CA2244969C - Process for the production of an electrode for a fused carbonate fuel cell, electrode produced according to this process and fused carbonate fuel cell provided with an electrode produced according to this process - Google Patents
Process for the production of an electrode for a fused carbonate fuel cell, electrode produced according to this process and fused carbonate fuel cell provided with an electrode produced according to this process Download PDFInfo
- Publication number
- CA2244969C CA2244969C CA002244969A CA2244969A CA2244969C CA 2244969 C CA2244969 C CA 2244969C CA 002244969 A CA002244969 A CA 002244969A CA 2244969 A CA2244969 A CA 2244969A CA 2244969 C CA2244969 C CA 2244969C
- Authority
- CA
- Canada
- Prior art keywords
- plates
- electrode
- fuel cell
- lithium
- process according
- 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 - Fee Related
Links
Classifications
-
- 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
Landscapes
- Inert Electrodes (AREA)
- Fuel Cell (AREA)
Abstract
The invention concerns a process for the production of a porous lithium cobaltite electrode plate with a large inner surface and low polarization resistance. Lithium carbonate powder and cobalt metal powder are uniformly mixed together and then films are produced from the mixture and plates from the films, which plates are sintered and then placed in an air stream for several hours at a temperature between 400 ° C and 488 ° C until the conversion of said plates to lithium cobaltite electrode plates with an extremely large inner surface has taken place.
Description
SPECIFICATION
Process for the Production of an Electrode for a Fused Carbonate Fuel Cell, Electrode Produced According to this Process and Fused Carbonate Fuel Cell Provided With an Electrode Produced According to this Process The invention relates to a process for making an electrode for a carbonate melt fuel cell, an electrode made according to the process, and a carbonate melt fuel cell with an electrode made by the process.
The production of cathodes for carbonate melt fuel cells from lithium cobaltite (LiCoO~ is known. For making such cathodes, lithium cobaltite powder is mixed with a binder. A
dispersant can be added to the binder. A foil is made from the mixture which is divided into plates. The plates are sintered at high temperatures in an air-carbon dioxide atmosphere.
Lithium cobaltite is made by reacting cobalt with lithium compounds (EP 0 473 236 A2).
Making lithium cobaltite by reacting cobalt oxide (iron oxide) with lithium hydroxide vapor as a powder in a high-temperature reaction is also known. This powder is made into brittle electrode plates with small dimensions by a ceramic sintering process (JP
0636, 770).
Finally, making a lithium cobaltite layer from a ductile cobalt layer whose pores are filled with lithium carbonate is known. Conversion to the lithium cobaltite layer is preferably done after combination with a matrix layer and an anode layer and after installation together with current collector plates in a cell holder of a fuel cell during the start-up phase of the fuel cell.
The structure of the lithium cobaltite electrode plate made in this way corresponds to the structure of the original porous cobalt electrode plate which has a relatively high polarization resistance (DE 43 03 136 Cl).
The invention is based on the problem of creating a process for producing a porous lithium cobaltite electrode plate with a large internal surface area and a low polarization resistance and producing an electrode plate made according to the process.
Process for the Production of an Electrode for a Fused Carbonate Fuel Cell, Electrode Produced According to this Process and Fused Carbonate Fuel Cell Provided With an Electrode Produced According to this Process The invention relates to a process for making an electrode for a carbonate melt fuel cell, an electrode made according to the process, and a carbonate melt fuel cell with an electrode made by the process.
The production of cathodes for carbonate melt fuel cells from lithium cobaltite (LiCoO~ is known. For making such cathodes, lithium cobaltite powder is mixed with a binder. A
dispersant can be added to the binder. A foil is made from the mixture which is divided into plates. The plates are sintered at high temperatures in an air-carbon dioxide atmosphere.
Lithium cobaltite is made by reacting cobalt with lithium compounds (EP 0 473 236 A2).
Making lithium cobaltite by reacting cobalt oxide (iron oxide) with lithium hydroxide vapor as a powder in a high-temperature reaction is also known. This powder is made into brittle electrode plates with small dimensions by a ceramic sintering process (JP
0636, 770).
