Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/20—Indirect fuel cells, e.g. fuel cells with redox couple being irreversible
• • 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
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/4242—Regeneration of electrolyte or reactants
• • 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
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0082—Organic polymers
• • 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
• • 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
  • H01M50/70—Arrangements for stirring or circulating the electrolyte
  • H01M50/77—Arrangements for stirring or circulating the electrolyte with external circulating path
• • 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
• • 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
• • 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
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49108—Electric battery cell making

Definitions

• the invention pertains to redox flow batteries (RFB) that have multiple- membranes (for example, at least two membranes, such as one cation exchange membrane and one anion exchange membrane) and a multiple-electrolyte (for example, at least three electrolytes, such as one electrolyte in contact with a negative electrode, one electrolyte in contact with a positive electrode, and at least one electrolyte disposed between the two membranes) as the basic characteristic.
• RFB redox flow batteries
• a redox flow battery As an electrochemical cell, a redox flow battery (RFB) is a type of rechargeable battery that stores electrical energy, typically in two soluble redox pairs contained in external electrolyte tanks.
• An ion-selective membrane (either cation exchange membrane, CEM, or anion exchange membrane, AEM) is used to physically separate, but ionically connect, the two electrolytes that dissolve the two redox pairs.
• the scale of external electrolyte stored can be sized in accordance with application requirements. When n eeded, liquid electrolytes are pumped from storage tanks to flow-through electrodes where chemical energy is converted to electrical energy (discharge) or vice versa (charge). Different from other conventional battery systems, RFBs store electrical energy in the flowing electrolytes.
• the energy capacity and the power rating are fundamentally decoupled :
• the energy capacity is determined by concentration and volume of electrolytes, while the power rating is determined by the size and number of cells in stack.
• This unique feature combined with its long cycle-life, low capital-cost, scalability, and independence from geographical/geological limitations that are faced by pumped hydro and compressed air technologies, makes RFB one of the most intrinsically attractive technologies in electrical energy storage, especially in the field of renewable (e.g., wind or solar) electricity generation where the intrinsic intermittency has to be dealt with. Since the first concept of RFB was put forward about 40 years ago (in 1974), significant progress has been made and some RFB systems, e.g., the all vanadium RFB (AV-RFB), have already been commercialized.
• AV-RFB all vanadium RFB
• RFBs have not reached broad market penetration yet because many challenging problems remain unsolved.
• the generally low energy and power density of RFB have been identified to be main drawbacks when compared with other battery systems, which means more electrolyte/electrode materials are needed when certain energy capacity/power rating is required, negatively impacting their cost-effectiveness.
• Attempts have been made to increase the solubility of active species by choosing alternative redox pairs or using different electrolytes, which can theoretically increase the energy density, but these efforts do not improve the power density.
• efforts have been made to improve electrode performance by using better electrode designs or utilizing more active catalysts, which can increase the power density, but not the energy density.
• the ideal and simple solution would be the increase of RFB's cell voltage, which could increase the energy density and power density simultaneously.
• a prior art RFB system 100 is shown in Figure 1. Negative electrolyte 30 flows through negative electrode (anode) 31 from negative electrolyte source 20 via pump 15. Positive electrolyte 40 flows through positive electrode (cathode) 41 from positive electrolyte source 25 via pump 16. Positive electrode 40 and negative electrode 30 are separated by a single ion selective membrane 28.
• the RFB 100 may be connected to a grid input/output processor 10.
• the cell voltage is simply determined by the two redox pairs used, and often the cation-based redox pairs (e.g., Co 3+ /Co 2+ redox pair with +1.953 V standard electrode potential and Ce 4+ /Ce 3+ one with + 1.743 V, all the quoted potential values here and hereinafter calculated based on standard thermodynamic conditions) have more positive electrode potentials (ideally for the positive electrode of RFB) and the anion- based ones (e.g., AI(0H) 4 7AI with -2.337 V and Zn(OH) 4 2 7Zn with - 1.216 V) have more negative electrode potentials (ideally for the negative electrode).
