JP2006216403A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell recovering water exhausted from an electrode installed on a hollow outer surface of an electrolyte membrane, and effectively utilizing the recovered water in the wet state control on the inside of the fuel cell and in addition, in the other application if necessary. <P>SOLUTION: In the fuel cell equipped with a cell module having a hollow electrolyte membrane and a pair of electrodes installed on the inner surface and the outer surface of the hollow electrolyte membrane, the cell module has the electrode producing water of the pair of electrodes on the outer surface side of the hollow electrolyte membrane and a reservoir for storing water exhausted from the electrode installed on the outer surface side of the hollow electrolyte membrane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell including a cell module having a hollow electrolyte membrane.

  A fuel cell directly converts chemical energy into electrical energy by supplying fuel and an oxidant to two electrically connected electrodes and causing the fuel to be oxidized electrochemically. Unlike thermal power generation, it is not subject to the Carnot cycle, so it exhibits high energy conversion efficiency. Among them, the solid polymer electrolyte fuel cell is a fuel cell that uses a solid polymer electrolyte membrane as an electrolyte, and has advantages such as easy miniaturization and operation at a low temperature. It is attracting attention as a power source for mobile objects.

In the solid polymer electrolyte fuel cell, when hydrogen is used as the fuel, the reaction of the formula (1) proceeds at the anode.
H ₂ → 2H ⁺ + 2e ⁻ (1)
The electrons generated by the equation (1) reach the cathode after working with an external load via an external circuit. Then, the proton generated in the formula (1) moves by electroosmosis from the anode side to the cathode side in the solid polymer electrolyte membrane in a state of being hydrated with water.

Further, when oxygen is used as the oxidizing agent, the reaction of the formula (2) proceeds at the cathode.
4H ⁺ + O ₂ + 4e ⁻ → 2H ₂ O (2)
The water produced at the cathode mainly passes through the gas diffusion layer and is discharged to the outside.
As described above, the fuel cell is a clean power generation device having no emission other than water.

  Conventionally, as a solid polymer electrolyte fuel cell, a catalyst layer serving as an anode and a cathode is provided on one surface of a planar solid polymer electrolyte membrane, and the resulting planar membrane / electrode assembly is obtained. There has been developed a fuel cell stack obtained by laminating a plurality of flat single cells prepared by further providing gas diffusion layers on both sides and finally sandwiching them with a planar separator.

In order to improve the output density of the solid polymer electrolyte fuel cell, a proton conductive polymer membrane having a very thin film thickness is used as the solid polymer electrolyte membrane. The film thickness of 100 μm or less is the mainstream, and even if a thinner electrolyte membrane is used to further improve the power density, the thickness of the single cell cannot be dramatically reduced from the present one. Similarly, the catalyst layer, the gas diffusion layer, the separator, and the like have been made thinner, but there is a limit to improving the output density per unit volume even by making all these members thinner.
In addition, a sheet-like carbon material having excellent corrosivity is usually used for the separator. This carbon material itself is also expensive. However, in order to distribute the fuel gas and the oxidant gas almost uniformly over the entire surface of the planar membrane / electrode assembly, a gas is usually provided on the surface of the separator. Since the groove to be the flow path is finely processed, the processing makes the separator very expensive, which increases the manufacturing cost of the fuel cell.

  In addition to the above problems, it is a technology to reliably seal the periphery of a plurality of unit cells stacked so that fuel gas and oxidant gas do not leak from the gas flow path in the flat unit cell. There are many problems such as difficulty in power generation and reduction in power generation efficiency due to deflection or deformation of the planar membrane / electrode assembly.

In recent years, a solid polymer electrolyte fuel cell has been developed in which a cell module having electrodes on the inner surface side and outer surface side of a hollow electrolyte membrane is used as a basic power generation unit. (For example, see Patent Documents 1 to 4).
Usually, in a fuel cell having such a hollow cell module, it is not necessary to use a member corresponding to a separator used in a flat type. Since different types of gas are supplied to the inner surface and the outer surface for power generation, it is not necessary to form a gas flow path. Therefore, the manufacturing cost is expected to be reduced. Further, since the cell module has a three-dimensional shape, the specific surface area with respect to the volume can be increased as compared with the flat single cell, and the power generation output density per volume can be expected to be improved.

