Carbon felt electrode and preparation method thereof, all-vanadium redox flow battery and energy storage device

Abstract

The invention relates to a carbon felt electrode and a preparation method thereof, an all-vanadium redox flow battery and an energy storage device. The carbon felt electrode comprises an original carbon felt and a porous material coated on the original carbon felt, the porous material is obtained by reaction of trialdehyde m-phenol and 2, 5-diaminobenzene sulfonic acid, and at least part of trialdehyde m-phenol is attached to the original carbon felt through chemical bonds. According to the carbon felt electrode, the electrochemical activity of the carbon felt electrode can be improved while the specific surface area of the carbon felt electrode is increased, so that the electrode performance of the carbon felt electrode is improved.

Description

Technical Field

[0001] This invention relates to the field of vanadium redox flow battery technology, and in particular to a carbon felt electrode and its preparation method, a vanadium redox flow battery, and an energy storage device. Background Technology

[0002] Vanadium redox flow batteries are a promising large-scale energy storage device. Their unique feature lies in storing electrical energy in a vanadium-ion-containing liquid electrolyte, allowing for flexible design of power and capacity—power is determined by the stack size, while capacity can be increased by increasing the electrolyte volume or concentration. This characteristic makes them highly promising for renewable energy fields such as wind power and photovoltaics. They offer numerous advantages, including long lifespan, no self-discharge, high safety, deep discharge capability, and easy maintenance. Furthermore, the system operates in a closed loop, is pollution-free, and achieves an energy efficiency of approximately 80%.

[0003] A battery mainly consists of three parts: the fuel cell stack, the electrolyte, and the control system. The fuel cell stack is the core component, including current collectors, bipolar plates, a separator, and electrodes. Electrodes are one of the key components of a vanadium redox flow battery, significantly impacting its performance. Currently, carbon felt electrodes are the primary electrode used in vanadium redox flow batteries.

[0004] Carbon felt electrodes are typically made from polyacrylonitrile-based carbon fibers through heat treatment processes such as pre-oxidation, carbonization, and graphitization. They are three-dimensional network structures composed of high-purity carbon fibers and are widely used in electrochemical energy storage and conversion, particularly as core components in flow batteries, fuel cells, supercapacitors, and water electrolysis for hydrogen production. Their high conductivity, large specific surface area, and excellent chemical stability effectively promote charge transfer and redox reactions. Their porous structure facilitates electrolyte penetration, and they are inexpensive and easy to mass-produce. However, the strong hydrophobicity of the carbon felt electrode surface leads to poor wettability and low electrolyte utilization efficiency. Without modification, insufficient electrochemical activity can easily induce polarization. The relatively limited specific surface area may also restrict the full exposure of reaction sites, affecting battery power density and efficiency. These issues can be improved through surface treatment. Surface-treated carbon felt electrodes can further increase their specific surface area and electrochemical activity, achieving even higher performance. Therefore, modifying the surface of carbon felt electrodes to increase the specific surface area participating in the reaction and introducing some functional groups to enhance electrochemical activity is of great research significance for improving the performance of carbon felt electrodes. Summary of the Invention

[0005] Therefore, it is necessary to provide a carbon felt electrode that can improve the specific surface area of ​​the carbon felt electrode while also enhancing its electrochemical activity, thereby improving the electrode performance of the carbon felt electrode.

[0006] The present invention provides a carbon felt electrode, comprising a raw carbon felt and a porous material coated on the raw carbon felt, wherein the porous material is obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid, and at least a portion of the trialdehyde resorcinol is attached to the raw carbon felt by chemical bonds.

[0007] In one embodiment, at least a portion of the porous material is obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid on a raw carbon felt.

[0008] The present invention also provides a method for preparing a carbon felt electrode, comprising the following steps:

[0009] The surface of the original carbon felt is oxidized to form oxygen-containing tube energy groups on the surface of the original carbon felt;

[0010] Trialdehyde-based resorcinol is attached to the original carbon felt surface after oxidation treatment, wherein at least a portion of the trialdehyde-based resorcinol is attached to the original carbon felt surface after oxidation treatment through a chemical reaction with oxygen-containing tube groups; and

[0011] The original carbon felt with trialdehyde resorcinol monomer attached to its surface was placed in a 2,5-diaminobenzenesulfonic acid solution and chemically reacted to obtain a carbon felt electrode with a porous material coated on its surface. The porous material was obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid.

