A method for recycling and regenerating waste vanadium electrolyte, regenerated vanadium electrolyte and application thereof

Abstract

This application relates to the field of vanadium redox flow battery electrolyte technology, and discloses a method for recycling and regenerating waste vanadium electrolyte, the regenerated vanadium electrolyte, and its application. The recycling and regeneration method includes the following steps: filtering, concentrating, and acid-adjusting the waste vanadium electrolyte to obtain a pretreated electrolyte; subjecting the pretreated electrolyte to electrochemical oxidation-reduction treatment to obtain a pre-reduced waste electrolyte; passing the pre-reduced waste electrolyte into the negative electrode of a permeation stack, and passing a diluted electrolyte containing sulfonated quaternary ammonium salt into the positive electrode of the permeation stack, performing forced shuttle treatment based on mobility differences to obtain a pure high-valence electrolyte and tailings; and adjusting the valence state of the pure high-valence electrolyte to obtain a regenerated vanadium electrolyte. This invention achieves the recycling and regeneration of waste vanadium electrolyte through an electrochemical method, which is low-cost, has a short process, simple equipment, and requires few chemicals, making it suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of vanadium redox flow battery electrolyte technology, and in particular to a method for recycling and regenerating waste vanadium electrolyte, as well as the regenerated vanadium electrolyte and its application. Background Technology

[0002] Vanadium redox flow batteries (vanadium batteries) are the most widely used flow energy storage technology in grid-side peak shaving, new energy supporting energy storage, and distributed microgrid energy storage, thanks to their advantages such as power-capacity decoupling, cycle life exceeding 20,000 cycles, intrinsic safety, and strong low-temperature adaptability. Vanadium electrolyte, as the only active energy storage medium in vanadium redox flow batteries, accounts for 45% to 55% of the initial construction cost of the energy storage system. The mainstream commercial system is a 1.6~2.0 mol / L sulfuric acid system vanadium electrolyte, composed of V... 2+ / V 3+ Negative electrode couple, VO 2 + / VO2 + The positive electrode couple constitutes a redox cycle system.

[0003] Waste vanadium electrolyte after long-term use contains organic matter and Fe. 3+ Al 3+ Mn 2+ NH4 + Impurities such as these can affect battery performance. However, the vanadium content in waste vanadium electrolyte can reach 1.5~2.0 mol / L, and the vanadium resource enrichment is far greater than that of primary vanadium ore leaching solution. If the waste vanadium electrolyte is directly outsourced for disposal, it will not only cause permanent loss of high-value vanadium resources and increase the life cycle cost of vanadium batteries, but the high concentration of sulfuric acid and vanadium ions in the waste liquid will also cause soil acidification and heavy metal pollution of groundwater. The commonly used recycling and regeneration methods are mainly: (1) Vanadium precipitation-preparation, the process is filtration to remove impurities-oxidation-pH adjustment-ammonium salt precipitation-calcination-vanadium pentoxide sulfuric acid dissolution to prepare electrolyte. This method has defects such as high cost, complex process and need for special equipment; (2) Electroreduction method, the process is filtration to remove impurities-electroreduction to adjust the valence state to 3.5. Although the process is simple, it can only restore the valence state and cannot remove impurities; (3) Chemical reduction method, this method is similar to electroreduction, the only difference is that chemical reduction is used instead of electroreduction, but it still cannot solve the problem of the influence of impurities in waste electrolyte.

[0004] Therefore, developing low-cost, low-impurity, short-process, and adaptable technologies for recycling and regenerating waste vanadium electrolytes for large-scale power plants is a core necessity for reducing costs and ensuring compliant and environmentally friendly disposal throughout the entire life cycle of vanadium batteries. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a method for recycling and regenerating waste vanadium electrolyte, as well as the regenerated vanadium electrolyte and its applications.

[0006] In the first aspect, a method for recycling and regenerating waste vanadium electrolyte is disclosed, comprising the following steps: Step S1: Filter, concentrate, and acid-adjust the waste vanadium electrolyte to obtain a pretreated electrolyte; Step S2: Pass the pretreated electrolyte into the pretreated stack for electrochemical oxidation-reduction treatment to obtain pre-reduced waste electrolyte; Step S3: Pass the pre-reduced waste electrolyte into the negative electrode of the permeation stack, and pass the diluted electrolyte containing sulfonated quaternary ammonium salt into the positive electrode of the permeation stack to perform forced shuttle treatment based on the mobility difference to obtain pure high-valence electrolyte and tail liquid; wherein, the volume ratio of the positive electrode to the negative electrode of the permeation stack is (2~2.5):1. Step S4: Remove impurities and concentrate the tail liquid, and add the concentrated tail liquid to the pre-reduced waste electrolyte for reuse in step S3; Step S5: Adjust the valence state of the pure high-valence electrolyte to obtain a regenerated vanadium electrolyte.

