KR100754375B1 - Proton conductive solid polymer electrolyte and fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a proton conductive solid polymer electrolyte and a fuel cell having the same, and specifically, an acid and a polyazo containing a polymer compound impregnated with the acid, wherein the polymer compound has a repeating unit represented by the following Chemical Formula 1 It relates to a proton conductive solid polymer electrolyte characterized in that the methine and a fuel cell having the same:

However, in the following general formula (1), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group or an allyl group, X is an aryl group, and n is an integer of 100 to 100,000.

<Formula 1>

According to the present invention, it is possible to provide a fuel cell stably exhibiting long-term stable power generation performance at an operating temperature of about 100 ° C. to 200 ° C. under operating conditions of no humidification or a relative humidity of 50% or less.

 Polyazomethine, proton conductive solid polymer electrolyte, fuel cell

Description

Proton conductive solid polymer electrolyte and fuel cell comprising the same

1 is a schematic cross-sectional view showing a unit cell structure of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a graph showing temperature dependence of proton conductivity in the polymer electrolyte membrane according to Example 1. FIG.

3 is an infrared spectrum graph of a polymer film according to Example 6.

4 is an infrared spectrum graph of a polymer film according to Example 1. FIG.

<Brief description of reference numerals>

One … Unit cell (fuel cell)

2 … Oxygen electrode (electrode)

3…. Fuel electrode (electrode)

4 … Electrolyte Membrane (Proton Conductive Solid Polymer Electrolyte)

The present invention relates to a proton conductive solid polymer electrolyte and a fuel cell having the same, and has a power generation performance that works well under operating conditions of 50% or less relative humidity or 50% relative humidity at an operating temperature of about 100 ° C to 200 ° C. The present invention relates to a fuel cell exhibiting long-term stability.

Conventionally, as a proton conductive electrolyte for a solid polymer fuel cell, in terms of system efficiency and long-term durability of a component, at an operating temperature of about 100 ° C. to 300 ° C., under low humidity or low humidity operation conditions of 50% or less relative humidity. There is a need for a proton conductor that exhibits good proton conductivity over a long period of time. In the development of a conventional solid polymer fuel cell, various studies have been carried out in view of the above requirements, but in a solid polymer fuel cell using a perfluoro carbon sulfonic acid membrane as an electrolyte membrane, at an operating temperature of 100 ° C to 300 ° C, There was a defect that sufficient power generation performance could not be obtained at a relative humidity of 50% or less.

Furthermore, those containing a proton conductivity imparting agent (see, for example, Japanese Patent Application Laid-Open No. 2001-035509), those using a silica dispersion film (see, for example, Japanese Patent Application Laid-Open No. 06-111827), and an inorganic-organic composite film. (See, for example, Japanese Patent Application Laid-Open No. 2000-090946.), Using a graft film doped with phosphoric acid (see, for example, Japanese Patent Application Laid-Open No. 2001-213987), or using an ionic liquid composite membrane (e.g. Although there exist prior arts such as 2001-167629.), All of them have a problem that sufficient power generation performance can not be stably exhibited for a long time under an operating environment of 100 ° C to 300 ° C under a humidification or a relative humidity of 50% or less. There was this.

On the other hand, U.S. Patent No. 5525436 discloses a solid polymer fuel cell that exhibits sufficient power generation performance even at a high temperature up to 200 ° C by using a polymer electrolyte membrane made of polybenzimidamide sol doped with a strong acid such as phosphoric acid. Since impregnated with 4 times of phosphoric acid is used, it is difficult to maintain stable power generation performance for a long time.

The present invention is to solve the problems of the prior art, at an operating temperature of about 100 ℃ to 200 ℃, can exhibit a long-term stable generation performance that works well under operating conditions of less than 50% relative humidity or relative humidity. An object of the present invention is to provide a proton conductive solid polymer electrolyte and a fuel cell having the electrolyte.

In order to achieve the above object, the present invention in one aspect,

A proton conductive solid polymer electrolyte comprising an acid and a polymer compound impregnated with the acid, wherein the polymer compound is a polyazomethine having a repeating unit represented by Formula 1 below:

(In formula (1), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, or an allyl group, X is an aryl group, and n is an integer of 100 to 100,000.)

To provide.

