CA1309135C - Redox battery - Google Patents
Redox batteryInfo
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- CA1309135C CA1309135C CA000580967A CA580967A CA1309135C CA 1309135 C CA1309135 C CA 1309135C CA 000580967 A CA000580967 A CA 000580967A CA 580967 A CA580967 A CA 580967A CA 1309135 C CA1309135 C CA 1309135C
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- Prior art keywords
- redox
- electrode
- battery according
- negative electrode
- battery
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
- H01M8/184—Regeneration by electrochemical means
- H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
-
- 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
-
- 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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- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Inert Electrodes (AREA)
- Fuel Cell (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Catalysts (AREA)
Abstract
REDOX BATTERY
Abstract The combination of gold, thallium, lead and bismuth is used as a catalyst in a battery comprised of at least one "redox" cell to accelerate the oxidation of chromous ions to chromic ions and the reduction of chromic ions to chromous ions. The gold, thallium, lead and bismuth catalyst is coated on an electronically conductive, inert electrode which is in the anode fluid of the "redox" cell.
Abstract The combination of gold, thallium, lead and bismuth is used as a catalyst in a battery comprised of at least one "redox" cell to accelerate the oxidation of chromous ions to chromic ions and the reduction of chromic ions to chromous ions. The gold, thallium, lead and bismuth catalyst is coated on an electronically conductive, inert electrode which is in the anode fluid of the "redox" cell.
Description
~3~ 5 REDOX BATTERY
FIEI.D OF INVENTION
-This invention relates to electrochemical cells for storing electrical charges and is directed more particularly to achieving the maximum energy ef-ficiency from reduction-oxidation cells ("redox" cells).
BACKGROU~D OF THE INVE~TIO~
"Redox" batteries function as a bul~ energy storage system of electric energy and have a very higl~ overall energy efficiency as compared to many other systems. The storage of energy takes place through t~le solutions of metal ion pairs at differing states of oxidation. If two such ion pairs, whose "redox" potentials deviate suficiently far from each other, are allowed to react on two different electrodes which are separated from each other by a membrane, then a potential difference is obtained, i.e. electric energy (See, for example, EP-P O 143 300).
"~edox" pairs of the above mentioned kincl are, for example Fe3~/Fe2~ and Cr3+/Cr2+. In cells containing such "redox"
pairs, for example Fe/Cr "redox" cells, the storage o~ power -upon applying the charging voltage - takes place through the following processes:
Fe2~ ~ ~ ~ ~ ~ ~ ~~ Fe3-~ + e~ (Eo = + 0.77 V) and Cr3+ + e~ - - - - - - -> Cr2+ (Eo = - 0.41 V).
The values o the potentials refer to the standard hydrogen elec-trode. At the positive electrode bivalent iron ions are oxidized while at the negative electrode trivalent chromium ions are ~-r ,5~' reduced. On reversing these processes - reduction of trivalent iron ions (Fe3~) at the positive electrode and oxidation of biva-lent chromium ions (Cr2~) at the negative electrode - the stored electric energy i5 again freed and the discharge voltage can be tapped at the electrodes. Since the discharge voltage of a single cell is generally too low for tec~mical applications, several "redox" cells are always electrically connected in series by wtlich "redox" batteries result.
"Redox" cells generally are operated with acidic elec-trolyte solutions, for example Wittl solutions of iron chloride or chromium chloride in hydrochloric acid. The electrochemical re-actions take place at electrodes whictl are inert to the particular electrolyte solutions, i.e. cathode fluid (catholyte) or anode fluid ~anolyte). Coal or graphite, which are inert to the anode and cathode fluids, generally serve as electrode material. (See, for example U5P 3 996 06~ and USP 4 382 116).
The "redox" reaction oE the iron in "redox" cells nor-mally does not present any problems. It takes place particularly ?
when graphite materials are used, at a sufficient rate and Wittl a current yield of nearly 100%. In contrast, the "redox" reaction oE the chromium presents problems since it is not catalyzed to a sufficiently great extent by graphite. For that reason, previous attempts have been made to activate the graphite electrodes for the chromium reaction.
A suitable measure for activating the chromium electrode is by coating with metals. For example, gold catalyzes the .
- , :
.
:~3~`~3~ 2o365-2863 oxidation of bivalent chromium and the reduction of trivalent chromium so that a sufficient reaction speed can be achieved for the discharge reaction as well as for the charge reaction.
However~ the hydrogen overvoltage on gold is less than on graphite. Therefore, during the charging process in this case, as a side reaction of the reduction of the trivalent chromium, an undesirable hydrogen formation, occurs. Thus, the current yield of the charging process for the chromium electrolyte is markedly below 100%. As a consequence, the charging state of the chromium solution with each cycle remains further behind the charging state of the iron solution.
