WO1993003506A1 - Electrodes pour cellule electrochimique alcaline a courant fort - Google Patents
Electrodes pour cellule electrochimique alcaline a courant fort Download PDFInfo
- Publication number
- WO1993003506A1 WO1993003506A1 PCT/US1991/005320 US9105320W WO9303506A1 WO 1993003506 A1 WO1993003506 A1 WO 1993003506A1 US 9105320 W US9105320 W US 9105320W WO 9303506 A1 WO9303506 A1 WO 9303506A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- particles
- catalyst
- electrode
- catalyst layer
- anode
- Prior art date
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 31
- 239000003054 catalyst Substances 0.000 claims abstract description 161
- 239000002245 particle Substances 0.000 claims abstract description 132
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 34
- 239000003792 electrolyte Substances 0.000 claims abstract description 32
- 239000000758 substrate Substances 0.000 claims abstract description 29
- 230000037361 pathway Effects 0.000 claims abstract description 22
- 239000007788 liquid Substances 0.000 claims abstract description 21
- 239000011230 binding agent Substances 0.000 claims abstract description 19
- 238000003487 electrochemical reaction Methods 0.000 claims abstract description 13
- 238000005086 pumping Methods 0.000 claims abstract description 11
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 29
- 239000007789 gas Substances 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 17
- 239000010931 gold Substances 0.000 claims description 16
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 15
- 239000006185 dispersion Substances 0.000 claims description 14
- 229910052737 gold Inorganic materials 0.000 claims description 14
- 230000001737 promoting effect Effects 0.000 claims description 13
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 12
- 229910045601 alloy Inorganic materials 0.000 claims description 11
- 239000000956 alloy Substances 0.000 claims description 11
- 229910052697 platinum Inorganic materials 0.000 claims description 11
- 239000000725 suspension Substances 0.000 claims description 11
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 10
- 229920001600 hydrophobic polymer Polymers 0.000 claims description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 9
- 239000001257 hydrogen Substances 0.000 claims description 9
- 229910052739 hydrogen Inorganic materials 0.000 claims description 9
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 9
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 229910052741 iridium Inorganic materials 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 239000010948 rhodium Substances 0.000 claims description 8
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 8
- 229910052703 rhodium Inorganic materials 0.000 claims description 7
- 239000004332 silver Substances 0.000 claims description 7
- 229910001260 Pt alloy Inorganic materials 0.000 claims description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 6
- 230000010287 polarization Effects 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 238000009792 diffusion process Methods 0.000 claims description 5
- 238000006056 electrooxidation reaction Methods 0.000 claims description 5
- 239000011159 matrix material Substances 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 230000009467 reduction Effects 0.000 claims description 5
- 239000006229 carbon black Substances 0.000 claims description 4
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 claims description 4
- 230000005611 electricity Effects 0.000 claims description 4
- JUWSSMXCCAMYGX-UHFFFAOYSA-N gold platinum Chemical compound [Pt].[Au] JUWSSMXCCAMYGX-UHFFFAOYSA-N 0.000 claims description 4
- 230000001590 oxidative effect Effects 0.000 claims description 4
- 229910000575 Ir alloy Inorganic materials 0.000 claims description 3
- 230000003311 flocculating effect Effects 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 238000005245 sintering Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 229910000480 nickel oxide Inorganic materials 0.000 claims description 2
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 2
- 229910001316 Ag alloy Inorganic materials 0.000 claims 1
- 229910001020 Au alloy Inorganic materials 0.000 claims 1
- 229910000629 Rh alloy Inorganic materials 0.000 claims 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 16
- 239000004810 polytetrafluoroethylene Substances 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- -1 polytetrafluoroethylene Polymers 0.000 description 6
- 239000000376 reactant Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000012153 distilled water Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910001414 potassium ion Inorganic materials 0.000 description 2
- 229910000566 Platinum-iridium alloy Inorganic materials 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- QXZUUHYBWMWJHK-UHFFFAOYSA-N [Co].[Ni] Chemical compound [Co].[Ni] QXZUUHYBWMWJHK-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 239000012777 electrically insulating material Substances 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 229920002313 fluoropolymer Polymers 0.000 description 1
- 239000004811 fluoropolymer Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 230000005660 hydrophilic surface Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- HWLDNSXPUQTBOD-UHFFFAOYSA-N platinum-iridium alloy Chemical class [Ir].[Pt] HWLDNSXPUQTBOD-UHFFFAOYSA-N 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 229910052566 spinel group Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
Classifications
-
- 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
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
-
- 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
-
- 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
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
-
- 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
- H01M4/96—Carbon-based electrodes
-
- 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
- H01M8/08—Fuel cells with aqueous electrolytes
- H01M8/083—Alkaline fuel cells
-
- 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
- H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
- H01M2004/8684—Negative electrodes
-
- 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
- H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
- H01M2004/8689—Positive electrodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0002—Aqueous electrolytes
- H01M2300/0014—Alkaline electrolytes
-
- 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
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/921—Alloys or mixtures with metallic elements
-
- 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 present invention pertains to fuel cell electrodes, and particularly to electrodes for fuel cells having an alkaline electrolyte.
