USH1334H - Method of making a teflon bonded cathode for use in a high temperature cell and high temperature cell including said cathode - Google Patents
Method of making a teflon bonded cathode for use in a high temperature cell and high temperature cell including said cathode Download PDFInfo
- Publication number
- USH1334H USH1334H US07/715,083 US71508391A USH1334H US H1334 H USH1334 H US H1334H US 71508391 A US71508391 A US 71508391A US H1334 H USH1334 H US H1334H
- Authority
- US
- United States
- Prior art keywords
- cathode
- high temperature
- weight percent
- teflon
- temperature cell
- 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.)
- Abandoned
Links
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
- H01M4/02—Electrodes composed of, or comprising, active material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
- H01M10/39—Accumulators not provided for in groups H01M10/05-H01M10/34 working at high temperature
- H01M10/3909—Sodium-sulfur 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
- 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
- Y02E60/10—Energy storage using batteries
Definitions
- This invention relates in general to a method of preparing a teflon bonded cathode, and in particular to a high temperature electrochemical cell including the cathode, the cell containing sodium as the anode, a solid electrolyte separator of ⁇ "-Al 2 O 3 , and a teflon bonded iron (IV) sulfide cathode emmersed in a molten salt electrolyte of NaAlCl 4 and electrochemically operated at 200° C.
- Previous cathodes used for other Na/ ⁇ "-Al 2 O 3 /NaAlCl 4 -transition metal sulfide cells used a slurry mixture of the transition metal sulfide and electrolyte formed onto a graphite felt that was then contained in a separated compartment from the sodium anode.
- the general object of this invention is to provide a cathode for use in a high temperature electrochemical cell wherein the cathode is free standing and impervious to attack by the electrolyte at the cell's operating temperature of 200° C.
- a further object of the invention is to provide such a cathode where only the weight percent of graphite is needed in the cathode to aid in reducing cell polarization while providing excellent cell performance at discharge rates up to 200 mA/cm 2 .
- a still further object of the invention is to provide a method of making a cathode that will provide excellent electrochemical cell performance of the Na/Na- ⁇ "-Al 2 O 3 /NaAlCl 4 -FeS 2 cell when operated at 200° C.
- thermally sintered cathodes made from powdered mixtures of transition metal sulfides, a conductive diluant, and teflon aqueous emulsion onto a metal grid, plate or sheet.
- the cathode electrodes are prepared using 80 to 90 weight percent powdered transition metal sulfide active materials such as FeS 2 , NiS 2 , CoS 2 , FeS, NiS, and CoS mixed with 5 to 10 weight percent conductive diluents such as graphite, carbon, and metal powders or fibers with 5 to 10 weight percent Teflon solids from a Teflon-aqueous emulsion.
- a distilled water-isopropylalcohol solution 60/40 wt %) in drop wise additions until a tough dough like consistency is attained.
- the cathode dough is then successively roll pressed between two Mylar plastic sheets to a thickness of about three quarters of a millimeter.
- the cathode sheet is then cut into two equally sized pieces and a metal current collector grid placed in between them.
- the cathode with the grid is then roll pressed between the Mylar sheets to a thickness of about one millimeter.
- the rolled cathode is then placed between two polished aluminum plates, which keep the cathode flat and avoids curling during sintering, and sintered at 280° C. for one hour in an evacuated oven.
- the Teflon sintered cathodes are cooled under vacuum to ambient temperature before being transferred into an argon filled glove box.
- a specific cathode preparation utilizes 80 weight percent iron (IV) sulfide (-325 mesh powder) as the active cathode component, 10 weight percent graphite powder as the conductive diluent, and 10 weight percent Teflon as the cathode binder sintered onto an expanded stainless steel grid at 280° C. for one hour under vacuum.
- a stainless steel rod provided electrical contact with the molten sodium metal and electrical contact to the cathode is provided by spot welding a portion of the cathode grid to the stainless can.