The difference between the charging state of the chromium solu-tion and that of the iron solution must be balanced externally with a special cell. (See, for example: M.A. Reid and L.H. Thaller "Improvement and Scale-up of the NASA Redox Storage System", DOE/NASA/12726-6 ~SA T~~81632, 1981). The concepts developed until now for such a "rebalance cell," however, use up energ~ so that the energy efficiency of the "redox" system is diminished. The hig~ler the rate of hydrogen development at the chromium electrode and, hence, the required power of the rebalance cell, the lower the energy efficiency of the energy storage system.
A further problem arises in this connection with respect to the material balance. The hydrogen formed as a byproduct in the chromium reduction represents a substance loss which, in the interest of a long operating life of the total system, must be compensated for in order to permit a closed cycle.
In order to decrease the hydrogen formation, attempts have been made to use a second catalyst besides gold. Known for this purpose are lead and cadmium (See, for example USP 4 192 910 and USP 4 270 984) as well as thallium (5ee, EP-P 0 137 990).
However, when applied in practice, the hydrogen overvoltage is also insufficient to suppress the hydrogen development to a suffi-cient extent.
It is the object of the invention to implement a battery of "redox" cells of the aforementioned type with a - 3a -, :' ' ~ ' :
.
. ':' ' '. ~ , ' .
13~35 20365-2863 catalyst for accelerating Cr3 /Cr2 "redox" processes in such a way tha~ the current yield of the "redox" reaction of the chromium is optimized and, hence, maximum possible energy efficiency is achieved for the overall system.
SUMMARY OF THE TNVE~TIO~
In accordance with the present invention, the combination of gold, thallium, lead and bismuth is used as a catalyst for the oxidatlon of chromous ions to chromic ions in a "redox" cell. It is also used as a catalyst for the reduction of chromic ions to chromous ions in a "redox" cell. The gold, thalllum, lead and bismuth catalyst is coated on an inert, electrically conductive electrode of the "redox" cell With the Au/Tl/Pb/~i combination catalyst, efficient ~atalysis of the reaction at the chromium electrode is achleved.
This y.telds a serles of signifiaant advantages for the "redox"
system. The hydrogen development ls largely suppressed, and thereby a dearease of the inequilibrium of the charging state of the two energy carriers is brought about. In addition, a decreased substance loss occurs which leads to correspondingly low maintenance of the battery. Further, a potentially avallable rebalance cell requires less power, which effec~s energy consumption and the investment costs of the peripheral installation. Moreover, the catalyst according to the invention entrain~ an increase o~ the current density which corresponds to an improvement of the power density~and likewise leads to savings : , .
in lnvestment.
In accordance with a broad aspect of the invention there is provided a battery comprising:
at least one "redox" cell, each cell having first and second chambers separated by a membrane;
a positive electrode disposed in the first chamber;
a negative electrode disposed in the second chamber;
a catholyte fluid in said flrst chamber, said positive electrode being inert to the catholyte fluid; and an anolyte fluid in said second chamber, said negative electrode belng inert to the anolyte fluid;
said negative electrode containing a combination of gold (Au), thallium (Tl), lead (Pb), and bismuth (Bi) as a catalyst for the acceleration of Cr3 /Cr2 "redox" processes.
BRIEF DESCRIPTION OF _E DRAWINGS
Figure 1 is a graph illustratlng the rate of hydrogen formation as a funation of the charging state as carried out with the catalyst of the invention with respect to the 4a ... . ~ , . ' - ~ . ~ -' ' ~3~35 20365-28~3 catalysts of the prior art on an electrode comprised of fluoro-plastic-bound finely flocculent material of natural graphite.
FIG. 2 is a graph showing the rate of hydrogen ~ormation as a function of the charging state as carried out with the cata-lyst of the invention with respect to the catalysts of the prior art on an electrode comprised of fluoroplastic-bound coarsely flocculent material of natural graphite.
DESCRIPTIO~ OF A PREF~RRED EMBODIMENT
In a preferred embodiment of the "redox" battery accord-ing to the invention, the negative electrode has a catalytic coat-ing of gold, thallium, lead, and bismuth. This coating can be generated directly onto the negative electrode, for example, through impregnation with aqueous solutions of corresponding metal salts. Preferentially, however, the metals are applied on the negative electrode in suc~ a manner so that the anolyte, i.e; the chromium electrolyte, contains salts of gold, thallium, lead, and bismuth. During charging, under reducing conditions, the corres-ponding metals are then deposited, in accordance with their posi-tion in the electrochemical voltage series on the negative elec-trode (chromium electrode).
The concentration of the metal salts in the anolyte areselected such, that on the negative electrode under the precondi-tion that 100% deposition takes place; the following surface den-sities, in each instance relative to 1 cm2, are formed: 0.02 to 1 mg Au, 0.2 to 40 mg Tl, 0.2 to 10 mg Pb, and 0.2 to 10 mg Bi.