- a fuel cell is a device for converting chemical energy into electricity.
- An alkaline fuel cell comprises an anode, a cathode and an alkaline
- hydroxide is typically used as the alkaline
- the anode and cathode each comprise a porous substrate and a porous catalyst layer supported on the substrate.
- a hydrogen containing gas is fed to the anode and an oxygen containing gas is fed to the cathode.
- the reactant gases diffuse through the electrodes to react with the electrolyte in the presence of the catalysts to produce water, heat and electricity.
- the hydrogen is electrochemically oxidized and gives up electrons according to the reaction:
- the electrons so generated are conducted from the anode through an external circuit to the cathode.
- electrons are electrochemically combined with the oxidant according to the reaction:
- a flow of ions through the electrolyte completes the electrical circuit.
- the catalyst layer comprises a polymeric hydrophobic phase and a wettable catalyst phase. Particles of catalyst form a network of electrolyte-filled channels through the catalyst layer.
- the porous hydrophobic phase binds the electrode together and provides a network of channels through which reactant gases gain access to the catalytic surfaces and through which gaseous reaction products escape from the catalyst layer.
- water-producing electrode i.e. the anode of an alkaline electrolyte fuel cell.
- plating refers to bulk movement of electrolyte from one side of a fuel cell to the other due to the electromigration of nonelectroactive ions.
- electromigration For example, in an alkaline fuel cell having a KOH electrolyte nonelectroactive potassium ions migrate toward the cathode.
- pressure may be built up that is sufficient to force electrolyte out of the gas side of the cathode. Accumulation of electrolyte on the gas side of the electrode restricts the supply of reactant gas to the catalyst layer of the electrode and may lead to severe concentration polarization of the electrode.
- the conventional approach to the problem of flooding has been to make the catalyst layer of the electrode more hydrophobic.
- the catalyst layer can be made more hydrophobic by increasing the amount of hydrophobic binder in the layer or by increasing the temperature or process time during sintering of the electrode.
- the pumping phenomenon has been addressed by applying a thin layer of a porous hydrophobic polymer to the gas side of the electrode.
- What is needed in the art is a way to provide electrodes that are resistant to flooding and pumping and to thereby provide an alkaline fuel cell that may be operated continuously at high current density.
- a gas diffusion electrode for conducting an electrochemical reaction in an alkaline fuel cell comprises a porous substrate and a catalyst layer supported on the substrate.
- the catalyst layer comprises a catalytically effective amount of catalyst particles for promoting the
- a porous hydrophobic binder for providing a network of hydrophobic gas pathways communicating with the catalyst particles and
- hydrophilic particles in an amount effective to provide a network of liquid transport pathways throughout the catalyst layer.
