WO2009113523A1 - Alkaline fuel cell - Google Patents

Alkaline fuel cell Download PDF

Info

Publication number
WO2009113523A1
WO2009113523A1 PCT/JP2009/054518 JP2009054518W WO2009113523A1 WO 2009113523 A1 WO2009113523 A1 WO 2009113523A1 JP 2009054518 W JP2009054518 W JP 2009054518W WO 2009113523 A1 WO2009113523 A1 WO 2009113523A1
Authority
WO
WIPO (PCT)
Prior art keywords
fuel
fuel cell
indicator
alkaline
container
Prior art date
Application number
PCT/JP2009/054518
Other languages
French (fr)
Japanese (ja)
Inventor
省治 関野
小林　憲司
中村　新
Original Assignee
日本電気株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本電気株式会社 filed Critical 日本電気株式会社
Priority to JP2010502821A priority Critical patent/JPWO2009113523A1/en
Publication of WO2009113523A1 publication Critical patent/WO2009113523A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04186—Arrangements for control of reactant parameters, e.g. pressure or concentration of liquid-charged or electrolyte-charged reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04201—Reactant storage and supply, e.g. means for feeding, pipes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/08—Fuel cells with aqueous electrolytes
    • H01M8/083—Alkaline fuel cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/2455—Grouping of fuel cells, e.g. stacking of fuel cells with liquid, solid or electrolyte-charged reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
    • H01M2250/30—Fuel cells in portable systems, e.g. mobile phone, laptop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0002—Aqueous electrolytes
    • H01M2300/0014—Alkaline electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04201—Reactant storage and supply, e.g. means for feeding, pipes
    • H01M8/04208—Cartridges, cryogenic media or cryogenic reservoirs
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02B90/10—Applications of fuel cells in buildings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to an alkaline fuel cell using a liquid fuel containing an alkali.
  • the polymer electrolyte fuel cell includes an electrode-electrolyte membrane assembly (hereinafter referred to as MEA) having a structure in which a solid polymer electrolyte membrane is sandwiched between an anode and a cathode.
  • MEA electrode-electrolyte membrane assembly
  • the type of fuel cell that supplies liquid fuel to the anode has a different reaction mechanism depending on the ion conductive species of the solid polymer electrolyte membrane used in MEA, and is distinguished by its name.
  • direct methanol fuel cells hereinafter referred to as DMFC
  • DMFC direct methanol fuel cells
  • the liquid fuel of the alkaline fuel cell contains an alkali having a certain concentration rather than a pure methanol aqueous solution.
  • the purified CO 2 immediately changes to carbonate ions CO 3 2 ⁇ and dissolves in the fuel, so that it is difficult for CO 2 to be released as a gas. Does not occur.
  • CO 3 2 ⁇ is generated directly instead of CO 2 as shown in Equation (3). Therefore, with respect to the contents shown in this case, the reaction occurring in the reaction formula shown here. It is not limited to only.
  • the power generation part of a polymer electrolyte fuel cell has a basic power generation minimum unit called MEA, and further power is supplied for the first time by installing the MEA in a fuel cell having a structure for supplying fuel and taking out power. Can be used.
  • MEA basic power generation minimum unit
  • Patent Document 1 proposes a method of detecting hydrogen by passing a hydrogen gas concentration used as an anode fuel of a fuel cell through an aqueous solution containing hypochlorite and the like, and visualizing it by a change in pH.
  • Patent Document 2 is a fuel cell of a type that supplies hydrogen gas to the anode, and detects the pH of water condensed inside the fuel cell stack by some means, and controls the amount of water inside the fuel cell stack. A method for preventing corrosion of the fuel cell stack by controlling the pH has been proposed.
  • Patent Document 3 a portion for protonating hydrogen with a catalyst is provided so as to cover a hydrogen gas cylinder serving as fuel for a fuel cell, and a substance colored by pH is introduced therein, and the pH change is measured.
  • a method for detecting hydrogen leakage by a color change from a window that can be observed from the outside As described above, several proposals have been made as a method of using pH as a means for detecting the hydrogen gas and the acidity of water inside the fuel cell stack.
  • the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an alkaline fuel cell capable of easily discriminating the hydroxide ion concentration of liquid fuel.
  • the alkaline fuel cell of the present invention is a fuel cell composed of MEA having an anion exchange membrane as an electrolyte membrane, and at least a part of a fuel container provided in contact with the anode is transparent, A pH indicator that is colored by the hydrogen ion concentration of the liquid fuel inside the fuel container is introduced.
  • the alkaline fuel cell of the present invention is characterized in that the pH sensitive region is sensitive to pH 8 to 14, more preferably pH 10 to 14.
  • the initial shape of the pH indicator may be granular, plate-like or rod-like, and may be any shape, and is contained in the fuel container and does not affect power generation. It is characterized by a size of about.
  • the alkaline fuel cell according to the present invention is characterized in that it is prevented from moving to a position where it cannot be observed from externalization by being placed in a dedicated container inside the fuel container so that the pH indicator does not move. To do.
  • the alkaline fuel cell of the present invention does not require a large amount of a substance that changes the color by sensing the pH introduced into the pH indicator, even when the pH sensitive material is dissolved in the liquid fuel, the color of the liquid fuel It is characterized in that the pH is discriminated from the change in.
  • the pH indicator is covered with a protective film so that the pH sensitive material supported on the substrate does not come into contact with the liquid fuel, and the pH of the liquid fuel is to be known.
  • the pH at that time is observed by breaking the protective film by an external operation.
  • the alkaline fuel cell of the present invention is equipped with a plurality of pH indicator materials having the above-described structure, and when it is desired to know the pH of the liquid fuel, the pH is observed multiple times by breaking the protective film at any time. It is characterized by.
  • the alkaline fuel cell of the present invention is characterized in that the pH indicator is held in a fuel cartridge or a fuel supply path for supplying fuel to the fuel container.
  • a decrease in hydroxide ion concentration due to power generation of an alkaline fuel cell can be visually captured in real time using a pH indicator, so that the timing of fuel replacement can be accurately grasped. It becomes possible to do.
  • FIG. 1 shows a cross-sectional view of a fuel battery cell 11 relating to an embodiment of the present invention.
  • the fuel container 10 has a structure capable of storing the liquid fuel 60.
  • a fuel injection port 21 for injecting fuel is provided in the fuel container 10 so that fuel can be replenished and replaced in a timely manner.
  • two or more fuel injection ports 21 may be provided.
  • the MEA 30 is set between current collectors. Specifically, an anode current collector 42 is located on the anode 32 side, and a cathode current collector 41 is located on the cathode side 31, and these current collectors sandwich the MEA 30 to collect current.
  • the MEA 13 has a structure in which the cathode 31 and the anode 32 face each other so as to sandwich the anion exchange membrane (hereinafter, in the embodiment of the present invention, the anion exchange membrane is expressed as a solid polymer electrolyte membrane 33). .
  • a cathode catalyst layer and an anode catalyst layer are formed on the surfaces of the cathode 31 and the anode 32 in contact with the solid polymer electrolyte membrane 33, respectively. Further, a seal member 43 is provided between the current collectors for the purpose of sealing insulation and leakage of liquid.
  • These power generation parts are basically fastened to the fuel container 10 by a fixing method such as screwing, but are not necessarily fixed by screws or the like, and can be collected by a current collector. Moreover, it is only necessary that the structure does not leak fuel.
  • the fuel cell 11 is configured by such a structure.
  • the liquid fuel 60 is stored in the fuel container 10.
  • a liquid fuel 60 in which an alkali such as KOH is dissolved in an aqueous methanol solution is used as the liquid fuel 60.
  • a wicking material intended to efficiently supply the liquid fuel 60 to the anode electrode 32 may be used inside the fuel container 10.
  • the wicking material has a fuel supply promoting ability mainly using a capillary force as a driving force through continuous pores formed in a foam material such as urethane. As a result, the fuel is stably supplied to the anode electrode 32.
  • alkali is contained in the liquid fuel 60, it is necessary to use a wicking material using an alkali-resistant material. It is conceivable that alkali such as KOH is deposited in the partial space formed by the consumption of the liquid fuel 60. As a result, continuous vacancies in the wicking material are blocked, which is necessary for power generation. It is also conceivable that the liquid fuel 60 is difficult to be supplied to the anode electrode 32. As described above, since the wicking material is not an essential element, the description thereof is omitted.
  • the fuel cell according to the embodiment of the present invention uses the liquid fuel 60 in which an alkali is dissolved in an alcohol aqueous solution such as a methanol aqueous solution.
  • an alcohol aqueous solution such as a methanol aqueous solution.
  • the alkali it is desirable to use KOH, NaOH, or the like, but CaOH, ammonia, or the like can also be used although there is a limit in dissolution in liquid and pH.
  • the liquid fuel 60 becomes alkaline, substances other than those described above can be used.
  • an aqueous methanol solution is used as the liquid fuel 60.
  • the fuel component is not necessarily limited to one containing methanol as a basic component, but alcohol fuel such as ethanol, ether fuel, and the like.
  • the fuel component is not limited.
  • the liquid fuel 60 may be supplied from the fuel container 10 to the anode electrode 32 in some form, and may be a passive type or a fuel circulation supply type such as an active type.
  • the supply form of the liquid fuel 60 is not limited in the present invention.
  • the MEA 30 has a structure in which a solid polymer electrolyte membrane 33 is sandwiched between a cathode 31 and an anode 32.
  • a solid polymer electrolyte membrane 33 having high conductivity of anions, that is, hydroxide ions, and having no electronic conductivity is used.
  • an ion exchange resin having a polar group such as a base is preferable, but the material cannot be specified at present.
  • the film thickness of the solid polymer electrolyte membrane 33 can be appropriately selected within the range of about 5 to 300 ⁇ m depending on the material, the use of the fuel cell, and the like. However, the values shown here are not absolute with respect to this film thickness.
  • the cathode electrode 31 is an electrode that generates hydroxide ions by the reaction of water and oxygen.
  • particles (including powder) in which a catalyst is supported on a carrier such as carbon or a catalyst alone having no carrier, A catalyst layer made of a binder having ion conductivity can be obtained by coating or the like on a substrate such as carbon paper.
  • the catalyst include platinum, rhodium, palladium, iridium, osmium, ruthenium, rhenium, gold, silver, nickel, cobalt, molybdenum, lanthanum, strontium, yttrium, and the like.
  • the catalyst may be used alone or in combination of two or more.
  • the particles supporting the catalyst include carbon-based materials such as acetylene black, ketjen black, carbon nanotubes, and carbon nanohorns.
  • the size of the particles is appropriately selected, for example, in the range of about 0.01 to 0.1 ⁇ m, preferably in the range of about 0.02 to 0.06 ⁇ m when the carbonaceous material is a granular material.
  • an impregnation method can be applied.
  • the solid polymer electrolyte membrane 33 can be used as the base material on which the catalyst layer is formed.
  • a porous material having conductivity such as carbon paper, a carbon molded body, a carbon sintered body, a sintered metal, and a foamed metal can be used.
  • the catalyst layer is formed on the base material to obtain the cathode electrode 31, and then the catalyst layer is in contact with the solid polymer electrolyte membrane 33 by a method such as hot pressing.
  • the cathode electrode 31 is preferably joined to the solid polymer electrolyte membrane 33.
  • the catalyst amount per unit area of the cathode electrode 31, according to the catalyst type and size and the like can be appropriately selected within the range of about 0.1mg / cm 2 ⁇ 20mg / cm 2, the power density to obtain It is also possible to apply an amount outside this range.
  • the anode electrode 32 is an electrode that generates water, CO 2, and electrons from a reaction between an aqueous methanol solution and hydroxide ions, and is configured in the same manner as the cathode electrode 31 described above.
  • the catalyst layer and base material constituting the anode electrode 32 may be the same as or different from the catalyst layer and base material constituting the cathode catalyst 31.
  • the catalyst amount per unit area of the anode 32, as in the case of the cathode, depending on the catalyst type and size, etc., may be appropriately selected within the range of about 0.1mg / cm 2 ⁇ 20mg / cm 2, Depending on the desired power density, it is possible to apply an amount outside this range.
  • hydrophobic PTFE, anion exchange resin, or the like as a binder supplement, but water is mediated. Therefore, it is possible to substitute a proton conductor such as Nafion at present.
  • the cathode current collector 41 and the anode current collector 42 are disposed on and in contact with the cathode electrode 31 and the anode electrode 32, respectively, and act to increase the electron extraction efficiency and the electron supply efficiency.
  • these current collectors 41 and 42 may have a frame shape in contact with the peripheral portion of the MEA 30, or may have a flat plate shape or mesh shape in contact with the entire surface of the MEA. Also good. The shape can be determined according to the design convenience.
  • Examples of the material of the current collectors 41 and 42 include stainless steel, sintered metal, foam metal, etc., or a conductor such as a carbon material obtained by plating these metals with a highly conductive metal material, or the like. Can be used. In particular, a material having high alkali resistance is preferable.
  • the fuel cell stack 15 that includes the current collecting structure in the MEA structure itself is not as shown here, and may not necessarily be a current collecting system using a current collector.
  • the fuel battery cell 11 of the present embodiment is provided with a plurality of sealing members 43 having a sealing function.
  • a seal member 43 having a thickness substantially the same as the thickness of the cathode electrode 31 is provided between the solid polymer electrolyte membrane 33 and the cathode current collector 41 on the periphery of the cell structure.
  • a seal member 43 having a thickness substantially the same as the thickness of the anode electrode 32 is provided between the solid polymer electrolyte membrane 33 and the anode current collector 42 in a frame shape on the periphery of the cell structure. Is provided.
  • a seal member 43 having an arbitrary thickness is provided between the anode current collector 42 and the fuel container 10.
  • Each of these sealing members preferably has sealing properties, insulating properties, and elasticity as necessary, and is usually formed of rubber or plastic having a sealing function.
  • it can be formed of a plastic material such as PTFE, PET, PEEK, or vinyl chloride, or a rubber material such as Teflon (registered trademark) rubber, silicon rubber, or butyl rubber.
  • the opening facing the anode 32 has the same surface area as the anode electrode. Also, there is no particular restriction on the thickness direction, but if the distance between the bottom of the fuel container 10 and the anode is too far, fuel tends to accumulate at the bottom of the fuel container 10. It is desirable that the thickness of the fuel battery cell 11 is about 10 mm. Further, the fuel container 60 according to the embodiment of the present invention is characterized in that at least a part of the fuel container 60 is transparent, and the colors of the pH indicator 70 and the liquid fuel 60 can be confirmed from the outside.
  • PH indicator 2 2, 3, 4, and 5 show examples of fuel cells into which the pH indicator 70 according to the embodiment of the present invention is inserted.
  • the pH indicator 70 is applied or supported with a substance that changes color depending on the pH of the liquid fuel 60.
  • the carrier of the pH indicator 70 and the substance to be carried will be described later.
  • at least a part of the fuel container 10 is transparent so that the inside of the fuel container 10 can be visually observed, and the pH indicator 70 can be seen from the outside.
  • FIG. 3 shows that the pH indicator 70 has a plate shape rather than a granular shape.
  • the shape of the pH indicator shown in FIGS. 2 and 3 is an example, and the shape is not limited as long as the shape and size can be observed.
  • FIG. 4 shows a pH indicator material container 71 for fixing the position so that the pH indicator material 70 does not roll inside the fuel container 10.
  • the pH indicator material container 71 is characterized by having openings such as a mesh shape, a fiber shape, and a patch shape so as not to prevent the fuel 60 from touching the pH indicator material 70.
  • FIG. 5 is characterized in that, when the pH indicator 70 shown in FIG. 3 is fixed at a specific place, the fuel container 10 has an indicator observation window 72 having a transparent portion only at that portion. .
  • Such a partially transparent portion is not necessarily limited to the structure as shown in FIG. 3, but is also provided when the pH indicator 70 is movable as shown in FIGS. be able to.
  • FIG. 6 is a simplified view of the cross-sectional structure of the pH indicator 70 according to the embodiment of the present invention shown in FIG.
  • the pH indicator 70 may be a pH-sensitive material as a whole, but only the portion visible from the outside needs to be discolored. Therefore, the pH-sensitive material is applied only to the surface of some substrate 73, and a pH-sensitive agent application unit 74 may be formed. Moreover, since the sensitive material itself dissolves in the liquid fuel, it is desirable that the base material 73 has a function of delaying the dissolution of the pH sensitive material.
  • the base material 73 is preferably made of a white or transparent material, and preferably has alkali resistance and alcohol resistance in order to make it easy to recognize the color change due to the pH of the liquid fuel 60.
  • resin materials such as PTFE, polyethylene, and polypropylene, and ceramic materials such as alumina and titania are suitable.
  • the base material 73 is required to be a transparent material, for example, hard vinyl chloride, polyethylene, polypropylene having alkali resistance, Materials such as polyacrylonitrile can be used.
  • materials other than those described here can be used as long as the materials have alkali resistance and alcohol resistance.
  • a pigment-based organic substance can be used as the pH sensitive material.
  • p- ⁇ -naphtholphthalein yellow to blue at pH 7.0 to 9.0
  • cresol red yellow to red
  • thymol blue at pH 8.0 to 9.6
  • phenolphthalein colorless to magenta at pH 8.0 to 10.0, colorless at pH 13.4 or higher
  • thymolphthalein colorless to blue at pH 9.4 to 10.6
  • alizarin yellow R (Yellow to red at pH 10.1 to 12.0)
  • Tropeolin O yellow to orange brown at pH 11.0 to 13.0) and the like have a color change range in the alkaline region at pH 8.0 to 14.0. Is suitable.
  • the color change range shown here is behavior in an aqueous solution, there is a slight difference in the degree of coloration and the color change range in a methanol aqueous solution.
  • these organic substances are dissolved in the alcohol aqueous solution, the organic substances are dissolved in the liquid fuel 60 depending on the affinity with the base material, and the pH is judged by the discoloration of the liquid fuel 60 itself.
  • the pH-sensitive material is not limited to those listed here, and is not particularly limited as long as it is a substance having a color change region in an alkaline region.
  • FIG. 7 is a cross-sectional view (a) and a perspective view (b) of the pH indicator 70 according to the embodiment of the present invention.
  • FIG. 8 is a cross-sectional view of the pH indicator 70 according to the embodiment of the present invention.
  • FIG. 9 is an external view of the pH indicator 70 according to the embodiment of the present invention. Since the pH sensitive material described above is easily dissolved in the liquid fuel 60, as shown in FIG. 7, the pH indicating portion 74 in which the pH sensitive material is applied is provided on the indicator material base 73, and is sandwiched between the protective members 75 and directly. It is preferable not to touch the liquid fuel 60.
  • either or both of the indicator material base 73 and the protective member 75 are transparent, and any member is provided with a hole reaching the pH indicator 74, and the hole is sealed with the protective film 76, and the time is appropriate. It is desirable to break the protective film 76 so that the pH of the liquid fuel 60 at that time can be monitored.
  • the indicator base material 73 does not necessarily require high alkali resistance / alcohol resistance, so it is also possible to use a commercially available pH test paper in which a pH sensitive material is impregnated into filter paper or the like. .
  • a commercially available pH test paper in which a pH sensitive material is impregnated into filter paper or the like.
  • the material of the protective film 76 it is desirable to use a transparent resin film having alkali resistance and alcohol resistance.
  • polyethylene or polypropylene can be used.
  • an elastic part (elastic film 78) is provided on at least a part of the fuel container 10, and the elastic film 78 is provided. It is possible to push the thumbtack-like protrusion 771 into the protective film 76 in a timely manner.
  • the part of the indicator material observation window 72 that is partially transparent as shown in FIG. 5 also serves as the elastic film 78, and the pH indicator 70 itself is the fuel container as shown in FIG. 10 is preferably fixed inside.
  • a method of breaking the protective film 76 of the pH indicator 70 for example, as shown in FIG. And a method of breaking the protective film 76 by operating outside the fuel container 10 with a slider 79 with magnet. Further, a magnet may be disposed on the cutter 772, and the slurder may be made of a ferromagnetic material.
  • a material having a groove-like concave portion as shown in FIG. 12 is preferable, and the blades of the cutter 772 are arranged in parallel to the concave portion. At this time, the pH indicator 70 itself is fixed inside the fuel container 10 as shown in FIG.
  • the pH indicator 70 and the stored liquid fuel 60 can be seen from the outside of the fuel container 10, and the pH indicator 70 or the liquid can be seen. Since the pH of the liquid fuel can be confirmed by the change in the color of the fuel 60, the hydroxide ion concentration required in the cell reaction shown in the formulas (3) and (4) can be confirmed, so that the voltage drop is reduced. It is possible to change the fuel before it happens. In addition, since no external load is required, there is a merit that the power generation efficiency is hardly affected. Further, the pH indicator 70 does not necessarily have to be directly installed in the fuel container 10, and can be installed in a cartridge for supplying fuel or in the fuel supply channel. It is possible to widen the range of use.
  • Example 1 The structure of the fuel cell used in the examples will be described below.
  • catalyst-supported carbon particles are prepared by supporting 50% by weight of platinum particles having a particle diameter in the range of 3 to 5 nm on carbon particles (Ketjen Black EC600JD manufactured by Lion Corporation).
  • a 5 wt% Nafion solution (trade name: DE521, “Nafion” is a registered trademark of DuPont) manufactured by DuPont was added and stirred to obtain a catalyst paste.
  • This catalyst paste was applied to carbon paper (TGPH-120 manufactured by Toray Industries, Inc.) at a coating amount of 1 to 8 mg / cm 2 and dried to be a 4 cm ⁇ 4 cm cathode electrode 31 and anode electrode 32.
  • carbon paper TGPH-120 manufactured by Toray Industries, Inc.
  • an alkaline polymer electrolyte membrane (6 cm ⁇ 6 cm ⁇ 50 ⁇ m thickness) manufactured by Tokuyama Corporation was used as the solid polymer electrolyte membrane 33, and the cathode electrode 31 was placed on one surface in the thickness direction of the membrane.
  • An electrode surface in which the surface to which the catalyst is not applied is arranged in the direction facing outside, and the surface in which the anode catalyst of the anode electrode 32 is not coated on the other surface is similarly arranged in the direction to be outside, and the electrode is coated with the catalyst.
  • Hot pressing was performed by applying pressure from the outside of each carbon paper so that they face each other through the solid polymer electrolyte membrane 33. In this way, MEA 13 was produced.
  • a rectangular frame-shaped frame plate having an outer dimension of 5 cm ⁇ 5 cm, an inner dimension of 3.8 cm ⁇ 3.8 cm, and a thickness of 1.0 mm made of stainless steel (SUS316).
  • the cathode current collector 41 and the anode current resistance 42 were arranged on both the cathode 31 side and the anode 32 side and fixed to the fuel container 10 by screwing.
  • the fuel container 10 has the same outer dimensions as the above-described current collector, and a part thereof has a transparent portion as shown in FIG.
  • the overall thickness is 5 mm
  • the depth of the inner fuel tank 12 is 3 mm
  • the cross-sectional structure is as shown in FIG.
  • a seal member 43 made of butyl rubber was disposed to prevent liquid leakage.
  • a pH indicator 70 is arranged in the vicinity of the indicator observation window 72 as shown in FIG. 5 inside the fuel container 10 so that the pH indicator 70 does not roll inside the fuel container 10.
  • the pH indicator 70 used was a pH-sensitive material in which Alizarin Yellow R, which is alkaline in red and turns yellow when the pH is lowered, is applied to a granular porous alumina substrate having a diameter of 1 mm.
  • the fuel container 10 was filled with a 15 vol% methanol aqueous solution having a KOH concentration of 3M from the fuel inlet 21 and then plugged so as not to leak fuel.
  • Example 2 In Example 2, instead of the pH indicator 70 used in Example 1, the pH indicator 70 as shown in FIG. 7 was used alone. As shown in FIG. 5, the fuel container 10 is partially provided with a transparent elastic film 78. By pushing a thumbtack-like projection 771 as shown in FIG. 8 through the elastic film 78, the protective film 76 is broken. The pH was observed by the discoloration caused by the liquid fuel 60 entering from the pH indicator 74 being touched.
  • Example 3 In Example 3, instead of the pH indicator 70 used in Example 2, a plurality of pH indicators 70 arranged as shown in FIG. 10 were used. As shown in FIG. 5, the fuel container 10 is partially provided with a transparent elastic film 78. By pushing a thumbtack-like projection 771 as shown in FIG. 8 through the elastic film 78, the protective film 76 is broken. The pH was observed by the discoloration caused by the liquid fuel 60 entering from the pH indicator 74 being touched. The observation time was taken every hour from the start of power generation, and when a voltage drop was observed, timely observation was performed.
  • Example 4 In Example 4, instead of the pH indicator 70 used in Example 3, a plurality of pH indicators 70 arranged as shown in FIG. 11 were used. However, the shape of the pH indicator 70 was as shown in FIG. As the fuel container 10, as shown in FIG. 5, a part provided with a transparent indicator observation window 72 is used. Inside the fuel container 10, a cutter 772 with a ferromagnetic base is installed along the groove of the pH indicator 70 so as not to fall inside the container, and on the outside is a slider equipped with a magnet. 79 was installed, and the cutter 772 and the slider 79 were set so as to be pulled across the wall of the fuel container 10.
  • the slurder 79 When observing pH, the slurder 79 is moved and the cutter 772 is moved to break the protective film 76, and the pH is observed by discoloration caused by the liquid fuel 60 entering from the pH touching part 74. did. The observation time was taken every hour from the start of power generation, and when a voltage drop was observed, timely observation was performed.
  • the constant current power generation test at 1.0 A was performed on the fuel cell 10 thus manufactured.
  • Example 1 most of the pH sensitive material was dissolved from the pH indicator 70 in about 30 minutes, and the liquid fuel 60 was colored red.
  • the discoloration of the liquid fuel 60 started from around 3 hours of power generation, and turned yellow after 3 and a half hours.
  • the voltage value that had been changing at about 0.45V started to decrease slightly, and was below 0.40V. Therefore, when the liquid fuel 60 was immediately replaced, it was confirmed that the liquid fuel 60 returned to a value close to the voltage value (0.44 V). To see the reproducibility, the same experiment was repeated five times, and all of them had the same result.
  • Example 2 the voltage value that had been transitioning to about 0.45 V until then began to decrease slightly after about 3 hours, and was below 0.40 V. Therefore, when the protective film 76 of the pH indicator 70 was broken, a pH drop was observed. When the liquid fuel 60 was immediately replaced at that stage, the voltage value so far returned to 0.45V. To see the reproducibility, the same experiment was repeated five times, and all of them had the same result.
  • Example 3 and Example 4 For Example 3 and Example 4, until 3 hours, the pH indicating unit 74 has a color indicating that the pH is sufficiently high, and the voltage has been stable at about 0.45 V, but for 3 hours. After a while, the voltage dropped to 0.40 V or less, and when pH was observed, a pH drop was observed. Therefore, the fuel was changed. As a result, the voltage returned to the original 0.45V. In Example 1 and Example 2, it becomes impossible to observe pH after refueling once. However, in Example 3 and Example 4, pH observation can be continued until all of the pH indicator 70 disappears, and the pH is lowered. The power generation was continued by repeating the fuel exchange.
  • the present invention it is possible to easily know a voltage drop due to a hydroxide ion concentration drop in an alkaline fuel cell. Therefore, the timing of fuel replacement can be grasped in a timely manner, and continuous stable power generation becomes possible.
  • the present invention is a technique that makes it possible to lengthen the usage time of a portable small device that is required to be continuously used, while being very simple.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

Disclosed is an alkaline fuel cell wherein the hydroxide ion concentration in a liquid fuel can be easily determined. An alkaline fuel cell comprises an electrode-electrolyte membrane assembly composed of an anion exchange membrane, a cathode arranged in contact with one side of the anion exchange membrane and an anode arranged in contact with the other side of the anion exchange membrane. The electrode-electrolyte membrane assembly is held between a cathode collector (41) and an anode collector (42) respectively arranged in contact with the cathode and the anode. The alkaline fuel cell further comprises a fuel cell container (10) which is at least partially transparent so that the interior thereof can be seen from the outside. The fuel cell container (10) is formed in contact with the anode. Changes in pH of the alkali-containing liquid fuel can be determined from the outside through color changes of a pH-indicating material (70) which is held within the fuel cell container (10).

