JP2009230905A - Amino siloxane-based proton exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proton exchanger which gives proton conductivity even in non-humidified condition. <P>SOLUTION: The proton exchanger contains a salt which is obtained by an amino siloxane-based compound as expressed by formula (1) and Broensted acid. In the formula, R<SP>1</SP>, R<SP>2</SP>, R<SP>11</SP>, R<SP>12</SP>express independently hydrogen, alkyl group, or alkoxy-alkyl group; R<SP>3</SP>, R<SP>4</SP>, R<SP>9</SP>, R<SP>10</SP>express independently hydrogen, alkyl group or alkoxy-alkyl group; R<SP>5</SP>and R<SP>6</SP>, R<SP>7</SP>, R<SP>8</SP>express independently alkyl group or alkoxy-alkyl group. R<SP>1</SP>and R<SP>2</SP>, R<SP>3</SP>and R<SP>4</SP>, R<SP>5</SP>and R<SP>6</SP>, R<SP>7</SP>and R<SP>8</SP>, R<SP>9</SP>and R<SP>10</SP>each may form a ring structure integrally. l, m, m shows an integer of ≥1 and ≤15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel proton exchanger that functions even under non-humidified conditions, and more particularly to a proton exchanger that can be used in electrochemical devices such as batteries and electrolytes.

  A perfluorocarbon sulfonic acid membrane or the like is used as an electrolyte membrane of a conventional polymer solid electrolyte fuel cell (Patent Document 1). The perfluorocarbon sulfonic acid membrane has a drawback that it cannot be used in a dry state because water contained in the membrane becomes a proton conduction path (Non-patent Document 1). In order to improve proton conductivity in a dry state, various materials such as a silica-dispersed perfluorosulfonic acid membrane (Patent Literature 2), an inorganic-organic composite membrane (Patent Literature 3), a phosphoric acid doped graft membrane (Patent Literature 4), etc. Attempts have been made. However, in any of these methods, water in the membrane is essential to show proton conductivity, and it has not been an essential solution to the problem of proton conduction under non-humidified conditions.

  Therefore, development of a proton conductor that does not require water has been demanded, and the use of an ionic liquid has been proposed as an example. 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 for proton exchangers mainly used for fuel cells. For example, a proton exchange membrane using an aprotic ionic liquid composed of a nitrogen-containing quaternary salt such as a quaternary ammonium salt, quaternary pyridinium salt, or quaternary imidazolium salt and a polymer material having an ion exchange group (Patent Literature) 5-7), a proton exchange solution by using a protic ionic liquid composed of an imidazole compound, a membrane (Patent Document 8), and the like. However, the proton conductivity under non-humidified conditions shown in these examples is about 10 ⁻⁴ to 10 ⁻³ S / cm at the highest, and improvement is necessary for use as a non-humidified proton exchanger. there were. Proton exchange solutions and membranes using imidazole ionic liquids with hydrogen fluoride compounds as anions have been proposed as having high proton conductivity, but if this material is to be used, the handling of hydrogen fluoride Is expected to be a problem.

  Although these ionic liquids have been proposed that necessary characteristics can be expressed by combining ions according to the purpose as described above, they have not yet exhibited sufficient proton conductivity. However, most of them use quaternary imidazolium, alicyclic quaternary ammonium, quaternary alkylammonium, etc., and in order to dramatically improve proton conductivity, a breakthrough due to a new skeleton is required. Was needed.

  Therefore, as a result of searching for a new skeleton for an ion conductive material, the present inventors focused on a salt obtained from an aminosiloxane compound and a Bronsted acid. There was no report on the electrochemical use of salts obtained from aminosiloxane compounds and Bronsted acids, and the effect on proton conductivity was unknown.

JP-A-7-90111 Japanese Unexamined Patent Publication No. 6-11827 JP 2000-90946 A Japanese Patent Laid-Open No. 2001-213987 JP 2003-257484 A JP 2004-31307 A JP 2004-311212 A WO2003-083981 Publication Chem. & Eng. News, May 15, 2000 issue Functional creation and application of ionic liquids, NTS Corporation 2004

  An object of this invention is to provide the aminosiloxane type | system | group proton exchanger which has proton-conducting ability on non-humidified conditions.

  Therefore, as a result of intensive studies to solve such problems, the present inventors have found that a salt obtained from an aminosiloxane compound and a Bronsted acid has high proton conductivity, and reached the present invention. did.

