KR101763044B1 - Method for controlling operation of redox flow battery - Google Patents

Abstract

The present invention relates to a method of operating a redox flow cell, and more particularly, to a redox flow battery using an active material containing vanadium and an anion exchange membrane to prevent an abrupt increase in resistance value, And a method of operating the redox flow cell.

Description

METHOD FOR CONTROLLING OPERATION OF REDOX FLOW BATTERY [0001]

The present invention relates to a method of operating a redox flow cell, and more particularly, to a redox flow battery using an active material containing vanadium and an anion exchange membrane to prevent an abrupt increase in resistance value, And a method of operating the redox flow cell.

BACKGROUND ART In a secondary battery which is a high-efficiency energy storage system, a redox flow cell having high energy storage density, high output and high durability is attracting attention as a large-capacity power storage technology or an emergency power source.

A redox flow cell is an electrochemical storage device that charges or discharges electrical energy through oxidation / reduction reactions of ions contained in an electrolyte solution.

Particularly, the vanadium redox flow cell is most widely used because it has a simple electrode reaction, high electromotive force, fast electrode reaction of vanadium ion, excellent durability, and high output. Vanadium is used as an active material The redox battery used has a redox reaction of vanadium divalent (V ^{2 +} ) / 3 valence (V ^{3 +} ) in the anode and a quaternary (V ^{4 +} ) / 5 valence of vanadium ^{5 +} ) oxidation-reduction reaction.

The vanadium redox flow cell is a material that acts as a diaphragm to divide the cathode and the anode in operation. The ion exchange membrane, which is effective for the selective permeation of ions, is used as a cation exchange membrane and anion exchange membrane Can be classified.

When the anion exchange membrane is used, the surface of the diaphragm is charged with a positive electric charge so that most of the anions and hydrogen ions pass through. However, when ion clusters (aggregates of a plurality of atoms aggregated) having anions in the electrolyte are present at high concentrations, there is a problem that the particles of anions are stuck on the surface of the anion exchange membrane due to the electrical attraction and interfere with the passage of hydrogen ions. In this case, the resistance of the battery suddenly rises instantaneously, so that the battery can not perform a normal circuit and can not function as a battery.

In a system where V ^{2 +} and V ^{3 +} are contained in the catholyte and the anolyte contains V ^{4 +} and V ^{5 +} in a vanadium redox flow cell, V ^{5 +} exists in the form of some anionic charge .

The molecular form of the chemical species is determined by various factors such as temperature and pH. However, more than half of the V ^{5 +} ions in the electrolyte exists in the form of ion clusters with VO ₂ SO ₄ ^- negative charge. Therefore, when the state of charge (SOC) of the battery is high, the density of the ion cluster having a negative charge increases, which hinders the smooth reaction of the electrons on the surface of the anion exchange membrane, .

Therefore, in the case of a redox flow cell to which an anion exchange membrane is applied and a redox flow cell including various anion species in an electrolyte, it is necessary to develop a technique for preventing a battery malfunction due to an abrupt increase in resistance.

It is an object of the present invention to provide a method for controlling the resistance of a redox flow cell using an anion exchange membrane so as not to increase rapidly.

It is another object of the present invention to provide a method for controlling a smooth chemical reaction on the surface of an anion exchange membrane of a redox flow cell.

Another object of the present invention is to provide a method for lowering the battery resistance when the resistance of a redox flow cell using an anion exchange membrane is rapidly increased.

It is another object of the present invention to provide a method for ensuring continuous and stable operation of a redox flow battery without the need for interruption and re-operation for inspection.

In order to solve the above problems,

An embodiment of the present invention is a method of operating a redox flow cell comprising an anolyte, a catholyte and an anion exchange membrane, the method comprising: determining the concentration of ions contained in the anolyte and the catholyte, And the resistance of the redox flow cell is maintained at a value of 80 to 150% of the initial resistance value by adjusting the temperature of the redox flow battery.

When the concentration of the vanadium ion contained in the anolyte is V mol / L, the concentration of the sulfate ion is S mol / L, and the concentration of the chloride ion is C mol / L, the anolyte can satisfy the following formula 1 .

