KR101609913B1 - Carbon felt electrode for redox flow battery and method for preparing the same - Google Patents

Abstract

The present invention provides a method for manufacturing a carbon felt electrode for redox flow cells, comprising an electrode activation step of introducing an oxygen-containing functional group into a carbon felt using a mixture of strong acid and an oxidation promoter.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to carbon felt electrodes for redox flow cells,

The present invention relates to a carbon felt electrode for a redox-flow battery and a method of manufacturing the carbon felt electrode.

Studies on redox flow cells are mainly focused on electrode modification, development of ion exchange membranes, and fabrication of large capacity stacks.

Carbon felt, which is a material mainly used as an electrode of a commercial redox flow cell, has a large resistivity value due to a low response surface area and low affinity with an electrolyte despite its versatility, It acts as a cause of lowering.

To solve these problems, attempts have been made to modify the electrode surface through acid treatment or heat treatment, or to improve the electrical conductivity of the electrode by adding Pt, Pd, Ir, Au, or CNT to the electrode. However, in the case of conventional acid treatment, the surface treatment time is long and the surface treatment efficiency is not high in order to achieve an appropriate level of energy efficiency. Compared to acid treatment, the heat treatment method has a relatively high surface treatment efficiency and is known to be able to lower the activation resistance of the electrode more effectively than the acid treatment method. However, since the heat treatment must be performed at a high temperature ranging from 300 ° C. to 500 ° C., And it has a disadvantage in that it is not efficient to perform large-capacity processing. The method of adding the last-mentioned additive to the electrode can be performed by a metal deposition method for improving the conductivity of the electrode. However, since expensive materials must be used, there is a disadvantage that high cost is incurred.

One embodiment of the present invention provides a carbon felt electrode that is made by treating carbon felt for a short time with a low cost material using low energy and lowering the resistivity value.

Another embodiment of the present invention provides a redox flow cell having improved energy efficiency by applying the carbon felt electrode.

In one embodiment of the present invention, there is provided a method of manufacturing a carbon felt electrode for a redox flow cell comprising an electrode activation step of introducing an oxygen-containing functional group into a carbon felt using a mixture of a strong acid and an oxidation promoter.

The strong acid may be used as a mixed acid containing sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid hydrochloride, hydroiodic acid, perchloric acid or hydrofluoric acid, or a combination of two or more thereof.

The oxidation promoter may include at least one selected from the group consisting of potassium permanganate, potassium chlorate, and combinations thereof.

The electrode activation step may be performed at 35 ° C to 50 ° C.

The electrode activation step

(a) placing a carbon felt in a reaction vessel;

(b) adding a mixed solution containing the strong acid and the oxidation promoter to a reaction vessel containing the carbon felt; And

(c) rotating the carbon felt immersed in the mixed solution to uniformly react;

. ≪ / RTI >

Wherein the carbon felt has a rectangular sheet shape, the reaction container has a cylindrical shape with an open top, a diameter of a circular bottom surface of the reaction container is equal to either a transverse length or a longitudinal length of the carbon felt, And may be 0.8 to 1.2 times the length or the length.

The method of manufacturing a carbon felt electrode for a redox-flow battery may further include the step of intercalating water in the carbon felt by infiltrating the carbon felt containing the oxygen-containing functional group after the electrode activation step.

The step of intercalating water in the carbon felt

Adding water to the mixture while the carbon felt containing the oxygen-containing functional group is immersed; And

Lt; 0 > C to 120 < 0 > C.

In another embodiment of the present invention, there is provided a carbon felt electrode for a redox flow cell comprising an oxygen containing functional group and having an oxygen atom content of 5 to 20 atomic%.

The oxygen-containing functional group may include at least one selected from the group consisting of a hydroxyl group, a ketone group having 2 to 5 carbon atoms, an aldehyde group, an ester group having 2 to 5 carbon atoms, a carboxyl group, and combinations thereof.

