JP4324518B2 - Solid polymer electrolyte for fuel cell and membrane / electrode assembly for fuel cell using the same - Google Patents

Description

The present invention is excellent in a suitable oxidation resistance and the like to the electrolyte membrane or the like used in the fuel cells, fuel cell membrane / electrode using the solid polymer electrolyte and it for a new fuel cell has a low-cost high durability It relates to a joined body.

  A solid polymer electrolyte is a solid polymer material having an electrolyte group such as a sulfonic acid group in the polymer chain, and has a property of binding firmly to a specific ion or selectively transmitting a cation or an anion. Therefore, it is formed into particles, fibers, or membranes, and is used for various applications such as electrodialysis, diffusion dialysis, and battery diaphragm.

  A reformed gas fuel cell is provided with a pair of electrodes on both sides of a proton-conducting solid polymer electrolyte membrane, and hydrogen gas obtained by reforming low-molecular hydrocarbons such as methane and methanol is used as a fuel gas. It supplies to an electrode (fuel electrode), supplies oxygen gas or air to the other electrode (air electrode) as an oxidizing agent, and obtains an electromotive force. In water electrolysis, hydrogen and oxygen are produced by electrolyzing water using a solid polymer electrolyte membrane.

  As solid polymer electrolyte membranes for fuel cells and water electrolysis, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Kogyo Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) A fluorine-based electrolyte membrane represented by a known perfluorosulfonic acid membrane having high proton conductivity is used because of its excellent chemical stability.

  Moreover, salt electrolysis produces sodium hydroxide, chlorine, and hydrogen by electrolyzing a sodium chloride aqueous solution using a solid polymer electrolyte membrane. In this case, since the solid polymer electrolyte membrane is exposed to chlorine, high temperature, and high concentration sodium hydroxide aqueous solution, it is not possible to use a hydrocarbon electrolyte membrane having poor resistance to these. For this reason, solid polymer electrolyte membranes for salt electrolysis are generally resistant to chlorine and high-temperature, high-concentration sodium hydroxide aqueous solution, and in addition, partly on the surface to prevent back diffusion of generated ions. A perfluorosulfonic acid film into which a carboxylic acid group is introduced is used.

  By the way, a fluorine-based electrolyte typified by a perfluorosulfonic acid membrane has a very large chemical stability because it has a C—F bond, and is used for the fuel cell, water electrolysis, or salt electrolysis described above. In addition to these solid polymer electrolyte membranes, they are also used as solid polymer electrolyte membranes for hydrohalic acid electrolysis, and further widely applied to humidity sensors, gas sensors, oxygen concentrators, etc. using proton conductivity. ing.

JP-A-6-93114 Japanese Patent Laid-Open No. 9-245818 Japanese Patent Laid-Open No. 11-116679 Japanese National Patent Publication No. 10-503788 Japanese National Patent Publication No. 11-510198 Japanese National Patent Publication No. 11-515040 JP 2000-106203 A JP-A-9-102322 U.S. Pat.No. 4,012,303 U.S. Pat.No. 4,605,685 Japanese Patent Publication No. 1-52866 JP-A-9-102322

  However, the fluorine-based electrolyte has a drawback that it is difficult to manufacture and is very expensive. For this reason, fluorine-based electrolyte membranes are used for special applications such as solid polymer fuel cells for space or military use, and consumer applications such as solid polymer fuel cells as low-pollution power sources for automobiles. It was difficult.

  Therefore, as an inexpensive solid polymer electrolyte membrane, Patent Document 1 discloses sulfonated polyether ether ketone, Patent Document 2 and Patent Document 3 include sulfonated polyethersulfone, and Patent Document 4 includes sulfonated acrylonitrile / butadiene / styrene polymer. Patent Document 5 proposed an aromatic hydrocarbon electrolyte membrane such as sulfonated polysulfide and Patent Document 6 such as sulfonated polyphenylene. Aromatic hydrocarbon electrolyte membranes obtained by sulfonating these engineered plastics are advantageous in that they are easy to manufacture and low in cost as compared with fluorine electrolyte membranes represented by Nafion. On the other hand, however, the problem remains that the aromatic hydrocarbon electrolyte membrane tends to deteriorate. According to Patent Document 7, since the hydrogen peroxide generated in the catalyst layer formed at the interface between the solid polymer electrolyte membrane and the air electrode (oxidant electrode) degrades the aromatic hydrocarbon skeleton by oxidation, the aromatic hydrocarbon skeleton The electrolyte membrane having

  Therefore, various attempts have been made in the past to obtain a solid polymer electrolyte membrane that has an oxidation deterioration resistance equal to or better than that of a fluorine-based electrolyte membrane and can be manufactured at low cost. For example, Patent Document 8 discloses a sulfonic acid-type polystyrene comprising a main chain formed by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer, and a hydrocarbon side chain having a sulfonic acid group. Graft-ethylenetetrafluoroethylene copolymer (ETFE) membranes have been proposed.

  The sulfonic acid type polystyrene-graft-ETFE membrane disclosed in Patent Document 8 is inexpensive, has sufficient strength as a solid polymer electrolyte membrane for fuel cells, and increases the amount of sulfonic acid groups introduced. It is possible to improve electrical conductivity. However, the sulfonic acid-type polystyrene-graft-ETFE membrane has high oxidation resistance degradation characteristics of the main chain portion made by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer, but the side chain into which a sulfonic acid group is introduced. The portion is an aromatic hydrocarbon polymer that is susceptible to oxidative degradation. Therefore, when this is used for a fuel cell, there is a problem that the oxidation resistance deterioration characteristic of the entire membrane is insufficient and the durability is poor.

  In Patent Document 9 and Patent Document 10, α, β, β-trifluorostyrene is graft-polymerized on a film formed by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer, and sulfonic acid is added thereto. A sulfonic acid type poly (trifluorostyrene) -graft-ETFE membrane, in which a group is introduced to form a solid polymer electrolyte membrane, has been proposed. This is based on the recognition that the chemical stability of the polystyrene side chain moiety into which the sulfonic acid group is introduced is not sufficient, instead of styrene, partially fluorinated α, β, β-trifluoro. Styrene is used. However, since α, β, β-trifluorostyrene, which is a raw material for the side chain portion, is difficult to synthesize, when considering application as a solid polymer electrolyte membrane for a fuel cell, the aforementioned Nafion As with, there is a cost problem. Further, α, β, β-trifluorostyrene has a low polymerization reactivity, so that there is a small amount that can be introduced as a graft side chain, and there is a problem that the conductivity of the resulting film is low.

An object of the present invention, fluorine-based electrolyte least equivalent or practically sufficient have deterioration resistance characteristics, yet solid polymer fuel cell having an easily manufactured highly durable electrolyte Shitsu及 patron Re fuel cell using It is to provide a membrane / electrode assembly for use .

  In order to solve the above-mentioned problems, the degradation mechanism of the electrolyte membrane was examined. The degradation of the aromatic hydrocarbon electrolyte membrane is due to the strong acid, high temperature because the sulfonic acid group is bonded directly to the aromatic ring rather than the oxidation degradation. It was found that the sulfonic acid group was eliminated from the aromatic ring underneath, and the ionic conductivity was lowered due to this phenomenon.

Fuel cell for a solid polymer electrolyte having a high durability according to the present invention, aromatic described below was introduced in place of the sulfonic acid groups of sulfo alkyl group represented by (Formula 1) in the side chain bonded to the aromatic ring It is a non-crosslinked polymer composed of a hydrocarbon polymer compound, and has a durability equivalent to or higher than that of a fluorine-based electrolyte, or practically sufficient, and is an economical, highly durable solid polymer. it is possible to obtain an electrolyte. Moreover, if the ion exchange group equivalent weight is the same, the ionic conductivity of the electrolyte into which the sulfoalkyl group is introduced is more advantageous than the ionic conductivity of the electrolyte into which the sulfonic acid group is introduced. This seems to be related to the fact that the sulfoalkyl group is easier to move than the sulfonic acid group. The highly durable solid polymer electrolyte membrane is preferably formed by any one of a solution casting method, a melt press method, and a melt extrusion method.

The aromatic hydrocarbon polymer compound is a polyethersulfone polymer compound, a polyetheretherketone polymer compound, a polyphenylene sulfide polymer compound, a polyphenylene ether polymer compound, or a polysulfone polymer compound. And a non-crosslinked polymer made of any of polyetherketone polymer compounds.

Further, as the electrode catalyst coating solution for binding a conductive material having a carbon material carrying fine particles of a catalytic metal to the surface of the polymer electrolyte membrane with a binder, a solution containing the polymer electrolyte described above in the binder is preferable. .

The membrane / electrode assembly of the present invention comprises a polymer electrolyte membrane comprising the above-mentioned solid polymer electrolyte, and a gas diffusion electrode comprising a cathode electrode and an anode electrode disposed on both sides via the polymer electrolyte membrane. A membrane / electrode assembly for a polymer electrolyte fuel cell, and the gas diffusion electrode is formed by bonding a conductive material made of a carbon material carrying fine particles of a catalytic metal to the surface of the polymer electrolyte membrane with a binder. It is preferable that the binder comprises the aforementioned polymer electrolyte.

In the present invention, a polymer electrolyte membrane, a gas diffusion electrode composed of a cathode electrode and an anode electrode disposed on both sides of the polymer electrolyte membrane, and a gas installed so as to sandwich the gas diffusion electrode A solid polymer type fuel cell having a pair of impermeable separators and a pair of current collectors disposed between the solid polymer electrolyte membrane and the separator, comprising the above-mentioned solid polymer electrolyte membrane , it is also preferable if the above-described gas diffusion electrodes Ranaru.

  The sulfoalkylated aromatic hydrocarbon electrolyte of the present invention is not particularly limited as long as it is a hydrocarbon electrolyte having an aromatic ring in the main chain having a sulfoalkyl group introduced in the side chain. Specific examples include polyetheretherketone (PEEK) having a structural unit represented by (Chemical Formula 2) developed by ICI in 1977 and semicrystalline polyaryletherketone developed by BASF Germany (PAEK), polyether ketone (PEK) having a structural unit represented by (Chemical Formula 3) sold by Sumitomo Chemical Industries, etc., polyketone (PK) sold by Teijin Amoco Engineering Plastics, Sumitomo Chemical , Polyethersulfone (PES) having a structural unit represented by Teijin Amoco Engineering Plastics and Mitsui Chemicals (Chemical Formula 4), represented by Teijin Amoco Engineering Plastics (Chemical Formula 5) Polysulfone (PSU), Toray, Dainippon Chemical Industry, Toprene, Idemitsu Petrochemical and Kureha Chemical Sold in linear or cross-linked polyphenylene sulfide (PPS) having structural units represented by (Chemical Formula 6), Asahi Kasei, Nippon GE Plastics, Mitsubishi Engineering Plastics and Sumitomo Chemical An aromatic hydrocarbon in which a sulfoalkyl group represented by (Chemical Formula 1) is introduced into a side chain of an engineering plastic such as modified polyphenylene ether (PPE) having a structural unit represented by Chemical Formula 7 or a polymer alloy thereof. Based polymer compound. Of these, sulfoalkylated PEEK, PEAK, PEK, PK, PPS, and PES are preferred from the viewpoint of oxidation resistance deterioration characteristics of the main chain.

There is no particular limitation on the sulfoalkylation method used when introducing the sulfoalkyl group represented by (Chemical Formula 1) into the aromatic hydrocarbon polymer or polymer alloy thereof into the side chain, but as a specific method, for example, J. Amer. Chem. Soc., 76 , 5357-5360 (1954), there is a method for introducing a sulfoalkyl group into an aromatic ring using a sultone represented by (Chemical Formula 8).

  Alternatively, the aromatic ring hydrogen is replaced with lithium, and then a halogenoalkyl group is substituted with a dihalogenoalkane and converted to a sulfoalkyl group, or a halogenobutyl group is introduced using a tetramethylenehalogenium ion, and the halogen is converted to a sulfone. There is a method of converting to an acid group. See (Chemical 9).

  The sulfoalkylation method used for sulfoalkylating an aromatic hydrocarbon polymer compound is not particularly limited, but the method represented by the above (Chemical Formula 8) is preferable from the viewpoint of cost.

  The polyelectrolyte used in the present invention is a sulfoalkylated polymer having an ion exchange group equivalent weight of 250 to 2500 g / mol. Preferably, the ion exchange group equivalent weight is 300 to 1500 g / mol, more preferably 350 to 1000 g / mol. When the ion exchange group equivalent weight exceeds 2500 g / mol, the output performance may decrease, and when it is lower than 250 g / mol, the water resistance of the polymer decreases, which is not preferable.

In the present invention, the ion exchange group equivalent weight represents the molecular weight of the sulfoalkylated polymer per mole of the introduced sulfoalkyl group, and the smaller the value, the higher the sulfoalkylation degree. The ion-exchange group equivalent weight can be measured by ¹ H-NMR spectroscopy, elemental analysis, acid-base titration described in Patent Document 11, non-hydroxybase titration (normal solution is potassium methoxide in benzene / methanol), etc. It is.

