Coffee grounds-derived carbon materials modify carbon fiber electrodes, their preparation methods and applications

Abstract

This invention discloses a carbon fiber electrode modified with coffee grounds-derived carbon material, its preparation method, and its application. The preparation method includes: thermal desizing of carbon fiber woven fabric and hot air oxidation to obtain oxidized carbon fiber woven fabric; mixing dried coffee grounds with an activator, carbonizing the mixture under inert gas protection by wrapping it with carbon paper, separating the carbonization product by acid washing and filtration or pressure filtration, taking the solid for further washing until the acidic substances are completely removed, and drying the product to obtain coffee grounds-derived carbon; grafting polyethyleneimine onto the surface of the coffee grounds-derived carbon using hexachlorocyclotriphosphazene as a multi-arm coupling agent, washing the reaction product, and carbonizing it to obtain nitrogen and phosphorus co-doped coffee grounds-derived carbon; mixing the nitrogen and phosphorus co-doped coffee grounds-derived carbon with a solvent and a binder to form an activated carbon electrode slurry, coating it onto the surface of the oxidized carbon fiber woven fabric, and drying it to obtain the carbon fiber electrode material modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon material.

Description

Technical Field

[0001] This invention relates to the field of new energy materials, specifically to a carbon fiber electrode modified with coffee grounds-derived carbon material, its preparation method, and its application in the preparation of composite material structure supercapacitors. Background Technology

[0002] Composite material structure supercapacitors, as an energy storage device, have advantages such as high power density, fast charging and discharging capability and long cycle life. At the same time, they can also serve as structural components to play a mechanical load-bearing role. Therefore, they are expected to meet the dual needs of high-efficiency energy storage and lightweight structure in fields such as new energy vehicles and aerospace, and have attracted widespread attention.

[0003] Carbon fiber electrodes, as a crucial structural component of composite material supercapacitors, bear the dual responsibility of enriching and storing charge and providing mechanical support, making them a key factor in determining their energy storage and mechanical properties. Composite material supercapacitors require carbon fiber electrodes to possess high specific surface area, well-developed pore structure, excellent mechanical properties, and excellent wetting ability with high-viscosity solid resin electrolytes. However, ordinary carbon fibers have smooth surfaces, small specific surface areas, and high chemical inertness, which are unfavorable for charge accumulation on their surface and sufficient wetting and penetration of the resin electrolyte, limiting the fabrication and application of high-performance composite material supercapacitors. High specific surface area and well-developed pore structure are key factors for achieving charge storage and rapid charge migration in carbon fiber electrodes; therefore, surface activation modification treatment of carbon fibers is necessary.

[0004] Patent specification CN116994885A discloses a carbon fiber electrode for integrated structural energy storage composite materials, its preparation method, and its application in the preparation of integrated structural energy storage composite materials. The preparation method of this patented technology includes: peeling and freeze-drying a biomass carbon source, cutting it into blocks to obtain a biomass carbon source block; mixing the biomass carbon source block with phosphoric acid and water, completely impregnating it, and then freeze-drying it; subjecting the freeze-dried biomass carbon source block to high-temperature carbonization in an inert gas atmosphere; washing and drying the carbonization product to obtain a biomass carbon source-derived porous carbon material; mixing the biomass carbon source-derived porous carbon material with a conductive agent and a binder, coating it onto the surface of a carbon fiber cloth, and drying it to obtain a carbon fiber electrode for integrated structural energy storage composite materials. This patented technology uses biomass carbon sources such as wax apples with porous structures as precursors, and through phosphoric acid and high-temperature activation treatment, obtains a porous carbon material with abundant pore structure and high specific surface area. Then, the obtained biomass carbon source-derived porous carbon material is loaded onto the surface of carbon fibers to prepare a carbon fiber structural electrode material with a micro-nano porous structure.

[0005] Using waste biomass as a precursor to prepare biomass-derived carbon is an effective way to obtain low-cost carbon electrode materials.

[0006] However, while biomass-derived carbon active materials with micro- and nano-porous structures can increase the specific surface area of ​​carbon fibers, they also suffer from high chemical inertness and poor surface accessibility, which hinders the full wetting of carbon fiber electrodes by viscous resin electrolytes. More specifically, the poor interfacial compatibility between the resin electrolyte and carbon fibers makes it difficult for the electrolyte to penetrate into the pores of the carbon fiber electrode, resulting in low specific surface area utilization and limited improvement in the energy storage performance of composite material structure supercapacitors.

[0007] Heteroatom doping can improve the surface wettability of carbon fiber electrodes, promote the formation of new active sites, and even impart additional pseudocapacitance to the electrode material, which is an effective way to improve the capacitance performance of carbon fiber electrodes.

