 CO 2 H, CF 3 CO 2 Li, CF ₃ CO ₂ Na, CF ₃ CO ₂ K, CH ₃ SO ₃ H, CH ₃ SO ₃ Li, CH ₃ SO ₃ Na, CH ₃ SO ₃ K and the like can be mentioned.

  This salt exchange reaction is carried out in a suitable solvent. As a solvent to be used, as long as it is a solvent that can dissolve the quaternary ammonium salt represented by the general formula (4) and the compound represented by the general formula (5) and does not adversely influence the reaction, Things can be used widely. Examples of such solvents include water; halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; lower alcohols such as methanol, ethanol, isopropanol, n-butanol, and tert-butanol; ketones such as acetone and methyl ethyl ketone; Examples include esters such as ethyl acetate and butyl acetate; and aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide. Among these, lower alcohols such as methanol; halogenated hydrocarbons such as chloroform and water are preferable. These solvents can be used singly or in combination of two or more.

  The salt exchange can also be performed using an ion exchange resin. As the ion exchange resin, an anion exchange resin is usually used.

  The salt exchange can be achieved by exchanging the anion in the resin with the target anion in advance and passing a solution in which the general formula (4) is dissolved through the resin. The solvent used here can be widely used as long as it can dissolve the general formula (4) and does not adversely affect the salt exchange reaction. Such solvents are generally water, alcohols and the like.

  As a use ratio of the quaternary ammonium salt represented by the general formula (4) and the compound represented by the general formula (5), the latter is usually 0.5 to 5 mol, preferably 1 to 1 mol of the former. Is preferably 0.9 to 1.2 mol. Since the reaction usually proceeds rapidly, for example, the temperature of a solution in which both are dissolved in a solvent may be maintained near room temperature. In general, the salt exchange reaction is completed in about 10 minutes to 2 hours.

  The target compound obtained in each of the above reactions can be easily isolated and purified from the reaction mixture by conventional separation means, for example, conventional isolation and purification means such as concentration, washing, organic solvent extraction, chromatography, and recrystallization. Is done.

The reaction conditions in the case of producing the quaternary ammonium salt represented by the general formula (1) in which X represents BF ₄ from the quaternary ammonium salt represented by the general formula (4) are shown as follows. A quaternary ammonium salt represented by the formula (4) is dissolved in the lower alcohol, and a predetermined amount of boron fluoride such as borohydrofluoric acid or silver borofluoride is added to the solution. React for about 30 minutes. The target compound can be isolated by distilling off the hydrogen halide produced by the reaction, filtering off a halogen salt such as silver halide, concentrating the filtrate under reduced pressure, and drying. For distilling off the hydrogen halide, a known method such as distilling by N ₂ bubbling or distilling by reduced pressure can be applied.

Specific reaction conditions for producing a quaternary ammonium salt represented by the general formula (1) in which X represents N (SO ₂ CF ₃ ) ₂ from the quaternary ammonium salt represented by the general formula (4) Specifically, a quaternary ammonium represented by the general formula (4) is dissolved in water, and a predetermined amount of an alkali metal salt of bistrifluoromethanesulfonimide (a lithium salt of bistrifluoromethanesulfonimide, sodium) Salt, potassium salt, etc.) is added and reacted at 0-25 ° C. for 30 minutes. The target compound is extracted with an appropriate solvent (eg, dichloromethane, chloroform, ethyl acetate, etc.), and the extract is washed with water, concentrated under reduced pressure, and dried to isolate the target compound. .

Electrolyte and Electrolyte Solution The quaternary ammonium salt of the present invention is a room temperature molten salt that is liquid at room temperature, has excellent solubility in non-aqueous organic solvents, and has high electrical conductivity. Therefore, the quaternary ammonium salt of the present invention can be suitably used as an electrolyte.

  In the present invention, the electrolyte itself made of the quaternary ammonium salt of the present invention can be used as the electrolytic solution. Moreover, the electrolyte which consists of this invention quaternary ammonium salt can be mixed and used for a suitable solvent.

  Examples of the solvent include cyclic carbonates, chain carbonates, phosphate esters, cyclic ethers, chain ethers, lactone compounds, chain esters, nitrile compounds, amide compounds, and sulfone compounds. These solvents are used alone or in combination.

  Specific examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, and the like.

  Specific examples of the chain carbonate include dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

  Specific examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, ethyldimethyl phosphate, and diethylmethyl phosphate.

  Specific examples of the cyclic ether include tetrahydrofuran and 2-methyltetrahydrofuran.

  Specific examples of the chain ether include dimethoxyethane.

  Specific examples of the lactone compound include γ-butyrolactone.

  Specific examples of the chain ester include methyl propionate, methyl acetate, ethyl acetate, and methyl formate.

  Specific examples of the nitrile compound include acetonitrile.

  Specific examples of the amide compound include dimethylformamide.

  Specific examples of the sulfone compound include sulfolane and methyl sulfolane.

  When the electrolyte comprising the quaternary ammonium salt of the present invention is used by mixing with the above solvent, the electrolyte concentration is preferably 0.1M or more, more preferably 0.5M or more, and further preferably 1M or more. .

  Furthermore, the electrolyte of the present invention can be used by mixing with a known electrolyte.

  Examples of known electrolytes used by mixing with the electrolyte of the present invention include alkali metal salts, quaternary ammonium salts, quaternary phosphonium salts, and the like.

  Examples of the alkali metal salt include lithium salt, sodium salt, potassium salt and the like. More specifically, examples of the lithium salt include lithium hexafluorophosphate, lithium borofluoride, lithium perchlorate, lithium trifluoromethanesulfonate, lithium sulfonylimide, lithium sulfonylmethide, and the like. More specifically, examples of the sodium salt include sodium hexafluorophosphate, sodium borofluoride, sodium perchlorate, sodium trifluoromethanesulfonate, sodium sulfonylimide, sodium sulfonylmethide, and the like. Specific examples of the potassium salt include potassium hexafluorophosphate, potassium borofluoride, potassium perchlorate, potassium trifluorosulfonate, potassium sulfonylimide, potassium sulfonylmethide, and the like.