[0012] In one embodiment, the oxygen-containing functional group includes at least one of hydroxyl and carboxyl groups.

[0013] In one embodiment, the step of oxidizing the surface of the original carbon felt to form oxygen-containing tube groups on the surface of the original carbon felt includes the following steps:

[0014] The raw carbon felt was soaked in an acid solution at a temperature of 25–80°C for 1–4 hours, wherein the acid solution was sulfuric acid or nitric acid with a concentration of 1–6M.

[0015] The original carbon felt was removed from the acid solution by washing with deionized water; and

[0016] The raw carbon felt, after being dried and washed with deionized water, is obtained as a raw carbon felt with an oxidized surface.

[0017] In one embodiment, the step of attaching trialdehyde resorcinol to the oxidized raw carbon felt includes the following steps:

[0018] The original carbon felt with surface oxidation treatment was immersed in a trialdehyde resorcinol solution and the reaction vessel containing the trialdehyde resorcinol solution was sealed. The solvent of the trialdehyde resorcinol solution was dimethyl sulfoxide.

[0019] Heat the sealed reaction vessel at 50-70℃ for 16-32 hours; and

[0020] The original carbon felt was removed from the trialdehyde resorcinol solution and dried at 70-90℃ for 48 hours.

[0021] In one embodiment, the concentration of the trialdehyde resorcinol is 0.02-0.036 M.

[0022] In one embodiment, in the step of immersing the original carbon felt with trialdehyde resorcinol monomers attached to its surface in a 2,5-diaminobenzenesulfonic acid solution and performing a chemical reaction to obtain a carbon felt electrode with a porous material coated on its surface...

[0023] The 2,5-diaminobenzenesulfonic acid was in excess; and / or

[0024] The solvent in the 2,5-diaminobenzenesulfonic acid solution is deionized water; and / or

[0025] React at 70-90℃ for 40-56 hours; and / or

[0026] After the reaction, the sample is removed, washed with deionized water, and dried under vacuum at 70-90℃.

[0027] The present invention also provides an all-vanadium redox flow battery, comprising the carbon felt electrode described above or the carbon felt electrode prepared by the above preparation method.

[0028] The present invention also provides an energy storage device, including the above-described vanadium redox flow battery.

[0029] In the aforementioned carbon felt electrode, the surface of the carbon felt electrode is coated with a porous material, achieving surface modification treatment. This increases the specific surface area and electrochemical activity of the carbon felt electrode, thereby improving its electrode performance. Trialdehyde-resorcinol and 2,5-diaminobenzenesulfonic acid can undergo a Schiff base reaction condensation to generate a covalent organic framework (COF) with a porous structure. In the aforementioned carbon felt electrode, the porous material is obtained by reacting trialdehyde-resorcinol with 2,5-diaminobenzenesulfonic acid; that is, the porous material is a covalent organic framework (COF) with a porous structure. This further increases the specific surface area and electrochemical activity of the carbon felt electrode. Moreover, in the aforementioned carbon felt electrode, at least a portion of the trialdehyde-resorcinol is attached to the original carbon felt through chemical bonds, allowing the porous material to adhere more stably to the original carbon felt, thus improving the lifespan of the carbon felt electrode. Furthermore, the porous material possesses sulfonic acid groups with good electrical conductivity and hydrophilicity, which can further improve the conductivity and hydrophilicity of the carbon felt electrode. Examples 1-5 and Comparative Examples 1 and 2 demonstrate that the carbon felt electrode described above has good electrode performance, and the surface hydrophobicity of the carbon felt electrode is improved, resulting in better hydrophilicity and thus relatively good wettability. Attached Figure Description

[0030] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0031] Figure 1 This is a flowchart of a method for preparing a carbon felt electrode according to an embodiment of the present invention;

[0032] Figure 2 for Figure 1 The flowchart of step S110 of the method for preparing the carbon felt electrode is shown.

