A prussian blue-like additive for vanadium electrolyte and a preparation method and application thereof

Abstract

This invention relates to the field of vanadium redox flow battery electrolyte additives, and discloses a Prussian blue-like additive for vanadium electrolytes, its preparation method, and its application. The method includes the following steps: dissolving a first metal source, a second metal source, and a structural stabilizer in an acidic solution and uniformly dispersing them to obtain a uniform dispersion I; dissolving ferrocyanide and an organophosphonate in deionized water and uniformly dispersing them to obtain a uniform dispersion II; subjecting uniform dispersion II to continuous ultrasonic treatment, and adding uniform dispersion I dropwise to uniform dispersion II to obtain a Prussian blue-like precursor solution; and heat-treating the Prussian blue-like precursor solution to obtain the Prussian blue-like additive for vanadium electrolytes. Using this additive as a vanadium redox flow battery electrolyte can effectively improve the battery's discharge capacity and capacity retention.

Description

Technical Field

[0001] This invention relates to the field of additives for vanadium redox flow batteries, and particularly to a Prussian blue-like additive for vanadium electrolytes, its preparation method, and its application. Background Technology

[0002] As a highly safe and long-cycle-life energy storage technology, flow batteries are considered one of the most promising energy storage technologies at present, especially suitable for large-scale stationary energy storage scenarios such as grid peak shaving and renewable energy grid connection, and have become a key technology in the field of large-scale energy storage. However, the cost of flow batteries is still relatively high, with electrolyte costs accounting for more than 30% of the total stack cost. Therefore, improving electrolyte utilization is one of the effective strategies to reduce the operating cost of vanadium batteries.

[0003] In vanadium redox flow battery electrolyte systems, the low diffusion coefficient of vanadium ions and the imbalance of redox couple kinetics lead to continuous capacity decay. Existing additive technologies, such as inorganic acid regulators, can inhibit vanadium precipitation but exacerbate electrode corrosion; organic viscosity modifiers, due to molecular blockage of electrode pores, actually reduce ion mobility; and while metal ion additives can improve reaction kinetics, they suffer from dissolution contamination problems, and their catalytic efficiency drops significantly after 50 cycles, failing to meet long-life requirements and unable to simultaneously address the multiple challenges of ion transport, reaction kinetics, and side reaction suppression. Therefore, developing efficient and stable vanadium battery electrolyte additives to improve electrolyte utilization, discharge capacity, and electrolyte stability is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a Prussian blue-like additive for vanadium electrolytes, its preparation method and application, to solve the problems of low discharge capacity and poor stability of existing electrolytes.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention discloses a method for preparing a Prussian blue-like additive for vanadium electrolytes, comprising the following steps:

[0007] Step S1: Dissolve the first metal source, the second metal source and the structural stabilizer in an acidic solution to obtain a mixed solution one. Place the mixed solution one in an ice bath and perform uniform dispersion treatment in a cell disruptor to obtain a uniform dispersion one.

[0008] Step S2: Dissolve ferrocyanide and organophosphonate in deionized water to obtain mixed solution two. Place mixed solution two in an ice bath and perform uniform dispersion treatment in a cell disruptor to obtain uniform dispersion two.

[0009] Step S3: The second uniform dispersion is subjected to ultrasonic treatment, and the first uniform dispersion is added dropwise to the second uniform dispersion at a constant rate. After the addition is completed, a Prussian blue-like precursor solution is obtained.

[0010] Step S4: Transfer the Prussian blue-like precursor solution into a polytetrafluoroethylene liner and place it in an oven for heat treatment. After the reaction, allow it to cool naturally to room temperature to obtain a Prussian blue-like additive for vanadium electrolyte.

[0011] In one implementation, in step S1:

[0012] The mass ratio of the first metal source, the second metal source, the structural stabilizer, and the acidic solution is 1:(0.2~0.8):(0.02~0.05):(30~50).

