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WO2005050763A1 - Systeme de piles a combustible microfluidique et procede pour des applications d'energie portable - Google Patents

Systeme de piles a combustible microfluidique et procede pour des applications d'energie portable Download PDF

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Publication number
WO2005050763A1
WO2005050763A1 PCT/US2004/038653 US2004038653W WO2005050763A1 WO 2005050763 A1 WO2005050763 A1 WO 2005050763A1 US 2004038653 W US2004038653 W US 2004038653W WO 2005050763 A1 WO2005050763 A1 WO 2005050763A1
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Prior art keywords
fuel
liquid
fuel cell
gas
gaseous
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English (en)
Inventor
Dominic Gervasio
Frederic Zenhausern
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University of Arizona
Arizona's Public Universities
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University of Arizona
Arizona's Public Universities
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
    • C01B3/065—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents from a hydride
    • 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
    • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
    • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
    • H01M8/065—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants by dissolution of metals or alloys; by dehydriding metallic substances
    • 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
    • H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1067—Polymeric electrolyte materials characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/06—Integration with other chemical processes
    • C01B2203/066—Integration with other chemical processes with fuel cells
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/10—Catalysts for performing the hydrogen forming reactions
    • C01B2203/1041—Composition of the catalyst
    • C01B2203/1047—Group VIII metal catalysts
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/14—Details of the flowsheet
    • C01B2203/148—Details of the flowsheet involving a recycle stream to the feed of the process for making hydrogen or synthesis gas
    • 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
    • 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
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
    • 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 generally concerns fuel cell technology. More particularly, the present invention involves a system and method for the storage, generation and separation of gaseous fuel components as well as the partitioning of liquid and gaseous byproducts in the operation of a portable fuel cell device.
  • Fuel cells are electrochemical cells in which a free energy change resulting from a fuel oxidation is converted into electrical energy.
  • the earliest fuel cells were first constructed by William Grove in 1829 with later development efforts resuming in the late 1930's with the work of F. T. Bacon.
  • hydrogen and oxygen gas were bubbled into compartments containing water that were connected by a gas barrier through which an aqueous electrolyte was permitted to pass.
  • a typical hydrogen-oxygen cell operating at about 250°C and a pressure of about 50 atmospheres yields approximately 1 volt of electric potential with the generation of water and a small quantity of thermal energy as byproducts.
  • PEMFC's Polymer Electrolyte Membrane Fuel Cells
  • An additional advantage of fuel cells is that they generally have a higher energy density and are intrinsically more efficient than methods involving indirect energy conversion. In fact, fuel cell efficiencies have been typically measured at nearly twice those of thermo-electric conversion methods (e.g., fossil fuel combustion heat exchange).
  • fuel cells function similar different principles and are compared with standard batteries. As a standard battery operates, various chemical components of the electrodes inside the battery package are depleted over time. In a fuel cell, however, as long as fuel and oxidant are continuously supplied to the fuel cell electrodes, the cell's electrode material is not consumed and therefore will not run down or require recharging or replacement.
  • One class of fuel cells currently under development for general consumer use is that of hydrogen fuel cells, wherein hydrogen-rich compounds are used to fuel the redox reaction. As chemical fuel species are oxidized at the anode, electrons are liberated to flow through the external circuit.
