Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
• • 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
  • H01M8/04—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
  • H01M8/04201—Reactant storage and supply, e.g. means for feeding, pipes
• • 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
  • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
  • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
  • H01M8/0444—Concentration; Density
  • H01M8/04477—Concentration; Density of the electrolyte
• • 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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N2021/3129—Determining multicomponents by multiwavelength light
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/94—Investigating contamination, e.g. dust
• • 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

Definitions

• the present invention relates to a method for determining the
• Concentration measurements of the negative and positive electrolytes by UV / Vis spectrometry as well as a method for operating a vanadium redox battery, in the context of which the charge state of the redox flow battery is determined by means of the indicated method.
• Another aspect of the present invention relates to a vanadium redox flow battery equipped with devices that allow the determination of the state of charge based on the UV / Vis absorptions of the negative and positive electrolytes using UV / Vis measurements and by these devices avoids or reduces the need for rebalancing.
• electrical networks can be stabilized. Thus, in times when more electrical energy is generated than consumed, electrical energy can be taken up in such storage systems in order to avoid an overload of the line networks. At a later stage, when more energy is needed than can be provided by the renewable energy, then the energy can be fed back into the electrical grid.
• Many energy storage systems used today are redox flow batteries. In contrast to conventional batteries, the electrodes of a redox flow battery are only involved in a catalytic process, but not in chemical reactions, so that the electrode is used in the context of the use of the
• redox flow batteries are particularly suitable for temporary energy storage.
• Redox flow batteries are known based on various redox pairs.
• iron solutions with the redox couple Fe 2+ / Fe 3+ are used as the positive electrolyte
• the negative electrolyte is based on chromium solutions with the redox couple Cr 2+ / Cr 3+ (cf., for example, US Pat. US 4,159,366).
• the vanadium redox flow battery has the advantage over such batteries that the redox pairs in the negative and positive electrolytes are based on the same element "vanadium", which may be in two-, three-, four- and pentavalent form
• vanadium which may be in two-, three-, four- and pentavalent form
• the divalent and trivalent forms exist as V 2+ and V 3+ ions
• the penta- and pentavalent forms are present as V0 2+ and V0 2 + on a fast response time, a non-occurring contamination in case of a
• vanadium redox flow batteries are particularly suitable for use as large-scale energy storage.
• Vanadium amount of the two electrolyte tanks is that during the long-term operation of redox flow batteries various processes take place, which can lead to a change in the vanadium concentration, vanadium or the charge state in the two electrolytes. Likewise, these processes can lead to a shift of the electrolyte volume between the two electrolytes.
• Electrolyte tanks and a partial self-discharge of the electrolyte The diffusion of water through the membrane can cause a shift in the
• Vanadium concentration and the electrolyte volumes lead. This can lead to a higher vanadium concentration on the one half-cell side of the battery and a decrease in the vanadium concentration on the other half-cell side of the battery. This results in an imbalance of
• Capacity loss of the battery can be determined by the vanadium concentration or amount of vanadium and the charge state of the negative and the positive electrolyte.
• a rebalancing or remixing of the electrolyte is necessary at certain intervals, to the different amounts of substance, concentration, volume and / or Recharge states of the two electrolytes again.
• the rebalancing leads to a partial discharge of the electrolyte, the remixing usually to a complete discharge of the electrolyte. Both rebalancing and remixing are detrimental to the energy efficiency of the redox flow battery.
• V 2+ , V 3+ , V 4+ and V 5+ may be necessary for the following other reasons:
• V 2+ is a strong reducing agent and is in the presence of
• V 5+ is stable only in a limited temperature window and concentration range and can age permanently and irreversibly precipitate out of the solution;
• the permanganometric titration is used, in which the charge state of both the negative and the negative V 2+ , V 3+ and V 4+ equivalence points as well as part of the positive electrolyte can be determined.
• the negative electrolyte is directly titrated, whereby the oxidation of the V 2+ is kinetically inhibited.
