Electrochemical reaction apparatus and current conductor

Abstract

To reduce a weight of an apparatus, such as an electrochemical reaction apparatus, in which an electrochemical reaction is performed.SOLUTION: An electrochemical reaction apparatus includes: a reaction part in which an electrochemical reaction is performed; a current supply part for supplying current to or receiving current from the reaction part; and a sheet-like reaction part having a catalyst layer including a reaction catalyst used for the electrochemical reaction, wherein: a surface of the reaction part is in contact with a fluid used for the electrochemical reaction; and the current supply part has a current conductor in contact with the reaction part. The surface of the reaction part is a contact surface abutting the current conductor, and the current conductor is a porous body made of a foam constituted of a polymer composition including a conductive polymer in which the polymer itself has electronic conductivity. A current conductor used in such an apparatus is also provided.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electrochemical reaction device in which an electrochemical reaction takes place and a current conductor used as a flow path for electricity in the electrochemical reaction device or the like. [Background technology]

[0002] In recent years, there has been an increasing use of electrochemical reaction devices that utilize electrochemical reactions, such as fuel cells that convert chemical energy into electrical energy and water electrolysis devices that electrolyze water to generate oxygen gas and hydrogen gas.

[0003] An electrochemical reactor typically includes a reaction section for generating electrical energy through a chemical reaction or for consuming electrical energy to generate a chemical reaction. In electrochemical reaction devices, the reaction section may be made of a porous material that is an aggregate of particles, and the porous material may be impregnated with a fluid such as a gas or liquid in which the electrochemical reaction takes place, and a large contact area may be provided between the fluid and the porous material. Furthermore, the porous material that constitutes the reaction section of the electrochemical reaction device may be partially composed of catalyst particles that can be used in the electrochemical reaction.

[0004] The electrochemical reaction device further includes an electric current supply section that serves as a path for extracting the electrical energy generated in the reaction section to the outside or for supplying the electrical energy consumed in the reaction section. The current-carrying parts are usually paired with an anode side (positive electrode side) and a cathode side (negative electrode side).

[0005] As an electrochemical reaction device as described above, for example, one having a structure as shown in FIG. 4 of Patent Document 1 listed below is known. That is, FIG. 4 of Patent Document 1 below shows a configuration in which a reaction section is formed by laminating porous layers composed of particles such as carbon black (reference number 11), PTFE (reference number 12), and Pt (catalyst: reference number 21) on both sides of a solid polymer membrane (reference number 3) made of Nafion (registered trademark), and the reaction section is sandwiched between a pair of electrode substrates (reference numbers 41 and 42). Furthermore, Patent Document 1 describes that the electrode substrates (reference numerals 41 and 42), which are current-carrying bodies that exchange electricity with the reaction section, are made of carbon fiber. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3049267 Summary of the Invention [Problem to be solved by the invention]

[0007] BACKGROUND ART There is a demand for devices in which electrochemical reactions occur, such as electrochemical reaction devices, to be lightweight. Although various efforts have been made to reduce the weight of electrochemical reaction devices, there is still room for improvement. Therefore, an object of the present invention is to reduce the weight of an apparatus in which an electrochemical reaction occurs, such as an electrochemical reaction device. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the inventor discovered that while conventional conductors are made of metal or carbon materials, the weight of the conductor can be reduced by using a conductive polymer with electronic conductivity instead, which led to the completion of the present invention.

[0009] In order to solve the above problems, the present invention provides: The electrochemical reaction device includes a reaction section where an electrochemical reaction takes place and a current supply section where power is supplied to the reaction section or power is received from the reaction section. 、 An electrochemical reaction device including the sheet-shaped reaction unit having a catalyst layer containing a reaction catalyst used in the electrochemical reaction, The reaction section is configured so that a fluid used in the electrochemical reaction comes into contact with a surface of the reaction section, the current-carrying unit has a current-carrying body that is in contact with the reaction unit, the surface of the reaction section is a contact surface that is in contact with the current-carrying body, The electrochemical reaction device is provided in which the current-carrying body is a porous body made of a foam and is made of a polymer composition containing a conductive polymer, the polymer itself having electronic conductivity.

