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
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/2465—Details of groupings of 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
  • H01M8/02—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
  • H01M8/02—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
  • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
  • H01M8/028—Sealing means characterised by their material
  • H01M8/0284—Organic resins; 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
  • H01M8/10—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
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/2465—Details of groupings of fuel cells
  • H01M8/247—Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
  • H01M8/248—Means for compression of the fuel cell stacks
• • 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
  • H01M8/2465—Details of groupings of fuel cells
  • H01M8/2484—Details of groupings of fuel cells characterised by external manifolds
  • H01M8/2485—Arrangements for sealing external manifolds; Arrangements for mounting external manifolds around a stack
• • 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

• the invention relates to a fuel cell stack with a row of cells made up of a plurality of unit cells which are formed with cell-internal media ducts and which are accommodated between two end plates clamped together in a fuel cell stack housing.
• the invention further relates to a method for producing such a fuel cell stack.
• Fuel cells are used to provide electrical energy through an electrochemical reaction, with several fuel cells connected in series being able to be combined to form a fuel cell stack in order to increase the usable power.
• Each of the fuel cells includes an anode, a cathode, and a proton conductive membrane separating the anode from the cathode and coated with a catalyst to promote the electrochemical reaction.
• bipolar plates are provided on both sides of the membrane for supplying the reactants and, if necessary, a coolant.
• gas diffusion layers are used in order to distribute the reactants introduced in the bipolar plates as evenly as possible over the entire surface of the membrane coated with the catalyst.
• This plurality of fuel cells combined in a fuel cell stack is generally pressed using tension elements with a force in the range of several kilonewtons in order to achieve a sufficient To achieve contact pressure on the catalyst-coated membrane to reduce ohmic losses and to avoid leaks in the seals used by means of the high compression.
• a fuel cell stack is formed by alternately stacking bipolar plates and membrane electrode assemblies (MEAs), collectively referred to as a unit cell, thus forming a cell array.
• MEAs membrane electrode assemblies
• a polymer seal is applied either to the surface of the bipolar plates or to the surface of the MEA, which is compressed by the final pressing of the cell row using a clamping system and thus provides the sealing effect.
• EP 0 897 196 A1 shows a method for producing an insulating component for a high-temperature fuel cell.
• a method for producing a fuel cell arrangement is known from DE 11 2004001 748 B4, wherein the fuel cell arrangement is cast with a sealant.
• a method for producing a fuel cell stack, in which sealing is carried out using an electrically insulating potting compound, is shown in DE 10 2010 011 206 A1. Casting or encapsulating the fuel cell with the insulating component is not disclosed.
• a problem with known seals is hydrogen permeability, which necessitates continuous venting of the stack casing.
• the loss of hydrogen from the stack can result in air initially being present on the anode side when the fuel cell system is restarted (so-called air-air start), which leads to considerable damage to the fuel cell.
• the object of the present invention is to provide a fuel cell stack with improved tightness. It is also an object to specify an improved method for producing such a fuel cell stack. This object is achieved by a fuel cell stack having the features of claim 1 and by a method having the features of claim 10. Advantageous configurations with expedient developments of the invention are specified in the dependent claims.
• the fuel cell stack mentioned at the outset is characterized in that the row of cells present in the fuel cell stack housing is completely embedded in an electrically insulating cast material.
• the row of cells is sealed with regard to gas exchange by delaying the loss of hydrogen from the stack and additionally reducing cavities present in the fuel cell stack housing, the penetration of air into the fuel cell stack being prevented or at least drastically reduced.
• the cast material is supported on the fuel cell stack.
• the mechanical stability of the row of cells can also be improved by casting in a suitable material, since the adhesive force of the cells to one another is no longer based solely on the seal, but the row of cells is supported on the housing.
• materials with a very low H2 permeation or gas permeation are preferred, since these have a more secure seal against hydrogen and other gaseous media.
• the unit cell comprises a membrane electrode arrangement held between two bipolar plates, and if there is a lateral overhang on the membrane electrode arrangement, on a frame enclosing the membrane electrode arrangement or on one of the membrane electrode arrangements laterally surrounding seal is formed.
• the thickness of the cast layer can preferably be selected in such a way that the remaining gas volume inside the stack housing is reduced to such an extent It is emphasized that, taking into account and complying with hydrogen safety guidelines and standards, there is no need for any ventilation of the stack housing. It has proven to be particularly useful if the overhang is completely embedded in the casting material.
• the overhang is only partially embedded in the casting material.
