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
  • H01M8/04291—Arrangements for managing water in solid electrolyte fuel cell systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
  • H01M4/8647—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites
  • H01M4/8657—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites layered
• • 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
  • 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
  • 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
  • H01M8/04216—Reactant storage and supply, e.g. means for feeding, pipes characterised by the choice for a specific material, e.g. carbon, hydride, absorbent
• • 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

• a pneumatic valve is used to control a hydrogen generating chemical reaction that feeds hydrogen oxygen PEM fuel cells.
• the valve comprises a substantial portion of the power generator volume and weight, and thus reduces the energy density and specific energy of the power generator.
• PEM fuel cells use a simple chemical reaction to combine hydrogen and oxygen into water, producing electric current in the process.
• Hydrogen may be produced by a chemical reaction between a fuel, such as lithium aluminum hydride and water vapor.
• a fuel such as lithium aluminum hydride and water vapor.
• hydrogen molecules are ionized by a platinum catalyst, and give up electrons.
• the PEM allows protons to flow through, but not electrons.
• FIG. 1 is a cross section view of a power generator according to an example embodiment.
• FIG. 3 A is a cross section of a fuel cell stack according to an example embodiment.
• FIG. 2 is a top cross section view of the power generator 100.
• the power generator comprises a fuel cell stack 110 that is exposed to air.
• the power generator 100 in one embodiment is built as a hollow cylinder with two ends, and surrounds a fuel 120. Other geometries for the shape of the power generator include rectangular solids, spheres, and other non geometrical shapes.
• the fuel is a hydrogen generating fuel that is used by the generating stack 110 to generate electricity.
• the fuel in one embodiment comprises a hydrogen and porous metal hydride fuel.
• the fuel cell stack 110 combines with oxygen from the air to create water and electricity.
• a pressure relief valve 130 may be used to relieve pressure should excess hydrogen be generated.
• the relief valve may be located on the power generator with access to the hydrogen generated by the fuel.
• a cathode gas diffusion layer (GDL) 310 is coupled to the cathode current collector.
• a hydrophobic micro porous layer 315 is formed on the cathode GDL and separates the cathode GDL 310 from a catalyst coated proton exchange membrane (PEM), such as a Nafion® membrane layer 320.
• PEM catalyst coated proton exchange membrane
• a hydrophilic micro porous layer 325 separates layer 320 from an anode GDL 330, which in turn is coupled to an anode current collector 335.
• the anode current collector 335 has pores formed therein to allow hydrogen to pass through to the anode.
• the anode current collector 335 is separated by water vapor and hydrogen permeable membrane 340.
• Membrane 340 is liquid water and particulate impermeable. Membrane 340 is used to separate the fuel 345 from the anode current collector 335. The layers between the cathode and the hydrogen generating fuel serve to separate the cathode from the hydrogen generator containing the fuel 345 that generates hydrogen when exposed to water vapor and provide a diffusion path.
• the gas diffusion electrodes are one piece in one embodiment with three layers.
• the three layers are the gas diffusion layer (GDL)(carbon paper), the micro porous layer (MPL) (PTFE or PVDF) and the catalyst layer (carbon/platinum).
• FIG. 4 is a perspective view of the fuel cell stack 300.
• Anode current collector 335 is illustrated, showing multiple pores 410.
• the pores are relatively large to allow hydrogen to move through to the anode gas diffusion layer 330.
• the hydrophobic coating on the cathode GDL and the hydrophilic coating on the anode GDL promote back permeation of water (from cathode to anode) through the PEM by increasing the hydraulic pressure difference across the PEM.
• a hygroscopic material (hydrogen generating hydride fuel) at the ajr ⁇ dejxirther increases the hydraulic pressure difference across the PEM by reducing the humidity (vapor pressure) at the cathode.
• a diffusion path is thus provided between the fuel cell cathode and the hydrogen generator.
• Power generator 100 is a valveless power generator that produces power without the need for moving parts.
• the valveless power generator may provide a self regulating water flow.
• the rate of hydrogen generation is regulated according to the electrical power drawn from the fuel cell without the need for moving parts.