[0010] In order to solve the above problems, the present invention provides: A porous body made of a foam constituted by a polymer composition containing a conductive polymer, the polymer itself having electronic conductivity, Provided is an electric conductor that has a catalyst layer containing a reaction catalyst used in an electrochemical reaction, and is used by being brought into contact with the surface of a sheet-like reaction section having a surface that comes into contact with a fluid used in the electrochemical reaction, to supply electricity to the reaction section or receive electricity from the reaction section. [Effects of the Invention]

[0011] According to the present invention, it is possible to reduce the weight of devices in which electrochemical reactions occur, such as electrochemical reaction devices. [Brief explanation of the drawings]

[0012] [Figure 1] Schematic diagram showing the configuration of the hydrogen and oxygen generation device. [Figure 2] FIG. 1 is a schematic front view of a water electrolysis device (electrochemical reaction device). [Figure 3] FIG. 1 is a schematic plan view of a water electrolysis device (electrochemical reaction device). [Figure 4] 4 is a schematic cross-sectional view of a water electrolysis device (electrochemical reaction device) (a cross-sectional view taken along line IV-IV in FIG. 3). [Figure 5] FIG. 1 is a schematic diagram showing the configuration of a water electrolysis unit. [Figure 6]FIG. 2 is a schematic perspective view showing an example of a current-carrying body. [Figure 7] FIG. 10 is a schematic perspective view showing another example of a current conductor. [Figure 8] FIG. 1 is a schematic diagram showing the configuration of a cell unit in a fuel cell. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, a water electrolysis device that electrolyzes water as an electrochemical reaction to generate hydrogen gas and oxygen gas will be specifically described as an example of the electrochemical reaction device of the present invention. That is, in the following, an embodiment of the present invention will be described using a hydrogen / oxygen generation device as an example of a device equipped with a reaction section where an electrochemical reaction takes place.

[0014] As shown in FIG. 1, the hydrogen / oxygen generation device 100 of this embodiment includes a gas generation device 1 that electrolyzes pure water to generate hydrogen gas on the cathode side and oxygen gas on the anode side as product gases from the electrolysis, and is configured so that the electrolysis can be carried out while the anode side of the cathode side and the anode side serves as a water circulation electrode through which the pure water is circulated.

[0015] The gas generator 1 is composed of a water electrolysis device 1a including a plurality of water electrolysis cell units UT, each of which has an anode chamber and a cathode chamber adjacent to each other with a solid polymer electrolyte membrane interposed therebetween, and a power supply device 1b for applying a direct current to the water electrolysis device 1a.

[0016] The hydrogen / oxygen generation apparatus 100 of this embodiment includes a pure water storage tank 2 for storing the pure water to be supplied to the anode side (anode chamber) of the water electrolysis apparatus 1a, a water supply path 3 for supplying the pure water from the pure water storage tank 2 to the anode side of the water electrolysis apparatus 1a, and a return path 4 for returning water discharged together with oxygen gas from the anode side of the water electrolysis apparatus 1a to the pure water storage tank 2. That is, in the hydrogen / oxygen generation apparatus 100, a circulation path is formed through which pure water circulates between the water electrolysis apparatus 1a and the pure water storage tank 2 via the water supply path 3 and the return path 4. In this embodiment, pure water in an amount greater than that which is electrolyzed in the water electrolysis apparatus 1a is supplied to the anode side of the water electrolysis apparatus 1a, whereby excess water and oxygen gas are discharged from the anode chamber as a gas-liquid mixed fluid, and the gas-liquid mixed fluid is separated into gas and liquid in the pure water storage tank 2.

[0017] The hydrogen / oxygen generation apparatus 100 of this embodiment includes the pure water storage tank 2 that functions as a gas-liquid separator on the anode side (anode-side gas-liquid separator), and further includes a gas-liquid separator (cathode-side gas-liquid separator 5) for removing moisture from wet hydrogen gas generated from the cathode side of the water electrolysis apparatus 1a.

