JP5245269B2 - Composite electrolyte and polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a composite electrolyte and a polymer electrolyte fuel cell, and more particularly, to a polymer electrolyte fuel cell, a water electrolysis device, a hydrohalic acid electrolysis device, a salt electrolysis device, an oxygen and / or hydrogen concentrator, a humidity. The present invention relates to a composite electrolyte suitable as an electrolyte membrane and electrode material used in various electrochemical devices such as sensors and gas sensors, and a polymer electrolyte fuel cell using the same.

  The solid polymer electrolyte is a solid polymer material having an acid group such as a sulfonic acid group in a polymer chain. Since the solid polymer electrolyte has a property of binding firmly to specific ions or selectively permeating cations or anions, it is formed into particles, fibers, or membranes, electrodialysis, It is used for various applications such as diffusion dialysis and battery diaphragm.

  For example, in various electrochemical devices such as solid polymer fuel cells and water electrolysis devices, the solid polymer electrolyte is used in the form of a membrane electrode assembly (MEA) in which a membrane is formed and electrodes are bonded to both sides thereof. Is done. In the polymer electrolyte fuel cell, the electrode generally has a two-layer structure of a diffusion layer and a catalyst layer. The diffusion layer is for supplying reaction gas and electrons to the catalyst layer, and carbon fiber, carbon paper, or the like is used. The catalyst layer is a part that becomes a reaction field for electrode reaction, and generally comprises a composite of carbon carrying a catalyst such as platinum and a solid polymer electrolyte.

  Conventionally, various materials are known as solid polymer electrolytes used for such applications. For example, the electrolyte membrane used in an electrochemical device used under severe conditions and the electrolyte in the catalyst layer include a perfluorinated electrolyte membrane excellent in oxidation resistance (for example, Nafion (registered trademark, manufactured by DuPont), It is common to use Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd., etc.). In order to reduce the cost of electrochemical devices, use of hydrocarbon electrolytes such as sulfonated polyetheretherketone and sulfonated polyethersulfone is also being studied.

  An improvement guideline for improving the performance of these electrolyte membranes used in fuel cells is to increase the proton conductivity of the electrolyte. For this purpose, it is a general method to increase the amount of sulfonic acid groups in the membrane. However, a simple increase in sulfonic acid groups results in an increase in hydrophilicity. As a result, there is an adverse effect that the durability of the battery is lowered, such as swelling of the electrolyte membrane due to water content, and the membrane becoming water-soluble.

  As one of the measures for suppressing swelling and water solubility, mixing with a basic polymer is known. This is intended to suppress swelling by crosslinking an acid group such as a sulfonic acid group in an electrolyte with a basic polymer. For example, Non-Patent Document 1 discloses a mixture of sulfonated polyether ether ketone and polybenzimidazole (basic polymer).

K.D.kreuer, Journal of Membrane Science 185 (2001) 29-39

  However, the electrolyte obtained by mixing sulfonated polyetheretherketone and polybenzimidazole has a hydrophilic cross-linking point, so in order to obtain a sufficient cross-linking effect, a large amount of basic polymer is combined. There is a need to. On the other hand, as the content of the basic polymer increases, a sulfonic acid group responsible for proton conduction is used for cross-linking, so that there is a problem that proton conductivity of the electrolyte membrane decreases.

  The problem to be solved by the present invention is to provide a composite electrolyte that achieves both high electrical conductivity, water resistance and swelling resistance, and a polymer electrolyte fuel cell using the same.

In order to solve the above problems, the first of the composite electrolyte according to the present invention is:
An electrolyte polymer having an acid group;
A crosslinking agent molecule having any two or more functional groups of a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group,
The gist is that a cationic group formed by dissociation of the functional group and an anion group formed by dissociation of the acid group form a hydrophobic acid / base bridge.
The second of the composite electrolyte according to the present invention is
An electrolyte polymer having an acid group and one or more functional groups of a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group in the molecule;
Between the electrolyte polymer molecules or within the electrolyte polymer molecule, a cationic group formed by dissociation of the functional group and an anion group formed by dissociation of the acid group form a hydrophobic acid / base bridge. The gist.
The solid polymer fuel cell according to the present invention is summarized in that the composite electrolyte according to the present invention is used for an electrolyte membrane and / or an electrolyte in a catalyst layer.

