Electrolyte film with catalytic layer, film electrode joint body, and fuel cell

Abstract

To provide an electrolyte film with a catalytic layer, the electrolyte film presenting an improved power generation performance and using a carbon hydride-based polymer electrolyte film.SOLUTION: The electrolyte film with a catalytic layer includes: a cathode catalytic layer in one surface of an electrolyte film; and an anode catalytic layer in the other surface. The electrolyte film includes a carbon hydride-based polymer electrode and has a thickness (TM) of less than 20 μm. The ratio of the thickness (TC) of the cathode catalytic layer and the thickness (TA) of the anode catalytic layer, (TA / TC), is less than 0.40.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a catalyst-coated electrolyte membrane, a membrane electrode assembly, and a fuel cell. [Background technology]

[0002] 2. Description of the Related Art Fuel cells are a type of power generation device that generates electrical energy by electrochemically oxidizing fuels such as hydrogen and methanol, and have recently been attracting attention as a clean energy source.

[0003] Fuel cells are typically constructed as a unit, with a cell consisting of a membrane electrode assembly (MEA) sandwiched between separators. The MEA is composed of a catalyst coated membrane (CCM), which has catalyst layers laminated on both sides of the electrolyte membrane, and gas diffusion layers arranged on both sides of that. A pair of electrodes is composed of the catalyst layers and gas diffusion layers arranged on either side of the electrolyte membrane, one of which is the anode electrode and the other the cathode electrode. In a fuel cell, electricity is generated by an electrochemical reaction when fuel gas such as hydrogen comes into contact with the anode electrode and oxygen or air comes into contact with the cathode electrode. At this time, water is produced at the cathode electrode through a cell reaction.

[0004] Conventionally, fluoropolymer electrolyte membranes using fluoropolymers such as perfluorocarbon sulfonic acid polymers have been widely used as the electrolyte membrane, and the catalyst layer has also been designed to match the fluoropolymer electrolyte membrane.

[0005] On the other hand, fluorine-based polymer electrolyte membranes have problems such as being expensive, having poor gas barrier properties, and having relatively low mechanical strength at high temperatures, and therefore the use of hydrocarbon-based polymer electrolyte membranes instead of fluorine-based polymer electrolyte membranes is being considered (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-167820 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-195046 [Patent Document 3] Special Publication No. 2015-519681 Summary of the Invention [Problem to be solved by the invention]

[0007] Hydrocarbon-based polymer electrolyte membranes are expected to solve the problems of fluororesin-based polymer electrolyte membranes, but there is also the problem that simply applying a conventional catalyst layer to a hydrocarbon-based polymer electrolyte membrane does not provide sufficient power generation performance.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a catalyst layer-equipped electrolyte membrane using a hydrocarbon-based polymer electrolyte membrane, which has improved power generation performance. [Means for solving the problem]

[0009] The present inventors have discovered that the above-mentioned problem is related to the fact that hydrocarbon-based polymer electrolyte membranes have lower water permeability than fluorine-based polymer electrolyte membranes, and have thus achieved the present invention. In order to achieve the above-mentioned object, the catalyst-layered electrolyte membrane of the present invention has the following configuration. That is, [1] A catalyst-layered electrolyte membrane having a cathode catalyst layer on one side of the electrolyte membrane and an anode catalyst layer on the other side, the electrolyte membrane contains a hydrocarbon-based polymer electrolyte; The thickness (TM) of the electrolyte membrane is less than 20 μm; In the catalyst layer-equipped electrolyte membrane, the ratio (TA / TC) of the thickness (TC) of the cathode catalyst layer to the thickness (TA) of the anode catalyst layer is less than 0.40. [2] The catalyst layer-equipped electrolyte membrane according to [1], wherein the thickness (TC) of the cathode catalyst layer is 8 μm or more and less than 20 μm, and the thickness (TA) of the anode catalyst layer is 0.3 μm or more and less than 4 μm. [3] The catalyst layer-equipped electrolyte membrane according to [1] or [2], wherein the ratio (TA / TM) of the thickness of the electrolyte membrane (TM) to the thickness of the anode catalyst layer (TA) is 0.50 or less. [4] The catalyst layer-equipped electrolyte membrane according to any one of [1] to [3], wherein the ratio (TC / TM) of the thickness of the electrolyte membrane (TM) to the thickness of the cathode catalyst layer (TC) is 0.60 or more. [5] The catalyst layer-equipped electrolyte membrane according to any one of [1] to [4], wherein the ratio (TA / TC) is 0.03 or more. [6] The catalyst layer-equipped electrolyte membrane according to any one of [1] to [5], wherein the cathode catalyst layer and the anode catalyst layer each contain platinum-supported carbon particles in which platinum is supported on carbon particles. [7] The catalyst-layered electrolyte membrane according to [6], wherein the ratio of the mass of platinum to the mass of the platinum-supported particles (platinum support rate) is 25 mass % or more and less than 60 mass %. [8] The catalyst layer-equipped electrolyte membrane according to [6] or [7], wherein the cathode catalyst layer and the anode catalyst layer each further contain a polymer electrolyte, and the ratio (I / C) of the mass of the carbon particles in the platinum-supported carbon particles to the mass of the polymer electrolyte in each catalyst layer (C) is 0.6 to 1.4 in both the cathode catalyst layer and the anode catalyst layer. [9] The catalyst layer-equipped electrolyte membrane according to any one of [6] to [8], wherein the mass per unit area of ​​platinum contained in the cathode catalyst layer is (CPt) and the mass per unit area of ​​platinum contained in the anode catalyst layer is (APt), and the ratio therebetween (APt / CPt) is less than 0.9.

[10] The (CPt) is 0.15 mg / cm 2 More than 1.3mg / cm 2 and (APt) is less than 0.03 mg / cm 2 More than 0.3mg / cm 2 The catalyst layer-equipped electrolyte membrane according to [9], wherein the .lambda.

[11] The water vapor transmission rate (WR) of the electrolyte membrane measured and calculated under the following conditions is 1.7 × 10 -5 cm 3 cm / (cm 2The catalyst-layered electrolyte membrane according to any one of [1] to

[10] , wherein the surface tension is 0.0 ... <Measurement conditions and calculation method for water vapor transmission rate> The water permeation rate (cm) from the cathode to the anode at 85°C when the cathode is at 55% RH and the anode is at 0% RH. 3 / s) and the permeation rate (cm 3 / s), electrolyte membrane thickness (cm), differential pressure (cmHg), and permeation area (cm 2 ) and calculated using the following formula: <Calculation formula> Water vapor permeability (cm 3 cm / (cm 2 cmHg s))= {Water vapor transmission rate (cm 3 / s) × electrolyte membrane thickness (cm)} / {(gas pressure difference (cmHg) × permeation area (cm 2 ))}.

[12] The catalyst layer-equipped electrolyte membrane according to any one of [1] to

[11] , wherein the hydrocarbon-based polymer electrolyte is partly or entirely an aromatic hydrocarbon-based polymer.

[13] The catalyst layer-equipped electrolyte membrane according to

[12] , wherein a part or all of the aromatic hydrocarbon-based polymer is a polyether ketone-based polymer.

[14] The catalyst layer-equipped electrolyte membrane according to

[12] or

[13] , wherein the aromatic hydrocarbon-based polymer is a block copolymer of an ionic segment and a nonionic segment.

[15] The catalyst-layered electrolyte membrane according to any one of [1] to

[14] , wherein the electrolyte membrane comprises a porous substrate.

[16] The catalyst-layered electrolyte membrane according to any one of [1] to

[15] , wherein the electrolyte membrane has a polymer electrolyte layer on one or both sides of a composite layer containing a porous substrate and a polymer electrolyte.

[17] A membrane / electrode assembly comprising a catalyst-coated electrolyte membrane according to any one of [1] to

[16] and a gas diffusion layer disposed on each of the two surfaces of the electrolyte membrane.

[18] A fuel cell comprising the membrane electrode assembly according to

[17] . [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a catalyst layer-equipped electrolyte membrane using a hydrocarbon-based polymer electrolyte membrane, which has improved power generation performance. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments and can be implemented with various modifications depending on the purpose and application.

[0012] [Electrolyte membrane with catalyst layer] A catalyst-coated electrolyte membrane according to an embodiment of the present invention comprises an electrolyte membrane containing a hydrocarbon-based polymer electrolyte, a cathode catalyst layer on one side thereof, and an anode catalyst layer on the other side thereof. The inventors have discovered that the above-mentioned problems with such a catalyst-coated electrolyte membrane are related to the low water permeability of the electrolyte membrane, leading to the present invention.

[0013] In a fuel cell, water produced at the cathode moves to the anode through the electrolyte membrane. As the water permeability of the electrolyte membrane decreases, the amount of water moving from the cathode to the anode decreases. Electrolyte membranes containing hydrocarbon-based polymer electrolytes have lower water permeability than fluoropolymer electrolyte membranes. In other words, electrolyte membranes containing hydrocarbon-based polymer electrolytes suppress water movement from the cathode to the anode compared to fluoropolymer electrolyte membranes.

[0014] When the migration of water produced at the cathode to the anode is inhibited, water tends to accumulate in the cathode catalyst layer. When water accumulates in the cathode catalyst layer, gas (oxygen and air) diffusivity decreases. It is presumed that this series of phenomena is the main cause of the above-mentioned problems. Until now, the problems caused by the water permeability of electrolyte membranes containing hydrocarbon-based polymer electrolytes as described above have not been recognized, and no design concepts that motivate solutions to these problems have been reported.

[0015] Therefore, in order to design a system to promote the movement of water from the cathode to the anode, we focused on the following points: (1) In the electrolyte membrane, water permeability is correlated with the membrane thickness, and water movement becomes easier as the membrane thickness is reduced; and (2) in the catalyst layer, water movement becomes easier as a result of creating a water concentration gradient between the cathode and anode.

