JP2009259736A - Fuel cell electric power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power generation system having high output stability.
A fuel cell comprising an electrode / electrolyte integrated body having a positive electrode that reduces oxygen, a negative electrode that oxidizes fuel, and a solid polymer electrolyte membrane disposed between the positive electrode and the negative electrode, and A fuel cell power generation system comprising a humidifier that humidifies fuel supplied to the negative electrode, wherein the humidifier supplies the fuel to the negative electrode in a state of containing mist-like moisture. This problem is solved by a fuel cell power generation system.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell power generation system having a fuel cell and a humidifier that supplies fuel in a humidified state.

  In recent years, with the widespread use of cordless devices such as personal computers and mobile phones, there has been a demand for further miniaturization and higher capacity of batteries as power sources. Currently, lithium ion secondary batteries have been put into practical use as batteries that have high energy density and can be reduced in size and weight, and demand for portable power sources is increasing. However, this lithium ion secondary battery has a problem that it cannot guarantee a sufficient continuous use time for some cordless devices.

  In order to solve the above problems, for example, development of fuel cells such as polymer electrolyte fuel cells (PEFC) is underway. The fuel cell can be used continuously if fuel and oxygen are supplied.

  The PEFC is composed of a positive electrode (cathode) that reduces oxygen in the air, a negative electrode (anode) that oxidizes hydrogen, and a solid polymer electrolyte membrane disposed between the positive electrode and the negative electrode. -It has electrolyte integrated substance (MEA: Mebrane electrode assembly), and attracts attention as a battery whose energy density is higher than a lithium ion secondary battery.

  By the way, in the fuel cell, when the power generation is continued, the moisture in the MEA is reduced and dried. When the solid polymer electrolyte membrane of the MEA is dried, the ionic conductivity is lowered. Therefore, the fuel cell in such a state cannot sufficiently take out the output.

  Techniques for solving these problems have also been proposed. For example, Patent Document 1 holds 75 to 78 ° C. warm water, holds a fuel gas humidification tank for humidifying the fuel gas by passing the fuel gas through the warm water, and holds warm water in the warm water. A fuel cell comprising an oxidant humidification tank for humidifying an oxidant such as oxygen is disclosed. As in the technique described in Patent Document 1, by humidifying the fuel gas and oxidant (oxygen) supplied to the MEA of the fuel cell, it is possible to prevent the MEA from being dried due to power generation and to stabilize the output. it can.

  Patent Document 2 describes a hydrogen generating material for producing hydrogen suitable for a fuel for a fuel cell, and a fuel cell using this as a hydrogen source. Since the hydrogen generating material includes a metal material that generates hydrogen by reacting with water, the hydrogen obtained using the hydrogen generating material includes a part of the water supplied for the hydrogen generating reaction. It is out. Therefore, in the fuel cell using hydrogen obtained from the hydrogen generating material as a fuel, moisture is continuously supplied to the MEA by supplying hydrogen, so that drying of the MEA accompanying power generation is suppressed.

JP 2003-217620 A JP 2006-306700 A

  As described above, according to the technique disclosed in Patent Document 1, although a certain effect is recognized in the stabilization of the output of the fuel cell, since the bubbling is performed in water heated to 70 ° C. or higher, Since the temperature of the gas rises, it is difficult to increase the relative humidity, and the evaporation of moisture from the MEA cannot always be suppressed.

  On the other hand, according to the technique described in Patent Document 2, moisture can be supplied to the MEA in the fuel cell without separately providing a member for preventing the MEA from drying. However, the reaction for generating hydrogen is an exothermic reaction, and depending on the state of the reaction, the temperature of the hydrogen gas to be taken out may be 70 ° C. or higher. Similar to the technique described in Patent Document 1, by the drying of MEA In some cases, output reduction could not be suppressed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell power generation system having high output stability.

  The fuel cell power generation system of the present invention that has achieved the above object includes a positive electrode that reduces oxygen, a negative electrode that oxidizes fuel, and a solid polymer electrolyte membrane disposed between the positive electrode and the negative electrode A fuel cell power generation system having a fuel cell including an electrode / electrolyte integrated body and a humidifying device for humidifying fuel supplied to the negative electrode, the humidifying device containing mist-like moisture. In this state, the negative electrode is supplied to the negative electrode.

  According to the present invention, a fuel cell power generation system having high output stability can be provided.

  First, details of the fuel cell power generation system of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a fuel cell and a humidifier constituting the fuel cell power generation system of the present invention. Although FIG. 1 is a cross-sectional view, in order to facilitate understanding of each component, some components are not hatched to indicate a cross section.

  In the fuel cell of FIG. 1, an electrode in which a positive electrode composed of a positive electrode diffusion layer 13 and a positive electrode catalyst layer 14, a solid polymer electrolyte membrane 15, and a negative electrode composed of a negative electrode diffusion layer 17 and a negative electrode catalyst layer 16 are sequentially laminated. -It has three electrolyte integrated objects (MEA) 100, and these MEAs are arrange | positioned planarly.

  On the positive electrode side of each MEA 100, positive electrode current collecting plates 5 and 6, a positive electrode insulating plate 3, and a positive electrode panel plate 1 are sequentially arranged. Further, negative electrode current collector plates 7 and 8, negative electrode insulating plate 4, and negative electrode panel plate 2 are sequentially arranged on the negative electrode side of each MEA 100.

  All the MEAs 100 are sandwiched and integrated by the positive electrode panel plate 1 and the negative electrode panel plate 2. Although not clearly shown in FIG. 1, adjacent MEAs 100 are connected in series by electrical connection between the positive current collector plates 5 and 6 and the negative current collector plates 7 and 8.

  The positive electrode current collecting plates 5 and 6, the positive electrode insulating plate 3 and the positive electrode panel plate 1 are provided with a plurality of oxygen introduction holes for introducing oxygen outside the fuel cell into the positive electrode as air. Then, from the outer surface of the positive electrode panel plate 1 to the positive electrode diffusion layer 13 of the MEA 100 by the oxygen introduction holes of the positive electrode current collecting plates 5 and 6, the oxygen introduction hole of the positive electrode insulating plate 3, and the oxygen introduction hole of the positive electrode panel plate 1. A plurality of reaching openings 11 are formed, and oxygen (air) outside the fuel cell is supplied from the openings 11 to the positive electrode diffusion layer 13 by diffusion.

  In the fuel cell of FIG. 1, the negative electrode current collector plates 7 and 8, the negative electrode insulating plate 4, and the negative electrode panel plate 2 are provided with a plurality of fuel introduction holes for introducing fuel from the humidifier 10 to the negative electrode. . Then, the negative electrode diffusion layer of the MEA 100 from the humidifying device 10 side surface of the negative electrode panel plate 2 by the fuel introduction holes of the negative electrode current collecting plates 7 and 8, the fuel introduction hole of the negative electrode insulating plate 4 and the fuel introduction hole of the negative electrode panel plate 2. A plurality of openings 12 reaching 17 are formed, and the fuel in the humidifier 10 is supplied to the anode diffusion layer 17 from these openings 12.

  In the fuel cell of FIG. 1, the positive electrode panel plate 1 and the negative electrode panel plate 2 (and the humidifying device 10) are fixed by a fixing portion arranged with a gap therebetween, and in the fixing portion, a bolt 18 and a nut 19 are fixed. It is fixed by. In FIG. 1, 9a and 9b are seals.

  Although FIG. 1 shows a fuel cell in which three MEAs 100 are arranged in a plane, the number of MEAs is not particularly limited. Moreover, when arrange | positioning several MEA, you may arrange | position planarly and may arrange | position so that it may laminate | stack up and down.

  FIG. 2 shows a schematic diagram of a humidifier 10 provided adjacent to the negative electrode of the fuel cell of FIG. In FIG. 2, (a) is a plan view. (B) is a cross-sectional view taken along line AA in (a), and (c) is a cross-sectional view taken along line BB in (a). In these cross-sectional views, the arrangement of the fixing portion 20 (screw hole) is shown. Since it is indicated by a dotted line, in order to facilitate understanding of this arrangement, a diagonal line indicating a cross section is omitted. The humidifier 10 is provided to allow the fuel supplied to the negative electrode of the MEA to contain mist-like moisture and supply the fuel to the negative electrode of the MEA in that state.

