JP2006164947A - Polymer electrolyte type fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that an output power of a solid polymer electrolyte fuel cell is lowered because of low electron conductivity, as far as a conventional current collection method through a gas diffusion layer is used. <P>SOLUTION: The current collector layer is made of a metallic porous body having gas permeability. A contact layer is formed by arranging the porous body made of carbon on a face contacting an electrode of the metallic porous body, and by the contact of an electrode of the metallic porous body 100 and a textile made of long carbon fiber. The formation of the contact layer is promoted by making the diameter of a warp 102 and weft 103 of the aggregated carbon fiber smaller than the diameter of the pore 101 of the metallic porous body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polymer electrolyte fuel cell used for a power source of a portable device or the like, particularly to an electrode thereof.

  In recent years, the possibility of a fuel cell as a power source for mobile devices such as notebook computers and mobile phones has been studied. Therefore, a “portable fuel cell device” is a method in which high-pressure hydrogen is packed in a cylinder (see, for example, Patent Document 1).

  In addition, a method of reacting methanol directly on an electrode (DMFC) has been proposed (see, for example, Patent Document 2).

  The reactivity of these fuel cells is said to be dominated by the state of the three-phase interface (the three-phase interface is the interface where the electrolyte, catalyst electrode, and reaction gas are in contact with each other) ( For example, refer nonpatent literature 1.).

  Therefore, in order to generate electricity efficiently, a good three-phase interface must always be maintained. The gas diffusion layer (GDL) that also serves as a current collector adjacent to the catalyst layer has (1) electronic conductivity. It is required to have functions such as (2) high gas diffusibility and air permeability, (3) efficient discharge of water or water vapor generated by the reaction, and (4) electrochemical stability. It is done. Conventionally, carbon support current collectors such as carbon paper have been widely used as GDLs that satisfy these functions.

Therefore, when a material such as carbon paper is used for the GDL, in order to reduce the internal resistance of the power generation cell, it must be pressed to improve the adhesion between the GDL and the catalyst layer. However, when using a conventional carbon porous body such as carbon paper, the fibers are developed in the surface direction, the gaps are crushed by pressing, and the ventilation performance of the gas or generated water is reduced. There was a problem. In order to solve this, the use of a foam metal having a high porosity has been studied (for example, see Patent Document 3).
JP 09-092318 A JP 2001-313046 A JP 2004-140001 A Surface Technology, 46, 1995, paragraph 702

  When conventional carbon paper was used, water evaporation was not sufficient at the cathode electrode, and flooding was likely to occur. However, when foam metal is used instead of carbon paper, the porosity is high and it is advantageous when water is evaporated, but the end surface of the foam metal is uneven, and the area where the foam metal and the catalyst layer come into contact is reduced. Since the electron conductivity is not high, a desired output cannot be obtained.

  In order to solve the above-described problems, each of the electrolyte layers made of proton conductive resin has an anode electrode and a cathode electrode on which catalyst layers are formed, and current collecting is performed on the surface of each electrode opposite to the electrolyte layer. In a solid polymer electrolyte fuel cell having a body layer, the current collector layer is made of a gas-permeable metal porous body, and the carbon porous body is disposed on the surface of the metal porous body in contact with the electrode It was. Further, the metal porous body having gas permeability is used in combination of two or more kinds of metal porous bodies having different pore diameters. In particular, use a metal porous body with a small pore size on the side that contacts the carbon porous body, and a metal porous body with a large pore size on the opposite side of the surface that contacts the carbon porous body. Use. At this time, as the metal porous body having a large pore diameter, a material having a high bending strength is preferable. Besides using a foam metal body, a punching metal or an expanded metal having an open area ratio of 40% or more is used.

  The porous metal body has a three-dimensional network structure like a sponge, and its end face can be approximated to be an aggregate of spheres having numerous open ends. One approximated to a sphere at this time is defined as a unit hole 104. The metal porous body is pressed against the carbon porous body. FIG. 3A shows a woven fabric composed of weft yarns 102 and warp yarns 103 formed by collecting carbon fibers of long fiber yarns, and unit holes 104. FIG. 3B shows a state in which the metal porous body is in contact with the carbon porous body. In the state of FIG. 3B, the weft 102 and the warp 103 formed by aggregating the carbon fibers of the long fiber yarn are in a state in which the binding is maintained. FIG. 3C shows a case where the metal porous body is pressed against the carbon porous body in the direction of the arrow 110. In the state shown in FIG. 3C, pressing the unit hole 104 generates a force 111 that pushes the weft 102 and the warp 103 outward, and either the weft 102 or the warp 103 positioned at the open portion of the unit hole 104. Either or both of these bonds loosen. A contact layer is formed by these processes. This contact layer forms a “solid-gas interface layer” composed of a carbon porous body and two phases of the open air open to the cathode electrode. Increases the solid-gas interface layer. Further, the contact layer has a rectangular shape formed in the cross section of the metal porous body, and a protrusion having a wedge-shaped end surface pierces the weft 102 and the warp 103 in which carbon fibers of long fiber yarns are gathered, and the carbon fiber A contact interface portion, that is, a solid-solid interface layer that penetrates into the bundle deeply and is strong and has an increased contact area is formed.

  By developing such a contact layer, increasing the solid-gas interface layer has an effect of promoting the evaporation of water generated in the cathode catalyst layer by the electrochemical reaction of the fuel cell.

  As a result, when conventional carbon paper is used, water evaporation is not sufficient at the cathode electrode and flooding is likely to occur, but it can be avoided. Moreover, a desired output can be maintained.

  In addition, an increase in the “solid-solid interface layer” has an effect of reducing the contact resistance affecting the electron conductivity. At this time, by combining the metal porous body having gas permeability with two or more kinds of metal porous bodies having different pore diameters, and using a metal porous body having a large pore diameter, a material having high bending strength, By forming the contact layer uniformly with respect to the surface direction, it can be expected that the maximum output is also improved due to the effect of suppressing variations in in-plane contact resistance.