  When an acid group of an electrolyte polymer is reacted with a crosslinker molecule or a quaternary onium group or a nitrogen-containing heterocyclic alkyl cation group of the electrolyte polymer to form an acid / base bridge in the composite electrolyte, a relatively high electrical conductivity is obtained. Water resistance and swelling resistance can be improved while maintaining the above. This is because the steric hindrance of the quaternary onium group or the nitrogen-containing heterocyclic alkyl cation group is large and the water molecule is difficult to approach the cross-linking point (that is, the cross-linking point becomes hydrophobic). This is considered to be suppressed.

Hereinafter, an embodiment of the present invention will be described in detail.
The composite electrolyte according to the first embodiment of the present invention includes an electrolyte polymer and a crosslinking agent molecule.

[1. Electrolyte polymer]
In the present invention, the electrolyte polymer is not particularly limited, and may be either a fluorocarbon electrolyte or a hydrocarbon electrolyte.
Here, the “fluorocarbon electrolyte” refers to a perfluorinated electrolyte or a partially fluorinated electrolyte.
“Fully fluorinated electrolyte” means a polymer skeleton containing a C—F bond and no C—H bond. In the present invention, the term “perfluorinated electrolyte” refers to a structure other than the C—F bond (for example, —O—, —S—, —C (═O) —, —N (R) in the polymer skeleton. -Etc., provided that "R" is an alkyl group.)
The “partial fluorine-based electrolyte” refers to a polymer skeleton containing both C—F bonds and C—H bonds.
“Hydrocarbon-based electrolyte” means a polymer skeleton containing a C—H bond and no C—F bond.
The composite electrolyte according to the present invention may contain only one of these electrolyte polymers, or may contain two or more of them.

Among these, the electrolyte polymer is
(A) perfluorinated electrolyte polymer,
(B) the main chain imide _{(- [(CF 2) m} - (SO 2 NH) n -SO 2] X -, m = 0~20, n = 1~20, X = 2 or more),
(C) A polymer having at least one of an aromatic ring and a heterocyclic ring, wherein a protonic acid group is bonded to at least one of the aromatic ring and the heterocyclic ring, or
(D) a vinyl polymer containing a protonic acid group introduced into any one or more of the vinyl polymers;
Is preferred.

As an electrolyte polymer that may have an aromatic ring and / or a heterocyclic ring,
(1) Polyarylene polymers (eg, polyether, polyketone, polysulfone, polyethersulfone, polyetherethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfoxide, polyether ketone ketone, A polyamide system, a polyimide system, a polyamideimide system), and a protonic acid group bonded to any one or more of an aromatic ring and a heterocyclic ring included in the polymer,
(2) Including a polyazole-based polymer (for example, polybenzimidazole-based, polybenzothiazole-based, polybenzoxazole-based), and a protonic acid group is bonded to at least one of an aromatic ring and a heterocyclic ring included in the polymer. What
Is mentioned.
Examples of the proton acid group include sulfonic acid, phosphonic acid, and carboxylic acid, and among these, sulfonic acid is most preferable.

  Specifically, the electrolyte polymer containing a polymer (polyarylene polymer) containing a repeating structural unit having a polyarylene structure is preferably represented by the formula (1).

In the formula (1), X ₁ , X ₂ , and X ₃ are each composed of a single bond, a phenyl group, a naphthyl group, an anthracenyl group, a phenanthyl group, and the like. Of these groups, a phenyl group and a naphthyl group are preferable. In addition, a protonic acid group is bonded to one or more of X ₁ , X ₂ , and X ₃ included in 20 to 100% of the entire polymer unit.
A, B and C each represent a divalent single bond or an organic group. Specifically, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) —, —C (CF ₂ ) ₂ —, — (CH ₂ ) —, — C (CH ₂ ) ₂ —, —O—, —S—, —CH═CH—, —C≡C— and the like can be mentioned.
n shows the integer of 10-10000.