  The humidifier according to the fuel cell power generation system of the present invention can be constituted by, for example, a tank in which humidifying water is stored. In this case, by adjusting the amount of water so that the fuel circulates in the water for humidification, the mist-like moisture generated by the bubbles of the fuel repelling (that is, not in a completely vaporized state but in a mist state) Water in the form of fine particles) can be contained in the fuel, and by providing the tank adjacent to the MEA negative electrode, the fuel is supplied to the negative electrode while containing mist-like water. be able to. Thereby, the fuel containing water in a supersaturated state can be supplied to the negative electrode, and the lack of humidification is eliminated.

  The humidification tank 10 shown in FIG. 2 has a supply port 22 for introducing fuel and humidifying water into the tank interior 21 and an exhaust port 23 for discharging excess fuel and water from the tank interior 21 to the outside of the tank. The supply port 22 and the discharge port 23 can store water for humidifying the fuel in the tank interior 21. Reference numeral 20 denotes a fixing portion (a screw hole through which a bolt is passed) for fixing the positive electrode panel plate and the negative electrode panel plate, and is provided in accordance with the position of the fixing portion between the positive electrode panel plate and the negative electrode panel plate.

  More specifically, in the humidifying tank 10 shown in FIG. 2, the supply port 22 and the discharge port 23 are arranged so that the supply port 22 is at the bottom when the fuel cell is used (that is, in the drawing). Install the fuel cell so that the upper side is also the upper side when the fuel cell is used). In the fuel cell having the humidification tank 10 shown in FIG. 2, this water is stored in the tank interior 21 of the humidification tank 10 by supplying water from the supply port 22. When fuel is supplied to the humidification tank 10 in this state, the supplied fuel is humidified by water stored in the humidification tank 10. In addition, although a fuel cell heat | fever-generates with electric power generation, the effect which cools MEA can also be anticipated by providing a humidification tank adjacent to the negative electrode of MEA.

  In addition, as described above, the supply port 22 and the discharge port 23 in the humidification tank 10 are arranged so that the supply port 22 is at the bottom when the fuel cell is used, so that the water stored in the humidification tank 10 is stored. The amount of can be controlled. That is, the water supplied from the supply port 22 accumulates in the lower side of the tank inside 21 in the figure due to gravity, and when the water level reaches the position of the discharge port 23, the water is discharged from the discharge port 23 to the outside of the humidification tank. The Therefore, by continuously or intermittently supplying water from the supply port 22, it is possible to prevent the water inside the tank 21 from being reduced below a certain amount, and at least water from the supply port 22. By keeping the supply speed lower than the speed at which water can be discharged from the discharge port 23, the water level in the tank 21 can be kept below the position of the discharge port 23.

  If the water inside the tank 21 is increased, the water may block the surface of the negative electrode and hinder the fuel supply to the negative electrode. However, as shown in FIG. 2, the humidification tank 10 has a mechanism capable of controlling the amount of stored water, so that the occurrence of these problems can be avoided.

  Regarding the arrangement of the supply port 22 and the discharge port 23 in the humidification tank 10, the supply speed of water from the supply port 22 and the supply timing, the stored water does not hinder the fuel supply to the negative electrode, and What is necessary is just to set suitably in the range which can humidify fuel satisfactorily. For example, in order to reduce the influence of water on the negative electrode as much as possible, the discharge port 23 can be arranged so that the negative electrode of the MEA is located above the discharge port 23 in FIG. On the other hand, in order to reduce the size of the fuel cell as much as possible, the MEA negative electrode is positioned below the discharge port 23 in FIG. 2 and the fuel humidification is not insufficient as much as possible. The discharge port 23 can be arranged so that the portion in contact with water on the negative electrode surface becomes small.

  In addition, although the humidification tank 10 (fuel tank part 10 which concerns on the fuel cell of FIG. 1) shown in FIG. 2 is an independent thing, you may make it the structure which integrated the humidification tank with the negative electrode panel plate, for example.

  The material of the humidification tank 10 should be free from corrosion and form change by the fuel. Specifically, for example, glass epoxy resin; polycarbonate resin, acrylic resin, polyimide resin, fluororesin [polytetrafluoroethylene (PTFE) etc.] plastic; metals such as stainless steel, nickel, copper, graphite, titanium; Is preferred.

  FIG. 3 is a schematic plan view of the positive electrode panel plate 1. The positive electrode panel plate 1 is provided with an oxygen introduction hole 11a in accordance with the position of the positive electrode diffusion layer of each MEA, and the oxygen introduction hole 11a is formed by the oxygen introduction hole of the positive electrode insulating plate and the oxygen introduction hole of the positive electrode current collecting plate. The opening is formed together with the hole. 20, 20 a, 20 b, 20 c, 20 d, and 20 e are screw holes through which bolts for fixing the positive electrode panel plate 1 and the negative electrode panel plate are passed, and fixing portions for fixing the positive electrode panel plate 1 and the negative electrode panel plate It becomes.

  The positive electrode panel plate 1 is preferably made of metal from the viewpoint of suppressing the occurrence of deflection when the MEA is suppressed. Further, from the viewpoint of reducing the deflection at the time of suppressing the MEA, the metal constituting the positive electrode panel plate 1 preferably has a Young's modulus required by a bending test of 50000 MPa or more. Specific examples of the metal include carbon steel, alloy steel, stainless steel, superalloy, aluminum alloy, magnesium alloy, titanium alloy, and nickel alloy. In addition, the Young's modulus calculated | required by the bending test as used in this specification is a value calculated | required by measuring the amount of deflection | deviation especially produced when a load was applied to the center part of the plate-shaped sample which supported both ends.

  Moreover, it is preferable that the thickness of the positive electrode panel plate 1 is 0.5-3.5 mm. If the positive electrode panel plate 1 is too thin, the deflection when the MEA is suppressed increases, and the uniformity of the MEA suppression may be impaired. On the other hand, if the positive electrode panel plate 1 is too thick, the total thickness of the positive electrode panel plate 1, the positive electrode insulating plate, and the positive electrode current collector plate increases, and the amount of oxygen supplied to the positive electrode may decrease.

  In addition, the thing of the same structure (shape and material) as the said positive electrode panel plate can be used for a negative electrode panel plate.

  FIG. 4 is a schematic plan view of the positive electrode current collecting plates 5 and 6. In FIG. 4, the positive electrode current collecting plate 5 in FIG. 4A is a current collecting plate (positive electrode current collecting plate) to be arranged on the positive electrode side of the leftmost MEA 100 of the fuel cell in FIG. A positive electrode current collecting terminal portion 24 for electrical connection is provided. Also, in FIG. 3, the positive electrode current collecting plate 6 of FIG. 3B is a current collecting plate for disposing on the positive electrode side of the MEA 100 at the center and the right side of the fuel cell of FIG. A positive electrode series connection tab 25 is provided at the position. The positive electrode series connection tab 25 is brought into contact with a negative electrode current collecting plate disposed on the negative electrode side of the adjacent MEA (for example, brought into contact with a negative electrode series connection tab provided on the negative electrode current collector plate), etc. By connecting each other, each MEA is connected in series.

  Further, the positive electrode current collecting plates 5 and 6 of FIG. 4 are provided with oxygen introducing holes 11b in accordance with the positions of the positive electrode diffusion layers of the MEA and the oxygen introducing holes of the positive electrode panel plate. The introduction hole 11b forms the opening together with the oxygen introduction hole of the positive electrode panel plate and the oxygen introduction hole of the positive electrode insulating plate. Furthermore, the positive electrode current collecting plates 5 and 6 in FIG. 4 are provided with a fixing portion 20 (screw hole) in accordance with the position of the fixing portion (screw hole) of the positive electrode panel plate.

  The positive current collecting terminal portion 24 in the positive current collecting plate 5 is not particularly limited. For example, as shown in FIG. 4, a hole for connecting an external terminal drawn from a device connected to the fuel cell or the like Is mentioned.

  Although only one positive electrode series connection tab 25 in the positive electrode current collecting plate 6 may be provided at a position corresponding to the outer peripheral portion of the fuel cell, two tabs 25 are provided at a position corresponding to the outer peripheral portion of the fuel cell as shown in FIG. It is preferable. Since the resistance between the current collecting plates is reduced by connecting from two tabs rather than connecting from one positive electrode series connection tab, the output of the battery can be further improved.

