JP5386775B2 - Manufacturing method of electrolyte membrane - Google Patents

Description

  The present invention relates to an electrolyte membrane and a method for producing the same, an electrolyte membrane-electrode assembly (hereinafter referred to simply as “MEA”) using the electrolyte membrane, and a fuel cell using the MEA. It is. More specifically, the present invention relates to an electrolyte membrane having excellent proton conductivity, particularly an electrolyte membrane for a fuel cell, and a method for producing the same, and an electrolyte membrane-electrode assembly using the electrolyte membrane, particularly an electrolyte membrane for a fuel cell. The present invention relates to an electrode assembly and a fuel cell using the MEA.

  In recent years, in response to social demands and trends against the background of energy and environmental problems, fuel cells that can operate at room temperature and obtain high output density have attracted attention as power sources for electric vehicles and stationary power sources. A fuel cell is a clean power generation system in which the product of an electrode reaction is water in principle and has almost no adverse effect on the global environment. In particular, the polymer electrolyte fuel cell is expected as a power source for electric vehicles because it operates at a relatively low temperature. In general, the polymer electrolyte fuel cell has a structure in which an electrolyte membrane-electrode assembly is sandwiched between a gas diffusion layer and a separator. The electrolyte membrane-electrode assembly is obtained by sandwiching a polymer electrolyte membrane between a pair of electrode catalyst layers.

In the polymer electrolyte fuel cell having the MEA as described above, the following electrochemical reaction proceeds. First, hydrogen contained in the fuel gas supplied to the anode side is oxidized by the catalyst component to become protons and electrons (2H ₂ → 4H ⁺ + 4e ⁻ ). Next, the generated protons pass through the solid polymer electrolyte contained in the electrode catalyst layer and the polymer electrolyte membrane in contact with the electrode catalyst layer, and reach the cathode side electrode catalyst layer. In addition, the electrons generated in the anode-side electrode catalyst layer include a conductive carrier constituting the electrode catalyst layer, a gas diffusion layer in contact with a side of the electrode catalyst layer different from the polymer electrolyte membrane, a separator, and an external circuit. To reach the cathode side electrocatalyst layer. The protons and electrons that have reached the cathode-side electrode catalyst layer react with oxygen contained in the oxidant gas supplied to the cathode side to generate water (O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O). In the fuel cell, electricity can be taken out through the above-described electrochemical reaction.

  Conventionally, an electrolyte membrane of a fuel cell is roughly classified into a fluorine-based electrolyte membrane and a hydrocarbon-based electrolyte membrane depending on the type of ion exchange resin that is a constituent material. Among these, the fluorine-based electrolyte membrane has a C—F bond and is excellent in heat resistance and chemical stability. In particular, it is a perfume known under the trade name of Nafion (registered trademark, manufactured by DuPont). A fluorine-based electrolyte membrane represented by a fluorosulfonic acid membrane is used. However, the above-mentioned fluorine-based electrolyte has a drawback that it is difficult to produce and is very expensive. For this reason, it is considered that a hydrocarbon electrolyte membrane is used instead of the perfluorosulfonic acid membrane. Compared with the above-mentioned fluorine-based electrolyte membrane, this hydrocarbon-based electrolyte membrane has the advantages that the raw material is inexpensive, the production process is simple, and the selectivity of the material is high, but the proton conductivity is low. It was insufficient to use as.

  In order to solve the above problems, attempts have been made to use fullerene and derivatives thereof, which are effective in improving proton conductivity of the electrolyte membrane and suppressing chemical degradation, for the electrolyte membrane (for example, Patent Document 1). Patent Document 1 discloses a proton conductive membrane comprising a water-soluble fullerene derivative or a mixture of a water-soluble fullerene derivative and a polymer material having a hydroxyl group in view of the perfluorosulfonic acid resin having a low methanol permeation blocking ability. A proton conductive composite membrane, in particular a proton conductive composite membrane for a methanol fuel cell, in which a membrane made of a different material having the property of suppressing the water solubility of a fullerene derivative is laminated on the surface of is disclosed.

  In Patent Document 2, the ion exchange capacity of the ionomer arranged in the catalyst layer is arranged to be higher by about 0.01 to 1.5 meq / g on the anode side than on the cathode side. Thus, basically, the membrane electrode assembly is filled with water through the electrolyte layer, and ions bonded to the hydrogen electrode reaction layer and the air electrode reaction layer cannot move, so that the ion concentration fixed to the anode is reduced. The state of becoming larger than the cathode continues. For this reason, the water on the cathode side moves to the anode side based on the difference in ion concentration and tries to counteract the ion concentration difference between the hydrogen electrode reaction layer side and the air electrode reaction layer side by osmotic pressure. Will be diffused back to the anode side.

  For this reason, in this fuel cell system, even if the anode supplies hydrogen without humidification or low humidification during power generation, it does not tend to dry, and water does not become excessive at the cathode. It is disclosed that the output of the fuel cell system can be increased.

In Patent Document 3, the ion exchange capacity of the electrolyte membrane is arranged in the order of the ionomer of the anode, the membrane, and the ionomer of the cathode, in the order of the dry weight of the ion exchange resin per 1 mol of ion exchange groups. This ensures constant power generation performance even when continuous operation in different environments is required, such as when the operation in a high current density region continues for a long period of time and the generated water accumulates and causes flatting. It is disclosed that it can be maintained.
JP 2004-55311 A JP-A-2005-174664 JP 2004-349180 A

  According to Patent Document 1, the proton conductive membrane has a laminated structure in which a perfluorosulfonic acid resin membrane such as Nafion is formed on both sides of a proton conductive layer made of a fullerene derivative (paragraph “0038”, Examples 1) of paragraphs “0048” to “0056”. Such a laminated structure is taken to prevent the fullerene derivative and the electrolyte membrane from eluting under the humidified condition (paragraph “0013”) because the fullerene derivative is water-soluble (paragraph “0013”). However, taking a laminated structure means that the production is complicated, and there is a problem that the manufacturing cost increases in mass production. Moreover, the said patent document 1 intends using it as an electrolyte membrane for methanol type fuel cells, and cannot be applied to a solid polymer type fuel cell, for example. For example, polyvinyl alcohol is preferably used as a polymer material having a hydroxyl group (claim 12). However, since polyvinyl alcohol is vulnerable to water vapor, the above-described hydrogen-oxygen type fuel cell has a problem that the mechanical strength is lowered. Further, in Patent Document 1, Nafion is used as a different material (claims 19 to 21 and paragraph “0034”), and as described above, these fluorine-based electrolytes are difficult to manufacture and very expensive. The problem is still not solved. Further, when a film is formed using a polymer material such as polyvinyl alcohol as described above, the fullerene derivative is introduced by bonding to the polymer chain of the polymer material, but this method is complicated. There was also a problem that the production efficiency of the membrane was poor because a process was required and the yield of the compound was poor.

In addition, generated water is generated at the cathode during power generation, and the following problems occur due to non-uniform water movement.
(1) When operation is performed at a high current density during power generation, a large amount of anode water flows to the cathode together with protons, and anode dryout occurs, resulting in a decrease in performance.
(2) When performing a low humidification operation during power generation, performance degradation due to drying occurs at the cathode inlet, and performance degradation due to flooding occurs at the cathode exit when operation at a high current density or high humidification is performed.

  In Patent Documents 2 and 3, since the ion exchange capacity of the electrolyte is increased and the water content is improved, there is a problem that durability is lowered.

  Furthermore, although water is produced at the cathode, the moisture content distribution also occurs depending on the location of the cathode, thereby causing problems such as management of the moisture content in the membrane-electrode assembly.

  As described above, the use of a hydrocarbon-based electrolyte for an electrolyte membrane has been strongly desired in terms of cost and material selectivity, but it is practically used in terms of proton conductivity, which is an essential characteristic for an electrolyte membrane. The current situation is that it is not easy to make it.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide an electrolyte membrane having improved proton conductivity, particularly a hydrocarbon electrolyte membrane for a polymer electrolyte fuel cell, and a method for producing the membrane. And

  Another object of the present invention is to provide an electrolyte membrane, particularly a hydrocarbon electrolyte membrane for a polymer electrolyte fuel cell, and a method for producing the same that can improve proton conductivity and suppress / prevent deterioration of the electrolyte. .

  Another object of the present invention is to provide an electrolyte membrane with improved proton conductivity, particularly a hydrocarbon electrolyte membrane for a polymer electrolyte fuel cell, which can be produced by an easy process, and a method for producing the membrane.

  As a result of intensive studies to solve the above problems, the present inventor has found that proton conductivity is higher than that of a conventional hydrocarbon electrolyte membrane by uniformly dispersing a specific amount of additive in the electrolyte membrane. It was found that the hydrocarbon electrolyte membrane containing the additive exhibits sufficient proton conductivity even under relatively high humidity conditions. In addition, as a result of further earnest studies on a method for producing a hydrocarbon-based electrolyte membrane containing fullerenol, the present inventor once dissolved fullerenol in a basic solution such as an aqueous sodium hydroxide solution, and then the basic fullerenol solution. It is found that a hydrocarbon-based electrolyte membrane in which fullerenol is uniformly dispersed can be easily and easily produced by immersing the electrolyte membrane in the solution or by further adding an electrolyte to the basic fullerenol solution and forming the mixture into a membrane. It was. In addition to the above production method, the present inventor can dissolve the solution in an aprotic polar solvent in which both fullerenol and the electrolyte can be dissolved, even if the pH of the mixture is not made basic. In addition, it has been found that a hydrocarbon electrolyte membrane in which fullerenol is uniformly dispersed can be produced easily and simply.

Further, the present inventor has paid attention to the problem of deterioration of the electrolyte membrane in the idle stop (OCV) state, which has been recently proposed as an important problem in the polymer electrolyte fuel cell as described above. This problem is considered to be caused by the following mechanism. That is, the electrolyte membrane does not inherently completely shut off the gas (makes it impermeable), so depending on the concentration gradient (partial pressure) of oxygen or hydrogen gas, hydrogen may flow from the anode side to the cathode side. Oxygen and nitrogen are slightly permeated (dissolved and diffused) from the cathode side to the anode side (this phenomenon is also referred to as “cross leak”). In particular, at the time of OCV, the oxygen concentration at the interface between the cathode and the electrolyte membrane is higher than that at the time of power generation. Therefore, the amount of oxygen that dissolves and diffuses from the cathode side to the anode side through the electrolyte membrane is also larger than at the time of power generation. For this reason, oxygen moves from the cathode side to the anode side due to cross leak, and oxygen reacts directly with hydrogen on the anode side, causing a reaction of H ₂ + O ₂ → H ₂ O ₂ , resulting in hydrogen peroxide (H ₂ O ₂ ) is generated, hydrogen is transferred from the anode side to the cathode side, and hydrogen directly reacts with oxygen on the cathode side to similarly generate hydrogen peroxide. This hydrogen peroxide is known to decompose the electrolyte component (ionomer) contained in the electrolyte membrane or the anode or cathode catalyst layer to chemically degrade the electrolyte membrane. Here, in consideration of the relationship between the potential of the anode catalyst layer and the cathode catalyst layer and the decomposition reaction of hydrogen peroxide, the potential on the cathode side is relatively high (about 0.6 to 1 V) with respect to the electrolyte potential. Since nearby oxygen directly reacts with hydrogen that has cross-leaked from the anode catalyst layer, the generated hydrogen peroxide is decomposed into oxygen and protons relatively quickly by the reaction of H ₂ O ₂ → O ₂ + 2H ++ 2e−. To do. On the other hand, since the potential is low on the anode side, the above-described decomposition reaction of hydrogen peroxide hardly occurs. For this reason, hydrogen peroxide generated frequently on the anode side moves into the electrolyte membrane due to concentration diffusion, oxidatively degrades the electrolyte membrane, or the presence of cations (eg, Fe ²⁺ , Cu ²⁺ ) in the electrolyte membrane. As a result, the electrolyte membrane components are degraded at an accelerated rate. As a result of further diligent studies to solve such problems of electrolyte membrane and catalyst layer degradation, particularly electrolyte membrane degradation, the present inventor has uniformly dispersed a specific amount of additive in the electrolyte membrane. It has been found that the obtained electrolyte membrane can suppress the permeation of oxygen, which is a fuel gas and an oxidant gas, particularly the oxidant gas, as compared with a membrane not added. In addition, this makes it possible to significantly suppress / prevent oxygen gas cross leak from the cathode side to the anode side and to significantly suppress / prevent electrolyte deterioration in the electrolyte membrane and the catalyst layer. It has been found that a fuel cell having such an electrolyte membrane can achieve high power generation efficiency.

  Based on the above findings, the present invention has been completed.

