JP2008239514A - Aminosiloxane-type ionic liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ionic liquid which has high ionic conductivity and is stable over a wider voltage range, and is usable as an electrolyte for electrochemical devices such as a primary or secondary lithium ion battery, a dye-sensitized solar cell, an electric double-layer capacitor and an electrochromic display element. <P>SOLUTION: The ionic liquid comprises an aminosiloxane quaternary salt expressed by formula (1) (R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>, R<SP>6</SP>, R<SP>7</SP>, R<SP>10</SP>, R<SP>11</SP>and R<SP>12</SP>are each an alkyl group or an alkoxyalkyl group; R<SP>4</SP>, R<SP>5</SP>, R<SP>8</SP>and R<SP>9</SP>are each a hydrogen atom, an alkyl group or an alkoxyalkyl group; R<SP>1</SP>and R<SP>2</SP>, R<SP>4</SP>and R<SP>5</SP>, R<SP>6</SP>and R<SP>7</SP>, R<SP>8</SP>and R<SP>9</SP>, and R<SP>10</SP>and R<SP>11</SP>may together form a ring structure; l, m and n are each an integer of ≥1 and ≤15; and Y<SP>-</SP>is a univalent anion). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to novel ionic liquids having aminosiloxane cations useful as electrolytes in electrochemical devices.

  In electrochemical devices such as lithium batteries, electric double layer capacitors, electrolytic capacitors, electrochromic elements, and dye-sensitized solar cells, a solution in which an electrolyte is dissolved in an organic solvent such as propylene carbonate, γ-butyrolactone, and acetonitrile as a non-aqueous electrolyte Is used. However, since the organic solvent used in these electrolyte solutions is volatile and is itself a dangerous substance, there have been concerns about problems with long-term reliability, durability, and safety.

  Thus, as one method for solving such a problem, there is a method using an ionic liquid as an electrolyte. An ionic liquid is a general term for compounds having a melting point of 100 ° C. or less composed of a combination of an anion and a cation, and it is proposed that necessary characteristics can be expressed by a combination of ions according to the purpose (non-patent). Reference 1). As its use, utilization to a reaction solvent, a battery electrolyte, a lubricant, a heat medium, etc. has been proposed (Non-Patent Document 2).

  Several proposals have also been made on electrolytes used in electrochemical devices. For example, there are alkyl-substituted imidazolium salts (for example, Patent Documents 1 to 4) and quaternary alkyl ammonium salts (for example, Patent Documents 5 to 8).

  Although these ionic liquids have been proposed to exhibit the necessary characteristics by combining ions according to the purpose as described above, in most developments, quaternary imidazolium and alicyclic compounds are proposed. At present, quaternary ammonium, quaternary alkylammonium and the like are used, and a breakthrough with a new skeleton has been required.

  Therefore, the present inventors have made a search for a novel skeleton aimed at an electrolyte used in an electrochemical device, and as a result, have focused on aminosiloxane-based quaternary salts. However, for the use of aminosiloxane-based quaternary salts so far, antibacterial agents (Patent Document 9), fabric softeners (Patent Document 10), additives to polymer materials (Patent Document 11), dye-sensitized solar cells There are only reports of lithium secondary batteries (Patent Documents 12 and 13). Even in reports on dye-sensitized solar cells and lithium secondary batteries, the electrochemical characteristics of aminosiloxane-based quaternary salts, in particular, the potential window serving as an index of ionic conductivity and electrochemical stability are not disclosed, Its effectiveness was unknown.

JP-A-8-259543 JP 2003-62467 Japanese Patent Laid-Open No. 11-86905 Japanese Patent No. 347213 WO02 / 076924 Publication JP 2003-331918 A Japanese Patent No. 2981545 JP 2004-67543 A Japanese Patent Laid-Open No. 6-25421 JP-A-62-298775 Japanese Patent Laid-Open No. 11-512130 Japanese Patent Laid-Open No. 2002-298913 JP 2002-251916 Chem. & Eng. News, May 15, 2000 issue Functional creation and application of ionic liquids, NTS Corporation 2004

  An object of the present invention is to provide an ionic liquid that is stable in a wider potential range and has high ionic conductivity.

