JP4734688B2 - ELECTRODE AND MANUFACTURING METHOD THEREOF, MEMBRANE-ELECTRODE COMPOSITION AND MANUFACTURING METHOD THEREOF, AND ELECTROCHEMICAL DEVICE, WATER ELECTROLYTIC DEVICE, FUEL CELL, MOBILE BODY USING THE SAME, AND AUTOMOBILE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode or membrane-electrode composite used in a fuel cell or various electrochemical devices, and a method for producing them.
[0002]
[Prior art]
A fuel cell is a power generation device with low emissions, high energy efficiency, and low environmental burden. For this reason, it is in the spotlight again in recent years to the protection of the global environment. It is a power generation device that is expected in the future as a power generation device for a mobile body such as a distributed power generation facility, a car or a ship that is relatively small compared to a conventional large-scale power generation facility.
[0003]
There are various types of fuel cells such as a solid polymer type, a phosphoric acid type, a solid oxide type, a molten carbonate type, and an alkaline type depending on the type of electrolyte used. In particular, solid polymer fuel cells have features such as lower operating temperatures, shorter start-up times, higher output, easier downsizing and weight reduction, and resistance to vibration than other fuel cells. Suitable for body power supply.
[0004]
A fuel cell is configured as a unit of a cell in which an anode electrode and a cathode electrode in which a reaction responsible for power generation occurs and an electrolyte serving as an ion conductor between the anode and the cathode are sandwiched between separators. The electrode is composed of an electrode base material (also referred to as a current collector) that promotes gas diffusion and collects (supply) electricity, and an electrode catalyst layer that actually becomes an electrochemical reaction field. For example, in the anode electrode of a polymer electrolyte fuel cell, the fuel gas reacts on the catalyst surface to generate protons and electrons, the electrons are conducted to the electrode substrate, and the protons are conducted to the proton exchange membrane of the electrolyte. For this reason, the anode electrode is required to have good gas diffusibility, electron conductivity, and ion conductivity. On the other hand, in the cathode electrode, the oxidizing gas on the surface of the catalyst layer reacts with protons conducted from the electrolyte and electrons conducted from the electrode base material to generate water. For this reason, it is also necessary to efficiently discharge the generated water together with gas diffusibility, electronic conductivity, and ion conductivity.
[0005]
From such a point, a porous conductive sheet having conductivity and good gas permeability has been used for the electrode substrate (current collector). For example, JP-A-6-20710, JP-A-7-326362, or JP-A-7-220735 has been proposed. The current collectors disclosed in these are composed of a porous carbon plate in which carbon fibers having a short length are bound with carbon.
[0006]
[Problems to be solved by the invention]
The porous conductive sheet described above has good gas permeability, but when an electrode catalyst layer was applied on the sheet, a phenomenon in which the catalyst coating solution penetrated into the pores was observed. This catalyst penetration phenomenon increases the number of catalysts that are not used effectively. Since noble metal catalysts are used in fuel cells, an increase in the number of catalysts that are not used effectively leads to an increase in the cost of the electrodes. In particular, solid polymer fuel cells have high expectations for automotive applications. In addition to performance, cost is an important factor for adaptation to automotive applications. The current polymer electrolyte fuel cells are expected to become more popular if the cost is reduced. For this reason, an electrode with less catalyst penetration has been desired.
[0007]
An object of the present invention is to solve the above problems and to obtain an electrode with less catalyst penetration, thereby improving the utilization efficiency of the catalyst and obtaining a cost-reduced electrode by reducing the amount of catalyst.
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems.
[0008]
  That is, the electrode of the present invention is an electrode composed of at least an electrode base material and an electrode catalyst layer, and the electrode catalyst layer soaks into the electrode base material to form a mixed layer. The thickness of the mixed layer3μm or moreIt is characterized by being 20 μm or less.
[0009]
The method for producing an electrode of the present invention is produced by providing an electrode catalyst layer on an electrode substrate. The electrode catalyst coating solution is applied on the electrode substrate, and the electrode catalyst layer is applied to the electrode substrate. It is characterized by providing.
[0010]
Furthermore, the electrode of the present invention is applied not only to a membrane-electrode assembly (MEA) but also to an ordinary electrochemical device, particularly a polymer electrolyte fuel cell. A mobile body or an automobile using the fuel cell is used. It also applies to.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described.
[0012]
  The present invention provides an electrode composed of at least an electrode base material and an electrode catalyst layer, and the thickness of the mixed layer in which the electrode catalyst layer is immersed in the electrode base material is3μm or moreThe electrode base material and the electrode catalyst layer used here are not particularly limited.
[0013]
In the present invention, the mixed layer is a layer in which the electrode catalyst layer is soaked in the electrode base material. Therefore, the constituent components of the electrode catalyst layer not including the electrode base material (for example, catalyst metal, catalyst particles, carbon black) , A layer composed only of fluorine atoms (hereinafter referred to as a pure electrode catalyst layer) is not included in the mixed layer. Therefore, the thickness of the pure electrocatalyst layer is not included in the thickness of the mixed layer of the present invention, and is calculated by excluding it. However, it does not prevent the electrode of the present invention from having the pure electrode catalyst layer. Therefore, the electrode catalyst layer of the present invention may include a pure electrode catalyst layer together with the mixed layer.
[0014]
In the present invention, the electrode catalyst layer is soaked in the electrode base material. In at least some layers or regions of the electrode base material, the electrode is formed in the void portion where the constituent material of the electrode base material does not exist. It means a state in which a catalyst component is present. Certainly, the production method in which the electrode catalyst constituent material in a liquid state that is not solidified or immobilized with respect to the electrode base material that has already been formed is invaded to form the mixed layer or the present invention. This is one of the preferred methods for producing the electrode catalyst layer. However, it does not mean that the mixed layer or the electrode catalyst layer of the present invention is necessarily limited to being formed by this production method.
[0015]
  The thickness of the mixed layer in the present invention is an average thickness. Therefore, even if there is a portion that does not locally satisfy the numerical range of the present invention, as long as the average value is satisfied, the thickness is within the technical scope of the present invention. Needless to say. The thickness of the mixed layer is preferably 15 μm or less, more preferably 10 μm or less. still3Must be μm or moreIs necessaryMore preferably, it is 5 μm or more. If the above upper limit is exceeded, the amount of catalyst that is soaked in and effectively used will decrease, and if it falls below the lower limit, resistance may increase when a membrane-electrode composite is produced, which is not preferable. is there.
[0016]
  In the present invention, the thickness of the mixed layer in which the electrode catalyst layer is immersed in the electrode substrate can be confirmed by observation with a scanning electron microscope (SEM) of the electrode cross section. In general, since the electrode substrate has a porous structure and the electrode catalyst layer has a structure filled with particles, a mixed layer in which the electrode catalyst particles are immersed in the porous electrode substrate is observed. The In addition, a mixed layer in which the electrode catalyst layer is immersed in the electrode base material may not be clearly observed, as in the case where the electrode base material contains conductive fine particles such as carbon powder. In such a case, by using a combination of SEM and X-ray microanalysis (XMA) (SEM-XMA), observe how far a noble metal catalyst such as platinum contained in the electrode catalyst has penetrated the electrode substrate. It is possible to determine the thickness of the mixed layer by.
[0017]
In SEM-XMA, the pure electrode catalyst layer and the mixed layer are measured by the following procedure. First, the interface between the conductive sheet and the pure electrode catalyst layer is confirmed from SEM observation, and the thickness of the pure electrode catalyst layer is measured. Next, the presence of Pt used for the electrode catalyst is confirmed by XMA measurement in the shade of the screen, and the total thickness of the pure electrode catalyst layer and the mixed layer immersed in the conductive sheet is measured. The thickness of the mixed layer can be obtained from the difference between the two.
[0018]
The electrode substrate used in the present invention is not particularly limited as long as it has a low electrical resistance and can collect (supply) electricity. Characteristic is expressed. Examples of the constituent material of the electrode base material include those mainly composed of a conductive inorganic substance. Examples of the conductive inorganic substance include a fired body from polyacrylonitrile, a fired body from pitch, graphite, and expanded graphite. Examples thereof include carbon materials, stainless steel, molybdenum, and titanium. The form of the conductive inorganic material is not particularly limited, such as fibrous or particulate, but when used in an electrochemical device using gas as an electrode active material such as a fuel cell, the fibrous conductive inorganic material is used from the viewpoint of gas permeability. (Inorganic conductive fiber) Carbon fiber is particularly preferable. As the porous conductive sheet using inorganic conductive fibers, either a woven fabric or a non-woven fabric structure can be used. For example, carbon paper TGP series, SO series manufactured by Toray Industries, Inc., carbon cloth manufactured by E-TEK, etc. are used.
[0019]
The electrode substrate used in the present invention preferably has a thickness of 0.02 to 0.3 mm when a uniform surface pressure of 2.9 MPa is applied in the thickness direction. More preferably, it is 0.04 to 0.2 mm. When the thickness is less than 0.02 mm, the electrode base material is buried in the gas flow path of the separator when used in a fuel cell, the diffusion / permeability in the surface direction is low, the strength is weak, and the workability is poor. When it is thicker than 0.3 mm, the electric resistance in the thickness direction increases. The thickness is determined when the electrode substrate is sandwiched between two glassy carbon plates having a uniform thickness and a smooth surface, and is pressed with a uniform surface pressure of 2.9 MPa, and the electrode substrate is not sandwiched. It is calculated from the difference between the upper and lower indenters. In measuring the distance between the indenters, the distance between the indenters is measured by a minute displacement detector at both ends sandwiching the center point of the indenter, and the distance between the indenters is calculated as an average value of the distance between both ends. In order to obtain a uniform surface pressure, one of the indenters is received by a ball seat so that the angle formed by the pressure surfaces of the upper and lower indenters is variable.