  As a method for controlling the ion exchange group equivalent weight of the sulfoalkylated polyelectrolyte to 250 to 2500 g / mol, the mixing ratio of the aromatic hydrocarbon polymer and the sulfoalkylating agent, the reaction temperature, the reaction time, By changing the chemical structure or the like of the aromatic hydrocarbon polymer, a sulfoalkylated polymer having a target ion exchange group equivalent weight can be obtained.

  When the polymer electrolyte used in the present invention is used for a fuel cell, it is usually used in a membrane state. The method for converting the sulfoalkylated polymer into a membrane is not particularly limited, but a method of forming a film from a solution state (solution casting method) or a method of forming a film from a molten state (melt press method or melt extrusion method) is possible. is there. Specifically, the former is formed by, for example, casting a polymer solution on a glass plate and removing the solvent.

  The solvent used for film formation is not particularly limited as long as it dissolves the polymer and can be removed thereafter. N, N′-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone , Aprotic polar solvents such as dimethyl sulfoxide, or alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, halogen solvents such as dichloromethane and trichloroethane, Alcohols such as i-propyl alcohol and t-butyl alcohol are preferably used.

  The thickness of the polymer electrolyte membrane is not particularly limited but is preferably 10 to 200 μm. 30 to 100 μm is particularly preferable. A thickness of more than 10 μm is preferable to obtain a membrane strength that can withstand practical use, and a thickness of less than 200 μm is preferable to reduce membrane resistance, that is, to improve power generation performance. In the case of the solution casting method, the film thickness can be controlled by the solution concentration or the coating thickness on the substrate. When the film is formed from a molten state, the film thickness can be controlled by stretching a film having a predetermined thickness obtained by a melt press method or a melt extrusion method at a predetermined magnification.

  Moreover, when manufacturing the electrolyte of this invention, additives, such as a plasticizer, a stabilizer, a mold release agent, etc. which are used for a normal polymer can be used in the range which is not contrary to the objective of this invention.

A gas diffusion electrode used for a membrane / electrode assembly when used as a fuel cell is composed of a conductive material carrying fine particles of a catalytic metal, and a water repellent or a binder is provided as necessary. It may be included. Moreover, you may form the layer which consists of the electrically conductive material which does not carry | support a catalyst, and the water repellent and binder contained as needed on the outer side of a catalyst layer. The catalyst metal used for the gas diffusion electrode may be any metal that promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen, such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium. , Iron, cobalt, nickel, chromium, tungsten, manganese, vanadium, or alloys thereof. Of these catalysts, platinum is often used. The particle size of the metal used as the catalyst is usually 10 to 300 angstroms. When these catalysts are attached to a carrier such as carbon, the amount of the catalyst used is small and advantageous in terms of cost. The amount of the catalyst supported is preferably 0.01 to 10 mg / cm ² with the electrode formed.

  As the conductive material, any material can be used as long as it is an electron conductive material, and examples thereof include various metals and carbon materials. Examples of the carbon material include carbon black such as furnace black, channel black, and acetylene black, activated carbon, graphite, and the like, and these are used alone or in combination. As the water repellent, for example, fluorinated carbon is used. As the binder, the electrode catalyst coating solution of the present invention is preferably used as it is from the viewpoint of adhesiveness, but other various resins may be used. In that case, a fluorine-containing resin having water repellency is preferable, and those having excellent heat resistance and oxidation resistance are particularly preferable. For example, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylene -A hexafluoropropylene copolymer is mentioned.

  There are no particular restrictions on the electrolyte membrane and the electrode joining method when used as a fuel cell, and known methods can be applied. As a method for producing a membrane / electrode assembly, for example, Pt catalyst powder supported on carbon is mixed with a polytetrafluoroethylene suspension, applied to carbon paper, and heat-treated to form a catalyst layer. Next, there is a method in which the same electrolyte solution as the electrolyte membrane is applied to the catalyst layer and integrated with the electrolyte membrane by hot pressing. In addition, a method of coating the same electrolyte solution as the electrolyte membrane on the Pt catalyst powder in advance, a method of applying a catalyst paste to the electrolyte membrane, a method of electrolessly plating an electrode on the electrolyte membrane, a platinum group metal on the electrolyte membrane There is a method of reducing complex ions after adsorbing them.

  The polymer electrolyte fuel cell is a fuel distribution plate as a grooved current collector that forms a fuel flow path and an oxidant flow path outside the joined body of the electrolyte membrane and gas diffusion electrode formed as described above. And an oxidizer flow plate are provided as a single cell, and a plurality of such single cells are stacked through a cooling plate or the like. It is desirable to operate the fuel cell at a high temperature because the catalytic activity of the electrode is increased and the electrode overvoltage is reduced. However, since the electrolyte membrane does not function without moisture, it must be operated at a temperature at which moisture management is possible. . The preferred range of operating temperature of the fuel cell is from room temperature to 100 ° C.

According to the present invention, a solid polymer electrolyte for a fuel cell having a deterioration resistance characteristic equivalent to or higher than that of a fluorine-based electrolyte, practically sufficient, and easy to manufacture, and for a fuel cell using the same A membrane / electrode assembly can be provided.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, the measurement conditions of each physical property are as follows.

(1) Equivalent weight of ion exchange group The sulfoalkylated polymer to be measured was precisely weighed (a (gram)) in a glass container capable of being sealed, and an excess amount of calcium chloride aqueous solution was added thereto and stirred overnight. Hydrogen chloride generated in the system was titrated (b (ml)) with 0.1N sodium hydroxide standard aqueous solution (titer f) using phenolphthalein as an indicator. The ion exchange group equivalent weight (g / mol) was determined from the following formula.
Ion exchange group equivalent weight = (1000 × a) / (0.1 × b × f)
(2) Fuel cell single cell output performance evaluation An electrolyte with electrodes joined was incorporated into the evaluation cell, and the fuel cell output performance was evaluated. Hydrogen / oxygen was used as the reaction gas, and both were humidified through a water bubbler at 23 ° C. at a pressure of 1 atm, and then supplied to the evaluation cell. The gas flow rate was 60 ml / min for hydrogen, 40 ml / min for oxygen, and the cell temperature was 70 ° C. The battery output performance was evaluated with an H201B charge / discharge device (Hokuto Denko).

(Example 1)
(1) Synthesis of sulfopropylated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 21.6 g of polyether Sulfone (PES), 12.2 g (0.1 mol) of propane sultone and 50 ml of dried nitrobenzene were charged. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the mixture was refluxed for 8 hours. Then, the reaction product was poured into 500 ml of ice water to which 25 ml of concentrated hydrochloric acid was added to stop the reaction. The reaction solution was slowly added dropwise to 1 liter of deionized water to precipitate sulfopropylated polyethersulfone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. The obtained sulfopropylated polyethersulfone had an ion exchange group equivalent weight of 980 g / mol.

  The cost of sulfopropylated polyethersulfone electrolyte can be manufactured in one process using polyethersulfone, which is a commercially available low-priced engineer plastic, so the cost of the perfluorosulfonic acid electrolyte manufactured through five processes is expensive. Compared to 1/50 or less, it is inexpensive.

Polytetrafluoroethylene code put sulfopropyl 20 ml polyether sulfone 1.0g of ion-exchanged water obtained in a SUS closed container proboscis, and held for 2 weeks to 12 0 ° C.. Then, it cooled and the ion exchange group equivalent weight of sulfopropylated polyether sulfone was measured. As a result, the ion exchange group equivalent weight of sulfopropylated polyethersulfone was 980 g / mol, which was the same as that of the expensive perfluorosulfonic acid electrolyte. On the other hand, as shown in Comparative Example 1 (1) described later, the ion exchange group equivalent weight of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3000 g / mol under the same heating hydrolysis condition, and the initial 960 g The value was larger than the value of / mol, and the sulfone group was dissociated. That is, an inexpensive sulfopropylated polyethersulfone electrolyte, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte described in (1) of Comparative Example 1 described later, exhibits stability as with an expensive perfluorosulfonic acid electrolyte. The cost and characteristics are both excellent.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20:80:25) to a concentration of 5% by weight of the product obtained in (1) above. Dissolved. This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane I having a thickness of 42 μm. The obtained electrolyte membrane I had an ionic conductivity of 5 S / cm.

  The obtained electrolyte membrane I and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating, and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in (2) of Comparative Example 1 described later, the relatively inexpensive sulfonated aromatic hydrocarbon-based electrolyte II was broken under the same heating hydrolysis condition and was raged. In other words, the inexpensive sulfopropylated polyethersulfone electrolyte membrane is as stable as the expensive perfluorosulfonic acid membrane, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane described in Comparative Example 1 (2) described later. It is excellent in terms of both cost and characteristics.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The weight ratio of platinum catalyst to polymer electrolyte is 2: 1 with 40% by weight platinum-supported carbon and 5% by weight N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) above. The paste (Electrocatalyst coating solution I) was prepared by uniformly adding and dispersing. The electrode catalyst coating solution I was applied to both sides of the electrolyte membrane I obtained in the above (2) and then dried to prepare a membrane / electrode assembly I having a platinum loading of 0.25 mg / cm ² .

After applying the electrode catalyst coating solution II described in (2) of Comparative Example 1 (described later) to both sides of the electrolyte membrane I obtained in (2) above on 40% by weight of platinum-supporting carbon, drying is performed to obtain platinum. A membrane / electrode assembly I ′ having a loading amount of 0.25 mg / cm ² was produced.

  To 40% by weight of platinum-supported carbon, add a 5% by weight alcohol-water mixed solution of perfluorosulfonic acid electrolyte so that the weight ratio of the platinum catalyst to the polymer electrolyte is 2: 1. A paste (electrocatalyst coating solution) was prepared by dispersing. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane I obtained in the above (2). The electrolyte membrane and the electrode catalyst coating solution were separated and could not be applied uniformly, and a membrane / electrode assembly could not be produced. The electrode catalyst coating solution I is excellent as the electrode catalyst coating solution.

  The obtained membrane / electrode assembly I and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly I was the same as the membrane / electrode assembly produced using the high-cost perfluorosulfonic acid membrane and the perfluorosulfonic acid electrolyte, and the membrane was solid.

  Further, the obtained membrane / electrode assembly I ′ and 20 ml of ion-exchanged water were put into a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, in the membrane / electrode assembly I ′, the electrode was slightly peeled off, but the membrane was firm and had power generation capability.

  On the other hand, as shown in Comparative Example 1 (3) described later, the membrane / electrode assembly II produced using the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane II and the electrode catalyst coating solution II is the same. Under heated hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, an inexpensive sulfopropylpolychlorotrifluoroethylene electrolyte membrane / electrode assembly is expensive, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 1 (3) described later. As with the perfluorosulfonic acid membrane / electrode assembly, it is stable and has excellent cost and characteristics.

(4) Durability test of single fuel cell The membrane / electrode assembly I or I ′ was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. That is, the polymer electrolyte membrane 1, the oxygen electrode 2 and the hydrogen electrode 3 are constituted by the membrane / electrode assembly 4 manufactured in the above (3), and both electrodes are supported by a thin carbon paper packing material and sealed. The solid polymer fuel cell unit shown in FIG. 1 is composed of a conductive separator (bipolar plate) 6 which serves as a gas chamber for separation of the polar chamber and the gas supply passage from both sides. A cell was produced. The oxygen electrode 2 serves as a cathode electrode and the hydrogen electrode 3 serves as an anode electrode.

The polymer electrolyte fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. 2 in FIG. 2 is a durability test result of a single fuel cell using the electrolyte membrane / electrode assembly I of the present invention. Reference numeral 13 in FIG. 2 represents a durability test result of a single fuel cell using the electrolyte membrane / electrode assembly I ′. 2 in FIG. 2 is the result of a durability test of a single fuel cell using a perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 12 in FIG. 2, the output voltage was 0.8V in the initial stage, and it was the same as the result using the perfluorosulfonic acid membrane of FIG.

On the other hand, the output voltage of 15 in FIG. 2 (a fuel cell single cell using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 1 described later) was 0.73 V in the initial stage, and the output disappeared after 600 hours of operation time. . Therefore, a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is an aromatic hydrocarbon electrolyte directly bonded to a sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, although the platinum loading of the membrane / electrode assembly of Example 1 and Comparative Example 1 is the same as 0.25 mg / cm ² , the output voltage of the single fuel cell of Example 1 is that of Comparative Example 1. The reason why the output voltage of the fuel cell unit cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of the membrane / electrode assembly of Example 1 is the electrolyte membrane and electrode catalyst coating of the membrane / electrode assembly of Comparative Example 1 This is because the membrane / electrode assembly of Example 1 is superior to the membrane / electrode assembly of Comparative Example 1 because it is larger than the ionic conductivity of the working solution.

(5) Fabrication of fuel cell A polymer electrolyte fuel cell in which 36 single-cell cells fabricated in (4) were stacked was fabricated and showed an output of 3 kW.

