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
  • H01M8/0297—Arrangements for joining electrodes, reservoir layers, heat exchange units or bipolar separators to each other
• • 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
  • H01M4/8605—Porous electrodes
  • H01M4/8621—Porous electrodes containing only metallic or ceramic material, e.g. made by sintering or sputtering
• • 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
  • H01M4/88—Processes of manufacture
  • H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
  • H01M4/8882—Heat treatment, e.g. drying, baking
  • H01M4/8885—Sintering or firing
• • 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
• • 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
  • H01M8/0204—Non-porous and characterised by the material
  • H01M8/0206—Metals or alloys
  • H01M8/0208—Alloys
  • H01M8/021—Alloys based on iron
• • 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
  • H01M8/0204—Non-porous and characterised by the material
  • H01M8/0223—Composites
  • H01M8/0226—Composites in the form of mixtures
• • 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
  • H01M8/0232—Metals or alloys
• • 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
  • H01M8/0243—Composites in the form of mixtures
• • 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
• • 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
• • 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
  • H01M8/242—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes comprising framed electrodes or intermediary frame-like gaskets
• • 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
  • H01M8/2425—High-temperature cells with solid electrolytes
• • 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
  • H01M8/0204—Non-porous and characterised by the material
  • H01M8/0215—Glass; Ceramic materials
• • 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
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the invention relates to a SOFC stack according to the preamble of patent claim 1.
• a fuel cell stack is an arrangement of several planar fuel cells.
• Fuel cells consist of an ion-conducting electrolyte, electrodes and elements for contacting the electrodes and for distributing the fuels across the electrode surface.
• Fuel cells are generally distinguished by the material of the electrolyte used, which also determines the operating conditions and in particular the operating temperature.
• the solid oxide fuel cell (SOFC - Solid Oxide Fuel Cell) used here is operated at temperatures above 800 ° C.
• SOFC - Solid Oxide Fuel Cell As an ion-conducting electrolyte, which is contacted on both sides via two electrodes, anode and cathode, a ceramic is used which conducts O 2 " ions, but is insulating for electrons Such a ceramic is, for example, yttrium-stabilized zirconium oxide, YSZ Because of the low conductivity of the ceramics, thin electrolytes ( ⁇ 50 ⁇ m) are preferably used either in a self-supporting or in a non-self-supporting form, eg as so-called ASE (anode supported electrolyte) .Ceramic layers, possibly with metals, also come as electrodes The unit of electrolyte and electrodes is called MEA (membr
• each element is arranged between each two MEAs, which electrically connects the anode of an MEA to the cathode of the next MEA, with the best possible contact being distributed over the entire electrode surface being required.
• These elements are referred to as bipolar plates, interconnectors or current collectors.
• the anode of the fuel cells is supplied with a reducing, mostly hydrogen-containing fuel and the cathode is an oxidizing agent, e.g. Air.
• the bipolar plates serve to separate these gases and to supply and distribute fuel and oxidant over the electrode surfaces.
• channels for guiding the gas are usually formed on each side of the bipolar plate. In the edge area of the fuel cells, these channels typically go bundled into an external gas supply and are sealed off from the environment.
• end plates are used. They are often thicker than the bipolar plates in order to be more mechanically stable and to allow current to flow parallel to the plane of the electrodes, and provide channels for gas conduction only on one side. Otherwise they are structurally and functionally analogous to the bipolar plates, which is why the following about bipolar plates also applies to the end plates.
• Bipolar plates of ceramic material or metal are known from the prior art.
• a ceramic material for example, LaCrO 3 is used, since it at the high Operating temperatures of the SOFC has sufficient conductivity and can be well adapted to the thermal expansion behavior of the electrolytes.
• a disadvantage is the high production price due to the problematic processing of such large-area ceramic plates.
