JP4762695B2 - Proton conducting solid polymer electrolyte and fuel cell - Google Patents

Description

  The present invention relates to a proton-conducting solid polymer electrolyte and a fuel cell, and in particular, at an operating temperature of 100 ° C. or more and 200 ° C. or less, good power generation performance is obtained even when there is no humidification or a relative humidity of 50% or less. The present invention relates to a polymer electrolyte fuel cell that is stably displayed for a long period of time.

  Conventionally, as a proton conductive electrolyte for a polymer electrolyte fuel cell, from the viewpoint of system efficiency and long-term durability of components, at a working temperature of about 100 ° C. to 300 ° C., it is not humidified or has a low relative humidity of 50% or less. There is a demand for a proton conductor that stably exhibits good proton conductivity for a long period of time under humid operating conditions. In the development of a conventional polymer electrolyte fuel cell, it has been studied in view of the above requirements, but in a polymer electrolyte fuel cell using a perfluorocarbon sulfonic acid membrane as an electrolyte membrane, an operating temperature of 100 ° C. or more and 300 ° C. or less. Below, there was a drawback that sufficient power generation performance could not be obtained at a relative humidity of 50% or less.

  Further, a material containing a proton conductivity-imparting agent (for example, see Patent Document 1), a material using a silica dispersion film (for example, Patent Document 2), or a material using an inorganic-organic composite film ( For example, see Patent Document 3), using a phosphate-doped graft membrane (see, for example, Patent Document 4), or using an ionic liquid composite membrane (see, for example, Patent Document 5 and Patent Document 6). However, in any case, sufficient power generation performance cannot be exhibited stably for a long period of time under an operating temperature of 100 ° C. or more and 300 ° C. or less, no humidification, or a relative humidity of 50% or less.

Only by using a polymer electrolyte membrane made of polybenzimidazole doped with a strong acid such as phosphoric acid disclosed in Patent Document 7, a solid high performance that exhibits sufficient power generation performance even at high temperatures up to 200 ° C. Although a molecular fuel cell can be obtained, since it is impregnated with phosphoric acid 4 times the weight of the polymer, it is difficult to stably maintain power generation performance for a long period of time.
JP 2001-035509 A Japanese Patent Laid-Open No. 06-1111827 JP 2000-090946 A JP 2001-213987 A JP 2001-167629 A JP 2003-123791 A US Pat. No. 5,525,436

  The present invention has been made in order to solve the above-mentioned problems, and has stable power generation performance for a long period of time at an operating temperature of about 100 ° C. to 200 ° C. under a non-humidified or relative humidity of 50% or less. An object of the present invention is to provide a proton-conducting solid polymer electrolyte that can be shown in (1) and a fuel cell equipped with the electrolyte.

In order to achieve the above object, the present invention employs the following configuration.
The proton conductive solid polymer electrolyte of the present invention comprises an acid and a polymer compound impregnated with the acid, and the polymer compound has a repeating unit represented by the following general formula (1). It is characterized by having polyazomethines. However, in the general formula (1), R ₁ is hydrogen atom, an alkyl group, or a aryl group, R ₂ represents a hydrogen atom, an alkyl group, or a allyl group, X is an arylene group , N indicating the number of repetitions is an integer in the range of 100 to 100,000.

In the proton conductive solid polymer electrolyte of the present invention, in the general formula (1), R ₁ is any _one of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an allyl group, and R ₂ is hydrogen atom, an alkyl group of 1 to 6 carbon atoms, are either allyl group, X is phenylene group, tolylene group, xylylene group, biphenylene group, naphthyl alkylene group, Antori alkylene group, Fenantori alkylene group N representing the number of repetitions is preferably an integer in the range of 100 to 100,000.
In the proton conductive solid polymer electrolyte of the present invention, a part of the polyazomethines may be oxidized and modified.
In the proton conductive solid polymer electrolyte of the present invention, a crosslinked structure with a low molecular crosslinking agent may be formed. As the low molecular crosslinking agent, a compound selected from a diacid anhydride, a diepoxy compound, and a diisocyanate is preferable.
In the proton conductive solid polymer electrolyte of the present invention, the acid is preferably phosphoric acid, phosphonic acid, or a mixture thereof.