  The thickness of the positive electrode current collecting plates 5 and 6 is preferably 0.2 to 3.2 mm. If the positive electrode current collecting plates 5 and 6 are too thin, the electronic resistance may increase and the output of the battery may decrease. On the other hand, if the positive current collecting plates 5 and 6 are too thick, the total thickness of the positive electrode panel plate, the positive electrode insulating plate and the positive current collecting plate is increased, and the supply amount of oxygen to the positive electrode may be reduced.

  Note that the negative electrode current collecting plate (the negative electrode end current collecting plate 7 and the negative electrode current collecting plate 8 in FIG. 1) includes the positive electrode current collecting plate (the positive electrode end current collecting plate 5 shown in FIG. 4 and FIG. 5). The same configuration (shape) as the positive electrode current collecting plate 6) shown in FIG.

  In the fuel cell constituting the fuel cell power generation system of the present invention, the positive electrode current collecting plate and the negative electrode current collecting plate are each made of a metal base material having a good conductivity metal and a corrosion-resistant conductive material layer covering the base material. It is preferable to use a configured material, and at least one of the positive electrode current collecting plate and the negative electrode current collecting plate, the metal base material is constituted by two layers parallel or substantially parallel to the electrode surface of the MEA, and Of the two layers, it is more preferable to use a layer in which the electrode side layer is made of a corrosion-resistant metal and the other layer (the layer on the side opposite to the electrode) is made of the highly conductive metal. preferable.

  FIG. 5 shows a part of a cross section in the thickness direction of the positive electrode current collecting plates 5 and 6 constituted by the base material having the two-layer structure and the corrosion-resistant conductive material layer. The positive electrode current collecting plates 5 and 6 shown in FIG. 5 include a metal base 51 and a corrosion-resistant conductive material layer 52 that covers the base 51. The metal base 51 is composed of two layers 51a and 51b that are parallel or substantially parallel to the MEA electrode surface (in the case of a positive electrode current collector plate), of which the electrode side (positive electrode side) ) Layer 51a is made of a corrosion-resistant metal, and the other layer 51b is made of a highly conductive metal.

  By using the positive current collector plate made of the above-mentioned material, the corrosion of the positive current collector plate due to contact with the positive electrode is suppressed while improving the electrical connection between the adjacent MEAs, so that the Both good output characteristics and long life can be achieved. Moreover, if it is a positive electrode current collection plate comprised with the said raw material, it is cheap, but it is corrosion-resistant to the highly conductive metal which comprises the layer 51b on the opposite side to the positive electrode side which mainly plays the original role of a current collection plate. Even if Cu, which is inferior, is used, its corrosion can be suppressed, so that the cost of the fuel cell can be reduced and its productivity can be increased.

  In addition, only one of the positive electrode current collecting plate and the negative electrode current collecting plate may be a current collecting plate composed of the base material having the two-layer structure and the corrosion-resistant conductive material layer as shown in FIG. However, since the positive electrode current collector plate is required to have higher corrosion resistance than the negative electrode current collector plate, at least the positive electrode current collector plate and the base material having the two-layer structure are used. More preferably, the current collecting plate is composed of a corrosion-resistant conductive material layer, and both the positive electrode current collecting plate and the negative electrode current collecting plate are composed of the base material having the two-layer structure and the corrosion-resistant conductive material layer. The electric plate is particularly preferable, and in this case, the above-described effect by using the current collecting plate having such a configuration is more excellent.

  That is, the negative electrode current collecting plate is composed of a metal base material having a highly conductive metal and a corrosion-resistant conductive material layer covering the base material, and the metal base material is an electrode surface of the MEA. Of the two layers, the electrode (negative electrode) side layer is made of a corrosion-resistant metal, and the other layer is made of the highly conductive metal. Even when using one, the electrical connection between adjacent MEAs is improved, and corrosion of the negative electrode current collector plate due to contact with the electrode is suppressed to ensure better output characteristics and longer life in the fuel cell. Both can be achieved. In addition, if the negative electrode current collector plate is made of the above-described material, the highly conductive metal constituting the layer on the opposite side of the positive electrode, which mainly plays the original role of the current collector plate, is inexpensive and has corrosion resistance. Even if inferior Cu or the like is used, the corrosion can be suppressed, so that the cost of the fuel cell can be reduced and the productivity thereof can be increased.

  Note that the positive electrode current collecting plate and the negative electrode current collecting plate are preferably made of a material having good electron conductivity and high acid resistance. In the case of not using a layered base material and a corrosion-resistant conductive material layer covering the base material, a metal base material having a good conductivity metal (for example, a good conductivity metal) It is preferable to use a substrate composed of a single layer structure base material) and a corrosion-resistant conductive material layer covering the base material. Good.

  As the corrosion-resistant conductive material constituting the layer covering the metal base material related to the positive electrode current collector plate and the negative electrode current collector plate, for example, selected from the group consisting of Au, Pt, Pd and alloys mainly composed of those elements At least one metal; a mixture of carbon and a thermosetting resin; and the like. When the corrosion-resistant conductive material is the alloy, the content of Au, Pt or Pd in the alloy is preferably 80% by mass or more, for example. Moreover, as an alloy component in the said alloy, iridium etc. are mentioned, for example (namely, as an alloy, an alloy of Pt: 80 mass% -Ir: 20 mass% etc. is mentioned), for example. Furthermore, examples of the thermosetting resin in the mixture of the corrosion-resistant conductive material of carbon and thermosetting resin include polyamideimide.

  The thickness of the corrosion-resistant conductive material layer is preferably 0.1 to 50 μm, and it is recommended that the thickness of the current collecting plate be set to the above-mentioned preferable value while the thickness of the corrosion-resistant conductive material layer is set in this way. If the corrosion-resistant conductive material layer is too thin, the corrosion-inhibiting effect of the current collecting plate due to the formation of the corrosion-resistant conductive material layer may be reduced. Moreover, if the corrosion-resistant conductive material layer is too thick, the metal base material having a good conductivity metal becomes thin, and depending on the selection of the corrosion-resistant conductive material, the electronic resistance increases or the cost of the current collecting plate increases. There are things to do.

  In addition, examples of the highly conductive metal in the metal base material related to the positive electrode current collecting plate and the negative electrode current collecting plate include Ni, Ni alloy, Cu, or Cu alloy, and these may be used alone. In addition, two or more kinds may be used in combination. In the case of a Ni alloy or a Cu alloy, the content of Ni or Cu in the alloy is preferably 95% by mass or more, for example. Moreover, as an alloy component in Ni alloy or Cu alloy, beryllium etc. are mentioned, for example (namely, as an alloy, Cu: 98 mass% -Be: 2 mass% alloy, Ni: 98 mass% -Be: 2% by mass of alloy). When the negative electrode current collecting plate or the positive electrode current collecting plate has the base material having the two-layer structure, the layer on the side opposite to the electrode can be made of the exemplified conductive metal.

  When the positive electrode current collecting plate or the negative electrode current collecting plate has the base material having the two-layer structure, as the corrosion-resistant metal constituting the electrode side layer, for example, stainless steel, Ti, or an alloy mainly composed of Ti is used. These may be used alone or in combination of two or more. In addition, in the case of the said alloy, it is preferable that content of Ti in an alloy is 90 mass% or more, for example. Examples of the alloy component in the alloy include Pd and Ta (that is, the alloy includes Ti: 99.85% by mass—Pd: 0.15% by mass, Ti: 95% by mass). -Ta: 5 mass% alloy etc. are mentioned).

  The thickness of the metal base material having a highly conductive metal related to the positive electrode current collecting plate and the negative electrode current collecting plate is the preferred thickness of the positive electrode current collecting plate and the negative electrode current collecting plate, and the preferred thickness of the corrosion-resistant conductive material layer. It is preferable to set while satisfying.

  Moreover, when the positive electrode current collecting plate or the negative electrode current collecting plate has the base material having the two-layer structure, the ratio of the thickness of the electrode side layer to the other layer in the base material is the electrode side layer. The thickness of the other layer is preferably 0.2 to 3 when the thickness is 1. If the other layer is too thin relative to the thickness of the electrode side layer, the electronic resistance of the current collector plate may increase. If the other layer is too thick relative to the thickness of the electrode side layer, A layer becomes thin and the corrosion inhibitory effect of the current collection plate by providing this may become small.

