JP2009252471A - Solid polymer electrolyte for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer fuel cell of a high output and high durability, by making an electrolyte film of low cost by turning into practical application of a PEFC or a DMFC, of high ionic conductivity, and with less variations in the dimensions under water in an area direction, due to superior water resistance. <P>SOLUTION: With the use of a block copolymer with a glass transition temperature of a hydrophobic segment which does not contain an ion-exchange group in a main chain nor in side chains, or with a larger equivalent weight of an ion exchange group than that of a hydrophilic segment which is substantially the same as or higher than a glass transition temperature of a hydrophilic segment containing an ion exchange group; and further, when the hydrophobic segment in that block copolymer includes a specific average molecular weight, it is found that an electrolyte film with higher ionic conductivity, and with little variation of dimensions underwater in a plane direction is obtained, leading to the invention. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid polymer electrolyte for a fuel cell, and more particularly to a polymer electrolyte membrane having high ionic conductivity and excellent water resistance.

  Examples of solid polymer electrolyte membranes used in polymer electrolyte fuel cells include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Chemicals), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Although a fluorine-based electrolyte membrane having a high ionic conductivity is known, the fluorine-based electrolyte membrane is very expensive.

  Furthermore, since ionic conductivity falls at high temperature, there exists a subject that it cannot be used at high temperature.

  Further, when used as an electrolyte membrane of a direct methanol fuel cell (hereinafter referred to as DMFC), there are problems such as voltage drop and power generation efficiency drop due to methanol crossover.

  As a polymer electrolyte membrane for a polymer electrolyte fuel cell, an aromatic electrolyte membrane having an ion exchange group is used in addition to a fluorine electrolyte membrane.

  Patent Document 1 and Patent Document 2 include a block copolymer composed of a polyethersulfone block having a sulfone group and a polyethersulfone block having no sulfonic acid group, and a polyetherketone block and sulfone having a sulfonic acid group. A block copolymer comprising a polyether ketone block having no acid group is disclosed.

  However, it is difficult to obtain sufficient water resistance only by using an electrolyte membrane using these polyethersulfone block copolymers and polyetherketone block copolymers, so the dimensional change in the area direction in water Is large, has a problem in durability, and has a small effect on improving ionic conductivity.

  In addition, Patent Documents 1 and 2 do not describe the glass transition temperature of the hydrophilic segment and the hydrophobic segment and the relationship thereof, and the average molecular weight of the hydrophilic segment and the hydrophobic segment is also different from the intended molecular weight of the present invention. Yes.

  Moreover, in the transmission electron microscope observation of the metal-substituted electrolyte membrane described in Patent Document 3, only the phase separation structure in the vacuum atmosphere was confirmed, and the relationship with the actual proton conductivity was unknown.

  The phase separation structure during humidification is also measured by an AFM (atomic force microscope) or the like, but AFM is an analysis method for the surface of the electrolyte membrane, and the phase separation structure of the entire membrane has not been evaluated.

  Furthermore, there is a method of reinforcing the electrolyte membrane with a reinforcing material to reduce the dimensional change of the electrolyte membrane.

Patent Document 4 discloses a solid polymer electrolyte composite membrane in which pores of a porous thin film made of polyolefin having a weight average molecular weight of 5 × 10 ⁵ or more are filled with an ion exchange resin. However, the solid polymer electrolyte composite membrane has a problem of low ionic conductivity.

JP 2003-031232 A JP 2006-512428 A JP 2005-190830 A JP-A 64-022932

  Accordingly, an object of the present invention is to produce an electrolyte membrane that is inexpensive, has high ionic conductivity, and has a small dimensional change in the area in water in order to have excellent water resistance. A further object is to provide a polymer electrolyte fuel cell with high output and high durability.

  In view of the above situation, in order to have excellent water resistance in an aromatic electrolyte membrane, an electrolyte membrane having a small dimensional change of the electrolyte membrane in water and having high proton conductivity was developed.

  As a result of intensive studies to achieve the above object, the present inventors have found that a block copolymer in which the glass transition temperature of the hydrophobic segment is substantially the same or higher than the glass transition temperature of the hydrophilic segment. In addition, it can be seen that when the hydrophobic segment in the block copolymer has a specific average molecular weight, an electrolyte membrane having high ionic conductivity and small dimensional change in the plane direction in water can be obtained. The present invention has been reached.

That is, in the present invention, it comprises a hydrophilic segment containing an ion exchange group and a hydrophobic segment substantially not containing an ion exchange group or having a smaller ion exchange amount than the hydrophilic segment, and the number average molecular weight of the hydrophobic segment. The present invention provides a block copolymer having a Mn of 1.0 × 10 ^{4 to} 5.0 × 10 ⁴ or a weight average molecular weight Mw of 1.5 × 10 ⁴ to 1.5 × 10 ⁵ .

  In the block copolymer of the present invention, the glass transition temperature of the film formed by forming only the hydrophobic segment is substantially the same as the glass transition temperature of the film formed by forming only the hydrophilic segment or High temperature is preferred.

  The block copolymer of the present invention is preferably a solid polymer electrolyte for fuel cells in which the hydrophilic segment containing a sulfonic acid group is water-soluble.

  In the solid polymer electrolyte for a fuel cell of the present invention, it is preferable that the hydrophilic segment containing a sulfonic acid group includes a structural unit represented by the general formulas (1) and (2).

ここでＸ₁は、直接結合、−Ｏ−，−Ｓ−，

Ｙ₁は、直接結合、

のいずれかである。

Here, X ₁ is a direct bond, —O—, —S—,

Y ₁ is a direct bond,

One of them.

Z ₁ is any of a direct bond, —S—, and —O—, and Z ₁ may be the same as or different from each other. a ₁ and b ₁ are 0 or an integer of 1 or more, and a ₁ + b ₁ ≧ 1.

Further, 0 ≦ c ₁ , d ₁ , e ₁ , f ₁ ≦ 1, and c ₁ + d ₁ + e ₁ + f ₁ > 0.2.

のいずれかであり、同一でも異なっていても良い。Ｏ₁は、０〜６の整数であり、２つのＯ₁は同一でも異なっていてもよい。 R ₁ and R ₂ are a direct bond, —O—,

Which may be the same or different. O ₁ is an integer of 0 to 6, and two O ₁ may be the same or different.

  Some hydrogen atoms may be substituted with fluorine atoms.

Ｗ₁は、直接結合、

のいずれかである。

W ₁ is a direct bond,

One of them.

Z ₂ is either a direct bond, —S— or —O—, and the two Z ₂ may be the same or different. m ₁ and n ₁ are 0 or an integer of 1 or more, and m ₁ + n ₁ ≧ 1.

Further, 0 ≦ i ₁ and j ₁ ≦ 1.

のいずれかであり、２つのＲ₃は同一でも異なっていても良い。ｐ₁は、０〜６の整数であり、２つｐ₁は同一でも異なっていても良い。 R ₃ is a direct bond, —O—,

And two R _{3 s} may be the same or different. p ₁ is an integer of 0 to 6, and two p ₁ may be the same or different.