  • a representative advantage of the present invention includes the user- or designer-controlled processing and/or partitioning of gases produced during operation of a fuel cell device.
  • FIG. 2 representatively illustrates a schematic diagram of an integrated microfluidic gaseous fuel generator and fuel cell subsystem in accordance with another exemplary embodiment of the present invention
  • Fig. 3 representatively illustrates a schematic diagram of an integrated microfluidic H 2 generator and fuel cell subsystem in accordance with another exemplary embodiment of the present invention.
  • Elements in the Figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in tne higures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention.
  • the terms 'first', 'second', and the like herein, if any, are used inter alia for distinguishing between similar elements and not necessarily for describing a sequential or chronological order.
  • Certain representative implementations may include, for example: controlling the concentration of dissolved gases in a fuel cell solution; controlling the concentration of gaseous phase chemical species in a fuel cell; or controlling the rate of effusion of exhaust gases from a fuel cell.
  • exhaust exhaust
  • vent exhaust
  • transport transport
  • diffuse diffuse
  • effuse and “partition”, or any variation or combination thereof, are generally intended to include anything that may be regarded as at least being susceptible to characterization as or generally referring to the movement of at least one chemical compound from one area to another area so as to: (1) relatively decrease the concentration in or around one area, and/or (2) relatively increase the concentration in or around another area. The same shall properly be regarded as within the scope and ambit of the present invention.
  • the terms "fuel”, “fluid”, “solution”, “stream”, “liquid” and “effluent”, or any variation or combination thereof are generally intended to include any anode fuel solution and/or cathode oxidant solution whether or not the solution has been pre-conditioned or post- conditioned with respect to exposure to a fuel cell's electrode elements.
  • a detailed description of an exemplary application namely the parameterization and control of the rate of generation of hydrogen from a PEM fuel cell fuel stream, is provided as a specific enabling disclosure that may be generalized to any application of the disclosed system and method for controlling gas transport in any type of fuel cell in accordance with various embodiments of the present invention.
  • the principles of the present invention may be employed to ascertain and/or realize any number of other benefits associated with controlling the transport of gases in a fuel cell such as, but not limited to: reclamation of gaseous byproducts; reformation of at least one constituent fuel compound; controlling the concentration of dissolved gaseous components and byproducts in a fuel system; controlling a fuel cell's redox reaction kinetics and the like.
  • a fuel cell may be generally characterized as any device capable of converting the chemical energy of a supplied fuel directly into electrical energy by electrochemical reactions. This energy conversion corresponds to a free energy change resulting from the oxidation of a supplied fuel (e.g., hydrogen) and the simultaneous reduction of an oxidant (e.g., oxygen).
  • a supplied fuel e.g., hydrogen
  • an oxidant e.g., oxygen
  • a typical prior art fuel cell consists of an anode (e.g., 'fuel electrode') that provides a reaction site to to oxidize fuel (e.g., hydrogen) and generate electrons and spent fuel (e.g., protons) and a cathode (e.g., Oxidant electrode') that provides sites to receive the free electrons to reduce an oxidant (e.g., oxygen) which can combine with portions of the spent fuel ions (e.g., protons) in order to produce a potential difference (voltage or electromotive force, emf) across the external circuit.
  • the electrodes are generally gas porous, ionic and electronic conductors that include catalytic properties to provide significant redox reaction rates.
  • incident hydrogen gas catalytically ionizes to produce protons (e.g., electron-deficient hydrogen nuclei) and electrons.
  • incident oxygen gas catalytically reacts with incoming electrons from the external circuit to form electron-rich oxygen atoms which combine with protons migrating through the electrolyte to produce water as a byproduct.
  • byproduct water may remain in the electrolyte, thereby increasing the volume and diluting the electrolyte, or may be discharged from the cathode as vapor.
