WO2007046239A1

WO2007046239A1 - Electrolyte composition for fuel cell, membrane-electrode assembly for fuel cell using same, and fuel cell

Info

Publication number: WO2007046239A1
Application number: PCT/JP2006/319889
Authority: WO
Inventors: Norie Taguchi; Ryotaro Tsuji
Original assignee: Kaneka Corporation
Priority date: 2005-10-17
Filing date: 2006-10-04
Publication date: 2007-04-26
Also published as: JPWO2007046239A1

Abstract

Disclosed is a low-cost electrolyte composition for fuel cells which is excellent in adhesion to the electrolyte membrane and electrode, capable of uniformly holding a catalyst metal, and has high environmental suitability and durability. This electrolyte composition for fuel cells has high resistance to methanol, and the proton conductivity of the electrolyte does not deteriorate in this composition. Also disclosed are a low-cost membrane-electrode assembly using such an electrolyte composition for fuel cells and a low-cost fuel cell. The electrolyte composition for fuel cells contains, as indispensable components, (A) a compound having a number average molecular weight of 500-100,000 while having a functional group which can be bonded with a catalyst metal, and (B) a compound having a number average molecular weight of 50-1,000,000 while having a proton conductive functional group. The electrolyte composition may further contain (C) a carbon loaded with a catalyst metal for fuel cells to form a catalyst composition, and an electrode layer for fuel cells can be suitably formed from such a catalyst composition. The membrane-electrode assembly has a structure wherein a proton conductive electrolyte membrane is sandwiched between layers containing the electrolyte composition.

Description

Electrolyte composition for fuel cell, membrane-electrode assembly for fuel cell using the same, and fuel cell

Technical field

TECHNICAL FIELD [0001] The present invention relates to an electrolyte composition for fuel cells, a membrane-electrode assembly for fuel cells using the same, and a fuel cell.

Background art

[0002] Generally, a fuel cell has a structure in which an electrolyte membrane having proton conductivity is sandwiched between electrolytes containing a catalytic metal. A polymer electrolyte fuel cell (PEFC) that uses a polymer compound as an electrolyte membrane has the advantages of being able to operate at low temperatures and being compact and lightweight. For automobiles, homes, small portable devices, etc. Wide range of uses has been made. In particular, a direct methanol fuel cell (DMFC) that uses methanol as the fuel can be simplified in size compared to a type that uses hydrogen gas as fuel, and can be miniaturized because of its high power density.

[0003] Conventionally, as such DMFC, a technique of using a fluoric resin containing a sulfonic acid group for both an electrolyte membrane and an electrolyte used as a binder has been common. However, the use of such a fluorine-based electrolyte membrane is a cross-over in which methanol permeability is high and the methanol that cannot be consumed at the fuel electrode reaches the oxidant electrode and reacts on the oxidant electrode to generate back electromotive force. There was a problem that sufficient power generation characteristics could not be obtained due to the over phenomenon. In addition, fluorine-based resin is expensive and difficult to recycle, and there is a problem that waste disposal is also expensive.

[0004] Development of various hydrocarbon-based electrolyte membranes has been promoted as means for solving such problems peculiar to fluorocarbon resins (Patent Documents 1 to 3). However, these hydrocarbon-based electrolyte membranes have poor adhesion to the fluorine-based electrolytes used as binders for conventional catalyst layers, and therefore hydrocarbon-based electrolytes with similar compositions to the electrolyte membranes can be used as catalyst layers. Consideration of use as a binder is considered necessary. By the way, in the catalyst layer in this electrode, the diffusion of reactants' products, electron transfer, and hydrogen ion transfer occur, so the fuel, electrons, Emphasis is placed on the size of the three-phase interface that is the on-movement path of each. Since the present inventors have reduced the size of the three-phase interface when a general hydrocarbon electrolyte is used as a binder, compared to the case where a conventional fluorine-based resin is used as a binder. The inventors have found that it is difficult to obtain sufficient power generation performance and have devised the present invention. In addition, as with this three-phase interface problem, it is important to improve durability against methanol, which has been one of the issues to be solved.

[0005] Patent Document 4 describes a technique for chemically bonding a molecule having a proton conductive functional group to the surface of a catalyst particle in order to extend the battery life. However, when the catalyst particles and the proton-conducting functional group-containing compound are combined, the proton-conducting functional group itself is modified by the action of the catalyst, resulting in a decrease in proton conductivity or adsorption of the proton-conducting functional group onto the catalyst. There has been a problem of deteriorating catalyst performance.

Patent Document 1: Japanese Patent Publication No. 11-515040

Patent Document 2: JP 2002-110174 A

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-87288

Patent Document 4: Japanese Unexamined Patent Application Publication No. 2004-172098

Disclosure of the invention

Problems to be solved by the invention

[0006] The problem to be solved by the present invention is that it has excellent adhesion to an electrolyte membrane and an electrode, can hold a catalytic metal uniformly, and prevents a decrease in proton conductivity that is highly resistant to methanol. It is possible to provide an electrolyte composition for a fuel cell and a fuel cell at low cost that are capable of being environmentally compatible and durable.

Means for solving the problem

[0007] The fuel cell electrolyte composition of the present invention is a fuel cell electrolyte composition containing the following compound (A) and compound (B) as essential components.

