CA1113802A - Mixed oxide oxygen electrode - Google Patents
Mixed oxide oxygen electrodeInfo
- Publication number
- CA1113802A CA1113802A CA360,068A CA360068A CA1113802A CA 1113802 A CA1113802 A CA 1113802A CA 360068 A CA360068 A CA 360068A CA 1113802 A CA1113802 A CA 1113802A
- Authority
- CA
- Canada
- Prior art keywords
- nickel
- plate
- plaque
- polytetrafluoroethylene
- cobalt nitrate
- 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.)
- Expired
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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
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
-
- 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
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
- C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
-
- 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
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
- C25B11/077—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the compound being a non-noble metal oxide
- C25B11/0771—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the compound being a non-noble metal oxide of the spinel type
-
- 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
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
- C25B11/095—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one of the compounds being organic
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8817—Treatment of supports before application of the catalytic active composition
- H01M4/8821—Wet proofing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
- H01M4/8882—Heat treatment, e.g. drying, baking
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
- H01M4/8892—Impregnation or coating of the catalyst layer, e.g. by an ionomer
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
- H01M4/8896—Pressing, rolling, calendering
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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
- 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
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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
- H01M2300/00—Electrolytes
- H01M2300/0002—Aqueous electrolytes
- H01M2300/0014—Alkaline electrolytes
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- 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
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Abstract
Abstract of the Disclosure The invention disclosed is a novel method for the preparation of a nickel/cobalt oxide impregnated nickel plaque material involving a single oxidation step. The nickel plaque material is cleaned, impregnated with an aqueous cobalt nitrate solution and dried. The nickel/cobalt oxide is then formed in a single oxidation step.
Description
-` 11138~Z
This invention relates to the preparation of a nickel/cobalt oxide impregnated nickel plaque material.
Mixed oxides are receiving considerable attention as catalysts both for oxygen reduction (fuel cells and metal/air batteries) and oxygen evolution (electrolytes). The problem is to prepare these catalysts inexpensively and to incorporate them into practical electrode structures. One mixed oxide of particular interest is nickel/cobalt spinel of the formula NiCoO4.
British Patent No. 1,461,764 Published 19 January 1977 to Walter J.
King et al, discloses methods for the preparation of nickel/cobalt spinel which include the co-precipitation of nickel oxalate and cobalt oxalate followed by a heat treatment or freeze drying of the nitrates of nickel/cobalt followed by decomposition in Yacuo and a heat treatment. The heat treatment is effected at about 400C for 10 hours. These catalyst powders so formed are then mixed with carbon, for increased electrical conductivity, and a polytetra-fluoroethylene binder and pressed onto a metal screen which acts as a current conductor. This method is quite complex. The freeze drying of the nitrates is advantageous from the point of view of high catalytic activity but is a very time consuming and costly procedure.
In Canadian Patent No. 834,890, which issued on February 17, 1970 to John H. Sizer et al, a method for the preparation of a nickel/cobalt oxide impregnated nickel plaque material is described. In the disclosed method, a layer of nickel oxide is formed on the plaque in a first oxidation step by heat treatment at 650C. The oxidized material is then impregnated with cobalt nitrate and a second oxidation step is performed at 500C to form cobalt oxide and to react the cobalt oxide so formed with the already present nickel oxide, to form the nickel/cobalt spinel. This procedure is also time consum-ing and complex because of the multiple oxidation steps.
~oth of the aforementioned patents involve heat treatments at 400 to 650C. Applicant has found that heat treatments at such high temperatures have deleterious effects as will be apparent hereinafter.
I ~' .... .
- .
- ` 11138~2 According to one aspect of the invention, a method for the prepara-tion of a nickel/cobalt oxide impregnated nickel plaque material is contem-plated, comprising a) providing a substantially oxide free sintered metal plaque material;
b) dipping the nickel plaque in an aqueous solution of cobalt nitrate;
c) drying the cobalt nitrate impregnated plaque so formed; and d) heat treating at about 200 to 350C for about 1 to 8 hours, to form the nickel/cobalt oxide impregnated nickel plaque material.
In the drawing which serves to illustrate the preferred embodiments of the invention, Figures 1 to 3 are graphs illustrating the operation of electrodes made of the nickel/cobalt spinel prepared in accordance with the invention.
