Membrane electrode assembly and fuel cell

Abstract

The object of the present invention is to provide a membrane electrode assembly that, when used as a membrane electrode assembly for a polymer electrolyte fuel cell, is expected to not only maintain the durability of the catalyst layer but also maintain power generation performance even when operated for a long period of time under a high-potential environment. [Solution] A membrane electrode assembly is provided, which includes a proton-conductive solid electrolyte membrane, an anode catalyst layer, a cathode catalyst layer, and gas diffusion layers provided on the outside of the anode and cathode catalyst layers, wherein the cathode catalyst layer contains catalyst-supporting ceramic particles, a carbon material, and an ionomer, and the absolute value (x) calculated from the formula |(ΔV1-ΔV2) / ΔV1| is within the range of 0 to 0.5.

Description

[Technical Field]

[0001] The present invention relates to a membrane electrode assembly and a solid polymer fuel cell. [Background technology]

[0002] Fuel cells are devices that generate electricity and heat through a chemical reaction that converts hydrogen and oxygen into water. There are several types of fuel cells, including phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), and polymer electrolyte fuel cells (PEFCs). Among these, polymer electrolyte fuel cells (PEFCs) have a structure in which a catalyst layer that constitutes the anode (fuel electrode) on one side of a solid polymer membrane and the cathode (air electrode) on the other side is provided, with a gas diffusion layer bonded to the outside of each catalyst layer. The catalyst layer is made of a catalyst-supported carrier in which particulate catalysts containing precious metals are highly dispersed and supported on the surface of nano-level support particles.

[0003] Known conventional polymer electrolyte fuel cells have a membrane electrode assembly that uses, as an electrode catalyst that satisfies both a large specific surface area and high conductivity, mesoporous carbon carrying catalytic metal particles or acetylene black carrying platinum or a platinum alloy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 117369 [Patent Document 2] Japanese Patent Application Publication No. 2023-163196 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it was found that the power generation performance of polymer electrolyte fuel cells rapidly deteriorates when they are operated for long periods under high-voltage conditions, regardless of the membrane electrode assembly used. Furthermore, the timing at which power generation performance deteriorates varies depending on the type of support used, making it difficult to predict in advance. An object of the present invention is to provide a membrane electrode assembly that, when used as a membrane electrode assembly for a polymer electrolyte fuel cell, is expected to not only maintain the durability of the catalyst layer but also maintain power generation performance even when operated for a long period of time under a high-potential environment. [Means for solving the problem]

[0006] As a result of intensive research to achieve the above-mentioned object, the inventors have found that by setting the absolute value of the difference in the rate of change of gas diffusion resistance within a specific range, it is possible to maintain the durability of the catalyst layer and maintain power generation performance under high-potential environments. That is, the present invention provides the following configurations.

[0007] [1] A fuel cell comprising: a proton-conductive solid electrolyte membrane; an anode catalyst layer; a cathode catalyst layer; and gas diffusion layers provided on the outer sides of the anode and cathode catalyst layers, wherein the cathode catalyst layer contains catalyst-supporting ceramic particles, a carbon material, and an ionomer; A membrane electrode assembly, in which the absolute value (x) calculated by the following measurement method is within the range of 0 to 0.5. (Measurement method) The rate of change in gas diffusion resistance of the membrane electrode assembly from 0 to 2500 cycles in the start-stop durability test is defined as ΔV1. The rate of change in gas diffusion resistance of the membrane electrode assembly from 2500 to 5000 cycles in the start-stop durability test is defined as ΔV2. The absolute value (x) is calculated using the formula |(ΔV1-ΔV2) / ΔV1|.

[0008] [2] The membrane / electrode assembly according to the above [1], wherein the ratio of the carbon material to the catalyst-supporting ceramic particles is 5.5% by mass to 95.0% by mass.

[0009] [3] The membrane / electrode assembly according to the above [1] or [2], wherein the mass ratio of the total mass of the catalyst-supporting ceramic particles and the carbon material to the ionomer is 1:0.01 to 1:30.

