AU725835B2 - Fuel cell with pulsed anode potential - Google Patents
Fuel cell with pulsed anode potential Download PDFInfo
- Publication number
- AU725835B2 AU725835B2 AU70343/98A AU7034398A AU725835B2 AU 725835 B2 AU725835 B2 AU 725835B2 AU 70343/98 A AU70343/98 A AU 70343/98A AU 7034398 A AU7034398 A AU 7034398A AU 725835 B2 AU725835 B2 AU 725835B2
- Authority
- AU
- Australia
- Prior art keywords
- anode
- fuel cell
- carbon monoxide
- fuel
- catalyst
- 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.)
- Ceased
Links
Classifications
-
- 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
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
- H01M8/04238—Depolarisation
-
- 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
- H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
-
- 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
Abstract
The invention concerns a fuel cell (1) comprising an electrode-electrolyte unit (2, 3, 4) with an anode catalyst whose catalytic activity in a fuel cell is reduced by carbon monoxide and with means (5, 6) for varying the anode potential in pulsed manner such that carbon monoxide which has been adsorbed on the catalyst is oxidized. In this way, power losses owing to carbon monoxide adsorption at the anode catalyst are reduced.
Description
WO 98/42038 PCT/EP98/01436 Description FUEL CELL WITH PULSED ANODE POTENTIAL The invention concerns a fuel cell.
A fuel cell has a cathode, an electrolyte and an anode. The cathode is supplied with an oxidizing agent, for example air, and the anode is supplied with a fuel, for example hydrogen.
There are fuel cells in which the electrolyte comprises a proton-conducting membrane. The operating temperature of such fuel cells is up to 1300 C. In the presence of the fuel, hydrogen ions form at the anode by means of a catalyst. The hydrogen ions pass the electrolyte and bond on the cathode side with the oxygen ions originating from reduction of oxygen to form water. Electrons are thereby released and consequently electrical energy is generated.
During the operation of fuel cells, which comprise for example noble metal catalysts such as Pt as the active component of the electrodes, even very low concentrations of carbon monoxide in the fuel 50 ppm) lead to a reduction in the power of the cell, because active catalyst locations are occupied by adsorbed carbon monoxide and are blocked. This problem occurs particularly badly in the case of fuel cells which have a polymeric solid electrolyte.
REPLACEMENT SHEET (RULE 26) 2 Methanol is frequently provided as the energytransmission medium for fuel cells with polymeric solid electrolytes and is converted in a reforming reaction with water into a hydrogen-rich synthesis gas. This synthesis gas contains about 1% carbon monoxide. The relatively high proportion of CO in the synthesis gas leads to a drastic deactivation of the electrocatalyst of the anode of the fuel cell and reduces the power of the fuel cell.
The deactivation of the catalysts likewise occurs when using a combustion gas, which is produced by reforming alcohols, hydrocarbons and mixtures of hydrocarbons. The reforming of the energy-transmission medium may take place externally or internally, as described in the publication reviewing fuel cell technology by U. St imming, VDI Berichte No. 1174, (1995). it is also known that a reduction in the power of fuel cells due to deactivation of the anode catalysts also occurs in the case of direct methanol conversion at the anode of the fuel cell due to the production of CO.
For avoiding the aforementioned deactivation of toeo catalysts, it is known to reduce the CO content of the fuels below 100 ppm by gas cleaning. However, secondary cleaning oe ~is complex and consequently costly.
to It is also known to develop anode catalysts with improved CO resistance, such as Pt-Ru alloys for example.
Such catalysts are, however, likewise very expensive.
Adsorption effects, and associated power losses, can also be reduced only unsatisfactory.
It is known from the publication by S. Gottesfeld and J. Pafford, J. Electrochem. Soc. 135 (1988) 2651, to avoid deactivations caused by adsorbed carbon monoxide by adding low concentrations of oxygen or air to the fuel. A disadvantage of this solution is that ignitable mixtures may occur.
The object of the invention is to provide a fuel cell in which power losses caused by contaminants adsorbed at the anode catalyst can be avoided inexpensively and reliably.
The present invention provides a fuel cell having an anode-electrolyte-cathode unit, having an anode catalyst and having means for impressing a positive voltage pulse on the anode, wherein the voltage of the fuel cell does not change its sign and at most becomes zero.