  Furthermore, by forming the contact layer, it is possible to prevent the tip of the porous metal body having a wedge-shaped end face from coming into direct contact with the catalyst layer and the electrolyte membrane, and to suppress the reduction in reliability due to penetration or short circuit. . Further, by forming the contact layer, the catalyst metal made of a metal material different from the metal porous material is not in direct contact with each other, so that it is effective to suppress the occurrence of corrosion or the like due to the action of the local battery.

  The carbon porous body of the present invention can use a woven fabric or the like composed of weft yarns 102 and warp yarns 103 in which carbon fibers of long fiber yarns are aggregated, and a schematic diagram thereof is shown in FIG. At this time, the contact layer is formed by contacting the electrode of the metal porous body 100 and the fabric composed of the carbon fibers of the long fiber yarn. Here, when a foam metal is used as the metal porous body, the pores serving as the unit have a spherical structure having a void inside the needle-shaped metal. A cross section of the porous metal body used for forming the contact layer is schematically shown in FIG. At this time, when the void inside the porous metal having a porosity of 80% or more and close to 100% is assumed to be a pseudo sphere, the value corresponding to the diameter of the sphere is defined as the pore diameter 101. For this reason, the diameters of the weft yarn 102 and the warp yarn 103 formed by collecting carbon fibers are made smaller than the hole diameter 101 of the metal porous body, so that the formation of the contact layer is promoted.

  FIG. 4 shows an embodiment of the present invention. Here, in the case of the cathode electrode of the present invention, it is called the outside from the surface on which the electrolyte layer 107 made of proton conductive resin is arranged to the outside, and the inside from the outside to the side where the electrolyte layer 107 exists. Call it. At this time, a catalyst layer 108 containing carbon particles carrying fine particles of catalyst is disposed at an outer position in contact with the electrolyte layer 107 made of proton conductive resin. Between the catalyst layer 108 and the carbon porous bodies 102 and 103, a water-repellent layer 109 having conductivity made of carbon particles subjected to water-repellent treatment with PTFE or the like is formed. A porous body made of carbon, which is a woven fabric composed of weft yarns 102 and warp yarns 103 formed by collecting carbon fibers of long fiber yarns, is disposed at a position adjacent to the outside of the water repellent layer 109. Further, the metal porous body 100 having gas permeability is formed at a position outside the carbon porous body, which is a woven fabric composed of weft yarns 102 and warp yarns 103 formed by gathering carbon fibers of long fiber yarns. The current collector layer is arranged.

  The electrolyte layer 107 made of a proton conductive resin used in the fuel cell of the present invention is made of a perfluoro resin film that exhibits proton conductivity at room temperature, a graft polymer film such as a composite of engineering plastic, or a partially fluorinated film. However, it is not limited to those materials.

  As the catalyst used for the cathode electrode catalyst layer 108 and the anode electrode catalyst layer, platinum-supported carbon can be used. The catalyst element of the electrode is not limited to platinum, and various alloys and oxides can be used.

  The metal porous body 100 is required to have a high electron conductivity, a high corrosion resistance, and a mechanical strength, in addition to the air permeability and the liquid permeability. Therefore, the three functions of the skeleton with mechanical strength, the conductive layer with electron conductivity, and the protective layer with corrosion resistance may be composed of different types of materials, but the three different functions are It is also possible to carry out with the simple substance or alloy. For example, metal titanium, metal nickel, nickel-chromium alloy, or stainless steel can be used.

  The metal porous body can be a sintered body of metal fibers, a sintered body of powder metal, or the like. As the metal porous body 100, a net woven with metal wire, an expanded metal, or a punching metal (hole shape: round hole, slit, herribbon, square hole, slit bay window screen) can be used in combination. In consideration of the porosity and vent holes, it is most desirable to use a metal foam body as the metal porous body. When a foam metal body is used as the metal porous body, the skeleton has a three-dimensional network like a sponge, and therefore has a high air permeability or liquid permeability due to a very high porosity. The method for producing the foam metal body is as follows: raw powder, water-soluble resin binder, foaming agent which is a water-insoluble hydrocarbon-based organic solvent, surfactant added as necessary, remaining water and inevitable impurities It is also possible to use a foamed metal body composed of a fired foamed sintered metal using a foamed slurry obtained by mixing the above as a raw material. Alternatively, it may be a metal foam body formed by a plating process in which urethane foam is subjected to electroconductive treatment and then subjected to heat treatment as necessary. Furthermore, the metal porous body is preferably used in combination of two or more kinds of metal porous bodies having different pore diameters. In particular, use a metal porous body with a small pore size on the side that contacts the carbon porous body, and a metal porous body with a large pore size on the opposite side of the surface that contacts the carbon porous body. Use. At this time, as the metal porous body having a large pore diameter, a material having high bending strength is preferable, and besides using a foam metal body, a punching metal or an expanded metal having an open area ratio of 40% or more can be used.

For the metal porous body 100, a metal porous body having a porosity of 60% or more is used with a thickness of 0.5 mm or more so that water vapor generated at the cathode is easily diffused into the atmosphere. More preferably, a metal porous body having a porosity of 90 to 98% is used with a thickness of 0.5 mm to 2 mm. The compressive strength is preferably 0.01 to 0.15 kg / mm ³ . In the case of using the metal foam body 100, the average diameter of the metal unit holes 104, that is, the hole diameter 101 may be larger than the diameter of the carbon fiber of the carbon porous material, and is preferably 0.3 mm or more and 3.2 mm or less. More preferably, the hole diameter is 0.6 mm or more and 1 mm or less. In order to improve the air permeability required for the catalyst layer 108 of the cathode electrode, it is preferable that the hole diameter is large. However, when the pore diameter 101 of the metal foam body is too large, the carbon porous material has low mechanical strength, and the contact with the carbon porous material decreases. At the same time, when the load 110 is increased, only the pressed portion is localized. Compressed and crushed. At this time, the continuity of the path in which the gas diffuses in the carbon porous body is lost, and the air permeability is lowered. On the other hand, if the pore diameter 101 of the metal foam body is too small, the fibers are in close contact with the pores or block the pores, and the continuity of the path in which the gas diffuses in the carbon porous body is lost, and the air permeability is lost. By lowering, the generated steam and water are also inhibited from being discharged. Such a decrease in air permeability and inhibition of product discharge properties cause a decrease in output during continuous power generation in power generation of the fuel cell. When the air permeability at this time is converted into pressure loss, it becomes 10 mmaq or less, more preferably 5 mmaq or less at a wind speed of 0.5 m / s. When evaporating water, the required specific surface area is 500 or more and 15000 m ² / m ³ .