Next, a fuel cell according to the present invention includes an oxygen electrode, a fuel electrode, and a polymer electrolyte membrane sandwiched between both electrodes, an oxidant distribution plate having an oxidant channel formed on the oxygen electrode side, and the fuel channel A fuel cell having a unit cell formed by providing a formed fuel flow distribution plate on the fuel electrode side, wherein the polymer electrolyte membrane is formed of the proton-conducting solid polymer electrolyte described above. .
In the fuel cell of the present invention, it is preferable that either one or both of the oxygen electrode and the fuel electrode contain the proton-conducting solid polymer electrolyte described above.

  According to the present invention, even when the operating temperature is 100 ° C. or higher and 200 ° C. or lower and no humidification or a relative humidity of 50% or less, by using a proton conductive solid polymer electrolyte doped with a small amount of acid, It is possible to obtain a polymer electrolyte fuel cell that stably exhibits good power generation performance for a long period.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Proton conductive solid polymer electrolyte]
The proton conductive solid polymer electrolyte (hereinafter referred to as polymer electrolyte) of the present embodiment is configured to include an acid and a polymer compound impregnated with the acid. The polymer compound is a polyazomethine having a repeating unit represented by the general formula (1). In the polymer electrolyte of the present embodiment, an acid is impregnated (doped) with a polymer compound composed of polyazomethines. Moreover, the polymer electrolyte of this embodiment may have a crosslinked structure in which the main chains of polyazomethines are crosslinked with a low molecular crosslinking agent.
Hereinafter, components constituting the polymer electrolyte of the present embodiment will be described below.

(Polyazomethines)
As described above, the polyazomethine is a polymer having a repeating unit represented by the general formula (1). As shown in the general formula (1), the polyazomethines have an amine group bonded to a phenyl group, and the acid is doped into the polyazomethines by the interaction between the amine group and the acid. Proton conductivity is considered to be expressed. In addition, polyazomethines have a nitrogen-carbon double bond bonded to a phenyl group, and the presence of this nitrogen-carbon double bond imparts thermal stability to the polyazomethine, thereby It is considered that the heat resistance of the polymer electrolyte is improved.

In the general formula (1), R ₁ is hydrogen atom, an alkyl group, or a aryl group, R ₂ represents a hydrogen atom, an alkyl group, or a aryl group, X is arylene group, repeated N representing a number is an integer in the range of 1 to 6. More preferably, R ₁ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an allyl group, and R ₂ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an allyl group. There, X is phenylene group, tolylene group, xylylene group, biphenylene group, naphthyl alkylene group, Antori alkylene group, or a Fenantori alkylene groups, integers ranging n is 100 to 100,000 indicating the number of repetitions It is. Particularly preferably, _{R 1} and _{R 2} are hydrogen atoms, X is phenylene group, which is an integer in the range n of 100 to 100,000 indicating the number of repetitions.

When R ₁ and R ₂ are substituents other than those described above, the thermal stability of the polyazomethines decreases due to the interaction with the amino group bonded to the phenyl group, which is not preferable. Moreover, when X becomes a substituent other than the above, it is not preferable because the thermal stability of the polyazomethines is lowered. Further, when n indicating the number of repetitions is less than 100, the mechanical strength of the polymer electrolyte is decreased, which is not preferable. On the other hand, when n exceeds 100000, the solubility of polyazomethines in a solvent is decreased. Therefore, the moldability of polyazomethines by the so-called casting method is lowered, and it becomes difficult to make the polymer electrolyte into a desired shape, which is not preferable.