Finally, making a lithium cobaltite layer from a ductile cobalt layer whose pores are filled with lithium carbonate is known. Conversion to the lithium cobaltite layer is preferably done after combination with a matrix layer and an anode layer and after installation together with current collector plates in a cell holder of a fuel cell during the start-up phase of the fuel cell.
The structure of the lithium cobaltite electrode plate made in this way corresponds to the structure of the original porous cobalt electrode plate which has a relatively high polarization resistance (DE 43 03 136 Cl).
The invention is based on the problem of creating a process for producing a porous lithium cobaltite electrode plate with a large internal surface area and a low polarization resistance and producing an electrode plate made according to the process.
The problem is solved for the process according to the invention by mixing cobalt metal powder and lithium carbonate powder with each other homogenously then producing foils from the mixture and plates from the foils, said plates being sintered into porous electrode precursor plates, then exposing the electrode precursor plates to an air flow for several hours at a temperature of between 400°C and 488°C, until the electrode precursor plates have been converted into lithium cobaltite electrode plates with extremely large internal surface areas. In the process according to the invention, a lithium cobaltite formation reaction that determines the structure takes several hours. Initially, cobalt in the porous cobalt/lithium carbonate precursor electrode plate is oxidized in the atmosphere of air. Then lithium cobaltite and lithium oxide are formed at the points where cobalt oxide contacts lithium carbonate, releasing carbon dioxide which is carried away with the air current. Because of its high vapor pressure, lithium oxide changes to the gas phase in which it reacts with cobalt oxide that has not contacted lithium carbonate to form lithium cobaltite.
While the lithium cobalt is being formed, it is preferable to keep the temperature at 420°C to 480°C. It has been shown that in this temperature range the above-described reactions take place under favorable conditions, influenced by atmospheric oxygen.
In particular, the quantity of air admitted and the air flowrate are adjusted such that the carbon dioxide level in the air is no higher than approximately 1 % and the air is allowed to act for approximately 10 hours. Under these conditions, an electrode consisting of lithium cobaltite with a very large internal surface area of 2 to 6 mZ/g is obtained, that no longer contains any lithium carbonate.
The reactions that take place in the above-described process during the various phases are described in detail below:
Mechanism of Solid-Gas Reaction (400°C-488°C) Oxidation of cobalt:
Co+ 3 Oz--~ 3 Solid reaction at cobalt oxide/lithium carbonate contact points:
j CU3~4 + L12CO3 + I2 O2 ~ LiCoO2.+ Cp2 + 1 Li-,.O
(solid) LizOtr°S~> -~ Li20ts~>
Gas diffusion of Li20ig~~:
Li20~s~~ (reaction location 1 ) -~ diffusion ~ Li20~g~~ (reaction location 2) Gas-solid reaction at reaction location 2:
_1 _1 a) 3 Co304 + LlzOis~i + 12 02 ..-~ LiCo02 When the carbon dioxide component of the air is small, not exceeding a value of I%, an electrode consisting of lithium cobaltite with a very large internal surface area of 2-6 m2/g is obtained, which no longer has any LizC03 after ten hours. The structure formed during this combined oxidation/activation process is retained when the electrode is used in a carbonate melt fuel cell.
Li20 diffusion into oxidized CO particles that have not contacted Li2C03 particles is not hindered by increasing the COZ level of the air since LiZC03 forms from the Li20 and COZ
once again. Consequently the rate of LiCo02 formation decreases with a rising COa level in the air and the desired fine structure with a large internal surface area cannot form.
While the lithium cobalt is being formed, it is preferable to keep the temperature at 420°C to 480°C. It has been shown that in this temperature range the above-described reactions take place under favorable conditions, influenced by atmospheric oxygen.
In particular, the quantity of air admitted and the air flowrate are adjusted such that the carbon dioxide level in the air is no higher than approximately 1 % and the air is allowed to act for approximately 10 hours. Under these conditions, an electrode consisting of lithium cobaltite with a very large internal surface area of 2 to 6 mZ/g is obtained, that no longer contains any lithium carbonate.
