Method for preparing high-performance vanadium electrolyte from vanadium slag intermediate product and application

Abstract

The invention belongs to the technical field of vanadium batteries, and particularly relates to a method for preparing a high-performance vanadium electrolyte from a vanadium slag intermediate product and application of the high-performance vanadium electrolyte. The vanadium slag intermediate product NaVO3 is converted into high-purity VOCl3 through chlorination reaction, the step of additionally preparing high-purity vanadium oxide is avoided, emission of waste water and waste gas is reduced, cost is reduced, clean preparation is achieved, and the method is suitable for industrial production. And no toxic gas is generated. VOCl3 has high purity and excellent solubility and can be directly used for preparing the high-concentration vanadium electrolyte. On the basis of a sulfate-chloride system, VOCl3 is directly dissolved in a sulfuric acid solution, and hydrochloric acid does not need to be additionally added as a chlorine source. The 2.0 mol / L vanadium electrolyte prepared by the process is applied to VRFB, and the energy efficiency reaches more than 89%.

Description

Technical Field

[0001] The present invention relates to the technical field of vanadium batteries, in particular to a method for preparing a high-performance vanadium electrolyte using a vanadium slag intermediate product and its application, in particular to a method for preparing vanadium oxychloride using a vanadium slag intermediate product, a method for preparing a vanadium electrolyte and a vanadium battery. Background Art

[0002] Large-scale energy storage systems can improve the reliability and economic viability of renewable energy. Vanadium redox flow batteries (VRFBs) are one of the most promising large-scale energy storage technologies due to their high energy efficiency, rapid response, long lifespan, and low environmental impact. The vanadium electrolyte, a core component of VRFBs, directly impacts the battery's performance, cost, and lifespan.

[0003] Currently, vanadium slag is the primary raw material for the production of vanadium compounds. Through processes such as "sodium roasting-water leaching" and "calcification roasting-acid leaching," intermediate products such as sodium metavanadate can be obtained. Traditionally, these intermediates are further processed into V2O5 or VOSO4 for use in the preparation of vanadium electrolytes. Currently, thionyl chloride is used as a chlorinating agent to react with vanadium pentoxide to produce VOCl3. However, this is highly toxic and produces large amounts of toxic sulfur dioxide gas, which can be highly hazardous to humans and the environment. Existing techniques use vanadium chromium slag mixed with a chlorinating agent at a reaction temperature of 200-600°C to produce vanadium oxytrichloride. This method requires high temperatures, high energy consumption, and harsh reaction conditions. Furthermore, it uses highly toxic chlorine as a raw material. Consequently, these traditional processes are complex, difficult to operate, and generate significant amounts of wastewater and exhaust emissions, making them difficult to meet the requirements of a green economy transition.

[0004] The mixed acid system significantly improves the stability and electrochemical performance of the electrolyte. - The supporting electrolyte solution is mixed with SO4 2- and Cl -The supporting solution can improve the energy density and improve the stability and solubility of one or more ionic substances in the cathode or anode electrolyte. At present, the raw materials for preparing the electrolyte are mostly vanadium-containing substances such as V2O5 and VOSO4. There are problems such as low solubility of vanadium substances in sulfuric acid solution (about 0.3-0.6 mol / L), slow dissolution rate, and easy precipitation that need to be solved. Solving the problem of raw material solubility is an important issue that urgently needs to be solved. It is of great significance to promote the development of high-concentration vanadium electrolytes. Compared with V2O5 or VOSO4, liquid VOCl3 has a higher solubility in sulfuric acid solution, and its liquid-liquid reaction in sulfuric acid solution can increase the reaction rate. The prior art records a method of preparing a 2.0M mixed acid electrolyte by adding vanadium trichloride to sulfuric acid, and preparing vanadium electrolytes of different valence states by electrolysis. However, its preparation process is relatively complicated.