ここで、Ａｒ₈，Ａｒ₉は少なくともひとつの芳香環を有する４価の基である。 Ar ₁ is any one of the following general formulas (4) to (8). In (4) to (8), a substituent may be introduced.

Here, Ar ₈ and Ar ₉ are tetravalent groups having at least one aromatic ring.

のいずれかであり、同一でも異なっていても良い。ｑ₁は、０〜６の整数であり、２つのｑ₁は同一でも異なっていても良い。 R ₄ , R ₅ and R ₆ are a direct bond, —O—,

Which may be the same or different. q ₁ is an integer of 0 to 6, and the two q ₁ may be the same or different.

Also, 0 ≦ r ₁ , s ₁ ≦ 1, 0 ≦ t ₁ ≦ 2, and i ₁ + j ₁ + r ₁ + s ₁ + t ₁ > 0.2.

Z ₅ and Z ₆ represent —O—, —S—, —NR— (R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 6 to 10 carbon atoms). The two Z ₅ groups may be the same or different. The alkyl group, the alkoxy group and the aryl group may be substituted.

  Some hydrogen atoms may be substituted with fluorine atoms.

  Moreover, in the solid polymer electrolyte for a fuel cell of the present invention, it is preferable that the hydrophobic segment includes a structural unit represented by the general formula (3) or (4).

ここでＸ₂は、直接結合、−Ｏ−，−Ｓ−，

Ｙ₂は、直接結合、

のいずれかである。

Here, X ₂ is a direct bond, —O—, —S—,

Y ₂ is a direct bond,

One of them.

Z ₃ is any one of a direct bond, —S—, and —O—, and c ₂ + d ₂ + e ₂ + f ₂ <0.2. Two Z ₃ may be the same or different.

a ₂ and b ₂ are 0 or an integer of 1 or more, and a ₂ + b ₂ ≧ 1.

Further, 0 ≦ c ₂ , d ₂ , e ₂ , f ₂ , ≦ 1, and c ₂ + d ₂ + e ₂ + f ₂ <0.2.

のいずれかであり、同一でも異なっていても良い。Ｏ₂は、０〜６の整数であり、２つのＯ₂は同一でも異なっていても良い。 R ₇ and R ₈ are a direct bond, —O—,

Which may be the same or different. O ₂ is an integer of 0 to 6, and the two O ₂ may be the same or different.

  Some hydrogen atoms may be substituted with fluorine atoms.

Ｗ₂は、直接結合、

のいずれかである。

W ₂ is a direct bond,

One of them.

Z ₄ is either a direct bond, —S— or —O—, and the two Z ₄ may be the same or different. m ₂ and n ₂ are 0 or an integer of 1 or more, and m ₂ + n ₂ ≧ 1.

Further, 0 ≦ i ₂ , j ₂ ≦ 1, and two k ₂ are independent and are integers of 0 or more.

のいずれかであり、２つのＲ₉は同一でも異なっていても良い。Ａｒ₂は、下記一般式（９）〜（１３）のいずれかである。なお、（９）〜（１３）は置換基が導入されていても良い。

ここで、Ａｒ₈，Ａｒ₉は少なくともひとつの芳香環を有する４価の基である。 R ₉ is a direct bond, —O—,

And two R _{9 s} may be the same or different. Ar ₂ is any one of the following general formulas (9) to (13). In (9) to (13), a substituent may be introduced.

Here, Ar ₈ and Ar ₉ are tetravalent groups having at least one aromatic ring.

のいずれかであり、同一でも異なっていても良い。ｑ₂は、０〜６の整数であり、２つのｑ₂は同一でも異なっていても良い。 R ₁₀ , R ₁₁ and R ₁₂ are a direct bond, —O—,

Which may be the same or different. q ₂ is an integer from 0 to 6, two q ₂ may be the same or different.

Further, 0 ≦ r ₂ , s ₂ ≦ 1, 0 ≦ t ₂ ≦ 2, and i ₂ + j ₂ + r ₂ + s ₂ + t ₂ <0.2.

Z ₅ and Z ₆ represent —O—, —S—, —NR— (R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 6 to 10 carbon atoms). The two Z ₅ groups may be the same or different. The alkyl group, the alkoxy group and the aryl group may be substituted. Some hydrogen atoms may be substituted with fluorine atoms.

In the solid polymer electrolyte for a fuel cell of the present invention, the hydrophobic segment includes a structural unit represented by the general formula (3) or (4), and a ₂ , b ₂ , m ₂ , or n ₂ It is preferable that at least one is 20 or more.

  The present invention provides a polymer electrolyte membrane for fuel cells formed by forming the polymer electrolyte described above.

  The present invention also provides an analysis method in which analysis is performed by small-angle X-ray scattering after the ion exchange group of a solid polymer electrolyte membrane for a fuel cell is replaced with a metal.

  Furthermore, the present invention includes the above-described polymer electrolyte membrane for fuel cells, and a cathode electrode and an anode electrode sandwiching the polymer electrolyte membrane, and the cathode electrode and the anode electrode are supported on at least carbon and the carbon. A membrane electrode assembly including an electrode catalyst and a polymer electrolyte is provided.

  The present invention also provides a polymer electrolyte fuel cell using the membrane electrode assembly.

  According to the present invention, an electrolyte membrane with high ionic conductivity and small dimensional change in the area in water can be produced, and the output and life of the fuel cell are improved.

  Hereinafter, embodiments of the present invention will be described in detail.

In the present invention, a hydrophilic segment containing an ion exchange group and a hydrophobic segment substantially not containing an ion exchange group or having a smaller ion exchange amount than the hydrophilic segment, the number average molecular weight Mn of the hydrophobic segment is 1 Any block copolymer having a weight average molecular weight Mw of 1.5 × 10 ^{4 to} 5.0 × 10 ⁴ or 1.5 × 10 ⁴ to 1.5 × 10 ⁵ is within the scope of the invention.

  The block copolymer here is a copolymer containing at least one hydrophilic segment and at least one hydrophobic segment that are covalently bonded to each other directly or indirectly. The hydrophobic segment means a copolymer having an ion exchange equivalent weight of 1000 g / equivalent or more, and the hydrophilic segment has an ion exchange equivalent weight of 1000 g / equivalent or less and more ion exchange than the hydrophobic segment. A copolymer having a small equivalent weight.

In addition, ion exchange group equivalent represents the molecular weight of the polymer per introduced ion exchange group unit equivalent, and shows that the introduction degree of an ion exchange group is so large that a value is small. Ion exchange group equivalent weight is ¹ H-NMR spectroscopy, elemental analysis, acid-base titration described in JP-B-1-52866, non-hydroxybase titration (normal solution is benzene / methanol solution of potassium methoxide) It is possible to measure by such as.

  In a preferred embodiment of the block copolymer, the hydrophobic segment and the hydrophilic segment are reacted separately to form hydrophobic or hydrophilic segments, respectively, and these segments are then polymerized. Is not limited. For example, after synthesizing a hydrophobic-hydrophobic block copolymer (hydrophobic segment), only one of the hydrophobic sites may be hydrophilized with sulfuric acid or chlorosulfuric acid. Alternatively, the hydrophobic segment or the hydrophilic segment may be used. A block copolymer may be prepared by adding a hydrophilic monomer or a hydrophobic segment after synthesizing.