A plurality of cell modules having a hollow shape as described above are usually arranged, and the anode terminal and cathode terminal of each cell module are bundled and connected in parallel or in series to form a cell group supported by a support plate or the like. Further, the cell group is connected in series or in parallel with other cell groups to form a cell aggregate.
The cell group and the cell assembly are usually housed in an outer container, and the hollow portion of the cell module is used as a supply source of a reactive gas (oxidant or fuel) supplied to the electrode provided on the hollow inner surface of the electrolyte membrane. The internal space of the outer container is connected to the supply source of the reactive gas supplied to the electrode provided on the hollow outer surface of the electrolyte membrane, whereby the reactive gas is supplied to each electrode.

  Excess moisture in the cell module, such as water generated as a result of the electrochemical reaction and water vapor supplied to the electrode together with the reaction gas, is removed from the electrodes provided on the inner and outer surfaces of the electrolyte membrane from the cell module hollow part and the outer container. It is discharged into the internal space. At this time, the amount of water discharged from each electrode increases at the electrode that generates the generated water. That is, when the electrode that generates water as a result of the electrochemical reaction is provided on the outer surface side of the electrolyte membrane, a large amount of moisture is discharged into the internal space of the outer container.

  By the way, in a polymer electrolyte fuel cell using a polymer electrolyte membrane, which is one of proton conducting membranes as an electrolyte membrane, protons generated at the anode are hydrated with water and flow inside the polymer electrolyte membrane on the anode side. Therefore, proton conductivity decreases when the water content of the polymer electrolyte membrane is low. Therefore, it is important to keep the moisture content of the polymer electrolyte membrane high and prevent drying. In addition, if the electrodes formed on both surfaces of the polymer electrolyte membrane are dry, the electrolyte membrane cannot be kept in a high wet state, and therefore the electrode needs to be in a proper wet state.

JP-A-9-223507 JP 2002-124273 A JP 2002-158015 A Japanese Patent Laid-Open No. 2002-260685

  The present invention recovers moisture discharged from the electrode provided on the hollow outer surface of the electrolyte membrane, and effectively uses the recovered moisture for wet state management in the fuel cell, and for other uses as necessary. An object of the present invention is to provide a fuel cell that can be used.

The fuel cell of the present invention is a fuel cell comprising a cell module having a hollow electrolyte membrane and a pair of electrodes provided on an inner surface and an outer surface of the hollow electrolyte membrane, the cell module comprising the pair of electrodes. Of these, an electrode for generating generated water is provided on the outer surface side of the hollow electrolyte membrane, and a reservoir for storing water discharged from the electrode provided on the outer surface side of the hollow electrolyte membrane is provided. .
According to the present invention, moisture discharged from the electrode provided on the outer surface side of the hollow electrolyte membrane, mainly generated water during the electrochemical reaction, is stored in the reservoir, moisture management in the cell module and other Can be reused for any purpose.

In order to effectively use the water collected and stored in the reservoir, it is preferable to further include means for reusing the water in the reservoir.
In addition, in order to efficiently collect the water discharged from the electrode provided on the outer surface side of the hollow electrolyte membrane into the reservoir, the reservoir is placed on the lower side in the gravity direction of the cell module in the state of use of the fuel cell. It is preferable that it is provided so that it may be located. By providing the reservoir on the lower side in the direction of gravity, water that naturally falls due to gravity can be collected in the reservoir.
Further, from the viewpoint of simplifying the structure of the fuel cell, the cell module is preferably arranged so that its longitudinal direction is substantially perpendicular to the direction of gravity when the fuel cell is in use.

  The fuel cell of the present invention includes a cell group in which a plurality of the cell modules are arranged, the cell group is accommodated in an outer container, and the outer container is attached to electrodes provided on the inner surface and the outer surface of the hollow electrolyte membrane. In the case of having a structure in which the airtightness with the external space is maintained except for the outlet / inlet of the substance to be supplied, the outer container is caused by the moisture discharged from the electrode provided on the outer surface side of the hollow electrolyte membrane. Since the inside can be maintained in a high humidity state, drying of the electrolyte membrane and the electrode can be suppressed.