  Therefore, as a result of intensive studies to solve such problems, the present inventors have found that an ionic liquid having aminosiloxane as a cation is stable in a wide potential range and has high ionic conductivity, The present invention has been reached.

（式中、R¹，R²，R³，R⁶，R⁷，R¹⁰，R¹¹及びR¹²は独立にアルキル基またはアルコキシアルキル基を示す。R⁴，R⁵，R⁸及びR⁹は独立に水素またはアルキル基またはアルコキシアルキル基を示す。R¹とR²、R⁴とR⁵、R⁶とR⁷、R⁸とR⁹、R¹⁰とR¹¹は、それぞれ一体となって環構造を形成しても良い。ｌ，ｍ，ｎは１以上１５以下の整数を示す。Ｙ^-は一価のアニオンを示す。） The present invention is an ionic liquid comprising an aminosiloxane quaternary salt represented by the following formula (1).

(In the formula, R ¹ , R ² , R ³ , R ⁶ , R ⁷ , R ¹⁰ , R ¹¹ and R ¹² independently represent an alkyl group or an alkoxyalkyl group. R ⁴ , R ⁵ , R ⁸ and R ⁹ Each independently represents hydrogen, an alkyl group or an alkoxyalkyl group, wherein R ¹ and R ² , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ⁸ and R ⁹ , R ¹⁰ and R ¹¹ are combined together. A ring structure may be formed. L, m, and n represent an integer of 1 to 15. Y ⁻ represents a monovalent anion.)

Further, the present invention relates to the formula (1), wherein Y ⁻ is (R ¹³ SO ₂ ) ₂ N ⁻ , R ¹³ SO ₃ ⁻ , R ¹³ COO ⁻ , BF ₄ −, PF ₆ ⁻ , NO ₃ ⁻ , (CN ) The above ionic liquid which is an anion selected from ₂ N ^- and a halogen ion (R ¹³ represents a perfluoroalkyl group, an alkyl group or an aromatic group).

Further, in the present invention, an alkylating agent represented by the following formula (3) is allowed to act on the aminosiloxane compound represented by the following formula (2), and then the leaving group X and the monovalent are used as necessary. anions Y ^- to a salt exchange reaction with an amino siloxane quaternary salt manufacturing method represented by the following formula (4), characterized in.

In the formula, R ¹ , R ² , R ⁶ , R ⁷ , R ¹⁰ and R ¹¹ independently represent an alkyl group or an alkoxyalkyl group, and R ⁴ , R ⁵ , R ⁸ and R ⁹ independently represent a hydrogen or alkyl group. Or an alkoxyalkyl group is shown. R ¹ and R ² , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ⁸ and R ⁹ , and R ¹⁰ and R ¹¹ may be combined to form a ring structure. l, m, and n represent an integer of 1 to 15. R ³ independently represents an alkyl group or an alkoxyalkyl group, and X represents a leaving group. Y ⁻ represents X or a monovalent anion generated by a salt exchange reaction. In addition, in Formula (2)-Formula (4), the same symbol has the same meaning.

  Moreover, this invention is an electrolyte characterized by including said ionic liquid. Furthermore, the present invention is an electrochemical cell characterized by using an electrolyte containing the above ionic liquid. Furthermore, the present invention is an electrolytic capacitor, an electric double layer capacitor or a lithium secondary battery characterized by using the above electrolyte.

  Hereinafter, the present invention will be described in more detail.

The ionic liquid used in the present invention comprises an aminosiloxane quaternary salt represented by the formula (1). In the formula, R ¹ , R ² , R ³ , R ⁶ , R ⁷ , R ¹⁰ , R ¹¹ and R ¹² independently represent an alkyl group or an alkoxyalkyl group. R ¹ and R ² , R ⁶ and R ⁷ , R ¹⁰ and R ¹¹ may be combined to form a ring structure. R ¹ and R ¹⁰ , R ² and R ¹¹ , R ³ and R ¹² , and R ⁶ and R ⁷ are preferably the same from the viewpoint of ease of production of the ionic liquid. Preferred examples of the alkyl group include C1 to C12 alkyl groups. The alkoxyalkyl group is preferably a C1 to C8 lower alkoxyalkyl group, for example, methoxymethyl group, methoxyethyl group, methoxypropyl group, methoxybutyl group, ethoxyethyl group, ethoxypropyl group, ethoxybutyl group, propyloxyethyl. Group, isopropyloxyethyl group, isopropyloxypropyl group, butoxyethyl group, butoxypropyl group, butoxybutyl group and the like can be exemplified.