In another embodiment of the present invention, there is provided a carbon felt electrode for a redox flow cell produced by the above method.

The carbon felt electrode for the redox-flow battery comprises an oxygen-containing functional group and may have an oxygen atom content of 5 to 20 atomic%.

The carbon felt electrode for the redox-flow battery has a high electrochemically activatability, a low resistivity value, and enhances the energy efficiency of the redox-flow battery.

1 is a flow chart of a method of manufacturing a carbon felt electrode for a redox flow battery according to an embodiment of the present invention.
2 is a schematic view showing a step of performing a method of manufacturing a carbon felt electrode for a redox flow battery according to another embodiment of the present invention.
3-5 are scanning electron microscope (SEM) images of the surfaces of carbon felt electrodes prepared in Examples 1-3.
FIG. 6-7 is a scanning electron microscope (SEM) image of the surface of the carbon felt electrode prepared in Comparative Example 1-2. FIG.
8-12 are graphs of EDS analysis results for Example 1-3 and Comparative Example 1-2, respectively.
13 is a graph showing CV (cyclic voltammetry) evaluation performed on the carbon felt electrode manufactured in Example 1-3 and Comparative Example 1-2.
14 is a graph showing the results of charging and discharging tests of a vanadium redox flow cell to which the carbon felt electrodes prepared in Examples 1-3 and 1-2 were applied.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

In one embodiment of the present invention, there is provided a carbon felt electrode for a redox flow cell comprising an oxygen-containing functional group and having an oxygen atom content of 5 to 20 atomic%.

The redox flow cell stores the chemical energy of the active material supplied in the form of an aqueous solution directly as electrical energy through oxidation and reduction. Such redox flow cells have advantages of low initial installation cost, large capacity, and long life. The electrode of the redox flow cell is used to form an electric field in the dielectric or to induce a current in the system. The electrode of the redox flow cell affects the oxidation and reduction reactions occurring on the electrode surface due to the electric activity of the electrode, It is an important factor.

The carbon felt electrode for the redox-flow battery is manufactured by treating carbon felt so that the electrochemically activatability is high, and the redox flow battery using the carbon felt electrode is more energy efficient.

The carbon felt electrode for a redox flow battery has an oxygen-containing functional group introduced at a high oxygen content of 5 to 20 atomic%, exhibiting a high electrical activity characteristic and exhibiting a low resistivity characteristic. Therefore, Redox flow batteries (RFB) are excellent in energy efficiency.

The carbon felt, which is not electrochemically activated, has a relatively small surface area at which redox reaction occurs during operation of the redox flow cell when used as a redox flow cell electrode, has a low affinity with the electrolyte and a large resistivity value, The carbon felt electrode having high electrochemically activity as described above may be introduced with a high content of oxygen-containing functional groups to lower the resistivity value, thereby reducing the energy efficiency of the redox flow cell. It can contribute to height.

The improved energy efficiency of the redox flow battery has the advantage of reducing the size of the redox flow battery system and thus reducing costs.

Further, as the energy efficiency of the redox flow cell improves, higher power can be produced at the same size, thereby reducing the number of required stacks in the redox flow battery system, reducing the size thereof, Thereby reducing the material cost of components of the redox flow cell.

A carbon felt electrode containing an oxygen-containing functional group such that the oxygen content is in a high content of 5 to 20 atomic% can be produced by a method for producing a carbon felt electrode for a redox flow battery described below.

Specifically, the oxygen-containing functional group may include at least one selected from the group consisting of a hydroxyl group, a ketone group having 2 to 5 carbon atoms, an aldehyde group, an ester group having 2 to 5 carbon atoms, a carboxyl group, and combinations thereof .

In another embodiment of the present invention, there is provided a method of manufacturing a carbon felt electrode for a redox flow cell comprising an electrode activation step of introducing an oxygen-containing functional group into a carbon felt using a mixture of strong acid and an oxidation promoter.