[Formula 1]

0? V + S + C / 2? 7, where V> 0, S> 0,

When the concentration of the vanadium ion contained in the anolyte is V mol / L, the concentration of the sulfate ion is S mol / L, and the concentration of the chloride ion is C mol / L, the anolyte satisfies the following formula 2 time,

[Formula 2]

7 < V + S + C / 2 20 wherein V > 0, S >

The temperature (A DEG C) of the redox flow cell and the charge state value (B%) of the anolyte can be adjusted as follows.

0? A? 15, 0 < B? 50,

15 < A? 30, 0 < B? 75,

30 < A < 45, 0 &lt; B &lt;

The state of charge of the anolyte can be adjusted to 75% or less.

When the concentration of vanadium contained in the anolyte and the catholyte is equal to that of each of the anolyte, the average oxidation number of the total vanadium in the anolyte and the catholyte can be adjusted to 3.25 to 3.375.

When the concentration of the anolyte and the vanadium contained in the catholyte are the same and the amount of the catholyte is 75% or less of the amount of the anolyte,

 The average oxidation number of the total vanadium in the anolyte and the catholyte can be adjusted to 3.57 to 3.65.

Further, when the concentration (vanadium / vanadium) contained in the catholyte solution is greater than the concentration of vanadium contained in the anolyte, the liquid amount L of each electrolytic solution is adjusted so that the anolyte The number of moles of vanadium can be controlled to be the same.

At this time, the concentration of vanadium in the cathode liquid may be 1 to 1.7.

Another embodiment of the present invention is a method for operating a redox flow cell comprising an anode liquid, a cathode liquid, and an anion exchange membrane, wherein the anode liquid and the cathode liquid include vanadium ions, sulfate ions and chlorine ions, When the resistance of the redox-flow battery reaches a value exceeding 150% of the initial resistance value, the temperature or the current density of the battery is adjusted so that the resistance of the redox-flow battery is 80 to 150% A redox flow cell operating method may be provided.

The temperature of the battery can be adjusted to a value of 1.1 to 2.0 times the temperature value (占 폚) at which the resistance reaches a value exceeding 150% of the initial resistance value.

The current density of the battery can be adjusted to 0.5 to 0.9 times the current density value (A / cm ² ) at the time when the resistance reaches a value exceeding 150% of the initial resistance value.

By controlling not only the concentration of the vanadium ion contained in the electrolytic solution of the redox-flow battery but also the concentration of each of the anion species and the operating temperature, it is possible to prevent the rapid increase of the resistance of the battery or lower the increased resistance.

According to the present invention as described above, there is an advantage that a sudden increase in resistance of a redox flow cell to which an anion exchange membrane is applied can be prevented in advance.

In addition, when the resistance of the redox-flow battery to which the anion-exchange membrane is applied is rapidly increased, the present invention can be shortened within a short period of time to secure long-term reliability of the battery.

Further, the present invention is advantageous in that the operation of the redox flow battery can be ensured continuously and stably without interruption or re-operation for checking the battery.

Further, the present invention is advantageous in that the battery can be smoothly operated without being limited to the thickness and material of the anion exchange membrane.

1 shows the principle of reaction in an anion exchange membrane of a redox flow cell.
2 schematically illustrates the structure of a redox flow cell according to an embodiment of the present invention.
3 is a graph showing a charged state value of an anolyte and a catholyte and a resistance according to vanadium oxidation number.
4 is a graph showing the operation of the battery according to the charged state values of the anolyte and the catholyte.
5 is a graph showing the charge / discharge performance of the battery according to the battery temperature.
6 is a graph showing the charge / discharge performance of the battery according to the operating current density.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described hereinafter. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, the present invention will be described in detail.

In general, a vanadium redox flow cell uses an ion exchange membrane or a separator as a diaphragm for separating a cathode and an anode during operation. The separator has an advantage of low cost, but it has a problem that the Coulomb effect of the battery is deteriorated because it passes through the diaphragm without ion selectivity, and the battery capacity is difficult to maintain.

Therefore, an ion exchange membrane having ion selectivity of a porous polymer is mainly used to maintain the ion balance between the anodes. The ion exchange membrane can be classified into a cation exchange membrane and an anion exchange membrane depending on the terminal functional group charge of the polymer.