  • the anode and cathode are generally separated by an ion-conducting electrolytic medium (i.e., PEM's or alkali metal hydroxides such as, for example: KOH, NaOH and the like).
  • PEM's or alkali metal hydroxides such as, for example: KOH, NaOH and the like.
  • any chemical substance capable of oxidation i.e., hydrogen, methanol, ammonia, hydrazine, simple hydrocarbons, and the like
  • the oxidant i.e., oxygen, ambient air, etc.
  • the oxidant may be selected to be any substance that can spontaneously oxidize fuel at a sufficient rate to maintain a suitable voltage across the external circuit.
  • ⁇ G ⁇ £ + ⁇ H
  • ⁇ E the energy available to accomplish electrical work
  • ⁇ H the energy liberated from the reaction to raise the temperature of the fuel cell and the surroundings.
  • the heat liberated to the fuel cell's surroundings is much less than the energy available to accomplish electrical work; which may be expressed as: ⁇ H ⁇ s ⁇ E .
  • Q Fmlcdl ⁇ E c,rtc ⁇ l represents the efficiency of converting ⁇ Chemical chemical potential energy E Chmkal directly to electrical energy E cll .
  • Standard batteries have generally dominated the available choices for portable power storage solutions for consumer-level electronic equipment in the past. Some of the disadvantages associated with standard batteries, however, is that they generally provide power for a relatively short duration of time and thereafter require recharging or replacement.
  • Fuel cells on the other hand, have many of the consumer-oriented features typically associated with standard batteries (i.e., providing quiet power in a convenient and portable package) in addition to other representative advantages including, for example, long usage lifetimes and the ability to be fueled with high- energy-density liquid or gaseous compounds rather than the relatively low-energy- density 'solid fuels' as are typically used in conventional batteries.
  • FUEL CELL DEVELOPMENT One class of fuel cells currently under development for consumer use is the hydrogen fuel cell, wherein hydrogen-rich fuels (i.e., hydrogen, methanol, methane, etc.) are used to fuel the redox reaction. As fuel is oxidized at the anode, protons pass through the cell for reduction at the cathode. In the case of using hydrogen as the fuel for example, proton is formed as a byproduct at the anode.
  • hydrogen-rich fuels i.e., hydrogen, methanol, methane, etc.
  • Direct oxidation fuel cells generally include fuel cells in which an organic fuel is fed to the anode for oxidation without significant pre-conditioning or modification of the fuel. This is generally not the case with 'indirect oxidation' (e.g., "reformer") fuel cells, wherein the organic fuel is generally catalytically reformed or processed into organic-free hydrogen for subsequent oxidation.
  • 'indirect oxidation' e.g., "reformer”
  • MEA 'membrane- electrode assembly'
  • a number of these unit fuel cells may be stacked or grouped together to form a 'fuel cell stack'.
  • the individual cells may be electrically connected in series by abutting the anode current collector of one cell with the cathode current collector of a neighboring unit cell in the stack.
  • the current produced is proportional to the net reaction rate, wherein one ampere corresponds approximately to 1.04E18 reactions per second.
  • water saturated H 2 is oxidized at the anode, electrons are liberated to flow through an external circuit to power a load where electrical work may be accomplished.
  • Protons migrate through the proton-transmissive electrolytic membrane where they subsequently are combined with oxygen that has been reduced with incoming electrons from the external circuit with water formed as a result.
  • the time-rated change of the number of particles is given as —Z w A r> , where Z,dite is the collisional frequency associated with the mean free path of the gas particles and A 0 is the area of the opening that the effused gas has available to escape from.
  • the collisional frequency is related to the partial pressure of the gas p , the mass of the gas m and the temperature of the system T by the equation Substitution of this relation back into the expression for the pressure velocity yields .
  • hydrogen will generally: (1) effuse more rapidly at higher operating temperatures and more slowly at lower temperatures; (2) effuse more rapidly with increased back-side pressure of H 2 and more slowly with decreased back-side pressure; (3) effuse more rapidly with membranes having increased porosity and more slowly with decreased porosity; and (4) effuse more rapidly with porous barriers having decreased linear transport distances (e.g., thinner membranes) and more slowly with increased transport distances.