• the fuel cells may occupy the surface of the power generator, with fuel occupying a large volume of the power generator. Removing the valve frees up a significant portion of the volume of the power generator for additional fuel, improving energy density and specific energy of the power generator.
• Many different sizes of power generators may be formed, such as those having the same volumetric shape as existing batteries, or yet other shapes as desired.
• a micro porous layer is added to the fuel cell membrane to encourage water transport from the cathode to the anode.
• Hydrophobic layers are added to the fuel cell to encourage water transport from _ the cathode to the anode.
• Hy drophilic_ layers are also added to the fuel cell to encourage water transport from the cathode to the anode.
• the fuel cell may be produced with micromachining processes, and a protective cover may be provided for the cathode to prevent excess exposure to air and water vapor when power generation is not desired. The cap may be removed when power generation is desired.
• Water flux at the cathode, JM is a function of at least three components, diffusion, osmotic drag, and hydraulic permeation:
• water flux at the fuel cell cathode is the sum of at least three modes of water transport. Water diffusion in the PEM membrane, electro osmosis, and hydraulic permeation.
• Hydraulic permeation can also be increased by setting up a pressure differential across the fuel cell membrane. This can be accomplished by operating the power generator at lower than ambient hydrogen pressure.
• ⁇ c membrane thickness
• ⁇ c membrane thickness
• ⁇ c contact angle of the cathode micro porous layer
• re pore radius of the cathode micro porous layer
• ⁇ c contact angle of the anode micro porous layer
• maximizing pore radius ( ⁇ c) of the anode micro porous layer helps to increase water flux from the cathode to the anode.
• the parameters should not be minimized or maximized, because at their extremes they negatively affect other factors that limit power generator performance.
• the micro porous layers are composed of 100 to 500 nm carbon or graphite particles mixed with a polymeric binder, usually PTFE or PVDF.
• the pore size of the cathode MPL can range from 100 to 1000 nm, the thickness can range from 10 to 100 um, and the contact angle from 90 to 120 degrees.
• the pore size of the anode MPL can range from 500 to 2000 nm, the thickness from 10 to 100 um, and the contact angle from 50 to 90 degrees.
• the rate at which water is generated by the fuel cells is equal to the rate at which water is consumed by the hydrogen generating reaction.
• the reaction is self sustaining and the pressure inside the generator is constant. If the load is increased, the pressure inside the power generator is reduced as hydrogen is consumed by the fuel cells. The drop in internal pressure causes the hydraulic permeation to increase, thus more water is transported into the hydrogen generator and more hydrogen is generated, and a new steady state is achieved at a lower pressure.
• FIG. 5 illustrates a further embodiment of a power generator 500.
• a container 510 holds a hydrogen generating fuel 515, which in one embodiment occupies a substantial volume of the power generator.
• a membrane, 520 such as a Gore Tex water vapor and hydrogen permeable membrane separates the fuel 515 from a fuel cell assembly 530.
• the fuel cell assembly 530 may be formed in the same manner as fuel cell stack 300.
• Openings 540 may also contain an oxygen-permeable water vapor-impermeable membrane 545 positioned between the opening and the cathode, that allows substantially enough oxygen to permeate from the ambient to the cathode for a desired power level while restricting permeation of water vapor from the cathode to the ambient, hi one embodiment, the membrane 550 comprises a thin layer or layers of a fluorinated ethylene polymer or propylene (FEP) or perfluoroalkoxy (PFA) to provide high selectivity.
• FEP fluorinated ethylene polymer or propylene
• PFA perfluoroalkoxy

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

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Publications (2)

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Citations (6)

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• 2005
  • 2005-10-25 US US11/257,738 patent/US7811690B2/en not_active Expired - Fee Related
• 2006
  • 2006-10-20 CN CN200680048951XA patent/CN101346845B/zh not_active Expired - Fee Related
  • 2006-10-20 EP EP06826323.5A patent/EP1964197B1/en not_active Ceased
  • 2006-10-20 WO PCT/US2006/040984 patent/WO2007050448A2/en not_active Ceased
  • 2006-10-20 JP JP2008537806A patent/JP2009514170A/ja not_active Withdrawn
• 2010
  • 2010-09-01 US US12/873,895 patent/US8202657B2/en not_active Expired - Fee Related
• 2014
  • 2014-10-28 JP JP2014219075A patent/JP6129806B2/ja not_active Expired - Fee Related
• 2017
  • 2017-01-06 JP JP2017000881A patent/JP6325698B2/ja not_active Expired - Fee Related

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