  That is, the above-mentioned objects are achieved by an electrolyte membrane in which the additive is dispersed in an amount of 1 to 50% by mass with respect to the electrolyte.

  The above-mentioned objects of the present invention also include a step of preparing a basic fullerenol solution (1) by dissolving fullerenol in a basic solution; and further immersing an electrolyte membrane in the basic fullerenol solution (1). The method for producing an electrolyte membrane of the present invention, or fullerenol is dissolved in a basic solution to prepare a basic fullerenol solution (2); the basic fullerenol solution (2) is mixed with an electrolyte, and the fullerenol-electrolyte is prepared. It is also achieved by the method for producing an electrolyte membrane of the present invention, which comprises the step of preparing a mixed solution (1); and further forming the fullerenol-electrolyte mixed solution (1) into a membrane.

  Further, the above objects of the present invention include the step of mixing fullerenol-electrolyte and solvent to prepare a fullerenol-electrolyte mixed solution (2); and further forming the fullerenol-electrolyte mixed solution (2) into a film. This can also be achieved by the method for producing an electrolyte membrane of the present invention.

  According to the present invention, the specific amount of additive present in the electrolyte membrane can significantly improve the proton conductivity of the electrolyte membrane even under relatively high humidity conditions. For this reason, according to the present invention, even when a hydrocarbon-based electrolyte membrane is used as an electrolyte membrane for a fuel cell, particularly a hydrogen-oxygen fuel cell, sufficient proton conductivity can be exhibited. In addition to the above advantages, the electrolyte membrane added with fullerenol suppresses the permeation of oxygen, which is a fuel gas and an oxidant gas, particularly an oxidant gas. Therefore, according to the electrolyte membrane of the present invention, oxygen gas cross-leakage from the cathode side to the anode side is significantly suppressed and prevented through the membrane, that is, electrolyte deterioration in the electrolyte membrane and the catalyst layer is significantly reduced. Can be suppressed and prevented. Therefore, the fuel cell having the electrolyte membrane of the present invention can achieve high power generation efficiency.

  In addition, according to the present invention, by providing a portion that promotes the diffusion of water in the electrolyte membrane, the rate of movement of water from the anode to the cathode in the film thickness direction increases during power generation. Power generation performance can be improved by suppressing drying that tends to occur on the anode side and flooding that tends to occur on the cathode side.

  Furthermore, according to the method of the present invention, fullerenol can be uniformly and easily dispersed at an arbitrary ratio without using special equipment, complicated operation, or a dedicated device. Therefore, according to the method of the present invention, it is possible to easily produce an electrolyte membrane to which fullerenol is added with stable quality, that is, exhibits excellent proton conductivity.

  Embodiments of the present invention will be described below.

  The first of the present invention relates to an electrolyte membrane in which an additive is dispersed in an amount of 1 to 50% by mass with respect to the electrolyte. The present invention is characterized in that a specific amount of the additive is present in the electrolyte membrane.

  The additive according to the present invention is preferably a fullerene derivative, a metal oxide or the like. For example, when fullerenol is used as the additive, fullerenol has an effect of improving proton conductivity. Compared with the electrolyte membrane, significantly higher proton conductivity can be exhibited even under relatively high humidity conditions (for example, the relative humidity is 60% or more). For this reason, it is particularly useful for a hydrocarbon-based electrolyte membrane having a problem of low proton conductivity. In addition, when the electrolyte membrane according to the present invention is used in, for example, a battery, the electrolyte membrane according to the present invention has a single layer structure in which an additive such as fullerenol is dispersed in the membrane, or a portion where a flooding phenomenon is likely to occur in the electrolyte membrane. A multi-layer structure may be formed by adding an additive such as a metal oxide, or by adding an additive such as a fullerene derivative or a metal oxide to a portion that is easily dried. For this reason, the electrolyte membrane having such a single layer structure is easier to manufacture than the laminated structure described in Patent Document 1, and does not cause problems such as layer peeling. In addition, in Patent Document 1 described above, since fullerenol is water-soluble, it was described that it flows out under humidified conditions. However, according to the present invention, fullerenol exhibits acidity in water, so under humidified conditions. The electrolyte swells in a gel state, and fullerenol is trapped in the gel. For this reason, in the electrolyte of the present invention, fullerenol does not dissolve and flow out of the membrane even in the presence of water. Therefore, when the electrolyte membrane of the present invention is applied to a hydrocarbon-based electrolyte membrane which is advantageous in terms of cost and material selection but has a problem in terms of proton conductivity, it maintains excellent proton conductivity for a long period of time. Can be particularly useful.

  As described above, the additive according to the present invention is preferably a fullerene derivative, a metal oxide or the like. The fullerene derivative is preferably a fullerenol, and the metal oxide is preferably an alkoxysilane or an alkoxytitanium.

  Examples of the alkoxysilane include tetraalkoxysilane having 4 alkoxy groups, trialkoxysilane having 3 alkoxy groups, and dialkoxysilane having 2 alkoxy groups. Although the kind in particular of alkoxy group is not restrict | limited, A methoxy group, an ethoxy group, a propoxy group, a butoxy group etc. are mentioned. Further, when the alkoxysilane has 3 or 2 alkoxy groups, an organic group, a hydroxyl group, or the like may be bonded to the silicon atom in the alkoxysilane, and the organic group is an amino group, a mercapto group, or the like. It may further have a functional group.

  Further, when the alkoxysilane is tetraalkoxysilane, tetramethoxysilane, tetraethoxysilane (TEOS), tetraisopropoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane and the like can be mentioned. Methoxysilanol, triethoxysilanol, trimethoxymethylsilane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- (2 -Aminoethyl) aminopropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane and the like. Examples of dialkoxysilane include dimethoxydimethylsilane, diethoxydimethylsilane, diethoxy-3-glycidoxypropylmethylsilane, dimethoxydiphenylsilane, and dimethoxymethylphenylsilane. Of these, tetraethoxysilane is more preferable.

  Although the said alkoxysilane can also be used independently, it can also be used in combination of 2 or more types. Moreover, the alkoxysilane having 2 to 4 alkoxy groups described above can be used in combination with a monoalkoxysilane having one alkoxy group. Examples of the monoalkoxysilane that can be used in this way include trimethylmethoxysilane, trimethylethoxysilane, and 3-chloropropyldimethylmethoxysilane.

The alkoxytitanium is represented by the chemical formula TiR ′ _n (OR) _4-n , wherein R and R ′ are alkyl groups, and n is 0 or an integer of 1 to 3. R and R ′ may be the same or different alkyl groups, and when there are a plurality of R and R ′, they may be the same or different alkyl groups. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Furthermore, part of R in the formula may be hydrogen or an alkenyl group having 2 to 10 carbon atoms, and examples of the alkenyl group include a vinyl group, an isopropenyl group, a butadienyl group, and a 2-methylallyl group. It is done. The substituent represented by R ′ in the formula may contain an epoxy group or a glycidyl group in the molecule.

  Preferable specific examples of the alkoxy titanium include tetraethoxy titanium, tetrapropoxy titanium, tetraisopropoxy titanium and the like. Further, a mixed system of two or more types of the above-described alkoxy titanium may be used mainly based on these alkoxy titaniums. Furthermore, the alkoxytitanium additive according to the present invention may be used in combination with the above alkoxysilane according to the present invention. In this case, two or more types of alkoxytitanium and two or more types of alkoxysilane may be used. Good.

In the present specification, “fullerenol” is a compound in which a hydroxyl-containing group is bonded to a fullerene skeleton. The “hydroxyl-containing group” means a group having one or more hydroxyl groups in the group. Specifically, hydroxyl group (—OH), sulfone group (—SO ₃ H), carboxyl group (—COOH), phosphone group [—PO ₃ H ₂ ], —OSO ₃ H, —OPO (OH) _{2 and the} like. And preferably a hydroxyl group (—OH), a sulfone group (—SO ₃ H) and a carboxyl group (—COOH). In addition, the fullerene that can be used in this case is not particularly limited, and conventionally known fullerenes can be used. Specifically, spherical carbon cluster molecules Cn such as C60, C70, C76, C78, C82, C84, C90, and C96 are used. (N is 60 or more) etc. are mentioned preferably. Among these, C60 and C70 are preferable in consideration of reactivity and the like. Further, the number of substitution of the hydroxyl-containing group to the fullerene varies depending on the electrolyte used and is not particularly limited, and can be appropriately selected according to the desired proton conductivity of the electrolyte membrane. For example, in the case of C60 fullerene, the number of hydroxyl-containing group substitution to fullerene is preferably 1 to 24, more preferably 6 to 12, and in the case of C70 fullerene, the hydroxyl to fullerene The number of substitutions of the containing group is preferably 1 to 28, more preferably 6 to 14.
Further, the substitution position of the hydroxyl-containing group to fullerene is not particularly limited, and can be appropriately selected according to the desired proton conductivity of the electrolyte membrane.

In the present invention, the method for producing fullerenol is not particularly limited, and a known method can be used. For example, when fullerenol has a sulfone group (—SO ₃ H), a method of reacting fullerene in fuming sulfuric acid or concentrated sulfuric acid at a high temperature can be used. Further, the methods described in JP 2000-247935 A, JP 9-157273 A, JP 7-247273 A, JP 7-188129 A, JP 5-221623 A, and the like can be applied. Alternatively, a commercially available product may be used as fullerenol. Such commercial products include Nanom Spectra series fullerene hydroxide (trade name: Hydroxide C60 (HX10-S), Hydroxide mix (HX10-M)) manufactured by Frontier Carbon Co., Ltd .; Honjo Chemical Examples include fullerenol and hydrogen sulfated fullerenol.

  Further, the electrolyte membrane containing an additive such as fullerenol of the present invention significantly suppresses / prevents permeation of fuel gas and oxidant gas, particularly oxygen which is oxidant gas. For this reason, according to the electrolyte membrane of the present invention, it is possible to significantly suppress / prevent oxygen gas cross-leakage from the cathode side to the anode side through the membrane, thereby significantly reducing electrolyte deterioration in the electrolyte membrane and the catalyst layer. It can be suppressed / prevented. Therefore, the fuel cell having the electrolyte membrane of the present invention is expected to achieve high power generation efficiency.

The electrolyte membrane used in the present invention is not particularly limited, and a membrane made of a known electrolyte can be used, but any member having at least proton conductivity may be used. At this time, the electrolyte membrane preferably contains a polymer having a proton dissociable functional group. In the present specification, the “proton dissociable group” means a functional group from which a hydrogen atom can be ionized as a proton (H ⁺ ) and separated. The proton dissociating functional group is not particularly limited, for example, a sulfonic group _(-SO 3 H), such as a phosphonic group _[-PO 3 _{H 2]} are preferably exemplified. Specifically, an electrolyte such as phosphoric acid or ionic liquid is formed on a porous thin film formed of a fluorine-based electrolyte membrane, a hydrocarbon-based electrolyte membrane, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or the like. Well-known solid polymer electrolyte membranes such as membranes impregnated with components, membranes in which a polymer microporous membrane is impregnated with a liquid electrolyte, membranes in which a porous body is filled with a polymer electrolyte, etc. Can be used.

  Among these, as a fluorine-type electrolyte membrane, it does not restrict | limit in particular, A well-known fluorine-type electrolyte membrane is used. Specifically, as the fluorine-based electrolyte having a proton dissociative functional group constituting the fluorine-based electrolyte membrane, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), Flemion ( (Registered trademark, manufactured by Asahi Glass Co., Ltd.), etc., perfluorocarbon sulfonic acid polymers, polytrifluorostyrene sulfonic acid polymers, perfluorocarbon phosphonic acid polymers, trifluorostyrene sulfonic acid polymers, ethylenetetrafluoroethylene-g-styrene sulfone. An acid-based polymer, an ethylene-tetrafluoroethylene copolymer, a polyvinylidene fluoride-perfluorocarbon sulfonic acid-based polymer, an ion exchange resin manufactured by Dow Chemical Company, an ethylene-tetrafluoroethylene copolymer, and trifluorostyrene. A resin to polymer are mentioned as suitable examples. From the viewpoint of power generation performance such as heat resistance and chemical stability, these fluorine-based electrolyte membranes are preferably used, and particularly preferably a fluorine-based electrolyte membrane composed of a perfluorocarbon sulfonic acid polymer.

