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
  • H01M8/0202—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
  • H01M8/026—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant characterised by grooves, e.g. their pitch or depth
• • 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
  • H01M8/023—Porous and characterised by the material
  • H01M8/0241—Composites
  • H01M8/0245—Composites in the form of layered or coated products
• • 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
• • 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
  • 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
  • H01M8/0263—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant having meandering or serpentine paths
• • 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
  • H01M8/0273—Sealing or supporting means around electrodes, matrices or membranes with sealing or supporting means in the form of a frame
• • 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
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
• • 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
• • 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 relates to fuel cells, and in particular to improvements in performance of polymer fuel cells .
• the dominating component at the internal resistance loss in the stack, is due to the limiting proton conductivity of the membrane. Membranes tend to dry out, especially on the anode side, at high current densities, since proton migration drags water molecules away from the anode. Drying of anode does not only affect resistance but also the kinetics of hydrogen reduction reaction (HRR) at the anode.
• HRR hydrogen reduction reaction
• the cathode side of the cell can also be pressurized to use the pressure gradient over the membrane to press the water back to the anode.
• Another solution is to have a direct water contact with the membrane at the anode side, since the water content and conductivity of the membrane are much higher when membrane " is in equilibrium with water. Also, when liquid is evaporated inside the fuel cell a considerable amount (40-50%) of the heat can be removed from the cell with the produced water vapor.
• the object of the present invention is to provide means for achieving better humidification, at low cost and low cell complexity.
• the trade off between performance and cost should be acceptable.
• an aqueous phase preferably water
• the polymer electrolyte fuel cell structure according to the invention comprises a proton exchange membrane, an anode catalyst layer on one side of the proton exchange membrane, a cathode catalyst layer on the opposite side of the proton exchange membrane and a gas distribution layer on each side of the proton exchange membrane. It is characterized in that the anode side gas distribution layer is a flat, porous structure having water channels formed in the surface facing the membrane, and that the anode side gas distribution layer is enclosed by a coplanar, sealing plate with water inlet channels coupled to said water channels in the gas distribution layer.
• Fig. 1 is a perspective explosion view showing the elements of a polymer fuel cell structure in accordance with the invention
• Fig. 2 shows in plane view from above and below, all elements of the structure in Fig. 1
• Fig. 3 is a section in larger scale, through a gas distribution layer which is included in the structure of Fig. 1 and 2
• Fig. 4 shows a second embodiment of the gas distribution layer
• Fig. 5 shows a third embodiment of the gas distribution layer
• Fig. 6 shows, in the same manner as Fig. 2, an alternative structure layout
• Fig. 1 is a perspective explosion view showing the elements of a polymer fuel cell structure in accordance with the invention
• Fig. 2 shows in plane view from above and below, all elements of the structure in Fig. 1
• Fig. 3 is a section in larger scale, through a gas distribution layer which is included in the structure of Fig. 1 and 2
• Fig. 4 shows a second embodiment of the gas distribution layer
• Fig. 5 shows a third embodiment of the
• Fig. 7 shows still another embodiment of the gas distribution layer.
• the fuel cell comprises a conductive anode plate 1.
• An anode sealing frame 2 is provided adjacent the bipolar plate 1.
• This frame is provided with a central, rectangular opening for an anode gas distribution layer 3.
• the frame 2 is also provided with an anode gas inlet 9 and an outlet 10 and distribution channels are formed as well as water inlets and outlets 11, 12 respectively.
• the anode gas distribution layer 3 is provided with a plurality of narrow water channels 3a on the opposite side of the layer 3, with reference to the anode plate 1.
• a proton exchange membrane 4 is arranged for cooperation with the plate 1 for sandwiching the frame 2 and the diffusion layer 3 between themselves.
• the cathode side of the fuel cell is structured in a similar manner as the anode side.
• the opposite side of the membrane 4 is arranged for cooperation with a conductive cathode plate 7 for sandwiching a cathode sealing frame 6 and a cathode gas distribution layer 5 between themselves.
• the cathode diffusion layer 5 is not provided with any water channels as the anode diffusion layer 3.
• the cathode sealing frame 6 is provided with a cathode gas inlet 13 and an outlet 14.
• figure 2 the detailed structure of water channels and how the water distribution is organized in a stack is shown.
• the left-hand side of the figure shows the upside and the right-hand side of the figure shows the down side.
• Each sealing frame 2 in a stack has a number of holes made through it.
• the holes located in the corners are for clamping bolts used when assembling a number of cell units to a cell stack.
• the remaining holes, together with corresponding holes in the other components of a stack, form channels through the stack for water, fuel gas and oxidant gas respectively.