- the assembled cell is then sealed into an 8 cm inside diameter sealed bottom Pyrex glass vessel equipped with a threaded Teflon cap having electrical feed throughs and inert gas inlet and outlet fittings. Electrical connections are made between the cell and the feed throughs of the Teflon cap and argon gas is continuously purged through the cell during the galvanostatic cycling performed at 200° C.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
A method is provided for preparing flexible, free standing electrodes for use in preparing transition metal sulfide cathodes for use in high temperature electrochemical cells. Specifically, the cells contain sodium as the anode, a solid electrolyte separator of β"-Al2 O3, and a Teflon bonded iron (IV) sulfide cathode emmersed in a molten salt electrolyte of NaAlCl4 and electrochemically operated at 200° C.
Description
The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.
This invention relates in general to a method of preparing a teflon bonded cathode, and in particular to a high temperature electrochemical cell including the cathode, the cell containing sodium as the anode, a solid electrolyte separator of β"-Al2 O3, and a teflon bonded iron (IV) sulfide cathode emmersed in a molten salt electrolyte of NaAlCl4 and electrochemically operated at 200° C.
It has been desired in the art to provide a method for preparing flexible free standing electrodes for use in preparing transition metal sulfide cathodes for use in high temperature electrochemical cells; particularly cells of the type Na/β"-Al2 O3 /NaAlCl4 -transition metal sulfide electrochemical cell at 200° C. Previous cathodes used for other Na/β"-Al2 O3 /NaAlCl4 -transition metal sulfide cells used a slurry mixture of the transition metal sulfide and electrolyte formed onto a graphite felt that was then contained in a separated compartment from the sodium anode. The disadvantage of this cell preparation was that large amounts of graphite felt of greater than 20 weight percent were needed in the cathode to provide sufficient electrical contact to the transition metal sulfide active material. In addition, this type of cathode process didn't immobilize the active cathode materials and thus after the electrolyte was molten, the active materials settled in the cell resulting in an nonuniform distribution of the electrochemical products.
The general object of this invention is to provide a cathode for use in a high temperature electrochemical cell wherein the cathode is free standing and impervious to attack by the electrolyte at the cell's operating temperature of 200° C. A further object of the invention is to provide such a cathode where only the weight percent of graphite is needed in the cathode to aid in reducing cell polarization while providing excellent cell performance at discharge rates up to 200 mA/cm2. A still further object of the invention is to provide a method of making a cathode that will provide excellent electrochemical cell performance of the Na/Na-β"-Al2 O3 /NaAlCl4 -FeS2 cell when operated at 200° C.
It has now been found that the aforementioned objects can be attained by preparing thermally sintered cathodes made from powdered mixtures of transition metal sulfides, a conductive diluant, and teflon aqueous emulsion onto a metal grid, plate or sheet.
The cathode electrodes are prepared using 80 to 90 weight percent powdered transition metal sulfide active materials such as FeS2, NiS2, CoS2, FeS, NiS, and CoS mixed with 5 to 10 weight percent conductive diluents such as graphite, carbon, and metal powders or fibers with 5 to 10 weight percent Teflon solids from a Teflon-aqueous emulsion. Into the aforementioned cathode mixture is added a distilled water-isopropylalcohol solution (60/40 wt %) in drop wise additions until a tough dough like consistency is attained. The cathode dough is then successively roll pressed between two Mylar plastic sheets to a thickness of about three quarters of a millimeter. The cathode sheet is then cut into two equally sized pieces and a metal current collector grid placed in between them. The cathode with the grid is then roll pressed between the Mylar sheets to a thickness of about one millimeter. The rolled cathode is then placed between two polished aluminum plates, which keep the cathode flat and avoids curling during sintering, and sintered at 280° C. for one hour in an evacuated oven. The Teflon sintered cathodes are cooled under vacuum to ambient temperature before being transferred into an argon filled glove box.
A specific cathode preparation utilizes 80 weight percent iron (IV) sulfide (-325 mesh powder) as the active cathode component, 10 weight percent graphite powder as the conductive diluent, and 10 weight percent Teflon as the cathode binder sintered onto an expanded stainless steel grid at 280° C. for one hour under vacuum.
