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
  • H01M8/02—Details
  • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
• • 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
  • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
  • H01M8/04067—Heat exchange or temperature measuring elements, thermal insulation, e.g. heat pipes, heat pumps, fins
  • H01M8/04074—Heat exchange unit structures specially adapted for fuel cell
• • 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
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• • 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
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
• • 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
  • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
  • H01M8/04029—Heat exchange using liquids
• • 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
  • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective 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
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
  • H01M8/04225—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells during start-up
• • 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
  • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
  • H01M8/04228—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells during shut-down
• • 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
  • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
  • H01M8/043—Processes for controlling fuel cells or fuel cell systems applied during specific periods
  • H01M8/04302—Processes for controlling fuel cells or fuel cell systems applied during specific periods applied during start-up
• • 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
  • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
  • H01M8/043—Processes for controlling fuel cells or fuel cell systems applied during specific periods
  • H01M8/04303—Processes for controlling fuel cells or fuel cell systems applied during specific periods applied during shut-down
• • 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
  • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported 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
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
  • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
  • H01M8/04156—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal
• • 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 fuel cell is a device that generates electrical energy by converting chemical
• a typical fuel cell includes a casing which houses an
• the electrolyte membrane is
• a catalyst layer is disposed on the
• Suitable catalysts include nickel, silver,
• a relatively simple type of fuel cell (commonly called a PEM fuel cell) uses hydrogen and oxygen as the fuel and oxidant materials,
• Hydrogen combines with oxygen to form water while at the same time
• Fuel cells can be classified into several types according to
• electrolytes such as
• the overall reaction in the cell i.e. formation of water
• the overall reaction in the cell i.e. formation of water
• the rate of heat generation is dependent upon the reaction rate and the heat flux
• Water is generally used for cooling fuel cells.
• PEM fuel cells generally require humidification to maintain the moisture of the
• water loop generally provides both humidification and cooling for fuel cells.
• Ice formation inside the fuel cell system may
• coolants must be selected that freeze at temperatures below the freezing point of water.
• catalyst layer by binding to catalyst sites if such materials are allowed to come in
• a freeze tolerant fuel cell system including at least one fuel cell made up
• first and a second gas diffusion layer is disposed between said collector plates;
• MEA membrane electrode assembly
• the MEA is interposed between said gas diffusion layers, and
• the fuel cell stack can further include at least one coolant
• coolant stream does not contact said MEA while cooling the fuel cell.
• coolant passage is poisonous to the MEA and thus must be mechanically isolated
• the surfaces of the coolant passage in contact with the coolant can be selected from the MEA.
• the coolant can be electrically non-conductive.
• isolation can be provided by a gasket arrangement around coolant ports running
• the gaskets are preferably spaced from the gas
• cooling passage can be positioned outside the
• the fuel cell coolant loop can include edge cooling within the fuel cell, or a
• This coolant layer can be provided. This coolant layer can be provided.
• peripheral port gaskets and the active area membrane can be supported by bridging
• the sub gaskets extend across the
• the sub-gaskets can be made of a number of materials, including FEP, TFE, ETFE, PFA, CTFE, E-CTFE, PVF2 and PVF.
• the fuel cell system is not operating.
• water can accumulate in the gas diffusion layers as
• the reactant channels in the collector plates are discontinuous, whereby
• purging dry gases can be forced
• surfaces of the channels are preferably essentially impermeable to water.
• the surfaces of the channels can be essentially impermeable to all fluids.
• system according to the invention can provide counterflow in the gas diffusion layers
• the reactant channels of each collector plate can be arranged so the
• direction of reactant flow in one gas diffusion layer is opposite the direction of
• Another improvement to assist in water purging relates to the positioning of the outlet channels to use gravitational force.
• inventions can have reactant outlets in which at least one of the outlets is positioned