Description

アルカリ型燃料電池Alkaline fuel cell
　本発明は、アルカリを含む液体燃料を用いたアルカリ型燃料電池に関する。 The present invention relates to an alkaline fuel cell using a liquid fuel containing an alkali.
　固体高分子型燃料電池は、固体高分子電解質膜をアノードとカソードとで挟持した構造の電極－電解質膜接合体（Membrane and Electrode Assembly。以下、ＭＥＡという。）を備えている。液体燃料をアノードに供給するタイプの燃料電池は、ＭＥＡに用いられる固体高分子電解質膜のイオン伝導種によって、反応メカニズムが異なり、その名称でも区別される。近年では、安価で取り扱いの容易な有機液体であるメタノールを燃料として直接利用するダイレクトメタノール型燃料電池（以下、ＤＭＦＣ）の開発が盛んに行われてきた。 The polymer electrolyte fuel cell includes an electrode-electrolyte membrane assembly (hereinafter referred to as MEA) having a structure in which a solid polymer electrolyte membrane is sandwiched between an anode and a cathode. The type of fuel cell that supplies liquid fuel to the anode has a different reaction mechanism depending on the ion conductive species of the solid polymer electrolyte membrane used in MEA, and is distinguished by its name. In recent years, direct methanol fuel cells (hereinafter referred to as DMFC) that directly use methanol, which is an inexpensive and easy-to-handle organic liquid, as a fuel have been actively developed.
　ＤＭＦＣでは、プロトンである酸型燃料電池が一般的であるが、最近では、水酸化物イオンがイオン伝導種であるアルカリ型燃料電池にも注目が集まっている。 In DMFC, an acid fuel cell that is a proton is generally used, but recently, an alkaline fuel cell in which hydroxide ions are ion-conducting species has also attracted attention.
　酸型燃料電池の場合、理想的には、アノードでは式（１）のような反応がおこり、カソードでは式（２）のような反応がおこると解釈されている。 In the case of an acid fuel cell, it is ideally interpreted that a reaction such as formula (1) occurs at the anode and a reaction such as formula (2) occurs at the cathode.
　ＣＨ３ＯＨ　＋　Ｈ２Ｏ　→ＣＯ２　＋　６Ｈ+　+  ６ｅ-　　　・・・式（１） CH 3 OH + H 2 O → CO 2 + 6H + + 6e− Formula (1)
　６Ｈ+　＋　６ｅ-　+  ３／２Ｏ２　→　３Ｈ２Ｏ    ・・・式（２） 6H + + 6e- + 3 / 2O 2 → 3H 2 O Formula (2)
　アルカリ型燃料電池の場合、理想的には、アノードでは式（３）のような反応がおこり、カソードでは式（４）のような反応がおこると解釈されている。 In the case of an alkaline fuel cell, ideally, it is interpreted that a reaction such as formula (3) occurs at the anode and a reaction such as formula (4) occurs at the cathode.
　ＣＨ３ＯＨ　＋　６ＯＨ-　→　５Ｈ２Ｏ　＋　ＣＯ２　＋　６ｅ-   ・・・式（３） CH 3 OH + 6OH − → 5H 2 O + CO 2 + 6e − Formula (3)
　３／２Ｏ２　＋　３Ｈ２Ｏ　＋　６ｅ-　→　６ＯＨ-　　　　　　　・・・式（４） 3 / 2O 2 + 3H 2 O + 6e− → 6OH− Formula (4)
　ただし、カソードで生成した水酸化物イオンは、その全てが固体高分子電解質膜を通じてアノードに到達するわけではなく、電池反応を安定して継続させるためには、液体燃料中のアルカリから補う方が効率的に反応できる。そのため、アルカリ型燃料電池の液体燃料としては、純粋なメタノール水溶液ではなく、ある程度の濃度のアルカリを含ませる方がよい。ただし、液体燃料にアルカリを含むアルカリ型燃料電池では、精製したＣＯ２が即座に炭酸イオンＣＯ３ ２－に変化し、燃料中に溶け込むため、ＣＯ２が気体として放出されにくく、見た目上では気体は発生しない。実際には、式（３）のようにＣＯ２が生成するのではなく、直接ＣＯ３ ２－が生成することも考えられるため、本件で示す内容に関しては、ここで示した反応式で起こる反応のみに限定はしない。 However, not all of the hydroxide ions generated at the cathode reach the anode through the solid polymer electrolyte membrane. In order to continue the cell reaction stably, it is better to supplement from the alkali in the liquid fuel. Can react efficiently. For this reason, it is preferable that the liquid fuel of the alkaline fuel cell contains an alkali having a certain concentration rather than a pure methanol aqueous solution. However, in an alkaline fuel cell that contains alkali in the liquid fuel, the purified CO 2 immediately changes to carbonate ions CO 3 2− and dissolves in the fuel, so that it is difficult for CO 2 to be released as a gas. Does not occur. Actually, it is possible that CO 3 2− is generated directly instead of CO 2 as shown in Equation (3). Therefore, with respect to the contents shown in this case, the reaction occurring in the reaction formula shown here. It is not limited to only.
　このような液体燃料を使用した固体高分子型燃料電池は、小型、軽量化が容易であるために、これまでにも携帯機器をはじめとした種々の電子機器用電源としての研究開発が活発に進められてきた。固体高分子燃料電池の発電部分は、ＭＥＡと呼ばれる発電最小ユニットを基本構成としてもち、さらに、燃料供給や電力の取り出しを行うための構造をもつ燃料電池セルにＭＥＡを搭載することによって、初めて電源としての利用が可能となる。このような燃料電池を、携帯電話等の小型機器の電源や、外付け充電器として使用する場合、外出先で使用することが主用途になるため、より小型な燃料電池が求められている。 Since the polymer electrolyte fuel cell using such a liquid fuel is easy to reduce in size and weight, research and development as a power source for various electronic devices such as portable devices have been actively conducted so far. It has been advanced. The power generation part of a polymer electrolyte fuel cell has a basic power generation minimum unit called MEA, and further power is supplied for the first time by installing the MEA in a fuel cell having a structure for supplying fuel and taking out power. Can be used. When such a fuel cell is used as a power source for a small device such as a mobile phone or an external charger, the main application is to use the fuel cell outside the home. Therefore, a smaller fuel cell is required.
　そのため、燃料電池システムを構成する燃料電池セルの出力密度を高めることが求められてきた。しかし、メタノールのみを燃料とするような酸型燃料電池では、燃料成分であるメタノールのクロスオーバーや、アノードで発生する一酸化炭素ＣＯが触媒金属である白金Ｐｔに吸着被毒することに起因した過電圧の低下などの問題点が、出力密度の向上の妨げとなっている。また、反応で生じる酸に耐えうる触媒として、白金を用いることが必須であるが、白金価格の高騰によって、燃料電池の価格をある程度以下に抑えられないことなどのビジネス上の問題点も浮上してきた。 Therefore, it has been demanded to increase the output density of the fuel cells constituting the fuel cell system. However, in an acid fuel cell that uses only methanol as the fuel, the fuel component methanol crossover and carbon monoxide CO generated at the anode are adsorbed and poisoned by platinum Pt as the catalyst metal. Problems such as a decrease in overvoltage hinder the improvement of output density. In addition, it is essential to use platinum as a catalyst that can withstand the acid generated by the reaction. However, due to the rising price of platinum, business problems such as the fact that the price of fuel cells cannot be kept below a certain level have emerged. It was.
　それに対し、アルカリ型燃料電池では、必ずしも白金などの貴金属を触媒として用いる必要はなく、比較的安い材料を触媒として用いることができ、さらに出力密度も酸型と同等以上である。このような背景から、アルカリ型燃料電池に関する関心も高まってきている。 On the other hand, in an alkaline fuel cell, it is not always necessary to use a noble metal such as platinum as a catalyst, a relatively cheap material can be used as a catalyst, and the output density is equal to or higher than that of an acid type. Against this background, interest in alkaline fuel cells is increasing.
　ところが、アルカリ型燃料電池用途には、酸型燃料電池で使用されているナフィオンを代表とするような、高性能な燃料電池用の固体高分子形電解質が開発されていなかった。そのため、アルカリ型燃料電池では、酸型燃料電池のように、燃料極および酸化剤極と、これらの間に設けられた固体高分子電解質膜から構成されるＭＥＡを基本とする燃料電池セルを、酸型燃料電池用と同様には作製することが難しかった。そのことにより、ＤＭＦＣにおける酸型燃料電池ほど、携帯型小型機器においては、アルカリ型燃料電池の研究開発が発展していなかった。しかしながら、最近では、開発段階ながらも、酸型燃料電池の出力に匹敵するようなポテンシャルを持つアニオン交換膜も出回ってきており、アルカリ型燃料電池をＭＥＡとして評価できる段階になってきた。 However, for alkaline fuel cell applications, high-performance solid polymer electrolytes for fuel cells, such as Nafion used in acid fuel cells, have not been developed. Therefore, in an alkaline fuel cell, as in an acid fuel cell, a fuel cell based on MEA composed of a fuel electrode and an oxidant electrode and a solid polymer electrolyte membrane provided therebetween, It was difficult to produce as in the case of an acid fuel cell. As a result, research and development of alkaline fuel cells has not been developed in portable small devices as much as acid fuel cells in DMFC. However, recently, an anion exchange membrane having a potential comparable to the output of an acid fuel cell has been on the market in the development stage, and the alkaline fuel cell can be evaluated as an MEA.
　現状のアルカリ型燃料電池に用いることができるアニオン交換膜では、いまだに液体燃料にアルカリを加えないと満足な出力密度を得ることはできない。そのため、液体燃料中にはアルカリが添加される必要がある。燃料中の水酸化物イオン濃度が薄くなってくると、出力低下にもつながるため、液体燃料中のメタノール濃度の管理のみならず、水酸化物イオン濃度をなんらかの形で管理できることが求められることになる。現段階ではアルカリ型燃料電池を、燃料電池セルとして評価している例も少ないため、水酸化物イオン濃度管理にまでは目を向けられていないという段階であるが、アルカリ型燃料電池を実用化する上では、今後、水酸化物イオン濃度の管理をリアルタイムで行う必要性が生じてくると考えられる。 In an anion exchange membrane that can be used in current alkaline fuel cells, satisfactory output density cannot be obtained unless alkali is added to the liquid fuel. Therefore, alkali needs to be added to the liquid fuel. As the hydroxide ion concentration in the fuel decreases, it also leads to a decrease in output, so it is required to be able to manage the hydroxide ion concentration in some form as well as the methanol concentration in liquid fuel Become. At present, alkaline fuel cells are not being evaluated as fuel cells, so there are few examples of hydroxide ion concentration management. Alkaline fuel cells have been put to practical use. Therefore, it will be necessary to manage the hydroxide ion concentration in real time in the future.
　水酸化物イオン濃度を測定する手段としては、ｐＨを測定することが挙げられる。たとえば、特許文献１では、燃料電池のアノード燃料として用いる水素ガス濃度を、次亜塩素酸塩などを含む水溶液中に通し、ｐＨの変化によって可視化して水素を検知する方法が提案されている。また、特許文献２では、水素ガスをアノードに供給するタイプの燃料電池であって、燃料電池スタック内部に凝縮した水のｐＨを何らかの手段によって検知し、燃料電池スタック内部の水量を制御する機構によってｐＨを制御することによって、燃料電池スタックの腐食を防止する方法が提案されている。 As a means for measuring the hydroxide ion concentration, it is possible to measure pH. For example, Patent Document 1 proposes a method of detecting hydrogen by passing a hydrogen gas concentration used as an anode fuel of a fuel cell through an aqueous solution containing hypochlorite and the like, and visualizing it by a change in pH. Patent Document 2 is a fuel cell of a type that supplies hydrogen gas to the anode, and detects the pH of water condensed inside the fuel cell stack by some means, and controls the amount of water inside the fuel cell stack. A method for preventing corrosion of the fuel cell stack by controlling the pH has been proposed.
　さらに、特許文献３では、燃料電池の燃料となる水素ガスのボンベを覆う形で、水素を触媒によってプロトン化する部分を設け、その内部にｐＨによって呈色する物質を導入し、そのｐＨ変化を外部から観察することができる窓から色の変化によって水素の漏れを検出する方法が提案されている。このように、水素ガス検知や燃料電池スタック内部の水の酸性度を検知する手段として、ｐＨを用いる方法としては、いくつかの提案がなされている。
特開２００５－３３１２８４号公報 特開２００６－４０６１０号公報 特開２００７－２７８９９４号公報 Furthermore, in Patent Document 3, a portion for protonating hydrogen with a catalyst is provided so as to cover a hydrogen gas cylinder serving as fuel for a fuel cell, and a substance colored by pH is introduced therein, and the pH change is measured. There has been proposed a method for detecting hydrogen leakage by a color change from a window that can be observed from the outside. As described above, several proposals have been made as a method of using pH as a means for detecting the hydrogen gas and the acidity of water inside the fuel cell stack.
Japanese Patent Laid-Open No. 2005-331284 JP 2006-40610 A JP 2007-278994 A
　前述のように、現状の固体高分子電解質を用いたアルカリ型燃料電池では、液体燃料中の水酸化物イオン濃度をリアルタイムで観測する必要がある。例えば、特許文献１、２、３のように、ｐＨを計測する手段を考慮しうるが、いずれも液体燃料のｐＨを直接測定する方法としての具体性には欠けていたり、携帯用小型装置には不向きであったりするため、液体燃料中のｐＨをリアルタイムで知る手段としては導入しがたいのが現状である。 As described above, in the alkaline fuel cell using the current solid polymer electrolyte, it is necessary to observe the hydroxide ion concentration in the liquid fuel in real time. For example, as disclosed in Patent Documents 1, 2, and 3, it is possible to consider means for measuring pH, but none of them are practical as a method for directly measuring pH of liquid fuel, or to portable small devices. Is currently unsuitable, so it is difficult to introduce as a means to know the pH in liquid fuel in real time.
　本発明は、上述した課題を解決するためになされたものであり、液体燃料の水酸化物イオン濃度を容易に判別することが可能なアルカリ型燃料電池を提供することを目的とする。 The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an alkaline fuel cell capable of easily discriminating the hydroxide ion concentration of liquid fuel.
　本発明のアルカリ型燃料電池は、上記課題を解決するため、アニオン交換膜を電解質膜とするＭＥＡからなる燃料電池セルにおいて、アノードに接して設けられた燃料容器の少なくとも一部が透明であり、燃料容器内部の液体燃料の水素イオン濃度によって呈色するｐＨ指示材が導入されていることを特徴とする。 In order to solve the above problems, the alkaline fuel cell of the present invention is a fuel cell composed of MEA having an anion exchange membrane as an electrolyte membrane, and at least a part of a fuel container provided in contact with the anode is transparent, A pH indicator that is colored by the hydrogen ion concentration of the liquid fuel inside the fuel container is introduced.