The present invention further provides a method for the removal of carbon monoxide on anode catalysts of fuel cells, wherein a or repeated positive voltage pulse(s) are impressed on the anode, wherein the voltage of the fuel cell does not change its sign and at most becomes zero.
The improvement in the power is achieved by oxidation of the carbon monoxide adsorbed at the catalyst by eo ~means of the pulsed variation of the anode potential. The ooo magnitude of the voltage of the voltage pulse is consequently to be chosen during operation such that carbon monoxide adsorbed at the anode catalyst is oxidized.
-4- To produce a suitable positive voltage pulse, means which produce a temporary short circuit between the anode and cathode are provided for example. Alternatively, means which bring about a pulsed feeding in of external electrical energy, which is supplied to the anode, are provided. In both cases, short current or voltage pulses are produced and impressed on the anode in the way claimed. The pulse may in principle be of any desired shape. The variant first described, with the short circuit, has the advantage over the feeding in of external energy that there is no need for an external energy source.
For the pulsed variation of the anode potential, a control device for a suitable, fast transistor switch is used, for example. The transistor switch either briefly shorts the contaminated fuel cell for a defined time or changes the anode potential to positive values, in that an external DC voltage source of about 1 V a battery), applied via the switch, is impressed on the cell for a defined time.
The coupling in of the current or voltage pulses has the effect that contaminants adsorbed on the anode catalyst are oxidized and, as a consequence, the cell is reactivated. Since the reactivation takes place considerably faster than the deactivation, an average increase in power is the consequence in the case of fuel with carbon monoxide fractions. This applies in particular when catalysts with improved CO resistance, such as Pt-Ru alloys, are used.
Preferred time periods for the pulses are 10 to 200 milliseconds. The electric currents are generally several A/cm 2 up to 10 A/cm 2 If a fuel cell is operated under constant load, repetition rates of 0.01 0.5 Hz are to be preferred. In cases of load changes, a corresponding variation of the repetition times of the pulses is expedient.
The power losses of a fuel cell caused by the operation of an electronic device for generating the voltage or current pulses, that is the power losses caused by the interruption in the removal of energy during the time period of a pulse as well as the power losses caused by the energy expended for the pulse are at most 1 5% of the power ~generated by the cell.
0A preferred embodiment of the invention will now be described with reference to the accompanying drawings; Figure 1 shows a fuel cell 1, an anode 2, an electrolyte layer 3 and a cathode 4. A signal generator 5 is provided as a control device. The signal generator oeo• controls a fast high-power transistor switch, to be precise a S: transistor MOSFET 6 for generating voltage pulses 7. The 0oo* transistor MOSFET 6 is electrically connected to the anode 2, so that a pulsed variation of the anode potential is produced. The variation is such that carbon monoxide adsorbed at the anode catalyst can be oxidized.
Figure 2 shows the variation in electric current I at an anode plotted against time t, as produced according to the invention in a fuel cell. A carbon-supported Pt/Ru alloy catalyst was used at a potential of 200 mV with H 2 CO gas mixtures being supplied. By periodic coupling in of potentiostatic pulses with an amplitude of 700 mV and a pulse duration of 100 ms at a repetition rate of 0.1 Hz, a current can be continuously maintained. The coupled-in pulse brings about a potential of 900 mV with respect to hydrogen potential in a step-change manner. Such a step potential is sufficient for bringing about the desired oxidation of the adsorbed carbon monoxide. In the present example, the current is at least 50 pA for longer than one hour. Such a continuous oxidation current at the anode of the fuel cell permits constant operation and a considerable increase in power of the cell in comparison with operation without the coupling in of pulses.
Claims (5)
- 2. A method for the removal of carbon monoxide on anode catalysts of fuel cells, wherein a or repeated positive voltage pulse(s) are impressed on the anode, wherein the voltage of the fuel cell does not change its sign and at most becomes zero
- 3. The method as claimed in claim 2, wherein reformed alcohols are used as fuel.
- 4. The method as claimed in claim 2, wherein reformed S• hydrocarbons are used as fuel. The method as claimed in claim 3, wherein the reforming of the alcohols takes place internally in the fuel cell.
- 6. The method as claimed in claim 4, wherein the to.* reforming of the hydrocarbons takes place internally in the fuel cell. S7. The method as claimed in claim 2, wherein a direct O conversion of alcohols takes place at the anode.