These values represent, independently of the kind and manner of "~
- ':
~3~9~35 20365-2863 application of the metals on the electrode surface, the preferred ranges of surface densities. It is particularly advantageous if the negative electrode has approximately the following surface densities: 0.2 mg/cm2 ~u, 8 mg/cm2 Tl, 2 mg/cm2 Pb, and 2 mg/cm2 Bi.
In "redox" cells or "redox" batteries, the electrolyte fluid generally is aqueous hydrochloric acid, preferably 3 molar hydrochloric acid. If metal salts are added to the anolyte, these are, therefore preferentially metal chlorides. In particular, the following compounds serve as chlorides: AUC13, TlC13, PbC12, and BiC13. AUC13 can also be present in the form of HAuC14 and TlCl can also be used instead of TlC13.
The electrode materials used in the "redox" battery according to the invention are in particular, carbon and graphite, which can be utilizecl in the form of felt. It is preferable that the negative and positive electrodes consist of plastic-bound graphite. The positive electrode is preferably an iron electrode, i.e. an electrode on whic~l Fe3~/Fe2+ "redox" processes take place.
The positive electrode may also be a manganese or vanadium elec-trode as well as a bromium electrode. If the "redox" batteryaccording to the invention is a Fe/Cr battery, that is if it has as its positive electrode an iron electrode and as its negative electrode a chromium electrode, then the particular electrolyte fluid contains preferably iron chloride or chromium chloride in an aqueous HCl solution. The catholyte fluid is preferably 1 M
FeC12/3M HCl, and the anolyte fluid is preferably 1 M CrC13/3M
........ .
. ' . ' . ~ . :
:
, ~ ~ ~ g 13 5 20365-2863 HCl. The positive and negative electrodes are inert to the ano-lyte and catholy~e fluids and the corresponding electrode chambers (and hence also the catholyte and anolyte) are separated from each other by an ion exchange membrane.
In conjunction with the embodiment e~amples and figures, the invention will be explained in yet grea-ter detail.
EXAMPLES
The following negative electrodes were examined for the chromium reaction, in each instance with an electrode surface of 5 cm2:
1. An Au/Tl/Pb/Bi electrode according to the invention with 0.2 mg/cm2 Au, 8 mg/cm2 Tl, 2mg/cm2 Pb, and 2 mg/cm2 Bi (electrode l); and 2. An AutPb electrode corresponding to prior ar-t (See, ~or e~amp]e, USP 4 192 910 or EP-P 0 020 66~) with 0.2 mg/cm2 Au and 2 mg/cm2 Pb (electrode 2); and 3. An Au/Tl electrode corresponding to prior art (See EP-P 0 137 990) with 0.2 mg/cm2 Au and 8 mg/cm2 Tl (electrode 3);
and 4. A Pb/Bi electrode with 2 mg/cm2 Pb and 2 mg/cm2 Bi as comparison (electrode 4).
The electrode material used in each case was graphite bound with plastic material. The catalyst material was applied on the electrode in such a manner that appropriate quantities of metal chloride were added to the electrolyte fluid, i.e. to the anolyte. l M CrC13/3M HCl served as anolyte. Approximately the .~., .
', . . ' ' ~3~9~3S 20365-2863 same results are obtained if 1 M CrC13/1 M FeC12/3 M HCl is used as the electrolyte fluid.
The electrochemical investigations of the above mention-ed electrodes took place initially with the delta voltage method which permits rapid overview of the quality of electrode or cata-lyst materials. It was found that the achievable current densi-ties, for the Cr3+ reduction as well as for the Cr2+ oxidation, were greatest for electrode 1. The other three investigated elec-trodes yielded significantly lower current densities for the "redox" reaction of the chromium.
The most important criterion for the quality of a cata-lyst for the chromium reaction is the proportion of hydrogen development to the reduction current. For this purpose, the elec-trodes were arranged in a flow apparatus and a constant current was applied, and the rate of hydrogen development in the reduction of Cr3~ to Cr2~ was determined through volumetric determination of the generated quantity of gas. The quantity of gas here was de-pendent of the charging state of the chromium electrolyte: at a lower charging state, that is at a high concentration ratio of Cr3+: Cr2+, no hydrogen formation takes place and at a higher charging state, gas formation starts.
The obtained test results can be found in Figures 1 and 2 (numerals 1, 2, 3, and 4 apply to the electrodes with the corre-sponding number). For the above four described electrodes, the rate of hydrogen formation (given as a percentage of the total current flow) is graphically represented as a function o~ the ,~
- : . ' ': ........... , , charging state (the charging s-tate was calculated with a calibra-tion curve over the resting potential of the measuring electrode).
The flow rate of the electrolyte (1 M CrC13/1 M FeC12/3 M HCl) on the electrode surface was 250 ml/minute in each case. The current density in each instance was 40 mA/cm2, i.e. the current was 200 mA.
In Figures 1 and 2, it can be seen that electrode 1, the electrode with an ~u~Tl/Pb/Bi combina~ion catalyst has by far the lowest rate of hydrogen formation. It was far superior to the known Au/Pb and Au/Tl electrodes (and also to a Pb/Bi electrode).
