All-vanadium redox flow battery hydrochloric acid / mixed acid-based energy storage medium precursor, preparation method and application

Abstract

The invention belongs to the field of electrochemistry, and particularly relates to an all-vanadium redox flow battery hydrochloric acid / mixed acid-based energy storage medium precursor, a preparation method and application. The invention relates to a preparation method of an all-vanadium redox flow battery hydrochloric acid / mixed acid-based energy storage medium precursor, which comprises the following steps: mixing ammonium metavanadate with a chlorinating agent and a reducing agent, reacting at a high temperature under the protection of a gas atmosphere, cooling, and dissolving the mixture in an acid solution to prepare the all-vanadium redox flow battery hydrochloric acid / mixed acid-based energy storage medium precursor. The preparation process disclosed by the invention is simple to operate, energy-saving, environment-friendly and low in cost, and meanwhile, stable operation of the electrolyte in the battery can be realized.

Description

Technical Field

[0001] The invention belongs to the field of electrochemistry, and in particular relates to a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery, a preparation method and an application thereof. Background Art

[0002] Wind energy and solar energy are considered the cleanest renewable energy sources, but due to natural factors, they cannot obtain continuous and stable energy, and must be regulated by large-scale energy storage technology. However, the backwardness of energy storage technology has become a bottleneck restricting the utilization of these two renewable energy sources. All-vanadium liquid flow battery is a new type of energy storage battery with the advantages of high energy conversion efficiency, long service life, convenient capacity adjustment, high safety and environmental friendliness. It can be used in large-scale energy storage fields such as renewable energy such as solar energy and wind energy and peak-shaving and valley-filling of power grids. It is one of the most promising energy storage devices. Among them, the electrolyte, as a carrier of active substances, is one of the most important components of all-vanadium liquid flow batteries. The performance and concentration of the electrolyte directly affect the performance and energy density of the battery. How to obtain high-performance vanadium electrolyte has become a hot topic for researchers from various countries.

[0003] In recent years, the energy storage medium of all-vanadium liquid flow battery with hydrochloric acid and sulfuric acid as supporting electrolytes has gradually replaced the pure sulfuric acid system. This system has the advantages of high power density and good energy efficiency. At present, the mixed acid system mainly uses electrolysis or chemical reduction to first synthesize low-valent vanadium oxides, and then dissolves them in a mixed solution of sulfuric acid and hydrochloric acid.

[0004] The chemical method mainly uses vanadium oxide or other vanadium salts as raw materials, heats them in a certain concentration of sulfuric acid solution and adds a reducing agent (such as S, SO2, etc.) to dissolve and reduce them to low-priced and soluble vanadium compounds, thereby preparing a vanadium electrolyte of a certain concentration. The advantage of the chemical synthesis method is that the production equipment is simple, but the solid dissolution rate is slow, and the added reducing agent will remain in the vanadium electrolyte and is difficult to eradicate, affecting the purity and performance of the vanadium electrolyte. The electrolysis method generally uses an electrolytic cell device with a diaphragm, using V2O5 or metavanadate as raw materials, adding an H2SO4 solution containing V2O5 or metavanadate to the negative electrode area of ​​the electrolytic cell, adding the same concentration of H2SO4 to the positive electrode area, adding appropriate direct current to the two electrodes of the electrolytic cell, and the V2O5 or metavanadate powder is reduced on the negative electrode surface through contact with the negative electrode to prepare the all-vanadium liquid flow battery electrolyte. The electrolysis method can continuously prepare high-concentration vanadium electrolyte in large quantities, is simple and convenient to operate, and is easy to carry out industrial production; in addition, the electrolysis method also has the disadvantages of slow reaction rate, high equipment requirements, high energy consumption and high cost.