[0010] [4] The membrane / electrode assembly according to any one of the above [1] to [3], wherein the catalyst-supporting ceramic particles contain silicon element.

[0011] [5] A solid polymer fuel cell comprising the membrane electrode assembly according to any one of [1] to [4] above. [Effects of the Invention]

[0012] A polymer electrolyte fuel cell including a membrane electrode assembly according to one embodiment of the present invention is expected to maintain high power generation performance by maintaining the durability of the catalyst layer and keeping the porosity of the catalyst layer constant even during long-term operation under a high-potential environment. Furthermore, according to the present invention, it is possible to easily predict when a polymer electrolyte fuel cell will deteriorate, and it is expected that this information will be useful as an index for maintenance and for inspecting defective products in the manufacturing process. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the embodiments described below, and modifications such as design changes based on the knowledge of those skilled in the art may be made, and such modified embodiments are also included in the scope of the present embodiments.

[0014] (Membrane electrode assembly) The membrane electrode assembly of the present invention comprises a proton-conductive solid electrolyte membrane, an anode catalyst layer, a cathode catalyst layer, and gas diffusion layers provided on the outer sides of the anode and cathode catalyst layers, and has an absolute value (x) within the range of 0 to 0.5. In polymer electrolyte fuel cells, fuel gas is continuously supplied and discharged, allowing the fuel gas to reach every corner of the catalyst layer, thereby increasing the number of reaction sites. Furthermore, by efficiently discharging reaction-produced water from the catalyst layer, flooding can be suppressed, and stable power generation performance can be expected even when the fuel cell is placed in a high-potential environment for a long period of time. In conventional polymer electrolyte fuel cells, cell degradation during actual fuel cell operation was predicted through durability tests of tens of thousands to hundreds of thousands of cycles. However, the present invention has discovered that by setting the desired value for the degradation rate within a specific cycle range, a catalyst layer can be obtained that exhibits excellent power generation performance over a long period of time, without conducting the aforementioned durability tests. Furthermore, application of the present invention is expected to make it possible to easily provide catalyst layers of stable quality.

[0015] The absolute value (x) of the difference in the rate of change of gas diffusion resistance is thought to affect the timing of the buckling point at which corrosion degradation of the catalyst layer progresses rapidly, and in order to delay the timing of the buckling point, it is preferable that the value be in the range of 0 to 0.5, preferably in the range of 0 to 0.3, and more preferably in the range of 0 to 0.2.

[0016] The absolute value (x) is calculated from the formula |(ΔV1-ΔV2) / ΔV1|, where ΔV1 is the rate of change in gas diffusion resistance from 0 to 2500 cycles of the start-stop durability test of the membrane electrode assembly, and ΔV2 is the rate of change in gas diffusion resistance from 2500 to 5000 cycles of the start-stop durability test. In this specification, "||" indicates an absolute value.

[0017] <Solid electrolyte membrane> The solid electrolyte membrane may be any material having proton conductivity, and may be a fluorine-based polymer electrolyte or a hydrocarbon-based polymer electrolyte. Examples of fluorine-based polymer electrolytes that can be used include Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Kasei Corporation, and Gore Select (registered trademark) manufactured by Gore. Examples of hydrocarbon-based polymer electrolytes that can be used include electrolytes such as sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, and sulfonated polyphenylene. Among these, Nafion (registered trademark) materials manufactured by DuPont are suitable for use as polymer electrolytes. Examples of hydrocarbon-based polymer electrolytes that can be used include electrolytes such as sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, and sulfonated polyphenylene. In particular, Nafion (registered trademark) materials manufactured by DuPont are suitable for use as polymer electrolytes.

[0018] <Anode catalyst layer> The anode catalyst layer is composed of catalyst-supporting carbon particles and an ionomer. The catalyst-supporting carbon particles are not particularly limited, and examples of the catalyst include metals such as platinum group elements (platinum, palladium, ruthenium, iridium, rhodium, and osmium), iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum, as well as alloys, oxides, double oxides, and carbides of these metals. The carbon particles are also not particularly limited as long as they can support the catalyst and have electrical conductivity, and examples include carbon black (acetylene black, furnace black, ketjen black, and the like), graphite, activated carbon, and fullerene.