  Also, the hydrocarbon film is not particularly limited, and a known hydrocarbon electrolyte film is used. Specifically, a hydrocarbon-based resin film having a sulfonic acid group, a hydrocarbon polymer compound doped with an inorganic acid such as phosphoric acid, an organic partially substituted with a functional group of a proton conductor / Inorganic hybrid polymer, proton conductor impregnated with phosphoric acid solution or sulfuric acid solution in polymer matrix is used, but considering oxidation resistance, low gas permeability, ease of production and low cost, A hydrocarbon film having a sulfonic acid group is preferred. The hydrocarbon membrane used in the present invention is not particularly limited, and a known hydrocarbon electrolyte membrane is used. For example, sulfonated polyethersulfone (S-PES), PBI (polybenzimidazole) , PBO (polybenzoxazole), S-PPBP (sulfonated polyphenoxybenzoylphenylene), S-PEEK (sulfonated polyetheretherketone), sulfonamide type polyethersulfone, sulfonated polyetheretherketone, sulfonamide type poly Ether ether ketone, sulfonated crosslinked polystyrene, sulfonamide type crosslinked polystyrene, sulfonated polytrifluorostyrene, sulfonamide type polytrifluorostyrene, sulfonated polyaryletherketone, sulfonamide type polyaryl ether T, sulfonated poly (aryl ether sulfone), sulfonamide type poly (aryl ether sulfone), polyimide, sulfonated polyimide, sulfonamide type polyimide, sulfonated 4-phenoxybenzoyl-1,4-phenylene, sulfonamide type 4- Phenoxybenzoyl-1,4-phenylene, phosphonic acid type 4-phenoxybenzoyl-1,4-phenylene, sulfonated polybenzimidazole, sulfonamide type polybenzimidazole, phosphonic acid type polybenzimidazole, sulfonated polyphenylene sulfide, sulfonamide Type polyphenylene sulfide, sulfonated polybiphenylene sulfide, sulfonamide type polybiphenylene sulfide, sulfonated polyphenylene sulfone, sulfonamide type polyphenylene sulfide Preferred examples include nylene sulfone, sulfonated polyphenoxybenzoylphenylene, sulfonated polystyrene-ethylene-propylene, sulfonated polyetheretherketone, sulfonated polyphenyleneimide, polybenzimidazole-alkylsulfonic acid, sulfoallylated polybenzimidazole, and the like. It is done. These hydrocarbon-based electrolyte membranes are preferably used from the viewpoint of production such that the raw material is inexpensive, the production process is simple, and the selectivity of the material is high. In addition, as for the electrolyte (ion exchange resin) mentioned above, only 1 type may be used independently and 2 or more types may be used together. Moreover, it is needless to say that other materials may be used without being limited to the above-described materials.

  Among these, as described above, according to the present invention, proton conductivity can be improved by the presence of fullerenol, so that the hydrocarbon-based electrolyte membrane / hydrocarbon-based electrolyte, particularly the hydrocarbon-based electrolyte having a proton-dissociating functional group. Membrane / hydrocarbon electrolytes are particularly useful. Therefore, in the present invention, sulfonated polyethersulfone (S-PES), sulfonated polyetheretherketone (S-PEEK), and sulfonated polyphenoxybenzoylphenylene (S-PPBP) are particularly preferable as the electrolyte constituting the electrolyte membrane. used.

  The thickness of the electrolyte membrane may be appropriately determined in consideration of the characteristics of the MEA incorporating the membrane or the solid electrolyte fuel cell (PEFC), and is not particularly limited. However, the thickness of the electrolyte membrane is preferably 5 to 300 μm, more preferably 10 to 200 μm, still more preferably 15 to 150 μm, and particularly preferably 20 to 50 μm. When the thickness is within such a range, the balance of strength during film formation, durability during use, and output characteristics during use can be appropriately controlled.

  In the present invention, it is essential to add and disperse the additive in an amount of 1 to 50% by mass with respect to the electrolyte. At this time, when the amount of the additive is less than 1% by mass, the effect of addition (particularly, the effect of improving proton conductivity and the effect of suppressing / preventing electrolyte deterioration) cannot be obtained. On the contrary, if the amount of the additive exceeds 50% by mass, the improvement of the effect corresponding to the addition is not recognized, and conversely the toughness of the material is lost. It becomes difficult. The amount of the additive is preferably 2 to 40% by mass, more preferably 5 to 30% by mass with respect to the electrolyte.

  When the additive is a metal oxide, it is essential that the additive is 1 to 50% by mass, preferably 3 to 30% by mass, more preferably 7 to 25% by mass with respect to the electrolyte. . At this time, if the amount of the additive is less than 1% by mass, the effect of addition (particularly, the effect of improving proton conductivity and the effect of suppressing / preventing electrolyte deterioration) cannot be obtained. On the contrary, if the amount of the additive exceeds 50% by mass, the improvement of the effect corresponding to the addition is not recognized, and conversely the toughness of the material is lost. It becomes difficult.

  In addition, when the additive is fullerenol, the addition amount is preferably 1 to 50% by mass with respect to the electrolyte, and if it is less than 1% by mass, the effect of addition of fullerenol (especially the effect of improving proton conductivity or In some cases, the effect of suppressing / preventing electrolyte deterioration is not sufficiently achieved, and there is no advantage over cost increase due to an increase in the number of steps. Conversely, if the amount of fullerenol exceeds 50% by mass, no improvement in the effect commensurate with the addition of fullerenol is observed, and conversely, the durability against long-term operation may be lost due to the loss of the toughness of the material. The amount of fullerenol is preferably 2.5 to 25% by mass, more preferably 5 to 20% by mass with respect to the electrolyte.

  The present invention is an electrolyte membrane provided with a site that promotes diffusion of water, and the site preferably contains the additive. For example, when the electrolyte of the present invention is used in a battery, by providing a portion that promotes water diffusion in the electrolyte membrane, during power generation, drying due to outflow of proton entrained water or flooding phenomenon under high current density or high humidity This prevents the performance degradation due to the low humidity condition and the performance on the high current density side.

  The site | part which accelerates | stimulates the spreading | diffusion of a water here may be provided in the surface direction or thickness direction in an electrolyte membrane, and may be provided in any of a surface direction and thickness direction.

In the present specification, the “site that promotes the diffusion of water” refers to a region where the diffusion rate of water is high. Specifically, the diffusion rate of water is 1 × 10 ⁻⁷ (cm ² / s) or more. (More specifically, 3 × 10 ^{− ○} or more and 1 × 10 ⁻⁴ or less is more preferable at a humidity of 30 to 80% RH), and by adding a fullerene derivative, a metal oxidizer, This is also a region in which the diffusion rate is higher than that in the case where no diffusion rate is added.

  The present invention provides an electrolyte comprising an anode electrode catalyst layer and a cathode electrode catalyst layer on both sides of an electrolyte membrane, and further formed with a pair of gas diffusion layers so as to carry the anode electrode catalyst layer and the cathode electrode catalyst layer. In the membrane-electrode assembly, it is preferable that the portion that promotes the diffusion of water is provided in a portion where drying of the membrane is easy to dry. For example, in the thickness direction of the electrolyte membrane-electrode assembly, the anode in the electrolyte membrane More preferably, the portion is formed on at least a part of the cathode gas inlet side in the electrolyte membrane with respect to the in-plane direction of the electrolyte membrane-electrode assembly. preferable.

  Further, in the present invention, it is preferable to provide the portion that promotes the diffusion of water in a portion where a flooding phenomenon easily occurs, and the portion is a cathode in the electrolyte membrane with respect to the thickness direction of the electrolyte membrane-electrode assembly. More preferably, the portion is formed on at least a part of the cathode gas outlet side in the electrolyte membrane with respect to the in-plane direction of the electrolyte membrane-electrode assembly. preferable.

  In particular, the portion that promotes the diffusion of water in the electrolyte membrane according to the present invention is provided at a portion where the electrolyte membrane is easily dried when the diffusion coefficient of water at a low humidity (humidity 0 to 40% RH) is promoted. Preferably, the part where the electrolyte membrane is easy to dry is the anode side and / or the cathode gas inlet side, and more specifically, the part which promotes the diffusion of water in the thickness direction of the electrolyte membrane is the anode side. More preferably, the portion that promotes the diffusion of water in the surface direction of the electrolyte membrane is formed on the cathode gas inlet side. The thickness direction of the electrolyte membrane will be described in more detail. The thickness direction of the electrolyte membrane is the x axis, the thickness of the electrolyte membrane is L, and the center of the electrolyte membrane (the same as the middle point of the thickness of the electrolyte membrane described later) X = 0, the surface of the electrolyte membrane on the cathode side is x = (− 1/2) L, and the surface of the electrolyte membrane on the anode side is x = (1/2) L, 0 ≦ x ≦ (1/2 ) L is a preferable region as a portion promoting the diffusion of water on the anode side, and (1/3) L ≦ x ≦ (1/2) L is a more preferable region as a portion promoting the diffusion of water.

  Instead of or in addition to the above, the in-plane direction of the electrolyte membrane will be described in more detail. When the y axis is provided perpendicular to the x axis from the center of the electrolyte membrane on the x axis, the length of the electrolyte membrane Is k and the gas passes from the minus direction of the y-axis in the plus direction, 0 ≦ y ≦ (1/2) k is a preferable range in the region on the cathode gas inlet side as a portion that promotes the diffusion of water. , 0 ≦ y ≦ (1/3) k is a more preferable range in the region on the cathode gas inlet side as a portion that promotes the diffusion of water. As a result, it is considered that the diffusion coefficient of water at low humidity can be improved and performance degradation due to drying can be prevented.

  It is preferable that the cathode gas inlet side and the anode side contain an additive such as the above fullerene derivative or metal oxide.

  The anode side as the site for promoting the diffusion of water in the electrolyte membrane according to the present invention is the center plane of the electrolyte membrane (the thickness direction of the electrolyte membrane is the x axis, and the thickness of the electrolyte membrane on the x axis is The region on the anode side with reference to the virtual plane when the electrolyte membrane is cut perpendicularly from the middle point of the cathode, and the cathode side as a site that promotes the diffusion of water in the electrolyte membrane according to the present invention, A region on the cathode side with reference to the center plane of the electrolyte membrane.

  When the portion that promotes the diffusion of water in the electrolyte membrane according to the present invention improves the diffusion coefficient of water at a high humidity (humidity 40 to 100% RH), it is preferably provided at a portion that easily causes a flooding phenomenon. More specifically, it is on the cathode side, and more specifically, it is more preferably formed on the cathode side in the thickness direction of the electrolyte membrane and on the cathode gas outlet side in the surface direction of the electrolyte membrane.

  The thickness direction of the electrolyte membrane will be described in more detail. The thickness direction of the electrolyte membrane is taken as the x axis, the thickness of the electrolyte membrane is L, the center of the electrolyte membrane is x = 0, and the surface of the electrolyte membrane on the cathode side is x. = (− 1/2) L, where x = (1/2) L is the surface of the electrolyte membrane on the anode side, (−1/2) L ≦ x ≦ 0 is the portion that promotes water diffusion on the cathode side (−1/2) L ≦ x ≦ − (1/3) L is a more preferable region as a portion that promotes the diffusion of water.

  Instead of or in addition to the above, the in-plane direction of the electrolyte membrane will be described in more detail. When the y axis is provided perpendicularly from the center of the electrolyte membrane on the x axis, the length of the electrolyte membrane is k, Assuming that the gas flow direction is the y-axis brass direction, (1/2) k ≦ y ≦ k is a preferable range in the region on the cathode gas outlet side as a portion that promotes the diffusion of water, and (2/3) k ≦ x ≦ k is a more preferable range in the region on the cathode gas outlet side as the portion that promotes the diffusion of water. Thereby, the diffusion coefficient of water at high humidity can be improved, and performance degradation at high humidity and high current density can be prevented.

  It is preferable that the cathode gas outlet side and the cathode side contain an additive such as the above metal oxide.

  In addition, when providing the site | part which accelerates | stimulates the spreading | diffusion of water, it may be a layer form or a film | membrane form, and when the electrolyte membrane takes a multi-layer structure, the diffusion coefficient of water is improved, high humidity and Performance degradation at current density can be prevented.

  Further, in the present invention, the fullerene derivative additive and the metal oxide additive may be included in the same site that promotes the diffusion of water, but are more preferably used in different sites. .

  Moreover, as described above, a portion that promotes the diffusion of water according to the present invention may be provided by combining the above conditions of low humidity and high humidity.

  In FIG. 7 of the present specification, there is shown a conceptual diagram of the portion that promotes the diffusion of water, the cathode gas outlet side, and the cathode inlet side. In this figure, the gas flow path is the surface direction of the electrolyte membrane. The cathode gas outlet side and the cathode inlet side when the gas flows meandering in parallel with each other are described.

  In the electrolyte membrane according to the present invention, the water content of the site that promotes the diffusion of water does not increase, but the diffusion of water at the site that promotes the diffusion of water is preferably promoted. This is because some moisture is supplied to the dried part such as the anode side due to the increase in the total water content in the electrolyte membrane, but flooding phenomenon tends to occur when the water content in the electrolyte membrane increases. This is because it is considered that the water content in the electrolyte membrane, and hence the membrane-electrode assembly system, can be managed by circulating water through the system by diffusion while keeping the water content of the system constant. .