[0016] After extensive investigation into these two points, it was found that the above problem can be solved by the synergistic effect of the combination of (A) the thickness (TM) of the electrolyte membrane containing a hydrocarbon-based polymer electrolyte being less than 20 μm, and (B) the ratio (TA / TC) of the thickness (TC) of the cathode catalyst layer to the thickness (TA) of the anode catalyst layer being less than 0.40. Hereinafter, the electrolyte membrane containing a hydrocarbon-based polymer electrolyte may be simply referred to as the "electrolyte membrane."

[0017] The minimum thickness of conventional commercially available fluorine-based polymer electrolyte membranes, such as "Nafion" (registered trademark) (manufactured by Chemours), is approximately 25 μm. Electrolyte membranes containing hydrocarbon-based polymer electrolytes have superior gas barrier properties and mechanical strength compared to fluorine-based polymer electrolyte membranes, and can be made thinner than 20 μm.

[0018] When the electrolyte membrane thickness (TM) is less than 20 μm, water mobility from the cathode to the anode is enhanced. From the viewpoint of further enhancing water mobility from the cathode to the anode, TM is preferably less than 17 μm, more preferably less than 15 μm, even more preferably less than 13 μm, and particularly preferably less than 10 μm. Furthermore, from the viewpoint of durability, TM is preferably 3 μm or more, more preferably 5 μm or more.

[0019] The ratio (TA / TC) of the thickness of the cathode catalyst layer (TC) to the thickness of the anode catalyst layer (TA) is less than 0.40. That is, by making TC relatively large and TA relatively small, a water concentration gradient occurs between the cathode and the anode, and water mobility from the cathode to the anode is enhanced. From this viewpoint, TA / TC is preferably less than 0.35, more preferably less than 0.30, and particularly preferably less than 0.27. Furthermore, from the viewpoint of durability, the ratio (TA / TC) is preferably 0.03 or more, more preferably 0.05 or more, even more preferably 0.08 or more, and particularly preferably 0.10 or more.

[0020] The cathode catalyst layer preferably has a thickness that can retain a certain amount of water, from the viewpoints of suppressing a decrease in gas diffusibility and increasing the water concentration gradient between the cathode and the anode. From this viewpoint, the thickness (TC) of the cathode catalyst layer is preferably 8 μm or more, more preferably 9 μm or more, and particularly preferably 10 μm or more. On the other hand, if TC is too large, gas diffusibility may decrease, so it is preferably less than 20 μm, more preferably less than 19 μm, even more preferably less than 18 μm, and particularly preferably less than 17 μm.

[0021] The thickness (TA) of the anode catalyst layer is preferably less than 4 μm, more preferably less than 3.5 μm, even more preferably less than 3 μm, and particularly preferably less than 2.7 μm, from the viewpoint of relatively reducing the water retention capacity and increasing the water concentration gradient between the anode and the cathode. If the TA is too small, the output may decrease, so the thickness is preferably 0.3 μm or more, more preferably 0.5 μm or more, and particularly preferably 0.7 μm or more.

[0022] It has been found that the catalyst-coated electrolyte membrane according to the embodiment of the present invention has a preferable range for the relationship between the thickness of the electrolyte membrane (TM) and the thickness of the cathode catalyst layer (TC), and the relationship between the thickness of the electrolyte membrane (TM) and the thickness of the anode catalyst layer (TA) from the viewpoint of improving output. That is, TC / TM is preferably 0.60 or more, and TA / TM is preferably 0.50 or less.

[0023] TC / TM is more preferably 0.70 or more, further preferably 0.80 or more, and particularly preferably 0.90 or more, and is preferably 5.0 or less, more preferably 4.0 or less, and particularly preferably 3.0 or less.

[0024] TA / TM is more preferably 0.40 or less, further preferably 0.33 or less, and particularly preferably 0.30 or less, and is preferably 0.05 or more, more preferably 0.08 or more, and particularly preferably 0.10 or more.

[0025] [Electrolyte membrane] The electrolyte membrane of the present invention includes a hydrocarbon-based polymer electrolyte. The hydrocarbon-based polymer electrolyte is a hydrocarbon-based polymer having an ionic group. The hydrocarbon-based polymer refers to a polymer having a main chain whose main structural unit is hydrocarbon.

[0026] The content of the hydrocarbon-based polymer electrolyte in the electrolyte membrane is preferably 60 mass% or more, more preferably 75 mass% or more, even more preferably 90 mass% or more, and particularly preferably 100 mass% based on the total mass of all polymer electrolytes contained in the electrolyte membrane.

[0027] Examples of hydrocarbon-based polymer electrolytes include aromatic hydrocarbon-based polymers having aromatic rings in the main chain. The aromatic rings may include not only hydrocarbon-based aromatic rings but also heterocycles. Furthermore, the aromatic ring units may also include aliphatic units.

[0028] Specific examples of aromatic hydrocarbon-based polymers include polymers having, together with an aromatic ring, a structure selected from polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene-based polymers, polyarylene ketone, polyether ketone, polyarylene phosphine oxide, polyether phosphine oxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, and polyimide sulfone in the main chain.

[0029] The above-mentioned polysulfone is a general term for a structure having a sulfone bond in the molecular chain, the polyethersulfone is a general term for a structure having an ether bond and a sulfone bond in the molecular chain, and the above-mentioned polyetherketone is a general term for a structure having an ether bond and a ketone bond in the molecular chain. The aromatic hydrocarbon polymer may have a plurality of these structures.

[0030] The ionic group may be an ionic group having either cation exchange ability or anion exchange ability. Examples of such functional groups include sulfonic acid groups, sulfonimide groups, sulfate groups, phosphonic acid groups, phosphate groups, carboxylic acid groups, ammonium groups, phosphonium groups, and amino groups. Two or more types of ionic groups may be contained in the polymer.

[0031] The hydrocarbon-based polymer electrolyte is preferably an aromatic hydrocarbon-based polymer. Examples of the aromatic hydrocarbon-based polymer include polyetherketone-based polymers, polyarylene-based polymers, and polyethersulfone-based polymers, with polyetherketone-based polymers being particularly preferred. Examples of the polyetherketone-based polymer include polyetherketone, polyetherketoneketone, polyetheretherketone, polyetheretherketoneketone, and polyetherketoneetherketoneketone.

[0032] The aromatic hydrocarbon polymer is preferably a random or block copolymer containing an ionic component and a nonionic component, and more preferably a block copolymer. Specifically, a block copolymer of an ionic segment (containing a structural unit containing an ionic group) and a nonionic segment (containing a structural unit not containing an ionic group) is preferred. Polyetherketone block copolymers are particularly preferred. The nonionic segment may contain a small amount of ionic groups as long as the effects of the present invention are not impaired.

[0033] In a block copolymer of an ionic segment and a nonionic segment, the nonionic segment (S E2 ) to the ionic segment (S E1 ) molar composition ratio (S E1 / S E2 ) is preferably 0.20 or more, more preferably 0.33 or more, and even more preferably 0.50 or more. E1 / S E2 ) is preferably 5.00 or less, more preferably 3.00 or less, and even more preferably 2.50 or less.

[0034] As described above, it is preferable to use an aromatic hydrocarbon-based block copolymer as the hydrocarbon-based polymer electrolyte, and it is more preferable to use a polyetherketone-based block copolymer. As the polyetherketone-based block copolymer, it is particularly preferable to use one containing a segment containing a structural unit (S1) containing an ionic group as shown below and a segment containing a structural unit (S2) not containing an ionic group.

[0035] [ka]

[0036] In general formula (S1), Ar 1 ~Ar 4 represents any divalent arylene group, Ar 1 and / or Ar2 contains an ionic group, and Ar 3 and Ar 4 may or may not contain an ionic group. 1 ~Ar 4 may be optionally substituted, and two or more types of arylene groups may be used independently. * represents a bonding site to general formula (S1) or another structural unit.

[0037] [ka]

[0038] In general formula (S2), Ar 5 ~Ar 8 represents any divalent arylene group, which may be optionally substituted, but does not contain an ionic group. 5 ~Ar 8 may independently use two or more types of arylene groups. * represents a bonding site to general formula (S2) or other structural units.

[0039] where Ar 1 ~Ar 8 Preferred divalent arylene groups include hydrocarbon arylene groups such as phenylene, naphthylene, biphenylene, and fluorenediyl groups, and heteroarylene groups such as pyridinediyl, quinoxalinediyl, and thiophenediyl, but are not limited thereto. Here, the term "phenylene group" can be classified into three types: o-phenylene, m-phenylene, and p-phenylene, depending on the bonding site between the benzene ring and other structural units, and unless otherwise specified, the term is used as a general term for these groups in the present specification. The same applies to other divalent arylene groups such as "naphthylene" and "biphenylene." Ar 1 ~Ar 8 is preferably a phenylene group and a phenylene group containing an ionic group, and most preferably a p-phenylene group and a p-phenylene group containing an ionic group. 5 ~Ar 8may be substituted with a group other than an ionic group, but is preferably unsubstituted in terms of proton conductivity, chemical stability, and physical durability.

[0040] The weight-average molecular weight of the hydrocarbon-based polymer electrolyte is more preferably 200,000 or more, even more preferably 220,000 or more, and particularly preferably 250,000 or more, and more preferably 800,000 or less, even more preferably 700,000 or less, and particularly preferably 600,000 or less.

[0041] The ion exchange capacity (IEC) of the hydrocarbon-based polymer electrolyte is preferably 1.9 meq / g or more, more preferably 2.0 meq / g or more, and particularly preferably 2.1 meq / g or more, and more preferably 3.0 meq / g or less, more preferably 2.9 meq / g or less, and particularly preferably 2.8 meq / g or less.

[0042] The ion exchange capacity (IEC) is the molar amount of ionic groups introduced per unit dry weight of a hydrocarbon-based polymer electrolyte, and a larger value indicates a larger amount of ionic groups introduced. In the present invention, the IEC is defined as a value determined by neutralization titration. The IEC calculated by neutralization titration can be calculated by the method described in the Examples.

[0043] The hydrocarbon-based polymer electrolyte is preferably crystalline. Here, "crystalline" means either that it can be crystallized by heating or that it has already crystallized. A polymer electrolyte is judged to be capable of crystallizing by heating when the heat of crystallization measured by differential scanning calorimetry (DSC) is 0.1 J / g or more. A polymer electrolyte is judged to be already crystallized when the degree of crystallization measured by wide-angle X-ray diffraction is 0.5% or more.

