Vanadium redox flow battery electrode material with low internal resistance as well as preparation method and application of vanadium redox flow battery electrode material

Abstract

The invention relates to the field of batteries, in particular to a low-internal-resistance vanadium redox flow battery electrode material and a preparation method and application thereof. The preparation method of the low-internal-resistance vanadium redox flow battery electrode material comprises the following steps: carrying out plasma activation treatment on an electrode base material to obtain an activated electrode material; the method comprises the following steps: mixing a bimetallic MAX phase compound with a fluorine-containing salt solution, and carrying out electrochemical etching to obtain an MXene material; the preparation method comprises the following steps: dispersing an MXene material in water, and adding carbon nanotubes and a surfactant to obtain a dispersion liquid; dipping the activated electrode material in the dispersion liquid, and carrying out hydrothermal reaction to obtain an intermediate product; dipping the intermediate product in a dopamine hydrochloride solution containing metal salt, adopting a pulse electrochemical deposition method layer, and then performing carbonization and activation treatment in sequence to obtain the low-internal-resistance vanadium redox flow battery electrode material. The low-internal-resistance vanadium redox flow battery electrode material provided by the invention can effectively reduce electrode polarization, improve the energy utilization rate and prolong the service life.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a low-internal-resistance vanadium redox flow battery electrode material, a preparation method thereof, and applications thereof. Background Art

[0002] Vanadium redox flow batteries (VRFBs) are widely researched and applied in large-scale energy storage due to their high safety, long cycle life, and strong scalability. This system converts electrical energy into chemical energy through the reversible redox reaction of vanadium ions between different oxidation states, demonstrating excellent reversibility and system stability.

[0003] In all-vanadium redox flow batteries, electrode materials serve as the core interface where electrochemical reactions occur. Their structure and performance directly influence the battery's charge transfer rate, energy efficiency, and cycle life. Currently, widely used electrodes are primarily carbon-based porous materials such as graphite felt (GF) or carbon felt (CF). These materials possess high chemical stability and moderate electrical conductivity, but they exhibit poor natural hydrophilicity, limited surface active sites, and insufficient electrocatalytic performance. This results in high polarization resistance and low energy efficiency, particularly at high current densities, where performance degrades significantly, severely limiting the battery's power output and long-term stable operation.

[0004] To address these issues, various electrode modification strategies have been explored, including surface activation, doping modification, conductive material loading, metal / metal oxide modification, and electrocatalytic layer construction. While these approaches can improve the electrochemical activity and charge transfer rate of electrodes to a certain extent, they still face a number of challenges in practical application. For example, some modification methods are complex, have poor reproducibility, are costly, or may result in active material shedding, poor structural stability, and electrode pore clogging, making it difficult to achieve both high-efficiency catalysis and long-term cycling stability.

[0005] Therefore, how to construct an electrode material with stable structure, strong conductivity, high electrochemical activity and suitable for large-scale preparation is still one of the key technical bottlenecks in the current development of vanadium flow battery technology. Summary of the Invention

[0006] In view of this, the present invention is dedicated to providing a low internal resistance vanadium redox flow battery electrode material and its preparation method and application, so as to solve the problem of poor electrochemical performance of vanadium redox flow battery electrode materials in the prior art.

[0007] In order to solve the above technical problems, this application is implemented as follows:

[0008] The present invention provides a method for preparing a low internal resistance vanadium redox flow battery electrode material, comprising the following steps:

[0009] (1) Plasma activation treatment of the electrode substrate to obtain an activated electrode material;

[0010] (2) mixing the bimetallic MAX phase compound and a fluorine-containing salt solution, performing electrochemical etching, and obtaining a MXene material after centrifugal washing;

[0011] (3) Dispersing the MXene material in water, adding carbon nanotubes and surfactants to obtain a dispersion; immersing the activated electrode material in the dispersion to perform a hydrothermal reaction to obtain an intermediate product;

[0012] (4) The intermediate product is immersed in a dopamine hydrochloride solution containing a metal salt, and a coating is formed on the electrode surface by a pulse electrochemical deposition method, followed by carbonization and activation treatments in sequence. After cooling, a low internal resistance vanadium liquid flow battery electrode material is obtained.

