CA2288678C - Production of electrolyte units by electrolytic deposition of a catalyst - Google Patents
Production of electrolyte units by electrolytic deposition of a catalyst Download PDFInfo
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- CA2288678C CA2288678C CA002288678A CA2288678A CA2288678C CA 2288678 C CA2288678 C CA 2288678C CA 002288678 A CA002288678 A CA 002288678A CA 2288678 A CA2288678 A CA 2288678A CA 2288678 C CA2288678 C CA 2288678C
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- 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]
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
- C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
- C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
-
- 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
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0082—Organic polymers
-
- 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
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Manufacturing & Machinery (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- General Chemical & Material Sciences (AREA)
- Inert Electrodes (AREA)
- Fuel Cell (AREA)
- Catalysts (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention relates to a method for producing an electrolyte unit with a catalytically active coating. Dissolved metal salt (2) is placed in the form of a coating between an electrolyte coating (1) and an electrode (3) and metal is electrochemically separated from the metal salt. One advantage of the invention is that no expensive electroplating baths are required for production. The catalytically active metal is deposited in targeted manner on the three phase zone, thereby minimizing the use of expensive precious metals. The electrolyte unit can, for example, be used in fuel cells.
Description
PRODUCTION OF ELECTROLYTE UNITS BY ELECTROLYTIC DEPOSITION
OF A CATALYST
The invention relates to a method of producing an electrode-electrolyte unit with a catalytically active layer.
Electrochemically operating units consisting of electrode-electrolyte-electrode are provided for example for use in fuel cells, electrolysis cells, or cells for electro-organic syntheses. The electrodes are preferably porous throughout so that operating means such as air and hydrogen can pass through the electrodes. In many cases, the electrodes participating in the electrochemical reactions must be activated by suitable catalysts.
For fuel cells whose operating temperatures are 0 -150 C, ion conductive solid electrolyte membranes are used. The anodes for the hydrogen oxidation and the cathodes for the oxygen reduction are coated mostly with platinum, recently also with a platinum-ruthenium alloy.
The principle of such a membrane fuel cell is known from the book by K. Kordesch, Gunter Simadar entitled "FUEL CELLS AND
THEIR APPLICATIONS", published by VCH Weinheim in 1996. In this book furthermore various methods for producing membrane-electrode units for fuel cells are described. For example, the electrode can be activated by sputtering a thin platinum layer onto the diffusion layer of the gas diffusion electrode. Additional manufacturing methods are described in the German patent document DE 196 38 928 Al published on April 2, 1990. The manufacture of gas diffusion electrodes by way of a spray process is disclosed in the printed publication EP 0 687 024 Al.
The main disadvantages of the known electrode-electrolyte units with electrochemically active areas are the high costs. The high price results essentially from expensive membranes consisting for example of *Nafion and from expensive catalysts consisting for example of platinum.
To avoid the high prices, it is being tried therefore to deposit thin catalytically active layers in electrochemically active areas. The electrochemical processes in a fuel cell occur immediately at the contact area between the gas diffusion electrode and the nafion membrane. The catalyst is therefore preferably located at these contact areas, in other words, at the three-phase zone consisting of a gas distributor with electronic current conductance, the place of the electrochemical reaction and the electrolytes (in this case: nafion membrane).
The printed publication US 5 084 144 and the printed publication, E.J. Taylor, E.B. Anderson, NR K.
Vilambi, Journal of the Electrochemical Society, Vol. 139 (1992) L 45-46" discloses a method for the manufacture of gas diffusion electrodes with the object to achieve a high platinum utilization for membrane fuel cells. In accordance with that method, among others, a catalyst metal is electrolytically deposited from a galvanic bath to form a thin catalytically active layer.
The disadvantage of the method disclosed in US 5 084 144, is that it requires expensive liquid galvanic baths which must be reconditioned in a complicated and expensive manner. Furthermore, the utilization of the precious metal dissolved in the galvanic bath is very limited so that the advantages obtained by the optimized deposition are offset for example by rinsing procedures.