In order to achieve the above object, the present invention in another aspect,

A fuel cell comprising a polymer electrolyte membrane sandwiched between an oxygen electrode, a fuel electrode, and a positive electrode, provided with an oxidant bipolar plate on which an oxidant flow path is formed on an oxygen electrode side, and a fuel bipolar plate on which a fuel flow path is formed on a fuel electrode side. In the fuel cell, the polymer electrolyte membrane is a proton conductive solid polymer electrolyte.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

[Proton Conductive Solid Polymer Electrolyte]

The proton conductive solid polymer electrolyte (hereinafter referred to as polymer electrolyte) of the present embodiment contains an acid and a polymer compound impregnated with the acid. The high molecular compound is polyazomethine which has a repeating unit represented by the said Formula (1). In the polymer electrolyte of the present embodiment, an acid is impregnated (doped) with a polymer compound made of polyazomethines. In the polymer electrolyte of the present embodiment, a crosslinked structure in which main chains of polyazomethines are crosslinked by a low molecular crosslinking agent may be formed.

Hereinafter, the component which comprises the polymer electrolyte of this embodiment is demonstrated.

(Polyazomethine)

As described above, polyazomethines are polymers having a repeating unit represented by Chemical Formula 1. Such polyazomethines have an amine group bonded to a phenyl group, as shown in the formula (1), and the acid is doped into the polyazomethines by the interaction of the amine group and the acid, thereby determining the expression of proton conductivity. In addition, polyazomethines have a double bond of nitrogen-carbon that binds to a phenyl group, and thermal stability is imparted to the polyazomethines due to the presence of the double bond of nitrogen-carbon, thereby providing heat resistance of the polymer electrolyte. It is judged that this is improved.

In formula (1), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, or an allyl group, X is an aryl group, and n, which represents a repeating number, is an integer of 100 to 100,000. More preferably, R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an allyl group, and X is a phenyl group, tolyl group, xylyl group, biphenyl group, naphthyl group, anthryl group or It is a phenanthryl group, n is an integer of 100-100,000. Especially preferably, R <_1> and R <_2> is a hydrogen atom, X is a phenyl group, n is an integer of 100-100,000.

When R <_1> and R <_2> are substituted by substituents other than the above, since the thermal stability of polyazomethines falls by interaction with the amino group couple | bonded with a phenyl group, it is unpreferable. Moreover, when X is substituted by the substituent of that excepting the above, since the thermal stability of polyazomethines falls, it is unpreferable. Furthermore, when n which represents a repeating number is less than 100, since the mechanical strength of a polymer electrolyte falls, it is unpreferable, and when n exceeds 100,000, the solubility to the solvent of polyazomethines falls, and so-called It is not preferable because the moldability of polyazomethines by the casting method is lowered and it becomes difficult to make the polymer electrolyte into a desired shape.

In addition, the polyazomethine of this embodiment may be partially denatured by heat oxidation. As described above, polyazomethines have excellent thermal stability due to the presence of a double bond of nitrogen-carbon, and also proton conductivity is expressed by the interaction of an amine group and an acid, but on the other hand, in particular, R ₁ or R ₂ When either is a hydrogen atom, dehydration reaction by heat oxidation easily occurs between the nitrogen-carbon double bond and the amine group in the presence of oxygen. This dehydration reaction is a reaction in which water is produced by combining R ₁ or R ₂ (hydrogen atoms) bonded to carbon of a nitrogen-carbon double bond with hydrogen of oxygen and amine groups in the atmosphere. By this reaction, the nitrogen-carbon double bond becomes a single bond, and furthermore, the nitrogen atom of the amine group is bonded to the carbon atom of the nitrogen-carbon bond to form a nitrogen-containing carbocyclic structure. In Formulas 2 and 3, an example of a structure in which polyazomethines are modified by heating and oxidizing them is shown.

Such modification is likely to occur under conditions in which polyazomethines are heated to about 60 ° C. in the presence of oxygen. Under conditions where oxygen is not present, no modification occurs even when heated to about 60 ° C. In addition, about the polyazomethine doped with acid, it is presumed that an amine group is protected by an acid, and even if it heats at about 60 degreeC in presence of oxygen, a modification does not occur easily.

In addition, R ₁ and R ₂ is a need exists in the case other than a hydrogen atom, so that heated to 60 ℃ presence of oxygen is difficult to occur degeneration, R ₁ group and an R ₂ group catalyst such as ferric chloride for subtraction Done.

