Vanadium slag valence state regulation-based short-process preparation method of vanadyl sulfate electrolyte and application thereof

Abstract

The application discloses a short-process preparation method of vanadyl sulfate electrolyte based on vanadium residue valence state regulation and application thereof, and belongs to the technical field of vanadium electrolyte. The vanadium residue is leached with sulfuric acid to obtain a leaching solution containing low-valence vanadium; amine organic extractant is used to extract vanadium and chromium in the leaching solution; then, sulfuric acid is used for back extraction; then, phosphoric acid extractant is used to extract and separate vanadium, and finally, sulfuric acid is used for back extraction, so that the vanadium electrolyte is obtained, and the obtained vanadium electrolyte can be used to build a VFB-5kW / 10kWh vanadium battery energy storage system. The application breaks through the established thinking of the traditional vanadium residue oxidation extraction of pentavalent vanadium as a vanadium source to prepare vanadium electrolyte, proposes a new process of directly preparing vanadium electrolyte from vanadium residue extraction of low-valence vanadium solution, constructs a short-process and green new process technology of preparing vanadium electrolyte from vanadium residue, and improves the efficiency of the vanadium electrolyte preparation process and reduces the preparation cost.

Description

Technical Field

[0001] This invention belongs to the technical field of vanadium electrolyte for all-vanadium redox flow batteries, specifically relating to a short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation and its application. Background Technology

[0002] Flow batteries, due to their ability to physically isolate charge from energy storage materials, offer longer cycle life and higher safety compared to lithium-ion batteries, making them a promising large-scale energy storage technology. Furthermore, their capacity does not decrease with increasing charge-discharge cycles, achieving tens of thousands of cycles. With their superior cycle life, high safety, and environmental friendliness, they have become a long-term energy storage technology approaching commercial application. However, the relatively high cost of preparing vanadium electrolytes results in a significant portion of the cost of vanadium battery systems. For a full vanadium redox flow battery system with a storage time of 10 hours, the electrolyte cost accounts for more than 70% of the total cost, directly hindering the large-scale commercial application of vanadium redox batteries. Therefore, reducing electrolyte costs is a pressing issue that needs to be addressed for the promotion and application of full vanadium redox flow batteries.

[0003] Currently, the most common vanadium electrolyte preparation technologies are chemical reduction and electrolysis, primarily using high-purity V₂O₅ as the vanadium source. This leads to the vanadium electrolyte price in vanadium redox flow batteries being significantly affected by fluctuations in the vanadium price (V₂O₅). Vanadium slag, as the main direct vanadium extraction raw material, plays a crucial role in reducing the cost of vanadium electrolytes through its extraction and purification processes. Vanadium slag has a complex and dense phase structure, with vanadium mainly existing as V(III) FeV₂O₄. Currently, industrial methods produce industrial-grade V₂O₅ as the final vanadium extraction product. Industrial-grade V₂O₅ requires further dissolution, impurity removal, precipitation, and calcination to obtain high-purity V₂O₅ (purity greater than 99.9%) as the main raw material for vanadium electrolyte preparation. Therefore, the existing vanadium slag oxidation vanadium extraction process is complex, has a long production flow, and the price of V₂O₅ itself, as a raw material for producing other vanadium products, is high. To reduce preparation costs, in recent years, some researchers have chosen vanadium leaching solution as a raw material for electrolyte preparation, aiming to avoid the preparation and dissolution process of high-purity V₂O₅ and simplify the current industrial process. First, some impurity ions are removed by pre-purification. Then, V(V) is reduced to low-valence vanadium ions by reduction method. Finally, the extraction-back-extraction method is used to achieve deep separation of vanadium and impurities. After removing the organic phase, a low-valence vanadium electrolyte is obtained. However, this method still uses the intermediate product of vanadium slag oxidation to extract vanadium, and it is inevitable that vanadium needs to be reduced again.

[0004] CN114361549A discloses a method for preparing vanadium electrolyte for an all-vanadium redox flow battery. This method involves reducing high-purity vanadium pentoxide under a reducing gas to obtain low-valence vanadium oxide. The low-valence vanadium oxide is then mixed with an activator and activated by heating to obtain a vanadium-containing paste electrolyte. Finally, the vanadium paste electrolyte is dissolved in water to obtain the vanadium electrolyte. This method still requires vanadium pentoxide as a reactant and necessitates its initial reduction to low-valence vanadium.