[0013] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium flow battery electrode material, in step (1), the electrode substrate comprises at least one of carbon paper, carbon cloth, carbon felt and graphite felt.

[0014] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (1), the conditions for the plasma activation treatment are: the gas is a mixed atmosphere of oxygen and argon, the volume ratio of oxygen to argon is 4:1, the power is 100~250W, and the time is 5~15min.

[0015] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (2), the bimetallic MAX phase compound comprises Mo2VAlC2 and / or TiVAlC;

[0016] In step (2), the fluorine-containing salt solution includes LiF and HCl, the concentration of LiF in the fluorine-containing salt solution is 1.5-2 mol / L, and the concentration of HCl in the fluorine-containing salt solution is 2-3 mol / L;

[0017] In step (2), the usage ratio of the bimetallic MAX phase compound and the fluorine-containing salt solution is 1 g: 10-30 mL.

[0018] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (2), the electrochemical etching conditions are: the current is 10~12mA / cm 2 , time is 4~5h.

[0019] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (3), the usage ratio of the MXene material and water is 1 g: 10-30 mL;

[0020] In step (3), the mass ratio of the MXene material to the carbon nanotubes is 1:0.25-0.5;

[0021] In step (3), the mass ratio of the MXene material to the surfactant is 1:0.01~0.05;

[0022] In step (3), the surfactant is hexadecyltrimethylammonium bromide.

[0023] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (3), the immersion temperature is 20-30° C., and the immersion time is 1-2 h;

[0024] In step (3), the temperature of the hydrothermal reaction is 180-200° C., and the time of the hydrothermal reaction is 6-8 h.

[0025] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (4), the concentration of dopamine hydrochloride in the dopamine hydrochloride solution containing a metal salt is 2-5 mg / L;

[0026] In step (4), the molar ratio of the metal salt to dopamine in the dopamine hydrochloride solution containing the metal salt is 1 to 3:10;

[0027] In step (4), the metal salt in the dopamine hydrochloride solution containing the metal salt includes FeCl3, CoCl2 or H2PtCl6.

[0028] Preferably, in the above-mentioned method for preparing a low internal resistance vanadium redox flow battery electrode material, in step (4), the immersion temperature is 30-40° C., and the immersion time is 20-30 min;

[0029] In step (4), the pulse voltage is +0.8V / -0.2V, the pulse width is 10s, and the total deposition time is 30-60min;

[0030] In step (4), the carbonization atmosphere is an inert gas, the carbonization temperature is 800-1000°C, and the carbonization time is 2-4 hours;

[0031] In step (4), the atmosphere of the activation treatment is carbon dioxide, the flow rate of carbon dioxide is 100~120mL / min, the temperature of the activation treatment is 900~1000℃, and the time of the activation treatment is 0.5~1h.

[0032] The present invention also provides a low internal resistance vanadium redox flow battery electrode material prepared by a method for preparing the low internal resistance vanadium redox flow battery electrode material.

[0033] The present invention also provides an application of a low internal resistance vanadium redox flow battery electrode material in an all-vanadium redox flow battery.

[0034] Through the above technical solution, the beneficial technical effects of the present invention are:

[0035] The present invention provides a method for preparing a low-internal-resistance vanadium redox flow battery electrode material. Based on MAX phase MXene materials, multi-walled carbon nanotubes (CNTs), a metal / nitrogen hybridized conductive coating, and a multi-step coupling modification strategy, a composite structure electrode material with synergistic conductivity, abundant active sites, and smooth ion transport is constructed. This method effectively reduces electrode polarization and improves energy utilization and service life. Specific implementations are as follows:

[0036] The MXene material obtained from bimetallic MAX phases such as TiVAlC or Mo2VAlC2 by electrochemical etching has a two-dimensional layered structure and excellent conductive properties, which can effectively improve the electron transfer efficiency, provide a large number of reaction sites, help to increase the charge transfer rate between the electrode and the electrolyte, and reduce the interface resistance; the introduction of carbon nanotubes (CNTs) forms a three-dimensional conductive network between the MXene layers, improves the overall conductivity and mechanical stability of the material, inhibits the agglomeration of MXene in subsequent treatments, and is beneficial to the long-term cycle stability of the composite system; hexadecyltrimethylammonium bromide (CTAB) is used as a cationic surfactant to enhance the dispersibility of MXene and CNT in the aqueous phase, and regulates its adsorption and assembly efficiency on the surface of porous carbon felt, thereby ensuring the uniformity of subsequent reactions and material loading; then the MXene / CNT composite is deeply embedded and coated with the graphite felt fiber by a hydrothermal method, forming a stable "soft coating + skeleton support" structure, which effectively improves the adhesion and electrochemical stability of the electrode composite. Dopamine molecules are highly soluble in metal ions (such as Fe 3+ 、Co 2+ ) spontaneously polymerizes in the presence of carbon nanotubes (CNTs) to form a polydopamine (PDA) complex, which is densely coated on the substrate via electrodeposition. This layer is rich in nitrogen-doped and metal-active sites, further enhancing electronic conductivity and electrode surface activity. Carbonization transforms the PDA complex layer into a nitrogen-doped carbon material, which forms a multi-channel electron transport pathway with CNTs and MXene. CO2 activation further introduces microporous structures on the material surface, improving electrolyte permeability and the reaction interface area, ultimately achieving an organic combination of low internal resistance and high power output. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below by way of examples. The raw materials used in the examples can all be obtained through commercial sources.

[0038] Example 1

[0039] A method for preparing a low internal resistance vanadium redox flow battery electrode material comprises the following steps:

[0040] (1) A 30 cm × 30 cm graphite felt was selected as the electrode substrate and placed in a mixed plasma with an oxygen to argon gas volume ratio of 4:1 for surface activation treatment at a power of 150 W for 10 min to obtain an activated electrode material;

[0041] (2) Weigh 2 g of bimetallic MAX phase TiVAlC powder and add it to 20 mL of a mixed solution containing 1.8 mol / L LiF and 2.5 mol / L HCl. Electrochemical etching is performed at a constant current of 10 mA / cm² for 5 h. After the reaction is completed, centrifugal washing is performed with deionized water to a pH of 6 to obtain MXene material.

[0042] (3) Take 1g of the above MXene material, add 20mL of deionized water, add 0.3g of multi-walled carbon nanotubes (CNTs) and 0.02g of hexadecyltrimethylammonium bromide (CTAB), and ultrasonicate for 30min to form a uniform dispersion; completely immerse the activated graphite felt material in the above dispersion, let it stand at room temperature for 1.5h, and then transfer it to a stainless steel autoclave for hydrothermal reaction at 180℃ for 6h. After cooling, take it out and wash it with deionized water, and then dry it to obtain the intermediate product;

[0043] (4) A dopamine hydrochloride solution (4 mg / mL) was prepared, to which FeCl₃ was added so that the molar ratio of FeCl₃ to dopamine was 2:10, to obtain a dopamine hydrochloride solution containing a metal salt. The intermediate product was immersed in the dopamine hydrochloride solution containing a metal salt, maintained at 35°C, and immersed for 30 min. Subsequently, pulse electrodeposition was performed in a three-electrode system with a voltage range of +0.8 V / −0.2 V, a pulse width of 10 s, and a total deposition time of 45 min to form a metal / nitrogen hybrid conductive coating on the electrode surface. The obtained electrode material was carbonized in an argon atmosphere (900°C, 3 h), and then activated in a CO₂ atmosphere (950°C, 0.5 h, CO₂ flow rate 110 mL / min). After cooling, a low internal resistance vanadium redox flow battery electrode material was obtained.