• the upper side (as defined above) of the sealing 2 has gas channels 15 running along the inner edge of the frame like structure.
• a number of distribution apertures are diverted from each channel 15, so as to distribute incoming gas into the diffusion/distribution material located in the frame.
• the second hole from left (in the figure) in the upper array of holes is the inlet channel 9 for incoming gas, and the second hole from left in the lower array of holes is the outlet channel 10 for gas exiting. from the cell on the anode side.
• the anode sealing 2 has the same configuration of gas channels regardless of position in the stack.
• each sealing 2 On the down side (as defined above) of each sealing 2 there are provided channels for water, having a common water inlet 11 and a common water outlet 12.
• the membrane 4 In the middle of the stack the membrane 4 is arranged, separating the anode and cathode parts of the stack.
• a cathode gas distribution layer 5 On the cathode side, a cathode gas distribution layer 5 is provided, and then there is sealing 6 for cathode wherein cathode gas inlet and outlet 13, 14 are formed, in a similar way as in the anode sealing 2.
• Figure 3 shows a more detailed structure of a gas distribution layer.
• the layer 3 is provided with water channels 3a adjacent the membrane 4.
• the water channels 3a may have a width of about 50-100 ⁇ m, a depth of about 100-300 ⁇ m and the channels may be separated by a distance of about 200- lOOO ⁇ m.
• One possible method of producing the channels 3a would be to press the gas distribution layer against a template having a ridge structure surface corresponding to the desired water channel structure.
• Figure 4 shows an embodiment of the invention, where the gas distribution layer 3 is provided with a catalyst layer 16.
• a non-porous or almost non-porous proton conducting polymer layer 17 is arranged so that it lines the water channel.
• a hydrogen peroxide or other oxygen evolving compounds may be added to the humidification and cooling water, which is fed into the cell on the anode side. Since the oxygen is released in the vicinity of the catalyst, CO adsorption at the anode catalyst may be avoided, in a manner which is effective and which leads to less consumption of oxygen. Part of the hydrogen peroxide will be decomposed at the electrode surface to generate oxygen with the reaction H 2 0 2 ⁇ >H 2 0+l/20 2 . In this system possible benefits of hydrogen peroxide are achieved even if the decomposition is not complete.
• the path of the hydrogen peroxide and evolved oxygen is marked as arrows in Fig. 4. However, this method can be applied to other direct water humidification systems in polymer fuel cells.
• Figure 5 shows a gas distribution layer 3, the edges of which has been treated with a hydrophobous polymer to prevent the water from entering the cell gas chamber.
• the gas distribution layers can have a porosity exceeding 90% and they should be good electrical conductors and have proper corrosion resistance against acid proton conducting membrane .
• the present invention may be combined with the conventional serpentine channel structure. The principle of this is illustrated in figure 6.
• the same reference numbers has been used as in the embodiment according to Fig. 2.
• the anode layer side of each bipolar plate 1, 7 may be provided with an anode gas channel 19 and at least one water inlet 20.
• a water outlet 21 may also be provided.
• the cathode layer side of each bipolar plate is provided with at least one cathode gas channel 22.
• Fig. 7 An alternative structure for the water channels is presented in Fig. 7.
• the catalyst layer 16 is located on top of the membrane 4.
• a hydrophobous layer 18 is positioned between the membrane and the gas distribution layer. The function of this layer 18 is to let gas diffuse to the electrode (catalyst layer) but not let the water to escape from the water channel 3a.
• the embodiment according to Fig. 7 may be used for operation of a liquid-gas direct methanol fuel cell.
• the anode side of the cell is fed with a liquid water-methanol mixture, which is totally or partially evaporated in the cell.
• the liquid mixture is fed in such a way that most part of the anode electrode is in contact with a thin film of liquid methanol-water mixture.
• the remaining area of the anode electrode is in contact with the gas phase free from liquid. This in order to enable both fast release of gaseous carbon dioxide as well as for humidifying of membrane by water vapor reactant to remaining part of the anode area.
• Water and methanol are transferred from fuel feeding channels to the anode electrode both directly and via gas phase. This is illustrated by means of arrows in Figure 7.
• the above described method may also be applied to other types of fuel cell structures which are direct liquid cooled.
• the water channel structure is preferably applied to the anode side. However, this structure can also be applied to the cathode side or to both sides simultaneously.

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

Priority Applications (5)

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• 2000
  • 2000-07-07 SE SE0002601A patent/SE518621C2/sv not_active IP Right Cessation
• 2001
  • 2001-06-29 WO PCT/SE2001/001514 patent/WO2002005373A1/en not_active Ceased
  • 2001-06-29 JP JP2002509127A patent/JP5111714B2/ja not_active Expired - Lifetime
  • 2001-06-29 CN CNB018113664A patent/CN1235305C/zh not_active Expired - Lifetime
  • 2001-06-29 AU AU2001267984A patent/AU2001267984A1/en not_active Abandoned
  • 2001-06-29 CA CA2412180A patent/CA2412180C/en not_active Expired - Lifetime
  • 2001-06-29 EP EP01945875A patent/EP1301956B1/en not_active Expired - Lifetime
• 2003
  • 2003-01-07 US US10/248,304 patent/US7790330B2/en not_active Expired - Lifetime

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