　本発明のアルカリ型燃料電池は、ｐＨ指示部のｐＨを感受する領域が、ｐＨ８～１４、より好ましくはｐＨ１０～１４のアルカリ性領域にあることを特徴とする。 The alkaline fuel cell of the present invention is characterized in that the pH sensitive region is sensitive to pH 8 to 14, more preferably pH 10 to 14.
　本発明のアルカリ型燃料電池は、ｐＨ指示材の初期形状は、粒状、板状もしくは棒状であること、さらには任意の形状であってもよく、燃料容器内部に納まり、発電に影響を与えない程度の大きさであることを特徴とする。 In the alkaline fuel cell of the present invention, the initial shape of the pH indicator may be granular, plate-like or rod-like, and may be any shape, and is contained in the fuel container and does not affect power generation. It is characterized by a size of about.
　本発明のアルカリ型燃料電池は、ｐＨ指示材が移動しないように、上記燃料容器の内部で、専用の容器にいれることによって、外部化から観察できない位置に移動することを防止することを特徴とする。 The alkaline fuel cell according to the present invention is characterized in that it is prevented from moving to a position where it cannot be observed from externalization by being placed in a dedicated container inside the fuel container so that the pH indicator does not move. To do.
　本発明のアルカリ型燃料電池は、ｐＨ指示材に導入されたｐＨを感受して変色する物質を大量に入れる必要はないため、ｐＨ感受材が液体燃料中に溶解した場合でも、液体燃料の色の変化からｐＨを判別することを特徴とする。 Since the alkaline fuel cell of the present invention does not require a large amount of a substance that changes the color by sensing the pH introduced into the pH indicator, even when the pH sensitive material is dissolved in the liquid fuel, the color of the liquid fuel It is characterized in that the pH is discriminated from the change in.
　本発明のアルカリ型燃料電池は、ｐＨ指示材は、基材に支持されたｐＨ感受材を、液体燃料と触れないように、保護膜で被覆されており、液体燃料のｐＨを知りたいときに、外部からの操作によって保護膜を破ることによって、その時点におけるｐＨを観測することを特徴とする。 In the alkaline fuel cell of the present invention, the pH indicator is covered with a protective film so that the pH sensitive material supported on the substrate does not come into contact with the liquid fuel, and the pH of the liquid fuel is to be known. The pH at that time is observed by breaking the protective film by an external operation.
　本発明のアルカリ型燃料電池は、上記構造をもつｐＨ指示材が複数個搭載され、液体燃料のｐＨを知りたいときに、随時保護膜を破っていくことによって、複数回のｐＨを観測することを特徴とする。 The alkaline fuel cell of the present invention is equipped with a plurality of pH indicator materials having the above-described structure, and when it is desired to know the pH of the liquid fuel, the pH is observed multiple times by breaking the protective film at any time. It is characterized by.
　本発明のアルカリ型燃料電池は、ｐＨ指示材は、燃料容器に燃料を供給するための燃料カートリッジ、もしくは燃料供給経路に保持されることを特徴とする。 The alkaline fuel cell of the present invention is characterized in that the pH indicator is held in a fuel cartridge or a fuel supply path for supplying fuel to the fuel container.
　本発明によれば、アルカリ型燃料電池の発電による水酸化物イオン濃度の低下を、ｐＨ指示材を用いて、リアルタイムで視覚的に捕らえることが可能となるため、燃料交換のタイミングを的確に把握することが可能となる。 According to the present invention, a decrease in hydroxide ion concentration due to power generation of an alkaline fuel cell can be visually captured in real time using a pH indicator, so that the timing of fuel replacement can be accurately grasped. It becomes possible to do.
　以下、本発明の実施形態に係るアルカリ型燃料電池について、図面を参照しつつ説明する。ただし、本発明で例示した構造および構成は、その効果を発現させるための一例であり、その構造および構成は、これ以前および以降に示したものに限定されるわけではない。 Hereinafter, an alkaline fuel cell according to an embodiment of the present invention will be described with reference to the drawings. However, the structure and configuration exemplified in the present invention are examples for exhibiting the effect, and the structure and configuration are not limited to those shown before and after.
（燃料電池セル）
　図１は、本発明の実施形態に関連する燃料電池セル１１の断面図を示したものである。燃料容器１０には、液体燃料６０を貯液できる構造となっている。燃料を注入するための燃料注入口２１が、燃料容器１０に設けられており、適時燃料を補充・交換できるようになっているが、燃料注入口２１は、２つ以上設けられていることが望ましい。燃料容器１０の上には、ＭＥＡ３０が集電体に挟まれてセットされている。具体的には、アノード３２側にはアノード集電体４２、カソード側３１にはカソード集電体４１が位置し、それらの集電体がＭＥＡ３０を挟み込み、集電する構造となっている。ＭＥＡ１３は、アニオン交換膜を挟み込むように、カソード３１とアノード３２が対面する構造になっている（以下、本発明の実施形態においては、アニオン交換膜を、固体高分子電解質膜３３と表記する）。 (Fuel battery cell)
FIG. 1 shows a cross-sectional view of a fuel battery cell 11 relating to an embodiment of the present invention. The fuel container 10 has a structure capable of storing the liquid fuel 60. A fuel injection port 21 for injecting fuel is provided in the fuel container 10 so that fuel can be replenished and replaced in a timely manner. However, two or more fuel injection ports 21 may be provided. desirable. On the fuel container 10, the MEA 30 is set between current collectors. Specifically, an anode current collector 42 is located on the anode 32 side, and a cathode current collector 41 is located on the cathode side 31, and these current collectors sandwich the MEA 30 to collect current. The MEA 13 has a structure in which the cathode 31 and the anode 32 face each other so as to sandwich the anion exchange membrane (hereinafter, in the embodiment of the present invention, the anion exchange membrane is expressed as a solid polymer electrolyte membrane 33). .
　カソード３１およびアノード３２の固体高分子電解質膜３３に接する面には、それぞれカソード触媒層、アノード触媒層が形成されている。また、集電体の間には、絶縁および液体の漏れをシールする目的でシール部材４３が設けられている。これらの発電部分は、基本的には、ねじ止めなどの固定方法によって、燃料容器１０に留められているが、必ずしもねじなどで固定する必要は無く、集電体によって集電することができ、かつ燃料の漏れがない構造でありさえすればよい。このような構造によって、燃料電池セル１１が構成されている。 A cathode catalyst layer and an anode catalyst layer are formed on the surfaces of the cathode 31 and the anode 32 in contact with the solid polymer electrolyte membrane 33, respectively. Further, a seal member 43 is provided between the current collectors for the purpose of sealing insulation and leakage of liquid. These power generation parts are basically fastened to the fuel container 10 by a fixing method such as screwing, but are not necessarily fixed by screws or the like, and can be collected by a current collector. Moreover, it is only necessary that the structure does not leak fuel. The fuel cell 11 is configured by such a structure.
　図１において、燃料容器１０には液体燃料６０が貯液されている。本実施形態においては、液体燃料６０として、メタノール水溶液中にＫＯＨなどのアルカリを溶解した液体燃料６０を用いることを前提とする。燃料容器１０内部には、液体燃料６０をアノード電極３２に効率よく供給させることを目的としたウィッキング材を用いてもよい。ウィッキング材とは、ウレタンなどの発泡素材に形成された連続空孔を通じ、主に毛管力などを駆動力とした燃料供給促進能をもつ。その結果、アノード電極３２に燃料が安定して供給されることになる。 In FIG. 1, the liquid fuel 60 is stored in the fuel container 10. In the present embodiment, it is assumed that a liquid fuel 60 in which an alkali such as KOH is dissolved in an aqueous methanol solution is used as the liquid fuel 60. A wicking material intended to efficiently supply the liquid fuel 60 to the anode electrode 32 may be used inside the fuel container 10. The wicking material has a fuel supply promoting ability mainly using a capillary force as a driving force through continuous pores formed in a foam material such as urethane. As a result, the fuel is stably supplied to the anode electrode 32.
　アルカリ型燃料電池においては、アルカリを液体燃料６０中に含むため、耐アルカリ性を持つ素材を用いたウィッキング材を使用する必要がある。液体燃料６０が消費されることによって形成された部分的な空間にＫＯＨなどのアルカリが析出してしまうことも考えられ、その結果、ウィッキング材の連続空孔が塞がれ、発電に必要な液体燃料６０がアノード電極３２に供給されにくくなることも考えられる。このように、ウィッキング材は必須の要素ではないため、これ以降は省略する。 In an alkaline fuel cell, since alkali is contained in the liquid fuel 60, it is necessary to use a wicking material using an alkali-resistant material. It is conceivable that alkali such as KOH is deposited in the partial space formed by the consumption of the liquid fuel 60. As a result, continuous vacancies in the wicking material are blocked, which is necessary for power generation. It is also conceivable that the liquid fuel 60 is difficult to be supplied to the anode electrode 32. As described above, since the wicking material is not an essential element, the description thereof is omitted.
（燃料）
　本発明の実施形態に係る燃料電池に関しては、前述の通り、メタノール水溶液などのアルコール水溶液にアルカリを溶解させた液体燃料６０を用いる。アルカリとしては、ＫＯＨやＮａＯＨなどを用いることが望ましいが、液体中への溶解やｐＨに限度があるものの、ＣａＯＨやアンモニアなども用いることができる。ただし、液体燃料６０がアルカリ性になるのであれば、前述のようなもの以外の物質を用いることができる。本実施形態においては、液体燃料６０としてメタノール水溶液を用いることを前提としているが、燃料の成分としては、必ずしもメタノールを基本成分としたものに限定されず、エタノールなどのアルコール系燃料、エーテル系燃料などにも適用可能であり、液体燃料６０を用いる燃料電池であれば、燃料成分を限定することはない。また、液体燃料６０は、燃料容器１０からアノード電極３２に何らかの形で供給されればよく、パッシブ型であっても、アクティブ型のような燃料循環供給型であってもよい。液体燃料６０の供給形態に関しては、本発明において限定を加えることはない。 (fuel)
As described above, the fuel cell according to the embodiment of the present invention uses the liquid fuel 60 in which an alkali is dissolved in an alcohol aqueous solution such as a methanol aqueous solution. As the alkali, it is desirable to use KOH, NaOH, or the like, but CaOH, ammonia, or the like can also be used although there is a limit in dissolution in liquid and pH. However, if the liquid fuel 60 becomes alkaline, substances other than those described above can be used. In the present embodiment, it is assumed that an aqueous methanol solution is used as the liquid fuel 60. However, the fuel component is not necessarily limited to one containing methanol as a basic component, but alcohol fuel such as ethanol, ether fuel, and the like. As long as the fuel cell uses the liquid fuel 60, the fuel component is not limited. Further, the liquid fuel 60 may be supplied from the fuel container 10 to the anode electrode 32 in some form, and may be a passive type or a fuel circulation supply type such as an active type. The supply form of the liquid fuel 60 is not limited in the present invention.
（ＭＥＡ）
　ＭＥＡ３０は、固体高分子電解質膜３３をカソード３１とアノード３２とで挟持した構造からなるものである。固体高分子電解質膜３３としては、アニオンすなわち水酸化物イオンの伝導性が高く、かつ、電子伝導性をもたない固体高分子電解質膜３３が使用される。固体高分子電解質膜３３の構成材料としては、塩基等の極性基を有するイオン交換樹脂が好ましいが、現在では、その材料を特定することはできない。また、固体高分子電解質膜３３の膜厚は、その材質や燃料電池の用途等に応じて、５～３００μｍ程度の範囲内で適宜選定可能である。ただし、この膜厚に関しても、ここで示した値が絶対であるわけではない。 (MEA)
The MEA 30 has a structure in which a solid polymer electrolyte membrane 33 is sandwiched between a cathode 31 and an anode 32. As the solid polymer electrolyte membrane 33, a solid polymer electrolyte membrane 33 having high conductivity of anions, that is, hydroxide ions, and having no electronic conductivity is used. As a constituent material of the solid polymer electrolyte membrane 33, an ion exchange resin having a polar group such as a base is preferable, but the material cannot be specified at present. The film thickness of the solid polymer electrolyte membrane 33 can be appropriately selected within the range of about 5 to 300 μm depending on the material, the use of the fuel cell, and the like. However, the values shown here are not absolute with respect to this film thickness.
（電極）
　カソード電極３１は、水と酸素の反応によって水酸化物イオンを生成する電極であり、例えば、触媒をカーボン等の担体に担持させた粒子（粉末を含む）又は担体を有さない触媒単体と、イオン伝導性をもつバインダから成る触媒層を、カーボンペーパー等の基材上に塗布等で形成することにより得ることができる。触媒としては、白金、ロジウム、パラジウム、イリジウム、オスミウム、ルテニウム、レニウム、金、銀、ニッケル、コバルト、モリブデン、ランタン、ストロンチウム、イットリウム等があげられる。触媒は、１種のみでも、２種類以上を組み合わせて用いてもよい。触媒を担持する粒子としては、アセチレンブラック、ケッチェンブラック、カーボンナノチューブ、カーボンナノホーン等の炭素系材料が例示される。粒子の大きさは、例えば炭素系材料が粒状物であるときには、０．０１～０．１μｍ程度の範囲内、好ましくは０．０２～０．０６μｍ程度の範囲内で適宜選定される。粒子に触媒を担持させるには、例えば含浸法を適用することができる。 (electrode)
