WO2022215822A1 - 바나듐 전해액 제조방법 및 바나듐 전해액을 포함하는 전지 - Google Patents
바나듐 전해액 제조방법 및 바나듐 전해액을 포함하는 전지 Download PDFInfo
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- WO2022215822A1 WO2022215822A1 PCT/KR2021/017147 KR2021017147W WO2022215822A1 WO 2022215822 A1 WO2022215822 A1 WO 2022215822A1 KR 2021017147 W KR2021017147 W KR 2021017147W WO 2022215822 A1 WO2022215822 A1 WO 2022215822A1
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- Prior art keywords
- vanadium
- electrolyte
- reaction
- vanadium compound
- compound
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 299
- 229910052720 vanadium Inorganic materials 0.000 title claims abstract description 272
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 title claims abstract description 272
- 238000000034 method Methods 0.000 title claims abstract description 158
- 150000003682 vanadium compounds Chemical class 0.000 claims abstract description 259
- 238000006722 reduction reaction Methods 0.000 claims abstract description 134
- 238000002360 preparation method Methods 0.000 claims abstract description 17
- 239000006227 byproduct Substances 0.000 claims abstract description 16
- 239000002904 solvent Substances 0.000 claims description 264
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 193
- 238000006243 chemical reaction Methods 0.000 claims description 186
- 239000000654 additive Substances 0.000 claims description 151
- 230000000996 additive effect Effects 0.000 claims description 141
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 131
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 118
- 239000003638 chemical reducing agent Substances 0.000 claims description 90
- 238000004519 manufacturing process Methods 0.000 claims description 83
- 238000001816 cooling Methods 0.000 claims description 67
- 239000002253 acid Substances 0.000 claims description 64
- 229910052757 nitrogen Inorganic materials 0.000 claims description 54
- 230000001603 reducing effect Effects 0.000 claims description 54
- 239000008151 electrolyte solution Substances 0.000 claims description 53
- -1 Molybdenum Metal Nitride Chemical class 0.000 claims description 43
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- 239000000376 reactant Substances 0.000 claims description 33
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- 229910001873 dinitrogen Inorganic materials 0.000 claims description 23
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 239000002184 metal Substances 0.000 claims description 20
- 239000000243 solution Substances 0.000 claims description 19
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical group [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 18
- 239000007864 aqueous solution Substances 0.000 claims description 16
- 229910052782 aluminium Inorganic materials 0.000 claims description 12
- 238000006297 dehydration reaction Methods 0.000 claims description 12
- 229910052710 silicon Inorganic materials 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 11
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- 229910052791 calcium Inorganic materials 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 229910052763 palladium Inorganic materials 0.000 claims description 6
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- 229910052707 ruthenium Inorganic materials 0.000 claims description 6
- 229910052697 platinum Inorganic materials 0.000 claims description 5
- 230000018044 dehydration Effects 0.000 claims description 4
- MCPTUMJSKDUTAQ-UHFFFAOYSA-N vanadium;hydrate Chemical compound O.[V] MCPTUMJSKDUTAQ-UHFFFAOYSA-N 0.000 claims description 4
- QIJNJJZPYXGIQM-UHFFFAOYSA-N 1lambda4,2lambda4-dimolybdacyclopropa-1,2,3-triene Chemical compound [Mo]=C=[Mo] QIJNJJZPYXGIQM-UHFFFAOYSA-N 0.000 claims description 3
- 229910039444 MoC Inorganic materials 0.000 claims description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
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- 229910052785 arsenic Inorganic materials 0.000 claims description 3
- GPBUGPUPKAGMDK-UHFFFAOYSA-N azanylidynemolybdenum Chemical compound [Mo]#N GPBUGPUPKAGMDK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052788 barium Inorganic materials 0.000 claims description 3
- 229910052793 cadmium Inorganic materials 0.000 claims description 3
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
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- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
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- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 claims description 3
- 229910000476 molybdenum oxide Inorganic materials 0.000 claims description 3
- PDKHNCYLMVRIFV-UHFFFAOYSA-H molybdenum;hexachloride Chemical compound [Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Mo] PDKHNCYLMVRIFV-UHFFFAOYSA-H 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
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- AMWVZPDSWLOFKA-UHFFFAOYSA-N phosphanylidynemolybdenum Chemical compound [Mo]#P AMWVZPDSWLOFKA-UHFFFAOYSA-N 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 229910052718 tin Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- 229910052726 zirconium Inorganic materials 0.000 claims description 3
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- MJKYCJBIICJHRD-UHFFFAOYSA-N pentane-2,4-dione;vanadium Chemical compound [V].CC(=O)CC(C)=O MJKYCJBIICJHRD-UHFFFAOYSA-N 0.000 description 2
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G31/00—Compounds of vanadium
-
- 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
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to a method for manufacturing a vanadium electrolyte and a battery including a vanadium electrolyte, and more particularly, it is possible to control the reduction reaction rate of a vanadium compound, and to omit the separation and recovery process or to provide a reduction effect because by-products are not generated. It relates to a method for producing a vanadium electrolyte that can reproducibly provide a single process of chemical reduction and a battery including the vanadium electrolyte.
- 'ESS' Energy Storage System
- Representative strategic storage technologies include pumped-water power generation, compressed air storage, and physical storage methods including flywheels; electromagnetic methods including superconducting energy storage, supercapacitors; chemical methods including flow batteries and lithium-ion batteries; and the like.
- the vanadium redox flow battery has advantages such as low cost, large capacity, long lifespan, and stability.
- the demonstration has been completed in power plants, new and renewable energy ESS linkage systems, and smart grid ESS construction. have.
- An example of the electrolyte constituting the flow battery is a vanadium electrolyte.
- a vanadium 3.5-valent electrolyte containing the same vanadium tetravalent and trivalent ions is most often used. Therefore, it is necessary to develop a process for producing a vanadium 3.5 electrolyte solution that is simple, low-cost, high-quality and easy to mass-produce.
- the existing electrolyte manufacturing process is a multi-stage process mainly using a chemical reaction method and an electrolysis method together.
- V 2 O 5 is usually dissolved in a sulfuric acid solution to form a vanadium pentavalent ion, which is reduced to a vanadium tetravalent ion (VO 2+ ) using a reducing agent, etc.
- a reducing agent etc.
- the types of reducing agents proposed in the existing process include oxalic acid and methanol.
- the oxalic acid (C 2 H 2 O 4 ) is a typically used reducing agent.
- vanadium, sulfuric acid and water are mixed in consideration of heat generation, and then oxalic acid was added to proceed with the stirring reaction.
- the temperature of the reactor is maintained at 90°C, it takes about 4 hours, and the reaction formula is as follows.
- Methanol has a much slower reaction rate than oxalic acid, so its use is limited.
- the reducing agent proceeds only from pentavalent to tetravalent reaction.
- some of the unreacted reducing agent or CO 2 gas generated by the oxidation reaction of the reducing agent is dissolved in the electrolyte, and these unreacted / side reactants cause serious deterioration of the electrolyte properties.
- vanadium tetravalent electrolyte is primarily prepared as above, 1/3 of which is put in the anode tank and 1/3 is put in the cathode tank and electrolyzed to obtain pentavalent and trivalent electrolytes, respectively, and the first By merging 1/3 of the tetravalent electrolyte remaining after manufacturing and 1/3 of the vanadium trivalent electrolyte generated by secondary preparation (electrolysis), a vanadium 3.5 valence electrolyte can be prepared.
- the conventional process has disadvantages of, first, that it undergoes a multi-step process, second, a factor of deterioration of electrolyte performance in the primary manufacturing, and third, an inevitable loss of electrolyte of 33%.
- electrolysis in addition to the initial investment cost of the electrolysis facility, continuous consumable costs such as electrodes and separators are incurred, and there is no clear advantage in terms of mass production facility construction. It was not easy to meet competitive unit prices.
- a vanadium 3.3 to 3.7 electrolyte solution is prepared without electrolysis by using a noble metal catalyst such as Ru, Pd, or Pt in an organic reducing agent including formic acid.
- a noble metal catalyst such as Ru, Pd, or Pt
- the 3.3 to 3.7 vanadium electrolyte refers to an electrolyte containing vanadium tetravalent and trivalent ions in the same molar ratio, unless otherwise specified.
- this method still requires process improvement in that it uses an organic acid-based reducing agent, there is a risk that some noble metal catalysts that degrade battery performance may remain in the electrolyte, and the catalysts used are mostly rare metals. .
- a technology for preparing a vanadium 3.5 electrolyte solution using a single reactor of a non-catalytic chemical reaction method using a hydrazine compound has been recently developed. Specifically, when a pentavalent vanadium compound is reduced to a hydrazine compound near the boiling point of the electrolyte under heating conditions without a separate catalyst and step-by-step process, a high-purity vanadium electrolyte solution without by-products can be prepared.
- the present invention provides a method for producing a vanadium electrolyte that can control the reduction reaction rate of a vanadium compound in the production of a vanadium electrolyte, omit a by-product separation and recovery process, and maximize reaction efficiency aim to do
- Another object of the present invention is to provide a method for producing a vanadium electrolyte solution capable of producing a high-yield and high-quality electrolyte while providing the reproducibility of the production process as a single process of chemical reduction.
- Another object of the present invention is to provide a battery including the vanadium electrolyte prepared by the method for preparing the vanadium electrolyte.
- a second step of reducing the tetravalent vanadium compound to a 3.3 to 3.7 vanadium compound, wherein the reaction rate in at least one reduction reaction selected from the reduction reaction of the first step and the reduction reaction of the second step is reduced It provides a method for producing a vanadium electrolyte, characterized in that the.
- the redox additive may dehydrate the acid to form an aqueous solution and then oxidize the nitrogen-based reducing agent while reducing itself to generate nitrogen gas.
- the redox additive is molybdenum metal, molybdenum oxide (MoxOy), molybdenum nitride (MoxNy), molybdenum chloride (MoxCly), molybdenum sulfide (MoxSy), molybdenum phosphide (MoxPy), Molybdenum Carbide (MoxCy), Molybdenum Metal Oxide (MoxMyOz), Molybdenum Metal Nitride (MoxMyNz), Molybdenum Metal Chloride (MoxMyClz), Molybdenum Metal Sulfide (MoxMySz), Molybdenum Metal Phosphide ( MoxMyPz) and molybdenum metal carbide (MoxMyCz) may be at least one selected from the group consisting of.
- MoxOy molybdenum oxide
- MoxNy molybdenum chloride
- MoxSy mo
- the metal of the redox additive is Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Mg, Mn, Na, Ni, Pb, Si, Sn, Ti, Zn, Au, Ag , Pt, Ru, Pd, Li, Ir, W, Nb, Zr, Ta, Ge, and a species or a plurality of species selected from In may be a metal forming an alloy, wherein x and y (x / y) or x, y and z (x/y/z) may independently be integers from 0 to 1.
- the redox additive may be included in an amount of 0.1 to 1.6 parts by weight based on 100 parts by weight of the pentavalent vanadium compound.
- the nitrogen-based reducing agent may be included in an amount of 10 to 35 parts by weight based on 100 parts by weight of the vanadium compound.
- a ratio of the molar concentration (M; mol/L) of the pentavalent vanadium compound and the nitrogen-based reducing agent may be 1:0.1 to 1.6.
- the acid may be at least one selected from sulfuric acid, hydrochloric acid, nitric acid and acetic acid, and the concentration of proton ions from the acid may be 1 to 20 moles per 1 mole of the vanadium compound.
- the second step may be performed at 70 to 120 °C.
- the pentavalent vanadium compound may be a low-grade compound having a purity of 90% or more and less than 99.9%, or a high-grade compound having a purity of 99.9% or more.
- It may include the step of filtering after the first step or after the second step.
- the vanadium compound produced in the second step is cooled to room temperature or less, and then water is added in an excess of the amount previously added, and the reaction solution is filtered to reduce the reaction rate in the reduction reaction.
- the excess amount of water may be in the range of 42 to 44 moles based on the composition of 1.6 moles of vanadium and 4.0 moles of sulfuric acid.
- the first step water is used in an amount of 5 to 15 moles per 1 mole of the vanadium compound, reacted at 100° C. or higher to form a vanadium compound, and then water is added in an excess of the amount previously added, and the reduced vanadium compound is added to -25 to 20
- the reaction rate in the reduction reaction can be reduced by cooling to °C and then circulating the reaction solution under -25 to 40 °C.
- water is used in an amount of 5 to 15 moles per 1 mole of the vanadium compound, reacted at 100 ° C. or higher to form a vanadium compound, and then the reduced vanadium compound is cooled to -25 to 20 ° C. It is possible to reduce the reaction rate in the reduction reaction by introducing an excess and circulating the reaction solution under -25 to 40 °C.
- (D) reducing the tetravalent vanadium compound to a 3.3 to 3.7 vanadium compound while the self-reduced product is oxidized by heating the reactant; includes,
- the nitrogen-based reducing agent provides a method for producing a vanadium electrolyte, characterized in that the total amount is added to the step (A) or divided into steps (A) and (D).
- the redox additive is characterized in that by-products derived from the redox additive are not generated by participating in the reaction in an aqueous solution state by a dehydration reaction with an acid.
- the step (D) may be performed by applying the reduction reaction time of the vanadium compound calculated by substituting the reaction temperature of 70 to 120° C. and the amount of the redox additive into Equation 1 below.
- a first step of forming a reduced vanadium compound by reacting a vanadium compound, a reducing agent, and an acid at 100° C. or higher in an exclusive solvent of 5 to 15 moles per 1 mole of the vanadium compound;
- a method for producing a vanadium electrolyte comprising a third step of circulating filtering the cooled vanadium electrolyte at a condition of -25 to 40 °C.
- the present invention provides a vanadium electrolyte prepared by the above-described method.
- the present invention provides a redox flow battery comprising the above-described vanadium electrolyte.
- the vanadium electrolyte may be included in the anode and the cathode.
- impurities can be effectively reduced, thereby providing a high-purity vanadium electrolyte.
- the battery containing the vanadium electrolyte can be applied to all fields in which the vanadium redox flow battery is used, such as renewable energy, smart grid, and power plants. It works.
- 1 is a graph showing the temperature change for each reduction reaction time period at the sulfuric acid flow rate of 240 ml/hr and 480 ml/hr of Example.
- FIG. 3 is a graph showing the reduction reaction rate of the vanadium compound as the oxidation number of the vanadium ion for each input amount of the redox additive in Examples and Comparative Examples, thereby confirming the effect of the redox additive on the reduction reaction rate and reduction amount.
- FIG. 5 is a graph showing the discharge capacity per cycle of the redox flow battery using the vanadium electrolyte for the positive electrode and the negative electrode according to the input amount of the redox additive of Examples and Comparative Examples.
- FIG. 6 is a graph showing the energy efficiency of a battery including a vanadium electrolyte for each input amount of the redox additive of Examples and Comparative Examples.
