KR101976906B1 - Redox flow battery and Electrolyte Solution for The Same - Google Patents

Abstract

A redox flow battery and a redox flow battery. The redox flow cell comprises a first half cell having a first electrode and a first electrolyte, a second half cell having a second electrode and a second electrolyte, and an ion exchange membrane separating the first and second half cells Wherein the first electrolyte and the second electrolyte contain an electrolyte and provide a redox flow cell containing a folate type additive and an electrolyte solution for a redox flow battery.

Description

(Redox flow battery and Electrolyte Solution for the Same)

The present invention relates to a battery chemical element, and more particularly, to a redox flow cell.

Redox flow battery (RFB) is a secondary battery that can be used for long-term storage of energy by repeated charging and discharging by electrochemical reaction of electrolyte. However, unlike conventional secondary batteries, the redox flow battery is a system in which an active material dissolved in an electrolyte receives and discharges electrons, and a unit cell and an electrolyte tank which independently control a capacity and an output characteristic of the battery are formed independently of each other There is an advantage that the battery design is free and the installation space is limited.

However, it takes a long time to prepare the electrolytes of the redox-flow battery, and it is a problem to be solved that there is a limit to commercialization because the performance of the impurity-retaining problem cell is drastically reduced in the electrolyte generated during the operation of the battery .

A first object of the present invention is to provide a redox flow cell having improved durability and stability while containing an additive to improve charge / discharge efficiency.

A second problem to be solved by the present invention is to provide an electrolyte solution for a redox flow battery, which has improved durability and stability while containing an additive to improve charge / discharge efficiency.

The technical objects of the present invention are not limited to the technical matters mentioned above, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a plasma display panel including a first half-cell including a first electrode and a first electrolyte, a second half-cell opposed to the first half-cell and including a second electrode and a second electrolyte, Cell and an ion exchange membrane separating the first and second half cells, wherein the first electrolyte and the second electrolyte can provide a redox flow cell containing an electrolyte and a folate-based additive.

The electrolyte may include a redox flow cell characterized by comprising V ₂ O ₅ , V ₂ O ₃ , V ₂ O _4, and NH ₄ VO ₃ or NH ₄ VO ₃ .

And the electrolyte has a concentration of 0.5M to 5M.

The folate-based additive may be selected from the group consisting of an alkali-metal formate, an alkaline-earth-metal formate, a transitional-metal formate, an alkyl formate ), Or a mixture thereof.

The alkali-metal folate may be HCOOLi or HCOONa.

And the alkaline earth metal-metal fomate Be (HCOO) ₂ or Mg (HCOO) ₂ .

The transition metal folate may include Co (HCOO) ₂ , Cr (HCOO) ₃ or Fe (HCOO) ₃ .

The alkylfolmate may include R (HCOO), and R may be a methyl group, an ethyl group, a propyl group, or a butyl group.

The folate-based additive is contained in the electrolyte at a molar concentration of the electrolyte of 100 wt%, and the folate-based additive is contained at 0.01 wt% to 1 wt% in the electrolyte.

According to another aspect of the present invention, there is provided an electrolyte solution for a redox flow battery comprising an electrolyte and a folate-based additive contained in the electrolyte.

The electrolyte may include an electrolyte for a redox flow battery, which includes V ₂ O ₅ , V ₂ O ₃ , V ₂ O _4, and NH ₄ VO ₃ .

Wherein the electrolyte has a concentration of 0.5M to 5M.

The folate-based additive added to the electrolyte is selected from the group consisting of an alkali-metal formate, an alkaline-earth-metal formate, a transitional-metal formate, An alkyl formate, or a mixture thereof.

The alkali-metal folate may be HCOOLi or HCOONa, and the electrolytic solution for a redox-flow battery may be provided.

And the alkaline earth metal-metal folate may be Be (HCOO) ₂ or Mg (HCOO) ₂ .

Wherein the transition metal folate is Co (HCOO) ₂ , Cr (HCOO) ₃ or Fe (HCOO) ₃ .

The alkylfolmate may include R (HCOO), and R may include a methyl group, an ethyl group, a propyl group, or a butyl group.

The folate-based additive is contained in an electrolyte at a molar concentration of the electrolyte of 100 wt%, and the folate-based additive is contained in an amount of 0.01 wt% to 1 wt%. The electrolytic solution for a redox flow battery can be provided.

When the folate based additive is contained, it can prevent the precipitation of VO ₂ ⁺ (V ⁵⁺ ) of the vanadium compound in the positive electrode electrolyte even at room temperature and high temperature, .

