All-ionic liquid extraction system and method for preparing vanadium electrolyte based on all-ionic liquid extraction system in short process

Abstract

The invention discloses an all-ionic liquid extraction system and a short-process vanadium electrolyte preparation method based on the all-ionic liquid extraction system, and belongs to the technical field of vanadium product preparation. According to the specific scheme, the method comprises the following steps: (1) adding sulfuric acid and a leaching aid into the vanadium-containing material, reacting for 4-12 hours, and filtering to obtain vanadium-containing mother liquor; (2) adding the vanadium-containing mother liquor into a full-ionic liquid extraction system to obtain vanadium extraction ionic liquid; (3) sulfuric acid is added into the vanadium extraction ionic liquid for back extraction, and vanadium-containing acid liquid is obtained; and (4) adding sulfuric acid into the vanadium-containing acid solution again or directly evaporating and concentrating to obtain the vanadium electrolyte. According to the method, the defects that a conventional extracting agent and a conventional solvent are prone to volatilization and pollute the environment are overcome, the recovery rate of vanadium is increased, the impurity content of the prepared vanadium electrolyte is low, and the method is green and sustainable.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium product preparation, and in particular to a full ionic liquid extraction system and a method for preparing a vanadium electrolyte in a short process based on the full ionic liquid extraction system. Background Art

[0002] With the continuous development of industrial economy, the importance of renewable energy in modern society has become increasingly prominent, and solar and wind power generation has been widely used. Due to the instability of the electricity generated by solar and wind power generation, this electricity cannot be directly connected to the power grid. Redox flow batteries have the characteristics of energy storage and energy conversion that can be realized in different locations, and are a promising energy storage system.

[0003] Vanadium battery is a type of redox flow battery. Vanadium electrolyte is one of the key materials of vanadium battery. The concentration and electrochemical activity of vanadium ions in vanadium electrolyte determine the energy density of vanadium battery and play a vital role in the development of vanadium battery. The active substance in vanadium electrolyte is vanadium oxyacyl ion, which is the key material in all-vanadium flow battery. High vanadium oxyacyl ion concentration and purity in electrolyte are the material basis of high comprehensive electrical performance of vanadium battery. Usually, vanadium electrolyte is made of ammonium metavanadate or ammonium polyvanadate as raw material, and high-purity vanadium pentoxide is obtained after calcination. Subsequently, vanadium sulfate electrolyte is prepared by chemical reduction-electrochemical reduction. There are many processes, complex process, high cost and other problems.

[0004] Therefore, it is necessary to develop a new, simpler and more convenient short-process vanadium electrolyte production process to reduce production costs while ensuring the purity of the vanadyl sulfate product and achieve efficient, green and clean production of vanadium electrolyte. Summary of the invention

[0005] In view of the shortcomings of the currently widely used vanadium electrolyte preparation methods, the purpose of the present invention is to provide a full ionic liquid extraction system and a method for preparing vanadium electrolyte in a short process based on the full ionic liquid extraction system. The method for preparing vanadium electrolyte in a short process based on the full ionic liquid provided by the present invention is green and environmentally friendly, has lower cost, higher efficiency, and has good application prospects compared with traditional methods.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an all-ionic liquid extraction system, including an extractant and a diluent; the extractant is [TOMA][EHEHP], [TOMA][DEHP], [P 4444 ][EHEHP] or [P 4444 ][DEHP] or a mixture of any two of them in any proportion; the diluent is [C n mim][NTf2], [C n mim][PF6] or [C nmim][SbF6] or a mixture of any two of them in any proportion, wherein n=2-8.

[0007] Furthermore, in the above-mentioned all-ionic liquid extraction system, the volume ratio of extractant:diluent is 1:3-5.