（１）
（式中、Ｒ¹，Ｒ²，Ｒ¹¹，Ｒ¹²は独立に水素、アルキル基またはアルコキシアルキル基を示し、Ｒ³，Ｒ⁴，Ｒ⁹,Ｒ¹⁰は独立に水素、アルキル基またはアルコキシアルキル基を示し、Ｒ⁵〜Ｒ⁸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。Ｒ¹とＲ²、Ｒ³とＲ⁴、Ｒ⁵とＲ⁶、Ｒ⁷とＲ⁸、Ｒ⁹とＲ¹⁰、Ｒ¹¹とＲ¹²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は独立に１以上１５以下の整数を示す。）で表されるアミノシロキサン系化合物とブレンステッド酸から得られる塩を含有することを特徴とするプロトン交換体である。 The present invention provides the following formula (1)

(1)
(In the formula, R ¹ , R ² , R ¹¹ and R ¹² independently represent hydrogen, an alkyl group or an alkoxyalkyl group, and R ³ , R ⁴ , R ⁹ and R ¹⁰ independently represent hydrogen, an alkyl group or an alkoxyalkyl group. R ^{5 to} R ⁸ independently represent an alkyl group or an alkoxyalkyl group, R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , R ¹¹ and R ¹² may be combined to form a ring structure. L, m and n each independently represents an integer of 1 to 15, and an aminosiloxane compound represented by A proton exchanger characterized by containing a salt obtained from a Sted acid.

In the above formula (1), hydrogen is preferably exemplified as R ^{1 to} R ⁴ and R ^{9 to} R ¹² . Moreover, as R < ⁵ > -R < ⁸ >, an alkyl group is illustrated preferably, In this case, it is more preferable that all are the same alkyl groups.

  The proton exchanger can be composed of a salt obtained by reacting the aminosiloxane compound represented by the formula (1) with a Bronsted acid in an equivalent amount.

  In addition, the present invention is a proton exchange membrane obtained by forming the proton exchanger into a membrane shape. Furthermore, the present invention is a fuel cell comprising a solid polymer electrolyte membrane comprising the proton exchange membrane. The present invention also provides an electrolyte for an electrochemical cell using the proton exchanger as an electrolyte.

  The proton exchanger of the present invention is excellent in proton conductivity under non-humidified conditions, which has been difficult until now. Therefore, it is suitable for an electrochemical device material utilizing this characteristic, for example, a solid electrolyte of a fuel cell or an electrolyte in the battery field.

  The proton exchanger containing the aminosiloxane salt of the present invention is used as an electrolyte for electrochemical devices such as primary and secondary lithium ion batteries, dye-sensitized solar cells, electric double layer capacitors, electrolytic capacitors, and electrochromic display elements. Thus, 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.
The proton exchanger of the present invention contains an aminosiloxane compound represented by the above formula (1) and a salt obtained from Bronsted acid.

In the above formula (1), R ^{1 to} R ² , R ^{11 to} R ¹² and R ^{3 to} R ⁴ and R ^{9 to} R ¹⁰ each independently represent hydrogen, an alkyl group or an alkoxyalkyl group, and R ^{5 to} R ^8. Each independently represents an alkyl group or an alkoxyalkyl group. R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , and R ¹¹ and R ¹² together form a ring structure. Also good.

  Here, preferred examples of the alkyl group include C1-C12 alkyl groups. As the alkoxyalkyl group, a C1-C10 lower alkoxyalkyl group is preferable, 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 independently represent an integer of 1 to 15, but preferably l and n are integers of 1 to 5, and m is an integer of 7 to 10.

  The aminosiloxane compound may be synthesized by a known method, or a commercially available product may be used.

  The aminosiloxane compound represented by the above formula (1) is converted into a salt (hereinafter sometimes abbreviated as AS-B salt) by the action of Bronsted acid.

  As the Bronsted acid, either an organic Bronsted acid or an inorganic Bronsted acid can be used. Examples of the inorganic Bronsted acid include sulfuric acid, phosphoric acid, boric acid, and heteropolyacid. Organic Bronsted acids include carboxylic acids such as acetic acid, formic acid, and trifluoroacetic acid, alkyl sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, and octanesulfonic acid, trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, and perfluorooctane. Examples thereof include fluorine-containing sulfonic acids such as sulfonic acid, and fluorine-containing alkylsulfonic acid imides (referred to as imide acids) such as bis (trifluoromethanesulfonic acid) imide. Alkyl sulfonic acids, fluorine-containing alkyl sulfonic acids, alkyl carboxylic acids (RCOOH) or imide acids are preferred. Here, the alkyl preferably has 1 to 6 carbon atoms.

