JP2002343132A - Composite solid high polymer electrolyte, its manufacturing method, and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite solid high polymer electrolyte and its manufacturing method, which is cheap and excellent in oxidation resistance, intensity, and creep properties nature. SOLUTION: A composite solid high polymer electrolyte consists of a complex of a hydrocarbon system solid high polymer electrolyte and a chelate functional group having a zirconium phosphonate compound. As the chelate function group, the chelate functional group containing one or two or more phosphate groups, especially, an aminomonoalkylene-phosphonate group, an alkylaminomonoalkylene-phosphate group an iminophosphonate group, an aminodialkylenephosphonate group, or alkylenediamintriphosphonate group is favorable. Such a composite solid high polymer electrolyte can be manufactured so that, at first, the hydrocarbon system solid high polymer electrolyte may be immersed in solution of a 1st compound (for example, zirconylchloride), and subsequently, may be immersed to solution of a 2nd compound (for example, nitrilotris(methylelephosphonate)).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite solid polymer electrolyte, a method for producing the same, and a fuel cell. More specifically, the present invention relates to a fuel cell, a water electrolysis apparatus, a hydrohalic acid electrolysis apparatus, a salt electrolysis apparatus, hydrogen and And / or a composite solid polymer electrolyte suitable as an electrolyte membrane or the like used for an electrochemical device such as an oxygen concentrator, a humidity sensor, or a gas sensor, a method for producing the same, and a fuel using such a composite solid polymer electrolyte Battery.

[0002]

2. Description of the Related Art A solid polymer electrolyte is a solid polymer material having an electrolyte group such as a sulfonic acid group in a polymer chain.
Since it has the property of firmly binding to specific ions and selectively permeating cations or anions, it is formed into particles, fibers, or membranes, and used for various electrochemical devices. I have.

For example, in a polymer electrolyte fuel cell, a pair of electrodes is provided on both sides of an electrolyte membrane, a fuel gas containing hydrogen such as a reformed gas is supplied to one electrode (anode), and oxygen such as air is supplied. Is supplied to the other electrode (cathode), and the change in free energy that occurs when the fuel is oxidized is
It is a battery that is directly extracted as electric energy. In a polymer electrolyte fuel cell, a polymer electrolyte membrane having proton conductivity is used as an electrolyte membrane.

[0004] For example, an SPE electrolyzer is an apparatus for producing hydrogen and oxygen by electrolyzing water. Instead of a conventional alkaline aqueous solution, a solid polymer having proton conductivity is used as an electrolyte. An electrolyte membrane is used.

As solid polymer electrolytes used for such various electrochemical devices, perfluoro-based electrolytes represented by Nafion (registered trademark, manufactured by DuPont) and various hydrocarbon-based electrolytes are known. However, in electrochemical devices used under severe conditions such as fuel cells and SPE electrolyzers, the chemical stability is extremely high,
In general, a perfluoro-based electrolyte having excellent oxidation resistance is used.

[0006] This is because, in the case of a fuel cell or an SPE electrolytic device, peroxide is generated in a catalyst layer formed at the interface between the solid polymer electrolyte membrane and the electrode, and the generated peroxide diffuses through the electrolyte membrane. This is because it is radicalized. Hydrocarbon-based electrolytes generally have low durability against peroxide radicals and are susceptible to deterioration reactions (oxidation reactions due to peroxide radicals) due to peroxide radicals, so they are used as electrolyte membranes for fuel cells and SPE electrolyzers. I can't.

However, perfluoro-based electrolytes are
Very expensive due to difficulties in manufacturing. Also, in order to reduce the size, weight, and efficiency of an electrochemical device, it is effective to reduce the thickness of the electrolyte membrane and increase the operating temperature, and for that purpose, the electrolyte membrane has strength and creep resistance. It is necessary to have excellent properties. However, conventional perfluoro-based electrolytes have insufficient strength and creep resistance because they are non-crosslinked.

In order to solve this problem, various proposals have hitherto been made. For example, JP 2000
Japanese Patent Publication No. 11755 proposes a highly durable solid polymer electrolyte in which a phosphorus-containing functional group such as a phosphonic acid group is introduced into a polymer compound having a hydrocarbon moiety.

Japanese Patent Application Laid-Open No. 2000-11756 discloses a polymer compound having an electrolyte group and a hydrocarbon moiety,
The applicant has proposed a highly durable solid polymer electrolyte obtained by mixing a compound containing phosphorus (for example, a polymer compound containing a phosphonic acid group).

