Preparation method of electrolyte of all-cerium liquid flow battery and application thereof

Abstract

The application relates to a preparation method of electrolyte of a full-cerium liquid flow battery and application thereof, and belongs to the liquid flow battery field. A negative electrolyte comprises a tetravalent cerium salt, a chelating agent, a supporting electrolyte and oxygen-free deionized water; a positive electrolyte comprises a trivalent cerium salt, a dissolving agent and oxygen-free deionized water; the chelating agent is one or more of carboxylic acid substances such as citric acid, malic acid, tartaric acid, gluconic acid and succinic acid. The negative electrode is prepared by adding the carboxylic acid chelating agent and the supporting electrolyte to the tetravalent cerium salt. The obtained electrolyte reduces the introduction of other active element impurities, the addition of the carboxylic acid chelating agent improves the solubility of the cerium salt, adjusts the redox potential of the negative electrode cerium salt to be more negative, improves the voltage of the liquid flow battery composed of the trivalent cerium salt, and increases the application fields of the full-cerium liquid flow battery in new energy vehicles, photovoltaic energy storage, wind power energy storage and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a full-cerium flow battery electrolyte and application thereof, and the full-cerium flow battery electrolyte is composed of chelation of cerium salt and ligand. The full-cerium flow battery prepared by the full-cerium flow battery electrolyte is suitable for new energy vehicles, photovoltaic energy storage, wind energy storage and other fields. BACKGROUND

[0002] Flow battery technology has a wide application in the field of new energy, and its unique technical characteristics are highly compatible with the demand of new energy system. Flow battery has excellent long-time energy storage capacity, which can effectively solve the intermittency and volatility problem of renewable energy generation. Its energy storage capacity can be linearly expanded by simply increasing the volume of electrolyte, which perfectly matches the large-scale energy storage demand of clean energy such as wind and solar energy. Flow battery not only can be used as an ideal energy storage unit for clean energy systems such as photovoltaic and wind power to improve the stability and peak regulation capacity of power grid, but also can be seamlessly embedded into intelligent power grid management system. Therefore, flow battery shows unique application potential in the field of new energy technology.

[0003] At present, there is a great demand for flow battery electrolyte with simple operation, low cost and good performance in the market, and the price of cerium salt is low. The full-cerium flow battery electrolyte composed of cerium salt has simple configuration and can well meet the market demand. Full-cerium flow battery is a new type of high-efficiency and environmentally friendly energy storage flow battery which uses different valence cerium ions as positive and negative active materials. The active material of full-cerium flow battery exists in the form of ions or ion association in the electrolyte during the charging and discharging process of the battery. The positive and negative active materials of full-cerium flow battery are stored in two liquid storage tanks, and the electrolyte is pushed into the battery system from the positive and negative electrolyte pools by external force (pump) during operation. The positive and negative electrolytes undergo oxidation and reduction reactions in the independent chambers of the battery, respectively, and the electrons move directionally through the external circuit, thereby completing the process of energy storage and release. The active material of full-cerium flow battery is cerium ion, which exists in two valence states of Ce(IV) and Ce(III), and the battery stores and releases energy through the change of cerium ion valence.

[0004] Full-cerium flow battery mainly consists of battery stack, electrolyte storage tank, charging and discharging control system and other modules. The battery stack is composed of single cells connected in series, and the single cell is composed of electrodes, separators and conductive plates. The electrolyte is the core material for providing positive and negative active materials for full-cerium flow battery, which is mainly composed of positive and negative active materials, supporting electrolyte and the like. However, the oxidation and reduction potentials of Ce(IV) and Ce(III) are close, so in order to make the open circuit voltage of full-cerium flow battery reach a suitable level, a chelating agent needs to be added to adjust the oxidation and reduction potential of cerium ion. SUMMARY

[0005] The problem to be solved by the present application is to adjust the redox potential of cerium ions by a chelating agent to meet the open circuit voltage requirement, and a full cerium flow battery electrolyte preparation method and a full cerium flow battery comprising the electrolyte are provided. The present application provides a simple full cerium flow battery electrolyte preparation method without introducing other active impurities except cerium ions. The full cerium flow battery electrolyte preparation method can directly obtain a full cerium flow battery electrolyte, thereby obtaining a low-cost, high-activity, and stable performance full cerium flow battery electrolyte and battery.