[0008] One of the major challenges in preparing biomass-derived carbon with micro-nano porous structures and heteroatom doping is how to effectively prepare carbon fiber electrode materials for high-performance composite supercapacitors. Summary of the Invention

[0009] To address the aforementioned technical problems and shortcomings in the field, this invention provides a method for preparing a carbon fiber electrode modified with coffee grounds-derived carbon material.

[0010] This invention boasts advantages such as simple process, high efficiency, low cost, and environmental friendliness. Using waste coffee grounds as a biomass precursor, this invention prepares coffee grounds-derived carbon (CGC) with smaller particle sizes through high-temperature activation with a specific activator. Hexachlorocyclotriphosphazene (HCCP) is used as a coupling agent to graft polyethyleneimine as both nitrogen and phosphorus sources, yielding nitrogen-phosphorus co-doped coffee grounds-derived carbon (NPCGC). Finally, the NPCGC is used as an active material to modify carbon fiber electrodes, preparing NPCGC-modified carbon fiber electrode materials. This method effectively improves the specific surface area and porosity of coffee grounds-derived carbon and introduces nitrogen and phosphorus doping structures into the derived carbon structure. Surface modification of the carbon fiber electrode material is achieved through a coating method, modifying carbon fibers with micro / nano-porous structures and heteroatom doping structures, thereby improving the electrochemical performance of the carbon fiber electrode and providing technical support for the development of carbon fiber electrodes for high-performance composite material structure supercapacitors.

[0011] The specific technical solution is as follows:

[0012] A method for preparing a carbon fiber electrode modified with coffee grounds-derived carbon material includes:

[0013] Carbon fiber woven fabric is obtained by thermal desizing and hot air oxidation to produce oxidized carbon fiber woven fabric.

[0014] Dry coffee grounds are mixed with an activator and carbonized under an inert gas atmosphere by wrapping them in carbon paper. The carbonized product is then acid-washed and separated by filtration or pressure filtration. The solid is taken and further washed until the acidic substances are completely removed. The product is dried to obtain coffee grounds-derived carbon. The activator is at least one of potassium hydroxide, zinc chloride, sodium hydroxide, sodium carbonate, and potassium carbonate.

[0015] Polyethyleneimine was grafted onto the surface of coffee grounds-derived carbon using hexachlorocyclotriphosphazene as a multi-arm coupling agent. The reaction product was washed and then carbonized to obtain nitrogen and phosphorus co-doped coffee grounds-derived carbon.

[0016] Nitrogen and phosphorus co-doped coffee grounds-derived carbon was mixed with solvent and binder to form an activated carbon electrode slurry, which was then coated onto the surface of oxidized carbon fiber woven fabric and dried to obtain a carbon fiber electrode material modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon material.

[0017] This invention utilizes pretreated coffee grounds under specific conditions and grafts polyethyleneimine as both a nitrogen and phosphorus source using hexachlorocyclotriphosphazene as a coupling agent. The process involves carbonization in a high-temperature, inert gas atmosphere to prepare coffee grounds-derived carbon with a micro / nano porous structure and heteroatom doping. Finally, the obtained derivative carbon is used to prepare an activated carbon electrode slurry, which is then coated onto the surface of an oxidized carbon fiber cloth, thereby producing a nitrogen- and phosphorus co-doped coffee grounds-derived carbon fiber electrode material.

[0018] In one embodiment, the method for preparing the coffee grounds-derived carbon material-modified carbon fiber electrode involves obtaining oxidized carbon fiber woven fabric by removing a commercial sizing agent through pyrolysis in an inert gas environment. The pyrolysis temperature is 500–700°C, the holding time is 5–6 h, and the heating rate is 1–10°C / min.

[0019] In one embodiment, the method for preparing the coffee grounds-derived carbon material-modified carbon fiber electrode involves obtaining oxidized carbon fiber woven fabric, wherein the hot air oxidation temperature is 300–500°C and the time is 0.5–5 h.

[0020] In one embodiment, the method for preparing the coffee grounds-derived carbon material-modified carbon fiber electrode involves drying the coffee grounds at 80–120°C for 12–24 hours to obtain dried coffee grounds.

[0021] In one embodiment, the method for preparing the coffee grounds-derived carbon material-modified carbon fiber electrode uses a coffee grounds to activator mass ratio of 1:1 to 10.

[0022] In one embodiment, the method for preparing the carbon fiber electrode modified with coffee grounds-derived carbon material involves wrapping the carbon paper with carbon at a temperature of 500–700°C, holding it at that temperature for 2–4 hours, and a heating rate of 1–10°C / min.