  In the fuel cell of the present invention, moisture discharged from the outer surface side of the cell module is collected and stored in a reservoir provided in a place where the battery characteristics such as the power generation performance of the fuel cell are not adversely affected. It can be effectively used for moisture management and other purposes. Therefore, according to the present invention, in a fuel cell including a cell module having a hollow shape, when an electrode for generating generated water is provided on the hollow outer surface side, water discharged from the outer surface electrode is reused. In addition, the battery characteristics of the fuel cell can be improved.

  In particular, in a fuel cell using an electrolyte membrane that requires a good wet state such as a solid polymer electrolyte membrane, when using the water collected and stored in the reservoir to increase the wet state of the cell module, Drying of the electrolyte membrane can be suppressed, and the power generation performance of the fuel cell can be improved.

  The fuel cell of the present invention is a fuel cell comprising a cell module having a hollow electrolyte membrane and a pair of electrodes provided on an inner surface and an outer surface of the hollow electrolyte membrane, the cell module comprising the pair of electrodes. Of these, an electrode for generating generated water is provided on the outer surface side of the hollow electrolyte membrane, and a reservoir for storing water discharged from the electrode provided on the outer surface side of the hollow electrolyte membrane is provided. Is.

  Hereinafter, the fuel cell of the present invention will be described by taking as an example a case where a solid polymer electrolyte membrane which is a kind of proton conducting membrane is used as an electrolyte membrane. Here, a perfluorocarbon sulfonic acid resin membrane is used as the solid polymer electrolyte membrane.

  First, an embodiment of the fuel cell of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an example of a cell module used in the present invention.

  In FIG. 1, a cell module 101 has a tubular electrolyte membrane (perfluorocarbon sulfonic acid resin membrane) 1, and a first electrode (in this case, a cathode) 2 that generates product water is a hollow outer surface of the electrolyte membrane 1. On the side, a second electrode (in this case, an anode) 3 that forms a pair with the first electrode is formed on the hollow inner surface side of the electrolyte membrane 1. Inside the second electrode (anode) 3, a hollow portion (usually a flow path for a fuel gas such as hydrogen gas) 4 into which a reaction gas supplied to the second electrode flows is formed. Current collectors 5 and 6 are connected to the first electrode 2 and the second electrode 3, respectively, and one end of the current collectors 5 and 6 functions as an output terminal.

  FIG. 2 is a cross-sectional perspective view showing an example of an outer container in which a plurality of cell modules are arranged and accommodated. In FIG. 2, the plurality of cell modules 101 are accommodated in the outer casing 7 in a state of being supported and arranged by a support plate (not shown). The plurality of cell modules accommodated in the outer casing 7 constitute a cell group in which the cathode terminals 5 (not shown) and the anode terminals 6 (not shown) are bundled and connected in parallel or in series. The internal space of the outer container 7 communicates with an oxidant gas supply source (not shown), and the hollow portion 4 of the cell module 101 communicates with a fuel gas supply source (not shown). Gas is supplied. The outer container 7 includes an oxidant gas inlet and an oxidant gas outlet through which the oxidant gas flows into the internal space, and a fuel gas inlet and fuel gas through which the fuel gas flows through the hollow portion 4 of the cell module 101. The parts other than the outflow port are blocked from the external space, and airtightness is maintained.

  The exterior container 7 is provided with a reservoir 8 having a space communicating with the internal space of the exterior container 7. The reservoir 8 is located on the lower side in the gravity direction of the space in which the cell module 101 is accommodated in the outer container 7. The reservoir 8 is positioned so as not to adversely affect the supply of reaction gas to the electrode 2 provided on the outer surface side of the tubular electrolyte membrane 1 and the moisture distribution of the electrodes 2 and 3 (particularly the electrode 2). The cell module 101 is provided at a position so as not to be immersed in moisture stored in the reservoir 8.