This applied to a chromium and iron-containing electrolyte as well as to an electrolyte containing only chromium ions for the influ-ence of iron ions on the reduction of chromium ions was apparently very weak. The electrode material also exerted, at least as far as electrode 1 is concerned, no decisive effects. The electrodes according to Figure 1 were based on fluoroplastic-bound finely flocculent material of natural graphite, and the electrodes accor-ding to Figure 2 were based on a fluoroplastic-bound coarsely flocculent material of natural graphite, (plastic binding agent:
polyvinylidene Eluoride).
Investigations of the different electrodes further show-ed that with the Au/Tl/Pb/Bi catalyst, especially at high charging states, higher reduction currents could be realized than with the customary catalysts. The invention also showed improved current density, for the discharging process, which meant greater area-related power of the battery. Therefore, in order to achieve the ~ _ g _ ~3~9~3~ 20365-2863 same power, the electrode surface could, consequently, be reduced.
For example, the "redox" bat-tery according to the invention could, at the same power, be of smaller size than other batteries.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claim.
,.~
,~
",, . ~ , - . .
FIEI.D OF INVENTION
-This invention relates to electrochemical cells for storing electrical charges and is directed more particularly to achieving the maximum energy ef-ficiency from reduction-oxidation cells ("redox" cells).
BACKGROU~D OF THE INVE~TIO~
"Redox" batteries function as a bul~ energy storage system of electric energy and have a very higl~ overall energy efficiency as compared to many other systems. The storage of energy takes place through t~le solutions of metal ion pairs at differing states of oxidation. If two such ion pairs, whose "redox" potentials deviate suficiently far from each other, are allowed to react on two different electrodes which are separated from each other by a membrane, then a potential difference is obtained, i.e. electric energy (See, for example, EP-P O 143 300).
"~edox" pairs of the above mentioned kincl are, for example Fe3~/Fe2~ and Cr3+/Cr2+. In cells containing such "redox"
pairs, for example Fe/Cr "redox" cells, the storage o~ power -upon applying the charging voltage - takes place through the following processes:
Fe2~ ~ ~ ~ ~ ~ ~ ~~ Fe3-~ + e~ (Eo = + 0.77 V) and Cr3+ + e~ - - - - - - -> Cr2+ (Eo = - 0.41 V).
The values o the potentials refer to the standard hydrogen elec-trode. At the positive electrode bivalent iron ions are oxidized while at the negative electrode trivalent chromium ions are ~-r ,5~' reduced. On reversing these processes - reduction of trivalent iron ions (Fe3~) at the positive electrode and oxidation of biva-lent chromium ions (Cr2~) at the negative electrode - the stored electric energy i5 again freed and the discharge voltage can be tapped at the electrodes. Since the discharge voltage of a single cell is generally too low for tec~mical applications, several "redox" cells are always electrically connected in series by wtlich "redox" batteries result.
"Redox" cells generally are operated with acidic elec-trolyte solutions, for example Wittl solutions of iron chloride or chromium chloride in hydrochloric acid. The electrochemical re-actions take place at electrodes whictl are inert to the particular electrolyte solutions, i.e. cathode fluid (catholyte) or anode fluid ~anolyte). Coal or graphite, which are inert to the anode and cathode fluids, generally serve as electrode material. (See, for example U5P 3 996 06~ and USP 4 382 116).
The "redox" reaction oE the iron in "redox" cells nor-mally does not present any problems. It takes place particularly ?
when graphite materials are used, at a sufficient rate and Wittl a current yield of nearly 100%. In contrast, the "redox" reaction oE the chromium presents problems since it is not catalyzed to a sufficiently great extent by graphite. For that reason, previous attempts have been made to activate the graphite electrodes for the chromium reaction.
A suitable measure for activating the chromium electrode is by coating with metals. For example, gold catalyzes the .
- , :
.
:~3~`~3~ 2o365-2863 oxidation of bivalent chromium and the reduction of trivalent chromium so that a sufficient reaction speed can be achieved for the discharge reaction as well as for the charge reaction.
However~ the hydrogen overvoltage on gold is less than on graphite. Therefore, during the charging process in this case, as a side reaction of the reduction of the trivalent chromium, an undesirable hydrogen formation, occurs. Thus, the current yield of the charging process for the chromium electrolyte is markedly below 100%. As a consequence, the charging state of the chromium solution with each cycle remains further behind the charging state of the iron solution.
The difference between the charging state of the chromium solu-tion and that of the iron solution must be balanced externally with a special cell. (See, for example: M.A. Reid and L.H. Thaller "Improvement and Scale-up of the NASA Redox Storage System", DOE/NASA/12726-6 ~SA T~~81632, 1981). The concepts developed until now for such a "rebalance cell," however, use up energ~ so that the energy efficiency of the "redox" system is diminished. The hig~ler the rate of hydrogen development at the chromium electrode and, hence, the required power of the rebalance cell, the lower the energy efficiency of the energy storage system.