Further, Japanese Patent Application Laid-Open No. 2000-516014 discloses that a fluorine-containing polymer having a cation exchange group contains
An inorganic filler-containing membrane in which an inorganic filler having proton conductivity (eg, zirconium hydrogen phosphate) is dispersed is disclosed.

[0011]

A highly durable polymer electrolyte having a functional group containing phosphorus and a highly durable polymer electrolyte comprising a mixture with a compound containing phosphorus are both hydrocarbon-based. Because it is mainly composed of the high molecular compound described above, it is inexpensive. The functional group containing phosphorus or the compound containing phosphorus improves the oxidation resistance of the hydrocarbon-based polymer compound and improves the durability in an environment where peroxide radicals are present.

However, simply introducing a functional group containing phosphorus into a hydrocarbon polymer compound or mixing a hydrocarbon polymer electrolyte with a compound containing phosphorus is expected to have a reinforcing effect on the electrolyte. Can not. Therefore, there is a limit to thinning the electrolyte membrane and increasing the operating temperature.

On the other hand, in the case of a membrane containing an inorganic filler in which an inorganic filler having proton conductivity is dispersed in a fluorine-based polymer, improvement in mechanical properties and proton conductivity of the membrane can be expected by the inorganic filler. . Further, when this inorganic filler-containing membrane is used directly in a methanol fuel cell, the inorganic filler suppresses methanol crossover. However, since the inorganic filler-containing film is mainly composed of a fluorine-based polymer, there is a problem that it is expensive as in the case of the perfluoro-based electrolyte.

An object of the present invention is to provide a composite solid polymer electrolyte which is inexpensive and has excellent oxidation resistance, strength and creep resistance. Also,
Another object of the present invention is to provide a method for producing a composite solid polymer electrolyte capable of easily producing a composite solid polymer electrolyte having such characteristics.

[0015]

In order to solve the above-mentioned problems, a composite solid polymer electrolyte according to the present invention comprises a hydrocarbon solid polymer electrolyte and a composite solid polymer electrolyte. And a zirconium phosphonate compound having a chelating functional group.

When a hydrocarbon-based solid polymer electrolyte is combined with a zirconium phosphonate compound having a chelating functional group (hereinafter referred to as "chelating zirconium phosphonate compound"), a catalyst for decomposition of peroxide is obtained. Is captured by the chelating functional group and inactivated. Therefore, radicalization of peroxide, and,
The degradation reaction of the hydrocarbon-based solid polymer electrolyte due to peroxide radicals is suppressed.

Further, since the chelating zirconium phosphonate compound has a high elastic modulus, the hydrocarbon-based solid polymer electrolyte is reinforced by forming a complex with the hydrocarbon-based solid polymer electrolyte. , Strength and creep resistance are improved. Further, since the main part of the composite solid polymer electrolyte according to the present invention is constituted by the hydrocarbon-based solid polymer electrolyte, such an electrolyte having excellent oxidation resistance, strength and creep resistance can be obtained at low cost. be able to.

Further, the method for producing a composite solid polymer electrolyte according to the present invention comprises a first step of immersing a hydrocarbon-based solid polymer electrolyte in an aqueous solution of a first compound containing zirconium; A second step of immersing the hydrocarbon-based solid polymer electrolyte in an aqueous solution of a second compound having a phosphonic acid group and one or more chelating functional groups. It is.

When the hydrocarbon-based solid polymer electrolyte is sequentially immersed in the aqueous solution of the first compound and the aqueous solution of the second compound, the first compound and the second compound are introduced into the hydrophilic portion of the hydrocarbon-based solid polymer electrolyte. At the hydrophilic site, the phosphonic acid group of the second compound reacts with the first compound to form a chelating zirconium phosphonate compound. Therefore, the chelating zirconium phosphonate compound can be preferentially introduced into the hydrophilic portion of the hydrocarbon-based solid polymer electrolyte. In addition, since the process involves only immersing the electrolyte membrane in the two kinds of raw material aqueous solutions, the composite solid polymer electrolyte according to the present invention can be easily manufactured.

[0020]

Embodiments of the present invention will be described below in detail. The composite solid polymer electrolyte according to the present invention includes a hydrocarbon-based solid polymer electrolyte and a chelating zirconium phosphonate compound.

First, the hydrocarbon solid polymer electrolyte will be described. The hydrocarbon-based solid polymer electrolyte refers to a hydrocarbon-based polymer compound having an electrolyte group. In the present invention, the type of electrolyte group provided in the hydrocarbon-based solid polymer electrolyte is not particularly limited,
The present invention can be applied to hydrocarbon-based solid polymer electrolytes having various electrolyte groups.