  Examples of the quaternary ammonium salt include a tetraalkylammonium salt, an imidazolium salt, a pyrazolium salt, a pyridinium salt, a triazolium salt, and a pyridazinium salt. More specifically, as tetraalkylammonium salts, tetraethylammonium tetrafluoroborate, tetramethylammonium tetrafluoroborate, tetrapropylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, triethylmethylammonium tetrafluoroborate, trimethylethylammonium Tetrafluoroborate, dimethyldiethylammonium tetrafluoroborate, trimethylpropylammonium tetrafluoroborate, trimethylbutylammonium tetrafluoroborate, dimethylethylpropylammonium tetrafluoroborate, methylethylpropylbutylammonium tetrafluoroborate, N, N-dimethylpyrrolidinium Tetra Fluoroborate, N-ethyl-N-methylpyrrolidinium tetrafluoroborate, N-methyl-N-propylpyrrolidinium tetrafluoroborate, N-ethyl-N-propylpyrrolidinium tetrafluoroborate, N, N-dimethylpi Peridinium tetrafluoroborate, N-methyl-N-ethylpiperidinium tetrafluoroborate, N-methyl-N-propylpiperidinium tetrafluoroborate, N-ethyl-N-propylpiperidinium tetrafluoroborate, N, N-dimethylmorpholinium tetrafluoroborate, N-methyl-N-ethylmorpholinium tetrafluoroborate, N-methyl-N-propylmorpholinium tetrafluoroborate, N-ethyl-N-propylmorpholinium tetrafluoroborate Borate, and the like. More specifically, as the imidazolium salt, 1,3-dimethylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1,3-diethylimidazolium tetrafluoroborate, 1,2 -Dimethyl-3-ethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium tetrafluoroborate and the like. More specific examples of the pyrazolium salt include 1,2-dimethylpyrazolium tetrafluoroborate, 1-methyl-2-ethylpyrazolium tetrafluoroborate, and 1-propyl-2-methylpyrazolium tetrafluoroborate. 1-methyl-2-butylpyrazolium tetrafluoroborate and the like. More specifically, examples of the pyridinium salt include N-methylpyridinium tetrafluoroborate, N-ethylpyridinium tetrafluoroborate, N-propylpyridinium tetrafluoroborate, N-butylpyridinium tetrafluoroborate and the like. More specifically, as the triazolium salt, 1-methyltriazolium tetrafluoroborate, 1-ethyltriazolium tetrafluoroborate, 1-propyltriazolium tetrafluoroborate, 1-butyltriazolium tetrafluoroborate Etc. More specific examples of the pyridazinium salt include 1-methylpyridazinium tetrafluoroborate, 1-ethylpyridazinium tetrafluoroborate, 1-propylpyridazinium tetrafluoroborate, and 1-butylpyridazidi. Examples thereof include nium tetrafluoroborate.

  As the quaternary phosphonium salt, for example, tetraethylphosphonium tetrafluoroborate, tetramethylphosphonium tetrafluoroborate, tetrapropylphosphonium tetrafluoroborate, tetrabutylphosphonium tetrafluoroborate, triethylmethylphosphonium tetrafluoroborate, trimethylethylphosphonium tetrafluoroborate Dimethyldiethylphosphonium tetrafluoroborate, trimethylpropylphosphonium tetrafluoroborate, trimethylbutylphosphonium tetrafluoroborate, dimethylethylpropylphosphonium tetrafluoroborate, methylethylpropylbutylphosphonium tetrafluoroborate and the like.

  In this invention, these well-known electrolytes are used individually by 1 type or in mixture of 2 or more types.

Electrochemical devices Examples of the electrochemical device include an electric double layer capacitor and a secondary battery. The electrolyte or electrolytic solution of the present invention can be used in the same manner as the electrolyte or electrolytic solution used in known electric double layer capacitors and secondary batteries.

  The quaternary ammonium salt of the present invention or a solution obtained by dissolving the salt in an organic solvent can be used as an electrolytic solution for electrochemical devices.

  When a solution in which a quaternary ammonium salt is dissolved in an organic solvent is used as an electrolytic solution for an electrochemical device, the electrolyte concentration is preferably 0.1 M or more, more preferably 0.5 M or more, and particularly preferably 1 M or more. . When the electrolyte concentration is less than 0.1M, the electrical conductivity is lowered, and the performance of the electrochemical device is deteriorated. The upper limit of the electrolyte concentration is a concentration that separates from an organic solvent for a quaternary ammonium salt that is liquid at room temperature, and is 100% when not separated from an organic solvent. For quaternary ammonium salts that are solid at room temperature, the upper limit is the concentration at which the salt is saturated in an organic solvent.

  An electrolytic solution for an electrochemical device can be prepared using the quaternary ammonium salt of the present invention. The electrolytic solution obtained in the present invention can be used for an electrochemical device capable of storing electric energy by physical action or chemical action, and can be suitably used for, for example, an electric double layer capacitor and a lithium battery.

  A method for preparing an electrolytic solution for an electric double layer capacitor using the quaternary ammonium salt of the present invention will be described below. When the quaternary ammonium salt of the present invention is a liquid, it can be used as an electrolyte, and the salt can be used by mixing with an appropriate organic solvent. In preparing the electrolytic solution for the electric double layer capacitor, moisture adversely affects the performance of the electric double layer capacitor. Therefore, in an environment where air is not mixed, for example, in an inert atmosphere glove box such as argon gas and nitrogen gas. It is preferable to prepare. The moisture in the work environment can be managed with a dew point meter. It is preferable to set the working environment so that the dew point is −60 ° C. or lower. When the dew point is −60 ° C. or higher, if the working time is long, the electrolytic solution absorbs moisture in the atmosphere, and thus the moisture in the electrolytic solution increases. Water in the electrolyte can be measured with a Karl Fischer meter.

  When using the solution which melt | dissolved the quaternary ammonium salt of this invention in the organic solvent as an electrolyte solution for electrochemical devices, as above-mentioned, from the viewpoint of the electrical conductivity of electrolyte solution, Preferably electrolyte concentration is 0.1 M or more. More preferably, it is 0.5M or more, and particularly preferably 1M or more. The upper limit of the electrolyte concentration is not limited as long as the electrolyte does not precipitate and separate.

  Here, as the organic solvent, the above-mentioned various solvents can be used, but the physical properties such as dielectric constant, viscosity, melting point and the like differ depending on the type of the solvent. It is preferable to determine the mixing ratio of these depending on the type of salt. For example, in the case of an electrolytic solution composed of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate and propylene carbonate, N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidi in the electrolytic solution The proportion of nitrotetrafluoroborate is preferably 10 to 80% by weight, more preferably 15 to 70% by weight, and still more preferably 20 to 60% by weight. In the case of an electrolytic solution composed of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate and dimethyl carbonate, N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetra in the electrolytic solution The proportion of fluoroborate is preferably 20 to 90% by weight, more preferably 30 to 80% by weight. In the case of an electrolytic solution composed of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate and ethyl methyl carbonate, N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium in the electrolytic solution The proportion of tetrafluoroborate is preferably 30 to 90% by weight, more preferably 40 to 80% by weight. It is also possible to use a mixture of two or more organic solvents. When using a mixed solvent of dimethyl carbonate and ethyl methyl carbonate (mixing ratio is 1: 1), N- (ethoxymethyl) in the electrolytic solution The proportion of -N- (methoxymethyl) pyrrolidinium tetrafluoroborate is preferably 30 to 80% by weight.