[0005] CN116995285A discloses a method for preparing vanadium electrolyte for an all-vanadium redox flow battery. Ammonium metavanadate and / or ammonium polyvanadate are reduced and calcined with a reducing gas to obtain vanadium oxide. A mixed sulfuric acid solution and vanadium oxide are then subjected to a dissolution reaction, and the vanadium content is adjusted to obtain the vanadium electrolyte. This method still requires vanadium pentoxide as a reactant and necessitates prior reduction to a lower valence vanadium.

[0006] CN114156516A discloses a method for producing vanadium electrolyte. The method involves high-temperature oxidative sodium roasting and acid leaching to obtain a sodium vanadate solution; adding acid to the alkaline solution to make it acidic, then removing impurities; further adding acid and reducing the solution to a tetravalent vanadium solution; and finally, extraction-back-extraction to obtain a vanadium oxysulfate solution. This method requires not only high-temperature oxidative roasting and impurity pretreatment of the leachate, but also the reduction of vanadium valence state, making the overall process lengthy.

[0007] In summary, current electrolyte preparation methods mostly require the reduction of pentavalent vanadium sources through chemical reduction and electrolysis, which presents the following problems: 1) The vanadium extraction process from vanadium slag requires oxidation treatment, causing V(V) and Cr(VI) contamination and increasing subsequent processing steps; 2) In the process of vanadium extraction from vanadium slag to vanadium electrolyte preparation, the vanadium valence state exhibits a circuitous route of V(III)−V(V)−V(III) / V(IV); 3) Limited by current vanadium extraction and purification processes, the production process of V2O5 raw materials used to produce vanadium electrolytes is lengthy and costly. Therefore, it is crucial to find an economical and green process for directly preparing high-value-added vanadium oxysulfate electrolytes from vanadium slag or other vanadium-containing raw materials. This patent develops a high-concentration all-vanadium electrolyte technology for all-vanadium flow batteries based on the vanadium slag valence state regulation of V(III)−V(III) / V(IV)−V(III) / V(IV). Figure 1 This simplifies the preparation process, reduces costs, improves the environmental friendliness of the preparation process, and enables the efficient application of vanadium redox flow batteries in the field of energy storage. Summary of the Invention

[0008] In view of the above-mentioned prior art, the present invention provides a short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation and its application, so as to solve the technical problems of difficult preparation and high preparation cost of vanadium electrolyte.

[0009] To achieve the above objectives, the technical solution adopted by this invention is to provide a short-process preparation method for vanadium oxysulfate electrolyte based on vanadium slag valence state regulation, comprising the following steps:

[0010] S1: Selective oxidation roasting and acid leaching, low-temperature sulfation roasting and water leaching, or self-pressurized acid leaching are performed on vanadium slag to obtain VO2-containing vanadium slag. 2+ Cr 3+ Fe 2+ Mn 2+ Acidic leachate;

[0011] S2: Adjust the pH of the acidic leachate to 0.5~2.5, and then add vanadium-chromium extractant to the acidic leachate to co-extract vanadium and chromium to obtain a supported organic phase containing vanadium and chromium; the vanadium-chromium extractant is obtained by mixing amine organic extractant, 2-octanol and sulfonated kerosene.

[0012] S3: The supported organic phase is back-extracted using sulfuric acid solution to obtain a back-extraction solution containing vanadium and chromium;

[0013] S4: Adjust the pH of the back-extraction solution to 1.5~2.7, and then add a phosphoric acid extractant to the back-extraction solution to extract vanadium, thereby obtaining a vanadium-containing supported organic phase;

[0014] S5: Use sulfuric acid solution to back-extract the vanadium-containing supported organic phase to obtain a vanadium-rich sulfuric acid solution;

[0015] S6: Activated carbon is used to remove the organic phase from the vanadium-rich sulfuric acid solution to obtain vanadium oxysulfate electrolyte.

[0016] Based on the above technical solution, the present invention can be further improved as follows.