  • Figure 1 generally depicts a borohydride-based fuel cell system 100 in accordance with an exemplary embodiment of the present invention.
  • Fuel cell 110 generally comprises cathode 135, electrolytic membrane 130 and anode 125.
  • Fuel system 100 generally comprises liquid fuel reservoir 140, catalytic gas generator 150, liquid/gas separator 155 and fuel gas 160. As fuel exits reservoir 140 and is introduced to catalytic gas generator 150 via fuel transport path 170, fuel gas 160 is generated. The mixture of liquid and gaseous fuel is then introduced to liquid/gas separator 155 via transport path 175.
  • a substantially integrate micro-fuel cell device 200 generally comprises a fuel pump 235 for delivering hydraulic pressure through transport line 245 to expel liquid fuel 230 for introduction to catalytic micro- reactor 215 via fuel transport path 250.
  • a valve 240 may be provided in transport path 250 for controlling or otherwise managing the introduction of liquid fuel 230 to micro-reactor 215.
  • the resulting liquid/gas fuel mixture is then introduced to separator 220 via transport path 260.
  • Spent fuel is then directed to waste liquid reservoir 225 via transport path 255, while gaseous fuel is delivered to fuel cell 210 via transport path 265.
  • Figure 3 generally depicts yet another exemplary embodiment in accordance with a representative aspect of the present invention.
  • a substantially integrate micro- fuel cell device 300 generally comprises an electro-chemical fuel pump 335 for delivering hydraulic pressure through transport line 345 along fuel pump outlet 337 thru fuel reservoir inlet 339 to expel liquid fuel 330 for introduction to catalytic micro-reactor 315 via fuel transport path 350 along reservoir outlet 342 thru micro-reactor inlet 313.
  • a valve 340 may be provided in transport path 350 for controlling or otherwise managing the introduction of liquid fuel 330 to micro-reactor 315.
  • the resulting liquid/gas fuel mixture is then introduced to separator 320 via transport path 260 from micro-reactor outlet 317 thru separator inlet 319.
  • Spent fuel is then directed to waste liquid reservoir 325 via transport path 355 from first separator outlet 359 to waste reservoir inlet 357, while gaseous fuel is delivered to fuel cell 310 via transport path 365 from second separator outlet 363 thru fuel cell inlet 367.
  • fuel reservoir 3300 may be optionally configured with a diaphragm, partition, membrane or bladder 332 for disposing spent liquid fuel in a region 325 at least partially separated from unprocessed liquid fuel 330 in such a fashion that as the volume of unprocessed liquid fuel 330 is depleted, the waste reservoir region 325 is enlarged to at least partially occupy a portion of the depleted volume formerly occupied by the unprocessed liquid fuel 330.
  • the disclosed fuel cell system is a miniature low-temperature, long-lived electrical power supply system for man portable applications that require up to about 1W to greater than about 20W of power.
  • Catalytic room-temperature borohydride hydrolysis is accomplished in a plastic microfluidic micro-reactor and offers a low temperature process for generating hydrogen gas to supply hydrogen fuel to a fuel cell, the ultimate source of electric power in this device which is a hybrid of a fuel cell, a battery, a power conditioning subsystem and system control circuitry.
  • Hydrogen gas may be used because it is a well-behaved anode reactant for a low temperature PEM fuel cell.
  • the power supply system may be configured as a hybrid of a battery and a PEM fuel cell, since the battery may be suitably adapted to provide an acceptable power/time profile and system start up benefits while the fuel cell provides relatively long application lifetime.
  • the fuel cell may be configured to enable the hybrid system to provide an energy density on the order of up to about 3 to more than about 10 times greater than is possible with any presently available conventional battery alone.
  • plastic housed microfluidics are used to fabricate a miniature room temperature hydrogen gas generator.
  • Hydrogen gas is liberated from, for example, a liquid alkaline aqueous sodium borohydride solution 330 by, for example, the following catalytic hydrolysis reaction: NaBH + 2H 2 0 * ⁇ il >AH 2 + NaB0 2
  • the H + catalyst 150 may be Ruthenium.
