WO1989005528A1 - Vanadium charging cell and vanadium dual battery system - Google Patents

Vanadium charging cell and vanadium dual battery system Download PDF

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Publication number
WO1989005528A1
WO1989005528A1 PCT/AU1988/000473 AU8800473W WO8905528A1 WO 1989005528 A1 WO1989005528 A1 WO 1989005528A1 AU 8800473 W AU8800473 W AU 8800473W WO 8905528 A1 WO8905528 A1 WO 8905528A1
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WIPO (PCT)
Prior art keywords
charge
discharge
electrode
positive
negative
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PCT/AU1988/000473
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French (fr)
Inventor
Maria Skyllas-Kazacos
Michael Kazacos
Rodney John Charles Mcdermott
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Unisearch Limited
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Publication of WO1989005528A1 publication Critical patent/WO1989005528A1/en

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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L50/00—Electric propulsion with power supplied within the vehicle
    • B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
    • B60L50/60—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries
    • B60L50/64—Constructional details of batteries specially adapted for electric vehicles
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • 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
    • H01M2300/00—Electrolytes
    • H01M2300/0002—Aqueous electrolytes
    • H01M2300/0005—Acid electrolytes
    • 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
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04186—Arrangements for control of reactant parameters, e.g. pressure or concentration of liquid-charged or electrolyte-charged reactants
    • H01M8/04194—Concentration measuring 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
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/16—Information or communication technologies improving the operation of electric vehicles

Definitions

  • This invention relates to an all-vanadium redox charge cell and an all-vanadium redox dual battery system.
  • This problem can be alleviated to some extent by avoiding overcharge and restricting the battery charging to up to about 90% state-of-charge.
  • V0 2+ + 0 2 - VO 2 + e
  • An object of this invention is to provide an all-vanadium redox charge cell and an all-vanadium redox dual battery system.
  • an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge eTectrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge
  • the positive and negative charge electrodes can be any shape desired. It is preferred that the positive and negative charge electrodes are rectangular-plate shaped.
  • the positive and negative charge electrodes are chosen from electrode materials which are stable in the charge catholyte and charge anolyte respectively in the potential ranges in which the respective charge reactions occur.
  • the negative charge electrode has a higher hydrogen overvoltage than copper to minimise H 2 evolution during the charging reaction at the positive charge electrode.
  • Low H 2 evolution during charging means low volume water loss from the cell electrolyte, low risk of H 2 explosion and high coulombic charging efficiency at the negative charge electrode.
  • the negative charge electrode can be selected from the group consisting of TI; Bi; Pb; Hg; In; Cd; Ag; Ga; Sb; Zn; Pb/Hg; Pb/Bi ; Hg/In; Hg/Cd; Hg/Ga; Hg/Ag; carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; and cellulose (most of the metallic materials could not be used to discharge the negative half-cell because they will corrode or passivate at the discharge potentials).
  • the open circuit potential of the negative charge cell is about -0.4V vs SHE. It is preferable to select the negative charge electrode from electrode materials which are stable to corrosion at the open circuit potential.
  • the inventor has found surprisingly that many materials are unsuitable for use as a positive charge electrode and they have also found unpredictably that a number of materials which are suitable for use as the positive charge electrode can be selected from the group consisting of DSA, platinised Ti ; platinised Ru; platinised Ir; and V 2 0s coated on Pb, Ti , Zr, Hf, Ta, W or Nb.
  • the V 2 0 s coated electrodes would be unsuitable for the positive half-cell in a discharging battery as it would dissolve at the discharge potential range.
  • a DSA electrode would perform well for both charging and discharging but it is an expensive electrode material and the lifetime of DSA electrodes is limited as has been found by cycling experiments.
  • the charge cell of the invention includes monopolar and bipolar type charge cells.
  • a bipolar charge cell typically includes a plurality of positive charge compartments each having a positive charge electrode therein and a plurality of negative charge compartments each having a negative charge electrode therein and wherein each of the compartments are separated by a membrane.
  • a bipolar charge cell is typically of the flat plate- or filter press-type.
  • the charge cell can include a charge anolyte reservoir for storing charge anolyte operatively coupled to the negative charge compartment by charge anolyte supply and return lines via a pump and a charge catholyte reservoir for storing charge catholyte operatively coupled to the positive charge compartment by charge catholyte supply and return lines via a pump.
  • the charge cell can include a charge anolyte charge reservoir having charge anolyte charge supply and return line or lines for charging further charge anolyte which is to be delivered to the negative charge compartment and a charge catholyte charge reservoir having charge catholyte charge supply and return line or lines for charging further charge catholyte which is to be delivered to the positive charge compartment an charge anolyte storage reservoir having charge anolyte storage supply and return line or lines for storing charge anolyte from the negative charge compartment and a charge catholyte storage reservoir having charge catholyte storage supply and return line or lines for storing charge catholyte from the positive charge compartment and pumping means operatively coupled to the charge anolyte storage line or lines and/or the charge anolyte charge line or lines and to the charge catholyte storage line or lines and/or the charge catholyte charge line or lines for pumping:
  • a process for charging a charge anolyte and a charge catholyte of an all-vanadium redox charge cell having: a negative charge compartment containing a charge anolyte and having a negative charge electrode for charging said charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment containing a charge catholyte and having a positive charge electrode for charging said charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during
  • an all-vanadium redox dual battery system comprising: an all-vanadium redox discharge cell having a negative discharge compartment having a negative charge electrode for discharging a discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a positive charge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionicaTly conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte ; and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is
  • a process for producing electricity from a charged all-vanadium discharge cell of an all-vanadium redox dual battery system comprising: an all-vanadium redox discharge cell having a negative discharge compartment containing a discharge anolyte and having a negative discharge electrode for discharging said discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a discharge catholyte and having a positive discharge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte ; and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge
  • the discharge cell can include a discharge anolyte reservoir for storing discharge anolyte operatively coupled to the negative discharge compartment by discharge anolyte supply and return lines via a pump and a discharge catholyte reservoir for storing discharge catholyte operatively coupled to the positive discharge compartment by discharge catholyte supply and return lines via a pump.
  • the discharge cell can include a discharge anolyte discharge reservoir having discharge anolyte discharge supply and return line or lines for charging further discharge anolyte which is to be delivered to the negative discharge compartment and a discharge catholyte discharge reservoir having discharge catholyte discharge supply and return line or lines for charging further discharge catholyte which is to be delivered to the positive discharge compartment a discharge anolyte storage reservoir having discharge anolyte storage supply and return line or lines for storing discharge anolyte from the negative discharge compartment and a discharge catholyte storage reservoir having discharge catholyte storage supply and return line or lines for -n- storing discharge catholyte from the positive discharge compartment and pumping means operatively coupled to the discharge anolyte storage line or lines and/or the discharge anolyte discharge line or lines and to the discharge catholyte storage line or lines and/or the discharge catholyte discharge line or lines for pumping:
  • an all-vanadium redox dual battery composite system comprising: an all-vanadium redox discharge cell having a negative discharge compartment having a negative discharge electrode for discharging a discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a positive discharge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the
  • the positive and negative discharge electrodes can be any shape desired. It is preferred that the positive and negative discharge electrodes are rectangular-plate shaped.
  • a transfer means consist of at least two pipes having at least one pump operatively coupled thereto.
  • the positive and negative discharge electrodes are chosen from electrode materials which are stable in the discharge catholyte and anolyte respectively in the potential ranges in which the respective discharge reactions occur.
  • the open circuit potential of the negative discharge half-cell is about -0.4V vs SHE while the open circuit of the positive discharge half-cell is about +1.0V vs SHE.
  • the positive and negative discharge electrodes can be selected from electrode materials which are stable to corrosion at potentials below 1.0V and above -0.4V vs SHE respectively. Electrode materials which corrode at potentials more positive than about -0.4V vs SHE are unsuitable in this instance.
  • the positive and negative discharge electrodes can be carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; cellulose;
  • the positive and negative discharge electrodes can also be selected from the group consisting of carbon or graphite felt, mat, plate, rod, knit, fibre, or cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene, carbon impregnated polystyrene, carbon impregnated polyvinylchloride and carbon impregnated polyvinylidenechloride, when impregnated with and/or coated with Au, Pt, Ir, Ru, Os, Re, Rh and/or Ag;
  • a dimensionally stabilized anode (DSA - Ti or Ti alloy core, coated at least partially with titanium dioxide which coating is coated in turn with a noble metal coating selected from the group consisting of Pt, Pd, Os, Rh, Ru, Ir and alloys thereof) is a suitable positive discharge electrode.
  • the positive and negative discharge compartments of the discharge cell can be coupled to the positive and negative charge compartments of the charge cell respectively by lines through which catholyte can be transported between positive di charge and charge compartments and anolyte can be transported inter negative discharge and charge compartments.
  • the lines can include pumps and valves as required to transport the catholyte and anolyte.
  • the positive charge and discharge anolytes and the negative charge and discharge catholytes comprise an electrolyte which is typically an aqueous solution which includes H 2 S0 4> trifluoromethanesulphonic acid, Na 2 S0 4 , K 2 S0 4 , H 3 P0 4 , Na 3 P0 4 , K 3 P0 4 , HN0 3 , KN0 3 , NaN0 3 , sulphonic acid, C 6 -C, arylsulphonic acid such as p-toluenesulphonic acid, benzenesulphonic acid, naphthalenesulphonic acid, C ⁇ -C 6 alkylsulphonic acid such as methylsulphonic acid and ethylsulphonic acid, acetic acid or mixtures thereof in a concentration of from 0.01M to 6.0M. It is especially preferred to use H 2 S0 4 in a concentration of from 0.25M to 4.5M, more preferably 0.5M to 4M.
