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
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
  • H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
  • H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
• • 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
  • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
  • H01M8/1213—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material
• • 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
  • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
  • H01M8/1213—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material
  • H01M8/1226—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material characterised by the supporting layer
• • 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
  • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
  • H01M2008/1293—Fuel cells with solid oxide 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
• • 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

• Solid oxide fuel cell Solid oxide fuel cell and process for its manufacture
• the invention relates to a solid oxide fuel cell according to the preamble of claim 1 and a method for its production.
• solid oxide fuel cell or SOFC
• SOFC solid oxide fuel cell
• the power density of solid oxide fuel cells depends not only on the quality of the anode and cathode, but above all on the material and thickness of the electrolyte and the operating temperature. Operating temperatures of less than, in particular when the solid oxide fuel cell is used in automobiles 800 ° C preferred in order to be able to use metallic materials for the bipolar plates and other parts of the fuel cell, for example steel, which is subject to severe corrosion at higher temperatures.
• the electrolyte layer which is made from a high-melting metal oxide, particularly yttrium-stabilized zirconium dioxide, must be absolutely gas-tight on the one hand to separate the anode compartment from the cathode compartment, and on the other hand as thin as possible to ensure rapid transport of the oxygen ions from the cathode to the anode.
• a high-melting metal oxide particularly yttrium-stabilized zirconium dioxide
• Such thin, gas-tight electrolyte layers can only be achieved using sintering techniques. So far, high sintering temperatures of around 1400 ° C and long sintering times have been required.
• the sintering of the electrolyte layer takes place on the electrode layer which has been applied to the support structure, the support structure being a porous layer, via which - in the case of an anode-supported SOFC - the fuel is supplied.
• the support structure must consist of a material that can withstand the high sintering temperature. This is the case with a support structure made of anode material made from a mixture of yttrium-stabilized Zr0 2 and Ni oxide, but not with a support structure or cathode material made of metal.
• solid oxide fuel cells in which the electrode layer is provided on a metal support structure are preferred, especially for automotive applications, since this results in faster heating, higher redox resistance and cost savings.
• a simpler joining technique is possible because, for example, the outer circumference of the metallic support structure can be tightly connected to the metal bipolar plate by laser welding.
• the electrolyte layer is usually applied to a metallic support structure by thermal spraying. Since the tightness of an electrolyte layer produced by thermal spraying is significantly lower than that of an electrolyte layer produced by sintering, the electrolyte layer must, however, be made significantly thicker if it is deposited by thermal spraying. That is, in order for the electrolyte layer of a solid oxide fuel cell with a metallic supporting structure to be gas-tight, layer thicknesses of up to 60 ⁇ m are necessary, whereby experience has shown that the power density of the solid oxide fuel cell at 800 ° C. and 0.7 V is limited to a maximum of approximately 0.4 W / cm 2 . This is for automotive applications where the most compact fuel cells with high power density are required, a disadvantage.
• the object of the invention is to provide a solid oxide fuel cell with a high power density, which has a thin electrolyte layer that can be produced without high temperature stress, so that in particular metallic support structures can also be used.
• the electrolyte layer is applied to a porous primer, which also consists of electrolyte material. That is, a graded, asymmetrical structure of the electrolyte layer between the two electrodes is proposed.
• the porous primer made of electrolyte material is first applied to the anode as the electrode layer, for example.
• a thermal spraying process or a sintering process can be used, which can be carried out at a low temperature of below 1300 ° C. because the primer does not need to be tight.
• the primer can have a thickness of 1 ⁇ m to 30 ⁇ m, for example.
• the diameter of the pores of the primer should be less than 1 ⁇ m, preferably less than 300 nm.
• the actual electrolyte layer is produced according to the invention from nanoparticles, ie particles with a maximum particle size of 300 nm, preferably less than 100 nm.
• the electrode layers have a high porosity.
• the primer essentially serves to prevent the small nanoparticles from penetrating into the comparatively large pores of the electrode layer.
• the nanoparticles can be sintered at a low temperature of, for example, 1100 ° C. and below. In other words, with a corresponding sintering time, a very thin, gas-tight electrolyte layer can be produced from the nanoparticles. High solid densities above 1 W / cm 2 at 800 ° C. and 0.7 V can thus be achieved with the solid oxide fuel cell according to the invention.
• the graded structure of the electrolyte material i.e. the porous primer achieves an increase in the phase interface between the electrolyte material and the electrode material, so that more active centers are available at which electrochemical reactions can take place, which in turn leads to an increase in the power density.