The method for producing the carbon felt electrode for a redox-flow battery can improve acid treatment efficiency by using a strong acid and an oxidation promoter together. In addition, since the strong acid solution and the oxidation promoter are inexpensive in terms of cost, the reaction can proceed at a low temperature as compared with a method of introducing an oxygen-containing functional group by heat treatment, and the manufacturing method of the carbon felt electrode for a redox- Since the treatment efficiency is excellent, the acid treatment time can be shortened and the productivity can further be improved. Accordingly, the manufacturing method of the carbon felt electrode for redox flow battery is an economical method which is very advantageous in terms of energy consumption.

The method for producing the carbon felt electrode for a redox-flow battery uses a strong acid as a solution phase and a felt is immersed therein, so that a reaction for introducing an oxygen-containing functional group into a carbon felt occurs in the solution. The carbon felt electrode for a redox flow battery is suitable for uniformly advancing the oxidation of the carbon felt because the reaction proceeds in a solution state, and thus the carbon felt electrode product thus produced has excellent quality and uniformity can do.

The method for producing the carbon felt electrode for a redox-flow battery is excellent in acid treatment efficiency by using a strong acid and an oxidation promoting agent together, so that the oxygen-containing functional group can be introduced into the carbon felt in a high content as described above. As described above, the carbon felt electrode containing a high content of oxygen-containing functional groups has a low specific resistance and thus can increase the energy efficiency of the redox flow cell.

As described above, the oxidation promoter enhances the efficiency of oxidation of the carbon felt by assisting the strong acid, that is, the oxidation efficiency.

The oxidation promoting agent may include at least one selected from the group consisting of, for example, potassium permanganate, potassium chlorate, and combinations thereof.

1 is a flow chart of a method of manufacturing a carbon felt electrode for a redox flow battery according to an embodiment of the present invention.

(A) placing carbon felt in a reaction vessel (step S10 in FIG. 1); (b) mixing a reaction vessel containing the carbon felt with the strong acid and the oxidation promoter in a reaction vessel, (S20 in Fig. 1) and (c) rotating the carbon felt immersed in the mixed solution to uniformly react (S30 in Fig. 1).

The strong acid may be used alone, or may be used as a mixed acid containing two or more of them, such as sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid hydrochloride, hydroiodic acid, perchloric acid or hydrofluoric acid.

When the aqueous strong acid solution is used as the mixed acid, it is possible to introduce more functional groups than in the case of using the acid alone. As the number of functional groups that can be introduced increases, it may contribute to enhancement of the oxidizing ability, but the oxidizing ability is not determined only by this.

The strong acid may be used in the form of a strong acid aqueous solution, and the concentration of the strong acid aqueous solution may be appropriately adjusted to obtain the optimum oxidation efficiency.

The acid treatment with the strong acid and the oxidizing accelerator may be performed at a temperature lower than the temperature during the acid treatment by the heat treatment performed at about 300 ° C to about 500 ° C. In the present invention, acid treatment of the carbon felt with the strong acid and the oxidizing accelerator is possible even if it is carried out at a low temperature of 30 DEG C or less. The higher the acid treatment temperature, the higher the oxidation efficiency. However, at too high a temperature, the oxidation reaction proceeds rapidly and it is difficult to control the acid treatment process. Therefore, it is preferable that the temperature is below the controllable limit. Considering the oxidation efficiency and the process control aspect, the carbon felt electrode for redox flow battery may be manufactured at a temperature ranging from 35 ° C to 50 ° C.

The carbon felt can be cut and used to have a rectangular shape. The carbon felt can be completely immersed in a mixed solution of a strong acid and an oxidation promoting agent so that the oxidation reaction can occur uniformly throughout the entire rectangular sheet. State, and a reaction vessel designed not to float on the surface of a mixed solution of a strong acid and an oxidation promoting agent can be used.

