Catalytically modified graphite felt electrode for vanadium battery and preparation method thereof

Abstract

The present invention relates to the technical field of electrode materials for all-vanadium liquid flow batteries, and discloses a catalytically modified graphite felt electrode for vanadium batteries and a preparation method thereof. In view of the problems of existing graphite felt electrodes such as strong hydrophobicity, insufficient catalytic activity, and weak carbon nanotube loading, the present invention achieves improvements through the following steps: Step S1: acid pretreatment of graphite felt; Step S2: polypyrrole-modified graphite felt; Step S3: carbon nanotube-modified graphite felt; Step S4: catalytic modification of graphite felt. The catalytically modified graphite felt prepared by the present invention uniformly loads carboxyl carbon nanotubes on the polypyrrole layer through hydrogen bonds and π-π conjugation, and improves conductivity through a sintering process. In addition, the electrostatic effect of a surfactant is utilized to further grow polypyrrole particles on the surface of the carbon nanotubes to increase active sites. The present invention significantly improves the conductivity, catalytic activity, and scour resistance of the electrode through the in-situ growth of polypyrrole and the composite loading of carbon nanotubes, combined with sintering optimization and surfactant regulation.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite felt electrodes for all-vanadium redox flow batteries, and in particular to a catalytically modified graphite felt electrode for vanadium batteries and a preparation method thereof. Background Art

[0002] The performance of all-vanadium redox flow batteries (VFBs) is highly dependent on the electrodes, separators, and electrolytes. In recent years, researchers have focused on developing high-performance electrode materials. Generally, VFB electrode materials can be categorized as noble metals (such as Pt-Ti and IrO2-DSA) and carbon-based materials (CBMs). While noble metal electrodes offer excellent electrochemical activity and reversibility, their high cost limits widespread application. Carbon-based materials are considered the most viable electrode materials for VFBs due to their chemical inertness and resource abundance. Among these, self-supporting carbon-based materials (such as graphite felt, carbon felt, and carbon cloth) can be used directly as electrodes without complex processing. Graphite felt (GF) is considered the most promising electrode material due to its high stability, low cost, and high conductivity. However, GF suffers from poor electrolyte wettability and insufficient active sites due to its high hydrophobicity and low specific surface area resulting from its high graphitization temperature.

[0003] While traditional modification methods (such as acid treatment, thermal oxidation, and electrochemical activation) can enhance the hydrophilicity of GF, their impact on VFB performance is limited. In recent years, the strategy of preparing composite electrodes by loading nanotubes and conductive polymers onto the GF surface has attracted considerable attention. Common loading methods include dip-drying and chemical vapor deposition. However, the dip-drying method only adsorbs the conductive material onto the carbon fiber surface through van der Waals forces, resulting in weak bonding and easy detachment due to electrolyte flow. The chemical vapor deposition method, on the other hand, grows carbon nanotubes in situ on the carbon fiber surface, resulting in uneven dispersion. Furthermore, this development and preparation process is complex, significantly increasing the cost of the electrode material and making it unsuitable for large-scale industrial production. Furthermore, the catalytic activity of GF electrodes still has considerable room for improvement and urgently needs to be further enhanced. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a catalytically modified graphite felt electrode for vanadium batteries and a preparation method thereof.

[0005] The technical solution adopted in the present invention is as follows:

[0006] The present application discloses a method for preparing a catalytically modified graphite felt electrode for a vanadium battery, comprising the following steps:

[0007] Step S1: acid pretreatment of graphite felt: soaking the graphite felt in a concentrated sulfuric acid solution with a mass fraction of 98%, washing with deionized water, and vacuum drying to obtain acid pretreated graphite felt.

[0008] Step S2: Preparation of polypyrrole-modified graphite felt: Add 3-5 parts by mass of pyrrole monomer to a mixed solution of 100 parts by mass of deionized water and ethanol, then add 1-3 parts by mass of acid-pretreated graphite felt, and finally slowly add 10-20 parts by mass of initiator solution, start the circulation pump for circulation and dispersion, and after the reaction, wash with water and ethanol and vacuum dry to obtain polypyrrole-modified graphite felt.

[0009] Step S3: Preparation of carbon nanotube-modified graphite felt: Ultrasonic dispersion of 1-2 parts by mass of carboxyl carbon nanotubes, 0.5-1 parts by mass of dispersant polyvinyl pyrrolidone and 100 parts by mass of deionized water for 1-2 hours is carried out and then transferred to a reactor. Then, polypyrrole-modified graphite felt is added to the reactor, and a circulation pump is turned on for circulation dispersion, blending and sintering to obtain carbon nanotube-modified graphite felt.