In addition, a part of the polyazomethines of this embodiment may be modified by heat oxidation. As described above, polyazomethines have excellent thermal stability due to the presence of a nitrogen-carbon double bond, and also exhibit proton conductivity due to the interaction between an amine group and an acid. When either R ₁ or R ₂ is a hydrogen atom, a dehydration reaction due to thermal oxidation is likely to occur between the nitrogen-carbon double bond and the amine group in the presence of oxygen. This dehydration reaction is a reaction in which R ₁ or R ₂ (hydrogen atom) bonded to carbon of a nitrogen-carbon double bond, oxygen in the atmosphere, and hydrogen of the amine group combine to generate water. . By this reaction, the nitrogen-carbon double bond becomes a single bond, and the nitrogen atom of the amine group is further bonded to the carbon atom of the nitrogen-carbon bond to form a nitrogen-containing carbocyclic structure. The following general formulas (2) and (3) show examples of structures in which polyazomethines are modified by heat oxidation.

Such modification is likely to occur under conditions in which polyazomethines are heated to about 60 ° C. in the presence of oxygen. In the absence of oxygen, denaturation does not occur even when heated to about 60 ° C. In addition, with respect to polyazomethines doped with an acid, it is presumed that the amine group is protected by the acid, and even when heated to about 60 ° C. in the presence of oxygen, the modification is unlikely to occur.
In addition, when R ₁ and R ₂ are other than hydrogen atoms, modification is unlikely to occur only by heating to 60 ° C. in the presence of oxygen, and a catalyst such as ferric chloride for extracting the R ₁ and R ₂ groups. The existence of

  This modified structure is desirably present in a part of the polyazomethines, and it is not desirable that the entire polyazomethines are modified. Modification of part of polyazomethines improves the thermal stability and solvent resistance of polyazomethines, and allows stable proton conductivity to be expressed even in relatively high-temperature atmospheres such as fuel cells. . On the other hand, if the whole polyazomethine is modified, the amine group disappears, the acid impregnation rate (doping rate) is significantly lowered, and the proton conductivity is lowered, which is not preferable.

(acid)
Examples of the acid in the present embodiment include phosphoric acid, phosphonic acid, sulfuric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, trifluoromethanesulfimidic acid, phosphotungstic acid, and the like, but heat resistance, corrosiveness, volatility, conductivity From this point of view, phosphoric acid and phosphonic acid or mixtures thereof are preferred. Any of these acids interacts with the amine group of the polyazomethine and is impregnated (doped) into the polyazomethine to develop proton conductivity. The acid doping ratio with respect to polyazomethines is preferably in the range of 50% to 400%, more preferably in the range of 100% to 300%, although it depends on the type of acid. If the doping rate is too low, the proton conductivity is lowered, which is not preferable, and if the doping rate is too high, the mechanical strength of the solid polymer electrolyte is reduced.

(Low molecular crosslinking agent)
Moreover, in the solid polymer electrolyte of this embodiment, the crosslinked structure by a low molecular crosslinking agent may be formed. As the low molecular crosslinking agent, a compound selected from a diacid anhydride, a diepoxy compound, and a diisocyanate is preferable. By these low molecular crosslinking agents, a crosslinked structure in which the main chains of polyazomethines are crosslinked is formed, and the mechanical strength of the polymer electrolyte is further improved. The cross-linking reaction mainly occurs with respect to the amine group of the polyazomethine, and the amine groups of adjacent molecular chains are cross-linked to stabilize the molecular structure of the whole polyazomethine.

Examples of the dianhydride include dianhydride pyromellitic acid, cyclobutene dicarboxylic acid anhydride, and derivatives thereof.
Examples of the diepoxy compound include ethylene glycol diglycidyl ether and 2,2′-bis (4-glycidyloxyphenyl) -propane.
Further, as the diisocyanate, diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4′-diphenyl ether diisocyanate (ODI), tolylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, hexafluorobiphenyl diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, Examples include isophorone diisocyanate and cyclohexane diisocyanate. Furthermore, these derivatives can also be used.

  Also, the mixing ratio of these low molecular crosslinkers and polyazomethines (low molecular crosslinkers / polyazomethines) is mixed at a ratio of 1/5 (mol / mol) to 1/3 (mol / mol). Is preferred. When the amount of the low molecular crosslinking agent is larger than this, gelation proceeds and it becomes difficult to form the polymer electrolyte into a film.