[0005] In summary, the existing methods all adopt the method of dissolving V2O5 in sulfuric acid or a mixed solution of sulfuric acid and hydrochloric acid, and forming a low-valent vanadium ion acid solution by chemical or electrolytic methods. And finally make the all-vanadium liquid flow battery energy storage medium. In practical applications, it involves the secondary transportation of concentrated sulfuric acid and sulfuric acid-containing electrolyte, which greatly increases the cost. Moreover, the precursor synthesis and electrolyte configuration processes are separated, resulting in a huge waste of resources. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery, comprising the following steps:

[0007] Ammonium metavanadate is mixed with a chlorinating agent and a reducing agent, and reacted under high temperature and gas atmosphere protection to obtain a mixture. After cooling, the mixture is dissolved in an acid solution to obtain a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery.

[0008] Furthermore, the mass ratio of the ammonium metavanadate to the reducing agent is 1:1-5.

[0009] Furthermore, the mass ratio of the ammonium metavanadate to the chlorinating agent is 1:1-10.

[0010] Furthermore, the reaction temperature is 800-1500°C.

[0011] Furthermore, the reaction time is 1 to 4 hours.

[0012] Furthermore, the reaction atmosphere is any one of argon and nitrogen.

[0013] Furthermore, the acid solution is any one of sulfuric acid and hydrochloric acid.

[0014] Furthermore, the acid solution is 3-8M.

[0015] A hydrochloric acid / mixed acid based energy storage medium precursor for all-vanadium liquid flow batteries.

[0016] The invention discloses an application of a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery. The hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery is applied in the preparation of an all-vanadium liquid flow battery.

[0017] Beneficial Effects

[0018] (1) The present invention provides a method for preparing a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery. The preparation method is a simple, convenient and low-cost route for preparing a mixed acid electrolyte. The present invention uses a high-temperature solid phase method to synthesize the required low-valent vanadium chloride solid powder in one step. By adjusting the reaction conditions, a mixture of different low-valent vanadium chlorides in different proportions can be prepared, which is suitable for the subsequent configuration of the all-vanadium liquid flow battery mixed acid energy storage medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0020] In the figure:

[0021] Figure 1 to Figure 5 : XRD diagrams of vanadium chlorides of different valence states of the present invention;

[0022] Figure 6 to Figure 10 is a topographical diagram of the present invention;

[0023] Figure 11 to Figure 15 It is a performance diagram of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with embodiments 1 to 5 of the present invention and the attached Figures 1 to 15 , the technical solution of the present invention is clearly and completely described. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0025] The present invention provides a method for preparing a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery, comprising the following steps:

[0026] First, a mixture of ammonium metavanadate, a chlorinating agent and a reducing agent is decomposed under high temperature and gas atmosphere to obtain a mixture of different low-valent vanadium chlorides containing different proportions, and the all-vanadium liquid flow battery energy storage medium is configured according to the proportion of different valence vanadium chlorides, wherein the reducing agent is a carbon material, a sulfide and a carbon-containing organic polymer material; the chlorinating agent is a chlorinated organic polymer material, ammonium chloride and other high-temperature easily decomposable chlorides. The weight ratio of ammonium metavanadate to the reducing agent is between 1:1-1:5; the weight ratio of ammonium metavanadate to the chlorinating agent is between 1:1-1:10. The high-temperature reaction temperature of the mixture is between 800-1500℃; the high-temperature reaction time of the mixture is between 1-4h; the high-temperature reaction atmosphere of the mixture is an inert gas such as argon and nitrogen; the decomposition product is dissolved in a 3-5M sulfuric acid solution to configure the all-vanadium liquid flow battery mixed acid energy storage medium precursor.

[0027] Example 1

[0028] 4 g of ammonium metavanadate powder, 20 g of sodium sulfite, and 20 g of chlorinated polyethylene are mixed to obtain a mixture, and the mixture is reacted at 800° C. under argon gas protection for 1 hour. After cooling to room temperature, the mixture is taken out and dissolved in a 3M sulfuric acid solution to prepare a vanadium liquid flow battery energy storage medium precursor with a total vanadium ion concentration of 1.6M.