Hydrophilic segment, hydrophobic segment, block polymer number average molecular weight Mn, weight average molecular weight Mw are vapor pressure osmotic pressure method, membrane osmotic pressure method, light scattering method, low angle light scattering method, sedimentation equilibrium method, viscosity measurement, gel permeation It can be measured by chromatography (GPC) or the like. As a method for measuring the average molecular weight of the hydrophilic segment and the hydrophobic segment, in addition to the method of measuring the average molecular weight when each of the hydrophobic or hydrophilic segments is formed, the block polymer is subjected to 80 ° C., 3% for a predetermined time. There is a method of immersing in a solution containing H ₂ O ₂ , 3 ppm Fe ²⁺ and partially breaking the molecular chain of the block polymer to dissolve the hydrophilic segment in the solution and then measuring the molecular weight of each. In the case of this method, the number average molecular weight Mn of the hydrophobic segment is 0.5 × 10 ^{4 to} 5.0 × 10 ⁴ and the weight average molecular weight Mw is considered to be 1.5 × 10 ⁴ to 1.5 × 10 ^5. It is done.

  In addition, in the present invention, if the block copolymer is substantially the same or higher than the glass transition temperature of the hydrophilic segment, the glass transition temperature of the hydrophobic segment is within the scope of the invention. The glass transition temperature can be measured by thermomechanical analysis (TMA), differential scanning calorimetry (DSC), viscoelasticity measurement (DMA), or the like.

In the present invention, the water resistance of the electrolyte membrane is improved, and the reason why the dimensional change in the area direction in water is reduced is largely due to the influence of intermolecular interaction in the hydrophobic segment, and the hydrophobic segment having a high glass transition temperature. Therefore, it is considered that the dimensional change in the area direction in water is small. The dimensional change in the area direction in water is influenced by the molecular weight of the entire block polymer in addition to the average molecular weight of the hydrophobic segment, but the maximum value of the molecular weight distribution in the random polymer is the number average molecular weight Mn of the hydrophobic segment. About 1.0 × 10 ⁴ , weight average molecular weight Mw is about 2.5 × 10 ⁴ , number average molecular weight Mn is 1.0 × 10 ^{4 to} 5.0 × 10 ⁵ , or weight average molecular weight Mw is 1 It is considered that the dimensional change in the area direction in water can be reduced because the intermolecular interaction becomes large when it is from 0.5 × 10 ^{4 to} 1.5 × 10 ⁵ .

  In addition, the ionic conductivity is considered to be improved by continuous ion conduction sites due to the hydrophilic segment. In addition, since the electrolyte membrane of this invention has the small dimensional change to the area direction in water, it is thought that methanol permeation at the time of using for DMFC is small.

  The hydrophobic segment used in the present invention includes a polyimide copolymer, a polybenzimidazole copolymer, a polyquinoline copolymer, a polysulfone copolymer, a polyethersulfone copolymer, and a polyetheretherketone system. Aromatic hydrocarbon polymers such as copolymers, polyetherketone copolymers, polyphenylenesulfide copolymers, polyetherimide copolymers, etc., may be substituted. Further, sulfonic acid, alkylsulfonic acid, alkyloxysulfonic acid, oxysulfonic acid, etc. may be attached.

  The hydrophilic segment used in the present invention includes a polyether ether ketone having a sulfonic acid group, a polyether sulfone copolymer having a sulfonic acid group, a polysulfide copolymer having a sulfonic acid group, and a sulfonic acid group. Sulfonated engineering plastics electrolytes such as polyphenylene copolymers, polyimide copolymers with sulfonic acid groups, polybenzimidazole copolymers with sulfonic acid groups, polyquinoline copolymers with sulfonic acid groups, alkyl Polyether ether ketone copolymer having sulfonic acid, polyether sulfone copolymer having alkyl sulfonic acid, polyether ether sulfone copolymer having alkyl sulfonic acid, polysulfone copolymer having alkyl sulfonic acid , Archi Polysulfide copolymer with sulfonic acid, polyphenylene copolymer with alkyl sulfonic acid, polyether ether sulfone copolymer with alkyl sulfonic acid, polyphenylene copolymer with alkyl sulfonic acid, alkyl sulfonic acid Engineered plastic electrolytes having alkyl sulfonic acid groups, such as polyimide copolymers having polyalkylene copolymers, polybenzimidazole copolymers having alkyl sulfonic acids, polyquinoline copolymers having alkyl sulfonic acids, poly having alkyl oxy sulfonic acids Ether ether ketone copolymer, polyether sulfone copolymer having alkyloxy sulfonic acid, polyether ether sulfone copolymer having alkyloxy sulfonic acid, alkyloxy sulfone Engineer plastics having alkyloxy sulfonic acid such as sulfoalkylated polysulfone copolymer having alkyloxysulfonic acid, sulfoalkylated polysulfide copolymer having alkyloxysulfonic acid, sulfoalkylated polyphenylene copolymer having alkyloxysulfonic acid, etc. Electrolyte, polyether ether ketone copolymer having oxysulfonic acid, polyether sulfone copolymer having oxysulfonic acid, polyether ether sulfone copolymer having oxysulfonic acid, sulfo having oxysulfonic acid It has oxysulfonic acid such as alkylated polysulfone copolymer, sulfoalkylated polysulfide copolymer having oxysulfonic acid, sulfoalkylated polyphenylene copolymer having oxysulfonic acid, etc. And an electrolyte such as an engineer plastic electrolyte, which may have a substituent.

The block copolymer constituting the polymer electrolyte of the present invention has a number average molecular weight Mn and a weight average molecular weight Mw of 1.0 × 10 ^{4 to} 2.5 × 10 ^{5 for} Mn and 1.5 × 10 ⁴ to Mw. 1.5 × 10 ⁵ . Preferably Mn is 2.0 × 10 ^{4 to} 2.2 × 10 ⁵ , Mw is 2.5 × 10 ^{4 to} 1.0 × 10 ^{6, and} more preferably Mn is 2.5 × 10 ^{4 to} 2.0 × 10 6. ⁵ and Mw are 5.0 × 10 ^{5 to} 9.0 × 10 ⁵ . When Mn is less than 1.0 × 10 ^4, the strength of the electrolyte membrane is lowered, and when Mn exceeds 2.5 × 10 ⁵ , output performance may be lowered, which is not preferable.

  Moreover, the ion exchange equivalent weight of the block copolymer of this invention is 200-2000 g / equivalent. Preferably it is 350-1500 g / equivalent.

  The block copolymer of the present invention is used in a polymer membrane state in a fuel cell. Examples of the film production method include a solution casting method, a melt press method, a melt extrusion method, and the like, which form a film from a solution state. Among these, the solution casting method is preferable. For example, after casting a polymer solution on a substrate, the solvent is removed to form a film. The solvent used in the film formation is not particularly limited as long as it can be removed after dissolving the block copolymer of the present invention. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2- Aprotic polar solvents such as pyrrolidone and dimethyl sulfoxide, or alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether, iso-propyl alcohol, t- Examples include alcohols such as butyl alcohol and tetrahydrofuran.