(Polymer electrolyte production method)
The method for producing a polymer electrolyte includes a step of synthesizing polyazomethines, and a step of forming the synthesized polyazomethines into, for example, a film and impregnating the polyazomethines with an acid.
As described in the literature (Macromolecules, vol.16, No.1 (1983) 128-136), for example, polyazomelins can be synthesized by using a diamine such as 3,3′-diaminobenzidine and a dialdehyde such as isophthalaldehyde. Is obtained by reacting. The reaction scheme is shown in the following formula (4).

When R ₁ or R ₂ in the general formula (1) is an alkyl group such as a methyl group, a diamine such as 3,3′-diaminobenzidine and 1,4, as shown in the following formula (5) -Obtained by reacting with a diketone such as diacetylbenzene. In the formula (5), R ₁ and R ₂ are methyl groups, but when other alkyl groups are introduced, the methyl group bonded to the carbonyl group of the diketone in the formula (5) is replaced with other alkyl groups. Just do it.

  As the diamine in the above formulas (4) and (5), 3,3′-diaminobenzidine is preferable. In addition to isophthalaldehyde, terephthalaldehyde, 9,10-diformylanthracene, 4,4'-diformylbiphenyl, and the like can be used as the dialdehyde. Further, as the diketone, 1,3-diacetylbenzene and the like can be used in addition to 1,4-diacetylbenzene.

Next, the synthesized polyazomethines are dissolved in a solvent, a solution is applied onto a substrate such as a glass substrate, and then the solvent is removed by heating to form a polymer film made of polyazomethines. . An example of a solvent that dissolves polyazomethines is dimethylacetamide. When removing the solvent by heating, polyazomethines are easily oxidized by heating and denatured, so it is desirable to adjust the heating temperature and heating atmosphere.
When it is not desired to modify the polyazomethines, the heating atmosphere is preferably a non-oxidizing atmosphere such as a reduced pressure atmosphere or an inert gas atmosphere. In addition, when a part of the polyazomethines is modified, the heating atmosphere may be an oxidizing atmosphere such as air.

  Next, the polyazomethines are impregnated with an acid by immersing a polymer film made of the polyazomethines in an acid aqueous solution. In this way, a membrane-like polymer electrolyte is obtained.

  In addition, when polyazomethines are dissolved in a solvent and applied onto a glass substrate, an acid may be mixed in advance with the polyazomethines together with the solvent, and this mixed solution may be applied onto the glass substrate. After coating, the solvent is removed by heating in the same manner as described above. In this way, a polymer electrolyte is obtained. According to this method, a polymer film made of polyazomethines can be formed and simultaneously impregnated with an acid, and the manufacturing process can be simplified.

  As described above, according to the polymer electrolyte of the present embodiment, excellent thermal stability and high proton conductivity can be exhibited.

"Fuel cell"
In FIG. 1, the schematic diagram of the single cell which comprises the fuel cell of this embodiment is shown. A single cell 1 shown in FIG. 1 includes an oxygen electrode 2, a fuel electrode 3, a polymer electrolyte 4 sandwiched between the oxygen electrode 2 and the fuel electrode 3 (hereinafter may be referred to as an electrolyte membrane 4). And an oxidant distribution plate 5 having an oxidant flow path 5a disposed outside the oxygen electrode 2 and a fuel distribution plate 6 having a fuel flow path 6a disposed outside the fuel electrode 3, and operating temperature. It operates under conditions of 100 ° C. to 200 ° C. and no humidity or relative humidity of 50% or less.

  The fuel electrode 3 and the oxygen electrode 2 are each generally composed of porous catalyst layers 2a and 3a and porous carbon sheets (carbon porous bodies) 2b and 3b that hold the catalyst layers 2a and 3a. The catalyst layers 2a and 3a contain an electrode catalyst (catalyst), a hydrophobic binder for solidifying and molding the electrode catalyst, and a conductive material.

  The catalyst is not particularly limited as long as it is a metal that promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen. For example, lead, iron, manganese, cobalt, chromium, gallium, vanadium, tungsten, ruthenium, iridium, palladium, platinum, There may be mentioned rhodium or an alloy thereof. An electrode catalyst can be constituted by supporting such a metal or alloy on activated carbon.