In the case of cation exchange membranes, the cation is predominantly passed and the anions are only partially passed, whereas the anion exchange membranes predominantly pass the anions and some of the cations pass.

Accordingly, in the case of the vanadium redox flow cell, since the main reactant is a vanadium ion carrying a positive electric charge, the use of an anion exchange membrane is advantageous in effectively preventing passage of vanadium ions having a positive electric charge through the diaphragm.

However, as shown in FIG. 1, when an anion exchange membrane is used, a cation at the terminal of the diaphragm and an anion having a relatively large ion radius may combine with each other to cause aggregation on the membrane surface. At this time, ion clusters of relatively large size interfere with exchange of other ions, resulting in an increase in battery resistance, thereby deteriorating the operating efficiency of the battery.

Accordingly, it is an object of the present invention to provide a battery operating method capable of increasing charge / discharge efficiency and energy efficiency by controlling various anion concentrations and operating conditions in a redox flow battery using an anion exchange membrane.

According to an aspect of the present invention, there can be provided a method of operating a redox flow cell, which prevents a sudden increase in resistance of a redox flow cell to which an anion exchange membrane is applied, so as to cope with a sudden failure of a device and a drop in driving capability.

Specifically, the present invention provides a method of operating a redox flow cell comprising an anolyte, a catholyte, and an anion exchange membrane, the method comprising the steps of: determining the concentrations of ions contained in the anolyte and the catholyte, The resistance of the redox flow cell is maintained at a value of 80 to 150%, preferably 100 to 120% of the initial resistance value.

2 schematically illustrates the structure of a redox flow cell according to an embodiment of the present invention.

The electrolytic solution (anolyte and catholyte) of the redox flow cell of the present invention may contain vanadium ions. The anolyte (anode electrolytic solution) contains V ^{4 +} ion or V ^{5 +} ion as the anolyte solution, (Cathode electrolytic solution) may include V ^{2 +} ions or V ^{3 +} ions as cathode solution ions.

In addition, the anolyte and catholyte solution may use a solution containing HSO ₄ ^- , SO ₄ ^{2 -} and Cl ^- (that is, a mixed acid including sulfuric acid and hydrochloric acid) as an electrolyte for dissolving the vanadium active material.

The anolyte 110 and the catholyte 112 flow into the anode cell 102A and the cathode cell 102B of the cell 102 through the pumps 114 and 116, respectively. In the anode cell 102A, electrons move through the electrode 106 in accordance with the operation of the power source / load 118, so that a charge / discharge (oxidation / reduction) reaction of V ^{5 +} ↔ V ^{4 +} occurs .

Similarly, the negative electrode cell (102B), the power / the movement of the electron occurs through the electrode 108 in accordance with an operation of the load 118, so that V ^{2 +} ↔ V ^{3 +} charging / discharging (oxidization / reduction) reaction of This happens.

After the oxidation / reduction reaction, the anolyte and catholyte are circulated to the catholyte storage tank 110 and the catholyte storage tank 112, respectively.

Vanadium ions of tetravalent vanadium ion contained in the anolyte is a cation in the form of VO ^{2 +,} 5 vanadium ions VO ₂ ⁺ in cationic form and VO ₂ SO ₄ ^- are present in most of the anionic form.

On the other hand, the anode cell 102A and the cathode cell 102B are separated by an anion exchange membrane 104 through which ions can pass. Accordingly, ion movement, that is, crossover, may occur between the anode cell 102A and the cathode cell 102B.

That is, during the charging / discharging process of the redox flow cell, the anolyte ions (V ^{5 +} , V ^{4 +} ) of the anode cell 102A move to the cathode cell 102B and the catholyte ions V ^{2 +} , V ^{3 +} ) can move to the anode cell 102A.

In particular, the present invention relates to a method of operating a redox flow cell using an anion exchange membrane (104), wherein the concentration of ions in each electrolyte, the state of charge of the anolyte, and the temperature of the battery are controlled, So that the resistance of the redox flow cell can be maintained at a value of 80 to 150% of the initial resistance value.

Specifically, when the concentration of the vanadium ion contained in the anolyte is V mol / L, the concentration of the sulfate ion is S mol / L, and the concentration of the chloride ion is C mol / L, Can be satisfied.

