JP4608958B2 - Fuel cell - Google Patents

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. A solid polymer electrolyte fuel cell is a fuel cell that uses a solid polymer electrolyte membrane as an electrolyte, and has advantages such as being easy to downsize and operating 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.

The electrons generated in 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.

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.

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

In a fuel cell including a cell module having a hollow shape as described above, when an electrode that generates water as a result of an electrochemical reaction is provided on the hollow inner surface of an electrolyte membrane, the generated water or water vapor in the reaction gas is Moisture in a liquid state easily accumulates in the hollow of the cell module, such as moisture condensed due to supersaturation. This liquid moisture causes a soaked state of the electrode, so-called flooding, and decreases the flowability of the reaction gas (fuel gas or oxidant gas) through the hollow. As a result, the supply amount of the reaction gas, the electrode As a result, the power generation effective area of the fuel cell decreases and the power generation performance of the fuel cell decreases. Therefore, in order to improve the power generation performance of the fuel cell, it is necessary to discharge excess moisture present in the hollow to a location that does not adversely affect the reaction gas flow in the hollow and the moisture distribution of the electrode and the electrolyte membrane. It becomes important.
On the other hand, 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 in the polymer electrolyte membrane. Since the polymer electrolyte membrane moves from the cathode side to the cathode side, 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. That is, in order to improve the power generation performance of the polymer electrolyte fuel cell, excessive moisture may be discharged appropriately and moisture may be required.

  The present invention has been made in consideration of the above problems, and provides a fuel cell that is excellent in moisture management in the hollow interior of a cell module, particularly drainage, and that can effectively use water as needed. Objective.

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 inner surface side of the hollow electrolyte membrane, and a reservoir for storing water in the hollow is provided.
According to the present invention, moisture present in the hollow of the cell module, mainly generated water during the electrochemical reaction, does not adversely affect the flow of the reaction gas in the hollow and the moisture distribution of the electrode and the electrolyte membrane. Since it is stored in a reservoir provided at a place, problems caused by excessive moisture such as flooding and a decrease in the flow of reaction gas can be suppressed.

The specific configuration of the cell module in the fuel cell of the present invention includes a configuration in which an opening for guiding water to the reservoir is provided in the hollow of the hollow electrolyte membrane or the hollow extension connected to the hollow electrolyte membrane, Specifically, a reaction gas induction path is inserted into the hollow electrolyte membrane of the cell module or a hollow extension connected to the hollow electrolyte membrane, and the opening is connected to the outer periphery of the reaction gas induction path. The structure formed by the inner surface of the surrounding hollow electrolyte membrane or a hollow extension part is mentioned.
In addition, when the opening has a structure that allows the water collected in the reservoir to be volatilized again into the hollow of the hollow electrolyte membrane, the inside of the hollow of the hollow electrolyte membrane can be humidified. Since the electrolyte membrane and the electrode can be wetted, it is suitable for a fuel cell using an electrolyte membrane that requires a good wet state such as a solid polymer electrolyte membrane.
From the viewpoint of improving the drainage performance in the hollow of the hollow electrolyte membrane, the cell module is disposed so as to be oblique or perpendicular to the horizontal direction when the fuel cell is used, and a reservoir is provided at the lower end side of the hollow electrolyte membrane. It is preferable to be provided. By arranging the cell module in this way, the moisture in the hollow naturally falls into the reservoir due to gravity, and is efficiently discharged and collected.

Further, when the flow direction of the reaction gas in the hollow and the direction in which water is guided to the reservoir are reversed, the reaction gas flowing in the hollow can be prevented from entering the reservoir. It is also possible to promote volatilization of the water collected in the reservoir into the hollow electrolyte membrane.
The reservoir is preferably made of a stretchable material so as not to be damaged by expansion of water stored in the reservoir during freezing.
Further, when a heating means for heating the water in the reservoir is provided, it is possible to promote the evaporation of moisture in the reservoir and to quickly thaw the moisture in the frozen reservoir.

  According to the present invention, the moisture in the hollow of the cell module having a hollow shape is discharged and stored in a reservoir provided in a place that does not adversely affect battery characteristics such as power generation performance of the fuel cell. Problems caused by excessive moisture, such as a decrease in gas flowability in the hollow, can be prevented. Therefore, even in the case where an electrode for generating generated water is provided on the hollow inner surface side in a fuel cell provided with a cell module having a hollow shape, it exhibits excellent drainage and reduces the effective power generation area of the fuel cell. In addition, since the reaction gas can be circulated smoothly, high battery characteristics can be exhibited.