(Comparative Example 1)
(1) Synthesis of sulfonated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 25 g of polyethersulfone ( PES) and 125 ml of concentrated sulfuric acid were added. The mixture was stirred overnight at room temperature under a nitrogen stream to obtain a uniform solution. To this solution, 48 ml of chlorosulfuric acid was added dropwise from a dropping funnel while stirring under a nitrogen stream. Since the chlorosulfuric acid reacted vigorously with the water in the concentrated sulfuric acid and foamed for a while after the start of the dripping, it was slowly dripped, and after the foaming became mild, the dripping was completed within 5 minutes. The reaction solution after completion of the dropwise addition was sulfonated by stirring at 25 ° C. for 3.5 hours. The reaction solution was then slowly added dropwise to 15 liters of deionized water to precipitate sulfonated polyethersulfone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water by a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The obtained sulfonated polyethersulfone electrolyte had an ion exchange group equivalent weight of 960 g / mol.

  1.0 g of the sulfonated polyethersulfone electrolyte obtained and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of sulfonated polyether sulfone electrolysis. As a result, the ion exchange group equivalent weight of the sulfonated polyethersulfone electrolyte was 3000 g / mol, which was larger than the initial value of 960 g / mol, and the sulfone group was dissociated.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20:80) so that the sulfonated polyethersulfone electrolyte obtained in (1) has a concentration of 5% by weight. : 25). This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane II having a film thickness of 45 μm. The ionic conductivity of the obtained electrolyte membrane II was 0.02 S / cm.

  The obtained electrolyte membrane II and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating, and kept at 120 ° C. for 2 weeks. As a result, the electrolyte membrane II was broken and raged.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The weight ratio of platinum catalyst to polymer electrolyte is 2: 1 with 40% by weight platinum-supported carbon and 5% by weight N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) above. The paste (Electrocatalyst Coating Solution II) was prepared by uniformly adding and dispersing. The electrode catalyst coating solution II was applied to both sides of the electrolyte membrane II obtained in the above (2) and then dried to prepare a membrane / electrode assembly II having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly II and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the membrane of the membrane / electrode assembly II was broken and raged, and the electrode was peeled off.

(4) Durability test of a single fuel cell cell A thin carbon paper packing material (supporting current collector) is adhered to both sides of the membrane / electrode assembly II in Comparative Example 1, and the electrode chamber is separated from both sides to the electrode. A polymer electrolyte fuel cell single cell consisting of a conductive separator (bipolar plate) that also functions as a gas supply passage was fabricated and subjected to a long-term operation test under a current density of 300 mA / cm ² . As a result, as shown by 15 in FIG. 2, the output voltage was 0.73 V in the initial stage, and the output voltage disappeared after 600 hours of operation.

  The cost of sulfopropylated polyethersulfone electrolyte can be manufactured in one process using polyethersulfone, which is a commercially available low-priced engineer plastic, so the cost of the perfluorosulfonic acid electrolyte manufactured through five processes is expensive. Compared to 1/50 or less, it is inexpensive.

  As can be seen from Example 1 and Comparative Example 1 (1), the inexpensive sulfopropylated polyethersulfone electrolyte is different from the sulfonated aromatic hydrocarbon electrolyte, and shows stability as with the expensive perfluorosulfonic acid electrolyte. And excellent properties.

  As can be seen from (1) and (2) of Example 1 and Comparative Example 1, the ion-exchange group equivalent weight of the aromatic hydrocarbon electrolyte in which the sulfonic acid group is bonded via the alkyl group of Example 1 is 980 g / mol. The ion-exchange group equivalent weight of the aromatic hydrocarbon electrolyte directly bonded to the sulfonic acid group of Comparative Example 1 is 960 g / mol, and the ion-exchange group equivalent weight of Example 1 is larger than that of Comparative Example 1. Nevertheless, the ionic conductivity of the electrolyte membrane of Example 1 is larger than the ionic conductivity of the electrolyte membrane of Comparative Example 1 (usually, the smaller the ion exchange group equivalent weight, the higher the ionic conductivity). This electrolyte membrane is superior to the electrolyte membrane of Comparative Example 1. Further, as can be seen from Example 1 and Comparative Example 1 (2), the inexpensive sulfopropylated polyethersulfone electrolyte membrane is different from the sulfonated aromatic hydrocarbon electrolyte membrane and is the same as the expensive perfluorosulfonic acid electrolyte membrane. It has excellent stability in terms of cost and characteristics.

  As can be seen from Example 1 and Comparative Example 1 (3), the inexpensive sulfopropylated polyethersulfone electrolyte membrane / electrode assembly is different from the sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly and is expensive perfluoro. Similar to the sulfonic acid electrolyte membrane / electrode assembly, it exhibits stability and is excellent in both cost and characteristics.

  Further, as can be seen from Example 1 and Comparative Example 1 (4), the output voltage of the fuel cell single cell using the electrode catalyst coating solution of Example 1 is a fuel using the electrode catalyst coating solution of Comparative Example 1. The electrode catalyst coating solution of Example 1 is superior to the electrode catalyst coating solution of Comparative Example 1 above the output voltage of the single battery cell. The fuel cell unit cell of the present invention is low in cost and has durability equivalent to that of a perfluorosulfonic acid fuel cell unit cell. Unlike the sulfonated aromatic hydrocarbon fuel cell unit cell, the unit cell has sufficient practical durability. is doing.

As can be seen from FIG. 2, the output voltage of 12 (the fuel cell single cell of Example 1) is 0.8V at the initial stage, and it remains unchanged from the initial state even after 5000 hours of operation time, and 14 perfluorosulfonic acid membranes in FIG. It was equivalent to the result. On the other hand, the output voltage of 15 (the fuel cell single cell of Comparative Example 1) was 0.73 V in the initial stage, and the output disappeared after 600 hours of operation. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, although the platinum loading of the membrane / electrode assembly of Example 1 and Comparative Example 1 is the same as 0.25 mg / cm ² , the output voltage of the single fuel cell of Example 1 is that of Comparative Example 1. The reason why the output voltage of the fuel cell unit cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of the membrane / electrode assembly of Example 1 is the electrolyte membrane and electrode catalyst coating of the membrane / electrode assembly of Comparative Example 1 This is because the membrane / electrode assembly of Example 1 is superior to the membrane / electrode assembly of Comparative Example 1 because it is larger than the ionic conductivity of the working solution.

(Example 2)
(1) Synthesis of sulfopropylated polyetheretherketone After purging the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube with nitrogen, Ether ether ketone, 12.2 g (0.1 mol) of propane sultone, 50 ml of dried nitrobenzene were charged. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the mixture was refluxed for 30 hours. Next, the reaction solution was slowly dropped into 0.5 liter of deionized water to precipitate sulfopropylated polyetheretherketone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. The obtained sulfopropylated polyetheretherketone electrolyte had an ion exchange group equivalent weight of 800 g / mol.

  The cost of sulfopropylated polyetheretherketone electrolyte can be manufactured in one step using polyetheretherketone, which is a commercially available low-priced engineer plastic, so the raw material is expensive and the perfluorosulfonic acid electrolyte manufactured through five steps It is less than 1/40 of the cost.

  1.0 g of the obtained sulfopropylated polyetheretherketone electrolyte and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of sulfopropylated polyetheretherketone electrolyte. As a result, the ion exchange group equivalent weight of the sulfopropylated polyetheretherketone electrolyte was as stable as that of the expensive perfluorosulfonic acid electrolyte, which was 800 g / mol. On the other hand, as shown in (1) of Comparative Example 2 described later, the ion-exchange group equivalent weight of an inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 2500 g / mol under the same heating hydrolysis condition, and the initial 600 g The value was larger than the value of / mol, and the sulfone group was dissociated. That is, an inexpensive sulfopropylated polyetheretherketone electrolyte, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte described in Comparative Example 2 (1) described later, is stable as an expensive perfluorosulfonic acid electrolyte. It is excellent in both cost and characteristics.

(2) Production of electrolyte membrane The product obtained in (1) was dissolved in N-methylpyrrolidone solvent so as to have a concentration of 5% by weight. This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane III having a thickness of 42 μm.

  The obtained electrolyte membrane III and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in (2) of Comparative Example 2 described later, the relatively inexpensive sulfonated aromatic hydrocarbon-based electrolyte IV was broken under the same heating hydrolysis conditions and was raged. That is, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane described in Comparative Example 2 (2) described later, the inexpensive sulfopropylated polyethersulfone exhibits stability similar to the expensive perfluorosulfonic acid membrane. The cost and characteristics are both excellent.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The N-methylpyrrolidone solution described in (2) above is added to 40% by weight of platinum-supporting carbon so that the weight ratio of the platinum catalyst to the polymer electrolyte is 2: 1 and dispersed uniformly to obtain a paste (electrode) Catalyst coating solution III) was prepared. This electrode catalyst coating solution III was applied to both sides of the electrolyte membrane III obtained in the above (2) and then dried to prepare a membrane / electrode assembly III having a platinum loading of 0.25 mg / cm ² .

After applying the electrode catalyst coating solution IV of Comparative Example 2 (3) described later to 40% by weight of platinum-supporting carbon on both sides of the electrolyte membrane III obtained in the above (2), the coating was dried and the amount of platinum supported A membrane / electrode assembly III ′ of 0.25 mg / cm ² was produced.

  To 40% by weight of platinum-supported carbon, add a 5% by weight alcohol-water mixed solution of perfluorosulfonic acid electrolyte so that the weight ratio of the platinum catalyst to the polymer electrolyte is 2: 1. A paste (electrocatalyst coating solution) was prepared by dispersing. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane III obtained in the above (2). The electrolyte membrane and the electrode catalyst coating were separated and could not be applied uniformly, and a membrane / electrode assembly could not be produced.

  The obtained membrane / electrode assembly III and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly III was the same as the initial membrane as well as the membrane / electrode assembly produced using a high-cost perfluorosulfonic acid membrane and a perfluorosulfonic acid electrolyte, and the membrane was solid.

  Further, the obtained membrane / electrode assembly III ′ and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, in the membrane / electrode assembly III ′, the electrode was slightly peeled off, but the membrane was firm and had power generation capability.

  On the other hand, as shown in Comparative Example 2 (3) described later, the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane IV and the membrane / electrode assembly IV prepared using the electrode catalyst coating solution IV are the same. Under heated hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, an inexpensive sulfopropylpolychlorotrifluoroethylene electrolyte membrane / electrode assembly is expensive, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 2 (3) described later. As with the perfluorosulfonic acid membrane / electrode assembly, it is stable and has excellent cost and characteristics.

(4) Fuel cell single cell output performance evaluation The membrane / electrode assemblies III and III ′ were absorbed by immersing them in boiling deionized water for 2 hours. These membrane / electrode assemblies were incorporated into an evaluation cell, and the fuel cell output performance was evaluated. FIG. 3 shows a current density-voltage plot of a fuel cell single cell incorporating the membrane / electrode assembly III. When the current density is 1 (A / cm ² ), the output voltage is 0.6 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.76 (V). It was possible.

A thin carbon paper packing material (supporting current collector) is adhered to both sides of the membrane / electrode assembly III and III ′ of Example 2 to serve as a chamber separation and a gas supply passage to the electrode from both sides. A single polymer electrolyte fuel cell unit cell made of a conductive separator (bipolar plate) was fabricated and subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. 4 in FIG. 4 is the result of a durability test of a single fuel cell using the electrolyte membrane / electrode assembly III of the present invention. 4 in FIG. 4 is the result of the durability test of the single fuel cell using the electrolyte membrane / electrode assembly III ′. 4 in FIG. 4 is the result of a durability test of a single fuel cell using a perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 16 in FIG. 4, the output voltage was 0.76 V in the initial stage, which was the same as the initial value even after 5000 hours of operation, and was the same as the result of using the 18 perfluorosulfonic acid membrane in FIG. 4. On the other hand, the output voltage of 19 in FIG. 4 (single cell using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 2 described later) was 0.73 V in the initial stage, and the output disappeared after 5000 hours of operation time. .

Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. The amount of supported platinum of the membrane / electrode assembly Example 2 and Comparative Example 2 even though the same as 0.25 mg / cm ^2, the output voltage of the fuel cell unit of Example 2 of Comparative Example 2 The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 2 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 2. This is because the membrane / electrode assembly of Example 2 is superior to the membrane / electrode assembly of Comparative Example 2 because it is larger than the ionic conductivity of the working solution.

(5) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of the unit cells fabricated in (4), and showed an output of 3 kW.

(Comparative Example 2)
(1) Synthesis of sulfonated polyetheretherketone After purging the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube with nitrogen, 6.7 g of polyether Etherketone (PEEK) and 100 ml of 96% concentrated sulfuric acid were added. The mixture was dissolved by stirring at 60 ° C. for 60 minutes under a nitrogen stream. To this solution, oleum (containing 20 wt% SO ₃ ) was added with stirring under a nitrogen stream to adjust the concentrated sulfuric acid concentration to 98.5 wt%. Subsequently, it heated at 80 degreeC for 30 minutes. The reaction solution was slowly dropped into 15 liters of deionized water to precipitate sulfonated polyetheretherketone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water by a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The sulfonated polyether ether ketone electrolyte obtained had an ion exchange group equivalent weight of 600 g / mol.

