Modification method of carbon electrode for flow battery, carbon electrode and flow battery
By loading diatomic catalysts containing iron atoms on the carbon electrodes of the liquid flow battery stack, the problems of poor hydrophilicity and insufficient electrochemical activity of the electrode are solved, and the stability and voltage efficiency of the battery are significantly improved.
Patent Information
- Application Number
- CN202510322197.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-13
AI Technical Summary
The carbon-type electrodes of existing flow cell stacks have problems of poor hydrophilicity and insufficient electrochemical activity, and existing modification methods such as heat treatment and metal modification are costly or dangerous.
A catalyst solution is prepared by mixing a diatomic catalyst containing iron atoms with a polymer binder and solvent. The catalyst is uniformly loaded onto a carbon-based electrode through impregnation and annealing treatment, improving its conductivity and stability.
It significantly improves the hydrophilicity and electrochemical activity of carbon-based electrodes, enhances the stability and voltage efficiency of flow batteries, and is suitable for all-vana flow batteries and other types of flow batteries.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of flow batteries, and particularly to a modification method for carbonaceous electrodes for flow batteries, carbonaceous electrodes, and flow batteries. Background Art
[0002] A flow battery is an electrochemical energy storage device that stores electricity through an electrolyte. Currently, the electrodes of flow battery stacks usually use carbonaceous materials such as carbon felt and graphite felt, which have the characteristics of good electrical conductivity, large specific surface area, high porosity, low cost, and good mechanical stability. However, they also have disadvantages such as poor hydrophilicity and insufficient electrochemical activity.
[0003] In order to improve the hydrophilicity and activity of carbonaceous electrodes, there are already various methods such as heat treatment, chemical treatment, metal modification, and graphene modification to modify them. However, methods such as heat treatment and metal modification cannot improve the hydrophilicity of carbonaceous electrodes such as carbon felt and graphite felt; chemical treatment often uses nitric acid and concentrated sulfuric acid, etc., which are relatively dangerous and costly.
[0004] Therefore, an improved modification method for carbonaceous electrodes for flow batteries, carbonaceous electrodes, and flow batteries is needed. Summary of the Invention
[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of the claims.
[0006] In one aspect, the present application provides a modification method for a carbonaceous electrode for a flow battery, the modification method comprising: Step 1): Mix 1 g - 10 g of a diatomic catalyst containing iron atoms, 1 g - 20 g of a polymer binder, and 10 g - 200 g of a solvent and stir to prepare a catalyst solution; Step 2): Pretreat the carbonaceous electrode and immerse the pretreated carbonaceous electrode into the catalyst solution; and Step 3): Dry and anneal the carbonaceous electrode loaded with the diatomic catalyst containing iron atoms obtained in Step 2), to obtain the modified carbonaceous electrode; wherein the diatomic catalyst containing iron atoms is represented by XYABC, wherein X represents an iron atom, Y represents one of a nickel atom, a copper atom, and a cobalt atom, A represents a carbon atom, B represents a nitrogen atom, and C represents an oxygen atom; wherein in the diatomic catalyst containing iron atoms, the amount of iron element is in the range of 3 wt% - 6 wt%, the amount of one of nickel element, copper element, and cobalt element is in the range of 2 wt% - 4 wt%, the amount of carbon element is in the range of 60 wt% - 75 wt%, the amount of nitrogen element is in the range of 10 wt% - 25 wt%, and the balance is oxygen element; The platelet diameter of the dual-atom catalyst containing iron atoms is in the range of 0.2 μm - 5 μm.
[0007] In this application, the dual-atom catalyst containing iron atoms is a flaky material. The platelet diameter (Platelet Diameter or Flake Diameter) of the catalyst generally refers to the maximum lateral dimension of the flaky catalyst material in the planar direction, which is usually measured by transmission electron microscopy (TEM).
[0008] In this application, the dual-atom catalyst (DAC) containing iron atoms is a catalyst with active sites composed of two metal atoms, one being an iron metal atom and the other being a metal atom selected from nickel, copper, and cobalt. The synthesis methods of the dual-atom catalyst containing iron atoms generally include two methods: bottom-up and top-down. The bottom-up method can utilize precursors with binuclear metal centers or supports with binuclear anchoring sites, and methods such as pyrolysis, impregnation, atomic layer deposition, and ion exchange can be adopted. The top-down method relies on inputting energy to disperse the originally aggregated metals, and methods such as ball milling and atomic capture can be used.