[0008] Furthermore, in the above-mentioned all-ionic liquid extraction system, the method for preparing the extractant comprises the following steps:

[0009] (1) Dissolve sodium hydroxide and methyl trioctyl ammonium chloride or tetrabutylphosphonium bromide in isopropanol, mix well, stir at 30-40° C. for 24-26 hours, filter, and obtain [TOMA][OH] intermediate or [P 4444 ][OH] intermediate;

[0010] (2) Dissolve 2-ethylhexyl phosphate mono-2-ethylhexyl ester or di-2-ethylhexyl phosphate in isopropanol, and add [TOMA][OH] intermediate or [P 4444 The intermediate [TOMA] [EHEHP], [TOMA] [DEHP], [P 4444 ][EHEHP] or [P 4444 ][DEHP].

[0011] A method for preparing a vanadium electrolyte in a short process based on a full ionic liquid extraction system, using the above-mentioned full ionic liquid extraction system, the method comprises the following steps:

[0012] (1) adding sulfuric acid and a leaching aid to a vanadium-containing material, reacting for 4 to 12 hours, filtering, and obtaining a vanadium-containing mother liquor;

[0013] (2) adding the vanadium-containing mother liquor into a full ionic liquid extraction system to obtain a vanadium extraction ionic liquid;

[0014] (3) adding sulfuric acid to the vanadium extraction ionic liquid for stripping to obtain a vanadium-containing acid solution;

[0015] (4) Add sulfuric acid again to the vanadium-containing acid solution or directly evaporate and concentrate it to obtain a vanadium electrolyte.

[0016] Furthermore, in the above method, in step (1), the leaching aid is one of ammonium sulfate, calcium fluoride or sodium tripolyphosphate, or a mixture of any two in any proportion.

[0017] Furthermore, in the above method, in step (1), the amount of the leaching aid is 1 to 5% of the mass of the vanadium-containing material.

[0018] Furthermore, in the above method, in step (1), the concentration of the sulfuric acid is 10 to 25% by mass percentage.

[0019] Furthermore, in the above method, in step (2), the volume ratio of vanadium-containing mother liquor: full ionic liquid extraction system is 1:0.2-2.

[0020] Furthermore, in the above method, in step (3), the volume ratio of vanadium extraction ionic liquid: sulfuric acid is 1 to 5:1; the stripping is performed at 20 to 80° C. for 10 to 60 min; and the concentration of the sulfuric acid is 5 to 25% by mass percentage.

[0021] Furthermore, in the above method, in step (4), sulfuric acid is added again to adjust the vanadium concentration in the obtained vanadium electrolyte to 1.5-2.0 mol / L; in terms of mass percentage, the concentration of the sulfuric acid is 5-25%.

[0022] The beneficial effects of the present invention are:

[0023] 1. The method for preparing vanadium electrolyte in a short process based on a full ionic liquid extraction system provided by the present invention adopts a full ionic liquid extraction system, thereby avoiding the long process of obtaining high-purity vanadium pentoxide by calcining ammonium metavanadate or ammonium polyvanadate, and then preparing vanadyl sulfate electrolyte by chemical reduction-electrochemical reduction.

[0024] 2. The method provided by the present invention has a simple preparation method, a short process, reduced production costs, convenient recycling, recyclable use, little environmental pollution, and realizes the optimization of the production process of vanadyl sulfate electrolyte, which can generate huge economic and social benefits.

[0025] 3. The method provided by the present invention overcomes the drawbacks of conventional extractants and solvents that are volatile and pollute the environment, improves the recovery rate of vanadium, and the prepared vanadium electrolyte has a low impurity content, which is a green and sustainable method. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the NMR spectrum of [TOMA][EHEHP].

[0027] Figure 2 This is the NMR spectrum of [TOMA][DEHP].

[0028] Figure 3 For [P 4444 ][EHEHP]'s NMR spectrum.

[0029] Figure 4 For [P 4444 ][NMR spectrum of DEHP]. DETAILED DESCRIPTION

[0030] In order to better understand the above-mentioned technical scheme, the technical scheme of the embodiments of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the embodiments of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other.