The cathode electrode 31 is an electrode that generates hydroxide ions by the reaction of water and oxygen. For example, particles (including powder) in which a catalyst is supported on a carrier such as carbon or a catalyst alone having no carrier, A catalyst layer made of a binder having ion conductivity can be obtained by coating or the like on a substrate such as carbon paper. Examples of the catalyst include platinum, rhodium, palladium, iridium, osmium, ruthenium, rhenium, gold, silver, nickel, cobalt, molybdenum, lanthanum, strontium, yttrium, and the like. The catalyst may be used alone or in combination of two or more. Examples of the particles supporting the catalyst include carbon-based materials such as acetylene black, ketjen black, carbon nanotubes, and carbon nanohorns. The size of the particles is appropriately selected, for example, in the range of about 0.01 to 0.1 μm, preferably in the range of about 0.02 to 0.06 μm when the carbonaceous material is a granular material. In order to support the catalyst on the particles, for example, an impregnation method can be applied.
　触媒層が形成される基材としては、固体高分子電解質膜３３を用いることができる。また、カーボンペーパー、カーボンの成形体、カーボンの焼結体、焼結金属、発泡金属等、導電性を有する多孔性物質を用いることもできる。カーボンペーパー等の基材を用いた場合には、基材上に触媒層を形成してカソード電極３１を得た後に、ホットプレス等の方法によって、触媒層が固体高分子電解質膜３３と接する向きでカソード電極３１を固体高分子電解質膜３３に接合することが好ましい。カソード電極３１の単位面積当たりの触媒量は、触媒の種類や大きさ等に応じて、０．１ｍｇ／ｃｍ２～２０ｍｇ／ｃｍ２程度の範囲内で適宜選定可能であるが、求める出力密度によっては、この範囲外の量を塗布することも可能である。 As the base material on which the catalyst layer is formed, the solid polymer electrolyte membrane 33 can be used. In addition, a porous material having conductivity such as carbon paper, a carbon molded body, a carbon sintered body, a sintered metal, and a foamed metal can be used. When a base material such as carbon paper is used, the catalyst layer is formed on the base material to obtain the cathode electrode 31, and then the catalyst layer is in contact with the solid polymer electrolyte membrane 33 by a method such as hot pressing. The cathode electrode 31 is preferably joined to the solid polymer electrolyte membrane 33. The catalyst amount per unit area of the cathode electrode 31, according to the catalyst type and size and the like can be appropriately selected within the range of about 0.1mg / cm 2 ~ 20mg / cm 2, the power density to obtain It is also possible to apply an amount outside this range.
　アノード電極３２は、メタノール水溶液と水酸化物イオンの反応から、水とＣＯ２と電子を生成する電極であり、上記のカソード電極３１と同様にして構成される。アノード電極３２を構成する触媒層や基材は、カソード触媒３１を構成する触媒層や基材と同じであってもよいし、異なっていてもよい。アノード３２の単位面積当たりの触媒量も、カソードの場合と同様、触媒の種類や大きさ等に応じて、０．１ｍｇ／ｃｍ２～２０ｍｇ／ｃｍ２ 程度の範囲内で適宜選定可能であり、求める出力密度によっては、この範囲外の量を塗布することも可能である。また、カソード電極３１、アノード電極３２ともに、触媒層に燃料供給やイオン伝導性を向上させるため、疎水性のＰＴＦＥやアニオン交換樹脂などをバインダの補材として混入させることが好ましいが、水を媒介としたイオン伝導で十分な電池反応を得られるので、現状ではナフィオンなどのプロトン伝導体などを代用することが可能である。 The anode electrode 32 is an electrode that generates water, CO 2, and electrons from a reaction between an aqueous methanol solution and hydroxide ions, and is configured in the same manner as the cathode electrode 31 described above. The catalyst layer and base material constituting the anode electrode 32 may be the same as or different from the catalyst layer and base material constituting the cathode catalyst 31. The catalyst amount per unit area of the anode 32, as in the case of the cathode, depending on the catalyst type and size, etc., may be appropriately selected within the range of about 0.1mg / cm 2 ~ 20mg / cm 2, Depending on the desired power density, it is possible to apply an amount outside this range. In addition, in order to improve fuel supply and ion conductivity in both the cathode electrode 31 and the anode electrode 32, it is preferable to mix hydrophobic PTFE, anion exchange resin, or the like as a binder supplement, but water is mediated. Therefore, it is possible to substitute a proton conductor such as Nafion at present.
（集電体）
　カソード集電体４１及びアノード集電体４２は、カソード電極３１及びアノード電極３２上にそれぞれ接して配され、電子の取出効率及び電子の供給効率を高めるように作用する。これらの集電体４１、４２は、図２に示すように、ＭＥＡ３０の周縁部に接する枠形状のものであってもよいし、ＭＥＡの全面に接する平板状又はメッシュ状等のものであってもよい。その形状に関しては、設計上の都合などに合わせて決めることができる。これらの集電体４１、４２の材料としては、例えば、ステンレス鋼、焼結金属、発泡金属等、又はこれらの金属に高導電性金属材料をメッキ処理したものやカーボン材料などの導電体等を用いることができる。特に、耐アルカリ性が高い材料の方が好ましい。ただし、ＭＥＡ構造自体に集電構造を含んでしまうような燃料電池スタック１５に関しては、ここに示した通りではなく、かならずしも集電体を用いる集電方式でなくてもよい。 (Current collector)
The cathode current collector 41 and the anode current collector 42 are disposed on and in contact with the cathode electrode 31 and the anode electrode 32, respectively, and act to increase the electron extraction efficiency and the electron supply efficiency. As shown in FIG. 2, these current collectors 41 and 42 may have a frame shape in contact with the peripheral portion of the MEA 30, or may have a flat plate shape or mesh shape in contact with the entire surface of the MEA. Also good. The shape can be determined according to the design convenience. Examples of the material of the current collectors 41 and 42 include stainless steel, sintered metal, foam metal, etc., or a conductor such as a carbon material obtained by plating these metals with a highly conductive metal material, or the like. Can be used. In particular, a material having high alkali resistance is preferable. However, the fuel cell stack 15 that includes the current collecting structure in the MEA structure itself is not as shown here, and may not necessarily be a current collecting system using a current collector.
（シール部材）
　本実施形態の燃料電池セル１１には、シール機能を有するシール部材４３が複数設けられている。例えば、図１～５に示すように、固体高分子電解質膜３３とカソード集電体４１との間には、カソード電極３１の厚さとほぼ同じ厚さからなるシール部材４３がセル構造の周縁に枠状に設けられており、固体高分子電解質膜３３とアノード集電体４２との間には、アノード電極３２の厚さとほぼ同じ厚さからなるシール部材４３がセル構造の周縁に枠状に設けられている。アノード集電体４２と燃料容器１０との間には、任意の厚みをもつシール部材４３が設けられている。なお、これらの各シール部材は、必要に応じて、シール性、絶縁性及び弾性を有するものが好ましく、通常はシール機能を有するゴムやプラスチックで形成されている。具体的には、ＰＴＦＥ、ＰＥＴ、ＰＥＥＫ、塩化ビニル等のプラスチック素材や、テフロン（登録商標）ゴム、シリコンゴム、ブチルゴム等のゴム素材で形成することができる。 (Seal member)
The fuel battery cell 11 of the present embodiment is provided with a plurality of sealing members 43 having a sealing function. For example, as shown in FIGS. 1 to 5, a seal member 43 having a thickness substantially the same as the thickness of the cathode electrode 31 is provided between the solid polymer electrolyte membrane 33 and the cathode current collector 41 on the periphery of the cell structure. A seal member 43 having a thickness substantially the same as the thickness of the anode electrode 32 is provided between the solid polymer electrolyte membrane 33 and the anode current collector 42 in a frame shape on the periphery of the cell structure. Is provided. A seal member 43 having an arbitrary thickness is provided between the anode current collector 42 and the fuel container 10. Each of these sealing members preferably has sealing properties, insulating properties, and elasticity as necessary, and is usually formed of rubber or plastic having a sealing function. Specifically, it can be formed of a plastic material such as PTFE, PET, PEEK, or vinyl chloride, or a rubber material such as Teflon (registered trademark) rubber, silicon rubber, or butyl rubber.
　ただし、集電体を必要としないで電気的な接続が可能となるような構造の場合、燃料が漏れないようにシールさえされていればよく、前述のシール部材４３の全てが必須というわけではない。また、耐アルカリ性が高いほど、燃料電池の寿命が長くなるため、長期的な使用に関しては、耐アルカリ性の高い材質、例えばブチルゴムなどを用いることが好ましい。 However, in the case of a structure that allows electrical connection without the need for a current collector, it is only necessary to be sealed so that fuel does not leak, and not all of the sealing members 43 described above are essential. Absent. Also, the higher the alkali resistance, the longer the life of the fuel cell. For long-term use, it is preferable to use a material with high alkali resistance, such as butyl rubber.
（燃料容器）
　燃料容器１０には、燃料注入口２１が設けられている。通常の使用時には、燃料注入口２１には栓２２をして、液体燃料６０が漏れないようになっている。燃料注入口２１は、１つでもよいが、燃料交換しやすいように、また、液体燃料６０を循環供給できるように、複数の燃料注入口２１もしくは放圧弁のようなものを設けてもよい。本実施形態において、燃料注入口２１に関して具体的に制約を加えることはないが、注入した燃料が逆流しないような逆止弁を取り付けておくと、燃料の飛び出しなどが防げるため、より望ましい。 (Fuel container)
A fuel inlet 21 is provided in the fuel container 10. During normal use, the fuel inlet 21 is plugged 22 so that the liquid fuel 60 does not leak. The number of the fuel injection ports 21 may be one, but a plurality of fuel injection ports 21 or a pressure release valve may be provided so that the fuel can be easily exchanged and the liquid fuel 60 can be circulated and supplied. In the present embodiment, there is no specific restriction on the fuel injection port 21, but it is more desirable to attach a check valve that prevents the injected fuel from flowing backward, because it prevents the fuel from jumping out.
　また、燃料容器１０の形状、大きさに制約は無いが、アノード３２に対面する開口部分は、アノード電極表面積と同程度であることが望ましい。また、厚さ方向に関しても、特に制約は設けないが、燃料容器１０の底とアノードまでの距離が離れすぎると、燃料容器１０の底部分に燃料が溜まってしまう傾向が出るため、できれば１つの燃料電池セル１１に対して、１０ｍｍ程度の厚さに収まることが望ましい。また、本発明の実施形態における燃料容器６０に関しては、少なくとも一部に透明な部分があり、外部からｐＨ指示材７０ならびに液体燃料６０の色を確認できることを特徴とする。 Further, although there is no restriction on the shape and size of the fuel container 10, it is desirable that the opening facing the anode 32 has the same surface area as the anode electrode. Also, there is no particular restriction on the thickness direction, but if the distance between the bottom of the fuel container 10 and the anode is too far, fuel tends to accumulate at the bottom of the fuel container 10. It is desirable that the thickness of the fuel battery cell 11 is about 10 mm. Further, the fuel container 60 according to the embodiment of the present invention is characterized in that at least a part of the fuel container 60 is transparent, and the colors of the pH indicator 70 and the liquid fuel 60 can be confirmed from the outside.
（ｐＨ指示材）
　図２、図３、図４、図５は、本発明の実施形態に係るｐＨ指示材７０を挿入した燃料電池セルの例を示す。図２では、ｐＨ指示材７０は、液体燃料６０のｐＨによって変色する物質を塗布または担持したものである。特に、ｐＨが８～１４のアルカリ性の領域、より好ましくは、ｐＨが１０～１４の範囲内で変色することが望ましい。ｐＨ指示材７０の担体、担持する物質に関しては、後述する。また、燃料容器１０内部が目視できるように、燃料容器１０の少なくとも一部は透明であり、ｐＨ指示材７０を外部からみることができる。 (PH indicator)
2, 3, 4, and 5 show examples of fuel cells into which the pH indicator 70 according to the embodiment of the present invention is inserted. In FIG. 2, the pH indicator 70 is applied or supported with a substance that changes color depending on the pH of the liquid fuel 60. In particular, it is desirable that the color change within an alkaline region having a pH of 8 to 14, more preferably within a range of 10 to 14. The carrier of the pH indicator 70 and the substance to be carried will be described later. Further, at least a part of the fuel container 10 is transparent so that the inside of the fuel container 10 can be visually observed, and the pH indicator 70 can be seen from the outside.
　図３には、ｐＨ指示材７０の形状が粒状ではなく、板状であるものを示す。ただし、図２および図３に示したｐＨ指示材の形状は一例であり、その形状は観察できる形状、大きさであれば限定されない。 FIG. 3 shows that the pH indicator 70 has a plate shape rather than a granular shape. However, the shape of the pH indicator shown in FIGS. 2 and 3 is an example, and the shape is not limited as long as the shape and size can be observed.
　図４は、ｐＨ指示材７０が燃料容器１０内部で転がらないように、位置を固定するためのｐＨ指示材容器７１に入れられている。ｐＨ指示材容器７１は、燃料６０がｐＨ指示材７０に触れることを妨げないように、網目状、繊維状、パッチ状などの開口部を持つことを特徴とする。 FIG. 4 shows a pH indicator material container 71 for fixing the position so that the pH indicator material 70 does not roll inside the fuel container 10. The pH indicator material container 71 is characterized by having openings such as a mesh shape, a fiber shape, and a patch shape so as not to prevent the fuel 60 from touching the pH indicator material 70.
　図５は、図３に示したｐＨ指示材７０が特定の場所に固定されている場合、その部位のみ、燃料容器１０に透明な部分を持った指示材観察窓７２を有することを特徴とする。このような部分的な透明部分に関しては、必ずしも図３のような構造に限定して設置するのではなく、図２～図４に示したようにｐＨ指示材７０が可動である場合にも設けることができる。 FIG. 5 is characterized in that, when the pH indicator 70 shown in FIG. 3 is fixed at a specific place, the fuel container 10 has an indicator observation window 72 having a transparent portion only at that portion. . Such a partially transparent portion is not necessarily limited to the structure as shown in FIG. 3, but is also provided when the pH indicator 70 is movable as shown in FIGS. be able to.