• the charge state of the positive electrolyte is determined for V 5+ via a back titration.
• analysis technique is that the measurement can not be done online (i.e., on the fly), but that samples of the positive and negative electrolytes must be taken respectively, which then the
• permanganometric titration can not be used for continuous monitoring of the
• Charge state of a redox flow battery can be used.
• conductivity sensors for the electrolytes are therefore frequently used nowadays. It uses the fact that ions have a specific molar ionic conductivity, which can be used to determine the concentrations of these ions.
• first calibration lines at about 400 nm, about 600 nm and / or about 800 nm are recorded, based on which the redox state is to be determined on the basis of the linear behavior between absorption and charge state.
• the positive electrolyte is the
• the transmission spectra of the different charge states are to be recorded at a known total vanadium and sulfuric acid concentration and used as comparison spectrums for the adjustment.
• the "excess" absorption at a defined wavelength eg 760 nm
• At least the positive electrolyte is considered unsatisfactory.
• Charge state of both the negative and the positive electrolyte in a vanadium redox flow battery can be determined with high accuracy.
• the method should require as little additional effort as possible, such as the execution of calibrations, the determination of
• This method of rebalancing has the disadvantage that only a balance of the volumes of the negative and the positive electrolyte takes place. There is no compensation of the electrolyte with respect to the vanadium concentration and / or the amount of vanadium in the two electrolytes.
• Rudoplh et al. [S. Rudolph, U. Schröder, IM Bayanov, On-line controlled state of charge rebalancing in vanadium redox flow battery, Journal of Electroanalytical Chemistry 2013, 703, 29] describe a method for rebalancing the H + ion concentration. In this case, a small volume (5 ml) of the negative electrolyte in the positive electrolyte is given every four cycles. The same
• a higher pressure in the negative half-cell causes the solvent (H 2 O) to diffuse through the membrane from the negative electrolyte into the positive electrolyte.
• the positive electrolyte is diluted in the positive half-cell and the negative electrolyte is concentrated.
• the described methods have the disadvantage that the rebalancing takes place via the electrolyte tanks or in the cell and the self-discharge of the electrolyte takes place in the electrolyte tanks or in the cell.
• Rebalancing used volumetric flows are not used for further analysis of the electrolyte.
• the present invention therefore relates to a
• a second aspect of the present invention relates to a method for
• the charge state of the negative electrolyte is determined by determining the concentrations of V 2+ and V 3+ via the absorption at a defined wavelength
• the charge state of the positive electrolyte is calculated by calculating the original concentrations of V 4+ and V 5+ from the concentrations determined in (i) and (iii).
• Electrolytes removed and subjected to the specified steps are removed and subjected to the specified steps.
• the method is performed online, that is, the state of charge of the battery is determined during operation of the battery and the negative and positive electrolyte remains in the battery during the measurement.
• This can be z. B. in the negative electrolyte easily realized by a portion of the negative electrolyte, which is fed to the redox flow battery is passed through a UV / Vis detector.
• UV / Vis in the context of the present invention denotes the wavelength range of 200 to 1000 nm.
• the negative electrolyte contains vanadium ions substantially (ie, more than 99%) in the +11 and + III oxidation states, while the positive electrolyte contains vanadium ions substantially (ie, greater than 99%) in the + IV and + V oxidation states.
• the vanadium redox-flow battery may consist of one or more cells, each of these cells each having a half-cell with negative
• Electrolytes and a half-cell with positive electrolyte comprises.
• the negative and positive half cells are not fixed, i. Depending on how the battery is charged, one of the half cells is positive and one of the half cells is a negative half cell.
• defined volume is to be understood to dictate the volumes of the negative and positive electrolytes externally (i.e., by the battery / cell control) and held constant for a series of measurements.
• the total vanadium concentration it is expedient for the given negative and positive half cell, if this in the range of 0.5 to 8 mol / l, preferably 1 to 3 mol / l, particularly preferably 1.2 to 2.5 mol / l lies.