(A) a compound having a functional group capable of binding to a catalyst metal and having a number average molecular weight of 500 to 100,000

(B) A compound having a proton conductive functional group and a number average molecular weight of 50 to L000000.

[0008] Such an electrolyte composition for a fuel cell of the present invention has an adhesive property to an electrolyte membrane or an electrode material. Therefore, the membrane-electrode assembly can be adjusted without impairing proton conductivity. In addition, since the catalyst metal can be highly dispersed and the activity of the catalyst can be sufficiently extracted, the fuel cell including the catalyst metal can be a high output and high durability battery.

[0009] In particular, since the diffusion of reactants / products, electron transfer, and hydrogen ion occurs at the electrode of the fuel cell, each of the fuel, electrons, and hydrogen ions that are the reaction points moves. Ease of handling is important, but the electrolyte composition for a fuel cell of the present invention is not limited to the electrolytes even if the compounds (A) and (B) are hydrocarbon-based resins that are not fluorine-based resins. When is used as a binder for the electrode, the ease of each movement can be secured, so that sufficient power generation performance can be obtained, and the durability against methanol can be improved. In addition, non-fluorinated resin has a low environmental impact.

[0010] Since the number of functional groups capable of binding to the catalyst metal is preferably 2 or less per molecule, it is possible to sufficiently bring out the activity of the catalyst metal. A high output battery can be obtained.

[0011] The functional group capable of binding to the catalyst metal is preferably a mercapto group, and can form a covalent bond with the metal catalyst, and thus can be firmly bonded.

[0012] It is preferable that the mercapto group is present at the molecular end of the compound (A) because it efficiently binds to the catalyst and does not cover the surface of the catalyst more than necessary.

[0013] The compound (A) is preferably a polymer polymerized by reversible addition / elimination chain transfer polymerization and further treated with a treating agent, which has a mercapto group at the molecular end. The polymer compound to be prepared can be conveniently performed while sufficiently controlling the amount of mercapto group introduced.

[0014] Preferably, the treating agent is one or more compounds selected from the group consisting of a hydrogen-nitrogen bond-containing compound, a basic compound, and a reducing agent, and a thiocarbothio group is preferably converted to a mercapto group. Can be converted to

[0015] Further, it is preferable that the compound (A) and the compound (B) are the same compound.

Since the catalytic metal can be highly dispersed without considering the compatibility of (A) and (B), and the catalytic activity can be fully exploited, the fuel cell containing it can be considered as a high-power, high-durability battery. can do. [0016] On the other hand, the proton conductive functional group is preferably a sulfonic acid group, resulting in a highly proton conductive electrolyte composition.

[0017] The weight ratio of the compound (A) to the compound (B) is preferably in the range of (A): (B) = 1: 99 to 99: 1, and has catalytic activity and proton conductivity. · An electrolyte composition having excellent properties and durability.

[0018] A fuel cell catalyst composition having excellent characteristics can be obtained by further including, in such an electrolyte composition for a fuel cell of the present invention, carbon (C) carrying a catalyst metal. It can be done.

[0019] The weight ratio of the weight of the catalyst metal-supported carbon (C) to the total weight of the compound (A) and the compound (B) is (C): ((A) + (B)) = l: It is preferably in the range of 9 to 9: 1, and it becomes a fuel cell catalyst composition having excellent characteristics having both catalytic activity, proton conductivity and durability.

[0020] A membrane-electrode assembly comprising such an electrolyte composition of the present invention as a component of an electrode layer, wherein a membrane-electrode assembly in which an electrolyte membrane having proton conductivity is sandwiched between electrode layers is a fuel cell. The membrane electrode assembly is preferable because it stably exhibits excellent properties.

[0021] In particular, when a non-fluorine-based hydrocarbon resin is used as the proton-conductive electrolyte membrane, it is not a fluorine-based resin among the electrolyte compositions of the present invention as an electrode binder. In the case of using hydrocarbon-based resin, since the composition of the binder and the electrolyte membrane can be made similar, the adhesion between them can be strengthened.

[0022] The membrane electrode assembly is one or more types of fuel cells selected from the group consisting of a solid polymer type, a direct liquid type, and a direct methanol type, particularly a direct methanol type fuel cell because of its high resistance to methanol. It can be suitably used for.

[0023] In particular, when such a membrane-electrode assembly of the present invention is used directly in a methanol fuel cell, carbonization is performed as the proton-conducting electrolyte membrane constituting the membrane-electrode assembly. By using a hydrogen-based resin, durability to methanol as a fuel can be ensured. Further, by using a hydrocarbon-based resin among the electrolyte compositions of the present invention as a binder for an electrode layer, As fluorinated resin is not used, the environmental impact can be further reduced. The invention's effect

[0024] The electrolyte composition for a fuel cell of the present invention is excellent in adhesiveness with an electrolyte membrane or an electrode material, so that it can be adhered to a catalytic metal without impairing proton conductivity, and the catalytic metal has sufficient activity. Since it can be pulled out, the fuel cell containing it can be a high-power, high-durability battery.

Brief Description of Drawings

FIG. 1 is a schematic view of a membrane-electrode assembly.

FIG. 2 is a cross-sectional view of a main part of a direct methanol fuel cell.