When producing a polymer electrolyte membrane used in the present invention, a plasticizer, an antioxidant, a hydrogen peroxide decomposing agent, a metal scavenger, a surfactant, a stabilizer, and a mold release agent used for ordinary polymers Additives such as can be used within the range not contrary to the object of the present invention. Antioxidants include amine-based antioxidants such as phenol-α-naphthylamine, phenol-β-naphthylamine, diphenylamine, p-hydroxydiphenylamine, phenothiazine, 2,6-di (t-butyl) -p-cresol, 2, 6-di (t-butyl) -p-phenol, 2,4-dimethyl-6- (t-butyl) -phenol, p-hydroxyphenylcyclohexane, di-p-hydroxyphenylcyclohexane, styrenated phenol, 1,1 Phenolic antioxidants such as' -methylenebis (4-hydroxy-3,5-t-butylphenol), dodecyl mercaptan, dilauryl thiodipropionate, distearyl thiodipropionate, dilauryl sulfide, mercaptobenzimidazole Sulfur-based antioxidants such as Phosphorous antioxidants such as linoleyl phenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, and trilauri trithiophosphite are available. The hydrogen peroxide decomposing agent is not particularly limited as long as it has a catalytic action for decomposing peroxide. For example, in addition to the antioxidant, there may be mentioned metals, metal oxides, metal phosphates, metal fluorides, macrocyclic metal complexes, and the like. One kind selected from these may be used alone, or two or more kinds may be used in combination. Among these, as the metal is Ru, Ag, etc., as the metal _{oxide, RuO, WO 3, CeO 2} , Fe 3 O 4 , etc., as metal phosphates _{CePO 4, CrPO 4, AlPO 4} , FePO 4 , etc., as the metal fluoride CeF _3, FeF _3, etc., as the macrocyclic metal complex Fe- porphyrins, Co- porphyrins, heme, catalase and the like. In particular, it is preferable to use RuO ₂ or CePO ₄ because of its high peroxide decomposition performance.

In addition, the metal scavenger is particularly limited as long as it can react with metal ions such as Fe ²⁺ and Cu ²⁺ ions to form a complex, inactivate the metal ions, and suppress the deterioration promoting action of the metal ions. There is no. Examples of such metal scavengers include tenoyl trifluoroacetone, sodium diethylthiocarbamate (DDTC), 1,5-diphenyl-3-thiocarbazone, and 1,4,7,10,13-pentaoxycyclopentadecane, Crown ethers such as 4,7,10,113,16-hexaoxycyclopentadecane, 4,7,13,16-tetraoxa-1,10-diazacyclooctadecane and 4,7,13,16,21,24- A cryptand such as hexaoxy-1,10-diazacyclohexacosane, or a porphyrin-based material such as tetraphenylporphyrin may be used. Moreover, the mixing amount of these materials is not limited to what was described in the Example. Among these, a combined system of a phenolic antioxidant and a phosphorus antioxidant is particularly preferable because it is effective in a small amount and has little adverse effect on various characteristics of the fuel cell. These antioxidants, hydrogen peroxide decomposing agents, and metal scavengers may be added to the electrolyte membrane or electrode, or may be disposed between the membrane and the electrode. In particular, it is preferable to dispose the cathode electrode or between the cathode electrode and the electrolyte membrane in a small amount because it is effective because the degree of adverse effects on the various characteristics of the fuel cell is small.

Although there is no restriction | limiting in particular in the thickness of the polymer electrolyte membrane of this invention, 10-300 micrometers is preferable. 15-200 micrometers is especially 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 in order to reduce membrane resistance, that is, 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.

  In the present invention, an analysis method in which the ion exchange group of the polymer electrolyte membrane for a fuel cell is replaced with a metal and then analyzed by small angle X-ray scattering is also within the scope of the invention. Examples of the metal that replaces the ion exchange group include alkali metals, alkaline earth metals, and transition metals, and are not limited. Monovalent or divalent metals are preferable, and Na, K, Rb, Cs, Mg, Ca, Pb, and the like are more preferable. When the valence of the metal is high, the substitution of ion exchange groups is different, and the phase separation structure in a power generation environment cannot be simulated.

  The polymer electrolyte membrane of the present invention and the carbon powder carrying the catalyst, or the carbon powder carrying the catalyst are adhered to each other, and a conventional fluorine-based polymer electrolyte or hydrocarbon-based electrolyte is used as a polymer electrolyte that conducts protons. Can be used. Examples of such hydrocarbon electrolytes include sulfonated engineering ether plastic ketone, sulfonated polyether sulfone, sulfonated acrylonitrile / butadiene / styrene polymer, sulfonated polysulfide, sulfonated polyphenylene, and the like, Sulfoalkylation engineers such as alkylated polyetheretherketone, sulfoalkylated polyethersulfone, sulfoalkylated polyetherethersulfone, sulfoalkylated polysulfone, sulfoalkylated polysulfide, sulfoalkylated polyphenylene, sulfoalkylated polyetherethersulfone Plastic electrolytes, hydrocarbon electrolytes such as sulfoalkyletherified polyphenylene, and proton conductivity Hydrocarbon polymer, such as the introduction of Azukamoto and oxidation resistance imparting group.

Any metal that promotes the fuel oxidation reaction and oxygen reduction reaction as the anode catalyst or cathode catalyst may be used. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, Chromium, tungsten, manganese, vanadium, titanium, or an alloy thereof can be used. Among such catalysts, platinum (Pt) is often used as a catalyst. The particle size of the metal serving as the catalyst is usually 1 to 30 nm. 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 20 mg / cm ² in a state where the electrode is formed.

  The electrode used for the membrane electrode assembly is composed of a conductive material carrying catalyst metal fine particles, and may contain a water repellent or a binder as necessary. 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 conductive material for supporting the catalyst metal may be any conductive material as long as it is an electron conductive substance, and examples thereof include various metals and carbon materials. As the carbon material, for example, carbon black such as furnace black, channel black, and acetylene black, fibrous carbon such as carbon nanotubes, activated carbon, graphite, and the like can be used, and these can be used alone or in combination. it can.

  For example, fluorinated carbon is used as the water repellent. As the binder, it is preferable to use a hydrocarbon electrolyte solution of the same system as the electrolyte membrane from the viewpoint of adhesiveness, but other various resins may be used. Further, a water-repellent fluorine-containing resin such as polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer may be added.

  The method for joining the polymer electrolyte membrane and the electrode when used as a fuel cell is not particularly limited, and a known method can be applied. As a method for manufacturing a membrane electrode assembly, for example, a conductive material, for example, Pt catalyst powder supported on carbon and a polytetrafluoroethylene suspension are mixed, applied to carbon paper and heat-treated to form a catalyst layer. Next, there is a method in which the same polymer electrolyte solution or fluorine-based electrolyte as the polymer electrolyte membrane is applied as a binder to the catalyst layer and integrated with the polymer electrolyte membrane by hot pressing. In addition, a method in which the same polymer electrolyte solution as the polymer electrolyte is coated in advance on the Pt catalyst powder, a method in which the catalyst paste is applied to the polymer electrolyte membrane by a printing method, a spray method, or an ink jet method, a polymer electrolyte membrane There are a method of electroless plating the electrode, a method of adsorbing a platinum group metal complex ion to the polymer electrolyte membrane and then reducing it. Among these, the method of applying the catalyst paste to the polymer electrolyte membrane by the ink jet method is excellent with little loss of the catalyst.