The following examples described in detail methods for preparing electrodes containing a nickel/cobalt oxide catalyst.
Example I -A 3018 x 3.18 cm square flat plate of thickness of 0.071 cm of clean dry sintered nickel plaque with a 1.27 x 1.27 cm tab extending from one corner was dipped in an aqueous solution containlng 800 mg/ml of cobalt nltrate hexahydrate (Co(N03)2.6H20). The plaque was drained, dried over a hot plate and left to dry thoroughly overnight in an oven at 125C. The plaque was then transferred to a furnace at 250C where it was left for 4 hours. This electrode proved sui~able for catalysis of the evolution of oxygen in an elèctrolysis cell.
Example II
A 3.18 x 3.18 cm square flat plate of thickness 0.071 cm of clean dry sintered nickel plaque with a 1.27 x 1.27 cm tab extending from one corner was dipped in an aqueous solution containing 800 mg/ml of cobalt nitrate ;
.: : . . , ......................... :
.,, : , , ~ . : .: : . . ~ : -. .
1~138Q2 hexahydrate and 130 mg/ml polytetrafluoroethylene. This solution was prepared adding 8.00g of cobalt nitrate hexahydrate to a 10.0 ml volumetric flask, dissolving it in a little distilled water, adding 1.5 ml Teflon~ 30B and adding sufficient distilled water to bring the liquid level to the 10.0 ml mark and mixing thoroughly. The saturated plaque was drained, dried over a hot plate and left to dry thoroughly overnight in an oven at 125 C. The plaque was then transferred to a furnace at 250C where it was left for 4 hours. One side of the electrode was then covered with a piece of Zitex~ E606-223 poly-tetrafluoroethylene membrane which was pressed onto the electrode at 125C
and 112 kg/cm . This electrode proved suitable for the reduction of oxygen as is demonstrated in Figure 1 which is a plot of electrode potential vs current density in an electrolyte comprised of 4.4N potassium hydroxide.
A cell consisting of a cathode prepared as described in Example II, a nickel screen counter electrode, a mercury-mercuric oxide reference electrode and a 6.2N potassium hydroxide electrolyte was driven at a current density corresponding to 50 mA/cm on the cathode. As shown in Figure 2, the cathode was still performing satisfactorily after 5000 hours of operation.
Example III
A 3.18 x 3.18 cm square flat plate of thickness of 0.071 cm of clean dry sintered nickel plaque with a 1.27 x 1.27 cm tab extending from one corner was dipped in an aqueous solution containing 800 mg/ml of cobalt nitrate hexahydrate. The plaque was drained, dried over a hot plate and left to dry thoroughly overnight in an oven at 125C and then transferred to a furnace at 250C where it was left for 2 hours. One side of the plaque was covered with a piece of Zitex~ E606-223 polytetrafluoroethylene membrane which was cold-pressed onto the plaque. A solution containing 800 mg/ml of cobalt nitrate hexahydrate and 130 mg/ml polytetrafluoroethylene was added drop-wise to the bare side of the plaque until the plaque was saturated. The plaque was drained, dried over a hot plate and placed for 1 hour in an oven at 125C.
The Zitex~ cover was then removed and the plaque placed in a furnace at 250C
- . .: . .
- ~138~2 where it was left for 3 hours. This resulted in a flat plate electrode catalyzed evenly throughout with nickel/cobalt oxide but wet-proofed with polytetrafluoroethylene on only one side. The wet-proofed side was covered with a piece of Zite ~ E606-223 polytetrafluoroethylene membrane which was pressed onto the electrode at 125 C and 112 kg/cm .
This electrode was used both for the evolution and reduction of oxygen. A cell was prepared with this electrode mounted so that the side covered with polytetrafluoroethylene membrane had free access to the air while the other side was in contact with 6.2N KOH electrolyte. A nickel screen counter electrode and a mercury-mercuric oxide reference electrode completed the cell. By means of a power supply and a timing device, the nickel/cobalt oxide electrode was forced to alternately reduce oxygen and evolve oxygen in a manner similar to the requirements of an electrically rechargeable metal/air battery. The cycle consisted of 2 hours of oxygen -reduction at a current density of 50 mA/cm2 followed by 4 hours of oxygen evolution. The results on Figure 3 show that the electrode can operate satisfactorily for more than 200 such cycles. ~-As mentioned above, applicant has found that high oxidation tempera-tures produce certain deleterious effects on electrode performance.