For example, the reaction vessel may have a cylindrical shape with an open upper part, and the diameter of the circular bottom surface of the reaction vessel may be the same as either the transverse length or the longitudinal length of the carbon felt, 0.8 to 1.2. In the reaction vessel having the above-mentioned shape, a rectangular sheet of carbon felt was immersed so as to be aligned with the diameter of the round bottom surface of the reaction vessel containing a mixture of the strong acid and the oxidation promoting agent, So that the carbon felt of the rectangular sheet can be rotated around the axis. In order to be able to rotate in this way, the diameter of the circular cross section of the cylindrical shape of the reaction container may be formed to a length or length of the rectangular sheet of carbon felt plus the margin required for the above-described rotation.

FIG. 2 is a schematic view showing a step of performing a method of manufacturing a carbon felt electrode for a redox flow cell using the reaction vessel designed as described above.

2 (a), first, a carbon felt is inserted into a diameter (W) of a circular cross section of a cylindrical reaction container so as to be aligned with the length (w) of one side of either the width or the length of the rectangular sheet, Strong acid and oxidation promoter are added in b). The carbon felt is rotated, and the oxidation reaction can be made more uniform and efficient by stirring. The method of rotating the carbon felt is not limited. For example, the magnetic stirring rod used in Fig. 2 can be used.

The carbon felt electrode manufactured by making the oxidation reaction of the carbon felt more uniformly by designing the reaction vessel performing the method of manufacturing the carbon felt electrode for the redox-flow battery can include the oxygen-containing functional groups so as to be more uniformly distributed .

When the carbon felt electrode is treated with a strong acid and an oxidation promoter, the carbon felt is oxidized to form fine pores on the surface of the fibrous particles constituting the carbon felt having a smooth surface, and the surface roughness is increased.

Therefore, the carbon felt electrode for the redox-flow battery may have an increased surface roughness compared to untreated carbon felt.

As the surface roughness of the carbon felt electrode for the redox-flowable battery increases, the reaction surface area for redox reaction during operation of the redox flow cell may increase. The carbon felt electrode can be electrochemically activated by increasing the reaction surface area of the carbon felt electrode for redox flow battery.

Wherein the carbon felt electrode for a redox flow battery further comprises an oxygen-containing functional group introduced after the electrode activating step to penetrate the carbon felt containing oxygen-containing functional groups so that the carbon felt penetrates into the carbon felt Intercalated to broaden the electrochemically effective reaction surface area.

In the flow chart of FIG. 1, steps S10, S20, and S30 may be performed, followed by step S40 of adding water to the reaction vessel.

Since the carbon felt has fine pores inside thereof due to the nature of the felt material, when the electrode is used as an electrode of the redox flow cell, the electrolyte penetrates into the pores and electrochemical reaction of the battery occurs not only on the surface but also inside the carbon felt.

When the carbon felt containing the oxygen-containing functional group is infiltrated, water is intercalated into the fine pores and water is poured into the pores, and the pores are further widened. As a result, the accessibility of the electrolytic solution is further increased, and as a result, the effective reaction surface area in which the electrochemical reaction inside the carbon felt can occur can be increased. An increase in the effective reaction surface area at which the electrochemical reaction inside the carbon felt can take place means that the electrochemical activity of the electrode is improved.

The step of intercalating water in the carbon felt may include: adding water to the mixture while the carbon felt containing the oxygen-containing functional group is immersed; And raising the temperature to a temperature of 80 ° C to 120 ° C.

Intercalation of the water can be performed more easily by performing the step of intercalating the water in a temperature range of 80 ° C to 120 ° C.

In another embodiment of the present invention, there is provided a carbon felt electrode for a redox-flow battery manufactured according to the above-described method.

The carbon felt electrode for the redox-flow battery thus prepared contains an oxygen-containing functional group and has an oxygen atom content of 5 to 20 atomic%, and a detailed description thereof is as described above.