　図６は、図２に示した本発明の実施形態に係るｐＨ指示材７０の断面構造を簡略化した図である。ｐＨ指示材７０は、その全体がｐＨ感受材であってもよいが、外部から見える部分のみが変色すればよいため、なんらかの基材７３表面のみにｐＨ感受材を塗布し、ｐＨ感受剤塗布部７４が形成されていればよい。また、感受材自体が液体燃料に溶解するため、基材７３が、ｐＨ感受材の溶解を遅延させる機能をもつことが望ましい。 FIG. 6 is a simplified view of the cross-sectional structure of the pH indicator 70 according to the embodiment of the present invention shown in FIG. The pH indicator 70 may be a pH-sensitive material as a whole, but only the portion visible from the outside needs to be discolored. Therefore, the pH-sensitive material is applied only to the surface of some substrate 73, and a pH-sensitive agent application unit 74 may be formed. Moreover, since the sensitive material itself dissolves in the liquid fuel, it is desirable that the base material 73 has a function of delaying the dissolution of the pH sensitive material.
　基材７３としては、液体燃料６０のｐＨによる変色を見きわめやすくするため、白色、もしくは透明な材質のものがよく、かつ耐アルカリ性・耐アルコール性であることが望ましい。例えば、ＰＴＦＥ、ポリエチレン、ポリプロピレンなどの樹脂材料、アルミナやチタニアなどのセラミックス材料などが適している。また、基材７３を透過してｐＨ指示材７４の色を見る構造にする場合は、基材７３が透明な材質であることが求められ、例えば耐アルカリ性をもつ硬質塩化ビニル、ポリエチレン、ポリプロピレン、ポリアクリロニトリルなどの材料を用いることができる。ただし、耐アルカリ性・耐アルコール性を持つ材料でありさえすれば、ここに記述した材料以外のものでも適用できる。 The base material 73 is preferably made of a white or transparent material, and preferably has alkali resistance and alcohol resistance in order to make it easy to recognize the color change due to the pH of the liquid fuel 60. For example, resin materials such as PTFE, polyethylene, and polypropylene, and ceramic materials such as alumina and titania are suitable. Further, in the case of a structure in which the color of the pH indicator 74 is seen through the base material 73, the base material 73 is required to be a transparent material, for example, hard vinyl chloride, polyethylene, polypropylene having alkali resistance, Materials such as polyacrylonitrile can be used. However, materials other than those described here can be used as long as the materials have alkali resistance and alcohol resistance.
　ｐＨ感受材としては、色素系の有機物を用いることができる。例えば、ｐ-α-ナフトールフタレイン（ｐＨ７．０～９．０で黄～青）、クレゾールレッド（ｐＨ７．２～８．８で黄～赤）、チモールブルー（ｐＨ８．０～９．６で黄～青）、フェノールフタレイン（ｐＨ８．０～１０．０で無色～赤紫、ｐＨ１３．４以上では無色）、チモールフタレイン（ｐＨ９．４～１０．６で無色～青）、アリザリンイエローＲ（ｐＨ１０．１～１２．０で黄～赤）、トロペオリンＯ（ｐＨ１１．０～１３．０で黄～橙褐）などが、ｐＨ８．０～１４．０のアルカリ領域に変色域をもつため、適している。 As the pH sensitive material, a pigment-based organic substance can be used. For example, p-α-naphtholphthalein (yellow to blue at pH 7.0 to 9.0), cresol red (yellow to red at pH 7.2 to 8.8), thymol blue (at pH 8.0 to 9.6) Yellow to blue), phenolphthalein (colorless to magenta at pH 8.0 to 10.0, colorless at pH 13.4 or higher), thymolphthalein (colorless to blue at pH 9.4 to 10.6), alizarin yellow R (Yellow to red at pH 10.1 to 12.0), Tropeolin O (yellow to orange brown at pH 11.0 to 13.0) and the like have a color change range in the alkaline region at pH 8.0 to 14.0. Is suitable.
　ただし、ここで示した変色域は、あくまでも水溶液中での挙動であるため、メタノール水溶液などでは呈色の程度などや変色域に多少の差がある。また、これらの有機物は、アルコール水溶液に溶解してしまうので、基材との親和性によっては、液体燃料６０中に溶解してしまい、液体燃料６０そのものの変色によって、ｐＨを判断することになってしまうが、発電に支障がないかぎり問題はない。ｐＨ感受材としては、ここにあげたものに限らず、アルカリ性領域に変色域をもつ物質であれば特に限定することはない。 However, since the color change range shown here is behavior in an aqueous solution, there is a slight difference in the degree of coloration and the color change range in a methanol aqueous solution. In addition, since these organic substances are dissolved in the alcohol aqueous solution, the organic substances are dissolved in the liquid fuel 60 depending on the affinity with the base material, and the pH is judged by the discoloration of the liquid fuel 60 itself. However, there is no problem as long as power generation is not hindered. The pH-sensitive material is not limited to those listed here, and is not particularly limited as long as it is a substance having a color change region in an alkaline region.
　図７は、本発明の実施形態に係るｐＨ指示材７０の断面図(a)および斜視図(b)である。図８は、本発明の実施形態に係るｐＨ指示材７０の断面図である。図９は、本発明の実施形態に係るｐＨ指示材７０の外観図である。前述のｐＨ感受材は、液体燃料６０に溶解しやすいため、図７に示したように、指示材基材７３にｐＨ感受材を塗布したｐＨ指示部７４を設け、保護部材７５で挟み込み、直接液体燃料６０に触れないようにするとよい。その場合、指示材基材７３もしくは保護部材７５のいずれかもしくは両方が透明であり、いずれかの部材には、ｐＨ指示部７４まで到達する穴を設け、その穴を保護膜７６で封じ、適時保護膜７６を破ることによって、そのときにおける液体燃料６０のｐＨをモニターできるようにすることが望ましい。 FIG. 7 is a cross-sectional view (a) and a perspective view (b) of the pH indicator 70 according to the embodiment of the present invention. FIG. 8 is a cross-sectional view of the pH indicator 70 according to the embodiment of the present invention. FIG. 9 is an external view of the pH indicator 70 according to the embodiment of the present invention. Since the pH sensitive material described above is easily dissolved in the liquid fuel 60, as shown in FIG. 7, the pH indicating portion 74 in which the pH sensitive material is applied is provided on the indicator material base 73, and is sandwiched between the protective members 75 and directly. It is preferable not to touch the liquid fuel 60. In that case, either or both of the indicator material base 73 and the protective member 75 are transparent, and any member is provided with a hole reaching the pH indicator 74, and the hole is sealed with the protective film 76, and the time is appropriate. It is desirable to break the protective film 76 so that the pH of the liquid fuel 60 at that time can be monitored.
　このような構造の場合、必ずしも指示材基材７３に高い耐アルカリ性・耐アルコール性は必要としないため、濾紙などにｐＨ感受材を染み込ませた市販のｐＨ試験紙などを用いることも可能である。また、保護膜７６の素材としては、耐アルカリ性・耐アルコール性をもち、透明な樹脂性の膜などを用いることが望ましい。例えば、ポリエチレンやポリプロピレンなどを用いることができる。また、ｐＨ指示材７０を図８のように複数個設けることによって、複数回にわたってｐＨをモニターすることが可能となる。 In the case of such a structure, the indicator base material 73 does not necessarily require high alkali resistance / alcohol resistance, so it is also possible to use a commercially available pH test paper in which a pH sensitive material is impregnated into filter paper or the like. . Further, as the material of the protective film 76, it is desirable to use a transparent resin film having alkali resistance and alcohol resistance. For example, polyethylene or polypropylene can be used. Further, by providing a plurality of pH indicating materials 70 as shown in FIG. 8, it becomes possible to monitor the pH multiple times.
　ｐＨ指示材７０の保護膜７６を破る方法としては、例えば、図１０に示したように、燃料容器１０の少なくとも一部に弾性を持つ部分（弾性膜７８）を設け、その弾性膜７８に設けた画鋲状突起物７７１を、適時保護膜７６に押し込むことがあげられる。この際の燃料容器１０としては、図５に示したような一部が透明である指示材観察窓７２の部分が弾性膜７８を兼ね、ｐＨ指示材７０自体は、図３のように燃料容器１０の内部に固定されていることが好ましい。 As a method of breaking the protective film 76 of the pH indicator 70, for example, as shown in FIG. 10, an elastic part (elastic film 78) is provided on at least a part of the fuel container 10, and the elastic film 78 is provided. It is possible to push the thumbtack-like protrusion 771 into the protective film 76 in a timely manner. As the fuel container 10 at this time, the part of the indicator material observation window 72 that is partially transparent as shown in FIG. 5 also serves as the elastic film 78, and the pH indicator 70 itself is the fuel container as shown in FIG. 10 is preferably fixed inside.
　ｐＨ指示材７０の保護膜７６を破る他の方法としては、例えば、図１１に示したように、垂直に安定して立てられる強磁性の台座をもったカッター７７２を搭載させ、燃料容器１０外部から磁石付のスライダー７９によって燃料容器１０外部で操作し、保護膜７６を破る方法があげられる。また、カッター７７２に磁石を配置し、スラーダーが強磁性材料からできていてもよい。ここで用いるｐＨ指示材７０としては、図１２のように溝状の凹部分をもつものが好ましく、その凹みにカッター７７２の刃が並行に沿う形で並ぶように配置している。この際、ｐＨ指示材７０自体は、図３のように燃料容器１０の内部に固定されている。 As another method for breaking the protective film 76 of the pH indicator 70, for example, as shown in FIG. And a method of breaking the protective film 76 by operating outside the fuel container 10 with a slider 79 with magnet. Further, a magnet may be disposed on the cutter 772, and the slurder may be made of a ferromagnetic material. As the pH indicator 70 used here, a material having a groove-like concave portion as shown in FIG. 12 is preferable, and the blades of the cutter 772 are arranged in parallel to the concave portion. At this time, the pH indicator 70 itself is fixed inside the fuel container 10 as shown in FIG.
　以上説明したように、本発明の実施形態に係る燃料電池セル１１において、燃料容器１０の外側から、ｐＨ指示材７０ならびに貯液された液体燃料６０を見ることができ、ｐＨ指示材７０または液体燃料６０の色の変化によって液体燃料のｐＨを確認することができるため、式（３）および式（４）に示した電池反応において必要となる水酸化物イオン濃度を確認できるため、電圧低下が起こる前に燃料交換を行うことが可能となる。また、外部負荷などを必要としないため、発電効率などにも影響がおよびにくいというメリットもある。また、ｐＨ指示材７０に関しては、必ずしも燃料容器１０内部に直接設置する必要はなく、燃料供給するためのカートリッジや、燃料供給流路内部などに設置することも可能であるため、アルカリ型燃料電池の使用の幅を広げることを可能とする。 As described above, in the fuel cell 11 according to the embodiment of the present invention, the pH indicator 70 and the stored liquid fuel 60 can be seen from the outside of the fuel container 10, and the pH indicator 70 or the liquid can be seen. Since the pH of the liquid fuel can be confirmed by the change in the color of the fuel 60, the hydroxide ion concentration required in the cell reaction shown in the formulas (3) and (4) can be confirmed, so that the voltage drop is reduced. It is possible to change the fuel before it happens. In addition, since no external load is required, there is a merit that the power generation efficiency is hardly affected. Further, the pH indicator 70 does not necessarily have to be directly installed in the fuel container 10, and can be installed in a cartridge for supplying fuel or in the fuel supply channel. It is possible to widen the range of use.
　以下、実施例を示すことにより、本発明の燃料電池の例について具体的に説明する。 Hereinafter, examples of the fuel cell of the present invention will be specifically described by showing examples.
（実施例１）
　実施例で用いた燃料電池セルの構造について以下に説明する。先ず、炭素粒子（ライオン社製のケッチェンブラックＥＣ６００ＪＤ）に粒子径が３～５ｎｍの範囲内にある白金微粒子を重量比で５０％担持させた触媒担持炭素微粒子を用意し、この触媒担持炭素微粒子１ｇにデュポン社製の５重量％ナフィオン溶液（商品名；ＤＥ５２１、「ナフィオン」はデュポン社の登録商標）を加え、攪拌して、触媒ペーストを得た。この触媒ペーストを基材としてのカーボンペーパー（東レ社製のＴＧＰＨ－１２０）上に1～８ｍｇ／ｃｍ２の塗工量で塗布し、乾燥させて、４ｃｍ×４ｃｍのカソード電極３１およびアノード電極３２を作製した。 Example 1
The structure of the fuel cell used in the examples will be described below. First, catalyst-supported carbon particles are prepared by supporting 50% by weight of platinum particles having a particle diameter in the range of 3 to 5 nm on carbon particles (Ketjen Black EC600JD manufactured by Lion Corporation). To 1 g, a 5 wt% Nafion solution (trade name: DE521, “Nafion” is a registered trademark of DuPont) manufactured by DuPont was added and stirred to obtain a catalyst paste. This catalyst paste was applied to carbon paper (TGPH-120 manufactured by Toray Industries, Inc.) at a coating amount of 1 to 8 mg / cm 2 and dried to be a 4 cm × 4 cm cathode electrode 31 and anode electrode 32. Was made.
　次に、トクヤマ社製のアルカリ型高分子電解質膜（６ｃｍ×６ｃｍ×厚さ５０μｍ）を固体高分子電解質膜３３として用い、この膜の厚さ方向の一方の面に、上記カソード電極３１を、触媒を塗布していない面が外側となる向きで配置し、他の面に上記アノード電極３２のアノード触媒を塗布していない面が外側となる向きで同様に配置し、触媒を塗った電極面同士が固体高分子電解質膜３３を介して対面するように、各カーボンペーパーの外側から圧力を印加してホットプレスした。このようにして、ＭＥＡ１３を作製した。 Next, an alkaline polymer electrolyte membrane (6 cm × 6 cm × 50 μm thickness) manufactured by Tokuyama Corporation was used as the solid polymer electrolyte membrane 33, and the cathode electrode 31 was placed on one surface in the thickness direction of the membrane. An electrode surface in which the surface to which the catalyst is not applied is arranged in the direction facing outside, and the surface in which the anode catalyst of the anode electrode 32 is not coated on the other surface is similarly arranged in the direction to be outside, and the electrode is coated with the catalyst. Hot pressing was performed by applying pressure from the outside of each carbon paper so that they face each other through the solid polymer electrolyte membrane 33. In this way, MEA 13 was produced.