[0017] Furthermore, the preparation of acidic leachate from vanadium slag includes the following steps:

[0018] Vanadium slag and sulfuric acid solution were placed in a high-pressure reactor at a ratio of 1 g:10 mL. The mixture was stirred at 500 rpm for 60 min at 150 ℃ and 0.7 MPa. The mixture was then filtered, and the filtrate was collected to obtain the final product.

[0019] Furthermore, the amine organic extractant undergoes an acidification treatment, which includes the following steps:

[0020] An amine organic extractant was mixed with a 1 mol / L sulfuric acid solution at a volume ratio of 2:1, and then stirred at 25 °C for 1 h. The mixture was then separated, and the organic phase was collected to obtain the final product.

[0021] The amine organic extractants are trioctylamine (TOA), methyltrioctylammonium chloride (Aliquat 336), secondary carbon primary amine extractant (N1923) or trioctyldecyl tertiary amine (N235).

[0022] Furthermore, the vanadium-chromium extractant is obtained by mixing acidified amine organic extractant, 2-octanol and sulfonated kerosene in a volume ratio of 50:5:45; the volume concentration of amine organic extractant in the leachate after adding the vanadium-chromium extractant in S2 is 15%.

[0023] Furthermore, the extraction conditions in S2 are as follows: extraction temperature is 25 ℃, relative O / A is 1, extraction time is 10 min; extraction method is countercurrent extraction, and the number of extraction stages is two.

[0024] Furthermore, the concentration of the sulfuric acid solution used for back-extraction in S3 is 4 mol / L; the back-extraction conditions are: back-extraction temperature is 25℃, relative O / A is 2, back-extraction time is 10 min; the extraction method is countercurrent back-extraction, and the number of extraction stages is three.

[0025] The phosphate extractant is further di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) or di(2,4,4-trimethylpentyl)phosphonic acid (C272); the volume concentration of the phosphate extractant in the back-extraction solution after adding the phosphate extractant in S4 is 20%.

[0026] Furthermore, the extraction conditions in S4 were: extraction temperature of 25 ℃, relative O / A of 1, and extraction time of 30 min.

[0027] Furthermore, the concentration of the sulfuric acid solution used for back-extraction in S5 is 5 mol / L; the back-extraction conditions are: back-extraction temperature is 25℃, relative O / A is 6, and back-extraction time is 40 min.

[0028] This invention also discloses the application of a short-process preparation method for vanadium oxysulfate electrolyte based on vanadium slag valence state regulation in the preparation of vanadium oxysulfate electrolyte for all-vanadium redox flow batteries.

[0029] The beneficial effects of this invention are:

[0030] 1. This invention uses a non-high-temperature oxidation method to treat vanadium slag, which not only increases the leaching rate of metal ions such as vanadium and chromium in the vanadium slag, but also allows vanadium and chromium to leach out in a low valence state, eliminating the need for subsequent reduction operations. The vanadium oxysulfate electrolyte can be obtained through extraction and back-extraction, which simplifies the preparation process and reduces the preparation cost of the vanadium electrolyte.

[0031] 2. This invention uses an acidified organic extractant to extract V and Cr from the leachate, achieving separation from Fe and Mn. This process has advantages such as good selectivity, simple process, and easy regeneration of the extractant. Furthermore, the organic phase after sulfuric acid back-extraction does not need to be acidified again and can be directly used in the extraction cycle. After five cycles, the extraction capacity remains above 95%.

[0032] 3. The vanadium electrolyte prepared by the method of this invention has an oxidation peak current density Ia and a reduction peak current density Ic of 0.0735 A / cm². 2 and 0.0436 A / cm 2 Its oxidation peak potential is 1.15 V and its reduction peak potential is 0.769 V, which shows excellent electrochemical performance.

[0033] 4. In the traditional process of preparing vanadium electrolyte from vanadium slag, the vanadium slag undergoes oxidation roasting-leaching-ammonium salt precipitation-roasting to obtain V₂O₅, which is then dissolved and reduced to produce vanadium oxysulfate electrolyte. However, V₂O₅ has very low solubility, and the vanadium slag roasting process is energy-intensive, the vanadium precipitation process produces toxic tailings, and the reduction process significantly increases production costs. The vanadium oxysulfate electrolyte directly prepared from the vanadium slag leaching solution through extraction separation proposed in this invention has low energy consumption, minimal hazards, and a short process flow. Furthermore, it facilitates the comprehensive utilization of metallic elements such as Cr, Fe, and Mn in the vanadium slag, providing a reference for the green utilization of vanadium slag. Attached Figure Description

[0034] Figure 1 This is a comparison between the vanadium electrolyte preparation process disclosed in this patent and existing processes;

[0035] Figure 2 The graph shows the effect of acidified organic extractant on the extraction process of leachate at different pH values.