[0005] Therefore, how to develop a short-process, green and sustainable preparation technology that can directly convert intermediate products into high-purity vanadium electrolyte raw materials, and through process technology innovation, improve the stability and electrochemical performance of the electrolyte while increasing the concentration of the electrolyte, is the key to promoting the development and application of VRFB. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a method for preparing vanadium oxychloride using a vanadium slag intermediate product, a method for preparing a vanadium electrolyte, and a vanadium battery. The method of the present invention can realize the preparation of high-purity vanadium oxychloride as a raw material for vanadium electrolyte from a vanadium slag intermediate product (sodium metavanadate), while improving the yield, avoiding the use of toxic raw materials and reducing reaction energy consumption, thereby obtaining a high-performance vanadium electrolyte and a vanadium battery.

[0007] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0008] A method for preparing vanadium oxychloride using a vanadium slag intermediate product comprises:

[0009] Anhydrous aluminum chloride, sodium chloride and sodium metavanadate, an intermediate product of vanadium slag, are uniformly mixed and placed in a container. Inert gas is introduced and the temperature is increased to react to chlorinate the sodium metavanadate to obtain gaseous VOCl3; the gaseous VOCl3 is condensed to obtain liquid VOCl3.

[0010] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0011] A method for preparing a vanadium electrolyte comprises the following steps:

[0012] S1. Add the VOCl3 liquid obtained by the above method into a sulfuric acid solution at room temperature and stir to fully dissolve it to obtain a V(V) solution;

[0013] S2, placing the V(V) solution in a container and heating it to a constant temperature, adding a reducing agent and allowing it to react fully to obtain a V(IV) electrolyte;

[0014] S3. The V(IV) electrolyte is used as the positive electrode and negative electrode electrolyte for electrolysis, to obtain V(V) electrolyte at the positive electrode and V(II) and V(III) electrolytes at the negative electrode.

[0015] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0016] A vanadium battery, comprising a vanadium electrolyte obtained by the above-mentioned method for preparing the vanadium electrolyte.

[0017] As a preferred embodiment of the vanadium battery of the present invention, the vanadium battery can operate stably at -20 to 50° C., and the energy efficiency reaches above 89%.

[0018] The beneficial effects of the present invention are as follows:

[0019] This invention proposes a method for preparing vanadium oxychloride using a vanadium slag intermediate product, a method for preparing a vanadium electrolyte, and a vanadium battery. The vanadium slag intermediate product, NaVO3, is converted into high-purity VOCl3 through a chlorination reaction. In this method, sodium metavanadate is converted into gaseous VOCl3, which is then condensed to obtain high-purity liquid VOCl3. This method avoids the additional step of preparing high-purity vanadium oxide, reduces wastewater and exhaust emissions, and offers a clean production process without the generation of any toxic gases. VOCl3, as a liquid vanadium-containing substance, has high purity and excellent solubility and can be directly used to prepare a high-concentration vanadium electrolyte. Based on a sulfate-chloride system, VOCl3 is directly dissolved in a sulfuric acid solution, eliminating the need for the addition of hydrochloric acid as a chlorine source. Consequently, this method significantly reduces the production cost of the vanadium electrolyte. The 2.0 mol / L vanadium electrolyte prepared using this method has been applied to VRFBs, achieving an energy efficiency exceeding 89%. This invention provides a new, short-process, green method for the preparation of high-performance vanadium electrolyte raw materials, laying the foundation for the development and application of low-cost, high-energy-efficiency vanadium electrolytes for VRFBs. DETAILED DESCRIPTION

[0020] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0021] This invention proposes a method for preparing vanadium oxychloride from a vanadium slag intermediate, a method for preparing a vanadium electrolyte, and a vanadium battery. The sodium metavanadate, an intermediate product from the vanadium slag, is treated with an inert gas-low-temperature chlorination process. The chlorination temperature is low, effectively reducing energy consumption and equipment requirements. This method achieves efficient chlorination extraction of vanadium, producing a high-purity VOCl3 product, enabling clean and efficient production. Compared to existing processes, this invention has the following advantages:

[0022] (1) A new process for converting NaVO3, an intermediate product from vanadium slag, into high-purity VOCl3 through a chlorination reaction. In this process, sodium metavanadate is converted into gaseous VOCl3, which is then condensed to obtain high-purity liquid VOCl3. This process avoids the additional step of preparing high-purity vanadium oxide and reduces wastewater and exhaust gas emissions. This process reduces costs while ensuring a clean production process without generating any toxic gases.