[0018] The hydrogen / oxygen generation apparatus 100 of this embodiment further includes a pure water supply device 6 for supplying pure water to the pure water storage tank 2, a drainage path 7 for discharging water removed from the wet hydrogen gas in the cathode-side gas-liquid separator 5 to the outside of the system, and a supply path 8 for supplying pure water from a supply water tank 61 of the pure water supply device 6 to the pure water storage tank 2. The hydrogen / oxygen generation apparatus 100 of this embodiment is equipped with an oxygen gas discharge path 9a for discharging the oxygen gas separated in the anode-side gas-liquid separator (pure water storage tank 2) to the outside of the system, and a hydrogen gas discharge path 9b for discharging the hydrogen gas separated in the cathode-side gas-liquid separator 5 from the cathode-side gas-liquid separator 5 so that the hydrogen gas can be further subjected to drying treatment or the like.

[0019] As shown in Figures 2 to 5, the water electrolysis apparatus 1a of this embodiment includes a cell stack 10 configured by stacking a plurality of the water electrolysis cell units UT, a first end plate 20 stacked, via an electrical insulating sheet S, on a water electrolysis cell unit UT arranged at one edge in the stacking direction of the cell stack 10 (the vertical direction in Figure 4), and a second end plate 30 stacked, via an electrical insulating sheet S, on a water electrolysis cell unit UT arranged at the other edge in the stacking direction opposite the first end plate 20. That is, in the water electrolysis apparatus 1a of this embodiment, the cell stack 10 is sandwiched between two end plates with the electrical insulating sheet S interposed therebetween. The water electrolysis device 1a of this embodiment also includes a reaction unit 11 in which oxygen gas and hydrogen gas are generated by an electrochemical reaction (electrolysis of water), and a power supply unit 12 that supplies power to the reaction unit 11 so as to supply power provided by the power supply device 1b to the reaction unit 11.

[0020] The water electrolysis apparatus 1a of this embodiment includes a water inlet 40 for supplying pure water to each water electrolysis cell unit UT, an oxygen gas outlet 50 for discharging a gas-liquid mixture fluid containing oxygen gas produced by electrolysis in each water electrolysis cell unit UT, and a hydrogen gas outlet 60 for discharging hydrogen gas produced by electrolysis in each water electrolysis cell unit UT.

[0021] In the water electrolysis device 1a of this embodiment, an oxygen gas discharge path 15 and a hydrogen gas discharge path 16 are formed in the cell stack 10, extending in the stacking direction of the water electrolysis cell units UT and penetrating through multiple water electrolysis cell units UT. In the water electrolysis device 1a of this embodiment, the oxygen gas discharge path 15 communicates with the oxygen gas discharge port 50 and the anode chamber A of the water electrolysis cell unit UT, and the hydrogen gas discharge path 16 communicates with the hydrogen gas discharge port 60 and the cathode chamber C. That is, the oxygen gas discharge path 15 constitutes a flow path for a gas-liquid mixture fluid from the anode chamber A to the oxygen gas discharge port 50, and the hydrogen gas discharge path constitutes a gas flow path from the cathode chamber C to the hydrogen gas discharge port 60.

[0022] The water electrolysis apparatus 1a of this embodiment is provided with a pure water supply path 14 that communicates with the water supply port 40, similar to the oxygen gas discharge path 15 and the hydrogen gas discharge path 16, and extends through the multiple water electrolysis cell units UT. The pure water supply path 14 communicates with each anode chamber A but does not communicate with the cathode chamber C. That is, the water electrolysis apparatus 1a of this embodiment is configured so that pure water supplied from the water supply port 40 is distributed to each anode chamber A through the pure water supply path 14, the distributed water passes through each anode chamber A, and is collected in the oxygen gas discharge path 15, and then flows out to the oxygen gas discharge port 50.

[0023] The reaction section 11 of this embodiment is formed in a sheet shape and is composed of a solid electrolyte membrane 111 and catalyst layers 112 laminated on both sides of the solid electrolyte membrane 111 . The conductive section 12 in this embodiment is formed in a sheet shape similar to the reaction section 11, and is composed of an electrode plate 121 arranged opposite the reaction section 11, and a sheet-shaped conductive body 122 arranged between the electrode plate 121 and the catalyst layer 112. The current conductor 122 has one surface in contact with the catalyst layer 112 and the other surface in contact with the electrode plate 121, and is electrically connected to both the catalyst layer 112 and the electrode plate 121. The current-carrying section 12 constitutes at least a part of the current-carrying path extending from the reaction section 11 to the outside of the water electrolysis device 1a, and the current-carrying body 122 constitutes the part of the current-carrying path that is closest to the reaction section 11. In other words, in the reaction section 11, the surface of the catalyst layer 112 is located closest to the current conductor 12 side, and the surface of the catalyst layer 112 serves as a contact surface 11s with the current conductor 122.