[0013] In one implementation, in step S1:

[0014] The first metal source is selected from at least one of ferrous sulfate, ferrous chloride, ferrous oxalate, ferrous citrate, and ferrous acetylacetone;

[0015] The second metal source is selected from at least one of manganese bromide, manganese acetate, manganese nitrate solution, and vanadium(III) chloride and vanadium(III) oxalate;

[0016] The structural stabilizer is selected from at least one of ethylenediaminetetraacetic acid, sodium citrate, diethyltriaminepentaacetic acid, and hydroxyethylethylenediaminetriacetic acid;

[0017] The acidic solution is selected from at least one of hydrochloric acid solution, sulfuric acid solution, acetic acid solution and oxalic acid solution, and the concentration of the acidic solution is 0.1~0.7 mol / L.

[0018] The first metal source, ferrous metal, is used as the quantitative source, while the second metal source needs to be slightly less than the first metal source. A smaller amount of second metal source can effectively control the phase transition process of the synthesized Prussian blue-like substance, reduce the distortion energy, and ensure the structural stability of the synthesized substance. The selected structural stabilizer is a chelating agent-derived stabilizer, which can effectively achieve the function of structural stability by fixing metal ions through strong coordination and reducing vacancy defects.

[0019] In one implementation, in step S2:

[0020] The mass ratio of the ferrocyanide, the organophosphonate, and the deionized water is 1:(0.05~0.2):(30~50).

[0021] In one implementation, in step S2:

[0022] The ferrocyanide is selected from at least one of potassium ferrocyanide and sodium ferrocyanide;

[0023] The organophosphonate is selected from at least one of aminotrimethylene phosphonate, hydroxyethylidene diphosphonate, ethylenediaminetetramethylene phosphonate, and diethylenetriaminepentamethylene phosphonate.

[0024] Organophosphonates, as key components of mixed solution II, can optimize product performance through strong coordination anchoring and structural stabilization mechanisms, effectively improve the crystallinity of the prepared Prussian analogs, enhance product particle size uniformity, and reduce vacancy defect rate.

[0025] In one implementation, in steps S1 and S2:

[0026] The process conditions for uniform dispersion treatment are as follows: the power of the cell pulverizer is set to 30~50W, and the program is set to run for 3~5 seconds, stop for 2~5 seconds, run for 3~5 seconds, stop for 2~5 seconds, and repeat the cycle, with a total running time of 10~15 minutes.

[0027] Dispersion at low temperatures using a cell disruptor enhances the dispersion of substances in the mixed solution, achieving nanoscale mixing and increasing the reaction rate.

[0028] In one implementation, in step S3:

[0029] The frequency of the ultrasonic treatment is 30~60kHz;

[0030] The constant rate is 0.3~1 mL / s.

[0031] In one implementation, in step S4:

[0032] The heat treatment is performed at a temperature of 70~110℃ for 6~9 hours.

[0033] By employing a dual strategy of ultrasonic assistance and continuous titration, the mixing process is precisely controlled to generate a highly monodisperse Prussian blue analogue. Through subsequent low-temperature solvothermal reactions, the structure is reorganized, the crystallinity is improved, and the surface is engineered to obtain a Prussian blue-like product with a stable structure and uniform grains. This product is less prone to structural relaxation or collapse during the transformation of vanadium ions, and the complete lattice and larger grains provide a smoother ion diffusion channel for the transfer of vanadium ions.

[0034] Secondly, this invention discloses a Prussian blue-like additive for vanadium electrolytes, which is prepared using the preparation method of the Prussian blue-like additive for vanadium electrolytes described above.

[0035] Thirdly, this invention discloses the application of a Prussian blue-like additive for vanadium electrolytes, wherein the Prussian blue-like additive for vanadium electrolytes prepared by the above-described preparation method or the above-described Prussian blue-like additive for vanadium electrolytes is applied to an all-vanadium redox flow battery.

