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WO2001078174A1 - Pile a combustible a couche de diffusion - Google Patents

Pile a combustible a couche de diffusion Download PDF

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Publication number
WO2001078174A1
WO2001078174A1 PCT/DE2001/001077 DE0101077W WO0178174A1 WO 2001078174 A1 WO2001078174 A1 WO 2001078174A1 DE 0101077 W DE0101077 W DE 0101077W WO 0178174 A1 WO0178174 A1 WO 0178174A1
Authority
WO
WIPO (PCT)
Prior art keywords
diffusion layer
fuel cell
fuel
anode
methanol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DE2001/001077
Other languages
German (de)
English (en)
Inventor
Hendrik Dohle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Forschungszentrum Juelich GmbH
Original Assignee
Forschungszentrum Juelich GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Forschungszentrum Juelich GmbH filed Critical Forschungszentrum Juelich GmbH
Publication of WO2001078174A1 publication Critical patent/WO2001078174A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • 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 invention relates to a fuel cell with a diffusion layer, in which a direct electrochemical conversion of a fuel into electricity takes place, in particular a low-temperature fuel cell.
  • DMFC direct methanol fuel cell
  • Such a fuel cell has an anode compartment with an anode, an electrolyte membrane and a cathode compartment with a cathode.
  • the cathode becomes an oxidizing agent, e.g. B. air and the anode is a fuel through the anode compartment, for. B. hydrogen or methanol.
  • the cathode and anode of a fuel cell generally have a continuous porosity so that the two operating media, oxidizing agent and fuel, can be fed to the active areas of the electrodes.
  • the electrodes typically have a catalyst layer in which the actual electrochemically catalyzed processes take place.
  • the supplied fuel is depleted on the anode side, in the case of a methanol fuel cell a methanol / water mixture, during operation along the anode.
  • the following disadvantages occur.
  • the high concentration of methanol at the inlet of the anode space causes an increased permeation of the methanol through the electrolyte membrane and thus leads to the formation of a mixed potential on the cathode side. This regularly has a negative impact on fuel efficiency.
  • the low methanol concentrations at the outlet of the anode compartment can lead to diffusion overvoltages. This also has a negative impact on the efficiency of the fuel cell.
  • the object of the invention is to create a fuel cell which reduces the above-mentioned disadvantages of the varying fuel concentrations along the anode during operation and regularly achieves an improved efficiency.
  • the methanol fuel cell according to the invention comprises an anode space with an anode, a diffusion layer being arranged on the anode.
  • the diffusion layer of the fuel cell according to the invention has different diffusivities for the
  • Different diffusivity for the fuel means that the particle flow of the fuel from the free anode space through the diffusion layer to the electrode takes on different values.
  • this is achieved by a diffusion layer with different thickness. It was found within the scope of the invention that this changes the distance the fuel travels through the porous material of the diffusion layer. If the layer thickness of the porous material is increased, the path length also increases. The particle flow decreases accordingly.
  • the concentration of the fuel can be influenced directly at the anodic catalyst layer by varying the diffusivity of the diffusion layer.
  • the thickness of the diffusion layer decreases continuously from the fuel inlet side to the fuel outlet side.
  • the high initial concentrations in the free anode space at the fuel inlet are buffered or reduced by a thick diffusion layer directly at the anode.
  • the low content of fuel on the fuel outlet side is led to the anode almost unchanged by a thin diffusion layer there.
  • Such a diffusion layer regularly results in a more uniform concentration profile directly at the anode, in contrast to that in the free anode space.
  • a methanol fuel cell according to the invention is produced as a low-temperature fuel cell with a diffusion layer that has different diffusivities as follows.
  • the diffusion layer is applied to an electrical conductor that is in the form of a graphite fabric.
  • a mixture of 15% PTFE and 85% activated carbon (eg XC 72) is weighed out, mixed, diluted with a water / isopropanol mixture and thus produced a sprayable form.
  • the sprayable mixture is then sprayed onto the current conductor, the coverage usually varying from approximately 4 to 12 mg / cm 2 .
  • This diffusion layer for a methanol fuel cell comprises porous material and is permeable to methanol, water and CO 2 .
  • the fuel reaches the anode from the free anode space through the diffusion layer, where it can react on the catalyst layer.
  • the resulting reaction products, water and CO 2 can diffuse back into the anode compartment through the diffusion layer.
  • a suitable diffusion layer typically comprises PTFE and activated carbon, where the PTFE can be present in the form of fine-grain powder or as a suspension when the diffusion layer is produced.
  • a different diffusivity in the diffusion layer alternatively results from different porosities or also from different compositions within the diffusion layer. The proportion of PTFE in the mixture has a significant influence on the diffusivity of the diffusion layer.

Landscapes

  • 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)
  • Inert Electrodes (AREA)
  • Fuel Cell (AREA)

Abstract

Pile à combustible dont la couche de diffusion utilisée pour la distribution du carburant à la couche de catalyseur anodique présente différentes diffusivités obtenues, de façon avantageuse, par diminution de l'épaisseur de ladite couche dans le sens de l'écoulement du combustible. La couche de diffusion selon l'invention permet l'obtention d'un profil de concentration de combustible régulier, plus uniforme, directement sur l'anode, contrairement à celui obtenu dans la chambre d'anode libre. La couche de diffusion peut être utilisée de façon avantageuse dans une pile à combustible au méthanol.
PCT/DE2001/001077 2000-04-05 2001-03-17 Pile a combustible a couche de diffusion Ceased WO2001078174A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10016820A DE10016820A1 (de) 2000-04-05 2000-04-05 Brennstoffzelle mit Diffusionsschicht
DE10016820.5 2000-04-05

Publications (1)

Publication Number Publication Date
WO2001078174A1 true WO2001078174A1 (fr) 2001-10-18

Family

ID=7637610

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2001/001077 Ceased WO2001078174A1 (fr) 2000-04-05 2001-03-17 Pile a combustible a couche de diffusion

Country Status (2)

Country Link
DE (1) DE10016820A1 (fr)
WO (1) WO2001078174A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60189868A (ja) * 1984-03-12 1985-09-27 Fuji Electric Corp Res & Dev Ltd 燃料電池
WO1996035003A1 (fr) * 1995-05-01 1996-11-07 E.I. Du Pont De Nemours And Company Element electrochimique a couche autoregulatrice de diffusion gazeuse
US5840438A (en) * 1995-08-25 1998-11-24 Ballard Power Systems Inc. Electrochemical fuel cell with an electrode substrate having an in-plane nonuniform structure for control of reactant and product transport
DE19838814A1 (de) * 1997-08-28 1999-03-04 Fuji Electric Co Ltd Brennstoffzelle mit einem festen Polymer-Elektrolyten

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60189868A (ja) * 1984-03-12 1985-09-27 Fuji Electric Corp Res & Dev Ltd 燃料電池
WO1996035003A1 (fr) * 1995-05-01 1996-11-07 E.I. Du Pont De Nemours And Company Element electrochimique a couche autoregulatrice de diffusion gazeuse
US5840438A (en) * 1995-08-25 1998-11-24 Ballard Power Systems Inc. Electrochemical fuel cell with an electrode substrate having an in-plane nonuniform structure for control of reactant and product transport
DE19838814A1 (de) * 1997-08-28 1999-03-04 Fuji Electric Co Ltd Brennstoffzelle mit einem festen Polymer-Elektrolyten

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 010, no. 032 (E - 379) 7 February 1986 (1986-02-07) *

Also Published As

Publication number Publication date
DE10016820A1 (de) 2001-10-18

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