  The quaternary ammonium salt of this invention can also be used for the electrolyte solution for lithium batteries. As in the preparation of the electrolytic solution for the electric double layer capacitor, moisture adversely affects the lithium battery characteristics. Therefore, the working environment in which the preparation work is performed is preferably in a glove box in which the dew point is controlled.

  When the quaternary ammonium salt of the present invention is itself a liquid, an electrolytic solution can be obtained by dissolving a lithium salt in the quaternary ammonium salt. Moreover, an electrolytic solution can be obtained by mixing the quaternary ammonium salt of the present invention with an appropriate organic solvent and dissolving the lithium salt in this mixture.

  Various salts can be used as the lithium salt as described above. The type is not particularly limited as long as the lithium salt does not precipitate.

  The lithium salt concentration is usually from 0.1M to 2.0M, preferably from 0.15M to 1.5M, preferably from 0.2M to 1.2M, particularly preferably from 0.3M to 1. 0M or less. When the lithium salt concentration is less than 0.1M, when the charge / discharge rate is high, lithium ions are depleted in the vicinity of the electrode, and the charge / discharge characteristics tend to deteriorate. On the other hand, when the lithium ion concentration exceeds 2.0M, the viscosity of the electrolytic solution increases and the electric conductivity tends to decrease.

In the present invention, it is preferable that BF ₄ ⁻ is contained in any one of the anions forming the quaternary ammonium salt and the lithium salt of the present invention. Although the reason is not certain, it is thought that when tetrafluoroborate is included, a passive film is formed on the surface of aluminum used as the positive electrode current collector, and elution of aluminum can be suppressed. BF ₄ ^- content number of ions is preferably adjusted to be 0.5% or more of the total number of anions in the electrolytic solution, and more preferably prepared such that 0.8% or more. The upper limit concentration is such that the number of ions contained in BF ₄ ⁻ is 100% of the total number of anions in the electrolytic solution.

  The electrolytic solution can also be used after diluted in an organic solvent. Examples of the organic solvent that can be used include cyclic carbonates, chain carbonates, cyclic ethers, chain ethers, nitrile compounds, and sulfone compounds.

  Specific examples of the cyclic carbonate include ethylene carbonate and propylene carbonate. Specific examples of the chain carbonate include dimethyl carbonate and ethyl methyl carbonate. Specific examples of the cyclic ether include tetrahydrofuran, hexahydropyran and the like. Specific examples of the chain ether include 1,2-dimethoxyethane. Specific examples of the nitrile compound include acetonitrile. Specific examples of the sulfone compound include sulfolane.

  These organic solvents can be used in combination. Examples of combinations include ethylene carbonate and dimethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and propylene carbonate, ethylene carbonate and tetrahydrofuran.

  The electrolyte used in the present invention preferably contains a specific organic additive.

  Specific examples of the organic additive include ethylene carbonate, vinylene carbonate, butylene carbonate, ethylene trithiocarbonate, vinylene trithiocarbonate, and ethylene sulfide. Among these, ethylene carbonate and vinylene carbonate are preferable. These organic additives are used singly or in combination of two or more.

  By including the specific organic additive, a lithium ion selective permeable membrane known as SEI (Solid Electrolyte Interface) is formed on the surface of the negative electrode of the lithium battery, decomposition of ammonium cations forming a room temperature molten salt, and conversion to a negative electrode material. Insertion can be suppressed, and as a result, stable charge / discharge characteristics of the lithium battery can be provided.

  The organic additive contains a substance that also functions as a diluent.

  The content of these organic additives is such that the ratio of the organic additive to the total electrolyte weight is preferably 1% by weight or more and 40% by weight or less, more preferably 1% by weight or more and 30% by weight or less, and further preferably 1%. % By weight or more and 20% by weight or less, most preferably 1% by weight or more and 10% by weight or less. When the content of the organic additive is 1% by weight or less, a sufficient film is not formed on the negative electrode surface, and there is a tendency that decomposition of ammonium cations forming a room temperature molten salt and insertion into the negative electrode material cannot be suppressed. .

  An electric double layer capacitor can be suitably produced using the electrolytic solution of the present invention obtained above. As an example of the electric double layer capacitor, for example, the one shown in FIG. The shape of the electric double layer capacitor is not limited to the coin type as shown in FIG. 1, but is a laminated type in which electrodes are stacked and accommodated in a can body, a wound type in which winding is accommodated, Or what is called the lamination type | mold formed by packing in an aluminum laminate may be used. Hereinafter, the structure of a coin-type electric double layer capacitor will be described as an example.

  FIG. 1 is a cross-sectional view of a coin-type electric double layer capacitor. Electrodes 1 and 2 are disposed to face each other with separator 3 interposed between container bodies 4 and 5. The electrode includes a polarizable electrode portion made of a carbon material such as activated carbon and a current collector portion. The container bodies 4 and 5 do not have to be corroded by the electrolytic solution, and are made of, for example, stainless steel or aluminum. The container bodies 4 and 5 are electrically insulated by an insulating gasket 6, and at the same time, the inside of the metal can body is sealed so that moisture and air from the outside of the can body do not enter. The current collector and the container body 4 of the electrode 1, and the current collector of the electrode 2 and the metal spacer 7 are in contact with each other at an appropriate pressure due to the presence of the metal spring 8, and are kept in electrical contact. Yes. In order to increase electrical conductivity, the current collector may be bonded using a conductive paste such as carbon paste.

  The polarizable electrode material is preferably a material having a large specific surface area and high electrical conductivity, and needs to be electrochemically stable with respect to the electrolyte within the range of applied voltage to be used. Examples of such a material include a carbon material, a metal oxide material, and a conductive polymer material. In view of cost, the polarizable electrode material is preferably a carbon material.

  As the carbon material, an activated carbon material is preferable, and specifically, sawdust activated carbon, ashigara activated carbon, pitch coke activated carbon, phenol resin activated carbon, polyacrylonitrile activated carbon, cellulose activated carbon, and the like. It is not limited.

  Examples of the metal oxide material include, but are not limited to, ruthenium oxide, manganese oxide, and cobalt oxide.