[0044] Example 2

[0045] A method for preparing a low internal resistance vanadium redox flow battery electrode material comprises the following steps:

[0046] (1) A 30 cm × 30 cm graphite felt was selected as the electrode substrate and placed in a mixed plasma with an oxygen to argon gas volume ratio of 4:1 for surface activation treatment at a power of 150 W for 10 min to obtain an activated electrode material;

[0047] (2) Weigh 2 g of bimetallic MAX phase TiVAlC powder and add it to 20 mL of a mixed solution containing 1.8 mol / L LiF and 2.5 mol / L HCl. Electrochemical etching is performed at a constant current of 10 mA / cm² for 5 h. After the reaction is completed, centrifugal washing is performed with deionized water to a pH of 6 to obtain MXene material.

[0048] (3) Take 1g of the above MXene material, add 20mL of deionized water, add 0.3g of multi-walled carbon nanotubes (CNTs) and 0.02g of hexadecyltrimethylammonium bromide (CTAB), and ultrasonicate for 30min to form a uniform dispersion; completely immerse the activated graphite felt material in the above dispersion, let it stand at room temperature for 1.5h, and then transfer it to a stainless steel autoclave for hydrothermal reaction at 180℃ for 6h. After cooling, take it out and wash it with deionized water, and then dry it to obtain the intermediate product;

[0049] (4) A dopamine hydrochloride solution (4 mg / mL) was prepared, to which CoCl2 was added so that the molar ratio of CoCl2 to dopamine was 2:10, to obtain a dopamine hydrochloride solution containing a metal salt. The intermediate product was immersed in the dopamine hydrochloride solution containing a metal salt, maintained at 35°C, and immersed for 30 minutes. Subsequently, pulse electrodeposition was performed in a three-electrode system with a voltage range of +0.8 V / −0.2 V, a pulse width of 10 s, and a total deposition time of 45 minutes to form a metal / nitrogen hybrid conductive coating on the electrode surface. The obtained electrode material was carbonized in an argon atmosphere (1000°C, 3 hours), and then activated in a CO2 atmosphere (900°C, 0.5 hours, CO2 flow rate 110 mL / min). After cooling, a low internal resistance vanadium redox flow battery electrode material was obtained.

[0050] Example 3

[0051] A method for preparing a low internal resistance vanadium redox flow battery electrode material comprises the following steps:

[0052] (1) A 30 cm × 30 cm graphite felt was selected as the electrode substrate and placed in a mixed plasma with an oxygen to argon gas volume ratio of 4:1 for surface activation treatment at a power of 150 W for 10 min to obtain an activated electrode material;

[0053] (2) Weigh 2 g of bimetallic MAX phase TiVAlC powder and add it to 20 mL of a mixed solution containing 1.8 mol / L LiF and 2.5 mol / L HCl. Electrochemical etching is performed at a constant current of 10 mA / cm² for 5 h. After the reaction is completed, centrifugal washing is performed with deionized water to a pH of 6 to obtain MXene material.

[0054] (3) Take 1g of the above MXene material, add 20mL of deionized water, add 0.3g of multi-walled carbon nanotubes (CNTs) and 0.02g of hexadecyltrimethylammonium bromide (CTAB), and ultrasonicate for 30min to form a uniform dispersion. The activated graphite felt material is completely immersed in the above dispersion, allowed to stand at room temperature for 1.5h, and then transferred to a stainless steel autoclave for hydrothermal reaction at 200℃ for 7h. After cooling, the material is taken out and washed with deionized water, and dried to obtain the intermediate product.

