Preparation method for preparing all-vanadium electrolyte by taking ammonium polyvanadate as raw material

Abstract

The invention discloses a preparation method for preparing an all-vanadium electrolyte by taking ammonium polyvanadate as a raw material. The preparation method comprises the following steps: S1, crushing and grinding provided ammonium polyvanadate powder; s2, the ammonium polyvanadate powder is transferred into a vacuum metallurgical furnace to be calcined and decomposed; s3, crushing and grinding the produced blocky vanadium pentoxide; s4, hydrogen and nitrogen are prepared through liquid ammonia decomposition, and the vanadium pentoxide powder is reduced into vanadium dioxide (VO2) and vanadium trioxide (V2O3) powder in a hydrogen reduction furnace; s5, grinding the composite powder prepared in S4, and dissolving in a sulfuric acid solution; s6, determining the vanadium-containing mother liquor; and S7, the vanadium-containing mother liquor is used for the cathode, the sulfuric acid solution is used for the anode, and the vanadium-containing mother liquor and the sulfuric acid solution are electrolyzed and blended, so that the all-vanadium electrolyte with the valence state of + 3.5 is obtained. According to the invention, the high-purity ammonium polyvanadate is used as a raw material, so that the cost-effectiveness optimization is realized; environmental pollution is reduced through environment-friendly tail gas treatment and resource recycling; the one-step reduction technology simplifies the production steps and improves the product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of vanadium batteries, and particularly relates to a method for preparing an all-vanadium electrolyte by taking ammonium polyvanadate as a raw material. Background Art

[0002] As the proportion of new energy generation methods in my country's power energy system gradually increases, the volatility and instability of new power generation modes limit the utilization rate of this source of power energy and affect the stability of the power grid. To solve such problems, all-vanadium liquid flow batteries, as one of the representative technologies for long-term energy storage, have completed the development from demonstration projects to commercial projects from 2020 to date due to their flexibility, safety and large capacity. As of the end of 2023, according to statistics, there are a total of 1175MW h of all-vanadium liquid flow battery energy storage power stations under construction nationwide. In the 4-hour all-vanadium liquid flow battery energy storage system, its capacity unit (all-vanadium electrolyte) accounts for about 40% to 60% of the total investment cost. As capacity demand increases, its cost share will further increase.

[0003] In the process of preparing vanadium electrolyte, the oxalic acid reduction method can only reduce pentavalent vanadium to tetravalent, and it is impossible to obtain a vanadium ion solution with a lower valence state. Therefore, it needs to be further adjusted to +3.5 valence through electrolysis. Although this method is technically mature, the process steps are relatively cumbersome and the production efficiency is not high. In addition, in addition to using high-purity vanadium, high-purity oxalic acid is also required as a reducing agent, which costs about 6,000-8,000 yuan / ton. In theory, 1 ton of oxalic acid can produce 13 cubic meters of electrolyte with a concentration of 1.7 mol / L, resulting in an increase of 400-700 yuan in the cost of electrolyte per cubic meter.

[0004] Another technical route is to use reducing gas to reduce high-purity vanadium powder at high temperature. This method can directly produce a mixed powder of V2O3 and VO2, so the valence of the dissolved vanadium ion solution is lower than tetravalent. This method is superior to the oxalic acid reduction method in terms of cost and production speed. However, this route has strict process requirements and is somewhat dangerous.

[0005] Both routes use high-purity vanadium as raw material to produce vanadium electrolyte. Although there are differences in the process routes, since both use high-purity vanadium as the production raw material, it is impossible to achieve a significant reduction in the manufacturing cost of all-vanadium electrolyte. Therefore, in order to reduce costs, researchers are exploring the use of lower-priced vanadium sources, such as ammonium polyvanadate or ammonium metavanadate, in order to significantly reduce production costs. At the same time, the preparation process and technology are also being continuously optimized to improve production efficiency and reduce energy consumption. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material. By using ammonium polyvanadate as a raw material, high-purity vanadium pentoxide is prepared by high-temperature pyrolysis and gas reduction, and further converted into an all-vanadium electrolyte. The method has the advantages of short process flow, less equipment requirements, high cost-effectiveness, excellent environmental protection treatment and easy large-scale production, and effectively solves the cost, efficiency and environmental protection problems in traditional methods.