• the cation-based redox pairs e.g., Co 3+ /Co 2+ redox pair with +1.953 V standard electrode potential and Ce 4+ /Ce 3+ one with + 1.743 V, all the quoted potential values here and hereinafter calculated based on standard thermodynamic conditions
• the anion- based ones e.g.,
• CEM cation exchange membrane
• AEM anion exchange membrane
• the earliest RFB system i.e., the iron- chromium RFB system (Fe/Cr-RFB, [(Fe 3+ /Fe 2+ )/(Cr 3 7Cr 2+ )] with +1.18 V standard cell voltage) and the currently most popular RFB, i.e., the AV-RFB system ([(V0 2 7V0 2+ )/(V 3 7V 2+ )] with +1.26 V) both belong to the all-cation-based RFB systems.
• the iron-chromium RFB system Fe/Cr-RFB, [(Fe 3+ /Fe 2+ )/(Cr 3 7Cr 2+ )] with +1.18 V standard cell voltage
• the currently most popular RFB i.e., the AV-RFB system ([(V0 2 7V0 2+ )/(V 3 7V 2+ )] with +1.26 V) both belong to the all-cation-based RFB
• the polysulphide-bromine FB system (S/Br-RFB, [(S 4 2 7S 2 2 ⁇ )/(Br 3 7Br)] with + 1.36 V) is a typical all-anion-based RFB.
• the single ion-selective membrane also requires the same or similar (e.g., having the same cation but different anions when an AEM used, or having the same anion but different cations when a CEM used) supporting (or background) electrolyte in positive side and negative one, which sometimes limits the choices of redox pairs and further narrows the available range of cell voltages.
• the zinc-cerium RFB system (Zn/Ce-RFB, [(Zn 7Zn)/(Ce 4 7Ce 3+ )]) can offer as high as 2.50 V standard cell voltage (the highest number reported among all known aqueous RFB systems), it suffers a great hydrogen evolution problem in negative side (Zn 2 7Zn).
• the reason is that the acidic supporting electrolyte used (in both sides) creates a huge over-potential (760 mV) for hydrogen evolution reaction (0 V standard electrode potential of H7H 2 at pH 0 vs. and -0.760 V standard electrode potential of Zn 2 7Zn).
• the invention provides a novel redox flow battery design, e.g., a multiple-membrane, multiple-electrolyte (MMME) redox flow based battery design, comprising a first membrane; a second membrane; a first electrolyte disposed between the first membrane and the second membrane; a second electrolyte in contact with the first membrane and a first electrode; and a third electrolyte in contact with the second membrane and a second electrode; and wherein the first electrolyte and second electrolyte are different in terms of at least one species of anion, and the first electrolyte and third electrolyte are different in terms of at least one species of cation; and wherein the first electrode is a negative (or a positive) electrode and the second electrode is a positive (or a negative) electrode; and wherein the first membrane and/or the second membrane is selected from the group consisting of a cation exchange membrane and an anion exchange membrane.
• MMME multiple-membrane, multiple-
• the invention provides a novel redox flow battery design, e.g., a multiple-membrane, multiple-electrolyte (MMME) based battery design, comprising a first membrane; a second membrane; a first electrolyte disposed between the first membrane and the second membrane; a second electrolyte in contact with the first membrane and a first electrode; a third electrolyte in contact with the second membrane and a second electrode; wherein the battery further comprises a third membrane disposed between the first membrane and the second membrane and a fourth electrolyte disposed between the first membrane and the second membrane; wherein the third membrane separates the fourth electrolyte from the first electrolyte; and wherein the first electrolyte and second electrolyte are different in terms of at least one species of anion, and the first electrolyte and third or fourth electrolyte are different in terms of at least one species of cation; and wherein the first electrode is a negative electrode and the second electrode is a positive electrode;
• the second electrolyte comprises an anion-based redox pair, such as an anion-redox pair selected from the group consisting of an AI(OH) 4 " /AI redox pair, a Zn(OH) 4 2" /Zn redox pair, an S 4 2 7S 2 2 ⁇ redox pair and a Co(CN) 6 7Co(CIM) 6 4" redox pair.