  Examples of the conductive polymer material include, but are not limited to, polyaniline, polypyrrole film, polythiophene film, poly (3,4-ethylenedioxythiophene) film, and the like.

  The electrode is formed by pressing the polarizable electrode material together with a binder, or mixing the polarizable electrode material with an organic solvent such as pyrrolidone together with a binder to form a paste, such as an aluminum foil. It can be obtained by coating the electric body and then drying it.

  The separator preferably has high electronic insulation, excellent wettability of the electrolyte, and high ion permeability, and needs to be electrochemically stable within the applied voltage range. The material of the separator is not particularly limited, but papermaking made of rayon, Manila hemp or the like; polyolefin-based porous film; polyethylene nonwoven fabric; polypropylene nonwoven fabric or the like is preferably used.

  A lithium secondary battery can be suitably prepared using the electrolytic solution of the present invention obtained above. Examples of the shape of the lithium secondary battery of the present invention include a coin shape, a cylindrical shape, a square shape, and a laminate. However, the shape is not limited to these shapes. As an example of the lithium secondary battery of the present invention, for example, a coin-type cell shown in FIG. 2 can be cited.

  Hereinafter, the lithium secondary battery will be described with reference to FIG.

  In an internal space formed by the positive electrode can 14 and the negative electrode can 15, a stacked body in which the positive electrode 11, the separator 13, the negative electrode 12, and the spacer 17 are stacked in this order from the positive electrode can 14 side is accommodated. By interposing the spring 18 between the negative electrode can 15 and the spacer 17, the positive electrode 11 and the negative electrode 12 are appropriately pressed and fixed. The electrolytic solution is impregnated between the positive electrode 11, the separator 13, and the negative electrode 12. In a state where the gasket 16 is interposed between the positive electrode can 14 and the negative electrode can 15, the positive electrode can 14 and the negative electrode can 15 are crimped to bond them together, and the laminate is sealed.

Examples of the positive electrode active material include LiCoO ₂ , LiNiO ₂ , LiNi _1-x Co _x O ₂ , LiNi _1-yz Co _y Mn _z O ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiMnO ₂ , Complex oxides of lithium and transition metals such as LiMn ₂ O ₄ and LiNi _0.5 Mn _1.5 O ₄ ; oxides such as TiO ₂ and V ₂ O ₅ ; sulfides such as TiS ₂ and FeS However, a composite oxide of lithium and a transition metal is preferable from the viewpoint of battery capacity and energy density.

  In the above, 1> x> 0, 1> y> 0, 1> z> 0, y + z <1.

  The positive electrode is formed by pressure-molding these positive electrode active materials together with known conductive aids and binders, or the positive electrode active materials are mixed with known conductive aids and binders in organic solvents such as pyrrolidone. The paste can be obtained by coating a current collector such as an aluminum foil and then drying.

  As the negative electrode active material, lithium metal, an alloy of lithium metal and another metal, or a material from which lithium ions are inserted and released is used. Examples of alloys of lithium metal and other metals include Li—Al, Li—Sn, Li—Zn, Li—Si, and the like. Examples of the material from which lithium ions are inserted and desorbed include carbon materials obtained by firing resin and pitch, carbon materials obtained by adding boron compounds to these carbon materials, natural graphite, and the like. These negative electrode active materials are used individually by 1 type or in mixture of 2 or more types.

  The negative electrode is formed by pressure molding these negative electrode active materials together with known conductive aids and binders, or the negative electrode active materials are mixed with organic solvents such as pyrrolidone together with known conductive aids and binders. The paste can be obtained by coating a current collector such as a copper foil and then drying.

  The separator is not particularly limited as long as the electrolyte is easy to pass through, is an insulator, and is a chemically stable material.

  The quaternary ammonium salt of the present invention and an electrolytic solution containing the same have high electrical conductivity and high solubility in an organic solvent, and are suitable as an electrolytic solution for an electrochemical device.

  Examples of the electrochemical device include, but are not limited to, an electric double layer capacitor, a secondary battery, a dye-sensitized solar cell, an electrochromic element, and a capacitor. Particularly suitable electrochemical devices are electric double layer capacitors and secondary batteries.

  Since the quaternary ammonium salt of the present invention has a melting point of 10 ° C. or lower, it can itself maintain a liquid form at room temperature (25 ° C.). In addition, the quaternary ammonium salt of the present invention is remarkably excellent in solubility in an organic solvent and has high electrical conductivity.

  The quaternary ammonium salt of the present invention which is itself liquid at room temperature (25 ° C.) can be used as an electrolytic solution as it is. Even when this electrolytic solution is used at a low temperature, no electrolyte is deposited, and stable electric conductivity can be expressed. Moreover, since this quaternary ammonium salt can be used as an electrolytic solution as it is, it is possible to increase the ion concentration of the electrolytic solution and to exhibit high electrical conductivity.

  The quaternary ammonium salt of the present invention, which is excellent in solubility in an organic solvent, can be dissolved in an organic solvent to form an electrolytic solution. The salt does not precipitate, and there is no possibility that the electrical conductivity of the electrolytic solution is lowered.

  The quaternary ammonium salt of the present invention is excellent in fluidity because of its low viscosity, and therefore can be suitably used in an electrolytic solution of an electric device using a porous electrode that requires permeability.

It is a fragmentary sectional view of the electric double layer capacitor created in Example 10 of the present invention. It is a fragmentary sectional view of the lithium secondary battery created in Example 12 of the present invention. It is a graph which shows the electrical conductivity of the mixed solution of various density | concentrations obtained in Example 6, Example 7, and Comparative Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode 2 Electrode 3 Separator 4 Container body 5 Container body 6 Gasket 7 Spacer 8 Spring 11 Positive electrode 12 Negative electrode 13 Porous separator 14 Positive electrode can 15 Negative electrode can 16 Gasket 17 Spacer 18 Spring

  EXAMPLES The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

Example 1
Synthesis of bis (methoxymethyl) dimethylammonium tetrafluoroborate 30.0 g of dimethylmethoxymethylamine was dissolved in 120 g of toluene and purged with nitrogen. To this solution, 16.3 g of chloromethyl methyl ether (reagent: manufactured by Tokyo Chemical Industry) was added dropwise at 5 ° C. over 1 hour. The solution was stirred at 5 ° C. for 10 hours to complete the reaction. The lower layer separated into two layers was separated, washed three times with 150 g of toluene, further washed three times with 150 g of methyl ethyl ketone, dried under reduced pressure, and 25.0 g of dimethyldimethoxymethylammonium chloride. (Colorless liquid) was obtained.

