A biomass-modified iron-chromium flow battery carbon cloth electrode and its preparation method

Abstract

This invention relates to the field of flow battery energy storage technology, specifically disclosing a biomass-modified carbon cloth electrode for an iron-chromium flow battery and its preparation method, comprising the following steps: cleaning the carbon cloth with deionized water, immersing it in ethanol, then ultrasonically cleaning it in deionized water, drying it in an oven, and then activating the carbon cloth with high-temperature heat treatment; adding biomass powder to deionized water, then adding an auxiliary agent, stirring the resulting mixture, and ultrasonically treating it to form a precursor slurry; immersing the heat-treated carbon cloth in the precursor slurry using an impregnation method, and then drying the carbon cloth; removing the carbon cloth and calcining it at high temperature in a tube furnace under a protective atmosphere for carbothermic reduction to obtain a biomass-modified carbon cloth electrode. This invention achieves a nitrogen-doping effect on the surface of the carbon cloth through biomass modification, which can enhance the electrochemical reaction activity of chromium ions and simultaneously improve the energy efficiency of the iron-chromium flow battery.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage of flow batteries, and particularly relates to a biomass-modified carbon cloth electrode for an iron-chromium flow battery and a preparation method thereof. Background Art

[0002] Due to the intermittency and randomness of renewable energy sources such as wind power and photovoltaic power generation, large-scale integration into the power grid will bring serious impacts to the safe and stable operation of the power grid. Therefore, there is an urgent need for large-scale energy storage technologies to achieve peak shaving and valley filling of the power grid, thereby improving the power grid's ability to absorb renewable energy power generation and solving problems such as wind abandonment and light abandonment.

[0003] The iron-chromium flow battery is an energy storage technology with broad application prospects. Compared with traditional lead-acid batteries and lithium-ion batteries, flow batteries have significant advantages in terms of lifespan, efficiency, and safety. ICFB uses iron and chromium as active materials, and realizes the storage and release of energy through redox reactions in the electrolyte solution. This technology is particularly suitable for large-scale energy storage systems, such as power grid peak shaving and energy storage supporting renewable energy power generation.

[0004] In an iron-chromium flow battery, the electrode material is one of the key factors determining the battery performance. The carbon cloth electrode has become a commonly used electrode material in flow batteries due to its high conductivity, good chemical stability, and large specific surface area. However, the carbon cloth electrode itself has some deficiencies, such as low electrochemical activity and low catalytic activity, which limit the overall performance of the iron-chromium flow battery. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a biomass-modified carbon cloth electrode for an iron-chromium flow battery and a preparation method thereof. By using technologies such as high-temperature heat treatment, impregnation method, high-temperature calcination, and carbothermal reduction method to modify the carbon cloth with biomass materials, it provides abundant high-catalytic activity sites for the redox reaction of the iron-chromium flow battery electrolyte, promotes the redox reaction of the iron-chromium flow battery electrolyte by using the formed more oxygen-containing functional groups, improves the conductivity of the carbon cloth electrode, optimizes the growth environment of the catalyst, improves the electrochemical performance of the prepared electrode material, brings a high improvement to the battery performance, and solves the problems mentioned in the above background art.

[0006] To achieve the above object, the present invention provides the following technical solution: A preparation method of a biomass-modified carbon cloth electrode for an iron-chromium flow battery, comprising the following steps:

[0007] S1. Carbon cloth pretreatment: Wash the carbon cloth with deionized water, soak it in ethanol after washing, then ultrasonically wash it in deionized water, put the ultrasonically washed carbon cloth into an oven for drying, and then activate the carbon cloth by high-temperature heat treatment;

[0008] S2. Preparation of precursor slurry: Add biomass powder to deionized water, then add auxiliary agents to obtain a mixture. Stir the mixture and sonicate it to form a precursor slurry.