[0036] The beneficial effects of this invention patent are as follows:

[0037] 1. Prussian blue-like material is obtained by using ferrous iron as the first metal source and manganese / vanadium(III) as the second metal source. After nano-dispersion, it is reacted with ferrous cyanide in the presence of a structure inducer to obtain a Prussian blue-like material with uniform and precise lattice pore size. Its suitable pore size distribution can effectively block the cross-migration of water and vanadium ions while ensuring the rapid passage of water and protons, thus ensuring the shuttle and attenuation of vanadium ions in the reaction system and improving the capacity retention rate. At the same time, the modification with organophosphonates improves the structural stability and particle uniformity of the Prussian blue-like material, giving it a better acid buffering function, preventing its structural collapse and deactivation in a strong acid environment, and effectively improving its stability in the electrode reaction process of vanadium batteries.

[0038] 2. Through the synergistic effect of the second metal source manganese / vanadium(III) and the Fe-C≡N framework, highly active catalytic sites are formed on the Prussian blue-like surface. These sites greatly reduce the activation energy barrier of vanadium ion pairs, accelerate the electron transfer rate, and the bimetallic Prussian blue-like material itself has certain redox activity, which can provide additional highly reversible capacity for vanadium batteries, thereby effectively improving their discharge capacity. The highly fluffy particles generated by the cell disruptor provide a huge specific surface area, maximizing the contact area between the electrolyte and the catalytic active sites, and significantly improving the reaction interface. The combination of constant flow injection pump dripping and ultrasonic cell realizes instantaneous and uniform nucleation, creating a large number of catalytic sites. Organophosphonates, as structural stabilizers, prevent the sintering and deactivation of active sites during high-temperature heat treatment, thereby effectively improving the energy efficiency and capacity retention of Prussian blue-like material in vanadium batteries. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a method for preparing a Prussian blue-like additive for vanadium electrolytes.

[0040] Figure 2 This is a SEM image of the Prussian blue-like additive for the vanadium electrolyte prepared in Example 1. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0042] like Figure 1 As shown, a method for preparing a Prussian blue-like additive for vanadium electrolytes includes the following steps:

[0043] Step S1: Dissolve the first metal source, the second metal source, and the structural stabilizer in an acidic solution to obtain a mixed solution one. Place the mixed solution one in an ice bath and perform uniform dispersion treatment in a cell disruptor to obtain a uniform dispersion one. The first metal source is selected from ferrous sulfate, ferrous chloride, ferrous oxalate, ferrous citrate, and ferrous acetylacetone. The second metal source is selected from manganese bromide, manganese acetate, manganese nitrate solution, vanadium(III) chloride, and vanadium(III) oxalate. The structural stabilizer is selected from ethylenediaminetetraacetic acid, sodium citrate, diethyltriaminepentaacetic acid, and hydroxyethylethylenediaminetriacetic acid. The acidic solution is selected from hydrochloric acid solution, sulfuric acid solution, acetic acid solution, and oxalic acid solution, and the concentration of the acidic solution is 0.1~0.7M. The mass ratio of the first metal source, the second metal source, the structural stabilizer, and the acidic solution is 1:(0.2~0.8):(0.02~0.05):(30~50).

[0044] Step S2: Dissolve the ferrocyanide and organophosphonate in deionized water to obtain mixed solution two. Place the mixed solution two in an ice bath and perform uniform dispersion treatment in a cell disruptor to obtain uniform dispersion two. The ferrocyanide is one of potassium ferrocyanide and sodium ferrocyanide. The organophosphonate is aminotrimethylene phosphonate, hydroxyethylidene diphosphonate, ethylenediaminetetramethylidene phosphonate, and diethylenetriaminepentamethylidene phosphonate. The mass ratio of the ferrocyanide, organophosphonate, and deionized water is 1:(0.05~0.2):(30~50).

[0045] In the uniform dispersion treatment of mixed solution one and mixed solution two, the power of the cell pulverizer is set to 30~50W, and the program is set to run for 3~5s, stop for 2~5s, run for 3~5s, stop for 2~5s, repeat the cycle, and the total running time is 10~15min.

[0046] Step S3: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment, and add the uniform dispersion I to the uniform dispersion II dropwise at a constant rate using a constant flow injection pump. After the dropwise addition is completed, a Prussian blue precursor solution is obtained. The ultrasonic treatment frequency is 30~60kHz, and the constant flow injection pump is set to a constant rate of 0.3~1mL / s.

