JP2016033894A - Membrane-electrode assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane-electrode assembly which enables the improvement of a fuel cell in endurance.SOLUTION: In a membrane-electrode assembly, at least one of an anion exchange type solid polymer fuel cell electrolytic film 4, an anode electrode 2 and a cathode electrode 3 includes a peroxide decomposing catalyst selected from manganese and an alloy including manganese, and at least one of their oxides.SELECTED DRAWING: None

Description

  The present invention relates to a membrane electrode assembly, and more particularly to a membrane electrode assembly used in a fuel cell such as a polymer electrolyte fuel cell.

  Conventionally, various fuel cells such as alkaline type (AFC), solid polymer type (PEFC), phosphoric acid type (PAFC), molten carbonate type (MCFC), and solid electrolyte type (SOFC) are known as fuel cells. Yes. These fuel cells are being studied for use in various applications such as automobile applications.

  Examples of such a polymer electrolyte fuel cell include an electrolyte membrane made of a solid polymer membrane, a fuel side electrode (anode) formed on one surface of the electrolyte membrane, and oxygen formed on the other surface of the electrolyte membrane. A fuel cell including a membrane electrode assembly integrally including a side electrode (cathode) is known (see, for example, Patent Document 1).

  In such a fuel cell, fuel is supplied to the anode and air is supplied to the cathode, so that an electromotive force is generated between the anode and the cathode to generate electric power.

JP 2012-157811 A

  However, in the fuel cell described in Patent Document 1 described above, further improvement in durability has been studied.

  Accordingly, an object of the present invention is to provide a membrane electrode assembly capable of improving the durability of a fuel cell.

  The membrane electrode assembly of the present invention comprises an anion exchange type electrolyte membrane, an anode electrode formed on one surface of the electrolyte membrane, and a cathode electrode formed on the other surface of the electrolyte membrane, And at least one of the anode electrode and the cathode electrode contains a peroxide decomposition catalyst selected from manganese, an alloy containing manganese, and at least one of oxides thereof. It is said.

  According to the membrane electrode assembly of the present invention, at least one of the electrolyte membrane, the anode electrode, and the cathode electrode is manganese, an alloy containing manganese, and at least one of those oxides as a peroxide decomposition catalyst. Contains one of them.

  Therefore, the peroxide generated by the side reaction of the oxygen reduction reaction at the cathode electrode can be decomposed.

  As a result, it can suppress that a membrane electrode assembly deteriorates with a peroxide.

  Thereby, the durability of the membrane electrode assembly of the present invention can be improved, and as a result, the durability of the fuel cell can be improved.

FIG. 1 is a schematic configuration diagram of a fuel cell in which the membrane electrode assembly of the present invention is used. FIG. 2 shows changes over time in the anode potential, cathode potential, and cell voltage of a fuel cell evaluation cell using the membrane electrode assembly of the example. FIG. 3 shows changes with time in the anode potential, cathode potential, and cell voltage of the fuel cell evaluation cell using the membrane electrode assembly of the comparative example. FIG. 4 shows the change over time in the rated output of the fuel cell evaluation cell using the membrane electrode assemblies of Examples and Comparative Examples.

1. 1 is a schematic configuration diagram of a fuel cell in which the membrane electrode assembly of the present invention is used.

  The fuel cell 1 is a polymer electrolyte fuel cell, and includes a plurality of fuel cells S, and is formed as a stack structure in which these fuel cells S are stacked. In FIG. 1, only one fuel cell S is shown for easy illustration.

  The fuel cell S includes a membrane electrode assembly A, a fuel supply member 5, and an oxygen supply member 6.

  The membrane electrode assembly A includes an electrolyte layer 4, an anode electrode 2, and a cathode electrode 3.

The electrolyte layer 4 is formed from an anion exchange membrane. The anion exchange membrane is not particularly limited as long as it is a medium capable of moving hydroxide ions (OH ⁻ ) as anion components generated at the cathode electrode 3 from the cathode electrode 3 to the anode electrode 2. Examples thereof include a solid polymer membrane (anion exchange resin) having an anion exchange group such as a quaternary ammonium group and a pyridinium group.