[Formula 1]

0? V + S + C / 2? 7, where V> 0, S> 0,

These are for increasing the dissolution amount of the vanadium active material in the electrolytic solution, and prevent the phenomenon that the electrolytic solution hardens or precipitates, thereby increasing the battery efficiency.

Specifically, when the total molar concentration of the cationic species and the anionic species of the vanadium ion contained in the anolyte and the total of the sulfate ion and the half chloride ion is less than 0 mol / L, there are no ions capable of reacting in the anolyte, And when it exceeds 7 mol / L, there is a problem that the non-dissolved substance precipitates or the fluidity is lowered due to too dark concentration and the battery efficiency is reduced.

Particularly, when the concentration in the above range is satisfied, the battery is operated normally without being limited to the battery temperature and the charging state value in the entire battery temperature range (about 0 to 45 ° C) and the whole anolyte charging state value range (0 to 100% There is an advantage to be able to.

Therefore, by adjusting the total amount of vanadium ion, sulfate ion and half chloride ion in the anolyte within the above range, it is possible to adjust the battery resistance at a temperature, thereby optimizing the charging and discharging performance of the battery.

When the concentration of each of the ion species satisfies the following formula 2, the temperature of the redox-flow battery and the charge state of the anolyte are controlled so that the resistance of the redox-flow battery is 80 to 150% . &Lt; / RTI &gt;

 [Formula 2]

7 <V + S + C / 2? 20 where V> 0, S> 0, C?

FIG. 3 is a graph showing a difference in cell resistance according to vanadium oxidation number. Referring to FIG. 3, in case of less than 1% of charged state, the measured resistance value of the anolyte and the catholyte is about 50 mΩ. The catholyte is also measured at a similar level.

On the other hand, the anolyte exhibits a resistance value two to three times larger than that of the other cases in a state of charging more than 99% where predominantly pentavalent vanadium ions are present.

That is, in a redox flow cell using an anion exchange membrane, the resistance value is relatively increased when the charged state of the anolyte is high.

This is because when the concentration of vanadium in the anolyte is higher than that in the anolyte, the concentration of VO ₂ SO ₄ ^- The resistance of the membrane is rapidly increased due to the inhibition of the electron reaction in the exchange membrane, resulting in abnormal operation or stoppage of operation.

Therefore, in the redox-flow battery using the anion-exchange membrane, it is possible to prevent the resistance from being increased by adjusting the operating temperature according to the charging state, and normal charge-discharge can be realized.

Specifically, when the ion concentration satisfying Formula 2 is maintained, the temperature (A ° C) of the redox-flow battery and the charging state value (B%) of the anolyte can be adjusted as follows to operate the battery normally.

0? A? 15, 0 < B? 50,

15 < A? 30, 0 < B? 75,

30 < A < 45, 0 &lt; B &lt;

For example, the battery temperature can be adjusted to more than 30 ° C and less than 45 ° C under the SOC 100% condition in the fully charged state, and the battery temperature The battery can be operated by limiting the maximum value of the charge state value to 50%.

This is because the electron reaction rate and the amount of the product depending on the reaction are controlled in proportion to the operating temperature of the battery, so that it is possible to prevent the resistance from being increased by changing the temperature according to the charged state value of the anolyte.

Therefore, the present invention can be solved by reducing resistance through external conditions, which is caused by predominantly existing anion-like pentavalent vanadium in the anolyte in a redox flow cell using an anion exchange membrane.

In addition, the redox VO ₂ SO contrast within the entire vanadium ions the anolyte during operation of the flow cell ₄ ^- molar concentration of the form of vanadium ions, the concentration of the ion to maintain a 47% lower than the state, which cause to increase the resistance species itself The problem can be prevented.

Vanadium ions in the form of VO ₂ SO ₄ ^- especially in the case of the predominantly pentavalent vanadium, inhibit the electron reaction in the anion exchange membrane because many ions bind to form a relatively large ion cluster.

Accordingly, the present invention is the rail whole within the anolyte of the operation of the redox flow battery vanadium ions compared to VO ₂ SO ₄ ^- by maintaining the molar concentration of the form of vanadium ions to 47% lower than the state, electrons in the anolyte and an anion exchange membrane The reaction can be smoothly controlled to prevent the battery resistance from rising sharply.