[0006] A full cerium flow battery electrolyte, characterized in that: the negative electrolyte comprises tetravalent cerium salt, chelating agent, supporting electrolyte, and oxygen-free deionized water. The positive electrolyte comprises trivalent cerium salt, solubilizing agent, and oxygen-free deionized water.

[0007] The tetravalent cerium salt in the negative electrolyte is one or more of cerium sulfate and cerium nitrate.

[0008] The trivalent cerium salt is one or more of cerium carbonate and cerium chloride.

[0009] The chelating agent is one or more of carboxylic acid substances such as citric acid, malic acid, tartaric acid, gluconic acid, and succinic acid.

[0010] The supporting electrolyte is one or more of potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide.

[0011] The concentration of cerium salt in the positive electrolyte and the negative electrolyte is 0.01-1 mol / L, preferably 0.2-1.0 mol / L. The molar ratio of the selected chelating agent to cerium salt is 1-3:1, preferably 1.5:1. The concentration of the selected supporting electrolyte is 1-8 mol / L, preferably 2-5 mol / L.

[0012] The oxygen-free deionized water is ultrapure water.

[0013] Further, the solubilizing agent in the positive electrolyte is methanesulfonic acid.

[0014] The above-mentioned full cerium flow battery electrolyte preparation method, characterized in that the preparation method comprises the following steps:

[0015] 1) Negative electrode: The tetravalent cerium salt and the chelating agent are added to a reactor with stirring, deionized water is added, the supporting electrolyte is added while stirring until completely dissolved, the heating temperature is set to 20-50°C, and the volume is set after complete dissolution. The negative electrolyte is obtained after six hours of standing.

[0016] 2) Positive electrode: The trivalent cerium salt and the methanesulfonic acid are sequentially added to a reactor with stirring, deionized water is added, the heating temperature is set to 20-50°C, and the volume is set after complete dissolution. The positive electrolyte is obtained after six hours of standing.

[0017] The use temperature of the positive and negative electrolyte is 10-80 DEG C.

[0018] The preparation raw material of the electrolyte includes cerium carbonate, cerium sulfate and other cerium salts, citric acid, malic acid, tartaric acid, gluconic acid, succinic acid and other carboxylic acid chelating agents, potassium carbonate, sodium carbonate and other supporting electrolytes and methane sulfonic acid. The electrolyte prepared by using the above raw materials does not introduce other active element impurities, and the prepared all-cerium flow battery electrolyte has low cost, high conductivity efficiency and stable volt-ampere performance, greatly increasing the application field of the all-cerium flow battery.

[0019] In addition, when potassium carbonate or sodium carbonate is used to neutralize the carboxyl group in the carboxylic acid, carbon dioxide gas and water are generated in the reaction, the carbon dioxide is volatilized, and no other active impurities are introduced into the system. And the use temperature of the battery electrolyte is 10-80 DEG C.

[0020] The open circuit voltage can reach 1.05V.

[0021] The advantages of the present application are that the chelating agent is coordinated with tetravalent cerium, the oxidation-reduction potential is adjusted to be more negative, there is a suitable voltage difference with trivalent cerium, and the all-cerium flow battery can be formed. The all-cerium flow battery electrolyte configured by the method reduces the introduction of other active impurities, and the steric hindance effect of the selected carboxylic acid chelating agent is obvious, effectively reducing the cross contamination between electrolytes of different electrodes and improving the battery life. The electrolyte and the configuration method of the all-cerium flow battery provided by the present application increase the application field of the all-cerium flow battery in new energy vehicles, photovoltaic energy storage, wind power energy storage and the like. BRIEF DESCRIPTION OF DRAWINGS

[0022] The advantages and features of the present application will be more apparent from the following detailed description of specific embodiments and examples with reference to the accompanying drawings. In the drawings:

[0023] Figure 1 is a working principle diagram of the all-cerium flow battery;

[0024] Figure 2 is the cyclic voltammogram of the negative electrolyte of example 1 in 10-50 mV·s -1 ;

[0025] Figure 3 is the cyclic voltammogram of the positive electrolyte of example 1 in 10-50 mV·s -1 ;

[0026] Figure 4 is the cyclic voltammogram of the positive and negative electrolytes of example 1 in 10 mV·s -1 ;

[0027] Figure 5The results are the battery coulombic efficiency results after 40 cycles in Example 1. Detailed Implementation

[0028] The following will provide a detailed description of the preparation method of the all-cerium flow battery electrolyte according to the present invention, and the all-cerium flow battery including the electrolyte. Those skilled in the art should understand that the following detailed description is for the purpose of facilitating understanding of the present invention and is not intended to limit the scope of protection of the present invention.