[0023] (2) The obtained high-purity VOCl3, as a liquid vanadium-containing substance, has high solubility in sulfuric acid solution and can be directly used to prepare high-concentration vanadium electrolyte.

[0024] (3) Based on the sulfate-chloride system, VOCl3 is directly dissolved in a sulfuric acid solution without the need for external hydrochloric acid as a chlorine source. This process significantly reduces the production cost of vanadium electrolyte. The 2.0 mol / L vanadium electrolyte prepared using this process is applied to VRFB, with an energy efficiency of over 89%. The present invention provides a new method for the short-process green preparation of high-performance vanadium electrolyte raw materials, laying the foundation for the development and application of low-cost, high-energy-efficiency VRFB vanadium electrolytes.

[0025] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0026] A method for preparing vanadium oxychloride using a vanadium slag intermediate product comprises:

[0027] Anhydrous aluminum chloride, sodium chloride and sodium metavanadate, an intermediate product of vanadium slag, are uniformly mixed and placed in a three-necked flask. Inert gas is introduced and the temperature is increased to react and chlorinate the sodium metavanadate to obtain gaseous VOCl3. The gaseous VOCl3 is discharged from the three-necked flask using an inert gas and condensed through a condenser to obtain liquid VOCl3.

[0028] Preferably, the temperature is increased from room temperature to a reaction temperature of 130-180° C. at a heating rate of 10° C. / min and the reaction is carried out for 0.5-4 h.

[0029] Preferably, the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:(3-6), and the molar ratio of anhydrous aluminum chloride to sodium chloride is (1-10):1.

[0030] The reaction equation of the present invention is: 3NaVO3+4AlCl3=3NaCl+2Al2O3+3VOCl3

[0031] The present invention adds an excessive amount of anhydrous aluminum chloride to enable aluminum chloride to fully contact with NaVO3, so that NaVO3 can react as completely as possible; the present invention also adds a certain amount of sodium chloride, which can form a molten salt with aluminum chloride and absorb AlCl3 impurities in VOCl3, thereby playing a purification role.

[0032] Preferably, the inert atmosphere is selected from any one of argon, helium, and nitrogen, or a mixture of several of them.

[0033] Preferably, the condensation temperature is -20 to 5°C, and the condensation time is 0.5 to 4 hours.

[0034] Preferably, the mass percentage of impurities such as Fe and / or Al in the liquid VOCl3 is 0.001-0.1%. The Fe and / or Al ions come from sodium metavanadate, an intermediate product of the vanadium slag, and aluminum chloride that may volatilize.

[0035] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0036] A method for preparing a vanadium electrolyte comprises the following steps:

[0037] S1. Add the VOCl3 liquid obtained by the above method into a sulfuric acid solution at room temperature and stir to fully dissolve it to obtain a V(V) solution;

[0038] S2. Place the V(V) solution in a three-necked flask and heat it to a constant temperature. Add a reducing agent and allow it to react fully to obtain a V(IV) electrolyte. Connect a condenser to the three-necked flask to collect water vapor and reduce liquid volatilization.

[0039] S3, the V(IV) electrolyte is used as the positive and negative electrolytes for electrolysis, the positive electrode obtains V(V) electrolyte, and the negative electrode obtains V(II) and V(III) electrolytes. V(II), V(III), V(IV), V(V) represent different valence states of V(V) respectively. 2+ 、V 3+ 、V 4 + 、V 5+ ).

