KR100695115B1 - Proton conductive electrolyte for fuel cell, method for preparing the same and electrode using the proton conductive electrolyte - Google Patents

Abstract

Provided are a proton conductive solid polymer electrolyte which shows a satisfactory power generation stably for a long time, its preparation method, and a fuel cell containing the polymer electrolyte. The proton conductive solid polymer electrolyte comprises a matrix resin which has an amide bond structure; and a cationic compound which is infiltrated in the matrix resin. Preferably, the cationic compound is an aminated oxyacid obtained by substituting the hydroxyl group of oxo-acid with an amino group; and the matrix resin comprises at least one polymer selected from poly(amic acid), poly(vinyl pyrrolidone), polyacrylamide, polyamideimide and polyamide. The method comprises the steps of dissolving the matrix resin and the cationic compound in a solvent; and removing the solvent from the obtained mixture.

Description

Proton conductive electrolyte for fuel cell, method for manufacturing same and fuel cell employing same {Proton conductive electrolyte for fuel cell, method for preparing the same and electrode using the proton conductive electrolyte}

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows the structure of the unit cell of the fuel cell of embodiment of this invention.

2 is a graph showing the temperature dependence of proton conductivity of the proton conductive electrolyte membrane of Example 1. FIG.

3 is a graph showing a relationship between a closed circuit voltage and a power generation time of a fuel cell including the proton conductive electrolyte membranes of Example 1 and Comparative Example 1. FIG.

<Brief description of the major symbols in the drawings>

1 unit cell (fuel cell)

2 oxygen electrode (electrode)

3 anode (electrode)

4 Electrolyte Membrane (Proton Conductive Electrolyte)

The present invention relates to a proton conductive electrolyte for a fuel cell, a method for manufacturing the same, and a fuel cell employing the same. Particularly, under an operating temperature of 100 to 200 ° C., a good power generation performance can be maintained for a long time even if the humidity is 50% or less. The present invention relates to a polymer electrolyte fuel cell.

Background Art Conventionally, as an aqueous proton conductive electrolyte, water is used as a proton acceptor and a carrier. In addition, as a non-aqueous proton conductive electrolyte, non-volatile molten salts such as molten salt, phosphoric acid, and imidazole are used as proton acceptors or carriers, and these are compounded in matrices such as heat resistant polymers.

For example, Japanese Patent Laid-Open No. 2001-167629 discloses a gel electrolyte using an inorganic acid anion alkali metal salt, an organic acid anion alkali metal salt, a quaternary ammonium salt, and an anionic surfactant as a proton carrier.

Further, Japanese Patent Laid-Open No. 2003-123791 discloses a proton conductor using phosphoric acid, sulfuric acid, sulfonic acid, tris (trifluoromethylmetide) acid, inorganic solid acid, or the like as a proton acceptor. .

The proton acceptor or the proton carrier in Japanese Patent Application Laid-Open Nos. 2001-167629 and 2003-123791 are both relatively low molecular weight compounds and are water-soluble compounds or liquid compounds. For this reason, especially in polymer-based proton conductive electrolytes, these proton acceptors and the like are likely to be released from the polymer matrix of the electrolyte, and these proton acceptors and the like flow out of the electrolyte together with the water generated by the power generation reaction. There was a problem throwing away. As a result, in the proton conductive electrolytes of Japanese Patent Application Laid-Open Nos. 2001-167629 and 2003-123791, the concentration of proton acceptors and the like in the electrolyte decreases as the power generation time elapses, thereby proton conductivity There was a very diminishing problem.

In addition, when such a proton electrolyte is employed as an electrolyte membrane of a fuel cell, there is a problem that the fuel cell cannot be operated stably in the long term.

As described above, in view of the generation efficiency of the fuel cell, the system efficiency, and the long-term durability of the component, the operating temperature is about 100 ° C. to 200 ° C., and under low-humidity operation conditions with no humidification or relative humidity of 50% or less. There is a demand for a fuel cell that exhibits stable power generation performance for a long time. However, in the prior art, the achievement of such a fuel cell is difficult and stable performance cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes a proton conductive electrolyte capable of stably exhibiting good power generation performance for a long time under operating conditions of about 100 ° C to 200 ° C and no humidity or 50% relative humidity. An object thereof is to provide a manufacturing method and a fuel cell.