[0010] Step S4: Preparation of catalytically modified graphite felt: 1-2 parts by mass of surfactant and 0.5-2 parts by mass of pyrrole monomer are dispersed in 100 parts by mass of deionized water, carbon nanotube-modified graphite felt is added, the pH value is adjusted with hydrochloric acid, 10-20 parts by mass of initiator solution is added dropwise into the reactor, a circulating pump is turned on for circulating dispersion, and after the reaction, the catalytically modified graphite felt is washed with water and ethanol and vacuum dried to obtain the catalytically modified graphite felt.

[0011] Preferably, the soaking temperature in step S1 is 25-40° C., and the soaking time is 8-10 hours.

[0012] Preferably, the mass ratio of deionized water to ethanol in the mixed solution of step S2 is (20-50):1.

[0013] Preferably, the reaction temperature in step S2 is -5-3°C, and the reaction time is 16-20 h.

[0014] Preferably, the initiator in steps S2 and S4 is at least one of ammonium persulfate, sodium persulfate and potassium persulfate, and the mass fraction of the initiator solution is 1-2%.

[0015] Preferably, the blending temperature in step S3 is 60-80° C., and the blending time is 2-4 h.

[0016] Preferably, the sintering method in step S3 is to place the sample in a muffle furnace, heat it to 450-500° C. at a heating rate of 2-10° C. / min, and keep it at that temperature for 2-4 hours.

[0017] Preferably, the surfactant in step S4 is at least one of hexadecyldimethylammonium chloride, octadecyltrimethylammonium chloride, and dodecyldimethylamine oxide.

[0018] Preferably, in step S4, the pH value is 4-6; the reaction temperature is 0-3°C; and the reaction time is 18-24 h.

[0019] The present invention also discloses a catalytically modified graphite felt electrode for vanadium batteries, which is prepared by adopting the above-mentioned method for preparing the catalytically modified graphite felt electrode for vanadium batteries.

[0020] The beneficial effects of the present invention are:

[0021] 1. The catalytically modified graphite felt electrode prepared by the present invention is grafted with polypyrrole on the graphite felt fiber by an in-situ growth method. Polypyrrole acts as a conductive adhesive and bonds carbon nanotubes to the graphite felt fiber through hydrogen bonding and π-π conjugation. The carbon nanotubes are evenly loaded and have a high loading capacity. While being resistant to erosion, they also construct a conductive network, thereby improving the catalytic activation ability of the electrode, thereby improving the battery energy, voltage efficiency, and capacity retention.

[0022] 2. The present invention partially carbonizes the dispersant polyvinyl pyrrolidone through a sintering process, thereby improving the conductivity while maintaining the bonding force of the carbon nanotube-modified graphite felt, further improving the energy and voltage efficiency of the battery.

[0023] 3. The catalytically modified graphite felt electrode prepared by the present invention enables polypyrrole particles to grow on carbon nanotubes through the electrostatic interaction between the surfactant and the carboxyl carbon nanotubes, thereby increasing the reaction active area and active sites, providing faster ion transport and lower resistance, further enhancing the catalytic activity of the electrode, and significantly improving the battery energy and voltage efficiency.

[0024] 4. The strength of the catalytically modified graphite felt fiber for vanadium batteries prepared by the present invention is greatly improved, which can effectively reduce the contact resistance and thus improve the energy and voltage efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a diagram of the preparation mechanism of catalytically modified graphite felt for vanadium batteries according to the present invention.

[0026] Figure 2 This is a scanning electron microscope image during the test of Example 1 of the present invention;

[0027] a is acid-pretreated graphite felt, b is polypyrrole-modified graphite felt, c is carbon nanotube-modified graphite felt, and d is catalytically modified graphite felt.

[0028] Figure 3 The scanning electron microscope images of the catalytically modified graphite felt of Example 1 of the present invention and Comparative Example 1 are shown;

[0029] a is the catalytically modified graphite felt of Example 1, and b is the catalytically modified graphite felt of Comparative Example 1. DETAILED DESCRIPTION

[0030] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention, its application, or use. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0031] See also Figure 1 The present invention prepares a catalytically modified graphite felt electrode for vanadium batteries by first functionalizing the graphite felt fiber surface to provide more reaction sites. Pyrrole monomers are then grown on the graphite felt fibers in situ under the action of an initiator to produce polypyrrole-modified graphite felt. Next, carboxyl carbon nanotubes are linked to the polypyrrole through hydrogen bonds and π-π conjugation. Finally, the electrostatic interaction between a surfactant and the carbon nanotubes allows polypyrrole particles to grow on the carbon nanotube surface, completing the preparation of the catalytically modified graphite felt.