A further problem arises in this connection with respect to the material balance. The hydrogen formed as a byproduct in the chromium reduction represents a substance loss which, in the interest of a long operating life of the total system, must be compensated for in order to permit a closed cycle.
In order to decrease the hydrogen formation, attempts have been made to use a second catalyst besides gold. Known for this purpose are lead and cadmium (See, for example USP 4 192 910 and USP 4 270 984) as well as thallium (5ee, EP-P 0 137 990).
However, when applied in practice, the hydrogen overvoltage is also insufficient to suppress the hydrogen development to a suffi-cient extent.
It is the object of the invention to implement a battery of "redox" cells of the aforementioned type with a - 3a -, :' ' ~ ' :
.
. ':' ' '. ~ , ' .
13~35 20365-2863 catalyst for accelerating Cr3 /Cr2 "redox" processes in such a way tha~ the current yield of the "redox" reaction of the chromium is optimized and, hence, maximum possible energy efficiency is achieved for the overall system.
SUMMARY OF THE TNVE~TIO~
In accordance with the present invention, the combination of gold, thallium, lead and bismuth is used as a catalyst for the oxidatlon of chromous ions to chromic ions in a "redox" cell. It is also used as a catalyst for the reduction of chromic ions to chromous ions in a "redox" cell. The gold, thalllum, lead and bismuth catalyst is coated on an inert, electrically conductive electrode of the "redox" cell With the Au/Tl/Pb/~i combination catalyst, efficient ~atalysis of the reaction at the chromium electrode is achleved.
This y.telds a serles of signifiaant advantages for the "redox"
system. The hydrogen development ls largely suppressed, and thereby a dearease of the inequilibrium of the charging state of the two energy carriers is brought about. In addition, a decreased substance loss occurs which leads to correspondingly low maintenance of the battery. Further, a potentially avallable rebalance cell requires less power, which effec~s energy consumption and the investment costs of the peripheral installation. Moreover, the catalyst according to the invention entrain~ an increase o~ the current density which corresponds to an improvement of the power density~and likewise leads to savings : , .
in lnvestment.
In accordance with a broad aspect of the invention there is provided a battery comprising:
at least one "redox" cell, each cell having first and second chambers separated by a membrane;
a positive electrode disposed in the first chamber;
a negative electrode disposed in the second chamber;
a catholyte fluid in said flrst chamber, said positive electrode being inert to the catholyte fluid; and an anolyte fluid in said second chamber, said negative electrode belng inert to the anolyte fluid;
said negative electrode containing a combination of gold (Au), thallium (Tl), lead (Pb), and bismuth (Bi) as a catalyst for the acceleration of Cr3 /Cr2 "redox" processes.
BRIEF DESCRIPTION OF _E DRAWINGS
Figure 1 is a graph illustratlng the rate of hydrogen formation as a funation of the charging state as carried out with the catalyst of the invention with respect to the 4a ... . ~ , . ' - ~ . ~ -' ' ~3~35 20365-28~3 catalysts of the prior art on an electrode comprised of fluoro-plastic-bound finely flocculent material of natural graphite.
FIG. 2 is a graph showing the rate of hydrogen ~ormation as a function of the charging state as carried out with the cata-lyst of the invention with respect to the catalysts of the prior art on an electrode comprised of fluoroplastic-bound coarsely flocculent material of natural graphite.
DESCRIPTIO~ OF A PREF~RRED EMBODIMENT
In a preferred embodiment of the "redox" battery accord-ing to the invention, the negative electrode has a catalytic coat-ing of gold, thallium, lead, and bismuth. This coating can be generated directly onto the negative electrode, for example, through impregnation with aqueous solutions of corresponding metal salts. Preferentially, however, the metals are applied on the negative electrode in suc~ a manner so that the anolyte, i.e; the chromium electrolyte, contains salts of gold, thallium, lead, and bismuth. During charging, under reducing conditions, the corres-ponding metals are then deposited, in accordance with their posi-tion in the electrochemical voltage series on the negative elec-trode (chromium electrode).
The concentration of the metal salts in the anolyte areselected such, that on the negative electrode under the precondi-tion that 100% deposition takes place; the following surface den-sities, in each instance relative to 1 cm2, are formed: 0.02 to 1 mg Au, 0.2 to 40 mg Tl, 0.2 to 10 mg Pb, and 0.2 to 10 mg Bi.
These values represent, independently of the kind and manner of "~
- ':
~3~9~35 20365-2863 application of the metals on the electrode surface, the preferred ranges of surface densities. It is particularly advantageous if the negative electrode has approximately the following surface densities: 0.2 mg/cm2 ~u, 8 mg/cm2 Tl, 2 mg/cm2 Pb, and 2 mg/cm2 Bi.