This cathode is prepared into a high temperature electrochemical cell consisting of 2.5 grams of liquid sodium contained in a Ceramatec β"-Al2 O3 sealed end solid electrolyte tube having dimensions of 0.9 cm inside diameter, 10 cm length, and 0.083 cm thickness emmersed in a 2.54 cm diameter stainless steel can having a length of 4.86 cm and thickness of 0.05 cm containing 6.5 grams of NaAlCl4 molten salt electrolyte (mp=150° C.) into which is emmersed the Teflon bonded FeS2 cathode. A stainless steel rod provided electrical contact with the molten sodium metal and electrical contact to the cathode is provided by spot welding a portion of the cathode grid to the stainless can. The assembled cell is then sealed into an 8 cm inside diameter sealed bottom Pyrex glass vessel equipped with a threaded Teflon cap having electrical feed throughs and inert gas inlet and outlet fittings. Electrical connections are made between the cell and the feed throughs of the Teflon cap and argon gas is continuously purged through the cell during the galvanostatic cycling performed at 200° C.
We wish it to be understood that we do not desire to be limited to the exact details of construction as described for obvious modifications will occur to a person skilled in the art.
Claims (1)
1. A high temperature electrochemical cell including sodium as the anode, a solid electrolyte separator of B"-Al2 O3 ', and a Teflon bonded iron (iv) sulfide cathode emersed in a molten salt electrolyte of NaAlCl4 and capable of being electrochemically operated at 200° C., wherein the teflon bonded cathode is obtained by a method including the steps of:
(A) forming a mixture of about 80 weight percent FeS2 as the active cathode component, about 10 weight percent graphite as the conductive diluent, and about 10 weight percent Teflon as the cathode binder,
(B) drop wise adding a wetting agent of distilled water-isopropylalcohol (60/40 weight percent) solution to the mixture to form a stiff dough,
(C) roll pressing the dough onto a expanded metal grid current collector and sintering at about 280° C. for about one hour under vacuum, and
(D) cooling under vacuum to ambient temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/715,083 USH1334H (en) | 1991-06-10 | 1991-06-10 | Method of making a teflon bonded cathode for use in a high temperature cell and high temperature cell including said cathode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/715,083 USH1334H (en) | 1991-06-10 | 1991-06-10 | Method of making a teflon bonded cathode for use in a high temperature cell and high temperature cell including said cathode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USH1334H true USH1334H (en) | 1994-07-05 |
Family
ID=24872612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US07/715,083 Abandoned USH1334H (en) | 1991-06-10 | 1991-06-10 | Method of making a teflon bonded cathode for use in a high temperature cell and high temperature cell including said cathode |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | USH1334H (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170125794A1 (en) * | 2014-04-21 | 2017-05-04 | Xiamen University | A sulfur-based transition metal composite and the negative electrode comprising the same and the battery comprising the same |
| US9748564B2 (en) * | 2014-11-21 | 2017-08-29 | General Electric Company | Electrode compositions and related energy storage devices |
-
1991
- 1991-06-10 US US07/715,083 patent/USH1334H/en not_active Abandoned
Non-Patent Citations (1)
| Title |
|---|
| Encyclopedia of Polymer Science and Engineering, vol. 16, pp. 624, 625, (9), John Wiley & Sons, Inc. |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170125794A1 (en) * | 2014-04-21 | 2017-05-04 | Xiamen University | A sulfur-based transition metal composite and the negative electrode comprising the same and the battery comprising the same |
| US10847783B2 (en) * | 2014-04-21 | 2020-11-24 | Xiamen University | Sulfur-based transition metal composite and the negative electrode comprising the same and the battery comprising the same |
| US9748564B2 (en) * | 2014-11-21 | 2017-08-29 | General Electric Company | Electrode compositions and related energy storage devices |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| STCF | Information on status: patent grant |
Free format text: PATENTED CASE |