  The anode electrode 2 is formed on one surface of the electrolyte layer 4 by an electrode material such as a catalyst carrier carrying a catalyst. Further, without using the catalyst carrier, catalyst particles may be used as the electrode material, and the catalyst particles may be directly formed as the anode electrode 2.

  The catalyst is not particularly limited, and examples thereof include platinum group elements (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt)), iron group elements ( According to a periodic table such as iron (Fe), cobalt (Co), nickel (Ni)) (IUPAC Periodic Table of the Elements (version date 22 June 2007), the same applies hereinafter) Group 8 to 10 (VIII) elements, For example, periodic table 11th group (IB) elements, such as copper (Cu), silver (Ag), and gold (Au), and simple metals such as zinc (Zn), and alloys thereof may be used.

  These can be used alone or in combination of two or more.

  Examples of the catalyst carrier include porous substances such as carbon. The amount of the catalyst supported on the catalyst carrier is not particularly limited, and is appropriately set according to the purpose and application.

  In order to produce the anode electrode 2, for example, first, the above-described catalyst and ionomer are dispersed in an organic solvent to prepare a dispersion. Next, the dispersion is applied to one surface of the electrolyte layer 4 and dried to obtain the anode electrode 2.

  Examples of the ionomer include an anion exchange resin having an anion exchange group.

  Examples of the organic solvent include known solvents such as lower alcohols such as methanol, ethanol, 1-propanol, and 2-propanol, ethers such as tetrahydrofuran, and water. These solvents can be used alone or in combination of two or more.

In the anode electrode 2, the amount of the catalyst attached to the electrolyte layer 4 is, for example, 0.01 mg / cm ² or more, for example, 10 mg / cm ² or less.

  The thickness of the anode electrode 2 is, for example, 10 μm or more, preferably 20 μm or more, and for example, 200 μm or less, preferably 100 μm or less.

  The cathode electrode 3 is formed by the method described later on the other surface of the electrolyte layer 4 (the surface opposite to the surface on which the anode electrode 2 is formed) using an oxygen reduction catalyst described later instead of the above-described catalyst. Has been.

  The thickness of the cathode electrode 3 is, for example, 0.1 μm or more, preferably 1 μm or more, and for example, 100 μm or less, preferably 10 μm or less.

  The fuel supply member 5 is made of a gas-impermeable conductive member, and one surface thereof is opposed to the anode electrode 2. In the fuel supply member 5, a fuel-side flow path 7 for bringing fuel into contact with the entire anode electrode 2 is formed as a distorted groove that is recessed from one surface. In addition, the fuel supply member 5 has a supply port 8 and a discharge port 9 communicating with the fuel-side flow path 7 at its upstream end and downstream end.

  Similar to the fuel supply member 5, the oxygen supply member 6 is made of a gas-impermeable conductive member, and one surface thereof is in contact with the cathode electrode 3. In the oxygen supply member 6, an oxygen-side flow path 10 for bringing oxygen (air) into contact with the entire cathode electrode 3 is formed as a twisted groove recessed from one surface. The oxygen supply member 6 has a supply port 11 and a discharge port 12 communicating with the oxygen-side flow path 10 at the upstream end portion and the downstream end portion thereof.

  In the fuel cell 1, the fuel containing the fuel compound is supplied to the fuel side flow path 7 through the supply port 8 of the fuel supply member 5, and oxygen (air) passes through the supply port 11 of the oxygen supply member 6. To the oxygen-side flow path 10.

  Examples of the fuel compound include alcohols such as methanol, ethers having an alkyl group such as dimethyl ether, hydrazines, and the like, preferably alcohols and hydrazines, and more preferably hydrazines. It is done.

Examples of hydrazines include hydrazine (NH ₂ NH ₂ ), hydrated hydrazine (NH ₂ NH ₂ .H ₂ O), hydrazine carbonate ((NH ₂ NH ₂ ) ₂ CO ₂ ), and hydrazine hydrochloride (NH ₂ NH _2). HCl), hydrazine sulfate (NH ₂ NH ₂ .H ₂ SO ₄ ), monomethyl hydrazine (CH ₃ NHNH ₂ ), dimethyl hydrazine ((CH ₃ ) ₂ NNH ₂ , CH ₃ NHNHCH ₃ ), carboxylic hydrazide ((NHNH ₂ ) ₂ CO).