  FIG. 6 shows a schematic diagram of the positive electrode insulating plate 3. In FIG. 6, (a) is a plan view. Further, (b) is a cross-sectional view taken along the line AA in (a), but the arrangement of the fixing portion 20 (screw hole) is indicated by a dotted line, and is a cross section for easy understanding of this arrangement. The hatched lines indicating that are omitted. The positive electrode insulating plate 3 is disposed between the metal positive electrode panel plate and the positive electrode current collecting plate, and plays a role of insulating between these plates.

  The positive electrode insulating plate 3 is provided with an oxygen introduction hole 11c in accordance with the position of the positive electrode diffusion layer of each MEA and in accordance with the position of the oxygen introduction hole of the positive electrode panel plate and the oxygen introduction hole of the positive electrode current collector plate, The oxygen introduction hole 11c forms the opening together with the oxygen introduction hole of the positive electrode panel plate and the oxygen introduction hole of the positive electrode current collecting plate. Further, the positive insulating plate 3 is provided with a fixing portion 20 (screw hole) in accordance with the position of the fixing portion (screw hole) of the positive electrode panel plate and the positive electrode current collecting plate.

  The positive electrode insulating plate 3 is preferably provided with a recess 26 for accommodating the positive electrode current collecting plate. Since the step can be eliminated when the positive electrode insulating plate 3 and the positive electrode current collecting plate are stacked by the concave portion 26, it is possible to suppress the occurrence of gas leakage due to the step and the unevenness of the MEA suppression.

  The material of the positive electrode insulating plate 3 is not particularly limited as long as it is an electronic insulating material. For example, a plastic such as a glass epoxy resin, a polycarbonate resin, an acrylic resin, a polyimide resin, or a fluororesin (PTFE) is suitable.

  Of the positive electrode insulating plate 3, the thickness of the recess 26 in which the positive electrode current collecting plate is accommodated is preferably 0.3 to 3.3 mm. If the recess 26 is too thin, there is a risk of cracking due to insufficient strength. If the recess 26 is too thick, the total thickness of the positive electrode panel plate, the positive electrode insulating plate, and the positive electrode current collector plate increases, and the amount of oxygen supplied to the positive electrode may decrease.

  In addition, the thing of the same structure (shape and material) as the said positive electrode insulating plate can be used for a negative electrode insulating plate.

  In the fuel cell constituting the fuel cell power generation system of the present invention, the total thickness of the positive electrode panel plate, the positive electrode insulating plate, and the positive electrode current collecting plate is preferably 1 mm or more. In order to reduce the internal resistance of the fuel cell, it is preferable to suppress the MEA with a certain degree of uniformity by the positive electrode panel plate and the negative electrode panel plate. For example, as shown in FIG. 1, in the case where the positive electrode panel plate 1 and the negative electrode panel plate 2 are fixed by using bolts 18 and nuts 19 or the like at fixed portions arranged at intervals, the positive electrode panel plate 1 If the total thickness of the positive electrode insulating plate 3 and the positive electrode current collecting plates 5 and 6 is too small, the MEA 100 may be bent when the MEA 100 is suppressed, and the uniformity of the MEA 100 may be impaired.

  On the other hand, if the total thickness of the positive electrode panel plate 1, the positive electrode insulating plate 3, and the positive electrode current collecting plates 5 and 6 is too large, the amount of oxygen supplied from the opening 11 to the positive electrode diffusion layer 13 tends to decrease. The total thickness is preferably 4 mm or less.

  The total thickness of the negative electrode panel plate 2, the negative electrode insulating plate 4, and the negative electrode current collector plates 7 and 8 is the same as that of the positive electrode panel plate 1, the positive electrode insulating plate 3 and the positive electrode current collector plates 5 and 6. Is preferably 1 mm or more from the viewpoint of increasing the uniformity of the suppression of the battery and lowering the internal resistance of the battery, and is further 4 mm or less from the viewpoint of increasing the amount of fuel supplied from the opening 12 to the negative electrode diffusion layer 17. It is preferable.

  FIG. 7 shows a schematic diagram of the MEA 100. In FIG. 7, (a) is a plan view and (b) is a cross-sectional view of (a). In (b), in order to facilitate understanding of each component, hatched lines indicating a cross-section Is omitted.

  The MEA 100 includes a positive electrode catalyst layer 14 that reduces oxygen and a negative electrode catalyst layer 16 that oxidizes hydrogen. Further, a solid polymer electrolyte membrane 15 is interposed between the positive electrode catalyst layer 14 and the negative electrode catalyst layer 16. I have. Further, the positive electrode diffusion layer 13 is laminated on the surface opposite to the surface of the positive electrode catalyst layer 14 on the solid polymer electrolyte membrane 15 side, and on the surface opposite to the surface of the negative electrode catalyst layer 16 on the solid polymer electrolyte membrane 15 side. The negative electrode diffusion layer 17 is laminated.

  The solid polymer electrolyte membrane 15 preferably has a larger area than the electrodes (positive electrode and negative electrode) in plan view. This is because sealing is performed using a portion protruding from the electrode. If the sealing is not performed, the fuel and oxygen in the air are mixed, so that the function of the fuel cell may not be performed. The width of the portion of the solid polymer electrolyte membrane 15 that is larger than the electrode is preferably 1 mm or more from the viewpoint of securing a sufficient width for sealing. If the width of the portion of the solid polymer electrolyte membrane 15 that is larger than the electrode is made too large, the ratio of the area to be sealed in the limited area of the solid polymer electrolyte membrane 15 becomes large. The above-mentioned width is preferably 5 mm or less.

  The width of the electrode is preferably 3 to 35 mm. This is derived from the relationship between the preferred size of the solid polymer electrolyte membrane 15 and the preferred distance between the fixing parts described later. There is no restriction | limiting in particular in the length of an electrode, It can set in view of the output requested | required of a fuel cell.

  Further, the MEA 100 may have a structure in which the solid polymer electrolyte membrane 15 is shared by a plurality of MEAs 100 as shown in FIG. 8A is a plan view, and FIG. 8B is a cross-sectional view of FIG. 8A. Also in FIG. 8B, in order to facilitate understanding of each component, the cross-section is shown. The diagonal lines are omitted.

  In FIG. 8, reference numeral 27 denotes a series connection tab contact area. In this portion, the positive electrode series connection tab of the positive electrode current collector plate and the negative electrode series connection tab of the negative electrode current collector plate are electrically contacted, and each MEA in the MEA unit is brought into contact. Can be connected in series. Further, the MEA 100 in FIG. 8 is also provided with a fixing portion 20 (screw hole).

  The positive electrode diffusion layer 13 and the negative electrode diffusion layer 17 are made of a porous electron conductive material or the like, for example, a porous carbon sheet subjected to a water repellent treatment. In addition, on the catalyst layer side of the positive electrode diffusion layer 13 and the negative electrode diffusion layer 17, a carbon powder paste containing fluororesin particles (such as PTFE resin particles) is provided for the purpose of further improving water repellency and improving contact with the catalyst layer. It may be applied.

  The positive electrode catalyst layer 14 has a function of reducing oxygen diffused through the positive electrode diffusion layer 13. The positive electrode catalyst layer 14 contains, for example, a carbon powder carrying a catalyst (catalyst-carrying carbon powder) and a proton conductive material. Moreover, you may further contain the resin binder as needed.

  The catalyst contained in the positive electrode catalyst layer 14 is not particularly limited as long as it can reduce oxygen, and examples thereof include platinum fine particles. The catalyst may be fine particles composed of an alloy of platinum and at least one metal element selected from the group consisting of iron, nickel, cobalt, tin, ruthenium and gold.

As the carbon powder as the catalyst carrier, for example, carbon black having a BET specific surface area of 10 to 2000 m ² / g and an average particle diameter of 20 to 100 nm is used. The catalyst can be supported on the carbon powder by, for example, a colloid method.

  As a content ratio of the carbon powder and the catalyst, for example, the catalyst is preferably 5 to 400 parts by mass with respect to 100 parts by mass of the carbon powder. This is because such a content ratio can constitute a positive electrode catalyst layer having sufficient catalytic activity. Further, for example, when the catalyst-supported carbon powder is produced by a method of depositing the catalyst on the carbon powder (for example, a colloid method), the catalyst diameter is as long as the carbon powder and the catalyst have the above-mentioned content ratio. This is because it does not become too large and sufficient catalytic activity is obtained.