  • the electrolyte typically has vanadium ions in sufficient concentration for high discharge capacity in the discharge cell, for exa ple, 0.25M to 3.5M, preferably 1M to 3M, and more preferably 1.5M to 2.5M are typical in the charge and discharge cells of the invention.
  • the vanadium ions in the electrolyte are prepared by dissolving an oxide, sulphate, phosphate, nitrate, halogenide or other salt or complex of vanadium which is soluble in the electrolyte. It is especially preferable to dissolve vanadyl sulphate in 0.5M to 3.5M H 2 S0 4 or V 2 0 5 or NaV0 3 in 0.5M to 6M H 2 S0 4 by electrolytic dissolution.
  • the electrolyte is typically stirred or agitated preferably with a mechanical stirrer.
  • the charge cell of the invention and the discharge cell are typically cells of the "membrane-type", that is each type of cell employs a membrane rather than a diaphragm to separate a positive compartment from a negative compartment.
  • the membrane employed is typically sheet-like and can transport " electrolyte ions whilst at the same time being hydraulically-impermeable in contrast to a diaphragm (typically asbestos ) which allows restricted electrolyte transfer between compartments.
  • the ionically conducting separator can be a microporous separator or a membrane fabricated from a polymer based on perfluorocarboxylic acids or a proton exchange polymer such as sulphonated polystyrene, sulphonated polyethylene or a substantially fluorinated sulphonic acid polymer such as Nafion (Trade Mark) or membranes of Flemion (Trade Mark) or Sele ion ( Trade Mark) material as manufactured by Asahi Glass Company.
  • Discharging in the discharge cell and charging in the charge cell are typically conducted in sealed air tight cells and can be conducted under an inert atmosphere such as nitrogen, argon, helium or neon or mixtures thereof although an inert atmosphere can be avoided in a sealed system.
  • an inert atmosphere such as nitrogen, argon, helium or neon or mixtures thereof although an inert atmosphere can be avoided in a sealed system.
  • All-vanadium redox charge and discharge cells of the invention can be operated over a broad temperature range, e.g. -5°C to 99°C but are typically operated in the temperature range 15 ⁇ C to 40 ⁇ C.
  • the discharge cell includes monopolar and bipolar type discharge cells.
  • a bipolar discharge cell typically includes a plurality of positive discharge compartments each having a positive discharge electrode therein and a plurality of negative discharge compartments each having a negative discharge electrode therein and wherein each of the compartments are separated by a membrane.
  • a bipolar discharge cell is typically of the flat plate- or filter press-type.
  • Fig. 1 depicts schematically an all-vanadium redox charge cell system
  • Fig. 2 depicts schematically an all-vanadium redox charge cell system which utilizes bipolar electrodes
  • Fig. 3 depicts a bipolar electrode where two different materials are employed for positive and negative electrodes
  • Fig. 4 depicts schematically an a ⁇ T-vanadium redox dual battery system
  • Fig. 5 depicts schematically another all-vanadium redox dual battery system.
  • an all-vanadium redox charge cell 10 has a negative compartment 11 containing a charge anolyte 12 in electrical contact with negative charge electrode 13.
  • Charge anolyte 12 is an electrolyte containing 0.01M to 5.0M H 2 S0 4 and from 0.25M to 3.5M trivalent and/or tetravalent vanadium ions.
  • Cell 10 has a positive charge compartment 14 containing a charge catholyte 15 in electrical contact with positive charge electrode 16.
  • Charge catholyte 15 is an electrolyte containing 0.01M to 5.0M H 2 S0 4 and from 0.25M to 3.5M tetravalent vanadium ions.
  • Cell 10 has an ionically conducting separator 17 disposed between positive and negative charge compartments 14 and 11 and in contact with charge anolyte 12 and charge catholyte 15 to provide ionic communication therebetween.
  • Positive charge electrode 16 is chosen from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir and V 2 0 5 coated on Pb, Ti , Zr, Hf, Ta, W or Nb since electrodes fabricated from any of these materials have been found to be stable in charge catholyte 15 in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at positive charge electrode 16.
  • Negative charge electrode 13 can be selected from the group consisting of TI ; Bi ; Pb; Hg; In; Cd; Ag; Ga; Sb; Zn; Pb/Hg; Pb/Bi ; Hg/In; Hg/Cd; Hg/Ga; Hg/Ag; carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; and cellulose.
  • Negative charge compartment 11 is coupled to charge anolyte charge reservoir 18 by supply line 19 for charging charge anolyte from charge reservoir 18 to negative compartment 11 and to charge anolyte storage reservoir 20 by line 101 which includes pump 102.
  • Positive charge compartment 14 is coupled to charge catholyte charge reservoir 103 by supply line 104 for charging charge catholyte from charge reservoir 103 to positive compartment 14 and to charge catholyte storage reservoir 104 by line 105 which includes pump 106 or recycled to reservoir 103.
  • Negative charge electrode 13 and positive charge electrode 16 are electrically coupled to power source 107 via switch 108.
  • catholyte 15 is pumped by pump 106 into catholyte storage reservoir 104 or returned to catholyte charge reservoir 103 and anolyte 12 is pumped into anolyte storage reservoir 20 by pump 102 or returned to charge anolyte charge reservoir 18 and negative and positive compartments 11 and 14 are refilled and the above process is repeated.
  • the above steps are usually conducted under an inert atmosphere such as nitrogen or the system is sealed from the atmosphere.
  • an alternative all-vanadium redox charge cell 20 has negative charge compartment 21 and bipolar negative charge compartments 22 containing a charge anolyte in electrical contact with negative charge electrode 23 and bipolar negative charge electrodes 24 respectively.
  • Charge cell 20 has positive charge compartment 25 and bipolar positive charge compartments 26 containing a charge catholyte in electrical contact with positive charge electrode 27 and bipolar positive charge electrodes 28 respectively. Compartments 21, 22, 25 and 26 are I'
  • ionically conducting membranes 29 which are preferably Selemion or Nafion membranes.
  • the charge anolyte is an electrolyte containing 0.01M to 5.0M H 2 S0 4 and from 0.25M to 3.5M trivalent and/or tetravalent vanadium ions.
  • the charge catholyte is an electrolyte containing 0.01M to 5.0M H 2 S0 4 and from 0.25M to 3.5M tetravalent vanadium ions.
  • Positive charge electrode 27 and bipolar positive charge electrodes 28 is chosen from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir and V 2 0 5 coated on Pb, Ti , Zr, Hf, Ta, W or Nb. DSA or V 2 0 5 coated on Pb or Ti are particularly preferred positive charge electrode materials.
  • Negative charge electrode 23 and bipolar negative charge electrodes 24 can be selected from the group consisting of TI ; Bi ; Pb; Hg; In; Cd; Ag; Ga; Sb; Zn; Pb/Hg; Pb/Bi ; Hg/In; Hg/Cd; Hg/Ga; Hg/Ag; carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinylidenechloride; glassy carbon; non-woven carbon fibre material; and cellulose.
  • Pb is a particularly preferred negative charge electrode material.
  • Negative charge compartment 21 and bipolar negative charge compartments 22 are coupled to charge anolyte charge reservoir 200 by supply line 201 for charging charge anolyte from charge reservoir 200 to compartments 21 and 22 and by recirculation line 202 which includes pump 203 for pumping charge anolyte from compartments 21 and 22 into reservoir 200.
  • Positive charge compartment 25 and bipolar positive charge compartments 26 are coupled to charge catholyte charge reservoir 204 by supply line 205 for charging charge catholyte from charge reservoir 204 to compartments 25 and 26 and by recirculation line 206 which includes pump 207 for pumping charge catholyte from compartments 25 and 26 into reservoir 204.
  • Negative charge electrode 23 and positive charge electrode 27 are electrically coupled to power source 208 via switch 209.
  • the charge catholyte and the charge anolyte are typically recirculated through compartments 25 and 26 and compartments 21 and 22 respectively.
  • the charge catholyte and anolyte are removed from cell 20 and reservoirs 204 and 200 and discharged discharge catholyte and anolyte are added to reservoirs 204 and 200 respectively and the above process is repeated.
  • the process is conducted under an inert atmosphere such as nitrogen.
  • the process can be conducted under airtight sealed conditions.
  • Fig. 3 depicts a bipolar electrode 30 having a positive charge electrode 31 and a negative charge electrode 32 joined by conductive epoxy 33.
  • Electrode 30 has flow fields 34 which are insulated to prevent electrolyte contacting epoxy 33.
  • electrode 30 can be a Pb negative/DSA positive discharging electrode combination.
  • a Ti sheet can be coated on one side with Ti0 2 /Ru0 2 and on the other side coated with Pb or a thin Pb sheet can be bonded to one side of a Ti sheet with conductive cement/paste and the other side of the Ti sheet coated with Ti0 2 /Ru0 2 .
  • a Pb sheet can be coated on one side with V 2 0 5 film and uncoated on the other side to provide a bipolar electrode having Pb as the negative electrode and V 2 0 5 as the positive electrode.
  • an all-vanadium redox dual battery system includes an all-vanadium redox discharge cell 40 having a negative discharge compartment 41 containing a discharge anolyte in electrical contact with a negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions and a positive discharge compartment 42 containing a discharge catholyte comprising an electrolyte containing pentavalent vanadium ions.