  Specifically, the electrolyte polymer containing a polymer containing a repeating structural unit having a polyazole structure (polyazole polymer) is preferably represented by the formula (2).

In formula (2), X ₄ represents any of O, S, and N atoms. X ₅ represents a single bond, a phenyl group, a naphthyl group, an anthracenyl group, or a phenanthyl group. Further, the aromatic ring and / or heterocyclic ring X ₅ or in benzazole group contained 20 to 100% of the units of the total polymer units, protonic acid group is bonded.

Moreover, as an electrolyte polymer containing a vinyl-type polymer, what contains the structure shown to following (3) Formula is preferable.
-(CX ₁ X ₂ -CX ₃ X ₄ ) _n- (3)
However, X ₁ , X ₂ , and X ₄ are each H or R
R represents — (CH ₂ ) _m —CH ₃ , m = 0 to 20
X3 _{is, - (CH 2) a -SO} 3 H,
_{- (CH 2) a -CO- (} CH 2) b -SO 3 H,
_{- (CH 2) a -CONH- (} CH 2) b -SO 3 H,
_{- (CH 2) a -S- (} CH 2) b -SO 3 H,
_{- (CH 2) a -SO 2} - (CH 2) b -SO 3 H, or,
_{- (CH 2) a -O- (} CH 2) b -SO 3 H
a = 0-20, b = 0-20

The amount of acid groups in the electrolyte polymer is not particularly limited. In general, the greater the amount of acid groups, the higher the electrical conductivity, but it tends to dissolve or swell in water. In particular, when the electrolyte polymer alone is dissolved or greatly swollen in water (room temperature to 100 ° C.), a high effect can be obtained by applying the present invention.
Specifically, the ion exchange capacity of the electrolyte polymer alone is preferably 1.0 mmol acid group equivalent / g or more, and more preferably 2.0 mmol acid group equivalent / g or more.
In addition, the swelling ratio of the electrolyte polymer alone is often 30% or more. Here, the “swelling ratio of the electrolyte polymer alone” refers to the rate of increase in the membrane size when water is contained (after standing overnight in room temperature water) with respect to the membrane size during drying of the electrolyte polymer alone.
The molecular weight of the electrolyte polymer is not particularly limited, but is preferably 10,000 or more from the viewpoint of strength.

[2. Crosslinker molecule]
The crosslinking agent molecule refers to a compound having any two or more functional groups of a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group. The cation group formed by dissociation of the quaternary onium group or the nitrogen-containing heterocyclic alkyl cation group forms a hydrophobic acid / base bridge with the anion group formed by dissociation of the acid group contained in the electrolyte polymer.
Here, the “onium group” refers to a functional group composed of a cation salt having a bond larger than the reference number of bonds. The reference number of bonds refers to a value obtained by setting a reference value for some elements of the number of bonds. For example, 1 for F, Cl, Br, I, At, 2 for O, S, Se, Te, Po, 3 for N, P, As, Sb, Bi, B, 3 for C, Si, Ge, Sn, Pb 4. Specific examples of the quaternary onium group include a quaternary ammonium group and a quaternary phosphonium group. Among these, a quaternary ammonium group is particularly suitable as a quaternary onium group for forming a crosslinking point.

Examples of the quaternary onium group include a tetraalkylammonium group.
Examples of the quaternary phosphonium group include a tetraalkylphosphonium group.
Examples of nitrogen-containing heterocyclic alkyl cation groups include alkylimidazolium groups, alkylpyridinium groups, alkylpyridazinium groups, alkylpyrimidinium groups, alkylpyrazinium groups, alkylquinolinium groups, and nitrogen-containing heterocyclic compounds. Grade nitrogenated products.

  The crosslinking agent molecule may contain any one of the quaternary onium groups or nitrogen-containing heterocyclic alkyl cation groups described above, or may contain two or more kinds. In addition, one or two or more quaternary onium groups or one compound containing a nitrogen-containing heterocyclic alkyl cation group may be used for the cross-linking agent molecule, or one or two or more quaternary molecules may be used. Two or more compounds containing an onium group or a nitrogen-containing heterocyclic alkyl cation group may be used in combination.