In particular, the charged state value of the anolyte can be adjusted to 75% or less. The higher the charged state value of the anolyte, the higher the concentration of the vanadium ion is, and the battery performance may deteriorate. Adjusting to 75% or less is most desirable to prevent a sharp increase in resistance.

When the concentration of vanadium contained in the anolyte and the catholyte and the amount of each electrolyte are the same, the average oxidation number of the total vanadium in the anolyte and the catholyte can be adjusted to 3.25 to 3.375.

When the redox flow cell is fully charged (SOC 100%), the vanadium active material in the positive electrode electrolyte is V ^{5 +} , and the vanadium active material in the negative electrode electrolyte is in the V ^{2 +} state. On the contrary, when the battery is completely discharged (SOC 0%), the vanadium active material in the positive electrode electrolyte is V ^{4 +} , and the vanadium active material in the negative electrode electrolyte is V ³⁺ .

In addition, the charge value 50% of the positive electrode active material state, vanadium electrolytic solution is ⁵ V ⁺ and V ^4+, 50: to present in a proportion of 50 represents the oxidation state of +4.5, vanadium active material of the negative electrode electrolytic solution is V ^{3 +} and V ^{2 +} is present in a ratio of 50:50, indicating an oxidation number of +2.5 and an average oxidation number of +3.5.

That is, the average value of the oxidation number of the total vanadium in the anolyte and the catholyte is adjusted to 3.25 to 3.375, which means that the state of charge of the catholyte is adjusted to be larger than the value of the state of the anolyte.

In this modified redox flow cell, even when the cathode solution is 100% charged, the number of pentavalent anions contained in the anolyte solution is small and the formation rate of the ion clusters is not so large, so that the electron reaction in the anion exchange membrane can be smoothly performed.

4 is a graph showing the operation of the battery according to the charged state values of the catholyte and the anolyte.

delete

It was confirmed that the redox flow battery having the anode solution of the 100% charged state and the cathode solution of the 50% charged state shown in FIG. However, although not shown in the drawing, charging and discharging of the redox flow cell into which the anolyte filled in the 50% charged state and the catholyte filled in the 100% charged state were smoothly operated.

In FIG. 4, after 40 minutes, the battery performance was adjusted by controlling the temperature and the concentration. After about 2 hours and 20 minutes, the operation of the battery was deteriorated.

In this case, when the concentration of vanadium contained in the catholyte and the catholyte is equal to that of the anolyte and the amount of catholyte is 75% or less of the amount of the anolyte, the oxidation number of the total vanadium in the anolyte and the catholyte The average can be adjusted from 3.57 to 3.65.

Further, when the concentration (vanadium / vanadium) contained in the catholyte solution is greater than the concentration of vanadium contained in the anolyte, the liquid amount L of each electrolytic solution is adjusted so that the anolyte The molar number of vanadium can be controlled to be the same.

If the amounts of the anode solution and the vanadium active material in the cathode solution are different from each other, the efficiency of the battery capacity may be lowered because the active material of one side electrolyte does not participate in the electron reaction at this time.

At this time, the concentration of vanadium in the cathode liquid may be 1 to 1.7.

Not only the concentration of the vanadium ion contained in the anolyte is adjusted together with the concentration of the sulfuric acid and the hydrochloride ion but also the balance difference between the anolyte and the catholyte is reduced by adjusting the vanadium concentration of the catholyte to the above range, There is an effect that the resistance can be maintained more smoothly at the time of control.

Thus, by controlling not only the concentration of the vanadium ion contained in the electrolytic solution of the redox-flow battery but also the concentration of each of the anion species and the operating temperature, it is possible to prevent a rapid increase in resistance of the battery, thereby realizing smooth battery operation.

Another embodiment of the present invention is a method for operating a redox flow cell comprising an anode liquid, a cathode liquid, and an anion exchange membrane, wherein the anode liquid and the cathode liquid include vanadium ions, sulfate ions and chlorine ions, When the resistance of the redox-flow battery reaches a value exceeding 150% of the initial resistance value, the temperature or the current density of the battery is adjusted so that the resistance of the redox-flow battery is 80 to 150% The flow rate of the redox flow cell can be reduced.