[0007] In one implementation, in step S1: The concentration is achieved by vacuum rotary evaporation at a temperature of 60°C and a rotation speed of 80 rpm, resulting in a vanadium ion concentration of 2-2.5 mol / L after concentration. The acid adjustment is achieved by adding concentrated sulfuric acid to adjust the hydrogen ion concentration of the pretreated electrolyte to 5-7 mol / L.

[0008] Rotary evaporation removes volatile substances from waste vanadium electrolyte and improves space utilization by concentrating the waste vanadium electrolyte. At the same time, it increases the concentration of vanadium ions in the waste electrolyte. The higher the concentration, the more vanadium ions shuttle across the membrane per unit time.

[0009] In one implementation, in step S2: The electrochemical oxidation-reduction treatment method involves charging the pretreated electrolyte by passing it through the positive electrode of the pretreated stack to obtain a pre-oxidized waste electrolyte; then, charging the pre-oxidized waste electrolyte through the negative electrode of the pretreated stack to obtain the pre-reduced waste electrolyte; wherein... The pre-treated battery stack has 3 to 10 cells, the plates are carbon-plastic bipolar plates with a thickness of 1 to 1.5 mm, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 60 to 120 μm. The charging process employs a constant voltage charging method, and the average single-cell voltage of the pre-treated battery stack is 1.65V. The vanadium ion valence state in the pre-oxidized waste electrolyte is 4.5~5; The vanadium ion valence state in the pre-reduced waste electrolyte is 2~2.5.

[0010] Because waste vanadium electrolyte may contain reducing organic matter, pre-oxidation treatment can oxidize and decompose these substances. Carbon-plastic bipolar plates have better anti-foaming and anti-bubbling properties than graphite bipolar plates, effectively avoiding the adverse effects of localized voltage unevenness caused by the high resistance of waste vanadium electrolyte. The use of a thicker perfluorosulfonic acid resin membrane for the diaphragm effectively prevents the loss of vanadium ions.

[0011] In one implementation, in step S3: The number of cells in the permeation stack is 5 to 10. The plates are made of carbon-plastic bipolar plates with a thickness of 0.8 to 1 mm, the electrodes are made of graphite felt with a thickness of 4 to 6 mm, and the diaphragm is made of either perfluorosulfonic acid resin membrane or polybenzimidazole membrane with a thickness of 20 to 50 μm. The forced shuttle process is as follows: The average single-cell voltage of the permeation stack is set to 1.65V, and at a temperature of 50~60℃, the current is initially applied at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 It continuously undergoes charge-discharge cycles.

[0012] Using 4-6mm thick graphite felt in the permeation stack can effectively prevent the precipitation of pentavalent vanadium ions from clogging the flow channels. A thinner diaphragm and a higher charging temperature further facilitate the transport of vanadium ions from the waste vanadium electrolyte at the negative electrode to the positive electrode.

[0013] The forced shuttle process firstly avoids the presence of a large concentration of pentavalent vanadium ions at the positive electrode, thereby reducing the precipitation of pentavalent vanadium ions. Secondly, the low current density charging and high current density discharging can effectively increase the net shuttle amount of vanadium ions from the negative electrode to the positive electrode, accelerating the recovery process. Finally, continuous charge and discharge cycles can prevent material damage caused by the fuel cell stack being under high voltage for a long time.

[0014] In one implementation, in step S3: The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt and water, wherein the concentration of sulfate ions in the diluted electrolyte is 4~5 mol / L, the concentration of vanadium ions is 1 mol / L, the valence state of vanadium ions is 3.5~4, and the concentration of sulfonated quaternary ammonium salt is 10~50 mg / L. The concentration of vanadium ions in the pure high-valence electrolyte is 1.5~1.7 mol / L.