- the hydrophilic particles are not active in promoting the
- a method for making a gas diffusion electrode comprises preparing an aqueous dispersion of catalyst particles and
- hydrophobic polymer particles flocculating the dispersion to form a flocculent suspension, mixing hydrophilic particles with the flocculent suspension to form a mixture, filtering the mixture to form a catalyst layer, disposing the catalyst layer on a porous substrate and sintering the catalyst layer to form the electrode.
- Figure 1 shows a schematic cross section of an alkaline fuel cell
- Figure 2 shows a schematic diagram of a portion of a catalyst layer of a conventional electrode
- Figure 3 shows a schematic diagram of a portion of a catalyst layer of an electrode of the present invention.
- the fuel cell includes an anode 1, a cathode 2, an electrolyte-filled matrix 3 between the anode 1 and the cathode 2, an anode gas flow field 4 and a cathode gas flow field 5.
- the anode 1 comprises a substrate 6 and a catalyst layer 7.
- the cathode 2 comprises a substrate 8 and a catalyst layer 9.
- the catalyst layers 7 and 9 are each oriented toward the matrix 3.
- the matrix 3 is a thin porous sheet of an electrically insulating material which holds the alkaline electrolyte within its pores by capillary forces.
- the anode 1 and cathode 2 are electrically connected by an external circuit (not shown). Gas flow passages 10 and 11 distribute reactant gases over the electrodes.
- the electrodes of the present invention each include an electrically conductive porous substrate.
- the porous substrate may be any substrate
- the porous substrate may comprise gold screen, gold plated perforated metal foil, porous sintered nickel, carbon paper or graphite paper.
- the porous substrate of the electrode of the present invention comprises a gold plated
- the electrodes of the present invention each include a catalyst layer supported on the porous substrate.
- the catalyst layer includes a hydrophobic binder, catalyst particles, and hydrophilic particles.
- the hydrophobic binder may comprise any one of
- the hydrophobic binder of the present invention comprises a fluoropolymer.
- the hydrophobic binder comprises polytetrafluoroethylene (PTFE).
- the catalyst layer may comprise between about 10 weight percent and about 50 weight percent of hydrophobic binder.
- the catalyst layer comprises about 20 weight percent hydrophobic binder.
- the catalyst layer of the anode of the present invention includes the particles that catalyze the electrochemical oxidation of hydrogen in an alkaline electrolyte.
- the catalyst particles of the anode catalyst layer may comprise any material
- the catalyst conventionally used as a catalyst in the anode of an alkaline fuel cell.
- the catalyst is conventionally used as a catalyst in the anode of an alkaline fuel cell.
- the catalyst is conventionally used as a catalyst in the anode of an alkaline fuel cell.
- the catalyst is conventionally used as a catalyst in the anode of an alkaline fuel cell.
- the catalyst is conventionally used as a catalyst in the anode of an alkaline fuel cell.
- the catalyst is conventionally used as a catalyst in the anode of an alkaline fuel cell.
- particles of the anode catalyst layer may comprise platinum, palladium, rhodium, iridium and mixtures or alloys thereof, either as metal blacks or supported on a chemically inert support.
- the catalyst particles of the anode catalyst layer comprise
- platinum black or a mixture of platinum black and palladium black.
- the anode catalyst particles have a mean specific surface area between about 5 m 2 /g and 200 m 2 /g.
- the anode catalyst particles are metal blacks having a surface area between
- the anode catalyst layer may comprise between 25 weight percent and 90 weight percent catalyst particles.
- the catalyst layer of the anode comprises between 50 weight percent and 70 weight percent catalyst particles.
- the catalyst layer of the cathode of the present invention includes particles that catalyze the
- the catalyst particles of the cathode catalyst layer may be particles of any material conventionally used as a catalyst in the cathode of an alkaline fuel cell.
- the catalyst may be particles of any material conventionally used as a catalyst in the cathode of an alkaline fuel cell.
- the particles of the catalyst layer may comprise platinum, gold, silver, iridium, rhodium and mixtures or alloys thereof, as metal blacks or supported on an inert support.
- the cathode catalyst particles have a mean specific surface area between about
- the cathode catalyst particles are metal blacks and have a surface area between about 10 m 2 /g and about 40 m 2 /g.