[0032] Example 1: A method for preparing a catalytically modified graphite felt electrode for a vanadium battery, comprising the following steps:

[0033] Step S1: acid pretreatment of graphite felt: soaking the graphite felt in a concentrated sulfuric acid solution with a mass fraction of 98% at 25° C. for 10 h, washing with deionized water, and vacuum drying to obtain acid pretreated graphite felt.

[0034] Step S2: Preparation of polypyrrole-modified graphite felt: 3 parts by mass of pyrrole monomer are added to a mixed solution of 100 parts by mass of deionized water and ethanol, with the mass ratio of deionized water to ethanol being 50:1, and then 1 part by mass of acid-pretreated graphite felt is added, and finally 10 parts by mass of 2% initiator ammonium persulfate solution is slowly added, and a circulating pump is turned on for circulating dispersion. The reaction temperature is -2°C and the reaction is carried out for 18 hours. After the reaction, the polypyrrole-modified graphite felt is washed with water and ethanol and vacuum-dried to obtain the polypyrrole-modified graphite felt.

[0035] Step S3: Preparation of carbon nanotube-modified graphite felt: 1.5 parts by mass of carboxyl carbon nanotubes, 0.5 parts by mass of polyvinyl pyrrolidone and 100 parts by mass of deionized water are blended and ultrasonically dispersed for 1.5 hours, and then transferred to a reactor. Then, polypyrrole-modified graphite felt is added to the reactor, and the circulation pump is turned on for circulation dispersion. The mixture is blended at 70°C for 3 hours, placed in a muffle furnace, and heated to 480°C at a heating rate of 5°C / min. The mixture is kept warm for 3 hours and sintered to obtain carbon nanotube-modified graphite felt.

[0036] Step S4: Preparation of catalytically modified graphite felt: 2 parts by mass of surfactant hexadecyldimethylammonium chloride and 1 part by mass of pyrrole monomer are dispersed in 100 parts by mass of deionized water, carbon nanotube-modified graphite felt is added, hydrochloric acid is used to adjust the pH value to 5, 10 parts by mass of 2% initiator ammonium persulfate solution is added dropwise to the reactor, the circulating pump is turned on for circulation and dispersion, the reaction temperature is 0°C, the reaction is carried out for 20 hours, and after the reaction, the catalytically modified graphite felt is washed with water and ethanol and vacuum dried to obtain. Figure 2 As shown in the figure, a is acid pretreated graphite felt, b is polypyrrole modified graphite felt, c is carbon nanotube modified graphite felt, and d is catalytic modified graphite felt. The polypyrrole modified graphite felt has polypyrrole in situ grown on the surface of the fiber, the carbon nanotube modified graphite felt is further evenly loaded on the fiber surface, and the catalytic modified graphite felt has further loaded polypyrrole particles on the carbon nanotubes on the fiber surface, indicating that the catalytic modified graphite felt was successfully prepared.

[0037] Example 2: A method for preparing a catalytically modified graphite felt electrode for a vanadium battery, comprising the following steps:

[0038] Step S1: acid pretreatment of graphite felt: soaking the graphite felt in a concentrated sulfuric acid solution with a mass fraction of 98% at 30° C. for 9 hours, washing with deionized water, and vacuum drying to obtain acid pretreated graphite felt.

[0039] Step S2: Preparation of polypyrrole-modified graphite felt: 4 parts by mass of pyrrole monomer are added to a mixed solution of 100 parts by mass of deionized water and ethanol, where the mass ratio of deionized water to ethanol is 40:1, and then 3 parts by mass of acid-pretreated graphite felt are added. Finally, 15 parts by mass of a 1.5% mass fraction of an initiator potassium persulfate solution are slowly added, and a circulating pump is turned on for circulating dispersion. The reaction temperature is 0°C and the reaction is carried out for 16 hours. After the reaction, the polypyrrole-modified graphite felt is washed with water and ethanol and vacuum-dried to obtain the polypyrrole-modified graphite felt.