- FIG. 7 is a graph showing the reaction rate results according to the content ratio of the exclusive solvent and the after solvent in the first step of performing the reduction reaction as an embodiment of the present invention.
- FIG. 8 is a graph of the charging capacity according to the content ratio of the exclusive solvent and the after solvent of FIG. 7 .
- FIG. 9 is a graph of the discharge capacity according to the content ratio of the exclusive solvent and the after solvent of FIG. 7 .
- FIG. 10 is a graph of energy efficiency according to the content ratio of the exclusive solvent and the after solvent of FIG. 7 .
- FIG. 11 is an image showing reaction results when the exclusive solvent of FIG. 7 is used in an amount less than 5 times the number of moles of vanadium.
- FIG. 12 is a device diagram schematically illustrating an apparatus configuration and a process flow diagram for preparing an electrolyte according to an embodiment.
- a range of “5 to 10” includes the values of 5,6,7,8,9 and 10, as well as any subranges such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc. and any value between integers that are appropriate for the scope of the recited ranges, such as 5.5, 6.5, 7.5, 5.5 to 8.5, and 6.5 to 9, and the like.
- ranges from 10 to 30% include values of 10%, 11%, 12%, 13%, etc. and all integers up to and including 30%, as well as within the range of stated ranges such as 10.5%, 15.5%, 25.5%, etc. It will be understood to include any value between valid integers.
- the present inventors provide a first step of reducing reaction to a tetravalent vanadium compound by adding a pentavalent vanadium compound and water, and then sequentially adding a nitrogen-based reducing agent and an acid;
- a 'nitrogen-based reducing agent' used for the reduction of a vanadium raw material
- the term "redox additive" used in the present description provides reproducibility in the manufacturing process because it assists the vanadium ion reducing power of the nitrogen-based reducing agent and does not participate in the reduction amount, and secures the selectivity of the vanadium raw material as well as the electrolyte solution. It is preferable to select a type that is included in the battery to improve battery performance.
- the vanadium raw material selectivity means that even a vanadium compound of the same purity is not limited by a fine quality difference that may occur depending on the vanadium origin or purification method.
- the reducing power refers to the rate of a reduction reaction unless otherwise specified. Specifically, since reductions are sequentially performed in the order of increasing reducing power, reduction first means that the reduction reaction rate is fast. If it is first reduced and has a potential value of self-oxidation upon reduction of a subsequent material, the input amount of the first reduced material may affect the control of the reduction reaction rate of the subsequently reduced material.
- the redox additive of the present disclosure has an electrochemical/mechanical potential range in which the reduction reaction rate is faster than that of the vanadium compound and is first reduced, and then self-oxidized while reducing the vanadium compound, so the electrolysis process is omitted and the chemical process
- the reduction reaction rate of the vanadium compound can be controlled because the amount of the redox additive directly affects the reducing power of the vanadium compound.
- the redox additive of the present disclosure may satisfy the correlation between the input amount M a of the redox additive and the reduction reaction rate t R of the vanadium compound expressed by Equation 1 below.
- t R is the reaction time (min)
- A is the rate constant
- B is the concentration constant
- Ma is the input amount (g) of the redox additive
- Mv is the input amount (g) of the vanadium compound.
- Equation 1 can be obtained as a statistical approximation of a regression analysis technique for experimental data.
- the constants do not have any special physical meaning, but the constant A is closely related to the reduction rate, and the constant B is closely related to the concentration of vanadium/sulfuric acid/solvent/redox additive, so they are named as rate constants and concentration constants, respectively. do.
- Equation 1 can be obtained as a statistical approximation of a regression analysis technique for experimental data.
- the above description does not contain any special physical meaning, but the constant A is closely related to the reduction rate, so it is called a rate constant, and may be, for example, -2.233.
- the constant B is closely related to the concentration of vanadium, sulfate solvent, and redox additive, so it is named as a concentration constant and may be, for example, -3.8086.
- Equation 1 it is possible to control the process by predicting the reduction reaction rate of vanadium according to the input amount of the redox additive, thereby providing reproducibility of the manufacturing process and securing the vanadium raw material selectivity, thereby improving battery performance.
- Equation 1 shows that when the reaction temperature and the vanadium compound (raw material)/sulfuric acid/water (solvent) concentration are constant, the reaction rate (t R ) and the input amount (Ma) of the redox additive are proportionally negative, It can be seen in FIG. 2 below that the Renius equation is followed.
- the reduction reaction rate of the vanadium compound can be predicted according to the amount of the redox additive added, so process control is possible, and the reproducibility of the manufacturing process and the selectivity of the vanadium raw material can be secured, resulting in improved battery performance.
- the redox additive may be an ionic metal having solubility in a vanadium electrolyte, or a compound derived from the ionic metal.
- the ionic metal may be a reversible transition metal capable of repeatedly serving as an intermediate mediator of the redox reaction between the reducing agent and vanadium.
- the redox additive is characterized in that 1) the reduction rate is faster than that of vanadium ions, so that the reduced component has an electrochemical/mechanical potential to be oxidized by itself while reducing vanadium ions, and 2) redox between a nitrogen-based reducing agent and a vanadium compound. It has reversibility to repeatedly perform the role of an intermediate mediator of the reaction, and 3) The reduction reaction rate of the vanadium compound is shortened by adjusting the input amount of the redox additive according to the main component (metal) content of the redox additive contained in the vanadium compound. and control the reaction time.
- the ionic metal component which is the main component of the redox additive
- the battery performance can be maximized, but the reaction time can be shortened to within 8 hours.
- the ionic metal component may be selected from transition metals or salts thereof having a solubility of 0.1 ppm or more in a vanadium electrolyte.
- the raw material for vanadium may be a vanadium compound having a valence of 2.0 to 5.0, and at least a portion of the electrolyte may be a vanadium compound having a valence of 3.3 to 3.7.
- the vanadium raw material may be a low-grade compound having a purity of 90% or more and less than 99.9%, or a high-grade compound having a purity of 99.9% or more.
- the vanadium raw material may be, for example, a pentavalent vanadium compound or a tetravalent vanadium compound, the pentavalent vanadium compound may be at least one selected from V 2 O 5 , NH 4 VO 3 and NaVO 3 , and the tetravalent vanadium compound may be VOSO 4 • xH 2 O (where x is an integer from 1 to 6).
- the starting material for preparing the vanadium electrolyte includes a pentavalent or tetravalent vanadium compound, sulfuric acid, and a solvent, and the pentavalent or tetravalent vanadium compound is dehydrated with sulfuric acid by a nitrogen-based reducing agent to reduce the vanadium compound.
- the vanadium electrolyte may include a 3.3 to 3.7 vanadium compound.
- the 3.3 to 3.7 vanadium compound may be reduced from the vanadium compound using sulfuric acid, a reducing agent, and a solvent.
- the reduction reaction of the vanadium compound may be performed in an acidic solution containing sulfuric acid.
- the reduction reaction of the vanadium compound V 2 O 5 , the acidic solution H 2 SO 4 , and the nitrogen-based reducing agent N 2 H 4 ⁇ H 2 O may proceed as shown in Scheme 1 below.
- the vanadium compound having an oxidation number of 4.0 prepared through the reduction process according to Scheme 1 can form a specific compound with an acidic solution (hereinafter, also referred to as “acid”) and a reducing solvent (hereinafter also referred to as “solvent”),
- an acidic solution hereinafter, also referred to as “acid”
- a reducing solvent hereinafter also referred to as “solvent”.
- the solvent when it is water, it may be a compound containing VO 2+ , [VO(H 2 O) 5 ] 2+ or [VO(OH) 2 (H 2 O) 4 ] + ions.
- a vanadium compound having an oxidation number of 2.0 prepared through a reduction process can form a specific compound with an acid and a solvent.
- the solvent is water
- a vanadium compound having an oxidation number of 3.0 produced through a reduction process can form a specific compound with an acid and a solvent.
- the solvent is water
- V 3+ , [V(H 2 O) 6 ] 3+ , [V (OH)(H 2 O) 5 ] 2+ or [V(OH) 2 (H 2 O) 4 ] + ions may be included.
- a vanadium compound having an oxidation number of 5.0 prepared through a reduction process can form a specific compound with an acid and a solvent.
- the solvent is water
- VO 2 + , V 2 O 3 4+ , [VO 2 (H 2 O) ) 3 ] + or [V 2 O 3 (H 2 O) 8 ] 4+ ions may be included.
- the vanadium compound having an oxidation number of greater than 3.0 to less than 4.0 produced through a reduction process may consist of a mixture of a vanadium compound having an oxidation number of 3.0 and 4.0.
- V 3+ , [ V(H 2 O) 6 ] 3+ , [V(OH)(H 2 O) 5 ] 2+ and [V(OH) 2 (H 2 O) 4 ] + when the solvent is water, V 3+ , [ V(H 2 O) 6 ] 3+ , [V(OH)(H 2 O) 5 ] 2+ and [V(OH) 2 (H 2 O) 4 ] + , and VO 2 + , [VO(H 2 O) 5 ] 2+ or [VO(OH) 2 (H 2 O) 4 ] + may be a compound composed of a mixture of ions.
- the prepared vanadium compound having an oxidation number of 3.3 is VOSO 4 and V 2 (SO 4 ) 3 may be in a molar ratio of 6:5.5 to 6.5, and 3.5 is an oxidation number
- the vanadium compound having VOSO 4 and V 2 (SO 4 ) 3 may have a molar ratio of 2:0.5 to 1.5, and the vanadium compound having an oxidation number of 3.7 has a VOSO 4 and V 2 (SO 4 ) 3 ratio of 14:2.5. a molar ratio of ⁇ 3.5.
- nH 2 O in order to represent V3.3, V3.5, and V3.7 as molar ratios of tetravalent and trivalent ions, the description of nH 2 O is omitted, but does not mean that it does not include them.
- the redox additive may serve to promote the reduction reaction of the vanadium compound, and specifically, control the reduction reaction rate of the vanadium compound by the nitrogen-based reducing agent according to the input amount in the electrolyte of the vanadium redox flow battery. , and the correlation corresponding to Equation 1 described above is satisfied.
- Another embodiment of the present invention provides information on a vanadium electrolyte derived from a pentavalent vanadium compound.
- the pentavalent vanadium compound may be a low-grade or high-grade compound.
- the vanadium electrolyte may include 15 to 35 parts by weight of a nitrogen-based reducing agent along with sulfuric acid and a solvent of an appropriate weight based on 100 parts by weight of the vanadium contained in the pentavalent vanadium compound.
- the vanadium electrolyte can shorten the reduction reaction rate and secure reproducibility through control of the reaction time.
- the redox additive may or may not contain 0.1 ppm or more of the main metal component of the redox additive specifically.
- the process can be performed within 8 hours while maximizing the battery performance.
- the vanadium electrolyte may include a vanadium compound having a valence of 2.0 to 5.0, and particularly, at least a portion of the electrolyte solution may include a vanadium compound having a valence of 3.3 to 3.7.
- the 3.3 to 3.7 vanadium compounds may be reduced from the vanadium raw material using sulfuric acid, a reducing agent, ultrapure water, and the redox additive.
- the vanadium electrolyte may contain 15 to 35 parts by weight of the pentavalent hydrazine compound based on 100 parts by weight of the vanadium raw material.
- 16 parts by weight or more of N 2 H 4 are required based on 100 parts by weight of the vanadium raw material to reduce the pentavalent vanadium compound to tetravalent vanadium, and to reduce the pentavalent vanadium to 3.5 valent vanadium, based on 100 parts by weight of the vanadium raw material.
- N 2 H 4 needs 24 parts by weight or more.
- the redox additive is preferably adjusted so that Mo per 1 L of the electrolyte is around 270 ppm, and the amount of the redox additive can be adjusted according to the presence or absence of an ionic metal component, which is a main component of the redox additive, in the vanadium raw material.
- an ionic metal component which is a main component of the redox additive, in the vanadium raw material.
- Acid and solvent can be appropriately adjusted according to the type and purpose of the electrolyte.
- pentavalent vanadium when pentavalent vanadium is reduced to tetravalent vanadium, 17.5 parts by weight of N 2 H 4 ⁇ H 2 O compared to 100 parts by weight of V 2 O 5 raw material, H 2 SO 4 based on 98% concentration It may include 108 parts by weight or more, and 100 parts by weight or more of DIW.
- the vanadium electrolyte of the present invention may be, for example, V 2 O 5 of the pentavalent vanadium compound, based on 100 parts by weight of V 2 O 5 , 400 parts by weight or less of an acid, 38 parts by weight or less of a nitrogen-based reducing agent, and 700 parts by weight of a solvent It can be prepared by using not more than 1 part and 0.1 to 1.6 parts by weight of the redox additive, specifically, 100 to 400 parts by weight of an acid, 14 to 38 parts by weight of a nitrogen-based reducing agent, 300 to 700 parts by weight of a solvent, and 0.1 to 1.6 parts by weight of a redox additive. It can be prepared using parts.
- the nitrogen-based reducing agent may be, for example, hydrazine hydrate, specifically, hydrazine monohydrate, but is not limited thereto.
- the vanadium electrolyte may be prepared using 200 to 400 parts by weight of an acid, 14 to 30 parts by weight of a nitrogen-based reducing agent, 500 to 700 parts by weight of a solvent, and 0.2 to 1.6 parts by weight of a redox additive, more preferably 200 to 300 parts by weight of an acid, 20 to 30 parts by weight of a nitrogen-based reducing agent, 500 to 600 parts by weight of a solvent, and 0.2 to 1.2 parts by weight of a redox additive, and more preferably 250 to 300 parts by weight of an acid; It may be prepared by using 24 to 28 parts by weight of a nitrogen-based reducing agent, 500 to 550 parts by weight of a solvent, and 0.2 to 0.8 parts by weight of a redox additive. Within these ranges, the reaction time is shortened, the reaction efficiency is excellent, and a high-purity, high-quality vanadium electrolyte is prepared, and the charge/discharge capacity of the battery including the electrolyte is also improved.
- the redox additive may be included in an amount of 0.1 to 1.6 parts by weight based on 100 parts by weight of the V 2 O 5 raw material.
- the Mo content in the electrolyte is 1120 ppm
- the amount of MoO 3 added per 1L is 2.4 g
- the Mol% compared to the electrolyte may be 0.016 Mol%.
- reaction time may be, for example, 3 to 13 hours.
- the ratio of the pentavalent vanadium compound (V 2 O 5 ) to the molar concentration (M; mol/L) of the nitrogen-based reducing agent may be 1:0.1 to 1.6 or 1:0.2 to 0.4, and in this range, acid, solvent, By forming an appropriate molar concentration ratio with the redox additive, there is an advantage that the desired effect of the present invention is easily achieved.