  For example, a fluororesin can be used as the hydrophobic binder. Among the fluororesins, those having a melting point of 400 ° C. or less are preferable. Examples of such fluororesins include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride, tetrafluoroethylene / hexafluoroethylene copolymer. A resin excellent in hydrophobicity and heat resistance such as a polymer and perfluoroethylene can be used. By adding the hydrophobic binder, it is possible to prevent the catalyst layers 2a and 3a from being wetted excessively by the water generated in response to the power generation reaction, and the fuel gas and oxygen in the fuel electrode 3 and the oxygen electrode 2 can be prevented. Can be prevented.

  Further, the conductive material may be any material as long as it is an electrically conductive material, and examples thereof include various metals and carbon materials. Examples thereof include carbon black such as acetylene black, activated carbon and graphite, and these are used alone or in combination.

  The catalyst layers 2a and 3a may contain the polymer electrolyte according to the present invention instead of the hydrophobic binder or together with the hydrophobic binder. By adding the polymer electrolyte according to the present invention, the proton conductivity in the fuel electrode 3 and the oxygen electrode 2 can be improved, and the internal resistance of the fuel electrode 3 and the oxygen electrode 2 can be reduced.

The oxidant distribution plate 5 and the fuel distribution plate 6 are made of conductive metal or the like, and function as a current collector by being joined to the oxygen electrode 2 and the fuel electrode 3 respectively. Oxygen and fuel gas are supplied to the pole 3. That is, the fuel electrode mainly containing hydrogen is supplied to the fuel electrode 3 through the fuel flow path 6 a of the fuel flow distribution plate 6, and the oxidant flow path 5 a of the oxidant flow distribution plate 5 is supplied to the oxygen electrode 2. Through this, oxygen as an oxidizing agent is supplied.
The hydrogen supplied as fuel may be supplied by hydrogen generated by reforming hydrocarbon or alcohol, and oxygen supplied as oxidant is supplied in a state of being contained in air. Also good.

  In this single cell 1, hydrogen is oxidized on the fuel electrode 3 side to generate protons, which are conducted through the electrolyte membrane 4 to reach the oxygen electrode 2, and protons and oxygen are electrochemically connected to the oxygen electrode 2. It reacts to produce water and generates electrical energy.

  According to the above fuel cell, it is possible to obtain a fuel cell that stably exhibits good power generation performance for a long period of time even when the operating temperature is 100 ° C. or higher and 200 ° C. or lower and no humidification or relative humidity is 50% or less, It can be suitably used for automobiles, home power generation or portable devices.

Hereinafter, the present invention will be described more specifically with reference to examples.
The characteristics of the fuel cell are that the electrolyte membrane is sandwiched between commercially available fuel cell electrodes (Electrochem) to form a membrane electrode assembly, and the fuel cell is operated with hydrogen / air under conditions of 150 ° C. and no humidification. evaluated.

Example 1
Using 3,3′-diaminobenzidine and isophthalaldehyde as raw materials, a polyazomethine having the following structural formula (6) was synthesized according to the reaction scheme of the above formula (4).
The obtained polyazomethine was dissolved in dimethylacetamide (DMAc), this solution was cast on a glass substrate and dried at 60 ° C. under reduced pressure for 3 hours to obtain an orange polymer film having a thickness of 30 μm. It was. Subsequently, the polymer electrolyte membrane of Example 1 was manufactured by immersing in 20% phosphoric acid and doping phosphoric acid for 1 hour.

The polymer electrolyte membrane of Example 1 had a phosphoric acid doping rate of 150% by mass.
Further, the obtained polymer electrolyte membrane was sandwiched between circular platinum electrodes (diameter 13 mm), and the temperature dependence of ion conductivity was evaluated from the solution resistance obtained from the complex impedance measurement. The results are shown in FIG.