Specific examples of the electrolyte group include a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, and a sulfonimide group. Among them, a sulfonic acid group is particularly preferable because of its strong acid strength. Further, the hydrocarbon-based solid polymer electrolyte may be one having one type of electrolyte group among them, or
It may have two or more electrolyte groups. Further, the amount of the electrolyte group contained in the hydrocarbon-based solid polymer electrolyte can be arbitrarily selected according to the use of the hydrocarbon-based solid polymer electrolyte, and is not particularly limited.

In the present invention, the “hydrocarbon polymer compound” refers to a polymer compound having a C—H bond in at least a part of a polymer chain. That is, the hydrocarbon polymer compound includes not only a compound having only a C—H bond in a polymer chain, but also a compound having both a C—H bond and a C—F bond in a polymer chain.

The type, structure and the like of the hydrocarbon polymer compound are not particularly limited, and various compounds can be used. That is, the hydrocarbon polymer compound may have a straight-chain structure or may have a branched structure. Further, the electrolyte group may be introduced into either the main chain or the side chain of the hydrocarbon polymer compound.

Specific examples of the hydrocarbon polymer compound include polyether sulfone resin, polyether ether ketone resin, linear phenol-formaldehyde resin, cross-linked phenol-formaldehyde resin, linear polystyrene resin, and cross-linked polystyrene resin. Polystyrene resin, linear poly (trifluorostyrene) resin, cross-linked (trifluorostyrene) resin, poly (2,3-diphenyl-1,4)
-Phenylene oxide) resin, poly (allyl ether ketone) resin, poly (arylene ether sulfone) resin,
Poly (phenylquinosan phosphorus) resin, poly (benzylsilane) resin, ethylene tetrafluoroethylene copolymer-graft-polystyrene (hereinafter referred to as “ETFE-
g-PS ". ) Resin, polystyrene-graft-
Polyvinylidene fluoride resin, polystyrene-graft-
A preferred example is tetrafluoroethylene resin.

Above all, a graft copolymer represented by ETFE-g-PS resin having an ethylene tetrafluoroethylene copolymer resin as a main chain and a hydrocarbon polymer capable of introducing an electrolyte group as a graft side chain. Is a hydrocarbon-based polymer compound because it is inexpensive, has sufficient strength when thinned, and can easily control the conductivity by adjusting the type and introduction amount of the electrolyte group. Particularly preferred.

The hydrocarbon-based solid polymer electrolyte may be composed of only one kind of the above-mentioned hydrocarbon-based polymer compound having one or more kinds of electrolyte groups, or It may be a mixture of two or more hydrocarbon solid polymer compounds having one or more electrolyte groups.

Next, the chelating zirconium phosphonate
The compound will be described. "Chelable phosphonates
A `` conium compound '' refers to a host having a chelating functional group.
Zirconium phonate compound. Of chelating functional groups
The introduction position is not particularly limited,
The chelating functional group is a zirconium phosphonate compound.
It is preferably bonded to a constituent phosphorus atom. this
In some cases, the chelating functional group is directly attached to the phosphorus atom.
Or an alkylene chain (-(CH ₂)_n−,
n ≧ 1), a branched carbon structure (eg, —CHCH₃−, −
C (CH₃) ₂-Etc.) between the phosphorus atom through an atomic group such as
They may be directly connected.

The chelating functional group is a functional group having two or more coordinating atoms (O, N, S, etc.). In the present invention, the kind of the coordinating atom contained in the chelating functional group is not particularly limited. Further, the chelating functional group may have only one kind of coordinating atom, or may have two or more kinds of coordinating atoms.

The chelating functional group may be a functional group having an acidic group having one or more coordination atoms. Specific examples of such an acidic group include a phosphonic acid group (—P (O) (OH) ₂ ) and a carboxylic acid group (—COO
H) is a preferred example.

Further, the chelating functional group may be a functional group having only an acidic group having one or more coordinating atoms, or a combination of these acidic groups and other coordinating atoms or other coordinating atoms. It may be a functional group having both atomic groups including a coordination atom.

Among these, a functional group having one or more phosphonic acid groups (—P (O) (OH) ₂ ) provides high oxidation resistance to the composite solid polymer electrolyte. Therefore, it is particularly suitable as a chelating functional group.
In general, as the number of phosphonic acid groups contained in the chelating functional group increases, the oxidation resistance of the composite solid polymer electrolyte improves.

In particular, a functional group in which at least one hydrogen bonded to an amino group (—NH ₂ ) is substituted with an atomic group having a phosphonic acid group is preferable. In this case, a phosphonic acid group may be bonded directly to the nitrogen atom of the amino group, or an alkylene chain _{(- (CH 2) n -} , n
≧ 1), a branched carbon structure (eg, —CHCH ₃ —, —C
It may be indirectly bonded to a nitrogen atom through an atomic group such as (CH ₃ ) _2- .