  The cell group accommodated in the exterior container 7 is normally connected in series or in parallel with the cell group accommodated in another exterior container to form a cell aggregate. Here, the number of cell groups accommodated in one exterior container is not limited to one, a plurality of cell groups may be accommodated, or there may be one exterior container as the whole fuel cell. . In addition, the configuration of the cell module connection form and arrangement form is not particularly limited, and for example, a group of cells in which the cell modules are connected in series may be used. Further, the supply direction of the reaction gas is not limited to the case shown in the figure.

The fuel cell of the present invention is characterized in that the water discharged from the electrode provided on the outer surface side of the tubular electrolyte membrane, that is, the outer surface of the cell module, can be collected and stored in the reservoir. The moisture discharged from the electrode includes moisture supplied to the cell module together with the reaction gas in addition to moisture generated by the electrochemical reaction.
In the fuel cell of the present invention, the water collected in the reservoir can be effectively used to improve the operating environment of the fuel cell and improve the power generation performance, such as humidity adjustment and cooling of the cell module. In addition, the reservoir is provided in a place where the moisture collected in the reservoir does not adversely affect the flow of the reaction gas and the moisture distribution of the electrode and the electrolyte membrane. Therefore, according to the present invention, it is possible to improve the power generation performance of the fuel cell by reusing the water discharged from the electrode.

  In the present invention, the structure of the reservoir, the structure of the position, the material and the like are not particularly limited as long as the water discharged from the electrode provided on the outer surface side of the tubular electrolyte membrane can be collected and stored. What is necessary is just to design suitably in consideration of conditions, such as the arrangement | positioning state of the cell module at the time of fuel cell use, and the structure of an exterior container.

  In order to quickly and surely collect the moisture discharged from the electrode provided on the outer surface side of the cell module into the reservoir, as shown in FIG. It is preferable to be provided on the lower side. Thus, by providing the reservoir on the lower side in the gravitational direction of the cell module, the liquid water discharged from the first electrode provided on the outer surface side of the tubular electrolyte membrane naturally falls by its own weight, and the wall of the outer container It is efficiently collected into the reservoir through the inner surface or the outer surface of the cell module or directly.

  The reservoir has an opening through which water can be guided from the space in which the cell group in the outer container is accommodated, but the shape of the opening is not particularly limited. For example, the opening may be such that the boundary between the space in which the cell group of the outer container is accommodated and the reservoir is opened over the entire surface, or the space and the reservoir in which the cell group of the outer container is accommodated. It may be a hole-shaped opening provided in the wall to be separated. Further, when a wall is provided to separate the reservoir from the space in which the cell group of the outer container is accommodated, the water can be recovered in the reservoir even if the wall is formed of a material having water permeability.

  The opening need not always be open, and may be provided with a valve that prevents the backflow of moisture stored in the reservoir, a gate that can be opened and closed as necessary, and the like. Only one or a plurality of openings can be provided.

  In order to effectively use the water collected and stored in the reservoir, it is preferable to provide means for taking out and reusing the water in the reservoir. Examples of the means for reusing the water in the reservoir include the following.

  If the reservoir opening has a structure that allows the water collected and stored in the reservoir to be volatilized again into the outer container, the electrolyte membrane and the electrode are humidified by the volatilized water. It becomes easy to hold in a wet state. Therefore, in the case of using an electrolyte membrane in which the drying of the membrane such as the solid polymer electrolyte membrane has a great influence on the power generation performance, the power generation performance by drying the electrolyte membrane is provided by providing the opening having the above structure. Can be prevented. The structure of the opening that can volatilize the water in the reservoir into the hollow of the electrolyte membrane is not particularly limited, and may be appropriately designed. For example, in FIG. 2, the water in the evaporated reservoir naturally rises, moves from the opening of the reservoir to the outside of the reservoir, and can be volatilized into the outer container in which the cell group is accommodated.

  The water collected in the reservoir can be evaporated according to the temperature in the battery during operation of the fuel cell. However, when a heating means for heating the water in the reservoir is provided, the evaporation of the water collected in the reservoir is accelerated. In addition, since the drying of the electrolyte membrane can be further suppressed, the power generation performance of the fuel cell can be expected to be further improved. Further, under low temperature conditions, not only is the evaporation of moisture promoted, but also the frozen moisture in the reservoir can be quickly thawed and evaporated at the time of activation, and the electrolyte membrane can be quickly humidified. As such heating means, for example, a heating element such as a heating wire is provided on the outer periphery of the reservoir, and the outer wall of the reservoir is heated to heat the water in the reservoir. In addition, a heating element is provided in the reservoir. The thing which heats the water | moisture content directly is also mentioned.