[0020]
When the uniform surface pressure of 2.9 MPa is applied in the thickness direction, the thickness measured at a surface pressure of 13 kPa of the electrode base material having the above thickness is preferably 0.1 to 2.0 mm, 0.2 to 1 .2 mm is more preferable. If it exceeds 2 mm, the electrode substrate becomes bulky, the electrode substrate is directed in the thickness direction, and the strength of the electrode material is weakened. In order to obtain a thickness of less than 0.1 mm, it is necessary to firmly bind the electrode base material with a large amount of polymer substance.
[0021]
The basis weight of the electrode substrate is 10 to 220 g / m.²Is preferred. More preferably 20 to 120 g / m²It is. 10 g / m²If it is less than this, the strength of the electrode substrate is lowered. In addition, when the polymer electrolyte membrane, the catalyst layer, and the electrode base material are integrated or assembled into a battery, the electrode base material becomes thin and the effect of diffusion / permeation in the surface direction becomes insufficient. 220 g / m²If it exceeds the upper limit, the electrode substrate becomes thicker when assembled in a battery, and the resistance increases.
[0022]
The density of the electrode substrate is 0.3 to 0.8 g / cm when a uniform surface pressure of 2.9 MPa is applied in the thickness direction.^ThreeIs preferred. More preferred is 0.35 to 0.7 g / cm.^ThreeAnd more preferably 0.4 to 0.6 g / cm.^ThreeIt is. The density of the electrode base material when a uniform surface pressure of 2.9 MPa is applied in the thickness direction is as follows: the basis weight of the electrode base material and the electrode base material when a uniform surface pressure of 2.9 MPa is applied in the thickness direction Calculated from the thickness of The electrode substrate needs to have a high porosity in order to increase the diffusion and permeability, but the density when a uniform surface pressure of 2.9 MPa is applied in the thickness direction is 0.8 g / cm.^ThreeIf it is larger than 1, the porosity is lowered, and the diffusion and permeability become insufficient. 0.3 g / cm^ThreeIf it is smaller than 1, the resistance value in the thickness direction becomes large.
[0023]
The electrode base material has a pressure loss of 98 Pa (10 mmAq) or less when air of 14 cm / second is transmitted in the thickness direction in a state where no pressure is applied by the surface pressure in the thickness direction. It is preferable in terms of gas diffusivity. More preferable is 29 Pa (3 mmAq) or less, and further preferable is 9.8 Pa (1 mmAq) or less.
[0024]
The tensile strength of the electrode substrate is preferably 0.49 N / 10 mm width or more, more preferably 1.96 N / 10 mm width or more, and still more preferably 4.9 N / 10 mm width or more. If the tensile strength is low, there is a problem that the possibility of the sheet being damaged increases in the high-order processing of the electrode equipment.
[0025]
The electrode substrate may be broken by being pressurized in the thickness direction when the polymer electrolyte membrane, the catalyst layer and the electrode substrate are integrated or used as a battery. In addition, when used as a battery, pressure is applied in the thickness direction while facing the grooved separator, so that a large pressure is applied to the part facing the mountain of the grooved separator, and the part facing the boundary between the mountain and valley Is fragile. When the electrode base material is broken, the broken inorganic conductive material may drop off, the strength of the electrode base material may decrease, the electrical resistance in the surface direction may increase, and the electrode performance may deteriorate.
[0026]
From the above, the electrode base material preferably has a weight reduction rate of 3% or less after applying a uniform surface pressure of 2.9 MPa in the thickness direction for 2 minutes and releasing the surface pressure. This is because the electrode base material having a weight reduction rate higher than 3% is weak after the surface pressure is released, and is easily broken by handling. Thereby, it is hard to break at the time of pressurization, and it can prevent that a fuel cell becomes unusable by destruction of an electrode base material. Preferably it is 2% or less, More preferably, it is 1% or less.
[0027]
The weight loss rate is measured as follows. First, the electrode base material is cut into a circle having a diameter of 46 mm, and the weight is measured. Next, the electrode base material cut between two glassy carbon plates having a smooth surface that is larger than the electrode base material is sandwiched and pressurized to a pressure of 2.9 MPa per area of the electrode base material for 2 minutes. keep. The electrode base material is taken out by removing the pressure, and dropped from a height of 30 mm with its surface direction set to the vertical direction. The weight is measured after 10 drops, and the weight reduction rate is calculated.
[0028]
The measurement of the electrical resistance R of the electrode substrate is as follows. A test electrode plate in which a copper foil having a width of 50 mm, a length of 200 mm, and a thickness of 0.1 mm is attached to one surface of a glassy carbon plate having a flat surface with a width of 50 mm, a length of 200 mm, and a thickness of 1.5 mm. Two pieces are prepared. The two test electrode plates are positioned so that the surfaces of the glassy carbon plates are opposed to each other while maintaining a substantially uniform interval. A current terminal is provided at one end of each of the two test electrode plates, and a voltage terminal is provided at each other end. A sheet cut into a circle with a diameter of 46 mm is inserted into the gap and placed on the center of the two test electrode plates. The test electrode plate is moved so that a pressure of 0.98 MPa acts on the placed sheet. A current of 1 A flows between the two test electrode plates at the current terminal. The voltage V (V) at this time is measured at the voltage terminal. The value of the measured voltage V is used, and the resistance R (mΩ · cm²) Is required.
R = V × 2.3 × 2.3 × π × 1000
Here, π is the circumference ratio.
[0029]
The electrical resistance of the porous conductive sheet is 100 mΩ · cm²Or less, preferably 50 mΩ · cm²More preferably, 15 mΩ · cm²More preferably, it is as follows. As will be described later, the electrical resistance of the electrode substrate containing a water-repellent fluororesin is 150 mΩ · cm.²Or less, preferably 70 mΩ · cm²More preferably, it is 30 mΩ · cm²More preferably, it is as follows.
[0030]
In addition to the above electrode base material, the electrode base material includes a paper-like sheet formed by binding inorganic conductive fibers oriented in a random direction in a substantially two-dimensional plane with a polymer substance. A porous conductive sheet in which the length of the inorganic conductive fiber is at least 3 mm and at least 5 times the thickness of the sheet can also be used. Here, the thickness of the sheet is measured according to JIS P8118. The surface pressure during measurement is 13 kPa. The meaning that the inorganic conductive fibers are substantially oriented in a two-dimensional plane means that the inorganic conductive fibers lie so as to form a single plane. This can prevent a short circuit with the counter electrode due to the inorganic conductive fiber and breakage of the inorganic conductive fiber.
[0031]
In order to increase the strength and handling properties of the electrode substrate and to orient the inorganic conductive fibers in a substantially two-dimensional plane, the length of the inorganic conductive fibers is at least 3 mm, preferably 4.5 mm. More preferably, it is 6 mm or more. If it is less than 3 mm, it becomes difficult to maintain strength and handling properties. Moreover, in order to orient the inorganic conductive fibers in a random direction in a substantially two-dimensional plane, the length of the inorganic conductive fibers is at least 5 times the thickness of the electrode substrate, preferably at least 8 times, Preferably it is 12 times or more. If it is less than 5 times, it is difficult to ensure the orientation in two dimensions. The upper limit of the length of the inorganic conductive fibers is preferably 30 mm or less, more preferably 15 mm or less, and even more preferably 8 mm or less in order to orient in a substantially random direction within a two-dimensional plane. If the inorganic conductive fiber is too long, poor dispersion tends to occur, and many fibers may remain in a bundle. In such a case, the bundle-shaped part has a low porosity, and the thickness at the time of pressurization is increased, so that a high pressure is applied at the time of pressurization. Problems such as thinning easily occur.
[0032]
Moreover, it is preferable that the form of the inorganic conductive fiber is linear so that a short circuit with the counter electrode due to the fiber can be more completely prevented. Here, the linear inorganic conductive fiber means linearity with respect to the length L when the length L (mm) in the length direction of the fiber is taken in a state where the external force for bending the inorganic conductive fiber is removed. The deviation Δ (mm) from the distance is measured, and Δ / L is approximately 0.1 or less. On the other hand, non-linear fibers have a drawback that they tend to be oriented in a three-dimensional direction when oriented in a random direction in a substantially two-dimensional plane.
[0033]
In the preparation of the electrode substrate, as a method of orienting the inorganic conductive fibers in a random direction in a substantially two-dimensional plane, a wet method in which the inorganic conductive fibers are dispersed in a liquid medium and made, There is a dry method in which inorganic conductive fibers are dispersed in the air to be deposited. In order to ensure that the inorganic conductive fibers are oriented substantially in a two-dimensional plane and to increase the strength of the inorganic conductive fibers, a wet method, particularly a so-called papermaking method is preferred.
[0034]
In the electrode base material, in order to prevent breakage of the inorganic conductive material during pressurization and to reduce the weight reduction rate of the electrode base material to 3% or less as described above, the fiber used is carbon cut from carbon fiber. Short fibers are preferred, those that are tensioned during heat treatment are more preferred, and those that are stretched during heat treatment are more preferred.