Next, the obtained dimethyldimethoxymethylammonium chloride was dissolved in 50 g of methanol, and 45.3 g of a 30% HBF ₄ methanol solution was added. Under reduced pressure, hydrogen chloride and excess HBF ₄ were removed to obtain 31.9 g of the title object product (colorless liquid).
¹ H-NMR (d-CH ₃ OH) δ ppm:
2.98 (s, 6H), 3.65 (s, 6H), 4.59 (s, 4H).

  The melting point of the quaternary ammonium salt (bis (methoxymethyl) dimethylammonium tetrafluoroborate) obtained above was measured using a differential thermal analyzer (RIGAKU, DSC8230B) manufactured by Rigaku Corporation. Specifically, the sample weight was 20 mg, and the sample was rapidly cooled to −150 ° C. with liquid argon, and then heated at a rate of 5 ° C./min. The melting point was determined from the intersection of the baseline tangent and the peak slope tangent. The melting point of the quaternary ammonium salt obtained in Example 1 was 4 ° C.

Example 2
Synthesis of bis (methoxymethyl) pyrrolidinium bistrifluoromethanesulfonylimide 30.0 g of methoxymethylpyrrolidine and 89.9 g of lithium bistrifluoromethanesulfonylimide were dissolved in 300 g of dichloromethane and substituted with nitrogen. To this solution, 21.0 g of chloromethyl methyl ether (reagent: manufactured by Tokyo Chemical Industry) was added dropwise at 5 ° C. over 1 hour. The temperature of the solution was gradually raised and stirred at room temperature for 4 hours to complete the reaction. 200 ml of water was added to the reaction solution, and the lower layer was separated. The obtained organic layer was repeatedly washed 10 times with 50 ml of water. The organic layer was concentrated and dried under reduced pressure to obtain 97.6 g of the title object product (colorless liquid).
¹ H-NMR (CDCl ₃ ) δ ppm:
2.17 (m, 4H), 3.47 (m, 4H), 3.60 (s, 6H), 4.53 (s, 4H).

  The melting point of the quaternary ammonium salt (bis (methoxymethyl) pyrrolidinium bistrifluoromethanesulfonylimide) obtained above was measured in the same manner as in Example 1. The melting point of the quaternary ammonium salt obtained in Example 2 could not be determined clearly. The glass transition temperature (Tg) was -90 ° C.

Comparative Example 1
N- (methoxyethyl) -N-methylpyrrolidinium tetrafluoroborate was synthesized according to WO 02/076924 A1.

  That is, pyrrolidine (68.77 g) and 2-methoxyethyl chloride (88.02 g) were placed in an autoclave and reacted at 90 ° C. for 24 hours. After completion of the reaction, 200 ml of an aqueous solution in which 56 g of potassium hydroxide was dissolved was added, and the organic layer was separated and extracted. The aqueous layer was extracted with dichloromethane 100 (repeated twice: 200 ml in total) and washed with saturated brine. The organic layer was dried over anhydrous potassium carbonate. The organic layer was filtered and dichloromethane was distilled off under reduced pressure. The residue was distilled, and 24.02 g of N- (methoxyethyl) pyrrolidine was isolated.

  10.00 g of the obtained N- (methoxyethyl) pyrrolidine was dissolved in 12 ml of tetrahydrofuran, and 11.22 g of methyl iodide was added at 0 ° C. The temperature was gradually raised and the reaction was carried out at room temperature for 24 hours. After completion of the reaction, tetrahydrofuran was distilled off under reduced pressure, and the residue was recrystallized with a tetrahydrofuran / ethanol mixed solvent to obtain 17.22 g of N- (methoxyethyl) -N-methylpyrrolidinium iodide.

  N- (methoxyethyl) -N-methylpyrrolidinium iodide 10.00 was dissolved in 67 ml of ultrapure water, and 4.27 g of silver oxide was added and stirred for 3 hours. The reaction solution was filtered to completely remove the precipitate, and then 42% tetrafluoroboric acid was added little by little until the pH reached 5-6. The reaction solution was freeze-dried and further dried under reduced pressure to obtain 8.26 g of the target product, N- (methoxyethyl) -N-methylpyrrolidinium tetrafluoroborate.

  The melting point of N- (methoxyethyl) -N-methylpyrrolidinium tetrafluoroborate obtained above was measured in the same manner as in Example 1. The melting point was 15 ° C.

Comparative Example 2
N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate was synthesized according to WO 02/076924 A1 (Patent Document 1).

  In an autoclave, 35.35 g of diethylamine and 43.99 g of 2-methoxyethyl chloride were added and reacted at 100 ° C. for 24 hours. After completion of the reaction, 100 ml of an aqueous solution in which 56 g of potassium hydroxide was dissolved was added, and the organic layer was separated and extracted. The aqueous layer was extracted with 50 ml of dichloromethane (repeated twice: 100 ml in total) and washed with saturated brine. The organic layer was dried over anhydrous potassium carbonate. The organic layer was filtered and dichloromethane was distilled off under reduced pressure, and then the residue was distilled to obtain 9.20 g of 2-methoxyethyldiethylamine.

  9.20 g of N- (methoxyethyl) -N, N-diethyl-N-methylammonium was dissolved in 11 ml of tetrahydrofuran, and 10.18 g of methyl iodide was added at 0 ° C. The temperature was gradually raised and the reaction was carried out at room temperature for 24 hours. After completion of the reaction, the tetrahydrofuran was distilled off under reduced pressure, and the residue was recrystallized with a tetrahydrofuran / ethanol mixed solvent to obtain 17.52 g of N- (methoxyethyl) -N, N-diethyl-N-methylammonium iodide. It was.

  10.00 g of N- (methoxyethyl) -N, N-diethyl-N-methylammonium iodide was dissolved in 67 ml of ultrapure water, and 4.25 g of silver oxide was added and stirred for 3 hours. The reaction solution was filtered to completely remove the precipitate, and then 42% tetrafluoroboric acid was added little by little until the pH reached 5-6. The reaction solution was freeze-dried and further dried under reduced pressure to obtain 8.20 g of the target product N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate.

  The melting point of N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate obtained above was measured in the same manner as in Example 1. The melting point was 8 ° C.