  • An ionically conducting separator 43 is disposed between positive and negative discharge compartments 42 and 41 to provide ionic communication therebetween.
  • the positive and negative discharge electrodes are preferably carbon or graphite felt and the discharge catholyte and the discharge anolyte comprise an electrolyte which is typically 0.5M to 3.5M H 2 S0 4 containing typically 1.5M to 2.5M vanadium ions.
  • the positive discharge electrode is preferably a carbon or graphite felt electrode which is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is preferably a carbon or graphite felt electrode which is stable in the discharge anolyte in the discharge potential range during oxidation of divalent vanadium ions to trivalent vanadium ions at the negative discharge carbon electrode.
  • Negative discharge compartment 41 is operatively coupled to discharge anolyte reservoir 44 by discharge anolyte supply line 45 and return line 46.
  • Return line 46 includes pump 47 which can be used to recirculate discharge anolyte through discharge compartment 41 and anolyte storage compartment 44.
  • Positive discharge compartment 42 is operatively coupled to discharge catholyte reservoir 48 via discharge catholyte supply line 49 and discharge catholyte return line 401 which incorporates pump 402.
  • Pump 402 can be used to recirculate discharge catholyte through discharge compartment 42 and catholyte storage compartment 48.
  • Discharge cell 40 is suitable for use in an electric vehicle where the discharge cell 40 would be installed in the vehicle and after cell 40 has been discharged the discharged discharge catholyte and anolyte could be drained into charge catholyte reservoir 403 and charge anolyte reservoir 404 respectively.
  • Charge catholyte reservoir 403 is operatively coupled to positive charge compartment 408 via charge anolyte supply line 405 and charge anolyte return line 406 which includes pump 407 which can be used to recirculate charge catholyte between charge compartment 408 and reservoir 403.
  • Charge anolyte reservoir 404 is operatively coupled to negative charge compartment 409 via charge catholyte supply line 410 and charge catholyte return line 411 which includes pump 412 which can be used to recirculate charge catholyte between charge compartment 409 and reservoir 404.
  • Positive charge compartment 408 contains a charge catholyte in electrical contact with a positive charge electrode.
  • the charge catholyte typically comprises 0.5M to 3.5M H 2 S0 4 and contains 1.5M to 2.5M tetravalent vanadium ions.
  • Negative charge compartment 409 contains a charged anolyte in electrical contact with a negative charge electrode.
  • the charge anolyte typically comprises 0.5M to 3.5M H 2 S0 having 1.5M to 2.5M trivalent and/or tetravalent vanadium ions.
  • An ionically conducting separator 410 is disposed between compartments 408 and 409 and is in contact with the charge catholyte and the charge anolyte to provide ionic communication therebetween.
  • the positive and negative charge electrodes are chosen from electrode materials which are stable in the charge catholyte and charge anolyte respectively in the potential ranges in which the respective charge reactions occur. Carbon felt and Pb are particularly preferred negative charge electrode materials and DSA and V 2 0 5 on Pb or Ti is a particularly preferred positive charge electrode materials.
  • Compartments 408 and 409 are filled with charge catholyte and charge anolyte respectively from reservoirs 403 and 404 respectively and electrical energy is provided to the positive and negative charge electrodes to derive divalent vanadium ions in the charge anolyte and pentavalent vanadium ions in the charge catholyte.
  • the charge catholyte and charge anolyte are removed from compartments 408 and 409 and ' reservoirs 403 and 404 and placed into positive and negative compartments 42 and 41. Electricity can then be produced from cell 40 by withdrawing electrical energy from cell 40 by loading an external circuit in electronic communication with the positive and negative discharge electrodes. The charging and discharging processes can be repeated.
  • an all-vanadium redox dual battery composite system 50 has an all-vanadium redox discharge cell 51 having a negative discharge compartment 52 containing or adapted to contain a discharge anolyte in electrical contact with a negative discharge electrode.
  • the discharge anolyte is typically 0.25M to 3.5M H 2 S0 4 containing 1.5M to 2.5M divalent vanadium ions.
  • Cell 51 also has a positive discharge compartment 53 containing or adapted to contain a discharge catholyte in electrical contact with a positive discharge electrode.
  • the discharge catholyte typically comprises 0.25M to 3.5M H 2 S0 4 and has 1.5M to 2.5M pentavalent vanadium ions.
  • Ionically conducting separator 54 is disposed between compartments 52 and 53 to provide ionic communication therebetween.
  • the positive discharge electrode and negative discharge electrode are typically carbon or graphite felt electrodes.
  • Syste 50 also includes an all-vanadium redox charge cell 55 having a negative charge compartment 56 containing or adapted to contain a charge anolyte in electrical contact with a negative charge electrode.
  • the charge anolyte particularly comprises 0.25M to 3.5M H 2 S0 4 and contains 1.5M to 2.5M trivalent and/or tetravalent vanadium ions.
  • Positive charge compartment 57 contains or is adapted to contain a charge catholyte in electrical contact with a positive charge electrode.
  • the charge catholyte particularly comprises 0.5M to 3.5M H 2 S0 4 having 1.5M to 2.5M tetravalent vanadium ions.
  • Ionically conducting separator 58 is disposed between compartments 56 and 57 to provide ionic communication therebetween.
  • the positive charge electrode is typically DSA or V 2 0, on Pb or Ti and the negative charge electrode is typically a carbon felt or Pb electrode.
  • System 50 also includes a discharge /charge anolyte reservoir 59 for storing discharge and charge anolyte operatively coupled to negative discharge compartment 52 by discharge anolyte supply line 501 and return line 502 which includes pump 503 and operatively coupled to negative charge compartment 56 by charge anolyte supply line 504 and return line 505 which includes pump 506.
  • System 50 further includes a discharge/charge catholyte reservoir 507 for storing discharge and charge catholyte operatively coupled to positive discharge compartment 53 by discharge catholyte supply line 508 and return line 509 which includes pump 510 and operatively coupled to positive charge compartment 57 by charge catholyte supply line 511 and return line 512 which includes pump 513.
  • a discharge/charge catholyte reservoir 507 for storing discharge and charge catholyte operatively coupled to positive discharge compartment 53 by discharge catholyte supply line 508 and return line 509 which includes pump 510 and operatively coupled to positive charge compartment 57 by charge catholyte supply line 511 and return line 512 which includes pump 513.
  • System 50 includes valves 514 to 517 to enable diversion of the respective catholytes and anolytes to the desired compartments.
  • charge catholyte is charged in positive compartment 57 and charge anolyte is charged in negative compartment 56 and on completion of charging transferred to reservoirs 507 and 59 respectively and positive compartment 53 and negative compartment 52 respectively.
  • Electricity is then produced from cell 51 by withdrawing electrical energy from cell 51 by loading an external circuit in electronic communication with the positive and negative discharge electrodes.
  • the discharged discharge catholyte and anolyte are then retransferred into reservoirs 507 and 59 respectively and compartments 57 and 56 respectively and electrical energy is provided to the positive and negative charge electrodes to derive divalent vanadium ions in the charge anolyte and pentavalent vanadium ions in the charge catholyte.
  • the charging and discharging processes can be repeated.
  • a vanadium redox charging cell employing a lead negative electrode and a DSA positive electrode has been used for over 3 months continuously to charge a V(IV) solution to V(V) and V(III) Solution to V(II) at the positive and negative electrodes respectively.
  • the cell has been alowed to go into overcharge repetitively with generation of 0 2 and H 2 .
  • the electrodes were removed and weighed. Zero weight loss was found for the lead negative and less than 0.01% weight loss found for the positive DSA electrode.
  • An equivalent experiment using graphite plates for the negative and positive electrodes showed weight losses of approximately 1% and 5% respectively, illustrating the dramatic improvement in electrode life with the Pb and DSA electrodes for charging.
  • V 2 0 5 coatings on Ti substrates have been prepared by both spray deposition and by painting on a slurry of the material.
  • Spray deposition was carried out using a 1% solution of ammonium metavanadate in water. The solution was sprayed onto a Ti sheet resting on a hot plank set at about 300°C. As the spray solution comes into contact with the hot substrate, the ammonium metavanadate decomposes forming a thin film of V 2 0s. The procedure is continued until the required film thickness is achieved.
  • Coatings of V 2 0 5 and V 2 0 5 + Sb 2 0 3 mixtures have also been prepared by painting a slurry of the oxide or oxides mixed with water, onto the Ti substrate. The coating is then annealed at 500°C for approximately 2 hours. This results in a uniform, adherent film of V 2 0 5 . 20-30 wt% Sb 2 0 3 is added to increase conductivity of the V 2 0 5 films.
  • V 2 0 s was electrodeposited onto a 15cm x 15cm Pb substrate from a ⁇ .OlM solution of V0S0 4 in 2M H 2 S0 4 .
  • the Pb substrate was connected to the positive terminal of a power supply.
  • a 15cm x 15cm Pb substrate was employed as the negative electrode.
  • a current density of 40mAc ⁇ T 2 was applied for 24 hours resulting in a thin yellow coating of V 2 0 5 on the surface of the positive Pb electrode.
  • the two lead electrodes were then used as electrodes in a vanadium redox cell for charging only. Discharged vanadium solutions were pumped through the cell and charged at a current density of 20mAcm ⁇ 2 .
  • the cell voltage increased from approximately 2.5 volts to 2.7 volts near the end of the charge cycle. When fully charged, the solutions were replaced with uncharged solutions and charging was continued for several days without any deterioration in performance.
  • V 2 0 5 coated lead positive electrode does require a higher voltage than other electrode materials (due to the slight resistance of the V 2 0 s film). However, unlike graphite, it is not subject to degradation and is stable over extended periods of time.