Examples IV, V and VI illustrate the adverse affects of high oxida-tion temperatures. These electrodes were prepared in much the same way as ~ -Example II but with the following differences - -(i) the impregnation solution contained 600 mg/ml of cobalt nitrate and 87 mg/
ml PTFE, (ii) the drying time at 125C was only one hour and (iii) Electrode IV was oxidized for 4 hours at 200C and Electrode V for 4 -~
hours at 350C.
The potential of each of these electrodes in 6.2N KOH with respect to a .
~ mercury/mercuric oxide reference electrode is given below for a number of ; 30 current densities.
~; , - , , :
.,^,'.-: , ~' . ~ - , ' ' 1~-138~2 ELECTRODEOXIDATION POTENTLAL vs Hg/HgO 3 TEMPERATURE 26 53 83 106mA/cm _ _ _ IV 200C -77mV -118mV -160mV -180mV
It is evident that the electrode oxidized at 250C performed better than either of the other electrodes and the performance of the electrode oxidized at 350C (Electrode VI) was poorestO It would not support a current density of 106mA/cm .
Example VII
A clean dry sintered nickel plaque of the same dimensions as given in the other Examples was dipped into an aqueous solution containing 600 mg/ml of cobalt nitrate hexahydrate. The plaque was drained, dried over a hot plate and left to dry for 1 hour in an oven at 125 C and then transferred to a furnace at 250C where it was left to oxidize for 4 hours. The plaque was then washed in flowing dis~illed water for 15 minutes, drained, dried in an ~ -, oven at 125C for 10 minutes and dipped in a solution prepared by mixing 0.5 ml of Teflo ~ 30-B with 5 ml of distilled H20. The plaque was drained, dried in an oven at 125C for 1 hour and then placed on a hot plate at 250C for 3 minutes. One side of the flat plate electrode was covered with a piece of Zitex~ E 606 223 polytetrafluoroethylene membrane which was hot pressed onto the electrode at 125C and 112 kg/cm2.
Example VIII
The electrode was prepared in the same way as VII except that the oxidation step was carried out for 4 hours in a furnace at 350C rather than 250C. The potential of each of these electrodes, in 6.2N KOH with respect to a mercury/mercuric oxide reference electrode is given below for a number of current densities.
1~138~ .
ELECTRODE OXIDATION POTENTIAL vs Hg/HgO 2 TEMPERATURE 16 26 53 106mA/cm VII 250C -66mV -96 mV -165mV -299mV
VIII 350C -96 -149 -257 _ :
Electrode VIII, oxidized at 350C would not support a current density of 106mA/cm . This further illustrates the deleterious effects of higher oxida- ~ -tion temperatures.
It is essential to the invention that the starting material, the nickel plaque, be substantially oxide free. Specifically, there must not be a layer of nickel oxide on the plaque prior to impregnation with the cobalt nitrate solution.
Typically, the nickel plaque is pre-cleaned according to the follow-ing procedureO The porous sintered nickel plaque is first degreased by soaking iin trichloroethylene for ten minutes. The plaque is then rinsed with methanol to remove the trichloroethylene. After drying at room temperature the plaque i8 covered with a dilute solution of nitric acid (20 ml of concentrated HNO3 diluted to 100 ml with distilled water) and left for 2 minutes. This .
dissolves any oxides which may be on the surface of the plaque. The plaque i8 next washet in flowing tistillet water for 15 minutes, drained and dried in an oven at 125C for not more than 10 minUteQ too(low a temperature and short a time to form nickel oxite). As soon as it becomes sufficiently cool, the plaque is immerset in the impregnation solution.
In view of the preferred embotiments tescribet above, it shoult be apparent to those skilled in the art that the present invention may be embodied in forms other than those specifically tescribed herein without departing from the spirit or central characteristics of the invention. Thus, the specific embodiments tescribet herein are to be considered as illustrative and by no means restrictive.
.
, ..... . . .
This invention relates to the preparation of a nickel/cobalt oxide impregnated nickel plaque material.