Furthermore, the obtained polymer electrolyte membrane was incorporated into a fuel cell as described above, and the power generation characteristics were evaluated. Hydrogen was supplied as fuel and air as oxidant was supplied to the fuel cell, and a power generation test was conducted at 150 ° C. Table 1 shows the open circuit voltage before starting the power generation of the fuel cell and the output voltage at a current density of 0.3 A / cm ² .

(Example 2)
1.25 g of polyazomethine obtained by the same method as in Example 1 and 0.174 g of ethylene glycol diglycidyl ether (low molecular cross-linking agent) were dissolved in 15 ml of DMAc, this solution was cast on a glass substrate, By drying at 60 ° C. for 3 hours, an orange film having a thickness of 30 μm was obtained. Subsequently, the polymer electrolyte membrane of Example 2 was manufactured by immersing in 20% phosphoric acid and doping phosphoric acid for 1 hour.
The doping rate of the polymer electrolyte membrane of Example 2 was 184% by mass.

Using this polymer electrolyte membrane, power generation characteristics were measured as a fuel cell in the same manner as in Example 1. The results are shown in Table 1. As shown in Table 1, the ion conductivity at 150 ° C. was 2.6 × 10 ⁻⁴ Scm ⁻¹ . Table 1 shows the open circuit voltage and the output voltage at a current density of 0.3 A / cm ² .

(Example 3)
1.25 g of polyazomethine obtained by the same method as in Example 1 and 0.252 g of 4,4′-oxybis (phenylisocyanate) (low molecular crosslinking agent) were dissolved in 15 ml of DMAc, and this solution was dissolved in a glass substrate. Casting up and drying at 60 ° C. for 3 hours under reduced pressure, an orange film having a thickness of 30 μm was obtained. Subsequently, the polymer electrolyte membrane of Example 3 was manufactured by immersing in 20% phosphoric acid and doping phosphoric acid for 1 hour.
The polymer electrolyte membrane of Example 3 had a phosphoric acid doping rate of 263 mass%.
Further, using this polymer electrolyte membrane, power generation characteristics were measured as a fuel cell in the same manner as in Example 1. The results are shown in Table 1. As shown in Table 1, the ion conductivity at 150 ° C. was 3.1 × 10 ⁻³ Scm ⁻¹ . Table 1 shows the open circuit voltage and the output voltage at a current density of 0.3 A / cm ² .

Example 4
1.25 g of polyazomethine obtained by the same method as in Example 1 and 0.218 g of pyromellitic dianhydride (low molecular crosslinking agent) were dissolved in 15 ml of DMAc, this solution was cast on a glass substrate, The film was dried at 60 ° C. for 3 hours to obtain an orange film having a thickness of 30 μm. Subsequently, the polymer electrolyte membrane of Example 4 was manufactured by immersing in 20% phosphoric acid and doping phosphoric acid for 1 hour.
The polymer electrolyte membrane of Example 4 had a phosphoric acid doping rate of 235% by mass.
Further, using this polymer electrolyte membrane, power generation characteristics were measured as a fuel cell in the same manner as in Example 1. The results are shown in Table 1. As shown in Table 1, the ion conductivity at 150 ° C. was 7.5 × 10 ⁻⁴ Scm ⁻¹ . Table 1 shows the open circuit voltage and the output voltage at a current density of 0.3 A / cm ² .

(Comparative Example 1)
Based on the technique disclosed in US Pat. No. 5,525,436, poly-2,2 ′-(m-phenylene) -5,5′-bibenzimidazole is immersed in 20% phosphoric acid and is taken for 1 hour. A polymer electrolyte membrane of Comparative Example 1 was produced by doping phosphoric acid.
The phosphoric acid doping rate of Comparative Example 1 was 200 mass%.
Further, when the ionic conductivity of the polymer electrolyte membrane of Comparative Example 1 was determined in the same manner as in Example 1, it was 8.0 × 10 ⁻⁶ Scm ⁻¹ . Further, measurement of power generation characteristics as a fuel cell was attempted by the same method as in Example 1, but the cell resistance was high and power generation was impossible.

