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
  • H01M8/04089—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
  • 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
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0247—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form
• • 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
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M2008/1095—Fuel cells with polymeric electrolytes
• • 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

• Fuel cell comprising an assembly capable of managing the water produced by said battery.
• the invention relates to a fuel cell and more particularly to a fuel micro-cell comprising:
• an assembly disposed on at least a portion of an outer surface of said cathode and comprising at least one hydrophilic element in contact with at least a first zone of the outer surface of the cathode and a hydrophobic element covering all of a cathode. face of the hydrophilic element, opposite to the outer surface of the cathode.
• a basic fuel cell used in a miniature fuel cell comprises an electrolytic membrane 1 provided with front and rear faces 1a and 1b.
• the front and rear faces 1a and 1b are respectively and successively covered by first and second catalytic layers 2a and 3a and diffusion layers 2b and 3b.
• the first catalytic layer 2a and the first diffusion layer 2b form the anode 2 while the second catalytic layer 3a and the second diffusion layer 3b form the cathode 3.
• First and second collectors 4 and 5 are respectively disposed on the outer faces of the first and second layers of diffusion 2b and 3b.
• the stack EME and the first and second current collectors 4 and 5 form a single elementary cell.
• the hydrogen generally used as fuel
• the transverse passages 4a of the anode current collector 4 can pass through the transverse passages 4a of the anode current collector 4 to reach the diffusion layer 2b of the anode 2.
• Oxygen or air generally serving as oxidant passes through the transverse passages 5a of the cathode current collector 5 to reach the diffusion layer 3b of the cathode 3.
• the water produced during operation of the fuel cell is discharged through the same transverse passages 5a.
• the so-called stack-type filter-press cells generally comprise a large number of elementary cells arranged in series. Each cell comprises a stack comprising an anode and a cathode, separated by an electrolytic membrane.
• the stack generally called “EME” (Electrode-Membrane-Electrode) type stack, is arranged between two current collector plates.
• the set of elementary cells form a filter-press assembly, with clamping plates bolted on either side of a series of EME stacks.
• FIG. 2 illustrates an electrochemical cell of filter-press type which comprises, as in FIG. 1, an assembly 6 formed by the anode 7, the electrolytic membrane 8 and the cathode 9 is disposed between two fluid distribution layers 10 and 11.
• the layers 10 and 11 are electrically conductive layers and serve as conduits for gases and liquids entering and exiting the electrochemical cell from and to circulation channels 12.
• the layers 10 and 11 are electrically conductive layers and serve as conduits for gases and liquids entering and exiting the electrochemical cell from and to circulation channels 12.
• the patent application US-A-2005/0181264 proposes to use a particular cathodic current collecting plate improving the management of the water produced by an electrochemical cell of a filter-press type cell.
• the layer 11 disposed on the outer surface 9a of the cathode 9 has a certain hydrophobicity so as to push the water produced by the electrochemical cell and contained in the cathode 9, to the channels 12.
• the hydrophobicity of the layer 11 is, however, lower than that of the cathode 9.
• the walls of the channels 12 are formed by a stack of a porous hydrophilic layer 13 and a layer 14 impermeable to fluids.
• the porous hydrophilic layer 13 attracts, by capillary forces, the water accumulated in the cathode 9 and the impervious layer 14 forms a physical barrier between the various electrochemical cells, the assembly favoring the evacuation of water towards the channels 12 .
• the water management is controlled by diffusion supports contacted with the catalytic layers of the electrodes of an EME type stack.
• the diffusion supports each comprise two superimposed layers: a first layer, in contact with the electrode and formed of a porous matrix and particles intended to transfer the water, and a second hydrophobic layer covering the entire first layer.
• the object of the invention is a fuel cell that overcomes the drawbacks of the prior art. More particularly, the invention aims at a fuel cell provided with an assembly for effectively managing the humidity in the fuel cell and having optimum performance.
• the hydrophobic element comprises at least one through opening releasing a zone of said face of the hydrophilic element.
• FIGS. 1 and 2 respectively illustrate first and second embodiments of an electrochemical cell of a filter-press type cell according to the prior art.