As a preferred example of the chelating functional group,
Amino monoalkylene phos represented by the following general formula 1
And a phonic acid group. Further, an amino acid represented by the formula
Specific examples of the nomonoalkylenephosphonic acid group include
Nomethylene phosphonic acid group (-NH-CH₂P (O) (OH)
₂), Aminoethylenephosphonic acid group (—NH— (CH ₂)
₂-P (O) (OH)₂) And the like.

[0035]

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Another preferred example of the chelating functional group is an alkylaminomonoalkylenephosphonic acid group represented by the following general formula (2). In addition,
Specific examples of the alkylaminomonoalkylenephosphonic acid group represented by the formula include a methylaminomethylenephosphonic acid group (—N (CH ₃ ) (CH ₂ P (O) (OH) ₂ )) and the like.

[0037]

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Another preferred example of the chelating functional group is an iminophosphonic acid group represented by the following general formula. Further, specific examples of the iminophosphonic acid group represented by Formula 3 include an iminomethylenephosphonic acid group (= N—CH ₂ —P (O) (OH) ₂ ).

[0039]

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Another preferred example of the chelating functional group is an aminodialkylenephosphonic acid group represented by the following general formula (4). Specific examples of the aminodialkylenephosphonic acid group represented by the chemical formula 4 include an aminodi (methylenephosphonic acid) group (—N {CH ₂
P (O) (OH) ₂ } ₂ ) and an aminodi (ethylenephosphonic acid) group (—N {CH ₂ CH ₂ P (O) (OH) ₂ } ₂ ).

[0041]

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Another preferable example of the chelating functional group is an alkylenediaminetriphosphonic acid group represented by the following general formula (5). Further, specific examples of the alkylenediaminetriphosphonic acid group represented by Formula 5 include a triphosphonic acid compound in which the alkylene group of R1 to R4 is a methylene group or an ethylene group.

[0043]

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Such a chelating zirconium phosphonate compound is combined with the above-mentioned hydrocarbon-based solid polymer electrolyte. In the present invention, the macro-distribution of the chelating zirconium phosphonate compound in the hydrocarbon-based solid polymer electrolyte is not particularly limited, and is optimal according to the use of the composite solid polymer electrolyte, the use environment, and the like. What is necessary is just to select a macro distribution.

For example, when the electrolyte membrane is immersed in an aqueous solution containing peroxide and used in a heated state, peroxide radicals are generated randomly in the membrane. Therefore, when the composite solid polymer electrolyte according to the present invention is used in such an environment, the chelating zirconium phosphonate compound is uniformly introduced into the entire hydrocarbon-based solid polymer electrolyte. Is preferred.

On the other hand, in the case of a fuel cell or an SPE electrolyzer, peroxide is generated in the catalyst layer formed on the surface of the electrolyte membrane, and the generated peroxide diffuses inward from the surface of the electrolyte membrane. It becomes a peroxide radical and causes a deterioration reaction of the electrolyte membrane.

Therefore, when the composite solid polymer electrolyte according to the present invention is used in such an environment, the chelating zirconium phosphonate compound is not necessarily uniform with respect to the entire hydrocarbon-based solid polymer electrolyte. It is not necessary to be introduced into the surface portion of the hydrocarbon-based solid polymer electrolyte, which is the most intense in the oxidative degradation reaction, at least. In this case, the introduction amount of the chelating zirconium phosphonate in the surface portion may be uniform, or may be changed stepwise or continuously from the surface portion to the inside of the electrolyte membrane.

The micro-distribution of the chelating zirconium phosphonate compound in the hydrocarbon-based solid polymer electrolyte is not particularly limited, either. What is necessary is just to select the optimal micro distribution.

That is, the solid polymer electrolyte generally comprises
A strongly hydrophobic main chain portion and a strongly hydrophilic electrolyte group coexist, and the electrolyte groups associate in a matrix (hydrophobic portion) consisting of the main chain portion to form an ion cluster (hydrophilic portion).
Is formed. The chelating zirconium phosphonate compound may be introduced into one of the hydrophobic part and the hydrophilic part, or may be introduced into both. Further, the amount of the chelating zirconium phosphonate compound introduced may be changed stepwise or continuously from the hydrophilic part toward the hydrophobic part.