In order to solve the problems of the prior art, the present inventors have studied closely, adding an amidated oxo acid compound in which a hydroxy group of oxo acid is substituted with an amino group to any specific matrix resin, which is used as an electrolyte membrane for fuel cells. As a result, it was found that the electrolyte does not deteriorate even when the power generation reaction is continued for a long time, and the proton conductivity is not deteriorated, thereby completing the present invention.

That is, the proton conductive electrolyte for a fuel cell of the present invention is characterized in that a zwitterionic compound is contained in a matrix resin having an amide bond structure in a molecule thereof.

Moreover, in this invention, it is preferable that the said zwitterionic compound is an amidated oxo acid compound which substituted the hydroxyl group of oxo acid with an amino group.

Moreover, in this invention, it is preferable that the said zwitterionic compound is a compound of any one or more of amide sulfuric acid, amide phosphoric acid, diamide phosphoric acid, diphosphate tetraamide, thiophosphate triamide, or derivatives thereof.

In the present invention, the matrix resin is preferably composed of at least one polymer selected from polyamic acid, polyvinylpyrrolidone, polyacrylamide, polyamideimide, and polyamide.

In addition, the method for producing a proton conductive electrolyte for a fuel cell of the present invention comprises the steps of dissolving a matrix resin having an amide bond structure and a zwitterionic compound in a solvent to form a mixed solvent, and removing the solvent from the mixed solvent. It is characterized by comprising a step.

The fuel cell of the present invention is composed of a pair of electrodes and an electrolyte membrane disposed between each electrode, and the electrolyte membrane is made of the above-described proton conductive electrolyte.

In the fuel cell of the present invention, it is preferable that the proton conductive electrolyte described above is contained in a part of the electrode.

Best Mode for Carrying Out the Invention

`` Proton conductive electrolyte ''

EMBODIMENT OF THE INVENTION Hereinafter, the proton conductive electrolyte for fuel cells which is embodiment of this invention is demonstrated in detail.

The proton conductive electrolyte for a fuel cell of the present embodiment is roughly constituted by containing a zwitterionic compound in a matrix resin having an amide bond structure in a molecule thereof.

The matrix resin is to be a skeletal component of the proton conductive electrolyte and is a polymer having an amide bond structure in the main chain or in the side chain, and preferably is not thermally decomposed at the operating temperature (for example, 100 ° C to 200 ° C) of the fuel cell. It shows a stable appearance. Specifically, the matrix resin is composed of at least one polymer selected from polyamic acid, polyvinylpyrrolidone, polyacrylamide, polyamideimide, and polyamide.

Examples of the polyamic acid include poly (pyromellitic acid-co-4,4'-oxydianiline) amic acid and poly (3,3'-4,4'-benzophenonetetracarboxylic acid-co-4,4'- Examples of oxydianiline / 1,3-phenylenediamine) amic acid, poly (3,3'-4,4'-biphenyltetracarboxylic acid-co-4,4'-phenylenediamine) amic acid, etc. can do.

Examples of the polyvinylpyrrolidone include polyvinylpyrrolidone, poly (1-vinylpyrrolidone-co-styrene), poly (1-vinylpyrrolidone-co-vinylacetate) and the like.

Examples of the polyacrylamide include polyacrylamide, poly (acrylamide-co-acrylic acid), poly (2-acrylamide-2-methyl-1-propanesulfonic acid), and the like.

Examples of the polyamide-imide include poly (trimellitic acid chloride-co-4,4′-methylenedianiline), poly (trimellitic acid chloride-alt-benzidine), and the like.

Examples of the polyamides include aliphatic polyamides such as nylon 6 and aromatic polyamides such as poly-p-phenylene terephthalamide.