In the electrolyte membrane according to the present invention, the diffusion coefficient D (cm ² / s) of water is preferably 3 × 10 ⁻⁷ or more and 1 × 10 ⁻⁴ or less in the range of 30 to 80% RH.

When the water diffusion coefficient D (cm ² / s) is less than 3 × 10 ⁻⁷ , the generated water is generated from the cathode rich in generated water because the diffusion rate of water is slow in the state where an electric field is applied during power generation. There is a risk that back diffusion to the anode does not occur and anode dryout cannot be prevented.

  A method for calculating the diffusion coefficient from the embodiment of the present specification will be briefly described below. Although the method of measuring the time change of the weight of the electrolyte membrane at each humidity is used, the diffusion equation is generally given by the following Fick second law:

By the initial calculation method, the mass change rate (Mt / M∞) is proportional to √t, and the diffusion coefficient at each humidity is calculated from the mass change rate (Mt / M∞), time (s), and film thickness.

  The method for producing the electrolyte membrane of the present invention is not particularly limited, and a known method can be applied in the same manner or modified, but when producing a fullerenol-containing electrolyte membrane having a single layer structure, preferably fullerenol is used. A method capable of uniformly dispersing in the film is preferred. Since fullerenol is acidic, it dissolves in a basic solution. Therefore, once the fullerenol is dissolved in the basic solution to prepare a basic fullerenol solution in which the fullerenol is uniformly dissolved, and then the electrolyte membrane is immersed in the basic fullerenol solution, the fullerenol is uniformly dispersed in the film. Can be dispersed. Therefore, the second of the present invention is (a) a step of preparing a basic fullerenol solution (1) by dissolving fullerenol in a basic solution; and (a) an electrolyte membrane in the basic fullerenol solution (1). The manufacturing method of the electrolyte membrane of this invention including the process of soaking is provided.

  Here, first, the second of the present invention will be described in detail.

In the step (a), fullerenol is dissolved in a basic solution to prepare a basic fullerenol solution (1). In this step (a), the basic solution is not particularly limited as long as it can dissolve fullerenol. Examples of the base constituting the basic solution include lithium hydroxide (LiOH) and sodium hydroxide (NaOH). And alkali metal hydroxides such as potassium hydroxide (KOH); alkaline earth metal hydroxides such as calcium hydroxide, barium hydroxide and magnesium hydroxide; ammonium hydroxide (NH ₄ OH) and the like. . Of these, potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH ₄ OH) and lithium hydroxide (LiOH) are preferred. When the electrolyte has a sulfone group, it takes a form in which barium hydroxide, barium in calcium hydroxide, and calcium are bonded to the sulfone group and are not easily released. Therefore, when the electrolyte has a sulfone group, these bases Is not preferred. The above bases may be used alone or in the form of a mixture of two or more. The solvent for dissolving the base is not particularly limited as long as it can dissolve the base and fullerenol, but water; lower alcohols such as methanol, ethanol and propanol; lower polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin. Ketones such as acetone, methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK) and cyclohexanone; mercaptans such as ethanethiol and benzylthiol. The said solvent may be used independently or may be used with the form of a 2 or more types of mixture. Among the above solvents, a solvent that does not dissolve the electrolyte membrane in the step (A) is preferable, and water is particularly preferably used as such a solvent.

  Further, the pH of the basic solution is not particularly limited as long as it does not inhibit the dissolution of fullerenol and does not dissolve or excessively swell the electrolyte. Preferably it is 7-14, More preferably, it is 12-14. Within such a pH range, fullerenol can be sufficiently dissolved, and even if an electrolyte membrane is added in a later step, the electrolyte membrane does not deteriorate or deteriorate. At this time, the amount of the base added to the solvent is not particularly limited as long as it can dissolve fullerenol, and is preferably an amount such that the pH of the basic solution falls within the above range.

  In the above step (a), the amount of fullerenol added to the basic solution is such that the content of fullerenol in the membrane obtained after step (a) is 1 to 50% by mass with respect to the electrolyte constituting the membrane. The amount is not particularly limited as long as it is an appropriate amount, and is appropriately selected depending on the amount of fullerenol dispersed in the film. Preferably, the amount of fullerenol added to the basic solution is such that the concentration in the solution is 5 to 40 (w / v)%, more preferably 10 to 40 (w / v)%. If it is such a range, fullerenol can be easily dissolved in a basic solution.

  In the step (A), the electrolyte membrane is immersed in the basic fullerenol solution (1) prepared in the step (A). The conditions for immersing the film in this step are not particularly limited as long as a sufficient amount of fullerenol can be uniformly dispersed in the film, but it is preferable that the electrolyte does not elute or swell excessively. For example, the electrolyte membrane is placed in the basic fullerenol solution (1) prepared in the above step (a) at 20 to 80 ° C., more preferably 20 to 40 ° C., for 6 to 48 hours, more preferably 10 to 20 hours. It is preferable to immerse. In addition, since the electrolyte membrane used at this process is the same as that mentioned above, description is abbreviate | omitted here. Further, in this step (a), when the amount of fullerenol dispersed in the film does not reach a desired level in one step, the above step may be repeated a plurality of times until the desired level is reached.

  Alternatively, once the fullerenol is once dissolved in a basic solution to prepare a basic fullerenol solution in which the fullerenol is uniformly dissolved, this basic fullerenol solution is mixed with the electrolyte, and the fullerenol and the electrolyte are uniformly dissolved in the solution. After preparing a fullerenol-electrolyte mixed solution, an electrolyte membrane in which fullerenol is uniformly dispersed can be obtained by forming the fullerenol-electrolyte mixed solution into a membrane using the mixed solution. Therefore, the third of the present invention is (a ′) a step of preparing a basic fullerenol solution (2) by dissolving fullerenol in a basic solution; (ii ′) the basic fullerenol solution (2) as an electrolyte. There is provided a method for producing an electrolyte membrane of the present invention, comprising: mixing to prepare a fullerenol-electrolyte mixed solution (1); and (c) a step of forming the fullerenol-electrolyte mixed solution (1) into a membrane. .

  Here, the third aspect of the present invention will be described in detail.

In the above step (a ′), fullerenol is dissolved in a basic solution to prepare a basic fullerenol solution (2). In this step (a ′), the basic solution is not particularly limited as long as it can dissolve fullerenol. Examples of the base constituting the basic solution include lithium hydroxide (LiOH) and potassium hydroxide (KOH). ), Hydroxides of alkali metals such as sodium hydroxide (NaOH); hydroxides of alkaline earth metals such as calcium hydroxide, barium hydroxide, magnesium hydroxide; ammonium hydroxide (NH ₄ OH) It is done. Of these, potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH ₄ OH) and lithium hydroxide (LiOH), more preferably potassium hydroxide (NaOH), sodium hydroxide (KOH) And ammonium hydroxide (NH ₄ OH) is preferred. When the electrolyte has a sulfone group, it takes a form in which barium hydroxide, barium in calcium hydroxide, and calcium are bonded to the sulfone group and are not easily released. Therefore, when the electrolyte has a sulfone group, these bases Is not preferred. The above bases may be used alone or in the form of a mixture of two or more. The solvent for dissolving the base is not particularly limited as long as it can dissolve the base, fullerenol, and electrolyte, but water; lower alcohols such as methanol, ethanol, and propanol; lower solvents such as ethylene glycol, propylene glycol, and glycerin. Examples thereof include monohydric alcohols; ketones such as acetone, methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), and cyclohexanone; mercaptans such as ethanethiol and benzylthiol.

  The said solvent may be used independently or may be used with the form of a 2 or more types of mixture. Of the above solvents, it is preferable that the fullerenol and the electrolyte can be dissolved so that the fullerenol and the electrolyte are uniformly mixed when mixed with the electrolyte in the step (ii). As such a solvent, lower ketones, lower alcohols, or a mixed solvent of these solvents and water are preferably used, and water for dissolving fullerenol (preparing a basic aqueous solution), and an electrolyte It is more preferable to use a mixed solution of acetone, methanol, ethanol, and propanol for dissolving the solvent. This is because both fullerenol and the electrolyte can be sufficiently uniformly mixed. The mixing ratio of water and the solvent for dissolving the electrolyte at this time is not particularly limited as long as the fullerenol and the electrolyte can be mixed sufficiently uniformly. A mixed solution mixed at a mass ratio of 5: 9.5 to 5: 5, more preferably 1: 9 to 2: 8 is particularly preferably used.

  Further, the pH of the basic solution is not particularly limited as long as it can dissolve fullerenol and does not insolubilize fullerenol by changing the pH to the acidic side due to pH change due to addition of an electrolyte solution or electrolyte in the next step. Preferably it is 10-14, More preferably, it is 12-14. Within such a pH range, fullerenol can be sufficiently dissolved, and precipitation of fullerenol does not occur even when an electrolyte is added and mixed in a subsequent step. At this time, the amount of the base added to the solvent is not particularly limited as long as it can dissolve fullerenol, and is preferably an amount such that the pH of the basic solution falls within the above range.

  In the above step (A ′), the amount of fullerenol added to the basic solution is 1 to 50% by mass with respect to the electrolyte in which the content of fullerenol in the membrane obtained after the step (U ′) constitutes the membrane. The amount is not particularly limited and is appropriately selected depending on the amount of fullerenol dispersed in the film. Preferably, the amount of fullerenol added to the basic solution is such that the concentration in the solution is 0.01 to 40 (w / v)%, more preferably 0.01 to 20 (w / v)%. It is. If it is such a range, fullerenol can be easily dissolved in a basic solution.

  In the step (ii '), the basic fullerenol solution (2) prepared in the step (a') is mixed with an electrolyte to prepare a fullerenol-electrolyte mixed solution (1). In this step, the mixing ratio of the basic fullerenol solution (2) and the electrolyte is appropriately selected according to the desired amount of fullerenol in the film obtained in the subsequent step (d). Specifically, it is the same as the amount of fullerenol in the membrane (1 to 50% by mass with respect to the electrolyte). The electrolyte may also be mixed with a basic fullerenol solution in the form of a solution. In this case, the solvent used for dissolving the electrolyte is not particularly limited, and for example, a water / lower alcohol mixed solvent, a water / lower ketone compound mixed solvent, an aprotic polar solvent, and the like can be used. A solvent compatible with the above (A ′) can be used, but more preferably a solvent having the same composition as the above (A ′) is selected. When the electrolyte is mixed with the basic fullerenol solution (2) in the form of a solution, the concentration of the electrolyte in the solution is not particularly limited, and is appropriately selected depending on the ratio to the mixed fullerenol and ease of handling.

  Next, in the step (C '), a film is formed using the fullerenol-electrolyte mixed solution (1) obtained in the step (A'). At this time, the film forming conditions are not particularly limited as long as the electrolyte film having a desired thickness as described above can be obtained. Specifically, the thickness of the fullerenol-electrolyte mixed solution (1) after drying on a sheet such as a glass sheet, a polyester sheet such as a PTFE (polytetrafluoroethylene) sheet, a PET (polyethylene terephthalate) sheet, or the like. The electrolyte membrane is applied so as to have a preferable thickness as described above, and is dried in a vacuum dryer or under reduced pressure. The drying temperature is selected according to the solvent used. For example, in the case of a solvent having a boiling point of less than 60 ° C., the preferred drying temperature is 10 to 20 ° C .; in the case of a solvent having a boiling point of 60 ° C. or more and less than 100 ° C., the preferred drying temperature is 20 to 40 ° C .; In the case of a solvent having a temperature not lower than 150 ° C. and lower than 150 ° C., a preferable drying temperature is 40 to 80 ° C .; in the case of a solvent not lower than 150 ° C. and lower than 300 ° C., the preferable drying temperature is 80 to 150 ° C. Moreover, although the time which drying requires can be suitably selected according to the kind etc. of solvent, Preferably it is 4 to 24 hours, More preferably, it is 6 to 20 hours. When a plurality of solvents having different boiling points are used, drying at a low temperature may be performed until a component having a low boiling point volatilizes, and then drying at a high temperature may be performed to volatilize a component having a higher boiling point.