[0009] The dual-atom catalyst containing iron atoms in this application can use commercially available dual-atom catalysts, such as nitrogen-doped carbon iron-nickel dual-atom catalyst, nitrogen-doped carbon iron-copper dual-atom catalyst, and nitrogen-doped carbon iron-cobalt dual-atom catalyst purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd.
[0010] In one embodiment, the polymer binder is selected from one or more of polyvinylidene fluoride, polyaniline, polytetrafluoroethylene, styrene-butadiene rubber, polyethylene oxide, polyhexafluoropropylene, poly(vinylidene fluoride-co-hexafluoropropylene), epoxy resin, phenolic resin, acrylic resin, acetic acid-vinyl acetate resin, and polyurethane. These polymer binders used in this application are easy to obtain and have low costs.
[0011] In one embodiment, the solvent is selected from one or more of tetrahydrofuran, N-methylpyrrolidone, 1,2-dimethoxyethane (monoethylene glycol dimethyl ether), diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and diethyl ether. These solvents used in this application are easy to obtain and have low costs.
[0012] In one embodiment, the pretreatment includes cleaning the carbonaceous electrode with deionized water and drying it.
[0013] In one embodiment, the drying temperature is 40°C - 80°C and the time is 2 - 6 h.
[0014] In one embodiment, in step 1), the stirring time is 20 - 40 min.
[0015] In one embodiment, in step 2), the impregnation time is 4 - 12 h.
[0016] In one embodiment, in step 3), the drying temperature is 40°C - 80°C and the time is 2 - 6 h.
[0017] In one embodiment, in step 3), the annealing temperature is 100°C - 300°C and the time is 1 - 4 h.
[0018] In one embodiment, the carbon - based electrode material is glassy carbon, carbon paper, graphite felt or carbon felt.
[0019] In another aspect, the present application provides a carbon - based electrode for a flow battery, and the carbon - based electrode is modified by the above - mentioned method.
[0020] In one embodiment, the contact angle of the carbon - based electrode is in the range of 0° - 30°.
[0021] In yet another aspect, the present application provides a flow battery including the above - mentioned carbon - based electrode.
[0022] The present application uses a catalyst solution made of a specific dual - atom catalyst composed of an iron metal atom and one metal atom selected from nickel, copper, and cobalt to modify the carbon - based electrode. The specific dual - atom catalyst used in the present application is such that two metals composed of an iron metal atom and one metal atom selected from nickel, copper, and cobalt are dispersed in an isolated form on the surface of the carrier, with high atomic utilization rate and independent active centers; the dual atoms in the dual - atom catalyst used in the present application can synergistically and precisely regulate the electronic structure, with high activity and enhanced stability; the dual - atom catalyst used in the present application has strong selectivity for a specific reaction path due to its structure and electronic properties.
[0023] The present application uses methods such as the impregnation method to uniformly and efficiently load the dual - atom catalyst containing iron atoms onto the original carbon - based electrode (such as carbon felt), which is conducive to large - scale production and preparation. Through the modification method of the present application, the two metal atoms are highly dispersed on the carbon - based electrode (such as carbon felt), and each metal atom can become an active center, thereby improving the activity of the catalyst. A synergistic effect can occur between the two metal atoms to jointly regulate the adsorption and activation of reaction intermediates, thereby optimizing the reaction path and reducing the reaction energy barrier, and improving the reaction efficiency.
[0024] After the carbon - based electrode modified by the modification method of the present application is applied to a flow battery stack structure, such as a vanadium redox flow battery stack structure, it exhibits excellent stability during battery operation.
[0025] The modification method of the present application is simple and easy to implement, significantly improving the electrical conductivity and stability of carbonaceous electrodes. It is applicable not only to all-vanadium redox flow batteries but also can be extended to other types of redox flow battery systems, such as zinc-bromine redox flow batteries, etc.
[0026] Other features and advantages of the present application will be described in the subsequent specification, and, in part, will become apparent from the specification or be understood by implementing the present application. Other advantages of the present application can be realized and obtained through the solutions described in the specification and drawings. Brief Description of the Drawings
[0027] The drawings are used to provide an understanding of the technical solutions of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solutions of the present application and do not constitute a limitation to the technical solutions of the present application.