As described above, according to the present invention, the charge / discharge efficiency of the redox-flow battery can be improved at normal temperature and high temperature by adding a folate-based additive into the electrolyte, and the charge / discharge stability and reversibility can be improved.

However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

FIG. 1 and FIG. 2 are schematic views showing a redox flow cell according to an embodiment of the present invention, and show a charging process and a discharging process, respectively.
FIGS. 3 to 4 are graphs of a voltage efficiency graph and an energy efficiency analyzed at a high temperature of a battery having an electrolyte according to Production Examples 1 to 1 of the present invention. FIG.
FIG. 5 is a graph showing the charging and discharging curve of a battery having electrolytic solution according to Production Examples 1 to 3 of the present invention, analyzed at a high temperature. FIG.
FIGS. 6 to 7 are graphs of voltage efficiency and energy efficiency analyzed at room temperature for a battery having an electrolytic solution according to Production Examples 1 to Comparative Example 1 of the present invention.
FIG. 8 is a graph showing the charging and discharging curve of a battery having electrolytic solution according to Production Example 1 to Comparative Example 1 of the present invention at room temperature.

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

The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are also provided to more fully describe the present invention to those skilled in the art. Therefore, the shape and size of the elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

Redox  Flow cell

FIG. 1 and FIG. 2 are schematic views showing a redox flow cell according to an embodiment of the present invention, and show a charging process and a discharging process, respectively.

Referring to FIGS. 1 and 2, a redox flow cell 100 includes a first half cell 40 and a second half cell 50 disposed on both sides of a separation membrane 30 as a boundary. The first electrode 10 and the first electrolyte 15 are disposed in the first half cell 40 and the second electrode 20 and the second electrolyte 25 are disposed in the second half cell 50 . The first half cell 40 and the first electrolyte reservoir 60 are connected to each other and the first electrolyte 15 can circulate between the first half cell 40 and the first electrolyte reservoir 60. The second half cell 50 and the second electrolyte 25 reservoir 70 are connected to each other and the second electrolyte 25 is circulated between the second half cell 50 and the second electrolyte reservoir 70 . Between the first half cell 40 and the first electrolyte reservoir 60 and between the second half cell 50 and the second electrolyte reservoir 70 may include a pump for circulating electrolyte.

The first electrolytic solution 15 and the second electrolytic solution 25 may be composed of electrical active materials, and the electrical active materials may include an electrolyte and a solvent. The electrolyte may include a vanadium compound as an electric active material. More specifically, the electrolyte may include one or _two of V ₂ O ₅ , V ₂ O ₃ , V ₂ O _4, and NH ₄ VO ₃ . Also, when the electrolyte is vanadium, the following reactions may occur in the first electrode 10 and the second electrode 20.

The first electrode

VO ²⁺ + H ₂ O - e ^- → VO ₂ ⁺ + 2H ⁺ (charge)

The second electrode

V ³⁺ + e ^- → V ²⁺ (charge)

In addition, the solvent may be distilled water and sulfuric acid. For example, sulfuric acid may be contained at a concentration of 1M to 3M. Also, in the electrolyte, the electrolyte may have a concentration of 0.5M to 5M. More specifically, the molar concentration means an initial molar concentration before the battery is operated.

Further, the first electrolytic solution 15 and the second electrolytic solution 25 may further contain a formiat-based additive. More specifically, as the formiat-based additive, an alkali-metal formate, an alkaline-earth-metal formate, a transitional-metal formate ), Alkyl formiates, or mixtures thereof. The alkali-metal folate may be, for example, HCOOLi, HCOONa, and the like. The alkaline earth-metal folate may be Be (HCOO) ₂ , Mg (HCOO) ₂ , and the like. The transition metal folate may be selected from the group consisting of Co (HCOO) ₂ , Cr (HCOO) ₃ , Fe (HCOO) ₃ And so on. The alkyl folate may be R (HCOO), and R may include a methyl group, an ethyl group, a propyl group, and a butyl group. However, the additives are not limited thereto, and may include metal folate. When the molar concentration of the electrolyte is 100 wt%, the folate-based additive may be contained in the electrolyte in an amount of 0.01 wt% to 1 wt%. Particularly, the performance of the redox flow cell using the vanadium electrolyte is greatly reduced at high temperature. The reason for the decrease in the performance of the redox flow cell using the vanadium electrolyte at a high temperature is that the negative active material in the charging state is recovered to the anode electrolyte reservoir in the VO ₂ ⁺ (V ⁵⁺ ) state, and a side reaction to form a vanadium precipitate occurs. The generated vanadium precipitate may precipitate in the anode electrolyte and interfere with the flow of the electrolytic solution, thereby deteriorating the performance of the battery. However, when a folate-based additive is added, precipitation of VO ₂ ⁺ (V ⁵⁺ ) of the vanadium compound in the positive electrode electrolyte is prevented even at room temperature and high temperature. As described above, the non-uniform plating of vanadium and the formation of dendrite caused by oxidation can be further suppressed, so that the charge / discharge stability and reversibility of the redox-flow battery can be improved. Also, durability can be improved.

