KR20210079991A - Method for producing electrolyte for redox flow battery using additive containing amide functional group - Google Patents

Abstract

The present invention relates to a method for preparing an electrolyte for a redox flow battery using an additive comprising an amide functional group, and relates to a vanadium redox flow battery which uses and applies an additive comprising an amide functional group, a stabilizer of metal ions, in order to suppress precipitation of a positive electrode electrolyte according to temperature rise. The redox flow battery effectively suppresses or delays precipitation of vanadium which is generated when the redox flow battery is driven, so that capacity of the battery is increased and high energy density is ensured, while increasing lifespan and thus being used for various electronic devices.

Description

A method for producing an electrolyte for a redox flow battery using an additive containing an amide functional group {Method for producing electrolyte for redox flow battery using additive containing amide functional group}

The present invention relates to a method for preparing an electrolyte for a redox flow battery, and more particularly, to a method for preparing an electrolyte for a redox flow battery using an additive including an amide functional group.

As the use of fossil fuels is restricted due to environmental pollution problems, the proportion of development of new and renewable energy is increasing recently. Accordingly, it is inevitable to develop a power storage device in order to overcome the problem of inconsistency between the variability of renewable energy power production and the timing of supply and demand.

Secondary batteries for large-capacity power storage include lead-acid batteries, NaS batteries, and redox flow batteries (RFBs).

Although lead-acid batteries are widely used commercially compared to other batteries, they have disadvantages such as low efficiency, maintenance cost due to periodic replacement, and disposal of industrial waste generated during battery replacement.

In the case of a NaS battery, the advantage of high energy efficiency is that it operates at a high temperature of 300°C or more.

On the other hand, the redox flow battery has the advantages of low maintenance cost, operable at room temperature, and the ability to independently design capacity and output.

Transition metal materials that can be used as an active material of the redox flow battery include V, Fe, Cr, Cu, Ti and Sn, and in addition, transition metals having various oxidation values. The electrolyte of the initial flow battery used an Fe/Cr-based electrolyte, but problems of shortening the life of the flow battery and lowering the efficiency have occurred due to the reversibility of the Cr half battery and the crossover through the separator.

Among them, in the all-vanadium-based redox flow battery, vanadium ions are used in both the positive electrolyte and the negative electrolyte, and the vanadium ions used here are V(II), V(III), VO ₂ ⁺ (IV), VO ₂ ⁺ (V) and the like, oxidation/reduction is possible. In addition, the all-vanadium-based redox flow battery not only has a faster electrode reaction rate than the Fe/Cr-based redox flow battery, but also improves the battery capacity due to the effect of high electromotive force and solubility. As a material, it has the advantage that it can be divided into positive and negative electrodes again. Chemical formula 1 of the all-vanadium-based redox flow battery is as follows.

[Formula 1]

Negative electrode: V ³⁺ + e- ↔ V ²⁺

E = -0.26 V

Positive electrode: VO ₂ ⁺ + H ₂ O ↔ VO ₂ ⁺ + 2H+ + e-

E = 1.00 V

Cell reaction: V ³⁺ + VO ₂ ⁺ + H ₂ O ↔ V ²⁺ + VO ₂ ⁺ + 2H ⁺

E = 1.26 V

Materials that can be used as the vanadium compound include VCl ₃ , V ₂ O ₅ , and VOSO ₄ . However _{, in the case of VCl 3} , there is a problem in that the compound reacts with the electrolyte to generate chlorine gas, and in _{the case of V 2} O ₅ , there is a problem in that the capacity is small due to low solubility. So, VOSO ₄ is currently being used a lot.

VOSO ₄ is dissolved in sulfuric acid and used. At this time, the oxidation number of vanadium ions, which is the positive electrolyte, is made in a tetravalent state. Vanadium tetravalent is used in the anode electrolyte, and the electrolyte made trivalent through electrolytic reduction is used as the cathode electrolyte.

However, in the all-vanadium-based electrolyte, charge-discharge proceeds, and precipitation occurs as the temperature of the electrolyte increases. Depending on the vanadium concentration, sulfuric acid concentration, and operating temperature, red vanadium pentoxide (V ₂ O ₅ ) precipitates lower the capacity of the redox flow battery, and reduce the reaction sites where the precipitate attaches to the surface of the electrode and causes oxidation/reduction. There is a problem in that resistance increases and efficiency decreases.

Methods for suppressing such precipitation include a method of lowering the charging voltage to operate within a range in which pentavalent vanadium is not generated, a method of controlling the concentrations of vanadium and sulfuric acid, and the like.