[0036] Figure 3 This is a graph showing the effect of sulfuric acid concentration on the reverse extraction process of supported organic materials.

[0037] Figure 4 The extraction isotherm for V;

[0038] Figure 5 This is a diagram of a two-stage countercurrent extraction cascade experiment.

[0039] Figure 6 The graph shows the results of the cyclic performance evaluation of the extractant.

[0040] Figure 7 The graph shows the effect of the initial pH of the back-extraction solution on the vanadium extraction process.

[0041] Figure 8 The CV curve is shown for the vanadium electrolyte.

[0042] Figure 9 This is a photograph of a vanadium redox flow battery charging station using the prepared electrolyte. Detailed Implementation

[0043] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0044] Example 1: Preparation of low-valent vanadium solution from vanadium slag

[0045] Vanadium slag with a particle size of less than 74 μm (vanadium content of 9.6%) and a 2 mol / L sulfuric acid solution were placed in a zirconium-based autoclave at a feed-to-liquid ratio of 1 g: 10 mL. The autoclave was then sealed, and a leaching reaction was initiated under heat and pressure at a temperature of 150 °C, a leaching pressure of 0.7 MPa, a stirring speed of 500 rpm, and a leaching time of 60 min. After leaching, the mixture was cooled, and the slurry was filtered to obtain the leachate and leaching residue. It is worth noting that traditional vanadium slag pressure leaching involves the introduction of an oxidizing gas for pressurized oxidative leaching; however, to prepare a low-valent vanadium leachate, this invention does not require additional gas to supplement the pressure. The pressure during the reaction process is the self-pressure of the aqueous solution system under high-temperature leaching, which is a self-pressurized acid leaching process. Furthermore, the low-valent vanadium leachate can also be prepared by low-temperature sulfation roasting and water leaching.

[0046] The main elemental contents of the prepared leachate were analyzed by ICP-OES, and the results are shown in Table 1. Further analysis of the leachate revealed no pentavalent vanadium, indicating that the obtained leachate was a low-valent vanadium solution.

[0047] Table 1 Content of major elements in leachate

[0048]

[0049] Example 2: Vanadium-chromium co-extraction-back-extraction in low-valent vanadium solution

[0050] Take the above leachate and add it to a conical flask. Adjust the pH value to a certain value with 2 mol / L H2SO4 and 2 mol / L NaOH to obtain the aqueous phase. Then add the vanadium-chromium extractant and stir the solution in the conical flask thoroughly under constant temperature water bath conditions. After the reaction is complete, transfer it to a separatory funnel and allow it to stand for separation. Take out the aqueous phase and the loaded organic phase separately and measure their volumes. The loaded organic phase is back-extracted using a back-extraction agent, and the operation is similar to the above extraction process. Finally, analyze the obtained aqueous phase and organic phase. The vanadium-chromium extractant used is an extractant that has a good extraction effect on vanadium and chromium but a poor extraction effect on other metal ions. In this invention, amine organic extractants are preferred, such as trioctylamine (TOA), methyltrioctylammonium chloride (Aliquat 336), secondary carbon primary amine extractant (N1923), trioctyldecyl tertiary amine (N235), etc. In order to improve the extraction effect, the amine organic extractant can be acidified first. The acidification treatment includes the following steps:

[0051] Add 10 mL of amine organic extractant to a stoppered conical flask, then add 1 mol / L sulfuric acid to the flask at a volume ratio of organic phase to aqueous phase of 2:1. After standing and releasing heat, stir in a constant temperature water bath at 25 ℃ for 1 h, then separate the liquids and collect the upper organic phase, which is the acidified amine organic extractant.