  The molecular structure of the portion other than the functional group such as the quaternary onium group of the crosslinking agent molecule and the binding site of the functional group such as the quaternary onium group are not particularly limited. For example, a functional group such as a quaternary onium group may be bonded to the terminal of the main chain having a hydrocarbon structure or a fluorocarbon structure, or a quaternary onium group is provided in the middle of the main chain having a hydrocarbon structure or a fluorocarbon structure. Or a functional group such as Furthermore, a functional group such as a quaternary onium group may be bonded to the middle or terminal of the side chain having a hydrocarbon structure or a fluorocarbon structure.

Specifically, as the crosslinking agent molecule,
(1) Poly (alkylene) -trialkylammonium chloride terminal (formula (a)),
(2) poly (N, N-dialkyl-benzimidazolium) (formula (b)),
(3) polyvinyl (1-alkyl-pyridinium) (formula (c)),
(4) polydiallyldimethylammonium chloride (form (d)),
and so on.

[3. Addition amount of crosslinking agent molecule]
The addition amount of the cross-linking agent molecule is selected in accordance with the type of electrolyte polymer and cross-linking agent molecule, the required characteristics, and the like. In general, the greater the amount of crosslinker molecule added, the greater the number of crosslinking points and the better the water resistance and swelling resistance. In order to obtain relatively high water resistance and swelling resistance, the addition amount of the crosslinking agent molecule corresponds to 0.01% of the acid group amount of the quaternary onium group or the nitrogen-containing heterocyclic alkyl cation group. More than the amount is preferred.
On the other hand, when the addition amount of the crosslinking agent molecule becomes excessive, the acid group of the electrolyte polymer is consumed for the crosslinking reaction, and the electrical conductivity is lowered. In order to obtain high electric conductivity, the amount of the crosslinking agent molecule added is preferably not more than the amount corresponding to 80% of the acid group amount of the quaternary onium group or the nitrogen-containing heterocyclic alkyl cation group.

Next, the composite electrolyte according to the second embodiment of the present invention will be described.
The composite electrolyte according to the present embodiment is
An electrolyte polymer having an acid group and one or more functional groups of a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group in the molecule;
Between the electrolyte polymer molecules or within the electrolyte polymer molecule, a cationic group formed by dissociation of the functional group and an anion group formed by dissociation of the acid group form a hydrophobic acid / base bridge. Features.
That is, the cation group and the anion group form an acid / base bridge between polymer chains or within the same polymer chain without using a crosslinking agent molecule. This point is different from the first embodiment.
The amount of quaternary onium group and nitrogen-containing heterocyclic alkyl cation group introduced into the molecule is in accordance with the amount of crosslinking agent molecule added in the first embodiment. The other points regarding the electrolyte polymer, quaternary onium group, nitrogen-containing heterocyclic alkyl cation group, and acid / base crosslinking are the same as those in the first embodiment, and thus the description thereof is omitted.

Next, the polymer electrolyte fuel cell according to the present invention will be described.
A polymer electrolyte fuel cell includes a membrane electrode assembly (MEA) in which electrodes are bonded to both surfaces of a solid polymer electrolyte membrane. In addition, the polymer electrolyte fuel cell is usually formed by sandwiching both sides of such an MEA with a separator having a gas flow path and laminating a plurality of them.

  The electrode constituting the MEA usually has a two-layer structure of a catalyst layer and a diffusion layer, but may be constituted only by the catalyst layer. When the electrode has a two-layer structure of a catalyst layer and a diffusion layer, the electrode is joined to the electrolyte membrane via the catalyst layer.

  The catalyst layer is a part serving as a reaction field for the electrode reaction, and includes an electrode catalyst or a carrier carrying the electrode catalyst, and an electrolyte in the catalyst layer covering the periphery thereof. In general, an optimum electrode catalyst is used depending on the purpose of use of MEA, use conditions, and the like. In the case of a polymer electrolyte fuel cell, the electrode catalyst includes platinum, palladium, ruthenium, rhodium, iridium or the like, or an alloy containing one or more of these, or a platinum group element such as platinum, cobalt, iron An alloy with a transition metal element such as nickel is used. As the amount of the electrode catalyst contained in the catalyst layer, an optimal amount is selected according to the use of MEA, use conditions, and the like.