[0055] (4) A dopamine hydrochloride solution (4 mg / mL) was prepared, to which FeCl₃ was added so that the molar ratio of FeCl₃ to dopamine was 1:10, to obtain a dopamine hydrochloride solution containing a metal salt. The intermediate product was immersed in the dopamine hydrochloride solution containing a metal salt, maintained at 35°C, and immersed for 30 min. Subsequently, pulse electrodeposition was performed in a three-electrode system with a voltage range of +0.8 V / −0.2 V, a pulse width of 10 s, and a total deposition time of 45 min to form a metal / nitrogen hybrid conductive coating on the electrode surface. The obtained electrode material was carbonized in an argon atmosphere (1000°C, 2 h), and then activated in a CO₂ atmosphere (1000°C, 0.5 h, CO₂ flow rate of 100 mL / min). After cooling, a low internal resistance vanadium redox flow battery electrode material was obtained.

[0056] Example 4

[0057] A method for preparing a low internal resistance vanadium redox flow battery electrode material comprises the following steps:

[0058] (1) A 30 cm × 30 cm graphite felt was selected as the electrode substrate and placed in a mixed plasma with an oxygen to argon gas volume ratio of 4:1 for surface activation treatment at a power of 150 W for 10 min to obtain an activated electrode material;

[0059] (2) Weigh 2 g of bimetallic MAX phase Mo2VAlC2 powder and add it to 20 mL of a mixed solution containing 1.8 mol / L LiF and 2.5 mol / L HCl. Electrochemical etching is performed at a constant current of 10 mA / cm² for 5 h. After the reaction is completed, centrifugal washing is performed with deionized water to a pH of 6 to obtain MXene material.

[0060] (3) Take 1g of the above MXene material, add 20mL of deionized water, add 0.3g of multi-walled carbon nanotubes (CNTs) and 0.02g of hexadecyltrimethylammonium bromide (CTAB), and ultrasonicate for 30min to form a uniform dispersion; completely immerse the activated graphite felt material in the above dispersion, let it stand at room temperature for 1.5h, and then transfer it to a stainless steel autoclave for hydrothermal reaction at 180℃ for 6h. After cooling, take it out and wash it with deionized water, and then dry it to obtain the intermediate product;

[0061] (4) A dopamine hydrochloride solution (5 mg / mL) was prepared, to which FeCl₃ was added so that the molar ratio of FeCl₃ to dopamine was 3:10, thereby obtaining a dopamine hydrochloride solution containing a metal salt. The intermediate product was immersed in the dopamine hydrochloride solution containing a metal salt, maintained at 35°C, and immersed for 30 min. Subsequently, pulse electrodeposition was performed in a three-electrode system with a voltage range of +0.8 V / −0.2 V, a pulse width of 10 s, and a total deposition time of 45 min to form a metal / nitrogen hybrid conductive coating on the electrode surface. The obtained electrode material was carbonized in an argon atmosphere (1000°C, 4 h), then activated in a CO₂ atmosphere (900°C, 1 h, CO₂ flow rate of 110 mL / min), and cooled to obtain a low internal resistance vanadium redox flow battery electrode material.

[0062] Comparative Example 1

[0063] A method for preparing a low internal resistance vanadium redox flow battery electrode material comprises the following steps:

[0064] (1) A 30 cm × 30 cm graphite felt was selected as the electrode substrate and placed in a mixed plasma with an oxygen to argon gas volume ratio of 4:1 for surface activation treatment at a power of 150 W for 10 min to obtain an activated electrode material;

[0065] (2) Weigh 2 g of bimetallic MAX phase TiVAlC powder and add it to 20 mL of a mixed solution containing 1.8 mol / L LiF and 2.5 mol / L HCl. Electrochemical etching is performed at a constant current of 10 mA / cm² for 5 h. After the reaction is completed, the solution is centrifuged and washed with deionized water until the pH reaches 6 to obtain a dispersion.

[0066] (3) Take 1g of the above dispersion, add 20mL of deionized water, add 0.3g of multi-walled carbon nanotubes (CNTs) and 0.02g of hexadecyltrimethylammonium bromide (CTAB), and ultrasonicate for 30min to form a uniform dispersion; the activated graphite felt material is completely immersed in the above dispersion, allowed to stand at room temperature for 1.5h, and then transferred to a stainless steel autoclave for hydrothermal reaction at 180℃ for 6h. After cooling, the material is taken out and washed with deionized water, and dried to obtain an intermediate product; the intermediate product is carbonized in an argon atmosphere (900℃, 3h), and then activated in a CO2 atmosphere (950℃, 0.5h, CO2 flow rate 110mL / min). After cooling, a low internal resistance vanadium redox flow battery electrode material is obtained.