[0024] In this embodiment, the pure water supply path 14 penetrates the reaction section 11 in the thickness direction at one end edge of the reaction section 11, and the oxygen gas exhaust path 15 and the hydrogen gas exhaust path 16 penetrate the reaction section 11 in the thickness direction at the other end edge opposite to the one end edge through which the pure water supply path penetrates. That is, in the water electrolysis cell unit UT of this embodiment, as shown in FIG. 5, the space between the anode side electrode plate 121 (anode plate 121a) and the solid electrolyte membrane 111 forms an anode chamber A for generating oxygen gas, and the space between the cathode side electrode plate 121 (cathode plate 121c) and the solid electrolyte membrane 111 forms a cathode chamber C for generating hydrogen gas.

[0025] The water electrolysis cell unit UT of this embodiment is configured so that pure water W is supplied to one edge of the reaction section 11 (one edge of the anode chamber A), and oxygen gas O2 is generated by electrolysis as the supplied pure water W flows through the catalyst layer 112 (anode-side catalyst layer 112a) to the other edge, and the pure water W and oxygen gas O2 are discharged from the anode chamber A to the oxygen gas discharge path 15, and hydrogen ions migrate via the solid electrolyte membrane 111 to the cathode chamber C (cathode-side catalyst layer 112c) on the opposite side from the anode chamber A through which the pure water W flows, and the hydrogen ions receive electrons from the cathode plate 121c to generate hydrogen gas H2, which is then discharged from the cathode chamber C to the hydrogen gas discharge path 16. The water electrolysis device 1a of this embodiment is configured so that oxygen gas O2 and hydrogen gas H2 generated in each anode chamber A and each cathode chamber C, respectively, pass through the oxygen gas discharge path 15 and the hydrogen gas discharge path 16 and are discharged from the oxygen gas discharge port 50 and the hydrogen gas discharge port 60, respectively.

[0026] The solid electrolyte membrane 111 in the water electrolysis cell unit UT can be made of, for example, a cation exchange resin having ion conductivity, such as a perfluorosulfonic acid polymer. The catalyst layer 112 may be made of catalytic metal particles or the like. The metal includes platinum group elements such as platinum and iridium. The catalyst layer 112 may contain inorganic filler or particles of ion-conductive resin in addition to metal particles. In the catalyst layer 112, metal-coated particles obtained by coating inorganic fillers or resin particles with the metal may be used in place of some or all of the metal particles.

[0027] The electrode plate 121 may be a metal plate, such as a pure titanium plate or a titanium alloy plate. Furthermore, the electrode plate 121 of this embodiment may be made of a polymer composition containing a conductive polymer, similar to the current conductor 122 described later. In this case, the electrode plate 121 and the current conductor 122 do not need to be separate bodies, and may be integrated. That is, the current-carrying portion 12 may be configured solely by the current-carrying body 122 that also has the function of the electrode plate 121 .

[0028] The current conductor 122 in this embodiment is made of a polymer composition containing a conductive polymer having electronic conductivity. The polymer composition preferably has an electrical conductivity of 0.1 S / cm or more, and the conductive polymer contained in the polymer composition preferably has such an electrical conductivity. The electrical conductivity of the polymer composition or the conductive polymer is more preferably 1 S / cm or more, and even more preferably 10 S / cm or more. The base polymer of the polymer composition may be a π-conjugated polymer or a polymer obtained by doping a π-conjugated polymer with a polyanion. The electrical conductivity of the polymer composition or the conductive polymer can be measured by the method described in JIS K7194.

[0029] Examples of the π-conjugated polymer include homopolymers and copolymers containing, as repeating units, monocyclic aromatic compounds such as pyrroles, thiophenes, thiophene vinylenes, selenophenes, tellurophenes, phenylenes, phenylene vinylenes, and anilines; polycyclic aromatic compounds such as acenes; and acetylenes. The conductive polymer may have not only electronic conductivity but also ionic conductivity. That is, the conductive polymer may have ionic conductivity or may not have ionic conductivity. Examples of the conductive polymer include polypyrrole, polyaniline, and polyalkylthiophene.