  When the metal porous body 100 is incorporated into an electrode, it is desirable to perform plating for preventing oxidation, metal spraying, or the like. It is desirable to use gold or tantalum as the plating material. Further, it is preferable to remove the oxide film on the surface on which the contact layer is formed by being in contact with the carbon porous body. The removal of the oxide film can be performed by physical removal of sandpaper or sunblast, or by pickling with an acidic solution such as hydrochloric acid, sulfuric acid, or nitric acid.

  In the present invention, the foamed metal body 100 and the carbon porous body are used simultaneously for at least one of the cathode and the anode.

  As the carbon porous body, paper-like “carbon fiber paper (hereinafter abbreviated as CFP)” can be used. Carbon fiber paper can use 10 mm or more of short fiber in the carbon material produced by binding short fiber with a binder.

In order to form the contact layer, it is preferable to use a woven fabric composed of wefts and warps formed by aggregating a plurality of carbon fibers. A fabric composed of wefts and warps formed by aggregating a plurality of carbon fibers is sometimes referred to as “carbon cloth (hereinafter abbreviated as CL)”. The purity of the carbon material is preferably 85% or more, and its density is preferably 1.72 to 2.1 g / cc. The fiber diameter is preferably 1 to 20 μm. In the case of a woven fabric composed of weft and warp, the density of the weft and the warp is preferably 15 to 25 yarns / cm. The density of the carbon material is preferably ⁸ to 200 g / m ² , more preferably 80 to 200 g / m ² . The thickness of the carbon material without load is preferably 180 to 450 μm, more preferably 280 to 400 μm. As the fabric, flat knitting, milling knitting, Kanoko knitting and the like can be used, but flat knitting is preferred. The porosity of the carbon material is preferably 70 to 90%.

Here, the conductive water-repellent layer 109 composed of carbon particles subjected to water-repellent treatment with PTFE or the like and the weft 102 and the warp 103 formed by aggregating the carbon fibers of the long fiber yarn adjacent to the outside are combined. The carbon porous body 111 is obtained. The total thickness in the stacking direction of the carbon porous body 111 and the metal porous body 100 is preferably 3.1 mm or less in view of the degree of influence on the decrease in air permeability and the product dischargeability. The carbon porous body 111 is preferably 0.9 mm or less, and the thickness of the metal porous body 100 is preferably 3.0 mm or less. Therefore, FIG. 5 shows the relationship between the thickness of the carbon porous body 111 as t1 and the thickness of the metallic porous body 100 as t2. The ratio of t2 / t1 is preferably 7.5 [−] or less. FIG. 6 shows a bird's-eye view of the carbon porous body 111 and the metal porous body 100 observed from the outside. At this time, the area 112 of the carbon porous body 111 is S ₁ , and the area 113 of the metal porous body 100 is S ₂ . At this time, the ratio of S ₂ / S ₁ is preferably 1 or more.

  Furthermore, water repellent treatment is performed on at least a part of the surface of the metal porous body 100 in order to quickly discharge water vapor and water generated by the reaction by performing water repellency treatment on the surface of the metal porous body 100. It is desirable to apply. Alternatively, it is desirable to perform a hydrophilic treatment on at least a part of the surface of the metal porous body 100. Furthermore, it is desirable that the surface of the metal porous body 100 is subjected to water repellent treatment and hydrophilic treatment separately. The water repellent treatment can be performed by using a method of coating pure gold, a method of coating carbon such as graphite, or a method of coating an organic substance containing fluorine. As a method for coating gold, any method such as electrolytic plating, electroless plating, thermal spraying, vapor deposition, and sputtering can be used. In the case of carbon, in addition to the method described above, it is also possible to apply a solution or slurry mixed with a binder. Coating with fluorine-containing organic material as a coating method, placing the fluorine-containing material in a heating furnace, heat-treating it to near the decomposition temperature of the organic material containing fluorine (400 ° C. or less), and applying the decomposition vapor can do. Or, after immersing the metal porous body 100 in a dispersion solvent in which organic fine particles containing fluorine having a particle diameter of approximately 1 to 15 μm are dispersed in water, alcohol or other organic solvent, the metal porous After pulling up the solid body 100 and removing excess solvent adhering to the surface of the metal porous body 100, the temperature is equal to or higher than the boiling point of the organic dispersion solvent containing fluorine coated on the metal porous body 100. It can be dried and removed by heating, and then heat-treated in a heating furnace at a temperature not higher than the decomposition temperature of organic matter containing fluorine (400 ° C. or lower). Here, as an organic substance containing fluorine, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroethylene-propene copolymer ( FEP), polyvinylidene fluoride (PVdF), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and the like can be used.

Furthermore, in particular, when polyvinylidene fluoride (PVdF) is used, a method of coating using the above-described method after immersing the metal porous body 100 after being diluted in an organic solvent such as N-methylpyrrolidone. Can be used.
The heat treatment accompanying the coating of the organic substance containing fluorine can be performed in the air or in vacuum, but it is more preferable to perform it in vacuum.