[0033] Figure 3 for Figure 1 The flowchart of step S120 of the method for preparing the carbon felt electrode is shown.

[0034] Figure 4 This is an electron microscope image of Embodiment 1 of the present invention. Detailed Implementation

[0035] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0036] In the description of this application, it should be understood that, where they appear, the terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0037] Furthermore, where applicable, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., shall be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral part; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; they may refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] It should be noted that, if an element is described as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is described as "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0041] An embodiment of the present invention discloses a carbon felt electrode. The carbon felt electrode comprises a raw carbon felt and a porous material coated on the raw carbon felt. The porous material is obtained by reacting trialdehyde-resorcinol with 2,5-diaminobenzenesulfonic acid, and at least a portion of the trialdehyde-resorcinol is attached to the raw carbon felt by chemical bonds.

[0042] In the aforementioned carbon felt electrode, the surface of the carbon felt electrode is coated with a porous material, achieving surface modification treatment. This increases the specific surface area and electrochemical activity of the carbon felt electrode, thereby improving its electrode performance. Trialdehyde-resorcinol and 2,5-diaminobenzenesulfonic acid can undergo a Schiff base reaction condensation to generate a covalent organic framework (COF) with a porous structure. In the aforementioned carbon felt electrode, the porous material is obtained by reacting trialdehyde-resorcinol with 2,5-diaminobenzenesulfonic acid; that is, the porous material is a covalent organic framework (COF) with a porous structure. This further increases the specific surface area and electrochemical activity of the carbon felt electrode. Moreover, in the aforementioned carbon felt electrode, at least a portion of the trialdehyde-resorcinol is attached to the original carbon felt through chemical bonds, allowing the porous material to adhere more stably to the original carbon felt, thus improving the lifespan of the carbon felt electrode. Furthermore, the porous material possesses sulfonic acid groups with good electrical conductivity and hydrophilicity, which can further improve the conductivity and hydrophilicity of the carbon felt electrode. Examples 1-5 and Comparative Examples 1 and 2 demonstrate that the carbon felt electrode described above has good electrode performance, and the surface hydrophobicity of the carbon felt electrode is improved, resulting in better hydrophilicity and thus relatively good wettability.

[0043] In this embodiment, at least a portion of the porous material is obtained by reacting trialdehyde-resorcinol with 2,5-diaminobenzenesulfonic acid on the original carbon felt. That is, in preparing the aforementioned carbon felt electrode, instead of first preparing the porous material and then attaching it to the original carbon felt, at least a portion of the porous material is obtained by reacting trialdehyde-resorcinol with 2,5-diaminobenzenesulfonic acid on the original carbon felt. This facilitates the attachment of the porous material to the original carbon felt, reduces preparation steps, and allows for a more uniform distribution of the porous material attached to the original carbon felt. This further enhances the specific surface area of ​​the carbon felt electrode while simultaneously improving its electrochemical activity.

[0044] like Figure 1 As shown, the present invention also provides a method for preparing a carbon felt electrode. This method includes the following steps:

[0045] Step S110: The surface of the original carbon felt is oxidized to form oxygen-containing tube energy groups on the surface of the original carbon felt.

[0046] Step S120: Trialdehyde resorcinol is attached to the original carbon felt with an oxidized surface, wherein at least a portion of the trialdehyde resorcinol is attached to the original carbon felt with an oxidized surface by chemically reacting with oxygen-containing tube groups.

[0047] Step S130: The original carbon felt with trialdehyde resorcinol monomer attached to its surface is placed in a 2,5-diaminobenzenesulfonic acid solution and chemically reacted to obtain a carbon felt electrode with a porous material coated on its surface. The porous material is obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid.

[0048] In the above-described method for preparing a carbon felt electrode, the surface of the original carbon felt is first oxidized to form oxygen-containing functional groups. Then, trialdehyde-resorcinol is attached to the oxidized carbon felt. At least a portion of the trialdehyde-resorcinol is attached to the oxidized carbon felt through a chemical reaction with the oxygen-containing functional groups. Next, the original carbon felt with the trialdehyde-resorcinol monomer attached to its surface is placed in a 2,5-diaminobenzenesulfonic acid solution. The 2,5-diaminobenzenesulfonic acid reacts with the trialdehyde-resorcinol on the original carbon felt via a Schiff base reaction to condense and generate a covalent organic framework (COF) material with a porous structure, thereby obtaining a carbon felt electrode with a porous material coating. This method improves the electrode performance by treating the surface of the carbon felt electrode, increasing the specific surface area, introducing functional groups, and simultaneously enhancing electrochemical activity. Furthermore, the method is simple and easy to implement. It is understood that other methods can be used to coat the original carbon felt with porous materials in other embodiments.