*Trade-mark It is the object of the present invention to provide a cost effective manufacturing method for an electrode-electrolyte unit.
According to the invention, there is provided a method for the manufacture of an electrode-electrolyte unit with a catalytically active layer, comprising the steps of placing a solution including a dissolved metal salt as a layer between an electrolyte layer and an electrode and precipitating metal electrochemically, in situ, from the metal salt on said electrode, whereby all of the metal salt is used in the precipitation of the metal from the metal salt for forming said catalytically active layer.
With the method according to the invention dissolved metal salt is first sandwiched between an electrolyte and an electrode. In this way, the dissolved metal salt forms an intermediate layer in a multi-layer (layer-) system. Subsequently, the metal is electrochemically removed from the intermediate layer that is from the dissolved metal salt.
Salts of a metal of the VIII group or of an I-B
metal of the periodic system may be provided as metal salts from which catalytically active metal can be extracted.
If, for example, platinum is to be deposited as the catalytically active metal, a suitable salt is for example H2PtCl6 or Pt (NH3) 4C12. Such a salt is then mixed with a solvent.
As solvents, for example, acids such as HCl, H2SO4r HC104 are suitable.
OF A CATALYST
The invention relates to a method of producing an electrode-electrolyte unit with a catalytically active layer.
Electrochemically operating units consisting of electrode-electrolyte-electrode are provided for example for use in fuel cells, electrolysis cells, or cells for electro-organic syntheses. The electrodes are preferably porous throughout so that operating means such as air and hydrogen can pass through the electrodes. In many cases, the electrodes participating in the electrochemical reactions must be activated by suitable catalysts.
For fuel cells whose operating temperatures are 0 -150 C, ion conductive solid electrolyte membranes are used. The anodes for the hydrogen oxidation and the cathodes for the oxygen reduction are coated mostly with platinum, recently also with a platinum-ruthenium alloy.
The principle of such a membrane fuel cell is known from the book by K. Kordesch, Gunter Simadar entitled "FUEL CELLS AND
THEIR APPLICATIONS", published by VCH Weinheim in 1996. In this book furthermore various methods for producing membrane-electrode units for fuel cells are described. For example, the electrode can be activated by sputtering a thin platinum layer onto the diffusion layer of the gas diffusion electrode. Additional manufacturing methods are described in the German patent document DE 196 38 928 Al published on April 2, 1990. The manufacture of gas diffusion electrodes by way of a spray process is disclosed in the printed publication EP 0 687 024 Al.
The main disadvantages of the known electrode-electrolyte units with electrochemically active areas are the high costs. The high price results essentially from expensive membranes consisting for example of *Nafion and from expensive catalysts consisting for example of platinum.
To avoid the high prices, it is being tried therefore to deposit thin catalytically active layers in electrochemically active areas. The electrochemical processes in a fuel cell occur immediately at the contact area between the gas diffusion electrode and the nafion membrane. The catalyst is therefore preferably located at these contact areas, in other words, at the three-phase zone consisting of a gas distributor with electronic current conductance, the place of the electrochemical reaction and the electrolytes (in this case: nafion membrane).
The printed publication US 5 084 144 and the printed publication, E.J. Taylor, E.B. Anderson, NR K.
Vilambi, Journal of the Electrochemical Society, Vol. 139 (1992) L 45-46" discloses a method for the manufacture of gas diffusion electrodes with the object to achieve a high platinum utilization for membrane fuel cells. In accordance with that method, among others, a catalyst metal is electrolytically deposited from a galvanic bath to form a thin catalytically active layer.
The disadvantage of the method disclosed in US 5 084 144, is that it requires expensive liquid galvanic baths which must be reconditioned in a complicated and expensive manner. Furthermore, the utilization of the precious metal dissolved in the galvanic bath is very limited so that the advantages obtained by the optimized deposition are offset for example by rinsing procedures.