R ⁴ , R ⁵ , R ⁸ and R ⁹ independently represent hydrogen, an alkyl group or an alkoxyalkyl group. R ⁴ and R ⁵ , and R ⁸ and R ⁹ may be combined to form a ring structure. R ⁴ and R ⁸ and R ⁵ and R ⁹ are preferably the same type from the viewpoint of ease of production of the ionic liquid. Preferred examples of the alkyl group include C1 to C12 alkyl groups. The alkoxyalkyl group is preferably a C1 to C8 lower alkoxyalkyl group, for example, methoxymethyl group, methoxyethyl group, methoxypropyl group, methoxybutyl group, ethoxyethyl group, ethoxypropyl group, ethoxybutyl group, propyloxyethyl. Group, isopropyloxyethyl group, isopropyloxypropyl group, butoxyethyl group, butoxypropyl group, butoxybutyl group and the like can be exemplified.

  l, m, and n each represent an integer of 1 to 15, preferably l and n are integers from 1 to 6, and m is an integer from 1 to 10.

Y ⁻ represents a monovalent anion, preferably selected from (R ¹³ SO ₂ ) ₂ N ⁻ , R ¹³ SO ₃ ⁻ , R ¹³ COO ⁻ , BF ₄ −, PF ₆ ⁻ , NO ₃ ⁻ and halogen ions. Anions can be exemplified. Here, R ¹³ independently represents a perfluoroalkyl group, an alkyl group or an aromatic group. The perfluoroalkyl group is preferably a C1-C8 perfluoroalkyl group. The alkyl group is preferably a C1 to C12 alkyl group. As the aromatic group, a substituted or unsubstituted aromatic group can be used. For example, a phenyl group, an alkylphenyl group, an alkyloxyphenyl group, a halogenated phenyl group, a nitrophenyl group, an acylphenyl group, and an alkoxycarbonylphenyl group can be exemplified. Two molecules of Y ⁻ may be integrated to form a divalent anion. Examples thereof include unsaturated divalent carboxylic acid anions such as maleic acid and fumaric acid, saturated divalent carboxylic acid anions such as oxalic acid and succinic acid, and aromatic divalent carboxylic acid anions such as phthalic acid.

  The aminosiloxane quaternary salt represented by the formula (1) can be produced by a known method, but the aminosiloxane compound represented by the formula (2) and the alkylating agent represented by the formula (3) acted on. It can manufacture efficiently by using the method by making it.

The alkylating agent that acts on the aminosiloxane compound represented by the formula (2) is represented by the formula (3). In the formula, R ³ represents an alkyl group or an alkoxyalkyl group. In formula (3), R ³ has the same meaning as R ³ described in formula (1). X represents a leaving group. Examples of the leaving group include a halogen atom, a perfluoroalkanesulfonyloxy group, a perfluoroalkanecarbonyloxy group, a toluenesulfonyloxy group, a benzenesulfonyloxy group, and an acyloxy group. In the formula (1), when R ¹² is the same as R ³ , the chemical formula is the same as in the formula (4).

  The amount of the alkylating agent used for the alkylation reaction of the aminosiloxane compound is usually a 2-fold molar amount or more. On the other hand, it may be economically preferable to carry out at a molar amount of 2 or less in consideration of the removal of reaction by-products from the alkylating agent. Preferably, it is the range of 2-5 times mole.