Hereinafter, specific embodiments of the present invention will be described. It should be noted, however, that the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

( Example )

Example  One:

Untreated carbon felt (manufactured by SGL GROUP) was prepared. 30 mL of sulfuric acid (H ₂ SO ₄ , OCI Co. Ltd) was added to a reaction vessel containing carbon felt under stirring conditions at a temperature of 500 rpm and 3.6 g of potassium permanganate (KMnO ₄ , Sigma-Aldrich) The reaction was carried out at 35 ° C for 2 hours.

To remove excess potassium permanganate, add 6 mL of hydrogen peroxide (H ₂ O ₂ , Junsei) to 150 mL of DI water, add the solution, stir at 500 rpm for 30 minutes at 100 ° C, To prepare a carbon felt electrode according to Example 1, which was electrochemically activated.

Example  2

Untreated carbon felt was prepared. 0.66 mL of nitric acid (HNO ₃ , DC chemical Co. Ltd) was added to 30 mL of sulfuric acid (H ₂ SO ₄ , DC chemical Co. Ltd) under stirring conditions at a temperature of 500 rpm in a reaction vessel containing carbon felt , 3.6 g of potassium permanganate (KMnO ₄ , Sigma-Aldrich) was added slowly, and the mixture was allowed to react at 35 ° C for 2 hours.

To remove excess potassium permanganate, add 6 mL of hydrogen peroxide (H ₂ O ₂ , Junsei) to 150 mL of DI water, add the solution, stir at 500 rpm for 30 minutes at 100 ° C, To prepare a carbon felt electrode according to Example 2, which was electrochemically activated.

Example  3

Untreated carbon felt was prepared. 0.66 mL of nitric acid (HNO ₃ , DC chemical Co. Ltd) was added to 30 mL of sulfuric acid (H ₂ SO ₄ , DC chemical Co. Ltd) under stirring conditions at a temperature of 500 rpm in a reaction vessel containing carbon felt , 3.6 g of potassium permanganate (KMnO ₄ , Sigma-Aldrich) was added slowly, and the mixture was allowed to react at 35 ° C for 2 hours.

Then, the solution and the felt were slowly added to 60 mL of DI water, and then the temperature was raised to 100 DEG C and the mixture was stirred at 500 rpm for 30 minutes.

To remove excess potassium permanganate, add 6 mL of hydrogen peroxide (H ₂ O ₂ , Junsei) to 150 mL of DI water, add the solution, stir at 500 rpm for 30 minutes at 100 ° C, To prepare a carbon felt electrode according to Example 3, which was electrochemically activated.

Comparative Example  One

The untreated carbon felt was prepared as a carbon felt electrode.

Comparative Example  2

Untreated carbon felt was prepared. 200 mL of sulfuric acid (H ₂ SO ₄ , DC chemical Co. Ltd) was added to a reaction vessel containing carbon felt under a condition of stirring at a speed of 500 rpm at room temperature, followed by stirring at 200 ° C. at 500 RPM for 2 hours After the reaction, the carbon felt electrode according to Comparative Example 2 was dried at room temperature.

Experimental Example  One

Images of the surfaces of the carbon felt electrodes prepared in Example 1-3 and Comparative Example 1-2 were obtained using a scanning electron microscope (SEM). FIGS. 3-5 (a) and (b) are SEM images at × 1000 magnification and × 5000 magnification respectively of Example 1-3, and FIGS. 6-7 (a) and (b) 2 × 1000 magnification and × 5000 magnification SEM image.

As can be seen from the SEM image of FIG. 3-7, Comparative Example 1 shows a carbon felt surface with a smooth surface, and the surface of the carbon felt electrode of Example 1-3 had a smooth surface of Comparative Example 1 It was confirmed that fine pores were formed on the surface of the carbon felt having an increased surface roughness. It is understood that the increased surface roughness of the carbon felt surface will increase the surface area of the carbon felt electrode.