• an anion-based redox pair such as an anion-redox pair selected from the group consisting of an AI(OH) 4 " /AI redox pair, a Zn(OH) 4 2" /Zn redox pair, an S 4 2 7S 2 2 ⁇ redox pair and a Co(CN) 6 7Co(CIM) 6 4" redox pair.
• the third electrolyte comprises a cation-based redox pair, such as a cation-based redox pair selected from the group consisting of a Co 3+ /Co 2+ redox pair, a Fe 3+ /Fe 2+ redox pair and a Ce 4+ /Ce 3+ redox pair.
• at least one of the second electrolyte and third electrolyte comprises an anion-based redox pair, a cation-based redox pair or a cation-anion hybrid redox pair.
• one of the first, second, third and/or fourth electrolytes comprises at least one of: cations based on hydronium, sodium, magnesium, potassium or calcium; or anions based on hydroxide, perchlorate, sulfate, phosphate, acetate, chloride, bromide or carbonate.
• the invention provides a method of making a redox flow battery comprising : partially surrounding a first electrolyte with a first membrane and a second membrane; b) partially surrounding a second electrolyte with the first membrane and a first electrode; and partially surrounding a third electrolyte with the second membrane and a second electrode; wherein the first membrane and/or the second membrane is selected from the group consisting of a cation exchange membrane and an anion exchange membrane.
• the invention provides a method of making a redox flow battery comprising : partially surrounding a first electrolyte with a first membrane and a third membrane; partially surrounding a fourth electrolyte with the third membrane and a second membrane; partially surrounding a second electrolyte with the first membrane and a first electrode; and partially surrounding a third electrolyte with the second membrane and a second electrode; wherein the first and second membranes are anion-exchange membranes and the third membrane is a cation exchange membrane or the first and second membranes are cation-exchange membranes and the third membrane is an anion exchange membrane.
• the invention provides a redox flow battery made by these methods.
• Figure 1 shows a conventional single-membrane double-electrolyte RFB.
• Figure 2 shows an illustration of a multiple-membrane multiple-electrolyte concept.
• FIG. 3 shows a version of a multiple-membrane multiple-electrolyte RFB
• Figure 4 shows an illustration of another multiple-membrane multiple-electrolyte concept.
• FIG. 5 shows a version of another multiple-membrane multiple-electrolyte RFB.
• Figure 6 shows a standard electrode potential for select redox pairs and cell voltage for different RFBs.
• Figure 7 shows the open circuit voltage of an AI/Co-MMME-RFB.
• Figure 8 shows the charge and discharge curves of an AI/Co-MMME-RFB.
• Figure 9 shows the open circuit voltage of a Zn/Ce-MMME-RFB.
• Figure 10 shows the charge and discharge curves of a Zn/Ce-MMME-RFB.
• Figure 11 shows a continuous charge-discharge test of a Zn/Ce-DMTE-RFB for 10 cycles.
• Figure 12 shows the efficiency calculation of a Zn/Ce-DMTE-RFB for each cycle.
• the multiple-membrane, multiple-electrolyte (MMME) RFB systems described herein can dramatically increase cell voltages and decrease ionic crossover simultaneously by involvement of a multiple-membrane arrangement (at least one piece of CEM and at least one piece of AEM) that divides the redox flow battery cell into multiple compartments filled with multiple-electrolyte (one in contact with a negative electrode, one in contact with a positive electrode, and at least one in between the two membranes).
• a multiple-membrane arrangement at least one piece of CEM and at least one piece of AEM
• multiple-electrolyte one in contact with a negative electrode, one in contact with a positive electrode, and at least one in between the two membranes.
• This particular design favorably brings great freedom in selecting redox pairs as well as their supporting electrolytes for both the negative side and the positive side, making high cell voltage RFBs possible.
• the middle electrolyte(s) in between also serves as a great "buffer" that can significantly reduce the overall counter-ion crossover between the negative side and the positive side, fundamentally solving the electrolyte contamination problem and providing great convenience for electrolyte separation and rebalance.