  • an all-vanadium redox charge cell of the invention the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode.

Abstract

An all-vanadium redox charge cell is disclosed. The cell has a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions, a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions, and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte. The positive charge electrode is selected such that it is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is selected such that it is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode. Also disclosed is an all-vanadium redox dual battery system which incorporates the above all-vanadium redox charge cell.

Description

VANADIUM CHARGING CELL AND VANADIUM DUAL BATTERY SYSTEM
TECHNICAL FIELD This invention relates to an all-vanadium redox charge cell and an all-vanadium redox dual battery system.
BACKGROUND ART
The cycle life of an all-vanadium redox flow battery which uses a positive carbon electrode is currently limited by the slow disintegration of the positive carbon or graphite electrode during charging. This disintegration is postulated to be mainly due to the slow side reaction:
C + 2H;0 = C0? + 4H + 4e" which occurs during oxygen evolution as well as the reaction between the carbon surface and evolved oxygen.
This problem can be alleviated to some extent by avoiding overcharge and restricting the battery charging to up to about 90% state-of-charge.
Another cause of the degradation problem has been postulated to be associated with the vanadium charging reactions described by:
V02+ + H20 = VOz + 2H+ + e" and
V02+ + 02- = VO2 + e"
During the oxidation of V (IV) to V (V), oxygen transfer occurs and it has been postulated that oxygen bridging with the electrode substrate is involved. Hence at a carbon electrode it is further postulated that C-0 bonds would be broken at the surface when V (IV) is oxidized to V (V) and this in turn leads to disruption of the carbon surface structure and disintegration.
Although the present inventor have found that stability of the positive carbon electrode can be improved during cycling by addition of stabilizing and/or kinetic enhancing ions to the catholyte disintegration of the positive electrode would still occur if the redox battery were permitted to go into overcharge. OBJECT OF INVENTION
An object of this invention is to provide an all-vanadium redox charge cell and an all-vanadium redox dual battery system.
DISCLOSURE OF INVENTION
In this specification when reference is made to the electrolytes of the all-vanadium redox charge cell the positive and negative electrolytes are referred to as the catholyte and anolyte respectively. This is opposite to normal convention used in electrolytic processes but for convenience and consistency with nomenclature relating to other all-vanadium redox battery patent applications by the present applicant, the former arbitrary convention has been adopted.
According to a first embodiment of this invention there is provided an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge eTectrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode.
The positive and negative charge electrodes can be any shape desired. It is preferred that the positive and negative charge electrodes are rectangular-plate shaped.
The positive and negative charge electrodes are chosen from electrode materials which are stable in the charge catholyte and charge anolyte respectively in the potential ranges in which the respective charge reactions occur.
The negative charge electrode has a higher hydrogen overvoltage than copper to minimise H2 evolution during the charging reaction at the positive charge electrode. Low H2 evolution during charging means low volume water loss from the cell electrolyte, low risk of H2 explosion and high coulombic charging efficiency at the negative charge electrode. The negative charge electrode can be selected from the group consisting of TI; Bi; Pb; Hg; In; Cd; Ag; Ga; Sb; Zn; Pb/Hg; Pb/Bi ; Hg/In; Hg/Cd; Hg/Ga; Hg/Ag; carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; and cellulose (most of the metallic materials could not be used to discharge the negative half-cell because they will corrode or passivate at the discharge potentials). In an all-vanadium redox charge cell in which the charge anolyte comprises 2M trivalent/tetravalent vanadium ions in 2M - 3M H2S0-, and the charge catholyte comprises 2M pentavalent-tetravalent vanadium redox system in 2M - 3M H2S04, the open circuit potential of the negative charge cell is about -0.4V vs SHE. It is preferable to select the negative charge electrode from electrode materials which are stable to corrosion at the open circuit potential. Whilst some of the preceding negative charge electrode materials will dissolve/complex/corrode at open circuit (eg Cd and In) they can still be utilized but in such instances there is a need to continuously apply a suitable negative potential to such materials as they are bought into contact with the anolyte, so that the potential of the materials is more negative than -0.4V vs SHE, thus preventing the materials from corroding.
The inventor has found surprisingly that many materials are unsuitable for use as a positive charge electrode and they have also found unpredictably that a number of materials which are suitable for use as the positive charge electrode can be selected from the group consisting of DSA, platinised Ti ; platinised Ru; platinised Ir; and V20s coated on Pb, Ti , Zr, Hf, Ta, W or Nb. The V20s coated electrodes would be unsuitable for the positive half-cell in a discharging battery as it would dissolve at the discharge potential range. A DSA electrode would perform well for both charging and discharging but it is an expensive electrode material and the lifetime of DSA electrodes is limited as has been found by cycling experiments.
The charge cell of the invention includes monopolar and bipolar type charge cells. A bipolar charge cell typically includes a plurality of positive charge compartments each having a positive charge electrode therein and a plurality of negative charge compartments each having a negative charge electrode therein and wherein each of the compartments are separated by a membrane. A bipolar charge cell is typically of the flat plate- or filter press-type.
The charge cell can include a charge anolyte reservoir for storing charge anolyte operatively coupled to the negative charge compartment by charge anolyte supply and return lines via a pump and a charge catholyte reservoir for storing charge catholyte operatively coupled to the positive charge compartment by charge catholyte supply and return lines via a pump. In an alternative arrangement the charge cell can include a charge anolyte charge reservoir having charge anolyte charge supply and return line or lines for charging further charge anolyte which is to be delivered to the negative charge compartment and a charge catholyte charge reservoir having charge catholyte charge supply and return line or lines for charging further charge catholyte which is to be delivered to the positive charge compartment an charge anolyte storage reservoir having charge anolyte storage supply and return line or lines for storing charge anolyte from the negative charge compartment and a charge catholyte storage reservoir having charge catholyte storage supply and return line or lines for storing charge catholyte from the positive charge compartment and pumping means operatively coupled to the charge anolyte storage line or lines and/or the charge anolyte charge line or lines and to the charge catholyte storage line or lines and/or the charge catholyte charge line or lines for pumping:
(i)the charge catholyte through the charge catholyte storage line or lines, the positive charge compartment and the charge catholyte charge line or lines; and
(ii)the charge anolyte solution through the charge anolyte solution storage line or lines, the negative charge compartment and the charge anolyte solution charge line or lines.
According to a second embodiment of this invention there is provided a process for charging a charge anolyte and a charge catholyte of an all-vanadium redox charge cell having: a negative charge compartment containing a charge anolyte and having a negative charge electrode for charging said charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment containing a charge catholyte and having a positive charge electrode for charging said charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode; which process comprises providing electrical energy to the positive and negative charge electrodes to derive divalent vanadium ions in the charge anolyte and pentavalent vanadium ions in the charge catholyte.
According to a third embodiment of this invention there is provided an all-vanadium redox dual battery system comprising: an all-vanadium redox discharge cell having a negative discharge compartment having a negative charge electrode for discharging a discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a positive charge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionicaTly conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte ; and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the discharge anolyte in the discharge potential range during oxidisation of divalent to vanadium ions at the negative discharge electrode; an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, said charge anolyte comprising discharged discharge anolyte from said discharge cell and containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, said charge catholyte comprising discharged discharge catholyte from said discharge cell and containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode; and transfer means linking said discharge cell with said charge cell to transfer:
(a) discharged discharge anolyte from said discharge cell to the negative charge compartment in said charge cell and to transfer charged charge anolyte from said negative charge compartment to said negative discharge compartment in said discharge cell; and
(b) discharged discharge catholyte from said discharge cell to the positive charge compartment in said charge cell and to transfer charged charge catholyte from said positive charge compartment to said positive discharge compartment in said discharge cell.
According to a fourth embodiment of this invention there is provided a process for producing electricity from a charged all-vanadium discharge cell of an all-vanadium redox dual battery system comprising: an all-vanadium redox discharge cell having a negative discharge compartment containing a discharge anolyte and having a negative discharge electrode for discharging said discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a discharge catholyte and having a positive discharge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte ; and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the discharge anolyte in the discharge potential range during oxidisation of divalent to vanadium ions at the negative discharge electrode; an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, said charge anolyte comprising discharged discharge anolyte from said discharge cell and containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, said charge catholyte .comprising discharged discharge catholyte from said discharge cell and containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode; and transfer means linking said discharge cell with said charge cell to transfer:
(a) discharged discharge anolyte from said discharge cell to the negative charge compartment in said charge cell and to transfer charged charge anolyte from said negative charge compartment to said negative discharge compartment in said discharge cell; and
(b) discharged discharge catholyte from said discharge cell to the positive charge compartment in said charge cell and to transfer charged charge catholyte from said positive charge compartment to said positive discharge compartment in said discharge cell; which process comprises withdrawing electrical energy from the all-vanadium redox discharge cell by loading an external circuit in electronic communication with the positive and negative discharge electrodes.process for producing electricity from a charged all-vanadium discharge cell of an all-vanadium redox dual battery system comprising:
The discharge cell can include a discharge anolyte reservoir for storing discharge anolyte operatively coupled to the negative discharge compartment by discharge anolyte supply and return lines via a pump and a discharge catholyte reservoir for storing discharge catholyte operatively coupled to the positive discharge compartment by discharge catholyte supply and return lines via a pump.