[0052] The leachate was extracted using the above-described extraction process. The vanadium-chromium extractant consisted of 50 vol.% acidified N1923 + 5 vol.% sec-octanol + 45 vol.% sulfonated kerosene. The extraction conditions were as follows: the concentration of the acidified organic extractant in the leachate after adding the extractant was 10 vol.%, the extraction temperature (T) was 25 ℃, the phase ratio (O / A) was 1, and the extraction time (t) was 10 min. The effect of different initial pH values ​​of the aqueous phase on the extraction process is as follows. Figure 2 As shown in the figure, when the pH value is 1.7, the extraction rates of V and Cr are 82.5% and 84.6%, respectively. Therefore, an initial pH value of 1.7 for the aqueous phase is selected as the optimal initial pH value. After two stages of countercurrent extraction, the extraction rates of V and Cr are both above 98%, which means that V and Cr in the leachate can be basically completely extracted. Then, sulfuric acid is added to the above organic phase for back-extraction to obtain a solution containing V (VO). 2+ ), Cr (Cr 3+ The back-extraction solution was prepared using the following conditions: back-extraction temperature (T) of 25 ℃, phase ratio (O / A) of 2, and back-extraction time (t) of 10 min. The effects of different sulfuric acid concentrations on the V and Cr back-extraction process are shown below. Figure 3As shown in the figure, the back-extraction rates of both V and Cr increase with increasing sulfuric acid concentration. When the sulfuric acid concentration is 0.5 mol / L, the back-extraction rates of V and Cr are 13.4% and 18.2%, respectively; when the sulfuric acid concentration increases to 4 mol / L, the back-extraction rates of V and Cr increase to 63.5% and 67.8%, respectively; further increasing the concentration increases the back-extraction rate, but the acid concentration of the back-extraction agent should not be too high, because higher acidity is not conducive to the extraction of V in the subsequent P2O4 separation of V and Cr; at the same time, a higher concentration of back-extraction acid makes the organic phase more susceptible to damage.

[0053] The MT graphical method was used to determine the extraction stages to improve the separation efficiency of the target metal. Under conditions of an initial aqueous phase pH of 1.7, an acidified N1923 concentration of 15 vol.%, a temperature of 25 °C, and a extraction time of 10 min, extraction isotherms for V were obtained by varying the O / A ratios to 1:3, 1:2, 1:1, 2:1, and 3:1. The results are shown below. Figure 4 As shown in the figure, with the operating line O / A being 1, theoretically, after two stages of countercurrent extraction, the extraction rate of V can reach over 99%. Figure 5 The results after six extraction cycles are shown in the figure. The final solution closely resembles the actual two-stage countercurrent raffinate. Each box in the figure represents one extraction process of V and Cr using the acidified extractant. The letters V and L represent fresh leachate and fresh extractant, respectively. Each extraction experiment was conducted under conditions of O / A = 1, temperature of 25 °C, and time of 10 min. The outlet L3 value was the steady-state value after the cycle experiment. The data for V, Cr, Fe, and Mn in each stage of the reaction are listed in Table 2. In the simulated two-stage countercurrent extraction, the extraction rates of V and Cr were both above 98%, while the extraction rates of Fe and Mn remained below 1%. Therefore, after two-stage countercurrent extraction, V and Cr can be almost completely extracted from the leachate, achieving separation from Fe and Mn.

[0054] Table 2 Results of simulated two-stage countercurrent extraction experiments

[0055]

[0056] The process of back-extraction using sulfuric acid is also an acidification process. Using the back-extracted organic phase, five cycles were performed under the aforementioned preferred conditions, with the following results: Figure 6 As shown in the figure, after five cycles, the extractant maintained excellent extraction efficiency and did not require re-acidification. After one cycle, the extraction rates of V and Cr were 87.4% and 88.2%, respectively; after five cycles, the extraction rates of V and Cr remained at 84.2% and 85.1%, respectively. The extractant's extraction capacity for V and Cr remained above 95% after cycling, demonstrating good cycling performance.

[0057] Example 3: Separation of V and Cr in the back-extraction solution

[0058] The leachate was extracted using the extraction process described in Example 2 and the following optimal extraction conditions to obtain a solution containing V (VO). 2+ ) and Cr (Cr 3+ The supported organic phase was then back-extracted using the back-extraction process described in Example 2 and the following optimal back-extraction conditions to obtain a product containing V (VO). 2+ ) and Cr (Cr 3+ The ion concentrations of the main elements in the back-extraction solution are shown in Table 3.