Experimental Example  2

The specific surface area of the carbon felt electrode prepared in Examples 1 to 3 and Comparative Example 1-2 was measured by a BET measuring device. The BET specific surface area measurement results are shown in Table 1 below.

division BET specific surface area [m ² / g] Average pore diameter [nm] Example 1 4.0527 4.8955 Example 2 4.0106 4.3461 Example 3 4.0832 5.0356 Comparative Example 1 3.9359 3.9617 Comparative Example 2 3.9827 4.2695

From the results of Table 1, the specific surface area of Example 1-3 is larger than that of Comparative Example 1-2, and that of Example 3 is larger than that of Example 1-2. This suggests that the use of mixed acid can introduce more oxygen functional groups than the use of a single species acid.

The specific surface area means the reaction surface area, and the increase in the reaction surface area is due to the increase of the reaction surface area of the pores generated on the carbon felt surface in Examples 1-3 in which acid treatment was carried out with the oxidation promoter. In Example 3, the reaction surface area was the greatest increase as compared with Comparative Example 1, and the fact that the reaction surface area was greatly increased thus means that the treatment efficiency of the present invention is excellent.

Experimental Example  3

The carbon felt electrodes prepared in Examples 1-3 and 1-2 were analyzed by energy dispersive spectroscopy (EDS).

8-12 are the results of EDS analysis for Example 1-3 and Comparative Example 1-2, respectively, and the measured carbon and oxygen contents are shown in Table 2 below.

division Oxygen content Carbon content [atom%] [weight%] [atom%] [weight%] Example 1 10.30 13.26 89.74 89.70 Example 2 6.55 8.54 93.45 91.46 Example 3 11.32 13.90 86.65 79.86 Comparative Example 1 0 0 100 100 Comparative Example 2 2.46 3.23 97.12 95.67

In Comparative Example 1 using the untreated carbon felt, the oxygen (O) content was found to be zero and no oxygen-containing functional groups were present or existed below the measurement reference value. In the case of Comparative Example 2 in which an oxidized carbon felt electrode was produced without using an oxidation promoter, oxidation of the carbon felt resulted in oxidation of a hydroxyl group, a ketone group having 2 to 5 carbon atoms, an aldehyde group, an ester group having 2 to 5 carbon atoms, Were introduced onto the surface of the carbon felt electrode, indicating that the carbon-to-carbon content of the electrode was higher than that of the non-oxidized carbon felt electrode of Comparative Example 1. [ However, in Example 1-3, the oxygen content was measured to be higher than that in Comparative Example 2, and it was confirmed that the oxidation treatment was more efficient than Comparative Example 2.

Experimental Example  4

CV (cyclic voltammetry) experiments were performed on the carbon felt electrodes prepared in Examples 1-3 and 1-2.

CV experiments were carried out at a potential scan rate of 5 mV / S at -0.7 V to 1.3 V. SCE (Saturated calomel electrode) was used as the reference electrode and platinum mesh was used as the counter electrode. As the working electrode, the carbon felt electrodes prepared in Examples 1-3 and 1-2 were cut to a size of 4 mm in diameter. The electrolyte used was a mixed aqueous solution of 1 M sulfuric acid (H ₂ SO ₄ ) and 5 mM vanadium (V).

13 is a graph showing the CV measurement results for Example 1-3 and Comparative Example 1-2.

It was confirmed that the capacity and electrochemical characteristics of Example 1-3 were improved through superior oxidation-reduction characteristics of Example 1-3 and lower overpotential compared to Comparative Example 1-2. Example 2 using mixed acid showed better electrochemical properties than Example 1 using only a single acid and Example 3 in which water was intercalated showed better electric properties than Example 2 in which water was not intercalated Chemical properties.

Experimental Example  5

A vanadium redox flow cell using vanadium redox reaction using the carbon felt electrode prepared in Example 1-3 and Comparative Example 1-2 was manufactured as follows and a charge and discharge test was performed.