- the ratio of molar concentrations (M; mol/L) of the pentavalent vanadium compound (V 2 O 5 ), acid, nitrogen-based reducing agent and redox additive is, for example, 1: 2 to 3: 0.2 to 0.4: 0.001 or more 0.25 Less than, specifically, 1: 2 to 3: 0.3 to 0.4: 0.001 or more and less than 0.05, more preferably 1: 2.3 to 2.7: 0.36 to 0.39: 1.002 or more and less than 0.02, even more preferably 1: 2.4 to 2.6: 0.37 to 0.38: 0.003 to 0.01, within this range, the reaction time is shortened, the reaction efficiency is excellent, and a high-purity and high-quality vanadium electrolyte is prepared, and the charge/discharge capacity of the battery including the electrolyte is also improved.
- the redox additive is, for example, 1 to 6000 ppm, preferably 10 to 3000 ppm, more preferably 50 to 1500 ppm, still more preferably 100 to 1000 ppm, most preferably 200 to 800 ppm in the vanadium electrolyte solution. can be included as
- the main component of the redox additive may be included in an amount of 1 ppm or more and less than 1500 ppm in the vanadium electrolyte after the production process of the vanadium electrolyte solution, such as a reaction and filtration process, is completed.
- the nitrogen-based reducing agent provides the reducing power of vanadium ions and at the same time does not participate in the reduction amount but is involved in the reduction rate. For example, even if 20 parts by weight or less of H 3 PO 4 known as a thermal stability additive is added to 100 parts by weight of the V 2 O 5 raw material when preparing the vanadium electrolyte, the reducing effect of the redox additive is not affected.
- H 3 PO 4 (NH 4 )H 2 PO 4 , (NH 4 ) 3 PO 4 such as PO 4 series materials, HCl, MgCl 2 , CaCl 2 chlorine-based materials, such as cationic surfactants, Even if 20 parts by weight or less of additives such as anionic surfactants, amphoteric surfactants, and nonionic surfactants are added to 100 parts by weight of V 2 O 5 raw material, the reducing effect of the redox additive is not affected, and the unique functions of various additives are not affected. Redox additives have no effect.
- a vanadium electrolyte derived from a tetravalent vanadium compound may also be a low-grade or high-grade compound.
- the vanadium electrolyte may be prepared by using 10 to 20 parts by weight of a nitrogen-based reducing agent together with an appropriate amount of an acid and a solvent based on 100 parts by weight of vanadium contained in the tetravalent vanadium compound, and a redox additive to the tetravalent vanadium compound. It may be included while adjusting the amount of the redox additive input according to the content of the ionic metal component.
- the main component of the redox additive may be included in an amount of 1 ppm or more and less than 1500 ppm in the vanadium electrolyte.
- the vanadium electrolyte is, for example, in the case of VOSO 4 among the tetravalent vanadium compounds, based on 100 parts by weight of VOSO 4 , 400 parts by weight or less of an acid, 25 parts by weight or less of a nitrogen-based reducing agent, 700 parts by weight or less of a solvent, and redox It can be prepared using 0.1 to 1.6 parts by weight of the additive, specifically 100 to 400 parts by weight of an acid, 1 to 25 parts by weight of a nitrogen-based reducing agent, 300 to 700 parts by weight of a solvent, and 0.1 to 1.6 parts by weight of a redox additive.
- the redox additive is, for example, 1 to 6000 ppm, preferably 10 to 3000 ppm, more preferably 50 to 1500 ppm, still more preferably 100 to 1000 ppm, most preferably 200 to 800 ppm in the vanadium electrolyte solution. can be included as
- the redox additive includes other additives for improving electrolyte performance, it provides a reducing power of vanadium ions, thereby contributing to the reduction rate without being involved in the reduction amount. For example, even if 20 parts by weight or less of H 3 PO 4 , which is known as a representative additive for improving temperature stability, is added relative to 100 parts by weight of V 2 O 5 raw material when preparing a vanadium electrolyte, the reducing effect of the redox additive is not affected. .
- H 3 PO 4 as an example, (NH 4 )H 2 PO 4 , (NH 4 ) 3 PO 4 such as PO 4 material, Cl-based material such as HCl, MgCl 2 , CaCl 2 , cationic interface
- NH 4 )H 2 PO 4 NH 4 ) 3 PO 4
- Cl-based material such as HCl, MgCl 2 , CaCl 2
- cationic interface Even if 20 parts by weight or less of substances such as activators, anionic surfactants, amphoteric surfactants, and nonionic surfactants are added relative to 100 parts by weight of V 2 O 5 raw material, the effect of the redox additive on the reducing agent is not affected, and at the same time The additive function of various additives is also not violated by redox additives.
- the method for preparing the above-described vanadium electrolyte includes, for example, a first step of reducing a pentavalent vanadium compound to a tetravalent vanadium compound as a vanadium compound; and a second step of reducing the tetravalent vanadium compound to a 3.3 to 3.7 vanadium compound, wherein a redox additive is added to at least one of the first step and the second step, and the redox additive is the second step. It may be composed of a material having a lower reducing power than the nitrogen-based reducing agent used to reduce the vanadium compound in the first step.
- the first step may include sequentially i) adding a pentavalent vanadium compound and water, ii) adding a nitrogen-based reducing agent, and iii) adding sulfuric acid, in this case, the process
- the nitrogen-based compound may be a hydrazine compound as a specific example.
- the hydrazine compound may be preferably added in the form of a hydrate or an aqueous solution, and it may be preferable when the hydrazine compound is at least 95 weight ratio by weight relative to 100 weight ratio of the hydrazine compound.
- the hydrazine compound was diluted to about 200 to 500 weight ratio of water relative to 100 weight ratio, and there is no specific ratio, but the total amount of water required for preparing the electrolyte should be the same.
- the rapid reaction rate can be gently controlled and the reaction can be carried out more stably, so that the reaction efficiency is excellent and a high-purity, high-quality vanadium electrolyte can be prepared.
- the hydrazine hydrate is preferably hydrazine monohydrate, and the hydrazine salt is preferably hydrazine sulfate.
- the nitrogen-based reducing agent may be added in the entire amount in the first step, or may be partially added to the first step and then dividedly added to the second step.
- 60 to 80% by weight of the total amount may be added in the first step, and 20 to 40% by weight may be added in the second step, and preferably 60 to 70% by weight in the first step and the second 30 to 40 wt% may be added in the step.
- the input method of the nitrogen-based reducing agent may be appropriately used among the input methods commonly used in the technical field to which the present invention pertains depending on the purpose or process condition of the vanadium electrolyte solution.
- the redox additive may dehydrate the sulfuric acid in the first step to form an aqueous solution and then oxidize the nitrogen-based reducing agent while reducing itself to generate nitrogen gas.
- the redox additive is molybdenum metal, molybdenum oxide (MoxOy), molybdenum nitride (MoxNy), molybdenum chloride (MoxCly), molybdenum sulfide (MoxSy), molybdenum phosphide (MoxPy), Molybdenum Carbide (MoxCy), Molybdenum Metal Oxide (MoxMyOz), Molybdenum Metal Nitride (MoxMyNz), Molybdenum Metal Chloride (MoxMyClz), Molybdenum Metal Sulfide (MoxMySz), Molybdenum Metal Phosphide ( MoxMyPz) and molybdenum metal carbide (MoxMyCz) may be at least one selected from the group consisting of.
- MoxOy molybdenum oxide
- MoxNy molybdenum chloride
- MoxSy mo
- the metal of the redox additive is Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Mg, Mn, Na, Ni, Pb, Si, Sn, Ti, Zn, Au, Ag , Pt, Ru, Pd, Li, Ir, W, Nb, Zr, Ta, Ge, and a species or a plurality of species selected from In may be a metal forming an alloy, wherein x and y (x / y) or x, y and z (x/y/z) may independently be integers from 0 to 1.
- the redox additive may be used to reduce the tetravalent vanadium compound in the second step in a dehydrated aqueous solution state with sulfuric acid.
- the redox additive converts the tetravalent vanadium compound into a 3.3 to 3.7 vanadium compound, preferably a 3.4 to 3.6 vanadium compound, and most preferably a tetravalent vanadium compound while self-oxidizing to an aqueous solution formed through a dehydration reaction with sulfuric acid. 3.5 is reduced to a vanadium compound, and in this case, there is an advantage in that a high-purity, high-quality vanadium electrolyte is prepared.
- the second step may preferably be heated to 70 to 120 ° C, more preferably 80 to 115 ° C, more preferably 90 to 110 ° C, even more preferably 100 to 110 ° C, In this case, the reaction time is shortened and the reaction efficiency is excellent, but there is an advantage in that a high-purity, high-quality vanadium electrolyte is prepared.
- the heating time may be 12 hours or less, preferably 1 hour to 10 hours, more preferably 2 hours to 8 hours, still more preferably 3 to 8 hours, most preferably 4 to 8 hours time, and in this case, there is an advantage in that a high-purity, high-quality vanadium electrolyte solution is prepared while having excellent reaction efficiency.
- the first step and the second step may be performed under atmospheric pressure, for example, but may be pressurized or reduced as necessary within a range satisfying the above-described reaction conditions.
- the electrolyte preparation method may include a process of filtration after the first step or after the second step, more preferably, the first step after the first filtration and the second step after the second filtration.
- a process of filtration after the first step or after the second step more preferably, the first step after the first filtration and the second step after the second filtration.
- the filtration may be performed by gravity filtration using gravity, pressure filtration operated by applying pressure to the upper layer of the filtration means, and reduced pressure filtration operated by applying reduced pressure to the lower layer of the filtration means.
- the filtration can use a hydrophilic filtration means while having acid resistance having a pore size of 0.2 to 10 ⁇ m.
- the process time or pressure load increases, so that competitiveness compared to quality may be lowered.
- it exceeds 10 ⁇ m the filtration effect may be insignificant.
- the pentavalent vanadium compound is preferably V 2 O 5
- the tetravalent vanadium compound is preferably VOSO 4
- the 3.3 to 3.7 vanadium compound is preferably VOSO 4 and V 2 (SO 4 ) 3 Mixing may be performed, and in this case, there is an advantage in that a high-purity, high-quality vanadium electrolyte is prepared.
- the electrolyte preparation method may include a catalyst together with a redox additive in the first step or the second step, if necessary, and promote the reduction reaction.
- the catalyst serves as a catalyst in the first step, particularly in the second step, and is followed by a separation process from the electrolyte after performing the catalyst role. After the catalyst is added to the first step and filtered in the second step after the reaction is completed, the catalyst is added to the second step after the first step filtration and then filtered again in the second step after the reaction is completed, or the reactant is introduced into the catalyst facility It can be introduced and used in a way that a reduction reaction is possible.
- the main component of the catalyst may be a metal such as Pt, Pd, Ru, or the like, and may be a typical Pt catalyst.
- the Pt catalyst is not particularly limited if it is a Pt catalyst commonly used in the technical field to which the present invention pertains.
- the method for preparing a vanadium electrolyte includes: (A) preparing a reaction mixture by adding a pentavalent vanadium compound to a solvent and then adding a nitrogen-based reducing agent; (B) reducing the pentavalent vanadium compound to a tetravalent vanadium compound while performing a dehydration reaction by adding sulfuric acid and a redox additive to the reaction mixture; (C) generating a self-reduced product while the dehydration reactant oxidizes the nitrogen-based reducing agent to generate nitrogen gas; and (D) reducing the tetravalent vanadium compound to a 3.3 to 3.7 vanadium compound while the self-reduced product is oxidized by heating the reactant; Including, the nitrogen-based reducing agent may be added to the whole amount in step (A) or divided into steps (A) and (D).
- the redox additive includes an aqueous vanadium redox flow electrolyte or an electrolyte for a non-aqueous vanadium redox flow such as vanadium acetylacetone, and the preparation and use of the same As long as the vanadium redox flow battery is mechanically and electromagnetically driven, it can be used without any particular limitation.
- the vanadium electrolyte may be included in both the anode and the cathode.
- the reaction rate can be shortened by promoting the reduction reaction, and the energy transfer material of the additive material between vanadium ions that can be activated by electric field energy when the vanadium redox flow battery is operating It is estimated that by contributing to the electron mobility of vanadium ions, it will contribute to the improvement of the charge/discharge capacity and energy efficiency of the battery.
- the redox additive needs to be added at a certain concentration or higher to improve the reaction rate, but if it is added in excess of a certain concentration, the force that interferes with the diffusion of vanadium ions increases due to an increase in viscosity due to excessive mutual attraction between the vanadium ions and the redox additive. This may negatively affect the charge/discharge capacity and energy efficiency.
- the redox additive is preferably included in a concentration of about 0.2 to 2 mol% in the electrolyte when considering the improvement of the reaction rate and the improvement of the battery performance.
- concentration of the redox additive is contained in 0.2 mol% or more, there is a substantial effect on the reaction rate and performance improvement, and when it exceeds 2 mol%, the above-mentioned negative effects may occur.
- the redox additive may be included in the electrolyte in an amount of preferably 0.2 to 1.0 mol%, more preferably 0.2 to 0.8 mol%.
- the redox additive participates in the reaction in an aqueous solution state by dehydration reaction with sulfuric acid, a byproduct derived from the redox additive is not generated.
- Step (D) may be performed by applying the reduction reaction time of the vanadium compound calculated by substituting the reaction temperature of 70 to 120° C. and the amount of the redox additive into Equation 1 above.
- the vanadium electrolyte prepared with the redox additive of the present invention had a current density of 100 mA/cm 2 , a discharge cut-off voltage of 0.8 V, a charge cut-off voltage of 1.6 V, and a flow rate of 180 ml/min.
- the charging capacity and the charging/discharging capacity within the system can be improved by an average of 5% or more, preferably by 6.5% or more per cycle compared to the absence of the corresponding redox additive.
- energy efficiency may be improved by 0.5% or more, preferably by 1% or more.
- the charge capacity means a state in which charges are accumulated up to the charge cut-off voltage
- the charge/discharge capacity means a state in which the charge is emptied up to the discharge cut-off voltage
- energy efficiency means the charge capacity compared to the charge/discharge capacity.
- the redox additive of the present invention can provide an electrolyte having improved battery capacity and energy efficiency.
- the above-described method for producing the above-described vanadium electrolyte is, for example, a solvent is dividedly added in the production of the vanadium electrolyte, and when the input content and input timing are adjusted, an optimization process having the effect of improving the reaction rate and reducing impurities can be provided. confirmed that.
- the solvent used in the present description is used to reduce 3.3 to 3.7 into a vanadium compound through the reduction reaction of the vanadium compound, and unless otherwise specified, may be purified water, preferably deionized water or ultrapure distilled water is used. desirable.