[0044] The heat of crystallization of the hydrocarbon-based polymer electrolyte is preferably 1.0 J / g or more, more preferably 3.0 J / g or more, even more preferably 5.0 J / g or more, and particularly preferably 10.0 J / g or more, with the upper limit preferably being 40.0 J / g or less.

[0045] The degree of crystallinity of the hydrocarbon-based polymer electrolyte is preferably 1.0% or more, more preferably 2.0% or more, and particularly preferably 3.0% or more, and is preferably 30.0% or less, more preferably 25.0% or less, and particularly preferably 20.0% or less.

[0046] The electrolyte membrane of the present invention preferably has a phase-separated structure. Phase-separated structures are broadly classified into four types: co-continuous, lamellar, cylindrical, and sea-island. Among these, the co-continuous phase-separated structure is most preferred. A phase-separated structure is easily formed by using an aromatic hydrocarbon-based block copolymer as the hydrocarbon-based polymer electrolyte, and in particular, a co-continuous phase-separated structure is easily formed by using a polyether ketone-based block copolymer.

[0047] As described above, the electrolyte membrane of the present invention has the property of being relatively water permeable, i.e., having a relatively low water vapor transmission rate. This property is one of the characteristics of an electrolyte membrane containing a hydrocarbon-based polymer electrolyte, and the present invention can be more effective when the water vapor transmission rate is low.

[0048] On the other hand, in electrolyte membranes, water vapor permeability is correlated with gas barrier properties and mechanical strength (dimensional stability at high humidity), and electrolyte membranes with low water vapor permeability have the advantage of having relatively good gas barrier properties and mechanical strength. Good gas barrier properties suppress crossover of fuel gases (hydrogen gas) and the like.

[0049] Furthermore, a low water vapor permeability of the electrolyte membrane can be expected to have the following effects: By reducing the amount of water produced at the cathode that permeates to the anode, for example, hydrogen deficiency at the anode can be suppressed, which can be expected to suppress the oxidation of carbon particles, a side reaction in the anode catalyst layer. Furthermore, by reducing the amount of water that permeates to the anode, the amount of water mixed into hydrogen gas can be reduced, which can be expected to reduce the frequency of hydrogen purging to discard water.

[0050] From the above viewpoint, the water vapor transmission rate (WR) of the electrolyte membrane in the present invention is 1.7×10 -5 cm 3 cm / (cm 2 ·cmHg·s) or less, and 1.5×10 -5 cm 3 cm / (cm 2 ·cmHg·s) or less is more preferable, and 1.0×10 -5 cm 3 cm / (cm 2 ·cmHg·s) or less, and more preferably 0.7×10 -5 cm 3 cm / (cm 2 It is particularly preferable that the lower limit is 5.0×10 -7 cm 3 cm / (cm 2 The water vapor permeability of "Nafion" (registered trademark) (manufactured by Chemours), a typical example of a fluorine-based polymer electrolyte membrane, is preferably 2×10 -5 cm 3 cm / (cm 2 ·cmHg·s).

[0051] Here, the water vapor transmission rate (WR) of the electrolyte membrane is the rate (cm) of water permeation from the cathode to the anode at 85°C when the cathode is set to 55% RH and the anode is set to 0% RH. 3 / s), electrolyte membrane thickness (cm), differential pressure (cmHg), and permeation area (cm 2 ) and the value calculated using the following formula: <Calculation formula> Water vapor permeability (cm 3 cm / (cm 2 cmHg s))= {Water vapor transmission rate (cm 3 / s) × electrolyte membrane thickness (cm)} / {(gas pressure difference (cmHg) × permeation area (cm 2 ))}.

[0052] The electrolyte membrane of the present invention preferably includes a porous substrate. An electrolyte membrane including a porous substrate can be produced, for example, by impregnating the porous substrate with a hydrocarbon-based polymer electrolyte. Examples of the electrolyte membrane configuration include a configuration having a hydrocarbon-based polymer electrolyte layer on one or both sides of a composite layer containing a porous substrate and a hydrocarbon-based polymer electrolyte, i.e., a "hydrocarbon-based polymer electrolyte layer / composite layer" configuration (I) or a "hydrocarbon-based polymer electrolyte layer / composite layer / hydrocarbon-based polymer electrolyte layer" configuration (II). Among these configurations, configuration (II) is preferred from the viewpoint of enhancing adhesion between the electrolyte membrane and both catalyst layers. Here, the hydrocarbon-based polymer electrolyte layer is a layer containing a hydrocarbon-based polymer electrolyte without including a porous substrate.

[0053] The thickness of the composite layer is preferably 10 to 90%, more preferably 15 to 80%, further preferably 20 to 70%, and particularly preferably 25 to 50%, of the total thickness of the electrolyte membrane taken as 100%. Here, the thickness of the composite layer means the thickness of the porous substrate.

[0054] Examples of the form of the porous substrate include woven fabric, nonwoven fabric, porous film, mesh fabric, etc. Examples of the material of the porous substrate include hydrocarbon-based porous substrates containing hydrocarbon-based polymers as the main component, and fluorine-based porous substrates containing fluorine-based polymers as the main component.

[0055] Hydrocarbon polymers include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyacrylate, polymethacrylate, polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), polyester, polycarbonate (PC), polysulfone (PSU), polyethersulfone (PES), polyphenylene oxide (PPO), polyarylene ether polymers, polyphenylene sulfide (PPS), polyphenylene sulfide sulfone, and polyparaphenylene (P PP), polyarylene polymers, polyarylene ketone, polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyarylene phosphine oxide, polyether phosphine oxide, polybenzoxazole (PBO), polybenzthiazole (PBT), polybenzimidazole (PBI), polyamide (PA), polyimide (PI), polyetherimide (PEI), polyimide sulfone (PIS), etc.

[0056] Examples of fluorine-based polymers include polytetrafluoroethylene (PTFE), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVdF), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy fluororesin (PFA), and ethylene-chlorotrifluoroethylene copolymer (ECTFE).

[0057] Among the above porous substrates, porous films and nonwoven fabrics are preferred. As the porous film, stretched porous film of polytetrafluoroethylene (PTFE) is preferred. As the nonwoven fabric, nonwoven fabric made of nanofiber fibers produced by electrospinning or the like is preferred. As the nanofiber fibers, polyethersulfone (PES), polyetherketone (PEK), polyetheretherketone (PEEK), polybenzimidazole (PBI), etc. are preferred.

[0058] The electrolyte membrane of the present invention may contain various additives, such as antioxidants, surfactants, radical scavengers, hydrogen peroxide decomposers, non-electrolytic polymers, elastomers, and fillers, within the range that does not impair the effects of the present invention.

[0059] [Catalyst layer] The cathode catalyst layer and the anode catalyst layer in the catalyst-coated electrolyte membrane according to an embodiment of the present invention each preferably contain at least platinum as a catalyst. The platinum catalysts contained in the cathode catalyst layer and the anode catalyst layer may be the same or different. The detailed description of platinum below is common to both the cathode catalyst layer and the anode catalyst layer unless otherwise specified, but the optimum platinum can be selected depending on the respective catalyst layers.

[0060] Platinum may be used alone or in combination with other catalytic metals such as ruthenium, rhodium, palladium, osmium, iridium, iron, lead, gold, silver, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum.

[0061] Examples of the combined use include alloys of platinum with other catalytic metals and core-shell catalysts. Examples of the alloys include platinum-ruthenium alloys, platinum-cobalt alloys, platinum-palladium alloys, platinum-nickel alloys, and platinum-cobalt-manganese alloys. Examples of the core-shell type include platinum-palladium alloys and platinum-gold alloys.

[0062] Since the larger the surface area of ​​the platinum catalyst, the higher the output, it is preferable to increase the surface area of ​​the platinum catalyst. From this viewpoint, it is preferable that the average particle size of the platinum particles is small. The average particle size of the platinum particles is preferably 8 nm or less, more preferably 6 nm or less, and particularly preferably 5 nm or less. On the other hand, the average particle size is preferably 1 nm or more.

[0063] From the viewpoint of increasing the surface area of ​​the platinum catalyst, it is preferable to use so-called "platinum-supported carbon particles" in which platinum is supported on carbon particles. Examples of the carbon particles include carbon black such as furnace black, acetylene black, and ketjen black, and graphitized versions of these carbon blacks.

[0064] The platinum loading rate in the platinum-loaded carbon particles is determined based on the target design, e.g., the platinum loading amount (mg / cm 2 ) and the thickness of the catalyst layer. For example, the platinum loading rate in the cathode catalyst layer is preferably 25% by mass or more and less than 60% by mass, and more preferably 30% by mass or more and 58% by mass or less. The platinum loading rate in the anode catalyst layer is preferably 25% by mass or more and less than 60% by mass, and more preferably 32% by mass or more and 58% by mass or less. Here, the platinum loading rate is the ratio of the platinum mass to the mass of the platinum-loaded carbon particles.

[0065] The cathode catalyst layer and the anode catalyst layer each preferably contain platinum-supported carbon particles. As mentioned above, generating a water concentration gradient between the cathode and anode is expected to improve power generation performance. By making the porosity of the cathode catalyst layer larger than that of the anode catalyst layer, a water concentration gradient is more likely to occur between the cathode and anode.

[0066] From the above viewpoint, it is preferable to appropriately control the BET specific surface area of ​​the carbon particles (carbon black) constituting the platinum-supported carbon particles used in the cathode catalyst layer and the anode catalyst layer. For example, it is preferable to use platinum-supported particles in which platinum is supported on carbon black with a relatively large BET specific surface area for the cathode catalyst layer. The BET specific surface area of ​​such carbon black is 400 m 2 / g or more is preferable, and 500m 2 / g or more is preferable, and 600m 2 / g or more is particularly preferred. The upper limit is 2000m 2 / g or less is preferred.