[0035]
Examples of the carbon fiber include polyacrylonitrile (PAN) -based carbon fiber, phenol-based carbon fiber, pitch-based carbon fiber, and rayon-based carbon fiber. Of these, PAN-based carbon fibers are preferable. PAN-based carbon fibers have greater compressive strength and tensile elongation at break than pitch-based carbon fibers, and are not easily broken. This is considered to be due to the difference in crystallization of carbon constituting the carbon fiber. In order to obtain a carbon fiber that is not easily broken, the heat treatment temperature of the carbon fiber is preferably 2,500 ° C. or less, and more preferably 2,000 ° C. or less.
[0036]
The short carbon fibers used in the electrode substrate of the present invention satisfy the following formula in relation to the diameter D (μm), the tensile strength σ (MPa), and the tensile modulus E (MPa). Is good. This is because such an electrode substrate made of short carbon fibers is not easily broken. That is, the short carbon fiber has a smaller diameter, a higher tensile strength, and a lower tensile elastic modulus, the carbon short fiber is less likely to be broken, and the electrode substrate is less likely to be broken during pressurization.
σ / (E × D) ≧ 0.5 × 10^-3
Here, the tensile strength and tensile modulus of carbon fiber are measured according to JIS R7601. In the case of a carbon fiber having a flat cross section, the average value ((a + b) / 2) of the major axis (a) and the minor axis (b) is taken as the diameter. When different types of short carbon fibers are mixed, D, σ, and E are weight averaged values, respectively. Preferably σ / (E × D) ≧ 1.1 × 10^-3More preferably, σ / (E × D) ≧ 2.4 × 10^-3It is.
[0037]
The tensile elongation at break of the short carbon fibers is preferably 0.7% or more, more preferably 1.2% or more, and further preferably 1.8% or more because of the strength of the electrode substrate. . The tensile elongation at break is a value obtained by dividing the tensile strength (σ) by the tensile modulus (E).
[0038]
Further, since the breakage of the short carbon fiber occurs in various situations, the tensile strength of the short carbon fiber is preferably 500 MPa or more, more preferably 1,000 MPa or more, and 2,000 MPa or more. Is more preferable.
[0039]
The diameter of the inorganic conductive fiber used for the electrode substrate is preferably 20 μm or less. More preferably, it is 12 micrometers or less, More preferably, it is 8 micrometers or less. On the surface of the electrode substrate, voids having a diameter of 5 to 10 times the diameter of the inorganic conductive fiber are observed. This void increases as the fiber diameter increases. The conductive intermediate layer of the present invention suppresses the electrode performance from deteriorating due to the electrode catalyst layer dipping into the gap. If the voids are too large, the conductive intermediate layer needs to be thick, and gas permeability and water discharge properties are hindered. Therefore, it is preferable that the fiber diameter is narrow. In addition, the thinner the inorganic conductive fiber, the less likely it is to break when pressed in the thickness direction. On the other hand, if the diameter of the inorganic conductive fiber is too thin, it is difficult for the catalyst layer to enter the electrode base material at the time of integration. Therefore, the fiber diameter is preferably 2 μm or more. When fibers having different diameters are mixed, the diameter is obtained by weight average.
[0040]
The volume resistivity of the inorganic conductive fiber used for the electrode substrate is preferably 200 μΩ · m or less, more preferably 50 μΩ · m or less, and even more preferably 15 μΩ · m or less in order to reduce the resistance of the electrode substrate. The volume resistivity of the inorganic conductive fiber is measured according to JIS R7601. When the fiber length defined by the measurement prescription is not obtained, the measurement is performed with the obtained fiber length.
[0041]
When carbon fiber is used for the electrode substrate, the atomic ratio of the surface oxygen atoms to carbon atoms (number of oxygen atoms / number of carbon atoms) by X-ray photoelectron spectroscopy is 0.35 or less, preferably 0.20 or less. More preferably, it is 0.10 or less. This is because, when an electrode substrate is obtained by a wet papermaking method, if the atomic ratio of oxygen atoms to carbon atoms is high, it is difficult to disperse the short carbon fibers and the dispersion failure increases. When it exceeds 0.35, it becomes difficult to obtain a uniform electrode substrate. In order to reduce the atomic ratio of oxygen atoms to carbon atoms, there are methods of removing surface oxygen atoms from the surface by applying carbon fiber surface treatment or sizing agent, or by heat treatment in an inert or reducing atmosphere. .
[0042]
The electrode base material is a water repellent treatment to prevent gas diffusion and permeability deterioration due to water retention, a partial water repellent treatment to form a water discharge path, a hydrophilic treatment, and carbon to reduce resistance. It is also a preferred embodiment to add a fine powder.
[0043]
The electrode substrate of the present invention, when using a porous conductive sheet made of conductive inorganic fibers as described above, from the viewpoint of reducing thickness reduction during compression, improving density, reducing electrical resistance, and the like, In particular, it is also a preferred embodiment to include conductive inorganic particles. Such conductive inorganic particles are preferably carbon materials, particularly carbon particles, from the viewpoint of electrical resistance and corrosion resistance.
[0044]
In particular, it is also preferable to use a porous conductive sheet in which conductive inorganic particles having flexibility are arranged in a sheet shape as an electrode substrate. As a result, it is possible to provide an electrode base material that is less likely to drop out of constituent components or is less likely to break even when mechanical force is applied, has a low electrical resistance, and is inexpensive. In particular, the above object can be achieved by using expanded graphite particles as conductive inorganic particles having flexibility.
[0045]
Here, the expanded graphite particles refer to graphite particles obtained by making graphite particles intercalated with sulfuric acid, nitric acid or the like and then expanding them by rapid heating. Usually, the interlayer distance in the crystal structure of the expanded graphite particles is about 50 to 500 times that of the raw graphite particles.
[0046]
The expanded graphite particles themselves are rich in shape deformability. This property is expressed in terms of flexibility. This flexibility is observed by the morphological compatibility of the expanded graphite particles with respect to the expanded graphite particles and other objects adjacent thereto. This morphological compatibility is due to the fact that when expanded graphite particles are subjected to a pressurizing action with at least a part of them overlapping, they are deformed according to the pressurized state and the particles are at least partially joined. Observed. In addition, this morphological compatibility is due to the expanded graphite particles and auxiliary materials used when they are arranged in a sheet form in a state where gas permeability is ensured (for example, flexible materials such as carbon black, which are conventionally used) When conductive inorganic particles having no properties or conventionally used inorganic conductive fibers such as carbon fibers) are pressed together, the expanded graphite particles are deformed along the outer shape of the auxiliary material. And observed by being joined to this auxiliary material.
[0047]
In addition to the conductive fine particles having flexibility, the electrode base material of the present invention is also a preferred embodiment including other conductive particles and conductive fibers, but both the conductive fibers and the conductive particles are By using an inorganic material, an electrode substrate having excellent heat resistance, oxidation resistance, and elution resistance can be obtained. The conductive inorganic particles having no flexibility may include, for example, carbon black powder, graphite powder, metal powder, ceramic powder, etc., but in terms of electronic conductivity and touch resistance, carbon black, graphite, A carbonaceous carbon material is preferred. As such a carbon material, carbon black such as oil furnace black, channel black, lamp black, thermal black, and acetylene black is preferable from the viewpoint of electronic conductivity and a large specific surface area. Oil furnace black includes Vulcan XC-72, Vulcan P, Black Pearls 880, Black Pearls 1100, Black Pearls 1300, Black Pearls 2000, Legal 400, Lion Ketjen Black EC, Mitsubishi Chemical Corporation # 3150. , # 3250, etc., and acetylene black includes Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd. In addition to carbon black, there are artificial graphite and carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, phenol resin and furan resin. It is also possible to use carbon materials obtained by post-processing these carbon materials. Among these carbon materials, in particular, Vulcan XC-72 manufactured by Cabot, Denka Black manufactured by Denki Kagaku Kogyo, Ketjen Black manufactured by Lion, and the like are preferably used from the viewpoint of electronic conductivity.
[0048]
The amount of conductive particles added to the electrode substrate should be appropriately determined according to the required electrode characteristics, the specific surface area of the substance used, the electronic resistance, etc., but the weight ratio in the electrode substrate. 1 to 80% is preferable, and 20 to 60% is more preferable. When the amount of the electron conductor is small, the electronic resistance is lowered, and when the amount is large, the gas permeability is hindered.
[0049]
The electrode substrate of the present invention can be added with a polymer substance in addition to the above conductive particles. Thereby, it becomes strong to a compression and tension | tensile_strength, strength and handling property can be improved, and it can prevent that an inorganic electroconductive substance remove | deviates from an electrode base material, or faces the thickness direction of an electrode base material. In particular, when making an electrode substrate made of a porous conductive sheet by making paper with inorganic conductive short fibers, it is essential to use a polymer substance as a binder. As a method of binding the polymer substance, a fibrous, granular, or liquid polymer substance is mixed when the inorganic conductive substance is oriented in a random direction in a substantially two-dimensional plane, and an inorganic substance is mixed. There is a method of attaching a fibrous or liquid polymer substance to an aggregate in which a conductive substance is oriented in a substantially random direction within a two-dimensional plane. The liquid concept includes emulsions, dispersions, latexes, and the like that can be handled substantially as a liquid by dispersing fine particles of a polymer substance in the liquid. In order to strengthen the binding of the inorganic conductive material or reduce the electric resistance of the electrode base material, the polymer material binding the inorganic conductive material is fibrous, emulsion, dispersion, or latex. Is preferred. In the case of a fibrous polymer substance, it is preferable to use a filament yarn in order to reduce the content rate.