  The catalyst carrier is for carrying a fine electrode catalyst and simultaneously transferring electrons in the catalyst layer. Generally, carbon, activated carbon, fullerene, carbon nanophone, carbon nanotube or the like is used as the catalyst carrier. As the amount of the electrode catalyst supported on the surface of the catalyst carrier, an optimum amount is selected according to the material of the electrode catalyst and the catalyst carrier, the use of the MEA, the use conditions, and the like.

  The electrolyte in the catalyst layer is for exchanging protons between the solid polymer electrolyte membrane and the electrode. For the electrolyte in the catalyst layer, the same material as that constituting the solid polymer electrolyte membrane is usually used, but a different material may be used. As the amount of the electrolyte in the catalyst layer, an optimal amount is selected according to the use of MEA, use conditions, and the like.

  The diffusion layer is for supplying and receiving a reaction gas to the catalyst layer at the same time as transferring electrons to and from the catalyst layer. Generally, carbon paper, carbon cloth, or the like is used for the diffusion layer. In order to increase water repellency, a surface of carbon paper or the like coated with a mixture of water repellent polymer powder such as polytetrafluoroethylene and carbon powder (water repellent layer) is used as a diffusion layer. Also good.

The polymer electrolyte fuel cell according to the present invention is characterized in that the composite electrolyte according to the present invention is used as the electrolyte membrane and / or the catalyst layer electrolyte constituting the MEA described above.
When the composite electrolyte according to the present invention is used for the electrolyte membrane, the electrolyte membrane may be composed only of the composite electrolyte, or a composite electrolyte and a reinforcing material composed of a porous material, a long fiber material, a short fiber material, or the like. It may be a composite.

Next, a method for producing a composite electrolyte according to the present invention will be described.
First, the acid group of the electrolyte polymer having an acid group is inactivated. As a method for inactivating the acid group, there is a method in which a polymer having an acid group is dissolved in a suitable solvent, and aqueous ammonia is added thereto to react the acid group with ammonia.

Next, a crosslinking agent molecule is added to the solution in which the electrolyte polymer in which the acid groups have been deactivated is dissolved. At this point, since the acid group is inactivated, the acid group does not react with a functional group such as a quaternary onium group. Therefore, the electrolyte polymer and the crosslinking agent molecule can be mixed uniformly.
After preparing a uniform solution of the electrolyte polymer and the crosslinking agent molecule, this is applied to a suitable substrate (for example, a polytetrafluoroethylene sheet) and the solvent is volatilized to obtain an electrolyte membrane. Moreover, after adding an electrode catalyst further to a uniform solution, this is apply | coated to a suitable board | substrate and a solvent is volatilized, A catalyst sheet will be obtained.

Next, after the mixture of the electrolyte polymer and the cross-linking agent molecule is formed into a film or a catalyst sheet, or these are joined to form an MEA, the film, the catalyst sheet, or the MEA is converted into an acid solution (for example, an aqueous hydrochloric acid solution or an aqueous sulfuric acid solution). Soak in an aqueous nitric acid solution). As a result, the deactivated acid group returns to the original acid group, and at the same time, the anion having the acid group dissociated reacts with the cation having the dissociated cross-linking agent to form a hydrophobic acid / base bridge in the electrolyte. Is done.
If excess acid is removed by washing with water after the formation of the crosslink, an electrolyte membrane, a catalyst sheet or MEA containing the composite electrolyte according to the present invention is obtained. Furthermore, if both sides of the obtained MEA are sandwiched between separators having gas flow paths and a predetermined number of them are stacked, the polymer electrolyte fuel cell according to the present invention can be obtained.