- 8. The method as claimed in claim 2, wherein a direct conversion of hydrocarbons takes place at the anode.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19710819 | 1997-03-15 | ||
DE19710819A DE19710819C1 (en) | 1997-03-15 | 1997-03-15 | Fuel cell with anode-electrolyte-cathode unit |
PCT/EP1998/001436 WO1998042038A1 (en) | 1997-03-15 | 1998-03-12 | Fuel cell with pulsed anode potential |
Publications (2)
Publication Number | Publication Date |
---|---|
AU7034398A AU7034398A (en) | 1998-10-12 |
AU725835B2 true AU725835B2 (en) | 2000-10-19 |
Family
ID=7823504
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU70343/98A Ceased AU725835B2 (en) | 1997-03-15 | 1998-03-12 | Fuel cell with pulsed anode potential |
Country Status (10)
Country | Link |
---|---|
EP (1) | EP0968541B1 (en) |
JP (1) | JP2002514345A (en) |
AT (1) | ATE207248T1 (en) |
AU (1) | AU725835B2 (en) |
CA (1) | CA2284589A1 (en) |
DE (2) | DE19710819C1 (en) |
DK (1) | DK0968541T3 (en) |
ES (1) | ES2162438T3 (en) |
PT (1) | PT968541E (en) |
WO (1) | WO1998042038A1 (en) |
Families Citing this family (26)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6063516A (en) * | 1997-10-24 | 2000-05-16 | General Motors Corporation | Method of monitoring CO concentrations in hydrogen feed to a PEM fuel cell |
US6387556B1 (en) | 1997-11-20 | 2002-05-14 | Avista Laboratories, Inc. | Fuel cell power systems and methods of controlling a fuel cell power system |
US6472090B1 (en) | 1999-06-25 | 2002-10-29 | Ballard Power Systems Inc. | Method and apparatus for operating an electrochemical fuel cell with periodic reactant starvation |
US6329089B1 (en) | 1997-12-23 | 2001-12-11 | Ballard Power Systems Inc. | Method and apparatus for increasing the temperature of a fuel cell |
US6312846B1 (en) | 1999-11-24 | 2001-11-06 | Integrated Fuel Cell Technologies, Inc. | Fuel cell and power chip technology |
US6428918B1 (en) | 2000-04-07 | 2002-08-06 | Avista Laboratories, Inc. | Fuel cell power systems, direct current voltage converters, fuel cell power generation methods, power conditioning methods and direct current power conditioning methods |
WO2001080340A1 (en) * | 2000-04-14 | 2001-10-25 | Vodafone Ag | Circuit for generating voltage pulses and impressing voltage pulses upon a fuel cell and fuel cell system |
US20020028362A1 (en) * | 2000-09-01 | 2002-03-07 | Dennis Prediger | Anode oxidation protection in a high-temperature fuel cell |
DE10053851A1 (en) * | 2000-10-30 | 2002-05-08 | Siemens Ag | Process for the regeneration of CO poisoning in HT-PEM fuel cells |
DE10063456B4 (en) * | 2000-12-20 | 2005-04-21 | Robert Bosch Gmbh | fuel cell unit |
DE10203827C2 (en) * | 2002-01-31 | 2003-12-18 | P21 Power For The 21St Century | PCB arrangement and electrical component |
AU2003210939A1 (en) * | 2002-02-06 | 2003-09-02 | Battelle Memorial Institute | Polymer electrolyte membrane fuel cell system |
WO2003067696A2 (en) | 2002-02-06 | 2003-08-14 | Battelle Memorial Institute | Methods of removing contaminants from a fuel cell electrode |
EP1512189A2 (en) * | 2002-03-29 | 2005-03-09 | Estco Battery Management, Inc. | Fuel cell operating control system |
EP1620937A1 (en) * | 2003-04-29 | 2006-02-01 | NuCellSys GmbH | Power converter architecture and method for integrated fuel cell based power supplies |
US20040217732A1 (en) | 2003-04-29 | 2004-11-04 | Ballard Power Systems Inc. | Power converter architecture and method for integrated fuel cell based power supplies |
US7419734B2 (en) | 2003-05-16 | 2008-09-02 | Ballard Power Systems, Inc. | Method and apparatus for fuel cell systems |