[0023] In one embodiment, the method for preparing the coffee grounds-derived carbon material modified carbon fiber electrode uses at least one of acetonitrile, diethyl ether, acetone, ethanol, tetrahydrofuran, and ethyl acetate as the grafting solvent during the process of obtaining nitrogen-phosphorus co-doped coffee grounds-derived carbon.

[0024] In one embodiment, the method for preparing coffee grounds-derived carbon material-modified carbon fiber electrodes involves a stepwise grafting process to obtain nitrogen-phosphorus co-doped coffee grounds-derived carbon. First, hexachlorocyclotriphosphazene is grafted onto the surface of the coffee grounds-derived carbon, and then polyethyleneimine is grafted onto it. The solvent used for grafting is at least one of acetonitrile, diethyl ether, acetone, ethanol, tetrahydrofuran, and ethyl acetate. The grafting process also uses a catalyst, which is independently selected from at least one of triethylamine, pyridine, ammonium sulfate, sodium bicarbonate, and sodium hydroxide.

[0025] In one embodiment, the method for preparing the coffee grounds-derived carbon material modified carbon fiber electrode, specifically the grafting of polyethyleneimine onto the surface of coffee grounds-derived carbon using hexachlorocyclotriphosphazene as a multi-arm coupling agent, followed by washing and carbonization of the reaction product to obtain nitrogen-phosphorus co-doped coffee grounds-derived carbon, includes the following steps: first, mixing the grafting solvent with triethylamine, coffee grounds-derived carbon, and hexachlorocyclotriphosphazene, heating and refluxing at 75-85°C for a full reaction; filtering, washing, and vacuum drying the resulting solid product; then mixing it with the grafting solvent, triethylamine, and polyethyleneimine, heating and refluxing at 75-85°C for a full reaction; washing, vacuum drying, and carbonizing the reaction product to obtain nitrogen-phosphorus co-doped coffee grounds-derived carbon.

[0026] In one embodiment, the method for preparing the coffee grounds-derived carbon material modified carbon fiber electrode involves obtaining nitrogen-phosphorus co-doped coffee grounds-derived carbon in the following steps: the mass ratio of hexachlorocyclotriphosphazene to coffee grounds-derived carbon is 0.05 to 1:1, the mass ratio of hexachlorocyclotriphosphazene to polyethyleneimine is 1:0.5 to 1.5, and the mass ratio of coffee grounds-derived carbon to the volume ratio of the solvent used for grafting is 1 g: 250 to 2500 mL.

[0027] In one embodiment, the method for preparing coffee grounds-derived carbon material-modified carbon fiber electrodes involves obtaining nitrogen-phosphorus co-doped coffee grounds-derived carbon at a carbonization temperature of 400–700°C, a holding time of 2–4 h, and a heating rate of 1–5°C / min.

[0028] In one embodiment, the method for preparing the coffee grounds-derived carbon material-modified carbon fiber electrode uses at least one of N-methylpyrrolidone, isopropanol, N,N-dimethylformamide, and ethanol as the solvent for preparing the activated carbon electrode slurry.

[0029] In one embodiment, the method for preparing the coffee grounds-derived carbon material modified carbon fiber electrode uses a nitrogen-phosphorus co-doped coffee grounds-derived carbon with a solvent and binder ratio of 0.2-2g:2-20mL:0.02-0.2g.

[0030] In one embodiment, the method for preparing the coffee grounds-derived carbon material-modified carbon fiber electrode involves coating 0.01 to 0.1 mL of activated carbon electrode slurry per square centimeter of oxidized carbon fiber woven fabric.

[0031] The present invention also provides a carbon fiber electrode material modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon material prepared by the above preparation method.

[0032] This invention also provides the application of the nitrogen-phosphorus co-doped coffee grounds-derived carbon fiber electrode material modified in the preparation of composite material structure supercapacitors.

[0033] Compared with the prior art, the beneficial effects of this invention are as follows:

[0034] 1. A nitrogen-phosphorus co-doped coffee grounds-derived carbon material is provided for preparing carbon fiber electrodes of composite material structure supercapacitors using waste coffee grounds as biomass raw materials.

[0035] 2. Based on biomass raw material coffee grounds, a nitrogen source is introduced by grafting polyethyleneimine with hexachlorocyclotriphosphazene as a coupling agent, which provides nitrogen and phosphorus sources for the high-temperature carbonization process of coffee grounds, and realizes the preparation of nitrogen and phosphorus co-doped derived carbon.