  A SUS sealed container of polytetrafluoroethylene coating was charged with 1.0 g of the sulfonated polyetheretherketone electrolyte obtained and 20 ml of ion-exchanged water, and kept at 120 ° C. for 2 weeks. Then, it cooled and the ion exchange group equivalent weight of the sulfonated polyether ether ketone electrolyte was measured. As a result, the ion exchange group equivalent weight of the sulfonated polyetheretherketone electrolyte was 2500 g / mol, which was larger than the initial value, and the sulfone group was dissociated.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20: 20%) so that the sulfonated polyetheretherketone electrolyte obtained in the above (1) has a concentration of 5% by weight. 80:25). This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane IV having a film thickness of 45 μm. The sulfonated polyether ether ketone electrolyte membrane IV obtained had an ionic conductivity of 0.02 S / cm.

  The obtained sulfonated polyetheretherketone electrolyte membrane IV and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating, and kept at 120 ° C. for 2 weeks. As a result, the sulfonated polyetheretherketone electrolyte membrane was broken and raged.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The weight ratio of platinum catalyst to polymer electrolyte is 2: 1 with 40% by weight platinum-supported carbon and 5% by weight N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) above. The paste (Electrocatalyst coating solution IV) was prepared by uniformly adding and dispersing. This electrode catalyst coating solution IV was applied to both sides of the electrolyte membrane IV obtained in the above (2) and then dried to prepare a membrane / electrode assembly IV having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly IV and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the membrane of the membrane / electrode assembly IV was broken and raged, and the electrode was peeled off.

(4) Durability test of a single fuel cell cell A thin carbon paper packing material (supporting current collector) is adhered to both sides of the membrane / electrode assembly IV of Comparative Example 2 to separate the electrode chamber and electrodes from both sides. A polymer electrolyte fuel cell single cell consisting of a conductive separator (bipolar plate) that also functions as a gas supply passage was fabricated and subjected to a long-term operation test under a current density of 300 mA / cm ² . As a result, as indicated by 19 in FIG. 4, the output voltage was 0.73 V in the initial stage, and the output was lost after 5000 hours of operation.

The cost of sulfopropylated polyetheretherketone electrolyte can be manufactured in one step using polyetheretherketone, which is a commercially available low-priced engineer plastic, so the raw material is expensive and the perfluorosulfonic acid electrolyte manufactured through five steps It is less than 1/40 of the cost.

  As can be seen from (2) of Example 2 and Comparative Example 2, the aromatic hydrocarbon electrolyte having a sulfonic acid group bonded thereto via the alkyl group of Example 2 is an aromatic directly bonded to the sulfonic acid group of Comparative Example 2. More stable to 120 ° C ion-exchanged water than hydrocarbon electrolytes.

  As can be seen from Example 2 and Comparative Example 2 (3), the electrode catalyst coating solution of Example 2 is superior to the perfluorosulfonic acid electrode catalyst coating solution over the aromatic hydrocarbon membrane. Further, as can be seen from Example 2 and Comparative Example 2 (4), the output voltage of the fuel cell single cell using the electrode catalyst coating solution of Example 2 is a fuel using the electrode catalyst coating solution of Comparative Example 2. The electrode catalyst coating solution of Example 2 is superior to the electrode catalyst coating solution of Comparative Example 2 above the output voltage of the single battery cell.

As can be seen from FIG. 4, the output voltage of 16 (single fuel cell single cell of Example 2) is 0.8V at the initial stage, and it does not change from the initial state even after 5000 hours of operation, and 18 perfluorosulfonic acid membranes in FIG. It was equivalent to the result. On the other hand, the output voltage of 19 (the fuel cell single cell of Comparative Example 2) was 0.73 V in the initial stage, and the output disappeared after 5000 hours of operation. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. The amount of supported platinum of the membrane / electrode assembly Example 2 and Comparative Example 2 even though the same as 0.25 mg / cm ^2, the output voltage of the fuel cell unit of Example 2 of Comparative Example 2 The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 2 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 2. This is because the membrane / electrode assembly of Example 2 is superior to the membrane / electrode assembly of Comparative Example 2 because it is larger than the ionic conductivity of the working solution.

(Example 3)
(1) Synthesis of sulfopropylated polyphenylene sulfide After replacing the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, and reflux condenser connected with a calcium chloride tube with nitrogen, 10.8 g of polyphenylene Sulfide (PPS), 12.2 g (0.1 mol) of propane sultone, and 50 ml of dry acetophenone were added. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the mixture was refluxed for 10 hours. Subsequently, the reaction solution was slowly dropped into 0.5 liter of deionized water to precipitate sulfopropylated polyphenylene sulfide, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. The obtained sulfopropylated polyphenylene sulfide electrolyte had an ion exchange group equivalent weight of 520 g / mol.

  The cost of sulfopropylated polyphenylene sulfide electrolyte can be manufactured in one process using polyphenylene sulfide, which is a commercially available low-priced engineer plastic, so the raw material is expensive and the perfluorosulfonic acid electrolyte manufactured through 5 processes It is less expensive than 1/50 compared to the cost.

  1.0 g of the obtained sulfopropylated polyphenylene sulfide and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of the sulfopropylated polyphenylene sulfide electrolyte. As a result, the ion exchange group equivalent weight of the sulfopropylated polyphenylene sulfide electrolyte was as stable as that of the expensive perfluorosulfonic acid electrolyte at 520 g / mol, unchanged from the initial value. On the other hand, as shown in Comparative Example 3 (1) described later, the ion exchange group equivalent weight of an inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3500 g / mol under the same heating hydrolysis condition, and the initial 500 g The value was larger than the value of / mol, and the sulfone group was dissociated. That is, an inexpensive sulfopropylated polyphenylene sulfide electrolyte differs from the inexpensive sulfonated aromatic hydrocarbon-based electrolyte described in Comparative Example 3 (1) described later, and is as stable as an expensive perfluorosulfonic acid electrolyte. It is excellent in both cost and characteristics.

(2) Production of electrolyte membrane The sulfopropylated polyphenylene sulfide electrolyte obtained in (1) above was dissolved in N-methylpyrrolidone solvent so as to have a concentration of 5% by weight. This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane V having a film thickness of 46 μm.

  The obtained electrolyte membrane V and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in (2) of Comparative Example 3 described later, the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte VI was broken under the same heating hydrolysis condition and was raged. That is, an inexpensive sulfopropylated polyphenylene sulfide electrolyte membrane is different from an inexpensive sulfonated aromatic hydrocarbon-based electrolyte membrane described in Comparative Example 3 (2) described later, and is similar to an expensive perfluorosulfonic acid membrane. It is stable and has excellent cost and characteristics.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
Paste by adding the N-methylpyrrolidone solution of (2) Electrolyte V to 40% by weight of platinum-supported carbon so that the weight ratio of platinum catalyst to polymer electrolyte is 2: 1 and uniformly dispersed. (Electrocatalyst coating solution V) was prepared. This electrode catalyst coating solution was applied to one side of the electrolyte membrane V obtained in the above (2) and then dried. In addition, the N-methylpyrrolidone solution of (2) electrolyte V is added to 40% by weight of platinum-ruthenium alloy-supported carbon so that the weight ratio of the platinum-ruthenium alloy catalyst to the polymer electrolyte is 2: 1. The paste (electrode catalyst coating solution V ′) was prepared by uniformly dispersing the paste. This electrode catalyst coating solution V ′ was applied to the remaining side of the electrolyte membrane V obtained in the above (2) and then dried. A membrane / electrode assembly V having a platinum loading of 0.25 mg / cm ² (oxygen electrode) and a platinum-ruthenium alloy loading of 0.3 mg / cm ² (hydrogen electrode) was prepared.

Except for using the electrode catalyst coating solution VI of Comparative Example 3 which will be described later, the platinum loading 0.25 mg / cm ² (oxygen electrode) and the platinum-ruthenium alloy loading 0.3 mg / cm ² (hydrogen electrode) were made exactly the same. A membrane / electrode assembly V ′ was produced.

  To 40% by weight of platinum-supported carbon, add a 5% by weight alcohol-water mixed solution of perfluorosulfonic acid electrolyte so that the weight ratio of the platinum catalyst to the polymer electrolyte is 2: 1. A paste (electrocatalyst coating solution) was prepared by dispersing. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane V obtained in the above (2). The electrolyte membrane and the electrode catalyst coating were separated and could not be applied uniformly, and a membrane / electrode assembly could not be produced.

  The obtained membrane / electrode assembly V and 20 ml of ion-exchanged water were put into a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly V was the same as the initial membrane and the membrane was solid, as was the case with the membrane / electrode assembly produced using a high-cost perfluorosulfonic acid membrane and perfluorosulfonic acid electrolyte.

  Further, the obtained membrane / electrode assembly V ′ and 20 ml of ion-exchanged water were put into a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, in the membrane / electrode assembly V ′, the electrode was slightly peeled off, but the membrane was firm and had power generation capability.

  On the other hand, as shown in Comparative Example 1 (3) described later, the membrane / electrode assembly VI prepared using the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane VI and the electrode catalyst coating solution VI is the same. Under heated hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, the inexpensive sulfopropylated polyphenylene sulfide electrolyte membrane / electrode assembly is expensive, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 3 (3) below. As with the perfluorosulfonic acid membrane / electrode assembly, it is stable and has excellent cost and characteristics.

(4) Evaluation of fuel cell single cell output performance The membrane / electrode assembly was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. FIG. 5 shows a current density-output voltage plot of a single battery cell using the membrane / electrode assembly V. When the current density is 1 (A / cm ² ), the output voltage is 0.63 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.78 (V). It was possible.

The solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. 6 in FIG. 6 is a durability test result of a single fuel cell using the electrolyte membrane / electrode assembly V of the present invention. Reference numeral 21 in FIG. 6 represents a durability test result of the single fuel cell using the electrolyte membrane / electrode assembly V ′. 6 in FIG. 6 is the result of a durability test of a single fuel cell using a perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 20 in FIG. 6, the output voltage of the fuel cell single cell using the electrolyte membrane / electrode assembly V is 0.78 V in the initial stage, and is unchanged from the initial state even after 5000 hours of operation. It was equivalent to the result using an acid film. On the other hand, the output voltage of 23 in FIG. 6 (a fuel cell single cell using a sulfonated aromatic hydrocarbon electrolyte of Comparative Example 3 described later) was 0.63 V in the initial stage, and the output disappeared after 600 hours of operation time. . Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using.

In addition, the output voltage of the single fuel cell of Example 3 was the same as that of Comparative Example 3 even though the amount of platinum supported in the membrane / electrode assembly of Example 3 and Comparative Example 3 was the same as 0.25 mg / cm ² . The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 3 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 3. This is because the membrane / electrode assembly of Example 3 is superior to the membrane / electrode assembly of Comparative Example 3, which is larger than the ionic conductivity of the solution for use.

(5) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of the unit cells fabricated in (4), and showed an output of 3 kW.

(Comparative Example 3)
(1) Synthesis of sulfonated polyphenylene sulfide After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 12 g at 5 ° C Of polyphenylene sulfide (PPS) and 220 ml of chlorosulfuric acid were added. PPS was dissolved by stirring at 5 ° C. for 30 minutes under a nitrogen stream. Subsequently, it hold | maintained at 20 degreeC for 150 minutes and 50 degreeC for 60 minutes. The reaction solution was slowly dropped into 15 liters of deionized water to precipitate sulfonated polyphenylene sulfide, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water by a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The sulfonated polyphenylene sulfide obtained had an ion exchange group equivalent weight of 500 g / mol.

  A SUS airtight container of polytetrafluoroethylene coating was charged with 1.0 g of the sulfonated polyethersulfone and 20 ml of ion-exchanged water, and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of sulfonated polyphenylene sulfide. As a result, the ion exchange group equivalent weight of the sulfonated polyphenylene sulfide was 3500 g / mol, which was larger than the initial value, and the sulfone group was dissociated.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20:80:25) to a concentration of 5% by weight of the product obtained in (1) above. Dissolved. This solution was spread on glass by spin coating, air dried, and then vacuum dried at 80 ° C. to prepare a sulfonated polyphenylene sulfide electrolyte membrane VI having a film thickness of 45 μm. The ionic conductivity of the obtained film VI was 0.02 S / cm.

  The sulfonated polyphenylene sulfide electrolyte membrane VI and 20 ml of ion-exchanged water obtained in a SUS sealed container of polytetrafluoroethylene coating were placed and maintained at 120 ° C. for 2 weeks. As a result, the sulfonated polyphenylene sulfide electrolyte membrane VI was broken and raged.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The weight ratio of platinum catalyst to polymer electrolyte is 2: 1 with 40% by weight platinum-supported carbon and 5% by weight N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) above. The paste (Electrocatalyst coating solution VI) was prepared by uniformly adding and dispersing. This electrode catalyst coating solution VI was applied to both sides of the electrolyte membrane VI obtained in the above (2) and then dried to produce a membrane / electrode assembly VI having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly VI and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating, and kept at 120 ° C. for 2 weeks. As a result, the membrane of the membrane / electrode assembly VI was torn and shabby, and the electrode was peeled off.