　次に、カソード電極３１とアノード電極３２の上に、ステンレス鋼（ＳＵＳ３１６）からなる外寸法５cm×５cm、内寸法３．８cm×３．８cm、厚さ１．０mmの矩形枠状の枠板からなるカソード集電体４１およびアノード集電耐４２を、カソード３１側とアノード３２側の両面に配置し、ねじ止めすることで燃料容器１０に固定した。 Next, on the cathode electrode 31 and the anode electrode 32, a rectangular frame-shaped frame plate having an outer dimension of 5 cm × 5 cm, an inner dimension of 3.8 cm × 3.8 cm, and a thickness of 1.0 mm made of stainless steel (SUS316). The cathode current collector 41 and the anode current resistance 42 were arranged on both the cathode 31 side and the anode 32 side and fixed to the fuel container 10 by screwing.
　燃料容器１０は、前述の集電体と同じ外寸法をもち、その一部は図５に示したような透明な部分をもつ。全体の厚みは５ｍｍ、内側の燃料タンク部１２の深さは３ｍｍとし、図１に示したような断面構造をもつ。アノード３２と燃料容器１０の間には、ブチルゴム製のシール部材４３を配置させ、液漏れを防いだ。燃料容器１０内部には、図５に示したような指示材観察窓７２近傍に、ｐＨ指示材７０を配置し、燃料容器１０内部でｐＨ指示材７０が転がったりしないように、ｐＨ指示材７０をメッシュ状のｐＨ指示材容器に入れた。ｐＨ指示材７０には、ｐＨ感受材として、アルカリ性では赤色であり、ｐＨが低下すると黄色に変色するアリザリンイエローＲを、直径１ｍｍの粒状多孔質アルミナ基材に塗布したものを用いた。 The fuel container 10 has the same outer dimensions as the above-described current collector, and a part thereof has a transparent portion as shown in FIG. The overall thickness is 5 mm, the depth of the inner fuel tank 12 is 3 mm, and the cross-sectional structure is as shown in FIG. Between the anode 32 and the fuel container 10, a seal member 43 made of butyl rubber was disposed to prevent liquid leakage. A pH indicator 70 is arranged in the vicinity of the indicator observation window 72 as shown in FIG. 5 inside the fuel container 10 so that the pH indicator 70 does not roll inside the fuel container 10. Was placed in a mesh-shaped pH indicator container. The pH indicator 70 used was a pH-sensitive material in which Alizarin Yellow R, which is alkaline in red and turns yellow when the pH is lowered, is applied to a granular porous alumina substrate having a diameter of 1 mm.
　燃料容器１０には、燃料注入口２１から、ＫＯＨが３Ｍの濃度となる１５ｖｏｌ％メタノール水溶液を満たしたのち、燃料が漏れないように栓２２をした。 The fuel container 10 was filled with a 15 vol% methanol aqueous solution having a KOH concentration of 3M from the fuel inlet 21 and then plugged so as not to leak fuel.
（実施例２）
　実施例２では、上記実施例１で用いたｐＨ指示材７０の変わりに、図７に示したようなｐＨ指示材７０を単独で用いた。燃料容器１０としては、図５のように、一部に透明な弾性膜７８を設けており、弾性膜７８を通じて図８のような画鋲状突起物７７１を押し込むことによって、保護膜７６を破き、そこから入り込んだ液体燃料６０がｐＨ指示部７４に触れたことによる変色によって、ｐＨを観測した。 (Example 2)
In Example 2, instead of the pH indicator 70 used in Example 1, the pH indicator 70 as shown in FIG. 7 was used alone. As shown in FIG. 5, the fuel container 10 is partially provided with a transparent elastic film 78. By pushing a thumbtack-like projection 771 as shown in FIG. 8 through the elastic film 78, the protective film 76 is broken. The pH was observed by the discoloration caused by the liquid fuel 60 entering from the pH indicator 74 being touched.
（実施例３）
　実施例３では、上記実施例２で用いたｐＨ指示材７０の変わりに、図１０に示したように、ｐＨ指示材７０を複数個並べたものを用いた。燃料容器１０としては、図５のように、一部に透明な弾性膜７８を設けており、弾性膜７８を通じて図８のような画鋲状突起物７７１を押し込むことによって、保護膜７６を破き、そこから入り込んだ液体燃料６０がｐＨ指示部７４に触れたことによる変色によって、ｐＨを観測した。観測時間は、発電開始から１時間おきにおこない、電圧低下が見られた時点では、適時観測を行った。 (Example 3)
In Example 3, instead of the pH indicator 70 used in Example 2, a plurality of pH indicators 70 arranged as shown in FIG. 10 were used. As shown in FIG. 5, the fuel container 10 is partially provided with a transparent elastic film 78. By pushing a thumbtack-like projection 771 as shown in FIG. 8 through the elastic film 78, the protective film 76 is broken. The pH was observed by the discoloration caused by the liquid fuel 60 entering from the pH indicator 74 being touched. The observation time was taken every hour from the start of power generation, and when a voltage drop was observed, timely observation was performed.
（実施例４）
　実施例４では、実施例３で用いたｐＨ指示材７０の変わりに、図１１に示したように、ｐＨ指示材７０を複数個並べたものを用いた。ただし、ｐＨ指示材７０の形状は、上述した図１２に示すような形状にした。燃料容器１０としては、図５のように、一部に透明な指示材観測窓７２を設けたものを用いた。燃料容器１０の内側には、容器内部で倒れることのないように、強磁性の台座の付いたカッター７７２をｐＨ指示部７０の溝に沿う形で設置し、外側には、磁石を搭載したスライダー７９を設置し、カッター７７２とスライダー７９が、燃料容器１０の壁を挟んで引かれあうようにセットした。ｐＨの観測を行うときには、スラーダー７９を動かして、カッター７７２を移動させることによって保護膜７６を破き、そこから入り込んだ液体燃料６０がｐＨ指示部７４に触れたことによる変色によって、ｐＨを観測した。観測時間は、発電開始から１時間おきにおこない、電圧低下が見られた時点では、適時観測を行った。 Example 4
In Example 4, instead of the pH indicator 70 used in Example 3, a plurality of pH indicators 70 arranged as shown in FIG. 11 were used. However, the shape of the pH indicator 70 was as shown in FIG. As the fuel container 10, as shown in FIG. 5, a part provided with a transparent indicator observation window 72 is used. Inside the fuel container 10, a cutter 772 with a ferromagnetic base is installed along the groove of the pH indicator 70 so as not to fall inside the container, and on the outside is a slider equipped with a magnet. 79 was installed, and the cutter 772 and the slider 79 were set so as to be pulled across the wall of the fuel container 10. When observing pH, the slurder 79 is moved and the cutter 772 is moved to break the protective film 76, and the pH is observed by discoloration caused by the liquid fuel 60 entering from the pH touching part 74. did. The observation time was taken every hour from the start of power generation, and when a voltage drop was observed, timely observation was performed.
　このように作製した燃料電池１０について、１．０Ａにおける定電流発電試験を行った。 The constant current power generation test at 1.0 A was performed on the fuel cell 10 thus manufactured.
　実施例１では、３０分ほどでｐＨ指示材７０から大部分のｐＨ感受材が溶解し、液体燃料６０が赤色に色づいた。３時間程度発電させたあたりから、液体燃料６０の変色が始まり、３時間半では黄色くなった。その後１０分ほどしてから、０．４５Ｖほどで推移してきた電圧値がやや低下し始め、０．４０Ｖを下回ってしまった。そこで、液体燃料６０を即座に交換したところ、それまでの電圧値に近い値（０．４４Ｖ）に戻ったことを確認できた。再現性をみるため、同様の実験を５回繰り返したが、いずれも同様の結果となった。 In Example 1, most of the pH sensitive material was dissolved from the pH indicator 70 in about 30 minutes, and the liquid fuel 60 was colored red. The discoloration of the liquid fuel 60 started from around 3 hours of power generation, and turned yellow after 3 and a half hours. After about 10 minutes, the voltage value that had been changing at about 0.45V started to decrease slightly, and was below 0.40V. Therefore, when the liquid fuel 60 was immediately replaced, it was confirmed that the liquid fuel 60 returned to a value close to the voltage value (0.44 V). To see the reproducibility, the same experiment was repeated five times, and all of them had the same result.
　実施例２では、３時間を越えたあたりで、それまで０．４５Ｖ程度で推移してきた電圧値がやや低下し始め、０．４０Ｖを下回ってしまった。そこで、ｐＨ指示材７０の保護膜７６を破ったところ、ｐＨ低下が観測された。その段階で液体燃料６０を即座に交換したところ、それまでの電圧値は０．４５Ｖに戻った。再現性をみるため、同様の実験を５回繰り返したが、いずれも同様の結果となった。 In Example 2, the voltage value that had been transitioning to about 0.45 V until then began to decrease slightly after about 3 hours, and was below 0.40 V. Therefore, when the protective film 76 of the pH indicator 70 was broken, a pH drop was observed. When the liquid fuel 60 was immediately replaced at that stage, the voltage value so far returned to 0.45V. To see the reproducibility, the same experiment was repeated five times, and all of them had the same result.
　実施例３および実施例４については、３時間まではｐＨ指示部７４はｐＨが十分高いことを示す色が観測されており、０．４５Ｖ程度で電圧が安定して推移してきたが、３時間を越えてしばらくしてから０．４０Ｖ以下まで電圧が低下してきたため、ｐＨ観測を行ったところ、ｐＨ低下が観測された。そのため、燃料交換を行った。その結果、電圧は元の０．４５Ｖまで戻った。実施例１および実施例２では、一度燃料交換を行った後にｐＨ観測できなくなるが、実施例３および実施例４に関しては、ｐＨ指示材７０の全てがなくなるまで、ｐＨ観測を継続でき、ｐＨ低下に及んで燃料交換を繰り返すことによって、発電を継続することができた。 For Example 3 and Example 4, until 3 hours, the pH indicating unit 74 has a color indicating that the pH is sufficiently high, and the voltage has been stable at about 0.45 V, but for 3 hours. After a while, the voltage dropped to 0.40 V or less, and when pH was observed, a pH drop was observed. Therefore, the fuel was changed. As a result, the voltage returned to the original 0.45V. In Example 1 and Example 2, it becomes impossible to observe pH after refueling once. However, in Example 3 and Example 4, pH observation can be continued until all of the pH indicator 70 disappears, and the pH is lowered. The power generation was continued by repeating the fuel exchange.
　このように、本発明により、アルカリ型燃料電池における水酸化物イオン濃度低下による電圧低下を簡便に知ることができる。そのため、燃料交換のタイミングを適時に把握することができ、継続した安定発電が可能になる。本発明は、非常に簡便でありながら、連続使用が求められる携帯型小型機器などの使用時間を長くすることを可能にする技術である。 Thus, according to the present invention, it is possible to easily know a voltage drop due to a hydroxide ion concentration drop in an alkaline fuel cell. Therefore, the timing of fuel replacement can be grasped in a timely manner, and continuous stable power generation becomes possible. The present invention is a technique that makes it possible to lengthen the usage time of a portable small device that is required to be continuously used, while being very simple.
　この出願は、２００８年３月１２日に出願された日本出願特願２００８－０６２９４５を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2008-062945 filed on Mar. 12, 2008, the entire disclosure of which is incorporated herein.
本発明の実施形態に関連する燃料電池を示す断面図である。It is sectional drawing which shows the fuel cell relevant to embodiment of this invention. 本発明の実施形態に係る燃料電池の例を示す断面図である。It is sectional drawing which shows the example of the fuel cell which concerns on embodiment of this invention. 本発明の実施形態に係る燃料電池の例を示す断面図である。It is sectional drawing which shows the example of the fuel cell which concerns on embodiment of this invention. 本発明の実施形態に係る燃料電池の例を示す断面図である。It is sectional drawing which shows the example of the fuel cell which concerns on embodiment of this invention. 本発明の実施形態に係る燃料電池の例を示す断面図である。It is sectional drawing which shows the example of the fuel cell which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の断面の一例である。It is an example of the cross section of the pH indicator 70 which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の断面図(a)および斜視図(b)であるIt is sectional drawing (a) and perspective view (b) of the pH indicator 70 which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の断面図である。It is sectional drawing of the pH indicator 70 which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の外観図である。It is an external view of the pH indicator 70 which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の断面図である。It is sectional drawing of the pH indicator 70 which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の断面図である。It is sectional drawing of the pH indicator 70 which concerns on embodiment of this invention. 本発明の実施形態に係るｐＨ指示材７０の断面図(a)および斜視図(b)である。It is sectional drawing (a) and perspective view (b) of the pH indicator 70 which concerns on embodiment of this invention.
符号の説明Explanation of symbols
　１０　　燃料容器
　１１　　燃料電池セル
　２１　　燃料注入口
　２２　　栓
　３０　　ＭＥＡ
　３１　　カソード電極
　３２　　アノード電極
　３３　　固体高分子電解質膜
　４１　　カソード集電体
　４２　　アノード集電体
　４３　　シール部材
　６０　　液体燃料
　７０　　ｐＨ指示材
　７１　　ｐＨ指示材容器
　７２　　指示材観察窓
　７３　　基材
　７４　　ｐＨ指示部
　７５　　保護部材
　７６　　保護膜
　７８　　弾性膜
　７９　　スライダー
　７７１　　画鋲状突起物
　７７２　　カッター DESCRIPTION OF SYMBOLS 10 Fuel container 11 Fuel cell 21 Fuel inlet 22 Plug 30 MEA
31 Cathode electrode 32 Anode electrode 33 Solid polymer electrolyte membrane 41 Cathode current collector 42 Anode current collector 43 Seal member 60 Liquid fuel 70 pH indicator 71 pH indicator material container 72 Indicator material observation window 73 Substrate 74 pH indicator 75 Protective member 76 Protective film 78 Elastic film 79 Slider 771 Thumbtack-like projection 772 Cutter