*Trade-mark It is the object of the present invention to provide a cost effective manufacturing method for an electrode-electrolyte unit.
According to the invention, there is provided a method for the manufacture of an electrode-electrolyte unit with a catalytically active layer, comprising the steps of placing a solution including a dissolved metal salt as a layer between an electrolyte layer and an electrode and precipitating metal electrochemically, in situ, from the metal salt on said electrode, whereby all of the metal salt is used in the precipitation of the metal from the metal salt for forming said catalytically active layer.
With the method according to the invention dissolved metal salt is first sandwiched between an electrolyte and an electrode. In this way, the dissolved metal salt forms an intermediate layer in a multi-layer (layer-) system. Subsequently, the metal is electrochemically removed from the intermediate layer that is from the dissolved metal salt.
Salts of a metal of the VIII group or of an I-B
metal of the periodic system may be provided as metal salts from which catalytically active metal can be extracted.
If, for example, platinum is to be deposited as the catalytically active metal, a suitable salt is for example H2PtCl6 or Pt (NH3) 4C12. Such a salt is then mixed with a solvent.
As solvents, for example, acids such as HCl, H2SO4r HC104 are suitable.
First, the metal salt solution may be applied as a layer on the electrolyte layer of the electrode by spraying, brush coating, screen printing, etc... Then the electrode, or respectively, the electrolyte layer is disposed onto the solution layer. In this way, a layer system is provided which consists of an electrode, a metal salt solution and an electrolyte.
The layer thickness that is the amount of metal salt deposited between the electrolyte and the electrode is for example so selected that up to 0.01-1 mg metal per cm2 can be deposited from the intermediate layer. In order to generate the electric current required for the deposition, for example, a second electrode which is also disposed adjacent the electrolyte layer may be provided as an additional current conductor. The electrolyte layer is then disposed between two electrodes.
In the method according to the invention, no liquid electrolyte is needed for the electrochemical deposition. Consequently, expensive liquid galvanic baths are eliminated. The 3a complicated and expensive reconditioning and decontamination of such galvanic baths is also eliminated. Only a thin layer of the solution is applied. The consumption of expensive metals such as platinum, ruthenium, rhodium or palladium is conse-quently minimized.
The catalytically active metal is deposited directly at the three-phase zone. The catalyst material is therefore ap-plied to the electrochemically active area related to the pre-determined utilization in a controlled manner.
As a result, the membrane with the catalyst deposited thereon can be manufactured comparatively inexpensively.
If electrodes together with the intermediate layer con-sisting of the metal salt solution are disposed at both sides of the electrolyte layer, this electrode-electrolyte compound structure can be used directly in a fuel cell.
For the manufacture of an alloy, in an advantageous em-bodiment of the method, the solution includes several metal salts, which are electrochemically deposited together. In this way, an alloy of two or more metals or mixtures of metals and metal oxides, that is, an alloy catalyst, is deposited. In particular, ruthenium and platinum containing salts are consid-ered.
With respect to the known state of the art, this embodi-ment of the method according to the invention has the advantage that alloy catalysts can be optimally deposited and produced at the same time.
In another advantageous embodiment of the invention, the solution contains an ion conductive polymer in a dissolved or liquid state.
After completion of the process, an ion conductive polymer in the solution should be firmly connected to the membrane (electrolyte layer), that is it should be part of the membrane.
A polymer suitable to achieve this object is to be selected.
If for example, a solid electrolyte consisting of nafion is used, preferably dissolved nafion is used as ion conductive polymer in the solution.
The ion-conductive polymer causes an increase of the three-phase zone and, consequently improves the utilization of the catalyst material.
With the above-mentioned embodiment of the invention, catalytically active material is embedded in the solid material electrolyte and is advantageously mechanically firmly connected therewith.