[0028] Figure 1 is a diagram showing the appearance of the original carbon felt electrode provided according to Embodiments 1 - 3 of the present disclosure; Figure 2A and Figure 2B are respectively diagrams showing the cyclic voltammograms of the positive and negative electrodes of the modified carbon felt electrode and the original carbon felt electrode provided according to Embodiment 1 of the present disclosure; Figure 3 is a diagram showing the voltage efficiency of the modified carbon felt electrode and the original carbon felt electrode provided according to Embodiment 1 of the present disclosure at 160 mA / cm 2 and 240 mA / cm 2 current densities; Figure 4A and Figure 4B are respectively diagrams showing the cyclic voltammograms of the positive and negative electrodes of the modified carbon felt electrode and the original carbon felt electrode provided according to Embodiment 2 of the present disclosure; Figure 5 is a diagram showing the voltage efficiency of the modified carbon felt electrode and the original carbon felt electrode provided according to Embodiment 2 of the present disclosure at 160 mA / cm 2 and 240 mA / cm 2 current densities; Figure 6A and Figure 6B are respectively diagrams showing the cyclic voltammograms of the positive and negative electrodes of the modified carbon felt electrode and the original carbon felt electrode provided according to Embodiment 3 of the present disclosure; and Figure 7 is a diagram showing the voltage efficiency of the modified carbon felt electrode and the original carbon felt electrode provided according to Embodiment 3 of the present disclosure at 160 mA / cm 2 and 240 mA / cm 2 current densities. Detailed implementation manners
[0029] To make the objectives, technical solutions and advantages of the present application more clear and understandable, the embodiments of the present application will be described in detail below. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be arbitrarily combined with each other.
[0030] The following embodiments take a carbon felt electrode as an example of a carbonaceous electrode and select a vanadium redox flow battery for elaboration, but do not limit the application of other carbonaceous electrodes in other flow batteries.
[0031] The materials used in the following embodiments are all commercially available if not otherwise specified.
[0032] Embodiment 1 As Figure 1 shown, the original carbon felt used in this embodiment has a specification of 500mm×300mm×4.2mm.
[0033] 4 g of a nitrogen-doped iron-nickel dual-atom catalyst (commercially available, XF336 from Jiangsu Xianfeng Nano Materials Technology Co., Ltd., with a sheet diameter in the range of 0.5 μm - 2 μm (measured by TEM), in the form of a black powder, including 71.66 wt% carbon element content, 15.88 wt% nitrogen element content, 3.08 wt% iron element content, 2.42 wt% nickel element content, and 6.96 wt% oxygen element content (measured by XPS)), 4 g of polyvinylidene fluoride, and 20 g of N-methylpyrrolidone were mixed and stirred evenly to form a catalyst solution; the original carbon felt was ultrasonically cleaned in deionized water for 30 min and placed in a drying oven to be dried at 45°C for 90 min, and then placed in the catalyst solution for impregnation for 8 h; the impregnated carbon felt was put into a drying oven and dried at 60°C for 120 min, and annealed at 200°C for 2 h to obtain a modified carbon felt electrode.
[0034] Embodiment 2 As Figure 1 shown, the original carbon felt used in this embodiment has a specification of 500mm×300mm×4.2mm.
[0035] 4 g of nitrogen-doped carbon iron-copper dual-atom catalyst (commercially available, XF361 from Jiangsu Xianfeng Nano Materials Technology Co., Ltd., with a sheet diameter in the range of 0.2 μm - 4 μm (measured by TEM), in the form of black powder, including 62.16 wt% carbon element content, 22.97 wt% nitrogen element content, 5.63 wt% iron element content, 3.95 wt% copper element content, and 5.29 wt% oxygen element content (measured by XPS)), 4 g of polytetrafluoroethylene, and 20 g of tetrahydrofuran were mixed and stirred evenly to prepare a catalyst solution; the original carbon felt was ultrasonically cleaned in deionized water for 30 min and placed in a drying oven to dry at 45 °C for 90 min, and then placed in the catalyst solution for impregnation for 8 h; the impregnated carbon felt was put into the drying oven to dry at 60 °C for 120 min and annealed at 200 °C for 2 h to obtain the modified carbon felt electrode.