[0009] S3. Impregnation: The carbon cloth after high-temperature heat treatment is immersed in the precursor slurry and treated by impregnation method, and then the carbon cloth is dried.

[0010] S4. Carbothermic reduction: The carbon cloth obtained in step S3 is taken out and calcined at high temperature in a tube furnace under a protective atmosphere to carry out carbothermic reduction, thereby obtaining a biomass-modified carbon cloth electrode.

[0011] Preferably, in step S1, the carbon cloth is polyacrylonitrile (PNV) based carbon cloth, rayon based carbon cloth, or petroleum pitch based carbon cloth; the soaking time in ethanol is 10–20 min; the ultrasonic cleaning time is 10–100 min; and the drying temperature in the oven is 30–150 °C.

[0012] Preferably, in step S1, the high-temperature heat treatment to activate the carbon cloth involves placing the carbon cloth in a muffle furnace and subjecting it to high-temperature heat treatment in an atmosphere of one or more mixed gases selected from air, helium, nitrogen, argon, xenon, and neon; the temperature of the high-temperature heat treatment is 200–800°C, and the holding time is 1–20 hours.

[0013] Preferably, in step S2, the biomass powder is one or more of grapefruit peel powder, tangerine peel powder, orange peel powder, and lemon peel powder, and its mass fraction in the final precursor slurry is 1% to 30%.

[0014] Preferably, in step S2, the auxiliary agent acts as a binder, specifically one or more of sucrose, glucose, lactose, and fructose, with a concentration of 0.1–5 mol / L.

[0015] Preferably, in step S2, the stirring time is 10-100 min; the ultrasonic time is 10-100 min.

[0016] Preferably, in step S3, the impregnation time is 10 to 200 minutes; when drying the carbon cloth, the drying temperature is 30 to 150°C and the drying time is 1 to 20 hours.

[0017] Preferably, in step S4, during carbothermic reduction, the calcination temperature is 500–2000°C, the protective atmosphere is one or more mixed gases selected from helium, nitrogen, argon, xenon, and neon, the heating rate during the reaction is 1–30°C / min, and the holding time is 1–20 h.

[0018] On the other hand, in order to achieve the above objectives, the present invention also provides the following technical solution: an electrode material prepared according to the above preparation method.

[0019] The beneficial effects of this invention are:

[0020] 1) This invention modifies and transforms carbon cloth electrodes using biomass materials, resulting in higher energy efficiency, specific capacity, coulombic efficiency, and more stable cycle performance in battery cycling compared to unmodified materials; it can effectively improve the electrochemical performance and catalytic activity of the electrodes.

[0021] 2) This invention utilizes biomass materials to prepare modified iron-chromium redox flow battery electrode materials to improve battery performance. The method is simple, the raw material cost is low, and it is suitable for large-scale commercial preparation. It is a method that can promote the development of iron-chromium redox flow batteries.

[0022] 3) This invention utilizes a carbothermal reaction on a biomass-modified carbon cloth electrode. This carbothermal reaction forms carbides embedded in the pores of the worm-like biomass on the electrode surface, increasing the redox area and providing a richer effective surface for chemical reactions. Furthermore, the biomass modification achieves a nitrogen-doped effect on the carbon cloth surface, enhancing the electrochemical reactivity of chromium ions, improving the energy efficiency of the iron-chromium redox flow battery, slowing capacity decay, and improving cycle stability. The modified electrode has a larger specific surface area, introduces more oxygen-containing functional groups such as hydroxyl, aldehyde, and carboxyl groups, increases hydrophilicity, increases the number of active sites, and enhances the kinetics and reversibility of redox reactions. This modified electrode is effective for Fe... 2+ / Fe 3+ and Cr 3+ / Cr 2+ Redox reactions exhibit significant electrocatalytic activity. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the worm-like biomass pores of the biomass-modified carbon cloth electrode prepared in Example 1 of the present invention.