Explanation of symbols

[0026] 1 Proton conducting polymer membrane

2 Catalyst layer

3 Diffusion layer

4 Senore ¹ ~~ Ta ¹ ~~

5 flow path

BEST MODE FOR CARRYING OUT THE INVENTION

[0027] The electrolyte composition for a fuel cell of the present invention comprises (A) a compound having a number average molecular weight of 500 to LOOOOO having a functional group capable of binding to a catalytic metal, and (B) having a proton conductive functional group. Number Average molecular weight 50 ~: Contains LOOOOOO compound as an essential component. Each compound is described below.

(Compound A)

In compound (A), the functional group capable of binding to the catalyst metal is not particularly limited, and examples thereof include a mercapto group, a hydroxyl group, a carboxyl group, an amino group, an amide group, and a disulfide group. The bond to be formed is not limited to a covalent bond, an ionic bond, or a coordination bond, but a covalent bond is preferable because the bond is strong. Of these functional groups, a mercapto group is most preferable because a covalent bond can be formed. If the number average molecular weight of the compound (A) is less than 500, the resistance to methanol is low, and if it exceeds 100000, the catalyst coverage becomes too high and the catalytic activity becomes low. Such durability and catalytic activity In this respect, the number average molecular weight of the compound (A) is more preferably 1000 to 50000. In the present invention, the number average molecular weight of the polymer compound is a value determined by gel permeation chromatography (GPC) analysis. In compound (A), the number of functional groups capable of binding to the catalytic metal is not particularly limited, but if it is too large, the catalytic metal surface is covered with a polymer, resulting in low catalytic activity. The number is preferably 2 or less per, and more preferably 1 per molecule. Further, the position of the functional group in the compound (A) is more efficient at binding to the catalyst than at the molecular chain, and it does not cover the surface of the catalyst more than necessary. U, because, preferred.

[0028] A method for producing a polymer compound having a mercapto group at the molecular end as the compound (A) is not particularly limited, but a reversible addition / desorption chain can be introduced in a quantitative and simple manner. A method of treating a polymer obtained by transfer (RAFT) polymerization with a treating agent is preferred.

[0029] RAFT polymerization is a method of controlled radical polymerization of vinyl monomers using thiocarbothioi compounds as chain transfer agents. For example, "HANDBOOK OF RADICAL PO LYMERIZATION", K. Matyjaszewski and TP Davis Ed. The method described in Wiley, 2002, page 661, the method described in the reference of the book, or the method described in JP 2000-515181 A can be applied. The polymerization mode is not particularly limited, but bulk polymerization or solution polymerization is preferable in that the treatment with the treating agent after polymerization is simple.

[0030] The thiocarbothio compound is not particularly limited! However, a compound represented by the following general formula 1 is preferable in view of availability and reactivity.

[0031] [Chemical 1]

Ph-

S Me S Me

Ph-C-H S-CPh Ph-C-S-CHOAc

S e

S Me

Ph-CS-CCN Ph-CS-CCH ₂ CH ₂ COOH

e Me n

Me

PhO-CS-CCN EtO-CS-CH ₂ CN

e

PhCH ₂ -SCS-CH ₂

Me Me Me S Me

PhCH-S-C-S-CHPh PhC-S-C-S-CPh

General formula

Me Me

[In the formula, Me represents a methyl group, Et represents an ethyl group, Ph represents a phenyl group, Ac represents a acetyl group, and r is an integer of 1 or more].

[0033] The monomer used for polymerization is not particularly limited, and a vinyl monomer capable of radical polymerization can be used. However, (meth) acrylic acid ester, ( (Meth) acrylic acid, styrene, (meth) acrylonitrile, (meth) acrylamide, and salt vinyl are preferred (meth) acrylic acid esters are more preferred!

[0034] By treating the polymer obtained by RAFT polymerization with a treating agent, the thiothio group can be converted into a mercapto group to give a polymer compound having a mercapto group at the molecular end. The treatment agent is not particularly limited, but is selected from the group consisting of a hydrogen-nitrogen bond-containing compound, a basic compound, and a reducing agent in terms of high conversion efficiency to a mercapto group. One or more compounds are preferred.

[0035] Among the above treating agents, the hydrogen-nitrogen bond-containing compound is not particularly limited, but ammonia, hydrazine, primary amine, secondary amine, amido compound, ammine hydrochloride, hydrogen-nitrogen Examples thereof include a bond-containing polymer and a hindered amine light stabilizer (HALS). Examples of the primary amines include methylamine, ethylamine, isopropylamine, n-propylamine, n-butylamine, t-butylamine, 2-ethylhexylamine, 2-aminoethanolamine, ethylenediamine, diethylenetriamine, 1, 2 -Diaminopropane, 1,4-diaminobutane, cyclohexylamine, aline, phenethylamine and the like. Examples of secondary amines include dimethylamine, jetylamine, diisobutylamine, di-2-ethylhexylamine, iminodiacetic acid, bis (hydroxyethyl) amine, di-η-butylamine, di-butylamine, diphenyl- Examples include lumine, N-methylaline, imidazole, and piperidine. Examples of the amide compound include adipic acid hydrazide, N-isopropylacrylamide, oleamide, thioacetamide, formamide, acetate, phthalimide, and succinimide. Examples of the amine hydrochloride include acetamidine hydrochloride, monomethylamine hydrochloride, dimethylamine hydrochloride, monoethylamine hydrochloride, jetylamine hydrochloride, and guanidine hydrochloride. Examples of the hydrogen-nitrogen bond-containing polymer include polyethyleneimine, polyallylamine, polybulamine and the like. Examples of the above HALS include ADK STAB LA-77 (Asahi Denka Kogyo Co., Ltd.), Tinuvin 144 (Ciba 'Specialty Chemicals Co., Ltd.), ADK STAB LA-67 (Asahi Denka Kogyo Co., Ltd.), etc. Can do.