[0036] Example 3 As Figure 1 shown, the original carbon felt used in this example had a specification of 500 mm × 300 mm × 4.2 mm.
[0037] 4 g of nitrogen-doped iron-cobalt dual-atom catalyst (commercially available, XF311 from Jiangsu Xianfeng Nano Materials Technology Co., Ltd., with a sheet diameter in the range of 0.5 μm - 2 μm (measured by TEM), in the form of black powder, including 69.95 wt% carbon element content, 15.09 wt% nitrogen element content, 3.44 wt% cobalt element content, 3.90 wt% iron element content, and 8.62 wt% oxygen element content (measured by XPS)), 4 g of polyhexafluoropropylene, and 20 g of diglyme were mixed and stirred evenly to prepare a catalyst solution; the original carbon felt was ultrasonically cleaned in deionized water for 30 min and placed in a drying oven to dry at 45 °C for 90 min, and then placed in the catalyst solution for impregnation for 8 h; the impregnated carbon felt was put into the drying oven to dry at 60 °C for 120 min and annealed at 200 °C for 2 h to obtain the modified carbon felt electrode.
[0038] Performance detection The original carbon felt electrode, the modified carbon felt electrodes of Example 1, Example 2, and Example 3 were subjected to a hydrophilicity test. The results showed that the contact angle of the original carbon felt was 80°, indicating poor hydrophilicity; while the contact angle of the modified carbon felt electrode prepared in Example 1 was 10°, the contact angle of the modified carbon felt electrode prepared in Example 2 was 15°, and the contact angle of the modified carbon felt electrode prepared in Example 3 was 10°. It can be seen that the modified carbon felt electrodes obtained in the examples of this application have good hydrophilicity, and excellent hydrophilicity is one of the basic requirements for the electrode materials of all-vanadium redox flow batteries.
[0039] The modified carbon felt electrode and the original carbon felt electrode of Example 1 were subjected to electrochemical performance tests in a vanadium redox flow battery. The modified carbon felt electrode and the original carbon felt electrode of Example 1 were used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode to form a three-electrode system electrolytic cell, and cyclic voltammetry scanning experiments were carried out respectively, so as to obtain the cyclic voltammograms of the modified carbon felt electrode and the original carbon felt electrode of Example 1. The results Figure 2A and Figure 2B are shown. It can be seen from Figure 2A and Figure 2B that compared with the original carbon felt electrode, the modified carbon felt electrode by this method has the smallest oxidation-reduction peak potential difference and the largest peak current, showing excellent electrochemical activity; the modified carbon felt electrode has good electrochemical activity for both the positive electrode reaction (V 5+ / V 4 + ) and the negative electrode reaction (V 2+ / V 3+ ). This further shows the universality and popularization of the carbonaceous electrode modified by the modification method of this application for improving the electrochemical reaction activity of the vanadium redox flow battery.
[0040] The modified carbon felt electrode and the original carbon felt electrode of Example 1 were used as the positive and negative electrodes to assemble a vanadium redox flow battery stack, and the stack was assembled according to the structure of end plate - bipolar plate - electrode - proton exchange membrane - electrode - bipolar plate - electrode - proton exchange membrane - electrode - bipolar plate - end plate. The flow battery was subjected to constant current charge-discharge tests at current densities of 160 mA / cm 2 and 240 mA / cm 2 . The results are as shown in Figure 3 . It can be seen from Figure 3 that compared with the original carbon felt electrode, the flow battery containing the modified carbon felt electrode of Example 1 has higher voltage efficiency at both two different current densities. Further, Figure 3 it also shows that the voltage efficiency value of the modified electrode of this application at a current density of 160 mA / cm 2 is almost unchanged with the increase of the number of charge-discharge cycles, while the voltage efficiency value of the original carbon felt electrode at a current density of 160 mA / cm 2 gradually decreases with the increase of the number of charge-discharge cycles, which shows that the stability of the carbonaceous electrode modified by the modification method of this application is significantly better than that of the original carbon felt electrode.