In addition to acid groups in the molecule, an electrolyte polymer having one or more functional groups of a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group includes, for example, vinylphosphonic acid and vinyl (1-ethyl) pyridine. And can be produced by copolymerization. Moreover, inactivation of the acid group of such an electrolyte polymer can be performed with aqueous ammonia as described above.
After deactivating the acid group, an electrolyte membrane or a catalyst sheet is prepared according to the same procedure as described above, except that no crosslinking agent molecule is added. Further, when the obtained membrane, catalyst sheet, or MEA is immersed in an acid solution (for example, an aqueous hydrochloric acid solution, an aqueous sulfuric acid solution, an aqueous nitric acid solution, etc.), a hydrophobic acid / base bridge is formed in the electrolyte.
If excess acid is removed by washing with water after the formation of the crosslink, an electrolyte membrane, a catalyst sheet or MEA containing the composite electrolyte according to the present invention is obtained. Furthermore, if both sides of the obtained MEA are sandwiched between separators having gas flow paths and a predetermined number of them are stacked, the polymer electrolyte fuel cell according to the present invention can be obtained.

Next, the operation of the composite electrolyte and the polymer electrolyte fuel cell according to the present invention will be described.
For example, a basic polymer having an imidazole group such as polybenzimidazole and an electrolyte polymer such as sulfonated polyetheretherketone are mixed and reacted to obtain an electrolyte polymer crosslinked with polybenzimidazole. It is done. However, the electrolyte polymer obtained by this method requires a relatively large amount of basic polymer in order to obtain relatively high water resistance and swelling resistance. This is considered to be because the steric hindrance at the crosslinking point is small and water molecules are easy to approach the crosslinking point (that is, the hydrophilicity of the crosslinking point is high), so that the crosslinking point is easily dissociated by humidified water or generated water. .

On the other hand, by using a cross-linking agent molecule having a quaternary onium group or a nitrogen-containing heterocyclic alkyl cation group, an acid / ion in the composite electrolyte is formed from an anion in which the acid group of the electrolyte polymer is dissociated and a cation in which the cross-linking agent molecule is dissociated. By forming a base bridge, water resistance and swelling resistance can be improved while maintaining a relatively high electrical conductivity. This is presumably because the steric hindrance around the cation group is large, and water molecules are difficult to approach the cross-linking point (that is, the cross-linking point becomes hydrophobic), so that dissociation of the cross-linking point by water is suppressed. This is the same when a composite electrolyte is formed using only an electrolyte polymer having an acid group and a quaternary onium group and / or a nitrogen-containing heterocyclic alkyl cation group in the same molecule.
Therefore, compared with the conventional method, insoluble and swelling suppression effects can be imparted to an electrolyte polymer having a large ion exchange capacity with a relatively small amount of addition of a crosslinking agent. In addition, since the amount of acid groups consumed for obtaining high water resistance and swelling resistance can be relatively reduced, a higher electrical conductivity can be obtained as compared with conventional methods.