  In the present invention, various types of fuel cells can be provided by using the block co-aggregate as an electrolyte membrane. For example, the gas diffusion sheet is in close contact with the oxygen electrode side and the hydrogen electrode side of the polymer electrolyte membrane / electrode assembly in which one side of the main surface of the electrolyte membrane is sandwiched between an oxygen electrode and the other side is sandwiched between hydrogen electrodes. A solid polymer fuel cell single cell comprising a conductive separator provided on the outer surface of the gas diffusion sheet and having a gas supply passage to the oxygen electrode and the hydrogen electrode can be formed. Moreover, the portable power supply which has a hydrogen cylinder which stores said fuel cell main body and the hydrogen supplied to this fuel cell main body in a case can be provided. Further, a reformer for reforming into an anode gas containing hydrogen, a fuel cell for generating electricity from the anode gas and a cathode gas containing oxygen, and a high-temperature anode gas and reformer that are generated from the reformer are supplied to the reformer. A fuel cell power generation device including a heat exchanger that exchanges heat with a low-temperature fuel gas can be provided. In addition, the gas diffusion sheet is in close contact with the oxygen electrode side and the methanol electrode side of the polymer electrolyte membrane / electrode assembly in which one side of the main surface of the electrolyte membrane is sandwiched between the oxygen electrode and the other side is sandwiched between the methanol electrodes. A direct methanol fuel cell single cell comprising a conductive separator provided on the outer surface of the gas diffusion sheet and having gas and liquid supply passages to the oxygen electrode and the methanol electrode can be formed.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited only to the examples disclosed herein.

(1) Production of polymer a (hydrophobic segment) After the inside of a 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, and reflux condenser connected with a calcium chloride tube was purged with nitrogen, 4,4- Dichlorodiphenyl sulfone, 4,4-biphenol, and potassium carbonate were prepared in a molar ratio of 1.00: 1.05: 1.15, and charged. A polymer having an end group of OH was synthesized by performing a reaction at 200 ° C. for 24 hours using toluene as an azeotropic material and N-methyl-2-pyrrolidone (NMP) as a solvent. Further, decafluorobiphenyl having a mol ratio of 0.1 was added to make all ends F. As for the molecular weight of the obtained hydrophobic segment (polystyrene conversion value determined from GPC), the number average molecular weight Mn was 2.0 × 10 ⁴ and the weight average molecular weight Mw was 4.4 × 10 ⁴ .

The measurement conditions of GPC (gel permeation chromatograph) are as follows.
GPC device: HLC-8220GPC manufactured by Tosoh Corporation
Column: TSKgel SuperAWM-H × 2 manufactured by Tosoh Corporation Eluent: NMP (10 mmol / L lithium bromide added)
After the polymer a was formed by the method of Example 1 (4), the glass transition temperature was measured by dynamic viscoelasticity measurement. As a result, the glass transition temperature obtained from tan δ was about 237 degrees.

(2) Preparation of polymer b (hydrophilic segment) After the inside of a 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser connected with a calcium chloride tube was purged with nitrogen, sulfonation 4, 4-Dichlorodiphenylsulfone, 4,4-biphenol, and potassium carbonate were each prepared in a molar ratio of 1.60: 1.65: 1.15 and added. Toluene and N-methyl-2pyrrolidone (NMP) were used as a solvent and reacted at 200 ° C. for 12 hours to synthesize a polymer having an OH terminal group. The number average molecular weight Mn of the hydrophilic segment was 3.5 × 10 ⁴ , and the weight average molecular weight Mw was 8.5 × 10 ⁴ .

(3) Preparation of block copolymer A Polymers a and b synthesized in (1) and (2) were mixed and reacted at 140 ° C. for 2 hr. The blending ratio of polymer a and polymer b was adjusted so that the ion exchange group equivalent weight was 625 g / equivalent. The obtained solution was poured into water and reprecipitated to obtain a block copolymer A. The number average molecular weight Mn of the obtained block copolymer A was 1.2 × 10 ⁵ , and the weight average molecular weight Mw was 4.7 × 10 ⁵ . The ion exchange group equivalent weight measured by acid-base titration was 757.

(4) Preparation of polymer electrolyte membrane 1 and its characteristics The block copolymer A obtained in (3) above is dissolved in NMP so as to have a concentration of 15% by weight. This solution was cast on glass, heated and dried, then immersed in sulfuric acid and water, and dried to obtain a polymer electrolyte membrane 1 having a thickness of 40 μm. After substituting the ion exchange group of the polymer electrolyte membrane 1 with Cs and performing small-angle X-ray scattering analysis (SAXS) in water, the average period was 56 nm. Could not be confirmed. As described above, the phase separation structure in the humidified / water environment of the electrolyte membrane can be evaluated only when the SAXS analysis is performed after replacing the metal in the electrolyte membrane. Moreover, the dimensional change rate in the area direction after being immersed in water at 80 ° C. for 8 hours is 4%, and the ionic conductivity at 10 KHz measured by the 4-terminal AC impedance method at 80 ° C. and 60 RH% is 3.6%. × 10 ^-2 S / cm. FIG. 3 shows the result of dynamic viscoelasticity measurement (DMA) of the polymer electrolyte membrane 1. In the measurement of dynamic viscoelasticity, in order to remove the influence of the change in elastic modulus due to sulfonic acid group elimination occurring at a high temperature of about 270 ° C. or higher, the sulfonic acid group is substituted with Na and the sulfone desorption of 340 ° C. or higher is performed. An electrolyte membrane having a separation temperature was evaluated.

  The measurement conditions for SAXS are as follows.

Equipment: ATX-G manufactured by Rigaku Corporation
X-ray source, X-ray output: Cu, 40 kV-400 mA
Spectrometer, measurement method: multilayer mirror, transmission method Scanning axis, scanning method: 2θ, integrated scanning Scanning range (step): 0.2 ≦ 2θ ≦ 10 (0.05 deg / step), 0.05 ≦ 2θ ≦ 2 0.0 (0.01 deg / step)
Integration time: 60 seconds The DMA measurement conditions are as follows.

Device: ITA Measurement Control Co., Ltd. DVA-220
Measurement mode: Pulling Electrolyte membrane width, terminal distance: 5mm, 20mm
Measurement frequency: 10Hz
Measurement temperature, heating rate: 50-350 ° C., 5 ° C./min (5) Production of membrane electrode assembly (MEA) 1 Catalyst powder in which platinum fine particles are dispersed and supported on a carbon support and 5 wt% polyperfluoro A slurry of 1-propanol, 2-propanol, and water mixed with sulfonic acid was prepared and spray-coated on the electrolyte membrane so that the catalyst weight was 0.4 g · cm ^2. About 20 μm, width 30 mm, long A cathode and anode with a thickness of 30 mm were produced. Then, membrane electrode assembly (MEA) 1 having anodes and cathodes formed on both sides of the polymer electrolyte membrane 1 was produced by hot pressing at 120 ° C. and 13 MPa.