- the method for preparing a vanadium electrolyte of the present invention comprises: a first step of reacting a vanadium compound, a reducing agent, and an acid in an exclusive solvent of 5 to 15 moles per 1 mole of the vanadium compound to form a reduced vanadium compound; a second step of cooling the reduced vanadium compound after the completion of the reaction; a third step of adding a post solvent after the cooling step; and a fourth step of filtering the reaction solution after the post-solvent input step, and it is possible to secure the reproducibility of the manufacturing process while shortening the overall reaction time, and to improve the reaction efficiency to reduce impurities, in this case
- the chemical reaction process in a single reactor enables mass production of electrolyte, shortening the reduction process time, maximizing reaction efficiency, and achieving high yield and high-quality electrolyte production, as well as improving the battery performance of batteries containing the electrolyte.
- the solvent used for the reduction reaction of vanadium in the first step is referred to as an exclusive solvent, and the solvent added to match the composition of the vanadium obtained by the reduction reaction described above in the third step, which is a subsequent step. is referred to as a post-solvent.
- a vanadium compound, a reducing agent, and an acid are reacted in an amount of 5 to 15 moles of an exclusive solvent per 1 mole of the vanadium compound to form a reduced vanadium compound.
- the exclusive solvent may be, for example, deionized water, ultrapure distilled water, or a mixture thereof.
- the amount of the exclusive solvent used is small, it is preferable to improve the reaction rate and reduce impurities.
- the reduction reaction can be performed more rapidly due to increased interaction between reactants including the vanadium compound, the reducing agent, and the reaction accelerator.
- the ion ratio of the acid to the vanadium compound increases, so that the ionization of the vanadium compound may be much faster.
- the reduction reaction thereof occurs when the vanadium pentavalent ion has at least 5 moles of water molecules per 1 mole of the vanadium compound. It is converted into a solid tetravalent compound in the form
- the solid tetravalent compound can be converted into 1 mol of liquid vanadium trivalent compound when there is 1 mole of water molecules per 1 mole. As a theoretical value, at least 5.5 moles are required, but an additional solvent will be required in the actual reaction process. Therefore, if at least 6 moles of exclusive solvent, which is more than 5.5 moles per mole of the vanadium compound, is added, liquid or slush type 3.5 vanadium The compound is obtained.
- a 3.5-valent vanadium compound is obtained by using the above-described slush-type 3.5-valent vanadium compound, tetravalent vanadium and its impurities present in a solid state in the slush are not removed even if a later solvent is added, but are not removed in the 3.5-valent vanadium compound. As it remains, it temporarily affects the surface of the electrode and membrane, and may show abnormal behavior such as noise at the start of initial charge/discharge.
- the liquid phases 3.3 to 3.7 as described above play a role in finally matching the composition of the electrolyte solution, and the amount of the after solvent input depends on the composition ratio of vanadium and sulfuric acid added as raw materials.
- the solvent requires about 42 to 44 mol unless otherwise specified.
- the amount of the post solvent may be added by limiting the amount of the exclusive solvent (A mole).
- the above-described exclusive solvent and the after solvent may implement an optimized vanadium electrolyte manufacturing process if the content of the exclusive solvent and the after solvent are maintained within a specific ratio range.
- the vanadium electrolyte may include a 2.0 to 5.0 vanadium compound, and at least a portion of the electrolyte may be a 3.3 to 3.7 vanadium compound.
- the 3.3 to 3.7 vanadium compounds may be reduced from the vanadium compound using an acid, a reducing agent, and a solvent.
- the vanadium compound a low-grade or high-grade compound may be used.
- the low-grade vanadium compound refers to a vanadium compound having a purity of 99% or more, specifically 99% or more and less than 99.9%, and a relatively excessive amount of impurities.
- the high-grade vanadium compound refers to a vanadium compound having a purity of 99.9% or more and containing a relatively small amount of impurities.
- the low-grade vanadium compound or high-grade vanadium compound a commercially available product can be used as long as it follows the definition of the present disclosure, and when a low-grade vanadium compound is used, there is an advantageous effect on manufacturing cost, etc., and when a high-grade vanadium compound is used, advantageous effects such as performance can perform
- the vanadium compound used in the preparation of the vanadium electrolyte in the present description may be a pentavalent vanadium compound or a tetravalent vanadium compound.
- the pentavalent vanadium compound may be, for example, V 2 O 5
- the tetravalent vanadium compound may be, for example, VOSO 4 ⁇ xH 2 O.
- the 3.3 to 3.7 vanadium compound may be a mixture of VOSO 4 and V 2 (SO 4 ) 3 .
- the vanadium electrolyte solution having an oxidation number of 2.0 obtained through the reduction reaction can form a specific compound with an acid and a solvent.
- the solvent is water
- V 2+ , [V(H 2 O) 6 ] 2+ ions are compound may be included.
- the vanadium electrolyte solution having an oxidation number of 3.0 obtained through the reduction reaction can form a specific compound with an acid and a solvent, for example, when the solvent is water, V 2+ , [V(H 2 O) 6 ] 3+ , [ V(H 2 O) 5 ] 2+ or [V(OH) 2 (H 2 O) 4 ] + ions may be included.
- the vanadium electrolyte solution having an oxidation number of 4.0 obtained through the reduction reaction may form a specific compound with an acid and a solvent.
- the solvent is water
- V 2+ , [V(H 2 O) 5 ] 2+ or [ V(OH) 2 (H 2 O) 4 ] + ions may be included.
- the vanadium electrolyte solution having an oxidation number of 5.0 obtained through the reduction reaction can form a specific compound with an acid and a solvent.
- a solvent for example, when the solvent is water, VO 2+ , [VO 2 (H 2 O) 4 ] + ions are compound may be included.
- the vanadium electrolyte solution having an oxidation number of greater than 3.0 and less than 4.0 obtained through the reduction reaction may consist of a mixture of a vanadium compound having an oxidation number of 3.0 and 4.0.
- the solvent is water
- a compound consisting of a mixture of VO 2+ , [VO 2 (H 2 O) 4 ] + ions can
- the vanadium electrolyte solution having an oxidation number of 3.3 obtained when the acid is a sulfuric acid series and the solvent is water through the reduction reaction has a molar ratio of VOSO 4 and V 2 (SO 4 ) 3 of 6:6 to 9, or 6: It may be a molar ratio of 6 to 8, and the vanadium electrolyte solution having an oxidation number of 3.5 may have a molar ratio of VOSO 4 and V 2 (SO 4 ) 3 of 2:0.5 to 1.5, or a molar ratio of 2:0.8 to 1.2,
- the ratio of VOSO 4 and V 2 (SO 4 ) 3 may be a molar ratio of 14:1 to 5, or a molar ratio of 14:2 to 4.
- the vanadium electrolyte solution having an oxidation number of 3.3, VOSO 4 and V 2 (SO 4 ) 3 may be in a molar ratio of about 6:7, and the oxidation number of 3.5 is
- the vanadium electrolyte solution having VOSO 4 and V 2 (SO 4 ) 3 may have a molar ratio of about 2:1, and in the vanadium electrolyte solution having an oxidation number of 3.7, the ratio of VOSO 4 and V 2 (SO 4 ) 3 is about 14:3.
- the term "about” refers to a value including a margin of error of ⁇ 0.5 from the reference value.
- the reducing agent may be at least one hydrazine compound selected from the group consisting of hydrazine anhydride, hydrates thereof, and salts thereof.
- the reducing agent may include 15 to 35 parts by weight of the hydrazine compound based on 100 parts by weight of the vanadium compound. For example, when reducing pentavalent vanadium to tetravalent vanadium, 16 parts by weight or more of the hydrazine compound is required based on 100 parts by weight of vanadium, and 24 parts by weight or more of the hydrazine compound is required when reducing pentavalent vanadium to 3.5 vanadium. Within this range, the reaction time is shortened, the reaction efficiency is excellent, and a high-purity, high-quality vanadium electrolyte is prepared, and the discharge capacity of the battery including the electrolyte is also improved.
- Deionized water or ultrapure distilled water may be used as the exclusive solvent and the after-solvent, and the exclusive solvent may be added in an amount of 5 to 15 moles, specifically, 8 to 15 moles per 1 mole of the vanadium compound.
- an electrolyte having a composition of 1.6 mol vanadium, 4.0 mol sulfuric acid, and 43 mol mol 10 to 24 mol, preferably 13 to 24 mol of the exclusive solvent is added, and 19 to 33 mol, preferably 19 to 30 moles may be added.
- the reaction time is shortened, the reaction efficiency is excellent, and impurities are reduced, so that a high-purity and high-quality vanadium electrolyte is prepared, and the discharge capacity of a battery including the electrolyte is also improved.
- the order of mixing the reactants may vary, the most preferred method is to administer the solvent, the vanadium compound, the hydrazine compound, and the acid to the reactor in the order of the stirrer.
- the exclusive solvent may be injected in a certain amount in divided portions. For example, it is also possible to dilute and administer a part of the solvent in the exclusive solvent with the hydrazine compound, or to inject the solvent and the vanadium compound and then pour the solvent to wash the vanadium compound attached to the inlet into the reactor.
- the vanadium compound may be advantageous to disperse the vanadium compound. This is because when the solvent is added after the vanadium compound is added, the vanadium compound is easily isolated between the bottom of the reactor and the vanadium compound-solvent interface. because there is room for it.
- the most undesirable mixing method is a method of directly mixing the vanadium compound and the hydrazine compound.
- an electrolyte is prepared by mixing a vanadium compound and a hydrazine compound, adding a solvent, and then administering an acid in step 2, some of the raw materials are not dissolved in the acid and precipitation occurs.
- smoke and heat are generated under vigorous reaction, and the vanadium compound turns black. Judging from such a phenomenon, it is estimated that a part of the hydrazine compound is decomposed by the instantaneous heat of reaction, and thus the vanadium compound does not perform a reducing function after the acid is added, resulting in precipitation of the vanadium compound.
- the hydrazine compound may be a hydrate or a salt.
- the hydrazine compound may be hydrazine monohydrate
- the hydrazine salt may be a hydrazine sulfate.
- the hydrazine compound may be preferably added in the form of a hydrate or aqueous solution, for example, it may be preferable when the hydrazine compound is at least 95 weight ratio of water compared to 100 weight ratio of the hydrazine compound, preferably diluted with 200 to 500 parts by weight of water, etc., The total amount of water required to manufacture the electrolyte should be the same.
- the process can be performed more stably by gently controlling the rapid reaction rate, so that it is possible to prepare a high-purity, high-quality vanadium electrolyte solution with excellent reaction efficiency.
- the input flow rate of acid should be determined in consideration of the exotherm of the combined reaction solution, which is determined from the reactor size and reactant content.
- the acid input flow rate is, for example, 200 to 300 ml/h, preferably 220 to 260 ml/h, more preferably 230 to 250 ml/h, when preparing 1 L electrolyte having a composition of 1.6 mol vanadium and 4.0 mol sulfuric acid in a 2L flask. can be h.
- the rapid increase in exotherm due to the input of acid is until the point when the same amount of acid as the number of moles of vanadium is added, and if a gradual temperature rise or temperature decrease occurs thereafter, the input flow rate of acid is further increased or a reaction is performed using a heating device. It is desirable to be able to maintain the vicinity of the target temperature.
- the acid may be appropriately adjusted according to the type of the vanadium compound and the purpose of the electrolyte solution within the range of dissolving the vanadium compound.
- the acid may be at least one selected from sulfuric acid, hydrochloric acid, nitric acid and acetic acid.
- the vanadium compound for example, 1000 parts by weight or less of sulfuric acid, and specifically, 100 to 400 parts by weight of sulfuric acid may be included.
- the above-described input sequence (solvent ⁇ vanadium compound ⁇ hydrazine compound ⁇ sulfuric acid) has two advantages over the input sequence (solvent ⁇ vanadium compound ⁇ sulfuric acid ⁇ hydrazine compound) shown in the following comparative example.
- the hydrazine compound When the hydrazine compound is added later, if there is no separate cooling process, the hydrazine compound is added at a high temperature raised by the addition of sulfuric acid. Conditions can cause a rather abrupt reaction, so the flow rate must be controlled.
- the component requiring flow rate control is one type of sulfuric acid, whereas if the order of introduction is changed, the component requiring flow rate control becomes two types of sulfuric acid and hydrazine compound, so processing time and processing difficulties follow.
- the hydrazine compound is decomposed into NH 3 + NH when the temperature is 180 ° C or higher, and N 2 + 2H 2 when the temperature is 350 ° C or higher.
- the possibility of decomposition of hydrazine without reducing it by heat increases. Due to this side reaction, a part of hydrazine is consumed without participating in the reduction reaction, so contrary to the actual theory, experimentally, an excess of about 4-7% of stoichiometric ratio can be added to achieve 3.5 value.
- the hydrazine compound is added in advance and sulfuric acid is added later, the possibility of the side reaction described above is low, and it is economical because a small amount of about 3% or less can be added experimentally to achieve 3.5 value.
- the reaction may be accelerated.
- the usable catalyst may include Pt, Ru, Pd, and the like
- the additive may include Mo, MoO 3 , (MoO 2 )SO 4 and the like. The catalyst can be recovered and reused.
- the gas by-product (N 2 ) from the reduction process of pentavalent vanadium ions is discharged out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature, the reaction While maximizing efficiency, there is an advantage in that a change in composition in the reactor can be prevented.
- reaction of the first step may be performed under reflux within the reaction temperature range to improve the reaction participation of the reactants, thereby further improving productivity.
- reflux is not particularly limited if it corresponds to a reflux process commonly recognized in the art to which the present invention pertains, and as a specific example, the solvent evaporated in the reaction process by connecting a cooler or condenser to the upper inlet of the reactor It means that the reaction is continuously performed by condensing and circulating the condensed solvent back to the reactor.
- the reaction of the first step may be carried out, for example, at 70 to 120 ° C., preferably 80 to 120 ° C., more preferably 90 to 120 ° C., even more preferably, unless there is a special pressure device in the reactor. It can be carried out at 100 to 110 ° C. In this case, the reaction participation rate of the reactants can be further increased, and there is an advantage of improving productivity by manufacturing in a relatively short time.
- the reaction of the first step may be carried out, for example, for 13 hours or less, preferably 1 hour to 13 hours, more preferably 2 hours to 8 hours, and the amount of exclusive solvent is greater than 6 times the number of moles of vanadium. However, if it is closer to 6 times, the reaction time is shortened and the effect of removing impurities is excellent. However, 6 times is a theoretical value. In practice, when the amount of exclusive solvent is near 6 times, it may not be easy to prepare an electrolyte due to slushing and solidification of the reactants, which varies depending on the characteristics of the vanadium raw material.
- the exclusive solvent by at least 8.0 times the number of moles based on the number of moles of vanadium.
- the reaction may preferably be carried out under a non-reactive atmosphere such as nitrogen.
- the reaction may also proceed under atmospheric pressure, but may be pressurized or reduced pressure as necessary within the range satisfying the above-described reaction conditions.