• FIG. 3 represents the evolution of the flow of water in an electrochemical cell as a function of temperature, for three types of exchange surfaces.
• FIG. 4 represents a particular embodiment of a fuel cell according to the invention.
• FIGs 5 and 6 show two alternative embodiments of the embodiment shown in Figure 4.
• the amount of water discharged, in liquid form and / or evaporated is not greater than that produced by the cathode, so that the electrolyte membrane does not not dried up by lack of water.
• the amount of water produced by the cathode depends solely on the operating current of the fuel cell while the amount of water discharged depends on the temperature in the fuel cell and the wettability of the exchange surface between the stack and the outside of the fuel cell.
• the curves A, B and C represent the evolution of the flow of water discharged into an electrochemical cell as a function of the temperature of the fuel cell, respectively for three types of surface. 'exchange.
• the exchange surface corresponding to the curve B is a reference exchange surface, corresponding to the outer surface of a graphite cathode.
• the exchange surfaces corresponding respectively to curves A and C are respectively hydrophobic and hydrophilic.
• the hydrophobic exchange surface is, for example, obtained by covering the outer surface of a cathode with a silicon oxycarbide film while the hydrophilic surface is obtained by covering the outer surface of the same cathode with a film of silicon oxycarbide and by providing UV irradiation.
• the equilibrium point between the water produced and the water discharged into the electrochemical cell was determined by referring to FIG. 3 curves D, E and F.
• the curves D to F represent, in fact, the evolution the flow rate of the water produced by the cathode, for operating currents of 100 mA, 15OmA and 20OmA, respectively. It can thus be seen that for a produced water flow (curve D, E or F) there are two equilibrium points, that is to say two possible operating temperatures, depending on the environmental conditions. These two points of equilibrium correspond to the intersections of the curve D, E or F with the curves A and c.
• the moisture in the anode-electrolytic membrane-cathode stack must therefore be managed by an assembly for regulating, in a controlled manner, the water produced by the cathode.
• the water produced in a fuel cell and more particularly in a micropile with fuel, is managed and / or regulated by an assembly disposed on at least a portion of an outer surface of the cathode.
• the assembly comprises at least one hydrophobic element and a hydrophilic element, preferably each having a thickness of between 10 ⁇ m and 10 mm.
• a fuel micropile 15 comprises a successive stack of an anode 16, an electrolyte membrane 17 and a cathode 18.
• the anode 16 and the cathode 18 respectively have outer surfaces 19 and 20 on which current collectors 21 and 22 are respectively arranged.
• the current collectors 21 and 22 are integrated in the stack 6. They are each formed by a thin layer having through-passages, releasing areas of said outer surfaces.
• the cathode current collector 22, provided with said through passages, is covered by a hydrophilic element, preferably formed by a hydrophilic layer 23.
• a hydrophilic element preferably formed by a hydrophilic layer 23.
• the hydrophilic layer 23 comprises, for example a material selected from porous graphite, a ceramic treated to obtain a hydrophilic surface and a polymer having a hydrophilic function, while the hydrophobic element may comprise a material chosen from fluorinated polymers, oxycarbide of amorphous silicon and carbon nanotubes.
• the hydrophilic layer 23 also has a face 24, preferably flat, and opposite to the face which is in contact with the outer surface 20 of the cathode 18.
• the thickness of the hydrophilic layer 23 is greater than that of the cathode current collector 23.
• the cathode current collector 22 has a face 25 completely covered by the hydrophilic layer 23 Said face 25 of the cathode current collector 22 is the face opposite to that which is in contact with the cathode 18.
• a hydrophobic element covers the entire face 24 of the hydrophilic element 23. It forms a physical barrier to liquid water between the external environment and the fuel micro-cell.
• the hydrophobic element and the hydrophilic element are permeable to gaseous oxidants, such as air or oxygen, so that they can easily reach the cathode.
• the hydrophobic element comprises at least one through opening releasing at least one zone of the face 24 of the hydrophilic element 23.
• the hydrophobic element is in the form of a hydrophobic layer 26 provided with through apertures releasing areas of the face 24.
• the through openings 27 of the hydrophobic layer 26 are uniformly distributed in said layer whereas in FIG. they are distributed unevenly.
• the hydrophobic layer 26 comprises, in fact, three through openings.
• a first opening 27a is substantially disposed in the center of the layer 26 and two openings 27b, narrower than the first opening 27a, are arranged near the edges of said layer 26.