In particular, in the state of use of the fuel cell, the cell module is arranged so as to be perpendicular to the horizontal direction or inclined with respect to the horizontal direction, thereby providing a cell module having a hollow shape with only one opening. When it is difficult to push out the moisture inside the hollow with the pressure of the reaction gas, such as a fuel cell or a fuel cell that operates under a condition where the pressure of the reaction gas flow is low, Even when it is likely to occur, a fuel cell having excellent drainage can be obtained.
In addition, according to the present invention, since the gas flow path in the hollow is less likely to be clogged with moisture, the cell module can be reduced in diameter, so that the density of the cell module can be increased, and the unit volume It is possible to increase the per electrode area.

  Further, since the water collected in the reservoir is stored without being discarded, it can be used effectively, and in particular, a fuel using an electrolyte membrane that requires a good wet state such as a solid polymer electrolyte membrane. When the battery is used as moisture for humidifying the inside of the electrolyte membrane, drying of the electrolyte membrane can be suppressed, and as a result, the power generation performance of the fuel cell can be further enhanced. In addition, when a heating means for increasing the temperature of the moisture in the reservoir is provided, the moisture in the hollow is further humidified by evaporating more of the moisture stored in the reservoir, or the moisture frozen in the reservoir at a low temperature. Therefore, drying of the electrolyte membrane can be further suppressed.

  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 inner surface side of the hollow electrolyte membrane, and a reservoir for storing the water in the hollow is provided.

Hereinafter, the fuel cell of the present invention will be described by taking as an example a case where a perfluorocarbon sulfonic acid membrane which is one of solid polymer electrolyte membranes which is a kind of proton conducting membrane is used as an electrolyte membrane.
First, the first embodiment of the fuel cell of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic view showing an embodiment of the cell module of the present invention, and also shows an internal cross-section cut away. FIG. 2 is a schematic view showing a modification in which the cell module shown in FIG. 1 is provided with heating means for heating water in the reservoir.

  In FIG. 1, a cell module 101 has a tubular electrolyte membrane (perfluorocarbon sulfonic acid membrane) 1, and a first electrode (in this case, a cathode) 2 that generates generated water is on the hollow inner surface side of the electrolyte membrane 1. In addition, a second electrode (in this case, an anode) 3 paired with the first electrode is formed on the hollow outer surface side of the electrolyte membrane 1. Further, inside the first electrode (cathode) 2, a hollow portion (usually an oxidant gas channel such as air) 4 into which the reaction gas supplied to the first electrode flows is formed.

Reference numeral 5 denotes a reservoir for storing the water in the hollow, has a hollow shape formed by the outer wall 6 with the external space, and is provided on the lower end side in the gravity direction of the electrolyte membrane 1. The reaction gas guiding path 7 is inserted up to the boundary between the hollow portion of the electrolyte membrane and the outer wall 6 so as to penetrate the hollow of the reservoir formed by the outer wall 6. An opening 9 for guiding water to the reservoir 5 is formed in the hollow of the electrolyte membrane 1 from the inner periphery of the outer periphery 8 and the outer wall 6 surrounding the end outer periphery 8, and the hollow portion of the reservoir 5 and the hollow portion of the electrolyte membrane are formed in the opening 9. Communicate. The reactive gas guide path 7 is connected to a reactive gas (in this case, an oxidant gas such as air) supply source (not shown) supplied to the first electrode provided on the inner surface side of the electrolyte membrane, The reaction gas is supplied into the hollow of the electrolyte membrane 1 through the reaction gas guide path 7. Connection portions of the electrolyte membrane and the reservoir, and the reaction gas induction path and the reservoir are connected so as to maintain airtightness in the hollow of the cell module 101 (electrolyte membrane hollow, reaction gas induction path, reservoir hollow, etc.). ing.
Reference numerals 10 and 11 denote current collectors connected to the first electrode 2 and the second electrode 3, respectively, and one end thereof functions as an output terminal.