[0041] The modified carbon felt electrode and the original carbon felt electrode of Example 2 were subjected to electrochemical performance tests in a vanadium redox flow battery. The modified carbon felt electrode and the original carbon felt electrode of Example 2 were used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode to form a three-electrode system electrolytic cell, and cyclic voltammetry scanning experiments were carried out respectively, so as to obtain the cyclic voltammograms of the modified carbon felt electrode and the original carbon felt electrode of Example 2. The results Figure 4A and Figure 4B are shown. It can be seen from Figure 4A and Figure 4B that compared with the original carbon felt electrode, the modified carbon felt electrode by this method has the smallest redox peak potential difference and the largest peak current, showing excellent electrochemical activity; the modified carbon felt electrode has good electrochemical activity for both the positive electrode reaction (V 5+ / V 4 + ) and the negative electrode reaction (V 2+ / V 3+ ). This further shows the universality and popularization of the carbonaceous electrode modified by the modification method of this application for improving the electrochemical reaction activity of the vanadium redox flow battery.
[0042] The modified carbon felt electrode and the original carbon felt electrode of Example 2 were used as the positive and negative electrodes to assemble a vanadium redox flow battery stack. The stack was assembled according to the structure of end plate - bipolar plate - electrode - proton exchange membrane - electrode - bipolar plate - electrode - proton exchange membrane - electrode - bipolar plate - end plate. The flow battery was subjected to constant current charge and discharge tests at current densities of 160 mA / cm 2 and 240 mA / cm 2 . The results are as shown in Figure 5 . It can be seen from Figure 5 that compared with the original carbon felt electrode, the flow battery containing the modified carbon felt electrode of Example 2 has higher voltage efficiency at both two different current densities. Further, Figure 5 it also shows that the voltage efficiency value of the modified electrode of this application at a current density of 160 mA / cm 2 is almost unchanged with the increase of the number of charge and discharge cycles, while the voltage efficiency value of the original carbon felt electrode at a current density of 160 mA / cm 2 gradually decreases with the increase of the number of charge and discharge cycles. This shows that the stability of the carbonaceous electrode modified by the modification method of this application is significantly better than that of the original carbon felt electrode.
[0043] The electrochemical performance of the modified carbon felt electrode and the original carbon felt electrode of Example 3 was tested in a vanadium redox flow battery. The modified carbon felt electrode and the original carbon felt electrode of Example 3 were used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode to form a three-electrode system electrolytic cell, and cyclic voltammetry scanning experiments were carried out respectively, so as to obtain the cyclic voltammograms of the modified carbon felt electrode and the original carbon felt electrode of Example 3. The results Figure 6A and Figure 6B are shown. From Figure 6A and Figure 6B it can be seen that compared with the original carbon felt electrode, the carbon felt electrode modified by this method has the smallest redox peak potential difference and the largest peak current, showing excellent electrochemical activity; the modified carbon felt electrode has good electrochemical activity for both the positive electrode reaction (V 5+ / V 4 + ) and the negative electrode reaction (V 2+ / V 3+ ). This further shows the universality and popularization of the carbonaceous electrode modified by the modification method of this application for improving the electrochemistry reaction activity of the vanadium redox flow battery.
[0044] The modified carbon felt electrode and the original carbon felt electrode of Example 3 were used as the positive and negative electrodes to assemble a vanadium redox flow battery stack. The stack was assembled according to the structure of end plate - bipolar plate - electrode - proton exchange membrane - electrode - bipolar plate - electrode - proton exchange membrane - electrode - bipolar plate - end plate. The flow battery was subjected to constant current charge and discharge tests at current densities of 160 mA / cm 2 and 240 mA / cm 2 . The results are as Figure 7 shown. From Figure 7 it can be seen that compared with the original carbon felt electrode, the flow battery containing the modified carbon felt electrode of Example 3 has higher voltage efficiency at both two different current densities. Further, Figure 7 it also shows that the voltage efficiency value of the modified electrode of this application at a current density of 160 mA / cm 2 is almost unchanged with the increase of the number of charge and discharge cycles, while the voltage efficiency value of the original carbon felt electrode at a current density of 160 mA / cm 2 gradually decreases with the increase of the number of charge and discharge cycles. This shows that the stability of the carbonaceous electrode modified by the modification method of this application is significantly better than that of the original carbon felt electrode.
[0045] Although not wishing to be bound by theory, the applicant believes that the diatomic catalyst containing iron atoms used in this application can interact with vanadium ions to promote the vanadium redox flow battery reaction.