FIGS. 3 to 4 are graphs of voltage efficiency and energy efficiency analyzed at high temperature for a battery using the electrolytic solution according to Production Examples 1 to 1 of the present invention.

Production Example 1 and Comparative Example 1 disclosed in Figs. 3 to 8 are the same, and detailed descriptions of Production Example 1 and Comparative Example 1 are shown in Fig. 3, and Figs. 4 to 8 are shown in Production Example 1 and Comparative Example 1 The description of which is omitted.

Manufacturing example  One

60.4948 g of VOSO ₄ (purity: 97%) and 90.8306 ml of H ₂ SO ₄ (purity: 50%) were added to distilled water and stirred at room temperature for 12 hours to 24 hours to prepare a V ⁴⁺ (VO ²⁺ ) do. Then, 0.05 wt% of additive HCOONa (sodium formate, purity: 99%) is added to the positive electrode electrolyte and stirred to produce a positive electrode electrolyte.

Comparative Example  One

60.4948 g of VOSO ₄ (purity: 97%) and 90.8306 ml of H ₂ SO ₄ (purity: 50%) were added to distilled water and stirred at room temperature for 12 hours to 24 hours to prepare a V ⁴⁺ (VO ²⁺ ) do.

3 to 4, the results of analyzing the voltage efficiency and the energy efficiency of each cell in a state of high temperature as a battery having the electrolytic solution according to Production Example 1 and Comparative Example 1. FIG. It is also a value obtained by dividing the discharge voltage by the average charge voltage. In addition, the vanadium anodic electrolytes can be precipitated at high temperatures by the reaction schemes 1 and 2.

Scheme 1

[VO ₂ (H ₂ O) ₃ ] ⁺ - > VO (OH) ₃ + H ₃ O

Scheme 2

2VO (OH) _{3 -} > V ₂ O ₅ .H ₃ O

When precipitates are formed, the resistance to the electrolyte is increased, which results in a reduction in the voltage efficiency. However, in the case where the additive of the present invention is contained, it is confirmed that the battery of Preparative Example 1 containing the additive as compared to Comparative Example 1 which does not include the additive controls the decrease of the voltage efficiency over the cycle of repeated charging and discharging of the same battery . In addition, it can be confirmed that Production Example 1 having excellent voltage efficiency is superior in energy efficiency to Comparative Example 1.

FIG. 5 is a graph showing a charge / discharge curve graph of a battery having an electrolyte solution according to Production Examples 1 to 1 of the present invention analyzed at a high temperature

FIG. 5A is a graph showing a first charge / discharge curve of a battery having an electrolyte according to Production Examples 1 to Comparative Example 1. FIG. 5B is an eleventh charge / discharge curve graph. 5C is a graph of the 21st charge / discharge curve. FIG. 5D is a 31st charge / discharge curve graph. FIG. 5E is a 41 < th > charge / discharge curve graph. And FIG. 5F is a 51st charge / discharge curve graph.

5A to 5F are graphs showing voltage changes with respect to operation time as a result of charge / discharge tests at a high temperature of a redox-flow battery having electrolytes according to Production Examples 1 to Comparative Example 1. At this time, the charge-discharge operation was 55 cycles at a current density, voltage conditions of 0.7V to 1.7V for 40 ℃ to 70 ℃, 40mA / ㎝ ^2.

Production Example 1 containing an additive had a shorter charge time and discharge time as a whole compared to Comparative Example 1 containing no additive.

Therefore, it can be seen that the addition of the additive to the vanadium electrolyte of the redox-flow battery can improve the charge / discharge stability even when the battery is used at a high temperature, and the capacity can be sustained.

FIGS. 6 to 7 are graphs of voltage efficiency and energy efficiency analyzed at room temperature for a battery having an electrolytic solution according to Production Examples 1 to Comparative Example 1 of the present invention.