[0015] Introducing sulfonated quaternary ammonium salts into the diluted electrolyte can reduce the precipitation of pentavalent vanadium at the positive electrode at high temperatures and decrease the shuttle rate of vanadium ions from the positive electrode to the negative electrode. The significant concentration difference between the positive and negative electrodes of the permeation stack can effectively increase the shuttle rate of vanadium ions from the negative electrode to the positive electrode.

[0016] In one implementation, in step S4: The method for removing impurities and concentrating the liquid involves adding barium chloride solution to the tailings and centrifuging the solution; wherein, The centrifugation process is carried out at a speed of 10,000 to 15,000 rpm for a time of 5 to 10 minutes. The concentration of the barium chloride solution is 1 mol / L; The volume ratio of the barium chloride solution to the tail liquid is (1~1.7):1; The vanadium ion concentration in the tail liquid after impurity removal and concentration is 2~2.5 mol / L.

[0017] Barium chloride can remove some of the sulfate ions from the tailings, thereby reducing the sulfuric acid concentration in the concentrated tailings.

[0018] In one implementation, in step S5: The valence state adjustment is achieved by charging the valence-balanced electrode stack by introducing the pure high-valence electrolyte; wherein... The number of cells in the valence-balanced stack is 3 to 10, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 60 to 120 μm. The vanadium ions in the regenerated vanadium electrolyte have a valence state of 3.5.

[0019] The positive electrode of a valence equilibrium stack can be a mixed solution of vanadium electrolyte and citric acid, where vanadium ions act as a catalyst for the decomposition of citric acid.

[0020] In one embodiment, the waste vanadium electrolyte is a sulfuric acid-based electrolyte.

[0021] Secondly, a regenerated vanadium electrolyte is disclosed, which is prepared using the above-mentioned recycling and regeneration method.

[0022] Thirdly, an application of a regenerated vanadium electrolyte is disclosed, wherein the regenerated vanadium electrolyte prepared by the above-mentioned recycling and regeneration method is used in vanadium batteries; wherein... The coulombic efficiency of the regenerated vanadium electrolyte in the vanadium battery is not less than 99%; The energy efficiency of the recycled vanadium electrolyte in the vanadium battery is not less than 86.5%; After the vanadium battery has been operated for 200 cycles, the capacity retention rate of the regenerated vanadium electrolyte is not less than 97.9%.

[0023] The beneficial effects of this invention are: 1. This invention achieves the recycling and regeneration of waste vanadium electrolyte through an electrochemical method. It not only has a shorter process and directly produces electrolyte, but also reduces the need for special equipment (such as high-temperature furnaces). At the same time, the amount of chemicals required is small, further reducing costs.

[0024] 2. In the vanadium ion permeation process, the present invention adopts a stepped charge-discharge cycle method. First, the charge-discharge cycle can avoid the presence of a large concentration of pentavalent vanadium ions at the positive electrode, thereby reducing the precipitation of pentavalent vanadium ions. Second, the low current density charging and high current density discharging can effectively increase the net shuttle amount of vanadium ions from the negative electrode to the positive electrode, and accelerate the recovery process. Finally, the continuous charge-discharge cycle can avoid material damage caused by the stack being under high voltage for a long time.

[0025] 3. In this invention, the introduction of sulfonated quaternary ammonium salt into the diluted electrolyte of the positive electrode during the vanadium ion permeation process can reduce the precipitation of pentavalent vanadium at high temperatures and reduce the rate at which vanadium ions shuttle from the positive electrode to the negative electrode. At the same time, it can also improve the coulombic efficiency, energy efficiency, voltage efficiency and capacity retention of the subsequently obtained pure electrolyte in the vanadium battery.

[0026] 4. The large concentration difference between the positive and negative electrodes of the permeation stack can effectively increase the shuttle rate of vanadium ions from the negative electrode to the positive electrode, reducing the recycling and regeneration time.

[0027] 5. This invention improves the performance of regenerated vanadium electrolyte by pre-oxidizing and decomposing organic matter and allowing vanadium ions to permeate across the membrane, effectively preventing impurity elements from entering the pure electrolyte. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a method for recycling and regenerating waste vanadium electrolyte according to the present invention. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] like Figure 1 As shown, a method for recycling and regenerating waste vanadium electrolyte includes the following steps: Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2~2.5mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5~7mol / L, and obtain the pretreated electrolyte.