It is preferable that this modified structure exists in a part of polyazomethines, and it is not preferable that the whole polyazomethines are modified. By modifying a part of the polyazomethines, the thermal stability and the solvent resistance of the polyazomethines are improved, and stable proton conductivity can be expressed even in a relatively high temperature atmosphere such as a fuel cell. On the other hand, when the entire polyazomethine is denatured, the amine group is lost, the impregnation rate (doping rate) of the acid is greatly reduced, and the proton conductivity is not preferable.

(mountain)

The acid in the present embodiment refers to phosphoric acid, phosphonic acid, sulfuric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, trifluoromethanesulfoimic acid, phosphotungstic acid, and the like. From the viewpoint, phosphoric acid and phosphonic acid or mixtures thereof are preferred. All of these acids interact with the amine groups of the polyazomethines to impregnate (dope) the polyazomethines to express proton conductivity. The acid doping ratio with respect to polyazomethines also depends on the kind of acid, but the range of 50% or more and 400% or less is preferable, and the range of 100% or more and 300% or less is more preferable. If the doping rate is too low, it is not preferable because the proton conductivity is lowered. If the doping rate is too high, the mechanical strength of the solid polymer electrolyte is lowered, which is not preferable.

(Low molecular weight crosslinking agent)

Moreover, in the solid polymer electrolyte of this embodiment, the crosslinked structure by the low molecular crosslinking agent may be formed. As a low molecular crosslinking agent, the compound chosen from diacid anhydride, a diepoxy compound, and a diisocyanate is preferable. These low molecular weight crosslinking agents form a crosslinked structure in which main chains of polyazomethines are crosslinked, and the mechanical strength of the polymer electrolyte is further improved. The crosslinking reaction mainly occurs for amine groups of polyazomethines, and amine groups of adjacent molecular chains are crosslinked to stabilize the molecular structure of the entire polyazomethines.

Examples of the diacid anhydride include dianhydride pyromellitic acid, cyclobutene dicarboxylic acid anhydride, and derivatives thereof.

Moreover, an ethylene glycol diglycidyl ether, 2, 2-bis (4-glycidyl oxyphenyl) propane etc. are mentioned as a diepoxy compound.

Furthermore, as diisocyanate, diphenylmethane diisocyanate (henceforth MDI), 4, 4- diphenyl ether diisocyanate (ODI), triylene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, hexafluoro biphenyl Diisocyanate, hexamethylene diisocyanate, lidin diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, etc. are mentioned. Furthermore, these derivatives can also be used.

In addition, it is preferable that the mixing ratio (low molecular crosslinking agent / polyazomethine) of these low molecular weight crosslinking agents and polyazomethines is mixed in 1/5 (mol / mol)-1/3 (mol / mol) ratio. If the low molecular weight crosslinking agent is more than this, gelation advances and it becomes difficult to shape a polymer electrolyte into a film form.

(Method for Producing Polymer Electrolyte)

The method for producing a polymer electrolyte comprises a step of synthesizing polyazomethines and a step of molding the synthesized polyazomethines into, for example, a film, and impregnating polyazomethines with acid.

The method for synthesizing polyazomethines is, for example, diamines such as 3,3.-diaminobenzidine and isophthal, as described in, for example, Macromolecules, vol. 16, No. 1 (1983) 128-136. It is obtained by reacting dialdehydes, such as an aldehyde. A summary of the reaction is shown in Scheme 1 below.

In addition, in the case where R ₁ or R ₂ in the general formula (1) is an alkyl group such as a methyl group, as shown in the following Scheme 2, diamines such as 3,3'-diaminobenzidine and dike such as 1,4-diacetylbenzene Obtained by reacting tones. In the following scheme 2, R ₁ and R ₂ are methyl groups. When introducing another alkyl group, the methyl group bonded to the carbonyl group of the diketone in the following scheme 2 may be another alkyl group.

As the diamine in Schemes 1 and 2, 3,3'-diaminobenzidine is preferable. As the dialdehyde, in addition to isophthalaldehyde, terephthalaldehyde, 9,10-diformylanthracene, 4,4.-diformylbiphenyl and the like can be used. Furthermore, in addition to 1, 4- diacetyl benzene, 1, 3- diacetyl benzene etc. can be used as a diketone.