However, when the charging voltage is lowered, the output and capacity of the battery are lowered, and when it is necessary to control the concentration of vanadium and sulfuric acid, equipment for adjusting the concentration is emphasized as a disadvantage.

Therefore, in order to improve the vanadium precipitate and the problems caused by it, research has been conducted in various fields. However, the conventional techniques have a problem in that they cannot satisfactorily improve precipitation efficiency (time delay), battery efficiency, and capacity degradation prevention at the same time.

Registered Patent Publication No. 10-1600141 (2016.03.04. Announcement)

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a method for preparing an electrolyte for a redox flow battery using an additive containing an amide functional group having a high energy density by reliably suppressing the precipitation of vanadium by adding an additive. have.

In order to achieve the above object, the present invention provides a redox flow battery that does not reduce efficiency and capacity by suppressing precipitation of a vanadium-based redox flow battery by using an additive including an amide functional group.

A redox flow battery according to the present invention includes a positive electrode cell comprising a positive electrode and a positive electrode electrolyte; a negative electrode cell comprising a negative electrode and a negative electrolyte; an ion exchange membrane positioned between the anode cell and the cathode cell; and a cathode electrolyte tank in which a cathode electrolyte for supplying anode electrolyte to the anode cell by driving a pump is stored, and a cathode electrolyte tank in which a cathode electrolyte for supplying a cathode electrolyte to the cathode cell by driving a pump is stored. - Discharge takes place.

And the additive (stabilizer) may be formamide (Formamide).

According to the present invention, the redox flow battery suppresses the deposition of vanadium on the electrode surface by adding an additive containing an amide functional group or delays the deposition time, thereby exhibiting improved efficiency and capacity compared to the conventional battery, and the battery life has the effect of increasing

1 is a graph showing the state of an active material using a cyclic voltammetry at a high temperature of an electrolyte according to an embodiment and a comparative example.
2 is a graph showing redox ratios at high temperatures of electrolytes according to Examples and Comparative Examples.
3 is a photograph showing the color change of the electrolyte according to the time of vananium pentavalent according to the change of the type of stabilizer in the electrolyte according to Examples and Comparative Examples.
4 is a graph showing a state in which a battery test was performed by injecting a stabilizer in the electrolyte solution according to Examples and Comparative Examples.

It should be noted that, in the following description, only parts necessary for understanding the embodiments of the present invention are described, and descriptions of other parts will be omitted without departing from the gist of the present invention.

The terms or words used in the present specification and claims described below should not be construed as being limited to their ordinary or dictionary meanings, and the inventors have appropriate concepts of terms in order to best describe their inventions. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents that can be substituted for them at the time of the present application It should be understood that there may be variations and variations.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

The present invention provides a redox flow battery that does not reduce efficiency and capacity by suppressing precipitation of a vanadium-based redox flow battery by using an additive including an amide functional group.

A redox flow battery according to the present invention includes a positive electrode cell comprising a positive electrode and a positive electrode electrolyte; a negative electrode cell comprising a negative electrode and a negative electrolyte; an ion exchange membrane positioned between the anode cell and the cathode cell; and a cathode electrolyte tank in which a cathode electrolyte for supplying anode electrolyte to the anode cell by driving a pump is stored, and a cathode electrolyte tank in which a cathode electrolyte for supplying a cathode electrolyte to the cathode cell by driving a pump is stored. - Discharge takes place.

In order to confirm the electrochemical properties of the electrolyte prepared by the manufacturing method of the present invention as described above, electrolytes according to Comparative Examples and Examples were prepared and the following electrochemical properties were evaluated.

1 is a graph showing the state of an active material using a cyclic voltammetry at a high temperature of an electrolyte according to an embodiment and a comparative example.

2 is a graph showing the oxidation-reduction ratio at a high temperature of the electrolyte according to Examples and Comparative Examples.

3 is a photograph showing the color change of the electrolyte according to the time of vananium pentavalent according to the change of the type of stabilizer in the electrolyte according to Examples and Comparative Examples.

4 is a graph showing a state in which a battery test was performed by injecting a stabilizer in the electrolyte solution according to Examples and Comparative Examples.

1 to 4 , it can be confirmed that formamide is the most effective stabilizer among the stabilizers included in the electrolyte.

On the other hand, the embodiments disclosed in the present specification and drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims (2)

A method for preparing an electrolyte for a redox flow battery using an additive containing an amide functional group. The method of claim 1, wherein the additive is formamide.

Images