(4) Durability test of a single fuel cell cell A thin carbon paper packing material (supporting current collector) is adhered to both sides of the membrane / electrode assembly VI of Comparative Example 3 to separate the electrode chamber and electrodes from both sides. A polymer electrolyte fuel cell single cell consisting of a conductive separator (bipolar plate) that also functions as a gas supply passage was fabricated and subjected to a long-term operation test under a current density of 300 mA / cm ² . As a result, as indicated by 23 in FIG. 6, the output voltage was initially 0.63 V, and the output ceased after 600 hours of operation time.

  The cost of sulfopropylated polyphenylene sulfide electrolyte can be manufactured in one process using polyphenylene sulfide, which is a commercially available low-priced engineer plastic, so the raw material is expensive and the perfluorosulfonic acid electrolyte manufactured through 5 processes It is less expensive than 1/50 compared to the cost.

  As can be seen from (1) of Example 3 and Comparative Example 3, the aromatic hydrocarbon electrolyte in which the sulfonic acid group is bonded via the alkyl group of Example 3 is the aromatic directly bonded to the sulfonic acid group of Comparative Example 3. It is more stable to ion exchange water at 120 ° C than hydrocarbon electrolytes.

  As can be seen from (1) and (2) of Example 3 and Comparative Example 3, the ion-exchange group equivalent weight of the aromatic hydrocarbon electrolyte in which the sulfonic acid group is bonded via the alkyl group of Example 3 is 520 g / mol. The ion-exchange group equivalent weight of the aromatic hydrocarbon electrolyte directly bonded to the sulfonic acid group of Comparative Example 3 is 500 g / mol, and the ion-exchange group equivalent weight of Example 3 is larger than that of Comparative Example 3. Nevertheless, since the ionic conductivity of the electrolyte membrane of Example 3 is larger than the ionic conductivity of the electrolyte membrane of Comparative Example 2 (usually, the smaller the ion exchange group equivalent weight, the higher the ionic conductivity). The electrolyte membrane of 3 is superior to the electrolyte membrane of Comparative Example 3.

  As can be seen from Example 3 and Comparative Example 3 (3), the electrocatalyst coating solution of Example 3 is superior to the perfluorosulfonic acid electrocatalyst coating solution over the aromatic hydrocarbon membrane. Further, as can be seen from Example 3 and Comparative Example 3 (4), the output voltage of the fuel cell single cell using the electrode catalyst coating solution of Example 3 is a fuel using the electrode catalyst coating solution of Comparative Example 3. The electrode catalyst coating solution of Example 3 is superior to the electrode catalyst coating solution of Comparative Example 3 above the output voltage of the single battery cell.

As can be seen from FIG. 6, the output voltage of 20 (single fuel cell single cell of Example 3) is 0.78V in the initial stage, and it does not change from the initial state even after 5000 hours of operation time. It was equivalent to the result. On the other hand, the output voltage of 23 (a fuel cell single cell using an aromatic hydrocarbon-based electrolyte directly bonded to the sulfone group of Comparative Example 3) was 0.63 V in the initial stage, and the output disappeared after 600 hours of operation. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, the output voltage of the single fuel cell of Example 3 is the same as that of Comparative Example 3 even though the amount of platinum supported in the membrane / electrode assembly of Example 3 and Comparative Example 3 is the same as 0.25 mg / cm ² . The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 3 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 3. This is because the membrane / electrode assembly of Example 3 is superior to the membrane / electrode assembly of Comparative Example 3, which is larger than the ionic conductivity of the solution for use.

(Example 4)
(1) Synthesis of sulfopropylated modified polyphenylene oxide After replacing the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with calcium chloride tube with nitrogen, 12.0 g of modified polyphenylene Oxide (m-PPE), 12.2 g (0.1 mol) of propane sultone, and 50 ml of dried dimethyl sulfoxide were added. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the temperature was maintained at 150 ° C. for 8 hours. Then, the reaction product was poured into 500 ml of ice water to which 25 ml of concentrated hydrochloric acid was added to stop the reaction. The organic layer was separated, washed with water, and neutralized with an aqueous sodium carbonate solution to which a few drops of octyl alcohol was added. The aluminum hydroxide was filtered off, the filtrate was decolorized with activated carbon, and then the solvent was stripped. The obtained sulfopropylated modified polyphenylene oxide electrolyte had an ion exchange group equivalent weight of 370 g / mol.

  The cost of sulfopropylated polyphenylene oxide electrolyte can be manufactured in one process using polyphenylene oxide, which is a commercially available low-priced engineer plastic, so the cost is 1 compared to the cost of perfluorosulfonic acid electrolyte that is expensive and manufactured through 5 processes. / 50 or less and inexpensive.

  1.0 g of the obtained sulfopropylated modified polyphenylene oxide electrolyte and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of the sulfopropylation modification polyphenylene oxide electrolyte. As a result, the ion exchange group equivalent weight of the sulfopropylated modified polyphenylene oxide electrolyte was 520 g / mol, which was as stable as the expensive perfluorosulfonic acid electrolyte. On the other hand, as shown in Comparative Example 4 (1) described later, the ion exchange group equivalent weight of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3500 g / mol under the same heating hydrolysis condition, and the initial 490 g The value was larger than the value of / mol, and the sulfone group was dissociated. That is, an inexpensive sulfopropylated modified polyphenylene oxide electrolyte shows stability as an expensive perfluorosulfonic acid electrolyte, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte described in Comparative Example 4 (1) described later. The cost and characteristics are both excellent.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20: 20%) so that the sulfopropylated modified polyphenylene oxide electrolyte obtained in the above (1) has a concentration of 5% by weight. 80:25). This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare a sulfopropylated modified polyphenylene oxide electrolyte membrane VII having a thickness of 42 μm. The obtained membrane VII had an ionic conductivity of 0.01 S / cm.

  The obtained electrolyte membrane VII and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in Comparative Example 4 (2) described later, the relatively inexpensive sulfonated aromatic hydrocarbon-based electrolyte VIII was broken under the same heating hydrolysis conditions and was raged. That is, an inexpensive sulfopropylated modified polyphenylene oxide electrolyte membrane is as stable as an expensive perfluorosulfonic acid membrane, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane described in Comparative Example 4 (2) below. It is excellent in terms of both cost and characteristics.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The weight ratio of platinum catalyst to polymer electrolyte is 2: 1 with 40% by weight platinum-supported carbon and 5% by weight N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) above. The paste (Electrocatalyst coating solution VII) was prepared by uniformly adding and dispersing. This electrode catalyst coating solution VII was applied to both sides of the sulfopropylated modified polyphenylene oxide electrolyte membrane VII obtained in the above (2) and then dried to form a membrane / electrode assembly VII having a platinum loading of 0.25 mg / cm ^2. Was made.

  The obtained membrane / electrode assembly VII and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly VII was the same as the membrane / electrode assembly produced using the high-cost perfluorosulfonic acid membrane and the perfluorosulfonic acid electrolyte, and the membrane was firm.

  On the other hand, as shown in Comparative Example 4 (3) described later, the membrane / electrode assembly VIII produced using the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane VIII and the electrode catalyst coating solution VIII is the same. Under heated hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, an inexpensive sulfopropylated modified polyphenylene oxide electrolyte membrane / electrode assembly differs from an inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 4 (3) below. Similar to the fluorosulfonic acid membrane / electrode assembly, it exhibits stability and is excellent in both cost and characteristics.

(4) Fuel cell single cell output performance evaluation The membrane / electrode assembly VII was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly VII was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. The resulting current density-voltage plot is shown in FIG. When the current density is 1 (A / cm ² ), the output voltage is 0.69 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.82 (V). It was possible. The solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. In FIG. 8, 24 is the result of a durability test of a single fuel cell using the electrolyte membrane / electrode assembly VII of the present invention. Reference numeral 25 in FIG. 8 represents a durability test result of the single fuel cell using the perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 24 in FIG. 8, the output voltage was 0.82 V in the initial stage, which was the same as the initial value even after 5000 hours of operation, and was the same as the result of using the 25 perfluorosulfonic acid membrane in FIG. On the other hand, the output voltage of 26 in FIG. 8 (single cell using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 4 described later) was 0.63 V at the initial stage, and the output disappeared after 600 hours of operation time. .

Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, the output voltage of the fuel cell single cell of Example 4 was the same as that of Comparative Example 4 although the platinum loading of the membrane / electrode assembly of Example 4 and Comparative Example 4 was the same as 0.25 mg / cm ² . The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 4 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 4 This is because the membrane / electrode assembly of Example 4 is superior to the membrane / electrode assembly of Comparative Example 4, which is larger than the ionic conductivity of the working solution.

(5) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of the unit cells fabricated in (4), and showed an output of 3 kW.

(Comparative Example 4)
(1) Synthesis of sulfonated modified polyphenylene oxide After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 12 g of 5 g Polyphenylene oxide (m-PPE) and 220 ml of chlorosulfuric acid were added. PPS was dissolved by stirring for 30 minutes at 5 ° C. under a nitrogen stream. Subsequently, it hold | maintained at 20 degreeC for 150 minutes and 5 degreeC0 for 60 minutes. The reaction solution was slowly dropped into 15 liters of deionized water to precipitate sulfonated modified polyphenylene oxide, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water by a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The resulting sulfonated modified polyphenylene oxide electrolyte had an ion exchange group equivalent weight of 490 g / mol.

  A SUS airtight container of polytetrafluoroethylene coating was charged with 1.0 g of the sulfonated modified polyphenylene oxide electrolyte and 20 ml of ion-exchanged water, and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of the sulfonated modified polyphenylene oxide electrolyte. As a result, the ion exchange group equivalent weight of the sulfonated modified polyphenylene oxide electrolyte was 3500 g / mol, which was larger than the initial value, and the sulfone group was dissociated.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20:80:25) to a concentration of 5% by weight of the product obtained in (1) above. Dissolved. This solution was spread on glass by spin coating, air dried, and then vacuum dried at 80 ° C. to prepare a sulfonated modified polyphenylene oxide electrolyte membrane VIII having a film thickness of 45 μm. The sulfonated modified polyphenylene oxide electrolyte membrane VIII had an ionic conductivity of 0.02 S / cm.

  Sulfonation-modified polyphenylene oxide electrolyte membrane VIII and 20 ml of ion-exchanged water were added and kept at 120 ° C. for 2 weeks. As a result, the sulfonated modified polyphenylene oxide electrolyte membrane VIII was broken and raged.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
40% by weight of platinum-supported carbon is mixed with a 5% by weight N, N′-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) sulfonated modified polyphenylene oxide electrolyte in a weight ratio of platinum catalyst to polymer electrolyte. Was added so as to be 2: 1 and dispersed uniformly to prepare a paste (Electrocatalyst Coating Solution VIII). This electrode catalyst coating solution VIII was applied to both sides of the sulfonated modified polyphenylene oxide electrolyte membrane obtained in (2), and then dried to produce a membrane / electrode assembly VIII having a platinum loading of 0.25 mg / cm ^2. did.

  The obtained membrane / electrode assembly VIII and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the membrane of the membrane / electrode assembly VIII was torn and raged, and the electrode was peeled off.

(4) Durability test of a single fuel cell cell A thin carbon paper packing material (supporting current collector) is adhered to both sides of the membrane / electrode assembly VIII of Comparative Example 4, and the chamber separation and electrodes are performed from both sides. A polymer electrolyte fuel cell single cell consisting of a conductive separator (bipolar plate) that also functions as a gas supply passage was fabricated and subjected to a long-term operation test under a current density of 300 mA / cm ² . As a result, as indicated by 26 in FIG. 8, the output voltage was initially 0.63 V, and the output disappeared after 600 hours of operation.

  The cost of sulfopropylated polyphenylene oxide electrolyte can be manufactured in one process using polyphenylene oxide, which is a commercially available low-priced engineer plastic, so the cost is 1 compared to the cost of perfluorosulfonic acid electrolyte that is expensive and manufactured through 5 processes. / 50 or less and inexpensive.

  As can be seen from Example 4 and Comparative Example 4 (1), the aromatic hydrocarbon electrolyte in which the sulfonic acid group is bonded via the alkyl group in Example 4 is the aromatic bonded directly to the sulfonic acid group in Comparative Example 4. It is more stable against ion exchange water at 12 ° C than hydrocarbon electrolytes.

  As can be seen from (1) and (2) of Example 4 and Comparative Example 4, the ion-exchange group equivalent weight of the aromatic hydrocarbon electrolyte in which the sulfonic acid group is bonded via the alkyl group of Example 4 is 520 g / mol. The ion-exchange group equivalent weight of the aromatic hydrocarbon electrolyte directly bonded to the sulfonic acid group of Comparative Example 4 is 490 g / mol, and the ion-exchange group equivalent weight of Example 4 is larger than that of Comparative Example 4. Nevertheless, since the ionic conductivity of the electrolyte membrane of Example 4 is larger than the ionic conductivity of the electrolyte membrane of Comparative Example 4 (usually, the smaller the ion exchange group equivalent weight, the higher the ionic conductivity). The electrolyte membrane of 4 is superior to the electrolyte membrane of Comparative Example 4.