[0067] On the other hand, for the anode catalyst layer, it is preferable to use platinum-supported particles in which platinum is supported on carbon black with a relatively small BET specific surface area. 2 / g or less is preferable, and 300m 2 / g is more preferable, and 200m 2 The lower limit is particularly preferably less than 30 m / g. 2 / g or more is preferred.

[0068] Furthermore, from the viewpoint of generating a water concentration gradient between the cathode and anode, the mass per unit area of ​​the platinum-supported carbon particles contained in the catalyst layer is defined as "A (mg / cm 2 ) and the BET specific surface area of ​​the carbon particles is defined as "B(m 2 / g), the product "YC" of A and B in the cathode catalyst layer is preferably 80 or more, more preferably 100 or more, even more preferably 150 or more, and particularly preferably 200 or more. Moreover, YC is preferably 800 or less, more preferably 700 or less, and particularly preferably 600 or less.

[0069] On the other hand, the product "YA" of A and B in the anode catalyst layer is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, and particularly preferably 20 or less. Moreover, the YA is preferably 3 or more, more preferably 4 or more, and particularly preferably 5 or more.

[0070] In this specification, the values ​​of "YC" and "YA" are rounded off to the nearest integer.

[0071] It is also preferable to increase the difference between YC and YA, "YC-YA." For example, "YC-YA" is preferably 80 or more, more preferably 100 or more, even more preferably 150 or more, and particularly preferably 180 or more. The upper limit is preferably 780 or less.

[0072] The mass per unit area of ​​the carbon particles in the platinum-supported carbon particles contained in the catalyst layer, A (mg / cm 2) is the mass of platinum-supported carbon particles per unit area, D (mg / cm 2 The mass D of the platinum-loaded carbon particles can be calculated from the platinum amount per unit area (mg / cm) and the platinum loading rate E (%) of the platinum-loaded carbon particles using the following formula: 2 ) by the platinum loading rate (E / 100). A=D×(1-E / 100) Specifically, the platinum amount is "CPt" in the cathode catalyst layer and "APt" in the anode catalyst layer, as shown in Table 2 below and below.

[0073] In the catalyst-layered electrolyte membrane according to an embodiment of the present invention, the ratio (APt / CPt) of the platinum amount per unit area in the anode catalyst layer (APt) to the platinum amount per unit area in the cathode catalyst layer (CPt) is preferably less than 0.9. By making the platinum amount in the anode catalyst layer (APt) less than the platinum amount in the cathode catalyst layer (CPt), platinum elution from the cathode is suppressed, thereby suppressing a decrease in the output of the fuel cell. The mechanism behind this is unclear, but is presumed to be as follows.

[0074] During the "start-and-shutdown" process, which is the process of starting up a fuel cell and shutting down its operation, degradation of the cathode catalyst can cause a decrease in output. This decrease in output is thought to be due to the oxygen reduction reaction that occurs locally at the anode when air gets into the anode, resulting in the formation of a double cell. This oxygen reduction reaction in the anode can be suppressed by reducing the amount of platinum in the anode, which is thought to result in the suppression of catalyst degradation at the cathode.

[0075] The ratio (APt / CPt) is more preferably less than 0.6, even more preferably less than 0.5, and particularly preferably less than 0.4, while the ratio (APt / CPt) is preferably 0.04 or more, more preferably 0.05 or more, and particularly preferably 0.1 or more.

[0076] The amount of platinum per unit area (CPt) of the cathode catalyst layer is 0.15 mg / cm 2More than 1.3mg / cm 2 Preferably less than 0.2 mg / cm 2 More than 1.0mg / cm 2 Less than 0.25 mg / cm is more preferred 2 More than 0.9 mg / cm 2 Less than 1000 is particularly preferred.

[0077] The amount of platinum per unit area (APt) of the anode catalyst layer is 0.03 mg / cm 2 More than 0.3mg / cm 2 Less than 0.04 mg / cm is preferred. 2 More than 0.25mg / cm 2 Less than 0.05 mg / cm is more preferred. 2 More than 0.2mg / cm 2 Less than 1000 is particularly preferred.

[0078] From the viewpoint of reducing fuel cell costs, it is desirable to reduce the amount of expensive platinum used. To achieve this, it is necessary to consider a design that allows high power generation performance to be obtained even when the amount of platinum in the catalyst layer is reduced. In the catalyst-coated electrolyte membrane according to the embodiment of the present invention, when the total amount of CPt and APt is relatively small, for example, 1.0 mg / cm 2 That is, in one embodiment of the present invention, high power generation performance can be obtained even if the total amount of CPt and APt is less than 1.0 mg / cm. 2 Less than 0.7 mg / cm is preferred 2 Less than 0.6 mg / cm is more preferred. 2 The lower limit is particularly preferably less than 0.2 mg / cm. 2 The above is preferable.

[0079] The cathode catalyst layer and the anode catalyst layer each preferably further contain a polymer electrolyte. Examples of the polymer electrolyte that can be used include fluorine-based polymer electrolytes as described below and hydrocarbon-based polymer electrolytes as described above. Among these, fluorine-based polymer electrolytes are preferred from the viewpoints of gas diffusibility and chemical durability, and perfluorocarbon sulfonic acid polymers are more preferred.

[0080] A fluoropolymer electrolyte is a fluoropolymer having ionic groups. A fluoropolymer is a polymer in which most or all of the hydrogen atoms in the alkyl and / or alkylene groups in the molecule are substituted with fluorine atoms.

[0081] Examples of fluorine-based polymer electrolytes include perfluorocarbon sulfonic acid-based polymers, perfluorocarbon phosphonic acid-based polymers, trifluorostyrene sulfonic acid-based polymers, trifluorostyrene phosphonic acid-based polymers, ethylene tetrafluoroethylene-g-styrene sulfonic acid-based polymers, ethylene-tetrafluoroethylene copolymers, and polyvinylidene fluoride-perfluorocarbon sulfonic acid-based polymers.

[0082] Representative examples of fluorine-based polymer electrolytes include commercially available products such as "Nafion" (registered trademark) (manufactured by Chemours), "Flemion" (registered trademark) (manufactured by AGC Corporation), and "Aciplex" (registered trademark) (manufactured by Asahi Kasei Corporation).

[0083] The content of the polymer electrolyte in the cathode catalyst layer and the anode catalyst layer is preferably 30 to 350 mass%, more preferably 50 to 300 mass%, even more preferably 60 to 250 mass%, and particularly preferably 70 to 200 mass%, relative to 100 mass% of the catalyst. When the cathode catalyst layer and the anode catalyst layer each contain platinum-supported carbon particles, the ratio (I / C) of the mass of the carbon particles constituting the platinum-supported carbon particles to the mass of the polymer electrolyte is preferably 0.6 to 1.4, more preferably 0.7 to 1.3, and particularly preferably 0.8 to 1.2, in both the cathode catalyst layer and the anode catalyst layer.

[0084] [Methods of manufacturing electrolyte membranes and catalyst-layered electrolyte membranes] Hereinafter, methods for manufacturing an electrolyte membrane and a catalyst layer-equipped electrolyte membrane will be described, but the present invention is not limited to these manufacturing methods.

[0085] The electrolyte membrane can be produced, for example, by applying a polymer electrolyte solution to a membrane-forming substrate such as a glass plate or a PET film, followed by drying. When the electrolyte membrane includes a porous substrate, the membrane-forming substrate can be impregnated with the polymer electrolyte solution by laminating a porous substrate onto the polymer electrolyte solution applied thereto, and then the porous substrate can be coated with the polymer electrolyte solution and dried. This production method can provide the electrolyte membrane of the above-mentioned configuration (II).

[0086] In some cases, the polymer electrolyte is one in which the ionic group forms a salt with an alkali metal or alkaline earth metal cation, and in this case, after forming the electrolyte membrane or composite membrane on the membrane-forming substrate, it is preferable to perform an acid treatment to exchange the alkali metal or alkaline earth metal cation for a proton. Here, the acid treatment can be performed by a known method.

[0087] Examples of methods for laminating a catalyst layer on an electrolyte membrane include a coating method, a transfer method, and a combination of a coating method and a transfer method. These methods are not particularly limited, and any known method can be used.

[0088] Examples of the coating method include a method in which a cathode catalyst layer coating liquid is applied to an electrolyte membrane and dried to form a cathode catalyst layer, and an anode catalyst layer is formed by applying an anode catalyst layer coating liquid to the opposite side of the electrolyte membrane and drying the coating liquid. The order in which the cathode catalyst layer and the anode catalyst layer are stacked may be reversed. When the coating method is employed, it is preferable to stack a support substrate such as a PET film on the side of the electrolyte membrane opposite to the side to which the catalyst layer coating liquid is applied.

[0089] The transfer method involves preparing a catalyst decal by laminating a catalyst layer on a transfer substrate, placing the catalyst layer of this catalyst decal opposite the electrolyte membrane, and hot pressing to transfer the catalyst layer to the electrolyte membrane. Examples of transfer substrates include polytetrafluoroethylene film, polyethylene terephthalate film, and polyimide film.

[0090] Specifically, one method involves preparing a cathode catalyst decal in which a cathode catalyst layer is laminated on a transfer substrate, and an anode catalyst decal in which an anode catalyst layer is laminated on a transfer substrate, and then sandwiching the electrolyte membrane between the cathode catalyst decal and the anode catalyst decal and hot pressing them.

[0091] A combined application method and transfer method may include a method in which an anode catalyst layer coating liquid is first applied to an electrolyte membrane and dried to form an anode catalyst layer, and then a cathode catalyst decal is attached to the opposite surface of the electrolyte membrane and hot-pressed to transfer the cathode catalyst layer. Alternatively, a method may be used in which the cathode catalyst layer coating liquid is applied and then the anode catalyst layer is transferred.

[0092] A preferred method for preparing a catalyst-coated electrolyte membrane according to an embodiment of the present invention is to apply a coating liquid for an anode catalyst layer to an electrolyte membrane, dry the coating liquid, and then transfer the anode catalyst layer onto the opposite side of the electrolyte membrane by laminating a cathode catalyst decal on the opposite side of the electrolyte membrane and hot pressing the decal. The anode catalyst layer in the present invention is relatively thin, so a more stable, uniform membrane can be formed by directly applying the decal to the electrolyte membrane. On the other hand, the cathode catalyst layer is relatively thick, so a more stable, uniform membrane can be formed by laminating the decal by a transfer method.