Example 3
Synthesis of bis (methoxymethyl) dimethylammonium bistrifluoromethanesulfonylimide 31.4 g of lithium bistrifluoromethanesulfonylimide (reagent: made by ALDRICH) was added to 108.7 g of N- (methoxymethyl) -N, N-dimethylamine, Cooled to 5 ° C. To this solution, 7.8 g of chloromethyl methyl ether (reagent: manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 1 hour. The reaction temperature was 10 ° C. or lower. After completion of the dropwise addition, the temperature was gradually raised and the reaction was allowed to proceed at room temperature for 16 hours. After completion of the reaction, the mixture was concentrated and dried with a vacuum pump. Extraction was performed with 500 g of dichloromethane / 500 g of water. The organic layer was washed 4 times with 300 g of water, concentrated and dried under reduced pressure to obtain 30.2 g of the desired product.
¹ H-NMR (d-CH ₃ OH) δ ppm:
2.98 (s, 6H), 3.65 (s, 6H), 4.59 (s, 4H).

  The melting point of the bis (methoxymethyl) dimethylammonium bistrifluoromethanesulfonylimide obtained above was measured in the same manner as in Example 1.

Synthesis example 1
Synthesis of N-ethoxymethylpyrrolidine 101.2 g of paraformaldehyde (reagent: manufactured by MERK), 234.0 g of potassium carbonate (reagent: manufactured by Wako Pure Chemical) and 971.3 g of ethyl alcohol (reagent: manufactured by Wako Pure Chemical), 300.0 g of pyrrolidine (reagent: manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise at 10 ° C or lower. The dripping took 2 hours. After completion of the dropwise addition, the mixture was reacted for 7 hours under reflux. Ethyl alcohol was distilled off, and the residue was distilled under reduced pressure (70 mmHg) to obtain 148.4 g of ethoxymethylpyrrolidine.
¹ H-NMR (CDCl ₃ ) δ ppm:
1.17 (t 3H), 1.75 (m 4H), 2.73 (m 4H), 3.49 (q 2H), 4.16 (s 2H).

Synthesis example 2
Synthesis of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium perchlorate 147.9 g of N-ethoxymethylpyrrolidine produced in Synthesis Example 1 was mixed with 59.18 g of sodium perchlorate (reagent; manufactured by Wako Pure Chemical Industries, Ltd.). Added and cooled to 5 ° C. To this solution, 36.93 g of chloromethyl methyl ether (reagent: manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 1 hour. The reaction temperature was 10 ° C. or lower. After completion of the dropping, the reaction mixture was gradually warmed and reacted at room temperature for 12 hours. After completion of the reaction, the mixture was filtered and washed with 100 ml of ethyl alcohol. After concentration, extraction was performed with dichloromethane / water. The organic layer was washed 3 times with a small amount of water and concentrated. The concentrate was dissolved in ethyl alcohol and recrystallized at -50 ° C. Recrystallization was repeated 5 times. The obtained crystals were dried under reduced pressure to obtain 83.0 g of the desired product.
¹ H-NMR (d-CH ₃ OH) δ ppm:
1.28 (t 3H), 2.16 (m 4H), 3.49 (m 4H), 3.62 (s 3H), 3.84 (q 2H), 4.61 (s 2H), 4. 66 (s 2H).

Example 4
Synthesis of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate 30.0 g of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium perchlorate prepared in Synthesis Example 2 was methylated. It melt | dissolved in 250 ml of alcohol, and let it pass through 500 ml of ion exchange resin (The anion of Mitsubishi Chemical DIAION WA30 was replaced | exchanged for tetrafluoroborate). Anion exchange was confirmed by ion chromatography (TOSOH CM-8020). After confirming the anion exchange, the methyl alcohol solution was concentrated and dried under reduced pressure to obtain 26.1 g of the desired product.
¹ H-NMR (d-CH ₃ OH) δ ppm:
1.28 (t 3H), 2.15 (m 4H), 3.48 (m 4H), 3.62 (s 3H), 3.84 (q 2H), 4.60 (s 2H), 4. 65 (s 2H).

  The melting point of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate obtained above was measured in the same manner as in Example 1.

Example 5
Synthesis of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium bistrifluoromethanesulfonylimide 50.0 g of N-ethoxymethylpyrrolidine prepared in Synthesis Example 1 was added to lithium bistrifluoromethanesulfonylimide (reagent: manufactured by ALDRICH). 48.9 g was added and cooled to 5 ° C. To this solution, 12.5 g of chloromethyl methyl ether (reagent: manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 1 hour. The reaction temperature was 10 ° C. or lower. After completion of the dropping, the reaction mixture was gradually warmed and reacted at room temperature for 5 hours. After completion of the reaction, the reaction mixture was concentrated, dried with a vacuum pump, and extracted with 1300 g of dichloromethane / 1000 g of water. The organic layer was washed 4 times with 1000 g of water, concentrated and dried under reduced pressure to obtain 65.9 g of the desired product.
¹ H-NMR (d-CH ₃ OH) δ ppm:
1.28 (t 3H), 2.15 (m 4H), 3.46 (m 4H), 3.62 (s 3H), 3.83 (q 2H), 4.59 (s 2H), 4. 64 (s 2H).

  The melting point of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium bistrifluoromethanesulfonylimide obtained above was measured in the same manner as in Example 1.

Test example 1
For the quaternary ammonium salts obtained in Examples 1 to 5, Comparative Example 1 and Comparative Example 2, the electrical conductivity was measured.

  For measurement of electric conductivity, an electric conductivity meter manufactured by Radiometer was used. CDC641T manufactured by Radiometer was used for the measurement cell, and the measurement was performed at 25 ° C.

  Moreover, the viscosity of the quaternary ammonium salt obtained in Examples 1-5, Comparative Example 1, and Comparative Example 2 was measured. The viscosity was measured at 25 ° C. using a vibration viscometer (VM-1G CBC Materials Co., Ltd.).

  These results are shown in Table 1.

Example 6
N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate and propylene carbonate (PC) (reagent: manufactured by Kishida Chemical Co., Ltd., lithium battery grade) produced in Example 4 were used at various concentrations. So that the dew point was −60 ° C. or less in a nitrogen atmosphere dry box. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less. The concentration of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate in the mixed solution was as shown in Table 2.

  Each 4 ml of the mixed solution of various concentrations was transferred to a glass container with a screw stopper in the dry box and taken out of the dry box. Glass containers containing various solutions were immersed in a thermostatic bath and held at 25 ° C. for 5 hours, respectively.

Example 7
The dew point is −60 so that the bis (methoxymethyl) dimethylammonium tetrafluoroborate produced in Example 1 and propylene carbonate (PC) (reagent: manufactured by Kishida Chemical Co., Ltd., lithium battery grade) have various concentrations. Mixing was performed in a nitrogen atmosphere dry box at a temperature not higher than 0C. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less. The concentration of bis (methoxymethyl) dimethylammonium tetrafluoroborate in the mixed solution was as shown in Table 3.