• the total vanadium concentration decreases, the total storage capacity of the vanadium redox flow battery is reduced at constant volumes of the two electrolyte tanks.
• the electrolytic solution is relatively highly viscous, resulting in increased resistance to flow through the cell and decreased conversion efficiency in the cells.
• the determination of the V 2+ concentration is expediently carried out at a wavelength in the range from 800 to 900 nm, preferably 840 to 865 nm and particularly preferably at about 852 nm.
• This wavelength has the advantage that as far as possible there is no interference with the bands of the V 3+ species.
• determination of the V 3+ concentration may also be accomplished by measuring absorbance in the range of 550 to 700 nm, preferably 605 to 630 nm, and most preferably about 612 nm.
• the maximum at 852 nm may be used to determine the concentration of V 2+ , while for V 3+ , the maximum is due to only minor interference from the V 2+ band at around 370 nm at 402 nm.
• Equations 1 and 2 can be solved exactly by means of linear algebra and thus the concentration of V 2+ and V 3+ can be determined.
• the charge state of the negative electrolyte according to formula 3 can be determined.
• the positive electrolyte can be measured directly without dilution, but this leads to the problems described above.
• the solution of the positive electrolyte is, due to the very high
• a second approach is to use the positive electrolyte, e.g. B. by a factor of 1 to 2, to dilute and to measure the resulting solution in a cuvette with a layer thickness of 100 ⁇ .
• this possibility does not circumvent the aforementioned problem of computational and software effort.
• this solution requires a precise dilution, as any
• the problem of determining the charge state of the positive electrolyte is solved by mixing a defined volume of the negative and positive electrolytes with each other, resulting in that by reacting V 2+ in the negative electrolyte and V 5+ in the positive electrolyte be generated depending on the concentration of the respective species V 3+ ions and / or V 4+ ions.
• V 3+ with V 5+ and V 2+ with V 4+ the concentration of V 2+ and V 3+ or V 3+ and V 4+ ions in the resulting mixture of the negative and positive electrolytes is again determined by absorption at a defined wavelength in the mixture of negative and positive electrolytes, being to
• V 2+ and V 3+ or V 3+ and V 4+ ions are formed by mixing the two electrolytes depends solely on the mixing ratio, the charge states and the total vanadium concentration of the individual
• V 5+ species are still present after mixing.
• the concentration of V 4+ is preferably determined at a wavelength in the range of 700 to 850 nm, preferably 760 to 785 nm and particularly preferably 773 nm, since V 4+ species have their maximum absorption in this range.
• V 3+ ions have a high absorption at a wavelength of about 402 nm, while in V 4+ ions do not absorb in this region, the absorption of V 3+ at a wavelength of 773 nm can be determined from the V 3+ - Concentration and the extinction coefficient at this wavelength are determined and taken into account in the calculation of the V 4+ concentration.
• the ratio in which the negative and the positive electrolyte are mixed together in step (ii) is in the range from 4: 1 to 1: 4, a ratio of 3: 1 to 1: 3 can be given as preferred. It is initially not important which electrolyte is used to a greater extent and which to a smaller extent. Rather, it is crucial in this approach that the mixing of the two electrolytes causes a redox reaction, which ensures that any V 5+ is reduced.
• the remaining vanadium species are thus either V 4+ and V 3+ (ratio of positive electrolyte to negative electrolyte eg 2: 1) or V 3+ and V 2+ (ratio of positive electrolyte to negative electrolyte> 1: 2 with an assumed SOC of 100% and equal total vanadium concentrations of the electrolytes).
• step (ii) Software work around. It is most preferred that the ratio in which the negative and the positive electrolytes are mixed together in step (ii) is about 2: 1 or about 1: 2.
• V 4+ and V 3+ concentrations of V 4+ and V 3+ it is also expedient to carry out a correction by the absorption proportion of the vanadium ion of the other oxidation state.
• the V 4+ and V 3+ concentrations can then be calculated, for example, using the following formulas (4) and (5) and solving the linear system of equations.