[0093] The catalyst-coated electrolyte membrane according to the embodiment of the present invention includes a configuration in which a gas diffusion electrode, in which a catalyst layer is laminated on a gas diffusion layer, and an electrolyte membrane are joined via the catalyst layer. Details will be described later.

[0094] [Membrane electrode assembly] The membrane electrode assembly (MEA) includes a catalyst-coated electrolyte membrane according to an embodiment of the present invention and gas diffusion layers disposed on both sides of the electrolyte membrane. Specifically, a cathode gas diffusion layer is disposed and bonded to the cathode catalyst layer side of the catalyst-coated electrolyte membrane, and an anode gas diffusion layer is disposed and bonded to the anode catalyst layer side. Hereinafter, the cathode gas diffusion layer and the anode gas diffusion layer are collectively referred to as "gas diffusion layers."

[0095] The gas diffusion layer is generally made of a material having gas permeability and electron conductivity. The gas diffusion layer preferably includes a carbon sheet and a microporous layer. The microporous layer is disposed on the catalyst layer side.

[0096] As the carbon sheet, for example, a porous body containing carbon fiber such as a carbon fiber fabric, carbon paper, or a carbon fiber nonwoven fabric, or a carbonaceous porous foam containing carbon fiber is preferably used. Among these, a porous body containing carbon fiber is preferred because of its excellent corrosion resistance, and carbon paper is more preferred in terms of the springiness of the carbon sheet.

[0097] The microporous layer is preferably composed of a water-repellent resin such as polytetrafluoroethylene (PTFE) and a conductive filler. Carbon powder is preferred as the conductive filler. Examples of carbon powder include carbon blacks such as furnace black, acetylene black, lamp black, and thermal black; graphites such as flake graphite, flaky graphite, amorphous graphite, artificial graphite, expanded graphite, and flake graphite; carbon nanotubes; linear carbon; and milled carbon fibers. Of these, carbon black is preferred.

[0098] The thickness of the gas diffusion layer is preferably in the range of 50 to 300 μm, more preferably in the range of 60 to 200 μm, and particularly preferably in the range of 70 to 180 μm.

[0099] The cathode gas diffusion layer and the anode gas diffusion layer may be made of the same material, composition and thickness, or may be different.

[0100] [Membrane electrode assembly manufacturing method] Examples of methods for producing a membrane electrode assembly include (I) a method of bonding a gas diffusion layer to each side of a catalyst layer-equipped electrolyte membrane, and (II) a method of producing a gas diffusion electrode in which a catalyst layer is laminated on one side of a gas diffusion layer, and sandwiching the electrolyte membrane between a pair of gas diffusion electrodes and bonding them via the catalyst layer.

[0101] [Application example] The catalyst-coated electrolyte membrane and membrane electrode assembly according to the embodiment of the present invention can be used in, for example, electrochemical applications, such as fuel cells, water electrolysis devices, and electrochemical hydrogen compression devices. Of these, fuel cells are preferred. [Example]

[0102] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. The various measurement conditions are as follows.

[0103] (1) Molecular weight of the polymer The number-average molecular weight and weight-average molecular weight of the polymer solution were measured by GPC. A Tosoh HLC-8022 GPC was used as an integrated UV detector and differential refractometer. Two Tosoh TSK gel SuperHM-H GPC columns (6.0 mm inner diameter, 15 cm length) were used. Measurements were performed in N-methyl-2-pyrrolidone (containing 10 mmol / L lithium bromide) at a flow rate of 0.2 mL / min, and the number-average molecular weight and weight-average molecular weight were calculated in terms of standard polystyrene.

[0104] (2) Ion exchange capacity (IEC) Measurements were made by the neutralization titration method shown in i) to iv) below. Measurements were made three times and the average value was taken. i) After the proton exchange and thorough washing with pure water, the polymer electrolyte was wiped to remove moisture, and then vacuum dried at 100°C for 12 hours or more, and the dry weight was determined. ii) 50 mL of a 5 wt % aqueous solution of sodium sulfate was added to the block copolymer, and the mixture was allowed to stand for 12 hours to carry out ion exchange. iii) The resulting sulfuric acid was titrated with 0.01 mol / L aqueous sodium hydroxide solution. 0.1 w / v% commercially available phenolphthalein solution for titration was added as an indicator, and the point at which the color turned pale reddish purple was defined as the endpoint. iv) IEC was calculated using the following formula: IEC (meq / g) = [concentration of sodium hydroxide solution (mmol / ml) × amount dropped (ml)] / dry weight of sample (g).

[0105] (3) Measurement of the thickness of the electrolyte membrane and catalyst layer The cross section of the catalyst layer-attached electrolyte membrane was observed with a scanning electron microscope (SEM) under the following conditions, and the thicknesses of the electrolyte membrane and catalyst layer were measured from the obtained images. Equipment: Field emission scanning electron microscope (FE-SEM) S-4800 (Hitachi High-Technologies) Acceleration voltage: 2.0 kV Pretreatment: Cross-sectional samples prepared using the BIB method were coated with Pt and then measured. BIB method: A cross-sectional specimen preparation device that uses an argon ion beam. A shielding plate is placed directly above the specimen, and a broad argon ion beam is irradiated from above to etch the specimen, creating an observation and analysis surface (cross section).

[0106] The thicknesses of the composite layer and the hydrocarbon-based polymer electrolyte layer that constitute the electrolyte membrane were also measured by the above-mentioned method.

[0107] (4) Measurement of the amount of platinum in the catalyst layer First, the basis weight of the catalyst layer (calculated from the area and mass) was determined. When a catalyst decal was used to form the catalyst layer, the basis weight of the catalyst layer was determined by subtracting the basis weight of the substrate from the basis weight of the catalyst decal. When a catalyst layer was formed by directly applying a catalyst layer coating liquid to an electrolyte membrane, the basis weight of the catalyst layer was determined by subtracting the basis weight of the electrolyte membrane from the basis weight of this laminate (electrolyte membrane / catalyst layer). Using the following fluorescent X-ray measurement device, the platinum concentrations (wt%) of the catalyst decal and the laminate were measured, and the platinum amount was calculated by multiplying the basis weight of the catalyst layer determined above by the platinum concentration. Five points were measured, and the average value was used to determine the platinum amount (mg / cm) of the catalyst layer. 2 ) was decided. <X-ray fluorescence measurement device> Manufacturer: Rigaku Corporation ·Product name: NFX DE Measurement method: FP (fundamental parameter) method Tube voltage: Continuous measurement under two conditions: 6.5kV and 35kV Tube current: Automatic (The device automatically adjusts the X-ray intensity to the extent that the current is proportional) Measurement time: 100 seconds under all voltage conditions = 200 seconds in total.

[0108] (5) Measurement of BET specific surface area of ​​carbon particles (carbon black) The measurement was performed in accordance with JIS K6217-2:2017. Specifically, a container containing degassed carbon black was immersed in liquid nitrogen, and the amount of nitrogen adsorbed on the surface of the carbon black at equilibrium was measured. From this value, the specific surface area (m 2 / g) was calculated.

[0109] (6) Measurement of water vapor permeability of electrolyte membrane The stack, in which SGL gas diffusion electrodes 24BC were placed on both sides of the electrolyte membrane to be measured, was used as a fuel cell evaluation cell (electrode area 40 cm 2 ) to prepare a sample cell. The cell was heated to 85°C, and a mixed gas of nitrogen and water vapor adjusted to 85°C and 55% RH was introduced into the cathode inlet of the cell at 80 NL / h, and dry hydrogen was introduced into the anode inlet at 80 NL / h in parallel with the cathode gas. The water discharged from the cathode outlet and the anode outlet was weighed using a precision balance, and the water vapor transmission rate (cm) from the cathode to the anode was calculated. 3 / s) and calculate the water vapor permeability (cm 3 cm / (cm 2 ·cmHg·s) was calculated. <Calculation formula> Water vapor permeability (cm 3 cm / (cm 2 cmHg s))= {Water vapor transmission rate (cm 3 / s) × electrolyte membrane thickness (cm)} / {(gas pressure difference (cmHg) × permeation area (cm 2 ))}.

[0110] (7) Evaluation of power generation performance To evaluate the power generation performance, a membrane electrode assembly (MEA) was fabricated. <Fabrication of MEA> A commercially available gas diffusion layer 24BCH manufactured by SGL was overlaid on both sides of the electrolyte membrane with a catalyst layer prepared in the examples and comparative examples, and heat pressing was performed at 160 °C and 4.5 Ma for 5 minutes to fabricate an MEA. Using this MEA, the power generation performance was evaluated in the following manner. <Evaluation of Power Generation Performance> The MEA was set in a JARI standard cell "Ex-1" manufactured by Eiwa Corporation ( electrode area 25 cm 2 ) to make a power generation evaluation module. Hydrogen gas was supplied as a fuel gas to the anode electrode, and air was supplied as an oxidizing gas to the cathode electrode. Under the following conditions, the current was swept from 0 A / cm 2 to 2.5 A / cm 2 until the voltage became 0.2 V or less, and the voltages at current densities of 1.5 A / cm 2 and 2.5 A / cm 2 were read and evaluated. The higher these voltages, the better the power generation performance. Also, the voltage drop rate due to the increase in current density was obtained by inserting the voltage (V0) at a current density of 1.5 A / cm 2 and the voltage (V1) at 2.5 A / cm 2 into the following formula. The smaller the above voltage drop rate, the better the power generation performance. (Voltage drop rate (%)) = (V0 - V1) / V0 × 100 <Power Generation Conditions> · Electronic load device; Electronic load device "PLZ664WA" manufactured by Kikusui Electronics Industry Co., Ltd. [[ID=2⑨]]· Cell temperature; 80 °C · Relative humidity of the supplied gas (hydrogen gas and air); 30% RH · Back pressure of the supplied gas (hydrogen gas and air): 150 kPa · Gas utilization rate; 70% of the stoichiometry for the anode and 40% of the stoichiometry for the cathode.