  Further, the water-repellent carbon layer 109 can be formed using a mixture of conductive carbon and the above-described organic material containing fluorine. Carbon blacks classified as furnace black, channel black, thermal black, and lamp black as conductive carbon used for the water-repellent carbon layer 109 preferably have a large specific surface area due to their unique particle shape. The specific surface area varies depending on the type of carbonaceous material used, but also varies depending on the degree of particle size distribution after the pulverization step even if the same carbonaceous material is used. The carbonaceous material used in the present invention preferably has a specific surface area (BET method) distributed in a range of 5 to 50 m <2> / g, more preferably 10 to 35 m <2> / g.

  Here, the whole power generation cell will be described with reference to FIG. The power generation element 114 is configured except for the metal porous body 100. The constituent elements include an electrolyte layer 107 made of proton conductive resin, a cathode catalyst layer 108, an anode catalyst layer, a holding portion 110, a carbon porous body 111, and a packing for preventing leakage of fuel. Is done. A metal porous body 100 is disposed outside the power generation element 1114 at the cathode electrode, and a pressing plate 110 is disposed in order to add a load to the metal porous body 100. The holding plate 110 has a slit for supplying outside air to the metal porous body 100 or a through-hole having another shape. The holding plate 110 applies a load to the power generation element 114 to the anode current collector 117 and establishes conduction of the anode electrode. Here, as a method of applying a load to the pressing plate, a method of passing the bolt 116 through the pressing plate 110 and fastening it to the housing 119 can be used. Further, the housing 119 can be provided with a fuel supply unit 118 for supplying hydrogen as fuel to the anode electrode.

  It is preferable to connect the electrode leads 115 directly from the metal porous body 100. In particular, when a lead is taken out from two or more kinds of metallic porous bodies (2), it is only necessary to maintain electrical connection with at least one of them. As a method of connecting the lead to the metal porous body, electrical connection by contact can be used, but means such as resistance welding, laser welding, and ultrasonic welding can be used.

  As a material of the pressing portion 113 for applying weight to the metal porous body 100, polymer polymers such as polyethylene, polypropylene, polyethylene terephthalate, polyphenylene sulfide, ceramics such as alumina oxide, metal materials similar to the metal porous body 110, Corrosion-resistant spring-like metal materials such as ferritic stainless steel, martensitic stainless steel, austenitic stainless stainless steel, and spron can be used. In particular, when a polymer is used, it is preferable to use a material in which fibers are reinforced with glass.

  Hydrogen as a fuel is generated by combining a hydrogen generating substance and a substance that promotes generation. Here, examples of combinations of hydrogen generating substances and substances that promote generation are enclosed in parentheses and listed below. (Sodium hydroxide, metallic aluminum), (sodium borohydride, water), (sodium borohydride, sulfuric acid), (sodium borohydride, malic acid), (sodium borohydride, citric acid), (hydrogenated) Sodium borohydride, oxalic acid), (sodium borohydride), (sodium borohydride, cobalt chloride), (sodium borohydride, nickel chloride), (sodium borohydride, cobalt metal powder), (borohydride) Sodium, nickel powder), (sodium borohydride, boric acid), (lithium hydride, water), (sodium hydride, water), (magnesium hydride, water), (calcium hydride, water), (hydrogen Aluminum aluminium, water). When sodium borohydride is used as these hydrogen generating substances, various inorganic acids, organic acids, transition metal chlorides, and the like can be used in addition to water.

  Devices that can be applied with the power supply of the present invention are classified and exemplified as follows. [1] Examples of 2 to 20 class W equipment include notebook computers, touch panel input personal computers, external power supplies for video equipment, lighting equipment, and handy cleaners. [2] Equipment requiring about 1 to 2 W , Digital still cameras, health equipment, mobile phones, wearable mobile phones, order entry system terminals, mobile printers, power tools, car phones, transceivers, pen input PCs, electronic book players, LCD TVs, wearable TVs, electric shavers be able to. [3] Devices capable of operating at 1 W or less, wearable personal computers, arm-type PHSs, electronic dictionaries, toys, medical devices, wearable medical devices, pagers, wearable calculators, wearable GPS systems, voice input devices, memory cards, tape recorders, Examples include a radio, a headphone stereo, a portable DVD, an electronic notebook, a cordless phone, a portable MD, a portable CD, a camcorder, and a game machine. In particular, the present invention contributes most effectively as an effective power source in applications that require a small size or a thin shape as shown in [2] and [3] and further require a light weight.

In accordance with the present invention, the cathode catalyst layer 108 and the anode catalyst layer were sandwiched from both sides of a commercially available membrane electrode assembly formed in advance on the solid electrolyte membrane 107 using a fibrous carbon porous body. At that time, packing that also serves as a spacer is disposed on the outer periphery of the cathode catalyst layer 108 and the carbon porous body 111. Similarly, packing that also serves as a spacer is disposed on the outer periphery of the anode catalyst layer and the carbon porous body.
The thickness of the electrolyte membrane 107 is 30 μm. A catalyst layer is composed of carbon particles in which platinum is dispersed (supported) at 0.3 mg / cm ² as a catalyst on both the cathode electrode side and the anode electrode side of this electrolyte membrane and a proton conductive fluorine-based solid electrolyte. ing. The size of the catalyst layer was 20 mm × 25 mm. The rubber hardness used for the packing was about 50%, and a thickness of 200 μm was cut into a desired dimension and used. The carbon porous body 111 sandwiched from both sides of the membrane electrode assembly had a thickness of 300 to 440 μm. A layer 109 containing conductive carbon having water repellency is formed in advance on the surface of the carbon porous body 111 so that the layer 109 containing conductive carbon having water repellency and the catalyst layer are electrically connected. Arranged. The area 112 of the carbon porous body 111 is larger than the catalyst layer at an area ratio of about 30%.