  The proton conductive material contained in the positive electrode catalyst layer 14 is not particularly limited. For example, a resin having a sulfonic acid group such as a polyperfluorosulfonic acid resin, a sulfonated polyether sulfonic acid resin, or a sulfonated polyimide resin is used. Can be used. Specific examples of the polyperfluorosulfonic acid resin include “Nafion (registered trademark)” manufactured by DuPont, “Flemion (registered trademark)” manufactured by Asahi Glass, and “Aciplex (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd. Or the like.

  The content of the proton conductive material in the positive electrode catalyst layer 14 is preferably 2 to 200 parts by mass with respect to 100 parts by mass of the catalyst-supporting carbon powder. If the proton conductive material is contained in the above-mentioned amount, sufficient proton conductivity is obtained in the positive electrode catalyst layer, and the electric resistance value does not become too large, and a fuel cell with good battery performance can be obtained. It is.

  The binder for the positive electrode catalyst layer 14 is not particularly limited. For example, PTFE, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetra Fluoropolymers such as fluoroethylene-ethylene copolymer (E / TFE), polyvinylidene fluoride (PVDF) and polychlorotrifluoroethylene (PCTFE), polyethylene, polypropylene, nylon, polystyrene, polyester, ionomer, butyl rubber, ethylene -Non-fluorinated resins such as vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, and ethylene / acrylic acid copolymer can be used.

  The binder content in the positive electrode catalyst layer 14 is preferably 0.01 to 100 parts by mass with respect to 100 parts by mass of the catalyst-supporting carbon powder. This is because if the binder is contained in the above-mentioned amount, sufficient binding properties can be obtained for the positive electrode catalyst layer, and the electric resistance value does not become too large, and a fuel cell with good battery performance can be obtained.

  The negative electrode catalyst layer 16 has a function of oxidizing a fuel such as hydrogen or methanol that has diffused through the negative electrode diffusion layer. The negative electrode catalyst layer contains, for example, a carbon powder carrying a catalyst (catalyst-carrying carbon powder) and a proton conductive material. If necessary, a binder such as a resin may be further contained.

  The catalyst related to the negative electrode catalyst layer 16 is not particularly limited as long as it can oxidize a fuel such as hydrogen or methanol. For example, each of the catalysts exemplified as the catalyst related to the positive electrode catalyst layer can be used. Regarding the carbon powder, proton conductive material, and binder related to the negative electrode catalyst layer, the above-described materials exemplified as the carbon powder, proton conductive material, and binder related to the positive electrode catalyst layer can be used.

  The solid polymer electrolyte membrane 15 is not particularly limited as long as it is made of a material that can transport protons and does not exhibit electron conductivity. Examples of materials that can constitute the solid polymer electrolyte membrane 15 include polyperfluorosulfonic acid resin, specifically, “Nafion (registered trademark)” manufactured by DuPont, and “Flemion (registered trademark)” manufactured by Asahi Glass. "Aciplex (trade name)" manufactured by Asahi Kasei Corporation. In addition, sulfonated polyether sulfonic acid resin, sulfonated polyimide resin, sulfuric acid-doped polybenzimidazole, and the like can also be used as the material of the solid polymer electrolyte membrane 15.

  FIG. 9 shows a schematic plan view of the seals 9a and 9b. The seals 9a and 9b are arranged above and below the MEA. At that time, the MEA electrode fits in the hole 28 provided in the seal, and the portion of the solid polymer electrolyte membrane that protrudes from the electrode portion is sandwiched between the seals 9a and 9b. With such a configuration, the fuel cell can be made to function well by separating the fuel and oxygen in the air. The seals 9a and 9b shown in FIG. 9 are provided with a series connection tab contact area 27, in which the positive electrode series connection tab of the positive electrode current collector plate and the negative electrode series connection tab of the negative electrode current collector plate are electrically contacted. Each MEA can be connected in series. In addition, a fixing portion 20 (screw hole) is also provided in the seals 9a and 9b in FIG.

  As a material for the seal, various materials known as a seal material in the field of fuel cells, for example, silicon rubber, ethylene-propylene-diene rubber, PTFE film, polyimide film, and the like can be used.

  The fixing of the positive electrode panel plate and the negative electrode panel plate for integrating all the MEAs in the MEA unit is not particularly limited as long as each MEA can be suppressed with a certain degree of uniformity. For example, among the positive electrode panel plate, the positive electrode insulating plate, the positive electrode current collecting plate, the seal, the negative electrode current collecting plate, the portion corresponding to the negative electrode insulating plate and the negative electrode panel plate other than the MEA electrode portion, and the MEA solid polymer electrolyte membrane The entire portion protruding from the electrode portion may be fixed by bonding or the like.

  However, since the MEA can be more easily suppressed, as shown in FIG. 1, it is preferable to fix the positive electrode panel plate and the negative electrode panel plate by the mechanical clamping means in the fixing portions arranged at intervals. In this case, as the mechanical clamping means in the fixing portion, for example, screwing using a bolt and nut shown in FIG. 1 or riveting can be preferably employed.

  In addition, as described above, when the positive electrode panel plate and the negative electrode panel plate are fixed by the fixing portions arranged at intervals, the shorter fixing portion between the adjacent fixing portions with the MEA interposed therebetween. Is preferably 10 mm or more and 40 mm or less. By arranging the fixing portions so that the distance between the fixing portions is as described above, the battery characteristics can be improved.

  The distance between the fixed portions will be described with reference to FIG. 3. As fixed portions adjacent to each other with the MEA between the fixed portion 20a and 20a, there are 20b, 20c, and 20d. The distance is shorter at 20c. “The distance between the shorter fixed parts among the adjacent fixed parts across the MEA is 10 mm or more and 40 mm or less” means that the distance between the fixed part 20a and the fixed part 20c is 10 mm or more and 40 mm or less. I mean.

  If the distance between the fixed parts is too short, the area of the electrode portion of the MEA becomes small, and if it is too long, the deflection of the panel plate when tightened by the mechanical clamping means becomes large and the MEA is uniformly suppressed. The internal resistance of the battery may increase, or current concentration may occur in a relatively restrained portion, causing deterioration of the electrode. The distance between the fixed portions is more preferably 15 mm or more, and more preferably 30 mm or less.

  Further, the distance between the adjacent fixed parts without sandwiching the MEA (for example, the distance between the fixed part 20a and the fixed part 20e in FIG. For the same reason as “the shorter distance between the fixed portions”, it is preferably 10 mm or more, more preferably 15 mm or more, preferably 40 mm or less, more preferably 30 mm or less.

  In the fuel cell constituting the fuel cell power generation system of the present invention, for example, the total area in the plan view of the opening 11 on the positive electrode side shown in FIG. 1 is divided by the area of the positive electrode in the plan view and expressed as a percentage. The aperture ratio (A) is preferably 10% or more and 60% or less. By making the aperture ratio on the positive electrode side as described above, the supply of oxygen to the positive electrode and the current collection from the MEA can be made better.

  That is, if the aperture ratio (A) is too small, the supply of oxygen to the positive electrode may decrease. On the other hand, if the aperture ratio (A) is too large, the current collecting property of the current generated from the MEA 100 may be lowered. The aperture ratio (A) is more preferably 15% or more, and more preferably 50% or less.

  The opening 11 on the positive electrode side and the opening 12 on the negative electrode side can have various shapes such as a square (rectangle, square, etc.) and a circle (true circle, ellipse, etc.). The opening 11 on the positive electrode side is in contact with the opening 11 in a plan view on the positive electrode side, and when the two parallel lines with the shortest shortest distance between the lines are drawn, the shortest distance (B ) Is preferably 0.2 mm or more and 3 mm or less.

  FIG. 11 shows an enlarged view of one of the openings 11 on the positive electrode side. FIG. 11A shows a case where the opening 11 is rectangular. When the opening 11 is rectangular, two parallel lines I and II and i and ii in the figure can be drawn as two parallel lines in contact with the opening 11. Among these, the shortest distance between the two lines is the shortest between the lines I and II in the figure, and the shortest distance between the lines I and II is 0.2 mm or more. It is preferable that it is 3 mm or less.

  FIG. 11B shows a case where the opening 11 is a perfect circle. If the opening 11 is a perfect circle, two parallel lines in contact with the opening 11 are Two lines sandwiching the diameter of the opening 11 can be drawn like I and II in the middle, and even if the two lines are drawn at any position of the opening 11, the distance between these lines Is equal to the diameter of the opening 11. Therefore, when the opening 11 is a perfect circle, the shortest distance between the line I and the line II, that is, the diameter of the opening 11 is preferably 0.2 mm or more and 3 mm or less.