• the back calculations for the actual V 4+ and V 5+ concentrations in the positive electrolyte are carried out via a semi-empirical formula which shows the determined concentrations of the V 3+ and V 4+ concentrations of the mixture of positive and negative electrolytes and the V 2+ and V 3+ concentrations of the negative electrolyte used for the mixture are taken into account.
• V 2+ and V 3+ ions are obtained by the mixture of the positive and negative electrolytes, the concentration of these ions is determined according to the above-described formulas (1) and (2) and said semiempirical formula.
• Electrolysis cell is determined. This procedure has the advantage that in addition to the state of charge, the charge or discharge efficiency of the electrolysis cell can be determined. Furthermore, it is expedient if steps (ii) to (iv) are also carried out with positive and negative electrolytes, which are each branched off from the feed line to the electrolysis cell and in the region of the discharge from the electrolysis cell. By determining the charge state of the positive electrolyte in steps (ii) to (iv), it is thus also possible to determine the charge or discharge efficiency of the positive electrolysis cell.
• steps (ii) to (iv) a positive and negative electrolyte mixture is generated which can be recycled to the electrolyte circuits due to the fact that vanadium redox flow batteries in the positive and negative electrolytes have substantially the same chemical elements , Although this has the consequence that due to the technical discharge of the positive and negative electrolyte due to the determination of the state of charge, a small amount of additional energy is required to completely recharge the vanadium redox flow battery, but this disadvantage is compensated by that through the
• the total storage capacity of the vanadium redox flow battery can be kept constant.
• the process mixes the positive and negative electrolytes in a particular ratio, it is expedient for the mixture of the negative and the positive electrolytes to be returned to corresponding proportions in the positive and the negative electrolyte tank / reservoir.
• Another aspect of the present invention relates to the recycling of the positive and the negative electrolyte mixture subsequent to steps (ii) to (iv) and the determination of the state of charge in the negative and the positive electrolyte tank and the use of the mixture of the positive and the negative electrolyte to rebalance the vanadium redox flow battery.
• Charge state of the positive electrolyte, the negative and the positive electrolyte are mixed together to determine the vanadium concentration and the state of charge of the positive electrolyte.
• the vanadium redox flow battery For the operation of the vanadium redox flow battery, it may therefore be useful to combine the determination of the state of charge and the rebalancing or remixing with each other to reduce the efficiency of the vanadium redox flow battery, due to the technical discharge during mixing of the negative and of the positive electrolyte. If necessary, the frequency of determining the state of charge, the choice of the
• Mixing ratio for the determination of the state of charge and the recycling of the mixture of the negative and the positive electrolyte are so adapted or adjusted that the mixture of the negative and the positive electrolyte after the steps (ii) to (iv) in a further step ( v) can be used to rebalance the electrolyte.
• the mixture of the negative and positive electrolytes may be used for both complete and partial rebalancing of the electrolyte. Rebalancing the volume becomes the mix of the negative and the positive Electrolytes preferably returned to the electrolyte with the lower volume following the determination of the state of charge.
• the mixture of the negative and the positive electrolytes may be used to rebalance the amount of vanadium.
• the mixture of the negative and the positive electrolytes may be used to rebalance the amount of vanadium.
• Mixture of the negative and the positive electrolyte after the determination of the state of charge is preferably recycled to the electrolyte with the lower amount of vanadium.
• the mixture of negative and positive electrolytes is returned to the lower vanadium electrolyte or the higher vanadium electrolyte upon determination of the state of charge.
• the determination of the charge state of the electrolyte or the return of the mixture of the negative and the positive electrolyte is designed or combined with the rebalancing, which is a continuous
• Rebalancing of the electrolyte is achieved and on a discontinuous rebalancing at regular intervals, as it is usually performed, can be dispensed with.