Among the above-mentioned particularly preferable matrix resins, poly (pyromellitic acid-co-4,4'-oxydianiline) amic acid and poly (3,3'-4,4'-biphenyltetracarboxylic acid-co-1 , 4-phenylenediamine) amic acid, polyvinylpyrrolidone, polyacrylamide, poly (trimellitic acid chloride-co-4,4'-methylenedianiline) can be illustrated.

The average molecular weight of the matrix resin is preferably in the range of 10,000 to 500,000 as a value measured by the GPC method. If the average molecular weight is 10,000 or more, the mechanical strength of the proton conductive electrolyte can be sufficiently increased, and if the average molecular weight is 500,000 or less, the solubility in a solvent or the like can be controlled to be moderately high, and the moldability of the proton conductive electrolyte is improved, which is preferable. .

Next, the zwitterionic compound expresses proton conductivity as a dopant for the matrix resin. This zwitterionic compound is an amidated oxo acid compound in which a hydroxy group of oxo acid is substituted with an amino group. Like the matrix resin, the zwitterionic compound is not thermally decomposed at the operating temperature (100 ° C. to 200 ° C.) of the fuel cell. It represents. Here, as oxo acid, phosphoric acid, diphosphoric acid, thiophosphoric acid, a sulfuric acid etc. can be illustrated, for example. In addition, the number of the hydroxyl group substituted by an amino group should just be 1 or more, and any of 2-4 may be sufficient. As such an amidated oxo acid compound (positive compound), specifically, the compound of any one or more of amide sulfuric acid, amide phosphoric acid, diamide phosphoric acid, diphosphoric acid tetraamide, thiophosphate triamide, or derivatives thereof can be illustrated. Among them, amide sulfuric acid or amide phosphoric acid is particularly preferable.

As the amphoteric compound, an organic compound or inorganic compound having excellent heat resistance and oxidation resistance having basic groups such as amino groups and amine groups and acidic groups such as carboxylic acid groups and sulfonic acid groups may be used as the amphoteric compound.

The mixing ratio (matrix resin: zwitterionic compound) of the matrix resin and the zwitterionic compound is a weight ratio, and the ratio of matrix resin: zwitterionic compound = 90:10 to 30:70 is preferable. If the zwitterionic compound is less than 10% by weight, it does not exhibit sufficient proton conductivity, and if it exceeds 70% by weight, the physical strength of the proton conductive electrolyte is not sufficient.

The proton conductive electrolyte of the present embodiment has the above configuration, and together with the water produced by the power generation reaction under the operating conditions of the fuel cell in the relative humidity range of 0 to 50% at an operating temperature of 100 to 200 ° C. The zwitterion compound does not leak to the outside of the electrolyte, and the proton conductivity can be stably maintained for a long time. Such an effect is estimated to be obtained by the following effects.

That is, the matrix resin constituting the proton conductive electrolyte of the present embodiment has an amide bond structure (-NH-CO-) in its main chain or side chain. Since this amide bond structure has an N—H bond and a C═O bond (carbonyl bond), it is said that a relatively weak intermolecular bond such as a hydrogen bond can be formed between other substances.

On the other hand, the zwitterionic compound contained in the matrix resin contains an acidic group and a basic group in its molecular structure, and at least one of these acidic groups or basic groups is considered to have affinity for the amide bond structure.

As described above, since the zwitterionic compound has a relatively high affinity for the matrix resin, it is assumed that the zwitterionic compound and the matrix resin are homogeneously mixed with each other.

Moreover, since a matrix resin and a zwitterion compound are solid each independently in the temperature range of 100 degreeC-200 degreeC, it is estimated that the zwitterion compound contained in matrix resin also becomes a solid form in matrix resin.

From the above, even if water has penetrated into the proton conductive electrolyte of the present embodiment, since the affinity of the zwitterionic compound to the matrix resin is high, it is difficult for the zwitterionic compound to dissolve in water, whereby the zwitterionic compound It does not leak out of the electrolyte with water, and can maintain proton conductivity for a long time.

`` Production method of proton conductive electrolyte ''

Next, the manufacturing method of the proton conductive electrolyte of this embodiment is demonstrated. This manufacturing method is a process which melt | dissolves the matrix resin and zwitterion compound which have an amide bond structure in a molecule | numerator in a solvent, and uses it as a mixed solvent, and the said mixing It comprises the process of removing the said solvent from a solvent.