In an alternative arrangement the discharge cell can include a discharge anolyte discharge reservoir having discharge anolyte discharge supply and return line or lines for charging further discharge anolyte which is to be delivered to the negative discharge compartment and a discharge catholyte discharge reservoir having discharge catholyte discharge supply and return line or lines for charging further discharge catholyte which is to be delivered to the positive discharge compartment a discharge anolyte storage reservoir having discharge anolyte storage supply and return line or lines for storing discharge anolyte from the negative discharge compartment and a discharge catholyte storage reservoir having discharge catholyte storage supply and return line or lines for -n- storing discharge catholyte from the positive discharge compartment and pumping means operatively coupled to the discharge anolyte storage line or lines and/or the discharge anolyte discharge line or lines and to the discharge catholyte storage line or lines and/or the discharge catholyte discharge line or lines for pumping:
(i)the discharge catholyte through the discharge catholyte storage line or lines, the positive discharge compartment and the discharge catholyte discharge line or lines; and
(ii)the discharge anolyte solution through the discharge anolyte solution storage line or lines, the negative discharge compartment and the discharge anolyte solution discharge line or lines.
According to a fifth embodiment of this invention there is provided an all-vanadium redox dual battery composite system comprising: an all-vanadium redox discharge cell having a negative discharge compartment having a negative discharge electrode for discharging a discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a positive discharge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the discharge anolyte in the discharge potential range during oxidation of divalent vanadium ions to trivalent vanadium ions at the negative discharge electrode; an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of trivalent and tetravalent vanadium ions to divalent vanadium ions at the negative charge electrode; a discharge/charge anolyte reservoir for storing discharge and charge anolyte operatively coupled to the negative discharge compartment by discharge anolyte supply and return lines via a first transfer means and operatively coupled to the negative charge compartment by charge anolyte supply and return lines via a second transfer means and a discharge/charge catholyte reservoir for storing discharge and charge catholyte operatively coupled to the positive discharge compartment by discharge catholyte supply and return lines via third transfer means and operatively coupled to the positive charge compartment by charge catholyte supply and return lines via fourth transfer means.
The positive and negative discharge electrodes can be any shape desired. It is preferred that the positive and negative discharge electrodes are rectangular-plate shaped.
Generally a transfer means consist of at least two pipes having at least one pump operatively coupled thereto.
The positive and negative discharge electrodes are chosen from electrode materials which are stable in the discharge catholyte and anolyte respectively in the potential ranges in which the respective discharge reactions occur. For example, in an all-vanadium redox discharge cell in which the discharge anolyte comprises 2M divalent/trivalent vanadium ions in H2S04 and the discharge catholyte comprises 2M pentavalent-tetravalent vanadium redox system in 2M H2S0 , the open circuit potential of the negative discharge half-cell is about -0.4V vs SHE while the open circuit of the positive discharge half-cell is about +1.0V vs SHE. In this instance, the positive and negative discharge electrodes can be selected from electrode materials which are stable to corrosion at potentials below 1.0V and above -0.4V vs SHE respectively. Electrode materials which corrode at potentials more positive than about -0.4V vs SHE are unsuitable in this instance.
The positive and negative discharge electrodes can be carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; cellulose; The positive and negative discharge electrodes can also be selected from the group consisting of carbon or graphite felt, mat, plate, rod, knit, fibre, or cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene, carbon impregnated polystyrene, carbon impregnated polyvinylchloride and carbon impregnated polyvinylidenechloride, when impregnated with and/or coated with Au, Pt, Ir, Ru, Os, Re, Rh and/or Ag; platinised Ti ; platinised Ru; platinised Ir; platinised Pd; Pt; Pt black; Au; Pd; Ir; Ru; Os; Re; Rh; Hg or Ag. A dimensionally stabilized anode (DSA - Ti or Ti alloy core, coated at least partially with titanium dioxide which coating is coated in turn with a noble metal coating selected from the group consisting of Pt, Pd, Os, Rh, Ru, Ir and alloys thereof) is a suitable positive discharge electrode.
The positive and negative discharge compartments of the discharge cell can be coupled to the positive and negative charge compartments of the charge cell respectively by lines through which catholyte can be transported between positive di charge and charge compartments and anolyte can be transported inter negative discharge and charge compartments. The lines can include pumps and valves as required to transport the catholyte and anolyte.
The positive charge and discharge anolytes and the negative charge and discharge catholytes comprise an electrolyte which is typically an aqueous solution which includes H2S04> trifluoromethanesulphonic acid, Na2S04, K2S04, H3P04, Na3P04, K3P04, HN03, KN03, NaN03, sulphonic acid, C6-C, arylsulphonic acid such as p-toluenesulphonic acid, benzenesulphonic acid, naphthalenesulphonic acid, Cι-C6 alkylsulphonic acid such as methylsulphonic acid and ethylsulphonic acid, acetic acid or mixtures thereof in a concentration of from 0.01M to 6.0M. It is especially preferred to use H2S04 in a concentration of from 0.25M to 4.5M, more preferably 0.5M to 4M.
The electrolyte typically has vanadium ions in sufficient concentration for high discharge capacity in the discharge cell, for exa ple, 0.25M to 3.5M, preferably 1M to 3M, and more preferably 1.5M to 2.5M are typical in the charge and discharge cells of the invention. The vanadium ions in the electrolyte are prepared by dissolving an oxide, sulphate, phosphate, nitrate, halogenide or other salt or complex of vanadium which is soluble in the electrolyte. It is especially preferable to dissolve vanadyl sulphate in 0.5M to 3.5M H2S04 or V205 or NaV03 in 0.5M to 6M H2S04 by electrolytic dissolution.
During discharging in the discharge cell and charging in the charge cell the electrolyte is typically stirred or agitated preferably with a mechanical stirrer.
The charge cell of the invention and the discharge cell are typically cells of the "membrane-type", that is each type of cell employs a membrane rather than a diaphragm to separate a positive compartment from a negative compartment. The membrane employed is typically sheet-like and can transport "electrolyte ions whilst at the same time being hydraulically-impermeable in contrast to a diaphragm (typically asbestos) which allows restricted electrolyte transfer between compartments. Thus the ionically conducting separator can be a microporous separator or a membrane fabricated from a polymer based on perfluorocarboxylic acids or a proton exchange polymer such as sulphonated polystyrene, sulphonated polyethylene or a substantially fluorinated sulphonic acid polymer such as Nafion (Trade Mark) or membranes of Flemion (Trade Mark) or Sele ion (Trade Mark) material as manufactured by Asahi Glass Company.
Discharging in the discharge cell and charging in the charge cell are typically conducted in sealed air tight cells and can be conducted under an inert atmosphere such as nitrogen, argon, helium or neon or mixtures thereof although an inert atmosphere can be avoided in a sealed system.
All-vanadium redox charge and discharge cells of the invention can be operated over a broad temperature range, e.g. -5°C to 99°C but are typically operated in the temperature range 15βC to 40βC.
The discharge cell includes monopolar and bipolar type discharge cells. A bipolar discharge cell typically includes a plurality of positive discharge compartments each having a positive discharge electrode therein and a plurality of negative discharge compartments each having a negative discharge electrode therein and wherein each of the compartments are separated by a membrane. A bipolar discharge cell is typically of the flat plate- or filter press-type.
BRIEF DESCRIPTION OF DRAWINGS Preferred embodiments of the invention are described below with reference to the following drawing in which:
Fig. 1 depicts schematically an all-vanadium redox charge cell system;
Fig. 2 depicts schematically an all-vanadium redox charge cell system which utilizes bipolar electrodes;
Fig. 3 depicts a bipolar electrode where two different materials are employed for positive and negative electrodes;
Fig. 4 depicts schematically an aϊT-vanadium redox dual battery system; and
Fig. 5 depicts schematically another all-vanadium redox dual battery system.
MODES FOR CARRYING OUT INVENTION
Referring to Fig. 1 an all-vanadium redox charge cell 10 has a negative compartment 11 containing a charge anolyte 12 in electrical contact with negative charge electrode 13. Charge anolyte 12 is an electrolyte containing 0.01M to 5.0M H2S04 and from 0.25M to 3.5M trivalent and/or tetravalent vanadium ions. Cell 10 has a positive charge compartment 14 containing a charge catholyte 15 in electrical contact with positive charge electrode 16. Charge catholyte 15 is an electrolyte containing 0.01M to 5.0M H2S04 and from 0.25M to 3.5M tetravalent vanadium ions. Cell 10 has an ionically conducting separator 17 disposed between positive and negative charge compartments 14 and 11 and in contact with charge anolyte 12 and charge catholyte 15 to provide ionic communication therebetween. Positive charge electrode 16 is chosen from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir and V205 coated on Pb, Ti , Zr, Hf, Ta, W or Nb since electrodes fabricated from any of these materials have been found to be stable in charge catholyte 15 in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at positive charge electrode 16. Negative charge electrode 13 can be selected from the group consisting of TI ; Bi ; Pb; Hg; In; Cd; Ag; Ga; Sb; Zn; Pb/Hg; Pb/Bi ; Hg/In; Hg/Cd; Hg/Ga; Hg/Ag; carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; and cellulose. The immediately preceding materials have been found to be stable in charge anolyte 12 in the charge potential range during reduction of trivalent and tetravalent vanadium ions to divalent vanadium ions at negative charge electrode 13. It is especially preferred to use a Pb negative charge electrode 13 and a DSA or V205 coated on Pb or Ti positive charge electrode 16.