[0067] Comparative Example 2

[0068] A method for preparing a low internal resistance vanadium redox flow battery electrode material comprises the following steps:

[0069] (1) A 30 cm × 30 cm graphite felt was selected as the electrode substrate and placed in a mixed plasma with an oxygen to argon gas volume ratio of 4:1 for surface activation treatment at a power of 150 W for 10 min to obtain an activated electrode material;

[0070] (2) A dopamine hydrochloride solution (4 mg / mL) was prepared, to which FeCl₃ was added so that the molar ratio of FeCl₃ to dopamine was 2:10, to obtain a dopamine hydrochloride solution containing a metal salt. The activated electrode material was immersed in the dopamine hydrochloride solution containing a metal salt, maintained at 35°C, and immersed for 30 minutes. Subsequently, pulse electrodeposition was performed in a three-electrode system with a voltage range of +0.8V / −0.2V, a pulse width of 10s, and a total deposition time of 45 minutes to form a metal / nitrogen hybrid conductive coating on the electrode surface. The obtained electrode material was carbonized in an argon atmosphere (900°C, 3h), then activated in a CO₂ atmosphere (950°C, 0.5h, CO₂ flow rate of 110mL / min), and cooled to obtain a low internal resistance vanadium redox flow battery electrode material.

[0071] The low internal resistance vanadium redox flow battery electrode materials of the embodiment and the comparative example were respectively assembled into all-vanadium redox flow batteries and the battery characteristics were tested. The test results are shown in Tables 1 to 3.

[0072] The preparation conditions of all-vanadium redox flow battery are: the active material in the positive and negative electrolytes is 1.7 mol / LV 4+ / V 5+ and 1.7 mol / LV 2+ / V 3+ The supporting electrolyte is 4 mol / L sulfuric acid, the volume of the positive and negative electrolytes is 70 mL, the proton membrane is a perfluorosulfonic acid proton membrane, and the effective area of ​​the carbon felt electrode is 48 cm 2 , the compression ratio is 25%.

[0073] Test conditions:

[0074] (1) Initial performance: constant current test, the electric density is 150 and 300mA / cm 2 , the upper limit of charge is 1.55V, the lower limit of discharge is 1.00V, and the cycle is repeated 5 times at each density. The data of the 4th cycle is taken as the initial performance.

[0075] (2) Performance after 1000 cycles: constant current test, the electric density is 300mA / cm 2 , the upper limit of charge is 1.55V, the lower limit of discharge is 1.00V, and the cycle is 1000 times.

[0076] Table 1 Coulombic efficiency

[0077] Group Initial coulombic efficiency (150 mA / cm²)% Initial coulombic efficiency (300 mA / cm²)% Coulombic efficiency after 1000 cycles (300 mA / cm²)% Example 1 96.8 96.2 95.5 Example 2 96.4 95.8 94.7 Example 3 97.3 96.9 96.2 Example 4 97.1 96.6 95.9 Comparative Example 1 93.5 92.0 89.4 Comparative Example 2 94.1 93.3 91.2

[0078] Table 2 Voltage efficiency

[0079] Group Initial VE (150 mA / cm²) Initial VE (300 mA / cm²) VE after 1000 cycles (300 mA / cm²) Example 1 89.2% 85.6% 83.1% Example 2 90.4% 87.3% 85.5% Example 3 88.6% 84.2% 81.4% Example 4 91.0% 88.0% 86.8% Comparative Example 1 81.7% 76.5% 70.2% Comparative Example 2 78.3% 72.8% 66.0%