[0040] Step S3: Preparation of carbon nanotube-modified graphite felt 0: 2 parts by mass of carboxyl carbon nanotubes, 1 part by mass of polyvinyl pyrrolidone and 100 parts by mass of deionized water are blended and ultrasonically dispersed for 2 hours, and then transferred to a reactor. Then, polypyrrole-modified graphite felt is added to the reactor, and the circulation pump is turned on for circulation dispersion. The mixture is blended at 80°C for 2 hours, placed in a muffle furnace, and heated to 450°C at a heating rate of 2°C / min. The mixture is kept warm for 2 hours and sintered to obtain carbon nanotube-modified graphite felt.

[0041] Step S4: Preparation of catalytically modified graphite felt: 1 part by mass of surfactant dodecyldimethylamine oxide and 0.5 parts by mass of pyrrole monomer are dispersed in 100 parts by mass of deionized water, carbon nanotube-modified graphite felt is added, the pH value is adjusted to 4 with hydrochloric acid, 15 parts by mass of 1.5% initiator potassium persulfate solution is added dropwise into the reactor, the circulation pump is turned on for circulation dispersion, the reaction temperature is 3°C, the reaction is carried out for 18 hours, and after the reaction, the catalytically modified graphite felt is washed with water and ethanol and vacuum dried.

[0042] Example 3: A method for preparing a catalytically modified graphite felt electrode for a vanadium battery, comprising the following steps:

[0043] Step S1: acid pretreatment of graphite felt: soaking the graphite felt in a concentrated sulfuric acid solution with a mass fraction of 98% at 40° C. for 9 h, washing with deionized water, and vacuum drying to obtain acid pretreated graphite felt.

[0044] Step S2: Preparation of polypyrrole-modified graphite felt: 5 parts by mass of pyrrole monomer are added to a mixed solution of 100 parts by mass of deionized water and ethanol, with the mass ratio of deionized water to ethanol being 20:1, and then 2 parts by mass of acid-pretreated graphite felt are added, and finally 20 parts by mass of a 1% by mass initiator sodium persulfate solution are slowly added, and a circulating pump is turned on for circulating dispersion. The reaction temperature is -5°C and the reaction is carried out for 20 hours. After the reaction, the polypyrrole-modified graphite felt is washed with water and ethanol and vacuum-dried to obtain the polypyrrole-modified graphite felt.

[0045] Step S3: Preparation of carbon nanotube-modified graphite felt: 1 part by mass of carboxyl carbon nanotubes, 0.8 parts by mass of polyvinyl pyrrolidone and 100 parts by mass of deionized water are blended and ultrasonically dispersed for 1 hour, and then transferred to a reactor. Then, polypyrrole-modified graphite felt is added to the reactor, and the circulation pump is turned on for circulation dispersion. The mixture is blended at 60°C for 4 hours, placed in a muffle furnace, and heated to 500°C at a heating rate of 7°C / min. The mixture is kept warm for 4 hours and sintered to obtain carbon nanotube-modified graphite felt.

[0046] Step S4: Preparation of catalytically modified graphite felt: 1.5 parts by mass of surfactant octadecyltrimethylammonium chloride and 2 parts by mass of pyrrole monomer are dispersed in 100 parts by mass of deionized water, carbon nanotube-modified graphite felt is added, the pH value is adjusted to 6 with hydrochloric acid, 20 parts by mass of 1% initiator sodium persulfate solution is added dropwise into the reactor, the circulation pump is turned on for circulation dispersion, the reaction temperature is 2°C, the reaction is carried out for 22 hours, and after the reaction, the catalytically modified graphite felt is washed with water and ethanol and vacuum dried.

[0047] Example 4: A method for preparing a catalytically modified graphite felt electrode for a vanadium battery, comprising the following steps:

[0048] Step S1: acid pretreatment of graphite felt: soaking the graphite felt in a concentrated sulfuric acid solution with a mass fraction of 98% at 35° C. for 8 h, washing with deionized water, and vacuum drying to obtain acid pretreated graphite felt.

[0049] Step S2: Preparation of polypyrrole-modified graphite felt: 4 parts by mass of pyrrole monomer are added to a mixed solution of 100 parts by mass of deionized water and ethanol, where the mass ratio of deionized water to ethanol is 30:1, and then 2 parts by mass of acid-pretreated graphite felt are added. Finally, 15 parts by mass of 1.5% initiator ammonium persulfate solution are slowly added, and a circulating pump is turned on for circulation and dispersion. The reaction temperature is 3°C and the reaction is carried out for 16 hours. After the reaction, the polypyrrole-modified graphite felt is washed with water and ethanol and vacuum-dried to obtain the polypyrrole-modified graphite felt.