  In addition, when water stored in the reservoir is once recovered outside the outer container and used for cooling water for cooling the cell module or humidified water for humidifying the reaction gas, for example, the bottom of the reservoir is placed in the reservoir. The structure may be such that the moisture can be induced and collected at a desired location outside the outer container.

  The material forming the reservoir is not particularly limited as long as it does not have water permeability, and may be an elastic material or a rigid material, but from the viewpoint of preventing breakage due to freezing and expansion of moisture stored in the reservoir, It is preferable to use a stretchable material, particularly an elastic material. In the case of using a rigid material, it is preferable to select a material having a strength that does not break for the reasons described above. Moreover, it is preferable that it is a material which has durability. From the viewpoint of strength and durability, examples of the stretchable material include rubber, and examples of the rigid material include plastic, stainless steel, and gold. In addition, the water generated at the electrode (cathode) as a result of the electrochemical reaction itself is pure water, but as a result of mixing with the water that has moved with the protons from the anode side, the water discharged from the electrode is usually Since it shows acidity, it is preferable that it is a material excellent in corrosion resistance. From such a viewpoint, the reservoir material is particularly preferably rubber, stainless steel, or gold, and more preferably rubber having high resilience due to elasticity. Rubber is preferable from the viewpoint of cost because it is an inexpensive material. Specifically, examples of the rubber include, but are not limited to, nitrile rubber, butyl rubber, ethylene propylene rubber, and elastomer. Examples of the plastic include polypropylene (PP), polyethersulfone (PES), nylon, and the like, and examples of the stainless steel include SUS316.

  In the present invention, the outer container only needs to have a structure capable of maintaining the arrangement state of the cell modules to be accommodated, and further a structure capable of protecting the cell modules from mechanical shock as necessary. For example, it may be a frame surrounding the periphery of the cell group, but by keeping the humidity inside the outer container high, the first electrode and the electrolyte membrane, and thus the second electrode provided on the inner surface side of the electrolyte membrane Therefore, it is preferable that a highly airtight state blocked from the external space can be maintained except for the inlet / outlet for supplying the reaction gas to the electrodes 2 and 3. In this way, the highly airtight outer container can maintain its internal space in a high humidity state by the water discharged from the first electrode, and the water discharged from the first electrode in a gaseous state. However, when the humidity in the outer container 7 becomes saturated, it condenses and becomes liquid, so that it can be efficiently collected in the reservoir. Here, the airtightness with the external space is maintained as long as the humidity state in the exterior container can be maintained in a state different from the external space, and it is not necessary to be in a completely sealed state. Good.

  The material forming the outer container is not particularly limited as long as it is a material having a strength capable of maintaining the arrangement state of the cell modules to be accommodated and protecting it from mechanical impact. As described above, since it is preferable to keep the humidity state in the outer container high, it is preferable that the material has no water (droplet, water vapor, etc.) permeability. In the polymer electrolyte fuel cell, the water produced at the cathode itself is pure water, but the water discharged from the electrode is mixed as a result of mixing with water molecules that have moved with the protons from the anode side. Since it usually shows acidity, it is preferably a material having excellent corrosion resistance. Specific examples include plastic, stainless steel, gold, Ti alloy, and stainless steel, gold, and Ti alloy are particularly preferable. Examples of the stainless steel include SUS316, and examples of the Ti alloy include TiN. The exterior container may be formed of a single material or a combination of a plurality of materials.