[0050]
The polymer substance that binds the inorganic conductive substance is preferably a polymer substance having carbon or silicon in the main chain, such as polyvinyl alcohol (PVA), polyvinyl acetate (vinyl acetate), polyethylene terephthalate (PET), Thermoplastic resins such as polypropylene (PP), polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polyurethane, phenol resin, epoxy resin, melamine resin, urea resin, alkyd resin, unsaturated polyester resin, acrylic resin In addition to thermosetting resins such as polyurethane resins, thermoplastic elastomers, elastomers such as butadiene / styrene copolymer (SBR), butadiene / acrylonitrile copolymer (NBR), rubber, cellulose, pulp, and the like can be used. . A water repellent resin such as a fluororesin may be used, and the electrode substrate may be subjected to a water repellent treatment simultaneously with the binding of the inorganic conductive material.
[0051]
In order to make the electrode substrate difficult to break when pressed, the polymer material that binds the inorganic conductive material should be soft, and when the polymer material is used in a fibrous or granular form, It is preferable to use a soft polymer material such as a thermoplastic resin, elastomer, rubber, cellulose, or pulp because the electrode substrate is less likely to break when pressed. When the polymer substance is used in a liquid form, the polymer substance is preferably a thermoplastic resin, elastomer, rubber, or a thermosetting resin modified with a soft material such as thermoplastic resin, elastomer, rubber, The thermoplastic resin, elastomer, and rubber are more preferable because the electrode substrate is less likely to break when pressed.
[0052]
The high molecular weight material preferably has a compressive elastic modulus at 23 ° C. of 4,000 MPa or less, more preferably 2,000 MPa or less, and even more preferably 1,000 MPa or less. This is because a polymer material having a low compressive elastic modulus relaxes the stress applied to the binding portion and makes it difficult to release the binding, and also reduces the stress applied to the inorganic conductive material to make it difficult to break.
[0053]
In a polymer electrolyte fuel cell, water as an electrode reaction product or water that has permeated an electrolyte is generated at a cathode (air electrode, oxygen electrode). In the anode (fuel electrode), the fuel is humidified and supplied to prevent the polymer electrolyte membrane from drying. Since the condensation and stagnation of water and swelling of the polymer material by water hinder the supply of the electrode reactant, the water absorption rate of the polymer material should be low. Preferably it is 20% or less, More preferably, it is 7% or less.
[0054]
From such a point, it is also a preferred embodiment that the electrode base material contains a water-repellent polymer. Polymers (fluorine resins) containing fluorine atoms such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), etc. Since it has high water repellency, it is preferably used. When the electrode substrate is used as a current collector (supply) for a fuel cell, water repellent treatment is essential, and the water repellent polymer is bonded between the conductive inorganic substances constituting the electrode substrate. It also has an effect. This is useful in terms of the strength and electrical resistance of the electrode substrate. PTFE, FEP, and PFA have high water repellency and oxidation resistance required for a fuel cell current collector, and PTFE and PFA are more preferable because they provide an effect of low electrical resistance.
[0055]
The content of the polymer substance as described above with respect to the electrode substrate is preferably in the range of 0.1 to 50% by weight. In order to reduce the electric resistance of the electrode substrate, it is better that the content of the polymer substance is small. However, if it is less than 0.1% by weight, the strength to withstand handling is insufficient, and the inorganic conductive substance drops off. On the contrary, when it exceeds 40 weight%, the problem that the electrical resistance of an electrode base material will increase will arise. More preferably, it is in the range of 10 to 30% by weight.
[0056]
It is also a preferred embodiment that the polymer substance added to the electrode substrate is baked at 200 ° C. or higher. The above-mentioned fluororesin used for the water repellent treatment is improved in water repellency and binding properties by heating to the melting point or higher. In addition, in a polymer material other than the fluororesin, not only the binding force is improved by firing, but also the electrical resistance is reduced and the corrosion resistance is improved. In particular, polymer substances other than fluororesins may have poor oxidation resistance, and when used as electrodes for electrochemical devices such as fuel cells, electrode performance may be reduced during use. For this reason, it is preferable to use a polymer substance as a binder at the time of electrode preparation and to fire it before using it as an electrode.
[0057]
The electrode catalyst layer in the electrode of the present invention is not particularly limited, and a known one can be used. The electrode catalyst layer includes a catalyst and an electrode active material necessary for the electrode reaction, and more preferably includes a substance contributing to electron conduction and ion conduction that promotes the electrode reaction. If the electrode active material (oxidizing or reducing substance) is a gas, it must have a structure that allows the gas to easily permeate, and a structure that promotes the discharge of the product accompanying the electrode reaction is required. is there. When the electrode of the present invention is used in a fuel cell, the electrode active material is hydrogen or oxygen, the catalyst is a noble metal particle such as platinum, the electron conductor is carbon black, the ion conductor is a proton exchange resin, and the reaction product is water. is there. The electrode catalyst layer is required to have a structure in which the catalyst, the electron conductor, and the ionic conductor are in contact with each other so that the active material and the reaction product efficiently enter and exit.
[0058]
When the electrode of the present invention is used in a fuel cell, the catalyst contained in the electrode catalyst layer may be a known catalyst, and is not particularly limited, but is not limited to platinum, palladium, gold, ruthenium, iridium, etc. A noble metal catalyst is preferably used. Two or more elements such as alloys and mixtures of these noble metal catalysts may be contained.
[0059]
The electron conductor (conductive material) contained in the electrode catalyst layer is not particularly limited, but an inorganic conductive material is preferably used from the viewpoint of electron conductivity and corrosion resistance. Among these, carbon black, graphite or carbonaceous carbon material, metal or metalloid can be mentioned. As such a carbon material, carbon black such as oil furnace black, channel black, lamp black, thermal black, and acetylene black is preferable from the viewpoint of electronic conductivity and a large specific surface area. Oil furnace black includes Vulcan XC-72, Vulcan P, Black Pearls 880, Black Pearls 1100, Black Pearls 1300, Black Pearls 2000, Legal 400, Lion Ketjen Black EC, Mitsubishi Chemical Corporation # 3150. , # 3250, etc., and acetylene black includes Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd. In addition to carbon black, there are artificial graphite and carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, phenol resin and furan resin. As the form of these carbon materials, not only particles but also fibers can be used. It is also possible to use carbon materials obtained by post-processing these carbon materials. Among these carbon materials, in particular, Vulcan XC-72 manufactured by Cabot is preferably used from the viewpoint of electronic conductivity.
[0060]
The amount of these electron conductors to be added should be appropriately determined according to required electrode characteristics, specific surface area of the substance used, electronic resistance, etc., but is 1 to 80% as a weight ratio in the electrode catalyst layer. Is preferable, and 20 to 60% is more preferable. When the amount of the electron conductor is small, the electronic resistance is low, and when the amount is large, the gas performance is hindered or the catalyst utilization rate is lowered.
[0061]
It is preferable in terms of electrode performance that the electron conductor is uniformly dispersed with the catalyst particles. For this reason, a method in which the catalyst particles and the electron conductor are well dispersed in advance as a coating liquid and this coating liquid is applied onto a porous conductive sheet provided with a conductive intermediate layer is preferably used.
[0062]
When the electrode catalyst layer is used in a fuel cell, it is also a preferred embodiment to use a catalyst-supporting carbon in which a catalyst and an electron conductor are integrated. By using this catalyst-supporting carbon, the utilization efficiency of the catalyst is improved, which contributes to cost reduction. Even when catalyst-supported carbon is used for the electrode catalyst layer, a conductive agent can be further added. As such a conductive agent, the above-described carbon black is preferably used.
[0063]
A well-known thing can be used as an ion conductor used for an electrode catalyst layer, without being specifically limited. Various organic and inorganic materials are known as ion conductors, but when used in fuel cells, they have ion exchange groups such as sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups that improve proton conductivity. A polymer is preferably used. Among these, a polymer having a proton exchange group composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain is preferably used. For example, Nafion manufactured by DuPont, Aciplex manufactured by Asahi Kasei, and Flemion manufactured by Asahi Glass are preferable. These ion exchange polymers can be provided in the electrode catalyst layer in the state of a solution or a dispersion. At this time, the solvent for dissolving or dispersing the proton exchange resin is not particularly limited, but a polar solvent is preferable from the viewpoint of solubility of the proton exchange resin. It may be a polymer containing the above-described fluorine atom having a proton exchange group, another polymer such as ethylene or styrene, a copolymer or a blend thereof.
[0064]
From the viewpoint of electrode performance, it is preferable that the ion conductor is added in advance to a coating liquid mainly composed of electrode catalyst particles and an electron conductor when forming the electrode catalyst layer, and is applied in a uniformly dispersed state. However, the ionic conductor may be applied after the electrode catalyst layer is applied. The method for applying the ionic conductor to the electrode catalyst layer is not particularly limited, such as spray coating, brush coating, dip coating, die coating, curtain coating, and flow coating.