[0036] Among the above treatment agents, examples of basic compounds are not particularly limited, but include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, sodium methoxide, sodium ethoxy. And magnesium methoxide, sodium carbonate, potassium carbonate, sodium sulfate, sodium sulfate.

[0037] Among the above-mentioned treatment agents, examples of the reducing agent are not particularly limited, but examples thereof include sodium hydride, lithium hydride, calcium hydride, LiAlH, NaBH, LiBEt H, and hydrogen.

4 4 3

Togashi.

[0038] The above treatment agents may be used alone or in combination! N- in terms of reactivity Primary amines such as butyramine, sodium hydroxide, potassium hydroxide, sodium hydroxide, sodium sulfide, LiAlH, NaBH, and LiBEt H are preferred. The amount of the above treatment agent is special

4 4 3

Although not limited thereto, in terms of reactivity and economy, 0.01 to: 0 part by weight of LO is preferable with respect to 100 parts by weight of the polymer, and 0.1 to 50 parts by weight is more preferable. Reaction conditions such as temperature, presence or absence of solvent, and mixing conditions are not particularly limited. However, a reaction method in which a treatment agent is directly added to the solution after polymerization is preferable because the operation is simple. A range of C to 150 ° C is preferred.

(Compound B)

In the compound (B) of the present invention, the proton conductive functional group is not particularly limited, and examples thereof include a sulfonic acid group, a sulfino group, a phosphor group, and a phosphier group. Of these, sulfonic acid groups are preferred because of their high proton conductivity. The sulfonic acid group may be an alkali metal salt as it is. If the number average molecular weight of the compound (B) is less than 50, the adhesive strength with the electrolyte membrane or electrode material is insufficient, and if it exceeds 1000000, mixing with other components becomes difficult. In view of such adhesive strength and ease of handling, the number average molecular weight of the compound) is more preferably 100 to 800,000.

[0039] Although the main chain structure of compound (B) is not particularly limited, it is polyethersulfone (PES), polyetheretherketone (PEE K), polyphenylene in terms of excellent heat resistance, methanol resistance, and acid resistance. Sulfide, polyphenylene ether, polysulfone, polyether ketone, and styrene thermoplastic elastomer are preferred.

(A, B ratio)

In the fuel cell electrolyte composition of the present invention, the weight ratio of the compound (A) to the compound (B) is not particularly limited. However, the catalyst activity (proton conductivity / durability) (A) : (B) = 1: 99 to 99: 1 is preferable (A): (B) = 2: 98 to 98: 2 is more preferable!

[0040] The electrolyte composition for a fuel cell of the present invention has an excellent characteristic by further containing (C) carbon carrying a catalyst metal as a component other than the compounds (A) and (B). It can be a catalyst composition. (Catalyst metal-supported carbon c)

The catalyst metal in the catalyst metal-supported carbon (c) is not particularly limited, and examples thereof include platinum, gold, palladium, ruthenium, nickel, rhodium, connort, iridium, osmium, iron, and alloys containing these metals. Of these, platinum and platinum-containing alloys are preferred because of their high catalytic activity. The shape of the catalyst metal is not particularly limited, but it is preferably a particle having a number average particle size of lOOnm or less, which is preferably particulate in terms of high catalytic activity, and a number average particle size of 50 nm or less is more preferable. More preferably, it is a particle. Carbon in catalytic metal-supported carbon (C) is not particularly limited, but high conductivity is preferred. Specifically, high surface area such as carbon black such as ketjen black and acetylene black, activated carbon, carbon nanohorn and carbon nanotube Are preferred.

The composition ratio of the carbon carrying the catalyst metal is preferably in the range of catalyst metal: carbon (weight ratio) = 5: 95 to 95: 5, and the amount of the catalyst metal is preferably as small as possible within the range where desired characteristics are manifested. The basis weight in the catalyst layer is preferably in the range of about 0.1 to 5 mgZcm ² .

(A + B, C ratio)

In the fuel cell electrolyte composition of the present invention, the weight ratio of the compound (A), the compound (B) and the catalytic metal-supported carbon (C) is not particularly limited, but the catalytic activity 'proton conductivity In terms of durability, the weight ratio of the weight of catalyst metal-supported carbon (C) to the combined weight of compound (A) and compound (B) is (C): ((A) + (B)) = l: It is preferable to be in the range of 9 to 9: 1 (C): ((A) + (B)) = 2: It is more preferable to be in the range of 8 to 8: 2. Good.

(Membrane-electrode assembly)

The fuel cell of the present invention has a membrane electrode assembly shown in FIG. 1 in which an electrolyte membrane having proton conductivity is sandwiched between layers containing the electrolyte composition.