- the cathode catalyst particles comprise a platinum-iridium alloy black comprising 90 weight percent platinum and 10 weight percent iridium.
- the cathode catalyst layer may comprise between 25 weight percent and about 90 weight percent catalyst
- the catalyst layer of the cathode comprises between about 50 weight percent and about 70 weight percent catalyst particles.
- the catalyst layer of the electrode of the present invention comprises between about 2.5 weight percent and about 45 weight percent hydrophilic particles.
- the hydrophilic particles of the anode of the present invention may be any particles that have a hydrophilic, i.e. wettable by water, surface and that are stable in an alkaline electrolyte under the operating conditions of the anode.
- Suitable hydrophilic particles include, e.g.
- the hydrophilic particles of the anode catalyst layer comprise carbon black or a gold-platinum alloy black.
- the hydrophilic particles of the anode catalyst layer comprise a gold-platinum alloy black comprising about 90 weight percent gold and about 10 weight percent platinum.
- the hydrophilic particles of the cathode catalyst layer may comprise any particles that have hydrophilic surfaces and that are stable in an alkaline
- Suitable hydrophilic particles include, e.g. certain ceramic materials, spinels, (e.g.
- the hydrophilic particles of a particular cathode catalyst layer of the present invention comprise the same material as the catalyst particles of the particular cathode catalyst layer.
- a schematic diagram of a portion of the catalyst layer 12 of a conventional electrode is shown in
- the layer 12 includes catalyst particles 13 and a hydrophobic binder 14 which provides a network of gas pathways communicating with the catalyst particles 13.
- FIG. 3 A schematic diagram of a portion of a catalyst layer 15 of an electrode of the present invention is shown in Figure 3.
- the layer 15 includes catalyst particles 16 associated with a porous hydrophobic binder 17 which provides a network of hydrophobic gas pathways communicating with the catalyst particles 16.
- Hydrophilic particles 18 are distributed throughout the layer 15 to form an interpenetrating network of liquid transport pathways throughout the catalyst layer 15.
- the surfaces of the catalyst particles of the electrode of the present invention are associated with the
- hydrophobic polymeric binder to control the
- this is accomplished by flocculating a dispersion of the hydrophobic polymer and catalyst particles.
- hydrophilic particles of the present invention are incorporated into the catalyst layer in a manner which maintains the wettability of the surfaces of the hydrophilic particles.
- the process of the present invention is one method of providing an electrode having the desired composition and structure.
- catalyst particles and hydrophobic polymer particles are dispersed in water and the dispersion is caused to flocculate to form a
- hydrophilic particles are stirred rapidly into the flocculent aqueous suspension and the mixture so formed is immediately filtered to form a catalyst layer.
- the catalyst layer is transferred to a suitable porous substrate.
- the catalyst layer and substrate are dried and sintered to form the electrode.
- a small amount e.g. from about 5 to about 10 weight percent based on the combined weight of added hydrophobic polymer and hydrophilic particles, of polymer i.e. binder, may be added to the flocculent suspension along with the hydrophilic particles to more securely bind the hydrophilic particles into the catalyst layer without rendering the surfaces of the hydrophilic particles hydrophobic.
- hydrophilic particles of the present invention are present.
- hydrophilic particles form a network of liquid
- the hydrophilic particles are substantially inactive in the electrochemical reaction occurring at the electrode, even in embodiments of the present invention wherein the hydrophilic particles comprise a material that is catalytically active in the reaction occurring at an electrode that includes the
- the hydrophilic particles of the electrode of the present invention provide a network of wettable surfaces throughout the catalyst layer. Since the hydrophilic particles of the electrode are not active in promoting the electrochemical reaction occurring at the surfaces of the catalyst particles of the
- the hydrophilic particles make no substantial contribution to water generation at the anode or to hydroxyl ion generation at the cathode, the network of wettable surfaces provided by the hydrophilic particles functions primarily as a passive network of liquid transport pathways.
- An anode (Al) according to the present invention was fabricated according to the method of the present invention.