The method facilitates the manufacture of an electrochemi-cally active catalyst layer on a suitable carrier, which cata-lyst layer is suitable as a gas diffusion electrode for elec-trochemical applications such as in fuel cells, electrolysis cells, or cells for electro-organic syntheses. With the method electrodes with metal catalysts, alloys of metals or mixtures of metal oxides and metals can be manufactured in a simple manner. Only small amounts of the expensive catalyst material are consumed with this method.
With each embodiment, the method according to the inven-tion facilitates the use of the accurate amount of metal salts.
In this way, alloys or mixtures of metals and metal oxides of a predetermined combination can be accurately manufactured. An expert can to determine optimal mixture ratios by simple test procedures.
With the electrochemical precipitation, the active layer is formed on the diffusion layer in a controlled manner at the three-phase zone between the gas space in the pores of the gas diffusion electrode, the electro-active catalyst and the elec-trolytes. As a result, the catalyst utilization in application such as in fuel cells, electrolysis cells or cells for electro-organic synthesis is optimized and the required total amount is significantly reduced.
A fuel cells stack can be provided with pre-finished elec-trodes at one side and electrodes prepared in accordance with the method of the invention mounted at the other side. The electrolytic precipitation can be performed in the finished as-sembled fuel cell unit.
For single uses, units consisting of an ion conductive solid electrolyte, a manufactured gas diffusion electrode as counter electrode and a prepared operating electrode may be bolted together with a suitable seal or cemented together or they may be encapsulated in a similar way. For the applica-tion, the active electrode layer is formed by a short electro-lyte precipitation. Possible contamination or residues of the metal salt solution can subsequently be rinsed out.
Examples:
First example:
A diffusion layer for the technical gas diffusion elec-trode consisting of a mixture of finely distributed carbon and PTFE is manufactured. The diffusion layer contains no electro-mechanically active material:
A solution of a preferably 5% solution of nafion in low-molecular alcohols, preferably 1-propanol or 2 propanol and an aqueous solution of hexachloroplatinum acid hydrate (H2PtCl6) is prepared. The concentrations in the mixture of nafion solution and platinum solutions can be so adjusted that the desired im-pregnation with ion conductive nafion and the catalyst coating for the technical gas-diffusion electrode are obtained (pref-erably, 0.01 - 1 mg catalyst/c2 based on the geometric surface of the electrode). The mixture is then applied to the elec-trode by spraying brushing or screen-printing. As a counter electrode, a suitable electrode is provided or a counter elec-trode with an additional electrolyte layer is used. This stock unit is clamped together in an arrangement as shown in the fig-ure. By applying a current density in the particular applica-tion of 0.1 - 10 mA/cmZ, for example 2 mA/cmz, and a voltage of at least 1.23 V, for example, 2 V, the electrolysis is con-ducted at room temperature or at a raised temperature (<100 C) .......~...._ until all the platinum is deposited on the porous electrically conductive layer. By the addition of H20 as indicated in the figure, it is insured that the polymer solid electrolyte does not dry out and consequently is, or respectively remains, ioni-cally conductive. Subsequently, the electro-chemically active gas diffusion electrode so manufactured is treated for example with hydrogen peroxide, water and sulfuric acid and is cleaned.
Membrane electrode units with the manufactured electro-chemically active gas diffusion electrodes are used particu-larly in PEM fuel cells, for example, with a platinum coating of about 0.1 mg/cm2 for both the anode and the cathode. During operation with pure hydrogen and oxygen, current densities of more than 300 mA/cmz can be achieved at an operating tempera-ture of 80 C and with a terminal voltage of 0.7 V.
Second example.
The operation corresponds to that of the first example.
Instead of a platinum salt solution however, a mixture of platinum and ruthenium salt solutions (for example: H2PtC16 and RuCl3in H2SO4) is used. In this way, platinum-ruthenium alloys of a desired composition can be manufactured.
Third example.
The operation corresponds to that of the first example.
The nafion and metal salt containing solution is applied di-rectly to the solid electrolyte membrane by spraying brushing or screen-printing. Onto it a flexible graphite mesh or a graphite paper with suitable electronic conductivity and suit-able porosity for establishing electric contact is placed. The subsequent steps are the same as in the first example.