(6) Power generation performance of fuel cell (PEFC) The battery performance was measured by incorporating the diffusion layer composed of the MEA 1 and the carbon cloth using the small unit cell using hydrogen as shown in FIG. In FIG. 2, 1 is a polymer electrolyte membrane, 2 is an anode electrode, 3 is a cathode electrode, 4 is an anode diffusion layer, 5 is a cathode diffusion layer, and 6 serves as a chamber separation and a gas supply passage to the electrode. A fuel flow path of a conductive separator (bipolar plate), 7 is an air passage of the separator, 8 is hydrogen + water, 9 is hydrogen, 10 is air + water, and 11 is air. The small single battery cell was installed in a thermostat, and the temperature of the thermostat was controlled so that the temperature by a thermocouple (not shown) inserted in the separator was 70 ° C. The humidification of the anode and cathode was performed using an external humidifier, and the temperature of the humidifier was controlled between 70 and 73 ° C. so that the dew point near the humidifier outlet was 70 ° C. Electricity was generated at a load current density of 250 mA / cm ² , a hydrogen utilization rate of 70%, and an air utilization rate of 40%. PEFC using MEA1 showed an output of 0.74 V or more, and was able to generate electricity stably for 1000 hours or more.

(1) Production of polymer c (hydrophobic segment) In the same manner as in (1) of Example 1, the ratio of 4,4-dichlorodiphenylsulfone, 4,4-biphenol, potassium carbonate, decafluorobiphenyl was changed. Thus, a hydrophobic segment having a number average molecular weight Mn of 1.3 × 10 ⁴ and a weight average molecular weight Mw of 2.6 × 10 ⁴ was produced.

(2) Production of polymer b (hydrophilic segment) In the same manner as in (2) of Example 1, the ratio of sulfonated 4,4-dichlorodiphenylsulfone, 4,4-biphenol, potassium carbonate was changed, A hydrophilic segment having a number average molecular weight Mn of 2.5 × 10 ⁴ and a weight average molecular weight Mw of 5.5 × 10 ⁴ was prepared.

(3) Production of block copolymer B Polymers c and d synthesized in (1) and (2) were mixed in the same manner as in (2) of Example 1, and reacted at 140 ° C. for 2 hr. The blend ratio of polymer c and polymer d was adjusted so that the equivalent weight of ion exchange groups was 625 g / equivalent. The obtained block copolymer B had a number average molecular weight Mn of 9.5 × 10 ⁴ and a weight average molecular weight Mw of 2.5 × 10 ⁵ . The ion exchange group equivalent weight measured by acid-base titration was 689.

(4) Production of polymer electrolyte membrane 1-2 and its characteristics Polymer electrolyte membrane 1-2 was obtained from block copolymer B obtained in (3) by the same method as (4) of Example 1. . After substituting the ion exchange group of the polymer electrolyte membrane 1-2 with Cs and performing small-angle X-ray scattering analysis (SAXS) in water, the average period is 38 nm, and the peak in SAXS of the electrolyte membrane without metal substitution Could not be confirmed. Moreover, the dimensional change rate in the area direction after being immersed in water at 80 ° C. for 8 hours is 13%, and the ionic conductivity at 10 KHz measured by the 4-terminal AC impedance method at 80 ° C. and 60 RH% is 3.0. × 10 ^-2 S / cm. FIG. 4 shows the results of dynamic viscoelasticity measurement of the polymer electrolyte membrane 1-2 measured by the method shown in Example 1 (4).

(5) Production of Membrane / Electrode Assembly (MEA) 2 MEA 2 was obtained from the polymer electrolyte membrane 1-2 obtained in (4) by the same method as in (5) of Example 1.

(6) Power generation performance of fuel cell (PEFC) The battery performance of PEFC using MEA2 obtained in (5) was measured in the same manner as in (6) of Example 1. PEFC using MEA2 showed an output of 0.73 V or more, and was able to generate electricity stably for 1000 hours or more.

(1) Preparation of polymer e (hydrophobic segment) In the same manner as in (1) of Example 1, the ratio of 4,4-dichlorodiphenylsulfone, 4,4-biphenol, potassium carbonate, decafluorobiphenyl was changed. Thus, a hydrophobic segment having a number average molecular weight Mn of 0.5 × 10 ⁴ and a weight average molecular weight Mw of 0.8 × 10 ⁴ was produced.

(2) Production of polymer f (hydrophilic segment) In the same manner as in (2) of Example 1, the ratio of sulfonated 4,4-dichlorodiphenylsulfone, 4,4-biphenol, potassium carbonate was changed, A hydrophilic segment having a number average molecular weight Mn of 1.3 × 10 ⁴ and a weight average molecular weight Mw of 2.3 × 10 ⁴ was produced.

(3) Production of Block Copolymer C Polymers c and d synthesized in (1) and (2) were mixed in the same manner as in (2) of Example 1, and reacted at 140 ° C. for 2 hr. The blending ratio of polymer e and polymer f was adjusted so that the ion exchange group equivalent weight was 625 g / equivalent. The resulting block copolymer C had a number average molecular weight Mn of 8.2 × 10 ⁴ and a weight average molecular weight Mw of 1.8 × 10 ⁵ . The ion exchange group equivalent weight measured by acid-base titration was 672.

(4) Production of polymer electrolyte membrane 1-3 and its characteristics Polymer electrolyte membrane 1-3 was obtained from block copolymer C obtained in (3) by the same method as (4) of Example 1. . After substituting the ion exchange group of this polymer electrolyte membrane 1-3 with Cs and performing small-angle X-ray scattering analysis (SAXS) in water, the average period is 23 nm, and the peak in SAXS of the electrolyte membrane without metal substitution Could not be confirmed. Moreover, the dimensional change rate in the area direction after being immersed in water at 80 ° C. for 8 hours is 18%, and the ionic conductivity at 10 KHz measured by the four-terminal AC impedance method at 80 ° C. and 60 RH% is 2.1. × 10 ^-2 S / cm. FIG. 5 shows the results of dynamic viscoelasticity measurement of the polymer electrolyte membrane 1-3 measured by the method shown in Example 1 (4).

(5) Production of Membrane / Electrode Assembly (MEA) 3 MEA 3 was obtained from the polymer electrolyte membrane 1-3 obtained in (4) by the same method as (5) in Example 1.

(6) Power generation performance of fuel cell (PEFC) The battery performance of PEFC using MEA3 obtained in (5) was measured in the same manner as in (6) of Example 1. PEFC using MEA2 showed an output of 0.73 V or more, but the performance decreased after about 800 hours of power generation. When the MEA 3 after power generation was examined, in the MEA 3, breakage of the electrolyte membrane was confirmed at the boundary between the portion where the electrode was applied and the portion where the electrode was not applied. It is considered that the membrane breakage was caused by applying a larger stress than the electrolyte membranes of Examples 1 and 2 due to the large swelling and shrinkage of the electrolyte membrane.