  Each 4 ml of the mixed solution of various concentrations was transferred to a glass container with a screw stopper in the dry box and taken out of the dry box. Glass containers containing various solutions were immersed in a thermostatic bath and held at 25 ° C. for 5 hours, respectively.

Comparative Example 3
N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate prepared in Comparative Example 2 and propylene carbonate (PC) (made by Kishida Chemical Co., Ltd., lithium battery grade) at various concentrations As such, they were mixed in a nitrogen atmosphere dry box having a dew point of -60 ° C or lower. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less. The concentration of N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate in the mixed solution was as shown in Table 4.

Each 4 ml of the mixed solution of various concentrations was transferred to a glass container with a screw stopper in the dry box and taken out of the dry box. Glass containers containing various solutions were immersed in a thermostatic bath and held at 25 ° C. for 5 hours, respectively.
<Measurement of electrical conductivity>
After observing the mixed state of the various solutions, the various solutions were again taken out from the dry box and the electrical conductivity was measured. For the measurement of electrical conductivity, a conductivity meter (CDM210 Radiometer) was used. XE-100 (manufactured by Radiometer) was used for the measurement cell. The results are shown in Table 2, Table 3, Table 4, and FIG.

Example 8
N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate produced in Example 4 and ethyl methyl carbonate (EMC) (reagent: manufactured by Kishida Chemical Co., Ltd., lithium battery grade) Mixing was performed in a nitrogen atmosphere dry box having a dew point of −60 ° C. or lower so as to obtain a concentration. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less. The concentration of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate in the mixed solution was as shown in Table 5.

  Each 4 ml of each mixed solution was transferred to a glass container with a screw stopper in the dry box and taken out of the dry box. Glass containers containing various solutions were immersed in a thermostatic bath and held at 25 ° C. for 5 hours, respectively.

Comparative Example 4
N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate and ethyl methyl carbonate (EMC) produced in Comparative Example 2 (reagent: manufactured by Kishida Chemical Co., Ltd., lithium battery grade) Mixing was performed in a nitrogen atmosphere dry box having a dew point of −60 ° C. or lower so as to obtain various concentrations. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less. The concentration of N- (methoxyethyl) -N, N-diethyl-N-methylammonium tetrafluoroborate in the mixed solution was as shown in Table 6.

Comparative Example 5
N- (methoxyethyl) -N-methylpyrrolidinium tetrafluoroborate produced in Comparative Example 1 and ethyl methyl carbonate (EMC) (reagent: manufactured by Kishida Chemical Co., Ltd., lithium battery grade) have various concentrations. Thus, it mixed in the nitrogen atmosphere dry box whose dew point is -60 degrees C or less. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less. The concentration of N- (methoxyethyl) -N-methylpyrrolidinium tetrafluoroborate in the mixed solution was as shown in Table 7.

Each 4 ml of each mixed solution was transferred to a glass container with a screw stopper in the dry box and taken out of the dry box. Glass containers containing various solutions were immersed in a thermostatic bath and held at 25 ° C. for 5 hours, respectively.
<Measurement of electrical conductivity>
The mixed state of various solutions was observed, and the electrical conductivity of the mixture in the solution state that was not separated was measured in the same manner as described above. The results are shown in Tables 5-7.

Example 9
N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium bis (trifluoromethanesulfonyl) imide obtained in Example 5 was mixed with lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) at 0.5 M or 1. It mixed so that it might become a density | concentration of 0M. Mixing was performed in a nitrogen atmosphere dry box having a dew point of −60 ° C. or lower. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less.

Comparative Example 6
After drying N- (methoxyethyl) -N, N-diethyl-N-methylammonium bis (trifluoromethanesulfonyl) imide (reagent: for material research, manufactured by Kanto Chemical Co., Ltd.) under reduced pressure (water content 20 ppm or less), lithium bis ( Trifluoromethanesulfonyl) imide (LiTFSI) was added to a concentration of 0.5M or 1.0M and mixed in a nitrogen atmosphere dry box having a dew point of −60 ° C. or lower. The water content of the mixed solution was measured with a Karl Fischer moisture meter (Hiranuma Sangyo Co., Ltd., Hiranuma trace moisture measuring device AQ-7) and confirmed to be 30 ppm or less.
<Measurement of electrical conductivity>
After observing the mixed state of various solutions, the solution was taken out from the dry box again, and the electrical conductivity was measured in the same manner as described above. The results are shown in Table 8.

Example 10 (Production of an electric double layer capacitor)
Of the mixed solution (electrolytic solution) produced in Example 6, the following electric double layer capacitor was prepared using a mixed solution of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium tetrafluoroborate concentration 2M. did.

  The electrode 1 and the electrode 2 were obtained by applying a paste obtained by kneading together with a conductive substance mainly composed of activated carbon, a binder, and N-methylpyrrolidone to an aluminum foil to a thickness of 150 μm and then drying the paste. A sheet-like electrode is cut into a disk shape.

  The container body 4, the container body 5, the spacer 7, and the spring 8 are all made of stainless steel, and the separator 7 is a polypropylene nonwoven fabric.

  The electric double layer capacitor was assembled in a glove box filled with argon gas. The electrode 1, the electrode 2, the container body 4, the container body 5, the spring 8 and the spacer 7 were vacuum dried under heating at 120 ° C. for 24 hours, and then brought into the glove box. The electrode 1, electrode 2 and separator 3 were impregnated with the mixed solution (electrolytic solution for electric double layer capacitor) obtained in Example 6. As shown in FIG. 1, the electrode 1, the separator 3, the electrode 2, the spacer 7, and the spring 8 are sequentially placed on the container body 4, the gasket 6 is inserted, and the container is placed thereon. Body 5 was placed. The opening part of the container body 4 was sealed by bending inward to produce an electric double layer capacitor.

  After the coin-type electric double layer capacitor created above was set in a dedicated holder, charging / discharging of the electric double layer capacitor was started. Constant current charging with a current density of 2.0 mA was performed, and switching to constant voltage charging was performed when the voltage reached 2.5V. After holding at 2.5 V for 120 minutes, a constant current discharge of 2.0 mA was performed, and when the voltage reached 0 V, the voltage was switched to low voltage discharge, and the charge and discharge characteristics were examined by holding at 0 V for 120 minutes. As a result, the electric double layer capacitor of the present invention prepared in Example 10 showed good charge / discharge characteristics.