• the multiple-membrane multiple-electrolyte RFB design described herein allows for a strongly basic negative electrolyte (high pH, e.g. at least 8, at least 9, at least 10 or higher) and a strongly acidic positive electrolyte (low pH, e.g., not more than 6, not more than 5, not more than 4 or lower) to be used at the same time in the same redox flow battery, where a neutral middle electrolyte is in between.
• very negative redox pairs that are usually only stable in basic electrolytes and very positive ones that are usually only stable in acidic electrolytes can be simultaneously incorporated into the MMME-RFB, providing very high cell voltage and very low ionic crossover at the same time.
• FIG. 2 shows a MMME-RFB system 200 comprising a double-membrane and triple electrolyte (DMTE), wherein first electrolyte 60 may be partially surrounded by a second electrolyte 50 and a third electrolyte 70, wherein first electrolyte 60 may be separated from second electrolyte 50 by a f irst membrane 80, such as a cation exchange membrane (CEM) 80, and wherein first electrolyte 60 may be separated from third electrolyte 70 by a second membrane 90, such as an anion exchange membrane (AEM) 90.
• Second electrolyte 50 may be partially surrounded by a first electrode 35, such as a negative electrode (anode) 35.
• Third electrolyte 70 may be partially surrounded by a second electrode 45, such as a positive electrode (cathode) 45.
• DMTE double-membrane and triple electrolyte
• FIG 3 shows a DMTE-RFB based battery 300 wherein, and similar to Figure 2, first electrolyte 60 may be partially surrounded by a second electrolyte 50 and a third electrolyte 70, wherein first electrolyte 60 may be separated from second electrolyte 50 by a first membrane 80, such as a cation exchange membrane (CEM) 80, and wherein first electrolyte 60 may be separated from third electrolyte 70 by a second membrane 90, such as an anion exchange membrane (AEM) 90.
• Second electrolyte 50 may be partially surrounded by a first electrode 35, such as a negative electrode 35.
• Third electrolyte 70 may be partially surrounded by a second electrode 45, such as a positive electrode 45.
• Second electrolyte 50 is flowed from second electrolyte source 51 via pump 17.
• Third electrolyte 70 is flowed from third electrolyte source 71 via pump 19.
• First electrolyte 60 is flowed from first electrolyte source 61 via pump 18.
• DMTE based redox flow battery 300 may be connected to a grid input/output processor 11.
• elements 35 and 45 are referred as electrodes, but they may also include current collectors (not shown).
• the current collectors may be the same or different material as the electrodes. It will be understood to those skilled in the art that electrodes/current collectors 35, 45 may have high specific surface area (e.g., be highly porous).
• FIG. 4 shows a MMME-RFB system 400 comprising a triple-membrane and quadruple electrolyte (TMQE), wherein first electrolyte 203 may be partially surrounded by a second electrolyte 201 and a fourth electrolyte 205, wherein fourth electrolyte 205 may be partially surrounded by first electrolyte 203 and a third electrolyte 207, wherein second electrolyte 201 may be partially surrounded by first electrolyte 203 and a first electrode 235, wherein third electrolyte 207 may be partially surrounded by fourth electrolyte 205 and a second electrode 245, wherein first electrolyte 203 may be separated from second electrolyte 201 and fourth electrolyte 205 by a first membrane 220 and a third membrane 230, respectively, wherein fourth electrolyte 205 may be separated from first electrolyte 203 and third electrolyte 207 by a third membrane 230 and a second membrane 240, respectively
• Figure 5 shows a TMQE-RFB 500 wherein, and similar to Figure 4, wherein first electrolyte 203 may be partially surrounded by a second electrolyte 201 and a fourth electrolyte 205, wherein fourth electrolyte 205 may be partially surrounded by first electrolyte 203 and a third electrolyte 207, wherein second electrolyte 201 may be partially surrounded by first electrolyte 203 and a first electrode 235, wherein third electrolyte 207 may be partially surrounded by fourth electrolyte 205 and a second electrode 245, wherein first electrolyte 203 may be separated from second electrolyte 201 and fourth electrolyte 205 by a first membrane 220 and a third membrane 230, respectively, wherein fourth electrolyte 205 may be separated from first electrolyte 203 and third electrolyte 207 by a third membrane 230 and a second membrane 240, respectively.