The reactions that take place in the above-described process during the various phases are described in detail below:
Mechanism of Solid-Gas Reaction (400°C-488°C) Oxidation of cobalt:
Co+ 3 Oz--~ 3 Solid reaction at cobalt oxide/lithium carbonate contact points:
j CU3~4 + L12CO3 + I2 O2 ~ LiCoO2.+ Cp2 + 1 Li-,.O
(solid) LizOtr°S~> -~ Li20ts~>
Gas diffusion of Li20ig~~:
Li20~s~~ (reaction location 1 ) -~ diffusion ~ Li20~g~~ (reaction location 2) Gas-solid reaction at reaction location 2:
_1 _1 a) 3 Co304 + LlzOis~i + 12 02 ..-~ LiCo02 When the carbon dioxide component of the air is small, not exceeding a value of I%, an electrode consisting of lithium cobaltite with a very large internal surface area of 2-6 m2/g is obtained, which no longer has any LizC03 after ten hours. The structure formed during this combined oxidation/activation process is retained when the electrode is used in a carbonate melt fuel cell.
Li20 diffusion into oxidized CO particles that have not contacted Li2C03 particles is not hindered by increasing the COZ level of the air since LiZC03 forms from the Li20 and COZ
once again. Consequently the rate of LiCo02 formation decreases with a rising COa level in the air and the desired fine structure with a large internal surface area cannot form.
When moist air is used with vapor levels of over 2%, the activation process for forming a larger internal surface area of over 2 m2/g can also be carried out with COz levels of over I%
in the activation gas atmosphere. In this case, LiCo02 is formed by reacting oxidized cobalt with lithium hydroxide according to the following mechanism.
LiCoO~ formation in the presence of water vapor:
Li2C03 + H20ts~ -.~ 2LiOHtg~ + COZ
Li20ts,s~ + H20tsI --~ 2LiOH~s~
m~.s~a~~
LIOHts~, (Reaction location 1) "~-~ LiOI-I(s~ (Reaction location 2) 3 Co3O4 + LiOHIts> + I Z 02 --~ LiCo02 + ~ HZOts>
When the vapor Ieve1 is raised to over 2%, the reaction is not accelerated further.
The process according to the invention can be carried out after the electrode precursor plates have been placed in an oven under the conditions described above, removing the lithium cobaltite electrodes after the oven has cooled and assembling them with a matrix layer saturated with the molten electrolyte and an anode as well as with current collectors to form a fuel cell. , It is also favorable to combine the electrode precursor plate in question with a matrix layer filled with carbonate melt into a layer arrangement corresponding to the fuel cell and then to build it into a fuel cell together with the latter, and carry out the process according to the invention after installation in the fuel cell. Under the conditions of the process according to the invention, the lithium cobaltite cathode is formed during a fuel cell start-up procedure.
The lithium cobaltite can also be produced as a thin, adhesive layer,on a porous nickel substrate, which thus becomes oxidized.
The example below will further illustrate the invention - ~ CA 02244969 1998-07-31 S
Embodiment Example Fine cobalt powder with a particle size of less than 3 ~c and Li2C03 powder with a particle size of between 1 ~ and 10 ~c, as starting components, are processed into a viscous slurry in a proportion of 66 wt.% CO and 34 wt.% Li2C03 with addition of an organic binder dissolved in a nonaqueous solvent, a softener, and other organic additives, and said slurry is cast into a foil by the tape casting process. Plates are made from the foil after the drying process and these plates are sintered in a protective gas oven at a temperature below the melting point of LiZC03, preferably at 650°C, for 30 minutes in a reducing atmosphere.
After this procedure the CO and Li2C03 grains are in intimate contact in the electrode precursor plates. After the plates have been sintered, they are cooled at a rate of 200 K per hour to 460°C and, after sufficient flushing with nitrogen, exposed to atmospheric air that is exchanged. At this temperature, complete oxidation of CO occurs within 10 hours and at the same time lithium cobaltite forms from the cobalt oxide and the Li2C03 formed in a solid and gas reaction. The lithium cobaltite electrode thus formed has an extremely large internal surface area, depending on the rate of formation, which is retained after it has been installed in a carbonate melt fuel cell and the latter has been operated. The rate of activation is determined by (i) the carbon dioxide and vapor content and (ii) the cobalt and Li2C03 powder particle size.