[0031] In a first aspect of an embodiment of the present invention, a full ionic liquid extraction system is provided, comprising an extractant and a diluent; the extractant is [TOMA][EHEHP], [TOMA][DEHP], [P 4444 ][EHEHP] or [P 4444 ][DEHP] or a mixture of any two of them in any proportion; the diluent is [C n mim][NTf2], [C n mim][PF6] or [C n mim][SbF6] or a mixture of any two of them in any proportion, wherein n=2-8.

[0032] The all-ionic liquid extraction system provided by the present invention can extract vanadium from the vanadium-containing mother liquor into the ionic liquid. The extractant and diluent used in the all-ionic liquid extraction system are both ionic liquids, which are environmentally friendly compared to organic or inorganic solvents, and the all-ionic liquid extraction system can be recovered by back extraction, which is convenient to recycle and can be reused.

[0033] In some feasible embodiments, further, in the all-ionic liquid extraction system, the volume ratio of extractant: diluent is 1:3-5.

[0034] The concentration of the extractant has a significant effect on the extraction rate. When the extractant: diluent = 1:4, the extraction rate is high. Increasing the amount of the extractant does not significantly improve the extraction rate. Considering the economic cost, the present invention further prefers that the extractant: diluent = 1:4.

[0035] In some feasible embodiments, further, in the all-ionic liquid extraction system, the method for preparing the extractant comprises the following steps:

[0036] (1) Dissolve 4 parts of sodium hydroxide and 30-40 parts of methyl trioctyl ammonium chloride or tetrabutyl phosphine bromide in 200 parts of isopropanol, mix well, stir at 30-40° C. for 24-26 hours, filter, and obtain [TOMA][OH] intermediate or [P 4444 ][OH] intermediate;

[0037] (2) Dissolve 30 to 40 parts of 2-ethylhexyl phosphate mono-2-ethylhexyl ester or di-2-ethylhexyl phosphate in 200 parts of isopropanol, and add [TOMA][OH] intermediate or [P 4444 The intermediate [TOMA] [EHEHP], [TOMA] [DEHP], [P 4444 ][EHEHP] or [P 4444 ][DEHP].

[0038] A second aspect of the present invention provides a method for preparing a vanadium electrolyte in a short process based on a full ionic liquid extraction system, using the above-mentioned full ionic liquid extraction system, and the method comprises the following steps:

[0039] (1) adding sulfuric acid and a leaching aid to a vanadium-containing material, reacting for 4 to 12 hours, filtering, and obtaining a vanadium-containing mother liquor;

[0040] (2) adding the vanadium-containing mother liquor into a full ionic liquid extraction system to obtain a vanadium extraction ionic liquid;

[0041] (3) adding sulfuric acid to the vanadium extraction ionic liquid for stripping to obtain a vanadium-containing acid solution;

[0042] (4) Add sulfuric acid to the vanadium-containing acid solution again or directly evaporate and concentrate to obtain a vanadium electrolyte.

[0043] The present invention provides a method for preparing a vanadium electrolyte based on a full ionic liquid extraction system in a short process. The method extracts vanadium from a vanadium-containing material by sulfuric acid and a leaching aid to obtain a vanadium-containing mother liquor, thereby avoiding the step of calcining to obtain high-purity vanadium pentoxide. The method is simple and energy-saving. The vanadium in the vanadium-containing mother liquor is extracted by the full ionic liquid extraction system, and the vanadium is extracted into sulfuric acid through sulfuric acid back extraction to obtain a vanadium-containing acid liquid. The vanadium-containing acid liquid can be obtained through only a simple extraction step. The method is simple, and after back extraction, the full ionic liquid extraction system can be recovered and reused, which greatly reduces the production cost and does not pollute the environment.

[0044] In some feasible implementations, the vanadium-containing material can be commercially available crude ammonium metavanadate or ammonium polyvanadate (with a purity of less than 80%), or any mineral containing vanadium. If any mineral containing vanadium is used, the material is first crushed into particles with a particle size of less than 2 mm.

[0045] In some feasible embodiments, further, in the above method, in step (1), the leaching aid is one of ammonium sulfate, calcium fluoride or sodium tripolyphosphate, or a mixture of any two in any proportion.