(Examples 1-9, Comparative Examples 1-9)
[1. Preparation of electrolyte membrane]
[1.1. When poly (N, N-diethylbenzimidazolium) chloride is used as a crosslinking agent (Examples 1 to 3)]
0.588 g of water-soluble sulfonated polyetheretherketone (hereinafter referred to as “S-PEEK”; EW = 370) was weighed, dissolved and stirred in 10 mL of dimethylacetamide. To this solution, 10% aqueous ammonia was added so as to be equimolar with the amount of the sulfonic acid group in the above solution, followed by stirring for 2 hours.
Next, a DMAc solution of 10 wt% poly (N, N-diethyl-benzimidazolium) chloride was prepared by adding 10% (Example 1), 5% Example 2) or 1% (Example 3) was added, stirred overnight, and then cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove ammonia and DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[1.2. When polyvinyl (N-ethyl-pyridinium) chloride is used as a crosslinking agent (Examples 4 to 6)]
0.588 g of water-soluble S-PEEK (EW = 370) was weighed and dissolved and stirred in 10 mL of dimethylacetamide. To this solution, 10% aqueous ammonia was added so as to be equimolar with the amount of the sulfonic acid group in the above solution, followed by stirring for 2 hours.
Next, a DMAc solution of 10 wt% polyvinyl (N-ethyl-pyridinium) chloride was used with a pyridinium group amount of 10% (Example 4) and 5% (Example 5) based on sulfonic acid groups in S-PEEK. Alternatively, the mixture was added to 1% (Example 6), stirred overnight, and then cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove ammonia and DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[1.3. When polydiallyldimethylammonium chloride is used as a crosslinking agent (Examples 7 to 9)]
0.588 g of water-soluble S-PEEK (EW = 370) was weighed and dissolved and stirred in 10 mL of dimethylacetamide. To this solution, 10% aqueous ammonia was added so as to be equimolar with the amount of the sulfonic acid group in the above solution, followed by stirring for 2 hours.
Next, a 10 wt% polydiallyldimethylammonium chloride DMAc solution was prepared with an ammonium group content of 10% (Example 7), 5% (Example 8), or 1% based on sulfonic acid groups in S-PEEK ( Example 9) was put, and after stirring overnight, it was cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove ammonia and DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[1.4. When no crosslinking agent (Comparative Example 1)]
0.588 g of water-soluble S-PEEK (EW = 370) was weighed and dissolved and stirred in 10 mL of dimethylacetamide. This solution was stirred overnight and then cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[1.5. When polybenzimidazole is used as a crosslinking agent (Comparative Examples 2 to 4)]
0.588 g of water-soluble S-PEEK (EW = 370) was weighed and dissolved and stirred in 10 mL of dimethylacetamide. To this solution, 10% aqueous ammonia was added so as to be equimolar with the amount of the sulfonic acid group in the above solution, followed by stirring for 2 hours.
Next, a 10 wt% polybenzimidazole DMAc solution was prepared with an imidazole group content of 10% (Comparative Example 2), 5% (Comparative Example 3), or 1% (Comparative Example) with respect to the sulfonic acid group in S-PEEK. 4) After stirring overnight, the mixture was cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove ammonia and DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[1.6. When polyvinyl pyridine is used as a crosslinking agent (Comparative Examples 5 to 7)]
0.588 g of water-soluble S-PEEK (EW = 370) was weighed and dissolved and stirred in 10 mL of dimethylacetamide. To this solution, 10% aqueous ammonia was added so as to be equimolar with the amount of the sulfonic acid group in the above solution, followed by stirring for 2 hours.
Next, a DMAc solution of 10 wt% polyvinyl pyridine was used in which the amount of pyridine groups was 10% (Comparative Example 5), 5% (Comparative Example 6), or 1% (Comparative Example 7) with respect to the sulfonic acid group in S-PEEK. ) And stirred overnight, then cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove ammonia and DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[1.7. When polydiallylamine is used as a crosslinking agent (Comparative Examples 8 to 10)]
0.588 g of water-soluble S-PEEK (EW = 370) was weighed and dissolved and stirred in 10 mL of dimethylacetamide. To this solution, 10% aqueous ammonia was added so as to be equimolar with the amount of the sulfonic acid group in the above solution, followed by stirring for 2 hours.
Next, a DMAc solution of 10 wt% polyvinyl pyridine was used with an amino group content of 10% (Comparative Example 8), 5% (Comparative Example 9), or 1% (Comparative Example 10) with respect to the sulfonic acid group in S-PEEK. ) And stirred overnight, then cast into a flat petri dish. After leaving in a draft for 1 week, it was vacuum dried at 140 ° C. for 2 hours, and the film was peeled off from the petri dish.
This film was washed in 1N hydrochloric acid (2 hours × 5 times) to remove ammonia and DMAc remaining in the film. Thereafter, the film was washed with water (2 hours × 5 times) to remove the remaining hydrochloric acid. This film was dried at 60 ° C. overnight to obtain the desired film.

[2. Test method]
The obtained film was measured for hot water resistance, water swelling ratio, and electrical conductivity. The hot water test was performed by immersing the film in boiling water for 1 hour, and it was visually confirmed whether or not the film was dissolved. Moreover, the water swelling rate was calculated | required as a rate of change of the length of the film | membrane after being immersed in the film of an absolutely dry state and room temperature water overnight. Furthermore, the electrical conductivity was measured by the AC four-terminal method (in water, 25 ° C.).