• Another aspect of the present invention relates to a vanadium redox flow battery having a negative and a positive half-cell, a membrane positioned between the positive and the negative half-cell, and
• Circuits for negative and positive electrolytes each a reservoir for negative and positive electrolytes, a supply of the electrolyte into the respective half-cell, a derivative of the electrolyte from the half-cell into the reservoir and a pump for supplying negative and positive electrolytes in the Negative and positive half cells include, with the vanadium redox flow battery
• FIG. 1 A schematic representation of such a battery is shown in FIG. 1
• Figure 1 shows the redox-flow cell
• Figure 2 and 3 represents the positive and negative half cell, respectively
• Figure 4 shows the membrane.
• About the pumps 13 and 14 is from the reservoirs 7 and 8 positive and negative electrolytes in the respective
• Half-cells 2 and 3 pumped. After leaving the half-cells, the electrolyte flows back into the reservoirs 7 and 8 via the lines 11 and 12.
• each designates valves that are each opened during operation of the battery, and when the battery is not in use, can be closed to prevent diffusion of the electrolyte through the conduits.
• 5 and 6 respectively represent the positive and negative electrolyte circuits.
• In the area of the supply of the negative electrolyte 10 in the negative half-cell 3 is a device for measuring the UV / Vis spectrum of the negative
• Electrolytes 15 are provided, which is traversed either through a line parallel to the main line of electrolyte, or may be integrated directly into the supply line of the negative electrolyte 10. Furthermore, in the region of the feed line of the negative electrolyte 10, the device has a discharge line 17, with which electrolyte can be led to a further device for measuring a UV / Vis spectrum 18.
• the device 18 also has a supply line of positive electrolyte, which is branched off in the region of the feed line of the positive electrolyte 9 to the positive half-cell 2 via the discharge line 16 and mixed with the negative electrolene coming from the discharge line 17 before entering the UV / Vis spectrum of the mixture in the device 18 is taken.
• the vanadium redox flow battery has a control circuit 19, by means of which the concentrations of V 2+ and V 3+ in the negative electrolyte and V 4+ and V 5+ in the positive electrolyte, and thus the state of charge of the battery can be calculated ,
• the described battery is not limited to the use of a redox flow cell, but that the battery may also include multiple redox flow cell, e.g. B. are connected in series. In this case, the derivatives are positive and negative
• Electrolytes expedient in a range of leads 9 and 10, in which the entire electrolyte is passed to the different redox flow cells.
• the vanadium redox flow cell has a negative and a positive half-cell, as well as a membrane or separator positioned between the positive and negative half-cell.
• the membrane is an ion-conducting membrane which ensures ion exchange between the electrolytes in the positive and negative half-cells, while inhibiting mixing of the two solutions pumped by the cells. Theoretically, the membrane should insulate the metal ions in their half-cells, but it can not be completely avoided for the above reasons that it will over time lead to some
• the membrane is an ion exchange membrane, and more preferably a cation exchange membrane or membrane
• a cation exchange membrane allows the transfer of charge-carrying H + ions, depending on the concentration of the electrolyte.
• the cation exchange membrane is Nafion 112, Nafion 117, or other Nafion cation exchange membranes.
• the cation exchange membrane may also be a Gore Select membrane, a Flemion membrane or a Selenium CMV cation exchange membrane.
• Other suitable membranes such. B. from FuMA-Tech GmbH, Germany under the trade name
• the membrane may also be expedient for the membrane if it is covered by a graphite paper with respect to the positive half-cell and the negative half-cell, as described, for example, in US Pat. As described in US 8,808,897.
• the material that makes up the negative and positive electrode for the vanadium redox flow cell is typically a porous one
• the positive electrode material may also be an oxide-coated titanium metal plate or an expanded metal mesh.
• a titanium based electrode provides longer lasting stability to oxidation during charging of the solution in the positive half cell.
• the charging and discharging can be done either while the pumps are on and the electrolytes are pumped through the external tanks into the redox flow cell or while the pumps are off so that the solution in the cell can undergo a discharge reaction.
• the positive half-cell is designed as an electrolytic cell.