For example, in the case of a fuel cell or an SPE electrolyzer, the generated peroxide first diffuses into the hydrophilic portion of the electrolyte membrane and causes a deterioration reaction in the hydrophilic portion. Therefore, when the composite solid polymer electrolyte according to the present invention is used in such an environment, the chelating zirconium phosphonate compound is preferentially introduced into at least the hydrophilic portion of the electrolyte membrane. Is desirable.

The weight percentage of the chelating zirconium phosphonate compound with respect to the hydrocarbon-based solid polymer electrolyte (hereinafter referred to as “introduction rate”) is not particularly limited, and the use of the composite solid polymer electrolyte is not limited. The optimum introduction rate may be selected according to the usage environment and the like. In general,
As the rate of introduction of the chelating zirconium phosphonate compound increases, mechanical properties and oxidation resistance tend to improve, and ion conductivity tends to decrease.

For example, when the composite solid polymer electrolyte according to the present invention is used as an electrolyte membrane used in a fuel cell or an SPE electrolyzer, the rate of introduction of the chelating zirconium phosphonate compound is 0.01% to 90%. %, More preferably 0.5% or more and 30% or less.

Next, the operation of the composite solid polymer electrolyte according to the present invention will be described. In a fuel cell or an SPE electrolyzer, a catalyst (a hydrogen peroxide) is formed in a catalyst layer formed at an interface between an electrolyte membrane and an electrode by a battery reaction.
Is known to generate. In addition, it is known that this peroxide is decomposed by a specific metal ion (Fe ²⁺ , Cu ^2+, etc.) to form a radical.

In a fuel cell, a water electrolyzer, and the like, various metal materials are used for a reaction gas supply pipe and other peripheral members, and metal ions serving as a catalyst for decomposing peroxide react from the peripheral members. It elutes in gas etc. The eluted metal ions are carried to the electrolyte membrane via a reaction gas or the like,
The peroxide generated in the catalyst layer and diffused in the electrolyte membrane is radicalized. Therefore, in such an environment, if a hydrocarbon-based electrolyte having poor oxidation resistance is used,
The polymer chain is cut by the peroxide radical, and the electrolyte is oxidized and degraded.

On the other hand, when a chelating zirconium phosphonate compound is complexed with a hydrocarbon-based solid polymer electrolyte, metal ions serving as catalysts for decomposition of peroxides are as follows:
It is trapped by the chelating functional group and inactivated. Therefore, the peroxide generated in the catalyst layer is discharged out of the system without radicalization. Further, since the generation of peroxide radicals itself is suppressed, the degradation reaction of the hydrocarbon-based polymer electrolyte constituting the main part of the electrolyte does not easily progress.

When the chelating functional group is a functional group having a phosphonic acid group, particularly when the chelating functional group is a functional group having an atomic group such as an amino group containing a nitrogen atom and a phosphonic acid group, Metal ions serving as peroxide decomposition catalysts are efficiently captured. Therefore, the oxidation resistance of the composite solid polymer electrolyte is further improved.

Further, since the chelating zirconium phosphonate compound has a high elastic modulus, the hydrocarbon-based solid polymer electrolyte is reinforced by compounding the compound with the hydrocarbon-based solid polymer electrolyte. Therefore, the strength and creep resistance of the composite solid polymer electrolyte are improved. Further, since the main part of the composite solid polymer electrolyte according to the present invention is constituted by the hydrocarbon-based solid polymer electrolyte, such an electrolyte having excellent oxidation resistance, strength and creep resistance can be obtained at low cost. be able to.

Next, a method for producing the composite solid polymer electrolyte according to the present invention will be described. The method for producing a composite solid polymer electrolyte according to the present invention includes a first step and a second step.

In the first step, an aqueous solution of the first compound (hereinafter referred to as “the first compound”)
This is called "first aqueous solution". ) Is a step of immersing the above-mentioned hydrocarbon-based solid polymer electrolyte. The first compound used in the first step may be any water-soluble compound containing zirconium, and is not particularly limited. As the first compound, specifically, zirconyl chloride (ZrCl ₂ O), zirconyl bromide (ZrBr ₂
O) or their hydrated salts are preferred examples.

The concentration of the first compound in the first aqueous solution,
The immersion conditions in the first step, such as the immersion time of the hydrocarbon-based solid polymer electrolyte in the first aqueous solution, are arbitrary depending on the shape of the hydrocarbon-based solid polymer electrolyte, the introduction rate of the chelating zirconium phosphonate compound, and the like. Can be selected.

In general, when the immersion conditions are the same, the introduction amount of the first compound tends to increase as the hydrocarbon-based solid polymer electrolyte becomes thinner. In general, when the shape of the electrolyte is the same, the amount of the first compound introduced tends to increase as the concentration of the first compound increases or as the immersion time in the first aqueous solution increases.