[0049] In this embodiment, in step S110, the oxygen-containing tubular energy group includes at least one of hydroxyl and carboxyl groups. This greatly facilitates the chemical reaction between trialdehyde resorcinol and the oxygen-containing tubular energy group.

[0050] In this embodiment, step S110 includes the following steps:

[0051] Step S112: Immerse the raw carbon felt in an acid solution at a temperature of 25–80°C for 1–4 hours. The acid solution is a 1–6 M sulfuric acid or nitric acid solution, i.e., a 1–6 mol / L solution. This concentration of sulfuric acid or nitric acid oxidizes the surface of the raw carbon felt, generating oxygen-containing functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups. These oxygen-containing functional groups are bonded to the carbon (C) atoms of the raw carbon felt.

[0052] Step S114: Wash the original carbon felt removed from the acid solution with deionized water. This washes away any residual acid on the surface of the original carbon felt.

[0053] Step S116: Dry the raw carbon felt after washing with deionized water to obtain raw carbon felt with surface oxidation treatment.

[0054] The above method facilitates the oxidation treatment of the surface of the original carbon felt, forming oxygen-containing tube groups on its surface. It is understood that in other embodiments, other methods can also be used to oxidize the surface of the original carbon felt and form oxygen-containing tube groups on its surface.

[0055] In this embodiment, step S120 includes the following steps:

[0056] Step S122: Immerse the original carbon felt with surface oxidation treatment in a trialdehyde resorcinol solution and seal the reaction vessel containing the trialdehyde resorcinol solution, wherein the solvent of the trialdehyde resorcinol solution is dimethyl sulfoxide (DMSO).

[0057] In step S124, the sealed reaction vessel is heated at 50-70°C for 16-32 hours. In this way, the hydroxyl groups of the trialdehyde resorcinol can chemically react with oxygen-containing tube groups and adhere to the original carbon felt surface that has undergone oxidation treatment.

[0058] Step S126: Remove the original carbon felt from the trialdehyde resorcinol solution and dry it at 70-90°C for 48 hours. Without washing, after the solvent dimethyl sulfoxide (DMSO) evaporates, trialdehyde resorcinol that has not chemically reacted with oxygen-containing functional groups can remain on the original carbon felt. This increases the amount of trialdehyde resorcinol on the original carbon felt.

[0059] The above method facilitates the attachment of trialdehyde-resorcinol to the oxidized raw carbon felt, and at least a portion of the trialdehyde-resorcinol is attached to the oxidized raw carbon felt through a chemical reaction with oxygen-containing tube groups. It is understood that in other embodiments, other methods can be used to attach trialdehyde-resorcinol to the raw carbon felt. For example, aldehyde-resorcinol can be directly dripped onto the raw carbon felt.

[0060] In this embodiment, the concentration of the trialdehyde-resorcinol is 0.02-0.036 M. Too low a concentration of trialdehyde-resorcinol would result in too little trialdehyde-resorcinol adhering to the original carbon felt, while too high a concentration would lead to waste of trialdehyde-resorcinol. Considering the above factors, the concentration of trialdehyde-resorcinol is set at 0.02-0.036 M.

[0061] In this embodiment, the 2,5-diaminobenzenesulfonic acid is in excess in step S130. This ensures that all trialdehyde-resorcinol adhering to the original carbon felt can react with the 2,5-diaminobenzenesulfonic acid.

[0062] In this embodiment, in step S130, the solvent in the 2,5-diaminobenzenesulfonic acid solution is deionized water. This reduces costs.

[0063] In this embodiment, in step S130, the reaction is carried out at 70-90°C for 40-56 hours. This ensures that all trialdehyde-resorcinol adhering to the original carbon felt can react with 2,5-diaminobenzenesulfonic acid.