[0030] When the electrical conductivity exhibited by the electronic conduction of the conductive polymer is "Ec1 (S / cm)" and the electrical conductivity exhibited by the ionic conduction of the conductive polymer is "Ec2 (S / cm)," the electrical conductivity exhibited by the ionic conduction (Ec2) is preferably less than 0.1 S / cm. The electrical conductivity exhibited by the ionic conduction of the conductive polymer (Ec2) may be ½ or less, ⅕ or less, or 1 / 10 or less of the electrical conductivity exhibited by the electronic conduction (Ec1).

[0031] Electrical conductivity due to electronic conduction and electrical conductivity due to ionic conduction can be determined according to the method described in Electrochemistry, published by the Electrochemical Society. More specifically, the "ion blocking method" described in "Tutorial Electrochemical Measurement Methods, Series 9: Fundamentals and Measurement Methods of Solid Electrolytes 1 - Characterization of Solid Electrolytes" (by Hiroshi Amezawa) in Electrochemistry, Vol. 85 (2017), No. 3, and the "electron blocking method" described in "Tutorial Electrochemical Measurement Methods, Series 9: Fundamentals and Measurement Methods of Solid Electrolytes 2 - Oxide-Ion Conductors" (by Hiroshi Amezawa) in Electrochemistry, Vol. 85 (2017), No. 4, can be used to determine electrical conductivity due to electronic conduction and electrical conductivity due to ionic conduction, respectively.

[0032] In the π-conjugated polymer, some of the repeating units may be substituted with a substituent such as an alkyl group, a carboxy group, a sulfo group, an alkoxy group, a hydroxy group, a cyano group, or a halogen atom. Examples of the repeating unit include one or more types selected from pyrrole, thiophene, N-methylpyrrole, 3-methylthiophene, 3-methoxythiophene, 3,4-ethylenedioxythiophene, and the like. Among these, the π-conjugated polymer is preferably a homopolymer of 3,4-ethylenedioxythiophene, and more preferably poly(3,4-ethylenedioxythiophene).

[0033] Examples of the polyanion include homopolymers and copolymers containing, as repeating units, styrene sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, acryl sulfonic acid, methacryl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, isoprene sulfonic acid, sulfoethyl methacrylate, 4-sulfobutyl methacrylate, methacryloxybenzene sulfonic acid, vinyl carboxylic acid, styrene carboxylic acid, allyl carboxylic acid, acryl carboxylic acid, methacryl carboxylic acid, 2-acrylamido-2-methylpropane carboxylic acid, isoprene carboxylic acid, acrylic acid, sulfonated phenylacetylene, or the like. In addition, the repeating unit of the polyanion may form a salt with a sodium ion or the like.

[0034] The polyanion is preferably any one of polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyethyl acrylate sulfonic acid, polymethacrylic carboxylic acid, and the like, and more preferably polystyrene sulfonic acid.

[0035] The conductive polymer is preferably poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid) (PEDOT / PSS), and more preferably poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid) (PEDOT / PSS).

[0036] The water electrolysis apparatus 1a of this embodiment can be made lighter in weight because the current conductor 122 is made of a polymer composition. In order to make such effects more pronounced, it is preferable that the polymer composition does not contain a substance with a high specific gravity, such as an inorganic filler. The content of inorganic matter in the polymer composition constituting the current conductor 122 is preferably 80% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less. The content of inorganic substances in the polymer composition is particularly preferably 20% by mass or less, and particularly preferably 10% by mass or less.

[0037] In order to make the above-mentioned effects more pronounced, the current conductor 122 may be a foam (polymer foam) made of a polymer composition. The conductive body 122 is made of a foam material, and therefore exhibits excellent shock-absorbing properties. In order to ensure reliable electrical connection between the current conductor 122 and the catalyst layer 112, it is preferable that the current conductor 122 be easily deformable and exhibit excellent conformability to the contact surface 11s (surface of the catalyst layer 112). The current conductor 122 is preferably placed in the water electrolysis apparatus 1 a in a state where it is pressurized toward the catalyst layer 112 to a certain degree. On the other hand, if excessive pressure is applied, the solid electrolyte membrane 111 may be damaged. If the conductive body 122 is a foam, a reliable electrical connection can be made with the catalyst layer 112 without applying excessive pressure.