[0059] Table 3. Main elements and their contents in the back-extraction solution

[0060]

[0061] Take the above-mentioned back-extraction solution and add it to a conical flask. Adjust the pH value to a certain value with 2 mol / L H2SO4 and 2 mol / L NaOH to prepare the aqueous phase. Then add a phosphoric acid extractant (di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) or bis(2,4,4-trimethylpentyl)phosphonic acid (C272, preferably P204 in this invention). Stir the solution in the conical flask thoroughly under constant temperature water bath conditions. After the reaction is complete, transfer it to a separatory funnel and allow it to stand for separation. Take out the aqueous phase and the vanadium-loaded organic phase separately and measure their volumes. The vanadium-loaded organic phase is back-extracted using a back-extraction agent, and the operation is similar to the above extraction process. Finally, analyze the obtained aqueous and organic phases. The extraction conditions are: the concentration of the phosphoric acid extractant is 20 vol.%, the extraction temperature (T) is 25 ℃, the phase ratio (O / A) is 1, and the extraction time (t) is 30 min. The effect of different initial pH values ​​of the back-extraction solution on the extraction process, such as Figure 7 As shown in the figure, the extraction rates of V and Cr gradually increase with increasing pH. P₂O₄ does not extract Cr at pH values ​​below 2.1, and does not extract Fe across the entire pH range. Therefore, an initial pH of 2.1 for the back-extraction solution is selected as the optimal pH value, at which the extraction rate of V is 98.8%, yielding vanadium-loaded (VO₂O₄). 2 The organic phase of ).

[0062] Sulfuric acid is commonly used as a back-extraction agent in acidic extraction. Therefore, sulfuric acid is used for back-extraction of substances rich in low-valent V (VO). 2+ The organic phase (supported vanadium (VO)) 2 The organic phase of vanadium redox flow battery can be used to directly prepare vanadium oxysulfate electrolyte. According to the national standard for vanadium redox flow batteries (GB / T37204-2018), the concentration of vanadium redox flow battery (V) in the electrolyte must be greater than or equal to 76.41 g / L, and SO42- should be less than 76.41 g / L. 2-For a concentration greater than or equal to 2.3 mol / L, 5 mol / L H2SO4 was selected as the stripping agent to meet the requirements. Under the condition of 25 ℃, the optimal process parameters of phase ratio and time were explored. When the stripping time reached 40 min, V could be almost completely stripped. At the same time, increasing the phase ratio could achieve the effect of enriching V. At 40 min, even when the phase ratio O / A increased to 6, more than 99% of V could still be stripped. At this time, the V concentration in the solution reached 78.42 g / L, which met the above national standard. Therefore, the preferred stripping time is 40 min and the preferred phase ratio O / A is 6.

[0063] Example 4: Characterization of Vanadium Electrolyte

[0064] Vanadium electrolyte was prepared using the extraction and back-extraction processes and optimal extraction and back-extraction conditions described in Example 3. ICP-OES was used to perform elemental analysis to test the concentration of each ion in the vanadium electrolyte. The results are shown in Table 4. A comparison with the Grade I standard in the national standard for vanadium redox flow batteries (GB / T 37204-2018) shows that the V concentration and the content of other impurity elements all meet the requirements.

[0065] Table 4. Impurity ion content of vanadium electrolyte prepared by extraction method and national standard grade 1 product

[0066]

[0067] To better evaluate the electrochemical performance of the prepared vanadium electrolyte, the vanadium electrolyte obtained by extraction was used as the experimental group, and a vanadium electrolyte prepared with 99.80% pure vanadium oxysulfate and 5 mol / L sulfuric acid solution was used as the control group. The concentration of V in the control group was 78.42 g / L, the same as the experimental group. Cyclic voltammetry tests were performed on both the experimental and control groups, and the cyclic voltammetry curves are shown below. Figure 8 As shown, the main data are listed in Table 5. The oxidation peak current density Ia and reduction peak current density Ic of the experimental group are 0.0735 A / cm². 2 and 0.0436 A / cm 2 Its oxidation peak potential and reduction peak potential are 1.15 V and 0.769 V, respectively, which are roughly the same as the cyclic voltammetry curve of the prepared vanadium electrolyte, showing properties similar to those of the electrolyte in the control group.