• the positive electrode is designed as a corrosion-resistant electrode. Suitable electrodes are in this context
• Diamanf electrodes Diachem ® from Condias GmbH Germany.
• vanadium redox flow battery has feed lines with which the mixture of negative and positive electrolytes in the circuits of the positive and the negative
• Electrolytes can be recycled.
• leads 20 and 21 are shown as an example.
• the device described here is therefore modified so that it in the region of the leads 12 of the negative electrolyte from the negative half-cell 3, a device for Determination of the UV / Vis spectrum of the negative electrolyte and in the region of the derivatives of the negative and positive electrolytes 11 and 12 from the negative and positive half-cell derivatives for these electrolytes, said derivatives flowing together and with a supply line to a device for determining the UV / Vis spectrum of the mixture of negative and positive electrolytes are connected.
• the mixture formed in this case is preferably due to the reservoirs 7 and 8, which preferably takes place by means of a supply of the mixture to the supply lines 20 and 21.
• rebalancing may be wholly or partly via the supply of the positive and negative electrolyte mixture. If rebalancing via this measure is not possible to the required extent, then an additional rebalancing can also take place by means of additional lines which are installed between the reservoirs 7 and 8.
• the lines can be controlled by additional pumps, but it is also possible to attach the lines between the supply line 9 and the reservoir 8 or between the supply line 10 and the reservoir 7 so as to use the pumping power of the pumps 13 and 14. In this case, these lines are conveniently connected via valves to the lines 9 and 10, which, as needed, open or
• the device is expediently to be modified in such a way that it has further lines between the outlet 12 and the reservoir 7, or between the outlet 11 and the reservoir 8, via a separate valve or the valve illustrated in FIG.
• the method can be applied to various systems, i. also variations by stabilizers, temperature and variations of the transition metal are possible; The process is thus broadly applicable to all redox-flow systems with transition metals as
• another aspect of the present invention also relates to a method for determining the state of charge of a redox-flow battery having a negative and positive half-cell comprising the steps
• the exact extinction coefficients were determined iteratively on the basis of a series of real samples with different total vanadium concentrations and charge states (see FIG. 4). The adjustment was carried out by permanganometric titration, which was defined as the nominal value. The same procedure was also used for various real samples
• Electrolyte of unknown concentration and state of charge with a part of negative electrolyte Based on this mixture, the charge state and the total vanadium concentration by means of the UV / Vis spectrum (see FIG. 7) were also determined for the positive electrolyte by the method described above and compared with permanganometric titration (see Table 3).
• Electrolyte solutions (eg caused by diffusion processes) can be analyzed for total vanadium concentration and charge state by this method.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Electrochemistry (AREA)
• Sustainable Energy (AREA)
• Sustainable Development (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• General Physics & Mathematics (AREA)
• General Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Health & Medical Sciences (AREA)
• Analytical Chemistry (AREA)
• Fuel Cell (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=59858715

Family Applications (1)

Country Status (8)

Families Citing this family (11)

Family Cites Families (9)

• 2016
  • 2016-09-19 DE DE102016117604.4A patent/DE102016117604A1/de not_active Withdrawn
• 2017
  • 2017-09-08 CN CN201780057280.1A patent/CN109716572A/zh active Pending
  • 2017-09-08 JP JP2019514727A patent/JP2019530159A/ja not_active Withdrawn
  • 2017-09-08 WO PCT/EP2017/072547 patent/WO2018050547A1/de active Search and Examination
  • 2017-09-08 CA CA3036798A patent/CA3036798A1/en not_active Abandoned
  • 2017-09-08 US US16/333,292 patent/US20190267648A1/en not_active Abandoned
  • 2017-09-08 EP EP17765412.6A patent/EP3516722A1/de not_active Withdrawn
  • 2017-09-08 KR KR1020197011241A patent/KR20190055176A/ko not_active Application Discontinuation

Also Published As

Similar Documents

Legal Events