Among such hydrazines, preferably, hydrazines containing no carbon, that is, hydrazine, hydrated hydrazine, hydrazine sulfate, and the like. Hydrazine, hydrated hydrazine, hydrazine sulfate, etc. do not generate CO and CO ₂ and do not cause poisoning of the catalyst. Therefore, durability can be improved and substantially zero emission can be realized. it can.

  Such fuel components can be used alone or in combination of two or more.

  As the fuel, the fuel compound exemplified above may be used as it is, but the fuel compound exemplified above is used as a solution such as water and / or alcohol (for example, lower alcohol such as methanol, ethanol, propanol, isopropanol). Can be used.

For example, when the electrolyte membrane 4 is an anion exchange type solid polymer membrane and the fuel compound is hydrazine, an electrochemical reaction of the following formulas (1) to (3) occurs and an electromotive force is generated. .
(1) N ₂ H ₄ + 4OH ⁻ → N ₂ + 4H ₂ O + 4e ⁻ (reaction at anode electrode 2)
(2) O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (reaction at cathode electrode 3)
(3) N ₂ H ₄ + O ₂ → N ₂ + 2H ₂ O (reaction in the entire fuel cell 1)
That is, in the anode electrode 2, hydrazine (N ₂ H ₄ ) reacts with hydroxide ions (OH ⁻ ) generated by the reaction at the cathode electrode 3 to react with nitrogen (N ₂ ) and water (H ₂ O). Are generated and electrons (e ⁻ ) are generated (see the above formula (1)).

On the other hand, at the cathode electrode 3, electrons (e ⁻ ), water (H ₂ O) generated by reaction from the outside or the fuel cell 1, and oxygen (O ₂ ) react to generate hydroxide. Ion (OH ⁻ ) is generated (see the above formula (2)). The generated hydroxide ions (OH ⁻ ) pass through the electrolyte membrane 4 and are supplied to the anode electrode 2.

  When such an electrochemical reaction occurs continuously, the reaction represented by the above formula (3) occurs in the fuel cell 1 as a whole, and an electromotive force is generated.

2. Membrane electrode assembly The membrane electrode assembly A described above contains a peroxide decomposition catalyst having peroxide decomposition activity in the cathode electrode 3.

  Specifically, the oxygen reduction catalyst of the cathode electrode 3 contains a first component having oxygen reduction activity and a second component as a peroxide decomposition catalyst.

  Examples of the first component include a fired body of a transition metal complex in which an organic compound is coordinated to a transition metal, and a composite in which a transition metal is supported on a carbon composite composed of a conductive polymer and carbon.

  Examples of the transition metal include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu ), Yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), lanthanum (La) ), Hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), and the like.

  Examples of the organic compound coordinated to the transition metal include pyrrole, porphyrin, tetramethoxyphenylporphyrin, dibenzotetraazaannulene, phthalocyanine, choline, chlorin, phenanthroline, salcomine, nicarbazine, and polymers thereof.

  As the conductive polymer, there is a compound overlapping with the above organic compound, for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyvinylcarbazole, polytriphenylamine, polypyridine, polypyrimidine, polyquinoxaline, polyphenylquinoxaline, polyphenyl Examples include isothianaphthene, polypyridinediyl, polythienylene, polyparaphenylene, polyflurane, polyacene, polyfuran, polyazulene, polyindole, and polydiaminoanthraquinone.

  The first component is preferably a fired body of an iron complex in which an organic compound is coordinated to iron. The first component can be used alone or in combination of two or more.

  The first component is contained in the oxygen reduction catalyst, for example, 50% by weight or more, preferably 70% by weight or more, for example, 99% by weight or less, preferably 90% by weight or less.

  To prepare the first component, for example, when the first component is a fired product of a transition metal complex, a salt of a transition metal (for example, an inorganic salt such as sulfate, nitrate, chloride, phosphate, An organic acid salt such as acetate and oxalate) and an organic compound in a known solvent such as water, alcohol, aliphatic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon, and nitrile. By mixing, a transition metal complex can be produced.