  In addition, it is preferable to further perform the process of removing the base contained in a film | membrane after the said 2nd and 3rd method of this invention is complete | finished. As described above, fullerenol contained in the membrane is eluted under basic conditions, but insolubilized under neutral or acidic conditions. For this reason, by utilizing this property, the electrolyte membrane obtained above is immersed in pure water or the like at 25 to 40 ° C. for 1 to 3 hours to confine insolubilized fullerenol in the electrolyte, and on the surface. Any excess fullerenol that adheres and is easily washed off can be removed. The removal of excess fullerenol may be performed by other methods. Also, the method for removing the base contained in the electrolyte membrane is not particularly limited, and a known method can be used.For example, the electrolyte membrane after removing the excess fullerenol as described above is placed in an acidic aqueous solution. After neutralizing by immersing at 25 to 40 ° C. for 5 to 30 hours, the base can be removed by further immersing in pure water or the like at 25 to 40 ° C. for 5 to 30 hours. The acidic aqueous solution that can be used in the above method is not particularly limited as long as it can neutralize the base used. For example, an aqueous solution of sulfuric acid, hydrochloric acid or phosphoric acid, preferably an aqueous solution of sulfuric acid or hydrochloric acid can be used. The concentration is appropriately adjusted depending on the amount of base used.

  Or you may manufacture the electrolyte membrane of this invention by shape | molding into a film | membrane using the liquid mixture which mixed fullerenol, electrolyte, and the solvent together. Accordingly, the fourth aspect of the present invention is that (A) a step of preparing a fullerenol-electrolyte mixture (2) by mixing fullerenol, an electrolyte and a solvent; and (B) the fullerenol-electrolyte mixture (2) as a membrane. It is the manufacturing method of the electrolyte membrane of this invention which has the process shape | molded in.

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

  In the above step (A), the solvent used in preparing the fullerenol-electrolyte mixed solution (2) is not particularly limited as long as it can dissolve both fullerenol and the electrolyte, but is an aprotic polar solvent. It is preferable. Such a solvent is not particularly limited, and specific examples include dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, dimethylacetamide, sulfolane, quinoline, hexamethylphosphoric triamide, and preferably dimethyl sulfoxide. Dimethylformamide, N-methylpyrrolidone, dimethylacetamide, sulfolane and hexamethylphosphoric triamide. The said solvent may be used independently or may be used with the form of a 2 or more types of liquid mixture.

  In the step (A), the electrolyte may be mixed in the form as it is or may be mixed in the form of a solution once dissolved in a solvent, but is preferably mixed in the form of a solution. Similarly, fullerenol may be mixed as it is, or once dissolved in a solvent and then mixed in the form of a solution, but is preferably mixed in the form of a solution. This is because the use in the form of a solution is easier to handle and the form of the solution is easier to mix, so that the fullerenol and the electrolyte can be easily and uniformly mixed in a short time. The solvent used when mixing the electrolyte in the form of a solution is not particularly limited as long as the electrolyte can be dissolved. Specifically, the solvent is used when preparing the fullerenol-electrolyte mixed solution (2). It is preferable to select from the following solvents. The concentration of the electrolyte is not particularly limited and can be appropriately selected depending on the concentration of fullerenol, but is preferably 1 to 25 (w / v)% in the solution. Moreover, in order to accelerate | stimulate the solubility of electrolyte, you may heat the liquid which melt | dissolved electrolyte, for example, when it heats for 30 to 120 minutes at 100-120 degreeC, electrolyte can melt | dissolve completely in a solvent. Further, the solvent used when mixing fullerenol in the form of a solution is not particularly limited as long as it can dissolve fullerenol. Specifically, when preparing the fullerenol-electrolyte mixture (2), It is preferably selected from the solvents used. The fullerenol concentration is not particularly limited and can be appropriately selected depending on the concentration of the electrolyte, but is preferably 0.01 to 25 (w / v)% in the solution. Moreover, in order to accelerate | stimulate the solubility of fullerenol, you may heat the liquid which melt | dissolved fullerenol, for example, if it heats for 15 to 30 minutes at 100-120 degreeC, fullerenol can melt | dissolve completely in a solvent. In the present invention, after the fullerenol and the electrolyte are once dissolved in a solvent, the solvents used when mixing both may be the same or different, but they are easy to handle and In consideration of film forming operability and the like, the same solvent is preferable.

  The order of mixing fullerenol, electrolyte and solvent is not particularly limited. For example, (a) fullerenol is dissolved in a solvent to prepare a fullerenol solution, and the electrolyte is dissolved in the solvent to prepare an electrolyte solution. A step of mixing a fullerenol solution and an electrolyte solution; (b) preparing a fullerenol solution by dissolving fullerenol in a solvent; and (c) preparing an electrolyte solution by dissolving the electrolyte in a solvent. The step of adding fullerenol to the electrolyte solution; or (d) fullerenol, electrolyte and solvent may be mixed at the same time. However, when fullerenol is added to the electrolyte solution as it is, the fullerenol adheres to the electrolyte surface and becomes a viscous solution as a whole, so that it is difficult to completely dissolve the fullerenol. For this reason, it is preferable to mix fullerenol with an electrolyte or an electrolyte solution in a solution state. Further, as described above, since the electrolyte is also preferably mixed in the form of a solution, (a) and (a) are preferred, and (a) is most preferred. In this step (A), since the aprotic polar solvent can dissolve both fullerenol and the electrolyte, both fullerenol and the electrolyte can be mixed well even in the absence of a base. For this reason, it is not necessary to use a base in the fourth method of the present invention.

  Next, at a process (B), it shape | molds into a film | membrane using the fullerenol-electrolyte liquid mixture (2) obtained at the said process (A). At this time, the film forming conditions are not particularly limited as long as the electrolyte film having a desired thickness as described above can be obtained. Specifically, the thickness after drying the fullerenol-electrolyte mixed solution (2) on a sheet such as a glass sheet, a polyester sheet such as a PTFE (polytetrafluoroethylene) sheet, or a PET (polyethylene terephthalate) sheet. Is applied to a preferable thickness of the electrolyte membrane as described above, and is dried under normal pressure or reduced pressure in a vacuum dryer. The drying temperature is selected according to the solvent used. For example, in the case of a solvent having a boiling point of less than 60 ° C., the preferred drying temperature is 10 to 20 ° C .; in the case of a solvent having a boiling point of 60 ° C. or more and less than 100 ° C., the preferred drying temperature is 20 to 40 ° C .; In the case of a solvent having a temperature not lower than 150 ° C. and lower than 150 ° C., a preferable drying temperature is 40 to 80 ° C .; in the case of a solvent not lower than 150 ° C. and lower than 300 ° C., the preferable drying temperature is 80 to 150 ° C. Moreover, although the time which drying requires can be suitably selected according to the kind etc. of solvent, Preferably it is 4 to 24 hours, More preferably, it is 6 to 20 hours. When a plurality of solvents having different boiling points are used, drying at a low temperature may be performed until a component having a low boiling point volatilizes, and then drying at a high temperature may be performed to volatilize a component having a higher boiling point.

  In addition, after the drying step, in order to finally remove the solvent remaining in the film, a step of performing drying again after washing the film in a large excess of pure water may be added. In this case, the drying process conditions for the second time are not particularly limited as long as the remaining solvent can be sufficiently removed. For example, drying is performed in a temperature range of 80 ° C. to 120 ° C. for 2 to 8 hours under vacuum. Is preferably performed.

  According to the second, third and fourth methods of the present invention as described above, fullerenol is uniformly dispersed in the electrolyte membrane in a predetermined amount (1 to 50% by mass with respect to the electrolyte) as described above. The electrolyte membrane can be manufactured easily and without the need for special equipment, complicated operations, or dedicated equipment.

  In addition, the electrolyte membrane of the present invention or produced by the method of the present invention has a significantly improved proton conductivity of the electrolyte membrane due to the presence of a specific amount of fullerenol, particularly under relatively high humidity conditions. Can significantly improve proton conductivity. For this reason, the electrolyte membrane of the present invention is particularly advantageous in terms of cost and material selection because it can exhibit sufficient proton conductivity even when a hydrocarbon-based electrolyte is used as the electrolyte. Furthermore, the electrolyte membrane to which fullerenol of the present invention is added significantly suppresses / prevents permeation of fuel gas and oxidant gas, particularly oxygen which is oxidant gas. For this reason, according to the electrolyte membrane of the present invention, it is possible to significantly suppress / prevent oxygen gas cross-leakage from the cathode side to the anode side through the membrane, thereby significantly reducing electrolyte deterioration in the electrolyte membrane and the catalyst layer. It can be suppressed / prevented.

  Therefore, the fuel cell having the electrolyte membrane of the present invention is expected to achieve high power generation efficiency. Therefore, a fifth aspect of the present invention provides an electrolyte membrane-electrode assembly having an electrolyte membrane of the present invention or produced by the method of the present invention. The sixth aspect of the present invention provides a fuel cell using the electrolyte membrane-electrode assembly of the present invention.

  Hereinafter, the fifth and sixth aspects of the present invention will be described in detail. Although preferred embodiments are described below, the present invention is characterized by an electrolyte membrane, and members or methods known in the art are the same except that the electrolyte membrane of the present invention is used in an MEA or a fuel cell. Can be applied.

  Hereinafter, a preferred method for producing the MEA of the present invention by the transfer method using the electrolyte membrane according to the present invention will be described in detail.

  First, a catalyst ink is prepared, and this catalyst ink is applied onto a transfer mount and dried to obtain a transfer sheet having a catalyst layer formed on the transfer mount. Next, by sandwiching the electrolyte membrane according to the present invention between the two transfer sheets (for anode and cathode), performing hot pressing on the laminated layer, and peeling off the transfer mount, the catalyst layer and the electrolyte membrane An MEA consisting of can be obtained.

  The catalyst ink used in the above method includes a solvent, an electrolyte, and a catalyst component. The catalyst component used in the cathode catalyst layer is not particularly limited as long as it has a catalytic action for the oxygen reduction reaction, and a known catalyst can be used in the same manner. Further, the catalyst component used in the anode catalyst layer is not particularly limited as long as it has a catalytic action for the oxidation reaction of hydrogen, and a known catalyst can be used in the same manner. Specifically, selected from platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and alloys thereof, and the like Is done. Among these, those containing at least platinum are preferably used in order to improve catalyst activity, poisoning resistance to carbon monoxide and the like, heat resistance, and the like. The composition of the alloy is preferably 30 to 90 atomic% for platinum and 10 to 70 atomic% for the metal to be alloyed, depending on the type of metal to be alloyed. The composition of the alloy when the alloy is used as the cathode catalyst varies depending on the type of metal to be alloyed and can be appropriately selected by those skilled in the art, but platinum is 30 to 90 atomic%, and other metals to be alloyed are 10 to 70. It is preferable to use atomic%. In general, an alloy is a generic term for a metal element having one or more metal elements or non-metal elements added and having metallic properties. The alloy structure consists of a eutectic alloy, which is a mixture of the component elements as separate crystals, a component element completely melted into a solid solution, and a component element composed of an intermetallic compound or a compound of a metal and a nonmetal. There is what is formed, and any may be used in the present application. At this time, the catalyst component used for the cathode catalyst layer and the catalyst component used for the anode catalyst layer can be appropriately selected from the above. In the following description, unless otherwise specified, the description of the catalyst component for the cathode catalyst layer and the anode catalyst layer has the same definition for both, and is collectively referred to as “catalyst component”. However, the catalyst components for the cathode catalyst layer and the anode catalyst layer do not need to be the same, and are appropriately selected so as to exhibit the desired action as described above.

  The shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components can be used, but the catalyst component is preferably granular. At this time, the smaller the average particle diameter of the catalyst particles used in the catalyst ink, the higher the effective electrode area where the electrochemical reaction proceeds, which is preferable because the oxygen reduction activity is also high, but in practice the average particle diameter is too small. On the other hand, a phenomenon in which the oxygen reduction activity decreases is observed. Therefore, the average particle diameter of the catalyst particles contained in the catalyst ink is preferably 1 to 30 nm, more preferably 1.5 to 20 nm, still more preferably 2 to 10 nm, and particularly preferably 2 to 5 nm. It is preferably 1 nm or more from the viewpoint of easy loading, and preferably 30 nm or less from the viewpoint of catalyst utilization. The “average particle diameter of the catalyst particles” in the present invention is the average value of the particle diameter of the catalyst component determined from the crystallite diameter or transmission electron microscope image determined from the half width of the diffraction peak of the catalyst component in X-ray diffraction. Can be measured.

  In the present invention, the catalyst particles described above are included in the catalyst ink as an electrode catalyst supported on a conductive carrier.

  The conductive carrier may have any specific surface area for supporting the catalyst particles in a desired dispersed state and has sufficient electronic conductivity as a current collector. The main component is carbon. Preferably there is. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. In the present invention, “the main component is carbon” refers to containing a carbon atom as a main component, and is a concept including both a carbon atom only and a substantially carbon atom. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. In addition, being substantially composed of carbon atoms means that mixing of impurities of about 2 to 3% by mass or less is allowed.

The BET specific surface area of the conductive carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m ² / g, more preferably 80 to 1200 m ² / g. Is good. When the specific surface area of the conductive support is within this range, the balance between the dispersibility of the catalyst component on the conductive support and the effective utilization rate of the catalyst component can be appropriately controlled.