As the matrix resin and the zwitterionic compound, the above-mentioned ones can be used. Further, as the solvent, those having high solubility with respect to the matrix resin and the zwitterionic compound are preferable, for example, N-methylpyrrolidone and N, N'- Dimethyl acetamide, N, N'-dimethylformamide, dimethyl sulfoxide, etc. can be used.

The mixed solvent is prepared by adding and dissolving the matrix resin and the zwitterionic compound in the solvent. The mixing ratio (matrix resin: zwitterionic compound) of the matrix resin and the zwitterionic compound is a weight ratio, and the ratio of matrix resin: zwitterionic compound = 90:10 to 30:70 is preferable. The concentration of the total amount of the matrix resin and the zwitterion compound in the mixed solvent is preferably about 5 to 25% by weight as the total amount of the matrix resin and the zwitterion compound. Moreover, when preparing a mixed solvent, you may heat as needed.

Next, in order to remove a solvent from the prepared mixed solvent, the mixed solvent is dripped on a glass substrate, and the mixed solvent is spread | diffused uniformly on a glass substrate, and after that, the mixed solvent is heated and dried for every glass substrate. What is necessary is to volatilize the solvent contained in a mixed solvent by doing this. As a result, a film-like proton conductive electrolyte composed of a matrix resin and a zwitterionic compound is obtained on a glass substrate.

In the case where a proton conductive electrolyte having a thick film is desired, the mixed solvent may be dropped again on the formed proton conductive electrolyte, and the drying may be repeated. Further, by increasing the concentration of the total content of the matrix resin and the zwitterion compound in the mixed solvent, a proton conductive electrolyte having a thick film may be formed.

Thus, according to the manufacturing method of the proton conductive electrolyte of this embodiment, by removing a solvent from the mixed solvent in which a matrix resin and a zwitterion compound are melt | dissolved, shaping | molding of an electrolyte and addition of a zwitterion compound can be carried out simultaneously, The number of steps can be reduced compared to the method for preparing an electrolyte.

`` Fuel cell ''

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 proton conductive electrolyte 4 (hereinafter referred to as an electrolyte membrane) sandwiched between an oxygen electrode 2, a fuel electrode 3, and an oxygen electrode 2 and a fuel electrode 3. (4), 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. It consists of a fuel bipolar plate (6) having a working temperature of 100 ℃ to 200 ℃, the humidity is operating under the condition of no humidity or 50% relative humidity.

The fuel electrode 3 and the oxygen electrode 2 are schematically 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 and a conductive material for solidifying the electrode catalyst.

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. By supporting such a metal or alloy on activated carbon, an electrocatalyst can be constituted.

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 polytetrafluoro fluoride, a tetrafluoroethylene- perfluoroalkyl vinyl ether copolymer, a polyvinylidene fluoride, tetrafluoroethylene hexafluoroethylene Resin excellent in hydrophobicity and heat resistance, such as a copolymer and perfluoroethylene, can be used. By adding a hydrophobic binder, it is possible to prevent the catalyst layers 2a and 3a from excessively being wetted by the water generated by the power generation reaction, and the fuel gas and oxygen in the fuel electrode 3 and the oxygen electrode 2 can be prevented. Diffusion inhibition can be prevented.

Moreover, as an electrically conductive material, what kind of thing may be sufficient as it is an electrically conductive substance, and various metals, a carbon material, 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 a proton conductive electrolyte according to the present invention instead of the hydrophobic binder or together with the hydrophobic binder. By adding the proton conductive electrolyte according to the present invention, the proton conductivity at 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 each is bonded to the oxygen electrode 2 and the fuel electrode 3 to function as a current collector, and to serve as a current collector. 2) and the fuel electrode 3 are supplied with oxygen and fuel gas. That is, the fuel gas mainly containing hydrogen is supplied to the fuel electrode 3 via the fuel flow path 6a of the fuel bipolar plate 6, and the oxidant of the oxidant bipolar plate 5 is supplied to the oxygen electrode 2. Oxygen as an oxidant is supplied through the flow path 5a. In addition, hydrogen supplied as a fuel may be supplied with hydrogen generated by reforming of a hydrocarbon or alcohol, and oxygen supplied as an oxidant may be supplied in a state contained in air.