• Second electrolyte 201 is flowed from second electrolyte source 211 via pump 41.
• Third electrolyte 207 is flowed from third electrolyte source 217 via pump 44.
• First electrolyte 203 is flowed from first electrolyte source 213 via pump 42.
• Fourth electrolyte 205 is flowed from forth electrolyte source 215 via pump 43.
• TMQE based battery 500 may be connected to a grid input/output processor 12. Similar variations of the electrode and current collector materials and configurations described above with respect to Figure 3 are also applicable to the those of Figure 5.
• Adding a third ion exchange membrane can address challenging redox pair isolation problems presented by two anion-cation hybrid pairs.
• membranes 220, 240 are anion-exchange membranes and membrane 230 is a cation exchange membrane
• the two anion-exchange membranes can block the electro-active cations but not the electro-active anion of the negative and positive hybrid pairs.
• the crossed electro-active anions will be stopped by the cation exchange membrane between the two anion-exchange membranes.
• a configuration wherein membranes 220, 240 are cation-exchange membranes and membrane 230 is an anion exchange membrane can also isolate two hybrid pairs.
• the middle electrolyte(s) in an MMME-RFB system provides another significant benefit for RFBs based on an anion/anion redox pair vs. a cation/cation redox pair, which is the cleaning of crossed-over ions which may contaminate the electrolytes.
• Low level crossed-over ions e.g., about 100 ppm
• the use of middle electrolyte(s) offers an effective to efficiently clean contaminated cells, thereby extending the cell lifetime.
• First, second, third and/or fourth electrolytes 50, 60, 70, 201, 203, 205, 207 are not particularly limited and may comprise any suitable electrolyte or salt, such as those based on cations of hydronium, sodium, magnesium, potassium or calcium, or anions based on hydroxide, perchlorate, sulfate, phosphate, acetate, chloride, bromide or carbonate.
• First and second electrodes 35, 45, 235, 245 are not particularly limited and may comprise any suitable electrode material, such as Al, Zn, Cu, Cd, Pb and C.
• the MMME-RFB systems described herein have great advantages over conventional single-membrane, double-electrolyte batteries and offers high OCV, low ionic crossover, and suppressed hydrogen evolution.
• the materials used to construct the MMME-RFB systems described herein are not particularly limited and may be a myriad of materials, for example, any materials selected from conventional or otherwise known materials used for similar purposes in the energy arts. Such materials include, but are not limited to, cation exchange membranes, anion exchange membranes, electrolyte solutes and solvents, compounds capable of providing the desired redox pairs, acids, bases, negative electrodes, positive electrodes, and the like.
• the MMME-RFB systems described herein have a wide range of applications, especially for high voltage and low ionic crossover batteries.
• an attractive candidate for a RFB redox flow battery system is an aluminum-cobalt MMME-RFB system (e.g., AI/Co-MMME-RFB), configured as [(AI/AI(OH) 4 -)/(Co 3 7Co 2+ )].
• AI/Co-MMME-RFB aluminum-cobalt MMME-RFB system
• the Al portion of the AI/Co-MMME-RFB is comprised in second electrolyte 50 and the Co portion of the AI/Co- MMME-RFB is comprised in third electrolyte 70.
• the Al portion of the AI/Co-MMME-RFB is comprised in second electrolyte 201 and the Co portion of the AI/Co-MMME-RFB is comprised in third electrolyte 207.
• the AI/Co-MMME-RFB system offers a very high cell voltage (4.29 V standard cell voltage), as it successfully combines the very negative redox pair of AI/AI(OH) 4 - (-2.337 V standard electrode potential) in base and the very positive redox pair of Co 3+ /Co 2+ (+ 1.953 V standard electrode potential) in acid.