• ferritic alloys which are alloyed in such a way that an oxide layer is formed on their surface, by means of which a necessary corrosion resistance of the metals is achieved without excessively impairing the electrical conductivity.
• Such alloys for bipolar plates are known, for example, from the publication DE 197 05 874 A1 (Al and / or Cr oxide layer) or the document DE 100 50 010 A1 (Mn and / or Co oxide layer). In both cases (ceramic / metallic material), the bipolar plates for a prior art SOFC stack are rigid and of a given thickness.
• a cohesive connection of the stack can take place.
• the individual cells are provided at their edge with a hardening sealing paste, eg glass solder, which is applied around the bipolar plates around.
• This sealing paste hardens when the stack heats up, the so-called joining, and connects the cells to one another.
• a hardening sealing paste eg glass solder
• This sealing paste hardens when the stack heats up, the so-called joining, and connects the cells to one another.
• a ceramic paste preferably with a chemical composition corresponding to the contacted electrode.
• Such a paste is known for example from the document DE 199 41 282 Al.
• a disadvantage of these firmly joined fuel cell stacks is that subsequent shrinkage or bleeding of the seals or sintering or creep of the bipolar plates either lead to loss of contact or leakage of the stack. The reason is that there are no compensating elements for changes in the thickness of the gasket or bipolar plate.
• a stack can be provided with flexible seals and be pressed together, wherein externally compensating elements are provided.
• DE 19645111 C2 discloses an arrangement for a SOFC stack, in which buffer elements acting as springs are provided on the outside of the stack in the prestressing force path. Through these buffer elements, a nearly constant contact pressure is achieved over a wide temperature range.
• a rod-shaped compression element is presented for biasing a SOFC stack, in which a combination of the materials used achieves a thermal expansion coefficient adapted to the stack. In this way, the contact force can either be kept constant over a wide temperature range or even controlled change in a predetermined manner depending on the temperature.
• a disadvantage of these solutions is that a resilient or ausreted with, whereby neither manufacturing tolerances of the bipolar plates and electrodes are compensated, nor a secure contact is ensured in non-permanently elastic seals.
• the PEMFC Polymer Electrolyte Membrane Fuel Cell
• this stack elastic, balancing elements are used. Such elements include a gauze made of graphite fibers, which is used between the electrode and bipolar plate for better contacting or resilient bipolar plates.
• the polymer film used as electrolyte is elastic. In this concept, both manufacturing tolerances and thermal expansion can be compensated by the contact elements, which leads to a secure contacting of the electrodes. At the same time, external compensating elements can be dispensed with, allowing a more compact construction of the stack.
• the object of the invention is therefore to specify a SOFC stack which has internal balancing elements which satisfy the stated requirements and adversely affect neither the compact design nor the production costs of the SOFC stack.
• a SOFC stack with bipolar plates, each having a base plate and thus connected one or more contact elements on one or both sides of the base plate, which are characterized in that the base plate is rigid and gas-tight and the contact elements are elastically or plastically deformable and arranged or designed so that they are gas-permeable perpendicular to the plane of the base plate ,
• the contact elements of the bipolar plates according to the invention realize the internal compensating elements.
• the bipolar plates are rigid on the one hand by their base plate, whereby they stabilize the stack and prevent breakage of the MEAs. On the other hand, they are able by the contact elements, local thickness differences due to manufacturing tolerances of the electrodes or due to thermal expansion or creep processes o.a. compensate.
• the gas permeability of the contact elements serves to supply the reaction gases to the electrodes.
• a lateral distribution of the gases can take place between the base plate and the contact element, if appropriate by means of additional channels incorporated in the base plate.
• the invention will be explained in more detail with reference to a Principalsbeiffles shown in a drawing.
• the figure shows an embodiment of the SOFC stack according to the invention in a schematic cross-sectional drawing. Only part of the SOFC stack is reproduced.
• the MEAs 1 of two fuel cells are shown.
• the MEAs 1 each have an electrolyte 2, and two electrodes, cathode 3 and anode 4, on.