[0047] Step S4: Transfer the Prussian blue-like precursor solution into a polytetrafluoroethylene liner and place it in an oven for heat treatment. After the reaction, allow it to cool naturally to room temperature to obtain the Prussian blue-like additive for vanadium electrolyte. The heat treatment temperature is 70~110℃, and the heat treatment time is 6~9h.

[0048] Example 1: This example includes the following steps:

[0049] Step S1: Dissolve ferrous chloride, manganese nitrate, and diethyltriaminepentaacetic acid in 0.3 mol / L hydrochloric acid solution to obtain mixed solution one. Place this solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous chloride, manganese nitrate, and diethyltriaminepentaacetic acid to hydrochloric acid solution is 1:0.1:0.05:30. Dissolve sodium ferrocyanide and hydroxyethylidene diphosphonate in deionized water to obtain mixed solution two. Place this solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion two. The mass ratio of sodium ferrocyanide, hydroxyethylidene diphosphonate, and deionized water is 1:0.1:30. Set the cell disruptor power to 30W and the program to run for 3 seconds, stop for 5 seconds, run for 3 seconds, stop for 5 seconds, and repeat the cycle for a total running time of 15 minutes.

[0050] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 30 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow syringe pump at a rate of 0.3 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 110 °C for 6 h. After the reaction, allow it to cool naturally to room temperature to obtain a Prussian blue-like additive for vanadium electrolyte.

[0051] like Figure 2As shown, the Prussian blue analog prepared in Example 1 exhibits a cluster morphology. Benefiting from the presence of a bimetallic source and structural stability, it can effectively construct a stable structure and fix metal ions through strong coordination, reducing product vacancy defects and improving its structural stability in vanadium batteries. The additional introduction of organophosphonates optimizes product performance through strong coordination anchoring and structural stabilization mechanisms, effectively improving the crystallinity of the prepared Prussian blue analog, increasing product particle size uniformity, and reducing the vacancy defect rate. This effectively achieves a greater barrier effect against hydrated vanadium ions in vanadium batteries. To avoid the imbalance of active materials and capacity decay caused by the mixing of vanadium ions of different valence states, the capacity retention rate is effectively improved. Through a dual strategy of subsequent ultrasonic assistance and continuous titration, the mixing process is precisely controlled. Then, through subsequent low-temperature solvothermal reaction, the generated Prussian blue analogue is subjected to structural restructuring, crystallinity enhancement and surface engineering treatment to obtain a Prussian blue-like product with stable structure and uniform grains. It is not prone to structural relaxation or collapse during the transformation of vanadium ions. At the same time, the complete lattice and larger grains provide a smoother ion diffusion channel for the transfer of vanadium ions.

[0052] Example 2: This example includes the following steps:

[0053] Step S1: Dissolve ferrous citrate, manganese bromide, and sodium citrate in 0.1 mol / L acetic acid solution to obtain mixed solution one. Place this solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous citrate, manganese bromide, sodium citrate, and acetic acid solution is 1:0.2:0.02:50. Dissolve potassium ferrocyanide and ethylenediaminetetramethylenephosphonate in deionized water to obtain mixed solution two. Place this solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion two. The mass ratio of potassium ferrocyanide, ethylenediaminetetramethylenephosphonate, and deionized water is 1:0.05:30. Set the cell disruptor power to 50W and set the program to run for 5 seconds, stop for 5 seconds, run for 5 seconds, stop for 5 seconds, and repeat the cycle for a total running time of 10 minutes.

[0054] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 40 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow syringe pump at a rate of 0.5 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 100 °C for 7 h. After the reaction, allow it to cool naturally to room temperature to obtain a Prussian blue-like additive for vanadium electrolyte.