  The solution or dispersion of the transition metal complex thus prepared is dried if necessary and then calcined.

  In the firing, for example, heating is performed in an atmosphere of an inert gas (for example, nitrogen gas, argon gas, or the like) or a reducing gas (for example, a mixed gas of nitrogen gas and hydrogen gas).

  Moreover, a calcination temperature is 850 degreeC or more, for example, Preferably, it is 900 degreeC or more, for example, is 1500 degrees C or less. The firing time is, for example, 1 hour or longer, and for example, 10 hours or shorter, preferably 5 hours or shorter.

  The transition metal complex can be fired in one step or in multiple steps.

  When drying, the drying temperature is, for example, −25 ° C. or more, preferably 15 ° C. or more, and for example, 80 ° C. or less, preferably 50 ° C. or less. The drying time is, for example, 12 to 48 hours.

  Thereby, the sintered body of the transition metal complex can be obtained as the first component.

  The second component is selected from at least one of manganese, an alloy containing manganese, and oxides thereof.

Specifically, as the second component, for example, manganese, for example, manganese dioxide (MnO ₂ ), manganese oxide such as manganese oxide (MnO, Mn ₂ O ₃ , Mn ₃ O ₄ ), for example, AlMn, CrMn, Alloys containing manganese such as FeMn, CoMn, NiMn, CuMn, for example, manganese such as Fe ₂ MnO ₄ , FeMn ₂ O ₄ , La ₂ MnO ₄ , LaMn ₂ O ₄ , Sr ₂ MnO ₄ , SrMn ₂ O ₄ The oxide of the alloy to contain is mentioned.

  The second component is preferably manganese and manganese oxide, more preferably manganese oxide.

  The second component is contained in the oxygen reduction catalyst, for example, 1% by weight or more, preferably 10% by weight or more, for example, 50% by weight or less, preferably 30% by weight or less.

  The second component is blended at a ratio of, for example, 1 part by weight or more, preferably 11 parts by weight or more, for example, 100 parts by weight or less, preferably 43 parts by weight or less, relative to 100 parts by weight of the first component. Is done.

  The oxidation-reduction catalyst is obtained, for example, by blending and mixing the first component and the second component at the blending ratio described above.

  In order to produce the cathode electrode 3 using an oxygen reduction catalyst, for example, first, an oxygen reduction catalyst and an ionomer are dispersed in an organic solvent to prepare a dispersion. Next, the dispersion is applied to the other surface of the electrolyte layer 4 (the surface opposite to the surface on which the anode electrode 2 is formed) and dried to obtain the cathode electrode 3.

  Examples of the ionomer include an anion exchange resin having an anion exchange group.

  Examples of the organic solvent include known solvents such as lower alcohols such as methanol, ethanol, 1-propanol, and 2-propanol, ethers such as tetrahydrofuran, and water. These solvents can be used alone or in combination of two or more.

  The oxygen reduction catalyst is contained in the cathode electrode 3 by, for example, 50% by weight or more, preferably 70% by weight or more, for example, 90% by weight or less, preferably 80% by weight or less.

In the cathode electrode 3, the adhesion amount of the oxygen reduction catalyst to the electrolyte layer 4 is, for example, 0.01 mg / cm ² or more, for example, 10 mg / cm ² or less.

  The oxidation-reduction catalyst is prepared by mixing the first component and the second component in the ionomer and the organic solvent when the cathode electrode 3 is produced without previously mixing the first component and the second component. A dispersion can also be prepared.

In the power generation in the fuel cell 1 described above, since the electrolyte membrane 4 is made of an anion exchange membrane, the electrochemical reaction (reaction of the above formula (2)) at the cathode electrode 3 proceeds in an alkaline environment. In this case, HO ₂ ⁻ (peroxide) may be generated as a side reaction product.

  However, according to this membrane electrode assembly A, at least one of the electrolyte membrane 4, the anode electrode 2 and the cathode electrode 3 is used as a peroxide decomposition catalyst, manganese, an alloy containing manganese, and oxidation thereof. Contains at least one of the objects.