[0111] [Synthesis of Hydrocarbon-Based Polymer Electrolyte] [Synthesis Example 1] (Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP) represented by the following chemical formula (G1)) A 500 mL flask equipped with a stirrer, thermometer, and distillation tube was charged with 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate, and 0.50 g of p-toluenesulfonic acid monohydrate and dissolved. The mixture was then stirred at 78-82°C for 2 hours. The internal temperature was gradually raised to 120°C and heated until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling to room temperature, the reaction mixture was diluted with ethyl acetate, and the organic layer was washed with 100 mL of 5% aqueous potassium carbonate solution and separated. The solvent was then evaporated. 80 mL of dichloromethane was added to the residue to precipitate crystals, which were filtered and dried to obtain 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane, represented by the following chemical formula (G1): GC analysis of the crystals revealed that they were 99.9% 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane and 0.1% 4,4'-dihydroxybenzophenone. The purity was 99.9%.

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[0113] [Synthesis Example 2] (Synthesis of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone represented by the following chemical formula (G2)) 109.1 g of 4,4'-difluorobenzophenone (Sigma-Aldrich Japan, reagent) was reacted in 150 mL of fuming sulfuric acid (50% SO3) (Fujifilm Wako Pure Chemical Industries, Ltd., reagent) at 100°C for 10 hours. The mixture was then poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride (NaCl) was added to precipitate the product. The resulting precipitate was filtered and recrystallized from an aqueous ethanol solution to obtain disodium-3,3'-disulfonate-4,4'-difluorobenzophenone, represented by the following chemical formula (G2). The purity was 99.3%.

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[0115] [Synthesis Example 3] (Synthesis of nonionic oligomer a1 represented by the following general formula (G3)) A 2,000 mL stainless steel polymerization reactor equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap was charged with 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.83 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and 20.3 g of 4,4'-difluorobenzophenone (Aldrich reagent, 93 mmol). After nitrogen purge, 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene were added. The mixture was dehydrated at 150 °C, then heated to remove toluene, and polymerized at 170 °C for 3 hours. Purification by reprecipitation with a large amount of methanol yielded nonionic oligomer a1 with a terminal hydroxyl group. The number-average molecular weight of this nonionic oligomer a1 with a terminal hydroxyl group was 10,000.

[0116] A 500 mL three-neck flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap was charged with 1.1 g of potassium carbonate (Sigma-Aldrich Japan (same company) reagent, 8 mmol) and 20.0 g (2 mmol) of the terminal hydroxyl form of the above nonionic oligomer a1. After replacing the atmosphere with nitrogen, 100 mL of NMP and 30 mL of toluene were added. The mixture was dehydrated at 100 °C and then heated to remove the toluene. 2.2 g of hexafluorobenzene (Sigma-Aldrich Japan (same company) reagent, 12 mmol) was added, and the reaction was carried out at 105 °C for 12 hours. Purification was carried out by reprecipitation with a large amount of isopropyl alcohol to obtain nonionic oligomer a1 (terminal: fluoro group) represented by the following general formula (G3). The number-average molecular weight was 11,000.

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[0118] [Synthesis Example 4] (Synthesis of ionic oligomer a2 represented by the following general formula (G4)) A 2,000 mL stainless steel polymerization reactor equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap was charged with 27.6 g of potassium carbonate (Sigma-Aldrich Japan (same manufacturer), reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.3 g of 4,4'-biphenol (Sigma-Aldrich Japan (same manufacturer), reagent, 50 mmol), 39.3 g (93 mmol) of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2, and 17.9 g of 18-crown-6 (Fujifilm Wako Pure Chemical Industries, Ltd., 82 mmol). After nitrogen substitution, 300 mL of NMP and 100 mL of toluene were added, and the mixture was dehydrated at 150°C. The mixture was then heated to remove the toluene, and polymerization was carried out at 170°C for 6 hours. The product was purified by reprecipitation with a large amount of isopropyl alcohol to obtain an ionic oligomer a2 (terminal: hydroxy group) represented by the following general formula (G4). The number average molecular weight was 16,000. In general formula (G4), M represents a hydrogen atom, Na, or K.

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[0120] (In general formula (G4), M represents H, Na, or K.) [Synthesis Example 5] (Synthesis of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate represented by the following chemical formula (G5)) 245g (2.1mol) of chlorosulfonic acid was placed in a 3L three-neck flask equipped with a stirrer and condenser, followed by 105g (420mmol) of 2,5-dichlorobenzophenone, and the reaction was carried out in a 100°C oil bath for 8 hours. After the specified time, the reaction solution was slowly poured onto 1,000g of crushed ice and extracted with ethyl acetate. The organic layer was washed with brine and dried over magnesium sulfate, after which the ethyl acetate was distilled off to obtain pale yellow crude crystals of 3-(2,5-dichlorobenzoyl)benzenesulfonic acid chloride. The crude crystals were used directly in the next step without purification.

[0121] 41.1 g (462 mmol) of 2,2-dimethyl-1-propanol (neopentyl alcohol) was added to 300 mL of pyridine and cooled to approximately 10°C. The crude crystals obtained above were gradually added over approximately 30 minutes. After the entire amount was added, the mixture was stirred for an additional 30 minutes to allow the reaction to proceed. After the reaction, the reaction solution was poured into 1,000 mL of aqueous hydrochloric acid, and the precipitated solid was collected. The resulting solid was dissolved in ethyl acetate, washed with aqueous sodium bicarbonate and brine, dried over magnesium sulfate, and the ethyl acetate was distilled off to obtain crude crystals. These were recrystallized from methanol to obtain white crystals of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate, represented by the following chemical formula (G5).

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[0123] [Synthesis Example 6] (Synthesis of nonionic group oligomer a3 represented by the following general formula (G6)) 49.4 g (0.29 mol) of 2,6-dichlorobenzonitrile, 88.4 g (0.26 mol) of 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and 47.3 g (0.34 mol) of potassium carbonate were weighed into a 1 L three-neck flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube, and a three-way stopcock for nitrogen inlet. After purging with nitrogen, 346 mL of sulfolane and 173 mL of toluene were added and stirred. The flask was placed in an oil bath and heated to reflux at 150 °C. The water produced by the reaction was azeotroped with toluene and removed from the system via a Dean-Stark tube. After approximately 3 hours, almost no water was produced. The reaction temperature was gradually increased to remove most of the toluene, and the reaction was continued at 200 °C for 3 hours. Next, 12.3 g (0.072 mol) of 2,6-dichlorobenzonitrile was added, and the mixture was further reacted for 5 hours.

[0124] The resulting reaction solution was allowed to cool and then diluted with 100 mL of toluene. The precipitated inorganic compound by-product was filtered off, and the filtrate was poured into 2 L of methanol. The precipitated product was filtered off, collected, dried, and then dissolved in 250 mL of tetrahydrofuran. This was reprecipitated in 2 L of methanol to obtain nonionic oligomer a3 represented by the following general formula (G6). The number-average molecular weight was 11,000.

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[0126] [Synthesis Example 7] (Synthesis of precursor b5' of polyethersulfone-based block copolymer consisting of a segment represented by the following chemical formula (G8) and a segment represented by the following formula (G9)) 1.62 g of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide were mixed and adjusted to 70° C. 2.15 g of 2,2′-bipyridyl was added thereto, and the mixture was stirred at the same temperature for 10 minutes to prepare a nickel-containing solution.

[0127] To this solution, 1.49 g of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) and 0.50 g of Sumikaexcel PES5200P (Sumitomo Chemical Co., Ltd., Mn = 40,000, Mw = 94,000), represented by the following general formula (G7), were dissolved in 5 mL of dimethyl sulfoxide. 1.23 g of zinc powder was added and the temperature was adjusted to 70°C. The nickel-containing solution was poured into this solution, and a polymerization reaction was carried out at 70°C for 4 hours. The reaction mixture was added to 60 mL of methanol, followed by the addition of 60 mL of 6 mol / L hydrochloric acid and stirring for 1 hour. The precipitated solid was separated by filtration and dried to obtain a grayish-white precursor b5' of a polyethersulfone-based block copolymer containing segments represented by the following chemical formula (G8) and the following general formula (G9). The weight-average molecular weight was 230,000.

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[0131] [Polymer electrolyte solution A] Polymer electrolyte solution A consisting of polyether ketone-based block copolymer b1 A 500 mL three-neck flask equipped with a stirrer, nitrogen inlet, and Dean-Stark trap was charged with 0.56 g (4 mmol) of potassium carbonate (Sigma-Aldrich Japan (same) reagent) and 16 g (1 mmol) of ionic oligomer a2 (terminated with hydroxyl groups) obtained in Synthesis Example 4. After nitrogen substitution, 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane were added. The mixture was dehydrated at 100 °C, then heated to remove the cyclohexane. 11 g (1 mmol) of nonionic oligomer a1 (terminated with fluoro groups) obtained in Synthesis Example 3 was added and the reaction was carried out at 105 °C for 24 hours. Purification by reprecipitation into a large amount of isopropyl alcohol yielded polyetherketone-based block copolymer b1. The weight-average molecular weight of this block copolymer was 340,000 and the ion exchange capacity (IEC) was 2.1.

[0132] The resulting 5% by mass N-methylpyrrolidone (NMP) solution containing the polyetherketone-based block copolymer b1 was centrifuged directly at 25°C for 30 minutes at a centrifugal force of 20,000 G in a Kubota Manufacturing Co., Ltd. inverter compact high-speed refrigerated centrifuge (model 6930) equipped with an angle rotor RA-800. The precipitated solids (cake) and the supernatant (coating solution) were separated cleanly, and the supernatant was collected. The mixture was then distilled under reduced pressure at 80°C while stirring, and pressure filtered using a 1 μm polypropylene filter to obtain polymer electrolyte solution A.