An electrode made by the process according to the invention has a structure that is typical of the process with an extremely large internal surface area. Because of this, such a cathode has a very low polarization resistance in a fuel cell and this increases its performance.
in the activation gas atmosphere. In this case, LiCo02 is formed by reacting oxidized cobalt with lithium hydroxide according to the following mechanism.
LiCoO~ formation in the presence of water vapor:
Li2C03 + H20ts~ -.~ 2LiOHtg~ + COZ
Li20ts,s~ + H20tsI --~ 2LiOH~s~
m~.s~a~~
LIOHts~, (Reaction location 1) "~-~ LiOI-I(s~ (Reaction location 2) 3 Co3O4 + LiOHIts> + I Z 02 --~ LiCo02 + ~ HZOts>
When the vapor Ieve1 is raised to over 2%, the reaction is not accelerated further.
The process according to the invention can be carried out after the electrode precursor plates have been placed in an oven under the conditions described above, removing the lithium cobaltite electrodes after the oven has cooled and assembling them with a matrix layer saturated with the molten electrolyte and an anode as well as with current collectors to form a fuel cell. , It is also favorable to combine the electrode precursor plate in question with a matrix layer filled with carbonate melt into a layer arrangement corresponding to the fuel cell and then to build it into a fuel cell together with the latter, and carry out the process according to the invention after installation in the fuel cell. Under the conditions of the process according to the invention, the lithium cobaltite cathode is formed during a fuel cell start-up procedure.
The lithium cobaltite can also be produced as a thin, adhesive layer,on a porous nickel substrate, which thus becomes oxidized.
The example below will further illustrate the invention - ~ CA 02244969 1998-07-31 S
Embodiment Example Fine cobalt powder with a particle size of less than 3 ~c and Li2C03 powder with a particle size of between 1 ~ and 10 ~c, as starting components, are processed into a viscous slurry in a proportion of 66 wt.% CO and 34 wt.% Li2C03 with addition of an organic binder dissolved in a nonaqueous solvent, a softener, and other organic additives, and said slurry is cast into a foil by the tape casting process. Plates are made from the foil after the drying process and these plates are sintered in a protective gas oven at a temperature below the melting point of LiZC03, preferably at 650°C, for 30 minutes in a reducing atmosphere.
After this procedure the CO and Li2C03 grains are in intimate contact in the electrode precursor plates. After the plates have been sintered, they are cooled at a rate of 200 K per hour to 460°C and, after sufficient flushing with nitrogen, exposed to atmospheric air that is exchanged. At this temperature, complete oxidation of CO occurs within 10 hours and at the same time lithium cobaltite forms from the cobalt oxide and the Li2C03 formed in a solid and gas reaction. The lithium cobaltite electrode thus formed has an extremely large internal surface area, depending on the rate of formation, which is retained after it has been installed in a carbonate melt fuel cell and the latter has been operated. The rate of activation is determined by (i) the carbon dioxide and vapor content and (ii) the cobalt and Li2C03 powder particle size.
An electrode made by the process according to the invention has a structure that is typical of the process with an extremely large internal surface area. Because of this, such a cathode has a very low polarization resistance in a fuel cell and this increases its performance.
Claims (7)
1. Process for producing an electrode for a molten carbonate fuel cell, characterized in that cobalt metal powder and lithium carbonate powder are mixed with each other, then foils are made from the mixture and plates are made from the foils, said plates being sintered into electrode precursor plates, and then the electrode precursor plates are exposed to an air flow at a temperature of 400°C to 488°C until the electrode precursor plates have been converted into lithium cobaltite electrode plates with internal surface areas of 2 to 6 m2/g by cobalt oxidation and lithium cobaltite formation.
2. The process according to Claim 1, characterized in that the temperature is between 420°C and 480°C.
3. The process according to Claim 1 or 2, characterized in that the carbon dioxide level of the air is less than 1 %.
4. The process according to Claim 1 or 2, characterized in that the carbon dioxide level of the air is greater than 1 % and the air has a water vapor content of over 2%.