Using this carbon porous body 111 and metal porous body 100, a contact layer was formed. As this metal porous body 100, a nickel foam metal body (manufactured by Sumitomo Electric, Celmet, product number # 4) having a thickness of 2.0 mm was cut into a size of 30 mm × 42 mm with metal scissors. This metal porous body has the characteristics that the number of cells is 27 to 33 / inch, the pore diameter is 0.8 mm, and the specific surface area is about 2500 m ² / m ³ . In order to take out electrons from the porous metal body, nickel-like lead wires having a thickness of 0.1 mm and a width of 7.0 mm were directly welded by resistance welding. In the metal porous body 100, the lead 115 and the welded portion are rolled in advance to obtain a flat surface. The lead 115 was welded at intervals of 3.0 mm over about 30 mm.
The surface of the metal porous body 100 with the leads 115 was subjected to water repellent treatment. In the water-repellent treatment, the metallic porous body 100 with the leads is dipped in a fine powder dispersion solution of fluorine-containing resin (DuPont, DryFilm, RA), and the surface of the metallic porous body 100 is immersed. The entire surface was covered with PTFE fine powder, and the solvent was removed in a hot air drying oven at 120 ° C. for 20 minutes. Furthermore, it heated at 300 degreeC and the film | membrane by the resin containing a fluorine was spread over the whole surface of the foam metal.

By the water repellent treatment, the surface of the metal porous body 100 is coated with a highly insulating resin, so that it is insulated and loses its electronic conductivity. Therefore, the surface of the metal porous body 100 in contact with the carbon porous body 111 is polished with sandpaper (# 1000) to remove the resin film containing fluorine, and further the metal porous body The oxide film on the surface of the body 110 was also removed. The metal porous body 110 was fastened with a bolt 116 to a current collector 117 of an anode electrode having uneven hydrogen supply portions 118 at intervals of 1 mm, using a pressed portion 110 made of stainless steel. At this time, the bolt 116 disposed around the power generation element 114 was tightened with a torque driver (Tohichi, RTD120CN type) with a torque of 50 CNm or less. Then, cells having t ₁ = 0.2 mm, t ₂ = 2.0 mm, and t ₂ / t ₁ = 10 [−] were created as the parameters described above. At this time, the foam metal presses the porous body made of carbon with a load of 3 kgf / cm ² . The cell created in this way is referred to as Example 1. 99.99% pure in this cell, per unit area of hydrogen comprising 24 ° C., at a flow rate of 10cc / min · cm ^2, and regulated supply such that the gas pressure at the outlet is substantially atmospheric pressure. The cathode side was exposed to an atmosphere of about 40% RH and 25 ° C. At this time, an electronic load device (KFM2030, manufactured by Kikusui Electronics Co., Ltd.) was used, the load on the cell was changed between 0 A / cm ^{2 and} 0.8 A / cm ² , and the voltage at that time was recorded with a recorder. . The result at that time is shown in FIG.

  From the graph, it can be seen that the voltage at 0.3 A / sqcm is around 0.7V. Next, a change in voltage was recorded in this cell while maintaining an output of 0.3 A / sqcm under the gas supply conditions described above. Fig. 10. The voltage changes over time, and the degree of the change is shown as Example 1 in FIG. At this time, the voltage of 0.6 V was maintained for 18 hours or more. The voltage at 18 hours was 0.636V.

  In Example 1 above, the water-repellent treatment using the PTFE fine powder was not performed, but the fuel cell produced under the same conditions was used except that only one surface of the metal porous body was removed of the oxide film. Example 7 is used. Similar to the conditions described above, the change in voltage was recorded while maintaining an output of 0.3 A / sqcm. The results are shown as Example 2 in FIG. From this, it can be seen that the fuel cell using the solid oxide fuel cell electrode of the present invention exhibits excellent voltage maintaining characteristics. The voltage at 18 hours was 0.628V.

  A fuel cell manufactured in the same manner as in Example 1 except that the water-repellent treatment using the PTFE fine powder was not performed and the oxide film was not removed is referred to as Example 3. Similar to the conditions described above, the change in voltage was recorded while maintaining an output of 0.3 A / sqcm. The results are shown as Example 3 in FIG. From this, it can be seen that the fuel cell using the solid oxide fuel cell electrode of the present invention exhibits excellent voltage maintaining characteristics. The voltage at 18 hours was 0.546V.

In accordance with the present invention, fibrous carbon porous body 201 and carbon porous body 205 are formed from both sides of a commercially available membrane electrode assembly in which cathode catalyst layer 204 and anode catalyst layer 202 are previously formed on solid electrolyte membrane 203. Used to pinch. At this time, packing that also serves as a spacer is disposed on the outer periphery of the cathode catalyst layer 204 and the carbon porous body 205. Similarly, a packing that also serves as a spacer is disposed on the outer periphery of the anode catalyst layer 202 and the carbon porous body.
The thickness of the electrolyte membrane 203 is 30 μm. A catalyst layer is composed of carbon particles in which platinum is dispersed (supported) at 0.3 mg / cm ² as a catalyst on both the cathode electrode side and the anode electrode side of this electrolyte membrane and a proton conductive fluorine-based solid electrolyte. ing. The size of the catalyst layer was a circle having a diameter of 11 mm. The rubber hardness used for the packing was about 50%, and a thickness of 200 μm was cut into a desired dimension and used. The carbon porous body 201 and the carbon porous body 205 sandwiched from both sides of the membrane electrode assembly had a thickness of 300 to 440 μm. A layer containing water-repellent conductive carbon is formed in advance on the surfaces of the carbon porous body 201 and the carbon porous body 205, and the water-repellent conductive carbon-containing layer and the catalyst layer are electrically connected. Arranged to connect to.

  Using this carbon porous body 205 and metal porous body 206, a contact layer was formed. As the metal porous body 206, a nickel foam metal body (manufactured by Mitsubishi Materials) having a thickness of 1.0 mm was cut into a circle having a diameter of 20 mm using metal scissors. This metal porous body has an average pore diameter of 300 μm.