Therefore, peroxide (HO ₂ ⁻ ) generated by a side reaction in the oxygen reduction reaction can be decomposed.

The oxidation reaction (decomposition reaction) of this peroxide (HO ₂ ⁻ ) is represented by the following formula (4).
(4) HO ₂ ⁻ + H ₂ O + 2e ⁻ → 3OH ⁻ +0.87 V (vs. SHE)
As a result, the membrane electrode assembly A can be prevented from being deteriorated by the peroxide (HO ₂ ⁻ ).

  Thereby, when the membrane electrode assembly A of this invention is used for the fuel cell 1, the durability of the fuel cell 1 can be improved.

Further, the rated output (output when the current value is constant) of the fuel cell 1 can be improved.
3. Modified Example of Membrane Electrode Assembly (1) In the membrane electrode assembly A described above, the anode electrode 2 can contain a peroxide decomposition catalyst without containing the peroxide decomposition catalyst in the cathode electrode 3.

  In order to make the anode electrode 2 contain the peroxide decomposition catalyst, for example, when the anode electrode 2 is formed by the above-described method, a dispersion containing the anode electrode 2 catalyst and the peroxide decomposition catalyst is prepared. Then, the dispersion is applied to the electrolyte membrane 4 to form the anode electrode 2.

  The peroxide decomposition catalyst is, for example, 1% by weight or more, preferably 10% by weight or more, for example, 50% by weight or less, preferably 30% in the total amount of the catalyst of the anode electrode 2 and the peroxide decomposition catalyst. Less than wt% is included.

The peroxide decomposition catalyst is, for example, 1 part by weight or more, preferably 11 parts by weight or more, for example, 100 parts by weight or less, preferably 43 parts by weight or less, with respect to 100 parts by weight of the catalyst of the anode electrode 2. It is blended at a ratio of
(2) Further, in the membrane electrode assembly A described above, the cathode membrane 3 can contain a peroxide decomposition catalyst, but the electrolyte membrane 4 can contain a peroxide decomposition catalyst.

In order to contain the peroxide decomposition catalyst in the electrolyte membrane 4, for example, the peroxide decomposition catalyst is supported on the anion exchange resin by using a known surface treatment technique or a known pore filling technique.
(3) Moreover, the above-described embodiment and each modification can be combined with each other. Specifically, in the membrane electrode assembly A described above, the anode electrode 2, the cathode electrode 3 and the electrolyte membrane 4 can all contain a peroxide decomposition catalyst. Further, the peroxide decomposition catalyst can be contained in the anode electrode 2 and the cathode electrode 3 without containing the peroxide decomposition catalyst in the electrolyte membrane 4. Further, the peroxide decomposition catalyst can be contained in the cathode electrode 3 and the electrolyte membrane 4 without containing the peroxide decomposition catalyst in the anode electrode 2. Further, the peroxide decomposition catalyst can be contained in the anode electrode 2 and the electrolyte membrane 4 without containing the peroxide decomposition catalyst in the cathode electrode 3.
4). Modified Example of Manufacturing Method of Membrane / Electrode Assembly (1) When the above transition metal complex is fired, the fired body of the transition metal complex aggregates and grows, and its effective surface area decreases, resulting in catalytic activity. May decrease.

  Therefore, in order to ensure a sufficient effective surface area, it is preferable to form pores in the granular material in which the transition metal complex is aggregated and grown to form a porous fired body.

It does not restrict | limit especially as a method of forming a porous baked body, A well-known method is mentioned.
For example, first, a method of firing a particle mixture of a transition metal complex and soluble particles to produce a composite containing the transition metal complex and soluble particles at random, and then removing the soluble particles in the composite. Can be mentioned.

  Although it does not restrict | limit especially as a soluble particle, For example, at the time of mixing a complex mixture and a soluble particle, it can disperse | distribute uniformly to a complex mixture, and it distributes uniformly to a composite, without melt | dissolving by said baking, Examples of the particles that are dissolved and removed by firing with an acid or alkali after firing are exemplified.