[0046] The present invention adopts ammonium sulfate, calcium fluoride or sodium tripolyphosphate and sulfuric acid to cooperate with each other to quickly leach vanadium.

[0047] In some feasible implementations, further, in the above method, in step (1), the amount of the leaching aid is 1 to 5% of the mass of the vanadium-containing material.

[0048] In some feasible implementations, further, in the above method, in step (1), the concentration of sulfuric acid is 10-25% by mass percentage.

[0049] When the concentration of sulfuric acid is 10-25%, the leaching rate is high. When the concentration of sulfuric acid is further increased, the leaching rate is not significantly improved. Considering economic cost and safety issues, the preferred concentration of sulfuric acid in the present invention is 10-25%.

[0050] In some feasible embodiments, further, in the above method, in step (2), the volume ratio of vanadium-containing mother liquor: full ionic liquid extraction system is 1:0.2-2.

[0051] In some feasible embodiments, further, in the above method, in step (3), the volume ratio of vanadium extraction ionic liquid: sulfuric acid is 1 to 5:1; the back extraction is performed at 20 to 80° C. for 10 to 60 min; and the concentration of the sulfuric acid is 5 to 25% by mass percentage.

[0052] When the concentration of sulfuric acid is 5-25%, the stripping rate is high. When the concentration of sulfuric acid is further increased, the stripping rate is not significantly improved. Considering the economic cost and safety issues, the preferred concentration of sulfuric acid in the present invention is 5-25%.

[0053] In some feasible embodiments, further, in the above method, in step (4), sulfuric acid is added again to adjust the vanadium concentration in the obtained vanadium electrolyte to 1.5-3.0 mol / L; in terms of mass percentage, the concentration of the sulfuric acid is 5-25%.

[0054] By using the method of the present invention, a vanadium electrolyte having a vanadium concentration greater than 1.7 mol / L can be obtained.

[0055] Example 1

[0056] (I) Preparation of ionic liquid [TOMA] [EHEHP]

[0057] 20 g of sodium hydroxide and 200 g of methyltrioctyl ammonium chloride were dissolved in 1000 g of isopropanol, mixed evenly, stirred at 35° C. for 24 h, and the generated NaCl was filtered out using a sand core filter to obtain the [TOMA][OH] intermediate.

[0058] 150 g of 2-ethylhexyl phosphate mono-2-ethylhexyl ester was dissolved in 1000 g of isopropanol, and the intermediate [TOMA][OH] was added thereto. The mixture was stirred at 35°C for 24 h, and the isopropanol was removed by rotary evaporation to obtain a viscous ionic liquid [TOMA][EHEHP], and the NMR spectrum was as follows: Figure 1 .

[0059] (II) Preparation of all-ionic liquid extraction system

[0060] According to the volume ratio, [TOMA][EHEHP]:[C4mim][NTf2]=2:8. Take [TOMA][EHEHP] and [C4mim][NTf2], mix them evenly, and obtain a full ionic liquid extraction system ([TOMA][EHEHP]-[C4mim][NTf2]).

[0061] (III) Preparation of vanadium electrolyte

[0062] (1) 100 g of ammonium metavanadate was added with 200 mL of 15 wt% sulfuric acid and 2 g of ammonium sulfate as a leaching aid, and the mixture was reacted at room temperature for 6 h, and then filtered to obtain a vanadium-containing mother liquor;

[0063] (2) adding 180 mL of vanadium-containing mother liquor into 100 mL of [TOMA][EHEHP]-[C4mim][NTf2], extracting at 25° C. for 30 min to extract vanadium into the ionic liquid to obtain a vanadium-extracted ionic liquid;

[0064] (3) adding 15 wt % sulfuric acid to the vanadium extraction ionic liquid in a volume ratio of vanadium extraction ionic liquid to sulfuric acid = 3:1, and back-extracting at 30° C. for 30 min to obtain a vanadium-containing acid solution;

[0065] (4) 190 mL of 15 wt % sulfuric acid was added to the vanadium-containing acid solution again to obtain a vanadium electrolyte, wherein the vanadium concentration in the obtained vanadium electrolyte was 1.73 mol / L.