[0046] In the positive electrode reaction, VO 2+ + H2 O - e - VO 2 + + 2H + , the lone pair electrons of the nitrogen atom coordinate with the vacant orbital of the vanadium ion, reducing the reaction activation energy and accelerating the forward reaction, M n+ (M represents one of Ni, Cu, and Co and Fe, and n is a positive integer), which can react with VO 2+ or VO 2 + to undergo a redox reaction. For example, M n+ + VO 2+ M (n - 1)+ + VO 2 + , changing the valence state distribution of the vanadium ion and the reaction rate. The metal atom adsorbs VO 2+ reducing the reaction activation energy and accelerating the forward reaction.
[0047] In the negative electrode reaction, V 3+ + e - V 2+ , the catalyst has an adsorption and electrostatic interaction with V 3+ and V 2+ , increasing the negative electrode reaction rate and reversibility; the metal atom has a charge transfer and coordination interaction with V 3+ and V 2+ , such as forming [M-V 3+ or [M-V 2+ complexes (depending on the coordination ability of the specific metal), stabilizing the ion concentration, mobilizing the electron cloud distribution and diffusion kinetics, enhancing the negative electrode reaction rate and reversibility, ensuring stable and efficient ion transport and electrochemical reaction kinetics during the charge and discharge process of the battery, and improving the overall electrochemical performance and cycle life.
[0048] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.
Claims
1. A method for modifying a carbon electrode for a flow battery, characterized in that: The modification method comprises: Step 1): 1g-10g of a diatomic catalyst containing iron atoms, 1g-20g of a polymer binder and 10g-200g of a solvent are mixed and stirred to prepare a catalyst solution; Step 2): pretreating the carbon-based electrode and immersing the pretreated carbon-based electrode into the catalyst solution; and Step 3): drying and annealing the carbon-based electrode loaded with the diatomic catalyst containing iron atoms obtained in step 2) to obtain a modified carbon-based electrode; wherein the diatomic catalyst containing an iron atom is represented by XYABC, wherein X represents an iron atom, Y represents one of a nickel atom, a copper atom and a cobalt atom, A represents a carbon atom, B represents a nitrogen atom and C represents an oxygen atom; wherein the amount of the iron element in the diatomic catalyst containing iron atoms is in the range of 3wt%-6wt%, the amount of one of the nickel element, the copper element and the cobalt element is in the range of 2wt%-4wt%, the amount of the carbon element is in the range of 60wt%-75wt%, the amount of the nitrogen element is in the range of 10wt%-25wt%, and the balance is the oxygen element; The sheet diameter of the diatomic catalyst containing iron atoms is in the range of 0.2 μm to 5 μm.
2. The modification method according to claim 1, characterized in that The polymer binder is selected from one or more of polyvinylidene fluoride, polyaniline, polytetrafluoroethylene, styrene-butadiene rubber, polyethylene oxide, polyhexafluoropropylene, poly(vinylidene fluoride-co-hexafluoropropylene), epoxy resin, phenolic resin, acrylic resin, acetic acid-vinyl acetate resin and polyurethane; the solvent is selected from one or more of tetrahydrofuran, N-methylpyrrolidone, 1,2-dimethoxyethane (monoethylene glycol dimethyl ether), diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and diethyl ether.
3. The modification method according to claim 1, characterized in that The pretreatment includes washing the carbon-based electrode with deionized water and drying it.
4. The modification method according to claim 3, characterized in that The drying temperature is 40°C-80°C and the drying time is 2-6 hours.
5. The modification method according to claim 1, characterized in that In step 1), the stirring time is 20-40 minutes.
6. The modification method according to claim 1, characterized in that In step 2), the immersion time is 4-12 hours.
7. The modification method according to claim 1, characterized in that In step 3), the drying temperature is 40° C.-80° C. and the time is 2-6 hours; the annealing temperature is 100° C.-300° C. and the time is 1-4 hours.
8. The modification method according to any one of claims 1 to 7, characterized in that The carbon-based electrode material is selected from one of glassy carbon, carbon paper, graphite felt or carbon felt.
9. A carbon electrode for a liquid flow battery, characterized in that: The carbon-based electrode is modified by the modification method according to any one of claims 1 to 8.
10. A liquid flow battery, characterized in that: It comprises the carbon-based electrode according to claim 9.