[0029] Example 1

[0030] In this embodiment, cerium sulfate is selected to provide tetravalent cerium ions, cerium carbonate is selected to provide trivalent cerium ions, citric acid is selected as the chelating agent, potassium carbonate is the supporting electrolyte, and deionized water is the solvent.

[0031] The steps for preparing the negative electrode electrolyte are as follows:

[0032] Prepare 30 mL of negative electrode electrolyte. Take a 50 mL beaker and weigh out 2.43 g (0.2 mol / L) cerium sulfate tetrahydrate (Ce(SO4)2·4H2O) and 1.73 g (0.3 mol / L) citric acid. Place both into the beaker and insert a magnetic rotor. Add deionized water, seal with plastic wrap, and stir at room temperature. When the mixture is thoroughly mixed and turns orange-yellow, slowly add potassium carbonate in small amounts while stirring. This process will generate a lot of bubbles, so be careful to avoid liquid splashing. Control the stirring speed at 200–500 rpm. When the solute in the beaker is completely dissolved and the liquid is transparent and dark brown, remove the beaker from the stirrer, remove the rotor with a magnet, bring the volume to a final level, and let it stand for six hours before use.

[0033] The steps for preparing the positive electrode electrolyte are as follows:

[0034] Prepare 30 mL of positive electrolyte. Take a 50 mL beaker and weigh out 2.76 g (0.2 mol / L) cerium carbonate (Ce₂(CO₃)₃) and 2.88 g (1 mol / L) methanesulfonic acid. Place both into the beaker and insert a magnetic stirrer. Add deionized water, seal with plastic wrap, and stir at room temperature. When the solution becomes colorless and transparent, remove the beaker from the stirrer, remove the stirrer with a magnet, bring the volume to a final volume, and let it stand for six hours before use. Note that methanesulfonic acid has a high viscosity at room temperature, making it difficult to weigh. Therefore, before weighing, heat the methanesulfonic acid in an oven at 50°C for 20 minutes. Ensure proper ventilation in a fume hood and wear appropriate protective gear during weighing.

[0035] Electrochemical tests were performed on the above-mentioned positive and negative electrode electrolytes, and the results are shown in the appendix. Figure 2 Appendix Figure 3 As shown. (From the appendix) Figure 2 It can be seen that the negative electrode electrolyte is in the range of 10–50 mV·s -1The cyclic voltammetry curves at the specified scan rate exhibit good reversibility, with redox potentials around 0.33 V. (From the attached...) Figure 3 It can be seen that the positive electrode electrolyte is in the range of 10–50 mV·s -1 The cyclic voltammetry curves at the specified scan rate exhibit good reversibility, with redox potentials around 1.38 V. (From the attached...) Figure 4 It can be known that at 10mV·s -1 At the specified scan rate, the open-circuit voltage of the all-cerium redox flow battery can reach 1.05V. It is important to note that electrochemical tests should be conducted under inert gas protection to prevent electrolyte deterioration and deactivation of active materials, which would affect the accuracy of cyclic voltammetry tests.

[0036] Take 30 mL of electrolyte for both the positive and negative electrodes. Both the positive and negative electrodes are 3 × 3 cm. 2 A porous carbon felt electrode with a Nafion 212 proton exchange membrane was used. At 60 mA / cm²... 2 Charged to 1.5V at a current density of 60mA / cm 2 Discharged to 0.8V at a current density for 40 cycles. (For example...) Figure 5 As shown, the coulombic efficiency of the battery is stable at over 80%, and basically around 90%.

[0037] Example 2

[0038] In this embodiment, cerium sulfate is selected to provide tetravalent cerium ions, cerium chloride is selected to provide trivalent cerium ions, malic acid is selected as the chelating agent, sodium carbonate is the supporting electrolyte, and deionized water is the solvent.

[0039] The steps for preparing the negative electrode electrolyte are as follows:

[0040] Prepare 30 mL of negative electrode electrolyte. Take a 50 mL beaker, weigh 2.43 g (0.2 mol / L) cerium sulfate and 1.61 g (0.4 mol / L) malic acid, put them into the beaker and place a magnetic rotor inside. Add deionized water, seal with plastic wrap, stir at room temperature, and slowly add sodium carbonate in small amounts several times, controlling the stirring speed at 200-500 r / min. When the solute in the beaker is completely dissolved and the liquid is transparent, remove the beaker from the stirrer, remove the rotor with a magnet, make up the volume, and let it stand for six hours before use.