In the unit cell 1, hydrogen is oxidized at the fuel electrode 3 side to produce protons. The protons conduct the electrolyte membrane 4 to reach the oxygen electrode 2, so that the oxygen electrode 2 Protons and oxygen react electrochemically to produce water along with electrical energy.

Here, the generated water is generated in a state close to water vapor (gas) since the operating temperature of the fuel cell is 100 ° C to 200 ° C. This water vapor is generated in the oxygen electrode 2, and a part of the water vapor may sometimes enter the electrolyte membrane 4 adjacent to the oxygen electrode 2. In the present embodiment, even when water vapor invades the electrolyte membrane 4, for example, there is little fear that the zwitterionic compound contained in the electrolyte membrane 4 will leak out with the water vapor. This is because the affinity of the zwitterionic compound to the matrix resin is high, and since the zwitterionic compound is present in a solid state rather than in a liquid state, it is difficult for the zwitterionic compound to physically flow out of the matrix resin.

As a result, the composition of the electrolyte membrane 4 does not change, and high proton conductivity can be maintained for a long time.

According to the above configuration, a fuel cell exhibiting stable power generation performance over a long period of time even at an operating temperature of 100 to 200 ° C. without humidification or a relative humidity of 50% or less can be obtained, and is very suitable for automobile, home power generation, or portable equipment. Can be used.

Example

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

Example 1

(Production of Proton Conductive Electrolyte Membrane)

First, a 20% solution of poly (3,3'-4,4'-biphenyltetracarboxylic acid-co-1,4-phenylenediamine) amic acid as matrix resin (hereinafter referred to as "matrix resin solution") (Made by Aldrich Co.)) 5 g and 0.5 g of amide sulfuric acid (Kishida Chemical) were prepared as a zwitterionic compound. In addition, 1 g of poly (3,3'-4,4'-biphenyltetracarboxylic acid-co-1,4-phenylenediamine) amic acid is contained in the matrix resin solution.

Next, the matrix resin solution and the amide sulfuric acid are dissolved in 5 g of N-methylpyrrolidone (NMP) to prepare a mixed solvent. Next, the mixed solvent is applied onto a glass plate and dried at 50 ° C. for 6 hours to volatilize NMP. I was. Thus, the proton conductive electrolyte membrane of Example 1 which has a film thickness of 30 micrometers was manufactured. In Table 1, the kind of matrix resin of a proton conductive electrolyte, the kind of zwitterionic compound (dopant), and doping rate (weight%) are shown.

(Proton Conductivity of Proton Conductive Electrolyte Membrane)

Next, the proton conductive electrolyte membrane of Example 1 was inserted into a disk-shaped platinum electrode having a diameter of 13 mm, and the proton conductivity was measured by complex impedance measurement. The temperature dependence of proton conductivity is shown in FIG. Table 1 also shows the proton conductivity at 150 ° C. As shown in Table 1, the proton conductivity at 150 ° C. was 1.1 × 10 ⁻³ Scm ⁻¹ .

(Fuel cell)

Next, the proton conductive electrolyte membrane of Example 1 was dissolved in N, N'-dimethylacetamide solution, and carbon powder supported by 50% by weight of platinum was added, and these were sufficiently stirred to obtain a suspension. At this time, the weight ratio of the platinum-carrying carbon powder and the proton conductive electrolyte in the weight ratio of the solid content was adjusted so that the platinum-carrying carbon powder: proton conductive electrolyte was 2: 1. This suspension was applied onto a carbon porous body (porosity 75%), and dried to obtain a porous electrode for a fuel cell.

The proton conductive electrolyte membrane of Example 1 was sandwiched between a pair of the porous electrodes to form a unit cell (fuel cell).