[0029] The solution was used to assemble an all-vanadium redox flow battery for performance testing to evaluate the performance of the electrolyte. All-vanadium redox flow battery test conditions: The positive and negative electrodes are 800 cm 2 Carbon felt electrode, positive and negative electrodes are made of the prepared solution, using 80mA / cm 2 The charge and discharge cycles are carried out at a current density of , the charge cut-off condition is that the voltage is not higher than 1.5V, and the discharge cut-off condition is that the voltage is not lower than 0.1V.

[0030] Example 2

[0031] 4 g of ammonium metavanadate powder, 4 g of elemental sulfur, and 4 g of ammonium chloride are mixed to obtain a mixture, and the mixture is reacted at 1000° C. under argon gas protection for 2 hours, cooled to room temperature, taken out, dissolved in 4M sulfuric acid solution, and prepared into a mixed acid energy storage medium precursor for all-vanadium liquid flow battery with a total vanadium ion concentration of 1.6M.

[0032] The solution was used to assemble an all-vanadium redox flow battery for performance testing to evaluate the performance of the electrolyte. All-vanadium redox flow battery test conditions: The positive and negative electrodes are 800 cm 2 Carbon felt electrode, positive and negative electrodes are made of the prepared solution, using 80mA / cm 2 The charge and discharge cycles are carried out at a current density of , the charge cut-off condition is that the voltage is not higher than 1.5V, and the discharge cut-off condition is that the voltage is not lower than 0.1V.

[0033] Example 3

[0034] 2 g of ammonium metavanadate powder, 10 g of activated carbon, and 20 g of chlorinated polypropylene are mixed to obtain a mixture, and the mixture is reacted at 1200° C. under nitrogen gas protection for 4 hours, cooled to room temperature, taken out, dissolved in 4M sulfuric acid solution, and prepared into a mixed acid energy storage medium precursor for all-vanadium liquid flow battery with a total vanadium ion concentration of 1.6M.

[0035] The solution was used to assemble an all-vanadium redox flow battery for performance testing to evaluate the performance of the electrolyte. All-vanadium redox flow battery test conditions: The positive and negative electrodes are 800 cm 2 Carbon felt electrode, positive and negative electrodes are made of the prepared solution, using 80mA / cm 2 The charge and discharge cycles are carried out at a current density of , the charge cut-off condition is that the voltage is not higher than 1.5V, and the discharge cut-off condition is that the voltage is not lower than 0.1V.

[0036] Example 4

[0037] 5 g of ammonium metavanadate powder, 10 g of graphite, and 25 g of ammonium chloride are mixed to obtain a mixture, and the mixture is reacted at 1300° C. under argon gas protection for 4 hours, cooled to room temperature, taken out, dissolved in 5 M sulfuric acid solution, and prepared into a mixed acid energy storage medium precursor for all-vanadium liquid flow battery with a total vanadium ion concentration of 1.6 M.

[0038] The solution was used to assemble an all-vanadium redox flow battery for performance testing to evaluate the performance of the electrolyte. All-vanadium redox flow battery test conditions: The positive and negative electrodes are 800 cm 2 Carbon felt electrode, positive and negative electrodes are made of the prepared solution, using 80mA / cm 2 The charge and discharge cycles are carried out at a current density of , the charge cut-off condition is that the voltage is not higher than 1.5V, and the discharge cut-off condition is that the voltage is not lower than 0.1V.

[0039] Example 5

[0040] 5 g of ammonium metavanadate powder, 25 g of melamine, and 25 g of chlorinated polyethylene are mixed to obtain a mixture, and the mixture is reacted at 1500° C. under nitrogen gas protection for 3 hours, cooled to room temperature, taken out, dissolved in 4M sulfuric acid solution, and prepared into a mixed acid energy storage medium precursor for all-vanadium liquid flow battery with a total vanadium ion concentration of 1.6M.