  By setting the shortest distance (B) between the two wires in the opening on the positive electrode side as described above, it is possible to improve the supply of oxygen to the positive electrode and the current collection from the MEA. That is, if the shortest distance (B) between the two lines is too small, it may be difficult to take in oxygen in the atmosphere outside the fuel cell. On the other hand, if the shortest distance (B) between the two lines is too large, current collection at the portion where the opening 11 is located becomes insufficient, and the output of the battery may decrease. The shortest distance (B) between the two lines is more preferably 0.5 mm or more, and more preferably 2 mm or less.

  Furthermore, in the fuel cell constituting the fuel cell power generation system of the present invention, the portion other than the opening 11 (that is, the opening 11 reaching the positive electrode diffusion layer 13 is not formed in the plan view on the positive electrode side. It is preferable that the shortest distance (C) from an arbitrary point (where the panel plate 1 or the like is present) to the opening 11 located closest to the arbitrary point is 2 mm or less. By setting the shortest distance (C) to be equal to or less than the upper limit value, it is possible to further increase the uniformity of oxygen supply to the MEA 100 and further improve the output of the battery.

  That is, if the shortest distance (C) is too short, a portion where the upper portion of the positive electrode diffusion layer 13 is not opened due to the presence of the positive electrode panel plate 1 or the like is partially increased. It becomes difficult to supply oxygen. Therefore, the MEA 100 may have a location where oxygen supply is insufficient, and the output of the battery may be reduced. The shortest distance (C) is more preferably 1.5 mm or less. In addition, there is no restriction | limiting in particular about the lower limit of the said shortest distance (C), and it determines suitably in balance with the said aperture ratio (A).

  Also, for the opening 12 on the negative electrode side, the total area of the opening 12 on the negative electrode side in plan view is divided by the area of the negative electrode in plan view, which is expressed as a percentage. Is preferably 10% or more, more preferably 15% or more, and from the viewpoint of improving current collection or suppressing drying of MEA 100, it is preferably 60% or less. It is preferable that it is 50% or less.

  Further, also in the negative electrode side opening 12, when the two parallel lines that are in contact with the opening 12 and have the shortest shortest distance between the lines in the plan view on the negative electrode side are drawn, the shortest distance is From the viewpoint of improving the supply of fuel to the negative electrode, it is preferably 0.2 mm or more, more preferably 0.5 mm or more, and from the viewpoint of improving current collection, it is 3 mm or less. It is preferable that it is 2 mm or less.

  In addition, from the viewpoint of further improving the uniformity of the supply of fuel to the MEA 100, a portion other than the opening 12 (that is, the opening 12 reaching the negative electrode diffusion layer 17 is not formed in a plan view on the negative electrode side). The shortest distance from an arbitrary point at the location where the negative electrode panel plate 2 or the like is present to the opening 12 located closest to the arbitrary point is preferably 2 mm or less, and 1.5 mm The following is more preferable.

The individual area of the opening 11 on the positive electrode side is preferably 0.1 mm ² or more, more preferably 0.2 mm ² or more, from the viewpoint of better taking in oxygen outside the fuel cell. On the other hand, if the individual areas of the openings 11 are too large, the strength of the positive electrode panel plate 1 and the like may be reduced. Therefore, the area is preferably 40 mm ² or less, and more preferably 30 mm ² or less. preferable.

In addition, the individual area of the opening on the negative electrode side is also preferably 0.1 mm ² or more, more preferably 0.2 mm ² or more from the viewpoint of better taking in the fuel, and the negative electrode panel plate From the viewpoint of suppressing a decrease in strength such as ² , it is preferably 40 mm ² or less, and more preferably 30 mm ² or less.

  Although the fuel cell constituting the fuel cell power generation system of the present invention has been described so far with reference to FIGS. 1 to 10, those shown in these drawings are only examples, and the fuel cell used in the present invention is The structure is not limited to those shown in these drawings. For example, a fuel cell in which a plurality of MEAs are arranged in a plane has been described so far, but a fuel cell may be configured by stacking a plurality of MEA units in which a plurality of MEAs are arranged in a plane.

  The fuel of the fuel cell power generation system of the present invention is preferably a fuel that uses water in the production process, such as hydrogen produced by a reaction between a hydrogen generating substance and water. In this case, the fuel is used in the fuel production process. Since the water to be used and the water to humidify the fuel can be shared, the fuel cell power generation system of the present invention can be made more compact.

  The fuel cell can constitute a fuel cell power generation system of the present invention together with a fuel supply source. In the fuel cell power generation system of the present invention, for the above reasons, water is supplied continuously or intermittently as a fuel supply source to the hydrogen generating material, and the hydrogen generating material and the water are reacted to generate hydrogen. Preferably, a hydrogen production apparatus that generates hydrogen is used.

  FIG. 11 schematically shows a configuration example of the fuel cell power generation system of the present invention. In FIG. 11, 200 is a fuel cell, 300 is a hydrogen production apparatus, and 400 is an external load. Although FIG. 11 shows a configuration in which the external load 400 is connected to the fuel cell 200 via a switch, the external load 400 may be configured to be directly connected to the fuel cell 200.

  FIG. 12 schematically shows an example of a hydrogen production apparatus according to the fuel cell power generation system of the present invention. The hydrogen production apparatus shown in FIG. 12 has a mechanism for supplying water continuously or intermittently to the hydrogen generating substance and generating hydrogen by reacting the hydrogen generating substance with the water.

  The hydrogen production apparatus 300 includes a hydrogen generating substance storage container 301 that stores a hydrogen generating substance and a water storage container 302 that stores water, and supplies water from the water storage container 302 to the hydrogen generating substance storage container 301. Then, hydrogen is produced by reacting the hydrogen generating substance with water in the container 301. Therefore, the hydrogen generating substance storage container 301 also serves as a reaction container for the hydrogen generating substance and water. Hydrogen generated in the container 301 is supplied to the fuel cell 200 through a fuel flow path constituted by hydrogen outlet pipes 306 and 307.

  A water supply pipe 303 that supplies water from the water storage container 302 to the hydrogen generating substance storage container 301 is provided with a water supply pump 303.

  The hydrogen generating substance storage container 301 and the water storage container 302 may be detachable. As a result, when the hydrogen generating substance in the container 301 is completely consumed or when the water in the container 302 runs out, these are removed and the hydrogen generating substance containing container 301 filled with the hydrogen generating substance or water is filled. By newly attaching the water container 302, hydrogen production can be performed again.

  The hydrogen generating material stored in the hydrogen generating material storage container 301 is not particularly limited as long as it can generate hydrogen by reacting with water at a low temperature of 120 ° C. or lower. For example, metals such as aluminum, silicon, zinc, and magnesium; alloys mainly composed of one or more elements of aluminum, silicon, zinc, and magnesium; hydrogenated compounds;

  In the case of an alloy mainly composed of one or more elements selected from aluminum, silicon, zinc and magnesium, elements other than the respective elements which are the main elements are not particularly limited. Here, the “main body” means that 80% by mass or more, more preferably 90% by mass or more is contained with respect to the entire alloy.

  Metals such as aluminum, silicon, zinc, and magnesium, and alloys mainly composed of one or more elements of aluminum, silicon, zinc, and magnesium are less likely to react with water at room temperature. It is a substance that facilitates exothermic reaction. In this specification, normal temperature is a temperature in the range of 20 to 30 ° C.

For example, in the case of aluminum and water, the reaction for producing hydrogen and oxidation products is as follows:
2Al + 6H ₂ O → Al ₂ O ₃ .3H ₂ O + 3H ₂ (1)
2Al + 4H ₂ O → Al ₂ O ₃ .H ₂ O + 3H ₂ (2)
2Al + 3H ₂ O → Al ₂ O ₃ + 3H ₂ (3)

  The hydrogen generating material made of the metal or alloy is stabilized by forming an oxide film on the surface. For this reason, it is preferable to make the particle size of the hydrogen generating material as small as possible and increase the reaction area. For example, the form of the hydrogen generating substance is preferably in the form of particles or flakes having a particle diameter of 0.1 to 100 μm, and the particle diameter is more preferably 0.1 to 50 μm. This is because hydrogen generation occurs smoothly when the particle size of the hydrogen generating substance is 100 μm or less. Further, when the particle size of the hydrogen generating material is reduced, the hydrogen generation rate is increased. However, when the particle size is smaller than 0.1 μm, the flammability is increased and handling becomes difficult. Moreover, since the bulk density is reduced, the filling density of the hydrogen generating material is lowered, and the energy density is likely to be lowered. For this reason, it is preferable that the particle size of the hydrogen generating substance is 0.1 μm or more.