[0007] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0008] The present invention provides a method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material, the method comprising the following steps:

[0009] S1: crushing and grinding the provided ammonium polyvanadate powder;

[0010] S2: transferring the ammonium polyvanadate powder to a vacuum metallurgical furnace for calcination and decomposition;

[0011] S3: crushing and grinding the produced bulk vanadium pentoxide;

[0012] S4: preparing hydrogen and nitrogen by decomposing liquid ammonia to reduce vanadium pentoxide powder into vanadium dioxide (VO2) and vanadium trioxide (V2O3) powder in a hydrogen reduction furnace;

[0013] S5: grinding the composite powder prepared in S4, and then dissolving it in a sulfuric acid solution;

[0014] S6: measuring the vanadium-containing mother solution;

[0015] S7: A vanadium-containing mother solution is used as the cathode, and a sulfuric acid solution is used as the anode to electrolyze and prepare the vanadium-containing mother solution to obtain a vanadium electrolyte with a valence of +3.5 and a concentration of 1.7 mol / L.

[0016] In one embodiment, the chemical equation involved in step S2 is:

[0017]

[0018] In one embodiment, the chemical equation involved in step S3 is:

[0019]

[0020] The beneficial effects of the present invention are mainly reflected in the following aspects:

[0021] Cost-effectiveness: Using high-purity ammonium polyvanadate as raw material, high-purity vanadium pentoxide is produced at a lower cost through a high-temperature pyrolysis process. Compared with traditional high-purity vanadium and flake vanadium, it has obvious cost advantages.

[0022] Resource recycling: The tail gas generated during the pyrolysis process is converted into nitrogen and hydrogen through catalytic decomposition. These gases are then reused as protective gas and reducing gas, achieving resource recycling and reducing environmental pollution.

[0023] Simplified process flow: Compared with the traditional process, this solution has a shorter process flow, reduces production steps and improves production efficiency.

[0024] Reduced equipment requirements: Simplified process flow reduces dependence on equipment and reduces fixed asset investment.

[0025] One-step reduction technology: The present invention can reduce the powder valence state to a lower level in one step, and can produce vanadium solutions in various valence states from +3 to +4 as required.

[0026] Improved product quality: No reducing substances need to be added during the preparation of the electrolyte. The use of reducing gas will not introduce impurities into the electrolyte, which can improve the quality of the electrolyte.

[0027] Large-scale production capacity: Simplified processes and reduced equipment requirements are conducive to the large-scale production of all-vanadium electrolytes, meeting the market demand for high-performance electrolytes.

[0028] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0030] Figure 1 The present invention is a flow chart of a method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0032] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Embodiment 1

[0035] See also Figure 1 As shown, the present invention is a method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material. The method comprises the following steps:

[0036] S1: crushing and grinding the provided ammonium polyvanadate powder;

[0037] S2: transferring the ammonium polyvanadate powder to a vacuum metallurgical furnace for calcination and decomposition;

[0038] S3: crushing and grinding the produced bulk vanadium pentoxide;

[0039] S4: preparing hydrogen and nitrogen by decomposing liquid ammonia to reduce vanadium pentoxide powder into vanadium dioxide (VO2) and vanadium trioxide (V2O3) powder in a hydrogen reduction furnace;

[0040] S5: grinding the composite powder prepared in S4, and then dissolving it in a sulfuric acid solution;

[0041] S6: measuring the vanadium-containing mother solution;

[0042] S7: A vanadium-containing mother solution is used as the cathode, and a sulfuric acid solution is used as the anode to electrolyze and prepare the vanadium-containing mother solution to obtain a vanadium electrolyte with a valence of +3.5 and a concentration of 1.7 mol / L.

[0043] In one embodiment, the chemical equation involved in step S2 is:

[0044]

[0045] In one embodiment, the chemical equation involved in step S3 is:

[0046]

[0047] Embodiment 2

[0048] Take 500g of ammonium polyvanadate powder to prepare all-vanadium electrolyte as an example:

[0049] Step 1: weigh 500 g of ammonium polyvanadate powder to prepare an all-vanadium electrolyte;

[0050] Step 2: Grind the ammonium polyvanadate powder thoroughly;

[0051] Step 3: putting it into a crucible and thermally decomposing it at 550°C, and weighing and grinding the obtained vanadium pentoxide;

[0052] Step 4: placing the vanadium pentoxide powder in a hydrogen reduction furnace at 700° C. for reduction;

[0053] Step 5: The reduced powder is ground and dissolved in 5 mol / L sulfuric acid;

[0054] Step 6: Determine the concentration of +3 and +4 vanadium ions in the mother liquor, and calculate the amount of dilute sulfuric acid and electrolysis time required to adjust the sulfuric acid concentration and the vanadium ion valence to 4 mol / L and +3.5;

[0055] Step 7: Adjust the valence state of vanadium ions and the concentration of sulfuric acid in the mother liquor to obtain an all-vanadium electrolyte.

[0056] The experiment showed that the yield of 99% vanadium pentoxide prepared by pyrolysis of ammonium polyvanadate was about 87.5%, the ratio of trivalent vanadium to tetravalent vanadium in the mother liquor after 4 hours of reduction by hydrogen reduction was about 1:1.23, the conductivity of the all-vanadium electrolyte obtained by dilution electrolysis was about 210mS / cm, the energy efficiency was about 81.72% at 160mA / cm2, and the coulombic efficiency was about 96.2%.