[0041] The steps for preparing the positive electrode electrolyte are as follows:

[0042] Configuration 30 mL positive electrolyte, take 50 mL beaker, 2.24 g (0.2 mol / L) of cerium carbonate, 2.88 g (1 mol / L) of methanesulfonic acid, put them into the beaker and put into the magnetic rotor, add deionized water, seal with plastic wrap, stir at room temperature. When the solution is colorless and transparent, take the beaker out of the stirrer, take out the rotor with a magnet, and use it after standing for six hours after constant volume. Note that the treatment of methanesulfonic acid in this process is the same as in Example 1.

[0043] Electrochemical measurement is performed on the above electrolyte, the steps are the same as in Example 1. It should be noted that the electrochemical test should be carried out under the protection of inert gas to prevent the electrolyte from deteriorating and the active substance from deactivating, thereby affecting the accuracy of the cyclic voltammetry test.

[0044] Take 30 mL of positive and negative electrolyte, and 3x3 cm of positive and negative electrode 2 Porous carbon felt electrode, proton membrane is Nafion 212 membrane. Charge to 1.5 V at a current density of 60 mA / cm 2 , discharge to 0.8 V at a current density of 60 mA / cm 2 , and perform 40 cycles, with CE remaining above 80%.

Claims

1. An all-cerium flow battery electrolyte, characterized by: The negative electrolyte comprises tetravalent cerium salt, chelating agent, supporting electrolyte, and oxygen-free deionized water; the positive electrolyte comprises trivalent cerium salt, dissolving agent, and oxygen-free deionized water; The chelating agent is one or more of citric acid, malic acid, tartaric acid, gluconic acid, and succinic acid; The tetravalent cerium salt is one or more of cerium sulfate and cerium nitrate; The trivalent cerium salt is one or more of cerium carbonate and cerium chloride; The supporting electrolyte is one or more of potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide; The dissolving agent in the positive electrolyte is methanesulfonic acid.

2. A full-cerium flow battery electrolyte according to claim 1, characterized in that: The concentration of the cerium salt in the positive electrolyte and the negative electrolyte is 0.01-1 mol / L; the molar ratio of the selected chelating agent to the tetravalent cerium salt is 1-3:1; and the concentration of the selected supporting electrolyte is 1-8 mol / L.

3. A full-cerium flow battery electrolyte according to claim 2, characterized in that: The concentration of the cerium salt in the positive electrolyte and the negative electrolyte is 0.2-1.0 mol / L.

4. A full-cerium flow battery electrolyte according to claim 2, characterized in that: The molar ratio of the chelating agent to the tetravalent cerium salt is 1.5:

1.

5. A full-cerium flow battery electrolyte according to claim 2, characterized in that: The concentration of the selected supporting electrolyte is 2-5 mol / L.

6. A full-cerium flow battery electrolyte according to claim 1, characterized in that: The oxygen-free deionized water is ultrapure water.

7. A full-cerium flow battery electrolyte according to claim 1, characterized in that: The use temperature of the positive and negative electrolytes is 10-80°C.

8. A full-cerium flow battery electrolyte according to claim 1, characterized in that: The open-circuit voltage reaches 1.05 V.

9. A method of preparing a full-cerium flow battery electrolyte according to any one of claims 1-8, characterized in that: The method comprises the following steps: 1) Negative electrode: the tetravalent cerium salt and the chelating agent are added to a reactor with stirring, oxygen-free deionized water is added, the supporting electrolyte is added while stirring until completely dissolved, the heating temperature is set to 20-50°C, the volume is fixed after complete dissolution, and the negative electrolyte is obtained after six hours of standing; 2) Positive electrode: the trivalent cerium salt and the methanesulfonic acid are sequentially added to a reactor with stirring, oxygen-free deionized water is added, the heating temperature is set to 20-50°C, the volume is fixed after complete dissolution, and the positive electrolyte is obtained after six hours of standing.

10. An all-cerium flow battery, characterized in that, The method comprises the following steps:

11. The all-cerium flow battery of claim 10, wherein, The method is used in the fields of new energy vehicles, photovoltaic energy storage, and wind power energy storage.

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