- the weight of the solvent included in the total of 100% by weight of the vanadium compound, reducing agent, sulfuric acid and solvent may be, for example, 20 to 80% by weight, preferably 30 to 70% by weight, in which case the concentration of the reactor is There is an advantage in that it is high, and the reaction efficiency is excellent, and the purity is further improved.
- the reduced vanadium compound formed in the first step is cooled.
- the reaction of the second step may, for example, be performed under conditions of natural cooling, and preferably may be rapidly cooled compared to natural cooling using a temperature control device.
- the change in the cooling temperature and the time required for cooling may vary depending on the reaction scale, the temperature at the end of the reaction, the ambient temperature and the scale of the temperature control device, but it is preferable to proceed under stirring.
- the reaction of the 1L target electrolyte solution having the composition of 1.6 mol vanadium, 4.0 mol sulfuric acid, and 20M exclusive solvent using a 2L flask at room temperature in the first step described above is terminated at 110° C.
- the natural cooling of the second step The reaction can be carried out for 4 to 7 hours.
- the cooling time can be shortened according to the cooling scale, so that when a cooling device of an appropriate size is used, there is an advantage of further improving the production yield.
- a post solvent is added to the electrolyte obtained in the second step and filtered.
- the filtration may be a gravity filtration method using only gravity, or a pressure filtration method in which a pressure is applied to an upstream layer of the filtering means or a reduced pressure filtration method in which a pressure is applied to a downstream layer of the filtering means.
- the filtration can use a filtration means that is a hydrophilic material while having acid resistance having a pore size of 0.2 to 10 ⁇ m.
- the process time or pressure load increases, resulting in competitiveness versus quality. may fall, and if it exceeds 10um, the filtration effect may be insufficient.
- the vanadium electrolyte may have a residual impurity content of 30 ppm or less.
- the component included in the residual impurities may mean Si or Al.
- Residual impurity content may preferably be 20 ppm or less, thereby preventing deterioration of battery performance due to residual impurities in the vanadium electrolyte.
- the present invention provides a vanadium electrolyte prepared by the above method for preparing a vanadium electrolyte.
- the vanadium electrolyte may include a 2.0 to 5.0 vanadium compound, and at least a portion of the electrolyte may include a 3.3 to 3.7 vanadium compound.
- the vanadium electrolyte prepared by the method of the present invention was evaluated within the initial 30 cycles at a current density of 100 mA/cm 2 , a discharge cut-off voltage of 0.8 V, a charge cut-off voltage of 1.6 V, and a flow rate of 160 ml/min.
- the charge capacity means a state in which charges are accumulated up to the charge cut-off voltage
- the discharge capacity means a state in which the charge is emptied up to the discharge cut-off voltage
- energy efficiency means the product of the voltage efficiency to the charge capacity compared to the discharge capacity.
- the vanadium electrolyte can be used without any particular limitation as long as it is a compound capable of providing vanadium ions used in a vanadium redox flow battery, and it can be used in an aqueous vanadium redox flow electrolyte and an electrolyte for a non-aqueous vanadium redox flow such as vanadium acetylacetone. all apply
- the method for producing the above-described vanadium electrolyte is, for example, cooling the generated vanadium electrolyte solution prior to filtration. characterized in that
- the reaction rate in the reduction reaction can be reduced by circulating filtration of the reaction solution under -25 to 40 °C.
- water was used in an amount of 5 to 15 moles per 1 mole of the vanadium compound, reacted at 100 ° C. or higher to form a vanadium compound, and then the reduced vanadium compound was cooled to -25 to 20 ° C., and water was added previously. It is possible to reduce the reaction rate in the reduction reaction by introducing an excess of the content and circulating the reaction solution at -25 to 40 °C.
- the weight of the solvent included in the total of 100% by weight of the vanadium compound, reducing agent, sulfuric acid and solvent may be, for example, 20 to 80% by weight, preferably 30 to 70% by weight, in which case the concentration of the reactor is There is an advantage in that it is high, and the reaction efficiency is excellent, and the purity is further improved.
- the reaction of the first step may be carried out at, for example, 70 to 120° C. or less, corresponding to the first temperature, unless there is a special pressure device in the reactor, preferably 80 to 120° C., more preferably can be carried out at 90 to 120 ° C., more preferably at 100 to 110 ° C.
- the reaction participation rate of the reactants can be further increased, and there is an advantage of improving productivity by manufacturing in a relatively short time.
- the reaction may be carried out, for example, for up to 13 hours, preferably from 1 hour to 13 hours, and more preferably from 2 hours to 8 hours, and the amount of the exclusive solvent is 6 times the number of moles greater than 6 times the number of moles of vanadium. The closer it is, the shorter the reaction time and the better the effect of removing impurities. However, 6 times is a theoretical value. In practice, when the amount of exclusive solvent is near 6 times, it may not be easy to prepare an electrolyte due to slushing and solidification of the reactants, which varies depending on the characteristics of the vanadium raw material. Therefore, it is preferable to input the exclusive solvent by at least 8.0 times the number of moles based on the number of moles of vanadium.
- the reaction may preferably be carried out under a non-reactive atmosphere such as nitrogen.
- the reaction may also proceed under atmospheric pressure, but may be pressurized or reduced pressure as necessary within the range satisfying the above-described reaction conditions.
- the weight of the solvent included in the total of 100% by weight of the vanadium compound, reducing agent, sulfuric acid and solvent may be, for example, 20 to 80% by weight, preferably 30 to 70% by weight, in which case the concentration of the reactor is There is an advantage in that it is high, and the reaction efficiency is excellent, and the purity is further improved.
- the reduced vanadium compound formed in the first step is cooled to a temperature at least 80° C. lower than the first temperature.
- the cooling reaction may, for example, be performed under conditions of natural cooling, and preferably may be rapidly cooled compared to natural cooling using a temperature control device.
- the change in the cooling temperature and the time required for cooling may vary depending on the reaction scale, the temperature at the end of the reaction, the ambient temperature and the scale of the temperature control device, but it is preferable to proceed under stirring.
- the cooling reaction (second temperature corresponding to) may be carried out at -25 to 20 °C for 4 to 7 hours.
- the cooling time can be shortened according to the cooling scale, so that when a cooling device of an appropriate size is used, there is an advantage of further improving the production yield.
- the second temperature corresponds to a low temperature point (precipitation temperature) at which the vanadium electrolyte does not precipitate within 48 hours, and the vanadium electrolyte does not precipitate, but the present invention has been completed by confirming that impurities are precipitated as the temperature decreases.
- the temperature is preferably -25°C or higher and 20°C or lower, more preferably -10°C or higher and 10°C or lower, even more preferably -5°C or higher and 5°C or lower, and around 0°C is an impurity relative to the cooling temperature It is most preferable to realize the reduction effect.
- the obtained cooled electrolyte solution is filtered at a third temperature condition at least 40° C. lower than the first temperature.
- the filtration may be a gravity filtration method using only gravity, or a pressure filtration method in which a pressure is applied to an upstream layer of the filtering means or a reduced pressure filtration method in which a pressure is applied to a downstream layer of the filtering means.
- the filtration can use a filtration means that is a hydrophilic material while having acid resistance having a pore size of 0.2 to 10 ⁇ m.
- the process time or pressure load increases, resulting in competitiveness versus quality. may fall, and if it exceeds 10um, the filtration effect may be insufficient.
- the third temperature is preferably -25°C or more and 40°C or less, more preferably -10°C or more and 30°C or less, still more preferably -5°C or more and 30°C or less, and a cooling temperature near 0°C It is most preferable to realize the effect of reducing the impurity in contrast.
- filtration is applicable to both circulation and non-circulation.
- the third temperature is preferably -25 ° C or more and 20 ° C or less, more preferably -10 ° C or more, 10 ° C or less, -5 ° C or more, It is more preferable that it is 5° C. or less, and it is most preferable that it is around 0° C. to realize the effect of reducing impurities.
- the third temperature is higher than that in the case of not circulating in consideration of reaction efficiency, for example, it is preferable that the third temperature is 20°C or more and 40°C or less, like the second temperature described above, 25 °C or more and 35 °C or less are more preferable, and 25 °C or more and 30 °C or less are most preferable to realize the effect of reducing impurities.
- a post-solvent may be added between the first and second steps described above, or between the second and third steps. There may be some heat generation in the process of adding the after-solvent, but if the after-solvent is mixed while maintaining the third temperature by suppressing the heat generated when the after-solvent is added by using a temperature control device such as natural cooling or a cooler, filtration Using the device, it is possible to provide an effect of more suppressing the dissolution of some of the filterable impurities in the electrolyte.
- the vanadium electrolyte may have a residual impurity content of 30 ppm or less.
- the components included in the residual impurities may mean Si, Al, Ca, and Fe.
- Residual impurity content may preferably be 20 ppm or less, thereby preventing deterioration of battery performance due to residual impurities in the vanadium electrolyte.
- the circulation filtration includes, for example, an electrolyte discharge pipe connected to an electrolyte outlet of a vanadium electrolyte manufacturing apparatus, and a circulation pipe that is optionally extended from one side of the discharge pipe and connected to the upper part of the reaction tank, and the electrolyte solution
- a filtration device may be installed in the discharge pipe or the circulation pipe.
- the filtration step is naturally inserted in a single process, and thus, there is an advantage in that a high-purity, high-quality electrolyte is manufactured without significantly extending the process time.
- the vanadium electrolyte production apparatus includes, for example, a single reaction tank, a raw material input port for introducing a reaction raw material into the single reaction tank, an electrolyte solution outlet port for discharging the prepared vanadium electrolyte solution, a stirrer for stirring the input reaction raw material, and the single reaction tank.
- the manufacturing cost is low and the process is easy Simple, low facility investment cost, easy maintenance and management, mass production is possible with a non-catalytic chemical reaction process, and by applying predetermined reaction conditions, it is possible to shorten reaction time, maximize reaction efficiency, and achieve high-quality electrolyte production. can have an effect.
- the inside of the reaction tank is preferably coated with one or more selected from the group consisting of glass, PE and Teflon resin, and more preferably coated with one or more selected from the group consisting of PE and Teflon resin, most It is preferably coated with a Teflon resin, and in this case, maintenance and management of the reactor are easy, and the reaction efficiency is excellent.
- a filtering device may be more preferably installed in the electrolyte discharge pipe, and more preferably, a filtering device may be installed in both the electrolyte discharge pipe and a circulation pipe provided as necessary.
- a filtering device may be installed in both the electrolyte discharge pipe and a circulation pipe provided as necessary.
- the filtration device installed in the circulation pipe may be preferably one or more, more preferably one or two, and still more preferably one, and within this range, the filtration step is naturally inserted in a single process and the process There is an advantage in that a high-purity, high-quality electrolyte can be prepared without significantly extending time.
- the number of filtering devices installed in the discharge pipe may be preferably one or more, more preferably one to three, and still more preferably one or two, and within this range, the filtration step naturally occurs in a single process.
- the total number of filtering devices installed in the vanadium electrolyte production device may be preferably two or more, more preferably two or three, and still more preferably two, and within this range, a filtration step in a single process
- the temperature control device is preferably a heat exchanger, and more preferably a jacket-type heat exchanger, in which case it is easy to control the reaction temperature, so that the reaction efficiency is excellent and a high-purity, high-quality vanadium electrolyte is prepared. .
- the jacket-type heat exchanger in the present invention is not particularly limited in the case of a jacket-type heat exchanger commonly used in the technical field to which the present invention belongs, and may be, for example, a jacket surrounding the reaction tank and including a heat transfer medium.
- FIG. 16 the apparatus configuration and process flow diagram for the production of an electrolyte solution through circulation filtration is shown in FIG. 16 below.
- hydrazine monohydrate N 2 H 4 ⁇ H 2 O
- vanadium compound V 2 O 5
- sulfuric acid H 2 SO 4
- DIW deionized water
- the reactant is passed through a circulation pipe equipped with a filtration means (Filtration) to remove impurities, and then the reactant is heated with a jacket-type heat exchanger (heater) surrounding the reaction tank to proceed with the second-stage reduction reaction.
- a circulation pipe equipped with a filtration means Frtration
- a jacket-type heat exchanger Heater
- Water vapor generated during the reduction reaction water vapor in the nitrogen gas (N 2 ) is cooled by an open reflux condenser and recovered to the reactor, and the nitrogen gas (N 2 ) may be discharged to the outside through the open reflux condenser.
- impurities are removed once more through the discharge pipe equipped with filtration, and the final electrolyte product (V 3.5+ electrolyte product) is obtained.
- the vanadium electrolyte manufacturing apparatus and process according to the present invention has the advantage that, unlike the existing known vanadium electrolyte manufacturing apparatus and process, 3.5 valence electrolyte can be manufactured with one reactor, and the process equipment and maintenance are significantly advantageous compared to the existing ones. .
- the composition of the vanadium electrolyte to be described as the first embodiment is 1.6 moles of a vanadium compound and 4.0 moles of sulfuric acid, and the ionic value of the vanadium electrolyte is 3.5, and a vanadium electrolyte in which vanadium tetravalent ions and vanadium trivalent ions are mixed in a molar ratio of 1:1. to be.
- Low grade vanadium compound 146 g (99% low grade), 98% sulfuric acid solution 400 g, water 775 g, nitrogen-based reducing agent (hydrazine monohydrate) 80% by weight aqueous solution 38.0 g, redox additive (molybdenum trioxide) 0.15 g.
- hydrazine monohydrate is required as much as the number of moles corresponding to the value obtained by multiplying the number of moles of vanadium by 0.375, and about 0.6 M is required with respect to 1.6 moles of the vanadium compound.
- hydrazine an 80 wt% aqueous solution of hydrazine monohydrate was used, and molybdenum trioxide was used as a redox additive.
- M means the number of moles (mol/L) of the solute dissolved in 1 L of the solution.
- % means % by weight unless otherwise defined.
- An apparatus necessary for preparing the electrolyte of the first embodiment is as follows with reference to FIG. 12 .
- reaction tank (hereinafter referred to as 'reactor') that can react 1 L or more, a stirrer, a heater and thermometer capable of temperature control, and a filtration system (pump, tube, filter, etc.)
- 'reactor' a reaction tank
- stirrer a stirrer
- heater and thermometer capable of temperature control
- filtration system pump, tube, filter, etc.
- the facing surface should be made of a material with acid resistance and chemical resistance such as glass, PTFE, PE, Teflon, etc.
- Vanadium compound (V 2 O 5 ), sulfuric acid (H 2 SO 4 ), deionized water (DIW), and hydrazine monohydrate (N 2 H 4 ⁇ H 2 O) were added to the reaction tank through the raw material input port, and the reaction was introduced The raw material was stirred with a stirrer to start the first-step reduction reaction.