Next, the synthesized polyazomethine is dissolved in a solvent, a solution is applied onto a substrate such as a glass substrate, and then heated to remove the solvent to form a polymer film made of polyazomethine. As a solvent which melt | dissolves polyazomethines, dimethylacetamide can be illustrated, for example. When removing a solvent by heating, since polyazomethines are easily heat-oxidized and denatured, it is preferable to adjust heating temperature and a heating atmosphere.

When not modifying polyazomethines, it is preferable to make heating atmosphere into non-oxidizing atmosphere, such as a reduced pressure atmosphere or an inert gas atmosphere. In addition, what is necessary is just to make heating atmosphere into oxidative atmospheres, such as air, when modifying a part of polyazomethines.

Next, the polyazomethine is impregnated with an acid by dipping the polymer membrane made of polyazomethine into an aqueous solution of acid. In this way, a polymer electrolyte in the form of a membrane can be obtained.

In addition, when dissolving polyazomethines in a solvent and apply | coating on a glass substrate, an acid is mixed with a solvent in advance with a polyazomethine, and this mixed solution can also be apply | coated on a glass substrate. After coating, the solvent is heated in the same manner as above to remove the solvent. In this way, a polymer electrolyte is obtained. According to this method, a polymer film made of polyazomethines can be formed, and an acid can be impregnated, thereby simplifying the manufacturing process.

As described above, the polymer electrolyte of the present embodiment can exhibit excellent thermal stability and high proton conductivity.

`` Fuel battery ''

1, the schematic diagram of the unit cell which comprises the fuel cell of this embodiment is shown. The unit cell 1 shown in FIG. 1 includes a polymer electrolyte 4 (hereinafter, referred to as an electrolyte membrane 4) sandwiched between an oxygen electrode 2, a fuel electrode 3, and an oxygen electrode 2 and a fuel electrode 3. ), The oxidant bipolar plate 5 having the oxidant flow path 5a disposed outside the oxygen electrode 2, and the fuel flow path 6a disposed outside the fuel electrode 3, respectively. It consists of the excitation fuel bipolar plate 6, and it operates on the conditions of 100 degreeC-200 degreeC of operating temperature, and a temperature of 50 degrees or less of humidification or relative humidity.

The fuel electrode 3 and the oxygen electrode 2 are each composed of porous catalyst layers 2a and 3a and porous carbon sheets (carbon porous bodies) 2b and 3b holding the catalyst layers 2a and 3a, respectively. . The catalyst layers 2a and 3a contain an electrode catalyst (catalyst), a hydrophobic binder for solidifying 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, rhodium Or their alloys. The electrocatalyst can be constituted by supporting such a metal or alloy on activated carbon.

As the hydrophobic binder, for example, a fluororesin can be used. It is preferable that melting | fusing point is 400 degrees C or less among fluororesins, and, as such a fluororesin, a poly-4- fluoride, a tetrafluoroethylene- perfluoroalkyl vinyl ether copolymer, a polyvinylidene fluoride, and tetrafluoroethylene. Resin excellent in hydrophobicity and heat resistance, such as a hexafluoroethylene copolymer and a perfluoroethylene, can be used. By adding a hydrophobic binder, it is possible to prevent the catalyst layers 2a and 3a from overflowing too much by the water generated along with the power generation reaction, and the fuel gas and oxygen inside the fuel electrode 3 and the oxygen electrode 2 can be prevented. Can inhibit the diffusion of

Furthermore, as an electrically conductive material, any electrically conductive material may be sufficient, and various metals, carbon materials, etc. are mentioned. For example, carbon black, such as acetylene black, activated carbon, graphite, etc. are mentioned, These are used individually or in mixture.

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 bipolar plate 5 and the fuel bipolar plate 6 are made of a conductive metal or the like, and function as a current collector by being bonded to the oxygen electrode 2 and the fuel electrode 3, respectively, and at the same time, the oxygen electrode 2 ) And the fuel electrode 3 are supplied with oxygen and fuel gas. That is, a fuel gas mainly composed of hydrogen is supplied to the fuel electrode 3 through the fuel flow path 6a of the fuel bipolar plate 6, and the oxidant flow path of the oxidant bipolar plate 5 is supplied to the oxygen electrode 2. Oxygen as oxidant is supplied via 5a). In addition, the hydrogen supplied as a fuel may be one supplied with hydrogen generated by the reforming of a hydrocarbon or an alcohol, and the oxygen supplied as an oxidant may be supplied while being contained in air.