In "redox" cells or "redox" batteries, the electrolyte fluid generally is aqueous hydrochloric acid, preferably 3 molar hydrochloric acid. If metal salts are added to the anolyte, these are, therefore preferentially metal chlorides. In particular, the following compounds serve as chlorides: AUC13, TlC13, PbC12, and BiC13. AUC13 can also be present in the form of HAuC14 and TlCl can also be used instead of TlC13.
The electrode materials used in the "redox" battery according to the invention are in particular, carbon and graphite, which can be utilizecl in the form of felt. It is preferable that the negative and positive electrodes consist of plastic-bound graphite. The positive electrode is preferably an iron electrode, i.e. an electrode on whic~l Fe3~/Fe2+ "redox" processes take place.
The positive electrode may also be a manganese or vanadium elec-trode as well as a bromium electrode. If the "redox" batteryaccording to the invention is a Fe/Cr battery, that is if it has as its positive electrode an iron electrode and as its negative electrode a chromium electrode, then the particular electrolyte fluid contains preferably iron chloride or chromium chloride in an aqueous HCl solution. The catholyte fluid is preferably 1 M
FeC12/3M HCl, and the anolyte fluid is preferably 1 M CrC13/3M
........ .
. ' . ' . ~ . :
:
, ~ ~ ~ g 13 5 20365-2863 HCl. The positive and negative electrodes are inert to the ano-lyte and catholy~e fluids and the corresponding electrode chambers (and hence also the catholyte and anolyte) are separated from each other by an ion exchange membrane.
In conjunction with the embodiment e~amples and figures, the invention will be explained in yet grea-ter detail.
EXAMPLES
The following negative electrodes were examined for the chromium reaction, in each instance with an electrode surface of 5 cm2:
1. An Au/Tl/Pb/Bi electrode according to the invention with 0.2 mg/cm2 Au, 8 mg/cm2 Tl, 2mg/cm2 Pb, and 2 mg/cm2 Bi (electrode l); and 2. An AutPb electrode corresponding to prior ar-t (See, ~or e~amp]e, USP 4 192 910 or EP-P 0 020 66~) with 0.2 mg/cm2 Au and 2 mg/cm2 Pb (electrode 2); and 3. An Au/Tl electrode corresponding to prior art (See EP-P 0 137 990) with 0.2 mg/cm2 Au and 8 mg/cm2 Tl (electrode 3);
and 4. A Pb/Bi electrode with 2 mg/cm2 Pb and 2 mg/cm2 Bi as comparison (electrode 4).
The electrode material used in each case was graphite bound with plastic material. The catalyst material was applied on the electrode in such a manner that appropriate quantities of metal chloride were added to the electrolyte fluid, i.e. to the anolyte. l M CrC13/3M HCl served as anolyte. Approximately the .~., .
', . . ' ' ~3~9~3S 20365-2863 same results are obtained if 1 M CrC13/1 M FeC12/3 M HCl is used as the electrolyte fluid.
The electrochemical investigations of the above mention-ed electrodes took place initially with the delta voltage method which permits rapid overview of the quality of electrode or cata-lyst materials. It was found that the achievable current densi-ties, for the Cr3+ reduction as well as for the Cr2+ oxidation, were greatest for electrode 1. The other three investigated elec-trodes yielded significantly lower current densities for the "redox" reaction of the chromium.
The most important criterion for the quality of a cata-lyst for the chromium reaction is the proportion of hydrogen development to the reduction current. For this purpose, the elec-trodes were arranged in a flow apparatus and a constant current was applied, and the rate of hydrogen development in the reduction of Cr3~ to Cr2~ was determined through volumetric determination of the generated quantity of gas. The quantity of gas here was de-pendent of the charging state of the chromium electrolyte: at a lower charging state, that is at a high concentration ratio of Cr3+: Cr2+, no hydrogen formation takes place and at a higher charging state, gas formation starts.
The obtained test results can be found in Figures 1 and 2 (numerals 1, 2, 3, and 4 apply to the electrodes with the corre-sponding number). For the above four described electrodes, the rate of hydrogen formation (given as a percentage of the total current flow) is graphically represented as a function o~ the ,~
- : . ' ': ........... , , charging state (the charging s-tate was calculated with a calibra-tion curve over the resting potential of the measuring electrode).
The flow rate of the electrolyte (1 M CrC13/1 M FeC12/3 M HCl) on the electrode surface was 250 ml/minute in each case. The current density in each instance was 40 mA/cm2, i.e. the current was 200 mA.
In Figures 1 and 2, it can be seen that electrode 1, the electrode with an ~u~Tl/Pb/Bi combina~ion catalyst has by far the lowest rate of hydrogen formation. It was far superior to the known Au/Pb and Au/Tl electrodes (and also to a Pb/Bi electrode).