Negative charge compartment 11 is coupled to charge anolyte charge reservoir 18 by supply line 19 for charging charge anolyte from charge reservoir 18 to negative compartment 11 and to charge anolyte storage reservoir 20 by line 101 which includes pump 102. Positive charge compartment 14 is coupled to charge catholyte charge reservoir 103 by supply line 104 for charging charge catholyte from charge reservoir 103 to positive compartment 14 and to charge catholyte storage reservoir 104 by line 105 which includes pump 106 or recycled to reservoir 103.
Negative charge electrode 13 and positive charge electrode 16 are electrically coupled to power source 107 via switch 108.
In a typical application 3.0M H2S04 containing 2.0M-2.5M tetravalent vanadium ions are added to positive charge compartment 14 from catholyte charge reservoir 103 via supply line 104 and 3.0M H2S04 containing 2.0M-2.5M trivalent/tetravalent vanadium ions are added to negative charge compartment 11 from anolyte charge reservoir 18 via supply line 19. Switch 108 is closed so that electrical energy is provided to negative and positive electrodes 13 and 16 respectively from power source 107 which can be a dc battery to derive pentavalent vanadium ions in catholyte 15 and divalent vanadium ions in anolyte 12. On completion 'catholyte 15 is pumped by pump 106 into catholyte storage reservoir 104 or returned to catholyte charge reservoir 103 and anolyte 12 is pumped into anolyte storage reservoir 20 by pump 102 or returned to charge anolyte charge reservoir 18 and negative and positive compartments 11 and 14 are refilled and the above process is repeated.
The above steps are usually conducted under an inert atmosphere such as nitrogen or the system is sealed from the atmosphere.
Referring to Fig. 2 an alternative all-vanadium redox charge cell 20 has negative charge compartment 21 and bipolar negative charge compartments 22 containing a charge anolyte in electrical contact with negative charge electrode 23 and bipolar negative charge electrodes 24 respectively. Charge cell 20 has positive charge compartment 25 and bipolar positive charge compartments 26 containing a charge catholyte in electrical contact with positive charge electrode 27 and bipolar positive charge electrodes 28 respectively. Compartments 21, 22, 25 and 26 are I'
-19- separated by ionically conducting membranes 29 which are preferably Selemion or Nafion membranes.
The charge anolyte is an electrolyte containing 0.01M to 5.0M H2S04 and from 0.25M to 3.5M trivalent and/or tetravalent vanadium ions. The charge catholyte is an electrolyte containing 0.01M to 5.0M H2S04 and from 0.25M to 3.5M tetravalent vanadium ions. Positive charge electrode 27 and bipolar positive charge electrodes 28 is chosen from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir and V205 coated on Pb, Ti , Zr, Hf, Ta, W or Nb. DSA or V205 coated on Pb or Ti are particularly preferred positive charge electrode materials. Negative charge electrode 23 and bipolar negative charge electrodes 24 can be selected from the group consisting of TI ; Bi ; Pb; Hg; In; Cd; Ag; Ga; Sb; Zn; Pb/Hg; Pb/Bi ; Hg/In; Hg/Cd; Hg/Ga; Hg/Ag; carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinylidenechloride; glassy carbon; non-woven carbon fibre material; and cellulose. Pb is a particularly preferred negative charge electrode material.
Negative charge compartment 21 and bipolar negative charge compartments 22 are coupled to charge anolyte charge reservoir 200 by supply line 201 for charging charge anolyte from charge reservoir 200 to compartments 21 and 22 and by recirculation line 202 which includes pump 203 for pumping charge anolyte from compartments 21 and 22 into reservoir 200. Positive charge compartment 25 and bipolar positive charge compartments 26 are coupled to charge catholyte charge reservoir 204 by supply line 205 for charging charge catholyte from charge reservoir 204 to compartments 25 and 26 and by recirculation line 206 which includes pump 207 for pumping charge catholyte from compartments 25 and 26 into reservoir 204. Negative charge electrode 23 and positive charge electrode 27 are electrically coupled to power source 208 via switch 209.
In a typical charging operation 3.0M H2S04 containing 2.0M to 2.5M tetravalent vanadium ions are added to compartments 25 and 26 from catholyte charge reservoir 204 via supply line 205 and 3.0M H2S0 containing 2.0M to 2.5M trivalent/tetravalent vanadium ions are added to compartments 21 and 22 from anolyte charge reservoir 200 via supply line 201. Switch 209 is closed so that electrical energy is provided to negative and positive electrodes 23 and 27 respectively from power source 208 which is typically a dc battery to derive pentavalent vanadium ions in the catholyte and divalent vanadium ions in the anolyte. The charge catholyte and the charge anolyte are typically recirculated through compartments 25 and 26 and compartments 21 and 22 respectively. On completion of the charging processes the charge catholyte and anolyte are removed from cell 20 and reservoirs 204 and 200 and discharged discharge catholyte and anolyte are added to reservoirs 204 and 200 respectively and the above process is repeated. Typically the process is conducted under an inert atmosphere such as nitrogen. Alternatively, the process can be conducted under airtight sealed conditions.
Fig. 3 depicts a bipolar electrode 30 having a positive charge electrode 31 and a negative charge electrode 32 joined by conductive epoxy 33. Electrode 30 has flow fields 34 which are insulated to prevent electrolyte contacting epoxy 33. For example electrode 30 can be a Pb negative/DSA positive discharging electrode combination. Thus a Ti sheet can be coated on one side with Ti02/Ru02 and on the other side coated with Pb or a thin Pb sheet can be bonded to one side of a Ti sheet with conductive cement/paste and the other side of the Ti sheet coated with Ti02/Ru02. Alternatively, a Pb sheet can be coated on one side with V205 film and uncoated on the other side to provide a bipolar electrode having Pb as the negative electrode and V205 as the positive electrode.
An alternative all-vanadium redox discharge cell analogous construction to all-vanadium redox charge cell 20 shown in Fig. 2 can also be utilized.
Referring to Fig. 4 an all-vanadium redox dual battery system includes an all-vanadium redox discharge cell 40 having a negative discharge compartment 41 containing a discharge anolyte in electrical contact with a negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions and a positive discharge compartment 42 containing a discharge catholyte comprising an electrolyte containing pentavalent vanadium ions. An ionically conducting separator 43 is disposed between positive and negative discharge compartments 42 and 41 to provide ionic communication therebetween. The positive and negative discharge electrodes are preferably carbon or graphite felt and the discharge catholyte and the discharge anolyte comprise an electrolyte which is typically 0.5M to 3.5M H2S04 containing typically 1.5M to 2.5M vanadium ions. The positive discharge electrode is preferably a carbon or graphite felt electrode which is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is preferably a carbon or graphite felt electrode which is stable in the discharge anolyte in the discharge potential range during oxidation of divalent vanadium ions to trivalent vanadium ions at the negative discharge carbon electrode.
Negative discharge compartment 41 is operatively coupled to discharge anolyte reservoir 44 by discharge anolyte supply line 45 and return line 46. Return line 46 includes pump 47 which can be used to recirculate discharge anolyte through discharge compartment 41 and anolyte storage compartment 44. Positive discharge compartment 42 is operatively coupled to discharge catholyte reservoir 48 via discharge catholyte supply line 49 and discharge catholyte return line 401 which incorporates pump 402. Pump 402 can be used to recirculate discharge catholyte through discharge compartment 42 and catholyte storage compartment 48. Discharge cell 40 is suitable for use in an electric vehicle where the discharge cell 40 would be installed in the vehicle and after cell 40 has been discharged the discharged discharge catholyte and anolyte could be drained into charge catholyte reservoir 403 and charge anolyte reservoir 404 respectively. Charge catholyte reservoir 403 is operatively coupled to positive charge compartment 408 via charge anolyte supply line 405 and charge anolyte return line 406 which includes pump 407 which can be used to recirculate charge catholyte between charge compartment 408 and reservoir 403. Charge anolyte reservoir 404 is operatively coupled to negative charge compartment 409 via charge catholyte supply line 410 and charge catholyte return line 411 which includes pump 412 which can be used to recirculate charge catholyte between charge compartment 409 and reservoir 404. Positive charge compartment 408 contains a charge catholyte in electrical contact with a positive charge electrode. The charge catholyte typically comprises 0.5M to 3.5M H2S04 and contains 1.5M to 2.5M tetravalent vanadium ions. Negative charge compartment 409 contains a charged anolyte in electrical contact with a negative charge electrode. The charge anolyte typically comprises 0.5M to 3.5M H2S0 having 1.5M to 2.5M trivalent and/or tetravalent vanadium ions. An ionically conducting separator 410 is disposed between compartments 408 and 409 and is in contact with the charge catholyte and the charge anolyte to provide ionic communication therebetween. The positive and negative charge electrodes are chosen from electrode materials which are stable in the charge catholyte and charge anolyte respectively in the potential ranges in which the respective charge reactions occur. Carbon felt and Pb are particularly preferred negative charge electrode materials and DSA and V205 on Pb or Ti is a particularly preferred positive charge electrode materials. Compartments 408 and 409 are filled with charge catholyte and charge anolyte respectively from reservoirs 403 and 404 respectively and electrical energy is provided to the positive and negative charge electrodes to derive divalent vanadium ions in the charge anolyte and pentavalent vanadium ions in the charge catholyte. Once the process of charging has been completed the charge catholyte and charge anolyte are removed from compartments 408 and 409 and' reservoirs 403 and 404 and placed into positive and negative compartments 42 and 41. Electricity can then be produced from cell 40 by withdrawing electrical energy from cell 40 by loading an external circuit in electronic communication with the positive and negative discharge electrodes. The charging and discharging processes can be repeated.