[0041] The solution was used to assemble an all-vanadium redox flow battery for performance testing to evaluate the performance of the electrolyte. All-vanadium redox flow battery test conditions: The positive and negative electrodes are 800 cm 2 Carbon felt electrode, positive and negative electrodes are made of the prepared solution, using 80mA / cm 2 The charge and discharge cycle is carried out at a current density of , the charge cut-off condition is that the voltage is not higher than 1.5V, and the discharge cut-off condition is that the voltage is not lower than 0.1V.

[0042] from Figure 1 - Figure 5 It can be seen that although the composition and ratio of each substance in each embodiment are different, after sintering, the solid powders produced are all composed of tetravalent and trivalent chlorides or sulfates of vanadium, and according to the different components, the trivalent and tetravalent XRD peak intensities of the sintered products are slightly different, indicating that the tetravalent and trivalent compositions of vanadium are different. Figure 6-10 The morphology of the solid powder after sintering in each embodiment is shown, which is not much different, and all are spherical. At the same time, according to the parameters such as vanadium ion concentration in Table 1, it can be found that the total vanadium concentration is basically around 1.6M, and the ratio of trivalent and tetravalent vanadium ions is around 1. The sulfate concentration is stable at around 2M, which is in line with the preparation expectations. Figure 11-15 The battery performance parameters obtained from the battery cycle performance test are shown in Table 2. From the data in Table 2, it can be found that the application of the all-vanadium liquid flow battery mixed acid energy storage medium synthesized by adding a chlorinating agent to the all-vanadium liquid flow battery can obtain higher coulombic efficiency and energy efficiency.

[0043] Table 1 shows the data of total vanadium, vanadium ion ratio, chloride ion and sulfate ion in the solution

[0044]

[0045]

[0046] Table 2 is a performance comparison table

[0047] Serial number Solution Coulomb efficiency (%) Voltage efficiency (%) Energy efficiency (%) 1 1 95.96 87.07 83.55 2 2 96.51 87.13 84.09 3 3 96.00 87.07 83.58 4 4 97.23 86.84 84.44 5 5 96.98 86.54 84.18

[0048] Through the preparation method of a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery provided by the present invention, low-valent vanadium chloride is synthesized in one step by a high-temperature solid-phase method, which can effectively reduce the energy consumption and time in the synthesis process and improve production efficiency. Secondly, adjusting the reaction conditions to achieve vanadium chloride mixtures in different proportions provides greater flexibility to meet the needs of all-vanadium liquid flow batteries in different application scenarios. This preparation route of mixed acid electrolyte not only simplifies the process flow, reduces equipment investment, but also reduces the cost of raw materials, greatly improving the economy and feasibility of all-vanadium liquid flow batteries. In addition, the prepared energy storage medium has excellent electrochemical properties, which helps to improve the cycle life and energy density of the battery, and promotes the widespread application of this technology in the field of renewable energy storage.

Claims

1. A method for preparing a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery, characterized in that: The following steps are involved: Ammonium metavanadate is mixed with a chlorinating agent and a reducing agent, and reacted under high temperature and gas atmosphere protection to obtain a mixture. After cooling, the mixture is dissolved in an acid solution to obtain a hydrochloric acid / mixed acid-based energy storage medium precursor for an all-vanadium liquid flow battery.

2. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The mass ratio of the ammonium metavanadate to the reducing agent is 1:1-5.

3. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The mass ratio of ammonium metavanadate to the chlorinating agent is 1:1-10.

4. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The reaction temperature is 800-1500°C.

5. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The reaction time is 1 to 4 hours.

6. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The reaction atmosphere is any one of argon and nitrogen.

7. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The acid solution is any one of sulfuric acid and hydrochloric acid.

8. The method for preparing a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 1, characterized in that: The acid solution is 3-8M.

9. A hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery obtained according to the preparation method of any one of claims 1 to 8.

10. The use of a hydrochloric acid / mixed acid based energy storage medium precursor for an all-vanadium liquid flow battery according to claim 9, characterized in that: The all-vanadium liquid flow battery hydrochloric acid / mixed acid-based energy storage medium precursor is used in the preparation of the all-vanadium liquid flow battery.

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