The power generation test was conducted at 150 ° C. by supplying hydrogen to the fuel and air to the oxidant. The power generation test was conducted under conditions under which a constant current corresponding to a current density of 100 mA / cm 2 was obtained, and the battery was operated for a long time. The change over time of the relative value of the closed-circuit voltage when the voltage of 100% was measured was shown in FIG. 2. In addition, Table 1 shows the open-circuit voltage before the start of power generation of the fuel cell, and shows the voltage reduction rate of the closed-circuit voltage after 200 hours with respect to the closed-circuit voltage immediately after the start of power generation.

As shown in Table 1, the open circuit voltage before the start of power generation of the fuel cell was 0.901V. On the other hand, the closed-circuit voltage immediately after power generation started became 0.584V. In addition, as shown in Table 1 and FIG. 3, the fuel cell including the proton conductive electrolyte of Example 1 exhibited stable battery characteristics.

Example 2

A proton conductive electrolyte membrane of Example 2 was prepared in the same manner as in Example 1 except that amide phosphoric acid was used as the zwitterion compound.

Example 3

A proton conductive electrolyte membrane of Example 3 was prepared in the same manner as in Example 1 except that poly (pyromellitic acid-co-4,4′-oxydianiline) amic acid was used as the matrix resin.

Example 4

The proton conductivity of Example 4 was the same as in Example 1 except that poly (pyromellitic acid-co-4,4'-oxydianiline) amic acid was used as the matrix resin, and amide phosphoric acid was used as the zwitterionic compound. An electrolyte membrane was prepared.

Example 5

A proton conductive electrolyte membrane of Example 5 was prepared in the same manner as in Example 1 except that polyvinylpyrrolidone was used as the matrix resin.

Example 6

A proton conductive electrolyte membrane of Example 6 was prepared in the same manner as in Example 1 except that polyvinylpyrrolidone was used as the matrix resin, and amide phosphoric acid was used as the zwitterion compound.

Example 7

A proton conductive electrolyte membrane of Example 7 was prepared in the same manner as in Example 1 except that polyacrylamide was used as the matrix resin.

Example 8

A proton conductive electrolyte membrane of Example 8 was prepared in the same manner as in Example 1 except that polyacrylamide was used as the matrix resin and amide phosphoric acid was used as the zwitterion compound.

Example 9

A proton conductive electrolyte membrane of Example 9 was prepared in the same manner as in Example 1 except that poly (trimelitic acid chloride-co-4,4'-methylenedianiline) was used as the matrix resin.

Example 10

The proton conductive electrolyte of Example 10 was used in the same manner as in Example 1, except that poly (trimelitic acid chloride-co-4,4'-methylenedianiline) was used as the matrix resin, and amide phosphoric acid was used as the zwitterionic compound. The membrane was prepared.

Comparative Example 1

Polybenzimidazole was dissolved in NMP to prepare a solution, followed by swelling by coating film, predrying, main drying, and immersion in water in order to obtain a polybenzimidazole film having a film thickness of 30 µm. The polybenzimidazole membrane was then directly immersed in 85% phosphoric acid at room temperature, and after 10 minutes, the polybenzimidazole membrane was pulled up to wipe off the surface of the membrane with a wiping cross. Thus, the proton conductive electrolyte membrane of Comparative Example 1 was prepared. .

Evaluation of Examples 2-10 and Comparative Example 1

As in Example 1, the proton conductivity of the proton conductive electrolyte membranes of Examples 2 to 10 and Comparative Example 1 was determined by complex impedance measurement. Table 1 shows the proton conductivity at 150 ° C.

In addition, as in Example 1, a power generation test was carried out by embedding a proton conductive electrolyte membrane in a fuel cell, and the voltage reduction rate of the closed circuit voltage after 200 hours with respect to the open circuit voltage before the start of power generation and the closed circuit voltage immediately after the start of power generation was measured. . The results are shown in Table 1, respectively.

Table 1 also shows the type of matrix resin of the proton conductive electrolyte, the type of zwitterionic compound (dopant), and the doping rate (% by weight).