  The cell modules are usually arranged in a plurality of cells that are supported by a support plate, and the anode terminals and cathode terminals of each cell module are bundled and connected in parallel or in series, and the cell groups are connected in series with other cell groups. Or it connects in parallel and it is set as a cell aggregate. The cell group is surrounded and encased by an exterior member, and the hollow portion of the cell module (electrolyte membrane hollow portion, in the gas guiding path) is connected to the oxidant gas supply source, the internal space of the exterior member is connected to the fuel gas supply source, A reactive gas is supplied to both the inner and outer surfaces of each electrode. The configuration of the fuel cell, such as the connection configuration and arrangement configuration of the cell modules and cell groups, is not particularly limited. For example, the entire cell assembly may be casing and the internal space thereof may be communicated with the reaction gas supply source.

  The fuel cell of the present invention has excessive moisture present in the hollow of the electrolyte membrane, for example, water generated as a result of the electrochemical reaction at the inner surface side electrode, moisture condensed by supersaturation of water vapor in the reaction gas, etc. Are discharged and stored in a reservoir provided in a place that does not adversely affect the flow of the reaction gas and the moisture distribution of the electrode and the electrolyte membrane. Therefore, it prevents the problems caused by the presence of excessive moisture, such as flooding that is likely to occur at the electrode that generates the generated water, and a decrease in gas flowability in the hollow part that becomes the flow path for supplying the reaction gas to the inner surface side electrode. can do. Therefore, the fuel cell of the present invention does not decrease the effective power generation area of the fuel cell, and the reaction gas is smoothly circulated, so that excellent battery characteristics such as high power generation performance are exhibited.

  In order to quickly and surely discharge excess moisture in the hollow of the electrolyte membrane into the reservoir, the cell module is vertically or obliquely with respect to the horizontal direction when the fuel cell is used as shown in FIG. It is preferable that the reservoir be provided on the lower end side in the gravity direction of the tubular electrolyte membrane. By constructing and arranging the cell module in this way, excessive moisture in the hollow of the electrolyte membrane does not stay for a long time in a region that adversely affects the flowability of the reaction gas, the moisture distribution of the electrode, etc. Will naturally fall and be efficiently discharged into the reservoir. Since the water discharged and collected in the reservoir can be stored in the reservoir and used effectively, the cell module has a structure with excellent drainage as described above from the viewpoint of recovery for effective use. It is preferable to do. In order to move moisture into the reservoir more reliably and more quickly, it is preferable to arrange the cell module so that the inclination angle with respect to the horizontal direction is large, and it is particularly preferable that the cell module be perpendicular to the horizontal direction. The arrangement of the cell module so as to be oblique or vertical in the horizontal direction in the usage state of the fuel cell is not limited to the case where the cell module is fixedly installed in the fuel cell with a certain inclination angle, and some control is performed. This includes a case where the tilt angle of the cell module is adjusted at any time according to the displacement of the fuel cell by the mechanism.

  As described above, when the fuel cell is designed so that moisture flows down naturally into the reservoir due to gravity, it is necessary to apply gas pressure to force the moisture present in the hollow portion to move into the reservoir. Therefore, the design of the cell module and the fuel cell and the operating conditions of the fuel cell are not restricted. In particular, a fuel cell having a cell module having a hollow shape with only one gas inlet / outlet, a fuel cell having a low gas pressure flowing into the hollow of the cell module, etc., can extrude moisture in the hollow by the gas pressure. It is expected to exhibit an excellent effect when it is difficult or when the cell module is easily clogged, such as a fuel cell having an elongated hollow shape. In addition, since the hollow interior of the cell module serving as the reaction gas flow path is less likely to be clogged with moisture, the diameter of the cell module can be reduced. Therefore, the density of the cell modules can be increased, and the electrode area per unit volume can be increased.