Referring to Fig. 5 an all-vanadium redox dual battery composite system 50 has an all-vanadium redox discharge cell 51 having a negative discharge compartment 52 containing or adapted to contain a discharge anolyte in electrical contact with a negative discharge electrode. The discharge anolyte is typically 0.25M to 3.5M H2S04 containing 1.5M to 2.5M divalent vanadium ions. Cell 51 also has a positive discharge compartment 53 containing or adapted to contain a discharge catholyte in electrical contact with a positive discharge electrode. The discharge catholyte typically comprises 0.25M to 3.5M H2S04 and has 1.5M to 2.5M pentavalent vanadium ions. Ionically conducting separator 54 is disposed between compartments 52 and 53 to provide ionic communication therebetween. The positive discharge electrode and negative discharge electrode are typically carbon or graphite felt electrodes. Syste 50 also includes an all-vanadium redox charge cell 55 having a negative charge compartment 56 containing or adapted to contain a charge anolyte in electrical contact with a negative charge electrode. The charge anolyte particularly comprises 0.25M to 3.5M H2S04 and contains 1.5M to 2.5M trivalent and/or tetravalent vanadium ions. Positive charge compartment 57 contains or is adapted to contain a charge catholyte in electrical contact with a positive charge electrode. The charge catholyte particularly comprises 0.5M to 3.5M H2S04 having 1.5M to 2.5M tetravalent vanadium ions. Ionically conducting separator 58 is disposed between compartments 56 and 57 to provide ionic communication therebetween. The positive charge electrode is typically DSA or V20, on Pb or Ti and the negative charge electrode is typically a carbon felt or Pb electrode. System 50 also includes a discharge /charge anolyte reservoir 59 for storing discharge and charge anolyte operatively coupled to negative discharge compartment 52 by discharge anolyte supply line 501 and return line 502 which includes pump 503 and operatively coupled to negative charge compartment 56 by charge anolyte supply line 504 and return line 505 which includes pump 506. System 50 further includes a discharge/charge catholyte reservoir 507 for storing discharge and charge catholyte operatively coupled to positive discharge compartment 53 by discharge catholyte supply line 508 and return line 509 which includes pump 510 and operatively coupled to positive charge compartment 57 by charge catholyte supply line 511 and return line 512 which includes pump 513.
System 50 includes valves 514 to 517 to enable diversion of the respective catholytes and anolytes to the desired compartments.
In use charge catholyte is charged in positive compartment 57 and charge anolyte is charged in negative compartment 56 and on completion of charging transferred to reservoirs 507 and 59 respectively and positive compartment 53 and negative compartment 52 respectively. Electricity is then produced from cell 51 by withdrawing electrical energy from cell 51 by loading an external circuit in electronic communication with the positive and negative discharge electrodes. The discharged discharge catholyte and anolyte are then retransferred into reservoirs 507 and 59 respectively and compartments 57 and 56 respectively and electrical energy is provided to the positive and negative charge electrodes to derive divalent vanadium ions in the charge anolyte and pentavalent vanadium ions in the charge catholyte. The charging and discharging processes can be repeated.
EXAMPLE 1
A vanadium redox charging cell employing a lead negative electrode and a DSA positive electrode has been used for over 3 months continuously to charge a V(IV) solution to V(V) and V(III) Solution to V(II) at the positive and negative electrodes respectively. Operating at a current of 20 mA/cm2 and a voltage of 2.2 V, the cell has been alowed to go into overcharge repetitively with generation of 02 and H2. After 3 months continuous operation, the electrodes were removed and weighed. Zero weight loss was found for the lead negative and less than 0.01% weight loss found for the positive DSA electrode. An equivalent experiment using graphite plates for the negative and positive electrodes showed weight losses of approximately 1% and 5% respectively, illustrating the dramatic improvement in electrode life with the Pb and DSA electrodes for charging.
EXAMPLE 2
V205 coatings on Ti substrates have been prepared by both spray deposition and by painting on a slurry of the material. Spray deposition was carried out using a 1% solution of ammonium metavanadate in water. The solution was sprayed onto a Ti sheet resting on a hot plank set at about 300°C. As the spray solution comes into contact with the hot substrate, the ammonium metavanadate decomposes forming a thin film of V20s. The procedure is continued until the required film thickness is achieved.
Coatings of V205 and V205 + Sb203 mixtures have also been prepared by painting a slurry of the oxide or oxides mixed with water, onto the Ti substrate. The coating is then annealed at 500°C for approximately 2 hours. This results in a uniform, adherent film of V205. 20-30 wt% Sb203 is added to increase conductivity of the V205 films.
EXAMPLE 3
Preliminary experiments showed that if a lead electrode is used as a positive electrode in a vanadium redox cell, passivation occurs, probably due to the formation of a lead vanadate film on the surface. However, the present inventors have found that if a positive potential is applied to a lead electrode in a dilute vanadium solution, passivation does not occur since a coating of V205 is slowly produced as a result of oxidation of the vanadium ions in solution to V(V) and slow precipitation on the surface of the lead electrode.
V20s was electrodeposited onto a 15cm x 15cm Pb substrate from a α.OlM solution of V0S04 in 2M H2S04. The Pb substrate was connected to the positive terminal of a power supply. A 15cm x 15cm Pb substrate was employed as the negative electrode. A current density of 40mAcπT2was applied for 24 hours resulting in a thin yellow coating of V205 on the surface of the positive Pb electrode. The two lead electrodes were then used as electrodes in a vanadium redox cell for charging only. Discharged vanadium solutions were pumped through the cell and charged at a current density of 20mAcm~2. The cell voltage increased from approximately 2.5 volts to 2.7 volts near the end of the charge cycle. When fully charged, the solutions were replaced with uncharged solutions and charging was continued for several days without any deterioration in performance.
When similar continuous charging was carried out with a cell employing graphite plates and felt as the positive and negative electrodes, the cell voltage was considerably lower (1.5 - 2.0 volts) initially. However, after about one week of continuous charging, the voltage increased considerably as a result of the formation of a V205 film on the surface of the positive electrode. This was confirming by reversing the polarity of the electrodes i.e. making the positive electrode negative and vice versa. This resulted in the cell voltage returning to its original value since the V205 was now reduced and removed from the electrode surface.
The above results suggest a means for maintaining a clean positive electrode surface in a charging cell employing either graphite or DSA positive electrodes.
The use of a V205 coated lead positive electrode does require a higher voltage than other electrode materials (due to the slight resistance of the V20s film). However, unlike graphite, it is not subject to degradation and is stable over extended periods of time.
INDUSTRIAL APPLICABILITY
In an all-vanadium redox charge cell of the invention the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode. These attributes mean that an all-vanadium redox discharge cell which is used in conjunction with such an all-vanadium redox charge cell has a greater life.

Claims

VANADIUM CHARGING CELL AND VANADIUM DUAL BATTERY SYSTEMCLAIMS
1. ■ An all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode.
2. The all-vanadium redox charge cell as defined in claim 1 wherein the negative charge electrode has a higher hydrogen overvoltage than copper to minimise H2 evolution during the charging reaction at the positive charge electrode.
3. The all-vanadium redox charge cell as defined in claim 1 wherein the negative charge electrode is selected from the group consisting of TI , Bi , Pb, Hg, In, Cd, Ag, Ga, Sb, Zn, Pb/Hg, Pb/Bi , Hg/In, Hg/Cd, Hg/Ga, Hg/Ag, carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene,- carbon impregnated polystyrene, carbon impregnated polyvinylchloride, carbon impregnated polyvinylidenechloride, glassy carbon, non-woven carbon fibre material, and cellulose.
4. The all-vanadium redox charge cell as defined in claim 1 wherein the positive charge electrode is selected from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir, and V205 coated on Pb,
Ti, Zr, Hf, Ta, W or Nb.
5. The all-vanadium redox charge cell as defined in claim 3 wherein the positive charge electrode is selected from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir, and V205 coated on Pb,
Ti, Zr, Hf, Ta, W or Nb.
6. An all-vanadium redox dual battery system comprising: an all-vanadium redox discharge cell having a negative discharge compartment having a negative charge electrode for discharging a discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a positive charge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte ; and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the discharge anolyte in the discharge potential range during oxidisation of divalent to vanadium ions at the negative discharge electrode; an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, said charge anolyte comprising discharged discharge anolyte from said discharge cell and containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, said charge catholyte comprising discharged discharge catholyte from said discharge cell and containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode; and transfer means linking said discharge cell with said charge cell to transfer:
(a) discharged discharge anolyte from said discharge cell to the negative charge compartment in said charge cell and to transfer charged charge anolyte from said negative charge compartment to said negative discharge compartment in said discharge cell; and
(b) discharged discharge catholyte from said discharge cell to the positive charge compartment in said charge cell and to transfer charged charge catholyte from said positive charge compartment to said positive discharge compartment in said discharge cell.
7. The all-vanadium redox dual battery system as defined in claim 6 wherein the negative charge electrode has a higher hydrogen overvoltage than copper to minimise H2 evolution during the charging reaction at the positive charge electrode.
8. The all-vanadium redox dual battery system as defined in claim 6 wherein the negative charge electrode is selected from the group consisting of TI , Bi , Pb, Hg, In, Cd, Ag, Ga, Sb, Zn, Pb/Hg, Pb/Bi, Hg/In, Hg/Cd, Hg/Ga, Hg/Ag, carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene, carbon impregnated polystyrene, carbon impregnated polyvinylchloride, carbon impregnated polyvinyl idenechloride, glassy carbon, non-woven carbon fibre material, and cellulose.