[3. result]
Table 1 shows the results. Since the film (Comparative Example 1) consisting only of S-PEEK has a large ion exchange capacity (small EW), the electrical conductivity is high. However, the water swelling rate was large, and it was completely dissolved in the hot water test.
On the other hand, the case where polybenzimidazole is used as a crosslinking agent (Comparative Examples 2 to 4), the case where polyvinylpyridine is used (Comparative Examples 5 to 7), and the case where polydiallylamine is used (Comparative Examples 8 to 10) are used. In all cases, when the addition amount was 5% or more, the film became insoluble in hot water. Moreover, the electrical conductivity decreased as the amount of the crosslinking agent added increased, but the water swelling rate decreased. However, when the addition amount was 1%, all dissolved.

On the other hand, when poly (N, N-diethyl-benzimidazolium) chloride is used as a crosslinking agent (Examples 1 to 3), when polyvinyl (N-ethyl-pyridinium) chloride is used (Examples 4 to 4). In both cases of 6) and polydiallyldimethylammonium chloride (Examples 7 to 8), the film became insoluble in hot water. Further, by adding a cross-linking agent equivalent to 10% with respect to the amount of sulfonic acid group, an electric conductivity equal to or higher than that of Comparative Examples 2, 5, and 8 and a water swelling ratio of about 1/2 were obtained. Furthermore, even if the amount of the crosslinking agent added was 1%, the film was insoluble in hot water.
From Table 1, when a crosslinker molecule having two or more quaternary onium groups or nitrogen-containing heterocyclic alkyl cation groups is used, it is possible to maintain high electrical conductivity and to improve hot water resistance and swelling resistance. Recognize.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

The composite electrolyte according to the present invention is used in various electrochemical devices such as a polymer electrolyte fuel cell, a water electrolysis apparatus, a hydrohalic acid electrolysis apparatus, a salt electrolysis apparatus, an oxygen and / or hydrogen concentrator, a humidity sensor, and a gas sensor. It can be used as an electrolyte membrane, an electrode material, and the like.
Moreover, the polymer electrolyte fuel cell according to the present invention can be used for an in-vehicle power source, a stationary small power generator, a cogeneration system, and the like.

Claims (7)

An electrolyte polymer having an acid group;
A crosslinking agent molecule having any two or more functional groups of a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group,
A composite electrolyte in which a cationic group generated by dissociation of the functional group and an anion group generated by dissociation of the acid group form a hydrophobic acid / base bridge. An electrolyte polymer having one or more functional groups of an acid group, a quaternary onium group and a nitrogen-containing heterocyclic alkyl cation group in the molecule;
A composite electrolyte in which a cationic group formed by dissociation of the functional group and an anion group formed by dissociation of the acid group form a hydrophobic acid / base bridge between the electrolyte polymer molecules or in the electrolyte polymer molecule . The electrolyte polymer is
(A) perfluorinated electrolyte polymer,
(B) Main chain imide,
(C) a polyarylene-based or polyazole-based polymer, wherein a protonic acid group is introduced into any one or more of an aromatic ring and a heterocyclic ring included in the polymer, or
(D) a vinyl polymer, wherein one or more of the vinyl polymers have protonic acid groups introduced;
The composite electrolyte according to claim 1, comprising: The composite electrolyte according to any one of claims 1 to 3, wherein the quaternary onium group is at least one selected from the group consisting of a quaternary ammonium group and a quaternary phosphonium group. The functional group is
(A) tetraalkylammonium group,
(B) a tetraalkylphosphonium group, and
(C) Consisting of an alkylimidazolium group, an alkylpyridinium group, an alkylpyridazinium group, an alkylpyrimidinium group, an alkylpyrazinium group, an alkylquinolium group, and a quaternary nitrogenated product of a nitrogen-containing heterocyclic compound. The composite electrolyte according to any one of claims 1 to 4, which is any one or more selected from the group.   The crosslinker molecule is from the group consisting of poly (alkylene) -trialkylammonium chloride ends, poly (N, N-dialkyl-benzimidazolium), polyvinyl (1-alkyl-pyridinium), and polydiallyldimethylammonium chloride. The composite electrolyte according to claim 1, which is any one or more selected.   A polymer electrolyte fuel cell using the composite electrolyte according to any one of claims 1 to 6 for an electrolyte membrane and / or an electrolyte in a catalyst layer.