Fig. 1 is a schematic cross-sectional view of an electro-lyte layer 1 with a layer-like coating of a solution 2 disposed thereon. Electrodes 3 and 4 are disposed at opposite sides of the electrolyte layer 1. One of the electrodes 3 abuts the so-lution coating 2 and the other electrode 4 abuts the opposite side of the electrolyte layer 1. The electrode 4 includes a container-like recess 5. The container-like recess 5 is to be filled with water. Passages 6 present in the electrode 4 ex-tend from the container-like recess 5 to the membrane 1. The membrane 1 is moistened by the water in the container-like re-cess S. The moistened membrane remains electrically conduc-tive. It is necessary that the membrane is electrically con-ductive in order to achieve the electrochemical precipitation of the metal from the solution. For the precipitation, a cur-rent is applied in the manner as shown in Fig. 1.
The gases generated during the electrochemical precipita-tion are discharged by way of the gas passages 7.
The container-like recess 5 may be provided with a closure element, which is not shown. In that case, water vapors can be generated in the container for keeping the membrane moist.
The layer thickness that is the amount of metal salt deposited between the electrolyte and the electrode is for example so selected that up to 0.01-1 mg metal per cm2 can be deposited from the intermediate layer. In order to generate the electric current required for the deposition, for example, a second electrode which is also disposed adjacent the electrolyte layer may be provided as an additional current conductor. The electrolyte layer is then disposed between two electrodes.
In the method according to the invention, no liquid electrolyte is needed for the electrochemical deposition. Consequently, expensive liquid galvanic baths are eliminated. The 3a complicated and expensive reconditioning and decontamination of such galvanic baths is also eliminated. Only a thin layer of the solution is applied. The consumption of expensive metals such as platinum, ruthenium, rhodium or palladium is conse-quently minimized.
The catalytically active metal is deposited directly at the three-phase zone. The catalyst material is therefore ap-plied to the electrochemically active area related to the pre-determined utilization in a controlled manner.
As a result, the membrane with the catalyst deposited thereon can be manufactured comparatively inexpensively.
If electrodes together with the intermediate layer con-sisting of the metal salt solution are disposed at both sides of the electrolyte layer, this electrode-electrolyte compound structure can be used directly in a fuel cell.
For the manufacture of an alloy, in an advantageous em-bodiment of the method, the solution includes several metal salts, which are electrochemically deposited together. In this way, an alloy of two or more metals or mixtures of metals and metal oxides, that is, an alloy catalyst, is deposited. In particular, ruthenium and platinum containing salts are consid-ered.
With respect to the known state of the art, this embodi-ment of the method according to the invention has the advantage that alloy catalysts can be optimally deposited and produced at the same time.
In another advantageous embodiment of the invention, the solution contains an ion conductive polymer in a dissolved or liquid state.
After completion of the process, an ion conductive polymer in the solution should be firmly connected to the membrane (electrolyte layer), that is it should be part of the membrane.
A polymer suitable to achieve this object is to be selected.
If for example, a solid electrolyte consisting of nafion is used, preferably dissolved nafion is used as ion conductive polymer in the solution.
The ion-conductive polymer causes an increase of the three-phase zone and, consequently improves the utilization of the catalyst material.
With the above-mentioned embodiment of the invention, catalytically active material is embedded in the solid material electrolyte and is advantageously mechanically firmly connected therewith.
The method facilitates the manufacture of an electrochemi-cally active catalyst layer on a suitable carrier, which cata-lyst layer is suitable as a gas diffusion electrode for elec-trochemical applications such as in fuel cells, electrolysis cells, or cells for electro-organic syntheses. With the method electrodes with metal catalysts, alloys of metals or mixtures of metal oxides and metals can be manufactured in a simple manner. Only small amounts of the expensive catalyst material are consumed with this method.
With each embodiment, the method according to the inven-tion facilitates the use of the accurate amount of metal salts.