  • the borohydride solution 330 generally allows safe, stable (on the order of up to about or more than 450 day half-life) and high energy-density hydrogen storage (on the order of up to about or more than 3000 Watt-hour/liter).
  • Figure 1 shows a block diagram of a more generalized gaseous fuel generator 100 and fuel cell 110 subsystem.
  • the hydrogen may be separated from the liquid waste borax (NaBO 2 ) solution.
  • the hydrogen gas may then be provided to the anode 125 of a polymer electrolyte membrane 130 (PEM) fuel cell, while waste liquid borax solution and water is channeled back 165 to a waste reservoir 325, 225, 145.
  • the waste reservoir 325, 145 may be provided as the volume that remains when the fuel reservoir 330, 140 becomes at least partially depleted.
  • waste liquid borax solution and water may be channeled back 165 to fill the space that was originally occupied by the sodium borohydride hydrogen-storage solution 325.
  • Hydrogen fuel gas may be generated from liquid alkaline borohydride solution, for example, by passing the solution over solid supported Ru metal, or other suitable metals, to promote the heterogeneous catalytic hydrolysis of the alkaline borohydride, or by adding acid to the solution thereby lowering the solution pH to effect homogeneous acid-catalyzed hydrolysis of borohydride.
  • Conventional hydrogen and air-fed PEM fuel cells employ a Pt-catalyzed porous anode and cathode on opposite sides of a sheet of proton-conducting solid membrane electrolyte, like Nafion.
  • the present invention also anticipates, but does not require, novel PEM fuel cells using proton conducting membranes made from derivatives of C6O "buckyballs" or protic ionic salts, since such a C60 membrane or a protic ionic salt membrane generally need no water for proton conduction, which operates to greatly simplify water management, and as a consequence, would permit simple dead-ending of dry hydrogen to supply the anode.
  • a Nafion membrane may be used, however, liquid water would need to be removed from the anode surface and directed to the liquid waste storage region by using, for example, a hydrophilic liquid water-passing / gas-holding gas/liquid separator. This would generally operate to keep hydrogen freely flowing and diffusing into the anode.
  • Liquid-water can be separated from hydrogen gas using hydrophilic porous silicon membranes, which generally permit the passage of liquid water but holds back hydrogen gas.
  • the cathode may have passive (i.e., stagnant air) or an active (i.e., forced air) feed.
  • any cathode water may be dumped into the environment; however, if it is desired, liquid water from the cathode may be captured and directed back, for example, to the waste reservoir in a scheme similar to that previously discussed for removing liquid water from the anode.
  • 225 current collectors, valves 240, 340, fuel pumps 335, 235, air fans, dc-dc converters, system controllers, etc. may be employed to provide a substantially complete power supply system.
  • well-known heated paraffin valving and electro-chemical pumping techniques may be employed.
  • One-way piezo pumps with check valves may also be used for liquid pumping. This may be desirable as a practical system may be adapted to provide substantially direct control of H 2 generation by the electronic control of the frequency of liquid pumping.
  • the stack power density may be adapted to be on the order of about 100W per liter, based on a membrane electrode assembly generating about 0.1W to about 0.35W per square centimeter at 0.7V per cell.
  • the system energy density may be adapted to provide on the order of about 1000 Watt-hour per liter, based on a fuel composition, for example, of 30%(wt) NaBH and 4.3%(wt) NaOH and 67%(wt) water (2500 Wh/I).
  • a system chemical-to-electrical conversion efficiency of about 50% may be observed allowing the hydrogen generator/fuel cell subsystem about 10% of the total volume (fuel plus system).
  • 1 Liter of NaBH -30 solution has about 66 grams of hydrogen, or about 789 standard liters of hydrogen gas.
  • Table 1 (entitled "Borohydride solution and hydrogen gas flow for different electrical power") attached hereto, gives the fluid flows needed to sustain electrical currents.
  • the freezing point of borohydride-30 is about -13F to about -36F and the boiling point is about 120C.
  • the half-life at 70F of the hydrogen storage solution is on the order of about 450 days. Accordingly, these characteristics afford a system that may be adapted to operate over a wide range of practical conditions desirable for portable power applications.