In such a unit cell 1, hydrogen is oxidized on the fuel electrode 3 side to produce protons, which proton conducts the electrolyte membrane 4 to reach the oxygen electrode 2, and protons in the oxygen electrode 2 And oxygen react electrochemically to generate water and generate electrical energy.

According to the fuel cell, it is possible to obtain a fuel cell stably exhibiting good power generation performance for a long time even when the operating temperature is 100 ° C or more and 200 ° C or less, even when no humidification or relative humidity is 50% or less. It can be used effectively.

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

In addition, the characteristics of the fuel cell were evaluated by sandwiching the electrolyte membrane with a commercially available fuel cell electrode (Electrochem Co., Ltd.) to form a membrane electrode junction, and performing fuel cell operation in hydrogen / air under 150 ° C and a non-humidity condition.

(Example 1)

Using 3,3'-diaminobenzidine and isophthalaldehyde as raw materials, polyazomethine having the following formula (4) was synthesized according to the reaction scheme of Scheme 1.

The obtained polyazomethine was dissolved in dimethylacetamide (DMAc), the solution was cast on a glass substrate, and dried under reduced pressure at 60 ° C. for 3 hours to obtain an orange polymer film having a thickness of 30 μm. Subsequently, the polymer electrolyte membrane of Example 1 was prepared by immersing in 20% phosphoric acid and doping phosphoric acid over 1 hour.

The doping rate of phosphoric acid in the polymer electrolyte membrane of Example 1 was 150 mass%.

In addition, the obtained polymer electrolyte membrane was sandwiched by a circular platinum electrode (diameter 13 mm), and the temperature dependence of the ion conductivity was evaluated from the solution resistance obtained by the complex impedance measurement, and the results are shown in FIG. 2 and Table 1. FIG.

Further, the obtained polymer electrolyte membrane was included in the fuel cell as described above to evaluate the power generation characteristics. Hydrogen as a fuel and air as an oxidant were respectively supplied to the fuel cell, and a power generation test was conducted at 150 ° C. In Table 1, the open circuit voltage before the start of power generation of the fuel cell is shown, and the output voltage at the current density of 0.3 A / cm ² is shown.

(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 weight crosslinking agent) were dissolved in 15 ml of DMAc, and this solution was cast on a glass substrate, which was then subjected to 60 ° C under reduced pressure. By drying for 3 hours, an orange film having a thickness of 30 μm was obtained. Subsequently, the polymer electrolyte membrane of Example 2 was prepared by immersing in 20% phosphoric acid and doping phosphoric acid over 1 hour.

The doping rate of the polymer electrolyte membrane of Example 2 was 184 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 also 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 (phenylisocyanat) (low molecular weight crosslinking agent) are dissolved in 15 ml of DMAc, and the solution is cast on a glass substrate. And it dried under reduced pressure at 60 degreeC for 3 hours, and obtained the orange film of 30 micrometers in thickness. Subsequently, the polymer electrolyte membrane of Example 3 was prepared by immersing in 20% phosphoric acid and doping phosphoric acid over 1 hour.

The doping rate of phosphoric acid in the polymer electrolyte membrane of Example 3 was 263 mass%.

In addition, power generation characteristics were measured as a fuel cell in the same manner as in Example 1 using this polymer electrolyte membrane. 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 also 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 dianhydrous pyromellitic acid (low molecular weight crosslinking agent) were dissolved in 15 ml of DMAc, and the solution was cast on a glass substrate, and the solution was dried at 60 ° C. under reduced pressure for 3 hours. By drying, an orange film having a thickness of 30 μm was obtained. Subsequently, the polymer electrolyte membrane of Example 4 was prepared by immersing in 20% phosphoric acid and doping phosphoric acid over 1 hour. The doping rate of phosphoric acid in the polymer electrolyte membrane of Example 4 was 235 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 7.5 × 10 ⁻⁴ Scm ⁻¹ . Table 1 also 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 U.S. Patent 5,525,436, poly-2,2 '-(m-phenylene) -5,5'-bibenzimidazole is immersed in 20% phosphoric acid and in 1 hour The polymer electrolyte membrane of Comparative Example 1 was prepared by doping phosphoric acid over.