  Solvents are not limited as long as they do not inhibit the reaction, but aliphatic hydrocarbons such as hexane, heptane and petroleum ether, aromatic hydrocarbons such as benzene, toluene and xylene, and organic nitro compounds such as nitromethane and nitrobenzene. , Cyclic ether compounds such as tetrahydrofuran and dioxane, halides such as dichloromethane, chloroform and tetrachloroethane, nitrile compounds such as acetonitrile and benzonitrile, lower aliphatic alcohols such as methanol, ethanol and isopropyl alcohol, dimethyl sulfoxide, dimethylacetamide, Examples include aprotic polar solvents such as sulfolane, N-methylpyrrolidone, and dimethylimidazolidinone, and water.

  The reaction temperature of the alkylation reaction is usually room temperature to 150 ° C, preferably room temperature to 100 ° C. The reaction time is usually 0.5 to 24 hours, preferably 1 to 10 hours.

After completion of the reaction, an aminosiloxane-based quaternary salt represented by the formula (1) or (4) can be obtained by processing according to a conventional method. The desired Y ⁻ can be obtained depending on the treatment method, but aminosiloxane-based quaternary salts having various Y ⁻ can be easily obtained by using the following methods, which is preferable. That is, after carrying out the alkylation reaction of the aminosiloxane represented by the formula (2), the by-product and unreacted raw materials are removed by subjecting the reaction mixture to adsorption treatment such as silica gel, and then the solvent is distilled off. An aminosiloxane quaternary salt having a leaving group as an anion can be obtained. A desired ionic liquid can be obtained by subjecting the aminosiloxane quaternary salt obtained by such a method to a salt exchange reaction, if necessary. As a salt exchange method, a known salt exchange reaction used in a quaternary ammonium salt or the like can be performed. In addition, when X of Formula (3) is a leaving group which gives Y or Y, the target aminosiloxane type | system | group quaternary salt can be obtained, without performing a salt exchange reaction. Otherwise, the target aminosiloxane quaternary salt can be obtained by performing a salt exchange reaction using a salt such as MY (M represents a cation).

Examples of a preferred cationic structure of the aminosiloxane-based quaternary salt represented by the formula (1) (part excluding Y ⁻ from the formula (1)) are shown below, but are not limited thereto. The number described below the chemical formula is the chemical formula number. A preferable amino siloxane quaternary salts, and Y the cationic moiety ^- consists of.

  The ionic liquid of the present invention comprises an aminosiloxane quaternary salt represented by the formula (1). Since the ionic liquid of the present invention generally has a low melting point and high ion conductivity, electrochemical devices such as primary and secondary lithium ion batteries, dye-sensitized solar cells, electric double layer capacitors, and electrochromic display elements It can be used as an electrolyte. When using the ionic liquid of this invention for these uses, 1 type of ionic liquids which consist of aminosiloxane quaternary salts may be used, and 2 or more types may be mixed and used. Furthermore, the ionic liquid of the present invention may be used by mixing with a salt different from an aminosiloxane quaternary salt that can be used as an electrolyte in an electrochemical device. Further, the ionic liquid of the present invention or a mixture of salts different from the ionic liquid of the present invention may be used by dissolving in a solvent.

  By using the ionic liquid composed of the quaternary salt of aminosiloxane of the present invention as an electrolyte, electric such as primary and secondary lithium ion batteries, dye-sensitized solar cells, electric double layer capacitors, electrolytic capacitors, electrochromic display elements, etc. By constituting a chemical device, an electrochemical device having excellent low-temperature characteristics and long-term stability can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
1,3-bis (3-dimethylaminopropyl) tetramethyldisiloxane (3.05 g, 10 mmol), methanol 40 ml and methyl iodide (1.8 ml, 30 mmol) were added to a three-necked flask equipped with a reflux tube and refluxed. After 2 hours, the mixture was cooled to room temperature, the solvent was distilled off under reduced pressure, and the residue was recrystallized to obtain a white solid.

2.87 g of the obtained white solid and bis (trifluoromethanesulfonyl) imidolithium (3.16 g, 11 mmol) were added to 40 ml of methanol and stirred at room temperature. After 4 hours, the solvent was distilled off under reduced pressure, and then ethyl acetate and water were added to the residue and dissolved at room temperature. After removing the aqueous layer, 0.5 g of activated carbon was added to the ethyl acetate layer and stirred. After 1 hour, the activated carbon was removed and then distilled off under reduced pressure to obtain a pale yellow oil. ^{As a result of 1} H-NMR and ¹³ C-NMR measurements, the product is a salt having the chemical formula number 1 as a cation and bis (trifluoromethanesulfonyl) imide as an anion (hereinafter referred to as aminosiloxane-based ionic liquid 1-TFSI). I understood it.