  Examples of such soluble particles include amorphous silica such as fumed silica and colloidal silica, polymer particles such as polystyrene and polyimide, and fired bodies thereof.

  These soluble particles can be used alone or in combination of two or more, preferably amorphous silica, more preferably fumed silica.

  In this method, for example, first, the transition metal complex and the soluble particles are mixed before the firing.

  In order to mix the transition metal complex and the soluble particles, for example, first, the transition metal complex is dissolved or dispersed in a solvent.

  Although it does not restrict | limit especially as a solvent, For example, water, for example, protic polar solvent (For example, alcohol, such as methanol, ethanol, isopropanol, glycol, etc.), aprotic polar solvent (for example, acetone, N, N-dimethyl). Formamide (DMF), N, N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), acetonitrile, piperidine, etc.), amines (eg, ammonia, eg, triethylamine, pyridine, etc.), Ethers (for example, dioxane, tetrahydrofuran (THF), etc.), aromatic hydrocarbons (for example, benzene, toluene, xylene, etc.) and the like can be mentioned.

  These solvents can be used alone or in combination of two or more, and preferably include tetrahydrofuran, acetone and the like.

  The mixing ratio of the transition metal complex and the solvent is such that the solvent is, for example, 1 part by mass or more, preferably 10 parts by mass or more, for example, 100000 parts by mass or less, with respect to 100 parts by mass of the transition metal complex. Preferably, it is 50000 parts by mass or less.

  Next, the obtained transition metal complex solution or dispersion and the soluble particles are mixed by a known method such as wet mixing.

  The blending ratio of the transition metal complex solution or dispersion and the soluble particles is, for example, that the soluble particles contain, for example, 100 parts by mass of the transition metal complex (solid content) in the transition metal complex solution or dispersion, for example, It is 10 parts by mass or more, preferably 50 parts by mass or more, and for example, 500 parts by mass or less, preferably 200 parts by mass or less.

  Thereby, a solution or dispersion of the transition metal complex and soluble particles is obtained.

  Then, in this method, the obtained transition metal complex and soluble particle solution or dispersion are dried.

  As drying conditions, the drying temperature is, for example, −25 ° C. or higher, preferably 15 ° C. or higher, and for example, 80 ° C. or lower, preferably 50 ° C. or lower. The drying time is, for example, 12 to 48 hours.

  Next, under the above firing conditions, the mixture of the transition metal complex and the soluble particles is fired to obtain a composite containing the transition metal complex and the soluble particles at random.

  The method then removes the soluble particles in the composite.

  For example, when amorphous silica is used as the soluble particles, the amorphous silica may be crystallized by firing to form silica (fired body). In such a case, in order to remove the silica, for example, the composite is treated with an alkali.

  As the alkali treatment, the composite is impregnated with an alkaline solution such as potassium hydroxide or sodium hydroxide. Thereby, the soluble particles in the composite are dissolved to form pores, and as a result, a porous fired body is obtained.

  According to such a porous fired body, even when the transition metal complex aggregates and grows by firing, the effective surface area of the transition metal complex is sufficiently secured by the pores. Can be maintained.

The method for removing the soluble particles is not limited to the above, and can be appropriately selected according to the type of the soluble particles, such as a method of immersing in water or an acid treatment method.
(2) The first component or the second component described above can be carried on a carrier such as carbon particles.

  In order to support the first component or the second component on the support, for example, the support is mixed with the solution or dispersion of the first component or the second component described above, and then fired. The mixing ratio of the carrier is, for example, 10 parts by mass or more, preferably 50 parts by mass or more, and for example, 500 parts by mass or less, preferably 100 parts by mass of the first component or the second component. It is 200 parts by mass or less.

  Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example.

1) Production of Membrane / Electrode Assembly Example Nicarbazin Fe complex (NPC-2000, manufactured by Pajarito) as the first component and manganese oxide-supported carbon as the second component (support comprising manganese oxide made of carbon particles) And an ionomer were dispersed in an organic solvent to prepare a cathode electrode ink (dispersion).