• the distribution of the through openings 27 in the hydrophobic layer 26 is such that the through openings 27 of the hydrophobic layer 26 are arranged above the through-passages of the current collector 22.
• the current collector passages 22 and the openings of the hydrophobic layer 26 have, advantageously an identical width, so that a through opening 27 extends a through passage of the current collector 22.
• the hydrophobic zones of the hydrophobic layer 26, delimited by the through openings 27, are more particularly arranged. above the areas constituting the current collector 22 and delimited by the through passages.
• the regulation of the humidity in the stack is thus done by a storage of water in the first regions of the hydrophilic layer 23 while the water is discharged by second regions of the hydrophilic layer 23.
• the first regions of the hydrophilic layer 23 are the regions of the hydrophilic layer 23 covered by the hydrophobic layer 26 and the second regions are those not covered by said layer.
• the evacuation of the water by the second regions of the hydrophilic layer 23 is, in fact, carried out via the free zones of the face 24.
• the presence of the through openings in the hydrophobic layer 26 makes it possible to obtain localized retention of water in the first regions of the hydrophilic layer and localized evacuation in the second regions of said layer.
• the storage of the water is advantageously carried out in zones where the reaction of the cell is less, ie in first regions of the cell. the hydrophilic layer which are not only in contact with the hydrophobic layer 26 but also with the face 25 of the current collector 22.
• the volume of water storage depends on the thickness of the hydrophilic layer while the amount of water discharged depends on the width of the through openings made in the hydrophobic layer 26. It is then possible to find a balance between the quantity of water evacuated by the free zones of the face 24 and the quantity of water stored in the first regions of the hydrophilic layer 23, so as to retain a portion of moisture near the electrolytic membrane. It is also possible, in some cases, to promote the evacuation of water with respect to its storage, by increasing the width of the through openings and / or by decreasing the thickness of the hydrophilic layer. This is particularly interesting when the battery has a high operating current.
• the shape of the through openings can be of any type: round, square ...
• the non-uniform distribution of the through-openings in the hydrophobic layer has the advantage of obtaining a different water management between the center and the edge of the outer surface 20 of the cathode 18. This makes it possible to compensate for the differences in operation that can occur. occur between the periphery and the center of the stack 6. In fact, in general, warming due to the current collection is higher at the periphery than at the center of the stack.
• the hydrophilic and hydrophobic elements can be formed either by deposition techniques from microelectronics, or by conventional assembly techniques such as pressing.
• the hydrophilic element can be deposited on the outer surface of the cathode in the form of a thin layer, preferably consisting of a material chosen from porous graphite, a ceramic treated to obtain a hydrophilic surface and a polymer having a hydrophilic function such as, for example, the acid function (eg Nafion®). It can also be formed by a thin film of treated fabric to obtain a hydrophilic or polymer surface, the film being then pressed onto the outer surface 20 of the cathode 18.
• a ceramic or fabric can indeed be treated to have a surface hydrophilic.
• This treatment may, for example, be a plasma treatment.
• the hydrophobic element may be formed by deposition of a thin layer, preferably consisting of a material chosen from fluorinated polymers, amorphous silicon oxycarbide and carbon nanotubes. It can also be formed by a thin film of fabric treated to obtain a hydrophobic surface, the fabric being then pressed onto the stack.
• the hydrophilic layer 23 may be deposited on the outer surface 20 of the cathode 18, by coating with an absorbent gel solution, the solution being then dried and the water evaporated. Then, the hydrophobic layer 26 may, for example, be deposited by physical vapor deposition on the face 24 of the hydrophilic layer 23, through a stencil mask defining the shape of the through openings 27 for the evacuation of the 'water.

Landscapes

• 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)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (2)

Family

ID=37507555

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (4)

Family Cites Families (10)

• 2006
  • 2006-03-17 FR FR0602407A patent/FR2898731B1/fr active Active
• 2007
  • 2007-03-08 US US12/224,896 patent/US7993794B2/en not_active Expired - Fee Related
  • 2007-03-08 JP JP2009500885A patent/JP5242545B2/ja not_active Expired - Fee Related
  • 2007-03-08 EP EP07731115.7A patent/EP1997178B1/fr not_active Not-in-force
  • 2007-03-08 CN CN2007800135030A patent/CN101421881B/zh not_active Expired - Fee Related
  • 2007-03-08 WO PCT/FR2007/000418 patent/WO2007118945A2/fr not_active Ceased

Also Published As

Similar Documents

Legal Events