(Electrolyte membrane)

The electrolyte membrane having proton conductivity is not particularly limited. For example, polyacrylamide, polyacrylonitrile, polyarylethersulfone, poly (arylphenol) Tellurium), polyethyleneoxide, polyetherethersulfone, polyetherketone, polyetherketoneketone, polyvinylchloride, poly (diphenylsiloxane), poly (diphenylphosphazene), polysulfone, polyparaphenylene, polybulualcohol , Poly (phenylglycidyl ether), poly (phenylmethylsiloxane), poly (phenylmethylphosphazene), polyphenoloxide, polyphenylenesulfoxide, polyphenylenesulfonesulfone, polyphenylenesulfone, poly Benzimidazole, polybenzoxazole, polybenzothiazole, poly (a-methylstyrene), polystyrene, styrene- (ethylene-butylene) styrene copolymer, styrene (ethylene-propylene) styrene copolymer, Len (Polyisobutylene) Styrene copolymer, poly 1,4-biphenyl diethylene ether ether sulfone, polyarylene ether sulfone, polyether imide, cyanate ester, polyethylene, polypropylene, polyamide, polyacetal, polybutylene terephthalate, polyethylene terephthalate, The main constituents are hydrocarbon polymer compounds such as syndiotactic polystyrene, polyphenylene sulfide, polyetheretherketone, polyether-tolyl, etc., and sulfonic acid groups, phosphoric acid groups, carboxylic acid groups, phenolic hydroxyl groups, etc. It contains proton-conducting substituents, such as pore filling membranes filled with porous resins filled with these resins, inorganic proton conductors (eg tungsten oxide hydrate (WO · η 水和 0), oxidation Morib Down hydrate (ΜοΟ · ηΗ 0), data

3 2 3 2 Organic organic-inorganic composite films in which Ngstric acid, molybdophosphoric acid, etc.) are held in a polymer network that also has a key force with hydrocarbons. Of these, polystyrene is important in terms of proton conductivity, methanol blocking properties, and chemical and thermal stability of polymer electrolytes.

, Syndiotactic polystyrene, polyphenylene ether, modified polyphenylene ether, polysulfone, polyether sulfone, polyether ether ketone and polyphenylene sulfide, and their derivative power group power is at least one selected It is preferable.

The diffusion layers may or may not be joined to the catalyst with the same or different binder. In general, porous conductive materials such as carbon paper and carbon cloth are used. The diffusion layer is supplied with water or water generated by an electrochemical reaction, and prevents the pores from being blocked. Which fluorine compound should be water repellent treated?

(Production method of membrane electrode assembly)

Next, a method for producing a membrane / electrode assembly will be described. Various manufacturing methods can be selected, and an example of a manufacturing method of a membrane electrode assembly is described below. The catalyst layer 2 is mainly composed of an electrolyte composition which is a polymer compound having a binding action and the catalyst metal-supporting carbon. The electrolyte composition is used in a state dissolved or dispersed in a solvent, and the electrolyte composition is preferably 0.1% by weight to 30% by weight with respect to the solvent to form a uniform catalyst layer. A slurry or mixed solution is obtained by mixing a resin in which a resin is dissolved or dispersed (hereinafter referred to as a binder) and the above catalyst metal-supported carbon. The resin component of the binder is preferably in a weight ratio of 0.05 to L 5 with respect to the carbon supported on the catalyst metal. If it is larger than this range, the catalytic metal may be covered with the polymer electrolyte and not be used effectively. On the other hand, if it is smaller than this range, sufficient binding action may not be obtained, and the catalyst layer may not be maintained.In addition, water is added to this mixed solution so that the viscosity becomes appropriate for forming the catalyst layer. It may be included. This mixed solution is deposited on a release film such as a polytetrafluoroethylene (PTFE) film by a doctor knife, roll coater, screen printing, spraying, etc., and dried to remove the solvent and water. In order to prevent cracking of the catalyst layer, the coating and solvent removal operations can be repeated several times.

The release film coated with the catalyst is placed on both sides of the proton conducting polymer membrane and hot-pressed using a press such as a hot press or roll press. The hot press conditions need to be set according to the type of polymer electrolyte contained in the electrolyte membrane and binder used. The set temperature is generally 80 ° C to 200 ° C, which is the temperature above the glass transition point or softening point of the proton conductive polymer membrane or polymer electrolyte used, and further the polymer electrolyte. The temperature is preferably higher than the glass transition point and softening point of the membrane and the polymer electrolyte. If it is larger than this range, the terminal group in the polymer electrolyte may be detached and not used effectively. On the other hand, if it is smaller than this range, sufficient adhesion cannot be obtained, and the interface resistance may increase. Further, the thermal degradation or thermal decomposition temperature or less of the resin component contained in the electrolyte membrane or binder used is preferable. If the maximum pressure is 0. IMPa or more and 20 MPa or less, the polymer electrolyte membrane and the catalyst layer will adhere sufficiently. In addition, when there is no particularly large deformation of the material, it is preferable because the characteristic does not deteriorate. When larger than this range, there exists a possibility that a catalyst layer may collapse | crumble and it may not be utilized effectively. On the other hand, if it is smaller than this range, sufficient adhesion cannot be obtained, and the interface resistance may increase. Under the above conditions, the membrane-electrode assembly can be obtained by removing the release film from the bonded body force obtained by pressing. Another example of the method for producing the membrane-electrode assembly precursor is described below. The mixed solution is applied onto the diffusion layer by a doctor blade, a roll coater, screen printing, or spraying by spraying, and then dried to remove the solvent to obtain a catalyst-supporting gas diffusion layer. A membrane-one electrode assembly can be obtained by placing catalyst-supporting gas diffusion layers on both sides of a hydrocarbon polymer electrolyte membrane and hot pressing using a press such as a hot press or roll press. . As in the above example, the hot press conditions need to be set according to the type of proton conducting electrolyte membrane or polymer electrolyte used. In addition, the catalyst, the polymer electrolyte, and the diffusion layer may be commercially available or may be integrated.