[0066] Example 2

[0067] (I) Preparation of ionic liquid [TOMA] [DEHP]

[0068] 20 g of sodium hydroxide and 200 g of methyltrioctyl ammonium chloride were dissolved in 1000 g of isopropanol, mixed evenly, stirred at 35° C. for 24 h, and the generated NaCl was filtered out using a sand core filter to obtain the [TOMA][OH] intermediate.

[0069] Dissolve 160 g of di(2-ethylhexyl) phosphate in 1000 g of isopropanol, add [TOMA][OH] intermediate, stir at 35°C for 24 h, and remove isopropanol by rotary evaporation to obtain viscous ionic liquid [TOMA][DEHP], with the following NMR spectrum: Figure 2 .

[0070] (II) Preparation of all-ionic liquid extraction system

[0071] According to the volume ratio, [TOMA][DEHP]:[C4mim][NTf2]=2:8. Take [TOMA][DEHP] and [C4mim][NTf2], mix them evenly, and obtain a full ionic liquid extraction system ([TOMA][DEHP]-[C4mim][NTf2]).

[0072] (III) Preparation of vanadium electrolyte

[0073] (1) 100 g of ammonium metavanadate was added with 200 mL of 18 wt% sulfuric acid and 2 g of ammonium sulfate as a leaching aid, and the mixture was reacted at room temperature for 6 h, and then filtered to obtain a vanadium-containing mother liquor;

[0074] (2) adding 180 mL of vanadium-containing mother liquor into 100 mL of [TOMA][DEHP]-[C4mim][NTf2], extracting at 25° C. for 30 min to extract vanadium into the ionic liquid to obtain a vanadium-extracted ionic liquid;

[0075] (3) adding 18 wt % sulfuric acid to the vanadium extraction ionic liquid in a volume ratio of vanadium extraction ionic liquid to sulfuric acid = 4:1, and back-extracting at 30° C. for 20 min to obtain a vanadium-containing acid solution;

[0076] (4) 200 mL of 18 wt % sulfuric acid was added to the vanadium-containing acid solution again to obtain a vanadium electrolyte, wherein the vanadium concentration in the obtained vanadium electrolyte was 1.72 mol / L.

[0077] Example 3

[0078] (I) Ionic liquids [P 4444 Preparation of ][EHEHP]

[0079] 20 g of sodium hydroxide and 180 g of tetrabutylphosphonium bromide were dissolved in 1000 g of isopropanol, mixed evenly, stirred at 35 ° C for 24 h, and the generated NaBr was filtered out using a sand core filter device to obtain [P 4444 ][OH] intermediate.

[0080] 150 g of 2-ethylhexyl phosphate mono-2-ethylhexyl ester was dissolved in 1000 g of isopropanol and [P 4444 The intermediate [OH] was stirred at 35 °C for 24 h, and the isopropanol was removed by rotary evaporation to obtain a viscous ionic liquid [P 4444 ][EHEHP], NMR spectrum as Figure 3 .

[0081] (II) Preparation of all-ionic liquid extraction system

[0082] By volume ratio, [P 4444 ][EHEHP]-[C4mim][NTf2]=2:8, take [P 4444 ][EHEHP] and [C4mim][NTf2] were mixed evenly to obtain a full ionic liquid extraction system ([P 4444 ][EHEHP]-[C4mim][NTf2]).