US20060210852A1 (en) * | 2003-07-25 | 2006-09-21 | Ravindra Datta | Electrochemical preferential oxidation of carbon monoxide from reformate |
US7474078B2 (en) * | 2003-12-19 | 2009-01-06 | Texaco Inc. | Cell maintenance device for fuel cell stacks |
US7521138B2 (en) | 2004-05-07 | 2009-04-21 | Ballard Power Systems Inc. | Apparatus and method for hybrid power module systems |
DE102005012617B4 (en) * | 2005-03-18 | 2006-12-14 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Device and method for heating a fuel cell or a fuel cell stack |
HK1130951A1 (en) * | 2006-03-02 | 2010-01-08 | Encite Llc | Power cell architectures and control of power generator arrays |
US9819037B2 (en) | 2006-03-02 | 2017-11-14 | Encite Llc | Method and apparatus for cleaning catalyst of a power cell |
DE102006061225A1 (en) * | 2006-12-20 | 2008-06-26 | Forschungszentrum Jülich GmbH | Method for activation of fuel cell, particularly direct methanol fuel cell, involves operating fuel cell during galvanic operation for short time, fully or partially in electrolysis mode |
RU2330353C1 (en) * | 2007-02-13 | 2008-07-27 | Анатолий Иванович Мамаев | Ai mamaev's method of converting chemical energy to electrical energy and device for implementing method |
DE102008018941B4 (en) * | 2008-04-15 | 2020-08-06 | Sunfire Gmbh | Device having a fuel cell stack with an oxygen pump |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62128458A (en) * | 1985-11-28 | 1987-06-10 | Shin Kobe Electric Mach Co Ltd | Fuel concentration control for liquid fuel cell |
US4795537A (en) * | 1987-04-10 | 1989-01-03 | H.P.G. Research Ltd. | Electrical conditioning system for electrodes in an electrolysis cell |
GB9412073D0 (en) * | 1994-06-16 | 1994-08-03 | British Gas Plc | Method of operating a fuel cell |
JP3564742B2 (en) * | 1994-07-13 | 2004-09-15 | トヨタ自動車株式会社 | Fuel cell power generator |
-
1997
- 1997-03-15 DE DE19710819A patent/DE19710819C1/en not_active Expired - Fee Related
-
1998
- 1998-03-12 DK DK98916927T patent/DK0968541T3/en active
- 1998-03-12 JP JP54011498A patent/JP2002514345A/en active Pending
- 1998-03-12 PT PT98916927T patent/PT968541E/en unknown
- 1998-03-12 AT AT98916927T patent/ATE207248T1/en not_active IP Right Cessation
- 1998-03-12 EP EP98916927A patent/EP0968541B1/en not_active Expired - Lifetime
- 1998-03-12 WO PCT/EP1998/001436 patent/WO1998042038A1/en active IP Right Grant
- 1998-03-12 AU AU70343/98A patent/AU725835B2/en not_active Ceased
- 1998-03-12 ES ES98916927T patent/ES2162438T3/en not_active Expired - Lifetime
- 1998-03-12 CA CA002284589A patent/CA2284589A1/en not_active Abandoned
- 1998-03-12 DE DE59801774T patent/DE59801774D1/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
PUL.-POT.OXID.OF METH.FEDKIW P S ET AL,J.OF ELECTRO.SOCIETY * |
Also Published As
Publication number | Publication date |
---|---|
DK0968541T3 (en) | 2001-11-19 |
PT968541E (en) | 2002-04-29 |
ATE207248T1 (en) | 2001-11-15 |
JP2002514345A (en) | 2002-05-14 |
DE19710819C1 (en) | 1998-04-02 |
WO1998042038A1 (en) | 1998-09-24 |
ES2162438T3 (en) | 2001-12-16 |
EP0968541B1 (en) | 2001-10-17 |
DE59801774D1 (en) | 2001-11-22 |
EP0968541A1 (en) | 2000-01-05 |
AU7034398A (en) | 1998-10-12 |
CA2284589A1 (en) | 1998-09-24 |
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Legal Events
Date | Code | Title | Description |
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PC1 | Assignment before grant (sect. 113) |
Free format text: MANNESMANN AG |
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FGA | Letters patent sealed or granted (standard patent) |