[0065]
The amount of the ionic conductor contained in the electrode catalyst layer should be appropriately determined according to the required electrode characteristics and the conductivity of the ionic conductor used, and is not particularly limited. The ratio is preferably 1 to 80%, and more preferably 5 to 50%. When the ionic conductor is small, the ionic conductivity is low, and when the ionic conductor is large, the gas permeability is hindered.
[0066]
The electrode catalyst layer may contain various substances in addition to the catalyst, the electronic conductor, and the ionic conductor. In particular, in order to enhance the binding property of the substance contained in the electrode catalyst layer, it is also a preferred embodiment to contain a polymer other than the above-described proton exchange resin. Examples of such a polymer include a polymer containing a fluorine atom and are not particularly limited. For example, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyhexafluoropropylene (FEP), Polytetrafluoroethylene, polyperfluoroalkyl vinyl ether (PFA), etc., or copolymers thereof, copolymers of these monomer units with other monomers such as ethylene and styrene, and blends can also be used. . The content of these polymers in the catalyst layer is preferably 5 to 40% by weight. If the polymer content is too high, the electron and ionic resistance increases and the electrode performance decreases.
[0067]
In the electrode catalyst layer, it is also preferable that the catalyst-polymer composite has a three-dimensional network microporous structure. The catalyst-polymer composite is a polymer composite containing catalyst particles, and is characterized by a three-dimensional network microporous structure. The “three-dimensional network microporous structure” refers to a state in which a catalyst-polymer complex has a three-dimensional network structure that is three-dimensionally connected.
[0068]
When the electrode catalyst layer has a three-dimensional network microporous structure, the microporous diameter is preferably 0.05 to 5 μm. More preferably, it is 0.1-1 micrometer. The microporous diameter can be determined from an average of 20 or more, preferably 100 or more from a photograph of the surface taken with a scanning electron microscope (SEM) or the like, and can usually be measured with 100. The catalyst layer having a microporous structure of the present invention when manufactured by a wet coagulation method has a wide distribution of microporous diameters, and therefore it is preferable to average as many pore diameters as possible.
[0069]
The porosity of the three-dimensional network microporous structure is preferably 10 to 95%. More preferably, it is 50 to 90%. The porosity is a percentage (%) obtained by dividing the total volume of the catalyst layer by the volume of the catalyst-polymer complex divided by the total volume of the catalyst layer. The catalyst layer is wet-coagulated after being applied to the electrode substrate, proton exchange membrane, and other substrates. If it is difficult to obtain the porosity of the catalyst layer alone, the electrode substrate, proton It is also possible to obtain the porosity of the catalyst layer alone after obtaining the porosity of the exchange membrane and other base materials in advance and obtaining the porosity including these base materials and the catalyst layer. .
[0070]
Electrocatalyst layers, especially those with a three-dimensional network microporous structure obtained by the wet coagulation method, have high porosity, good gas diffusivity and good water discharge, and electronic conductivity and proton conductivity. Is also good. In conventional porosification, the catalyst particle size and the particle size of the added polymer are increased, or pores are formed using a pore-forming agent. In addition, the contact resistance between the proton exchange resins is larger than that of the electrode catalyst layer. On the other hand, in the three-dimensional network microporous structure by the wet coagulation method, the polymer composite containing the catalyst-supporting carbon has a three-dimensional network shape, so that electrons and protons can easily conduct through this polymer composite, Furthermore, because of the microporous structure, gas diffusibility and discharge of generated water are also good.
[0071]
Even when the electrode catalyst layer has a three-dimensional microporous structure, the same materials as those used in the past can be used for the catalyst, the electron conductor, and the ion conductor. However, it is preferable to use a wet coagulation method when preparing an electrode catalyst layer having a three-dimensional network microporous structure. Therefore, in the above case, it is preferable to use a polymer suitable for this wet coagulation method, and it is preferable to use a polymer in which the catalyst particles are well dispersed and does not deteriorate in the oxidation-reduction atmosphere in the fuel cell. Examples of such a polymer include a polymer containing a fluorine atom and are not particularly limited. For example, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyhexafluoropropylene (FEP), Polyperfluoroalkyl vinyl ether (PFA) or the like, copolymers thereof, copolymers of these monomer units with other monomers such as ethylene and styrene (for example, hexafluoropropylene-vinylidene fluoride copolymer), and Blends can also be used.
[0072]
Among these, polyvinylidene fluoride (PVDF) and hexafluoropropylene-vinylidene fluoride copolymer are three-dimensional network microporous by a wet coagulation method using an aprotic polar solvent and a protic polar solvent as a coagulation solvent. This is a particularly preferred polymer in that a catalyst-polymer complex having a crystalline structure is obtained. Examples of the solvent for these polymers include N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), propylene carbonate (PC), dimethylimidazolidinone (DMI), and the like. In addition to lower alcohols such as methanol, ethanol and isopropanol, esters such as ethyl acetate and butyl acetate, and various organic solvents such as aromatic and halogen compounds are used.
[0073]
As the polymer of the catalyst-polymer complex, in addition to the above-mentioned polymer, a polymer having a proton exchange group is also preferable in order to improve proton conductivity. Proton exchange groups contained in such polymers include sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups, but are not particularly limited. A polymer having such a proton exchange group is also selected without particular limitation, but a polymer having a proton exchange group composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain is preferably used. For example, Nafion manufactured by DuPont is also preferable. Moreover, the polymer which contains the above-mentioned fluorine atom which has a proton exchange group, other polymers, such as ethylene and styrene, these copolymers, and a blend may be sufficient.
[0074]
The Nafion polymer solution may be obtained by dissolving a commercially available Nafion membrane in an aprotic polar solvent, a Nafion solution of water-methanol-isopropanol mixed solvent manufactured by Aldrich, or a solution obtained by replacing this Nafion solution with a solvent. good. In this case, the coagulation solvent at the time of wet coagulation should be appropriately determined depending on the solvent of the Nafion solution, but when the solvent of the Nafion solution is an aprotic polar solvent, the coagulation solvent is water or alcohols. In addition to esters, various organic solvents are preferable, and in the case of a water-methanol-isopropanol mixed solvent, esters such as butyl acetate and various organic solvents are preferably used.
[0075]
As the polymer used in the catalyst-polymer composite, it is also preferable to use a polymer containing or blended with the above-described polymer containing a fluorine atom or a polymer containing a proton exchange group. In particular, blending a polyvinylidene fluoride, poly (hexafluoropropylene-vinylidene fluoride) copolymer, etc. with a polymer such as Nafion having a fluoroalkyl ether side chain and a fluoroalkyl main chain in the proton exchange group is effective in electrode performance. From the point of view, it is preferable.
[0076]
The main components of the catalyst-polymer composite are catalyst-supported carbon and polymer, and the ratio thereof should be appropriately determined according to the required electrode characteristics and is not particularly limited. The weight ratio of 5/95 to 95/5 is preferably used. In particular, when used as an electrode catalyst layer for a polymer electrolyte fuel cell, the catalyst-supported carbon / polymer weight ratio is preferably 40/60 to 85/15.
[0077]
It is also a preferred embodiment to add various additives to the catalyst-polymer complex. For example, there is a conductive agent such as carbon for improving the electronic conductivity, a polymer for improving the binding property, an additive for controlling the pore size of the three-dimensional network microporous structure, but there is no particular limitation. Can be used. The addition amount of these additives is preferably 0.1 to 50%, more preferably 1 to 20% as a weight ratio with respect to the catalyst-polymer composite.
[0078]
The method for producing a catalyst-polymer composite having a three-dimensional network microporous structure is preferably a wet coagulation method. In this wet coagulation method, after the catalyst-polymer solution composition is applied, the coating layer is brought into contact with a coagulation solvent for the polymer, and coagulation precipitation and solvent extraction of the catalyst-polymer solution composition are performed simultaneously.
[0079]
In this catalyst-polymer solution composition, catalyst-supported carbon is uniformly dispersed in the polymer solution. The aforementioned catalyst-supporting carbon and polymer are preferably used. The solvent for dissolving the polymer should be appropriately determined according to the polymer used, and is not particularly limited. It is important that the polymer solution is well dispersed with the catalyst-supporting carbon. When the dispersion state is poor, the catalyst-supporting carbon and the polymer cannot form a composite during wet coagulation, which is not preferable.
[0080]
As for the coating method, a coating method according to the viscosity and solid content of the catalyst-polymer solution composition is selected and should not be particularly limited. However, a knife coater, a bar coater, a spray, a dip coater, a spin coater, A general coating method such as a roll coater, a die coater, or a curtain coater is used.
[0081]
On the other hand, the coagulation solvent for wet coagulating the polymer is not particularly limited, but a solvent that easily coagulates and precipitates the polymer to be used and is compatible with the solvent of the polymer solution is preferable. The contact method with the coagulation solvent in which wet coagulation is actually performed is not particularly limited, but the coagulation solvent is immersed in the coagulation solvent with the base material, only the coating layer is brought into contact with the liquid surface of the coagulation solvent. There is no particular limitation such as showering or spraying on the coating layer.