[0133] [Polymer electrolyte solution B] Polymer electrolyte solution B consisting of polyether ketone block copolymer b2 Polyetherketone-based block copolymer b2 was synthesized in the same manner as the polyetherketone-based block copolymer b1, except that 20 g (1.25 mmol) of ionic oligomer a2 obtained in Synthesis Example 4 was used. The weight-average molecular weight of this block copolymer was 370,000, and the ion exchange capacity (IEC) was 2.4. Polymer electrolyte solution B was also obtained in the same manner as polymer electrolyte solution A, except that polyetherketone-based block copolymer b2 was used instead of polyetherketone-based block copolymer b1.

[0134] [Polymer electrolyte solution C] Polymer electrolyte solution C consisting of polyether ketone-based block copolymer b3 Polyetherketone-based block copolymer b3 was synthesized in the same manner as polyetherketone-based block copolymer b1, except that 25.6 g (1.6 mmol) of ionic oligomer a2 obtained in Synthesis Example 4 was used. The weight-average molecular weight of this block copolymer was 390,000, and the ion exchange capacity (IEC) was 2.7. Polymer electrolyte solution C was also obtained in the same manner as polymer electrolyte solution A, except that polyetherketone-based block copolymer b3 was used instead of polyetherketone-based block copolymer b1.

[0135] [Polymer electrolyte solution D] Polymer electrolyte solution D consisting of a polyarylene-based block copolymer represented by the following formula (G10): 540 ml of dry N,N-dimethylacetamide (DMAc) was added under nitrogen to a mixture of 135.0 g (0.336 mol) of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate, 40.7 g (5.6 mmol) of the nonionic group oligomer a3 synthesized in Synthesis Example 6, 6.71 g (16.8 mmol) of 2,5-dichloro-4'-(1-imidazolyl)benzophenone, 6.71 g (10.3 mmol) of bis(triphenylphosphine)nickel dichloride, 35.9 g (0.137 mol) of triphenylphosphine, 1.54 g (10.3 mmol) of sodium iodide, and 53.7 g (0.821 mol) of zinc.

[0136] The reaction system was heated with stirring (finally heated to 79°C) and reacted for 3 hours. An increase in viscosity was observed during the reaction. The polymerization reaction solution was diluted with 730 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.

[0137] The filtrate was concentrated using an evaporator, and 43.8 g (0.505 mol) of lithium bromide was added to the filtrate. The mixture was allowed to react at an internal temperature of 110°C for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature and poured into 4 L of acetone to coagulate. The coagulated product was collected by filtration, air-dried, pulverized in a mixer, and washed with 1,500 mL of 1N hydrochloric acid while stirring. After filtration, the product was washed with ion-exchanged water until the pH of the washings reached 5 or higher, and then dried overnight at 80°C to obtain polyarylene-based block copolymer b4 represented by the following formula (G10). This block copolymer had a weight-average molecular weight of 190,000 and an ion-exchange capacity (IEC) of 2.0. The obtained polyarylene-based block copolymer b4 was dissolved in an organic solvent (N-methyl-2-pyrrolidone / methanol = 30 / 70 (mass%)) to a concentration of 0.1 g / g, to obtain polymer electrolyte solution D.

[0138] [ka]

[0139] [Polymer electrolyte solution E] Polymer electrolyte solution E consisting of polyethersulfone-based block copolymer b5 0.23 g of the block copolymer precursor b5' obtained in Synthesis Example 7 was weighed and added to a mixed solution of 0.16 g of lithium bromide monohydrate and 8 mL of NMP, followed by a reaction at 120°C for 24 hours. The reaction mixture was poured into 80 mL of 6 mol / L hydrochloric acid and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain a gray-white polyethersulfone-based block copolymer b5 composed of a segment represented by the general formula (G9) and a segment represented by the following chemical formula (G11). The weight-average molecular weight of this block copolymer was 190,000 and the ion exchange capacity (IEC) was 2.0. The obtained polyethersulfone-based block copolymer b5 was dissolved in an organic solvent of N-methyl-2-pyrrolidone / methanol = 30 / 70 (mass %) to a concentration of 0.1 g / g, to obtain a polymer electrolyte solution E.

[0140] [ka]

[0141] <Electrolyte membrane manufacturing> Electrolyte membranes A to E were prepared in the following manner.

[0142] [Production Example 1: Preparation of electrolyte membrane A] A coating solution was prepared by dissolving 0.26 g of polyoxyethylene ether surfactant "Ftergent" (registered trademark) 208G (manufactured by Neos Corporation) in polymer electrolyte solution A. This coating solution was cast onto a PET film, and a porous substrate, an expanded PTFE porous film ("Tetratex" (registered trademark) TX1356 manufactured by Donaldson), was laminated thereon, thoroughly impregnated, and then dried at 100°C for 2 hours. The above coating solution was cast onto the upper surface of the dried membrane and dried at 100°C for 2 hours to obtain an electrolyte membrane precursor. This precursor was then immersed in a 10% by mass aqueous sulfuric acid solution at 80°C for 24 hours to undergo proton substitution and deprotection reactions, followed by immersion in a large excess of pure water for 24 hours, thorough washing, and drying to obtain electrolyte membrane A. The total thickness of this electrolyte membrane A was 8 μm, and the thickness ratio of the composite layer (layer in which the porous substrate was impregnated with the polymer electrolyte) to the total thickness was approximately 30%.

[0143] [Production Example 2: Preparation of electrolyte membrane B] An electrolyte membrane B was obtained in the same manner as in Production Example 1, except that polymer electrolyte solution B was used instead of polymer electrolyte solution A.

[0144] [Production Example 3: Preparation of electrolyte membrane C] An electrolyte membrane C was obtained in the same manner as in Production Example 1, except that polymer electrolyte solution C was used instead of polymer electrolyte solution A.

[0145] [Production Example 4: Preparation of electrolyte membrane D] An electrolyte membrane D was obtained in the same manner as in Production Example 1, except that polymer electrolyte solution D was used instead of polymer electrolyte solution A.

[0146] [Production Example 5: Preparation of electrolyte membrane E] An electrolyte membrane E was obtained in the same manner as in Production Example 1, except that polymer electrolyte solution E was used instead of polymer electrolyte solution A.

[0147] [Electrolyte membrane F: Fluorine-based polymer electrolyte membrane] As a reference example, the commercially available "Nafion" (registered trademark) (manufactured by Chemours) NR211 (film thickness 25 μm) was used as the electrolyte membrane F.

[0148] <Measurement results of water vapor permeability of electrolyte membrane> The water vapor transmission rates of the electrolyte membranes A to F obtained above were measured at 85° C. and 55% RH. The results are shown in Table 1.

[0149] [Table 1]

[0150] The above results show that electrolyte membranes A to E, which are electrolyte membranes containing a hydrocarbon-based polymer electrolyte, have a lower water vapor permeability than fluorine-based polymer electrolyte membrane F. In this example, several types of electrolyte membrane A, which has the lowest water vapor permeability, were prepared by varying the membrane thickness as follows, and were used to fabricate catalyst layer-equipped electrolyte membranes.

[0151] [Changes in electrolyte membrane A thickness] In Production Example 1, the amount of coating of the coating liquid containing the polymer electrolyte solution A was adjusted to prepare electrolyte membranes with total thicknesses of 12 μm and 25 μm. The same expanded PTFE porous film was used as in Production Example 1. In the following examples, the electrolyte membrane prepared in Production Example 1 with a total thickness (TM) of 8 μm was designated "A1," the electrolyte membrane with a total thickness (TM) of 12 μm was designated "A2," and the electrolyte membrane with a total thickness (TM) of 25 μm was designated "A3."

[0152] [Creating the catalyst layer] In preparing the catalyst layer, the following platinum-supported carbon particles and polymer electrolyte (fluorine-based polymer electrolyte) were used.

[0153] [Platinum-supported carbon particles] The type of platinum-supported carbon particles used, the BET specific surface area of ​​the carbon particles (B (m 2 / g)" and platinum loading rate "E (%)" are shown below. The platinum loading rate "E (%)" shown here is the same as the "Platinum loading rate (E)" in Table 2.

[0154] <Tanaka Kikinzoku Kogyo Co., Ltd. TEC10EA series>: Platinum particles are supported on carbon particles (graphitized Ketjen black), and the BET specific surface area (B) of the carbon particles is 140 m 2 / g. TEC10EA20E (platinum loading rate 20% by mass) TEC10EA30E (platinum loading rate 30% by mass) TEC10EA40E (platinum loading rate 40% by mass) TEC10EA50E (platinum loading rate 50% by mass) <Tanaka Kikinzoku Kogyo Co., Ltd. TEC10E series>: Platinum particles are supported on carbon particles (Ketjen Black), and the BET specific surface area "B" of the carbon particles is 800m 2 / g. TEC10E20E (platinum loading rate 20% by mass) TEC10E30E (platinum loading rate 30% by mass) <TEC10F series manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.>: Platinum particles are supported on carbon particles (acetylene black), and the BET specific surface area "B" of the carbon particles is 800 m 2 / g. · TEC10F35E (platinum loading rate: 35 mass%) · TEC10F40E (platinum loading rate: 40 mass%) · TEC10F45E (platinum loading rate: 45 mass%) · TEC10F50E (platinum loading rate: 50 mass%) · TEC10F55E (platinum loading rate: 55 mass%) [Polymer electrolyte] <Fluorine-based polymer electrolyte>: "Nafion" (registered trademark) manufactured by Chemours Co., Ltd.

[0155] [Preparation of coating liquid for anode catalyst layer] <An coating liquid 1> 10 parts by mass of TEC10EA50E and 4 parts by mass of the fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a coating liquid with a solid content concentration of 10 mass%. "I / C" in this coating liquid is 0.8.

[0156] <An coating liquid 2> 10 parts by mass of TEC10EA20E and 6.4 parts by mass of the fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a coating liquid with a solid content concentration of 20 mass%. "I / C" in this coating liquid is 0.8.

[0157] <An coating liquid 3> 10 parts by mass of TEC10E's 20E and 6.4 parts by mass of the fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a coating liquid with a solid content concentration of 20 mass%. "I / C" in this coating liquid is 0.8.

[0158] <An coating liquid 4> 10 parts by mass of TEC10E30E and 5.6 parts by mass of a fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a coating liquid with a solid content concentration of 20% by mass. "I / C" in this coating liquid is 0.8.