Claims (15)

  1. 　アニオン交換膜と、前記アニオン交換膜の一方の面に接して配されたカソードと、他方の面に接して配されたアノードと、で形成された電極－電解質膜接合体が、前記カソード及び前記アノードにそれぞれ接して配されたカソード集電体及びアノード集電体とで挟持され、さらに前記アノードに接して設けられ、少なくとも一部が透明である燃料容器を有するアルカリ型燃料電池であって、
    　前記燃料容器内部に保持されるｐＨ指示材の色の変化によって、アルカリを含む前記液体燃料のｐＨ変化を、外部から判別することを特徴とするアルカリ型燃料電池。     An electrode-electrolyte membrane assembly formed of an anion exchange membrane, a cathode disposed in contact with one surface of the anion exchange membrane, and an anode disposed in contact with the other surface, the cathode and the electrode An alkaline fuel cell having a fuel container sandwiched between a cathode current collector and an anode current collector disposed in contact with each anode, and further provided in contact with the anode, wherein at least a part is transparent.
    An alkaline fuel cell characterized in that the pH change of the liquid fuel containing alkali is discriminated from the outside based on a change in the color of the pH indicator held inside the fuel container.
  2. 　前記ｐＨ指示部のｐＨを感受する領域は、ｐＨ８～１４のアルカリ性領域にあることを特徴とする請求項１記載のアルカリ型燃料電池。 2. The alkaline fuel cell according to claim 1, wherein the pH sensing part is sensitive to a pH in an alkaline range of pH 8-14.
  3. 　前記ｐＨ指示材は、基材とｐＨ感受材の複合体であることを特徴とする請求項１又は２記載のアルカリ型燃料電池。 3. The alkaline fuel cell according to claim 1, wherein the pH indicator is a composite of a base material and a pH sensitive material.
  4. 　前記ｐＨ指示材の初期形状は、粒状であることを特徴とする請求項１から３のいずれか１項に記載のアルカリ型燃料電池。 The alkaline fuel cell according to any one of claims 1 to 3, wherein the initial shape of the pH indicator is granular.
  5. 　前記ｐＨ指示材の初期形状は、板状であることを特徴とする請求項１から３のいずれか１項に記載のアルカリ型燃料電池。 The alkaline fuel cell according to any one of claims 1 to 3, wherein an initial shape of the pH indicator is a plate shape.
  6. 　前記ｐＨ指示材の初期形状は、棒状であることを特徴とする請求項１から３のいずれか１項に記載のアルカリ型燃料電池。 The alkaline fuel cell according to any one of claims 1 to 3, wherein an initial shape of the pH indicator is a rod shape.
  7. 　前記ｐＨ指示材は、前記液体燃料に触れられる孔をもつ容器にいれられていることを特徴とする請求項１から６のいずれか１項に記載のアルカリ型燃料電池。 The alkaline fuel cell according to any one of claims 1 to 6, wherein the pH indicator is contained in a container having a hole that is in contact with the liquid fuel.
  8. 　前記ｐＨ指示材に導入されたｐＨを感受して変色する物質が、前記液体燃料中に溶解し、ｐＨの判別は、前記液体燃料の色によって行うことを特徴とする請求項１から６のいずれか１項に記載のアルカリ型燃料電池。 7. The substance according to claim 1, wherein a substance that senses and changes color when introduced to the pH indicator is dissolved in the liquid fuel, and the pH is determined by the color of the liquid fuel. The alkaline fuel cell according to claim 1.
  9. 　前記ｐＨ指示材は、前記基材に支持された前記ｐＨ感受材を、前記液体燃料と触れないように保護膜で被覆し、前記液体燃料のｐＨを知りたいときに、外部からの操作によって前記保護膜を破り、その時点におけるｐＨを観測することを特徴とする請求項３から８のいずれか１項に記載のアルカリ型燃料電池。 The pH indicator is covered with a protective film so that the pH sensitive material supported by the base material does not come into contact with the liquid fuel, and when it is desired to know the pH of the liquid fuel, the pH indicator is operated by an external operation. The alkaline fuel cell according to any one of claims 3 to 8, wherein the protective film is broken and the pH at that time is observed.
  10. 　前記燃料容器の少なくとも一部が弾性を有し、前記弾性部分の前記燃料容器の内側に、先端の尖った部材を設け、外部から前記弾性部分を押すことにより、前記保護膜を破ることを特徴とする請求項９記載のアルカリ型燃料電池。 At least a part of the fuel container has elasticity, a member having a pointed tip is provided inside the fuel container of the elastic part, and the protective film is broken by pushing the elastic part from the outside. The alkaline fuel cell according to claim 9.
  11. 　前記燃料容器の内側に、強磁性材料を構造中に有する先端の尖った部材を設け、前記燃料容器の外側には、磁石を構造中に有するスライダーを設け、前記スライダーを移動させることにより前記先端の尖った部材が前記燃料容器内部で移動し、前記保護膜を破ることを特徴とする請求項９記載のアルカリ型燃料電池。 A pointed member having a ferromagnetic material in the structure is provided inside the fuel container, a slider having a magnet in the structure is provided outside the fuel container, and the tip is moved by moving the slider. The alkaline fuel cell according to claim 9, wherein a pointed member moves inside the fuel container and breaks the protective film.
  12. 　前記燃料容器の内側に、磁石を構造中に有する先端の尖った部材を設け、前記燃料容器の外側には、強磁性の部材もしくは磁石を構造中に有するスライダーを設け、前記スライダーを移動させることにより前記先端の尖った部材が前記燃料容器内部で移動し、前記保護膜を破ることを特徴とする請求項９記載のアルカリ型燃料電池。 A pointed member having a magnet in the structure is provided inside the fuel container, and a slider having a ferromagnetic member or magnet in the structure is provided outside the fuel container, and the slider is moved. 10. The alkaline fuel cell according to claim 9, wherein the pointed member moves inside the fuel container to break the protective film.
  13. 　前記ｐＨ指示材を複数個設け、前記液体燃料のｐＨを知りたいときに、随時前記保護膜を破ることにより、複数回のｐＨの観測を行うことを特徴とする請求項９から１２のいずれか１項に記載のアルカリ型燃料電池。 The pH is observed a plurality of times by breaking the protective film as needed when providing a plurality of the pH indicator and knowing the pH of the liquid fuel. 2. The alkaline fuel cell according to item 1.
  14. 　前記ｐＨ指示材は、前記燃料容器に燃料を供給するための燃料カートリッジに設けられることを特徴とする請求項１から６のいずれか１項に記載のアルカリ型燃料電池。 The alkaline fuel cell according to any one of claims 1 to 6, wherein the pH indicator is provided in a fuel cartridge for supplying fuel to the fuel container.
  15. 　前記ｐＨ指示材は、前記燃料容器に燃料を供給するための燃料供給経路に設けられることを特徴とする請求項１から６のいずれか１項に記載のアルカリ型燃料電池。 7. The alkaline fuel cell according to claim 1, wherein the pH indicator is provided in a fuel supply path for supplying fuel to the fuel container.
PCT/JP2009/054518 2008-03-12 2009-03-10 Alkaline fuel cell WO2009113523A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2010502821A JPWO2009113523A1 (en) 2008-03-12 2009-03-10 Alkaline fuel cell