[0038] When the conductive body 122 is a foam, it is preferable that the open cell ratio is high in order to exhibit excellent cushioning properties. The foam preferably has an open cell ratio of 50% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more, as determined in accordance with JIS K7138:2006 "Rigid foamed plastics - Determination of open cell ratio and closed cell ratio."

[0039] A high open cell ratio is also advantageous in that the current conductor 122 exhibits excellent air and water permeability. When the conductive body 122 is a foam having open cells on the surface and having air permeability (water permeability) in the thickness direction due to the continuous cells including the cells, if the opening diameter on the surface is a certain size or larger, oxygen gas and hydrogen gas generated in the reaction section 11 can easily enter the cells. In order to prevent gas accumulation in the conductive body 122, the average diameter of the bubbles opening on the surface (the circle-equivalent diameter (diameter) calculated from the opening area) is preferably 1 mm or less, and more preferably 0.8 mm or less. On the other hand, if the diameter is larger, oxygen gas and hydrogen gas will be able to enter easily but will also be able to escape easily, making it more difficult for the gas to be captured. In order to prevent gas accumulation in the conductive body 122, the average diameter of the bubbles opening on the surface (the circle-equivalent diameter (diameter) calculated from the opening area) is preferably 2 mm or more, and more preferably 2.5 mm or more.

[0040] In order to make the electrical connection between the conductor 122 and the contact surface 11s more reliable while reducing the weight of the conductor 122, it is preferable that the conductor 122 has a base plate portion 1221 arranged opposite the contact surface 11s, and a protrusion portion 1222 protruding from the base plate portion 1221 toward the contact surface 11s, and that the tip of the protrusion portion 1222 is abutted against the contact surface 11s. In this embodiment, the tip of the protrusion can be easily deformed, and the contact surface 11s (catalyst layer 112) and the current conductor 122 can be reliably contacted with each other.

[0041] In order to improve the ability to follow the contact surface 11s, it is preferable that the protruding portion 1222 protruding from the base plate portion 1221 is provided with the brush-shaped conductive body 122 composed of a plurality of hair-like bodies, as shown in Figure 6. Furthermore, in the conductive body 122 in which the protrusion 1222 is composed of a plurality of linear protrusions extending along the planar direction of the contact surface 11s as shown in Figure 7, the pure water W can be guided in the extension direction of the linear protrusions. The linear protrusions extend from the pure water supply path 14, which is the supply point of the pure water W, toward the oxygen gas discharge path 15, which is the discharge point of the pure water W, and if they have multiple linear protrusions parallel to each other, the flow of the pure water W in the anode chamber A can be made smooth. Furthermore, if the anode has multiple linear protrusions extending in a direction inclined from the pure water supply path 14 toward the oxygen gas discharge path 15 (for example, at an inclination angle of approximately 15° to 60°) and parallel to each other, the retention time of the pure water W in the anode chamber A can be increased, and the time for which the pure water is electrolyzed can be prolonged. The protrusions 1222 may be a mixture of linear protrusions extending in the direction of flow of the pure water W and linear protrusions extending in a direction inclined relative to the direction of flow of the pure water W. Moreover, the capillaries may also be inclined in the direction of flow of the pure water W rather than protruding perpendicularly from the base plate portion 1221 . That is, the capillaries may be inclined so as to move away from the pure water supply point (pure water supply path 14) as they approach the reaction section 11.

[0042] By making the pure water W flowing from the pure water supply path 14 to the oxygen gas discharge path 15 pass through the thickness direction of the conductor 122 rather than only through the interface between the conductor 122 and the catalyst layer 112, it is possible to prevent gas accumulation in the conductor 12. In order to achieve such an effect, the current conductor 122 may be made of a porous material such as the foam mentioned above.