  The arrangement state of the cell modules in the usage state of the fuel cell is not particularly limited, and the longitudinal direction may be parallel to, inclined, or perpendicular to the direction of gravity. When the longitudinal direction of the cell module is parallel to the direction of gravity, that is, when the cell module is arranged vertically, the outlet and the inlet of the reactive gas (in this case, fuel gas) supplied into the hollow of the cell module Are usually provided on the upper surface side and the lower surface side of the outer container, respectively. At this time, in order to efficiently guide the water discharged from the electrode provided on the outer surface side of the cell module to the reservoir, the reservoir is preferably provided at the lower part in the gravity direction of the outer container 7 as shown in FIG. In this case, in order to prevent the cell module 101 from being immersed in the water in the reservoir 8, the arrangement and structure of the reservoir and the outlet or inlet of the reaction gas may be complicated.

  Therefore, from the viewpoint of simplification of the fuel cell structure, the cell module is preferably arranged so that its longitudinal direction is substantially perpendicular to the direction of gravity when the fuel cell is used as shown in FIG. In this case, since there is no portion such as an outlet or an inlet for the reaction gas on the lower side in the gravity direction of the outer container, the structure is not so complicated even if a reservoir is provided.

  In FIG. 1, an electrolyte membrane having a tubular hollow shape is used as the hollow electrolyte membrane. However, the hollow electrolyte membrane in the present invention is not limited to a tubular shape, and has a hollow portion, and a reaction occurs in the hollow portion. What is necessary is just to be able to supply a reaction component required for an electrochemical reaction to the inner surface side electrode by flowing gas.

  In the present embodiment, a perfluorocarbon sulfonic acid resin membrane, which is one of solid polymer electrolyte membranes, which is a kind of proton conducting membrane, is described as an electrolyte membrane. However, the fuel cell of the present invention is hollow. Since it has a cell module having a shape, it can take a larger electrode area per unit volume than a fuel cell having a flat cell, so it does not have a higher proton conductivity than a perfluorocarbon sulfonic acid resin membrane. Even when an electrolyte membrane is used, a fuel cell having a high output density per unit volume can be obtained. As the solid polymer electrolyte membrane, perfluorocarbon sulfonic acid resin and materials used for the electrolyte membrane of solid polymer fuel cells can be used. For example, fluorine other than perfluorocarbon sulfonic acid resin can be used. One kind of proton exchange groups such as at least sulfonic acid groups, phosphonic acid groups, and phosphoric acid groups, based on hydrocarbons such as polyolefins such as polystyrene ion exchange resins and polystyrene cation exchange membranes having sulfonic acid groups A complex of a basic polymer and a strong acid, which is disclosed in Japanese Patent Application Laid-Open No. 11-503262, etc., in which a basic polymer such as polybenzimidazole, polypyrimidine, and polybenzoxazole is doped with a strong acid And polymer electrolytes such as solid polymer electrolytes.

A solid polymer electrolyte membrane using such an electrolyte should be reinforced with a perfluorocarbon polymer in the form of a fibril, a fabric, a non-fabric, or a porous sheet, or the membrane surface can be coated with an inorganic oxide or metal. It can also be reinforced. In addition, examples of the perfluorocarbon sulfonic acid resin membrane include commercially available products such as Nafion manufactured by DuPont of the United States and Flemion manufactured by Asahi Glass.
In addition, the proton conductive electrolyte membrane is not limited to the solid polymer electrolyte membrane as described above, a porous electrolyte plate impregnated with a phosphoric acid aqueous solution, a proton conductor made of porous glass, Use hydrogelated phosphate glass, organic-inorganic hybrid proton conductive membrane with proton conductive functional groups introduced into the surface and pores of nanoporous glass, inorganic metal fiber reinforced electrolyte polymer, etc. Can do.

  Each electrode provided on the inner surface and the outer surface of the perfluorocarbon sulfonic acid resin film can be formed using an electrode material used in a polymer electrolyte fuel cell. Usually, an electrode configured by laminating a catalyst layer and a gas diffusion layer in order from the electrolyte membrane side is used.