[0055] Example 3: This example includes the following steps:

[0056] Step S1: Dissolve ferrous acetylacetone, manganese acetate, and ethylenediaminetetraacetic acid in 0.5 mol / L sulfuric acid solution to obtain mixed solution one. Place this solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous acetylacetone, manganese acetate, ethylenediaminetetraacetic acid, and sulfuric acid solution is 1:0.8:0.08:30. Dissolve sodium ferrocyanide and aminotrimethylene phosphonate in deionized water to obtain mixed solution two. Place this solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion two. The mass ratio of sodium ferrocyanide, aminotrimethylene phosphonate, and deionized water is 1:0.2:50. Set the cell disruptor power to 40W and set the program to run for 2 seconds, stop for 2 seconds, run for 2 seconds, stop for 2 seconds, and repeat the cycle for a total running time of 15 minutes.

[0057] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 50 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow syringe pump at a rate of 0.7 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 90 °C for 8 h. After the reaction, allow it to cool naturally to room temperature to obtain a Prussian blue-like additive for vanadium electrolyte.

[0058] Example 4: This example includes the following steps:

[0059] Step S1: Dissolve ferrous sulfate, vanadium(III) chloride, and sodium citrate in 0.4 mol / L acetic acid solution to obtain mixed solution one. Place the solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous sulfate, vanadium(III) chloride, sodium citrate, and acetic acid solution is 1:0.5:0.05:30. Dissolve potassium ferrocyanide and diethylenetriaminepentamethylphosphonate in deionized water to obtain mixed solution two. Place the solution in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion two. The mass ratio of potassium ferrocyanide, diethylenetriaminepentamethylphosphonate, and deionized water is 1:0.05:50. Set the cell disruptor power to 45W and set the program to run for 2 seconds, stop for 3 seconds, run for 2 seconds, stop for 3 seconds, and repeat the cycle for a total running time of 13 minutes.

[0060] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 60 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow syringe pump at a rate of 1.0 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 80 °C for 8 h. After the reaction, allow it to cool naturally to room temperature to obtain a Prussian blue-like additive for vanadium electrolyte.

[0061] Example 5: This example includes the following steps:

[0062] Step S1: Dissolve ferrous citrate, vanadium (III) oxalate, and hydroxyethyl ethylenediamine triacetic acid in 0.7 mol / L oxalic acid solution to obtain mixed solution one. Place the mixed solution in an ice bath and disperse it evenly in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous citrate, vanadium (III) oxalate, hydroxyethyl ethylenediamine triacetic acid, and oxalic acid solution is 1:0.4:0.04:40. Dissolve sodium ferrocyanide and ethylenediaminetetramethylenephosphonate in deionized water to obtain mixed solution two. Place the mixed solution in an ice bath and disperse it evenly in a cell disruptor to obtain uniform dispersion two. The mass ratio of sodium ferrocyanide, ethylenediaminetetramethylenephosphonate, and deionized water is 1:0.2:30. Set the cell disruptor power to 35W and set the program to run for 3 seconds, stop for 4 seconds, run for 3 seconds, stop for 4 seconds, and repeat the cycle for a total running time of 15 minutes.

[0063] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 50 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow injection pump at a rate of 0.6 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 70 °C for 9 h. After the reaction, allow it to cool naturally to room temperature to obtain a Prussian blue-like additive for vanadium electrolyte.

[0064] Comparative Example 1: No second metal source added

[0065] Step S1: Dissolve ferrous chloride and diethyltriaminepentaacetic acid in 0.3 mol / L hydrochloric acid solution to obtain mixed solution one. Place it in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous chloride, diethyltriaminepentaacetic acid and hydrochloric acid solution is 1:0.05:30. Dissolve sodium ferrocyanide and hydroxyethylidene diphosphonate in deionized water to obtain mixed solution two. Place it in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion two. The mass ratio of sodium ferrocyanide, hydroxyethylidene diphosphonate and deionized water is 1:0.1:30. Set the cell disruptor power to 30W and set the program to run for 3 seconds, stop for 5 seconds, run for 3 seconds, stop for 5 seconds, and repeat the cycle for a total running time of 15 minutes.

[0066] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 30 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow syringe pump at a rate of 0.3 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 110 °C for 6 h. After the reaction, allow it to cool naturally to room temperature to obtain the Prussian blue-like additive.