  Further, the size of the conductive carrier is not particularly limited, but from the viewpoint of controlling the ease of loading, the catalyst utilization, and the thickness of the catalyst layer within an appropriate range, the average particle size is 5 to 200 nm, The thickness is preferably about 10 to 100 nm.

  In the electrode catalyst in which the catalyst component is supported on the conductive support, the supported amount of the catalyst component is preferably 10 to 80% by mass, more preferably 30 to 70% by mass with respect to the total amount of the electrode catalyst. Good. If the loading amount exceeds 80% by mass, the degree of dispersion of the catalyst component on the conductive support is lowered, and although the loading amount is increased, the improvement in power generation performance is small and the economic advantage may be lowered. On the other hand, if the loading amount is less than 10% by mass, the catalytic activity per unit mass is lowered, and a large amount of electrode catalyst is required to obtain the desired power generation performance, which is not preferable. The amount of the catalyst component supported can be examined by inductively coupled plasma emission spectroscopy (ICP).

  The cathode catalyst layer / anode catalyst layer (hereinafter also simply referred to as “catalyst layer”) of the present invention contains a polymer electrolyte in addition to the electrode catalyst. The polymer electrolyte is not particularly limited, and the same polymer electrolyte as that used for the electrolyte membrane can be used. The polymer electrolyte used for the electrolyte membrane and the polymer electrolyte used for each catalyst layer may be the same or different from the viewpoint of improving the adhesion between each catalyst layer and the electrolyte membrane. It is preferable to use the same one.

  The catalyst component can be supported on the conductive carrier by a known method. For example, known methods such as impregnation method, liquid phase reduction support method, evaporation to dryness method, colloid adsorption method, spray pyrolysis method, reverse micelle (microemulsion method) can be used. Alternatively, a commercially available electrode catalyst may be used.

  In the method of the present invention, the catalyst layer is formed by applying a catalyst ink composed of the electrode catalyst, the polymer electrolyte, and the solvent as described above to the transfer mount. In this case, the solvent is not particularly limited, and usual solvents used for forming the catalyst layer can be used in the same manner. Specifically, water, lower alcohols such as cyclohexanol, ethanol and 2-propanol can be used. Also, the amount of solvent used is not particularly limited, and the same amount as known can be used. In the catalyst ink, the electrode catalyst has a desired action, that is, hydrogen oxidation reaction (anode side) and oxygen reduction reaction. Any amount may be used as long as it can sufficiently exert the action of catalyzing (cathode side). It is preferable that the electrode catalyst is present in the catalyst ink in an amount of 5 to 30% by mass, more preferably 9 to 20% by mass.

  The catalyst ink of the present invention may contain a thickener. The use of a thickener is effective when the catalyst ink cannot be successfully applied onto a transfer mount. The thickener that can be used in this case is not particularly limited, and a known thickener can be used. Examples thereof include glycerin, ethylene glycol (EG), polyvinyl alcohol (PVA), and propylene glycol (PG). The amount of the thickener added when the thickener is used is not particularly limited as long as it does not interfere with the above effect of the present invention, but is preferably 5 to 20 with respect to the total mass of the catalyst ink. % By mass.

  The catalyst ink of the present invention is not particularly limited in its preparation method as long as an electrode catalyst, an electrolyte and a solvent, and if necessary, a water-repellent polymer and / or a thickener are appropriately mixed. For example, a catalyst ink can be prepared by adding an electrolyte to a polar solvent, heating and stirring the mixed solution to dissolve the electrolyte in the polar solvent, and then adding an electrode catalyst thereto. Alternatively, after the electrolyte is once dispersed / suspended in a solvent, the dispersion / suspension may be mixed with an electrode catalyst to prepare a catalyst ink. In addition, a commercially available electrolyte solution in which the electrolyte is previously prepared in the other solvent (for example, Nafion (registered trademark) manufactured by DuPont: Nafion (registered trademark) dispersed in 1-propanol at a concentration of 5 wt% / The suspension) may be used in the above method as it is.

  Each catalyst layer is formed by applying the catalyst ink as described above onto a transfer mount. At this time, the conditions for forming the cathode / anode catalyst layer on the polymer electrolyte membrane are not particularly limited, and can be used in the same manner as known methods or appropriately modified. For example, the catalyst ink is applied onto the polymer electrolyte membrane so that the thickness after drying is 5 to 20 μm, and is 25 to 150 ° C., more preferably 60 to 120 ° C. in a vacuum dryer or under reduced pressure. And drying for 5 to 30 minutes, more preferably for 10 to 20 minutes. In addition, in the said process, when the thickness of a catalyst layer is not enough, the said application | coating and drying process is repeated until it becomes desired thickness.

  In the above method, the transfer mount is not particularly limited, and a known sheet such as a polyester sheet such as a PTFE (polytetrafluoroethylene) sheet or a PET (polyethylene terephthalate) sheet can be used. The transfer mount is appropriately selected according to the type of catalyst ink to be used (particularly, a conductive carrier such as carbon in the ink). In the above step, the thickness of the catalyst layer is not particularly limited as long as it can sufficiently exhibit the catalytic action of the hydrogen oxidation reaction (anode side) and the oxygen reduction reaction (cathode side). Can be used. Specifically, the thickness of the catalyst layer is 1 to 30 μm, more preferably 1 to 20 μm. The method for applying the catalyst ink onto the transfer mount is not particularly limited, and a known method such as a screen printing method, a deposition method, or a spray method can be similarly applied. Also, the drying conditions of the applied catalyst layer are not particularly limited as long as the polar solvent can be completely removed from the catalyst layer. Specifically, the catalyst ink coating layer (catalyst layer) is dried in a vacuum dryer at room temperature to 100 ° C., more preferably 50 to 80 ° C., for 30 to 60 minutes. At this time, if the thickness of the catalyst layer is not sufficient, the coating and drying process is repeated until a desired thickness is obtained.

  Next, after sandwiching the two catalyst layer electrolyte membranes thus produced, hot pressing is performed on the laminate. At this time, the hot press conditions are not particularly limited as long as the catalyst layer and the electrolyte membrane can be joined sufficiently closely, but are 100 to 200 ° C., more preferably 110 to 170 ° C., and 1 to 5 MPa with respect to the electrode surface. It is preferable to carry out at a pressing pressure of. Thereby, the bondability between the polymer electrolyte membrane and the catalyst layer can be enhanced. After performing hot pressing, an MEA composed of a catalyst layer and a polymer electrolyte membrane can be obtained by removing the transfer mount.

  In the above description, the method of forming the anode / cathode catalyst layer on the electrolyte membrane by the transfer method has been described. However, the MEA of the present invention can be applied to other methods such as a direct coating method in which the catalyst ink is directly printed on the electrolyte membrane. May be manufactured. Specifically, the catalyst ink as described above is applied on the electrolyte membrane of the present invention to form each catalyst layer. At this time, the conditions for forming the cathode / anode catalyst layer on the electrolyte membrane are not particularly limited, and a known method can be used in the same manner or with appropriate modification. For example, the catalyst ink is applied onto the polymer electrolyte membrane so that the thickness after drying is 5 to 20 μm, and is 25 to 150 ° C., more preferably 60 to 120 ° C. in a vacuum dryer or under reduced pressure. And drying for 5 to 30 minutes, more preferably for 10 to 20 minutes. In addition, in the said process, when the thickness of a catalyst layer is not enough, the said application | coating and drying process is repeated until it becomes desired thickness.

  Note that the MEA according to the present invention may generally further include a gas diffusion layer, as will be described in detail below. In this case, the gas diffusion layer is obtained by peeling off the transfer mount in the above method. It is preferable that the joined body is further sandwiched between gas diffusion layers to further join each catalyst layer after joining the catalyst layer and the electrolyte membrane. Alternatively, after the catalyst layer is formed on the surface of the gas diffusion layer in advance to produce the catalyst layer-gas diffusion layer assembly, the electrolyte membrane is heated with this catalyst layer-gas diffusion layer assembly in the same manner as described above. It is also preferable to sandwich and join by pressing.

  At this time, the gas diffusion layer used in the MEA is not particularly limited, and a known one can be used in the same manner. For example, the conductive and porous properties such as carbon woven fabric, paper-like paper body, felt, and non-woven fabric are used. The thing which uses the sheet-like material which has as a base material etc. are mentioned. The thickness of the substrate may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer, but may be about 30 to 500 μm. If the thickness is less than 30 μm, sufficient mechanical strength or the like may not be obtained, and if it exceeds 500 μm, the distance through which gas or water permeates is undesirably increased.

  The method for forming the catalyst layer on the surface of the gas diffusion layer is not particularly limited, and known methods such as a screen printing method, a deposition method, and a spray method can be similarly applied. Moreover, the formation conditions in particular on the gas diffusion layer surface of a catalyst layer are not restrict | limited, The conditions similar to the past can be applied with the above specific formation methods.

  The gas diffusion layer preferably contains a water repellent in the base material for the purpose of further improving water repellency and preventing a flooding phenomenon. Although it does not specifically limit as said water repellent, It is fluorine-type, such as a polytetrafluoroethylene (PTFE), a polyvinylidene fluoride (PVDF), a polyhexafluoropropylene, a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Examples thereof include polymer materials, polypropylene, and polyethylene.

  Moreover, in order to improve water repellency more, the said gas diffusion layer may have a carbon particle layer which consists of an aggregate | assembly of the carbon particle containing a water repellent on the said base material.

  The carbon particles are not particularly limited, and may be conventional ones such as carbon black, graphite, and expanded graphite. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferred because of their excellent electron conductivity and large specific surface area. The particle size of the carbon particles is preferably about 10 to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, it becomes possible to improve contact property with a catalyst layer.

  Examples of the water repellent used for the carbon particle layer include the same water repellents as those described above used for the substrate. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.

  In the carbon particle layer, the mixing ratio of the carbon particles to the water repellent may be insufficient to obtain water repellency as expected when there are too many carbon particles. If there are too many water repellents, sufficient electron conductivity may be obtained. There is a risk that it will not be obtained. Considering these, the mixing ratio of the carbon particles and the water repellent in the carbon particle layer is preferably about 90:10 to 40:60 (carbon particles: water repellent). .

  The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer.

  When a water repellent is contained in the gas diffusion layer, a general water repellent treatment method may be used. For example, after immersing the base material used for a gas diffusion layer in the dispersion liquid of a water repellent agent, the method of heat-drying with oven etc. is mentioned.

  When forming a carbon particle layer on a substrate in a gas diffusion layer, the carbon particles, water repellent, etc. are in a solvent such as water, alcohol solvents such as perfluorobenzene, dichloropentafluoropropane, methanol, ethanol, etc. A slurry is prepared by dispersing in a slurry, and the slurry is applied on a substrate and dried, or the slurry is dried and pulverized to form a powder, and this is applied to the gas diffusion layer. Use it. Then, it is preferable to heat-process at about 250-400 degreeC using a muffle furnace or a baking furnace.

  In addition, the manufacturing method of the joined body including the catalyst layer, the electrolyte membrane, and preferably the gas diffusion layer is not limited to the method described above. That is, a method in which a catalyst ink is applied and dried on an electrolyte membrane, followed by hot pressing, the catalyst layer is joined to a solid electrolyte membrane, and the obtained joined body is sandwiched between gas diffusion layers to form MEA; Ink may be applied to the gas diffusion layer and dried to form a catalyst layer, which may be bonded to the electrolyte membrane by hot pressing, or any other known technique may be used as appropriate.

  The electrolyte membrane-electrode assembly of the present invention and the electrolyte membrane-electrode assembly produced by the method of the present invention are included in the corrosion of the carbon support used as the catalyst support and the electrolyte membrane-electrode assembly as described above. It is possible to suppress deterioration of the electrolyte component. In addition, by providing a gasket layer, it is possible to easily determine the area and arrangement of the catalyst layer, and it is not necessary to accurately align each catalyst layer in advance, so industrial mass production is considered. This is highly desirable. Therefore, by using such an electrolyte membrane-electrode assembly, it is possible to provide a highly reliable fuel cell that has a simple manufacturing process and excellent durability.

  The type of the fuel cell is not particularly limited. In the above description, the polymer electrolyte fuel cell has been described as an example, but in addition to this, a representative example is an alkaline fuel cell and a phosphoric acid fuel cell. Examples thereof include an acid electrolyte fuel cell, a direct methanol fuel cell, and a micro fuel cell. Among them, a polymer electrolyte fuel cell is preferable because it is small in size, and can achieve high density and high output. The fuel cell is useful as a stationary power source in addition to a power source for a moving body such as a vehicle in which a mounting space is limited. However, the fuel cell is particularly useful for an automobile application in which system start / stop and output fluctuation frequently occur. It can be particularly preferably used.