  More specifically, 0.04 g of nicarbazine Fe complex, 0.01 g of manganese oxide-supported carbon, anion exchange ionomer as an electrolyte resin (hydrocarbon ionomer solution, ionomer concentration: 2% by mass, solvent (tetrahydrofuran: 1-propanol = 1) : 1 (mass ratio))) in a solid content of 0.017 g and a mixed solution of 1-propanol and tetrahydrofuran as a solvent (1-propanol: tetrahydrofuran = 1: 1 (mass ratio)) A cathode electrode ink was prepared.

  Moreover, 0.15 g of nickel zinc alloy (NiZn) (AQ672078, Ni: 87 mass%, Zn: 13 mass%, average particle diameter: 3 μm, manufactured by Cabot), which is a nickel-based metal as an anode catalyst, as an electrolyte resin Anion exchange type ionomer (hydrocarbon ionomer solution, ionomer concentration: 2 mass%, solvent (tetrahydrofuran: 1-propanol = 1: 1 (mass ratio))) in a solid content of 0.017 g, and 1 as the solvent 2 g of a mixed solution of propanol and tetrahydrofuran (1-propanol: tetrahydrofuran = 1: 1 (mass ratio)) was mixed to prepare an anode electrode ink.

Thereafter, the anode electrode ink was applied to the surface of one side of the anion exchange electrolyte membrane (A201CE Tokuyama Co., Ltd.) so that the amount of the anode catalyst was 2.6 mg / cm ^2, and the amount of cathode catalyst (the first catalyst was applied to the other side surface). The cathode electrode ink was applied so that the surface area after drying was 4 cm ² so that the total amount of the component and the second component was 1.0 mg / cm ² , thereby producing a membrane electrode assembly. .

  Thereafter, the solvent was evaporated in the atmosphere, and the obtained membrane / electrode assembly was immersed in 1M KOH for 12 hours or more.

Comparative Example A membrane / electrode assembly was produced in the same manner as in the above-described example except that 0.01 g of ketjen black was blended instead of manganese oxide-supporting carbon.

2) Durability evaluation Membrane electrode assemblies obtained in Examples and Comparative Examples were set in a fuel cell evaluation cell (Lab cell, manufactured by Daihatsu Kogyo Co., Ltd.). A mixed solution with hydrated hydrazine was supplied to the cathode side at a flow rate of 1.2 ml / min and 100 cc / min, respectively, and the current density (200 mA / cm) was obtained with an electronic load device (890e, manufactured by Scribner Associates). ² ) was controlled to be constant, and the anode potential, cathode potential, cell voltage and rated output were measured.

The measurement conditions are shown below.
Cell temperature: 60 ° C
Cathode temperature: 60 ° C
Anode temperature: 60 ° C
Humidity (RH): 50%
Back pressure; anode: 0 kPa, cathode: 10 kPa
FIG. 2 shows changes over time in the anode potential, cathode potential, and cell voltage using the membrane electrode assembly of Example, and shows changes over time in the anode potential, cathode potential, and cell voltage using the membrane electrode assembly of Comparative Example. As shown in FIG. Further, FIG. 4 shows changes with time in the rated output of the examples and comparative examples.

  In the above examples and comparative examples, manganese oxide is supported on carbon in order to sufficiently secure the initial performance of the fuel cell.

  Further, as shown in FIG. 2, it can be seen that in the example in which the cathode electrode contains manganese oxide, not only the cathode electrode but also the anode electrode can be used up to around 400 h.

  On the other hand, as shown in FIG. 3, in the comparative example in which the cathode electrode does not contain manganese oxide, the anode electrode cannot be used in the vicinity of 200 h.

  From this, if the peroxide decomposition catalyst is contained in any one of the anode electrode, the cathode electrode and the electrolyte membrane among the membrane electrode assemblies, the durability of the entire membrane electrode assembly can be improved. I understand that I can do it.

Claims (1)

An anion exchange type electrolyte membrane;
An anode electrode formed on one surface of the electrolyte membrane;
A cathode electrode formed on the other surface of the electrolyte membrane,
At least one of the electrolyte membrane, the anode electrode, and the cathode electrode contains a peroxide decomposition catalyst selected from manganese, an alloy containing manganese, and at least one of oxides thereof. A membrane electrode assembly characterized by that.

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