[0043] Examples of methods for forming a foam from the polymer composition include a method in which a polymer composition containing a physical foaming agent such as a hydrocarbon or an inorganic gas or a chemical foaming agent such as ADCA, OBSH, or DPT is prepared, a primary molded article in an unfoamed state is produced from the polymer composition, and then the primary molded article is heated to foam. The foamed conductive member may be produced by heating the polymer composition to a molten state and foaming it during extrusion molding or injection molding. This type of molding method tends to produce a molded product with a polymer film formed on the surface. Therefore, in order to achieve excellent water permeability and water retention, for example, a secondary process of removing the skin after molding may be carried out to obtain a foam in which the cut surfaces of the bubbles are exposed on the surface.

[0044] When forming a conductive body 122 having an uneven surface, it is possible to use a method in which a molded product that is slightly larger than the conductive body is produced, and then recesses are formed by carving into the molded product, or convex portions are formed by removing some parts and removing the rest. The molding can be cut or partially removed using a blade or a laser. Alternatively, a first member that will become the convex portion and a second member that has a flat surface larger than the first member may be fabricated separately, and one or more first members may be attached to the flat surface of the second member to form an electric conductor 122 having an uneven surface. The brush-like current conductor 122 as shown in FIG. 6 can be produced by implanting hair-like bodies, for example.

[0045] The conductive body 122 having an uneven surface can be produced without performing secondary processing such as digging or attaching a separate component, and may be produced using a molding die having a molding surface that is the inverse shape of the uneven surface.

[0046] When the conductor 122 is made of a porous material, the conductor 122 may be made of a fiber structure or the like other than a foam. When the current conductor 122 is made of a fiber structure, the fiber structure may be a woven fabric woven by plain weave, twill weave, or the like.

[0047] The fiber structure may be produced in the same manner as a nonwoven fabric. In this case, the fiber structure can be produced by subjecting a web of accumulated fibers to a treatment for bonding the fibers together. The web may be produced by a dry process such as a carding process or an airlaid process, which are used to produce dry-laid nonwoven fabrics. The web may be made by a wet method in which a slurry of fibers dispersed in a liquid is filtered through a screen. The fibers constituting the web can be bonded together by a method such as chemical bonding, thermal bonding, spunlace, needle punching, or stitch bonding. The fibrous structure may be made by a process that simultaneously forms a web and bonds the fibers together, such as a spunbonding process or a meltblowing process.

[0048] The fibrous structure may be made in a similar manner to perforated sheets such as those known by trade names such as "Warif". In this case, the conductive body 122 may be formed by forming a large number of short slits across the entire surface of a single polymer sheet, with the slits aligned in the longitudinal direction, and stretching the polymer sheet in a direction perpendicular to the longitudinal direction of the slits, or by stacking such sheets so that the slits are formed in alternating vertical and horizontal directions.

[0049] When the fiber structure is made into a thin film thinner than a typical nonwoven fabric, the conductive body 122 can be produced by forming a coating film by spraying a slurry containing the fibers onto a separator, drying the coating film, and then peeling it off from the separator.

[0050] In this embodiment, the current conductor 122 may have different shapes and materials on the anode side and the cathode side. If a metal current-carrying body is used as in conventional water electrolysis devices, not only is it difficult to reduce the weight of the device, but problems due to oxidation can occur on the anode side. Also, hydrogen embrittlement can be a problem on the cathode side. To prevent this, it becomes necessary to form the current conductor from a special metal. In the water electrolysis apparatus 1a of this embodiment, the current conductor 122 is made of a polymer composition, which can also prevent problems such as oxidative degradation and hydrogen embrittlement. In particular, there is a risk that the quality of water may be reduced due to the generation of ions from the metal on the anode side, but this embodiment can also suppress such a risk.

[0051] In this embodiment, for the reasons described above, an example is shown in which the electrochemical reaction is the electrolysis of water, the current-carrying body is used on at least the anode side of the anode side and the cathode side, and is disposed in a position in contact with the water and oxygen gas generated by the electrolysis, but the present invention is not limited to the above example. The current conductor 122 made of a polymer composition may be provided, for example, only on the cathode side.