• the thickness of the encapsulation layer can be reduced and/or the overhang of the MEA can be increased in order to have a positive effect on electrical creepage distances. This refinement also reduces the mass of the fuel cell stack.
• the fuel cell stack housing is hermetically sealed, with cavities present in the fuel cell stack housing being reduced by the cast material present.
• the fuel cell stack housing is formed without a fan, as a result of which any ventilation of the fuel cell stack housing can be dispensed with.
• At least one of the end plates is provided with all the connections for supplying the unit cells with the operating media, which are fluidically connected to the cell-internal media ducts. In this way, the media are all fed into the fuel cell stack from one and the same side and also fed out again, which offers advantages when using the installation space available in a motor vehicle.
• the advantages and preferred embodiments described in connection with the fuel cell stack according to the invention also apply to the method according to the invention. It comprises the step of stacking unit cells provided with cell-internal media ducts made of bipolar plates and intermediate membrane electrode arrangements to form a row of cells, the step of bracing the stacked unit cells between two end plates in a fuel cell stack case, and the step of casting the cell bank in an electrically insulating cast material that is supported on the fuel cell stack case.
• FIG. 1 shows a schematic representation of a fuel cell device
• FIG. 3 shows a representation corresponding to FIG. 2 with a projection of the MEA that remains free from the cast material.
• FIG. 1 schematically shows a fuel cell device 1 which comprises a fuel cell stack 2 which consists of a plurality of fuel cells connected in series.
• This fuel cell device 1 can in particular be part of a fuel cell vehicle, not shown in detail.
• Each of the fuel cells includes an anode and a cathode, and a proton conductive membrane separating the anode from the cathode.
• the membrane is formed from an ionomer, preferably a sulfonated tetrafluoroethylene polymer (PTFE) or a polymer of perfluorinated sulfonic acid (PFSA).
• PTFE sulfonated tetrafluoroethylene polymer
• PFSA perfluorinated sulfonic acid
• the membrane can be formed as a sulfonated hydrocarbon membrane.
• Fuel, for example hydrogen, from a fuel tank 20 is supplied to the anodes via anode chambers within the fuel cell stack 2 .
• PEM fuel cell polymer electrolyte membrane fuel cell
• fuel or fuel molecules are split into protons and electrons at the anode.
• the membrane lets the protons (H + ) through, but is impermeable to the electrons (e _ ).
• the following reaction takes place at the anode: While the protons pass through the membrane to the cathode, the electrons are conducted to the cathode or an energy storage device via an external circuit.
• Cathode gas for example oxygen or oxygen-containing air
• a compressor 21 and humidified by a humidifier 22 can be supplied to the cathodes via cathode chambers within the fuel cell stack 2, so that the following reaction takes place on the cathode side: O2 + 4H + + 4e - > 2H2O (reduction/electron acceptance).
• FIG. 2 shows a fuel cell stack 2 with a row of cells made up of a plurality of unit cells 4 which are formed with cell-internal media ducts and which are accommodated in a fuel cell stack housing 5 between two end plates 3 clamped together.
• Each of the unit cells 4 comprises two bipolar plates 7 and a membrane electrode arrangement 8 accommodated between them.
• the end plates 3 are provided with connections 10 for supplying the unit cells 4 with the operating media, which are flow-mechanically connected to the cell-internal media ducts.
• the row of cells present in the fuel cell stack housing 5 is completely embedded in an electrically insulating cast material 6; ie also the projections 9 present in the membrane electrode assemblies 8 or their frames or seals.
• the Supernatants 9 themselves do not have to be part of the electrochemically active membrane electrode assemblies 8 . These can be present on the frame surrounding the respective membrane electrode arrangement 8, which positively influences the stability of the stack and additionally seals it laterally. Due to the cast material 6, ventilation of the fuel cell stack housing 5 can be dispensed with, which means that it is therefore formed without a fan. In the exemplary embodiment shown, the cast material 6 is supported on the fuel cell stack housing 5, which also improves the mechanical stability of the cell row.
• the molding material 6 is preferably formed from a material selected from the group consisting of thermoplastic urethane (TPU), ethylene propylene diene (monomer) rubber (EPDM) and chlorobutyl rubber.
• FIG. 3 shows a further fuel cell stack 2 in which the overhangs 9 of the frames of the membrane electrode arrangements 8 are not completely covered by the cast material 6, which leads to a reduction in the overall mass of the stack.
• the row of cells is completely embedded in the casting material 6 because the casting material 6 completely penetrates the protrusions 9 axially and is thus impregnated.
• the fuel cell stack 2 according to the invention and the method according to the invention for producing a fuel cell stack 2 are characterized in that the row of cells is embedded in an electrically insulating cast material 6 which seals against gas exchange and reduces cavities present in the stack housing.

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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 (2)

Publications (1)

Family

ID=78528900

Family Applications (1)

Country Status (5)

Family Cites Families (6)

• 2020
  • 2020-10-30 DE DE102020128557.4A patent/DE102020128557A1/de active Pending
• 2021
  • 2021-10-25 EP EP21802612.8A patent/EP4179587A2/de active Pending
  • 2021-10-25 WO PCT/EP2021/079523 patent/WO2022090145A2/de unknown
  • 2021-10-25 CN CN202180049544.5A patent/CN115836418A/zh active Pending
  • 2021-10-25 US US18/005,563 patent/US20230275252A1/en active Pending

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