  As can be seen from Example 4 and Comparative Example 4 (3), the electrode catalyst coating solution of Example 4 is superior to the perfluorosulfonic acid electrode catalyst coating solution over the aromatic hydrocarbon membrane.

  In addition, as can be seen from (4) of Example 4 and Comparative Example 4, the output voltage of the fuel cell single cell using the electrode catalyst coating solution of Example 4 is a fuel using the electrode catalyst coating solution of Comparative Example 4. The electrode catalyst coating solution of Example 4 is superior to the electrode catalyst coating solution of Comparative Example 4 above the output voltage of the single battery cell.

As can be seen from FIG. 8, the output voltage of 24 (single fuel cell single cell of Example 4) is 0.82V in the initial stage, and it does not change from the initial state even after 5,000 hours of operation time. It was equivalent to the result. On the other hand, the output voltage of 26 (single fuel cell of Comparative Example 4) was 0.63 V in the initial stage, and the output was lost after 600 hours of operation. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, the output voltage of the fuel cell single cell of Example 4 was the same as that of Comparative Example 4 although the platinum loading of the membrane / electrode assembly of Example 4 and Comparative Example 4 was the same as 0.25 mg / cm ² . The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 4 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 4 This is because the membrane / electrode assembly of Example 4 is superior to the membrane / electrode assembly of Comparative Example 4, which is larger than the ionic conductivity of the working solution.

(Example 5)
(1) Synthesis of sulfopropylated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 11.6 g of polyether Sulfone (PES), 12.2 g (0.1 mol) of propane sultone, 50 ml of dry acetophenone were added. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the mixture was refluxed for 8 hours. Subsequently, the reaction solution was slowly dropped into 0.5 liter of deionized water to precipitate sulfopropylated polyethersulfone, which was recovered by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. The obtained sulfopropylated polyethersulfone had an ion exchange group equivalent weight of 700 g / mol.

  The cost of sulfopropylated polyethersulfone electrolyte can be manufactured in one process using polyethersulfone, which is a commercially available low-priced engineer plastic, so the cost of the perfluorosulfonic acid electrolyte manufactured through five processes is expensive. Compared to 1/50 or less, it is inexpensive.

  In a polytetrafluoroethylene coating SUS sealed container, 1.0 g of the obtained sulfopropylated polyethersulfone and 20 ml of ion-exchanged water were placed, and kept at 12 ° C. for 2 weeks. Then, it cooled and the ion exchange group equivalent weight of sulfopropylated polyether sulfone was measured. As a result, the ion-exchange group equivalent weight of the sulfopropylated polyethersulfone was 700 g / mol, which was the same as that of the expensive perfluorosulfonic acid electrolyte. On the other hand, as shown in Comparative Example 1 (1) described later, the ion exchange group equivalent weight of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3000 g / mol under the same heating hydrolysis condition, and the initial 960 g The value was larger than the value of / mol, and the sulfone group was dissociated. That is, an inexpensive sulfopropylated polyethersulfone electrolyte, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte described in (1) of Comparative Example 1 described later, exhibits stability as with an expensive perfluorosulfonic acid electrolyte. The cost and characteristics are both excellent.

(2) Production of electrolyte membrane The product obtained in (1) above was dissolved in an N, N'-dimethylformamide solution to a concentration of 5% by weight. The solution was applied to glass by spin coating, dried in air, was created electrolyte membrane IX of thickness 40μm was vacuum dried at 8 0 ° C..

  The obtained electrolyte membrane IX and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity of the electrolyte membrane IX was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in (2) of Comparative Example 1 described later, the relatively inexpensive sulfonated aromatic hydrocarbon-based electrolyte membrane II was broken under the same heating hydrolysis conditions and was raged. That is, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane described in Comparative Example 1 (2) described later, the inexpensive sulfopropylated polyethersulfone exhibits stability similar to the expensive perfluorosulfonic acid membrane. The cost and characteristics are both excellent.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The N, N'-dimethylformamide solution of (2) above was added to 40% by weight of platinum-supported carbon so that the weight ratio of platinum catalyst to polymer electrolyte was 2: 1 and dispersed uniformly. A paste (Electrocatalyst coating solution IX) was prepared. This electrode catalyst coating solution IX was applied to one side of the electrolyte membrane IX obtained in the above (2) and then dried. Further, the N, N′-dimethylformamide solution of (2) above is added to 40% by weight of platinum-ruthenium alloy-supported carbon so that the weight ratio of the platinum-ruthenium alloy catalyst to the polymer electrolyte is 2: 1. It was added and dispersed uniformly to prepare a paste (Electrocatalyst coating solution IX ′). This electrode catalyst coating solution IX ′ was applied to the remaining side of the electrolyte membrane IX obtained in the above (2) and then dried. A membrane / electrode assembly IX having a platinum loading of 0.29 mg / cm ² (oxygen electrode) and a platinum-ruthenium alloy loading of 0.32 mg / cm ² (hydrogen electrode) was prepared.
The obtained membrane / electrode assembly IX and 20 ml of ion-exchanged water were put into a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly IX was the same as the membrane / electrode assembly produced by using a high-cost perfluorosulfonic acid membrane and a perfluorosulfonic acid electrolyte, and the membrane was solid.

  On the other hand, as shown in Comparative Example 1 (3) described later, the membrane / electrode assembly II produced using the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane II and the electrode catalyst coating solution II is the same. Under heated hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, an inexpensive sulfopropylated polyethersulfone electrolyte membrane / electrode assembly is different from an inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in (3) of Comparative Example 1 described later. Similar to the fluorosulfonic acid membrane / electrode assembly, it exhibits stability and is excellent in both cost and characteristics.

(4) Fuel cell single cell output performance evaluation The membrane / electrode assembly IX was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly IX was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. The obtained current density-voltage plot is shown in FIG. When the current density is 1 (A / cm ² ), the output voltage is 0.63 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.80 (V). It was possible.

Further, the solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. 27 in FIG. 10 is the result of a durability test of a single fuel cell using the electrolyte membrane / electrode assembly IX of the present invention. 28 in FIG. 10 is a result of the durability test of the single fuel cell using the perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 27 in FIG. 10, the output voltage was 0.80 V at the initial stage, and it was the same as the result using the perfluorosulfonic acid membrane of 28 in FIG. On the other hand, the output voltage of 29 in FIG. 10 (fuel cell single cell using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 1) was 0.63 V in the initial stage, and the output disappeared after 600 hours of operation. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using.

(6) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of unit cells fabricated in (5), and showed an output of 3 kW.

(Example 6)
(1) Synthesis of sulfopropylated polysulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer and reflux condenser connected with a calcium chloride tube was purged with nitrogen, 22.1 g of polysulfone (PSU) 12.2 g (0.1 mol) of propane sultone and 50 ml of a dry mixed solvent of trichloroethane-dichloroethane (1: 1) were added. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the temperature was kept at 100 ° C. for 24 hours. Then, the reaction product was poured into 500 ml of ice water to which 25 ml of concentrated hydrochloric acid was added to stop the reaction. The organic layer was separated, washed with water, and neutralized with an aqueous sodium carbonate solution to which a few drops of octyl alcohol was added. The aluminum hydroxide was filtered off, the filtrate was decolorized with activated carbon, and then the solvent was stripped. The obtained sulfopropylated polysulfone electrolyte had an ion exchange group equivalent weight of 750 g / mol.

  The cost of sulfopropylated sulfone electrolyte is 1/50 compared to the cost of perfluorosulfonic acid electrolyte, which is expensive and can be manufactured in 5 steps because polysulfone, which is a commercially available engineer plastic, can be manufactured in 1 step. It is less expensive.

  1.0 g of sulfopropylated polysulfone electrolyte and 20 ml of ion-exchanged water were added and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of the sulfopropylated polysulfone electrolyte. As a result, the ion-exchange group equivalent weight of the sulfopropylated polysulfone electrolyte was 750 g / mol, which was as stable as the expensive perfluorosulfonic acid electrolyte. On the other hand, as shown in Comparative Example 5 (1) described later, the ion-exchange group equivalent weight of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3000 g / mol under the same heating hydrolysis condition, and the initial 700 g The value was larger than the value of / mol, and the sulfone group was dissociated. That is, an inexpensive sulfopropylated polysulfone electrolyte, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte described in Comparative Example 5 (1) described later, shows stability as an expensive perfluorosulfonic acid electrolyte, and has a low cost. And excellent properties.

(2) Production of electrolyte membrane The sulfopropylated polysulfone electrolyte obtained in (1) was dissolved in a mixed solvent (1: 1) of trichloroethane-dichloroethane so as to have a concentration of 5% by weight. This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare a sulfopropylated polysulfone electrolyte membrane X having a thickness of 42 μm.

  The obtained sulfopropylated polysulfone electrolyte membrane X and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in (2) of Comparative Example 5 described later, the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte XI was broken under the same heating hydrolysis conditions and was raged. That is, an inexpensive sulfopropylated polysulfone electrolyte membrane is stable like an expensive perfluorosulfonic acid membrane, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane described in Comparative Example 5 (2) described later. The cost and characteristics are both excellent.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
To the 40% by weight platinum-supporting carbon, the mixed solution of trichloroethane-dichloroethane of (2) above is added so that the weight ratio of the platinum catalyst to the polymer electrolyte is 2: 1 and dispersed uniformly to obtain a paste ( Electrocatalyst coating solution X) was prepared. This electrode catalyst coating solution X was applied to both sides of the electrolyte membrane obtained in the above (2) and then dried to produce a membrane / electrode assembly X having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly X and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly was the same as the membrane / electrode assembly produced by using a high-cost perfluorosulfonic acid membrane and a perfluorosulfonic acid electrolyte, and the membrane was solid.

  On the other hand, as shown in Comparative Example 5 (3) described later, the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane XI and the membrane / electrode assembly XI prepared using the electrode catalyst coating solution XI are the same. Under heated hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, the inexpensive sulfopropylated sulfone electrolyte membrane / electrode assembly differs from the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 5 (3) described later, and is expensive perfluorosulfone. Similar to the acid film / electrode assembly, it exhibits stability and is excellent in both cost and characteristics.

(4) Fuel cell single cell output performance evaluation The membrane / electrode assembly X was immersed in boiling deionized water for 2 hours to absorb water. The obtained membrane / electrode assembly X was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. The obtained current density-output voltage plot is shown in FIG. When the current density is 1 (A / cm ² ), the output voltage is 0.68 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.81 (V). It was possible.

The solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. Reference numeral 30 in FIG. 12 represents a durability test result of a single fuel cell using the electrolyte membrane / electrode assembly X of the present invention. Reference numeral 31 in FIG. 12 represents a durability test result of a single fuel cell using the perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 30 in FIG. 12, the output voltage was 0.81 V in the initial stage, which was the same as the result of using the perfluorosulfonic acid membrane 31 in FIG.

On the other hand, the output voltage of 32 in FIG. 12 (a fuel cell single cell using the sulfonated aromatic hydrocarbon electrolyte XI of Comparative Example 5) was 0.63 V in the initial stage, and the output disappeared after 600 hours of operation. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, the output voltage of the single fuel cell of Example 6 is the same as that of Comparative Example 5 even though the amount of platinum supported in the membrane / electrode assembly of Example 6 and Comparative Example 5 is the same as 0.25 mg / cm ² . The reason why the output voltage of the single cell of the fuel cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 6 is the membrane / electrode assembly of Example 6 and the electrolyte membrane and electrode catalyst coating of the membrane / electrode assembly of Comparative Example 5 This is because the membrane / electrode assembly of Example 6 is superior to the membrane / electrode assembly of Comparative Example 5 because it is larger than the ionic conductivity of the working solution.

(6) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of unit cells fabricated in (5), and showed an output of 3 kW.

(Comparative Example 5)
(1) Synthesis of sulfonated polysulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, and reflux condenser connected with a calcium chloride tube was purged with nitrogen, 25 g of polysulfone (PSU) and concentrated 125 ml of sulfuric acid was added. The mixture was stirred overnight at room temperature under a nitrogen stream to obtain a uniform solution. To this solution, 48 ml of chlorosulfuric acid was added dropwise from a dropping funnel while stirring under a nitrogen stream. Since the chlorosulfuric acid reacted vigorously with the water in the concentrated sulfuric acid and foamed for a while after the start of the dripping, it was slowly dripped, and after the foaming became mild, the dripping was completed within 5 minutes. The reaction solution after completion of the dropwise addition was sulfonated by stirring at 25 ° C. for 3.5 hours. The reaction solution was then slowly added dropwise to 15 liters of deionized water to precipitate sulfonated polyethersulfone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water by a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The obtained sulfonated polysulfone electrolyte had an ion exchange group equivalent weight of 700 g / mol.

  1.0 g of the sulfonated polysulfone electrolyte obtained above and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating, and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of sulfonated polysulfone electrolysis. As a result, the ion exchange group equivalent weight of the sulfonated polysulfone electrolyte was 3000 g / mol, which was larger than the initial value of 700 g / mol, and the sulfone group was dissociated.