Mixed oxides are receiving considerable attention as catalysts both for oxygen reduction (fuel cells and metal/air batteries) and oxygen evolution (electrolytes). The problem is to prepare these catalysts inexpensively and to incorporate them into practical electrode structures. One mixed oxide of particular interest is nickel/cobalt spinel of the formula NiCoO4.
British Patent No. 1,461,764 Published 19 January 1977 to Walter J.
King et al, discloses methods for the preparation of nickel/cobalt spinel which include the co-precipitation of nickel oxalate and cobalt oxalate followed by a heat treatment or freeze drying of the nitrates of nickel/cobalt followed by decomposition in Yacuo and a heat treatment. The heat treatment is effected at about 400C for 10 hours. These catalyst powders so formed are then mixed with carbon, for increased electrical conductivity, and a polytetra-fluoroethylene binder and pressed onto a metal screen which acts as a current conductor. This method is quite complex. The freeze drying of the nitrates is advantageous from the point of view of high catalytic activity but is a very time consuming and costly procedure.
In Canadian Patent No. 834,890, which issued on February 17, 1970 to John H. Sizer et al, a method for the preparation of a nickel/cobalt oxide impregnated nickel plaque material is described. In the disclosed method, a layer of nickel oxide is formed on the plaque in a first oxidation step by heat treatment at 650C. The oxidized material is then impregnated with cobalt nitrate and a second oxidation step is performed at 500C to form cobalt oxide and to react the cobalt oxide so formed with the already present nickel oxide, to form the nickel/cobalt spinel. This procedure is also time consum-ing and complex because of the multiple oxidation steps.
~oth of the aforementioned patents involve heat treatments at 400 to 650C. Applicant has found that heat treatments at such high temperatures have deleterious effects as will be apparent hereinafter.
I ~' .... .
- .
- ` 11138~2 According to one aspect of the invention, a method for the prepara-tion of a nickel/cobalt oxide impregnated nickel plaque material is contem-plated, comprising a) providing a substantially oxide free sintered metal plaque material;
b) dipping the nickel plaque in an aqueous solution of cobalt nitrate;
c) drying the cobalt nitrate impregnated plaque so formed; and d) heat treating at about 200 to 350C for about 1 to 8 hours, to form the nickel/cobalt oxide impregnated nickel plaque material.
In the drawing which serves to illustrate the preferred embodiments of the invention, Figures 1 to 3 are graphs illustrating the operation of electrodes made of the nickel/cobalt spinel prepared in accordance with the invention.
The following examples described in detail methods for preparing electrodes containing a nickel/cobalt oxide catalyst.
Example I -A 3018 x 3.18 cm square flat plate of thickness of 0.071 cm of clean dry sintered nickel plaque with a 1.27 x 1.27 cm tab extending from one corner was dipped in an aqueous solution containlng 800 mg/ml of cobalt nltrate hexahydrate (Co(N03)2.6H20). The plaque was drained, dried over a hot plate and left to dry thoroughly overnight in an oven at 125C. The plaque was then transferred to a furnace at 250C where it was left for 4 hours. This electrode proved sui~able for catalysis of the evolution of oxygen in an elèctrolysis cell.
Example II
A 3.18 x 3.18 cm square flat plate of thickness 0.071 cm of clean dry sintered nickel plaque with a 1.27 x 1.27 cm tab extending from one corner was dipped in an aqueous solution containing 800 mg/ml of cobalt nitrate ;
.: : . . , ......................... :
.,, : , , ~ . : .: : . . ~ : -. .
1~138Q2 hexahydrate and 130 mg/ml polytetrafluoroethylene. This solution was prepared adding 8.00g of cobalt nitrate hexahydrate to a 10.0 ml volumetric flask, dissolving it in a little distilled water, adding 1.5 ml Teflon~ 30B and adding sufficient distilled water to bring the liquid level to the 10.0 ml mark and mixing thoroughly. The saturated plaque was drained, dried over a hot plate and left to dry thoroughly overnight in an oven at 125 C. The plaque was then transferred to a furnace at 250C where it was left for 4 hours. One side of the electrode was then covered with a piece of Zitex~ E606-223 poly-tetrafluoroethylene membrane which was pressed onto the electrode at 125C
and 112 kg/cm . This electrode proved suitable for the reduction of oxygen as is demonstrated in Figure 1 which is a plot of electrode potential vs current density in an electrolyte comprised of 4.4N potassium hydroxide.