[0019] The ionomer may be any one having proton conductivity, and suitable examples thereof include fluorine-based polymer resins and hydrocarbon-based polymer resins, such as Nafion (registered trademark) manufactured by DuPont, sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, sulfonated polyphenylene, etc. The ionomer may be the same as that used in the above-mentioned solid electrolyte membrane, and using the same ionomer is preferred because it provides excellent adhesion between the catalyst layer and the solid electrolyte membrane.

[0020] Furthermore, the catalyst layer may contain a fibrous material. By containing the fibrous material, a structure in which fibers are entangled is formed within the catalyst layer, which improves the strength and can suppress the occurrence of cracks. In addition, the formation of suitable voids is expected to improve power generation performance. The average fiber diameter of the fibrous material is preferably 0.5 to 500 nm, more preferably 10 to 300 nm. The average fiber length is preferably 1 to 200 μm. From the viewpoint of void formation in the catalyst layer, it is preferable that the average fiber diameter and average fiber length are within the above ranges.

[0021] Examples of the fibrous material include conductive fibers and electrolyte fibers. Examples of the conductive fibers include carbon fibers, carbon nanotubes, carbon nanohorns, and conductive polymer nanofibers. Examples of the electrolyte fibers include the above-mentioned polymer electrolytes processed into a fibrous form.

[0022] <Cathode catalyst layer> The cathode catalyst layer is composed of catalyst-supporting ceramic particles, a carbon material, and an ionomer. The catalyst-supporting ceramic particles are not particularly limited, and examples of the catalyst include metals such as platinum group elements (platinum, palladium, ruthenium, iridium, rhodium, and osmium), iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum, as well as alloys, oxides, double oxides, and carbides of these metals, with platinum, platinum-cobalt, and platinum-nickel being more preferred.

[0023] The ceramic particles may be any material capable of supporting the catalyst, and preferably contain silicon, with silicon carbide, silicon oxycarbide, silicon nitroxycarbide, and silicon nitride being more preferred. The ceramic particles may also be composited with a carbon material, which will be described later, and can be composited by adding a carbon material when producing the ceramic particles. Composite formation allows the carbon material to be incorporated into the ceramic particles, which form a three-dimensional skeletal structure, making it possible to impart electrical conductivity to the ceramic particles, which is preferred.

[0024] The particle size of the ceramic particles is preferably 10 to 1000 nm, and more preferably 10 to 100 nm. A particle size of 1000 nm or less allows the thickness of the catalyst layer to be thin, reducing resistance and contributing to improved power generation performance, which is preferable. Furthermore, a particle size of 10 nm or more allows good voids to be obtained when the catalyst layer is formed, which is preferable.

[0025] Examples of carbon materials include acetylene black, furnace black, and ketjen black.

[0026] When the carbon material is composed of acetylene black, the average diameter of the primary particles of the carbon material is preferably 10 nm to 200 nm, more preferably 20 nm to 100 nm, and even more preferably 30 nm to 50 nm. When the average diameter of the primary particles of the carbon material is 10 nm to 200 nm, good electrical conductivity can be achieved.

[0027] When the carbon material is composed of carbon nanofibers or carbon nanotubes, the average diameter of the carbon material is preferably 10 nm or more and 200 nm or less, and the length of the carbon material is preferably 1 μm or more and 20 μm or less.

[0028] When a carbon material is composited with catalyst-supported ceramic particles, the ratio of the carbon material to the catalyst-supported ceramic particles is preferably 5.5% by mass to 95.0% by mass, more preferably 10% by mass to 90% by mass, and particularly preferably 20% by mass to 80% by mass. By keeping the ratio within this range, ΔV2 can be reduced, which is preferable.

[0029] The shape and size of ceramic particles and carbon materials can be measured, for example, by observation using a transmission electron microscope or a scanning electron microscope. The average diameter of primary particles can be determined, for example, from microscope images using image analysis particle size distribution measurement software.