- the reactant is passed through a circulation pipe equipped with a filtration means (Filtration) to remove impurities, and then molybdenum trioxide (MoO 3 ) is put into the reactor, and then jacketed heat exchange surrounding the reaction tank
- a circulation pipe equipped with a filtration means (Filtration) to remove impurities, and then molybdenum trioxide (MoO 3 ) is put into the reactor, and then jacketed heat exchange surrounding the reaction tank
- a heater heat exchange surrounding the reaction tank
- Example 1 the electrolyte preparation step of Example 1 will be described in detail by dividing the steps.
- Step 1 Input step of vanadium raw material and nitrogen-based reducing agent
- step 1 the input flow rate of raw materials is not considered much, but the order of raw material input needs to be considered.
- the reaction tank As for the order of raw material input, it is most preferable to administer to the reaction tank (reactor) in the order of water ⁇ vanadium ⁇ hydrazine monohydrate under the operation of the stirrer.
- a certain amount of water may be added in this process. For example, it is possible to dilute a portion of water with hydrazine monohydrate and administer it.
- a method of flushing it into the reactor by flowing water is also possible.
- water in the reactor before adding the vanadium compound it may be more advantageous in dispersing the vanadium compound in the reactor.
- water is added after adding the vanadium compound, the vanadium compound is more easily isolated between the reactor bottom and the vanadium compound-water interface, and the isolated and aggregated vanadium compound may generate unnecessary load.
- the most undesirable mixing method in step 1 is a method of directly mixing the vanadium compound and hydrazine monohydrate.
- a vanadium compound and hydrazine monohydrate are mixed and water is added, and sulfuric acid is administered in step 2 to be described later to make an electrolyte, a part of the vanadium compound, a raw material, is not dissolved in the sulfuric acid, and precipitation occurs.
- the two raw materials are mixed without water, smoke and heat are generated under a vigorous reaction, and the vanadium compound turns black.
- the sulfuric acid input flow rate may be determined in consideration of exotherm in the reaction solution formulated in step 1. Sulfuric acid is introduced slowly to prevent the reaction solution from splashing on the wall of the container as much as possible, and it is preferable that the exothermic temperature does not exceed 110 °C. In this process, gas evacuation and collection devices such as open reflux condensers are required, and additional heating devices such as cooling devices or heaters (heat exchangers) may be required.
- 1 is a graph showing the change in temperature according to time during which a reduction reaction using a reducing agent is performed under a sulfuric acid flow rate of 240 ml/hr or 480 ml/hr.
- the temperature rise shows a steep slope, at a time point of about 25 minutes in the case of a flow rate of 240 ml/hr, and at a time point of about 13 minutes in the case of a flow rate of 480 ml/hr Each temperature drop was observed.
- the temperature rise in the first half occurs when 1.6M of vanadium is dissolved in 1.6M of sulfuric acid (about 100ml) and reduced to vanadium pentavalent ions, while the reduced vanadium pentavalent ions are converted to tetravalent ions by hydrazine monohydrate. Fever is the biggest factor.
- the temperature after a specific time point was observed to decrease slightly in the case of 240ml/hr and to be maintained in the case of 480ml/hr. Therefore, it is desirable to design the flow rate control of sulfuric acid in consideration of the reactor size, reactant amount and composition as well as the reaction point.
- the first half is 200 to 300 ml/h, preferably 220 to 260 ml/h, more preferably 235 to 245 ml/h, and the second half is 430 to 530 ml/h, preferably 460 to 500 ml/h, more preferably 475 to 485 ml/h, and the redox reaction was performed.
- the flow rate in this embodiment is a range value in experimental conditions such as equipment for implementing this embodiment, and it will be most preferable when the flow rate control in the two sections is performed under the target temperature.
- step 1 and 2 tested in this example water ⁇ vanadium compound ⁇ hydrazine monohydrate ⁇ sulfuric acid, hereinafter referred to as the 'flow example'
- 'flow example' water ⁇ vanadium compound ⁇ sulfuric acid ⁇ hydrazine monohydrate. It has two advantages over the method (hereinafter referred to as 'flow rate comparative example').
- the reaction time is short, and secondly, the reduction efficiency of the reducing agent is high.
- hydrazine monohydrate is preferably used by diluting 20 to 30 parts by weight of 100 parts by weight of water.
- Hydrazine has a reducing power capable of instantaneously reducing pentavalent ions to tetravalent ions even at room temperature, and considering that hydrazine has a boiling point of 114°C, hydrazine input at high temperature is never used in process control even if diluted with water. Inappropriate. In addition, it is difficult to have a positive effect on quality influence by increasing the possibility of hydrazine disappearance.
- a method of compounding a diluted hydrazine raw material through flow control as in the flow rate comparative example may be used.
- hydrazine decomposes into NH 3 + NH when the temperature is 180 °C or higher, and N 2 + 2H 2 when the temperature is 350 °C or more.
- the possibility of decomposition of hydrazine without acting as a reducing agent increases due to the heat generated in Theoretically, even gaseous hydrazine above 114° C. may have a normal reaction if there is no loss, but there is a lot of room for loss in the actual process. Due to these side reactions and disappearance, experimentally, an amount of about 4 to 7% of the stoichiometric ratio must be added to achieve 3.5 value in the flow rate comparative example. On the other hand, since it is sufficient to consume a content of about 0 to 3% in the flow rate example, it is extremely superior from the problems of loss and side reactions compared to the flow rate comparative example.
- the end time of step 2 may be the time when sulfuric acid input is completed, or additional stirring may be performed at 110° C. or less within 2 hours.
- step 2 the gas by-product (N 2 ) from the reduction process of pentavalent vanadium ions is discharged out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature (around 110 °C).
- This has the advantage of maximizing the reaction efficiency and preventing a change in the composition in the reactor.
- Step 3 Preparation of the 3.5-valent electrolyte solution
- molybdenum trioxide 0.1 parts by weight relative to 100 parts by weight of V 2 O 5
- the reactor temperature was adjusted to 110° C. using a heater or a heat exchanger.
- hydrazine monohydrate can be added even if the reactor temperature does not reach 110 °C, when hydrazine monohydrate is added to the tetravalent electrolyte solution at 80 °C or less, particularly 60 °C or less, sulfuric acid-hydrazine salt is formed and the reducing function of hydrazine is reduced. may be lowered.
- step 3 the gas by-product (N 2 ) from the reduction process of tetravalent vanadium ions is discharged out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature (around 110 °C).
- This has the advantage of maximizing the reaction efficiency and preventing a change in the composition in the reactor.
- the time required for the three-step process is less than 12 hours.
- Example 1 The division of Example 1 into three steps is for illustrative purposes only, and as a whole is a single process carried out in the same reactor.
- the redox additive is added in step 3, it may be added together when the vanadium is added in step 1 before adding hydrazine or sulfuric acid.
- the input time of the redox additive may be added to the above-described 3 step, but is not limited thereto, and may be added in the 1st or 2nd step.
- Example 2 0.15 g of molybdenum trioxide (0.1 parts by weight relative to 100 parts by weight of V 2 O 5 ) used in Example 1 was added to 0.30 g (0.2 parts by weight: Example 2), 0.60 g (0.4 parts by weight: Example 3), The same experiment as in Example 1 was repeated except that 1.2 g (0.8 parts by weight: Example 4) and 2.4 g (1.6 parts by weight: Example 5) were respectively changed.
- Example 4 The same experiment as in Example 4 was repeated except that the low-grade vanadium compound (purity 99%) used in step 1 of Example 4 was replaced with a high-grade vanadium compound (purity 99.9%).
- vanadium compound 400 g of 98% sulfuric acid, 775 g of water, 72.0 g of oxalic anhydride (organic reducing agent replacing nitrogen-based reducing agent)
- a vanadium compound, oxalic anhydride, and water were added to the reactor, and sulfuric acid was added in consideration of exotherm as described in Example 1.
- each of the obtained vanadium tetravalent compound was placed in a positive electrode tank and a negative electrode tank, and electrolysis was performed while leaving 330 ml of the obtained vanadium tetravalent compound. Electrolysis was carried out in a constant current mode to reach a voltage of 1.8V under 150 mA/cm 2 conditions to obtain 300 ml or more of a pentavalent vanadium compound from the anode tank.
- 300 ml of the pentavalent vanadium compound obtained by electrolysis and 300 ml of 330 ml of the 330 ml of the vanadium tetravalent compound remaining without electrolysis are combined to obtain 600 ml of a vanadium 3.5-valent electrolyte solution, and impurities are removed again using filtration means did. In this process, if some oxidized water deviate, it can be adjusted with the remaining excess amount.
- Example 2 The same experiment as in Example 1 was repeated except that 0.29 g of molybdenum trioxide (0.2 parts by weight relative to 100 parts by weight of V 2 O 5 ) used in Example 1 was changed to 15 g (10 parts by weight). .
- the redox additive content represents 3 parts by weight of MoO relative to 100 parts by weight of V 2 O 5
- the reaction time is the time taken from the time when sulfuric acid input is completed to the time it is determined that the reaction is complete because the oxidation number hardly does not occur.
- charge capacity, discharge capacity, and energy efficiency are the values of the 30th cycle, respectively
- the content (ppm) represents the content of Mo, the main component of the redox additive MoO 3 in the electrolyte.
- Example 5 As shown in Example 5 and Comparative Example 2 in Table 1, when the redox additive is added in excess of an appropriate amount, the reaction rate may be slightly improved, but it can be seen that the electrolyte performance is reduced. According to the present examples, it can be confirmed that the redox additive has excellent performance degradation at the level of 10 parts by weight, which was confirmed in FIGS. 4 to 6 .
- Equation 1 can be embodied as Equation 1-1 below by substituting the values of Examples 1 to 6.
- Equation 1-1 the relationship between the redox additive and the reaction rate in Example 1 is a proportional negative correlation, and it follows the Arrhenius equation, and is confirmed in FIG. 2 . That is, the process time can be controlled by determining the amount of the redox additive from the variables of the raw material, composition, and process condition using Equation 1-1.
- Test Example 3 H 3 PO 4 known to be added for electrolyte temperature stability was added, and the mutual influence with the redox additive was confirmed.
- electrolyte samples using redox additives were prepared in the same manner as in Example 3, and then electrolyzed to prepare pentavalent electrolytes of Reference Examples 1a to 4a.
- the composition of the vanadium electrolyte solution which will be described as a second embodiment below, is 1.7 moles of a vanadium compound, 4.3 moles of sulfuric acid, an electrolyte density of 1.35 g/cm 3 , an ionic value of the vanadium electrolyte of 3.5, and a vanadium tetravalent ion and a vanadium trivalent ion equal to 1 It is an electrolyte mixed in a ratio of 1:1.
- the equipment required for preparing the electrolyte of the second embodiment is as follows.
- reaction tank capable of reacting 1L or more (hereinafter also referred to as 'reactor'), agitator, temperature-controllable heater and thermometer, reflux, filtration system (pump, tube, filter, etc.), and
- the contact surface should be made of acid- and chemical-resistant materials such as glass, PTFE, PE, Teflon, etc.
- Vanadium compound (V 2 O 5 ), exclusive solvent, and hydrazine monohydrate (N 2 H 4 ⁇ H 2 O) were added to the reaction tank through the raw material inlet, and then sulfuric acid (H 2 O) was added.
- the reaction product was heated with a jacketed heat exchanger (heater) surrounding the reaction tank to maintain the reaction temperature at 110° C., and the first-stage reaction was carried out.
- Example 7 as an experiment in which the exclusive solvent A is about 75% of the total solvent, which is 540 g, the amount of the after-solvent is 180 g, and when converted to the number of moles, the exclusive solvent is 30 M and the after-solvent is 10 M, where the exclusive solvent is vanadium 1.7M compared to 1.7M It is about 3.2 times more than the minimum required water 9.35M, and it is an amount corresponding to 17.6 times more moles than 1.7M of vanadium.
- Example 7 the electrolyte preparation step of Example 7 will be described in detail by dividing the steps.
- deionized water (DIW) and a vanadium compound (V 2 O 5 ) were introduced into the reactor under the operation of the stirrer. At this time, 440 g of 540 g of exclusive solvent was added.
- the sulfuric acid was slowly introduced and the flow rate was adjusted so that the reaction solution did not splash on the wall of the vessel as much as possible, and the exothermic temperature in the reactor did not exceed 110°C.
- the reflux discharges the gas by-product (N 2 ) from the reduction process of pentavalent vanadium ions out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature of around 110 ° C. Changes in composition in the reactor were prevented.
- Reduction was carried out while maintaining the reactor temperature at 110°C using a heater or a heat exchanger. The progress of the reduction was confirmed through UV measurement after diluting a part of a sample (0.5 ml or less) of the reactant.
- the reflux discharges the gas by-product (N 2 ) from the reduction process of pentavalent vanadium ions out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature around 110°C. and to prevent composition change in the reactor.
- the heater or heat exchanger was stopped and cooled to room temperature using a cooler.
- Example 8 the same process as in Example 7 was repeated except that the input amount of the exclusive solvent/after solvent was changed in Example 7.
- 360 g as the exclusive solvent A of Example 7 and 360 g as the after-solvent, that is, an amount corresponding to about 50% of the total solvent was used. This corresponds to about 2.1 times the water content compared to the minimum content of exclusive solvent, and 11.8 times the amount of vanadium compared to 1.7 moles.
- Example 9 the same process as in Example 7 was repeated except that the input amount of the exclusive solvent/after solvent was changed in Example 7.
- Example 7 180 g as the exclusive solvent A of Example 7 and 540 g as the after-solvent, that is, an amount corresponding to about 25% of the total solvent was used as the exclusive solvent and an amount corresponding to 75% as the after-solvent. This corresponds to about 1.1 times the water content compared to the minimum content of exclusive solvent, and 5.9 times the amount of vanadium to 1.7 moles.
- Comparative Example 3 is the same as in Example 7, except that 720 g of the total amount of the exclusive solvent + the after solvent was all added in the exclusive solvent input step of Example 7 and not added in the post solvent input step to contrast with the above examples. The process was repeated. Table 2 below specifically shows the amount of the exclusive solvent/post solvent used in Examples 7 to 9 and Comparative Example 3.
- Comparative Example 4 the same process as in Example 7 was repeated except that the input amount of the exclusive solvent/after solvent was changed in Example 7. Specifically, Comparative Example 4 is an experiment using 95 g (3.1 times mol of vanadium compared to 1.7 mol) of the exclusive solvent described in the present invention.
- the oxidation number of vanadium was measured using a UV spectrometer for each reaction step in the electrolyte preparation process, and the reaction time is shown in Table 3 below.
- the impurity Si content and Al content in the electrolyte were measured using an ICP-OES apparatus, respectively, and the results are shown in Table 2 below.
- the secondary battery was charged with a constant current at room temperature with a current of 100mA/cm 2 until the voltage reached 1.60V, and then discharged with a reverse constant current of 100mA/cm 2 until the voltage reached 0.8V during discharging.
- the cycle as described above was repeated 30 times to calculate the average value thereof, and the results are shown in Table 3 below.