[0031] Step S2: Assemble the pretreated battery stack with 3-10 cells. The plates are carbon-plastic bipolar plates with a thickness of 1-1.5 mm, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 60-120 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5-5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2-2.5 is obtained.

[0032] Step S3: Assemble the permeation stack with 5-10 cells. The plates are made of carbon-plastic bipolar plates with a thickness of 0.8-1 mm, the electrodes are made of graphite felt with a thickness of 4-6 mm, and the diaphragm is either a perfluorosulfonic acid resin membrane or a polybenzimidazole membrane with a thickness of 20-50 μm. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is (2-2.5):1. The average single-cell voltage is set to 1.65 V. At a temperature of 50-60℃, the voltage is initially increased at 50 mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The electrolyte undergoes continuous charge-discharge cycles, yielding a pure high-valence electrolyte with a vanadium ion concentration of 1.5~1.7 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 4~5 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.5~4, and the sulfonated quaternary ammonium salt concentration is 10~50 mg / L.

[0033] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of (1~1.7):1. After reacting for a period of time, centrifuge at 10000~15000 rpm for 5~10 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2~2.5 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0034] Step S5: Assemble the valence equilibrium battery stack with 3-10 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60-120 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0035] Example 1: The following technical solution is adopted. Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5mol / L, and obtain the pretreated electrolyte.

[0036] Step S2: Assemble the pretreated battery stack with 3 cells. The plates are carbon-plastic bipolar plates with a thickness of 1 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.5 is obtained.

[0037] Step S3: Assemble the permeation stack with 5 cells. The plates are made of 0.8mm thick carbon-plastic bipolar plates, the electrodes are made of 4mm thick graphite felt, and the diaphragm is a 20μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2:1. The average single-cell voltage is set to 1.65V. At a temperature of 50℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.5 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 4 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.5, and the sulfonated quaternary ammonium salt concentration is 10 mg / L.

[0038] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1:1. After reacting for a period of time, centrifuge at 10,000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0039] Step S5: Assemble the valence equilibrium battery stack with 3 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0040] Example 2: The following technical solution is adopted. Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2.5mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 7mol / L, and obtain the pretreated electrolyte.

[0041] Step S2: Assemble the pretreated battery stack with 10 cells. The plates are carbon-plastic bipolar plates with a thickness of 1.5 mm, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 120 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2 is obtained.

[0042] Step S3: Assemble the permeation stack with 10 cells. The plates are 1mm thick carbon-plastic bipolar plates, the electrodes are 6mm thick graphite felt, and the diaphragm is a 50μm thick polybenzimidazole membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2.5:1. The average single-cell voltage is set to 1.65V. At a temperature of 60℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.7 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 5 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 4, and the sulfonated quaternary ammonium salt concentration is 50 mg / L.

[0043] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1.7:1. After reacting for a period of time, centrifuge at 15000 rpm for 10 min to obtain a supernatant. Concentrate the supernatant to obtain a vanadium ion concentration of 2.5 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0044] Step S5: Assemble the valence equilibrium battery stack with 10 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 120 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0045] Example 3: The following technical solution is adopted. Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2.3mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 6mol / L, and obtain the pretreated electrolyte.

[0046] Step S2: Assemble the pretreated battery stack with 5 cells. The plates are carbon-plastic bipolar plates with a thickness of 1.2 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 100 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.7 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.3 is obtained.

[0047] Step S3: Assemble the permeation stack with 8 cells. The plates are made of 0.9mm thick carbon-plastic bipolar plates, the electrodes are made of 5mm thick graphite felt, and the diaphragm is a 40μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2.3:1. The average single-cell voltage is set to 1.65V. At a temperature of 55℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.6 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 4.5 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.7, and the sulfonated quaternary ammonium salt concentration is 30 mg / L.

[0048] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1.5:1. After reacting for a period of time, centrifuge at 12000 rpm for 7 min to obtain a supernatant. Concentrate the supernatant to obtain a vanadium ion concentration of 2.3 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0049] Step S5: Assemble the valence equilibrium battery stack with 7 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 100 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0050] Example 4: The following technical solution is adopted. Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2.5mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 7mol / L, and obtain the pretreated electrolyte.

[0051] Step S2: Assemble the pretreated battery stack with 8 cells. The plates are carbon-plastic bipolar plates with a thickness of 1.2 mm, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 120 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.9 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.1 is obtained.