The above-described power generating element was fastened with bolts 208 using a fuel supply portion having slit portions at intervals of 1 mm, a current collector 200 serving as an anode, and a pressing plate 207 made of stainless steel. This stainless steel pressing plate 207 had a breathable hole and was connected by lead to take out electrons. The stainless steel pressing plate 207 and the bolt are insulated. At this time, the bolt 208 arranged around the power generation element was tightened with a torque driver (Tohnichi, RTD120CN type) with a torque of 50 CNm or less. Then, as the parameters described _{above, t 1 = 0.2mm, t 2} = 1.0mm, t 2 / t 1 = 5 - was created consisting Cell []. The cell created in this way is referred to as Example 4. FIG. 10 schematically shows an embodiment of the present invention. At this time, hydrogen having a purity of 99.99% and a temperature of 24 ° C. was supplied to the cell at a flow rate of 10 cc / min · cm 2 at a flow rate of 10 cc / min · cm 2 so that the gas pressure at the outlet was approximately atmospheric pressure. The cathode side was exposed to an atmosphere of about 40% RH and 25 ° C. At this time, an electronic load device (KFM2030 type, manufactured by Kikusui Electronics Co., Ltd.) was used, and the load on the cell was changed between 0 A / cm2 and 1.0 A / cm2, and the voltage at that time was recorded with a recorder. FIG. 13 shows the current / voltage characteristics of the fuel cells produced in Example 1 and Example 4.

  In accordance with the present invention, fibrous carbon porous body 201 and carbon porous body 205 are formed from both sides of a commercially available membrane electrode assembly in which cathode catalyst layer 204 and anode catalyst layer 202 are previously formed on solid electrolyte membrane 203. Used to pinch. At this time, packing that also serves as a spacer is disposed on the outer periphery of the cathode catalyst layer 204 and the carbon porous body 205. Similarly, a packing that also serves as a spacer is disposed on the outer periphery of the anode catalyst layer 202 and the carbon porous body.

The thickness of the electrolyte membrane 203 is 30 μm. A catalyst layer is composed of carbon particles in which platinum is dispersed (supported) at 0.3 mg / cm ² as a catalyst on both the cathode electrode side and the anode electrode side of this electrolyte membrane and a proton conductive fluorine-based solid electrolyte. ing. The size of the catalyst layer was a circle having a diameter of 11 mm. The rubber hardness used for the packing was about 50%, and a thickness of 200 μm was cut into a desired dimension and used. The carbon porous body 201 and the carbon porous body 205 sandwiched from both sides of the membrane electrode assembly had a thickness of 300 to 440 μm. A layer containing water-repellent conductive carbon is formed in advance on the surfaces of the carbon porous body 201 and the carbon porous body 205, and the water-repellent conductive carbon-containing layer and the catalyst layer are electrically connected. Arranged to connect to.

  Using this carbon porous body 205 and metal porous body 206, a contact layer was formed. As the metal porous body 206, a nickel foam metal body (manufactured by Mitsubishi Materials) having a thickness of 1.0 mm was cut into a circle having a diameter of 20 mm using metal scissors. This metal porous body has an average pore diameter of 300 μm.

  Further, in order to stably form this contact layer, a metal porous body 206 that is in contact with the metal porous body 206 and has a pore diameter different from that of the metal porous body 206 on the opposite surface of the carbon porous body. The body 210 was placed. The metal porous body 210 is an expanded metal made of nickel having a plate thickness of 0.3 mm. The center distance (SW) of the mesh in the short direction is 1.8 mm, and the center distance in the long direction of the mesh ( LW) 3.0 mm, step width (W) 0.5 mm.

The above-described power generating element was fastened with bolts 208 using a fuel supply portion having slit portions at intervals of 1 mm, a current collector 200 serving as an anode, and a pressing plate 207 made of stainless steel. This stainless steel pressing plate 207 had a breathable hole, and a lead was connected to take out electrons. The stainless steel pressing plate 207 and the bolt are insulated. At this time, the bolt 208 arranged around the power generation element was tightened with a torque driver (Tohichi, RTD120CN type) with a torque of 50 CNm or less. Then, as the parameters described _{above, t 1 = 0.2mm, t 2} = 1.0mm, t 2 / t 1 = 5 - was created consisting Cell []. The cell created in this way is referred to as Example 4. FIG. 10 schematically shows an embodiment of the present invention. At this time, hydrogen having a purity of 99.99% and a temperature of 24 ° C. was supplied to the cell at a flow rate of 10 cc / min · cm 2 at a flow rate of 10 cc / min · cm 2 so that the gas pressure at the outlet was approximately atmospheric pressure. The cathode side was exposed to an atmosphere of about 40% RH and 25 ° C. At this time, an electronic load device (KFM2030, manufactured by Kikusui Electronics Co., Ltd.) was used, and the load on the cell was changed between 0 A / cm ^{2 and} 1.0 A / cm ² , and the voltage at that time was recorded with a recorder. . FIG. 13 shows a comparison of the maximum output per unit area of the fuel cells produced in Example 1, Example 4, and Example 5.

  In accordance with the present invention, fibrous carbon porous body 201 and carbon porous body 205 are formed from both sides of a commercially available membrane electrode assembly in which cathode catalyst layer 204 and anode catalyst layer 202 are previously formed on solid electrolyte membrane 203. Used to pinch. At this time, packing that also serves as a spacer is disposed on the outer periphery of the cathode catalyst layer 204 and the carbon porous body 205. Similarly, a packing that also serves as a spacer is disposed on the outer periphery of the anode catalyst layer 202 and the carbon porous body.