• Such a high standard cell voltage (4.29 V) is believed to be the highest one reported among all known RFB systems, which value is 1.7 times that of Zn/Ce-RFB systems (2.50 V), 3.2 times that of Polysulfide-bromide S/Br-RFB systems (1.36 V), 3.4 times that of All-Vanadium RFB systems (1.26 V), and 3.6 times that of Iron-Chromium Fe/Cr-RFB systems ( 1.18 V), as shown in Figure 6.
• the very high standard cell voltage of the AI/Co-MMME-RFB system is even higher than that of lithium ion batteries (around 3.5 V), suggesting a great potential of the design to rival other redox flow battery technologies.
• OCV open circuit voltage
• Another attractive candidate for a RFB system is a zinc-cerium
• MMME-RFB system Zn/Ce-MMME-RFB, configured as [(Zn/Zn(OH) 4 2" )/(Ce 4+ /Ce 3+ )].
• the Zn portion of the Zn/Ce-MMME-RFB is comprised in second electrolyte 50 and the Ce portion of the Zn/Ce-MMME-RFB is comprised in third electrolyte 70.
• the Zn portion of the Zn/Ce- MMME-RFB is comprised in second electrolyte 201 and the Ce portion of the Zn/Ce- MMME-RFB is comprised in third electrolyte 207.
• the Zn/Ce-MMME-RFB system offers a standard cell voltage of 2.96 V, as it combines the negative electrode potential (- 1.216 V) from the Zn/Zn(OH) 4 2 ⁇ redox pair and the .positive one (+1.743 V) from the Ce 4+ /Ce 3+ redox pair.
• Such a high standard cell voltage is also higher than those of all conventional aqueous RFB systems, e.g., higher than that of AV-RFB system (1.26 V) and that of Zn/Ce-RFB system (2.50 V, in spite of the strong concern of hydrogen evolution in negative electrode for Zn/Ce-RFB system).
• the discharge and charge reactions are represented in Eq. 3 and Eq. 4, respectively.
• the zincate anions are reduced to zinc metal and the sodium cations are balanced from the middle compartment to the negative compartment.
• cerium(III) cations are oxidized into cerium(IV) and the perchlorate anions are balanced from the middle compartment to the positive compartment.
• the opposite reactions and ion transfer directions will apply.
• the OCV After being charged to reach a state of charge of 90%, the OCV is monitored for 15 minutes. As seen in Figure 9, it shows an initial OCV of 3.14 V and quickly stabilizes to 3.10 V. These OCVs are higher than the standard one (2.96 V), which is reasonable since the cell is in charged state (90% of state of charge). Clearly, such a high observed OCV again confirms and verifies that the MMME-RFB system is feasible and successful.
• the hydrogen evolution phenomenon has not been found during the whole discharge operation as well as during the charge operation.
• the discharge duration lasts for 3 hours and 56 minutes, very close to the charge duration 4 hours, indicating high Coulombic efficiency.
• the overall Coulombic efficiency, voltage efficiency and energy efficiency are calculated in Table 1.
• AI/Co-DMTE-RFB An aluminum-cobalt DMTE-RFB system (AI/Co-DMTE-RFB), configured as [(AI/AI(OH) 4 -)/(Co 3+ /Co 2+ )] was constructed.
• a three-compartment cell made up of three plastic jars was designed and used as follows. Three 50 ml plastic jars were put in series with a hole (a quarter inch of diameter) opened between adjacent two jars. The three jars, based on half-reaction inside, were assigned as negative, middle and positive compartments.
• the cell was first charged at 50 mA (or 8.3 mA/cm 2 of current density) for 2.5 hours and the OCV was tested for 20 min.
• the discharge-charge cycle is then carried out for 20 min by setting current constant at 5 mA (or 0.83 mA/cm 2 of current density).
• a zinc-cerium DMTE-RFB (Zn/Ce-DMTE-RFB), configured as [(Zn/Zn(OH) 4 2- )/(Ce 4+ /Ce 3+ )] was constructed.