In the second step, the hydrocarbon-based solid polymer electrolyte immersed in the first aqueous solution is further immersed in an aqueous solution of the second compound (hereinafter, this is referred to as a “second aqueous solution”). As the second compound used in the second step, a compound having one or more phosphonic acid groups and one or more chelating functional groups is used.

The chelating functional group provided in the second compound may be a functional group having two or more coordinating atoms (O, N, S, etc.), and the type thereof is not particularly limited. is not. That is, the chelating functional group may have only one type of coordination atom, or may have two or more types of coordination atoms.

The chelating functional group may be a functional group having an acidic group having one or more coordination atoms (for example, a phosphonic acid group, a carboxylic acid group, etc.). Further, the chelating functional group may be a functional group having only an acidic group having one or more coordinating atoms, or a combination of these acidic groups and other coordinating atoms or other coordinating atoms. The functional group may have both of the atomic groups including

Among these, the above-mentioned chelating functional group having a phosphonic acid group, in particular, an amino group (—NH ₂ )
A chelating functional group in which at least one hydrogen attached to is replaced by an atomic group having a phosphonic acid group (for example,
The above-mentioned aminomonoalkylenephosphonic acid group, alkylaminomonoalkylenephosphonic acid group, iminophosphonic acid group, aminodialkylenephosphonic acid group, alkylenediaminetriphosphonic acid group, etc.) are suitable as the chelating functional group provided in the second compound. It is.

As the second compound used in the second step, specifically, nitrilotris (methylene phosphonic acid) (N {CH ₂ P (O) (OH) ₂ } ₃ ), ethylene diphosphonic acid (( OH) ₂ (O) PCH ₂ CH ₂ P (O) (O
H) ₂ ), xylylenediphosphonic acid ((OH) ₂ (O) PC
H ₂ PhCH ₂ P (O) (OH) ₂ ) is a preferred example.

Further, in addition to the second compound, the second aqueous solution may contain an acid containing phosphorus such as phosphoric acid or phosphorous acid. The addition of an acid containing phosphorus to the second aqueous solution has the effect of reducing the amount of the relatively expensive second compound used.

The immersion conditions in the second step, such as the concentration of the acid containing the second compound and phosphorus in the second aqueous solution and the immersion time of the hydrocarbon-based solid polymer electrolyte in the second aqueous solution, are as follows. It can be arbitrarily selected according to the shape of the polymer electrolyte, the introduction ratio of the chelating zirconium phosphonate compound to the hydrocarbon-based solid polymer electrolyte, and the like.

In general, when the immersion conditions are the same, the amount of the second compound or the acid containing phosphorus tends to increase as the thickness of the hydrocarbon-based solid polymer electrolyte becomes thinner. Also,
When the shape of the electrolyte is the same, as the concentration of the second compound or the acid containing phosphorus increases, or as the immersion time in the second aqueous solution increases, the amount of the second compound or the acid containing phosphorus increases. Tend.

Next, the operation of the manufacturing method according to the present embodiment will be described. In the first step, when the hydrocarbon-based solid polymer electrolyte is immersed in the first aqueous solution, the first aqueous solution is mainly introduced into the cluster which is a hydrophilic site. Next, in the second step, when the hydrocarbon-based solid polymer electrolyte is immersed in the second aqueous solution, the second aqueous solution is further introduced into the cluster into which the first aqueous solution has been introduced. Further, inside the cluster, the first compound and the phosphonic acid group of the second compound react with each other to generate a chelating zirconium phosphonate compound.

Therefore, according to the method of the present invention, it is possible to obtain a composite solid polymer electrolyte in which a chelating zirconium phosphonate compound is preferentially introduced into a hydrophilic portion of a hydrocarbon solid polymer electrolyte. it can. In addition, since the process involves only immersing the electrolyte membrane in the two kinds of raw material aqueous solutions, the composite solid polymer electrolyte according to the present invention can be easily manufactured.

[0072]

EXAMPLES (Example 1) A composite solid polymer electrolyte membrane (hereinafter referred to as a "composite membrane") was produced using an ETFE-g-PS membrane as a hydrocarbon-based solid polymer electrolyte. . The ETFE-g-PS membrane has a graft ratio of 40%.