[0082]
The substrate on which the catalyst-polymer solution composition is applied can be applied to either the electrode substrate or the solid electrolyte, and then wet coagulation can be performed. By performing the solidification, it is possible to suppress the penetration of the catalyst layer into the electrode substrate, which is a preferred embodiment of the present invention. In addition, after applying to a substrate (transfer substrate) other than the electrode substrate or solid electrolyte, and then performing wet coagulation to create a three-dimensional network microporous structure, this catalyst layer is applied to the electrode substrate or solid electrolyte. It may be transferred or clamped. As the transfer substrate in this case, a polytetrafluoroethylene (PTFE) sheet, or a glass plate or a metal plate whose surface is treated with a fluorine or silicone release agent is also used.
[0083]
The electrode of the present invention is intended to reduce a wasteful catalyst that is not effectively used by reducing the thickness of the mixed layer in which the electrode catalyst layer is immersed in the electrode base material to a thickness of 20 μm or less. The manufacturing method is not particularly limited. When a porous conductive sheet is used for the electrode base material, the electrode catalyst layer coating solution is likely to penetrate into the electrode base material, and thus a device that does not penetrate is necessary to obtain the electrode of the present invention. For example, there are methods such as increasing the viscosity of the electrode catalyst layer coating liquid and increasing the difference in surface energy between the electrode base material and the polymer material contained therein and the electrode catalyst layer coating liquid.
[0084]
When the viscosity of the electrode catalyst layer coating liquid is increased, penetration into the porous conductive sheet is suppressed. To increase the viscosity, increase the solid content ratio of the catalyst layer coating solution other than the solvent, increase the molecular weight of the polymer substance contained in the catalyst layer coating solution, and add various thickeners to the catalyst layer coating solution. There are methods. Examples of thickeners include polyhydric alcohols such as glycerin, higher alcohols such as octanol, celluloses such as carboxymethylcellulose and hydroxypropylcellulose, polymer compounds such as polyvinyl alcohol and polyvinylpyrrolidone, acetylene black, ketjen Carbon blacks such as black are preferable, but are not particularly limited.
[0085]
When utilizing the surface energy difference between the electrode substrate and the polymer contained therein and the electrode catalyst layer coating solution, the static contact angle between the electrode substrate and the electrode catalyst layer coating solution is 50 ° or more (more preferably 70 ° or more). It is possible to suppress penetration. When the electrode base material is used in a fuel cell, it contains a fluororesin for water repellent treatment and has a low surface free energy. For this reason, by using the electrode catalyst layer coating liquid containing a solvent having a large surface free energy, the static contact angle is increased and the penetration is suppressed. The electrode catalyst layer contains a proton exchange resin as an ionic conductor. For this reason, the catalyst layer coating liquid containing the ion exchange resin contains water, and in such a case, the penetration is suppressed by increasing the static contact angle. When the electrode base material contains a fluororesin, use of N-methylpyrrolidone in addition to water as a solvent for the electrode catalyst layer coating liquid increases the static contact angle and suppresses penetration. The measurement of the static contact angle may be a general measurement method in which a drop of the catalyst layer coating solution is dropped on a substrate with a microsyringe and measured with a microscope from the side.
[0086]
It is also a preferred embodiment that the electrode of the present invention is made into a membrane-electrode assembly (MEA) by combining with a solid electrolyte layer.
[0087]
The solid electrolyte constituting the solid electrolyte layer is not particularly limited as long as it is a solid electrolyte used in a normal fuel cell, but a proton exchange membrane is preferable in order to express the fuel cell performance of the present invention. Used. The proton exchange group of the proton exchange membrane is not particularly limited, such as a sulfonic acid group, a carboxylic acid group, and a phosphoric acid group.
[0088]
This proton exchange membrane includes a hydrocarbon system such as a styrene-divinylbenzene copolymer having the above proton exchange group, particularly a sulfonic acid group, a fluorine atom-containing polymer, particularly a fluoroalkyl ether side chain and a fluoroalkyl main chain. It is roughly classified into perfluoro-based copolymers composed of the following, and should be appropriately selected according to the application and environment in which the fuel cell is used. From the point of view, it is preferable. A partial fluorine film partially substituted with fluorine atoms is also preferably used. Examples of perfluoro membranes include DuPont's Nafion, Asahi Kasei Aciplex, Asahi Glass Flemion, and Japan Gore-Tex's Goa-select. Some have acid groups introduced. In addition, proton exchange membranes are reinforced with not only one type of polymer, but also a copolymer or blend polymer of two or more types of polymers, a composite membrane in which two or more types of membranes are bonded together, and a proton exchange membrane with a nonwoven fabric or a porous film. The film | membrane etc. which were made can also be used.
[0089]
It does not specifically limit as a manufacturing method of a membrane-electrode composite_body | complex. In general, an electrode catalyst layer is provided on an electrode substrate to create an electrode, and this electrode is bonded to a solid electrolyte such as a proton exchange membrane. The bonding conditions also depend on the characteristics of the electrode catalyst layer or the electrochemical device. It should be decided appropriately according to the situation.
[0090]
In making use of the characteristics of the electrode of the present invention, two electrodes composed of an electrode base material and an electrode catalyst layer are prepared in advance, and a proton exchange membrane is formed between these two electrodes. A MEA manufacturing method is preferred in which the side is disposed so as to face the proton exchange membrane, and the proton exchange membrane is sandwiched and joined by the two electrodes. This joining is a heating press, but this condition is not particularly limited. Generally, the press temperature is 20 ° C. to 200 ° C., and the press pressure is 1 MPa to 20 MPa.
[0091]
As other membrane-electrode composite production methods, a step of providing the electrode catalyst layer on both front and back surfaces of the proton exchange membrane (step A), and a step of providing an electrode substrate on both outer sides of the electrode catalyst layer (step B) It is also a preferable manufacturing method to carry out in this order. Since this method does not apply the catalyst layer to the electrode base material, it is a method that makes it possible to create an MEA comprising the electrode of the present invention in terms of suppressing the permeation of the catalyst layer into the base material.
[0092]
In particular, an MEA production method in which an electrode catalyst layer coating solution is applied onto a proton exchange membrane and an electrode base material is provided thereafter is also preferable. In this case, since the proton exchange membrane to which the catalyst coating liquid is applied is likely to swell with water or an organic solvent, it is necessary to select a solvent that does not easily swell the proton exchange membrane as the solvent used in the catalyst layer coating liquid. However, the catalyst layer coating liquid contains a proton exchange resin, and a solvent that dissolves the proton exchange resin swells or dissolves the proton exchange membrane. For this reason, in the catalyst layer coating liquid, it is preferable to use a solvent that is dispersed in the form of an emulsion or the like without dissolving the contained proton exchange resin. For example, the proton exchange resin solution is removed, dried and pulverized, and the resulting proton exchange resin powder and catalyst-supported carbon are mixed and dispersed in a solvent that does not swell the proton exchange membrane, or the proton exchange resin solution Examples of the method include, but are not limited to, a method of removing the dispersion with the catalyst-supported carbon, drying and pulverizing, and redispersing the obtained powder in a proton exchange resin and a solvent that does not swell.
[0093]
Furthermore, in the above step A, it is also preferred that the electrode catalyst coating liquid is applied on a transfer substrate other than the electrode substrate or the proton exchange membrane to form an electrode catalyst layer, and this is transferred onto the proton exchange membrane. It is a manufacturing method. As the transfer substrate at this time, it is possible to use a transfer substrate such as a sheet or a film made of various resins or fluororesins such as PTFE, PFA, FEP, a glass plate, and the like. In particular, it is possible to transfer an electrocatalyst layer onto a proton exchange membrane by applying an electrode catalyst layer to a sheet or film and roll pressing it with the proton exchange membrane.
[0094]
In the step B, it is also a preferable MEA production method to provide the electrode base material by applying a substance constituting the electrode base material to the proton exchange membrane. The MEA is produced by spraying the inorganic conductive fibers and particles constituting the electrode base material in a liquid or solid state onto a proton exchange membrane provided with an electrode catalyst layer. In particular, in the case where the inorganic conductive material constituting the electrode substrate is a short carbon fiber, a dispersion containing this and a fluorine atom-containing polymer is prepared in advance, and this dispersion is placed on the proton exchange membrane provided with the electrode catalyst layer. It is also preferable to apply the coating by spraying.
[0095]
The electrode comprising the electrode substrate and the electrode catalyst layer of the present invention, or the membrane-electrode assembly (MEA) comprising the electrode and a solid electrolyte membrane can be applied to various electrochemical devices. Of these, a fuel cell and a water electrolysis layer are preferable, and among the fuel cells, a polymer electrolyte fuel cell is preferable. Fuel cells include those using hydrogen as fuel and those using hydrocarbons such as methanol as fuel, but can be used without any particular limitation.
[0096]
Further, the use of the fuel cell using the electrode catalyst layer of the present invention is not particularly limited, but a mobile power supply source that is useful in a polymer electrolyte fuel cell is preferable. is there. In particular, automobiles such as passenger cars, buses, and trucks, ships, railways, and the like are also preferable moving bodies.
[0097]
【Example】
Hereinafter, the details of the present invention will be further described using examples.
[0098]
Example 1
(1) Creation of electrode substrate
Carbon paper (TGP-H-060 manufactured by Toray Industries, Inc.) was used as the porous conductive sheet, and this was used as a PTFE dispersion (manufactured by Daikin Industries: Polyflon TFE D-1, dispersion average particle size 0.2-0.4 μm, 60 weight). %, Aqueous solution), dried, and fired at 370 ° C. The amount of PTFE applied was 20% by weight.