(Example 6)
An orange polymer film having a thickness of 30 μm was prepared in the same manner as in Example 1 except that, when a solution of polyazomethine dissolved in DMAc was cast on a glass substrate, it was dried in the atmosphere at 60 ° C. for 3 hours. Got.

  About the obtained polymer film, the infrared spectrum was measured by the infrared spectrophotometry. The results are shown in FIG. FIG. 4 shows an infrared spectrum of the polymer film in Example 1.

As shown in FIGS. 3 and 4, when a solution containing polyazomethine is cast on a glass substrate, there is a large difference in the infrared spectrum depending on whether it is dried in the air or in a vacuum. I understand that. Specifically, in the infrared spectrum of Example 1 that was not air-oxidized (FIG. 4), an absorption peak near 1489 cm ⁻¹ derived from the NH ₂ group bonded to the benzene ring can be confirmed. In FIG. 4, the absorption peak around ^{3300cm -1 ~3460cm} -1 derived from the NH ₂ group can also be confirmed. On the other hand, in the infrared spectrum of Example 6 is air oxidized (FIG. 3), and the absorption peak in the vicinity of 1489cm ^-1, absorption peaks in the vicinity of 3300cm ^-1 ~3460cm -1 can not be confirmed. This is presumably because the NH ₂ group bonded to the benzene ring was reacted by air oxidation to form a nitrogen-containing carbocyclic structure. From the above results, it can be seen that the polyazomethines are denatured by drying in the air.

FIG. 1 is a schematic cross-sectional view showing the structure of a single cell of a fuel cell according to an embodiment of the present invention. FIG. 2 is a graph showing the temperature dependence of proton conductivity of the polymer electrolyte membrane of Example 1. FIG. 3 is an infrared spectrum of the polymer film in Example 6. FIG. 4 is an infrared spectrum of the polymer film in Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Single cell (fuel cell), 2 ... Oxygen electrode (electrode), 3 ... Fuel electrode (electrode), 4 ... Electrolyte membrane (proton conductive solid polymer electrolyte)

Claims (7)

A proton comprising an acid and a polymer compound impregnated with the acid, wherein the polymer compound is a polyazomethine having a repeating unit represented by the following general formula (1) Conductive solid polymer electrolyte.
However, in the general formula (1), R ₁ is hydrogen atom, an alkyl group, or a aryl group, R ₂ represents a hydrogen atom, an alkyl group, or a allyl group, X is an arylene group , N indicating the number of repetitions is an integer in the range of 100 to 100,000.

In the general formula (1), R ₁ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an allyl group, and R ₂ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, allyl is any one of groups, X is either phenylene group, tolylene group, xylylene group, biphenylene group, naphthyl alkylene group, Antori alkylene group, Fenantori alkylene radical, n is 100 or indicating the number of repetitions The proton conductive solid polymer electrolyte according to claim 1, wherein the proton conductive solid polymer electrolyte is an integer in the range of 100,000. The proton-conducting solid polymer electrolyte according to claim 1 or 2, wherein a part of the polyazomethines is heated and oxidized to form a nitrogen-containing carbocyclic structure . The crosslinked structure by a low molecular crosslinking agent is formed, and the low molecular crosslinking agent is a compound selected from a diacid anhydride, a diepoxy compound, and a diisocyanate. Proton-conducting solid polymer electrolyte. The proton conductive solid polymer electrolyte according to any one of claims 1 to 4 , wherein the acid is phosphoric acid, phosphonic acid, or a mixture thereof. Provided with an oxygen electrode, a fuel electrode, and a polymer electrolyte membrane sandwiched between both electrodes, an oxidant distribution plate having an oxidant flow path formed on the oxygen electrode side, and a fuel flow distribution plate having a fuel flow path formed on the fuel electrode side 6. A fuel cell comprising a unit cell as a unit cell, wherein the polymer electrolyte membrane comprises the proton conductive solid polymer electrolyte according to any one of claims 1 to 5 . Either or both of the oxygen electrode or the fuel electrode, according to claim 6, characterized in that it contains the proton conductive solid polymer electrolyte according to any one of claims 1 to 5 Fuel cell.

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