[Comparative Example 1]
(1) Polymerization of Polymer f (Random Copolymer A) The inside of a 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, and reflux condenser connected with a calcium chloride tube was purged with nitrogen and then sulfonated. 4,4-Dichlorodiphenylsulfone, 4,4-biphenol with 4,4-dichlorodiphenylsulfone, potassium carbonate, toluene as an azeotrope, and NMP as a solvent were synthesized at 200 ° C. for 24 hours. The obtained solution was poured into water and reprecipitated to obtain a random copolymer A. As for the molecular weight of the obtained random copolymer A, the number average molecular weight Mn was 1.7 × 10 ⁵ , and the weight average molecular weight Mw was 5.5 × 10 ⁵ .

(2) Production of Polymer Electrolyte Membrane 1-4 and Its Characteristics Polymer electrolyte membrane 1-4 was obtained from the random copolymer obtained in (1) by the same method as (4) of Example 1. When the ion exchange group of this polymer electrolyte membrane 1-4 was replaced with Cs and then small angle X-ray scattering analysis (SAXS) was performed in water, no peak could be confirmed. In addition, no peak was observed in SAXS of the electrolyte membrane not substituted with metal. Moreover, the dimensional change rate in the area direction after being immersed in water at 80 ° C. for 8 hours is 14%, and the ionic conductivity at 10 KHz measured by the 4-terminal AC impedance method at 80 ° C. and 60 RH% is 1.3. × 10 ^-2 S / cm. FIG. 6 shows the results of dynamic viscoelasticity measurement of the polymer electrolyte membrane 1-4 measured by the method shown in Example 1 (4).

(3) Production of Membrane / Electrode Assembly (MEA) 3 MEA 4 was obtained from the polymer electrolyte membrane 1-4 obtained in (2) by the same method as (5) in Example 1.

(4) Power generation performance of fuel cell (PEFC) The battery performance of PEFC using MEA4 obtained in (3) was measured by the same method as in (6) of Example 1. The PEFC using MEA2 had an output of 0.72V or less.

[Comparative Example 2]
(1) Polymerization of Polymer g (Random Copolymer B) The ratio of 4,4-biphenol to sulfonated 4,4-dichlorodiphenyl sulfone and 4,4-dichlorodiphenyl sulfone is changed in the same manner as in Comparative Example 1. As a result, a random copolymer B was obtained. The ion exchange equivalent weight of the random copolymer was 470 g / equivalent.

(2) Production of polymer electrolyte membrane 1-5 and its characteristics Polymer electrolyte membrane 1-5 was obtained from random copolymer B obtained in (1) in the same manner as in (4) of Example 1. . The glass transition temperature was measured by dynamic viscoelasticity measurement after improving the sulfonic acid desorption temperature by replacing the ion exchange group of the polymer electrolyte membrane with Na. As a result, the glass transition temperature obtained from tan δ was about 160 degrees. This temperature was lower than the temperature of the hydrophobic segment of Example 1 (1).

  Table 1 shows the physical properties of the polymer electrolyte membranes 1 to 1-5 produced in Examples 1 to 3 and Comparative Example 1.

According to Table 1, the dimensional change after immersion in water at 80 ° C. for 8 hours between the polymer electrolyte membrane 1 and 1-2 in which a block polymer having a hydrophobic segment molecular weight of 1.0 × 10 ⁴ or more is produced is a random polymer. It was smaller than the dimensional change of the polymer electrolyte membrane 1-4 that had been immersed in water at 80 ° C. for 8 hours.

Table 2 shows the physical properties of the polymer electrolyte membranes before and after immersing the polymer electrolyte membranes 1 to 1-5 produced in Examples 1 to 3 in a solution containing 80 ° C., 3% H ₂ O ₂ and 3 ppm Fe ²⁺ for 1.5 hours. Show.

From Table 2, when the molecular weight of the hydrophobic segment is 1.0 × 10 ⁴ or more, the molecular weight distribution after immersion in the solution is the number average molecular weight Mn> 0.5 and the weight average molecular weight Mw> 1.5.

  The dynamic viscoelasticity measurement result of each electrolyte membrane is shown in FIGS. 3 to 6 show the measurement results of the electrolyte membranes of Examples 1 to 3 and Comparative Example 1, respectively, in order.

From FIG. 3 to FIG. 6, when the average molecular weight of the hydrophobic segment is larger than 1.0 × 10 ⁴ and Mw is larger than 1.5 × 10 ^4, a peak of loss elastic modulus exists at about 250 ° C. This is a phenomenon caused by an increase in the intermolecular interaction of the hydrophobic segment, and it is considered that a dimensional change can be suppressed by the intermolecular interaction. On the other hand, the glass transition temperature of Comparative Example 1 is about 160 ° C., which is equal to or lower than the glass transition temperature with the hydrophilic segment. Moreover, the polymer electrolyte membrane 1-3 obtained in Example 3 has a wide peak from 160 ° C to 250 ° C. The glass transition temperature of 160 ° C. is equivalent to the glass transition temperature of the hydrophilic segment. Since the glass transition temperature is lower than that of the polymer electrolyte membranes of Examples 1 and 2, it is considered that the intermolecular interaction is also weak, whereby the dimensional stability is inferior to that of the polymer electrolyte membranes of Examples 1 and 2. Conceivable.

Further, from Examples 1 to 3 and Comparative Example 1, the ionic conductivity increases as the molecular weight of the hydrophobic segment and the hydrophilic segment increases, and from this result, the number average molecular weight Mn of the hydrophobic segment is 1.0 × 10 ^4. An electrolyte membrane having high ion conductivity and excellent water resistance by using a block copolymer having a molecular weight Mw of 1.5 × 10 ⁴ to 1.5 × 10 ⁵ or ˜5.0 × 10 ⁴ Is obtained.

  INDUSTRIAL APPLICABILITY The present invention can provide an electrolyte having high ionic conductivity and excellent water resistance, and can be used for a direct methanol fuel cell, a solid polymer fuel cell, and the like.

Schematic of an electrolyte membrane and an electrode. Schematic of a fuel cell. The figure which shows the dynamic viscoelasticity measurement result of an electrolyte membrane. The figure which shows the dynamic viscoelasticity measurement result of an electrolyte membrane. The figure which shows the dynamic viscoelasticity measurement result of an electrolyte membrane. The figure which shows the dynamic viscoelasticity measurement result of an electrolyte membrane.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 Anode electrode 3 Cathode electrode 4 Anode diffusion layer 5 Cathode diffusion layer 6 Fuel flow path 7 Air conduit 8 Hydrogen + Water 9 Hydrogen 10 Air + Water 11 Air

Claims (15)

It consists of a hydrophilic segment containing an ion exchange group and a hydrophobic segment that substantially does not contain an ion exchange group or has a smaller ion exchange amount than the hydrophilic segment, and the number average molecular weight Mn of the hydrophobic segment is 1. A solid polymer electrolyte for a fuel cell having a block copolymer having 0 × 10 ^{4 to} 5.0 × 10 ⁴ or a weight average molecular weight Mw of 1.5 × 10 ⁴ to 1.5 × 10 ⁵ .   A solid polymer electrolyte for a fuel cell, characterized in that a glass transition temperature of a film formed only of a hydrophobic segment is the same as or higher than a glass transition temperature of a film formed of only a hydrophilic segment. The solid polymer electrolyte for a fuel cell according to any one of claims 1 and 2, wherein the hydrophilic segment includes a structural unit represented by the general formula (1).