[0068] Table 5 Figure 8 Characteristic peak data in

[0069]

[0070] Example 5: Application of Vanadium Oxide Sulfate Electrolyte

[0071] Relying on the energy comprehensive utilization demonstration platform of Sichuan University, the prepared VOSO4 electrolyte was used in vanadium redox flow battery charging piles to build a VFB-5kW / 10kWh vanadium battery energy storage system, such as... Figure 9 As shown. After a period of demonstration operation, the vanadium redox flow battery system demonstrated good stability and high efficiency, and can meet the charging needs of electric vehicles.

[0072] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A short-process preparation method for vanadium oxysulfate electrolyte based on vanadium slag valence state regulation, characterized in that, Includes the following steps: S1: Vanadium slag is subjected to self-pressure acid leaching to obtain VO-containing... 2+ Cr 3+ Fe 2+ Mn 2+ The acidic leachate, wherein the acidic leachate does not contain pentavalent vanadium; the preparation of the acidic leachate by self-pressure acid leaching of vanadium slag includes the following steps: Vanadium slag and sulfuric acid solution were placed in a high-pressure reactor at a ratio of 1 g: 10 mL. The mixture was stirred at 500 rpm for 60 min at 150 ℃ and 0.7 MPa. The mixture was then filtered, and the filtrate was collected to obtain the final product. S2: Adjust the pH of the acidic leachate to 1.5-1.7, then add a vanadium-chromium extractant to the acidic leachate for co-extraction of vanadium and chromium, obtaining a supported organic phase containing vanadium and chromium; the vanadium-chromium extractant is obtained by mixing an acidified amine organic extractant, 2-octanol, and sulfonated kerosene in a volume ratio of 50:5:45; the acidification treatment of the amine organic extractant includes the following steps: An amine organic extractant was mixed with a 1 mol / L sulfuric acid solution at a volume ratio of 2:1, and then stirred at 25 °C for 1 h. The mixture was then separated, and the organic phase was collected to obtain the final product. The amine organic extractant is trioctylamine, methyltrioctylammonium chloride, secondary carbon primary amine extractant, or trioctyldecyl tertiary amine; S3: The supported organic phase is back-extracted using sulfuric acid solution to obtain a back-extraction solution containing vanadium and chromium; S4: Adjust the pH of the back-extraction solution to 1.5~2.7, and then add a phosphoric acid extractant to the back-extraction solution to extract vanadium, thereby obtaining a vanadium-containing supported organic phase; S5: Use sulfuric acid solution to back-extract the vanadium-containing supported organic phase to obtain a vanadium-rich sulfuric acid solution; S6: Activated carbon is used to remove the organic phase from the vanadium-rich sulfuric acid solution to obtain vanadium oxysulfate electrolyte.

2. The short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that, The volume concentration of amine organic extractant in the leachate after adding vanadium-chromium extractant to S2 is 15%.

3. The short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that, The extraction conditions in S2 are as follows: extraction temperature is 25 ℃, relative O / A is 1, extraction time is 10 min; extraction method is countercurrent extraction, and the number of extraction stages is two.

4. The short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that, The concentration of the sulfuric acid solution used for back-extraction in S3 is 4 mol / L; the back-extraction conditions are: back-extraction temperature is 25 ℃, relative O / A is 2, back-extraction time is 10 min; the extraction method is countercurrent back-extraction, and the number of extraction stages is three.

5. The short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that, The phosphoric acid extractant is di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester, or di(2,4,4-trimethylpentyl)phosphonic acid; the volume concentration of the phosphoric acid extractant in the back-extraction solution after adding the phosphoric acid extractant in S4 is 20%.

6. The short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that, The extraction conditions in S4 were: extraction temperature of 25 ℃, relative O / A of 1, and extraction time of 30 min.

7. The short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that, The concentration of the sulfuric acid solution used for back-extraction in S5 is 5 mol / L; the back-extraction conditions are: back-extraction temperature is 25 ℃, relative O / A is 6, and back-extraction time is 40 min.

8. The application of the short-process preparation method of vanadium oxysulfate electrolyte based on vanadium slag valence state regulation as described in any one of claims 1 to 7 in the preparation of vanadium oxysulfate electrolyte for all vanadium redox flow batteries.

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