[0050] Step S3: Preparation of carbon nanotube-modified graphite felt: 1.5 parts by mass of carboxyl carbon nanotubes, 0.5 parts by mass of polyvinyl pyrrolidone and 100 parts by mass of deionized water are blended and ultrasonically dispersed for 1.5 hours, and then transferred to a reactor. Then, polypyrrole-modified graphite felt is added to the reactor, and the circulation pump is turned on for circulation dispersion. The mixture is blended at 75°C for 3 hours, placed in a muffle furnace, and heated to 470°C at a heating rate of 10°C / min. The mixture is kept warm for 3 hours and sintered to obtain carbon nanotube-modified graphite felt.

[0051] Step S4: Preparation of catalytically modified graphite felt: 1.5 parts by mass of surfactant hexadecyl dimethylammonium chloride and 1.5 parts by mass of pyrrole monomer are dispersed in 100 parts by mass of deionized water, carbon nanotube-modified graphite felt is added, the pH value is adjusted to 5.5 with hydrochloric acid, 15 parts by mass of 1.5% initiator ammonium persulfate solution is added dropwise into the reactor, the circulation pump is turned on for circulation dispersion, the reaction temperature is 1°C, the reaction is carried out for 24 hours, and after the reaction, the catalytically modified graphite felt is washed with water and ethanol and vacuum dried to obtain.

[0052] Comparative Example 1:

[0053] The method is consistent with Example 1, except that step S2 of preparing polypyrrole-modified graphite felt is omitted, and step S3 of using acid-pretreated graphite felt to load carbon nanotubes is performed.

[0054] Comparative Example 2:

[0055] Consistent with Example 1, step S3 does not involve sintering.

[0056] Comparative Example 3:

[0057] The same as in Example 1, without step S4.

[0058] Comparative Example 4:

[0059] Blank graphite felt.

[0060] The graphite felts obtained in Examples 1-4 and Comparative Examples 1-4 were cut into 3cm*3cm sizes, copper plates were placed at both ends, and a digital pressure tester was used to maintain the graphite felt deformation at 25% to test the stress. A low resistance tester was used to clamp the copper plates at both ends to test the resistance at 25% deformation. The graphite felts obtained in Examples and Comparative Examples were assembled into battery stacks and charged and discharged under the same test conditions. The battery coulombic efficiency, voltage efficiency, energy efficiency, and capacity retention rate after 100 cycles were recorded. The test results are shown in Table 1:

[0061] Table 1 Test results summary

[0062] index Stress (N) Resistance (mΩ) Coulomb efficiency Energy efficiency Voltage efficiency Capacity retention rate after 100 cycles Example 1 94.6 21.4 97.1% 91.6% 94.3% 98.6% Example 2 94.8 20.8 97.0% 91.8% 94.6% 98.4% Example 3 94.2 22.2 97.1% 91.2% 93.9% 98.5% Example 4 94.5 21.6 97.3% 91.5% 94.0% 98.6% Comparative Example 1 94.0 22.4 97.1% 91.3% 94.0% 88.6% Comparative Example 2 94.2 22.2 97.0% 87.3% 90.0% 98.5% Comparative Example 3 94.6 21.5 97.2% 89.4% 92.0% 98.2% Comparative Example 4 60.8 45.9 97.1% 85.1% 87.6% 98.1%