[0057] Embodiment 3

[0058] Take 200g of ammonium polyvanadate powder to prepare all-vanadium electrolyte as an example:

[0059] Step 1: Weigh 200 g of ammonium polyvanadate powder to prepare an all-vanadium electrolyte;

[0060] Step 2: Grind the ammonium polyvanadate monohydrate powder thoroughly;

[0061] Step 3: putting it into a crucible and thermally decomposing it at 420°C, and weighing and grinding the obtained vanadium pentoxide;

[0062] Step 4: placing the vanadium pentoxide powder in a hydrogen reduction furnace at 700° C. for reduction;

[0063] Step 5: The reduced powder is ground and dissolved in 5 mol / L sulfuric acid;

[0064] Step 6: Determine the concentration of +3 and +4 vanadium ions in the mother liquor, and calculate the amount of dilute sulfuric acid and electrolysis time required to adjust the sulfuric acid concentration and the vanadium ion valence to 4 mol / L and +3.5;

[0065] Step 7: Adjust the valence state of vanadium ions and the concentration of sulfuric acid in the mother liquor to obtain an all-vanadium electrolyte.

[0066] The experiment showed that the yield of preparing 99% vanadium pentoxide by pyrolysis of ammonium polyvanadate was about 86.2%, the ratio of trivalent vanadium to tetravalent vanadium in the mother liquor after 3 hours of reduction by hydrogen reduction method was about 1:1.07, the conductivity of the all-vanadium electrolyte obtained by dilution electrolysis was about 207mS / cm, the energy efficiency was about 80.45% at 160mA / cm2, and the coulombic efficiency was about 95.3%.

[0067] Embodiment 4

[0068] Table 1 shows the experimental results obtained by the preparation method of the present invention using raw materials in different proportions;

[0069] Ammonium polyvanadate(g) Vanadium pentoxide(g) Yield (%) <![CDATA[V 3+: In 4+ ]]> Energy efficiency (%) Coulomb efficiency (%) 100.07 87.90 87.8 1:1.02 80.26 95.2 141.50 123.40 87.2 1:1.13 81.15 95.7 180.10 157.60 87.5 1.0.2:1 80.11 95.1 200.50 176.40 88.0 1:1.15 81.99 96.2 300.00 260.40 86.8 1:1.08 81.05 96.1 172.60 152.10 88.1 1:0 \ \ 272.60 237.40 87.1 0.05:1 \ \

[0070] The present invention can prepare a vanadium ion solution with a valence between +3 and +5 by changing process parameters and adjusting the ratio of trivalent vanadium to tetravalent vanadium in powder and electrolyte, and can realize the preparation of a +3.5 valence all-vanadium electrolyte by mutual deployment of high-valent and low-valent vanadium ion solutions.

[0071] The present invention optimizes cost-effectiveness by adopting high-purity ammonium polyvanadate as a raw material; its environmentally friendly tail gas treatment and resource recycling reduce environmental pollution; the simplified process flow and reduced equipment requirements improve production efficiency and reduce fixed asset investment; the one-step reduction technology simplifies the production steps and improves product quality; the chemical reaction of the entire preparation process is carefully designed to ensure high efficiency and high purity. These innovations jointly promote the large-scale production of all-vanadium electrolyte, enhance market competitiveness, and provide new possibilities for the future development of all-vanadium electrolyte technology.

[0072] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0073] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material, characterized in that: The method comprises the following steps: S1: crushing and grinding the provided ammonium polyvanadate powder; S2: transferring the ammonium polyvanadate powder to a vacuum metallurgical furnace for calcination and decomposition; S3: crushing and grinding the produced bulk vanadium pentoxide; S4: preparing hydrogen and nitrogen by decomposing liquid ammonia to reduce vanadium pentoxide powder into vanadium dioxide (VO2) and vanadium trioxide (V2O3) powder in a hydrogen reduction furnace; S5: grinding the composite powder prepared in S4, and then dissolving it in a sulfuric acid solution; S6: measuring the vanadium-containing mother solution; S7: A vanadium-containing mother solution is used as the cathode, and a sulfuric acid solution is used as the anode to electrolyze and prepare the vanadium-containing mother solution to obtain a vanadium electrolyte with a valence of +3.5 and a concentration of 1.7 mol / L.

2. The method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material according to claim 1, characterized in that: The chemical equation involved in step S2 is:

3. The method for preparing an all-vanadium electrolyte using ammonium polyvanadate as a raw material according to claim 1, characterized in that: The chemical equation involved in step S3 is:

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