This applied to a chromium and iron-containing electrolyte as well as to an electrolyte containing only chromium ions for the influ-ence of iron ions on the reduction of chromium ions was apparently very weak. The electrode material also exerted, at least as far as electrode 1 is concerned, no decisive effects. The electrodes according to Figure 1 were based on fluoroplastic-bound finely flocculent material of natural graphite, and the electrodes accor-ding to Figure 2 were based on a fluoroplastic-bound coarsely flocculent material of natural graphite, (plastic binding agent:
polyvinylidene Eluoride).
Investigations of the different electrodes further show-ed that with the Au/Tl/Pb/Bi catalyst, especially at high charging states, higher reduction currents could be realized than with the customary catalysts. The invention also showed improved current density, for the discharging process, which meant greater area-related power of the battery. Therefore, in order to achieve the ~ _ g _ ~3~9~3~ 20365-2863 same power, the electrode surface could, consequently, be reduced.
For example, the "redox" bat-tery according to the invention could, at the same power, be of smaller size than other batteries.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claim.
,.~
,~
",, . ~ , - . .
Claims (11)
1. A battery comprising:
at least one "redox" cell, each cell having first and second chambers separated by a membrane;
a positive electrode disposed in the first chamber;
a negative electrode disposed in the second chamber;
a catholyte fluid in said first chamber, said positive electrode being inert to the catholyte fluid; and an anolyte fluid in said second chamber, said negative electrode being inert to the anolyte fluid;
said negative electrode containing a combination of gold (Au), thallium (T1), lead (Pb), and bismuth (Bi) as a catalyst for the acceleration of Cr3+/Cr2+ "redox" processes.
at least one "redox" cell, each cell having first and second chambers separated by a membrane;
a positive electrode disposed in the first chamber;
a negative electrode disposed in the second chamber;
a catholyte fluid in said first chamber, said positive electrode being inert to the catholyte fluid; and an anolyte fluid in said second chamber, said negative electrode being inert to the anolyte fluid;
said negative electrode containing a combination of gold (Au), thallium (T1), lead (Pb), and bismuth (Bi) as a catalyst for the acceleration of Cr3+/Cr2+ "redox" processes.
2. The battery according to Claim 1 wherein the combination of gold, thallium, lead and bismuth is coated on said negative electrode.
3. The battery according to Claim 2, wherein said negative electrode has a surface concentration of 0.02 to 1 mg Au, 0.2 to 40 mg T1, 0.2 to 10 mg Pb, and 0.2 to 10 mg Bi, in each instance relative to one centimeter square.
4. The battery according to Claim 3, wherein said negative electrode has the following surface concentrations: Au about 0.2 mg/cm2, T1 about 8 mg/cm2, Pb about 2 mg/cm2, and Bi about 2 mg/cm2.
5. The battery according to Claim 1 wherein the battery is comprised of a series of "redox" cells.
6. The battery according to Claim 1, wherein the anolyte fluid contains salts of gold, thallium, lead, and bismuth.
7. The battery according to Claim 6, wherein the anolyte fluid contains metal chlorides.
8. The battery according to Claim 1, wherein said negative electrode consists of plastic-bound graphite.
9. The battery according to Claim 1, wherein said negative electrode is an inert, electrically conductive electrode on which Cr3+/Cr2+ "redox" processes take place.
10. The battery according to Claim 1, wherein said positive electrode is an inert, electrically conductive electrode on which Fe3+/Fe2+, "redox" processes take place.
11. The battery according to Claim 1 wherein said positive electrode consists of plastic-bound graphite.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3735992 | 1987-10-23 | ||
| DEP3735992.4 | 1987-10-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1309135C true CA1309135C (en) | 1992-10-20 |
Family
ID=6338977
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000580967A Expired - Lifetime CA1309135C (en) | 1987-10-23 | 1988-10-21 | Redox battery |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4882241A (en) |
| EP (1) | EP0312875B1 (en) |
| JP (1) | JPH01143152A (en) |
| CA (1) | CA1309135C (en) |
| DE (1) | DE3869547D1 (en) |
| ES (1) | ES2029707T3 (en) |
| GR (1) | GR3004755T3 (en) |
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| US7855005B2 (en) * | 2007-02-12 | 2010-12-21 | Deeya Energy, Inc. | Apparatus and methods of determination of state of charge in a redox flow battery |