  The catalyst layer contains catalyst particles and may contain a proton conductive material for increasing the utilization efficiency of the catalyst particles. As the proton conductive material, those used as the material of the electrolyte membrane can be used. As the catalyst particles, catalyst particles in which a catalyst component is supported on a conductive material such as a carbon material such as carbonaceous particles or carbonaceous fibers are preferably used. Since the fuel cell of the present invention has a cell module having a hollow shape, the electrode area per unit volume can be made larger than that of a fuel cell having a flat cell. Even when components are used, a fuel cell having a high output density per unit volume can be obtained. The catalyst component is not particularly limited as long as it has a catalytic action for hydrogen oxidation reaction at the anode and oxygen reduction reaction at the cathode. For example, platinum (Pt), ruthenium (Ru), iridium (Ir) , Rhodium (Rh), palladium (Pd), osmium (Os), tungsten (W), lead (Pb), iron (Fe), chromium (Cr), cobalt (Co), nickel (Ni), manganese (Mn) , Vanadium (V), molybdenum (Mo), gallium (Ga), aluminum (Al) and other metals, or alloys thereof. Preferable is platinum and an alloy made of platinum and another metal such as ruthenium.

  As the gas diffusion layer, a conductive material mainly composed of a carbon material such as carbonaceous particles and / or carbonaceous fibers can be used. The sizes of the carbonaceous particles and the carbonaceous fibers may be appropriately selected in consideration of the dispersibility in the solution when the gas diffusion layer is produced, the drainage property of the obtained gas diffusion layer, and the like. The configuration of each electrode provided on the inner and outer surfaces of the electrolyte membrane, the material used for the electrode, and the like may be the same or different. The gas diffusion layer is impregnated with, for example, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), perfluorocarbon alkoxyalkane, ethylene-tetrafluoroethylene polymer, or a mixture thereof from the viewpoint of enhancing the drainage of moisture such as generated water. It is preferable to perform water-repellent processing by forming a water-repellent layer using these substances.

The method of providing a pair of electrodes on the inner and outer surfaces of the tubular electrolyte membrane is not particularly limited. For example, first, a tubular electrolyte membrane is prepared. It does not specifically limit as a method of forming a tubular electrolyte membrane, You may use the electrolyte membrane formed in the tube shape of a commercial item. Then, a solution containing electrolyte and catalyst particles is applied and dried on the inner and outer surfaces of the tubular electrolyte membrane to form a catalyst layer, and carbonaceous particles and / or carbonaceous fibers are contained on the two catalyst layers. The method of apply | coating and drying a solution and forming a gas diffusion layer is mentioned. At this time, the catalyst layer and the gas diffusion layer are formed so that a hollow portion exists on the inner surface of the gas diffusion layer formed on the inner surface side of the electrolyte membrane.
Alternatively, first, a carbon material such as carbonaceous particles and / or carbonaceous fibers and formed into a tube shape (tubular carbonaceous material) is used as a gas diffusion layer of the second electrode (anode), and the gas A solution containing an electrolyte and catalyst particles is applied to the outer surface of the diffusion layer and dried to form a catalyst layer to produce a second electrode, and then a solution containing the electrolyte is applied to the outer surface of the catalyst layer and dried. The first catalyst layer is formed on the outer surface of the electrolyte membrane layer and the electrolyte membrane layer, and the first gas diffusion layer is formed by applying and drying a solution containing a carbon material on the outer surface of the first catalyst layer. The method of doing is also mentioned. The tubular carbonaceous material can be obtained, for example, by dispersing a carbon material such as carbonaceous particles and an epoxy and / or phenolic resin in a solvent to form a tubular shape, thermosetting, and firing.

  In addition, the solvent used when forming the electrolyte membrane, the catalyst layer, and the gas diffusion layer may be appropriately selected according to the material to be dispersed and / or dissolved, and the coating method when forming each layer is also as follows. It can be appropriately selected from various methods such as a spray method and a brush coating method.

  The inner diameter, outer diameter, length, etc. of the tubular cell module can be appropriately designed according to the output required for the fuel cell, the design of the fuel cell such as the equipment to which the fuel cell is applied, and the operating conditions, and are particularly limited. Although not intended, the outer diameter of the tubular electrolyte membrane is preferably 0.01 to 10 mm, more preferably 0.1 to 1 mm, and particularly preferably 0.1 to 0.5 mm. . At present, it is difficult to manufacture a tubular electrolyte membrane having an outer diameter of less than 0.01 mm due to technical problems. On the other hand, when the outer diameter exceeds 10 mm, the surface area with respect to the occupied volume becomes small. This is not preferable because the power generation output per unit volume of the obtained cell module becomes small.