[0099]
(2) Preparation of catalyst layer coating solution
A commercially available Aldrich Nafion solution (5 wt%) was concentrated to 15 wt%. To 10 g of this concentrated Nafion solution, 3 g of catalyst-supported carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-supported amount: 50 wt%) was added and stirred well to prepare a catalyst layer coating solution composed of a catalyst-polymer composition. Prepared.
[0100]
(3) Application of electrode catalyst layer coating solution and creation of electrode by drying
On the porous conductive sheet prepared in the above (1), the catalyst layer coating solution prepared in the above (2) was applied and dried to prepare an electrode composed of an electrode substrate and an electrode catalyst layer. The obtained electrode has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0101]
A cross-sectional SEM photograph of this electrode is shown in FIG. 1 (1), and platinum distribution by X-ray microanalysis is shown in FIG. 1 (3). The thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 10 μm, and the pure catalyst layer not including the mixed layer was 15 μm.
[0102]
Comparative Example 1
(1) Creation of electrode substrate
Similarly to Example 1, carbon paper (TGP-H-060 manufactured by Toray Industries, Inc.) was used as a porous conductive sheet, impregnated with PTFE dispersion (manufactured by Daikin Industries: Polyflon PTFE dispersion), dried, and 370 ° C. Baked in. The amount of PTFE applied was 20% by weight.
[0103]
(2) Preparation of catalyst layer coating solution
Using a commercially available Alfrich Nafion solution (5 wt%) as it is, added catalyst-supported carbon (catalyst; Pt, carbon; Cabot Vulcan XC-72, platinum-supported amount: 50 wt%), and stirred well to prepare a catalyst. A catalyst layer coating solution comprising a polymer composition was prepared.
[0104]
(3) Application of electrode catalyst layer coating solution and creation of electrode by drying
On the porous conductive sheet prepared in the above (1), the catalyst layer coating solution prepared in the above (2) was applied and dried to prepare an electrode composed of an electrode substrate and an electrode catalyst layer. The obtained electrode has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0105]
From the cross-sectional SEM photograph of this electrode, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 40 μm.
[0106]
Example 2
(1) Creation of electrode substrate
Carbon paper (TGP-H-060 manufactured by Toray Industries, Inc.) was used as the porous conductive sheet, impregnated in a PFA dispersion (manufactured by Daikin Industries: NEOFLON PFA AD-2CR), dried, and fired at 320 ° C. The amount of PFA applied was 20% by weight.
[0107]
(2) Preparation of catalyst layer coating solution
0.1% by weight of carboxymethylcellulose was added as a thickener to a commercially available Nafion solution (5% by weight) manufactured by Aldrich. To this, catalyst-supported carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-supported amount: 50 wt%) was added, and stirred well to prepare a catalyst layer coating solution comprising a catalyst-polymer composition.
[0108]
(3) Application of electrode catalyst layer coating solution and creation of electrode by drying
On the porous conductive sheet prepared in the above (1), the catalyst layer coating solution prepared in the above (2) was applied and dried to prepare an electrode composed of an electrode substrate and an electrode catalyst layer. The obtained electrode has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0109]
From the cross-sectional SEM photograph of this electrode, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 10 μm.
[0110]
Example 3
(1) Creation of electrode substrate
Similarly to Example 2, carbon paper (TGP-H-060 manufactured by Toray Industries, Inc.) was used as the porous conductive sheet, impregnated in a PFA dispersion (manufactured by Daikin Industries: NEOFLON PFA dispersion), dried, and 320 ° C. Baked in. The amount of PFA applied was 20% by weight.
[0111]
(2) Preparation of catalyst layer coating solution
N-methylpyrrolidone was added while concentrating a commercially available Aldrich Nafion solution (5% by weight) to perform solvent replacement. The resulting Nafion solution was 10% by weight. To this was added catalyst-carrying carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-carrying amount; 50 wt%), and the mixture was well stirred to prepare a catalyst layer coating solution comprising a catalyst-polymer composition.
[0112]
(3) Preparation of an electrode catalyst layer by applying and drying a catalyst-polymer composition
On the porous conductive sheet prepared in the above (1), the catalyst layer coating solution prepared in the above (2) was applied and dried to prepare an electrode composed of an electrode substrate and an electrode catalyst layer. The obtained electrode has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0113]
The static contact angle when a drop of the catalyst layer coating solution was allowed to stand on this electrode substrate was 90 °.
[0114]
From the cross-sectional SEM photograph of this electrode, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 15 μm.
[0115]
Example 4
(1) Creation of electrode substrate
Similarly to Example 1, carbon paper (TGP-H-060 manufactured by Toray Industries, Inc.) was used as a porous conductive sheet, impregnated with PTFE dispersion (manufactured by Daikin Industries: Polyflon PTFE dispersion), dried, and 370 ° C. Baked in. The amount of PTFE applied was 20% by weight.
[0116]
(2) Preparation of catalyst layer coating solution
A commercially available Aldrich Nafion solution (5 wt%) was concentrated to 10 wt%. To this was added catalyst-carrying carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-carrying amount; 50 wt%), and the mixture was well stirred to prepare a catalyst layer coating solution comprising a catalyst-polymer composition.
[0117]
(3) Preparation of microporous electrode by applying electrode catalyst layer, wet coagulation, and drying
After applying the catalyst layer coating solution prepared in (2) above on the porous conductive sheet prepared in (1), the electrode substrate and the microporous electrode catalyst layer are immediately immersed in butyl acetate and dried. An electrode composed of The obtained electrode has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0118]
From the cross-sectional SEM photograph of this electrode, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 10 μm.
[0119]
Example 5
(1) Creation of porous conductive sheet
Short fibers of PAN-based carbon fibers cut to a length of 12 mm and expanded graphite powder (manufactured by Toyo Tanso Co., Ltd., bulk density 0.14 g / cm^Three, Average particle diameter of 100 to 200 μm) was mixed at a weight ratio of 1: 1 and dispersed in an aqueous sodium carboxymethylcellulose solution. Using this dispersion, a sheet in which expanded graphite powder was adhered to short carbon fibers was made on a wire mesh. In order to remove moisture, the sheet was sandwiched between two filter papers and lightly pressed. Thereafter, the filter paper was removed and the sheet was dried. After drying, the sheet was roll-pressed to produce a porous conductive sheet. The obtained sheet is 80 g / m.²Met.
[0120]
(2) Creation of electrode substrate
The porous conductive sheet prepared in (1) above is heat-treated in air at 200 ° C. for 30 minutes, and then impregnated with PFA dispersion (Neoflon PFA dispersion, manufactured by Daikin Industries, Ltd.), and two filter papers It was lightly pressed and dried between. Furthermore, this sheet was 14.7 kPa (0.15 kgf / cm²The porous conductive sheet was manufactured by performing a heat treatment at 400 ° C. for 3 hours while applying pressure in the step). The amount of PFA applied was 15% by weight.
[0121]
(3) Creation of electrode catalyst layer
N-methylpyrrolidone was added while concentrating a commercially available Aldrich Nafion solution (5% by weight) to perform solvent replacement. The resulting Nafion solution was 10% by weight. To this was added catalyst-carrying carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-carrying amount; 50 wt%), and the mixture was well stirred to prepare a catalyst layer coating solution comprising a catalyst-polymer composition.
[0122]
(4) Application of electrode catalyst layer coating solution and creation of electrode by drying
On the porous conductive sheet prepared in (2), the catalyst layer coating solution prepared in (3) was applied and dried to prepare an electrode composed of an electrode substrate and an electrode catalyst layer. The obtained electrode has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0123]
The static contact angle when a drop of the catalyst layer coating solution was allowed to stand on this electrode substrate was 90 °.
[0124]
From the cross-sectional SEM photograph of this electrode, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 15 μm.
[0125]
Example 6
(1) Creation of electrodes
An electrode was prepared in the same manner as in Example 2.
[0126]
(2) Membrane-electrode composite (MEA)
Two electrodes prepared in the above (1) were prepared, and sandwiched with the electrode catalyst layer surfaces facing each other from both sides of the proton exchange membrane (Nafion 112 manufactured by DuPont). This was hot pressed at 150 ° C. and 150 MPa to prepare an MEA.
[0127]
When the cross section of this MEA was observed by SEM, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 10 μm.
[0128]
(3) MEA fuel cell performance evaluation
The MEA prepared in (2) was evaluated for fuel cell performance by current-voltage (IV) measurement. Evaluation cell temperature is 70 ° C., anode (fuel) gas is hydrogen, cathode (oxidation) gas is air, and gas pressure is a maximum output of 450 mW / cm at normal pressure.²It showed good performance.
[0129]
Comparative Example 2
An MEA was prepared in the same manner as in Example 6 using the electrode prepared in Comparative Example 1.
[0130]
In SEM observation of this MEA cross section, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 30 μm.
[0131]
Furthermore, this MEA was subjected to IV measurement under the same conditions as in Example 6, but the maximum output was 250 mW / cm.²Compared with Example 6, the output was low and the performance was inferior.
[0132]
Example 7
(1) Preparation of electrode catalyst layer coating solution
A commercially available proton exchange resin solution (Nafion solution manufactured by Aldrich) was freeze-dried and freeze-pulverized to prepare proton exchange resin powder. Add 1.5 g of this powder and 3 g of catalyst-supported carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-supported amount: 50 wt%) to 10 g of butyl acetate, thoroughly mix and disperse, and coat the catalyst layer. A liquid was created.