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| CN102246338B (en) * | 2008-10-10 | 2014-06-11 | 迪亚能源股份有限公司 | Thermal control of a flow cell battery |
| US8230736B2 (en) * | 2008-10-10 | 2012-07-31 | Deeya Energy, Inc. | Level sensor for conductive liquids |
| US20100092843A1 (en) * | 2008-10-10 | 2010-04-15 | Deeya Energy Technologies, Inc. | Venturi pumping system in a hydrogen gas circulation of a flow battery |
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| US20110079074A1 (en) * | 2009-05-28 | 2011-04-07 | Saroj Kumar Sahu | Hydrogen chlorine level detector |
| CN102460812B (en) * | 2009-05-28 | 2014-12-31 | 艾默吉电力系统股份有限公司 | Preparation of flow battery electrolytes from raw materials |
| EP2436080A2 (en) * | 2009-05-28 | 2012-04-04 | Deeya Energy, Inc. | Electrolyte compositions |
| US8587255B2 (en) * | 2009-05-28 | 2013-11-19 | Deeya Energy, Inc. | Control system for a flow cell battery |
| CN102460811B (en) * | 2009-05-28 | 2015-11-25 | 艾默吉电力系统股份有限公司 | Redox flow cell rebalancing |
| US8349477B2 (en) * | 2009-05-28 | 2013-01-08 | Deeya Energy, Inc. | Optical leak detection sensor |
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| US9281535B2 (en) | 2010-08-12 | 2016-03-08 | Imergy Power Systems, Inc. | System dongle |
| JP2014503946A (en) * | 2010-12-10 | 2014-02-13 | 中国科学院大▲連▼化学物理研究所 | Application of porous membrane and its composite membrane in redox flow battery |
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| JP2014532284A (en) * | 2011-10-14 | 2014-12-04 | ディーヤ エナジー，インコーポレーテッド | Vanadium flow cell |
| WO2013131838A1 (en) | 2012-03-05 | 2013-09-12 | Eos Holding Sa | Redox flow battery for hydrogen generation |
| US20130316199A1 (en) * | 2012-05-25 | 2013-11-28 | Deeya Energy, Inc. | Electrochemical balance in a vanadium flow battery |
| WO2014060886A1 (en) * | 2012-10-17 | 2014-04-24 | Ramot At Tel Aviv University Ltd | Super hybrid capacitor |
| US8980454B2 (en) * | 2013-03-15 | 2015-03-17 | Enervault Corporation | Systems and methods for rebalancing redox flow battery electrolytes |
| DE102013217882A1 (en) | 2013-09-06 | 2015-03-12 | Sgl Carbon Se | Electrode substrate made of carbon fibers |
| CN107210468B (en) | 2015-04-08 | 2021-02-12 | 株式会社Lg化学 | Polymer electrolyte membrane, electrochemical cell and flow battery, preparation method of polymer electrolyte membrane and flow battery electrolyte |
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| CN115632132B (en) * | 2022-10-25 | 2023-10-24 | 辽宁金谷炭材料股份有限公司 | Preparation method of composite electrode of iron-chromium flow battery |
| CN121506976A (en) * | 2025-11-19 | 2026-02-10 | 中海储能科技(北京)有限公司 | A gradient pulse electroplating catalytic electrode for iron-chromium redox flow batteries, its preparation method, and its application. |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2070648A1 (en) * | 1969-10-27 | 1971-09-17 | Usm Corp | Redox fuel element |
| US3996064A (en) * | 1975-08-22 | 1976-12-07 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Electrically rechargeable REDOX flow cell |
| US4192910A (en) * | 1978-11-29 | 1980-03-11 | Nasa | Catalyst surfaces for the chromous/chromic redox couple |
| US4270984A (en) * | 1978-11-29 | 1981-06-02 | Nasa | Catalyst surfaces for the chromous/chromic REDOX couple |
| US4382116A (en) * | 1981-05-22 | 1983-05-03 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Zirconium carbide as an electrocatalyst for the chromous/chromic REDOX couple |
| DE3333650C2 (en) * | 1983-09-17 | 1985-09-26 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München | Electrochemical redox cell |
| DE3338724A1 (en) * | 1983-10-25 | 1985-05-02 | Siemens AG, 1000 Berlin und 8000 München | REDOX CELL BATTERY |
| US4543302A (en) * | 1984-08-20 | 1985-09-24 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Negative electrode catalyst for the iron chromium REDOX energy storage system |
-
1988
- 1988-10-10 ES ES198888116793T patent/ES2029707T3/en not_active Expired - Lifetime
- 1988-10-10 DE DE8888116793T patent/DE3869547D1/en not_active Expired - Lifetime
- 1988-10-10 EP EP88116793A patent/EP0312875B1/en not_active Expired - Lifetime
- 1988-10-19 JP JP63265237A patent/JPH01143152A/en active Pending
- 1988-10-19 US US07/259,924 patent/US4882241A/en not_active Expired - Fee Related
- 1988-10-21 CA CA000580967A patent/CA1309135C/en not_active Expired - Lifetime
-
1992
- 1992-05-29 GR GR920400496T patent/GR3004755T3/el unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE3869547D1 (en) | 1992-04-30 |
| GR3004755T3 (en) | 1993-04-28 |
| JPH01143152A (en) | 1989-06-05 |
| US4882241A (en) | 1989-11-21 |
| EP0312875A1 (en) | 1989-04-26 |
| EP0312875B1 (en) | 1992-03-25 |
| ES2029707T3 (en) | 1992-09-01 |
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