Example 11 (Preparation of electrolyte solution for lithium secondary battery)
Using 5 wt% of N- (ethoxymethyl) -N- (methoxymethyl) pyrrolidinium bis (trifluoromethanesulfonyl) imide prepared in Example 5 and lithium bistrifluoromethanesulfonylimide (LiTFSI) 0.5M as a lithium salt, A non-aqueous electrolyte was prepared using vinylene carbonate (VC) 5 wt% as the non-aqueous solvent and the remainder using ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 1/3 (V / V).

Example 12 (Preparation of lithium secondary battery)
A coin-type non-aqueous electrolyte lithium secondary battery as shown in FIG. 2 was prepared. In FIG. 2, 11 is a positive electrode, 12 is a negative electrode, 13 is a porous separator, 14 is a positive electrode can, 15 is a negative electrode can, 16 is a gasket, 17 is a spacer, and 18 is a spring.

  A non-aqueous electrolyte lithium secondary battery shown in FIG. 2 was prepared by the following procedure.

Creation of negative electrode 12:
Natural graphite and binder polyvinylidene fluoride (PVdF) were mixed at a weight ratio of 9: 1, and N-methylpyrrolidone was added thereto to obtain a paste. This paste was uniformly applied onto a copper foil having a thickness of 22 μm using an electrode applicator. This was vacuum-dried at 120 ° C. for 8 hours, and a negative electrode 12 having a diameter of 16 mm was obtained with an electrode punching machine.

Creation of positive electrode 11:
LiCoO ₂ powder, acetylene black as a conductive additive, and PVdF as a binder were mixed at a weight ratio of 90: 5: 5, and N-methylpyrrolidone was added to this mixture to obtain a paste. This paste was vacuum-dried at 120 ° C. for 8 hours, and a positive electrode 11 having a diameter of 16 mm was obtained with an electrode punching machine.

  After placing the positive electrode 11 on the bottom surface of the positive electrode can 14 and placing the porous separator 13 thereon, the non-aqueous electrolyte prepared in Example 11 was injected, and the gasket 16 was inserted. Thereafter, the negative electrode 12, the spacer 17, the spring 18, and the negative electrode can 15 are placed on the separator 13 one after another, and the opening portion of the positive electrode can 14 is placed inside using a coin-type battery crimper machine. The non-aqueous electrolyte lithium secondary battery was prepared by bending the film in a bent direction.

  The battery prepared as described above was evaluated as follows. Charging was performed at a constant current of 0.4 mA, and constant voltage charging was performed at 4.1 V for 1 hour when the voltage reached 4.1 V. Discharging was performed at a constant current of 1.0 mA, and discharging was performed until the voltage reached 3V. When the voltage reached 3V, it was held at 3V for 1 hour, and the charge / discharge characteristics were examined. As a result, the secondary battery of the present invention produced in Example 11 showed good cycle characteristics.

Claims (18)

General formula
[Wherein, R ¹ and R ² are the same or different and each represents a C _1-4 alkyl group. R ¹ and R ² may be bonded together with the nitrogen atom to which they are bonded to form a saturated heterocyclic ring. R ³ and R ⁴ are the same or different and each represents a methyl group or an ethyl group. X ⁻ represents an anion. ]
A quaternary ammonium salt represented by The quaternary ammonium salt according to claim 1, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a 3- to 5-membered saturated heterocyclic ring. The quaternary ammonium salt according to claim 2, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a pyrrolidine ring. The quaternary ammonium salt according to claim ^1, wherein R ¹ and R ² are both methyl groups. Wherein X _{^{-, BF 4 -, AlCl 4 -}} , Al 2 Cl 7 -, PF 6 -, AsF 6 -, N (CF 3 SO 2) 2 -, N (CF 3CF2 SO 2) 2 -, C (CF 3 _{^{SO 2) 3 -, N (}} CF 3 SO 2) (CF 3 CO) -, CF 3 SO 3 -, CH 3 SO 3 -, CH 3 CO 2 -, CF 3 COO -, NO 3 -, C 6 H ₅ COO ^{- _{also, C 6 H 5 SO 3 -}} , CF3BF3 -, C2F5BF3 - or I ^- quaternary ammonium salt according to claim 1 is. Wherein X ^-, BF ₄ ^- or _{N (CF 3 SO 2) 2} - quaternary ammonium salt of claim 5 which is a. General formula
[Wherein, R ¹ and R ² are the same or different and each represents a C _1-4 alkyl group. R ¹ and R ² may be bonded together with the nitrogen atom to which they are bonded to form a saturated heterocyclic ring. R ³ and R ⁴ are the same or different and each represents a methyl group or an ethyl group. X ⁻ represents an anion. ]
An electrolyte comprising a quaternary ammonium salt represented by: The electrolyte according to claim 7, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a quaternary ammonium salt which is a 3- to 5-membered saturated heterocyclic ring. The electrolyte according to claim 8, wherein the saturated heterocyclic ring formed by bonding together with the nitrogen atom to which R ¹ and R ² are bonded is a quaternary ammonium salt which is a pyrrolidine ring. The electrolyte according to claim 7, wherein R ¹ and R ² are quaternary ammonium salts in which both are methyl groups. Wherein X _{^{-, BF 4 -, AlCl 4 -}} , Al 2 Cl 7 -, PF 6 -, AsF 6 -, N (CF 3 SO 2) 2 -, N (CF 3CF2 SO 2) 2 -, C (CF 3 _{^{SO 2) 3 -, N (}} CF 3 SO 2) (CF 3 CO) -, CF 3 SO 3 -, CH 3 SO 3 -, CH 3 CO 2 -, CF 3 COO -, NO 3 -, C 6 H ₅ COO ^{- _{also, C 6 H 5 SO 3 -}} , CF3BF3 -, C2F5BF3 - or I ^- a is electrolyte according to any one of claims 7 to 10 comprising a quaternary ammonium salt. The electrolyte according to claim 11, wherein X ⁻ is a quaternary ammonium salt which is BF ₄ ^— or N (CF ₃ SO ₂ ) ₂ ^— .   The electrolyte solution containing the 1 type (s) or 2 or more types of the electrolyte in any one of Claims 7-12.   The electrolytic solution according to claim 13, comprising at least one of the electrolytes according to claim 7 and an organic solvent.   The electrolytic solution according to claim 14, wherein the organic solvent is at least one selected from the group consisting of cyclic carbonates, chain carbonates, nitrile compounds, and sulfone compounds.   The electrolytic solution according to claim 15, wherein the organic solvent is at least one selected from the group consisting of propylene carbonate, ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate.   An electrochemical device comprising the electrolytic solution according to claim 13.   The electrochemical device according to claim 17, wherein the electrochemical device is an electric double layer capacitor or a secondary battery.