In the present invention, the structure, position, material, and the like of the reservoir are not particularly limited as long as the moisture in the hollow of the electrolyte membrane can be stored. The arrangement state of the cell module when using the fuel cell, the hollow What is necessary is just to design suitably considering various conditions, such as the hollow shape of an electrolyte membrane.
For example, the opening for guiding water to the reservoir is usually provided in the hollow of a tubular (hollow shape) electrolyte membrane. The opening of the reservoir is not limited to the inner wall surface of the electrolyte membrane hollow portion, and may be provided at any position in the electrolyte membrane hollow. Further, in the design of the cell module, a hollow extension formed of a material different from that of the electrolyte membrane and the electrode may be connected to the hollow portion of the electrolyte membrane, and in that case, an opening is formed in the hollow of the hollow extension. Can also be provided. For example, in FIG. 1, at the boundary between the hollow portion of the electrolyte membrane and the outer wall of the reservoir, the opening of the reservoir is defined by the outer periphery of the open end of the reaction gas guiding path and the inner surface of the outer wall of the reservoir. The opening end of the gas guiding path may be inserted into the hollow inside of the electrolyte membrane, and the opening may be defined by the outer periphery of the reaction gas guiding path and the inner wall of the electrolyte membrane hollow portion. Moreover, the opening part which opened the hole directly in the inner wall face of the electrolyte membrane hollow part may be used.

The shape of the opening is not particularly limited, and may be, for example, an annular shape that surrounds the outer periphery of the reaction gas guiding path as shown in FIG. 1, an ellipse, a circle, or a polygon.
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. Further, only one or a plurality of openings can be provided.
In the embodiment shown in FIG. 1, a reservoir opening is provided so as to surround the outer periphery of the reaction gas guiding path and face the moisture guiding direction, and the moisture travels through the inner wall of the hollow portion of the electrolyte membrane. Since it flows down and is naturally guided to the opening, it is efficiently collected in the reservoir.

  When the opening of the reservoir is structured so that the water collected in the reservoir can be volatilized again into the hollow of the electrolyte membrane, the electrolyte membrane and the electrode are humidified by the volatilized water, so that the electrolyte It becomes easy to keep the membrane in a high wet state. Therefore, when an electrolyte membrane such as a polymer electrolyte membrane having a large effect on power generation performance is used, by providing an opening having the above structure, battery characteristics due to excessive moisture can be reduced. Along with the decrease, it is possible to prevent a decrease in power generation performance due to the drying of the electrolyte membrane, and it is possible to perform moisture management with a balance between moisture discharge and supply. 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. Then, it can move from the opening of the reservoir to the outside of the reservoir and volatilize into the hollow of the electrolyte membrane.

The water collected in the reservoir can be evaporated depending on 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 water collected in the reservoir is not evaporated. It is promoted and the drying of the electrolyte membrane can be further suppressed, so that the power generation performance of the fuel cell can be expected to be further improved. In addition, 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 startup to quickly humidify the electrolyte membrane. As such heating means, a heating element such as a heating wire 13 is provided on the outer periphery of the reservoir as in the cell module 102 in FIG. 2, and the water in the reservoir is heated by heating the outer wall of the reservoir. A heating element provided in the hollow to directly heat the water in the reservoir can also be mentioned.
Further, the water collected in the reservoir may be effectively used for other purposes such as cooling of the cell module in addition to humidification for preventing the electrolyte membrane and electrodes in the hollow from being dried as described above.

  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. Furthermore, although the product water itself generated at the cathode is pure water, the water discharged from the electrode usually shows (strong) acidity as a result of mixing with water molecules etc. that have moved with the protons from the anode side. Therefore, it is preferable that the material is excellent in corrosion resistance. From such a viewpoint, the material of the outer wall of the reservoir 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. The outer wall of the reservoir may have a single layer structure or a multilayer structure made of such materials. The reservoir provided in the cell module 101 shown in FIG. 1 and the cell module 102 shown in FIG. 2 is rubber formed in a bag shape, and the reservoir of the cell module 103 in FIG. Steel is used. In addition, as a method for manufacturing the reservoir, a method suitable for the material, shape, and the like to be used may be selected as appropriate, and a commercially available product formed into a shape having a hollow portion may be used. The reactive gas guiding path can also be formed using the same material as that of the reservoir described above.