First, a first aqueous solution containing 1M zirconyl chloride was prepared, and the ETFE-g-PS film was formed on the first aqueous solution.
It was immersed in an aqueous solution under boiling conditions for 2 hours. Next, nitrilotris (methylene phosphonic acid) (hereinafter referred to as "NM
P3 ". ): A second aqueous solution having a weight ratio of water of 0.5: 0.5 is prepared, and the ETFE-g-PS film is immersed in the second aqueous solution at room temperature overnight to obtain ETFE-g-water.
A chelating zirconium phosphonate compound was generated inside the PS film. After the membrane is washed with water, it is immersed in boiling water for 2 hours, and the water-soluble part (unreacted reagent, low molecular weight phosphonic acid, etc.)
Was removed. Further, this film was dried to obtain a composite film.

In the formula, zirconyl chloride and NM
The reaction formula of P3 is shown. The composite membrane obtained in this example was E
It is composed of a composite of a TFE-g-PS film and a chelating zirconium phosphonate compound having an aminodi (methylene phosphonic acid) group as a chelating functional group.

[0075]

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(Example 2) The weight ratio of phosphoric acid: NMP3: water was 0.25: 0.25:
A composite membrane was prepared according to the same procedure as in Example 1 except that the second aqueous solution of 0.5 was used.

Example 3 The weight ratio of phosphoric acid: NMP3: water was 0.125: 0.37
Example 1 except that a second aqueous solution of 5: 0.5 was used.
According to the same procedure as above, a composite membrane was produced.

Comparative Example 1 Under the same conditions as in Example 1,
The ETFE-g-PS membrane was immersed in the first aqueous solution. Next, a second aqueous solution having a weight ratio of phosphoric acid: water of 0.5: 0.5 is prepared, and the ETFE-g-PS membrane is immersed in the second aqueous solution at room temperature overnight to obtain ETFE-g-PS. Zirconium phosphate was generated inside the g-PS film. After washing the membrane with water, the membrane was immersed in boiling water for 2 hours to remove water-soluble parts (unreacted reagent, low molecular weight phosphonic acid, etc.). Further, this film was dried to obtain a composite film.

(Comparative Example 2) ETFE- used in Example 1
The g-PS film was used as a test material without performing a treatment of immersing it in the first aqueous solution and the second aqueous solution.

The composite membranes obtained in Examples 1 to 3 and Comparative Example 1 and the untreated ETFE-g-PS membrane (Comparative Example 2) were prepared using a chelating zirconium phosphonate compound and a zirconium phosphate. The introduction rate and the electrical conductivity, water content, dynamic storage modulus and hydrogen peroxide resistance of the composite membrane were evaluated.

The rate of introduction was represented by the rate of weight increase before and after the reaction with the first aqueous solution and the second aqueous solution. The electric conductivity was measured in pure water at 25 ° C. by the AC method (10 kHz).
It was calculated from the film resistance measured in z) and the film thickness. Further, the water content was represented by a weight increase rate in impregnating the completely dried composite membrane with water. The elastic modulus was determined using a viscoelastic spectrometer at a dynamic storage elastic modulus at 120 ° C. (1
0 Hz). Furthermore, the hydrogen peroxide resistance is 3 wt.
% Of H ₂ O ₂ and 4 ppm of Fe ²⁺ ions were immersed in an aqueous solution under boiling conditions, and evaluated by a weight loss rate after a lapse of a predetermined time. Table 1 shows the results.

[0082]

[Table 1]

For the electrical conductivity, the untreated ETFE
-G-PS film (Comparative Example 2) was the highest, and the electrical conductivity of Comparative Example 1 where zirconium phosphate was introduced and Examples 1 to 3 where chelating zirconium phosphonate compound was introduced were lower than Comparative Example 2. . This is because the zirconium phosphate and the chelating zirconium phosphonate compound are weak acids. Further, the electric conductivity and the water content correlated therewith tended to decrease as the introduction rate of the zirconium phosphate or the chelating zirconium phosphonate compound increased.

Regarding the resistance to hydrogen peroxide, the untreated ET
The FE-g-PS membrane (Comparative Example 2) was the lowest, and the polystyrene portion was almost completely decomposed in about 9 minutes (the weight loss rate was about 4).
0% corresponds to complete decomposition of the polystyrene portion). Hydrogen peroxide resistance of Comparative Example 1 in which zirconium phosphate was introduced was the same, and the polystyrene portion was almost completely decomposed in about 9 minutes. This is because zirconium phosphate does not have a chelating functional group and has a poor effect of suppressing radicalization of hydrogen peroxide.

On the other hand, in Examples 1 to 3 in which the chelating zirconium phosphonate compound was introduced, the hydrogen peroxide resistance was greatly improved, and the weight loss rate after 36 minutes passed was 20%. % Or less. This is presumably because Fe ²⁺ ions were trapped and inactivated by the aminodi (methylene phosphonic acid) group contained in the chelating zirconium phosphonate compound.