9. The all-vanadium redox dual battery system as defined in claim 6 wherein the positive charge electrode is selected from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir, and V20s coated on Pb, Ti , Zr, Hf, Ta, W or Nb.
10. The all-vanadium redox dual battery system as defined in claim 8 wherein the positive charge electrode is selected from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir, and V205. coated on Pb, Ti , Zr, Hf, Ta, W or Nb.
11. The all-vanadium redox dual battery system as defined in claim 6 wherein the positive and negative discharge electrodes are selected from the group consisting of carbon, graphite felt, mat, plate, rod, knit, fibre, or cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinylidenechloride; glassy carbon; non-woven carbon fibre material; cellulose.
12. The all-vanadium redox dual battery system as defined in claim 6 wherein the positive and negative discharge electrodes are selected from the group consisting of carbon or graphite felt, mat, plate, rod, knit, fibre, or cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene, carbon impregnated polystyrene, carbon impregnated polyvinylchloride and carbon impregnated polyvinylidenechloride, when impregnated with and/or coated with Au, Pt, Ir, Ru, Os, Re, Rh and/or Ag; platinised Ti ; platinised Ru; platinised Ir; platinised Pd; Pt; Pt black; Au; Pd; Ir; -Ru; Os; Re; Rh; Hg or Ag.
13. The all-vanadium redox dual battery system as defined in claim 6 wherein the positive discharge electrode is a dimensionally stabilized anode with a Ti or Ti alloy core, coated at least partially with titanium dioxide which coating is coated in turn with a noble metal coating selected from the group consisting of Pt, Pd, Os, Rh, Ru, Ir and alloys thereof.
14. An all-vanadium redox dual battery composite system comprising: an all-vanadium redox discharge cell having a negative discharge compartment having a negative discharge electrode for discharging a discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a positive discharge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the discharge anolyte in the discharge potential range during oxidation of divalent vanadium ions to trivalent vanadium ions at the negative discharge electrode; an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of trivalent and tetravalent vanadium ions to divalent vanadium ions at the negative charge electrode; a discharge/charge anolyte reservoir for storing discharge and charge anolyte operatively coupled to the negative discharge compartment by discharge anolyte supply and return lines via a first transfer means and operatively coupled to the negative charge compartment by charge anolyte supply and return lines via a second transfer means and a discharge/charge catholyte reservoir for storing discharge and charge catholyte operatively coupled to the positive discharge compartment by discharge catholyte supply and return lines via third transfer means and operatively coupled to the positive charge compartment by charge catholyte supply and return lines via fourth transfer means.
15. The all-vanadium redox dual battery composite system as defined in claim 14 wherein the negative charge electrode has a higher hydrogen overvoltage than copper to minimise H2 evolution during the charging reaction at the positive charge electrode.
16. The all-vanadium redox dual battery composite system as defined in claim 14 wherein the negative charge electrode is selected from the group consisting of TI , Bi , Pb, Hg, In, Cd, Ag, Ga, Sb, Zn, Pb/Hg, Pb/Bi, Hg/In, Hg/Cd, Hg/Ga, Hg/Ag, carbon and graphite felt, mat, plate, rod, knit, fibre, and cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene, carbon impregnated polystyrene, carbon impregnated polyvinylchloride, carbon impregnated polyvinyl idenechloride, glassy carbon, non-woven carbon fibre material, and cellulose.
17. The all-vanadium redox dual battery composite system as defined in claim 14 wherein the positive charge electrode is selected from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir, and
V205 coated on Pb, Ti , Zr, Hf, Ta, W or Nb.
18. The all-vanadium redox dual battery composite system as defined in claim 17 wherein the positive charge electrode is selected from the group consisting of DSA, platinised Ti , platinised Ru, platinised Ir, and
V205 coated on Pb, Ti , Zr, Hf, Ta, W or Nb.
19. The all-vanadium redox dual battery composite system as defined in claim 14 wherein the positive and negative discharge electrodes are selected from the group consisting of carbon, graphite felt, mat, plate, rod, knit, fibre, or cloth; carbon impregnated teflon; carbon impregnated polyethylene; carbon impregnated polypropylene; carbon impregnated polystyrene; carbon impregnated polyvinylchloride; carbon impregnated polyvinyl idenechloride; glassy carbon; non-woven carbon fibre material; cellulose.
20. The all-vanadium redox dual battery composite system as defined in claim 14 wherein the positive and negative discharge electrodes are selected from the group consisting of carbon or graphite felt, mat, plate, rod, knit, fibre, or cloth, carbon impregnated teflon, carbon impregnated polyethylene, carbon impregnated polypropylene, carbon impregnated polystyrene, carbon impregnated polyvinylchloride and carbon impregnated polyvinyl idenechloride, when impregnated with and/or coated with Au, Pt, Ir, Ru, Os, Re, Rh and/or Ag; platinised Ti ; platinised Ru; platinised Ir; platinised Pd; Pt; Pt black; Au; Pd; Ir; Ru; Os; Re; Rh; Hg or Ag.
21. The all-vanadium redox dual battery composite system as defined in claim 14 wherein the positive discharge electrode is a dimensional ly stabilized anode with a Ti or Ti alloy core, coated at least partially with titanium dioxide which coating is coated in turn with a noble metal coating selected from the group consisting of Pt, Pd, Os, Rh, Ru, Ir and alloys thereof.
22. A process for charging a charge anolyte and a charge catholyte of an all-vanadium redox charge cell having: a negative charge compartment containing a charge anolyte and having a negative charge electrode for charging said charge anolyte in electrical contact with said negative charge electrode, the charge anolyte comprising an electrolyte containing trivalent and/or tetravalent vanadium ions; a positive charge compartment containing a charge catholyte and having a positive charge electrode for charging said charge catholyte in electrical contact with said positive charge electrode, the charge catholyte comprising an electrolyte containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode; which process comprises providing electrical energy to the positive and negative charge electrodes to derive divalent vanadium ions in the charge anolyte and pentavalent vanadium ions in the charge catholyte.
23. A process for producing electricity from a charged all-vanadium discharge cell of an all-vanadium redox dual battery system comprising: an all-vanadium redox discharge cell having a negative discharge compartment containing a discharge anolyte and having a negative discharge electrode for discharging said discharge anolyte in electrical contact with said negative discharge electrode, the discharge anolyte comprising an electrolyte containing divalent vanadium ions; a positive discharge compartment having a discharge catholyte and having a positive discharge electrode for discharging a discharge catholyte in electrical contact with said positive discharge electrode, the discharge catholyte comprising an electrolyte containing pentavalent vanadium ions; and an ionically conducting discharge separator disposed between the positive and negative discharge compartments to provide ionic communication between the discharge catholyte and the discharge anolyte ; and wherein the positive discharge electrode is stable in the discharge catholyte in the discharge potential range during reduction of pentavalent vanadium ions to tetravalent vanadium ions at the positive discharge electrode and the negative discharge electrode is stable in the discharge anolyte in the discharge potential range during oxidisation of divalent to vanadium ions at the negative discharge electrode; an all-vanadium redox charge cell having: a negative charge compartment having a negative charge electrode for charging a charge anolyte in electrical contact with said negative charge electrode, said charge anolyte comprising discharged discharge anolyte from said discharge cell and containing trivalent and/or tetravalent vanadium ions; a positive charge compartment having a positive charge electrode for charging a charge catholyte in electrical contact with said positive charge electrode, said charge catholyte comprising discharged discharge catholyte from said discharge cell and containing tetravalent vanadium ions; and an ionically conducting charge separator disposed between the positive and negative charge compartments to provide ionic communication between the charge catholyte and the charge anolyte ; and wherein the positive charge electrode is stable in the charge catholyte in the charge potential range during oxidisation of tetravalent vanadium ions to pentavalent vanadium ions at the positive charge electrode and the negative charge electrode is stable in the charge anolyte in the charge potential range during reduction of tetravalent and trivalent vanadium ions to divalent vanadium ions at the negative charge electrode; and transfer means linking said discharge cell with said charge cell to transfer: (a) discharged discharge anolyte from said discharge cell to the negative charge compartment in said charge cell and to transfer charged charge anolyte from said negative charge compartment to said negative discharge compartment in said discharge cell; and
(b) discharged discharge catholyte from said discharge cell to the positive charge compartment in said charge cell and to transfer charged charge catholyte from said positive charge compartment to said positive discharge compartment in said discharge cell; which process comprises withdrawing electrical energy from the all-vanadium redox discharge cell by loading an external circuit in electronic communication with the positive and negative discharge electrodes.
PCT/AU1988/000473 1987-12-10 1988-12-09 Vanadium charging cell and vanadium dual battery system WO1989005528A1 (en)

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AUPI584987 1987-12-10
AUPI5849 1987-12-10
AUPJ0583 1988-09-23
AUPJ058388 1988-09-23

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US9178207B2 (en) 2010-09-16 2015-11-03 Fluidic, Inc. Electrochemical cell system with a progressive oxygen evolving electrode / fuel electrode
US9214830B2 (en) 2010-10-20 2015-12-15 Fluidic, Inc. Battery resetting process for scaffold fuel electrode
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US8709629B2 (en) 2010-12-22 2014-04-29 Jd Holding Inc. Systems and methods for redox flow battery scalable modular reactant storage
US10141594B2 (en) 2011-10-07 2018-11-27 Vrb Energy Inc. Systems and methods for assembling redox flow battery reactor cells
US9853454B2 (en) 2011-12-20 2017-12-26 Jd Holding Inc. Vanadium redox battery energy storage system
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