[0159] <An coating liquid 5> 5 parts by mass of TEC10EA30E, 5 parts by mass of TEC10EA40, and 5.2 parts by mass of a fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a coating liquid with a solid content concentration of 15% by mass. "I / C" in this coating liquid is 0.8.

[0160] [Preparation of cathode catalyst decal (Ca decal)] <Ca decal 1> 10 parts by mass of TEC10F50E and 5 parts by mass of a fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a catalyst ink with a solid content concentration of 12% by mass. This catalyst ink was applied to a commercially available polytetrafluoroethylene film so that the dry thickness would be 12 μm and dried to prepare Ca decal 1. "I / C" in this Ca decal 1 is 1.0.

[0161] <Ca decal 2> 10 parts by mass of TEC10F55E and 4.5 parts by mass of a fluorine-based polymer electrolyte in terms of solid content were dispersed using a bead mill in a mixed solvent (mass ratio of water to 1-propyl alcohol: 4:6) to prepare a catalyst ink with a solid content concentration of 12% by mass. This catalyst ink was applied to a commercially available polytetrafluoroethylene film so that the dry thickness would be 10 μm and dried to prepare Ca decal 2. "I / C" in this Ca decal 2 is 1.0.

[0162] <Ca decal 3> A catalyst ink with a solids concentration of 12% by mass was prepared by dispersing 10 parts by mass of TEC10F45E and 5.5 parts by mass of a fluorinated polymer electrolyte in a mixed solvent (water and 1-propyl alcohol in a mass ratio of 4:6) using a bead mill. This catalyst ink was applied to a commercially available polytetrafluoroethylene film to a dry thickness of 15 μm and dried to produce Ca Decal 3. The "I / C" of this Ca Decal 3 was 1.0.

[0163] <Caデカール4> A catalyst ink with a solids concentration of 12% by mass was prepared by dispersing 10 parts by mass of TEC10F35E and 6.5 parts by mass of a fluorine-based polymer electrolyte in a mixed solvent (water and 1-propyl alcohol in a mass ratio of 4:6) using a bead mill. This catalyst ink was applied to a commercially available polytetrafluoroethylene film to a dry thickness of 21 μm and dried to produce Ca Decal 4. The "I / C" of this Ca Decal 4 was 1.0.

[0164] <Caデカール5> A catalyst ink with a solids concentration of 12% by mass was prepared by dispersing 10 parts by mass of TEC10EA40E and 6 parts by mass of a fluorinated polymer electrolyte in a mixed solvent (water and 1-propyl alcohol in a mass ratio of 4:6) using a bead mill. This catalyst ink was applied to a commercially available polytetrafluoroethylene film to a dry thickness of 7 μm and dried to produce Ca Decal 5. The "I / C" of this Ca Decal 5 was 1.0.

[0165] <Caデカール6> A catalyst ink with a solids concentration of 12% by mass was prepared by dispersing 10 parts by mass of TEC10F40E and 6 parts by mass of a fluorinated polymer electrolyte in a mixed solvent (water and 1-propyl alcohol in a mass ratio of 4:6) using a bead mill. This catalyst ink was applied to a commercially available polytetrafluoroethylene film to a dry thickness of 12 μm and dried to produce Ca Decal 6. The "I / C" of this Ca Decal 6 was 1.0.

[0166] [Example 1] An electrolyte membrane A1 formed on a PET film in Production Example 1 was used. An coating liquid 1 was applied to the side of this electrolyte membrane A1 opposite the PET film to a dry thickness of 1.5 μm and dried at 120°C, and an anode catalyst layer was laminated thereon. A protective adhesive film was then laminated on top of this anode catalyst layer. Next, the PET film was peeled off from the electrolyte membrane A1 on which the anode catalyst layer was laminated, exposing the electrolyte membrane. This surface was then superimposed on the catalyst layer of Ca decal 1, and the resulting surface was hot-pressed at 150°C and 5 MPa for 3 minutes to bond them together. The polytetrafluoroethylene film and protective adhesive film were then peeled off to obtain an electrolyte membrane with a catalyst layer.

[0167] [Examples 2 to 11 and Comparative Examples 1 to 4] A catalyst layer-equipped electrolyte membrane was obtained in the same manner as in Example 1, except that the type of electrolyte membrane, the type of Ca decal, the type of An coating liquid, and the thickness of the anode catalyst layer were changed as shown in Table 2.

[0168] [evaluation] The catalyst layer-equipped electrolyte membranes obtained in the above examples and comparative examples were evaluated for power generation performance. The results are shown in Table 2.

[0169] [Table 2]

[0170] "YC" and "YA" in the table represent the mass per unit area of ​​the carbon particles (carbon) in the platinum-supported carbon particles contained in the cathode catalyst layer and the anode catalyst layer, respectively, in mg / cm. 2 ) and the BET specific surface area of ​​the carbon particles, B(m 2 / g). The values ​​listed in "YC" and "YA" are rounded to the nearest integer.

[0171] The mass per unit area of ​​the carbon particles, "A", is the mass per unit area of ​​the platinum-supported carbon particles, "D (mg / cm 2The mass D of the platinum-loaded carbon particles was calculated by dividing the amount of platinum per unit area (indicated as "CPt" or "APt" in the table) by the platinum loading rate (E / 100). A=D×(1-E / 100) The BET specific surface area of ​​carbon particles, B(m 2 / g) is listed in the column for the platinum-supported carbon particles used to prepare the An coating liquid and Ca decal.

Claims

1. An electrolyte membrane with a catalyst layer, having a cathode catalyst layer on one surface of the electrolyte membrane and an anode catalyst layer on the other surface, wherein the electrolyte membrane contains a hydrocarbon-based polymer electrolyte, the thickness (TM) of the electrolyte membrane is less than 20 μm, the ratio (TA / TC) of the thickness (TA) of the anode catalyst layer to the thickness (TC) of the cathode catalyst layer is less than 0.

40. An electrolyte membrane with a catalyst layer.

2. The electrolyte membrane with a catalyst layer according to Claim 1, wherein the thickness (TC) of the cathode catalyst layer is 8 μm or more and less than 20 μm, and the thickness (TA) of the anode catalyst layer is 0.3 μm or more and less than 4 μm.

3. The electrolyte membrane with a catalyst layer according to Claim 1, wherein the ratio (TA / TM) of the thickness (TA) of the anode catalyst layer to the thickness (TM) of the electrolyte membrane is 0.50 or less.

4. The electrolyte membrane with a catalyst layer according to Claim 1, wherein the ratio (TC / TM) of the thickness (TC) of the cathode catalyst layer to the thickness (TM) of the electrolyte membrane is 0.60 or more.

5. The electrolyte membrane with a catalyst layer according to Claim 1, wherein the ratio (TA / TC) is 0.03 or more.

6. The electrolyte membrane with a catalyst layer according to Claim 1, wherein the cathode catalyst layer and the anode catalyst layer each contain platinum-supported carbon particles in which platinum is supported on carbon particles.

7. The electrolyte membrane with a catalyst layer according to Claim 6, wherein the ratio of the mass of platinum to the mass of the platinum-supported particles (platinum support ratio) is 25% by mass or more and less than 60% by mass.

8. The electrolyte membrane with a catalyst layer according to Claim 6, wherein the cathode catalyst layer and the anode catalyst layer each further contain a polymer electrolyte. For each catalyst layer, when the mass of the carbon particles in the platinum-supported carbon particles is (C) and the mass of the polymer electrolyte is (I), the ratio (I / C) of the two is 0.6 to 1.4 in both the cathode catalyst layer and the anode catalyst layer.

9. The electrolyte membrane with a catalyst layer according to Claim 6, wherein when the mass per unit area of platinum contained in the cathode catalyst layer is (CPt) and the mass per unit area of platinum contained in the anode catalyst layer is (APt), the ratio (APt / CPt) of the two is less than 0.

9.

10. The above (CPt) is 0.15 mg / cm ２ or more and 1.3 mg / cm ２ less than, and the above (APt) is 0.03 mg / cm ２ or more and 0.3 mg / cm ２ less than, the electrolyte membrane with a catalyst layer according to claim 9.

11. The water vapor transmission rate (WR) measured and calculated under the following conditions for the electrolyte membrane is 1.7 × 10 －５ cm ３ ·cm / (cm ２ ·cmHg·s) or less. The electrolyte membrane with a catalyst layer according to claim 1. <Measurement Conditions and Calculation Method of Water Vapor Permeability> The permeation rate of water from the cathode to the anode at 85 °C (cm ３ / s) when the cathode is at 55% RH and the anode is at 0% RH is measured, and the permeation rate (cm ３ / s), the thickness of the electrolyte membrane (cm), the differential pressure (cmHg), and the permeation area (cm ２ ) are used to obtain the following calculation formula; <Calculation Formula> Water vapor transmission rate (cm ３ ·cm / (cm ２ ·cmHg·s)) = {Water vapor permeation rate (cm ３ / s) × thickness of electrolyte membrane (cm)} / {(gas pressure difference (cmHg) × permeation area (cm ２ ))}

12. The electrolyte membrane with a catalyst layer according to Claim 1, wherein part or all of the hydrocarbon-based polymer electrolyte is an aromatic hydrocarbon-based polymer.

13. The electrolyte membrane with a catalyst layer according to claim 12, wherein part or all of the aromatic hydrocarbon polymer is a polyether ketone polymer.

14. The electrolyte membrane with a catalyst layer according to claim 12, wherein the aromatic hydrocarbon polymer is a block copolymer of an ionic segment and a non-ionic segment.

15. The electrolyte membrane with a catalyst layer according to claim 1, wherein the electrolyte membrane includes a porous substrate.

16. The electrolyte membrane with a catalyst layer according to claim 1, wherein the electrolyte membrane has a polymer electrolyte layer on one or both sides of a composite layer including a porous substrate and a polymer electrolyte.

17. A membrane electrode assembly, wherein gas diffusion layers are respectively disposed on both sides of the electrolyte membrane with a catalyst layer according to claim 1.

18. A fuel cell including the membrane electrode assembly according to claim 17.