[0036] 3. During the carbonization process, nitrogen and phosphorus atoms from polyethyleneimine and hexachlorocyclotriphosphazene can be incorporated into the carbon structure of coffee grounds-derived carbon, which is beneficial to improving the electrochemical performance of modified coffee grounds-derived carbon materials.

[0037] 4. During the high-temperature carbonization process, the activator of this invention is beneficial to control the size and internal pore structure of coffee grounds-derived carbon materials. The prepared NPCGC particles are small in size, which is conducive to their adhesion to the carbon fiber surface and improves the modification effect on carbon fiber electrodes.

[0038] 5. The accumulation of fine carbon particles can also form a large number of porous structures, which can construct a continuous pore structure with micro-nano multi-scale on the surface of carbon fibers. This is beneficial to improve the specific surface area of ​​carbon fiber electrodes, enhance the wettability of electrolytes in electrodes, and improve the storage capacity and transport rate of charges inside electrodes. Attached Figure Description

[0039] Figure 1 Microstructure morphology images of carbon fiber electrodes: (a) ordinary carbon fiber electrode material, (b) carbon fiber electrode modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0042] T300 grade carbon fiber woven fabric (carbon fiber microstructure morphology as shown) Figure 1 (a) The carbon fiber woven fabric was placed in a tube furnace and treated at 500°C for 5 hours under argon protection. The sizing agent on the surface was removed by high-temperature thermal desizing. After cooling to room temperature, it was taken out for use. The desized carbon fiber woven fabric was oxidized in a muffle furnace at 400°C for 2 hours to obtain oxidized carbon fiber woven fabric (CFO).

[0043] The collected coffee grounds were dried in a forced-air oven at 120°C for 12 hours. They were then mixed with zinc chloride at a mass ratio of 1:10, ground and thoroughly mixed using an agate mortar. Under nitrogen protection, the mixture was wrapped in carbon paper and placed in a tube furnace, heated to 600°C at a rate of 5°C / min and held for 2 hours, then allowed to cool naturally to room temperature. With the aid of a magnetic stirrer, the cooled product was washed with 1 mol / L dilute hydrochloric acid, then repeatedly rinsed with deionized water until the pH was neutral. Finally, the washed product was dried in a forced-air oven for 24 hours to obtain coffee grounds-derived carbon (CGC).

[0044] Weigh 0.2 g of CGC and 0.1 g of hexachlorocyclotriphosphazene into a round-bottom flask, add 100 mL of acetonitrile and 5 mL of triethylamine, reflux at 80 °C for 2 h, filter and wash to remove unreacted hexachlorocyclotriphosphazene, dry the product under vacuum, transfer to a round-bottom flask, add another 100 mL of acetonitrile, 5 mL of triethylamine and 0.1 g of polyethyleneimine, reflux at 80 °C for 2 h. Wash the reaction product clean and dry under vacuum, place it in a tube furnace, heat to 400 °C at a rate of 5 °C / min and hold for 2 h, then cool to room temperature to obtain nitrogen-phosphorus co-doped coffee grounds-derived carbon (NPCGC).

[0045] 0.2 g of NPCGC was weighed and placed in a sample vial, along with 0.02 g of polyvinylidene fluoride and 2 mL of N-methylpyrrolidone. The mixture was stirred with a magnetic stirrer for 0.5 h to obtain an NPCGC slurry. Oxidized carbon fiber woven fabric was cut into 2 cm × 1.5 cm pieces, and copper sheets were used as electrode tabs to prepare unmodified carbon fiber electrodes. 0.08 mL of coffee grounds-derived carbon slurry was coated onto each electrode piece, and the pieces were dried in a vacuum oven at 80 °C for 12 h. After cooling to room temperature, the coffee grounds-derived carbon modified carbon fiber electrode NPCGC-5@CFO (5 wt% NPCGC) was obtained. The microstructure morphology is shown in the image below. Figure 1 As shown in (b), by changing the amount of coffee grounds-derived carbon slurry used to 0.15 mL and 0.3 mL, two modified carbon fiber electrodes, NPCGC-10@CFO (10 wt% NPCGC) and NPCGC-20@CFO (20 wt% NPCGC), can be prepared by the same method.

[0046] A composite resin-based electrolyte was prepared by uniformly mixing polyethylene glycol diglycidyl ether resin (PEGDGE), polyetheramine (D-230), and ionic liquid (EMIMTFSI) at a mass ratio of 81.6:18.4:100. A glass fiber cloth was sandwiched between two nitrogen-phosphorus co-doped coffee grounds-derived carbon fiber electrode sheets. The carbon / glass fiber sandwich structure was thoroughly impregnated with the resin-based electrolyte. The mixture was cured in a vacuum oven at 120°C for 2 hours with the aid of a flat mold. After cooling to room temperature, it was demolded to obtain a composite supercapacitor. Similarly, a composite supercapacitor was prepared using unmodified coffee grounds-derived carbon fiber as the electrode, following the same method, as a comparison.