(Fuel cell)

Next, the fuel cell of the present invention will be described. Figure 2 is a cross-sectional view of the main part of a direct methanol fuel cell. The membrane-electrode assembly obtained by the method as described above is inserted between a pair of separators 4 and the like in which a flow path 5 for feeding fuel and an oxidant is formed. A direct methanol fuel cell with a high physical strength can be obtained. The diffusion layer 3 may or may not be adhered to the outside of the catalyst layer 2 with a polymer electrolyte having a binding action. If it is not bonded with a polymer electrolyte, it can be in sufficient contact by tightening the separator with screws. By separately supplying a liquid mainly composed of methanol as a fuel and a gas containing oxygen (oxygen or air) as an oxidant to the flow path 5 of the separator 4, the catalyst layer passes through the diffusion layer 3. The direct methanol fuel cell generates electricity.

As the separator 4, a force bone graphite or a stainless steel conductive material can be used. Especially when using metal materials such as stainless steel, it is preferable to apply a corrosion-resistant treatment!

Example Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

[Synthesis Example 1]

(Aromatic hydrocarbon proton conductive polymer: Synthesis of sulfonated PEEK) PEEK 4 50P (Made by Vitatrex Emshi Co., Ltd., with molecular weight of approx. 100,000) was added. In the reactor, 92 g of concentrated sulfuric acid was added from a dropping funnel and stirred at room temperature for 3 days. After completion of the reaction, the reaction solution was poured into 3 liters of pure water to precipitate a polymer and then filtered, and washed with 3 liters of water 10 times until the filtrate became neutral. The obtained reaction product was dried at 90 ° C. for 10 hours under a vacuum of lTorr to obtain 4.5 g of a yellow solid. In the obtained solid, peaks corresponding to sulfonic acid groups were observed at 1450, 1445, and 1390 cm- ¹ in the infrared spectrum. The ion exchange capacity (IEC) was calculated to be 2. 17 meq / g. A solution prepared from 2.14 g of this resin and 26.4 g of DM F2 was placed in a petri dish having an inner diameter of 60 mm and dried in a vacuum oven at 110 ° C. for 3 hours under 1 Torr. The resulting dried film was swollen with water to peel off the force and petri dish force, and dried for 5 hours at lTorr, 110 ° C. A blended resin composition film having a thickness of 30 m was obtained. Its proton conductivity: sigma was 7. 5 Χ 10- ² SZcm.

[0047] (Synthesis Example 2)

(Aromatic hydrocarbon proton conductive polymer: Synthesis of sulfonated PES) PES 76 OOP (Made by Sumitomo Chemical Co., Ltd., molecular weight of about 15) in a reaction vessel equipped with a mechano-car stirrer, nitrogen inlet tube and dropping funnel 10,000 Og was added. In the reactor, 138 g of concentrated sulfuric acid was added from a dropping funnel and stirred at room temperature for 1 day. To this reaction solution, 50.5 g of chlorosulfonic acid was added dropwise under nitrogen, followed by stirring at room temperature for 3 hours. After completion of the reaction, the reaction solution was poured into 3 liters of pure water to precipitate a polymer and then filtered, and washed with 3 liters of water 20 times until the filtrate became neutral. The resulting reaction product was dried at 90 ° C. for 10 hours under lTorr vacuum to obtain 16. Og of white solid. In the obtained solid, peaks corresponding to sulfonic acid groups were observed at 1450, 1445, and 1390 cm ¹ in the infrared spectrum. The ion exchange capacity is 1.39meqZg, and a 30m thick resin film prepared in the same manner as in Synthesis Example 1 is used. Ton conductivity, 4. was ² X 10- 2 SZcm.

[Synthesis Example 3]

(Proton-conducting styrene elastomer: Synthesis example of sulfonated SEPS) Septon S EPS 2007 (Made in Kurerene, molecular weight of about 80,000) in a reaction vessel equipped with a mechano-car stirrer, nitrogen inlet tube, and dropping funnel 5. Og, 1,2-diethyl ethane 15. Og, and cyclohexane 25. Og were added and stirred at room temperature for 3 hours. In the reactor, 0.66 g of chlorosulfonic acid dissolved in 10 g of dichloroethane was added from a dropping funnel and stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution is poured into 1 liter of methanol to precipitate a polymer, filtered, washed 3 times with methanol, and then twice with 1 liter of water until the filtrate is neutral. Washed. The obtained reaction product was dried at 90 ° C. for 10 hours under vacuum of lTorr to obtain 6. Og of a brown solid. In the obtained solid, peaks corresponding to sulfonic acid groups were observed at 1450, 1445, and 1390 cm ¹ in the infrared spectrum.