  The flow direction of each reaction gas supplied to the inner and outer surfaces of the electrolyte membrane is not particularly limited, but the reaction gas flow direction in the hollow of the electrolyte membrane is opposite to the direction of water induction to the reservoir. It is preferable. By flowing the reaction gas into the hollow in such a direction, the reaction gas can be prevented from entering the reservoir. When the reaction gas enters the reservoir, the gas flow may be disturbed or the water in the reservoir may be pushed out by the gas pressure. In particular, in a state where the fuel cell is installed, the cell module is arranged so as to be vertical or oblique with respect to the horizontal direction, and the reservoir is provided on the lower end side in the gravity direction of the cell module, and then circulates in the hollow. It is preferable to distribute the reaction gas from the lower side to the upper side in the direction of gravity. In the cell module 101 of FIG. 1 having such a configuration, the reaction gas is supplied from the reaction gas guide path provided at the lower end of the electrolyte membrane into the hollow of the electrolyte membrane, and does not enter the reservoir in the direction of gravity. The water in the electrolyte membrane is circulated from the lower side to the upper side (the direction opposite to the weight direction), while the moisture in the hollow of the electrolyte membrane is induced by gravity from the upper side to the lower side (direction according to the weight direction) and collected in the reservoir. Further, in the case of FIG. 1, since the opening of the reservoir is located upstream in the flow direction of the reaction gas and the hollow portion of the electrolyte membrane is located downstream in the flow direction of the reaction gas, it is discharged from the opening of the reservoir. Water vapor moves into the hollow of the electrolyte membrane along the flow of the reaction gas, and the drying of the electrolyte membrane can be further suppressed.

  Moreover, the fuel cell shown in FIG. 3 is demonstrated as 2nd Embodiment of this invention. The cell module 103 shown in FIG. 3 is arranged perpendicular to the horizontal direction when the fuel cell is in use, and a reservoir is provided on the lower end side in the gravity direction of the hollow electrolyte membrane. As in the cell module 101 of FIG. 1, the hollow perfluorocarbon sulfonic acid membrane 1 is formed with a first electrode 2 for generating generated water on the inner surface side and a second electrode 3 on the outer surface side. It has the hollow part 4 used as the reaction gas flow path. The reservoir 5 provided at the lower end of the electrolyte membrane hollow has a double tube structure, and water flows from the opening 9 into the outer hollow part having the bottom. On the other hand, the tubular hollow portion inside the double tube does not have a bottom portion and functions as the reaction gas guide path 7. The water recovered in the reservoir is vaporized according to the humidity condition in the hollow and supplied again to the hollow portion of the electrolyte membrane.

  FIG. 3 shows a cell group in which a plurality of cell modules 103 as described above are collected. The plurality of cell modules 103 are fixed and aligned by partition plates 12a, 12b, and 12c. The cell module 103 penetrates the partition plates 12a, 12b, and 12c, and is partitioned into a reservoir portion by a partition plate 12b and a portion made of the hollow electrolyte membrane 1 and the electrodes 2 and 3. The space partitioned by the partition plates 12a and 12b is kept airtight, and the fuel gas supplied to the outer surface side electrode 3 of the hollow electrolyte membrane 1 flows. On the other hand, the oxidant gas supplied to the inner surface side electrode 2 flows from the lower end of the reaction gas guiding path into the cell module 103 in which the airtightness with the external space is maintained, and from the lower side to the upper side of the cell module. Circulates in the hollow. In FIG. 3, the current collector is not shown.

  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 membrane that 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 has a hollow shape. Since the electrode module per unit volume can be increased compared to a fuel cell having a flat cell, the electrolyte membrane does not have a proton conductivity as high as that of a perfluorocarbon sulfonic acid membrane. Even if is used, a fuel cell having a high output density per unit volume can be obtained. As the polymer electrolyte membrane, in addition to perfluorocarbon sulfonic acid, materials such as those used for the electrolyte membrane of a polymer electrolyte fuel cell can be used. For example, fluorine ion other than perfluorocarbon sulfonic acid can be used. It has at least one of proton exchange groups such as sulfonic acid groups, phosphonic acid groups, and phosphoric acid groups with a backbone of a hydrocarbon such as polyolefin such as an exchange resin and a polystyrene-based cation exchange membrane having a sulfonic acid group. A composite of a basic polymer and a strong acid, such as polybenzimidazole, polypyrimidine, polybenzoxazole, etc., doped with a strong acid, as disclosed in JP-A-11-503262. Examples include 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 perfluorocarbon sulfonic acid membranes include commercially available products such as Nafion manufactured by DuPont, USA 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 outer surface of the perfluorocarbon sulfonic acid membrane 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 on the hydrogen oxidation reaction at the anode and the oxygen reduction reaction at the cathode. For example, platinum, ruthenium, iridium, rhodium, palladium, osnium, tungsten, It can be selected from metals such as lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, or alloys thereof. Pt and an alloy made of Pt and another metal such as Ru are preferable.