  In addition, the particle size of the hydrogen generating substance referred to in the present specification is an average particle size, and means a value of a particle diameter at a volume-based integrated fraction of 50%. As a method for measuring the average particle diameter, for example, a laser diffraction / scattering method or the like can be used. Specifically, this is a particle diameter distribution measurement method using a scattering intensity distribution detected by irradiating a measurement target substance dispersed in a liquid phase such as water with laser light. As a particle size distribution measuring apparatus using a laser diffraction / scattering method, for example, “Microtrack HRA” manufactured by Nikkiso Co., Ltd. can be used.

  Examples of the hydride compound that can be used as the hydrogen generating substance include metal hydrides such as sodium borohydride or potassium borohydride. These hydrogenated compounds are relatively stable in an alkaline aqueous solution, but when a catalyst is present, they can quickly react with water to generate hydrogen. As the catalyst, for example, metals such as Pt and Ni, acids, and the like can be used.

For example, in the case of sodium borohydride, it can react as the following formula to generate hydrogen.
NaBH ₄ + 2H ₂ O → NaBO ₂ + 4H ₂ (4)

  As the hydrogen generating substance, those exemplified above may be used alone or in combination of two or more.

  Further, by using the hydrogen generating material together with a heat generating material (a material other than the hydrogen generating material) that generates heat by reacting with water, even if low temperature (for example, about 5 ° C.) water is supplied, The temperature in the reaction system can be increased by exotherm, and rapid hydrogen generation can be enabled.

  Exothermic substances that generate heat by reacting with water, for example, calcium oxide, magnesium oxide, calcium chloride, magnesium chloride, calcium sulfate, etc., are converted into hydroxides by reaction with water or exothermic by hydration. Examples include alkali metal or alkaline earth metal oxides, chlorides, and sulfuric acid compounds. In addition, those that generate hydrogen by reaction with water, such as metal hydrides such as sodium borohydride, potassium borohydride, and lithium hydride, can be used as a hydrogen generating substance as described above. However, it can also be used as a heat generating material when the metal or alloy is used as a hydrogen generating material.

  For example, a heat-generating substance that reacts with oxygen and generates heat, such as iron powder, is also known. However, when iron powder is used as the exothermic substance, oxygen must be introduced during the reaction, and it occurs when the hydrogen generating substance and the exothermic substance are arranged in the same reaction vessel as described above. Problems such as reduction in the purity of hydrogen and reduction in the amount of hydrogen generated due to oxidation of the hydrogen generating substance by oxygen are likely to occur. Therefore, as the exothermic substance, a material that generates heat by reacting with water is preferably used.

  In particular, when a metal such as aluminum, silicon, zinc, or magnesium or an alloy mainly composed of one or more elements selected from aluminum, silicon, zinc, and magnesium is used as the hydrogen generating material, the exothermic material is used. It is preferable to use together. On the other hand, when the hydrogenated compound is used as a hydrogen generating substance, hydrogen can be produced at a relatively good rate without using the exothermic substance. May be increased.

  When the hydrogen generating substance and the exothermic substance are used in combination, the amount of the hydrogen generating substance is preferably 85% by mass or more in a total of 100 mass% of the hydrogen generating substance and the exothermic substance introduced into the hydrogen generating substance storage container. . If the amount of hydrogen generating material in the total of the hydrogen generating material and the exothermic material is too small, the hydrogen generating amount may decrease, or if the amount of the exothermic material is too large, the heat generation may become intense and the hydrogen generating reaction may be difficult to control. .

  The exothermic substance may be put into the hydrogen generating substance storage container as a mixture obtained by uniformly or non-uniformly mixing with the hydrogen generating substance, or may be put into the hydrogen generating substance storage container separately from the hydrogen generating substance. In the latter case, for example, it is preferable to dispose the exothermic substance in the vicinity of the mouth portion of the water supply pipe (305 in FIG. 12) related to the hydrogen generating substance storage container. By arranging the exothermic material in this way, the inside of the reaction system can be heated more efficiently.

  The material and shape of the hydrogen generating substance storage container 301 are not particularly limited as long as it can store a hydrogen generating substance that generates hydrogen, but a material that does not allow water or hydrogen to leak from other than the water supply port and the hydrogen outlet. Or a shape is preferred. As a specific material of the container, a material that does not easily transmit water and hydrogen and that does not break even when heated to about 120 ° C. is preferable. For example, a metal such as aluminum or iron, or a resin such as polyethylene or polypropylene may be used. Can be used. Further, as the shape of the container, a prismatic shape, a cylindrical shape or the like can be adopted.

  There is no restriction | limiting in particular about the water storage container 302, For example, the tank etc. which store the water similar to the conventional hydrogen production apparatus are employable.

  The water in the water storage container 302 is supplied to the hydrogen generating substance storage container 301 through the water supply pipe 305 to react with the hydrogen generating substance in the container 301 to generate hydrogen. The unreacted water present inside is pushed by the generated hydrogen gas pressure, and the water to be used for the reaction may come out of the hydrogen production apparatus 300 through the hydrogen outlet pipe 306 in some cases.

  Therefore, as shown in FIG. 12, the hydrogen production apparatus 300 is preferably provided with a condensate separator 304 in the fuel flow path connecting the fuel cell 200 and the hydrogen production apparatus 300. The condensed water separator 304 is connected to the hydrogen generating substance storage container 301 via a hydrogen outlet pipe 306, and a hydrogen outlet pipe 307 is attached. The water in the mixture with hydrogen discharged from the hydrogen generating substance storage container 301 is cooled in the hydrogen outlet pipe 306 to become condensed water. When the hydrogen accompanying the condensed water is introduced into the condensed water separator 304, the condensed water falls to the lower part of the condensed water separator 304 and is separated by gravity.

  Then, as shown in FIG. 12, by condensing the condensed water separator 304 and the water storage container 302 with a water recovery pipe 308, the water separated by the condensed water separator 304 is transferred to the water storage container 302. It can be recovered. Thus, by collecting the water separated by the condensate separator 304, it becomes possible to reduce the substantial supply amount of water used for hydrogen generation, and to make the water container 302 more compact. be able to.

  In the hydrogen production apparatus shown in FIG. 12, the water storage container 302 that stores water also has a function of supplying water for humidifying the fuel cell 200. That is, the water storage container 302 is provided with a water supply pipe 310 and a water supply pump 309 for supplying water to a humidification tank provided in the fuel cell 200. As described above, when the fuel supply source constituting the fuel cell power generation system is a hydrogen production apparatus that supplies hydrogen by the reaction of the hydrogen generating substance and water, a part of the water used for the hydrogen generating reaction is used. Can be used as water for humidifying the fuel, so that the system can be made more compact.

  As described above, the fuel cell power generation system of the present invention can be made more compact as the entire system can be made compact while suppressing the output decrease accompanying drying of the MEA in the fuel cell and stabilizing the output. It can be preferably used for power supply applications of various electronic devices including power supply applications such as portable devices that are required to be.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Experiment 1
<Fabrication of fuel cell>
A fuel cell having the structure shown in FIG. 1 was produced. The MEA 100 having the configuration shown in FIG. 8 was used. As the positive electrode and the negative electrode of MEA 100, electrodes (“LT140E-W” manufactured by E-TEK, Pt amount: 0.5 mg / cm ² ) coated with Pt-supported carbon on carbon cloth were used. In addition, “Nafion 112” manufactured by DuPont was used for the solid polymer electrolyte membrane 15. Each electrode was 25 mm × 92 mm, and the solid polymer electrolyte membrane was 105 mm × 100 mm.

  As the positive electrode panel plate 1, the one shown in FIG. 3 and made of stainless steel 304 and having a thickness of 2 mm was used. The oxygen introduction holes 11a for forming the openings are 1 mm × 13 mm rectangular holes, which are arranged in a total of 72 pieces, each having 6 pieces vertically and 12 pieces on the left and right over the entire area corresponding to the upper part of the positive electrode diffusion layer of each MEA. . The oxygen introduction holes 11a are arranged with a distance of 1 mm on the left and right and 2 mm on the top and bottom. The ratio of the opening on the positive electrode side to the electrode area (opening ratio) is 42%. As shown in FIG. 3, a hole of φ3 mm was provided in the fixing portion 20 at a position corresponding to the outer peripheral portion of the MEA. Among the fixed parts adjacent to each other with the MEA interposed therebetween, the distance between the shorter fixed parts is 31 mm, and the distance between the adjacent fixed parts without sandwiching the MEA is 15 mm.