(2) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20:80:25) so that the sulfonated polysulfone electrolyte obtained in (1) has a concentration of 5% by weight. ). This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane XI having a thickness of 45 μm. The obtained electrolyte membrane XI had an ionic conductivity of 0.02 S / cm.

  The obtained electrolyte membrane XI and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the electrolyte membrane XI was broken and raged.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
The weight ratio of platinum catalyst to polymer electrolyte is 2: 1 with 40% by weight platinum-supported carbon and 5% by weight N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solution of (2) above. Thus, the paste (electrode catalyst coating solution XI) was prepared by uniformly dispersing. This electrode catalyst coating solution XI was applied to both sides of the electrolyte membrane obtained in the above (2) and then dried to produce a membrane / electrode assembly XI having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly XI and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating and kept at 12 ° C. for 2 weeks. As a result, the membrane of the membrane / electrode assembly XI was broken and raged, and the electrode was peeled off.

(4) Durability test of a single fuel cell cell A thin carbon paper packing material (supporting current collector) is adhered to both sides of the membrane / electrode assembly XI in Comparative Example 5, and the electrode chamber is separated from both sides to the electrode. A polymer electrolyte fuel cell single cell consisting of a conductive separator (bipolar plate) that also functions as a gas supply passage was fabricated and subjected to a long-term operation test under a current density of 300 mA / cm ² . As a result, as indicated by 32 in FIG. 12, the output voltage was initially 0.68 V, and the output voltage disappeared after 600 hours of operation.

(Example 7)
(1) Synthesis of sulfopropylated polysulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with calcium chloride tube was purged with nitrogen, 22.1 g of polysulfone (PSU) 12.2 g (0.1 mol) of propane sultone and 50 ml of dried nitrobenzene. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After completion of the addition of anhydrous aluminum chloride, the mixture was refluxed for 24 hours. Then, the reaction product was poured into 500 ml of ice water to which 25 ml of concentrated hydrochloric acid was added to stop the reaction. The organic layer was separated, washed with water, and neutralized with an aqueous sodium carbonate solution to which a few drops of octyl alcohol was added. The aluminum hydroxide was filtered off, the filtrate was decolorized with activated carbon, and then the solvent was stripped. The obtained sulfopropylated polysulfone had an ion exchange group equivalent weight of 660 g / mol.

  The cost of sulfopropylated sulfone electrolyte is 1/50 compared to the cost of perfluorosulfonic acid electrolyte, which is expensive and can be manufactured in 5 steps because polysulfone, which is a commercially available engineer plastic, can be manufactured in 1 step. It is less expensive.

  1.0 g of sulfopropylated polysulfone electrolyte and 20 ml of ion-exchanged water were added and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of the sulfopropylated polysulfone electrolyte. As a result, the ion-exchange group equivalent weight of the sulfopropylated polysulfone electrolyte was as stable as that of the expensive perfluorosulfonic acid electrolyte at 660 g / mol, unchanged from the initial value. On the other hand, as shown in Comparative Example 5 (1), the ion exchange group equivalent weight of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3000 g / mol under the same heating hydrolysis condition, and the initial 700 g / mol. And the sulfone group was dissociated. That is, an inexpensive sulfopropylated polysulfone electrolyte, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte described in Comparative Example 5 (1) described later, shows stability as an expensive perfluorosulfonic acid electrolyte, and has a low cost. And excellent properties.

(2) Production of electrolyte membrane The product obtained in (1) was dissolved in a mixed solvent (1: 1) of trichloroethane-dichloroethane so as to have a concentration of 5% by weight. This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 80 ° C. to prepare an electrolyte membrane having a thickness of 38 μm.

  The obtained sulfopropylated polysulfone electrolyte membrane and 20 ml of ion-exchanged water were put into a SUS sealed container of polytetrafluoroethylene coating and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in (2) of Comparative Example 5, the relatively inexpensive sulfonated aromatic hydrocarbon-based electrolyte XI was broken under the same heating hydrolysis condition and was raged. That is, unlike the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane described in Comparative Example 5 (2), the inexpensive sulfopropylated polysulfone electrolyte membrane shows stability as in the case of an expensive perfluorosulfonic acid membrane. And excellent properties.

(3) Preparation of electrode catalyst coating solution and membrane / electrode assembly
To the 40% by weight platinum-supporting carbon, the mixed solution of trichloroethane-dichloroethane of (2) above is added so that the weight ratio of the platinum catalyst to the polymer electrolyte is 2: 1 and dispersed uniformly to obtain a paste ( Electrocatalyst coating solution) was prepared. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane obtained in the above (2) and then dried to prepare a membrane / electrode assembly having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly was the same as the membrane / electrode assembly produced by using a high-cost perfluorosulfonic acid membrane and a perfluorosulfonic acid electrolyte, and the membrane was solid.

  On the other hand, as shown in Comparative Example 5 (3), the membrane / electrode assembly produced using a relatively inexpensive sulfonated aromatic hydrocarbon electrolyte breaks the membrane under the same heating hydrolysis conditions, and is raged. The electrode was peeled off. That is, the inexpensive sulfopropylated sulfone electrolyte membrane / electrode assembly is different from the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 5 (3), and is an expensive perfluorosulfonic acid membrane. / Stable as in the electrode assembly, and excellent in both cost and characteristics.

(4) Evaluation of fuel cell single cell output performance The membrane / electrode assembly was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. The obtained current density-voltage plot is shown in FIG. When the current density is 1 (A / cm ² ), the output voltage is 0.75 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.83 (V). It was possible.

The solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. Reference numeral 33 in FIG. 14 represents the result of a durability test of a single fuel cell using the electrolyte membrane / electrode assembly of the present invention. 14 in FIG. 14 is the result of a durability test of a single fuel cell using a perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 33 in FIG. 14, the output voltage was 0.83 V at the initial stage, which was the same as the initial value even after 5000 hours of operation, and was the same as the result using the perfluorosulfonic acid membrane of 34 in FIG.

  On the other hand, the output voltage of 35 in FIG. 14 (single cell using the sulfonated aromatic hydrocarbon electrolyte XI of Comparative Example 5) was 0.63 V at the initial stage, and the output disappeared after 600 hours of operation time. Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using.

In addition, although the supported amount of platinum in the membrane / electrode assembly of Example 7 and Comparative Example 5 was the same as 0.25 mg / cm ² , the output voltage of the single fuel cell of Example 7 was the same as that of Comparative Example 5. The reason why the output voltage is larger than the output voltage of the single fuel cell is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 7 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 5. This is because the membrane / electrode assembly of Example 7 is superior to the membrane / electrode assembly of Comparative Example 5 because it is larger than the ionic conductivity of the working solution.

(6) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of unit cells fabricated in (5), and showed an output of 3 kW.

(Example 8 to Example 13)
After replacing the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer and reflux condenser connected with a calcium chloride tube with nitrogen, aromatic hydrocarbon polymer, sultone, and 50 ml of dried nitrobenzene were added. I put it in. With stirring, 14.7 g (0.11 mol) of anhydrous aluminum chloride was added over about 30 minutes. After the addition of anhydrous aluminum chloride, the temperature was maintained at a predetermined temperature for a predetermined time. Subsequently, the reaction product was poured into 150 ml of ice water to which 25 ml of concentrated hydrochloric acid was added to stop the reaction. Next, the reaction solution was slowly dropped into 0.5 liter of deionized water to precipitate a sulfoalkylated aromatic hydrocarbon, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. Measurement of the ion exchange group equivalent weight of the obtained sulfoalkylated aromatic hydrocarbon electrolyte, water-resistant deterioration characteristics of the electrolyte membrane and the electrolyte membrane / electrode assembly, and evaluation of the fuel cell single cell were performed.

  The results are shown in Table 1. The cost of sulfoalkylated aromatic hydrocarbon electrolytes can be manufactured in one process using commercially available inexpensive engineer plastics, so the cost of the raw materials is 1/40 compared to the cost of perfluorosulfonic acid electrolytes that are manufactured through 5 processes. It is less expensive. In addition, the ion exchange group equivalent weights after the sulfoalkylated aromatic hydrocarbon electrolytes of Examples 8 to 13 were held in ion exchange water at 120 ° C. for 2 weeks in a SUS sealed container of polytetrafluoroethylene coating were Comparative Example 1. Unlike the sulfonated aromatic hydrocarbon electrolyte, the same as in the initial stage, it is stable and excellent in both cost and characteristics as in the case of the expensive perfluorosulfonic acid electrolyte. After the sulfoalkylated aromatic hydrocarbon electrolyte membranes of Examples 8 to 13 were held in ion-exchanged water at 120 ° C. for 2 weeks in a SUS sealed container of polytetrafluoroethylene coating, the form was the sulfonated aromatic of Comparative Example 1. Unlike the hydrocarbon electrolyte membrane, it is the same as the initial perfluorosulfonic acid electrolyte membrane, and is stable and excellent in both cost and characteristics.

Even if the sulfoalkylated aromatic hydrocarbon electrolyte membrane / electrode assemblies of Examples 8 to 13 were heated in polytetrafluoroethylene coating SUS sealed containers with ion-exchanged water and 120 ° C. for 2 weeks, the sulfonation of Comparative Example 1 Unlike the aromatic hydrocarbon electrolyte membrane / electrode assembly, it does not change from the initial stage, and is stable and has excellent cost and characteristics in the same manner as the expensive perfluorosulfonic acid electrolyte membrane / electrode assembly. The output of the unit cell using the sulfoalkylated aromatic hydrocarbon electrolytes of Examples 8 to 13 after operation for 5000 hours at 300 mA / cm ² was obtained using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 1. Unlike a single battery cell, it is the same as the initial cell, and is stable and has excellent cost and characteristics as well as a single battery cell using an expensive perfluorosulfonic acid electrolyte.

(Example 14)
(1) Synthesis of chloromethylated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 21.6 g of polyethersulfone (PES), 60 g (2 mol) of paraformaldehyde, 50 ml of dried nitrobenzene were added. 73 g of hydrogen chloride gas was blown in with stirring at 10 ° C. After completion of blowing, the temperature was kept at 150 ° C. for 4 hours. Then, the reaction solution was slowly dropped into 1 liter of deionized water to precipitate chloromethylated polyethersulfone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water by a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight.

(2) Synthesis of sulfomethylated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 10 g of the chloromethylated polysulfone Ethersulfone, dried 50 ml of nitrobenzene, and 30 g of sodium sulfate were added and stirred at 100 ° C. for 5 hours. Further, 10 ml of ion exchange water was added and stirred for 5 hours. Subsequently, the reaction solution was slowly dropped into 1 liter of deionized water to precipitate sulfomethylated polyethersulfone, which was recovered by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. The obtained sulfomethylated polyethersulfone electrolyte had an ion exchange group equivalent weight of 600 g / mol.

  The cost of the sulfoalkylated polyethersulfone electrolyte obtained by this production method can be produced in two steps using polyethersulfone, which is a commercially available engineer plastic, as a raw material. Compared to the cost of acid electrolyte, it is less than 1/30. However, since the cost of the sulfoalkylated polyethersulfone electrolyte obtained by directly sulfoalkylating the polyethersulfone with sultone as in Example 1 is one step lower than the production method of Example 14, the production method of Example 14 The cost of the production method of sulfoalkylating directly with sultone is 1 / 1.5 of the cost of the resulting sulfoalkylated polyethersulfone electrolyte.

  A SUS sealed container of polytetrafluoroethylene coating was charged with 1.0 g of the obtained sulfomethylated polyethersulfone electrolyte and 20 ml of ion-exchanged water, and kept at 120 ° C. for 2 weeks. Then, it cooled and the ion exchange group equivalent weight of the sulfomethylated polyether sulfone electrolyte was measured. As a result, the ion-exchange group equivalent weight of the sulfomethylated polyethersulfone electrolyte was 600 g / mol, which was as stable as the expensive perfluorosulfonic acid electrolyte. On the other hand, as shown in (1) of Comparative Example 1, the ion-exchange group equivalent of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3000 g / mol under the same heating hydrolysis condition, and the initial value of 960 g / mol. It became larger and the sulfone group was dissociated. That is, an inexpensive sulfomethylated polyethersulfone electrolyte, unlike an inexpensive sulfonated aromatic hydrocarbon electrolyte, shows stability as an expensive perfluorosulfonic acid electrolyte, and is excellent in both cost and characteristics.

(3) Production of electrolyte membrane The sulfomethylated polyethersulfone electrolyte obtained in the above (2) was dissolved in a mixed solvent (1: 1) of trichloroethane-dichloroethane so as to have a concentration of 5% by weight. This solution was spread on glass by spin coating, air-dried, and then vacuum-dried at 8 ° C. to prepare a sulfomethylated polyethersulfone electrolyte membrane having a thickness of 42 μm.