[0064] In this embodiment, after the reaction in step S130, the product is removed, washed with deionized water, and vacuum dried at 70-90°C. This removes unreacted 2,5-diaminobenzenesulfonic acid.

[0065] The present invention also provides an all-vanadium redox flow battery, comprising the carbon felt electrode described above or the carbon felt electrode prepared by the above preparation method.

[0066] The present invention also provides an energy storage device. This energy storage device includes the aforementioned vanadium redox flow battery.

[0067] The present invention will be further described below with reference to embodiments.

[0068] Example 1

[0069] I. Surface oxidation treatment:

[0070] The raw carbon felt was immersed in a concentrated sulfuric acid solution at 50°C for 3 hours. The concentration of the concentrated sulfuric acid was 4M. After treatment, it was removed, washed with deionized water, and dried.

[0071] II. Porous material coating:

[0072] 1. Weigh 1.8 mmol of trialdehyde phloroglucinol (0.378 g; abbreviation Tp) and dissolve it in 50 ml of DMSO (dimethyl sulfoxide). Take a piece of raw carbon felt with a thickness of 3 mm and an area of ​​3*3 cm and place it in a petri dish. Pour in the Tp / DMSO solution to submerge it, seal it with plastic wrap, and heat it at 60 °C for 24 h. Then take it out and dry it at 80 °C for 48 h.

[0073] 2. Weigh 4g of 2,5-diaminobenzenesulfonic acid into 100ml of deionized water, stir and heat to dissolve, then put the carbon felt treated in step 1 into it and react at 80℃ for 48h. After the reaction is completed, take it out, wash it with deionized water, and then dry it in a vacuum oven at 80℃ to obtain a carbon felt electrode with a porous material coating on its surface.

[0074] Figure 4 This is an electron microscope image of the carbon felt electrode prepared in Example 1. According to... Figure 4 It can be seen that the porous material is uniformly coated on the fibers of the original carbon felt.

[0075] Example 2

[0076] The concentrated sulfuric acid was replaced with concentrated nitric acid, and everything else was the same as in Example 1.

[0077] Example 3

[0078] Weigh 2 mmol of trialdehyde phloroglucinol (0.42 g), and everything else is the same as in Example 1.

[0079] Example 4

[0080] Weigh 1.4 mmol of trialdehyde phloroglucinol (0.294 g), and everything else is the same as in Example 1.

[0081] Comparative Example 1

[0082] Raw carbon felt, without surface oxidation treatment and porous material coating.

[0083] Comparative Example 2

[0084] The raw carbon felt was surface-oxidized but not coated with a porous material.

[0085] test

[0086] I. Contact Angle Test

[0087] First, the clean, dry sample, fixed in a fixture, is immersed in deionized water (the test liquid) in a transparent bath and allowed to stand and equilibrate to eliminate the effects of surface adsorption or diffusion. Then, using a curved needle with extracted air (cleaning gas), a tiny bubble is slowly pushed out from below, adhering to the sample's downward-facing surface. Finally, a high-resolution camera is used to vertically capture a clear image of the bubble. Using analysis software with baseline recognition and Laplace equation fitting capabilities, the image is flipped, the bubble profile is fitted, the left and right contact angles are calculated, and the average value is taken to complete the test. The contact angle test results are shown in Table 1.

[0088] II. Energy Efficiency and Capacity Decay Test

[0089] The prepared carbon felt electrode was assembled into an assembly with an effective reaction area of ​​9 cm². 2 In the vanadium redox flow cell, the charge and discharge cutoff voltages are 1.55V and 1.0V, respectively; the positive and negative electrolyte volumes are each 200mL; the vanadium ion concentration in the electrolyte is 1.65mol / L, and the sulfate concentration is 3.5mol / L; constant current charge and discharge is performed with a current density of 80mA / cm². 2 Multiple cyclic tests were conducted. The results of the energy efficiency test and capacity decay test are detailed in Table 1.