• Between or above and below the MEAs 1 are bipolar plates 5, which consist of a base plate 6 and contact elements 7. O- and below the outer bipolar plates 5 close in the SOFC stack more, not shown here MEAs 1 at.
• a rigid seal 8 is arranged between the individual MEAs 1.
• the contact elements 7 are made of expanded metal.
• the material used is a ferritic metal which is mixed with finely divided, highly dispersive oxides of rare earth metals. Such metal alloys are characterized by a high elasticity even at high temperatures, since the finely divided additives a coarse-grained recrystallization of the material is prevented. A sheet of this material is suitably cut and subsequently stretched. This results in a 3-dimensional structure that springs perpendicular to the plane of the sheet.
• the erected webs act as contact points and the cuts serve as gas passages. By varying the arrangement and the length of the cuts, the density of the contact points and the size of the gas passages can be optimally balanced against each other.
• a plurality of superimposed contact elements 7 can also be made Expanded metal are used, which differ in the arrangement and / or the size of the gas passages. In this case, an arrangement is preferred which has smaller gas openings in a greater density with contact elements 7 closer to the MEAs than spring elements 7 located closer to the bipolar plates 5.
• contact elements 7 it is advantageous to produce the contact elements 7 in one piece over the entire surface of the electrodes to be contacted. If a plurality of contact elements 7 are used next to each other or above each other, it is favorable to use them in a materially cohesive manner, e.g. by welding, to connect together to prevent an increase in the electrical contact resistance between the individual contact elements 7 by surface oxidation.
• a ferritic metal is also provided.
• the material thickness is chosen so that the base plate 6 mechanically stabilizes the stack.
• the contact elements 7 are arranged on both sides materially, e.g. by laser or spot welding.
• the base plate 6 can be incorporated channels for the distribution of fuel and / or oxidant.
• the gas distribution can also take place only through the open structure of the contact elements 7.
• protruding tips can be smoothed after stretching by a rolling process.
• the contact element is brought to a defined thickness.
• Another way to Preventing pressure peaks is to additionally insert porous metal foils between contact elements 7 and electrodes 3, 4. This also advantageously results in an increased electrical conductivity in the direction of the plane of the electrodes 3, 4.
• the metal foils can also be connected to the contact elements 7, for example, again by welding.
• the contact element 7 has elastic properties and is therefore able to compensate for manufacturing tolerances of the MEAs and shifts of the components of the stack to each other due to thermal expansion or Kriechreaen. Also, contact disturbances are prevented by external influences such as shocks and vibrations.
• plastically deformable contact elements 7 see by means of a curing ceramic see paste according to the mentioned in the introduction state of
• the application of the ceramic paste can be carried out by screen printing, stencil printing or in a spray process.
• a sheet can be provided with punched holes and embossed in a three-dimensional, resilient structure (waves, trapezoids, etc.).
• U-shaped incisions can be punched into a metal sheet and the resulting webs can be used as resilient tongues. conditions are pushed out of the sheet metal plane.
• spiral or circular cuts can be punched, resulting in the formation of spiral or cup springs.
• a suitable base plate 6 as a bipolar plate 5 of the SOFC stack according to the invention.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=37125352

Family Applications (1)

Country Status (10)

Families Citing this family (22)

Family Cites Families (14)

• 2005
  • 2005-05-18 DE DE102005022894A patent/DE102005022894A1/de not_active Ceased
• 2006
  • 2006-05-18 RU RU2007146984/09A patent/RU2007146984A/ru not_active Application Discontinuation
  • 2006-05-18 JP JP2008511549A patent/JP2008541389A/ja not_active Withdrawn
  • 2006-05-18 WO PCT/DE2006/000853 patent/WO2006122534A2/de active Application Filing
  • 2006-05-18 EP EP06742360A patent/EP1882279A2/de not_active Withdrawn
  • 2006-05-18 BR BRPI0610685-4A patent/BRPI0610685A2/pt not_active IP Right Cessation
  • 2006-05-18 US US11/920,640 patent/US20090297904A1/en not_active Abandoned
  • 2006-05-18 CN CNA2006800263227A patent/CN101223664A/zh active Pending
  • 2006-05-18 CA CA002608813A patent/CA2608813A1/en not_active Abandoned
  • 2006-05-18 KR KR1020077028597A patent/KR20080008408A/ko not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events