This is because, in a redox flow cell using an anion exchange membrane, when the resistance of the battery is rapidly increased by blocking the surface of an excess anion paper diaphragm, the resistance of the battery is controlled to be in a normal operation state by controlling the battery temperature and current density It is a driving method which can secure the long-term reliability of the battery by lowering it to a possible value.

Specifically, the temperature of the battery may be adjusted to a value of 1.1 to 2.0 times the temperature value (占 폚) at which the resistance reaches a value exceeding 150% of the initial resistance value.

5 is a graph showing the charge / discharge performance of the battery according to the battery temperature. As shown in Fig. 5, the resistance can be lowered by regulating the temperature of the battery which does not operate smoothly due to the rapid rise of the resistance.

In particular, if the temperature is raised to 1.1 to 1.5 times higher than the temperature at which the resistance is rapidly increased, the resistance of the redox flow cell can be adjusted to a normal operation state.

For example, by adjusting the temperature of the battery, it is possible to adjust the resistance value to about 10 to 50% of the resistance value at the time when the value exceeds 150% of the initial resistance value, thereby enabling smooth operation of the battery .

Also, the current density of the battery may be adjusted to a value of 0.5 to 0.9 times the current density value (A / cm 2) at the time when the resistance reaches a value exceeding 150% of the initial resistance value.

6 is a graph showing the charge / discharge performance of the battery according to the operating current density. Referring to FIG. 6, when the operating current density is lowered, the difference in voltage across the battery becomes smaller, so that normal charging and discharging are possible.

For example, by adjusting the temperature of the battery, it is possible to operate in a normal operation state by adjusting the resistance value by about 10% to 70% of the resistance value at the time of reaching the value exceeding 150% of the initial resistance value .

As described above, according to the present invention, it is possible not only to maintain the resistance of the redox flow cell using an anion exchange membrane in a normal operation state but also to control the battery temperature and the operating current density even when the battery resistance is increased, And long-term reliability can be ensured.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the following examples.

Example  And Comparative Example

1. In order to confirm the effect of the operation method of the present invention, the resistance was measured at the point where there was no further temperature change due to thermal equilibrium in the entire battery stack and the tank satisfying the conditions shown in Table 1 below.

The concentration of each ion in the anolyte (mol / L) Anodic solution charge state value
(%) Battery temperature
(° C) Change rate of resistance value against initial resistance value (%) vanadium Hydrochloric acid Sulfuric acid Example 1 1.5 0 4.5 100 25 100 Example 2 1.5 0 4.5 100 0 120 Example 3 1.8 0 4.8 100 25 110 Example 4 2.0 2.0 4.2 75 25 130 Example 5 2.0 2.0 4.2 70 25 130 Comparative Example 1 2.0 2.0 4.2 80 10 170 Comparative Example 2 2.0 2.0 4.2 100 25 200

It can be seen that Examples 1 to 3 contain the anolyte solution in which the sum of the vanadium concentration and the sulfuric acid concentration does not reach 7 mol / L, so that the battery is operated so that the rate of change in resistance value relative to the initial resistance value is 120% .

On the other hand, in Examples 4 and 5 and Comparative Examples 1 and 2, the sum of the sum of the concentrations of vanadium and sulfuric acid and the half of the concentration of hydrochloric acid exceeds 7 molar. The embodiments can achieve a comparatively smooth operation with the rate of change of the resistance value to the initial resistance value being 130% or less by adjusting the anolyte charged state value to 75% or less at the battery temperature of 25 ° C. On the other hand, in the comparative examples, when the battery temperature is 10 ° C, the anolyte packed state value is 80% or the battery temperature is 25 ° C, the anolyte charged state value is adjusted to 100% , It is possible to efficiently operate the battery by adjusting the battery temperature and the anolyte charge state value.

That is, according to the present invention, when the concentration of each ion in the anolyte, the state of the anolyte filling state, and the battery temperature are adjusted, the redox flow battery can be operated such that the rate of change in resistance value is smaller than the initial resistance value.

2. When the resistance value already reached 150% or more of the initial resistance value, the resistance of the whole battery was measured at the temperature and current density under the conditions shown in Tables 2 and 3 below.