[0052] Step S3: Assemble the permeation stack with 10 cells. The plates are 1mm thick carbon-plastic bipolar plates, the electrodes are 6mm thick graphite felt, and the diaphragm is a 30μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2.5:1. The average single-cell voltage is set to 1.65V. At a temperature of 60℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm²2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.7 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 5 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 4, and the sulfonated quaternary ammonium salt concentration is 10 mg / L.

[0053] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1.7:1. After reacting for a period of time, centrifuge at 15000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a concentration of 2 mol / L of vanadium ions, and add it to the pre-reduced waste electrolyte for step S3.

[0054] Step S5: Assemble the valence equilibrium battery stack with 10 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 120 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0055] Comparative Example 1: The following technical solution is adopted. Blank raw electrolyte.

[0056] Comparative Example 2: The following technical solution is adopted. The only difference from Example 1 is that no concentration operation was performed in step S1.

[0057] Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5 mol / L to obtain the pretreated electrolyte.

[0058] Step S2: Assemble the pretreated battery stack with 3 cells. The plates are carbon-plastic bipolar plates with a thickness of 1 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.5 is obtained.

[0059] Step S3: Assemble the permeation stack with 5 cells. The plates are made of 0.8mm thick carbon-plastic bipolar plates, the electrodes are made of 4mm thick graphite felt, and the diaphragm is a 20μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2:1. The average single-cell voltage is set to 1.65V. At a temperature of 50℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.5 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 4 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.5, and the sulfonated quaternary ammonium salt concentration is 10 mg / L.

[0060] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1:1. After reacting for a period of time, centrifuge at 10,000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0061] Step S5: Assemble the valence equilibrium battery stack with 3 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0062] Comparative Example 3: The following technical solution is adopted. The difference compared to Example 1 is that step S3 involves a normal charge-discharge cycle.

[0063] Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5mol / L, and obtain the pretreated electrolyte.

[0064] Step S2: Assemble the pretreated battery stack with 3 cells. The plates are carbon-plastic bipolar plates with a thickness of 1 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.5 is obtained.

[0065] Step S3: Assemble the permeation stack with 5 cells. The plates are made of 0.8mm thick carbon-plastic bipolar plates, the electrodes are made of 4mm thick graphite felt, and the diaphragm is a 20μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2:1. The average single-cell voltage is set to 1.65V at a temperature of 50℃ and a flow rate of 50mA / cm². 2 The current density is used for charge-discharge cycles, and a pure high-valence electrolyte with a vanadium ion concentration of 1.5 mol / L is obtained at the positive electrode, and a tailings solution is obtained at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt and water, wherein the sulfate ion concentration is 4 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.5, and the sulfonated quaternary ammonium salt concentration is 10 mg / L.

[0066] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1:1. After reacting for a period of time, centrifuge at 10,000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0067] Step S5: Assemble the valence equilibrium battery stack with 3 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0068] Comparative Example 4: The following technical solution is adopted. The difference compared to Example 1 is that no sulfonated quaternary ammonium salt was added to the diluted electrolyte in step S3.

[0069] Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5mol / L, and obtain the pretreated electrolyte.

[0070] Step S2: Assemble the pretreated battery stack with 3 cells. The plates are carbon-plastic bipolar plates with a thickness of 1 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.5 is obtained.

[0071] Step S3: Assemble the permeation stack with 5 cells. The plates are made of 0.8mm thick carbon-plastic bipolar plates, the electrodes are made of 4mm thick graphite felt, and the diaphragm is a 20μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2:1. The average single-cell voltage is set to 1.65V. At a temperature of 50℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The charge-discharge cycle is continuously performed, and a pure high-valence electrolyte with a vanadium ion concentration of 1.5 mol / L is obtained at the positive electrode, and a tail liquid is obtained at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions and water, wherein the sulfate ion concentration is 4 mol / L, the vanadium ion concentration is 1 mol / L, and the vanadium ion valence state is 3.5.

[0072] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1:1. After reacting for a period of time, centrifuge at 10,000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0073] Step S5: Assemble the valence equilibrium battery stack with 3 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0074] Comparative Example 5: The following technical solution is adopted. The difference from Example 1 is that the positive to negative volume ratio in step S3 is 1:1.

[0075] Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5mol / L, and obtain the pretreated electrolyte.

[0076] Step S2: Assemble the pretreated battery stack with 3 cells. The plates are carbon-plastic bipolar plates with a thickness of 1 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.5 is obtained.