In this way, alloys or mixtures of metals and metal oxides of a predetermined combination can be accurately manufactured. An expert can to determine optimal mixture ratios by simple test procedures.
With the electrochemical precipitation, the active layer is formed on the diffusion layer in a controlled manner at the three-phase zone between the gas space in the pores of the gas diffusion electrode, the electro-active catalyst and the elec-trolytes. As a result, the catalyst utilization in application such as in fuel cells, electrolysis cells or cells for electro-organic synthesis is optimized and the required total amount is significantly reduced.
A fuel cells stack can be provided with pre-finished elec-trodes at one side and electrodes prepared in accordance with the method of the invention mounted at the other side. The electrolytic precipitation can be performed in the finished as-sembled fuel cell unit.
For single uses, units consisting of an ion conductive solid electrolyte, a manufactured gas diffusion electrode as counter electrode and a prepared operating electrode may be bolted together with a suitable seal or cemented together or they may be encapsulated in a similar way. For the applica-tion, the active electrode layer is formed by a short electro-lyte precipitation. Possible contamination or residues of the metal salt solution can subsequently be rinsed out.
Examples:
First example:
A diffusion layer for the technical gas diffusion elec-trode consisting of a mixture of finely distributed carbon and PTFE is manufactured. The diffusion layer contains no electro-mechanically active material:
A solution of a preferably 5% solution of nafion in low-molecular alcohols, preferably 1-propanol or 2 propanol and an aqueous solution of hexachloroplatinum acid hydrate (H2PtCl6) is prepared. The concentrations in the mixture of nafion solution and platinum solutions can be so adjusted that the desired im-pregnation with ion conductive nafion and the catalyst coating for the technical gas-diffusion electrode are obtained (pref-erably, 0.01 - 1 mg catalyst/c2 based on the geometric surface of the electrode). The mixture is then applied to the elec-trode by spraying brushing or screen-printing. As a counter electrode, a suitable electrode is provided or a counter elec-trode with an additional electrolyte layer is used. This stock unit is clamped together in an arrangement as shown in the fig-ure. By applying a current density in the particular applica-tion of 0.1 - 10 mA/cmZ, for example 2 mA/cmz, and a voltage of at least 1.23 V, for example, 2 V, the electrolysis is con-ducted at room temperature or at a raised temperature (<100 C) .......~...._ until all the platinum is deposited on the porous electrically conductive layer. By the addition of H20 as indicated in the figure, it is insured that the polymer solid electrolyte does not dry out and consequently is, or respectively remains, ioni-cally conductive. Subsequently, the electro-chemically active gas diffusion electrode so manufactured is treated for example with hydrogen peroxide, water and sulfuric acid and is cleaned.
Membrane electrode units with the manufactured electro-chemically active gas diffusion electrodes are used particu-larly in PEM fuel cells, for example, with a platinum coating of about 0.1 mg/cm2 for both the anode and the cathode. During operation with pure hydrogen and oxygen, current densities of more than 300 mA/cmz can be achieved at an operating tempera-ture of 80 C and with a terminal voltage of 0.7 V.
Second example.
The operation corresponds to that of the first example.
Instead of a platinum salt solution however, a mixture of platinum and ruthenium salt solutions (for example: H2PtC16 and RuCl3in H2SO4) is used. In this way, platinum-ruthenium alloys of a desired composition can be manufactured.
Third example.
The operation corresponds to that of the first example.
The nafion and metal salt containing solution is applied di-rectly to the solid electrolyte membrane by spraying brushing or screen-printing. Onto it a flexible graphite mesh or a graphite paper with suitable electronic conductivity and suit-able porosity for establishing electric contact is placed. The subsequent steps are the same as in the first example.