[0052] In this embodiment, a water electrolysis device is exemplified as an electrochemical reaction device provided with the above-described current conductor, but the current conductor can also be used in electrochemical reaction devices other than a water electrolysis device. For example, as shown in FIG. 8, the current conductor can also be used in a cell unit Ux of a fuel cell. The cell unit Ux illustrated in FIG. 8 includes a fuel electrode PF and an air electrode (oxygen electrode PO) between a pair of separators SP. The pair of separators SP are each in the form of a sheet and are arranged in the cell unit Ux so as to face each other at a distance. The pair of separators SP are separated by a membrane / electrode assembly (MEA) including a solid electrolyte membrane 111x so as to form two spaces, and the space between the first separator SP1 of the pair of separators SP and the solid electrolyte membrane 111x is the fuel electrode PF through which a fluid (fuel) that serves as a supply source of hydrogen H2 flows, and the space between the second separator SP2 and the solid electrolyte membrane 111x is the oxygen electrode PO through which a fluid (air) that serves as a supply source of oxygen O2 flows. The cell unit Ux is configured to react hydrogen and oxygen in the reaction section 11x to generate water Wx and electricity E through the reaction.

[0053] The membrane electrode assembly (MEA) is composed of a membrane-like reaction section 11x having the solid electrolyte membrane 111x and catalyst layers 112x laminated on both sides of the solid electrolyte membrane 111x, and electrodes (conductors 122x) laminated on the catalyst layers 112x. The current conductor 122x may be made of the porous material described above so as to constitute a transmission path for electricity E between the reaction section 11x and the outside and also function as a gas diffusion layer. The fuel cell in this embodiment may be of a type that uses hydrogen or hydrocarbon as the negative electrode active material, or may be of a type called a metal-air battery that uses a metal as the negative electrode active material.

[0054] The electrochemical reaction device of this embodiment may be other than a water electrolysis device or a fuel cell, and may be, for example, a secondary battery. The electrochemical reaction device in this embodiment is not limited to this example, and can be used in various modes. That is, the electrochemical reaction device and current-carrying body of the present invention are not limited to the above examples. [Explanation of symbols]

[0055] 1: gas generator, 1a: water electrolysis device, 10: Cell stack, 11: reaction section, 111: solid electrolyte membrane, 112: catalyst layer, 12: Current carrying part, 121: Electrode plate, 122: Current carrying body, 14: Pure water supply path, 15: Oxygen gas exhaust route, 16: Hydrogen gas emission route, 20: End plate 30: End plate 40: Pure water supply port 50: Oxygen gas outlet 60: Hydrogen gas outlet 100: Hydrogen and oxygen generator A:Anode chamber C: Cathode chamber UT: Water electrolysis cell unit

Claims

1. The electrochemical reaction device includes a reaction section where an electrochemical reaction takes place and a current supply section that supplies power to the reaction section or receives power from the reaction section, An electrochemical reaction device including the sheet-shaped reaction unit having a catalyst layer containing a reaction catalyst used in the electrochemical reaction, The reaction section is configured so that a fluid used in the electrochemical reaction comes into contact with a surface of the reaction section, the current-carrying unit has a current-carrying body that is in contact with the reaction unit, the surface of the reaction section is a contact surface that is in contact with the current-carrying body, The electrochemical reaction device is such that the conductive body is a porous body made of a foam and is made of a polymer composition containing a conductive polymer, the polymer itself having electronic conductivity.

2. a base plate portion disposed to face the contact surface; a protrusion protruding from the base plate portion toward the contact surface, 2. The electrochemical reaction device according to claim 1, wherein the current-carrying body has a tip of the protrusion abutting against the abutment surface.

3. 3. The electrochemical reaction device according to claim 2, wherein the protrusions are brush-shaped current-carrying members each made up of a plurality of hair-like members.

4. 3. The electrochemical reaction device according to claim 2, wherein the protrusion is formed of a linear projection extending along the planar direction of the contact surface.

5. 5. The electrochemical reaction device according to claim 1, wherein the conductive polymer is poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT / PSS).

6. A porous body made of a foam constituted by a polymer composition containing a conductive polymer, the polymer itself having electronic conductivity, An electric conductor having a catalyst layer containing a reaction catalyst used in an electrochemical reaction, the electric conductor being in contact with the surface of a sheet-like reaction section having a surface that comes into contact with a fluid used in the electrochemical reaction, for supplying electricity to the reaction section or receiving electricity from the reaction section.

7. A plate-shaped base plate portion; 7. The current conductor according to claim 6, further comprising a protruding portion protruding from the surface of the base plate portion, the tip of the protruding portion being brought into contact with the reaction portion when used.

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