  The polymer electrolyte fuel cell is useful not only as a stationary power source but also as a power source for a moving body such as an automobile having a limited mounting space. In particular, moving bodies such as automobiles that are susceptible to corrosion of the carbon support due to the high output voltage required after a relatively long shutdown, and deterioration of the polymer electrolyte due to the high output voltage being taken out during operation. It is particularly preferred to be used as a power source.

  The configuration of the fuel cell is not particularly limited, and a conventionally known technique may be used as appropriate. Generally, the fuel cell has a structure in which an MEA is sandwiched between separators.

  The separator can be used without limitation as long as it is conventionally known, such as those made of carbon such as dense carbon graphite and a carbon plate, and those made of metal such as stainless steel. The separator has a function of separating air and fuel gas, and a channel groove for securing the channel may be formed. The thickness and size of the separator, the shape of the flow channel, and the like are not particularly limited, and may be appropriately determined in consideration of the output characteristics of the obtained fuel cell.

  Further, in order to prevent the gas supplied to each catalyst layer from leaking to the outside, a gas seal portion may be further provided at a portion where the catalyst layer is not formed on the gasket layer. Examples of the material constituting the gas seal portion include rubber materials such as fluoro rubber, silicon rubber, ethylene propylene rubber (EPDM), polyisobutylene rubber, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoro. Fluorine polymer materials such as propylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and thermoplastic resins such as polyolefin and polyester. The thickness of the gas seal portion may be 2 mm to 50 μm, preferably about 1 mm to 100 μm.

  Furthermore, a stack in which a plurality of MEAs are stacked via a separator and connected in series may be formed so that the fuel cell can obtain a desired voltage or the like. The shape of the fuel cell is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

(Example 1-1)
25 mg of fullerenol (manufactured by Frontier Carbon Co., Ltd., nanom spectra HX10-S) was dissolved in 20 ml of dimethyl sulfoxide (DMSO) and heated to 80 ° C. for 30 minutes for complete dissolution. To this fullerenol solution, 500 mg of sulfonated polyethersulfone (S-PES) as an electrolyte was added and stirred at 80 ° C. for 2 hours to obtain a fullerene-electrolyte mixture solution in which fullerenol and S-PES were uniformly dissolved. Prepared. This fullerene-electrolyte mixed solution was spread on a 100 cm ² glass plate, heated in an oven at 80 ° C. for 12 hours, and dried to obtain an electrolyte membrane having a uniform thickness of 45 μm. The content of fullerenol in the electrolyte membrane thus obtained is 5% by mass with respect to the electrolyte.

  After the membrane was swollen with water and peeled, the four sides of the membrane were fixed with a frame. After dipping in water overnight to remove the fullerenol adhering to the electrolyte membrane surface and the remaining trace amount of solvent, drying was performed at 100 ° C. for 5 hours in a vacuum dryer. This was subjected to a performance test, and the results are shown in Table 1 below.

  The proton conductivity in Table 1 was evaluated according to the following method.

"Proton conductivity evaluation method"
Using an electrochemical impedance measuring device (Solartron 1280Z), impedance was measured in the region of amplitude 5 mV, frequency 100,000 to 10 Hz, 10 steps / decade, and the proton conductivity of the solid polymer electrolyte membrane was evaluated. In this case, a small opening specification (width 30 mm × length 15 mm) cell was used.

  In the above measurement, the sample is supported in an electrically insulated sealed container, and the cell temperature is changed from room temperature to 80 ° C. by a temperature controller in a water vapor atmosphere (30 to 95% RH). The impedance was measured three times after 30 minutes had passed since the thermostatic chamber was in a steady state, and the averages are shown in Tables 1 and 2. Moreover, in Table 1 and Table 2, the measured value on 80 degreeC30% RH (relative humidity), 60% RH, and 95% RH conditions is shown as a typical value.

(Example 1-2)
In Example 1-1, an electrolyte was prepared in the same manner as in Example 1 except that a fullerenol solution obtained by dissolving 50 mg of fullerenol (manufactured by Frontier Carbon Co., Ltd., nanom spectra HX10-S) in 20 ml of DMSO was used. A membrane was produced. In addition, content of fullerenol in the electrolyte membrane obtained in this way is 10 mass% with respect to electrolyte.

  Further, the proton conductivity of the obtained electrolyte membrane was evaluated in the same manner as in the method described in Example 1-1. The results are shown in Table 1 below.

(Example 1-3)
In Example 1-1, an electrolyte was used in the same manner as in Example 1 except that a fullerenol solution containing 500 mg of fullerenol (manufactured by Frontier Carbon Corporation, nanom spectra HX10-S) dissolved in 20 ml of DMSO was used. A membrane was produced. The content of fullerenol in the electrolyte membrane thus obtained is 50% by mass with respect to the electrolyte.

(Comparative Example 1-1)
A uniform electrolyte solution was obtained by adding 500 mg of sulfonated polyethersulfone (S-PES) as an electrolyte to 20 ml of DMSO and stirring at 80 ° C. for 2 hours. This was spread on a 100 cm ² glass plate, heated in an oven at 80 ° C. for 12 hours, and dried to obtain an electrolyte membrane having a uniform thickness of 45 μm. This was swollen with water and peeled, and then subjected to a performance test in the same manner as described in Example 1-1. The results are shown in Table 1 below.

  As shown in Table 1 above, it is shown that the proton conductivity of the electrolyte membrane of the present invention is significantly improved by adding fullerenol.

(Example 1-4)
5 g of propanol is added to 5 g of a 20% dispersion solution of Nafion (manufactured by DuPont, DE2029 (registered trademark)) as an electrolyte in a water / propanol mixture (water: propanol mixture ratio = 1: 2), followed by stirring and desorption. After foaming, it was developed on a 100 cm ² glass plate and dried overnight at room temperature to obtain an electrolyte membrane having a thickness of 60 μm. This was swollen and peeled with water, and then vacuum-dried to obtain a film.

  Separately, by adding fullerenol to a 1 mol / L sodium hydroxide aqueous solution (pH: 14) so that the content is 5% by mass, and stirring, a basic fullerenol solution as a uniform brown solution is obtained. Prepared.

  The membrane produced above was impregnated in the basic fullerenol solution at 25 ° C. for 1 hour. When the basic fullerenol solution sufficiently penetrated into the membrane, the four sides of the membrane were fixed with a frame. After being immersed in this basic fullerenol solution at 25 ° C. overnight, it was taken out and immersed in pure water overnight to remove excess fullerenol adhering to the film surface. Further, this membrane was immersed in 1 mol / L hydrochloric acid at 25 ° C. overnight, and then immersed in pure water at 25 ° C. overnight to remove excess hydrochloric acid, thereby obtaining the electrolyte membrane of the present invention. The content of fullerenol in the electrolyte membrane thus obtained is 3.6% by mass with respect to the electrolyte.

  The electrolyte membrane thus obtained was subjected to a performance test in the same manner as described in Example 1-1. The results are shown in Table 2 below.

(Comparative Example 1-2)
In Example 1-4, an electrolyte membrane was prepared in the same manner as in Example 1-4 except that fullerenol was not used. The electrolyte membrane thus obtained was the same as the method described in Example 1-1. Similarly, it was subjected to a performance test. The results are shown in Table 2 below.

(Example 1-5)
A basic fullerenol solution as a uniform brown solution was prepared by adding fullerenol to a 1 mol / L sodium hydroxide aqueous solution (pH: 14) so as to have a mass ratio of 5% and stirring. .

  When a sulfonated polyethersulfone (S-PES) electrolyte membrane having a thickness of 30 μm is impregnated into the basic fullerenol solution prepared above at 25 ° C. for 1 hour, the basic fullerenol solution is sufficiently permeated into the membrane. The four sides of the membrane were fixed with a frame. After being immersed in this basic fullerenol solution at 25 ° C. overnight, it was taken out and immersed in pure water overnight to remove excess fullerenol adhering to the film surface. Further, this membrane was immersed in 1 mol / L hydrochloric acid at 25 ° C. overnight, and then immersed in pure water at 25 ° C. overnight to remove excess hydrochloric acid, thereby obtaining the electrolyte membrane of the present invention. The content of fullerenol in the electrolyte membrane thus obtained is 2.8% by mass with respect to the electrolyte.

  The electrolyte membrane thus obtained was subjected to a performance test in the same manner as described in Example 1-1. The results are shown in Table 2 below.

(Comparative Example 1-3)
In Example 1-5, an electrolyte membrane was prepared in the same manner as in Example 1-5 except that fullerenol was not used. The electrolyte membrane thus obtained was obtained by the method described in Example 1-1. Similarly, it was subjected to a performance test. The results are shown in Table 2 below.

  By comparing the results of Example 1-4 and Comparative Example 1-2 in Table 2 above, and Examples 1-5 and Comparative Example 1-3, the electrolyte membrane of the present invention can be obtained by adding fullerenol. It is shown that proton conductivity is significantly improved.

  A method for producing a composite electrolyte membrane containing an inorganic gel by the sol-gel method was performed as described below in Japanese Patent Application No. 2005-255604.

(Example 2-1)
1. 1. Preparation of electrolyte solution containing hydrolysis / condensation reaction catalyst 1-1. Preparation of electrolyte solution (without catalyst) While stirring 20 ml of NMP (N-methylpyrrolidone), which is a high boiling point solvent, poly (4-phenoxybenzoyl-1,4-phenylene) (hereinafter, A small amount of 5.0 g (also simply referred to as S-PPBP) was added little by little (charging speed; about 0.1 to 10 g / min with respect to 10 ml of solvent), and the whole amount was added, followed by stirring at room temperature for 30 minutes or more. The mixture was further stirred for 12 hours at a high temperature of 80 ° C. by heating with a heater, and then returned to room temperature by natural cooling, thereby preparing a 25 wt / v% S-PPBP-containing NMP solution as an electrolyte-containing solution.

  Here, the input rate of S-PPBP was 0.5 g / min with respect to 10 ml of the solvent.

1-2. Preparation of Electrolyte Solution (Including Catalyst) While stirring the 25 wt / v% S-PPBP-containing NMP solution, the 25 wt / v% S-PPBP-containing NMP solution was mixed with water (neutral as a hydrolysis / condensation reaction catalyst). (Catalyst) was slowly added dropwise, followed by stirring for 0.5 hour to prepare an NMP aqueous solution containing about 25 wt / v% S-PPBP as an electrolyte-containing solution containing a hydrolysis / condensation reaction catalyst.

  Here, the amount of water added was 10 mol with respect to TEOS (also simply referred to as tetraethoxysilane) which is an inorganic precursor described later. Moreover, the dripping speed | rate of water was dripped slowly at the speed | rate of 0.01 ml / min with respect to 10 ml of 25 wt / v% S-PPBP containing NMP solution.

2. Preparation of inorganic precursor solution While stirring 1 g of NMP which is the same as the high boiling point solvent used in 1 above as a solvent, 0.1 g of TEOS which is an inorganic precursor is added to the NMP solvent and stirred for 1 hour or more to dissolve. As a result, a 9.1 wtwt / v% TEOS-containing NMP solution was prepared as an inorganic precursor-containing solution having a predetermined concentration.

  Here, the input rate of TEOS was 0.1 g / min with respect to 1 g of NMP solvent.

3. Preparation of Composite Electrolyte-Containing Solution To the S-PPBP-containing NMP aqueous solution obtained in 1-2 above, the 9.1 wt / v% TEOS-containing NMP solution obtained in 2 above prepared to a predetermined concentration is added at room temperature ( The solution containing the composite electrolyte was prepared by stirring dropwise for 12 hours or more at room temperature (room temperature) even after the entire amount was dropped. Here, the dropping rate of the TEOS-containing NMP solution was 0.1 ml / min per 10 ml of the electrolyte-containing solution.

4). Formation of electrolyte membrane 4-1. Application of Composite Electrolyte-Containing Solution Using the automatic coating apparatus, the composite electrolyte-containing solution prepared in 3 above was applied to a 50 μm thick Teflon film substrate to form a coating film (wet state). The coating treatment was performed at normal temperature and normal pressure in an air atmosphere.

4-2. Heat treatment of the coating film (wet state) The coating film (wet state) formed by the above 4-1 was heat-treated at 80 ° C. for at least 12 hours using a dryer to obtain a film (dry state). The heat treatment was performed under atmospheric pressure and normal pressure.

4-3. Pure water stripping of the membrane (dry state) The membrane obtained by 4-2 is immersed in pure water for 5 minutes to swell so that the membrane fixed to the substrate does not break at room temperature (room temperature). The film was peeled from the base material so that no tension was applied. Again, this was carried out at room temperature and atmospheric pressure in an air atmosphere.