Fig. 1 is a schematic cross-sectional view of an electro-lyte layer 1 with a layer-like coating of a solution 2 disposed thereon. Electrodes 3 and 4 are disposed at opposite sides of the electrolyte layer 1. One of the electrodes 3 abuts the so-lution coating 2 and the other electrode 4 abuts the opposite side of the electrolyte layer 1. The electrode 4 includes a container-like recess 5. The container-like recess 5 is to be filled with water. Passages 6 present in the electrode 4 ex-tend from the container-like recess 5 to the membrane 1. The membrane 1 is moistened by the water in the container-like re-cess S. The moistened membrane remains electrically conduc-tive. It is necessary that the membrane is electrically con-ductive in order to achieve the electrochemical precipitation of the metal from the solution. For the precipitation, a cur-rent is applied in the manner as shown in Fig. 1.
The gases generated during the electrochemical precipita-tion are discharged by way of the gas passages 7.
The container-like recess 5 may be provided with a closure element, which is not shown. In that case, water vapors can be generated in the container for keeping the membrane moist.
~ .~~~,
Claims (5)
1. A method for the manufacture of an electrode-electrolyte unit with a catalytically active layer, comprising the steps of placing a solution including a dissolved metal salt as a layer between an electrolyte layer and an electrode and precipitating metal electrochemically, in situ, from the metal salt on said electrode, whereby all of the metal salt is used in the precipitation of the metal from the metal salt for forming said catalytically active layer.
2. A method according to claim 1, wherein several metal salts are dissolved in said solution and are placed together between said electrolyte layer and said electrode and electrochemically precipitating said metal from the metal salts.
3. A method according to claim 1, wherein the solution with said metal salt includes an ion conductive polymer.
4. A method according to claim 2, wherein the solution with said metal salts includes an ion conductive polymer.
5. A method according to claim 1, wherein said electrode and said electrolyte layer have passages leading to said dissolved metal salt layer and moisture is admitted to said dissolved metal salt layer through the passages in said electrode and gas formed during precipitation is discharged through said passages formed in said electrolyte layer.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19720688A DE19720688C1 (en) | 1997-05-16 | 1997-05-16 | Fuel cell electrode- solid electrolyte unit manufacture |
| DE19720688.3 | 1997-05-16 | ||
| PCT/DE1998/001302 WO1998053515A1 (en) | 1997-05-16 | 1998-05-08 | Production of electrolyte units by electrolytic deposition of a catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2288678A1 CA2288678A1 (en) | 1998-11-26 |
| CA2288678C true CA2288678C (en) | 2007-07-31 |
Family
ID=7829736
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002288678A Expired - Fee Related CA2288678C (en) | 1997-05-16 | 1998-05-08 | Production of electrolyte units by electrolytic deposition of a catalyst |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0988656B1 (en) |
| JP (1) | JP4519950B2 (en) |
| AT (1) | ATE225569T1 (en) |
| CA (1) | CA2288678C (en) |
| DE (2) | DE19720688C1 (en) |
| WO (1) | WO1998053515A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10038862C2 (en) * | 2000-08-04 | 2003-04-10 | Rolf Hempelmann | Process for coating a membrane electrode assembly with a catalyst and device therefor |
| DE10063741A1 (en) * | 2000-12-21 | 2002-07-11 | Forschungszentrum Juelich Gmbh | Process for double-sided coating of a membrane-electrode unit with a catalyst |