[0030] The ionomer is the same as the ionomer used in the anode catalyst layer described above.

[0031] The mass ratio of the total mass of the catalyst-supporting ceramic particles and the carbon material to the ionomer is preferably 1:0.01 to 1:30, and more preferably 1:0.1 to 1:10. A mass ratio within this range is preferable from the viewpoint of forming a catalyst layer having pores that are excellent in gas diffusion.

[0032] (Method of manufacturing catalyst layer) The catalyst layer can be manufactured by preparing a catalyst layer slurry, applying it to a substrate or gas diffusion layer, drying it, and then thermocompressing the catalyst layer onto a solid polymer membrane. The catalyst layer slurry comprises catalyst-supporting carbon particles, an ionomer, and a solvent, or catalyst-supporting ceramic particles, a carbon material, an ionomer, and a solvent.

[0033] The solvent is not particularly limited as long as it can dissolve or disperse the ionomer and catalyst. Examples of the solvent include water, alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-butanol, pentanol, ethylene glycol, diacetone alcohol, 1-methoxy-2-propanol, etc.), ketones (acetone, methyl ethyl ketone, pentanone, methyl isobutyl ketone, diisobutyl ketone, etc.), ethers (dioxane, tetrahydrofuran, etc.), sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), and the like, which can be used alone or in combination. The solvent used in the catalyst ink is preferably one that can be easily removed by heating, and in particular, one with a boiling point of 150° C. or less is preferably used.

[0034] The concentration of the solute (catalyst-supporting carbon particles, ionomer or catalyst-supporting ceramic particles, carbon material, ionomer) in the catalyst layer slurry is, for example, about 1 to 80 mass %, preferably about 5 to 60 mass %, and more preferably about 10 to 40 mass %.

[0035] The catalyst layer slurry can be prepared by carrying out a dispersion treatment, and examples of the dispersion method include a ball mill, a bead mill, a roll mill, a shear mill, a wet mill, ultrasonic dispersion, and a homogenizer.

[0036] The catalyst layer slurry can be applied to the substrate by a conventional coating method, such as a roll coater, air knife coater, blade coater, rod coater, reverse coater, bar coater, comma coater, die coater, gravure coater, screen coater, sprayer, or spinner. There are no particular limitations on the coating means as long as a similar membrane electrode assembly can be obtained in the end.

[0037] The desired catalyst layer can be obtained by applying the catalyst layer slurry to a substrate and volatilizing the solvent in the catalyst ink by heating. Drying methods include hot air drying and IR drying. The drying temperature is 40 to 200°C, preferably about 40 to 120°C. The drying time is 0.5 minutes to 1 hour, preferably about 1 to 30 minutes. The drying step may be performed using a single drying mechanism or a combination of multiple drying mechanisms. The average thickness of the catalyst layer obtained by drying the catalyst layer slurry is, for example, about 0.1 to 100 μm, preferably about 0.5 to 50 μm, and more preferably about 1 to 20 μm.

[0038] The substrate used in the transfer step is not particularly limited as long as it can be coated with a catalyst layer slurry on at least one side, can form a catalyst layer by heating, and can transfer the formed catalyst layer to the solid polymer membrane. For example, polymer films such as polyethylene terephthalate, polyamide, polyimide, polystyrene, polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polybenzimidazole, polyamideimide, polyacrylate, polyethylene naphthalate, and polypalvanic acid aramid, or heat-resistant fluororesin films such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, ethylene tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroperfluoroalkyl vinyl ether copolymer can be used.

[0039] Furthermore, the substrate may be subjected to a release treatment, or may have a multi-layer structure in which a release layer is integrated by co-extrusion or the like. The substrate may be a sheet, film, plate, membrane, or foil, or at least one of these may be adhered, bonded, adhered, or pasted.