[0083] (III) Preparation of vanadium electrolyte

[0084] (1) 100 g of ammonium metavanadate was added with 200 mL of 20 wt% sulfuric acid and 2 g of sodium tripolyphosphate as a leaching aid, and reacted at room temperature for 6 h, and then filtered to obtain a vanadium-containing mother liquor;

[0085] (2) Add 180 mL of vanadium-containing mother liquor to 100 mL of [P 4444 ][EHEHP]-[C4mim][NTf2], extract at 25°C for 30 min, extract vanadium into the ionic liquid, and obtain vanadium extraction ionic liquid;

[0086] (3) adding 20 wt % sulfuric acid to the vanadium extraction ionic liquid in a volume ratio of vanadium extraction ionic liquid to sulfuric acid = 3:1, and back-extracting at 30° C. for 25 min to obtain a vanadium-containing acid solution;

[0087] (4) 215 mL of 20 wt % sulfuric acid was added to the vanadium-containing acid solution again to obtain a vanadium electrolyte, wherein the vanadium concentration in the obtained vanadium electrolyte was 1.71 mol / L.

[0088] Example 4

[0089] (I) Ionic liquids [P 4444 Preparation of ][DEHP]

[0090] 20 g of sodium hydroxide and 180 g of tetrabutylphosphonium bromide were dissolved in 1000 g of isopropanol, mixed evenly, stirred at 35 ° C for 24 h, and the generated NaBr was filtered out using a sand core filter device to obtain [P 4444 ][OH] intermediate.

[0091] 160 g of di(2-ethylhexyl) phosphate was dissolved in 1000 g of isopropanol and [P 4444 The intermediate [[P 4444 ][DEHP], NMR spectrum as Figure 4 .

[0092] (II) Preparation of all-ionic liquid extraction system

[0093] By volume ratio, [P 4444 ][DEHP]:[C4mim][NTf2]=2:8, take [P 4444 ][DEHP] and [C4mim][NTf2] were mixed evenly to obtain a full ionic liquid extraction system ([P 4444 [DEHP]-[C4mim][NTf2])

[0094] (III) Preparation of vanadium electrolyte

[0095] (1) Take 100 g of ammonium metavanadate, add 200 mL of 20 wt% sulfuric acid and 2 mg of leaching aid calcium fluoride, react at room temperature for 6 h, and filter to obtain a vanadium-containing mother liquor;

[0096] (2) Add 180 mL of vanadium-containing mother liquor to 100 mL of [P 4444 ][DEHP]-[C4mim][NTf2], extract at 25°C for 30 min, extract vanadium into the ionic liquid, and obtain vanadium extraction ionic liquid;

[0097] (3) adding 20 wt % sulfuric acid to the vanadium extraction ionic liquid in a volume ratio of vanadium extraction ionic liquid to sulfuric acid = 3:1, and back-extracting at 30° C. for 25 min to obtain a vanadium-containing acid solution;

[0098] (4) 220 mL of 20 wt % sulfuric acid was added to the vanadium-containing acid solution again to obtain a vanadium electrolyte, wherein the vanadium concentration in the obtained vanadium electrolyte was 1.75 mol / L.

[0099] Example 5

[0100] (I) Preparation of vanadium electrolyte

[0101] (1) Take a vanadium-containing material (vanadium concentration is 1wt%), first crush the vanadium-containing material into particles with a particle size of less than 2mm. Take 500g of the crushed vanadium-containing material, add 800mL of 15wt% sulfuric acid and 10g of leaching aid ammonium sulfate, react at room temperature for 6h, filter, and obtain a vanadium-containing mother liquor;

[0102] (2) adding 700 mL of the vanadium-containing mother liquor into 500 mL of the full ionic liquid extraction system shown in Table 1, extracting at 25° C. for 50 min to extract the vanadium into the ionic liquid, and obtaining vanadium extraction ionic liquids respectively;

[0103] (3) adding 15 wt % sulfuric acid to the vanadium extraction ionic liquid in a volume ratio of vanadium extraction ionic liquid to sulfuric acid = 3:1, and back-extracting at 30° C. for 30 min to obtain a vanadium-containing acid solution;

[0104] (4) The vanadium-containing acid solution was evaporated and concentrated to 25 mL to obtain a vanadium electrolyte. The vanadium concentration in the obtained vanadium electrolyte is shown in Table 1.