  The obtained sulfomethylated polyethersulfone electrolyte membrane at 20 ° C. and 20 ml of ion-exchanged water were placed in a SUS sealed container of polytetrafluoroethylene coating, and held at 120 for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in Comparative Example 1 (2), the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte broke under the same heating hydrolysis conditions and was raged. That is, an inexpensive sulfomethylated polyethersulfone electrolyte membrane, unlike an inexpensive sulfonated aromatic hydrocarbon-based electrolyte membrane, exhibits stability as an expensive perfluorosulfonic acid membrane, and is excellent in both cost and characteristics. .

(4) Preparation of electrode catalyst coating solution and membrane / electrode assembly
To 40% by weight of platinum-supported carbon, the trichloroethane-dichloroethane mixed solution of (3) above was added so that the weight ratio of the platinum catalyst to the polymer electrolyte was 2: 1 and dispersed uniformly to obtain a paste ( Electrocatalyst coating solution) was prepared. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane obtained in the above (2) and then dried to prepare a membrane / electrode assembly having a platinum loading of 0.25 mg / cm ² .

  The obtained membrane / electrode assembly and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly was the same as the membrane / electrode assembly produced by using a high-cost perfluorosulfonic acid membrane and a perfluorosulfonic acid electrolyte, and the membrane was solid. On the other hand, as shown in Comparative Example 1 (3), the membrane / electrode assembly II produced using the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane II and the electrode catalyst coating solution II was heated at the same temperature. Under the hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, the inexpensive sulfomethylated polyethersulfone electrolyte membrane / electrode assembly is different from the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in (3) of Comparative Example 1 and is expensive perfluorosulfonic acid. Similar to the membrane / electrode assembly, it is stable and has excellent cost and characteristics.

(5) Evaluation of fuel cell single cell output performance The membrane / electrode assembly was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. The obtained current density-output voltage plot is shown in FIG. When the current density is 1 (A / cm ² ), the output voltage is 0.68 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.82 (V). It was possible.

The solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. 16 in FIG. 16 is a durability test result of a single fuel cell using the electrolyte membrane / electrode assembly of the present invention. In FIG. 16, 37 is the result of a durability test of a single fuel cell using a perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown at 36 in FIG. 16, the output voltage was 0.82 V in the initial stage, which was the same as the result using the perfluorosulfonic acid membrane 37 in FIG. On the other hand, the output voltage of 38 in FIG. 16 (single cell using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 1) was 0.73 V in the initial stage, and the output disappeared after 600 hours of operation.

Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, although the supported amount of platinum in the membrane / electrode assembly of Example 14 and Comparative Example 1 was the same as 0.25 mg / cm ² , the output voltage of the single fuel cell of Example 14 was that of Comparative Example 4. The reason why the output voltage of the fuel cell unit cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 14 is the membrane / electrode assembly electrolyte membrane and electrode catalyst coating of Comparative Example 1. This is because the membrane / electrode assembly of Example 14 is superior to the membrane / electrode assembly of Comparative Example 1 because it is larger than the ionic conductivity of the working solution.

(6) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of unit cells fabricated in (5), and showed an output of 3 kW.

(Example 15)
(1) Synthesis of bromohexamethylated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 23.2 g of polysulfone Ethersulfone (PES), dried 50 ml of nitrobenzene were added. To this was added 6.5 g of n-butoxylithium and kept at room temperature for 2 hours. Next, 100 g of 1,6-dibromohexane was added, and the mixture was further stirred for 12 hours. The reaction solution was slowly added dropwise to 1 liter of deionized water to precipitate bromohexamethylated polyethersulfone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight.

(2) Synthesis of sulfohexamethylated polyethersulfone After the inside of a 500 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, 10 g of the bromo Hexamethylated polyethersulfone, dried 50 ml of nitrobenzene and 30 g of sodium sulfate were added and stirred at 100 ° C. for 5 hours. Further, 10 ml of ion exchange water was added and stirred for 5 hours. Subsequently, the reaction solution was slowly dropped into 1 liter of deionized water to precipitate sulfohexamethylated polyethersulfone, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 120 ° C. overnight. The obtained sulfohexamethylated polyethersulfone had an ion exchange group equivalent weight of 600 g / mol.

  The cost of the sulfoalkylated polyethersulfone electrolyte obtained by this production method can be produced in 2 steps using polyethersulfone, which is a commercially available engineer plastic, as a raw material, so the raw material is expensive and perfluoro produced through 5 steps. Compared to the cost of sulfonic acid electrolyte, it is less than 1/30 or less. However, since the cost of the sulfoalkylated polyethersulfone electrolyte obtained by directly sulfoalkylating the polyethersulfone with sultone as in Example 1 is one step lower than the production method of Example 14, the production method of Example 14 This is 1 / 1.5 of the cost of the resulting sulfoalkylated polyethersulfone electrolyte, which is advantageous in terms of cost.

  In a polytetrafluoroethylene coating SUS sealed container, 1.0 g of the obtained sulfohexamethylated polyethersulfone electrolyte and 20 ml of ion-exchanged water were placed and kept at 120 ° C. for 2 weeks. Then, it cooled and measured the ion exchange group equivalent weight of the sulfohexamethylated polyethersulfone electrolyte. As a result, the ion-exchange group equivalent weight of the sulfohexamethylated polyethersulfone electrolyte was 600 g / mol, which was as stable as the expensive perfluorosulfonic acid electrolyte. On the other hand, as shown in (1) of Comparative Example 1, the ion-exchange group equivalent of the inexpensive sulfonated aromatic hydrocarbon electrolyte changed to 3000 g / mol under the same heating hydrolysis condition, and the initial value of 960 g / mol. It became larger and the sulfone group was dissociated. That is, an inexpensive sulfohexamethylated polyethersulfone electrolyte, unlike an inexpensive sulfonated aromatic hydrocarbon electrolyte, exhibits stability in the same manner as an expensive perfluorosulfonic acid electrolyte, and is excellent in both cost and characteristics.

(3) Preparation of electrolyte membrane N, N'-dimethylformamide-cyclohexanone-methylethylketone mixed solvent (volume ratio 20:80:25) to a concentration of 5% by weight of the product obtained in (2) above. Dissolved. This solution was spread on glass by spin coating, air dried, and then vacuum dried at 80 ° C. to prepare an electrolyte membrane having a thickness of 42 μm. The resulting sulfohexamethylated polyethersulfone electrolyte membrane had an ionic conductivity of 8 S / cm.

  The obtained sulfohexamethylated polyethersulfone electrolyte membrane and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the ionic conductivity was the same as that of the high-cost perfluorosulfonic acid membrane, and the membrane was firm. On the other hand, as shown in Comparative Example 1 (2), the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte broke under the same heating hydrolysis conditions and was raged. That is, inexpensive sulfohexamethylated polyethersulfone electrolyte membranes, unlike inexpensive sulfonated aromatic hydrocarbon electrolyte membranes, show stability as well as expensive perfluorosulfonic acid membranes, and are excellent in both cost and characteristics. ing.

(4) Preparation of electrode catalyst coating solution and membrane / electrode assembly
To 40% by weight of platinum-supported carbon, the trichloroethane-dichloroethane mixed solution of (3) above was added so that the weight ratio of the platinum catalyst to the polymer electrolyte was 2: 1 and dispersed uniformly to obtain a paste ( Electrocatalyst coating solution) was prepared. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane obtained in (3) above, and then dried to prepare a membrane / electrode assembly having a platinum loading of 0.25 mg / cm ² .

  The obtained sulfohexamethylated polyethersulfone electrolyte membrane / electrode assembly and 20 ml of ion-exchanged water were placed in a polytetrafluoroethylene coating SUS sealed container and kept at 120 ° C. for 2 weeks. As a result, the membrane / electrode assembly was the same as the membrane / electrode assembly produced by using a high-cost perfluorosulfonic acid membrane and a perfluorosulfonic acid electrolyte, and the membrane was solid. On the other hand, as shown in Comparative Example 1 (3), the membrane / electrode assembly II produced using the relatively inexpensive sulfonated aromatic hydrocarbon electrolyte membrane II and the electrode catalyst coating solution II was heated at the same temperature. Under the hydrolysis conditions, the membrane was broken and raged, and the electrode was peeled off. That is, the inexpensive sulfohexamethylated polyethersulfone electrolyte membrane / electrode assembly is different from the inexpensive sulfonated aromatic hydrocarbon electrolyte membrane / electrode assembly described in Comparative Example 1 (3), and expensive perfluorocarbon. Similar to the sulfonic acid membrane / electrode assembly, it exhibits stability and is excellent in both cost and characteristics.

(5) Evaluation of fuel cell single cell output performance The membrane / electrode assembly was absorbed by immersing it in boiling deionized water for 2 hours. The obtained membrane / electrode assembly was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. The obtained current density-output voltage plot is shown in FIG. When the current density is 1 (A / cm ² ), the output voltage is 0.68 (V), and when the current density is 300 (mA / cm ² ), the output voltage is 0.83 (V). It was possible.

The solid polymer fuel cell single cell was subjected to a long-time operation test under a current density of 300 mA / cm ² . The result is shown in FIG. Reference numeral 39 in FIG. 18 represents the result of a durability test of a single fuel cell using the electrolyte membrane / electrode assembly of the present invention. Reference numeral 40 in FIG. 18 denotes a durability test result of the single fuel cell using the perfluorosulfonic acid electrolyte membrane / electrode assembly. As shown by 39 in FIG. 18, the output voltage was 0.83 V in the initial stage, which was the same as the result of using the perfluorosulfonic acid membrane 40 in FIG. On the other hand, the output voltage of 41 in FIG. 18 (a fuel cell single cell using the sulfonated aromatic hydrocarbon electrolyte of Comparative Example 1) was 0.73 V at the initial stage, and the output disappeared after 600 hours of operation.

Therefore, an aromatic hydrocarbon electrolyte in which a fuel cell unit cell using an aromatic hydrocarbon electrolyte in which a sulfonic acid group is bonded to an aromatic ring of an aromatic hydrocarbon via an alkyl group is directly bonded to the sulfone group. It is apparent that the fuel cell is superior in durability compared to a single fuel cell using. In addition, although the supported amount of platinum in the membrane / electrode assembly of Example 15 and Comparative Example 1 was the same as 0.25 mg / cm ² , the output voltage of the single fuel cell of Example 15 was that of Comparative Example 4. The reason why the output voltage of the fuel cell unit cell is larger is that the ionic conductivity of the electrolyte membrane and electrode catalyst coating solution of Example 15 is the electrolyte membrane and electrode catalyst coating of the membrane / electrode assembly of Comparative Example 1. This is because the membrane / electrode assembly of Example 15 is superior to the membrane / electrode assembly of Comparative Example 1, which is larger than the ionic conductivity of the working solution.

(6) Fabrication of fuel cell A polymer electrolyte fuel cell was fabricated by laminating 36 layers of unit cells fabricated in (5), and showed an output of 3 kW.

  As described above, in any of the examples, the sulfoalkylated aromatic hydrocarbon-based electrolyte can be manufactured in one process using cheap engineer plastic as a raw material. Compared to fluorine electrolyte membranes typified by acid membranes, its cost is less than 1/40 and has high productivity that can be manufactured in one process. In addition, by bonding a sulfonic acid group to an aromatic ring through an alkyl group, unlike a sulfonic acid group directly bonded to an aromatic ring, the ionic conductivity is large and the sulfonic acid group is dissociated under strong acid and high temperature. It shows high durability enough for practical use. Furthermore, the membrane / electrode assembly using the sulfoalkylated aromatic hydrocarbon-based electrolyte according to the present invention exhibits high durability practically sufficient as a fuel cell, and can shorten the manufacturing process.

The figure which shows the structure of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells. The figure which shows the current density-output voltage of the battery single cell for polymer electrolyte fuel cells. The figure which shows the durability test result of the battery single cell for polymer electrolyte fuel cells.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polymer electrolyte membrane, 2 ... Oxygen electrode, 3 ... Hydrogen electrode, 4 ... Membrane / electrode assembly, 5 ... Current collector, 6 ... Separator, 7 ... Air, 8 ... Air + water, 9 ... Hydrogen + water, 10… residual hydrogen, 11… water.

Claims (2)

The aromatic hydrocarbon polymer compound having a sulfoalkyl group represented by the formula (Chemical formula 1) in the side chain, wherein the aromatic hydrocarbon polymer compound is a polyethersulfone polymer compound, polyetherether ketone-based polymer compound, polyphenylene monkey fit-based polymers compounds, polyphenylene ether polymer compound, that is one that more Do uncrosslinked polymer polysulfone-based polymer compound and a polyether ketone polymer compound A solid polymer electrolyte for fuel cells .

The aromatic hydrocarbon polymer compound having a sulfoalkyl group represented by the formula (Chemical formula 1) in the side chain, wherein the aromatic hydrocarbon polymer compound is a polyethersulfone polymer compound, polyetherether ketone-based polymer compound, polyphenylene monkey fit-based polymers compound, the polyphenylene ether-based polymer compounds, solid high is any that more Do uncrosslinked polymer polysulfone-based polymer compound and a polyether ketone polymer compound A fuel cell membrane / electrode assembly comprising a molecular electrolyte membrane and electrodes disposed on both sides of the polymer electrolyte membrane.

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