[0040] (Method for manufacturing membrane electrode assembly) As a method for manufacturing a membrane electrode assembly, a catalyst layer is formed on a transfer substrate or a gas diffusion layer, and then the catalyst layer is formed on a solid polymer membrane by thermocompression bonding, or a catalyst layer is formed directly on a solid polymer membrane. The method of forming a catalyst layer directly on a solid polymer membrane is preferable because it provides high adhesion between the solid polymer membrane and the catalyst layer and there is no risk of the catalyst layer being crushed. [Example]

[0041] Examples of the present invention will be described below. The present invention is not limited to the examples shown below. Values in the tables mean "parts by weight" unless otherwise specified.

[0042] (evaluation) A single cell was assembled using the MEAs obtained in the examples and comparative examples, and was placed in a power generation evaluation device (FCE-1, manufactured by Panasonic Production Engineering Co., Ltd.), and the following evaluations were carried out.

[0043] [Start / Stop durability test] A durability test was carried out at a cell temperature of 80°C and a relative humidity of 100%RH, with hydrogen gas supplied to the anode side and nitrogen gas supplied to the cathode side, over a potential range of 1.0V-1.5V.

[0044] [Oxygen gas diffusion resistance measurement of catalyst layer] Under conditions of a cell temperature of 80°C and a relative humidity of 80% RH, hydrogen gas was supplied to the anode side, and nitrogen gas diluted to an oxygen concentration of 2% was supplied to the cathode side, and the back pressure was changed to 0, 20, 50, 80, and 100 kPa, and the limiting current density (Ilim) was measured and the gas diffusion resistance (Rtotal) was calculated. The gas diffusion resistance (Rother) of the catalyst layer was calculated from the pressure dependence data of Rtotal.

[0045] The rate of change in gas diffusion resistance of the membrane electrode assembly from 0 to 2500 cycles in the start-stop durability test is defined as ΔV1. The rate of change in gas diffusion resistance of the membrane electrode assembly from 2500 to 5000 cycles in the start-stop durability test is defined as ΔV2. The absolute value (x) is calculated using the formula |(ΔV1-ΔV2) / ΔV1|. The absolute value (x) can be evaluated as follows: If the absolute value (x) is in the range of 0 to 0.2, it is marked as "◎". If the absolute value (x) is in the range of 0 to 0.5 (excluding the above range), then "Yes" If the absolute value (x) is outside the range of 0 to 0.5, it is displayed as "×".

[0046] Example 1 (Preparation of anode catalyst ink) Carbon black (Pt / CB, Tanaka Kikinzoku K.K., TEC10E50E, Pt loading 46 wt%) carrying 0.45 g of platinum (Pt) was mixed with ionomer (Du Pont, Nafion® DE521) at a volume ratio of 1.0. This mixture, 2.5 g of ethanol, 2 g of water, and zirconia balls (5 mm diameter) were placed in a zirconia pot and mixed for 60 minutes in a planetary ball mill (Fritsch, P-6). The mixture obtained by mixing in this ball mill is hereafter referred to as the anode catalyst ink.

[0047] (Preparation of cathode catalyst ink) Platinum-supported silicon carbide ([Si] / [C] = 1:1.3, Pt loading 40% by mass) and ionomer (Du Pont, Nafion (registered trademark) DE521) were mixed to a mass ratio of 0.5 as an electrode catalyst, and this mixture, 2.5 g of ethanol, 2 g of water, and a zirconia ball (diameter 5 mm) were placed in a zirconia pot and mixed for 60 minutes with a planetary ball mill (Fritsch, P-7). The electrode catalyst was prepared by blending a carbon material with silicon carbide obtained by the method described in JP 2023-148962 A and mixing it with a dispersion containing a precious metal colloid.

[0048] (Fabrication of membrane electrode assembly (MEA)) Using the obtained anode and cathode catalyst inks, an anode catalyst layer and a cathode catalyst layer were produced on a solid electrolyte membrane (Nafion NR212, manufactured by Du Pont) using a spray coating device (manufactured by Acing Technologies) so that the platinum coverage of the anode was 0.5 mg / cm2 and the platinum coverage of the cathode was 0.3 mg / cm2. A fuel cell electrode membrane (CCM) consisting of an anode catalyst layer or a cathode catalyst layer and a polymer electrolyte membrane was hot pressed (140°C, pressure 2.86 kN) for 3 minutes using a hot press machine (CYPM-10, manufactured by Shinto Kogyo Co., Ltd.).