- a catalyst suspension was formed by ultrasonically codispersing 1.92g platinum black (fuel cell grade from Englehard Corp.) and 0.22g palladium black (Johnson Matthey Inc.) in distilled water.
- a hydrophobic polymer 0.715g polytetrafluoroethylene was added to the catalyst suspension in the form of a diluted aqueous dispersion of TFE-3170 (DuPont). The catalyst/PTFE mixture so formed was blended
- a conventional anode (A2) was fabricated by a process analogous to the process of the present invention, except that the step of adding hydrophilic particles to the flocculated catalyst particle/PTFE suspension was omitted.
- Catalyst particles (1.92g platinum black and 0.22g palladium black) were
- the electrode was transferred onto a 100 mesh gold plated nickel screen to form an electrode.
- the electrode was sintered at 590°F for 5 minutes.
- Anodes A1 and A2 were operated for over 2 hours at 200 ps ⁇ a,and 3500 amp/ft 2 in identical H 2 /O 2 fuel cells, using 40 weight percent KOH as the electrolyte.
- the cells were disassembled and the polarizations and limiting currents of the anodes were determined in a half cell apparatus as a function of current density.
- the values obtained and comparable results obtained from testing unused portions of the same electrodes are given in Table 1.
- the anode (Al) of the present invention exhibited no increase in polarization following operation in the fuel cell whereas the conventional anode (A2)
- the limiting current of the anode of the present invention was substantially unchanged, while the post test limiting current of the conventional electrode was substantially lower than its pretest limiting current. The results indicate that the anode of the present invention offers improved resistance to flooding.
- a cathode (Cl) of the present invention was fabricated according to the method of the present invention.
- Catalyst particles (2.80g of 90:10/Pt:Ir alloy black) were dispersed ultrasonically in 75 ml
- a hydrophobic polymer (0.70g PTFE in the form of a diluted aqueous dispersion of TFE-30 (DuPont) was added to the catalyst dispersion and blended ultrasonically. Aluminum ions were added and the pH of the catalyst/PTFE dispersion was adjusted to flocculate the catalyst/PTFE dispersion. Hydrophilic particles (0.65g of 90:l ⁇ /Pt:Ir alloy black) were rapidly stirred into the flocculated catalyst/PTFE suspension. The catalyst particle/PTFE/hydrophilic particle mixture was vacuum filtered and the damp filter cake was press transferred on to a 0.003 inch thick, gold-plated, perforated nickel foil to form an electrode having an active area of 131 cm. The electrode was vacuum dried, heated to volatilize the surfactant introduced with the TFE-30 dispersion and then sintered at 610"F for 10 minutes.
- a conventional cathode (C2) was fabricated by a conventional process analogous to the process of the present invention, except that the step of adding the hydrophilic particles to the flocculated catalyst particle/PTFE suspension was omitted.
- Cathodes Cl and C2 were operated in identical H 2 /O 2 fuel cells at 200 psia and 250°F using 40 weight percent KOH as the electrolyte.
- Each of the cells included anodes of the present invention as described in Example 1, i.e. identical to electrode Al. The results of the testing are given in TABLE II.
- the cell including the cathode (C1) of the present invention exhibited higher performance and substantially improved stability compared to the cell including the conventional cathode (C2).
- Electrodes are able to transport liquids.
- Flooding occurs when the rate at which water is generated in the anode reaction exceeds the rate at which the water can be transported away from the catalytic surfaces of the anode catalyst layer.
- hydrophilic particles of the particles of the electrode of the present invention provide
- catalytically inactive conduits for liquid transport through the catalyst layer Improving the ability of the fuel cell electrode to transport liquid directly addresses the causes of the flooding and pumping problems experienced with conventional electrodes and results in substantial improvement in electrode performance.
- Anodes of the present invention are resistant to flooding, even when operated at high current densities.