| DE10065074A1 (en) * | 2000-12-23 | 2002-07-04 | Forschungszentrum Juelich Gmbh | Process for the deposition of a catalyst |
| WO2008104322A2 (en) | 2007-02-26 | 2008-09-04 | Elcomax Gmbh | Method for producing a catalyst layer |
| DE102007033753B4 (en) | 2007-07-19 | 2014-07-03 | Cfso Gmbh | On its surface provided with metallic nanoparticles ultrahydrophobic substrate, process for its preparation and use thereof |
| DE102009051798A1 (en) | 2009-11-03 | 2011-05-05 | Elcomax Gmbh | Process for producing a catalyst-containing electrode layer |
| KR101209486B1 (en) | 2009-12-02 | 2012-12-07 | 광주과학기술원 | Method for fabricating of fuel cell |
| DE102010035592A1 (en) | 2010-08-27 | 2012-03-01 | Elcomax Gmbh | Electro-mechanical deposition of nanocrystalline Pt and Pt alloy catalyst layers on carbon fiber paper using a hydrogen-consuming anode |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3356538A (en) * | 1964-09-29 | 1967-12-05 | Gen Electric | Electrodeposited ion exchange membrane and method of forming |
| SU568989A1 (en) * | 1976-02-16 | 1977-08-15 | Московский Ордена Ленина Энергетический Институт | Method of metal coating of ion-exchange membrane of fuel cell |
| JPS5475488A (en) * | 1977-11-28 | 1979-06-16 | Asahi Chem Ind Co Ltd | Composite ion exchange membrane |
| CH634881A5 (en) * | 1978-04-14 | 1983-02-28 | Bbc Brown Boveri & Cie | METHOD FOR ELECTROLYTICALLY DEPOSITING METALS. |
| US4293394A (en) * | 1980-03-31 | 1981-10-06 | Ppg Industries, Inc. | Electrolytically producing chlorine using a solid polymer electrolyte-cathode unit |
| EP0048505B1 (en) * | 1980-09-19 | 1984-05-30 | BBC Aktiengesellschaft Brown, Boveri & Cie. | Process and apparatus for continuously covering a solid-state electrolyte with a catalytically active metal |
| FR2624885B1 (en) * | 1987-12-17 | 1991-01-04 | Commissariat Energie Atomique | SOLID POLYMER ELECTRODE-ELECTROLYTE ASSEMBLY USED FOR EXAMPLE FOR THE ELECTROLYSIS OF WATER, AND ITS MANUFACTURING METHOD |
| US5084144A (en) * | 1990-07-31 | 1992-01-28 | Physical Sciences Inc. | High utilization supported catalytic metal-containing gas-diffusion electrode, process for making it, and cells utilizing it |
| US5284571A (en) * | 1992-09-04 | 1994-02-08 | General Motors Corporation | Method of making electrodes for electrochemical cells and electrodes made thereby |
| KR100389150B1 (en) * | 1994-10-20 | 2003-10-10 | 훽스트 악티엔게젤샤프트 | Metal-clad cation exchange membrane / electrode composite and its manufacturing method |
| FR2744840B1 (en) * | 1996-02-12 | 1998-03-20 | Commissariat Energie Atomique | PROCESS FOR PREPARING ELECTRODES FOR MEMBRANE FUEL CELLS, GAS ELECTRODES AND FOR SUCH PEMFC BATTERIES AND BATTERIES CONTAINING THEM |
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1997
- 1997-05-16 DE DE19720688A patent/DE19720688C1/en not_active Expired - Lifetime
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1998
- 1998-05-08 AT AT98933496T patent/ATE225569T1/en active
- 1998-05-08 JP JP54979298A patent/JP4519950B2/en not_active Expired - Fee Related
- 1998-05-08 EP EP98933496A patent/EP0988656B1/en not_active Expired - Lifetime
- 1998-05-08 CA CA002288678A patent/CA2288678C/en not_active Expired - Fee Related
- 1998-05-08 WO PCT/DE1998/001302 patent/WO1998053515A1/en active IP Right Grant
- 1998-05-08 DE DE59805819T patent/DE59805819D1/en not_active Expired - Lifetime
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| EP0988656A1 (en) | 2000-03-29 |
| DE19720688C1 (en) | 1998-06-18 |
| WO1998053515A1 (en) | 1998-11-26 |
| JP2001525980A (en) | 2001-12-11 |
| ATE225569T1 (en) | 2002-10-15 |
| EP0988656B1 (en) | 2002-10-02 |
| JP4519950B2 (en) | 2010-08-04 |
| CA2288678A1 (en) | 1998-11-26 |
| DE59805819D1 (en) | 2002-11-07 |
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