Charge-discharge experiments were performed at a current density of 100 mA / cm ² . The carbon felt electrodes prepared in Examples 1-3 and 1-2 were cut to a size of 2 (cm) in length and 5 (cm) in size, and were used for the positive electrode and the negative electrode. Ion exchange was carried out using Nafion 115 membrane between the carbon felt electrodes on both sides. The electrolytic solution was a mixed aqueous solution of 3 M sulfuric acid (H ₂ SO ₄ ) and 1.48 M vanadium (V) in an amount of 30 ml each. The electrolyte was supplied at a flow rate of 2 mL / min? Cm ² using a pump.

10 is a graph showing the results of charge-discharge experiments.

The current efficiency, the voltage efficiency and the energy efficiency were calculated by the following formula according to the charge-discharge test results and are shown in Table 3.

(1) Coulomic efficiency

(2) Voltage efficiency

(3) Energy efficiency

Current efficiency Voltage efficiency Energy efficiency Example 1 98% 84% 82% Example 2 98% 81% 79% Example 3 97% 87% 84% Comparative Example 1 98% 75% 73% Comparative Example 2 97% 80% 78%

Table 3 shows that the voltage efficiency and energy efficiency of the vanadium redox flow cell to which the carbon felt electrode of Example 1-3 was applied was much higher than that of the vanadium redox flow battery to which the carbon felt electrode of Comparative Example 1-2 was applied have.

In addition, it was confirmed that the capacity of Example 1-3 was larger than that of Comparative Example 1-2, which is because the oxygen-containing functional groups were more generated in Example 1-3 and the reaction activity of the electrode was improved And it is understood that the contact resistance between the electrode and the carbon separator plate and the electrolyte membrane is lowered and the overvoltage is lowered.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the invention.

Claims (12)

An electrode activation step of introducing an oxygen-containing functional group into the carbon felt using a mixture of strong acid and oxidation promoter; and
And then intercalating water into the carbon felt by infiltrating the carbon felt containing the oxygen-containing functional group after the electrode activating step, to thereby form a carbon felt electrode for a redox flow cell.
The method according to claim 1,
Wherein the strong acid is selected from the group consisting of sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid hydrobromic acid, hydroiodic acid, perchloric acid, and hydrofluoric acid, or a mixture of two or more thereof, Gt;
The method according to claim 1,
Wherein the oxidation promoter comprises at least one selected from the group consisting of potassium permanganate, potassium chlorate, and combinations thereof.
The method according to claim 1,
Wherein the electrode activating step is performed at 35 to 50 占 폚.
The method according to claim 1,
The electrode activation step
(a) placing a carbon felt in a reaction vessel;
(b) adding a mixed solution containing the strong acid and the oxidation promoter to a reaction vessel containing the carbon felt; And
(c) rotating the carbon felt immersed in the mixed solution to uniformly react;
Wherein the carbon felt electrode for a redox-flow battery comprises:
6. The method of claim 5,
Wherein the carbon felt has a rectangular sheet shape, the reaction container has a cylindrical shape with an open top,
Wherein the diameter of the round bottom surface of the reaction vessel is equal to one of a transverse length or a longitudinal length of the carbon felt, or between 0.8 and 1.2 of the transverse length or the longitudinal length of the carbon felt.
delete The method according to claim 1,
The step of intercalating water in the carbon felt
Adding water to the mixture while the carbon felt containing the oxygen-containing functional group is immersed; And
Wherein the temperature of the carbon felt electrode for a redox-flow battery is raised to a temperature of 80 ° C to 120 ° C.
Containing functional group and having an oxygen atom content of 5 to 20 atomic%, wherein the oxygen-containing functional group is selected from the group consisting of a hydroxyl group, a ketone group having 2 to 5 carbon atoms, an aldehyde group, an ester group having 2 to 5 carbon atoms, Carbon fiber electrode for a redox flow cell.
delete A carbon felt electrode for a redox-flow battery produced according to the method of claim 1.
12. The carbon felt electrode according to claim 11, wherein the carbon felt electrode comprises an oxygen-containing functional group and has an oxygen atom content of 5 to 20 atomic%.

Images