[0133]
(2) Creation of MEA
The electrode catalyst layer coating solution prepared in (1) above was applied to both surfaces of a commercially available proton exchange membrane (DuPont Nafion 112) and dried. From both sides, a carbon cloth (ELAT manufactured by E-TEK) was sandwiched as an electrode base material to prepare an MEA.
[0134]
When the cross-sectional SEM observation of the obtained MEA was performed, the thickness of the mixed layer in which the electrode catalyst layer soaked into the electrode substrate was 5 μm.
[0135]
(3) MEA fuel cell performance evaluation
The MEA prepared in (2) was evaluated for fuel cell performance by current-voltage (IV) measurement. The evaluation cell temperature is 70 ° C., the anode (fuel) gas is hydrogen, the cathode (oxidation) gas is oxygen, and the gas pressure is a maximum pressure of 800 mW / cm at normal pressure.²It showed good performance.
[0136]
Example 8
(1) Preparation of electrode catalyst layer coating solution
Add 1 g of catalyst-supported carbon (catalyst; Pt, carbon; Vulcan XC-72 from Cabot, platinum loading: 50 wt%) to 10 g of a commercially available proton exchange resin solution (5% Nafion solution manufactured by Aldrich) and mix thoroughly. After dispersion, the solvent was removed by drying and pulverized to obtain a powder. 8 g of dioxane was added to this powder and mixed and dispersed sufficiently to prepare a catalyst layer coating solution.
[0137]
(2) Creation of MEA
Similarly to Example 7 (2), an MEA was prepared using the electrode catalyst layer coating solution prepared in (1) and the electrode substrate prepared in Example 5 (1). From the cross-sectional SEM observation of the obtained MEA, the thickness of the mixed layer was 5 μm.
[0138]
(3) MEA fuel cell performance evaluation
The MEA prepared in (2) was evaluated for fuel cell performance by current-voltage (IV) measurement. The evaluation cell temperature is 80 ° C., the anode (fuel) gas is hydrogen, the cathode (oxidation) gas is air, the gas pressure is 0.2 MPa, and the maximum output is 850 mW / cm.²It showed good performance.
[0139]
Example 9
(1) Creation of electrode substrate
An electrode substrate was prepared in the same manner as in Example 5 (1) and (2).
[0140]
(2) Creation of electrode catalyst layer
Add catalyst-supported carbon (catalyst; Pt, carbon; Cabot's Vulcan XC-72, platinum-supported amount: 50 wt%) to a commercially available Nadion solution (5 wt%) from Aldrich and stir well to obtain catalyst-polymer composition. A catalyst layer coating solution was prepared. This catalyst layer coating solution was applied on a 100 μm thick Teflon sheet and dried to prepare an electrode catalyst layer. The obtained electrocatalyst layer has a platinum content of 0.5 mg / cm.², Nafion amount 0.3mg / cm²Met.
[0141]
(3) Transfer of electrode catalyst layer to proton exchange membrane
Two electrode catalyst layers prepared in the above (2) were prepared and sandwiched with the electrode catalyst layer surfaces facing each other from both sides of the proton exchange membrane (Nafion 112 manufactured by DuPont). This was roll-pressed to transfer the electrode catalyst layer to the proton exchange membrane to produce a proton exchange membrane with an electrode catalyst layer.
[0142]
(4) Creation of MEA
Using the proton exchange membrane with an electrode catalyst layer prepared in (3) above, MEA was prepared by sandwiching two electrode base materials prepared in (1) from both sides. From the cross-sectional SEM observation of this MEA, the thickness of the mixed layer was 5 μm.
[0143]
(5) MEA performance evaluation
The MEA prepared in (4) was evaluated for fuel cell performance by current-voltage (IV) measurement. Evaluation cell temperature is 60 ° C., anode (fuel) gas is hydrogen, cathode (oxidation) gas is air, and gas pressure is a maximum output of 350 mW / cm at normal pressure.²It showed good performance.
[0144]
Example 10
(1) Preparation of electrode catalyst layer coating solution
A commercially available proton exchange resin solution (Nafion solution manufactured by Aldrich) was freeze-dried and freeze-pulverized to prepare proton exchange resin powder. Add 1.5 g of this powder and 3 g of catalyst-supported carbon (catalyst; Pt, carbon; Vulcan XC-72 manufactured by Cabot, platinum-supported amount: 50 wt%) to 10 g of butyl acetate, thoroughly mix and disperse, and coat the catalyst layer. A liquid was created.
[0145]
(2) Preparation of electrode substrate coating liquid
Short fibers of PAN-based carbon fibers cut to a length of 12 mm and expanded graphite powder (manufactured by Toyo Tanso Co., Ltd., bulk density 0.14 g / cm^Three, Average particle size of 100 to 200 μm) is mixed at a weight ratio of 1: 1, and sufficiently mixed and dispersed in a PFA dispersion (neoflon PFA dispersion, manufactured by Daikin Industries, Ltd.) to create an electrode base material coating solution did. The amount of PFA applied was 15% by weight.
[0146]
(3) Creation of MEA
The electrode catalyst layer coating solution prepared in (1) above was applied to both surfaces of a commercially available proton exchange membrane (DuPont Nafion 112) and dried. From both sides, the electrode catalyst layer coating solution prepared in (2) was applied and dried to prepare an MEA.
[0147]
From the cross section SEM of the obtained MEA, the thickness of the mixed layer was 5 μm.
[0148]
(4) MEA performance evaluation
The MEA prepared in (3) was evaluated for fuel cell performance by current-voltage (IV) measurement. The evaluation cell temperature is 70 ° C., the anode (fuel) gas is hydrogen, the cathode (oxidation) gas is oxygen, and the gas pressure is a maximum output of 500 mW / cm at normal pressure.²It showed good performance.
[0149]
【The invention's effect】
According to the present invention, an electrode with little catalyst permeation can be obtained. Therefore, the utilization efficiency of the catalyst is improved, and a low cost electrode can be obtained by reducing the amount of catalyst.
[0150]
The electrode of the present invention is applied not only to a membrane-electrode assembly (MEA) but also to an ordinary electrochemical device, particularly a polymer electrolyte fuel cell, and also to a mobile body and an automobile using this fuel cell. Applicable.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of the present invention.
[Explanation of symbols]
1: Scanning electron micrograph of a cross section of an example of the present invention
2: Cross section display
3: Platinum distribution map by X-ray microanalysis of the cross section of the embodiment of the present invention

Claims (27)

At least in an electrode composed of an electrode base material and an electrode catalyst layer, the electrode catalyst layer penetrates into the electrode base material to form a mixed layer, and the thickness of the mixed layer is 3 μm. electrode, characterized in that at 20μm or less. The electrode according to claim 1, wherein the mixed layer has a thickness of 10 μm or less. The electrode according to claim 1 or 2, wherein the electrode substrate is a porous conductive sheet. The electrode according to claim 3, wherein the porous conductive sheet has a woven fabric structure or a nonwoven fabric structure using inorganic conductive fibers. The electrode according to claim 4, wherein the inorganic conductive fiber is carbon fiber. The electrode according to any one of claims 1 to 5, wherein the electrode substrate contains conductive particles. The electrode according to claim 6, wherein the conductive particles are a carbon material. The electrode in any one of Claims 1-7 in which an electrode base material contains the polymer containing a fluorine atom. The electrode according to any one of claims 1 to 8, wherein the electrode catalyst layer contains at least one element selected from the group consisting of platinum, palladium, gold, ruthenium, and iridium. The electrode according to claim 1, wherein the electrode catalyst layer contains carbon black. The electrode according to claim 1, wherein the electrode catalyst layer contains a polymer containing fluorine atoms. The electrode according to claim 1, wherein the electrode catalyst layer contains a polymer having a proton exchange group. The method for producing an electrode according to any one of claims 1 to 12, wherein an electrode catalyst coating solution is applied onto the electrode substrate. The method for producing an electrode according to claim 13, wherein a static contact angle between the electrode substrate and the electrode catalyst coating liquid is 50 ° or more. A membrane-electrode composite comprising the electrode according to claim 1 and a proton exchange membrane. The membrane-electrode assembly according to claim 15, wherein the proton exchange membrane is a fluorine atom-containing polymer. The membrane-electrode assembly according to claim 16, wherein the fluorine atom-containing polymer is a polymer comprising a fluoroalkyl ether side chain having a sulfonic acid group and a fluoroalkyl main chain. A proton exchange membrane is disposed between two electrodes according to any one of claims 1 to 12 so that the electrode catalyst layer side of each electrode faces the proton exchange membrane, and the proton exchange is performed by the two electrodes. A method for producing a membrane-electrode composite comprising sandwiching and joining membranes. The electrochemical apparatus using the electrode in any one of Claims 1-12. An electrochemical device using the membrane-electrode assembly according to any one of claims 15 to 17. The water electrolysis apparatus using the electrode in any one of Claims 1-12. A water electrolysis apparatus using the membrane-electrode assembly according to any one of claims 15 to 17. A fuel cell using the electrode according to claim 1. A fuel cell using the membrane-electrode assembly according to claim 15. The fuel cell according to claim 23 or 24 , wherein a solid polymer electrolyte is used. A mobile body using the fuel cell according to any one of claims 23 to 25 as a power supply source. An automobile using the fuel cell according to any one of claims 23 to 25 as a power supply source.

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