The ion exchange capacity was 1.22 meqZg, and the proton conductivity of a 30 m thick resin membrane prepared in the same manner as in Synthesis Example 1 was 1.1 × 10−Zcm.

[0049] (Synthesis Example 4)

(Proton-conducting styrene-based elastomer: sulfonated SEBS synthesis example) Septon SEPS2007 was prepared in the same manner as Synthesis Example 3 except that SEBS G1650 (Kraton, molecular weight of about 70,000) was added to 5.0 g. As a result, 6.0 g of a reaction product was obtained. In the obtained solid, 1450, 1445, 1390 cm- ^{1, and the} corresponding peak were observed in the infrared spectroscopic spectrum. The ion exchange capacity, 1. a 34meq / g, the proton conductivity of the榭脂film having a thickness of 30 m was prepared in the same manner as in Synthesis Example 1, 3. a 1 X 10- ² SZcm

[0050] (Synthesis Example 5)

(Proton-conducting styrene elastomer: Synthesis example of sulfonated SIBS) Septon SEPS2007 was changed to SIBS Sibustar 103T022 (manufactured by Kane force Co., Ltd., molecular weight of about 50,000). The same operation was performed to obtain 6.0 g of a reaction product. From the obtained solid product, peaks corresponding to 1450, 1445, 1390 cm- ¹ [sulphonate groups] were observed. The ion exchange capacity is 1.32 meqZg, The proton conductivity of the 30 m thick resin membrane prepared in the same manner as in Synthesis Example 1 was 2.7 × 10 ”2 S / cm.

[0051] (Synthesis Example 6)

(Synthesis of polymethyl methacrylate (PMMA—SH) having a mercapto group at the end) 1-L 3-neck flask was charged with methyl methacrylate (501 g), toluene (260 g), 2— (2 ferrule neck pill) dithiobenzoate Og) and azobisisobuty-tolyl (1. lg) were added, and the inside of the reactor was purged with nitrogen. The solution was heated at 90 ° C. for 3 hours with stirring to obtain PMMA with a reaction rate of 42%. Next, n-butylamine (25 g) was added, and the terminal was modified to a mercapto group by stirring at 80 ° C. for 3 hours. This solution was concentrated to 400 ml with a rotary evaporator and poured into methanol (2 L) to precipitate PMMA-SH, which was isolated by filtration. The molecular weight and molecular weight distribution of the obtained PMMA—SH were Mw = 14000, Mn = 11900, and Mw / Mn = 1.17.

[0052] (Synthesis Example 7)

(Synthesis of sulfonated PMMA—SH)

PMMA—SH (5 g) obtained in Synthesis Example 6 was placed in a 300 mL reaction vessel. Add acetic acid (14. OmL) to this, soak 30% hydrogen peroxide (11.2 mL) gradually, then heat to 70 ° C and heat for 20 minutes at 70 ° C. Maintained. This was washed with running water at 60 ° C for 2 hours. In this way, the SH group of PMMA—SH is partially oxidized and converted to SO H group.

Three

Sulfonating power PMMA—SH was obtained. When the infrared visible absorption spectrum of this material was measured, peaks corresponding to sulfonic acid groups were observed at 1450, 1445, and 1390 cm- ¹ . The measured ion exchange capacity is 0. 76MeqZg, proton conductivity榭脂film having a thickness of 30 m was prepared in the same manner as in Synthesis Example ^{1, 1. 0 X 10- 2 S /} cm Met.

[0053] (Example 1)

A poly-lens sulfide film (manufactured by Toray Industries, Inc., trade name: Torelina, thickness: 25 m) was immersed in a mixed solution of chlorosulfonic acid and 1-chlorobutane. At this time, chlorosulfonic acid is 6 times in molar ratio with respect to the polyphenylene sulfide film, and the mixed solution is 1.5% by weight of black sulfonic acid with respect to 1 chlorobutane. After immersion, leave at room temperature for 20 hours Polyphenylene sulfide film was recovered and washed with ion exchange water until neutral.

[0054] The washed polysulfide sulfide film is allowed to stand at 23 ° C for 30 minutes to dry the film, and as a proton conductive polymer membrane, a polyphenylene sulfide membrane into which a sulfonic acid group has been introduced (hereinafter referred to as a proton-conductive polymer membrane) A sulfonated polyphenylene sulfide membrane (80 mm × 80 mm, thickness: 50 m) was obtained.

[0055] Fabrication of membrane-electrode assembly>

Toray TGP-H-60 carbon paper is washed with acetone, and then a Teflon (registered trademark) dispersion (Daikin Industries POLYFLON PTFE D—1E) is applied and baked at 360 ° C for 1 hour for water repellent treatment. A diffusion layer subjected to was obtained.