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Abstract

La présente invention a trait à un système et un procédé pour la génération et la séparation de constituants de combustible gazeux, ainsi que la séparation de produits secondaires liquides et gazeux, dans le fonctionnement d'un dispositif de piles à combustible portatif comportant : un volume de confinement microfluidique (140, 230) ; un substrat pour le support d'une composition catalytique (150, 215, 315) qui est parfaitement adaptée pour favoriser l'hydrolyse d'un précurseur de combustible sensiblement en suspension (330) pour la génération d'un constituant de combustible gazeux ; un séparateur gaz/liquide (155, 220, 363) pour la séparation au moins partielle d'un constituant gazeux d'un constituant liquide ; une pile à combustible (210, 310) comportant une anode (125) et une cathode (135) ; et des connexions électriques couplées à celle-ci pour l'alimentation d'une charge (120). Divers éléments et paramètres de la présente invention peuvent être parfaitement adaptés pour l'optimisation des fonctions de transport et/ou de séparation gaz/liquide pour n'importe quel modèle spécifique de pile à combustible. La présente invention assure un contrôle amélioré du débit d'alimentation/de retrait de constituants gazeux vers/depuis une solution de combustible de pile à combustible outre une application améliorée de technologie de pile à combustible pour l'alimentation, entre autres, de dispositifs électroniques portatifs.
PCT/US2004/038653 2003-11-14 2004-11-15 Systeme de piles a combustible microfluidique et procede pour des applications d'energie portable Ceased WO2005050763A1 (fr)

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US51999303P 2003-11-14 2003-11-14
US60/519,993 2003-11-14

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WO2005050763A1 true WO2005050763A1 (fr) 2005-06-02

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1909350A1 (fr) 2006-10-06 2008-04-09 STMicroelectronics S.r.l. Micropile à combustible alimentée avec de l'hydrogène provenant de la décomposition de borohydrure de sodium dans un microréacteur
EP1908728A1 (fr) * 2006-10-06 2008-04-09 STMicroelectronics S.r.l. Procédé et dispositif correspondant pour la production en continu d'hydrogène gazeux pour alimenter des micro-piles à combustible
US8232010B2 (en) 2006-10-06 2012-07-31 Stmicroelectronics S.R.L. Process and corresponding apparatus for continuously producing gaseous hydrogen to be supplied to micro fuel cells and integrated system for producing electric energy
EP1931754A4 (fr) * 2005-10-03 2014-03-12 Bic Soc Procede d'optimisation de l'efficacite de la generation d'hydrogene dans des cartouches de piles a combustible
JP2017139158A (ja) * 2016-02-04 2017-08-10 パナソニックＩｐマネジメント株式会社 燃料電池のシミュレーション方法と、燃料電池のシミュレーショ装置

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US5879827A (en) * 1997-10-10 1999-03-09 Minnesota Mining And Manufacturing Company Catalyst for membrane electrode assembly and method of making

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5879827A (en) * 1997-10-10 1999-03-09 Minnesota Mining And Manufacturing Company Catalyst for membrane electrode assembly and method of making

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1931754A4 (fr) * 2005-10-03 2014-03-12 Bic Soc Procede d'optimisation de l'efficacite de la generation d'hydrogene dans des cartouches de piles a combustible
EP1909350A1 (fr) 2006-10-06 2008-04-09 STMicroelectronics S.r.l. Micropile à combustible alimentée avec de l'hydrogène provenant de la décomposition de borohydrure de sodium dans un microréacteur
EP1908728A1 (fr) * 2006-10-06 2008-04-09 STMicroelectronics S.r.l. Procédé et dispositif correspondant pour la production en continu d'hydrogène gazeux pour alimenter des micro-piles à combustible
US8232010B2 (en) 2006-10-06 2012-07-31 Stmicroelectronics S.R.L. Process and corresponding apparatus for continuously producing gaseous hydrogen to be supplied to micro fuel cells and integrated system for producing electric energy
JP2017139158A (ja) * 2016-02-04 2017-08-10 パナソニックＩｐマネジメント株式会社 燃料電池のシミュレーション方法と、燃料電池のシミュレーショ装置

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