[0040] Preferably, in step S1, the concentration of the sulfuric acid solution is 1.5-5.0 mol / L, the molar ratio of VOCl3 liquid to sulfuric acid is 1:(1.5-6), and the dissolution time is 5-100 min.

[0041] Preferably, in step S2, the constant temperature condition is 50-95° C., the reaction time is 10-100 min, and the molar ratio of V(V) to the reducing agent is (0.5-1.5):1.

[0042] Preferably, in step S2, the reducing agent is selected from one or more of oxalic acid, sulfurous acid, tartaric acid, formic acid, acetic acid or hydrogen peroxide.

[0043] Preferably, in step S2, the vanadium reduction rate of the V(IV) electrolyte is determined to be 95-99% by potentiometric titration.

[0044] Preferably, in steps S1-S3, the concentration range of the electrolytes V(V), V(IV), V(II) and V(III) is 1.5-3.5 mol / L.

[0045] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0046] A vanadium battery, comprising a vanadium electrolyte obtained by the above-mentioned method for preparing a vanadium electrolyte; the vanadium battery can operate stably at -20 to 50° C., with an energy efficiency exceeding 89%.

[0047] The technical solution of the present invention is further described below with reference to specific embodiments.

[0048] Example 1

[0049] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 16.5g of anhydrous aluminum chloride, 0.717g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:3, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate, generating gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon gas and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 5.52g of liquid VOCl3 is obtained, with a yield of 77.7%.

[0050] Example 2

[0051] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 22g of anhydrous aluminum chloride, 0.96g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:4, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate, generating gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon gas and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 5.96g of liquid VOCl3 is obtained, with a yield of 83.1%.

[0052] Example 3

[0053] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 6.75g of liquid VOCl3 is obtained, with a yield of 94.1%.

[0054] Example 4

[0055] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 33g of anhydrous aluminum chloride, 1.44g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:6, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 6.8g of liquid VOCl3 is obtained, with a yield of 94.8%.

[0056] Example 5

[0057] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using a vanadium slag intermediate product comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 130°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon gas and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 5.97g of liquid VOCl3 is obtained, with a yield of 83.2%.

[0058] Example 6

[0059] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 145°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 6.26g of liquid VOCl3 is obtained, with a yield of 87.3%.

[0060] Example 7

[0061] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 175°C at a heating rate of 10°C / min for 4 hours to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 4 hours. Finally, 6.73g of liquid VOCl3 is obtained, with a yield of 93.8%.

[0062] Example 8

[0063] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min and kept warm for 0.5 hours to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 0.5 hours. Finally, 3.21g of liquid VOCl3 is obtained, with a yield of 44.7%.

[0064] Example 9

[0065] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using a vanadium slag intermediate product comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min and kept warm for 1 hour to achieve chlorination of sodium metavanadate and generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon and condensed through a condenser. The condensation temperature is set to 0°C and the condensation time is 1 hour. Finally, 6.31g of liquid VOCl3 is obtained, with a yield of 88.0%.

[0066] Example 10

[0067] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using a vanadium slag intermediate product comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 1.2g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min and kept warm for 2 hours to achieve chlorination of the sodium metavanadate, generating gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon gas and condensed through a condenser. The condensation temperature is set at 0°C and the condensation time is 2 hours. Finally, 6.58g of liquid VOCl3 is obtained, with a yield of 91.7% and a purity of VOCl3 of 99.96%.

[0068] Example 11

[0069] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using a vanadium slag intermediate product comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 3g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 4:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min and kept warm for 2 hours to achieve chlorination of the sodium metavanadate, generating gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon gas and condensed through a condenser. The condensation temperature is set at 0°C and the condensation time is 2 hours. Finally, 6.84g of liquid VOCl3 is obtained, with a yield of 95.4% and a purity of VOCl3 of 99.98%.