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2008062945 2008-03-12
JP2008-062945 2008-03-12

Publications (1)

Publication Number Publication Date
WO2009113523A1 true WO2009113523A1 (en) 2009-09-17

Family

ID=41065190

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2009/054518 WO2009113523A1 (en) 2008-03-12 2009-03-10 Alkaline fuel cell

Country Status (2)

Country Link
JP (1) JPWO2009113523A1 (en)
WO (1) WO2009113523A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101294182B1 (en) * 2011-11-14 2013-08-08 현대자동차주식회사 Apparatus and method for testing electrolyte membrane in fuel cell
KR101926867B1 (en) * 2012-07-30 2018-12-07 현대자동차주식회사 Pin hole inspection apparatus for MEA of fuel cell
CN109755624A (en) * 2017-11-07 2019-05-14 现代自动车株式会社 Fuel cell pack

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004206885A (en) * 2002-12-20 2004-07-22 Tdk Corp Fuel cell
JP2004273220A (en) * 2003-03-06 2004-09-30 Tohoku Ricoh Co Ltd Fuel cell
JP2006040610A (en) * 2004-07-23 2006-02-09 Nissan Motor Co Ltd Fuel cell system
JP2006107886A (en) * 2004-10-04 2006-04-20 Matsushita Electric Ind Co Ltd Humidifying apparatus, humidifying method, and fuel cell power generation system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004206885A (en) * 2002-12-20 2004-07-22 Tdk Corp Fuel cell
JP2004273220A (en) * 2003-03-06 2004-09-30 Tohoku Ricoh Co Ltd Fuel cell
JP2006040610A (en) * 2004-07-23 2006-02-09 Nissan Motor Co Ltd Fuel cell system
JP2006107886A (en) * 2004-10-04 2006-04-20 Matsushita Electric Ind Co Ltd Humidifying apparatus, humidifying method, and fuel cell power generation system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101294182B1 (en) * 2011-11-14 2013-08-08 현대자동차주식회사 Apparatus and method for testing electrolyte membrane in fuel cell
KR101926867B1 (en) * 2012-07-30 2018-12-07 현대자동차주식회사 Pin hole inspection apparatus for MEA of fuel cell
CN109755624A (en) * 2017-11-07 2019-05-14 现代自动车株式会社 Fuel cell pack

Also Published As

Publication number Publication date
JPWO2009113523A1 (en) 2011-07-21

Similar Documents

Publication Publication Date Title
US7413824B2 (en) Direct oxidation fuel cell with a divided fuel tank having a movable barrier pressurized by anode effluent gas
EP2254183B1 (en) Fuel cell with proton conducting membrane
de Leon et al. A direct borohydride—Acid peroxide fuel cell
Scott et al. Performance of a direct methanol alkaline membrane fuel cell
Liu et al. Influences of fuel crossover on cathode performance in a micro borohydride fuel cell
CN101794895A (en) Ionic layer with oxygen evolution reaction catalyst for electrode protection
US6855443B2 (en) Electrochemical device
KR20140000681A (en) Anode-side catalyst composition for fuel cells, and membrane electrode assembly (mea) for solid polymer fuel cells which comprises same
Li et al. CeO 2 doped Pt/C as an efficient cathode catalyst for an air-cathode single-chamber microbial fuel cell
JP4336182B2 (en) Operation method of fuel cell system and fuel cell system
WO2009113523A1 (en) Alkaline fuel cell
JP2005251434A (en) Fuel cell system, and control method of fuel cell
Wang et al. A high-performance direct methanol fuel cell with a polymer fiber membrane and RuO 2/CNTs as a cathode catalyst
Lam et al. Novel approach to membraneless direct methanol fuel cells using advanced 3D anodes
JP5470996B2 (en) Fuel cell
JPWO2007046231A1 (en) Fuel cell system and fuel cell
US10090552B2 (en) Liquid fuel battery
KR20060001536A (en) Electrode for fuel cell and fuel cell comprising same
US8026017B2 (en) High voltage methanol fuel cell assembly using proton exchange membranes and base/acid electrolytes
WO2009113524A1 (en) Alkaline fuel cell
Limjeerajarus et al. Analysis of oxygen reduction reaction activity of Pt/C catalysts for actual PEFC MEAs
Hu Proton Transport and Durability of Polymer Electrolyte Membrane Fuel Cells’ Catalyst Layer
Hinds In situ Mapping of Electrode Potential in a PEMFC
US20110287338A1 (en) Low level cerium mitigation with electrode edge protection
US20120292183A1 (en) Stand-Alone Water Detection Device That Includes a Hydrogen Source

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09719333

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2010502821

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09719333

Country of ref document: EP

Kind code of ref document: A1