[0063] As can be seen from Table 1, Examples 1-4 have similar capacity retention rates compared to Comparative Example 4, indicating that the carbon nanomaterials of Examples 1-10 loaded on the graphite felt fibers do not affect the performance of their capacity retention rates, indicating that the carbon nanotubes of Examples 1-4 can be firmly loaded on the graphite felt fibers and are not easily washed away. Secondly, the capacity retention rate of Comparative Example 1 is slightly lower than that of Examples 1-4, which further illustrates that polypyrrole plays an important role in firmly loading carbon nanotubes. Finally, as Figure 3 It can be seen from the scanning electron microscope images of Example 1 and Comparative Example 1 that the carbon nanotube content in Example 1 is much higher than that in Comparative Example 1, further illustrating that polypyrrole, as a conductive adhesive, bonds carbon nanotubes to the graphite felt fibers through hydrogen bonding and π-π conjugation, and that the carbon nanotubes are uniformly loaded and have a high loading capacity. Examples 1-4 and Comparative Examples 1-3 all have higher stress, lower resistance, and higher battery efficiency, indicating that the strength of the catalytically modified graphite felt fibers for vanadium batteries prepared by the present invention is greatly improved, which can effectively reduce contact resistance, thereby improving the energy and voltage efficiency of the battery. Examples 1-4 have higher energy and voltage efficiency than Comparative Example 2. This is because the present invention partially carbonizes the dispersant polyvinyl pyrrolidone through a sintering process, thereby improving the conductivity while maintaining the bonding force of the carbon nanotube-modified graphite felt, further improving the energy and voltage efficiency of the battery. Examples 1-4 have higher energy and voltage efficiencies than Comparative Example 3. This is because the catalytically modified graphite felt electrode prepared by the present invention enables polypyrrole particles to grow on carbon nanotubes through the electrostatic interaction between the surfactant and the carboxyl carbon nanotubes, thereby increasing the reaction active area and active sites, providing faster ion transport and lower resistance, further enhancing the catalytic activity of the electrode, and further significantly improving the battery energy and voltage efficiency.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a catalytically modified graphite felt electrode for a vanadium battery, characterized in that: The following steps are involved: Step S1: acid pretreatment of graphite felt: soaking the graphite felt in a concentrated sulfuric acid solution with a mass fraction of 98%, washing with deionized water, and vacuum drying to obtain acid pretreated graphite felt; Step S2: Preparation of polypyrrole-modified graphite felt: adding 3-5 parts by mass of pyrrole monomer to a mixed solution of 100 parts by mass of deionized water and ethanol, then adding 1-3 parts by mass of acid-pretreated graphite felt, and finally slowly adding 10-20 parts by mass of initiator solution, turning on a circulation pump for circulatory dispersion, washing with water and ethanol after the reaction, and vacuum drying to obtain polypyrrole-modified graphite felt; Step S3: Preparation of carbon nanotube-modified graphite felt: Ultrasonic dispersion of 1-2 parts by mass of carboxyl carbon nanotubes, 0.5-1 parts by mass of dispersant polyvinylpyrrolidone, and 100 parts by mass of deionized water for 1-2 hours is performed, and the mixture is transferred to a reactor. Polypyrrole-modified graphite felt is then added to the reactor, and a circulating pump is turned on for circulatory dispersion, blending, and sintering to obtain carbon nanotube-modified graphite felt. The sintering method is to place the mixture in a muffle furnace, heat it to 450-500° C. at a heating rate of 2-10° C. / min, and keep it at that temperature for 2-4 hours. Step S4: Preparation of catalytically modified graphite felt: 1-2 parts by mass of a surfactant and 0.5-2 parts by mass of a pyrrole monomer are dispersed in 100 parts by mass of deionized water, carbon nanotube-modified graphite felt is added, the pH value is adjusted with hydrochloric acid, 10-20 parts by mass of an initiator solution is dropped into the reactor, a circulating pump is turned on for circulating dispersion, and after the reaction, the catalytically modified graphite felt is washed with water and ethanol and vacuum dried to obtain the catalytically modified graphite felt; wherein the surfactant is at least one of hexadecyldimethylammonium chloride, octadecyltrimethylammonium chloride, and dodecyldimethylamine oxide.

2. The method for preparing a catalytically modified graphite felt electrode for a vanadium battery according to claim 1, wherein: In step S1, the soaking temperature is 25-40° C., and the soaking time is 8-10 hours.

3. The method for preparing a catalytically modified graphite felt electrode for a vanadium battery according to claim 1, wherein: The mass ratio of deionized water to ethanol in the mixed solution of step S2 is (20-50):

1.

4. The method for preparing a catalytically modified graphite felt electrode for a vanadium battery according to claim 1, wherein: In step S2, the reaction temperature is -5-3°C, and the reaction time is 16-20 h.

5. The method for preparing a catalytically modified graphite felt electrode for a vanadium battery according to claim 1, wherein: In steps S2 and S4, the initiator is at least one of ammonium persulfate, sodium persulfate and potassium persulfate, and the mass fraction of the initiator solution is 1-2%.

6. The method for preparing a catalytically modified graphite felt electrode for a vanadium battery according to claim 1, wherein: The blending temperature in step S3 is 60-80° C., and the blending time is 2-4 hours.

7. The method for preparing a catalytically modified graphite felt electrode for a vanadium battery according to claim 1, wherein: In step S4, the pH value is 4-6; the reaction temperature is 0-3°C; and the reaction time is 18-24 h.

8. A catalytically modified graphite felt electrode for vanadium batteries, characterized by: The catalytically modified graphite felt electrode is prepared by the method for preparing a catalytically modified graphite felt electrode for a vanadium battery as described in any one of claims 1 to 7.

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