- Example 7 25:75 2 3.5 8.5 2.53 2.43 83.84
- Example 8 50:50 5 5.6 10.6 2.53 2.45 85.15
- Example 9 75:25 8 7.1 11.5 2.51 2.44 85.04 Comparative Example 3 100:0 14 20.4 15.5 2.42 2.33 83.10
- the impurity content in the electrolyte was reduced by up to 82.8% for Si and by up to 45.2% for Al compared to Comparative Example, respectively, and the reaction time was shortened by up to 85.7%.
- the charging capacity was at least 2.51 Ah, whereas in the case of the comparative example, it was 2.42 Ah, which was at least 0.09 Ah lower, and the electrolyte solution to which the process of the present invention was applied In this case, the discharge capacity was at least 2.43 Ah, whereas in Comparative Example 3, it was 2.33 Ah, which was at least 0.10 Ah lower.
- the energy efficiency is at least 83.84%, which is at least 0.74% lower than that of the comparative example 83.10%. This can be interpreted as meaning that the quality and battery performance of the electrolyte solution to which the process proposed in the present invention is applied has an effect of improving.
- Example 8 is the most excellent in terms of battery performance such as charge capacity, discharge capacity and energy efficiency. This may be an example showing that even the theoretical minimum amount of the above-described exclusive solvent is not necessarily the best in battery performance.
- the composition of the vanadium electrolyte which will be described as a third embodiment below, is 1.7 moles of a vanadium compound, 4.3 moles of sulfuric acid, an electrolyte density of 1.35 g/cm 3 , an ionic value of 3.5, and a vanadium tetravalent ion and a vanadium trivalent ion equal to 1 It is an electrolyte mixed in a ratio of 1:1.
- the equipment required for preparing the electrolyte of the third embodiment is as follows.
- reaction tank capable of reacting 1L or more (hereinafter also referred to as 'reactor'), agitator, temperature-controllable heater and thermometer, reflux, filtration system (pump, tube, filter, etc.), and
- the contact surface should be made of acid- and chemical-resistant materials such as glass, PTFE, PE, Teflon, etc.
- Vanadium compound (V 2 O 5 ), exclusive solvent, and hydrazine monohydrate (N 2 H 4 ⁇ H 2 O) were added to the reaction tank through the raw material inlet, and then sulfuric acid (H 2 O) was added.
- the reaction product was heated with a jacketed heat exchanger (heater) surrounding the reaction tank, and the reaction temperature was maintained at 110° C. (first temperature) to proceed with the first stage reaction.
- the filtration removes impurities through a discharge pipe equipped with a filtration means to obtain a final electrolyte product (V 3.5+ electrolyte product).
- the exclusive solvent A used in Examples 10, 11, Comparative Example 5, and Comparative Example 6 was 540 g, which is about 75% of the total solvent, the amount of the after-solvent is 180 g, and when converted to the number of moles, the exclusive solvent is 30M and the after-solvent become 10M, where the exclusive solvent is in excess of 3.2 times of the minimum required water 9.35M compared to 1.7M of vanadium, and an amount corresponding to 17.6 times more moles compared to 1.7M of vanadium.
- deionized water (DIW) and a vanadium compound (V 2 O 5 ) were introduced into the reactor under the operation of the stirrer. At this time, 440 g of 540 g of exclusive solvent was added.
- the sulfuric acid was slowly introduced and the flow rate was adjusted so that the reaction solution did not splash on the wall of the vessel as much as possible, and the exothermic temperature in the reactor did not exceed 110°C.
- the reflux discharges the gas by-product (N 2 ) from the reduction process of pentavalent vanadium ions out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature of around 110 ° C. Changes in composition in the reactor were prevented.
- Reduction was performed while maintaining the reactor temperature at 110°C using a heater or a heat exchanger. The progress of the reduction was confirmed through UV measurement after diluting a part of a sample (0.5 ml or less) of the reactant.
- the reflux discharges the gas by-product (N 2 ) from the reduction process of pentavalent vanadium ions out of the vessel, and the vaporized H 2 O and H 2 SO 4 are condensed and cooled to stay in the reactor to maintain a high temperature around 110°C. and to prevent composition change in the reactor.
- the heater or heat exchanger was stopped and cooled to -25 to 20 °C using a cooler.
- Example 11 the same process as in Example 10 was repeated except that the order of the cooling step and the post-solvent input step in Example 1 was changed.
- Example 10 when the reduction step in Example 10 was completed, 180 g of the after-solvent was added to the reactor and stirred with the electrolyte. In this process, a slight exotherm occurs, and this exotherm also lowered the temperature to a level of -25 to 20 °C.
- Example 10 the temperature was reduced to -25 to 20 °C level, and then cooled to 20 to 40 °C, and then 180 g of the after-solvent was added to the reactor and stirred with the electrolyte.
- Example 6 the same process as in Example 10 was repeated, except that the filtration conditions were changed while not using the cooling step in Example 10.
- Example 10 the step of reducing the temperature to a level of -25 to 20 ° C was omitted, and 180 g of the after-solvent was added to the reactor, stirred with the electrolyte, and then cooled under the cooling conditions of 40 to 100 ° C. obtained by natural cooling. Impurities were removed through a discharge pipe equipped with a filtration means, and a final electrolyte product (V 3.5+ electrolyte product) was obtained.
- Example 12 the same process as in Example 10 was repeated except that the input amount of the exclusive solvent/after solvent was changed in Example 10.
- 360 g as the exclusive solvent A of Example 10 and 360 g as the after-solvent, that is, an amount corresponding to about 50% of the total solvent was used. This corresponds to about 2.1 times the water content compared to the minimum content of exclusive solvent, and 11.8 times the amount of vanadium compared to 1.7 moles.
- Example 13 the same process as in Example 10 was repeated except that the input amount of the exclusive solvent/after solvent was changed in Example 10.
- Example 10 180 g as the exclusive solvent A of Example 10 and 540 g as the after-solvent, that is, an amount corresponding to about 25% of the total solvent was used as the exclusive solvent and an amount corresponding to 75% was used as the after-solvent. This corresponds to about 1.1 times the water content compared to the minimum content of exclusive solvent, and 5.9 times the amount of vanadium to 1.7 moles.
- Comparative Example 7 is the same as in Example 10, except that 720 g of the total amount of the exclusive solvent + the after solvent was all added in the exclusive solvent input step of Example 10 and not added in the post solvent input step to contrast with the above examples. The process was repeated. Table 4 below specifically shows the amount of exclusive solvent/post solvent used in Examples 10 to 13 and Comparative Example 7.
- Comparative Example 8 the same process as in Example 10 was repeated except that the input amount of the exclusive solvent/after solvent was changed in Example 10. Specifically, Comparative Example 2 is an experiment using 95 g (3.1 times mol of vanadium compared to 1.7 mol) of the exclusive solvent described in the present invention.
- the circulation filtration (filtering) process is an operation in which the electrolyte in the reactor is filtered using a circulation system to filter out impurities.
- the application time of the circulation filtration process can be carried out immediately after the sulfuric acid is added in step 2, and in addition, it can be carried out between the 'time point when the amount of vanadium moles has been added' and 'the time when all the sulfuric acid has been introduced and about 2 hours have elapsed'.
- the filter used in the circulation filtration process may have hydrophilic, hydrophobic, amphiphilic or amphiphilic properties, and the material should be at least one selected from the group consisting of PTFE, PE, PET and PP with acid resistance, and the pore size The size may be between 0.2 and 5 um.
- the time required for filtration may be controlled by the size of the filter, that is, the diameter and the pore size.
- Example 14 the same process as in Example 10 was repeated except that in Example 10, the filtration was performed in a circulation filtration method in the apparatus shown in FIG. 16 equipped with a circulating filtration pipe.
- FIG. 16 Specifically, the apparatus configuration and process flow chart for preparing the electrolyte of Example 14 are shown in FIG. 16 below.
- hydrazine monohydrate N 2 H 4 ⁇ H 2 O
- vanadium compound V 2 O 5
- sulfuric acid H 2 SO 4
- DIW deionized water
- the first-step reduction reaction is started while the input reaction raw material is stirred with a stirrer.
- the reactant was cooled to -25 to 20 °C, and 180 g of the after-solvent was added to the reactor and stirred with the electrolyte. In this process, a slight exotherm occurs, and this exotherm also lowered the temperature to a level of -25 to 20 °C.
- the impurities are removed by passing through a circulation pipe equipped with a filtration means, and then the reactant is heated with a jacketed heat exchanger (heater) surrounding the reaction tank.
- a two-step reduction reaction proceeds by heating. Water vapor generated during the reduction reaction, water vapor in nitrogen gas (N 2 ) is cooled by an open reflux condenser to be recovered to the reactor, and nitrogen gas (N 2 ) may be discharged to the outside through the open reflux condenser.
- impurities are removed once more through the discharge pipe equipped with filtration, and the final electrolyte product (V 3.5+ electrolyte product) is obtained.
- the circulation filtration (filtering) process is an operation in which the electrolyte in the reactor is filtered using a circulation system to filter out impurities.
- the application time of the circulation filtration process can be carried out immediately after the sulfuric acid is added in step 2, and in addition, it can be carried out between the 'time point when the amount of vanadium moles has been added' and 'the time when all the sulfuric acid has been introduced and about 2 hours have elapsed'.
- the filter used in the circulation filtration process may have hydrophilic, hydrophobic, amphiphilic or amphiphilic properties, and the material should be at least one selected from the group consisting of PTFE, PE, PET and PP with acid resistance, and the pore size The size may be between 0.2 and 5 um.
- the time required for filtration may be controlled by the size of the filter, that is, the diameter and the pore size.
- Comparative Example 9 the same process as in Comparative Example 5 was repeated, except that the filtration in Comparative Example 5 was performed by the circulation filtration method in the apparatus shown in FIG. 5 equipped with a purifying filtration pipe.
- FIG. 16 Specifically, the apparatus configuration and process flow chart for preparing the electrolyte of Comparative Example 9 are shown in FIG. 16 below.
- hydrazine monohydrate N 2 H 4 ⁇ H 2 O
- vanadium compound V 2 O 5
- sulfuric acid H 2 SO 4
- DIW deionized water
- the first-step reduction reaction is started while the input reaction raw material is stirred with a stirrer.
- the reactant was cooled to 20 to 40 °C, and then 180 g of the after-solvent was added to the reactor and stirred with the electrolyte.
- step 2 Reduction reaction proceeds. Water vapor generated during the reduction reaction, water vapor in nitrogen gas (N 2 ) is cooled by an open reflux condenser to be recovered to the reactor, and nitrogen gas (N 2 ) may be discharged to the outside through the open reflux condenser.
- impurities are removed once more through the discharge pipe equipped with filtration, and the final electrolyte product (V 3.5+ electrolyte product) is obtained.
- FIG. 16 the apparatus configuration and process flow chart for preparing the electrolyte of Comparative Example 10 are shown in FIG. 16 below.
- hydrazine monohydrate N 2 H 4 ⁇ H 2 O
- vanadium compound V 2 O 5
- sulfuric acid H 2 SO 4
- DIW deionized water
- the reactant is cooled to -25 to 20 °C, and then the impurities are removed by passing through a circulation pipe equipped with a filtration means without input of a subsequent solvent, and then a jacketed heat exchanger surrounding the reaction tank (
- a two-step reduction reaction proceeds by heating the reactant with a heater). Water vapor generated during the reduction reaction, water vapor in the nitrogen gas (N 2 ) is cooled by an open reflux condenser and recovered to the reactor, and the nitrogen gas (N 2 ) may be discharged to the outside through the open reflux condenser.
- impurities are removed once more through the discharge pipe equipped with filtration, and the final electrolyte product (V 3.5+ electrolyte product) is obtained.
- the oxidation number of vanadium was measured using a UV spectrometer for each reaction step in the electrolyte preparation process, and the reaction time is shown in Table 4 and FIG. 7 below.
- the impurity Si content and Al content in the electrolyte were measured using an ICP-OES apparatus, respectively, and the results are shown in Table 4 below.
- the secondary battery was charged with a constant current at room temperature with a current of 100mA/cm 2 until the voltage reached 1.60V, and then discharged with a reverse constant current of 100mA/cm 2 until the voltage reached 0.8V during discharging.
- the cycle as described above was repeated 30 times to calculate the average value thereof, and the results are shown in Table 4 and FIGS. 8 to 10, respectively.
- Example 10 25:75 2 3.5 8.5 2.53 2.43 83.84
- Example 12 50:50 5 5.6 10.6 2.53 2.45 85.15
- Example 13 75:25 8 7.1 11.5 2.51 2.44 85.04 Comparative Example 7 100:0 14 20.4 15.5 2.42 2.33 83.10
- the impurity content in the electrolyte was reduced by up to 82.8% for Si and by up to 45.2% for Al compared to Comparative Example, respectively, and the reaction time was shortened by up to 85.7%.
- the reaction time was shortened by up to 85.7%.
- FIG. 8 in Examples 10, 12 to 13, it takes at most 600 minutes or less to reduce the vanadium compound to an oxidation number of 3.5, whereas in Comparative Example 3, it takes at least 840 minutes, so the production method of the present invention The effect of shortening the reaction time was confirmed.
- the charging capacity is at least 2.51 Ah, whereas in the case of the comparative example, 2.42 Ah is at least 0.09 Ah lower, and the present invention
- the discharge capacity was at least 2.43 Ah, whereas in Comparative Example 5, it was 2.33 Ah, which was at least 0.10 Ah lower.
- the energy efficiency is at least 83.84%, which is at least 0.74% lower than that of the comparative example 83.10%. This can be interpreted as meaning that the quality and battery performance of the electrolyte solution to which the process proposed in the present invention is applied has an effect of improving.
- Example 12 is the most excellent in terms of battery performance such as charge capacity, discharge capacity and energy efficiency. This may be an example showing that even the theoretical minimum amount of the above-described exclusive solvent is not necessarily the best in battery performance.
- Impurities in each of the electrolytes prepared in Examples 10 to 14 and Comparative Examples 5 to 10 were measured using an ICP device. The measured results are shown in Table 5 below, respectively.
- the impurity content in the electrolyte was reduced by up to 87.4% for Al, up to 26.2% for Ca, up to 71.2% for Fe, and up to 89.0% for Si compared to Comparative Example. .
- Example 10 in which only the order of the cooling step and the subsequent solvent injection step was changed, in Example 10 in which the cooling step was performed, Fe was further purified, whereas in Example 11 in which the subsequent solvent injection step was performed in advance The effect of further purification of Si was confirmed.
- Example 14 which was filtered while performing the cooling step in advance, it was confirmed that a good effect was exhibited across the four types of impurities such as Al, Ca, Fe, and Si such that the impurities of Fe were significantly reduced.