- Cathodes of the present invention are resistant to pumping, even when operated at high current densities.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Inert Electrodes (AREA)
Abstract
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP91919623A EP0600882A1 (fr) | 1991-07-26 | 1991-07-26 | Electrodes pour cellule electrochimique alcaline a courant fort |
| PCT/US1991/005320 WO1993003506A1 (fr) | 1991-07-26 | 1991-07-26 | Electrodes pour cellule electrochimique alcaline a courant fort |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1991/005320 WO1993003506A1 (fr) | 1991-07-26 | 1991-07-26 | Electrodes pour cellule electrochimique alcaline a courant fort |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1993003506A1 true WO1993003506A1 (fr) | 1993-02-18 |
Family
ID=22225695
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1991/005320 WO1993003506A1 (fr) | 1991-07-26 | 1991-07-26 | Electrodes pour cellule electrochimique alcaline a courant fort |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0600882A1 (fr) |
| WO (1) | WO1993003506A1 (fr) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1519433A1 (fr) * | 2003-09-26 | 2005-03-30 | Samsung SDI Co., Ltd. | Electrode à diffusion pour pile à combustible |
| FR2892233A1 (fr) * | 2005-10-19 | 2007-04-20 | Commissariat Energie Atomique | Electrode pour pile a combustible alcaline et procede de fabrication d'une pile a combustible alcaline comportant au moins une etape de fabrication d'une telle electrode. |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3386859A (en) * | 1964-11-04 | 1968-06-04 | Union Oil Co | Porous electrode comprising hydrophobic binder and hydrophilic material incorporated therein and method of fabricating same |
| GB1209249A (en) * | 1967-12-27 | 1970-10-21 | United Aircraft Corp | Anode for alkaline electrolyte fuel cell |
| EP0110491A2 (fr) * | 1982-08-27 | 1984-06-13 | Westinghouse Electric Corporation | Electrodes à diffusion gazeuse multi-couches présentant une gradation en poids et en taille |
-
1991
- 1991-07-26 WO PCT/US1991/005320 patent/WO1993003506A1/fr not_active Application Discontinuation
- 1991-07-26 EP EP91919623A patent/EP0600882A1/fr not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3386859A (en) * | 1964-11-04 | 1968-06-04 | Union Oil Co | Porous electrode comprising hydrophobic binder and hydrophilic material incorporated therein and method of fabricating same |
| GB1209249A (en) * | 1967-12-27 | 1970-10-21 | United Aircraft Corp | Anode for alkaline electrolyte fuel cell |
| EP0110491A2 (fr) * | 1982-08-27 | 1984-06-13 | Westinghouse Electric Corporation | Electrodes à diffusion gazeuse multi-couches présentant une gradation en poids et en taille |
Non-Patent Citations (2)
| Title |
|---|
| CHEMICAL ABSTRACTS, vol. 102, no. 14, 1984, Columbus, Ohio, US; abstract no. 116629R, MAOKA, TADANORI: 'Gas-diffusion Electrodes' * |
| PATENT ABSTRACTS OF JAPAN vol. 12, no. 101 (E-595)(2948) 2 April 1988 & JP,A,62 232 858 ( TANAKA KIKINZOKU KOGYO K.K. ) 13 October 1987 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1519433A1 (fr) * | 2003-09-26 | 2005-03-30 | Samsung SDI Co., Ltd. | Electrode à diffusion pour pile à combustible |
| FR2892233A1 (fr) * | 2005-10-19 | 2007-04-20 | Commissariat Energie Atomique | Electrode pour pile a combustible alcaline et procede de fabrication d'une pile a combustible alcaline comportant au moins une etape de fabrication d'une telle electrode. |
| WO2007045763A1 (fr) * | 2005-10-19 | 2007-04-26 | Commissariat A L'energie Atomique | Electrode pour pile a combustible alcaline et procede de fabrication d'une pile e combustible comportant au moins une etape de fabrication d'une telle electrode |
| US8017283B2 (en) | 2005-10-19 | 2011-09-13 | Commissariat A L'energie Atomique | Electrode for alkali fuel cell and method for making a fuel cell including at least one step of making such an electrode |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0600882A1 (fr) | 1994-06-15 |
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