As shown in Table 1 below, it can be seen that the proton conductivity of the proton conductive electrolyte membranes of Examples 2 to 10 is much higher than in the case of Comparative Example 1. In addition, the voltage reduction rate after 200 hours is only about 4.9 to 5.8% in the proton conductive electrolyte membranes of Examples 2 to 10, whereas in Comparative Example 1, the proton conductivity is low, and thus power generation itself is impossible.

TABLE 1

As shown in Table 1, although the dopants (cationic compounds, phosphoric acid) have almost the same doping rate, the proton conductive electrolyte membranes of Examples 2 to 10 have very excellent performances compared to the proton conductive electrolyte of Comparative Example 1 You can see that you have.

For reference, when the doping rate of the proton conductive electrolyte of Comparative Example 1 is increased from 163% to 400%, the voltage reduction rate after 200 hours at that time is about 14.2%. As described above, in Comparative Example 1, even if the doping amount is greatly increased, the voltage reduction rate is not significantly improved and the results are not comparable to Examples 1 to 10.

As described above, the proton conductive electrolytes of Examples 2 to 10 and Example 1 can generate power with a lower doping amount, compared with the conventional proton conductive electrolyte composed of polybenzimidazole and phosphoric acid. It turns out that it is superior also about a fall rate.

Since the matrix resin and the zwitterionic compound constituting the proton conductive electrolyte for the fuel cell of the present invention are all solid in the temperature range of 100 to 200 ° C, the relative humidity is in the range of 0 to 50% at the operating temperature of 100 to 200 ° C. There is no risk of changing to liquid phase even under the operating conditions of the fuel cell. Accordingly, a solid polymer fuel cell which operates stably for a long time without being exposed to the outside of the electrolyte together with the water generated by the power generation reaction. You can get it.

Further, according to the method for producing a proton conductive electrolyte for a fuel cell of the present invention, the zwitterion compound can be contained in the matrix resin by removing the solvent from the mixed solvent in which the matrix resin and the zwitterion compound are dissolved, thereby forming the electrolyte. The addition of the zwitterionic compound and the zwitterion compound can be carried out simultaneously, and the number of steps can be reduced as compared with the conventional method for producing electrolyte.

Claims (10)

A proton conductive electrolyte for a fuel cell, wherein a zwitterionic compound is contained in a matrix resin having an amide bond structure in a molecule thereof. The proton conductive electrolyte for a fuel cell according to claim 1, wherein the zwitterionic compound is an amidated oxyacid in which a hydroxy group of oxo acid is substituted with an amino group. The proton conductive electrolyte for a fuel cell according to claim 2, wherein the zwitterionic compound is at least one compound of amide sulfuric acid, amide phosphoric acid, diamide phosphoric acid, tetraphosphoric diphosphate, thiophosphate triamide or derivatives thereof. The proton conductive electrolyte for fuel cell according to claim 1, wherein the matrix resin is composed of at least one polymer selected from polyamic acid, polyvinylpyrrolidone, polyacrylamide, polyamideimide, and polyamide. Dissolving a matrix resin having a amide bond structure and a zwitterionic compound in a solvent to form a mixed solvent in a molecule; And Method of producing a proton conductive electrolyte for a fuel cell comprising the step of removing the solvent from the mixed solvent. A fuel cell comprising a pair of electrodes and an electrolyte membrane disposed between each electrode, wherein the electrolyte membrane is a proton conductive electrolyte according to any one of claims 1 to 4. The method of claim 6, And a proton conductive electrolyte comprising a zwitterionic compound in a matrix resin having an amide bond structure in a molecule of a part of the electrode. The fuel cell according to claim 7, wherein the zwitterionic compound is an amidated oxy acid in which a hydroxy group of oxo acid is substituted with an amino group. The fuel cell according to claim 7, wherein the zwitterionic compound is at least one compound of amide sulfuric acid, amide phosphoric acid, diamide phosphoric acid, tetraphosphate diphosphate, thiophosphate triamide or derivatives thereof. 8. The fuel cell according to claim 7, wherein the matrix resin is composed of at least one polymer selected from polyamic acid, polyvinylpyrrolidone, poly acrylamide, polyamideimide, and polyamide.

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