[0080] Table 3 Energy efficiency

[0081] Group Energy efficiency (%) 150 mA / cm² Energy efficiency (%) 300 mA / cm² Energy efficiency after 1000 cycles (%) 300 mA / cm² Example 1 88.7 84.2 82.5 Example 2 89.3 85.0 83.6 Example 3 91.5 86.7 85.1 Example 4 90.2 86.0 84.5 Comparative Example 1 80.1 74.3 70.8 Comparative Example 2 82.4 75.8 72.1

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a low internal resistance vanadium redox flow battery electrode material, characterized in that: The following steps are involved: (1) Plasma activation treatment of the electrode substrate to obtain an activated electrode material; (2) mixing the bimetallic MAX phase compound and a fluorine-containing salt solution, performing electrochemical etching, and obtaining a MXene material after centrifugal washing; (3) Dispersing the MXene material in water, adding carbon nanotubes and surfactant to obtain a dispersion; The activated electrode material is immersed in the dispersion to undergo a hydrothermal reaction to obtain an intermediate product; (4) The intermediate product is immersed in a dopamine hydrochloride solution containing a metal salt, and a coating is formed on the electrode surface by a pulse electrochemical deposition method, followed by carbonization and activation treatments in sequence. After cooling, a low internal resistance vanadium liquid flow battery electrode material is obtained.

2. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (1), the conditions for the plasma activation treatment are: the gas is a mixed atmosphere of oxygen and argon, the volume ratio of oxygen to argon is 4:1, the power is 100~250W, and the time is 5~15min.

3. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (2), the bimetallic MAX phase compound includes Mo2VAlC2 and / or TiVAlC; In step (2), the fluorine-containing salt solution includes LiF and HCl, the concentration of LiF in the fluorine-containing salt solution is 1.5-2 mol / L, and the concentration of HCl in the fluorine-containing salt solution is 2-3 mol / L; In step (2), the usage ratio of the bimetallic MAX phase compound and the fluorine-containing salt solution is 1 g: 10-30 mL.

4. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (2), the electrochemical etching conditions are: current of 10~12mA / cm 2 , time is 4~5h.

5. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (3), the ratio of the MXene material to water is 1 g: 10-30 mL; In step (3), the mass ratio of the MXene material to the carbon nanotubes is 1:0.25-0.5; In step (3), the mass ratio of the MXene material to the surfactant is 1:0.01~0.05; In step (3), the surfactant is hexadecyltrimethylammonium bromide.

6. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (3), the immersion temperature is 20-30°C, and the immersion time is 1-2 hours; In step (3), the temperature of the hydrothermal reaction is 180-200° C., and the time of the hydrothermal reaction is 6-8 h.

7. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (4), the concentration of dopamine hydrochloride in the dopamine hydrochloride solution containing a metal salt is 2 to 5 mg / L; In step (4), the molar ratio of the metal salt to dopamine in the dopamine hydrochloride solution containing the metal salt is 1 to 3:10; In step (4), the metal salt in the dopamine hydrochloride solution containing the metal salt includes FeCl3, CoCl2 or H2PtCl6.

8. The method for preparing a low internal resistance vanadium redox flow battery electrode material according to claim 1, characterized in that: In step (4), the immersion temperature is 30-40°C, and the immersion time is 20-30 minutes; In step (4), the pulse voltage is +0.8V / -0.2V, the pulse width is 10s, and the total deposition time is 30-60min; In step (4), the carbonization atmosphere is an inert gas, the carbonization temperature is 800-1000°C, and the carbonization time is 2-4 hours; In step (4), the atmosphere of the activation treatment is carbon dioxide, the flow rate of carbon dioxide is 100~120mL / min, the temperature of the activation treatment is 900~1000℃, and the time of the activation treatment is 0.5~1h.

9. A low internal resistance vanadium redox flow battery electrode material obtained by the method for preparing a low internal resistance vanadium redox flow battery electrode material according to any one of claims 1 to 8.

10. Use of the low internal resistance vanadium redox flow battery electrode material according to claim 9 in an all-vanadium redox flow battery.