  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, for example, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, perfluorocarbon alkoxyalkane, ethylene-tetrafluoroethylene polymer, or these from the point of improving the drainage of moisture such as generated water It is preferable to perform water-repellent processing by impregnating a mixture of the above or the like or forming a water-repellent layer using these substances.

The manufacturing method of the cell module which provided a pair of electrode in the inner surface and outer surface of a tubular electrolyte membrane is not specifically limited. For example, first, a tubular electrolyte membrane is prepared, and a solution containing electrolyte and catalyst particles is applied and dried on the inner and outer surfaces of the electrolyte membrane to form a catalyst layer, and a carbonaceous material is formed on the two catalyst layers. The method of apply | coating and drying the solution containing particle | grains and / or carbonaceous fiber, 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 tube material (tubular carbonaceous material) containing a carbon material such as carbonaceous particles and / or carbonaceous fibers is used as the gas diffusion layer of the first electrode (cathode), 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 first electrode, and then a solution containing the electrolyte is applied to the outer surface of the catalyst layer and dried. And forming a second gas diffusion layer by forming a second catalyst layer on the outer surface of the electrolyte membrane layer and further applying and drying a solution containing a carbon material on the outer surface of the catalyst layer. Can be mentioned.

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. 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 membrane is preferably thin from the viewpoint of improving proton conductivity. However, if the perfluorocarbon sulfonic acid membrane 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 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 said outer diameter and film thickness, the preferable range of an internal diameter is 0.01-10 mm, More preferably, it is 0.1-1 mm, More preferably, it is 0.1-0.5 mm. is there.
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. .
Further, the shape and material of the current collectors 10 and 11 are not particularly 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 membrane, which is a proton conducting membrane, is used as the electrolyte membrane. However, the electrolyte membrane used in the fuel cell of the present invention is not particularly limited. Alternatively, it may be proton-conductive or other ion-conductive such as hydroxide ion or oxide ion (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 inner surface side of the tubular electrolyte membrane, and hydrogen 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 one form example which provided the heating means which heats the water in a reservoir in the cell module shown in FIG. It is the schematic which shows one form example of the cell group which arranged the cell module in multiple numbers.

Explanation of symbols

1 ... Hollow electrolyte membrane (perfluorocarbon sulfonic acid membrane)
2 ... 1st electrode (cathode)
3. Second electrode (anode)
DESCRIPTION OF SYMBOLS 4 ... Hollow part 5 ... Reservoir 6 ... Outer wall of reservoir 7 ... Reaction gas induction path 8 ... Opening outer periphery of reaction gas induction path 9 ... Opening part 10, 11 ... Terminal 12a, 12b, 12c ... Partition plate 13 ... Heating means ( Heating wire)
101, 102, 103 ... cell module

Claims (8)

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 the water in the hollow, on the inner surface side of the hollow electrolyte membrane. The fuel cell according to claim 1, wherein an opening for guiding water to the reservoir is provided in a hollow of the hollow electrolyte membrane or a hollow extension connected to the hollow electrolyte membrane. A reaction gas induction path is inserted into the hollow electrolyte membrane of the cell module or a hollow extension connected to the hollow electrolyte membrane, and the opening has an outer periphery of the reaction gas induction path and a hollow electrolyte membrane surrounding the reaction gas induction path. The fuel cell according to claim 2, wherein the fuel cell is formed by an inner surface of the hollow extension portion. 4. The fuel cell according to claim 2, wherein the opening is capable of volatilizing water collected in the reservoir again into the hollow of the hollow electrolyte membrane. 5. 5. The cell module according to claim 1, wherein the cell module is disposed so as to be oblique or vertical with respect to a horizontal direction when the fuel cell is used, and a reservoir is provided on a lower end side of the hollow electrolyte membrane. Fuel cell. The fuel cell according to any one of claims 1 to 5, wherein a flow direction of the reaction gas in the hollow is opposite to a direction in which water is guided to the reservoir. The fuel cell according to claim 1, wherein the reservoir is made of a stretchable material. The fuel cell according to any one of claims 1 to 7, further comprising heating means for heating water in the reservoir.

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