• the production costs are reduced in that the electrolyte material applied as a primer is porous and therefore
• the electrolyte material can be any metal oxide which is suitable for SOFC and is an oxygen ion conductive metal oxide, for example stabilized zirconium oxide (ZrO 2 ) or doped cerium oxide. Yttrium-stabilized zirconium oxide or zirconium oxide stabilized with calcium, scandium or magnesium oxide is preferably used.
• Nanoparticle size electrolyte material is commercially available. Although the particle size of the electrolyte material can be up to 300 nm, an electrolyte material with a particle size of at most 100 nm is preferably used.
• the layer thickness of the electrolyte layer should be at most 20 ⁇ m, in particular at most 10 ⁇ m.
• the solid oxide fuel cell according to the invention preferably has a metal or a metal ceramic as the supporting structure.
• the support structure can be formed from threads, chips or other particles made of metal or metal ceramic. It can consist, for example, of a knitted fabric, a mesh, a fleece or fine woven fabric made of metal or metal-ceramic.
• a cover layer can be provided between the support structure and the electrode adjoining it, in order to be able to apply the electrode layer.
• an electrode layer (anode or cathode) is applied to the support structure, which preferably consists of metal or metal ceramic.
• the electrode layer can be driving can be used, for example, plasma spraying or flame spraying.
• the electrode layer can also be produced by a sintering process, the sintering temperature below 1300 ° C. and the sintering time below 4 h and the sintering should preferably take place in a protective gas atmosphere when using a metallic support structure.
• electrolyte material is applied to the electrode layer as a primer.
• the application of the electrolyte material to form the primer can be done by thermal spraying, e.g. Plasma or flame spraying or by applying the green material and then sintering. Since the primer need not be gas-tight, similar conditions can be used when sintering the primer, in particular a sintering temperature below 1300 ° C. as when sintering the electrode layer on the supporting structure.
• the electrode layer and the primer can also be sintered onto the support structure in a single step using a two-layer film comprising an electrode material layer and an electrolyte material layer.
• the gas-tight electrolyte layer is then formed on the primer.
• electrolyte material in the form of a powder of nanoparticles sintering at low temperature and having a particle size of at most 300 nm, in particular at most 100 nm, is applied to the primer.
• precursors of the nanoparticles can also be applied to the primer, for example salts or organometallic compounds from which the nanoparticles ⁇ __ ⁇ .c J r ⁇ -, "JJ"",,”” - in particular, so-called “sol-gel” materials have also proven to be suitable, ie organometallic polymers.
• the nanoparticles can be applied to the primer by electrophoresis, infiltration, knife coating, by pressure and / or by spraying.
• the composite of support structure, electrode layer and primer can, for example, be introduced into a chamber in which the nanoparticles or their precursor are dispersed in an electrically charged form.
• the metallic support structure can then be used as an electrode, for example as a cathode, so that when the nanoparticles or their precursors are positively charged, the particles dispersed on the side of the primer in the bath are deposited on the primer.
• the charging of the nanoparticles can e.g. via the pH value or charged surfactants.
• the nanoparticles dispersed in a liquid can be separated from the primer like a filter.
• the liquid can be pressed or sucked through with pressure into the composite of support structure, electrode layer and primer.
• the layer of the nanoparticles or their precursors can also be applied by knife coating on the primer or applied by a printing process, for example stamp or screen printing, or by spraying. Both the application process and the materials can be used in any combination. ⁇
• the applied nanoparticle layer is then sintered to form the electrolyte layer.
• the sintering can take place after the application of the nanoparticle layer.
• the second electrode layer can be applied by thermal spraying or by sintering.
• the material for the two electrodes can be applied, for example, as a film, by knife coating, by printing techniques or by spraying.
• a support structure 2 made of a knitted or woven fabric, e.g. made of steel threads.
• a porous cover layer 3 is applied to the coarse-mesh knitted fabric, on which there is a layer arrangement consisting of the anode layer 4, the primer 5, the electrolyte layer 6 and the cathode layer 7.
• the primer 5 and the electrolyte layer 6 consist, for example, of yttrium-stabilized zirconium oxide.
• the ano- a mixture of nickel metal or nickel oxide and yttrium-stabilized zirconium oxide.
• the cathode layer 7 can be formed, for example, by a Persovskite oxide, such as lanthanum strontium manganite.
• the fuel gas is supplied to the anode layer 4 via the support structure 2, while the cathode layer 7 is brought into contact with atmospheric oxygen.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Life Sciences & Earth Sciences (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)
• Inert Electrodes (AREA)

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• 2003
  • 2003-08-28 DE DE10339613A patent/DE10339613A1/de not_active Withdrawn
• 2004
  • 2004-07-15 EP EP04741994A patent/EP1658653A1/de not_active Withdrawn
  • 2004-07-15 JP JP2006524355A patent/JP2007504604A/ja not_active Withdrawn
  • 2004-07-15 WO PCT/EP2004/051501 patent/WO2005024990A1/de not_active Application Discontinuation
• 2006
  • 2006-02-28 US US11/363,319 patent/US20060172166A1/en not_active Abandoned

Non-Patent Citations (1)

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