The thickness of the electrolyte membrane 203 is 30 μm. A catalyst layer is composed of carbon particles in which platinum is dispersed (supported) at 0.3 mg / cm ² as a catalyst on both the cathode electrode side and the anode electrode side of this electrolyte membrane and a proton conductive fluorine-based solid electrolyte. ing. The size of the catalyst layer was a circle having a diameter of 11 mm. The rubber hardness used for the packing was about 50%, and a thickness of 200 μm was cut into a desired dimension and used. The carbon porous body 201 and the carbon porous body 205 sandwiched from both sides of the membrane electrode assembly had a thickness of 300 to 440 μm. A layer containing water-repellent conductive carbon is formed in advance on the surfaces of the carbon porous body 201 and the carbon porous body 205, and the water-repellent conductive carbon-containing layer and the catalyst layer are electrically connected. Arranged to connect to.

  Using this carbon porous body 205 and metal porous body 206, a contact layer was formed. As the metal porous body 206, a nickel foam metal body (manufactured by Mitsubishi Materials) having a thickness of 1.0 mm was cut into a circle having a diameter of 20 mm using metal scissors. This metal porous body has an average pore diameter of 300 μm.

  Further, in order to stably form this contact layer, a metal porous body that is in contact with the metal porous body 206 and has a pore diameter different from that of the metal porous body 206 on the opposite surface of the carbon porous body. 210 was placed. The metal porous body 210 is an expanded metal made of nickel having a plate thickness of 0.3 mm. The center distance (SW) of the mesh in the short direction is 1.8 mm, and the center distance in the long direction of the mesh ( LW) 3.0 mm, step width (W) 0.5 mm.

  Further, a metal porous body 211 having a different pore diameter was disposed on the surface opposite to the metal porous body 206 in contact with the metal porous body 210. This metal porous body is a punching metal made of stainless steel having a thickness of 1 mm and a hole diameter of 2 mm, the hole pitch is 3.0 mm, and the opening ratio is about 40.6%.

The above-described power generating element was fastened with bolts 208 using a fuel supply portion having slit portions at intervals of 1 mm, a current collector 200 serving as an anode, and a pressing plate 207 made of stainless steel. This stainless steel pressing plate 207 had a breathable hole and was connected by lead to take out electrons. The stainless steel pressing plate 207 and the bolt are insulated. At this time, the bolt 208 arranged around the power generation element was tightened with a torque driver (Tohichi, RTD120CN type) with a torque of 50 CNm or less. Then, cells having t ₁ = 0.2 mm, t ₂ = 1.0 mm, and t ₂ / t ₁ = 5 [−] were created as the parameters described above. The cell created in this way is referred to as Example 4. FIG. 10 schematically shows an embodiment of the present invention. At this time, hydrogen having a purity of 99.99% and a temperature of 24 ° C. was supplied to the cell at a flow rate of 10 cc / min · cm ² per unit area so that the gas pressure at the outlet was approximately atmospheric pressure. The cathode side was exposed to an atmosphere of about 40% RH and 25 ° C. At this time, an electronic load device (KFM2030, manufactured by Kikusui Electronics Co., Ltd.) was used, and the load on the cell was changed between 0 A / cm ^{2 and} 1.0 A / cm ² , and the voltage at that time was recorded with a recorder. .
(Comparative example)
In accordance with the present invention, fibrous carbon porous body 201 and carbon porous body 205 are formed from both sides of a commercially available membrane electrode assembly in which cathode catalyst layer 204 and anode catalyst layer 202 are previously formed on solid electrolyte membrane 203. Used to pinch. At this time, packing that also serves as a spacer is disposed on the outer periphery of the cathode catalyst layer 204 and the carbon porous body 205. Similarly, a packing that also serves as a spacer is disposed on the outer periphery of the anode catalyst layer 202 and the carbon porous body.
The thickness of the electrolyte membrane 203 is 30 μm. A catalyst layer is composed of carbon particles in which platinum is dispersed (supported) at 0.3 mg / cm ² as a catalyst on both the cathode electrode side and the anode electrode side of the electrolyte membrane and a proton conductive fluorine-based solid electrolyte. Yes. The size of the catalyst layer was a circle having a diameter of 11 mm. The rubber hardness used for the packing was about 50%, and a thickness of 200 μm was cut into a desired dimension and used. The carbon porous body 201 and the carbon porous body 205 sandwiched from both sides of the membrane electrode assembly had a thickness of 300 to 440 μm. A layer containing water-repellent conductive carbon is formed in advance on the surfaces of the carbon porous body 201 and the carbon porous body 205, and the water-repellent conductive carbon-containing layer and the catalyst layer are electrically connected. Arranged to connect to.

A power supply element having a slit portion at 1 mm intervals, a current collector 200 serving as an anode electrode, and a push plate 212 made of stainless steel plated with gold were used to fasten a power generation element with bolts 208 in the same manner as in the example. This stainless steel pressing plate 212 has a breathable hole 213 and is connected to lead to take out electrons. Further, the stainless steel pressing plate 212 and the bolt portion are insulated. At this time, the bolt 208 arranged around the power generation element was tightened with a torque driver (Tohichi, RTD120CN type) with a torque of 50 CNm or less. Then, cells having t ₁ = 0.2 mm, t ₂ = 1.0 mm, and t ₂ / t ₁ = 5 [−] were created as the parameters described above. The cell created in this way is referred to as Example 4. FIG. 14 schematically shows an embodiment of the present invention. At this time, hydrogen having a purity of 99.99% and a temperature of 24 ° C. was supplied to the cell at a flow rate of 10 cc / min · cm ² per unit area so that the gas pressure at the outlet was approximately atmospheric pressure. The cathode side was exposed to an atmosphere of about 40% RH and 25 ° C. At this time, an electronic load device (KFM2030, manufactured by Kikusui Electronics Co., Ltd.) was used, and the load on the cell was changed between 0 A / cm ^{2 and} 1.0 A / cm ² , and the voltage at that time was recorded with a recorder. . FIG. 15 shows current / voltage characteristics of the fuel cells manufactured in Example 1 and the conventional example. From this, it is clear that at any current, the voltage of the fuel cell of Example 1 is higher than the voltage of the fuel cell of the conventional example, and the performance is excellent.