• the drained water can be removed from the system or collected in a
• the reservoir such as a tank.
• the tank can be rendered freeze tolerant in a number of
• watering in the tank can be allowed to freeze
• the tank is designed to permit expansion of freezing water.
• the walls of the channels can be tapered
• a fuel cell system can be made more freeze
• the shut-down procedure can include the steps of: reducing the fuel cell system
• the shut down procedure can also include steps to further increase heat of
• One preferred step includes running said
• the predetermined temperature can be the freezing
• the start-up procedure can also preferably
• the start-up procedures can also include: providing a humidifier for
• the humidifier for humidification of the gas flows.
• the heat for melting the water in the reservoir can be obtained from the fuel
• the steps of an implementing method can include: operating a fuel
• processor in an oxidant rich mode to increase heat output; transferring a portion of
• reactant mixture in the fuel processor to increase fuel production after at least a portion of the water in said reservoir is melted and the fuel cell temperature has
• Fig. 1 illustrates a breakaway side view of fuel cell and coolant system
• Fig. 2 illustrates a freeze tolerant fuel cell system schematic comprising a fuel
• Fig. 3 illustrates a side view of a fuel cell having collector plates with non-
• Fig. 4 illustrates a breakaway side view of a fuel cell having primary gaskets
• a novel freeze tolerant fuel cell structure is provided that is adapted for
• sub-freezing environments As used throughout this specification, sub-freezing
• the cooling system and humidification systems are
• the cooling system is also preferably isolated from the
• the fuel cell which have freezing points below the freezing point of water may be any fuel cell which have freezing points below the freezing point of water.
• the fuel cell system is run in a
• the fuel cell during sub-freezing conditions involves removing as much water as
• a novel freeze tolerant fuel cell structure having both gaskets and sub-
• gaskets is also disclosed. Upon assembly of the freeze tolerant fuel cell, an interface
• the fuel cell is formed. This region is subject to enhanced mechanical and enhanced electrical stress due to increased edge conduction relative to electrochemically
• a fuel cell is identified generally by the reference numeral
• Each cell unit 1 1 includes a membrane
• MEA 12 comprised of a solid ion conducting membrane which
• anode 13 on one side and a cathode 14 on the other side of the
• the MEA 12 is interposed between a first
• anode and cathode may be attached or integrated into the
• the MEA includes an attached anode 13 and cathode 14 due to
• the MEA 12 extends some minimum
• the MEA can terminate with the edges of the gas diffusion layers
• the gas diffusion layers 15 and 16 are interposed between two electrically
• bipolar plates when two or more fuel cells are used to form
• the gas diffusion layers 15 and 16 are typically fabricated from
• porous, electrically conductive materials such as carbon/graphite fiber paper or
• collector plates 18 and 19 are provided for separating the cathode of one cell unit 11
• the fuel cell 10 is a proton
• PEM exchange membrane
• cathode of one cell to the anode of an adjacent cell (not shown).
• the collector plates 18 and 19 are electrically conductive. In the preferred embodiment
• the collector plates 18 and 19 are formed from
• electrically conductive polymer composites by filling a polymer with a plurality of
• the collector plates 18 and 19 may be
• water permeable collector plates may be used.
• water permeable collector plates may be used.
• collector plates 18 and 19 selected are essentially impermeable to water.
• the surfaces of the channels are impermeable to water while the
• remainder of the collector plate may be permeable to water.
• ionized water is commonly used to cool fuel cells and also to maintain the hydration
• Membrane humidification if required, must also be redesigned
• the coolant fluid in a freeze tolerant fuel cell cannot be pure water since water
• Humidification of the membrane may be derived from a source outside the
• fuel cell stack such as by humidifying incoming reactant gases through the use of misters or bubblers.
• fuel processors are used to produce
• the anode may not require humidification, due to moisture produced
• a dedicated coolant loop 25 has a coolant flow field through and between
• conductive sealant 32 binds top collector plate and bottom collector plate. Coolant
• a coolant return path is provided but not shown.
• Coolant loop 25 does not provide humidification to the fuel cell 11.
• coolant loop 25 is isolated from the membrane by a minimum
• the distance "A" is chosen to avoid coolant contact with the
• the distance "A" is at least approximately 0.1 inches.
• Seal integrity is principally a function of the type of gasket material selected.
• hydrocarbons For example, hydrocarbons
• Poisonous coolants are known to occupy catalyst sites. As used throughout the specification, these contaminating coolants are referred to as "poisonous.” Poisonous coolants are
• the coolant in an alternate embodiment of the freeze tolerant fuel cell, the coolant
• passage way is not part of the collector plate.
• coolant may be flowed
• coolant channels are placed
• coolant does not pass between the region
• Possible suitable coolants include:
• glycol and ethylene glycol such as methanol, with any percentage of other coolants