- Example 14 when comparing Example 14, in which a post solvent was introduced and circulated while cooling, Comparative Example 9, in which a circulation filtration was performed while cooling to room temperature, and Comparative Example 10, in which a subsequent solvent was introduced and filtered while cooling at a low temperature, Comparative Example 10 was subjected to circulating filtration while cooling at a low temperature. , and in the case of circulation filtration, it was confirmed that the four impurities of Al, Ca, Fe, and Si were maximized and removed.
- the process of the present invention has excellent impurity improvement effect while greatly shortening the reaction time, and at the same time the secondary battery performance of the prepared electrolyte is excellent, By reducing impurities under the reaction time and providing high-quality performance, it can be applied to all fields where vanadium redox flow batteries are used, such as renewable energy, smart grids, and power plants.
Abstract
Description
구분 | 실시예1 | 실시예2 | 실시예3 | 실시예4 | 실시예5 | 실시예6 | 비교예1 | 비교예2 |
산화환원 첨가제 (중량부) |
0.1 | 0.2 | 0.4 | 0.8 | 1.6 | 0.8 | - | 10 |
원료 순도 | 저품위 | 저품위 | 저품위 | 저품위 | 저품위 | 고품위 | 저품위 | 저품위 |
반응소요 시간(hr) |
12 | 10 | 8 | 6.5 | 5.5 | 6.5 | - | 1.5 |
최종 산화수 |
3.503 | 3.498 | 3.500 | 3.501 | 3.500 | 3.499 | 3.501 | 3.501 |
충전 용량 (Ah) | 2.30 | 2.31 | 2.24 | 2.31 | 2.16 | 2.34 | 2.16 | 1.71 |
방전 용량 (Ah) | 2.22 | 2.22 | 2.15 | 2.21 | 2.08 | 2.25 | 2.08 | 1.64 |
에너지효율(%) | 80.72 | 81.08 | 80.74 | 80.57 | 78.55 | 80.72 | 79.56 | 79.81 |
함량(ppm) | 71.0 | 134.2 | 271.6 | 538.5 | 1118.4 | 532.2 | - | 5974.2 |
구분 | 참고예1a | 참고예1b | 참고예2a | 참고예2b | 참고예3a | 참고예3b | 참고예4a | 참고예4b |
첨가제 | H3PO4 | H3PO4 | H3PO4 | H3PO4 | H3PO4 | H3PO4 | H3PO4 | H3PO4 |
V2O5대비 첨가제량 |
3중량부 | 3중량부 | 6중량부 | 6중량부 | 9중량부 | 9중량부 | 12중량부 | 12중량부 |
산화수 | 3.501 | 3.500 | 3.500 | 3.502 | 3.501 | 3.499 | 3.499 | 3.500 |
산화환원 첨가제량 | 0.4중량부 | 전기분해 | 0.4중량부 | 전기분해 | 0.4중량부 | 전기분해 | 0.4중량부 | 전기분해 |
반응소요시간 | 8h | 전기분해 | 8h | 전기분해 | 8h | 전기분해 | 8h | 전기분해 |
5가이온 석출시간 (50℃) |
~110h | ~110h | ~180h | ~180h | ~250h | ~250h | ~320h | ~320h |
구분 | 용매 비율 (전:후) | 반응 시간 (hr) |
불순물 Si (ppm) |
불순물 Al (ppm) |
충전 용량 (Ah) |
방전 용량 (Ah) |
에너지 효율 (%) |
실시예 7 | 25:75 | 2 | 3.5 | 8.5 | 2.53 | 2.43 | 83.84 |
실시예 8 | 50:50 | 5 | 5.6 | 10.6 | 2.53 | 2.45 | 85.15 |
실시예 9 | 75:25 | 8 | 7.1 | 11.5 | 2.51 | 2.44 | 85.04 |
비교예 3 | 100:0 | 14 | 20.4 | 15.5 | 2.42 | 2.33 | 83.10 |
구분 | 용매 비율 (전:후) | 반응 시간 (hr) |
불순물 Si (ppm) |
불순물 Al (ppm) |
충전 용량 (Ah) |
방전 용량 (Ah) |
에너지 효율 (%) |
실시예 10 | 25:75 | 2 | 3.5 | 8.5 | 2.53 | 2.43 | 83.84 |
실시예 12 | 50:50 | 5 | 5.6 | 10.6 | 2.53 | 2.45 | 85.15 |
실시예 13 | 75:25 | 8 | 7.1 | 11.5 | 2.51 | 2.44 | 85.04 |
비교예 7 | 100:0 | 14 | 20.4 | 15.5 | 2.42 | 2.33 | 83.10 |
구분 | 불순물 Al (ppm) |
불순물 Ca (ppm) |
불순물 Fe (ppm) |
불순물 Si (ppm) |
실시예 10 | 2.3 | 7.4 | 6.2 | 2.4 |
실시예 11 | 2.2 | 7.3 | 7.3 | 1.8 |
실시예 14 | 2.1 | 7.4 | 2.5 | 2.2 |
비교예 5 | 4.5 | 9.9 | 8.8 | 4.1 |
비교예 6 | 4.8 | 9.5 | 8.7 | 4.3 |
비교예 8 | 16.7 | 9.1 | 8.5 | 16.5 |
비교예 9 | 4.6 | 8.2 | 3.3 | 4.0 |
비교예 10 | 9.3 | 9.3 | 5.6 | 6.1 |
Claims (23)
- 5가 바나듐 화합물과 물을 투입한 다음 질소계 환원제와 산을 순차 투입하여 4가 바나듐 화합물로 환원 반응시키는 제1 단계; 및상기 4가 바나듐 화합물을 3.3 내지 3.7가 바나듐 화합물로 환원 반응시키는 제2 단계를 포함하되,상기 제1 단계의 환원 반응 및 상기 제2 단계의 환원 반응 중에서 선택된 하나 이상의 환원 반응에서의 반응속도가 저감되는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 질소계 환원제보다 환원력이 낮은 산화환원 첨가제를 사용하여 상기 환원 반응에서의 반응속도를 저감시키는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제2항에 있어서,상기 산화환원 첨가제는 상기 산과 탈수반응하여 수용액을 형성한 다음 자체 환원되면서 상기 질소계 환원제를 산화시켜 질소 기체를 발생시키는 것을 특징으로 하는 바나듐 전해액의 제조방법.
- 제3항에 있어서,상기 산화환원 첨가제는 몰리브데넘 금속, 산화몰리브데넘(MoxOy), 질화몰리브데넘(MoxNy), 염화몰리브데넘(MoxCly), 황화몰리브데넘(MoxSy), 인화몰리브데넘(MoxPy), 탄화몰리브데넘(MoxCy), 몰리브데넘 금속 산화물(MoxMyOz), 몰리브데넘 금속 질화물(MoxMyNz), 몰리브데넘 금속 염화물(MoxMyClz), 몰리브데넘 금속 황화물(MoxMySz), 몰리브데넘 금속 인화물(MoxMyPz) 및 몰리브데넘 금속 탄화물(MoxMyCz) 중에서 선택된 1종 이상인 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제4항에 있어서,상기 산화환원 첨가제의 금속은 Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Mg, Mn, Na, Ni, Pb, Si, Sn, Ti, Zn, Au, Ag, Pt, Ru, Pd, Li, Ir, W, Nb, Zr, Ta, Ge, 및 In 중에서 선택된 종 또는 복수의 종이 합금을 이룬 금속일 수 있고, 상기 x와 y(x/y) 또는 x,y 및 z(x/y/z)는 서로 독립적으로 0 내지 1의 정수인 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제5항에 있어서,상기 산화환원 첨가제는 상기 5가 바나듐 화합물 100 중량부 기준으로 0.1 내지 1.6 중량부로 포함하는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 질소계 환원제는 상기 바나듐 화합물 100 중량부 기준으로 10 내지 35 중량부로 포함하는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 5가 바나듐 화합물 및 질소계 환원제의 몰 농도(M; mol/L)의 비는 1 : 0.1 내지 1.6인 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 산은 황산, 염산, 질산 및 아세트산 중에서 선택된 1종 이상이고, 상기 산으로부터의 프로톤 이온 농도는 바나듐 화합물 1몰 당 1 내지 20몰인 것인 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 제2 단계는 70 내지 120 ℃ 하에 수행하는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 5가 바나듐 화합물은 순도 90 % 이상, 99.9 % 미만의 저품위 화합물이거나, 순도 99.9 % 이상의 고품위 화합물인 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항에 있어서,상기 제1 단계 이후 또는 제2 단계 이후에 여과하는 단계를 포함하는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제1항 또는 제2항에 있어서,상기 제1 단계에 물을 상기 바나듐 화합물 1몰 당 5 내지 15 몰로 사용하고, 상기 제2 단계에서 생성된 바나듐 화합물을 상온 이하로 냉각한 다음 물을 앞서 투입된 함량보다 과량으로 투입하고 반응 용액을 여과시켜 상기 환원 반응에서의 반응속도를 저감시키는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제13항에 있어서,상기 과량으로 투입된 물은 1.6몰 바나듐, 4.0몰 황산의 조성에 대하여 42 내지 44몰 범위 내인 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제13항에 있어서,상기 제1 단계에 물을 바나듐 화합물 1몰 당 5 내지 15 몰로 사용하고, 100 ℃ 이상에서 반응시켜 바나듐 화합물을 형성한 다음 물을 앞서 투입된 함량보다 과량으로 투입하고 환원된 바나듐 화합물을 -25 내지 20 ℃로 냉각한 다음 -25 내지 40 ℃ 하에 반응 용액을 순환 여과시켜 상기 환원 반응에서의 반응속도를 저감시키는 것을 특징으로 하는 바나듐 전해액 제조방법.
- 제13항에 있어서,상기 제1 단계에 물을 바나듐 화합물 1몰 당 5 내지 15 몰로 사용하고, 100 ℃ 이상에서 반응시켜 바나듐 화합물을 형성한 다음 환원된 바나듐 화합물을 -25 내지 20 ℃로 냉각하고 물을 앞서 투입된 함량보다 과량으로 투입하고 -25 내지 40 ℃ 하에 반응 용액을 순환 여과시켜 상기 환원 반응에서의 반응속도를 저감시키는 것을 특징으로 하는 바나듐 전해액 제조방법.
- (A)용매에 5가 바나듐 화합물을 투입한 다음 질소계 환원제를 투입하여 반응 혼합물을 제조하는 단계;(B)상기 반응 혼합물에 산과 산화환원 첨가제를 투입하여 탈수 반응을 수행하면서 상기 5가 바나듐 화합물을 4가 바나듐 화합물로 환원시키는 단계;(C)상기 탈수 반응물이 상기 질소계 환원제를 산화시켜 질소 기체를 생성하면서 자체 환원물을 생성하는 단계; 및(D)상기 반응물을 가온하여 상기 자체 환원물이 산화되면서 상기 4가 바나듐 화합물을 3.3 내지 3.7가 바나듐 화합물로 환원시키는 단계; 를 포함하며,상기 질소계 환원제는 상기 (A) 단계에 전량 투입하거나 혹은 (A) 단계와 (D) 단계에 분할 투입하는 것을 특징으로 하는 바나듐 전해액의 제조방법.
- 제17항에 있어서,상기 산화환원 첨가제는 산과의 탈수 반응에 의한 수용액 상태로 반응에 참여하여 산화환원 첨가제 유래 부산물이 생성되지 않는 것을 특징으로 하는 바나듐 전해액의 제조방법
- 제17항에 있어서,상기 (D) 단계는 70 내지 120 ℃의 반응 온도와 산화환원 첨가제의 투입량을 하기 수학식 1에 대입하여 계산된 바나듐 화합물의 환원반응시간을 적용하여 수행하는 것을 특징으로 하는 바나듐 전해액 제조방법.[수학식 1]tR = Aln(Ma/Mv)+ B(여기서, tR은 반응시간(min)이고, A는 속도상수, B는 농도상수, Ma는 산화환원 첨가제의 투입량(g), Mv는 바나듐 화합물의 투입량(g)이다)
- 바나듐 화합물, 환원제 및 산을 상기 바나듐 화합물 1몰 당 5 내지 15 몰의 전용매 하에 100 ℃ 이상에서 반응시켜 환원된 바나듐 화합물을 형성하는 제1 단계;상기 반응 완료 후 환원된 바나듐 화합물을 -25 내지 20 ℃로 냉각하는 제2 단계; 및냉각된 바나듐 전해액을 -25 내지 40 ℃ 조건에서 순환 여과하는 제3 단계를 포함하는 바나듐 전해액 제조방법.
- 제1항 내지 제20항 중 어느 한 항의 방법에 의해 제조된 바나듐 전해액.
- 제21항의 바나듐 전해액을 포함하는 레독스 플로우 전지.
- 제22항에 있어서,상기 바나듐 전해액은 양극 및 음극에 포함되는 것을 특징으로 하는 레독스 플로우 전지.
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JP2001052731A (ja) * | 1999-08-16 | 2001-02-23 | Nippon Chem Ind Co Ltd | 3価のバナジウム系電解液の製造方法 |
JP2002175831A (ja) | 2000-09-29 | 2002-06-21 | Shinko Kagaku Kogyo Kk | バナジウムレドックスフロー電池用電解液の製造方法 |
JP2016162529A (ja) * | 2015-02-27 | 2016-09-05 | 昭和電工株式会社 | レドックスフロー電池用電解液およびレドックスフロー電池 |
KR20200119773A (ko) * | 2020-10-12 | 2020-10-20 | 한국과학기술원 | 촉매반응을 이용한 바나듐 레독스 흐름전지용 고순도 전해액의 제조방법 |
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2021
- 2021-11-22 WO PCT/KR2021/017147 patent/WO2022215822A1/ko active Application Filing
- 2021-11-22 EP EP21936160.7A patent/EP4322268A1/en active Pending
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JP2001052731A (ja) * | 1999-08-16 | 2001-02-23 | Nippon Chem Ind Co Ltd | 3価のバナジウム系電解液の製造方法 |
JP2002175831A (ja) | 2000-09-29 | 2002-06-21 | Shinko Kagaku Kogyo Kk | バナジウムレドックスフロー電池用電解液の製造方法 |
JP2016162529A (ja) * | 2015-02-27 | 2016-09-05 | 昭和電工株式会社 | レドックスフロー電池用電解液およびレドックスフロー電池 |
KR20200119773A (ko) * | 2020-10-12 | 2020-10-20 | 한국과학기술원 | 촉매반응을 이용한 바나듐 레독스 흐름전지용 고순도 전해액의 제조방법 |
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HWANG DEOKHYUN, HA JONG-WOOK, YOUNG &, PARK SOO: "Molybdenum-assisted reduction of VO 2+ for low cost electrolytes of vanadium redox flow batteries", RESEARCH SQUARE, 16 April 2021 (2021-04-16), pages 1 - 34, XP055976158, DOI: 10.21203/rs.3.rs-402509/v1> * |
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