[0105] Table 1

[0106] All-ionic liquid extraction system Vanadium concentration in vanadium electrolyte (mol / L) <![CDATA[[TOMA][EHEHP]:[C4mim][NTf2]=2:8]]> 1.72 <![CDATA[[TOMA][DEHP]:[C4mim][NTf2]=2:8]]> 1.71 <![CDATA[[P 4444 ][EHEHP]-[C4mim][NTf2]=2:8]]> 1.71 <![CDATA[[P 4444 ][DEHP]:[C4mim][NTf2]=2:8]]> 1.72

[0107] It can be seen from Examples 1-4 and Table 1 that the vanadium electrolyte prepared by the present invention has a vanadium concentration greater than 1.7 mol / L.

[0108] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A full ionic liquid extraction system, characterized in that: The all-ionic liquid extraction system comprises an extractant and a diluent; the extractant is [TOMA][EHEHP], [TOMA][DEHP], [P 4444 ][EHEHP] or [P 4444 ][DEHP] or a mixture of any two of them in any proportion; the diluent is [C n mim][NTf2], [C n mim][PF6] or [C n mim][SbF6] or a mixture of any two of them in any proportion, wherein n=2-8.

2. The all-ionic liquid extraction system according to claim 1, characterized in that: By volume ratio, extractant: diluent = 1:3~5.

3. The all-ionic liquid extraction system according to claim 1, characterized in that: The preparation method of the extractant comprises the following steps: (1) Dissolve sodium hydroxide and methyl trioctyl ammonium chloride or tetrabutylphosphonium bromide in isopropanol, mix well, stir at 30-40° C. for 24-26 hours, filter, and obtain [TOMA][OH] intermediate or [P 4444 ][OH] intermediate; (2) Dissolve 2-ethylhexyl phosphate mono-2-ethylhexyl ester or di-2-ethylhexyl phosphate in isopropanol, and add [TOMA][OH] intermediate or [P 4444 The intermediate [TOMA] [EHEHP], [TOMA] [DEHP], [P 4444 ][EHEHP] or [P 4444 ][DEHP].

4. A method for preparing vanadium electrolyte based on a short process of full ionic liquid extraction system, characterized in that: Using the all-ionic liquid extraction system according to claim 1, 2 or 3, the method comprises the following steps: (1) adding sulfuric acid and a leaching aid to a vanadium-containing material, reacting for 4 to 12 hours, filtering, and obtaining a vanadium-containing mother liquor; (2) adding the vanadium-containing mother liquor into a full ionic liquid extraction system to obtain a vanadium extraction ionic liquid; (3) adding sulfuric acid to the vanadium extraction ionic liquid for stripping to obtain a vanadium-containing acid solution; (4) Add sulfuric acid again to the vanadium-containing acid solution or directly evaporate and concentrate it to obtain a vanadium electrolyte.

5. The method according to claim 4, characterized in that: In step (1), the leaching aid is one of ammonium sulfate, calcium fluoride or sodium tripolyphosphate, or a mixture of two of them in any proportion.

6. The method according to claim 5, characterized in that: In step (1), the amount of the leaching aid is 1-5% of the mass of the vanadium-containing material.

7. The method according to claim 4, characterized in that: In step (1), the concentration of the sulfuric acid is 10 to 25% by mass percentage.

8. The method according to claim 4, characterized in that: In step (2), the volume ratio of vanadium-containing mother liquor to full ionic liquid extraction system is 1:0.2-2.

9. The method according to claim 4, characterized in that: In step (3), the volume ratio of vanadium extraction ionic liquid to sulfuric acid is 1 to 5:1; the stripping is performed at 20 to 80° C. for 10 to 60 minutes; and the concentration of the sulfuric acid is 5 to 25% by mass percentage.

10. The method according to claim 4, characterized in that: In step (4), sulfuric acid is added again to adjust the vanadium concentration in the obtained vanadium electrolyte to 1.5-2.0 mol / L; in terms of mass percentage, the concentration of the sulfuric acid is 5-25%.

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