Here, X ₁ is a direct bond, —O—, —S—,

Y ₁ is a direct bond,

One of them.
Z ₁ is any of a direct bond, —S—, and —O—, and Z ₁ may be the same as or different from each other. a ₁ and b ₁ are 0 or an integer of 1 or more, and a ₁ + b ₁ ≧ 1.
Further, 0 ≦ c ₁ , d ₁ , e ₁ , f ₁ ≦ 1, and c ₁ + d ₁ + e ₁ + f ₁ > 0.2.
R ₁ and R ₂ are a direct bond, —O—,

Which may be the same or different. O ₁ is an integer of 0 to 6, and two O ₁ may be the same or different.
Some hydrogen atoms may be substituted with fluorine atoms. The solid polymer electrolyte for a fuel cell according to claim 1, wherein the hydrophilic segment includes a structural unit represented by the general formula (2).

W ₁ is a direct bond,

One of them.
Z ₂ is either a direct bond, —S— or —O—, and the two Z ₂ may be the same or different. m ₁ and n ₁ are 0 or an integer of 1 or more, and m ₁ + n ₁ ≧ 1.
Further, 0 ≦ i ₁ and j ₁ ≦ 1.
R ₃ is a direct bond, —O—,

And two R _{3 s} may be the same or different. p ₁ is an integer of 0 to 6, and two p ₁ may be the same or different.
Ar ₁ is any one of the following general formulas (4) to (8). In (4) to (8), a substituent may be introduced.

Here, Ar ₈ and Ar ₉ are tetravalent groups having at least one aromatic ring.
R ₄ , R ₅ and R ₆ are a direct bond, —O—,

Which may be the same or different. q ₁ is an integer of 0 to 6, and the two q ₁ may be the same or different.
Also, 0 ≦ r ₁ , s ₁ ≦ 1, 0 ≦ t ₁ ≦ 2, and i ₁ + j ₁ + r ₁ + s ₁ + t ₁ > 0.2.
Z ₅ and Z ₆ represent —O—, —S—, —NR— (R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 6 to 10 carbon atoms). The two Z ₅ groups may be the same or different. The alkyl group, the alkoxy group and the aryl group may be substituted.
Some hydrogen atoms may be substituted with fluorine atoms. The solid polymer electrolyte for a fuel cell according to claim 1, wherein the hydrophobic segment includes a structural unit represented by the general formula (3).

Here, X ₂ is a direct bond, —O—, —S—,

Y ₂ is a direct bond,

One of them.
Z ₃ is any one of a direct bond, —S—, and —O—, and c ₂ + d ₂ + e ₂ + f ₂ <0.2. Two Z ₃ may be the same or different.
a ₂ and b ₂ are 0 or an integer of 1 or more, and a ₂ + b ₂ ≧ 1.
Further, 0 ≦ c ₂ , d ₂ , e ₂ , f ₂ , ≦ 1, and c ₂ + d ₂ + e ₂ + f ₂ <0.2.
R ₇ and R ₈ are a direct bond, —O—,

Which may be the same or different. O ₂ is an integer of 0 to 6, and the two O ₂ may be the same or different.
Some hydrogen atoms may be substituted with fluorine atoms. The solid polymer electrolyte for a fuel cell according to any one of claims 1 and 2, wherein the hydrophobic segment includes a structural unit represented by the general formula (4).

W ₂ is a direct bond,

One of them.
Z ₄ is either a direct bond, —S— or —O—, and the two Z ₄ may be the same or different. m ₂ and n ₂ are 0 or an integer of 1 or more, and m ₂ + n ₂ ≧ 1.
Further, 0 ≦ i ₂ , j ₂ ≦ 1, and two k ₂ are independent and are integers of 0 or more.
R ₉ is a direct bond, —O—,

And two R _{9 s} may be the same or different. Ar ₂ is any one of the following general formulas (9) to (13). In (9) to (13), a substituent may be introduced.

Here, Ar ₈ and Ar ₉ are tetravalent groups having at least one aromatic ring.
R ₁₀ , R ₁₁ and R ₁₂ are a direct bond, —O—,

Which may be the same or different. q ₂ is an integer from 0 to 6, two q ₂ may be the same or different.
Further, 0 ≦ r ₂ , s ₂ ≦ 1, 0 ≦ t ₂ ≦ 2, and i ₂ + j ₂ + r ₂ + s ₂ + t ₂ <0.2.
Z ₅ and Z ₆ represent —O—, —S—, —NR— (R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 6 to 10 carbon atoms). The two Z ₅ groups may be the same or different. The alkyl group, the alkoxy group and the aryl group may be substituted. Some hydrogen atoms may be substituted with fluorine atoms.   The hydrophilic segment includes a structural unit represented by the general formula (1) or (2), and includes a structural unit represented by the hydrophobic segment general formula (3) or (4). Solid polymer electrolyte for fuel cells.   The hydrophilic segment includes a structural unit represented by the general formula (1) or (2), and includes a structural unit represented by the hydrophobic segment general formula (3) or (4). Solid polymer electrolyte for fuel cells. The hydrophobic segment includes a structural unit represented by the general formula (3) or (4), and at least one of a ₂ , b ₂ , m ₂ , and n ₂ is 20 or more. The solid polymer electrolyte for a fuel cell as described. The hydrophobic segment includes a structural unit represented by the general formula (3) or (4), and at least one of a ₂ , b ₂ , m ₂ , and n ₂ is 20 or more, The solid polymer electrolyte for a fuel cell as described. A hydrophilic segment containing a structural unit represented by the general formula (1) or (2) containing an ion exchange group, and a general one containing substantially no ion exchange group or having a smaller ion exchange amount than the hydrophilic segment It consists of a hydrophobic segment containing the structural unit represented by formula (3) or (4), and the number average molecular weight Mn of the hydrophobic segment is 1.0 × 10 ^{4 to} 5.0 × 10 ⁴ or the weight average molecular weight Mw is 1. 0.5 × 10 ^{4 to} 1.5 × 10 ⁵ , and the glass transition temperature of the film formed with only the hydrophobic segment is the same or higher than the glass transition temperature of the film formed with only the hydrophilic segment. A solid polymer electrolyte for a fuel cell.   A polymer electrolyte membrane for a fuel cell, comprising the solid polymer electrolyte according to claim 1, 2, 8, 9, or 11.   An analysis method in which an ion exchange group of a solid polymer electrolyte membrane for a fuel cell is replaced with a metal and then analyzed by small angle X-ray scattering. A membrane electrode joint comprising a polymer electrolyte membrane, and a cathode electrode and an anode electrode sandwiching the polymer electrolyte membrane, wherein the cathode electrode and the anode electrode include at least carbon, an electrode catalyst supported on the carbon, and a polymer electrolyte. In the body,
A membrane / electrode assembly, wherein the polymer electrolyte membrane is the polymer electrolyte membrane according to claim 12.   A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 14.

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