The doping rate of phosphoric acid of Comparative Example 1 was 200 mass%.

Further, the polymer electrolyte membrane of Comparative Example 1 was determined in the same manner as in Example 1 to determine ion conductivity, which was 8.0 × 10 ⁻⁶ Scm ⁻¹ . Furthermore, although the measurement of the power generation characteristics was tested as a fuel cell by the same method as in Example 1, power generation was impossible due to the high cell resistance.

Doping Rate (mass%) Ion Conductivity at 150 ℃ (Scm ^-1 ) Open circuit voltage (V) Voltage at 0.3Acm ^-2 output (V) Example 1 150 3.7 × 10 ^-4 0.815 0.18 Example 2 184 2.6 × 10 ^-4 0.825 0.19 Example 3 263 3.1 × 10 ^-8 0.932 0.19 Example 4 235 7.5 × 10 ^-4 0.844 0.19 Comparative Example 1 200 8.0 × 10 ^-6 0.981 Not developing

(Example 6)

When casting the solution which polyazomethine melt | dissolved in DMAc on the glass substrate, it carried out similarly to Example 1 except having dried for 3 hours at 60 degreeC in air, and obtained the orange polymer membrane of 30 micrometers in thickness.

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

As shown to FIG. 3 and 4, when casting the solution containing a polyazomethine on a glass substrate, it turns out that a big difference arises in an infrared spectrum according to whether it dries in air | atmosphere or in vacuum. Specifically, in the infrared spectrum (FIG. 4) of Example 1 which is not air oxidized, the absorption peak near 1489 cm <^-1> derived from NH2 group _{couple |} bonded with the benzene ring can be confirmed. Alternatively, in Figure 4 it can also be found the absorption peak of 3300cm ^-1 ~3460cm ^-1 vicinity derived from the group NH _2. On the other hand, in the air-IR spectrum (FIG. 3) of the oxide Example 6, the absorption peak of 1489cm ^-1, or near, the absorption peak of 3300cm ^{-1 -1} ~3460cm vicinity can not identify. This is presumably due to the formation of a nitrogen-containing carbocyclic structure by reaction of NH ₂ groups bound to the benzene ring by air oxidation. From the above result, it turns out that the denaturation of polyazomethines occurs by drying in air | atmosphere.

According to the present invention, even when the operating temperature is 100 DEG C or higher and 200 DEG C or lower, no humidification or a relative humidity of 50% or less, by using a proton conductive solid polymer electrolyte in which a small amount of acid is doped, a solid exhibiting good power generation performance stably for a long time A polymer fuel cell can be obtained.

Claims (8)

A proton conductive solid polymer electrolyte comprising an acid and a polymer compound impregnated with the acid, wherein the polymer compound is a polyazomethine having a repeating unit represented by Formula 1 below: However, in the following general formula (1), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group or an allyl group, X is an aryl group, and n is an integer of 100 to 100,000. <Formula 1>

The R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an allyl group, and wherein X is a phenyl group, tolyl group, xylyl group, biphenyl group, naphthyl group, and Proton conductive solid polymer electrolyte, characterized in that the trin or phenanthryl group, n is an integer of 100 to 100,000. The proton conductive solid polymer electrolyte of claim 1, wherein a part of the polyazomethines is oxidized and denatured. The proton conductive solid polymer electrolyte of claim 1, wherein the polymer compound has a crosslinked structure formed by a low molecular crosslinker. The proton conductive solid polymer electrolyte according to claim 4, wherein the low molecular crosslinking agent is a compound selected from the group consisting of diacid anhydride, diepoxy compound and diisocyanate. The proton conductive solid polymer electrolyte of claim 1, wherein the acid is phosphoric acid, phosphonic acid or a mixture thereof. A fuel cell comprising a polymer electrolyte membrane sandwiched between an oxygen electrode, a fuel electrode, and a positive electrode, provided with an oxidant bipolar plate on which an oxidant flow path is formed on an oxygen electrode side, and a fuel bipolar plate on which a fuel flow path is formed on a fuel electrode side. The fuel cell according to claim 1, wherein the polymer electrolyte membrane is a proton conductive solid polymer electrolyte according to any one of claims 1 to 6. The fuel cell according to claim 7, wherein the proton conductive solid polymer electrolyte is contained in one or both of the oxygen electrode and the fuel electrode.

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