[0067] Comparative Example 2: Without structure inducers and phosphates

[0068] Step S1: Dissolve ferrous chloride and manganese nitrate in 0.3 mol / L hydrochloric acid solution to obtain mixed solution one. Place it in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion one. The mass ratio of ferrous chloride, manganese nitrate and hydrochloric acid solution is 1:0.1:30. Dissolve sodium ferrocyanide in deionized water to obtain mixed solution two. Place it in an ice bath and uniformly disperse it in a cell disruptor to obtain uniform dispersion two. The mass ratio of sodium ferrocyanide and deionized water is 1:30. Set the power of the cell disruptor to 30W. Set the running program to run for 3 seconds, stop for 5 seconds, run for 3 seconds, stop for 5 seconds, and repeat the cycle for a total running time of 15 minutes.

[0069] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 30 kHz. Add the uniform dispersion I dropwise to the uniform dispersion II using a constant flow syringe pump at a rate of 0.3 mL / s. After the dropwise addition is complete, a Prussian blue-like precursor solution is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 110 °C for 6 h. After the reaction, allow it to cool naturally to room temperature to obtain the Prussian blue-like additive.

[0070] Comparative Example 3: Without a cell disruptor and constant flow pump

[0071] Step S1: Dissolve ferrous chloride, manganese nitrate, and diethyltriaminepentaacetic acid in 0.3 mol / L hydrochloric acid solution to obtain mixed solution one, wherein the mass ratio of ferrous chloride, manganese nitrate, and diethyltriaminepentaacetic acid to hydrochloric acid solution is 1:0.1:0.05:30; dissolve sodium ferrocyanide and hydroxyethylidene diphosphonate in deionized water to obtain mixed solution two, wherein the mass ratio of sodium ferrocyanide, hydroxyethylidene diphosphonate, and deionized water is 1:0.1:30.

[0072] Step S2: Place the uniform dispersion II in an ultrasonic bath for continuous ultrasonic treatment at a frequency of 30 kHz, and directly mix the uniform dispersion I and uniform dispersion II. After the mixture is dissolved, a Prussian blue-like substance is obtained. Transfer the Prussian blue-like precursor solution to a polytetrafluoroethylene liner and place it in an oven for heat treatment at 110°C for 6 hours. After the reaction, allow it to cool naturally to room temperature to obtain the Prussian blue-like additive.

[0073] Comparative Example 4:

[0074] Use blank electrolyte.

[0075] Test method: The electrolyte additives obtained in Examples 1-5 and Comparative Examples 1-3 were added to a vanadium electrolyte with a concentration of 1.7 mol / L and a valence state of 3.5, with an addition amount of 3%. For Comparative Example 4, only blank electrolyte was used for the test. Charge-discharge cycle tests were performed under the same operating conditions, and the coulombic efficiency, energy efficiency, voltage efficiency, discharge capacity, and capacity retention rate after 50 cycles were recorded.

[0076] The results of the above tests are shown in Table 1:

[0077] Table 1 Battery Performance Test Results

[0078]