[0024] Figure 2 This is a comparison chart of the coulombic efficiency of the biomass-modified carbon cloth electrode prepared in Example 1 of the present invention and the original unmodified carbon cloth electrode.

[0025] Figure 3 This is a comparison chart of the energy efficiency of the biomass-modified carbon cloth electrode prepared in Example 1 of the present invention and the original unmodified electrode.

[0026] Figure 4 This is a comparison chart of the voltage efficiency of the biomass-modified carbon cloth electrode prepared in Example 1 of the present invention and the original unmodified electrode;

[0027] Figure 5 This is a schematic diagram of the electrochemical performance of the biomass-modified carbon cloth electrode prepared in Example 1 of the present invention;

[0028] Figure 6 This is a schematic diagram of the electrochemical performance of the biomass-modified carbon cloth electrode prepared in Example 2 of the present invention;

[0029] Figure 7 This is a schematic diagram of the electrochemical performance of the biomass-modified carbon cloth electrode prepared in Example 3 of the present invention;

[0030] Figure 8 This is a schematic diagram of the electrochemical performance of the biomass-modified carbon cloth electrode prepared in Example 4 of the present invention;

[0031] Figure 9 The figure shows the improved hydrophilicity of the biomass-modified carbon cloth electrode prepared in this invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] After cleaning the carbon cloth with deionized water, soak it in alcohol for 10 minutes, then ultrasonically clean the carbon cloth material with deionized water for 10 minutes and place it in an oven to dry at 80°C to remove impurities from the surface of the carbon cloth material.

[0035] The carbon cloth was placed in a muffle furnace and subjected to high-temperature heat treatment at 450°C in air for 5 hours. 15g of grapefruit peel powder was added to 200.0ml of deionized water and mixed with 10.0ml of 0.2M sucrose solution. The resulting mixture was stirred for 10 minutes and ultrasonically treated for 10 minutes to form a slurry. The carbon cloth was immersed in the precursor slurry for 1 hour, followed by drying at 70°C.

[0036] The treated carbon cloth was placed in a tube furnace high-temperature equipment and subjected to high-temperature heat treatment at 1200℃ in a nitrogen atmosphere. The heating rate during the reaction process was 5℃ / min, and the holding time was 4h.

[0037] Carbothermic reactions were carried out on carbon cloth electrodes modified with biomass materials, such as... Figure 1As shown, the carbothermic reaction can form carbides embedded in the pores of worm-like biomass on the electrode surface, increasing the redox area at the electrode and providing a richer effective area for chemical reactions.

[0038] The carbon cloth electrode modified with biomass materials was compared with the original unmodified material in battery cycling tests (coulombic efficiency, energy efficiency, and voltage efficiency). The comparison results are as follows: Figure 2 , Figure 3 and Figure 4 As shown in the comparison, the modified carbon cloth electrode using biomass materials exhibits higher coulombic efficiency, energy efficiency, voltage efficiency, and more stable cycle performance in battery cycling compared to the original unmodified material; it can effectively improve the electrochemical performance and catalytic activity of the electrode.

[0039] The electrochemical test results of the obtained biomass-modified carbon cloth electrode material are shown in the figure. Figure 5 The oxidation and reduction peaks of the electrode prepared in the figure also showed more symmetry and less separation, indicating strong electrocatalytic activity.

[0040] Example 2

[0041] After cleaning the carbon cloth with deionized water, soak it in alcohol for 10 minutes, then ultrasonically clean the carbon cloth material with deionized water for 10 minutes and place it in an oven to dry at 95°C to remove impurities from the surface of the carbon cloth material.

[0042] The carbon cloth was placed in a muffle furnace and subjected to high-temperature heat treatment at 500°C in air for 5 hours. 20g of orange peel powder was added to 200.0ml of deionized water and mixed with 10.0ml of 0.15M sucrose solution. The resulting mixture was stirred for 10 minutes and sonicated for 15 minutes to form a slurry. The carbon cloth was immersed in the precursor slurry for 1 hour, followed by drying at 70°C.