A cell consisting of a cathode prepared as described in Example II, a nickel screen counter electrode, a mercury-mercuric oxide reference electrode and a 6.2N potassium hydroxide electrolyte was driven at a current density corresponding to 50 mA/cm on the cathode. As shown in Figure 2, the cathode was still performing satisfactorily after 5000 hours of operation.
Example III
A 3.18 x 3.18 cm square flat plate of thickness of 0.071 cm of clean dry sintered nickel plaque with a 1.27 x 1.27 cm tab extending from one corner was dipped in an aqueous solution containing 800 mg/ml of cobalt nitrate hexahydrate. The plaque was drained, dried over a hot plate and left to dry thoroughly overnight in an oven at 125C and then transferred to a furnace at 250C where it was left for 2 hours. One side of the plaque was covered with a piece of Zitex~ E606-223 polytetrafluoroethylene membrane which was cold-pressed onto the plaque. A solution containing 800 mg/ml of cobalt nitrate hexahydrate and 130 mg/ml polytetrafluoroethylene was added drop-wise to the bare side of the plaque until the plaque was saturated. The plaque was drained, dried over a hot plate and placed for 1 hour in an oven at 125C.
The Zitex~ cover was then removed and the plaque placed in a furnace at 250C
- . .: . .
- ~138~2 where it was left for 3 hours. This resulted in a flat plate electrode catalyzed evenly throughout with nickel/cobalt oxide but wet-proofed with polytetrafluoroethylene on only one side. The wet-proofed side was covered with a piece of Zite ~ E606-223 polytetrafluoroethylene membrane which was pressed onto the electrode at 125 C and 112 kg/cm .
This electrode was used both for the evolution and reduction of oxygen. A cell was prepared with this electrode mounted so that the side covered with polytetrafluoroethylene membrane had free access to the air while the other side was in contact with 6.2N KOH electrolyte. A nickel screen counter electrode and a mercury-mercuric oxide reference electrode completed the cell. By means of a power supply and a timing device, the nickel/cobalt oxide electrode was forced to alternately reduce oxygen and evolve oxygen in a manner similar to the requirements of an electrically rechargeable metal/air battery. The cycle consisted of 2 hours of oxygen -reduction at a current density of 50 mA/cm2 followed by 4 hours of oxygen evolution. The results on Figure 3 show that the electrode can operate satisfactorily for more than 200 such cycles. ~-As mentioned above, applicant has found that high oxidation tempera-tures produce certain deleterious effects on electrode performance.
Examples IV, V and VI illustrate the adverse affects of high oxida-tion temperatures. These electrodes were prepared in much the same way as ~ -Example II but with the following differences - -(i) the impregnation solution contained 600 mg/ml of cobalt nitrate and 87 mg/
ml PTFE, (ii) the drying time at 125C was only one hour and (iii) Electrode IV was oxidized for 4 hours at 200C and Electrode V for 4 -~
hours at 350C.
The potential of each of these electrodes in 6.2N KOH with respect to a .
~ mercury/mercuric oxide reference electrode is given below for a number of ; 30 current densities.
~; , - , , :
.,^,'.-: , ~' . ~ - , ' ' 1~-138~2 ELECTRODEOXIDATION POTENTLAL vs Hg/HgO 3 TEMPERATURE 26 53 83 106mA/cm _ _ _ IV 200C -77mV -118mV -160mV -180mV
It is evident that the electrode oxidized at 250C performed better than either of the other electrodes and the performance of the electrode oxidized at 350C (Electrode VI) was poorestO It would not support a current density of 106mA/cm .
Example VII
A clean dry sintered nickel plaque of the same dimensions as given in the other Examples was dipped into an aqueous solution containing 600 mg/ml of cobalt nitrate hexahydrate. The plaque was drained, dried over a hot plate and left to dry for 1 hour in an oven at 125 C and then transferred to a furnace at 250C where it was left to oxidize for 4 hours. The plaque was then washed in flowing dis~illed water for 15 minutes, drained, dried in an ~ -, oven at 125C for 10 minutes and dipped in a solution prepared by mixing 0.5 ml of Teflo ~ 30-B with 5 ml of distilled H20. The plaque was drained, dried in an oven at 125C for 1 hour and then placed on a hot plate at 250C for 3 minutes. One side of the flat plate electrode was covered with a piece of Zitex~ E 606 223 polytetrafluoroethylene membrane which was hot pressed onto the electrode at 125C and 112 kg/cm2.