  The aminosiloxane compound represented by the formula (1) acts as a base, and an AS-B salt is obtained by a neutralization reaction with Bronsted acid. As a specific method thereof, a generally known acid-base neutralization reaction method can be used. Since 1 mol of the aminosiloxane compound represented by the formula (1) is calculated as 2 equivalents of base, 2 times mol of Bronsted acid is required to neutralize 1: 1. However, either can be used in excess. A preferable range in this case is 0.5 to 4 times mole of Bronsted acid with respect to 1 mole of aminosiloxane compound. A salt obtained by using 2 moles of Bronsted acid with respect to 1 mole of aminosiloxane compound has a high AS-B salt concentration, so that the performance of the proton exchanger is excellent. The above explanation is an example when the Bronsted acid is a monobasic acid. When the Bronsted acid is a dibasic acid or more, the amount used (mol) is calculated by simple calculation.

  The neutralization reaction method is obtained by reacting the aminosiloxane compound represented by the formula (1) and Bronsted acid by dissolving or mixing them in a solvent. For example, by reacting an aminosiloxane compound represented by the formula (2) with a 2-fold molar amount of bis (trifluoromethanesulfonic acid) imide as a Bronsted acid in methanol, the compound is represented by the formula (3). A salt can be obtained.

  Since the AS-B salt itself has proton exchange ability, it can be used as the proton exchanger of the present invention. Moreover, it can also be used as an active ingredient of a proton exchanger.

  The proton exchanger is used in liquid or solid form. When used in liquid form, when the AS-B salt becomes liquid at the use temperature, it may be used as it is, or may be used by blending other components. When the AS-B salt becomes a solid, it can be used by dissolving it in a suitable solvent. The solvent that can be used is a solvent having a boiling point equal to or higher than the use temperature of the AS-B salt, and is not particularly limited as long as the AS-B salt dissolves and does not inhibit proton conductivity. Alcohols represented by methanol, aromatic hydrocarbons represented by toluene, aliphatic hydrocarbons represented by hexane, dimethylformamide, dimethylacetamide, dimethylimidazolidinone, N-methylpyrrolidone, dimethylsulfoxide Examples thereof include aprotic polar solvents represented by

  When the proton exchanger is used in a solid state, it may be used as it is when the AS-B salt becomes a solid at the use temperature. For example, it can be used as a solid electrolyte without a solvent.

  The proton exchange material of the present invention can also be obtained by combining a gelling material comprising a polymer compound and an AS-B salt. In this case, it can also be used as a polymer gel electrolyte. As a production method thereof, a polymer compound exemplified below and an AS-B salt are mixed and dissolved by heating and cooling, or after mixing and molding both in an appropriate organic solvent, a method such as drying under reduced pressure. Obtained by distilling off the solvent. The polymer compound is not limited as long as it can solidify the AS-B salt, but polyvinyl polymer compounds such as polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, and polyvinylidene fluoride, polyoxymethylene, poly Examples include polyether polymer compounds such as ethylene oxide and polypropylene oxide, polyamide compounds such as nylon 6 and nylon 66, polyester compounds such as polyethylene terephthalate, and polycarbonate compounds. Furthermore, it is also possible to make a composite by crosslinking these polymerizable precursors, for example, a polymerizable compound such as acrylate. It is also possible to obtain a polymer compound complex by polymerizing monomers in an AS-B salt-containing solution. If the proton exchanger thus obtained is formed into a membrane, a proton exchange membrane can be obtained.

  As an example of use of the proton exchanger of the present invention, it can be used for various electronic devices that require high proton conductivity. For example, when used in liquid form, the high ion of a lithium primary battery or a secondary battery. It can be used as a conductive non-aqueous organic electrolyte. When used in a solid state, it can be used as a proton exchange membrane sandwiched between a cathode and an anode of a fuel cell or the like.

Hereinafter, the present invention will be described in more detail with reference to examples.
The proton conductivity in the examples was measured by the AC impedance method.

Example 1
2.3 g (9.26 mmol) of 1,3-bis (3-aminopropyl) tetramethyldisiloxane and 0.85 g (18.52 mmol) of formic acid were dissolved in 9 ml of methanol and stirred under ice cooling. After 30 minutes, the reaction solution was distilled off under reduced pressure, and then dried under reduced pressure at room temperature to obtain 3.15 g of formate of 1,3-bis (3-aminopropyl) tetramethyldisiloxane (melting point: 61 ° C. ). A 1M (mol / L) ethylene glycol solution of the obtained salt was prepared, and proton conductivity was measured. The results are shown in Table 1.