[0043] The treated carbon cloth was placed in a tube furnace high-temperature equipment and subjected to high-temperature heat treatment at 1200℃ in a nitrogen atmosphere. The heating rate during the reaction process was 5℃ / min, and the holding time was 5h.

[0044] The electrochemical test results of the obtained biomass-modified carbon cloth electrode material are shown in the figure. Figure 6 The oxidation and reduction peaks of the electrode prepared in the figure also showed more symmetry and less separation, indicating strong electrocatalytic activity.

[0045] Example 3

[0046] After cleaning the carbon cloth with deionized water, soak it in alcohol for 10 minutes, then ultrasonically clean the carbon cloth material with deionized water for 10 minutes and place it in an oven to dry at 85°C to remove impurities from the surface of the carbon cloth material.

[0047] The carbon cloth was placed in a muffle furnace and subjected to high-temperature heat treatment at 540°C in air for 5 hours. 20g of orange peel powder was added to 200.0ml of deionized water and mixed with 10.0ml of 0.1M glucose solution. The resulting mixture was stirred for 10 minutes and sonicated for 15 minutes to form a slurry. The carbon cloth was immersed in the precursor slurry for 1 hour, followed by drying at 75°C.

[0048] The treated carbon cloth was placed in a tube furnace high-temperature equipment and subjected to high-temperature heat treatment at 1150℃ in a nitrogen atmosphere. The heating rate during the reaction process was 5℃ / min, and the holding time was 5h.

[0049] The electrochemical test results of the obtained biomass-modified carbon cloth electrode material are shown in the figure. Figure 7 .

[0050] Example 4

[0051] After cleaning the carbon cloth with deionized water, soak it in alcohol for 10 minutes, then ultrasonically clean the carbon cloth material with deionized water for 10 minutes and place it in an oven to dry at 90°C to remove impurities from the surface of the carbon cloth material.

[0052] The carbon cloth was placed in a muffle furnace and subjected to high-temperature heat treatment at 500°C in air for 4 hours. 20g of lemon peel powder was added to 200.0ml of deionized water and mixed with 10.0ml of 0.1M fructose solution. The resulting mixture was stirred for 15 minutes and sonicated for 15 minutes to form a slurry. The carbon cloth was immersed in the precursor slurry for 2 hours, followed by drying at 85°C.

[0053] The treated carbon cloth was placed in a tube furnace high-temperature equipment and subjected to high-temperature heat treatment at 1200℃ in a nitrogen atmosphere. The heating rate during the reaction process was 5℃ / min, and the holding time was 5h.

[0054] The electrochemical test results of the obtained biomass-modified carbon cloth electrode material are shown in the figure. Figure 8 Its hydrophilic properties are as follows Figure 9 As shown in the figure, the hydrophilicity of the biomass-modified carbon cloth electrode is significantly improved compared to the unmodified original electrode.

[0055] This invention proposes a method for modifying carbon cloth electrodes for iron-chromium redox flow batteries using biomass materials, thereby improving battery performance by preparing modified iron-chromium redox flow battery electrode materials using biomass materials.

[0056] Meanwhile, biomass materials are widely available, inexpensive, and environmentally friendly, making them ideal materials for modifying carbon cloth electrodes. Modifying carbon cloth electrodes using biomass materials can effectively enhance their electrochemical performance and catalytic activity, demonstrating significant research value and broad application prospects.

[0057] The biomass-modified carbon cloth electrode prepared by this invention can enhance the electrochemical reaction activity of chromium ions by forming nitrogen doping on the surface of carbon cloth through biomass modification. At the same time, it can improve the energy efficiency of iron-chromium redox flow batteries, slow down the capacity decay of batteries, and improve cycle stability. It is of great significance to the field of iron-chromium redox flow battery electrode manufacturing and has excellent prospects for promotion and application.