  The present invention provides an electrode configuration that can be used as an electrode for a solid oxide fuel cell to facilitate gas diffusion and discharge of generated water in the power generation unit, suppress MEA damage, and suppress moisture shortage at the anode electrode. And can be used for fuel cells for various portable electronic devices.

The figure which showed typically the metal porous body in embodiment of this invention. The figure which showed typically the textile fabric comprised by the weft formed by the carbon fiber in embodiment of this invention, and a warp. The figure which showed typically the mode of formation of the contact layer in embodiment of this invention. Sectional drawing at the time of observing a part of electric power generation element of the cathode pole in embodiment of this invention from the side. Sectional drawing at the time of observing a part of electric power generation element by the side of a cathode pole in embodiment of this invention from the side. The bird's-eye view which observed the porous body made from carbon, and the porous metal body from the outside. Sectional drawing which showed typically the electric power generation element in embodiment of this invention. The graph which measured the output performance of the fuel cell of this invention. The graph which measured and compared the output performance of the fuel cell of this invention. The figure which showed embodiment of this invention typically. The figure which showed embodiment of this invention typically. The figure which showed embodiment of this invention typically. The figure which showed the maximum output density regarding Example 1, 4, 5. FIG. The figure which showed the form of the prior art example typically. FIG. 3 is a current / voltage characteristic diagram related to Example 1 and a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Metal porous body 101 Pore diameter 102 Weft yarn 103 of long fiber yarns in a bundled state Warp yarn 104 in a bundled state of long fiber yarns 104 Unit void 105 Load on metal porous material 106 Stress on carbon porous material 107 Proton conductive resin Electrolyte layer 108 Catalyst layer 109 Water-repellent carbon layer 110 Holding portion 111 Carbon porous body 112 Area of carbon porous body 111 Area of metal porous body 100 114 Power generation element 115 Lead 116 Bolt 117 Anode collection Electrical section 118 Fuel supply section 119 Anode pole housing t2 Metal porous body thickness t1 Carbon porous body thickness 200 Fuel supply section and anode current collector 201 Carbon porous body 202 Anode catalyst layer 203 Proton conductivity Electrolyte layer 204 made of the above resin Cathode catalyst layer 205 Carbon porous body 206 Metal porous body 207 Presser plate 208 Bolt 209 Presser plate 210 Metal porous body 211 Metal porous body 212 Presser plate 213 Presser plate opening 301 Performance of fuel cell fabricated in Example 5 302 Conventional example Of a fuel cell fabricated using

Claims (18)

An anode having a catalyst layer on one side of an electrolyte layer made of proton conductive resin and a cathode having a catalyst layer on the other side, opposite to the surfaces of the anode and the cathode in contact with the electrolyte layer In a solid polymer electrolyte fuel cell having a current collector layer on each side surface,
The current collector layer is made of a gas-permeable metal porous body, and a carbon porous body is formed on a surface where the metal porous body and the anode electrode are in contact with each other or a surface where the metal porous body and the cathode electrode are in contact with each other. A polymer electrolyte fuel cell.   2. The polymer electrolyte fuel cell according to claim 1, further comprising a contact layer made of carbon fibers of the porous body and long fiber yarns at a portion where the metal porous body and the carbon porous body are in contact with each other.   3. The polymer electrolyte fuel cell according to claim 1, wherein the carbon porous body is a woven fabric composed of wefts and warps formed by collecting carbon fibers of long fiber yarns.   The polymer electrolyte fuel cell according to any one of claims 1 to 3, wherein the metal porous is a foam metal.   The polymer electrolyte fuel cell according to any one of claims 2 to 4, wherein the metal porous body is constituted by combining two or more kinds of metal porous bodies having different pore diameters.   The polymer electrolyte fuel cell according to any one of claims 2 to 5, wherein the metal porous body is at least a foam metal body and an expanded metal.   The polymer electrolyte fuel cell according to any one of claims 2 to 6, wherein the metal porous body is at least a foam metal body and a punching metal.   The polymer electrolyte fuel cell according to any one of claims 2 to 7, wherein a part of the surface of the metallic porous body is subjected to gold plating.   The polymer electrolyte fuel cell according to any one of claims 2 to 8, wherein the carbon fiber constituting the long fiber yarn is an aggregate of carbon fibers having a fiber diameter of 1 to 20 µm.   The polymer electrolyte fuel cell according to any one of claims 1 to 9, wherein an average pore diameter of the foam metal is 0.3 mm or more and 3.2 mm or less.   The polymer electrolyte fuel cell according to any one of claims 1 to 10, wherein the porosity per volume of the foam metal is 80% to 98%.   The polymer electrolyte fuel cell according to any one of claims 1 to 11, wherein the metal porous body has a surface subjected to a water repellent treatment.   The polymer electrolyte fuel cell according to any one of claims 1 to 12, wherein a part of the oxide film on the surface of the porous metal body is removed. The carbon-made porous body thickness of t ₁ of, according to the metal when the porous material thickness of the set to t _2, any one of claims 1 to 13 t ₂ / t ₁ is equal to or less than 10 Polymer electrolyte fuel cell. The thickness of the carbon porous body is t ₁ , and the thickness of the metal porous body is t ₂ , t ₂ / t ₁ is 10 or less. 15. Polymer electrolyte fuel cell. The area of the porous body made of carbon is S ₁ , and the area of the porous metal body is S ₂ , S ₂ / S ₁ is 1 or more and 2 or less. The polymer electrolyte fuel cell as described.   17. The solid polymer electrolyte fuel cell according to claim 1, wherein the fuel of the anode electrode is hydrogen gas.   18. The solid polymer electrolyte fuel cell according to claim 1, wherein the fuel of the anode electrode is hydrogen gas obtained from boron hydride.

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