• a three-compartment cell made up of three acrylic flow channels was designed and used as follows. Three 5cm by 6cm rectangular channels were put in series with membranes in between. The three channels, based on half-reaction inside, were assigned as negative, middle and positive compartments.
• One piece of Nafion® 1135 membrane (DuPont, 87.5 ⁇ m thickness) and one piece of Fumasep ® FAA membrane (FuMa-Tech, 70 ⁇ m thickness) were used as the CEM and AEM, respectively.
• the CEM is put between the negative compartment and the middle compartment while the AEM is put between the middle compartment and the positive compartment, along with silicone gasket to seal the conjunction part.
• the positive electrode and negative electrode are each put next to its corresponding compartment, respectively.
• Two clamps were used to compress the three channels and electrodes tight ly to avoid electrolyte leakage.
• Electrolytes are stored outside the channel in three tanks and delivered by peristaltic pump (Masterflex ® L/S® 100RPM).
• the working flow battery set-up is a potentiostat/galvanostat (Solartron 1287A) and was used in both OCV and discharge-charge cycle tests.
• the negative electrolyte contained 3 M NaOH and 0.5 M Na 2 [Zn(OH) 4 )]
• a solution that contained 0.5 M Ce(CIO 4 ) 3 , 2 M HCIO 4 was used as the positive electrolyte, which was prepared by dissolving Ce 2 (CO 3 ) 3 into perchloric acid.
• the middle electrolyte used was 4 M NaCIO 4 solution.
• the volume for each electrolyte used in test is 30 ml.
• a rectangular copper plate (ESPI Metals, 5cm by 6cm, 3N grade) was used as negative current collector. Before the experiment, the copper was rinsed with acetone and deposited with a layer of cadmium according to the method in reference.
• Graphite based bipolar plate (SGL group, 5 cm by 6 cm, Sigracet® TF6 type) was used as positive current collector.
• Graphite felt (SGL Group, 3 cm by 4 cm, Sigracell® GFA5 EA type) was used as positive electrode and compressed by plastic frame to contact bipolar plate.
• the cut-off voltage for charge and discharge are 3.24 and 1.8 respectively.
• the discharge-charge cycle was carried out at constant current density at 60 mA (or 5 mA/cm 2 of current density) with flow rate for all three electrolytes at 20 ml/min.
• MMME-RFB systems described above may have other configurations besides those of acid/neutral/base configurations and are not limited thereto.
• Tables 2-4 list some possible candidates and combinations of MMME-RFB configurations.
• Non-aqueous mixed ion systems such as a non-aqueous all-ruthenium RFB (Ru(acac) 3 /[Ru(acac) 3 ]- vs. [Ru(acac) 3 ] + /Ru(acac) 3 ), a non-aqueous all-vanadium RFB (V(acac) 3 /[V(acac) 3 ]- vs.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Fuel Cell (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=49758711

Family Applications (1)

Country Status (8)

Cited By (2)

Families Citing this family (52)

Citations (3)

Family Cites Families (9)

• 2013
  • 2013-06-13 MX MX2014015316A patent/MX2014015316A/es unknown
  • 2013-06-13 WO PCT/US2013/045595 patent/WO2013188636A1/en active Application Filing
  • 2013-06-13 EP EP13804479.7A patent/EP2862225A4/en not_active Withdrawn
  • 2013-06-13 AU AU2013274244A patent/AU2013274244A1/en not_active Abandoned
  • 2013-06-13 IN IN10255DEN2014 patent/IN2014DN10255A/en unknown
  • 2013-06-13 JP JP2015517416A patent/JP2015519718A/ja active Pending
  • 2013-06-13 CN CN201380031402.1A patent/CN104364959A/zh active Pending
  • 2013-06-14 US US13/918,444 patent/US9917323B2/en not_active Expired - Fee Related
  • 2013-06-14 US US13/918,452 patent/US9640826B2/en not_active Expired - Fee Related

Patent Citations (3)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events