  The perfluorocarbon sulfonic acid resin membrane is preferably thin from the viewpoint of improving proton conductivity, but if it is too thin, the function of isolating gas is lowered and the permeation amount of aprotic hydrogen is increased. However, in comparison with a conventional fuel cell in which flat cells for fuel cells are stacked, a fuel cell manufactured by collecting a large number of hollow cell modules can take a large electrode area. Even when is used, sufficient output is shown. From this viewpoint, the thickness of the perfluorocarbon sulfonic acid resin film is 10 to 100 μm, more preferably 50 to 60 μm, and still more preferably 50 to 55 μm.

Moreover, from the preferable range of the outer diameter and film thickness of the above-mentioned perfluorocarbon sulfonic acid resin film, the preferable range of the inner diameter is 0.01 to 10 mm, more preferably 0.1 to 1 mm, and still more preferably 0. .1 to 0.5 mm.
The thickness of the catalyst layer provided on the inner and outer surfaces of the electrolyte membrane is preferably about 1 to 100 μm, and the thickness of the gas diffusion layer is preferably about 3 to 10 μm.

The cell module having a hollow shape used in the fuel cell of the present invention is not limited to the configuration exemplified above, and a layer other than the catalyst layer and the gas diffusion layer may be provided for the purpose of enhancing the function of the cell module. .
Moreover, the form and material of a collector (5, 6) are not specifically limited. Examples of the current collector material include a metal wire such as stainless steel or a foil. For example, the current collector may be fixed on the electrode with a conductive adhesive such as a carbon-based adhesive or an Ag paste.

In the embodiment shown in FIG. 1, a perfluorocarbon sulfonic acid resin film, which is a proton conducting film, is used as the electrolyte film, but the electrolyte film used in the fuel cell of the present invention is particularly limited. Instead, it may be proton-conductive or other ion-conductive such as hydroxide ions or oxide ions (O ²⁻ ). Examples of other ion-conducting electrolytes such as hydroxide ions and oxide ions (O ²⁻ ) include those containing ceramics. In the case of using an oxide ion conductive electrolyte membrane, oxide ions generated on the cathode side pass through the electrolyte membrane and reach the anode side, react with hydrogen to generate water and simultaneously release electrons. Therefore, in this case, since generated water is generated on the anode side, an anode is provided on the outer surface side of the tubular electrolyte membrane, and an oxidizing gas is circulated in the hollow.

It is the schematic which shows one example of the cell module with which the fuel cell of this invention is equipped. It is the schematic which shows the example of 1 form of the fuel cell of this invention. It is the schematic which shows another one example of the fuel cell of this invention.

Explanation of symbols

101 ... Cell module 1 ... Hollow electrolyte membrane (perfluorocarbon sulfonic acid resin membrane)
2 ... Cathode (electrode for generating water: first electrode)
3 ... Anode (second electrode)
4 ... Hollow part 5, 6 ... Current collector 7 ... Exterior container 8 ... Reservoir

Claims (5)

  A fuel cell comprising a cell module having a hollow electrolyte membrane and a pair of electrodes provided on an inner surface and an outer surface of the hollow electrolyte membrane, wherein the cell module is an electrode that generates generated water of the pair of electrodes. And a reservoir for storing water discharged from an electrode provided on the outer surface side of the hollow electrolyte membrane.   2. The fuel cell according to claim 1, further comprising means for reusing water in the reservoir.   3. The fuel cell according to claim 1, wherein the reservoir is provided so as to be positioned on a lower side in a gravitational direction of the cell module in a use state of the fuel cell.   The fuel cell according to any one of claims 1 to 3, wherein the cell module is arranged so that a longitudinal direction thereof is substantially perpendicular to a direction of gravity in a use state of the fuel cell.   A cell group in which a plurality of the cell modules are arranged; the cell group is accommodated in an outer container; and the outer container is an outlet / outlet of a substance supplied to electrodes provided on an inner surface and an outer surface of the hollow electrolyte membrane The fuel cell according to any one of claims 1 to 4, wherein airtightness with respect to the external space is maintained except for the above.

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