Further, the elastic modulus of the untreated graft membrane (Comparative Example 2) was the lowest, and the elastic modulus of Examples 1 to 3 and Comparative Example 1 in which zirconium phosphate or chelating zirconium phosphonate was introduced were as follows: In each case, the result was improved by one digit or more compared to Comparative Example 2. This is because the membrane was reinforced by complexing zirconium phosphate or chelating zirconium phosphonate.

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

For example, the composite solid polymer electrolyte according to the present invention can be used alone, but the composite solid polymer electrolyte according to the present invention is bonded to the surface of another solid polymer electrolyte. You can also.

Further, in the above-described embodiment, the method of “in that case” forming the chelating zirconium phosphonate compound inside the electrolyte using the first aqueous solution and the second aqueous solution has been mainly described. The composite solid polymer electrolyte can also be produced by simply mixing a separately synthesized chelating zirconium phosphonate compound and a hydrocarbon-based solid polymer electrolyte.

Further, the composite solid polymer electrolyte according to the present invention is particularly suitable as an electrolyte membrane used in electrochemical devices used under severe conditions such as fuel cells and SPE electrolyzers. The use of is not limited to this, but also as an electrolyte membrane used in various electrochemical devices such as a hydrohalic acid electrolyzer, a salt electrolyzer, a hydrogen and / or oxygen concentrator, a humidity sensor, and a gas sensor. Can be used.

[0091]

The composite solid polymer electrolyte according to the present invention comprises a complex of a hydrocarbon-based solid polymer electrolyte and a chelating zirconium phosphonate compound. Is suppressed, and the oxidation resistance is improved. Further, there is an effect that the hydrocarbon-based solid polymer electrolyte is reinforced by the chelating zirconium phosphonate, and strength and creep resistance are improved. Further, since the main part is constituted by the hydrocarbon-based solid polymer electrolyte, there is an effect that such an electrolyte having excellent oxidation resistance, strength and creep resistance can be obtained at low cost. In addition, by using these composite solid polymer electrolytes in electrochemical devices, particularly in fuel cells and SPE electrolyzers, there is an effect that these devices can be provided at low cost and excellent in durability. .

Further, in the method for producing a composite solid polymer electrolyte according to the present invention, a chelating zirconium phosphonate compound is synthesized inside an electrolyte by immersing a hydrocarbon-based solid polymer electrolyte in two kinds of aqueous solutions of raw materials. Therefore, there is an effect that the chelating zirconium phosphonate compound can be preferentially introduced into the hydrophilic site of the hydrocarbon-based solid polymer electrolyte. In addition, since the process involves only immersing the electrolyte membrane in the two kinds of raw material aqueous solutions, there is an effect that the composite solid polymer electrolyte according to the present invention can be easily manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C25B 13/08 301 C25B 13/08 301 H01B 13/00 H01B 13/00 H01M 8/02 H01M 8/02 P 8/10 8/10 (72) Inventor Tomo Morimoto 41-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture, 1st place at Toyota Central Research Institute Co., Ltd. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kamiya Atsushi Kamiya, Aichi-gun, Nagakute Town AB25 AF14 4J002 BC031 BN031 CC031 CN031 EW046 GP01 5G301 CD01 5H026 AA06 BB03 EE18 HH00

Claims (7)

[Claims] 1. A composite solid polymer electrolyte comprising: a hydrocarbon-based solid polymer electrolyte; and a zirconium phosphonate compound having a chelating functional group, which is complexed with the hydrocarbon-based solid polymer electrolyte. 2. The composite solid polymer electrolyte according to claim 1, wherein the chelating functional group is a chelating functional group having one or more phosphonic acid groups or carboxylic acid groups. 3. The chelating functional group having a phosphonic acid is an aminomonoalkylenephosphonic acid group, an alkylaminomonoalkylenephosphonic acid group, an iminophosphonic acid group, an aminodialkylenephosphonic acid group, or an alkylenediaminetriphosphonic acid. The composite solid polymer electrolyte according to claim 2, which is a group. 4. A first step of immersing a hydrocarbon-based solid polymer electrolyte in an aqueous solution of a first compound containing zirconium, and one or more phosphonic acid groups and one or more chelating functional groups. And d. Immersing the hydrocarbon-based solid polymer electrolyte in an aqueous solution of a second compound having the following. 5. The method according to claim 4, wherein the first compound is zirconyl chloride. 6. The method for producing a composite solid polymer electrolyte according to claim 4, wherein the second compound is nitrilotris (methylene phosphonic acid). 7. A fuel cell comprising the composite solid polymer electrolyte according to any one of claims 1 to 3.