Example 2
A solution in which 4.26 g (5.56 mmol) of the aminosiloxane compound represented by the formula (2) is dissolved in 50 ml of dichloromethane, and then 3.12 g (11.1 mmol) of bis (trifluoromethanesulfonic acid) imide is dissolved in 30 ml of dichloromethane. Was dripped. After 30 minutes, the solvent was distilled off under reduced pressure and further dried under reduced pressure to obtain 7.38 g of a bis (trifluoromethanesulfonic acid) imide salt of an aminosiloxane compound represented by the formula (2) as a yellow clear liquid. The results of measuring the proton conductivity of the obtained salt are shown in Table 2.

Example 3
After dissolving 2.13 g (2.78 mmol) of the aminosiloxane compound represented by the formula (2) in 7 ml of methanol, 0.68 g (5.57 mmol) of benzoic acid was added. After 30 minutes, the solvent was distilled off under reduced pressure, and further dried under reduced pressure to obtain 3.15 g of a benzoate of an aminosiloxane compound represented by the formula (2) as a colorless clear liquid. A 1M ethylene glycol solution of the obtained salt was prepared, and the proton conductivity at 40 ° C. was measured. As a result, it was 1.1 mS / cm.

Example 4
In Example 3, except that methanesulfonic acid was used in place of benzoic acid, the same operation as in Example 3 was performed to obtain an aminosiloxane compound methanesulfonate as a colorless and clear liquid. A 1M ethylene glycol solution of the obtained salt was prepared and measured for proton conductivity at 40 ° C. and found to be 2.2 mS / cm.

Example 5
In Example 3, except that formic acid was used instead of benzoic acid, the same operation as in Example 3 was performed to obtain an aminosiloxane compound formate as a colorless clear liquid. A 1M ethylene glycol solution of the obtained salt was prepared, and the proton conductivity at 40 ° C. was measured. As a result, it was 2.5 mS / cm.

Example 6
As shown in FIG. 1, the bismuth of the aminosiloxane compound obtained in Example 2 was placed in a U-shaped glass cell in which platinum electrodes 1 and 2 were disposed at both ends and a gas bubbling tube 3 was disposed on the platinum electrode 1 side. (Trifluoromethanesulfonic acid) imide salt was added. A direct current power source was connected so that the electrode 1 was a positive electrode and the electrode 2 was a negative electrode, and nitrogen gas or hydrogen was circulated from the gas bubbling tube 3 to conduct an energization test. The results of the energization test are shown in FIG.

  When nitrogen was circulated through the gas bubbling pipe 3, almost no current flowed as shown in FIG. 2, but when hydrogen was circulated, a current flowed according to the voltage. That is, it is considered that the proton generated at the electrode 1 becomes hydrogen at the electrode 2 under the flow of hydrogen. From this, it was confirmed that the AS-B salt as the proton exchanger of the present invention functions as a proton conductor.

Schematic diagram of an apparatus for evaluating the performance of proton exchangers Diagram showing the relationship between voltage and current when hydrogen or nitrogen gas is passed

Explanation of symbols

  1: platinum electrode, 2: platinum electrode, 3: gas bubbling tube

Claims (7)

Following formula (1)

(In the formula, R ¹ , R ² , R ¹¹ and R ¹² independently represent hydrogen, an alkyl group or an alkoxyalkyl group, and R ³ , R ⁴ , R ⁹ and R ¹⁰ independently represent hydrogen, an alkyl group or an alkoxyalkyl group. R ^{5 to} R ⁸ independently represent an alkyl group or an alkoxyalkyl group, R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , R ¹¹ and R ¹² may be combined to form a ring structure. L, m and n each independently represents an integer of 1 to 15, and an aminosiloxane compound represented by A proton exchanger comprising a salt obtained from a Sted acid. 2. The proton exchanger according to claim 1, wherein in formula (1), R ^{1 to} R ⁴ and R ^{9 to} R ¹² are hydrogen, and R ^{5 to} R ⁸ are the same kind of alkyl group.   The proton exchanger according to claim 1 or 2, comprising a salt obtained by reacting the aminosiloxane compound represented by the formula (1) with a Brönsted acid in an equivalent amount.   The salt obtained from the aminosiloxane compound represented by the formula (1) and the Bronsted acid is retained in the gelling material composed of the polymer compound. The proton exchanger as described.   A proton exchange membrane, wherein the proton exchanger according to claim 4 is formed into a membrane.   A fuel cell comprising a solid polymer electrolyte membrane comprising the proton exchange membrane according to claim 5.   An electrochemical cell using the proton exchanger according to claim 1 as an electrolyte.

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