[0077] Step S3: Assemble the permeation stack with 5 cells. The plates are made of 0.8mm thick carbon-plastic bipolar plates, the electrodes are made of 4mm thick graphite felt, and the diaphragm is a 20μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2:1. The average single-cell voltage is set to 1.65V. At a temperature of 50℃, the voltage is initially increased at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.5 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 4 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.5, and the sulfonated quaternary ammonium salt concentration is 10 mg / L.

[0078] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1:1. After reacting for a period of time, centrifuge at 10,000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0079] Step S5: Assemble the valence equilibrium battery stack with 3 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0080] Comparative Example 6: The following technical solution was adopted. Compared to Example 1, the difference lies in the fact that step S3 is set as a reverse step, with the initial step at 200 mA / cm at a temperature of 50°C. 2 Discharge current density to below 80 mA / cm 2 Then at 50mA / cm 2 Charge to a current density below 20 mA / cm² 2 .

[0081] Step S1: Filter the sulfuric acid-based waste vanadium electrolyte, then place it in a vacuum rotary evaporator, set the temperature to 60℃ and the rotation speed to 80rpm, concentrate the vanadium ion concentration in the waste vanadium electrolyte to 2mol / L, add concentrated sulfuric acid to adjust the hydrogen ion concentration to 5mol / L, and obtain the pretreated electrolyte.

[0082] Step S2: Assemble the pretreated battery stack with 3 cells. The plates are carbon-plastic bipolar plates with a thickness of 1 mm, and the separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The pretreated electrolyte is passed into the positive electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-oxidized waste electrolyte with a vanadium ion valence state of 4.5 is obtained. The pre-oxidized waste electrolyte is then passed into the negative electrode of the pretreated battery stack, and constant voltage charging is performed with an average single-cell voltage of 1.65 V. After completion, a pre-reduced waste electrolyte with a vanadium ion valence state of 2.5 is obtained.

[0083] Step S3: Assemble the permeation stack with 5 cells. The plates are made of 0.8mm thick carbon-plastic bipolar plates, the electrodes are made of 4mm thick graphite felt, and the diaphragm is a 20μm thick perfluorosulfonic acid resin membrane. The pre-reduced waste electrolyte is introduced into the negative electrode of the permeation stack, and the diluted electrolyte is introduced into the positive electrode. The volume ratio of the positive to negative electrodes is 2:1. The average single-cell voltage is set to 1.65V. At a temperature of 50℃, the voltage is initially increased at 200 mA / cm². 2 Discharge current density to below 80 mA / cm 2 Then at 50mA / cm 2 Charge to a current density below 20 mA / cm² 2The system continuously performs charge-discharge cycles, obtaining a pure high-valence electrolyte with a vanadium ion concentration of 1.5 mol / L at the positive electrode and a tailings solution at the negative electrode. The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt, and water, wherein the sulfate ion concentration is 4 mol / L, the vanadium ion concentration is 1 mol / L, the vanadium ion valence state is 3.5, and the sulfonated quaternary ammonium salt concentration is 10 mg / L.

[0084] Step S4: Add a 1 mol / L barium chloride solution to the tail liquid, with a volume ratio of barium chloride solution to tail liquid of 1:1. After reacting for a period of time, centrifuge at 10,000 rpm for 5 min to obtain a supernatant. Concentrate the supernatant to a vanadium ion concentration of 2 mol / L, and add it to the pre-reduced waste electrolyte for step S3.

[0085] Step S5: Assemble the valence equilibrium battery stack with 3 cells. The separator is a perfluorosulfonic acid resin membrane with a thickness of 60 μm. The purified high-valence electrolyte is passed through the negative electrode of the valence equilibrium battery stack for charging, resulting in a regenerated vanadium electrolyte with a valence of 3.5.

[0086] Comparative Example 7: The following technical solution was adopted. After filtering, the waste vanadium electrolyte is electrochemically reduced to a 3.5 valence.