Current resistance value relative to initial resistance value
(%) Current battery temperature
(° C) Regulated
Battery temperature
(° C) Change rate of resistance value against initial resistance value (%) Example 6 200 25 40 110 Example 7 150 25 30 110 Example 8 200 15 25 120 Comparative Example 3 200 25 20 230

As shown in Table 2, when the temperature is raised to about 1.2 to 1.7 times the temperature at the point of time when the abnormal resistance is exhibited, it is found that the battery returns to the normal operable range. On the other hand, referring to Comparative Example 3 in which the temperature was not controlled as in the present invention, it was confirmed that the resistance value was rather high.

Current resistance value relative to initial resistance value
(%) Current density
(A / cm ² ) Regulated
Current density
(A / cm ² ) Change rate of resistance value against initial resistance value (%) Example 9 160 100 80 110 Example 10 180 100 50 110 Comparative Example 4 180 100 120 210

As shown in Table 3, when the current density is lowered at a current density of about 0.5 to 0.8 times the current density at the time of exhibiting the abnormal resistance, the resistance value is lowered and the battery operation is smooth. On the other hand, in Comparative Example 4 in which the current density was increased 1.2 times, it was confirmed that the resistance value was rather increased.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

Claims (11)

A method of operating a vanadium redox flow cell comprising an anode liquid, a cathode liquid, and an anion exchange membrane,
Wherein a resistance of the redox flow cell is maintained at a value of 80 to 150% of an initial resistance value by adjusting a concentration of ions contained in the positive electrode liquid and the negative electrode liquid, a charged state value of the positive electrode liquid and a temperature of the battery,
The charged state value of the anolyte is adjusted to 75% or less,
When the concentration of vanadium contained in the anolyte and the catholyte and the amount of each electrolyte are the same,
Wherein an average number of oxidation of all the vanadium in the anolyte and the catholyte is adjusted to 3.25 to 3.375,
A method of operating a vanadium redox flow cell.
A method of operating a vanadium redox flow cell comprising an anode liquid, a cathode liquid, and an anion exchange membrane,
Wherein the anolyte satisfies the following formula 1 when the concentration of the vanadium ion contained in the anolyte is V mol / L, the concentration of the sulfate ion is S mol / L, and the concentration of the chloride ion is C mol / L, Wherein the resistance of the redox flow cell is maintained at a value of 80 to 150% of the initial resistance value,
[Formula 1]
0? V + S + C / 2? 7, where V> 0, S> 0,
A method of operating a vanadium redox flow cell.
The method according to claim 1,
When the concentration of the vanadium ion contained in the anolyte is Vol / L, the concentration of the sulfate ion is Sol / L, and the concentration of the chloride ion is Col / L, when the anolyte satisfies the following formula 2,
[Formula 2]
7 < V + S + C / 2 20 wherein V > 0, S >
The temperature (A DEG C) of the redox flow cell and the charge state value (B%) of the anolyte are controlled as follows:
0? A? 15, 0 < B? 50,
15 < A? 30, 0 < B? 75,
30 < A < 45, 0 &lt; B &lt;
A method of operating a vanadium redox flow cell.
delete delete The method according to claim 1,
When the concentration of the anolyte and the vanadium contained in the catholyte are the same and the amount of the catholyte is 75% or less of the amount of the anolyte,
Wherein an average oxidation number of the total vanadium in the anolyte and the catholyte is adjusted to 3.57 to 3.65,
A method of operating a vanadium redox flow cell.
delete delete A method for operating a vanadium redox flow cell comprising an anolyte, a catholyte and an anion exchange membrane, wherein the anolyte and the catholyte comprise vanadium ions, sulfate ions and chlorine ions,
When the resistance of the redox flow cell reaches a value exceeding 150% of the initial resistance value,
The temperature or the current density of the battery is adjusted to adjust the resistance of the redox flow battery to a value of 80 to 150% of the initial resistance value,
The temperature of the battery is adjusted to a value of 1.1 to 2.0 times the temperature value (占 폚) at the time when the resistance reaches a value exceeding 150% of the initial resistance value.
A method of operating a vanadium redox flow cell.
delete 10. The method of claim 9,
Wherein the current density of the battery is adjusted to a value of 0.5 to 0.9 times a current density value (A / cm &lt; ² &gt;) at the time when the resistance reaches a value exceeding 150%
A method of operating a vanadium redox flow cell.

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