[0056] The force Sword platinum catalyzed 50 wt% on Ketjen black EC, produced using platinum 3 0 wt ^_0/0 ruthenium 23 weight ^_0/0 supported Ketjen Black EC to the anode catalyst. Mercapto group-containing hydrocarbon binders, the sulfonated PEEK obtained in Synthesis Example 1 heated and dissolved in methanol (MeO H), and the PMMA-SH obtained in Synthesis Example 6 were mixed with N-methyl-2 — A mixed solution (weight ratio: sulfonated PEEK ZPMMA—SH = lZ5) of pyrrolidone (NMP) dissolved in heat was used. In a mortar, 16.7% by weight of the binder solution having a weight concentration of 5%, and as a catalyst metal-supported carbon (C) for the power sword catalyst, the platinum 50% by weight of supported ketjen black EC is used as the anode catalyst. For use, platinum 30 wt% ruthenium 23 wt% ketjen black EC was mixed in a ratio of 83.3 wt%. Apply to the water repellent treated carbon paper with a thickness of 0.37mm as described above using a constant knife moving device with a doctor knife so that the amount of platinum in the power sword and anode is lmgZcm ² respectively, and dry at 60 ° C for 2 hours. Thus, an electrode with catalyst was obtained. The sulfonated poly (phenylene sulfide) membrane was cut to 20 mm × 20 mm, and a 12φ electrode was hot-pressed at a pressure of 100 kgZcm ² and a set temperature of 150 ° C. for 5 minutes to obtain a precursor of a membrane-electrode assembly.

[0057] <Cell fabrication>

The center of a Teflon (registered trademark) sheet having a thickness of 180 / ζ πι and 80 mm square was cut into a 5 × 5 cm square to form a gasket. Membrane - electrode assembly was sandwiched between the gasket and attached to the fuel cells for cell electrode area 25 cm ² (JARI manufactured EX- 1). [0058] <Evaluation of power generation characteristics of liquid fuel cell>

As an evaluation device, GFT-MW manufactured by Toyo Tech-Power was used. ImolZl aqueous methanol solution was supplied to the anode electrode side at a flow rate of 2.5 ml / min., And air was supplied as an oxidant to the power sword electrode side at a flow rate of 800 mlZmin. The power generation characteristics of a direct methanol fuel cell were evaluated at a cell temperature of 60 ° C. Maximum power density was 45. 5WZcm ^2. The results are shown in Table 1.

[0059] [Table 1]

[0060] (Examples 2 to 6)

The proton-conducting polymer compound of the hydrocarbon binder was sulfonated PES obtained in Synthesis Example 2 in Example 2, sulfonated SEPS obtained in Synthesis Example 3 in Example 3, and in Example 4, respectively. Example 1 except that the sulfonated SEBS obtained in Synthesis Example 4 and the sulfonated PMMA-SH obtained in Synthesis Example 7 were used in Example 5 and the sulfonated SIBS Example 6 obtained in Synthesis Example 5. Evaluation was performed in the same manner. The results are shown in Table 1.

[0061] (Examples 7 to 12) Evaluation was carried out in the same manner as in Examples 1 to 6 except that naphthion (registered trademark) 117 (manufactured by DuPont), which is a fluorine-based polymer electrolyte membrane, was used instead of the sulfone polyphenylene sulfide membrane. The results are shown in Table 1.

(Comparative Example 1)

Evaluation was performed in the same manner as in Example 1 except that only the sulfonated PEEK obtained in Synthesis Example 1 was dissolved by heating in methanol (MeOH) as the hydrocarbon binder. The results are shown in Table 1.

Claims

The scope of the claims

[I] An electrolyte composition for fuel cells containing the following compound (A) and compound (B) as essential components.

[2] The fuel cell electrolyte composition according to [1], wherein the number of functional groups capable of binding to the catalyst metal is 2 or less per molecule.

[3] The functional group capable of binding to the catalytic metal is a mercapto group.

1. The fuel cell electrolyte composition according to any one of 1 and 2.

4. The fuel cell electrolyte composition according to claim 3, wherein the mercapto group is present at the molecular end of the compound (A).

[5] The fuel according to claim 3 or 4, wherein the compound (A) is a polymer polymerized by reversible addition / elimination chain transfer polymerization and further treated with a treating agent. Battery electrolyte composition.

6. The fuel cell electrolyte composition according to claim 5, wherein the treating agent is one or more compounds selected from the group consisting of a hydrogen-nitrogen bond-containing compound, a basic compound, and a reducing agent. object.

[7] The compound (A) and the compound (B) are the same compound.

The electrolyte composition for fuel cells according to any one of 1 to 6.

8. The proton conductive functional group according to claim 1, wherein the proton conductive functional group is a sulfonic acid group.

V, electrolyte composition for fuel cells according to any one of the above.

[9] The weight ratio of the compound (A) to the compound (B) is in the range of (A): (B) = 1: 99-99: 1. 9. The fuel cell electrolyte composition according to any one of 8 above.

[10] The method according to any one of [1] to [9], further comprising carbon (C) supporting a catalytic metal.

V, electrolyte composition for fuel cells according to any one of the above.

[II] The weight of the catalyst metal-supported carbon (C), the compound (Α), and the compound (Β) The specific weight with respect to the total weight of (C): ((A) + (B)) = l: 9 to 9: 1 Range of any one of claims 1 to 10 An electrolyte composition for a fuel cell.

[12] A fuel cell membrane-electrode assembly in which an electrolyte membrane having proton conductivity is sandwiched between electrode layers, wherein the electrode layer comprises the fuel cell electrolyte composition according to any one of claims 1 to 11. A membrane / electrode assembly for a fuel cell, comprising:

[13] A fuel cell having one or more types selected from the group consisting of a solid polymer type, a direct liquid type, and a direct methanol type force, comprising the membrane electrode assembly according to claim 12.