[0087] Battery performance test: The Fe element content of the electrolytes obtained in Examples 1-4 and Comparative Examples 1-7 was tested to evaluate the impurity content in the electrolytes. Simultaneously, the electrolytes obtained in Examples 1-4 and Comparative Examples 1-7 were passed into vanadium batteries, and battery performance was tested under the same operating conditions. Coulombic efficiency, energy efficiency, voltage efficiency, electrolyte utilization rate, and capacity retention rate after 100 charge-discharge cycles were recorded. The test results are shown in Table 1. Table 1 Summary of Battery Performance Test Results

[0088] As shown in Table 1, comparing the recycling and regeneration times, it can be seen that Example 1 has a shorter recycling and regeneration time compared to Comparative Examples 2-4. This is mainly because the waste vanadium electrolyte in Comparative Example 2 was not concentrated, resulting in a smaller concentration difference between the positive and negative electrodes during the vanadium ion permeation process in step S3, and a smaller net shuttle amount of vanadium ions in the negative electrode per unit time. Compared to Comparative Example 3, the stepped charge-discharge cycle method used in Example 1 can avoid the presence of a large concentration of pentavalent vanadium ions in the positive electrode, thereby reducing the precipitation of pentavalent vanadium ions. Charging with a small current density and discharging with a large current density can effectively increase the net shuttle amount of vanadium ions from the negative electrode to the positive electrode, accelerating the recycling process. Moreover, continuous charge-discharge cycles can prevent material damage caused by the stack being under high voltage for a long time. Compared to Comparative Example 4, the sulfonated quaternary ammonium salt added in step S3 of Example 1 can reduce the precipitation of pentavalent vanadium in the positive electrode at high temperature and reduce the shuttle rate of vanadium ions from the positive electrode to the negative electrode.

[0089] Examples 1-4 and Comparative Examples 2-3 exhibit higher coulombic efficiency, energy efficiency, voltage efficiency, and capacity retention after 100 charge-discharge cycles compared to Comparative Examples 1 and 4. This is mainly because the present invention introduces sulfonated quaternary ammonium salts into the diluted electrolyte of the positive electrode during the vanadium ion permeation process. This reduces the precipitation of pentavalent vanadium at high temperatures and decreases the rate at which vanadium ions shuttle from the positive electrode to the negative electrode. It also improves the coulombic efficiency, energy efficiency, voltage efficiency, and capacity retention of the subsequently obtained pure electrolyte in the vanadium battery.

[0090] Compared to Comparative Example 5, although the recovery time of Example 1 was longer, the volume of the regenerated electrolyte was smaller due to the 1:1 volume ratio of the positive and negative electrodes in step S3. Compared to Comparative Example 6, the recovery time of Example 1 was shorter, mainly because Comparative Example 6 used a low charging current density and a high discharging current density in step S3, which reduced the net shuttle amount of vanadium ions from the negative electrode to the positive electrode, thus slowing down the recovery process.

[0091] Compared to Comparative Example 7, Examples 1-4 and Comparative Examples 2-6 have lower Fe content, indicating that the method of this application can effectively extract vanadium ions from waste vanadium electrolyte, while impurity elements are almost entirely retained in the original solution. Meanwhile, the Fe content of Examples 1-4 and Comparative Examples 2-6 is comparable to that of Comparative Example 1, indicating that the impurity element content of the regenerated electrolyte obtained by the method of this application meets the requirements.

[0092] Although the present invention has been preferably disclosed above, it is not intended to limit the present invention. Any person skilled in the art may make appropriate modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A method for recycling and regenerating waste vanadium electrolyte, characterized in that, Includes the following steps: Step S1: Filter, concentrate, and acid-adjust the waste vanadium electrolyte to obtain a pretreated electrolyte; Step S2: Pass the pretreated electrolyte into the pretreated stack for electrochemical oxidation-reduction treatment to obtain pre-reduced waste electrolyte; Step S3: Pass the pre-reduced waste electrolyte into the negative electrode of the permeation stack, and pass the diluted electrolyte containing sulfonated quaternary ammonium salt into the positive electrode of the permeation stack to perform forced shuttle treatment based on the mobility difference to obtain pure high-valence electrolyte and tail liquid; wherein, the volume ratio of the positive electrode to the negative electrode of the permeation stack is (2~2.5):

1. Step S4: Remove impurities and concentrate the tail liquid, and add the concentrated tail liquid to the pre-reduced waste electrolyte for reuse in step S3; Step S5: Adjust the valence state of the pure high-valence electrolyte to obtain a regenerated vanadium electrolyte.