• gases under anticipated conditions of operation such as nitrogen or
• the maximum allowable coolant ionization level depends on the design of the
• coolant loop 25 If the coolant loop 25 is designed to be electrically isolated from the
• ionic coolants may be used. However, if the coolant loop
• coolant ionization level must be limited to avoid electrically coupling neighboring
• the coolant loop 25 is not electrically isolated from collector plates
• coolant loop 25 is designed to be electrically isolated from collector
• the coolant isolation can be provided by a gasket arrangement.
• edge of the MEA 12 is interposed between a first gasket 20 and a second gasket 21.
• Gaskets 20 and 21 are preferably positioned so as to not overlap with gas diffusion
• Gaskets 20 and 21 may be made from polymer materials such as
• EPDM rubber also known as EP rubber
• fluorinated hydrocarbon also known as EP rubber
• butyl rubber fluorinated hydrocarbon
• An interface region 22 is a fluorosilicone, polysiloxane, thermoplastic elastomers such as blends containing polypropylene and EP rubber, and or other similar materials.
• the membrane at or near the interface region 22 is subjected to both
• the membrane in the interface region 22 will be unsupported and will tend to sag or
• the interface region 22 is effectively splitting the interface region 22 into two regions.
• gas diffusion layers 15 and 16 may butted up against the gaskets 20 and 21 and
• fuel cell system such as reactant flow control, temperature monitoring and control
• the percentage of hydrogen in the reformate stream may be adjusted
• Combustion is usually a
• tank 64 will be used for steam reforming and cathode gas humidification when the operating temperatures in the system rise above freezing point of water. In start up
• the hot gas stream produced by the fuel processor 60 can be used to calculate the hot gas stream produced by the fuel processor 60.
• a hot reactant stream will also help thaw out the various fuel stack
• dry air is fed to the cathode 70 without humidification. Pressurized dry air from the
• cathode compressor is typically heated to a temperature in the range of 90-100°C
• stack 10 will be operated in a low voltage/high current density mode to maximize
• Heat generated will be used to raise the temperature of the
• stack 10 and the coolant. As the stack 10 temperature increases, the stack will be
• the system may be
• Cathode air humidification may be begun after the stack 10 and coolant temperature are well above freezing.
• the fuel in an alternate embodiment of the freeze tolerant fuel cell system, the fuel
• processor shown in Fig. 6 is replaced by an essentially pure hydrogen source.
• Hydrogen is supplied to the anode of the fuel cell along with an oxygen source to the
• the temperature of the freeze tolerant coolant If the water tank contains ice, the
• heated freeze tolerant coolant is circulated through the water tank to melt the ice in
• a method for shutting down the freeze tolerant fuel cell is also required to
• the temperature may be reduced to condense water vapor within the system.
• the temperature may be
• freeze resistant storage tank 64 Second, the fuel cell stack 10 and system reactant
• Condensed water droplets will be separated in the anode separator(s) and
• freeze tolerant storage tank 64 can either be drained into freeze tolerant storage tank 64 or be completely purged
• An anode cooler/chiller is
• This water is eliminated from the anode stream by an anode separator 74.
• separated water can either be drained into a freeze resistant storage tank 64 or be
• the anode cooler/chiller holds the system
• anode gas temperature is brought down to ambient such that the anode gas temperature can also be cooled to near ambient temperature.
• cathode gas is terminated.
• the cathode system is then purged with dry cathode
• the compressor temperature and pressure are brought down to near ambient
• freeze resistant water storage tank 64 may be drained into the freeze resistant water storage tank 64 or be completely purged
• the fuel cell stack 10 is
• cathode inlet channel 28 anode outlet channel 27 and cathode outlet channel 29
• the walls of the channels making up the flow field may be any shape.
• Fig. 4 adds a pair of sub-gaskets 23 and 24 to Applicants' gasketed fuel cell
• Sub-gaskets 23 and 24 are positioned between first and second
• gaskets 20 and 21 and extend into a position between the gas diffusion layers 15
• sub-gaskets 23 and 24 are made from
• the coolant loop 25 passes through gaskets 20 and 21 as well as
• sub-gaskets 23 and 24 reduce
• Sub-gaskets 23 and 24 need not extend to be co-terminus on
• sub-gaskets 23 and 24 are co-
• gasket 23 and 24 material as compared to the added labor cost to construct

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• 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)

Applications Claiming Priority (3)

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• 2000
  • 2000-04-24 WO PCT/US2000/010949 patent/WO2000065676A1/en not_active Application Discontinuation
  • 2000-04-24 CN CN00808391A patent/CN1353869A/zh not_active Withdrawn
  • 2000-04-24 JP JP2000614524A patent/JP2002543566A/ja active Pending
  • 2000-04-24 MX MXPA01010724A patent/MXPA01010724A/es unknown
  • 2000-04-24 AU AU46580/00A patent/AU4658000A/en not_active Abandoned
  • 2000-04-24 EP EP00928326A patent/EP1216489A1/en not_active Withdrawn
  • 2000-04-24 CA CA002371257A patent/CA2371257A1/en not_active Abandoned

Non-Patent Citations (1)

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