6 to 7, the results of analyzing the voltage efficiency and the energy efficiency of each of the cells using the production example 1 and the comparative example 1 at room temperature are shown. It can be confirmed that the battery of Production Example 1 including the additive in comparison with Comparative Example 1 which does not include an additive has a higher voltage efficiency in a cycle in which the same battery is repeatedly charged and discharged. In addition, it can be confirmed that Production Example 1 having excellent voltage efficiency is superior in energy efficiency to Comparative Example 1.

FIG. 8 is a graph showing the charging and discharging curve of a battery having electrolytic solution according to Production Example 1 to Comparative Example 1 of the present invention at room temperature.

FIG. 8A is a graph showing the first charge / discharge curve of a battery provided with an electrolyte according to Production Examples 1 to 1; FIG. 8B is an eleventh charge / discharge curve graph. 8C is a graph of the 21st charge / discharge curve. 8D is a graph of the 31st charge / discharge curve. 8E is a 41 < th > charge / discharge curve graph. 8F is a 51 < th > charge / discharge curve graph.

8A to 8F are graphs showing voltage changes with respect to operation time as a result of charging / discharging tests of a redox-flow battery having electrolytes according to Production Examples 1 to Comparative Example 1 at room temperature. At this time, charge and discharge were carried out at room temperature under a voltage of 0.7 V to 1.7 V for a total of 55 cycles at a current density of 40 mA / cm ² .

Production Example 1 containing an additive had a shorter charge time and discharge time as a whole compared to Comparative Example 1 containing no additive. That is, when the vanadium electrolyte contains a folate-based additive, the side reaction of the vanadium electrolyte can be suppressed, and the charge / discharge stability can be improved and the capacity can be maintained even at room temperature and high temperature.

Claims (19)

A first half cell having a first electrode and a first electrolyte;
A second half cell facing the first half cell and including a second electrode and a second electrolyte; And
And an ion exchange membrane for separating the first and second half cells,
Wherein the first electrolyte and the second electrolyte contain an electrolyte and a folate-based additive,
Wherein the folate-based additive is selected from the group consisting of an alkali-metal formate, an alkaline-earth-metal formate, and a transitional-metal formate. One or a mixture thereof. The method according to claim 1,
Wherein the electrolyte comprises V ₂ O ₅ , V ₂ O ₃ , V ₂ O ₄ or NH ₄ VO ₃ . The method according to claim 1,
Wherein the electrolyte has a concentration of 0.5M to 5M. delete The method according to claim 1,
Wherein the alkali-metal folate comprises HCOOLi or HCOONa. The method according to claim 1,
Wherein the alkaline earth-metal folate comprises Be (HCOO) ₂ or Mg (HCOO) ₂ . The method according to claim 1,
Wherein the transition metal folate comprises Co (HCOO) ₂ , Cr (HCOO) ₃ or Fe (HCOO) ₃ . delete The method according to claim 1,
Wherein the folate based additive is contained in the electrolyte at a concentration of 0.01 wt% to 1 wt% when the molar concentration of the electrolyte is 100 wt%. Electrolyte; And
And a folate-based additive contained in the electrolyte,
Wherein the folate-based additive is selected from the group consisting of an alkali-metal formate, an alkaline-earth-metal formate, and a transitional-metal formate. One or a mixture thereof. ≪ RTI ID = 0.0 > 11. < / RTI > 11. The method of claim 10,
Wherein the electrolyte comprises V ₂ O ₅ , V ₂ O ₃ , V ₂ O ₄ or NH ₄ VO ₃ . 11. The method of claim 10,
Wherein the electrolyte has a concentration of 0.5M to 5M. delete 11. The method of claim 10,
Wherein the alkali-metal folate comprises HCOOLi or HCOONa. 11. The method of claim 10,
Wherein the alkaline earth-metal folate comprises Be (HCOO) ₂ or Mg (HCOO) ₂ . 11. The method of claim 10,
Wherein the transition metal folate comprises Co (HCOO) ₂ , Cr (HCOO) ₃ or Fe (HCOO) ₃ . delete 11. The method of claim 10,
Wherein the folate based additive is contained in an electrolyte at a concentration of 0.01 wt% to 1 wt% when the molar concentration of the electrolyte is 100 wt%. 11. The method of claim 10,
The poll-based case-mate contain an additive, the redox flow battery electrolyte, characterized in that to prevent the precipitation of the room temperature and the vanadium compound in the positive electrolyte at high temperature conditions as VO ₂ ⁺ (V ^5+).

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