4-4. Drying of the membrane The peeled membrane containing pure water was placed in a drier and vacuum dried at room temperature (room temperature) for 3 hours or more to form a desired composite electrolyte membrane.

(Comparative Example 2-1)
1. Preparation of Electrolyte Solution While stirring 20 ml of NMP, which is a high boiling point solvent, 5.0 g of S-PPBP as an electrolyte was added to the NMP solvent little by little, and after the entire amount was added, it was stirred at room temperature for 30 minutes or more. Thereafter, the mixture was further stirred for 12 hours at 80 ° C. by heating with a heater, and then returned to room temperature by natural cooling, thereby preparing a 25 wt / v% S-PPBP-containing NMP solution as an electrolyte-containing solution.

  Here, the input rate of S-PPBP was 0.5 g / min with respect to 10 ml of the solvent.

2. Formation of electrolyte membrane 2-1. Application of Electrolyte-Containing Solution Using the automatic coating apparatus, the electrolyte-containing solution prepared in 1 above was applied to a 50 μm thick polyethylene naphthalate substrate to form a coating film (wet state). The coating treatment was performed at normal temperature and normal pressure in an air atmosphere.

2-2. Heat Treatment of Coating Film (Wet State) A film (dry state) was obtained by heat-treating the coating film (wet state) formed by 2-1 above at 80 ° C. for at least 12 hours using a dryer. The heat treatment was performed under atmospheric pressure and normal pressure.

2-3. Pure water stripping of the membrane (dry state) The membrane obtained by 2-2 is immersed in pure water for 5 minutes and swollen so that the membrane fixed to the substrate does not break at room temperature (room temperature). The film was peeled from the base material so that no tension was applied. Again, this was carried out at room temperature and atmospheric pressure in an air atmosphere.

2-4. Drying of the membrane The peeled membrane containing pure water was put in a vacuum dryer and vacuum dried at room temperature (room temperature) for 3 hours or more to form a desired composite electrolyte membrane.

(Example 3-1)
25 mg of fullerenol (manufactured by Frontier Carbon Co., Ltd., nanom spectra HX10-S) was dissolved in 20 ml of dimethyl sulfoxide (DMSO) and heated to 80 ° C. for 30 minutes for complete dissolution. To this fullerenol solution, 500 mg of sulfonated polyethersulfone (S-PES) as an electrolyte is added and stirred at 80 ° C. for 2 hours, so that fullerenol and sulfonated polyethersulfone (S-PES) are uniformly dissolved. A fullerene-electrolyte mixture was prepared. This fullerene-electrolyte mixed solution was spread on a 100 cm ² glass plate, heated in an oven at 80 ° C. for 12 hours, and dried to obtain an electrolyte membrane having a uniform thickness of 45 μm. The content of fullerenol in the electrolyte membrane thus obtained is 5% by mass with respect to the electrolyte.

  After the membrane was swollen with water and peeled, the four sides of the membrane were fixed with a frame. After dipping in water overnight to remove the fullerenol adhering to the electrolyte membrane surface and the remaining trace amount of solvent, drying was performed at 100 ° C. for 5 hours in a vacuum dryer.

(Example 4-1)
100 mg of fullerenol (Nanom Spectra HX10-S, manufactured by Frontier Carbon Co., Ltd.) was dissolved in 20 ml of dimethyl sulfoxide (DMSO) and heated to 80 ° C. for 30 minutes to completely dissolve it. To this fullerenol solution, 500 mg of sulfonated polyethersulfone (S-PES) as an electrolyte was added and stirred at 80 ° C. for 2 hours to obtain a fullerene-electrolyte mixture solution in which fullerenol and S-PES were uniformly dissolved. Prepared. This fullerene-electrolyte mixed solution was spread on a 100 cm ² glass plate, heated in an oven at 80 ° C. for 12 hours, and dried to obtain an electrolyte membrane having a uniform thickness of 45 μm. The content of fullerenol in the electrolyte membrane thus obtained is 20% by mass with respect to the electrolyte.

  After the membrane was swollen with water and peeled, the four sides of the membrane were fixed with a frame. After dipping in water overnight to remove the fullerenol adhering to the electrolyte membrane surface and the remaining trace amount of solvent, drying was performed at 100 ° C. for 5 hours in a vacuum dryer.

(Comparative Example 2-2)
An electrolyte solution in which S-PES was uniformly dissolved was prepared by adding 500 mg of sulfonated polyethersulfone (S-PES) as an electrolyte to 20 ml of dimethyl sulfoxide (DMSO) and stirring at 80 ° C. for 2 hours. . This electrolyte solution was spread on a 100 cm ² glass plate, heated in an oven at 80 ° C. for 12 hours, and dried to obtain an electrolyte membrane having a uniform thickness of 45 μm.

  After the membrane was swollen with water and peeled, the four sides of the membrane were fixed with a frame. It was immersed in water overnight and dried at 100 ° C. for 5 hours in a vacuum dryer.

  Regarding the performance evaluation of the electrolyte membrane, both Examples and Comparative Examples were performed as follows.

"Proton conductivity measurement"
The impedance was measured by an alternating current method using a Solartron impedance analyzer. A frequency sweep with an amplitude of 10 mV and 10 k to 100 kHz was performed, and proton conductivity was evaluated using the obtained colle-core plot. In addition, the small opening specification (width 30mm x length 15mm) cell was used for evaluation.

  In the above measurement, the sample is supported in an electrically insulated sealed container, and the cell temperature is changed from room temperature to 80 ° C. by a temperature controller in a water vapor atmosphere (30 to 95% RH). The impedance was measured three times after 30 minutes had elapsed since the thermostatic chamber was in a steady state. Proton conductivity (S / cm) is shown in FIGS.

"Moisture content, diffusion coefficient"
The water content and diffusion coefficient were measured by a gravimetric method using a water adsorption measuring device IGA Sorp manufactured by HIDEN. After the electrolyte membrane of about 2 cm ^{2 is} dried for 2 hours, the humidity is changed to 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95% RH at 80 ° C. Amount) is measured in real time with an electronic balance. The water content was defined as the number of water molecules per sulfonic acid group (H ₂ O / SO ₃ H) on an ion exchange capacity basis. The calculation method of the diffusion coefficient was performed according to “Equation 1” described in the best mode of the invention. The results of calculating the water content and the water diffusion coefficient from this time change are shown in FIGS. 1, 2, 4, 5, 7, and 8.

"Power generation evaluation"
<Cathode catalyst ink> Fine particles of Pt-supported carbon (platinum supported amount: 50% by mass) in a commercially available Nafion solution (Aldrich 5% by mass solution), and the mass ratio of carbon to Nafion is carbon: Nafion = 1: 0. After mixing so as to be 0.8, a cathode catalyst ink was produced in a homogenizer (pulverizer) for about 3 hours.

  <Anode catalyst ink> An anode catalyst ink was prepared in the same manner as the cathode catalyst ink.

"Catalyst layer transfer sheet preparation"
The ink prepared as described above was applied onto a Teflon sheet used as a mount using a screen printer to prepare a catalyst layer transfer sheet for cathode and anode. As the mount, a PET (polyethylene terephthalate) sheet or the like is excellent in addition to the Teflon sheet. Coating and drying were repeated until the Pt carrying amount reached 0.4 mg / cm ² to prepare a catalyst layer transfer sheet having a predetermined platinum amount.

"Transfer of catalyst layer"
When the catalyst layer surface of the cathode and anode catalyst layer transfer sheets prepared as described above is sprayed and infiltrated with ethanol, and the catalyst layer surface is dried, the electrolyte membranes prepared with these transfer sheets are sandwiched, 130 Hot pressing was performed at a temperature of 6.5 MPa and a holding time of 10 minutes. The reason for infiltrating with ethanol is to make the catalyst layer and membrane electrolyte flexible and to facilitate the transfer of the catalyst layer.

  After cooling, the mount of the transfer sheet was peeled off to produce a membrane-catalyst layer assembly.

  In this example, a non-fluorine solid polymer electrolyte was used only for the cathode binder, and ordinary Nafion was used for the anode binder. This is because it is more convenient to use Nafion as the anode binder to make the reference electrode for CV (cyclic voltammetry) measurement. Needless to say, there is essentially no change.

"Power generation conditions"
Power generation is performed by supplying pure hydrogen to the anode and air (both atmospheric pressure) to the cathode. The power generation conditions are a cell temperature of 80 ° C., an anode gas relative humidity of 20%, a cathode gas relative humidity of 60%, a hydrogen utilization rate of 67%, and an air utilization rate of 40%. IV performance is shown in FIG.

  As is clear from the results of FIGS. 1 to 9, the composite electrolyte membranes (Examples 1 to 3) of the present invention have proton conductivity equal to or higher than that of the electrolyte membranes of Comparative Examples 1 and 2. Furthermore, it was confirmed that the diffusion coefficient could be improved more than twice while the water content increased by about 10% under a wider range of humidity conditions. In particular, as is apparent from the power generation test of FIG. 10, the electrolyte membrane of Example 1 is less susceptible to flooding on the high current density side, and the performance is improved. For this reason, when applied to applications such as fuel cell vehicles, a humidifier that humidifies hydrogen is no longer necessary, or a simple humidifier is sufficient, or the number of cells per unit area is improved. The size can be reduced.

  Since the electrolyte membrane of the present invention is excellent in proton conductivity and durability, the electrolyte membrane of the present invention is useful for MEA and further for a fuel cell having the MEA. The fuel cell has excellent durability, and can be used particularly suitably in automotive applications in which system start / stop and output fluctuations frequently occur.

It is the relationship between the diffusion coefficient concerning Example 2-1 of this invention, and humidity. It is the relationship between the moisture content and humidity concerning Example 2-1 of this invention. It is the relationship between proton conductivity and humidity concerning Example 2-1 of this invention. It is the relationship between the diffusion coefficient concerning Example 3-1 and 4-1 of this invention, and humidity. It is the relationship between the moisture content and humidity concerning Example 3-1 and 4-1 of this invention. It is the relationship between proton conductivity and humidity concerning Examples 3-1 and 4-1 of the present invention. It is a conceptual diagram of the in-plane direction in a cathode side film | membrane. It is a conceptual diagram of the film thickness direction of a membrane electrode assembly. It is an experimental result of IV performance.

Claims (5)

Fullerenol , sulfonated polyethersulfone (S-PES), PBI (polybenzimidazole), PBO (polybenzoxazole), S-PPBP (sulfonated polyphenoxybenzoylphenylene), S-PEEK (sulfonated polyetheretherketone) ), Sulfonamide type polyether sulfone, sulfonated polyether ether ketone, sulfonamide type polyether ether ketone, sulfonated crosslinked polystyrene, sulfonamide type crosslinked polystyrene, sulfonated polytrifluorostyrene, sulfonamide type polytrifluorostyrene, Sulfonated polyaryl ether ketone, sulfonamide type polyaryl ether ketone, sulfonated poly (aryl ether sulfone), sulfonamide type poly (aryl ether) Sulfone), polyimide, sulfonated polyimide, sulfonamide type polyimide, sulfonated 4-phenoxybenzoyl-1,4-phenylene, sulfonamide type 4-phenoxybenzoyl-1,4-phenylene, sulfonated polybenzimidazole, sulfonamide type Polybenzimidazole, sulfonated polyphenylene sulfide, sulfonamide type polyphenylene sulfide, sulfonated polybiphenylene sulfide, sulfonamide type polybiphenylene sulfide, sulfonated polyphenylene sulfone, sulfonamide type polyphenylene sulfone, sulfonated polyphenoxybenzoylphenylene, sulfonated polystyrene Ethylene-propylene, sulfonated polyetheretherketone, sulfonated polyphenyleneimide, polyethylene Benzimidazole - alkylsulfonic acids, and an electrolyte which is selected from the group consisting of Suruhoariru polybenzimidazole, a mixture of aprotic polar solvents, fullerenols - prepare an electrolyte mixture;
Furthermore, the manufacturing method of an electrolyte membrane including the process of shape | molding the said fullerenol -electrolyte mixed solution to a film | membrane. Dissolving fullerenol in a basic solution to prepare a basic fullerenol solution (2);
The basic fullerenol solution (2) is mixed with an electrolyte solution using an aprotic polar solvent as a solvent to prepare a fullerenol-electrolyte mixed solution (1); and further, the fullerenol-electrolyte mixed solution (1) is used as a membrane. comprising the step of forming, electrolyte membranes manufacturing method. The basic solution is an aqueous solution containing at least one selected from the group consisting of potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH ₄ OH) and lithium hydroxide (LiOH). The method of claim 2 . Wherein the aprotic polar solvent is dimethyl sulfoxide The method according to any one of claims 1-3. The method according to claim 2 or 3 , wherein the electrolyte includes a hydrocarbon-based electrolyte having a proton dissociable functional group.