[0047] As shown in Table 1, when the current density is 0.5 mA / cm² 2 At that time, the specific capacitances of the composite material structure supercapacitors fabricated from unmodified CFO, NPCGC-5@CFO, NPCGC-10@CFO, and NPCGC-20@CFO electrodes were 0.4, 52.3, 72.5, and 98.2 mF / cm, respectively. 2 .

[0048] Table 1

[0049]

[0050] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing a carbon fiber electrode modified with coffee grounds-derived carbon material, characterized in that, include: Carbon fiber woven fabric is obtained by thermal desizing and hot air oxidation to produce oxidized carbon fiber woven fabric. Dry coffee grounds are mixed with an activator and carbonized under an inert gas atmosphere by wrapping them in carbon paper. The carbonized product is then acid-washed and separated by filtration or pressure filtration. The solid is taken and further washed until the acidic substances are completely removed. The product is dried to obtain coffee grounds-derived carbon. The activator is at least one of potassium hydroxide, zinc chloride, sodium hydroxide, sodium carbonate, and potassium carbonate. Polyethyleneimine was grafted onto the surface of coffee grounds-derived carbon using hexachlorocyclotriphosphazene as a multi-arm coupling agent. The reaction product was washed and then carbonized to obtain nitrogen and phosphorus co-doped coffee grounds-derived carbon. Nitrogen and phosphorus co-doped coffee grounds-derived carbon was mixed with solvent and binder to form an activated carbon electrode slurry, which was then coated onto the surface of oxidized carbon fiber woven fabric and dried to obtain a carbon fiber electrode material modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon material.

2. The preparation method according to claim 1, characterized in that, In the process of obtaining oxidized carbon fiber woven fabric: Commercial sizing agents are removed by pyrolysis in an inert gas environment. The pyrolysis temperature is 500-700℃, the holding time is 5-6h, and the heating rate is 1-10℃ / min. The temperature for hot air oxidation is 300–500℃, and the time is 0.5–5 hours.

3. The preparation method according to claim 1, characterized in that, Dry coffee grounds are obtained by drying at 80-120℃ for 12-24 hours; The mass ratio of coffee grounds to activator is 1:1 to 10; The carbonization temperature for wrapping with carbon paper is 500–700℃, the holding time is 2–4 hours, and the heating rate is 1–10℃ / min.

4. The preparation method according to claim 1, characterized in that, In the process of obtaining nitrogen-phosphorus co-doped coffee grounds-derived carbon, a stepwise grafting method is adopted. First, hexachlorocyclotriphosphazene is grafted onto the surface of the coffee grounds-derived carbon, and then polyethyleneimine is grafted onto it. The solvent used for grafting is at least one of acetonitrile, diethyl ether, acetone, ethanol, tetrahydrofuran, and ethyl acetate. A catalyst is also used in the grafting process. The catalyst is independently selected from at least one of triethylamine, pyridine, ammonium sulfate, sodium bicarbonate, and sodium hydroxide.

5. The preparation method according to claim 1 or 4, characterized in that, In the process of obtaining nitrogen and phosphorus co-doped coffee grounds-derived carbon: The mass ratio of hexachlorocyclotriphosphazene to coffee grounds-derived carbon is 0.05 to 1:1, the mass ratio of hexachlorocyclotriphosphazene to polyethyleneimine is 1:0.5 to 1.5, and the mass ratio of coffee grounds-derived carbon to the volume ratio of the solvent used for grafting is 1 g: 250 to 2500 mL. The carbonization temperature is 400–700℃, the holding time is 2–4 hours, and the heating rate is 1–5℃ / min.

6. The preparation method according to claim 1, characterized in that, The solvent for preparing the activated carbon electrode slurry is at least one of N-methylpyrrolidone, isopropanol, N,N-dimethylformamide, and ethanol.

7. The preparation method according to claim 1 or 6, characterized in that, The ratio of nitrogen-phosphorus co-doped coffee grounds-derived carbon to solvent and binder is 0.2–2 g: 2–20 mL: 0.02–0.2 g; The slurry coating amount is 0.01 to 0.1 mL of activated carbon electrode slurry per square centimeter of oxidized carbon fiber woven fabric.

8. The carbon fiber electrode material modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon material prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the carbon fiber electrode material modified with nitrogen and phosphorus co-doped coffee grounds-derived carbon material according to claim 8 in the preparation of composite material structure supercapacitors.

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