[0070] Example 12

[0071] A method for preparing vanadium trichloride, a raw material for vanadium electrolyte, using vanadium slag intermediates comprises the following steps: first, 27.5g of anhydrous aluminum chloride, 6g of sodium chloride, and 5.0g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:5, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 2:1) are uniformly mixed, placed in a three-necked flask, purged with argon to form an inert atmosphere, and the temperature is raised to 160°C at a heating rate of 10°C / min and kept warm for 2 hours to achieve chlorination of sodium metavanadate, generating gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, the gaseous VOCl3 is discharged from the three-necked flask using argon gas and condensed through a condenser. The condensation temperature is set at 0°C and the condensation time is 2 hours. Finally, 6.86g of liquid VOCl3 is obtained, with a yield of 95.7% and a purity of VOCl3 of 99.97%.

[0072] Example 13

[0073] S1. Add sulfuric acid solution to the VOCl3 liquid obtained in Example 11 at room temperature and stir to fully dissolve it to obtain V(V) solution;

[0074] S2. Place the V(V) solution in a three-necked flask and heat it to a constant temperature. Add a reducing agent and allow it to react fully to obtain a V(IV) electrolyte.

[0075] S3. The V(IV) electrolyte is used as the positive electrode and negative electrode electrolyte for electrolysis, to obtain V(V) electrolyte at the positive electrode and V(II) and V(III) electrolytes at the negative electrode.

[0076] S4, the prepared 2.0M V(II) and V(III) electrolytes were subjected to electrochemical tests at 25°C and 80 mA cm -2The energy efficiency of the vanadium battery reached 89% at 25°C and 100 mA cm -2 The energy efficiency of the vanadium battery reached 89.9% at 25°C and 120 mA cm -2 At a current density of 1.5 GHz, the vanadium battery energy efficiency reaches 91%.

[0077] Comparative Example 1

[0078] The difference from Example 10 is that 7.4g of anhydrous aluminum chloride, 0.32g of sodium chloride and 5g of sodium metavanadate (the molar ratio of sodium metavanadate to anhydrous aluminum chloride is 3:4, and the molar ratio of anhydrous aluminum chloride to sodium chloride is 10:1) are uniformly mixed and placed in a three-necked flask. Argon is introduced to form an inert atmosphere, and the temperature is heated to 160°C at a heating rate of 10°C / min and kept warm for 2 hours. Finally, argon is used to discharge gaseous VOCl3 from the three-necked flask and condensed by a condenser. The condensation temperature is set to 0°C and the condensation time is 2 hours. Finally, 1.29g of liquid VOCl3 is obtained, and the yield is only 18.0%.

[0079] The addition of anhydrous aluminum chloride in this comparative example is not excessive, which will lead to a decrease in the yield of VOCl3.

[0080] Comparative Example 2

[0081] The difference from Example 10 is that 27.5g of anhydrous aluminum chloride is evenly mixed with 5.0g of sodium metavanadate (the mol ratio of sodium metavanadate to anhydrous aluminum chloride is 1: 5), placed in a three-necked flask, argon is passed through to form an inert atmosphere, and the temperature is heated to 160°C with a heating rate of 10°C / min and is incubated for 2 hours, to achieve the chlorination of sodium metavanadate, generate gaseous VOCl3 and AlCl3-NaCl molten salt. Finally, gaseous VOCl3 is discharged from three-necked flask using argon gas, and condensation is carried out by condensing tube, and condensation temperature is set at 0°C, and condensation time is 2 hours, and 6.17g of liquid VOCl3 is finally obtained, and the yield is 86.1%, and VOCl3 has a purity of 99.90%.

[0082] In this comparative example, NaCl is not added, which will result in a lower yield of VOCl3 and a lower purity of VOCl3.

[0083] Comparative Example 3

[0084] The difference from Example 13 is that V2O5 is directly dissolved in sulfuric acid-hydrochloric acid solution as vanadium-containing material to prepare 2.0M vanadium electrolyte. -2 At this current density, the vanadium battery energy efficiency is 75.4%.