2. The recycling and regeneration method as described in claim 1, characterized in that, In step S1: The concentration is achieved by vacuum rotary evaporation at a temperature of 60°C and a rotation speed of 80 rpm, resulting in a vanadium ion concentration of 2-2.5 mol / L after concentration. The acid adjustment is achieved by adding concentrated sulfuric acid to adjust the hydrogen ion concentration of the pretreated electrolyte to 5-7 mol / L.

3. The recycling and regeneration method as described in claim 1, characterized in that, In step S2: The electrochemical oxidation-reduction treatment method involves charging the pretreated electrolyte by passing it through the positive electrode of the pretreated stack to obtain a pre-oxidized waste electrolyte; then, charging the pre-oxidized waste electrolyte through the negative electrode of the pretreated stack to obtain the pre-reduced waste electrolyte; wherein... The pre-treated battery stack has 3 to 10 cells, the plates are carbon-plastic bipolar plates with a thickness of 1 to 1.5 mm, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 60 to 120 μm. The charging process employs a constant voltage charging method, and the average single-cell voltage of the pre-treated battery stack is 1.65V. The vanadium ion valence state in the pre-oxidized waste electrolyte is 4.5~5; The vanadium ion valence state in the pre-reduced waste electrolyte is 2~2.

5.

4. The recycling and regeneration method as described in claim 1, characterized in that, In step S3: The number of cells in the permeation stack is 5 to 10. The plates are made of carbon-plastic bipolar plates with a thickness of 0.8 to 1 mm, the electrodes are made of graphite felt with a thickness of 4 to 6 mm, and the diaphragm is made of either perfluorosulfonic acid resin membrane or polybenzimidazole membrane with a thickness of 20 to 50 μm. The forced shuttle process is as follows: The average single-cell voltage of the permeation stack is set to 1.65V, and at a temperature of 50~60℃, the current is initially applied at 50mA / cm². 2 Charge to a current density below 20 mA / cm² 2 Then at 200 mA / cm 2 Discharge current density to below 80 mA / cm 2 It continuously undergoes charge-discharge cycles.

5. The recycling and regeneration method as described in claim 1, characterized in that, In step S3: The diluted electrolyte is composed of sulfuric acid, vanadium ions, sulfonated quaternary ammonium salt and water, wherein the concentration of sulfate ions in the diluted electrolyte is 4~5 mol / L, the concentration of vanadium ions is 1 mol / L, the valence state of vanadium ions is 3.5~4, and the concentration of sulfonated quaternary ammonium salt is 10~50 mg / L. The concentration of vanadium ions in the pure high-valence electrolyte is 1.5~1.7 mol / L.

6. The recycling and regeneration method as described in claim 1, characterized in that, In step S4: The method for removing impurities and concentrating the liquid involves adding barium chloride solution to the tailings and centrifuging the solution; wherein, The centrifugation process is carried out at a speed of 10,000 to 15,000 rpm for a time of 5 to 10 minutes. The concentration of the barium chloride solution is 1 mol / L; The volume ratio of the barium chloride solution to the tail liquid is (1~1.7):1; The vanadium ion concentration in the tail liquid after impurity removal and concentration is 2~2.5 mol / L.

7. The recycling and regeneration method as described in claim 1, characterized in that, In step S5: The valence state adjustment is achieved by charging the valence-balanced electrode stack by introducing the pure high-valence electrolyte; wherein... The number of cells in the valence-balanced stack is 3 to 10, and the diaphragm is a perfluorosulfonic acid resin membrane with a thickness of 60 to 120 μm. The vanadium ions in the regenerated vanadium electrolyte have a valence state of 3.

5.

8. The recycling and regeneration method as described in claim 1, characterized in that, The waste vanadium electrolyte is a sulfuric acid-based electrolyte.

9. A regenerated vanadium electrolyte, characterized in that, It is prepared by the recycling and regeneration method as described in any one of claims 1-8.

10. An application of a regenerated vanadium electrolyte, characterized in that, The regenerated vanadium electrolyte prepared by the recycling method according to any one of claims 1-8 or the regenerated vanadium electrolyte according to claim 9 is used in vanadium batteries; wherein, The coulombic efficiency of the regenerated vanadium electrolyte in the vanadium battery is not less than 99.0%; The energy efficiency of the recycled vanadium electrolyte in the vanadium battery is not less than 86.5%; After the vanadium battery has been operated for 200 cycles, the capacity retention rate of the regenerated vanadium electrolyte is not less than 97.9%.

Images