  The negative electrode panel plate 2 was prepared with the same material and shape as the positive electrode panel plate 1.

  As the positive electrode current collecting plates 5 and 6, the structure shown in FIG. 4 (a) (positive electrode end current collecting plate) and (b) (positive electrode current collecting plate) having the cross-sectional structure shown in FIG. 5 was used. . The electrode-side layer (thickness 0.23 mm) of the positive electrode current collector plate is made of SUS304, and the layer on the opposite side of the electrode (thickness 0.07 mm) is made of Cu, and the entire surface is covered by vapor deposition of Au with a thickness of 0.2 μm. did. The shapes and arrangements of the oxygen introduction holes 11b and the fixing portions 20 of the positive electrode current collecting plates 5 and 6 are the same as those of the positive electrode panel plate. The positive electrode end current collecting plate 5 was provided with a positive electrode current collecting terminal portion 24. Furthermore, the positive electrode current collecting plate 6 is provided with one positive electrode series connection tab 25 at a position corresponding to the outer peripheral portion of the fuel cell.

  The negative electrode end current collecting plate 7 and the negative electrode current collecting plate 8 were prepared in the same material and shape as the positive electrode end current collecting plate 5 and the positive electrode current collecting plate 6.

  The positive electrode insulating plate 3 having the structure shown in FIG. 6 and made of glass epoxy resin and having a thickness of 0.5 mm was used. The shape and arrangement of the oxygen introduction hole 11c and the fixing portion 20 of the positive electrode insulating plate 3 are the same as those of the positive electrode panel plate. The negative electrode insulating plate 4 was prepared with the same material and shape as the positive electrode insulating plate 3.

As the humidifying tank 10, a tank having a thickness of 3 mm made of glass epoxy resin having the structure shown in FIG. 2 was used. The depth of the central tank interior 21 is 2 mm. Moreover, the supply port 22 and the supply port 23 made the shape of the opening part in the tank inside 21 circular (diameter: 2 mm, area: 3.14 mm < ² >). And the supply port 22 was provided in the location where the linear distance from the center (center of the circle of the opening part of the supply port 22) to the lower side in FIG. Moreover, the discharge port 23 was provided in the location where the linear distance from the center (center of the circle of the opening part of the discharge port 23) to the lower side in FIG.

  As the seals 9a and 9b, those having a structure shown in FIG. 9 and made of silicon rubber and having a thickness of 0.2 mm were used. The size of the hole 28 for accommodating the electrode was 26 m × 93 mm.

  The above members were stacked in the order shown in FIG. 1 and tightened with bolts 18 and nuts 19 to produce a fuel cell.

<Production of hydrogen production equipment>
Next, a hydrogen production apparatus 300 having the configuration shown in FIG. 12 was produced. As the hydrogen generating substance storage container 301, a polypropylene prismatic container having an internal volume of 50 cm ³ was used. Polypropylene pipes having an inner diameter of 2 mm and an outer diameter of 3 mm were used for the water supply pipe 305, the hydrogen outlet pipe 306, and the water recovery pipe 308. In a hydrogen generating substance storage container 301, 19.7 g of aluminum powder having an average particle diameter of 3 μm as a hydrogen generating substance and 2.5 g of calcium oxide as a heat generating substance were placed. As the water storage container 302, a polypropylene prismatic container having an internal volume of 50 cm ³ was used, and 45 g of water was put therein. For the condensate separator 304, a polypropylene prismatic container having an internal volume of 10 cm ³ was used.

<Assembly of fuel cell power generation system>
The fuel cell and the hydrogen production apparatus were connected by polypropylene pipes (307 and 310 in FIG. 12) having an inner diameter of 2 mm and an outer diameter of 3 mm to produce a fuel cell power generation system.

  In the fuel cell power generation system, hydrogen was generated from a hydrogen production apparatus, and a power generation test was performed at a constant current of 3.7 A. The test was performed at room temperature of 25 ° C., and water was supplied from the water storage container 302 of the hydrogen production apparatus 300 to the fuel cell 200, and power was generated in a state where water was stored in the humidification tank 10 up to the position of the discharge port 23. .

Experiment 2
<Fabrication of fuel cell>
A fuel cell power generation system was produced in the same manner as in Example 1 except that the hydrogen production apparatus 500 having the configuration shown in FIG. 13 was used as the hydrogen production apparatus. The hydrogen production apparatus 500 has the same configuration as the hydrogen production apparatus 300 except that the water supply pipe 310 that supplies water from the water container 302 to the fuel cell 200 and the water supply pump 309 are not provided.

  A power generation test was performed in the same manner as in Experiment 1 except that the fuel cell power generation system was used and water was not stored in the humidification tank 10. That is, the power generation test in Experiment 2 corresponds to a power generation test in a fuel cell power generation system that does not have a humidifier.

  The power generation test results of Experiment 1 and Experiment 2 are shown in FIG.

  As is clear from FIG. 14, the fuel cell power generation system of Experiment 1 can continue power generation stably. On the other hand, in the case of the fuel cell power generation system of Experiment 2, the voltage continuously decreased from about 30 minutes after the start of power generation, and power generation could not be continued stably.

It is a cross-sectional schematic diagram which shows an example of the fuel cell and humidification apparatus which comprise the fuel cell power generation system of this invention. It is a schematic diagram which shows an example of the humidification apparatus which comprises the fuel cell power generation system of this invention. It is a plane schematic diagram which shows an example of the positive electrode panel plate which concerns on the fuel cell which comprises the fuel cell power generation system of this invention. It is a plane schematic diagram which shows an example of the positive electrode current collecting plate which concerns on the fuel cell which comprises the fuel cell power generation system of this invention. It is a cross-sectional schematic diagram of a part of a positive electrode current collector plate. It is a schematic diagram which shows an example of the positive electrode insulating plate which concerns on the fuel cell which comprises the fuel cell power generation system of this invention. It is a schematic diagram which shows an example of the electrode and electrolyte integrated material which concerns on the fuel cell which comprises the fuel cell power generation system of this invention. It is a schematic diagram which shows the other example of the electrode and electrolyte integrated material which concerns on the fuel cell which comprises the fuel cell power generation system of this invention. It is a plane schematic diagram which shows an example of the seal | sticker which concerns on the fuel cell which comprises the fuel cell power generation system of this invention. It is explanatory drawing of the shape of an opening part. It is a schematic diagram which shows the structural example of the fuel cell power generation system of this invention. It is a schematic diagram which shows the structural example of the hydrogen production apparatus which can comprise the fuel cell power generation system of this invention. It is a schematic diagram which shows the structure of the hydrogen production apparatus which concerns on the fuel cell power generation system of the comparative example 1. 6 is a graph showing results of power generation tests of fuel cell power generation systems of Example 1 and Comparative Example 1.

Explanation of symbols

10 Humidifier (humidification tank)
21 Inside of tank 22 Supply port 23 Discharge port 100 Integrated electrode / electrolyte 300 Hydrogen production system

Claims (5)

A fuel cell comprising an electrode / electrolyte integrated product having a positive electrode for reducing oxygen, a negative electrode for oxidizing fuel, and a solid polymer electrolyte membrane disposed between the positive electrode and the negative electrode, and supply to the negative electrode A fuel cell power generation system having a humidifier for humidifying fuel
The humidifying device supplies the fuel to the negative electrode in a state of containing mist-like moisture.   The humidifier is a tank in which humidifying water is stored, and is provided adjacent to the negative electrode, and the fuel flows through the water so that the fuel contains mist-like water. The fuel cell power generation system according to claim 1, wherein   The fuel cell power generation system according to claim 1, further comprising a hydrogen production device that generates hydrogen by a reaction between a hydrogen generating substance and water.   The hydrogen generating material is at least one metal selected from the group consisting of aluminum, silicon, zinc and magnesium, and an alloy mainly composed of one or more of these elements, or a hydrogenated compound. The fuel cell power generation system described.   The fuel cell power generation system according to claim 3 or 4, wherein water for humidifying the fuel of the humidifying device can be supplied from the hydrogen production device.

Images