[0090] Table 1 Test Results

[0091]

[0092]

[0093] As shown in Table 1, the contact angles of the carbon felt electrodes prepared in Examples 1-5 are much smaller than those in Comparative Example 1 and Comparative Example 2, indicating that the surface hydrophobicity of the carbon felt electrodes prepared in Examples 1-5 is improved, and they have better hydrophilicity, thus having relatively good wettability.

[0094] As shown in Table 1, when the carbon felt electrodes prepared in Examples 1-5 are applied to vanadium redox flow batteries, the energy efficiency of the batteries is greater than that of Comparative Example 1 and greater than that of Comparative Example 2. The capacity decay of the batteries is less than that of Comparative Example 1 and less than that of Comparative Example 2.

[0095] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A carbon felt electrode, characterized in that, It includes a raw carbon felt and a porous material coated on the raw carbon felt, the porous material being obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid, at least a portion of the trialdehyde resorcinol being attached to the raw carbon felt by chemical bonds.

2. The carbon felt electrode as described in claim 1, characterized in that, At least part of the porous material was obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid on a raw carbon felt.

3. A method for preparing a carbon felt electrode, characterized in that, Includes the following steps: The surface of the original carbon felt is oxidized to form oxygen-containing tube energy groups on the surface of the original carbon felt; Trialdehyde-based resorcinol is attached to the original carbon felt surface after oxidation treatment, wherein at least a portion of the trialdehyde-based resorcinol is attached to the original carbon felt surface after oxidation treatment through a chemical reaction with oxygen-containing tube groups; and The original carbon felt with trialdehyde resorcinol monomer attached to its surface was placed in a 2,5-diaminobenzenesulfonic acid solution and chemically reacted to obtain a carbon felt electrode with a porous material coated on its surface. The porous material was obtained by reacting trialdehyde resorcinol with 2,5-diaminobenzenesulfonic acid.

4. The method for preparing the carbon felt electrode as described in claim 3, characterized in that, The oxygen-containing functional group includes at least one of hydroxyl and carboxyl groups.

5. The method for preparing the carbon felt electrode as described in claim 4, characterized in that, The step of oxidizing the surface of the original carbon felt to form oxygen-containing tube groups on the surface of the original carbon felt includes the following steps: The raw carbon felt was soaked in an acid solution at a temperature of 25–80°C for 1–4 hours, wherein the acid solution was sulfuric acid or nitric acid with a concentration of 1–6M. The original carbon felt was removed from the acid solution by washing with deionized water; and The raw carbon felt, after being dried and washed with deionized water, is obtained as a raw carbon felt with an oxidized surface.

6. The method for preparing the carbon felt electrode as described in claim 3, characterized in that, The step of attaching trialdehyde resorcinol to the original carbon felt that has undergone surface oxidation treatment includes the following steps: The original carbon felt with surface oxidation treatment was immersed in a trialdehyde resorcinol solution and the reaction vessel containing the trialdehyde resorcinol solution was sealed. The solvent of the trialdehyde resorcinol solution was dimethyl sulfoxide. Heat the sealed reaction vessel at 50-70℃ for 16-32 hours; and The original carbon felt was removed from the trialdehyde resorcinol solution and dried at 70-90℃ for 48 hours.

7. The method for preparing the carbon felt electrode as described in claim 6, characterized in that, The concentration of the trialdehyde resorcinol is 0.02-0.036M.

8. The method for preparing the carbon felt electrode as described in claim 3, characterized in that, In the step of placing the original carbon felt with trialdehyde resorcinol monomers attached to its surface into a 2,5-diaminobenzenesulfonic acid solution and carrying out a chemical reaction to obtain a carbon felt electrode with a porous material coated on its surface, The 2,5-diaminobenzenesulfonic acid was in excess; and / or The solvent in the 2,5-diaminobenzenesulfonic acid solution is deionized water; and / or React at 70-90℃ for 40-56 hours; and / or After the reaction, the sample is removed, washed with deionized water, and dried under vacuum at 70-90℃.

9. A vanadium redox flow battery, characterized in that, This includes the carbon felt electrode as described in claim 1 or 2, or the carbon felt electrode prepared by the preparation method described in any one of claims 3-8.

10. An energy storage device, characterized in that, Including the all-vanadium redox flow battery as described in claim 9.

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