Example VIII
The electrode was prepared in the same way as VII except that the oxidation step was carried out for 4 hours in a furnace at 350C rather than 250C. The potential of each of these electrodes, in 6.2N KOH with respect to a mercury/mercuric oxide reference electrode is given below for a number of current densities.
1~138~ .
ELECTRODE OXIDATION POTENTIAL vs Hg/HgO 2 TEMPERATURE 16 26 53 106mA/cm VII 250C -66mV -96 mV -165mV -299mV
VIII 350C -96 -149 -257 _ :
Electrode VIII, oxidized at 350C would not support a current density of 106mA/cm . This further illustrates the deleterious effects of higher oxida- ~ -tion temperatures.
It is essential to the invention that the starting material, the nickel plaque, be substantially oxide free. Specifically, there must not be a layer of nickel oxide on the plaque prior to impregnation with the cobalt nitrate solution.
Typically, the nickel plaque is pre-cleaned according to the follow-ing procedureO The porous sintered nickel plaque is first degreased by soaking iin trichloroethylene for ten minutes. The plaque is then rinsed with methanol to remove the trichloroethylene. After drying at room temperature the plaque i8 covered with a dilute solution of nitric acid (20 ml of concentrated HNO3 diluted to 100 ml with distilled water) and left for 2 minutes. This .
dissolves any oxides which may be on the surface of the plaque. The plaque i8 next washet in flowing tistillet water for 15 minutes, drained and dried in an oven at 125C for not more than 10 minUteQ too(low a temperature and short a time to form nickel oxite). As soon as it becomes sufficiently cool, the plaque is immerset in the impregnation solution.
In view of the preferred embotiments tescribet above, it shoult be apparent to those skilled in the art that the present invention may be embodied in forms other than those specifically tescribed herein without departing from the spirit or central characteristics of the invention. Thus, the specific embodiments tescribet herein are to be considered as illustrative and by no means restrictive.
.
, ..... . . .
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the preparation of a nickel/cobalt oxide impregnated nickel plaque material, comprising (a) providing a substantially oxide free sintered metal plaque material;
(b) dipping the nickel plaque in an aqueous solution of cobalt nitrate;
(c) drying the cobalt nitrate impregnated plaque so formed; and (d) heat treating at about 200 to 350°C for about 1 to 8 hours, to form the nickel/cobalt oxide impregnated nickel plaque material.
(b) dipping the nickel plaque in an aqueous solution of cobalt nitrate;
(c) drying the cobalt nitrate impregnated plaque so formed; and (d) heat treating at about 200 to 350°C for about 1 to 8 hours, to form the nickel/cobalt oxide impregnated nickel plaque material.
2. A method according to claim 1, wherein the concentration of the aqueous cobalt nitrate is 200 to 800 mg/ml.
3. A method according to claim 2, wherein the concentration of the aqueous cobalt nitrate is about 800 mg/ml.
4. A method according to claim 2, wherein the heat treatment is effected at about 250°C for about 4 hours in a drying furnace.
5. A method according to claim 1 wherein step (c) the plaque is air dried at about 125°C for about 12 hours.
6. A method according to claim 1, 2 or 4, wherein immediately prior to step (a) the nickel plaque is subjected to a cleaning treatment to remove oxides which may be on the surface of the plaque.
7. A method according to claim 1, 2 or 4, wherein step (b) the aqueous cobalt nitrate includes polytetrafluoroethylene as wet-proofing agent.
8. A method according to claim 2, which includes the additional steps of (e) dipping the nickel/cobalt oxide impregnated plaque material in aqueous polytetrafluoroethylene; and (f) drying the wet-proofed plaque material so formed.
9. A method according to claim 8, wherein the nickel plaque material is in the form of a flat plate and including the additional steps of (g) covering one side of the plate with a polytetrafluoroethylene membrane; and (h) hot pressing the membrane onto the plate.