[0079] As shown in Table 1, compared to Comparative Example 1, Examples 1-5 exhibited higher coulombic efficiency, voltage efficiency, and discharge capacity. This is because the introduction of the second metal can produce a synergistic effect with the Fe-C≡N framework and form highly catalytically active sites, effectively reducing the activation energy barrier of vanadium ions during the reaction, thereby effectively improving the transfer and catalysis of vanadium ions and increasing its energy efficiency. At the same time, the catalytic activity of the Prussian blue-like material itself and its reaction potential similar to that of vanadium ions also provide additional reversible capacity for the vanadium battery, thereby increasing its discharge capacity. The capacity retention rate also improved after 50 cycles, which may be due to the excellent structural stability of the prepared Prussian blue-like material and the guarantee of the shuttle of key ions in the reaction system, thus improving the capacity retention rate. From Comparative Example 2, due to the preparation process... The lack of necessary structure inducers and phosphates leads to instability and uniformity in the prepared Prussian blue-like structure, reducing its acid buffering capacity and causing structural collapse and deactivation in the vanadium battery reaction system. This results in a decrease in key factors such as energy efficiency and capacity retention. Compared to Example 3, Comparative Examples 1-5 used a constant flow injection pump and an ultrasonic cell for mixing, resulting in products with uniform particles and reaction, effectively avoiding product inhomogeneity caused by incomplete reaction. This uniform particle size and stable structure of the Prussian blue-like product can provide more transport channels for protons, significantly reduce the ohmic resistance and electrochemical polarization of the electrolyte, and stabilize the acidity of the electrode interface, providing a more stable reaction environment for the vanadium battery, thereby effectively improving its energy efficiency, discharge capacity, and capacity retention.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Use of a Prussian blue analogue additive for a vanadium electrolyte, characterized in that The vanadium electrolyte uses a prussian blue-like additive as an additive of an electrolyte in a full vanadium liquid flow battery, wherein a preparation method of the vanadium electrolyte uses a prussian blue-like additive includes the following steps: Step S1: a first metal source, a second metal source and a structure stabilizer are dissolved in an acidic solution to obtain a mixed solution one, the mixed solution one is placed in an ice bath and uniformly dispersed in a cell crusher to obtain a uniformly dispersed solution one; the mass ratio of the first metal source, the second metal source, the structure stabilizer and the acidic solution is 1:(0.2-0.8):(0.02-0.05):(30-50); the first metal source is selected from at least one of ferrous sulfate, ferrous chloride, ferrous oxalate, ferrous citrate and ferrous acetylacetone; the second metal source is selected from at least one of manganese bromide, manganese acetate, manganese nitrate solution, vanadium (III) chloride and vanadium (III) oxalate; Step S2: ferrocyanide and organic phosphonate are dissolved in deionized water to obtain a mixed solution two, the mixed solution two is placed in an ice bath and uniformly dispersed in a cell crusher to obtain a uniformly dispersed solution two; Step S3: the uniformly dispersed solution two is ultrasonically treated, and the uniformly dispersed solution one is added to the uniformly dispersed solution two at a constant rate, and a prussian blue-like precursor solution is obtained after the addition is completed; Step S4: the prussian blue-like precursor solution is transferred to a polytetrafluoroethylene liner and placed in an oven for heat treatment, and then naturally cooled to room temperature after the reaction to obtain a vanadium electrolyte prussian blue-like additive.

2. Use according to claim 1, wherein In the step S1: The structure stabilizer is selected from at least one of ethylenediaminetetraacetic acid, sodium citrate, diethylenetriaminepentaacetic acid and hydroxyethyl ethylenediamine triacetic acid; The acidic solution is selected from at least one of hydrochloric acid solution, sulfuric acid solution, acetic acid solution and oxalic acid solution, and the concentration of the acidic solution is 0.1-0.7 mol / L.

3. The use according to claim 1, wherein In the step S2: The mass ratio of the ferrocyanide, the organic phosphonate and the deionized water is 1:(0.05-0.2):(30-50).

4. The production method according to claim 1, wherein In the step S2: The ferrocyanide is selected from at least one of potassium ferrocyanide and sodium ferrocyanide; The organic phosphonate is selected from at least one of aminotri(methylene) phosphonate, hydroxyethylidene diphosphonate, ethylenediamine tetramethylene phosphonate and diethylenetriamine pentamethylene phosphonate.

5. The use according to claim 1, wherein In the step S1 and the step S2: The process conditions of the uniform dispersion treatment are that the power of the cell crusher is set to 30-50 W, the program is set to run for 3-5 s first, stop for 2-5 s, then run for 3-5 s, stop for 2-5 s, repeat the cycle, and the cumulative running time is 10-15 min.

6. The use according to claim 1, wherein In the step S3: The frequency of the ultrasonic treatment is 30-60 kHz; The constant rate is 0.3-1 mL / s.

7. The use according to claim 1, wherein the compound is ###0002### In the step S4: The temperature of the heat treatment is 70-110 DEG C, and the time is 6-9 h.

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