¹ H-NMR (CD3OD) measurement results of aminosiloxane-based ionic liquid 1-TFSI are shown in FIG. 1, and ¹³ C-NMR (CDCl ₃ ) measurement results are shown in FIG.
¹ H-NMR (CD3OD); d 3.25 (m, 4H), 3.06 (s, 18H), 1.72 (m, 4H), 0.51 (m, 4H), 0.09 (s, 12H)
¹³ C-NMR (CD3OD); d 120 (q, J = 320 Hz, SO ₂ CF ₃ ), 70, 54, 18, 15, 0

  Table 1 shows the results obtained by measuring the ionic conductivity of the obtained aminosiloxane-based ionic liquid 1-TFSI in a 1M propylene carbonate solution by an alternating current impedance method. Moreover, when CV measurement was performed, the potential window was −3.3 to 2.6 v with respect to Ag / Ag +.

¹ H-NMR chart of the ionic liquid obtained in Example 1 ¹³ C-NMR chart of the ionic liquid obtained in Example 1

Claims (7)

Following formula (1)

(In the formula, R ¹ , R ² , R ³ , R ⁶ , R ⁷ , R ¹⁰ , R ¹¹ and R ¹² independently represent an alkyl group or an alkoxyalkyl group, and R ⁴ , R ⁵ , R ⁸ and R ⁹ Each independently represents hydrogen, an alkyl group or an alkoxyalkyl group, wherein R ¹ and R ² , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ⁸ and R ⁹ , R ¹⁰ and R ¹¹ are combined together. A ring structure may be formed, wherein l, m, and n represent an integer of 1 to 15, and Y ⁻ represents a monovalent anion. Ionic liquid. In the formula (1), R ¹ and R ¹⁰ , R ² and R ¹¹ , R ³ and R ¹² , R ⁴ and R ⁸ , R ⁵ and R ⁹ or R ⁶ and R ⁷ are the same. The ionic liquid according to claim 1. In the formula (1), Y ⁻ represents (R ¹³ SO ₂ ) ₂ N ⁻ , R ¹³ SO ₃ ⁻ , R ¹³ COO ⁻ , BF ₄ −, PF ₆ ⁻ , NO ₃ ⁻ , (CN) ₂ N ⁻ and halogen The ionic liquid according to claim 1 or 2, wherein the ionic liquid is an anion selected from ions (R ¹³ represents a perfluoroalkyl group, an alkyl group or an aromatic group). Following formula (2)

(In the formula, R ¹ , R ² , R ⁶ , R ⁷ , R ¹⁰ and R ¹¹ independently represent an alkyl group or an alkoxyalkyl group, and R ⁴ , R ⁵ , R ⁸ and R ⁹ independently represent hydrogen, alkyl R ¹ and R ² , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ⁸ and R ⁹ , R ¹⁰ and R ¹¹ together form a ring structure. L, m and n represent an integer of 1 or more and 15 or less.)
Following formula (3)
R ³ X (3)
(R ³ represents an alkyl group or an alkoxyalkyl group. X represents a leaving group). Then, the leaving group X and a monovalent anion Y ⁻ are reacted as necessary. Formula (4) characterized by performing a salt exchange reaction with

(Wherein R ^{1 to} R ¹¹ , l, m and n are the same as those in the formulas (2) and (3). Y ⁻ represents X or a monovalent anion generated in a salt exchange reaction). The manufacturing method of the ionic liquid which consists of aminosiloxane quaternary salt represented.   An electrolyte comprising the ionic liquid according to claim 1, 2 or 3.   6. An electrochemical cell using the electrolyte according to claim 5 as an electrolyte of an electrochemical cell.   An electrolytic capacitor, an electric double layer capacitor or a lithium secondary battery using the electrolyte according to claim 5.

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