[0049] In the above CCM, gas diffusion layers (GDL, manufactured by SGL, 22BB) were placed on both sides of each catalyst layer, and a membrane electrode assembly (MEA) was obtained in which the cathode catalyst layer and the anode catalyst layer were stacked on the polymer electrolyte membrane so that they faced each other. The gas diffusion resistance was measured every 2,500 cycles of the start-stop durability test, and ΔV1 of the cell consisting of the above MEA was 1.52 × 10 -3 , ΔV2 is 1.36×10 -3 and the absolute value (x) was confirmed to be 0.105.

[0050] Example 2 Except for changing the electrode catalyst of the cathode catalyst layer to platinum-supported silicon nitride, an MEA was obtained in the same manner as in Example 1, and the absolute value (x) was determined. The electrode catalyst was prepared by blending a carbon material with silicon nitride obtained by the method described in JP 2024-021564 A, and mixing the mixture with a dispersion containing a precious metal colloid.

[0051] Example 3 Except for changing the electrode catalyst of the cathode catalyst layer to platinum-supported silicon oxycarbide, an MEA was obtained in the same manner as in Example 1, and the absolute value (x) was determined. The electrode catalyst was prepared by the method described in Japanese Patent No. 7533800.

[0052] (Comparative Example 1) An MEA was obtained in the same manner as in Example 1, except that the electrode catalyst in the cathode catalyst layer was changed to the platinum-supported carbon used in the anode catalyst layer. The gas diffusion resistance was measured every 2,500 cycles of a start-stop durability test, and ΔV1 of the cell comprising the MEA was 2.0 × 10 -3 , ΔV2 is 1.0×10 -4 and the absolute value (x) was confirmed to be 6.0.

[0053] [Table 1]

[0054] As shown in Table 1, in Comparative Example 1, the rate of change in gas diffusion resistance in the latter half of the start-stop durability test (2500 to 5000 cycles) was greater than the rate of change in gas diffusion resistance in the first half (0 to 2500 cycles) of the start-stop durability test, and it was confirmed that the power generation performance rapidly deteriorated as the gas diffusion resistance increased rapidly. On the other hand, in Examples 1 to 3, no rapid increase in gas diffusion resistance was confirmed, and it is believed that the state of the catalyst layer was maintained, resulting in stable power generation performance over a long period of time.

Claims

1. a proton-conducting solid electrolyte membrane, an anode catalyst layer, a cathode catalyst layer, and gas diffusion layers provided on the outer sides of the anode and cathode catalyst layers; the cathode catalyst layer includes catalyst-supporting ceramic particles, a carbon material, and an ionomer, and the catalyst-supporting ceramic particles are composited with the carbon material; A membrane electrode assembly, wherein the absolute value (x) calculated by the following measurement method is within the range of 0 to 0.

5. (Measurement method) The rate of change in gas diffusion resistance of the membrane electrode assembly from 0 to 2500 cycles in the start-stop durability test is defined as ΔV1. The rate of change in gas diffusion resistance of the membrane electrode assembly during 2500 to 5000 cycles of the start-stop durability test is defined as ΔV2. The absolute value (x) is calculated from the formula |(ΔV1-ΔV2) / ΔV1|.

2. 2. The membrane electrode assembly according to claim 1, wherein the ratio of the carbon material to the catalyst-supporting ceramic particles is 5.5% by mass to 95.0% by mass.

3. 2. The membrane / electrode assembly according to claim 1, wherein the mass ratio of the total mass of the catalyst-supporting ceramic particles and the carbon material to the ionomer is 1:0.01 to 1:

30.

4. 2. The membrane electrode assembly according to claim 1, wherein the catalyst-supporting ceramic particles contain silicon elements.

5. A solid polymer fuel cell comprising the membrane electrode assembly according to any one of claims 1 to 4.

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