10. A method according to claim 1 or 2; wherein the nickel plaque material is in the form of a flat plate, including the additional steps of (e) covering one side of the plate with a polytetrafluoroethylene membrane;
(f) cold pressing the membrane onto the plate;
(g) exposing the other side of the plate to aqueous cobalt nitrate and polytetrafluoroethylene solution;
(h) drying the plate;
(i) removing the polytetrafluoroethylene covering from said one site of the plate;
(j) heat treating the plate at about 250°C for about 3 hours, to form a plate wet-proofed only on said other side of the plate;
(k) covering the wet-proofed side of the plate with a polytetra-fluoroethylene membrane; and (l) hot-pressing the membrane onto the plate.
(f) cold pressing the membrane onto the plate;
(g) exposing the other side of the plate to aqueous cobalt nitrate and polytetrafluoroethylene solution;
(h) drying the plate;
(i) removing the polytetrafluoroethylene covering from said one site of the plate;
(j) heat treating the plate at about 250°C for about 3 hours, to form a plate wet-proofed only on said other side of the plate;
(k) covering the wet-proofed side of the plate with a polytetra-fluoroethylene membrane; and (l) hot-pressing the membrane onto the plate.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA360,068A CA1113802A (en) | 1980-09-02 | 1980-09-02 | Mixed oxide oxygen electrode |
| US06/256,665 US4391668A (en) | 1980-09-02 | 1981-04-22 | Mixed oxide oxygen electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA360,068A CA1113802A (en) | 1980-09-02 | 1980-09-02 | Mixed oxide oxygen electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113802A true CA1113802A (en) | 1981-12-08 |
Family
ID=4117859
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA360,068A Expired CA1113802A (en) | 1980-09-02 | 1980-09-02 | Mixed oxide oxygen electrode |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4391668A (en) |
| CA (1) | CA1113802A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4596638A (en) * | 1985-04-26 | 1986-06-24 | International Fuel Cells Corporation | Method for the electrochemical production of adiponitrile using anodes having NiCo2 O4 catalyst |
| US4585532A (en) * | 1985-04-26 | 1986-04-29 | International Fuel Cells Corporation | Method for using anodes having NiCo2 O4 catalyst for the electrolysis of potassium hydroxide solutions and method of making an anode containing NiCo2 O4 catalyst |
| US4996083A (en) * | 1987-02-19 | 1991-02-26 | Donnelly Corporation | Method for deposition of electrochromic layers |
| US4959247A (en) * | 1987-12-14 | 1990-09-25 | Donnelly Corporation | Electrochromic coating and method for making same |
| US5489314A (en) * | 1991-10-21 | 1996-02-06 | Yuasa Corporation | Manufacturing method of nickel plate and manufacturing method of alkaline battery |
| US20080280190A1 (en) * | 2005-10-20 | 2008-11-13 | Robert Brian Dopp | Electrochemical catalysts |
| US20070092784A1 (en) * | 2005-10-20 | 2007-04-26 | Dopp Robert B | Gas diffusion cathode using nanometer sized particles of transition metals for catalysis |
| US20070227300A1 (en) * | 2006-03-31 | 2007-10-04 | Quantumsphere, Inc. | Compositions of nanometal particles containing a metal or alloy and platinum particles for use in fuel cells |
| US7955755B2 (en) | 2006-03-31 | 2011-06-07 | Quantumsphere, Inc. | Compositions of nanometal particles containing a metal or alloy and platinum particles |
| CN101549890B (en) * | 2009-04-30 | 2011-01-19 | 中山大学 | Solvothermal Synthesis of Nickel Cobalt Oxide Nanoparticles |
| CN103646792B (en) * | 2013-12-19 | 2016-08-31 | 山东大学 | A kind of preparation method of metal/metal oxide nano composite material |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IL50217A (en) * | 1976-08-06 | 1980-01-31 | Israel State | Electrocatalytically acitve spinel type mixed oxides |
| GB1556452A (en) * | 1977-10-25 | 1979-11-28 | Nat Res Dev | Catalysing hydrogen evolution |
-
1980
- 1980-09-02 CA CA360,068A patent/CA1113802A/en not_active Expired
-
1981
- 1981-04-22 US US06/256,665 patent/US4391668A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4391668A (en) | 1983-07-05 |
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