[0085] Comparative Example 4

[0086] The difference from Example 13 is that VOSO4 is directly dissolved in sulfuric acid-hydrochloric acid solution as the vanadium-containing substance to prepare a 2.0M vanadium electrolyte at 25°C and 100 mA·cm -2 At this current density, the vanadium battery energy efficiency is 81.6%.

[0087] By comparing the vanadium electrolyte prepared by VOCl3 in the present invention with other vanadium-containing substances V2O5 and VOSO4, it is found that the energy efficiency of the 2.0M vanadium electrolyte prepared by the present invention is much higher than that of other vanadium-containing substances. The battery performance effect of the embodiment of the present invention is better, and the rationality of the research is demonstrated by the better results.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing vanadium oxychloride using a vanadium slag intermediate product, characterized in that: include: Anhydrous aluminum chloride, sodium chloride and sodium metavanadate, an intermediate product of vanadium slag, are uniformly mixed and placed in a container. Inert gas is introduced and the temperature is increased to react to chlorinate the sodium metavanadate to obtain gaseous VOCl3; the gaseous VOCl3 is condensed to obtain liquid VOCl3.

2. The method for preparing vanadium oxychloride using a vanadium slag intermediate product according to claim 1, wherein: The temperature is raised from room temperature at a heating rate of 10°C / min to a reaction temperature of 130-180°C and the reaction is carried out for 0.5-4h.

3. The method for preparing vanadium oxychloride using a vanadium slag intermediate product according to claim 1, characterized in that: The molar ratio of sodium metavanadate to anhydrous aluminum chloride is 1:(3-6), and the molar ratio of anhydrous aluminum chloride to sodium chloride is (1-10):

1.

4. The method for preparing vanadium oxychloride using a vanadium slag intermediate product according to claim 1, wherein: The condensation temperature is -20 to 5° C., the condensation time is 0.5 to 4 hours, and the mass percentage of impurities in the liquid VOCl 3 is 0.001 to 0.1%.

5. A method for preparing a vanadium electrolyte, characterized in that: The steps include: S1. Adding the VOCl3 liquid obtained by the method according to any one of claims 1 to 4 to a sulfuric acid solution at room temperature, stirring to fully dissolve it, to obtain a V(V) solution; S2, placing the V(V) solution in a container and heating it to a constant temperature, adding a reducing agent and allowing it to react fully to obtain a V(IV) electrolyte; S3. The V(IV) electrolyte is used as the positive electrode and negative electrode electrolyte for electrolysis, to obtain V(V) electrolyte at the positive electrode and V(II) and V(III) electrolytes at the negative electrode.

6. The method for preparing a vanadium electrolyte according to claim 5, wherein: In step S1, the concentration of the sulfuric acid solution is 1.5-5.0 mol / L, the molar ratio of VOCl3 liquid to sulfuric acid is 1:(1.5-6), and the dissolution time is 5-100 min.

7. The method for preparing a vanadium electrolyte according to claim 5, wherein: In step S2, the constant temperature condition is 50-95° C., the reaction time is 10-100 min, and the molar ratio of V(V) to the reducing agent is (0.5-1.5):

1.

8. The method for preparing a vanadium electrolyte according to claim 5, wherein: In step S2, the reducing agent is selected from one or more of oxalic acid, sulfurous acid, tartaric acid, formic acid, acetic acid or hydrogen peroxide.

9. The method for preparing a vanadium electrolyte according to claim 5, wherein: In step S2, the vanadium reduction rate of the V(IV) electrolyte is determined to be 95-99% by potentiometric titration; in steps S1-S3, the concentration range of the V(V), V(IV), V(II) and V(III) electrolytes is 1.5-3.5 mol / L.

10. A vanadium battery, characterized in that: The vanadium electrolyte is obtained by the preparation method of the vanadium electrolyte according to any one of claims 5 to 9; the vanadium battery can operate stably at -20 to 50° C., and the energy efficiency reaches more than 89%.