[0058] The present invention has a simple operation method, low raw material cost, and existing production processes are fully capable of manufacturing the method of the present invention, making it easy to promote. It is an electrode material manufacturing method that can greatly promote the commercialization of iron-chromium redox flow batteries and drive the better commercialization of iron-chromium redox flow batteries.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Unless otherwise specified, all means employed in this specification are existing techniques in the art.

[0060] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a biomass-modified iron-chromium flow battery carbon cloth electrode, characterized in that, The preparation process involves a carbothermic reaction of a biomass-modified carbon cloth electrode to form carbides embedded in the pores of worm-like biomass on the electrode surface. The specific steps include the following: S1. Carbon cloth pretreatment: The carbon cloth is cleaned with deionized water, then soaked in ethanol, and then ultrasonically cleaned in deionized water. The ultrasonically cleaned carbon cloth is placed in an oven to dry, and then activated by high-temperature heat treatment. S2. Preparation of precursor slurry: Biomass powder is added to deionized water, then an auxiliary agent is added to obtain a mixture. The mixture is stirred and ultrasonically treated to form a precursor slurry. The biomass powder is one or more of grapefruit peel powder, tangerine peel powder, orange peel powder, and lemon peel powder, and its mass fraction in the final precursor slurry is 1% to 30%. The auxiliary agent is one or more of sucrose, glucose, lactose, and fructose. S3. Impregnation: The carbon cloth after high-temperature heat treatment is immersed in the precursor slurry and treated by impregnation method, and then the carbon cloth is dried. S4. Carbothermic reduction: The carbon cloth obtained in step S3 is taken out and calcined at high temperature in a tube furnace under a protective atmosphere to carry out carbothermic reduction, thereby obtaining a biomass-modified carbon cloth electrode.

2. The method for preparing the biomass-modified iron-chromium flow battery carbon cloth electrode according to claim 1, characterized in that: In step S1, the carbon cloth is polyacrylonitrile-based carbon cloth, rayon-based carbon cloth, or petroleum pitch-based carbon cloth; the soaking time in ethanol is 10-20 min; the ultrasonic cleaning time is 10-100 min; and the drying temperature in the oven is 30-150 ℃.

3. The method for preparing the biomass-modified iron-chromium flow battery carbon cloth electrode according to claim 1, characterized in that: In step S1, the high-temperature heat treatment to activate the carbon cloth involves placing the carbon cloth in a muffle furnace and subjecting it to high-temperature heat treatment in an atmosphere of one or more mixed gases selected from air, helium, nitrogen, argon, xenon, and neon. The temperature of the high-temperature heat treatment is 200–800 °C, and the holding time is 1–20 h.

4. The method for preparing the biomass-modified iron-chromium flow battery carbon cloth electrode according to claim 1, characterized in that: In step S2, the concentration of the auxiliary agent is 0.1–5 mol / L.

5. The method for preparing the biomass-modified iron-chromium flow battery carbon cloth electrode according to claim 1, characterized in that: In step S2, the stirring time is 10 to 100 min; the ultrasonic time is 10 to 100 min.

6. The method for preparing the biomass-modified iron-chromium flow battery carbon cloth electrode according to claim 1, characterized in that: In step S3, the impregnation time is 10 to 200 min; when drying the carbon cloth, the drying temperature is 30 to 150°C and the drying time is 1 to 20 h.

7. The method for preparing the biomass-modified iron-chromium flow battery carbon cloth electrode according to claim 1, characterized in that: In step S4, during carbothermic reduction, the calcination temperature is 500–2000 °C, the protective atmosphere is one or more mixed gases selected from helium, nitrogen, argon, xenon, and neon, the heating rate during the reaction is 1–30 °C / min, and the holding time is 1–20 h.

8. An electrode material prepared by the preparation method according to any one of claims 1 to 7.

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