5. The process according to any one of Claims 1 to 4, characterized in that the electrode precursor plates are deposited in layers on a porous nickel substrate and the lithium cobaltite electrode plates are produced as adhesive layers on a nickel oxide substrate formed from the porous nickel substrate exposed to an air flow at a temperature of 400°C to 488°C.
6. The process according to any one of Claims 1 to 5, characterized in that the electrode precursor plates are subjected to cobalt oxidation and lithium cobaltite formation in an oven and each of the lithium cobaltite electrode plates is combined after cooling with a matrix layer filled with a carbonate melt and an anode layer into a layer arrangement corresponding to the fuel cell.
7. The process according to any one of Claims 1 to 4, wherein each of the electrode precursor plates is combined with a matrix layer filled with a molten carbonate and an anode layer into a layer arrangement which is placed in a fuel cell, and wherein a lithium cobaltite cathode plate is produced in the fuel cell in a start-up phase at below the melting point of the LiKCO3 molten electrodes in the fuel cells.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19603918A DE19603918C2 (en) | 1996-02-03 | 1996-02-03 | Process for producing an electrode for a molten carbonate fuel cell and its use |
| DE19603918.5 | 1996-02-03 | ||
| PCT/EP1997/000422 WO1997028571A1 (en) | 1996-02-03 | 1997-01-31 | Process for the production of an electrode for a fused carbonate fuel cell, electrode produced according to this process and fused carbonate fuel cell provided with an electrode produced according to this process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2244969A1 CA2244969A1 (en) | 1997-08-07 |
| CA2244969C true CA2244969C (en) | 2005-12-06 |
Family
ID=35519721
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002244969A Expired - Fee Related CA2244969C (en) | 1996-02-03 | 1997-01-31 | Process for the production of an electrode for a fused carbonate fuel cell, electrode produced according to this process and fused carbonate fuel cell provided with an electrode produced according to this process |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2244969C (en) |
-
1997
- 1997-01-31 CA CA002244969A patent/CA2244969C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2244969A1 (en) | 1997-08-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4663250A (en) | Reduction of electrode dissolution | |
| US5582624A (en) | Process for producing molten-carbonate fuel cells | |
| CA2038408C (en) | Carbonate fuel cell anodes | |
| US5415833A (en) | Method for forming molten carbonate fuel cell anodes | |
| Huang et al. | Study of NiO cathode modified by ZnO additive for MCFC | |
| Böhme et al. | Development of materials and production technologies for molten carbonate fuel cells | |
| CA2244969C (en) | Process for the production of an electrode for a fused carbonate fuel cell, electrode produced according to this process and fused carbonate fuel cell provided with an electrode produced according to this process | |
| US6238619B1 (en) | Process for the production of an electrode for a fused carbonate fuel cell | |
| US4752500A (en) | Process for producing stabilized molten carbonate fuel cell porous anodes | |
| JPH0869804A (en) | Anode for fused carbonate fuel cell and its preparation | |
| US5529856A (en) | Fuel cell having solidified plasma components | |
| US5021303A (en) | Molten carbonate fuel cell start-up process | |
| US6585931B1 (en) | Molten carbonate fuel cell anode and method for manufacturing the same | |
| US8911820B2 (en) | Fabrication method of electrolyte impregnanted cathodes | |
| CN113488632B (en) | Li (lithium ion battery)1-xTMO4-yNy/Li2SO4Coated high-nickel ternary positive electrode material and preparation method thereof | |
| JPH06349499A (en) | Manufacture of electrode for molten carbonate fuel cell | |
| JPH0412591B2 (en) | ||
| JPH0546666B2 (en) | ||
| KR100545826B1 (en) | Manufacturing method of fuel cell | |
| KR100331083B1 (en) | An anode of molten carbonate fuel cell | |
| JPH07105968A (en) | Molten carbonate fuel cell and its manufacture and operating method | |
| KR100188669B1 (en) | Method manufacturing cathode for molten carbonate fuel cell | |
| JP2944097B2 (en) | Molten carbonate fuel cell | |
| CN117457869A (en) | Preparation method and application of carbon-coated sodium iron silicate material | |
| KR100356684B1 (en) | Method for manufacture of cathode in molten carbonate type fuel cell |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 20100201 |