Recycled cellulose acetate fiber modified asphalt-based supercapacitor electrode material and preparation method thereof

Abstract

The invention provides a recycled cellulose acetate fiber modified asphalt-based supercapacitor electrode material and a preparation method thereof. The supercapacitor electrode material with high specific surface area, multi-stage pore structure and excellent electrochemical performance is prepared by recycling the cellulose acetate fiber filter element in the waste cigarette end, mixing the cellulose acetate fiber filter element with the asphalt in proportion, adding the activating agent and performing high-temperature carbonization. The method comprises the following steps: (1) separating, crushing and drying the waste cellulose acetate fiber filter element; (2) uniformly mixing with asphalt and an activating agent to form a carbonized matrix; (3) heating and carbonizing in an inert atmosphere, and cleaning and drying a product; and (4) preparing a working electrode. The prepared electrode material shows excellent electrochemical performance, and the specific capacitance, the cycle life and the rate capability of the supercapacitor are remarkably improved. The cellulose acetate fibers in the waste cigarette ends are creatively used as the pore-forming template, so that the problem of cigarette end pollution is solved, and high-valued recovery of waste resources is realized. The process is simple, green, environment-friendly and low in cost, and has industrial application potential and good economic and social benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy materials, and in particular relates to a recycled cellulose acetate modified asphalt-based supercapacitor electrode material and a preparation method thereof. Background Art

[0002] Every year, about 5.7 trillion cigarette butts (1.2 million tons) are discarded in the natural environment. Discarded cigarette butts have become a serious source of environmental pollution. The acetate fiber filter contained in cigarette butts poses a long-term threat to soil, water bodies and food chains due to its difficult-to-degrade characteristics. It not only puts tremendous pressure on the ecological environment, but also reflects the problem of resource waste. Therefore, the development of recycling and high-value utilization technology for discarded cigarette butt resources is of great significance to reducing environmental pollution and achieving resource regeneration.

[0003] Asphalt is an important by-product in the petroleum industry. Its efficient conversion and high-value utilization are crucial to promoting the green and high-quality development of the petroleum industry. In recent years, research on asphalt in the field of electrode materials has received extensive attention, especially its potential in the preparation of high-performance supercapacitor electrode materials. Asphalt is rich in carbon elements. Through reasonable modification and activation, porous carbon materials with excellent performance can be prepared to achieve efficient utilization of resources.

[0004] As a new type of energy storage device, supercapacitors show great application prospects in the field of energy storage with their high power density, fast charge and discharge capabilities and ultra-long cycle life. However, the electrochemical performance of supercapacitors is highly dependent on the characteristics of electrode materials, including specific surface area, pore structure and conductivity. Therefore, the development of high-performance electrode materials has become the key to improving the performance of supercapacitors.

[0005] Asphalt-based electrode materials have gradually become a research hotspot due to their excellent structural adjustability and cost advantages. However, the optimization of the pore structure of asphalt-based materials still faces technical bottlenecks. By introducing suitable pore-forming agents and carbon sources, the specific surface area and pore structure of the material can be significantly improved, thereby improving its electrochemical performance. The acetate fiber in discarded cigarette butts has strong thermal volatility and good pore-forming potential. Combining it with asphalt-based materials can not only effectively optimize the pore structure of electrode materials, but also realize the resource utilization of waste. This method provides a new idea for optimizing the performance of supercapacitor electrode materials, and also makes an important contribution to solving the environmental pollution problem of discarded cigarette butts. It has broad application prospects and important practical significance. Summary of the invention

[0006] The purpose of the present invention is to provide a recycled acetate fiber modified asphalt-based supercapacitor electrode material and a preparation method thereof, by efficiently recycling waste acetate fiber and combining it with asphalt, using activation technology and optimizing the carbonization process, to prepare an electrode material with a high specific surface area, a multi-level pore structure and excellent electrochemical properties.

[0007] In view of the shortcomings of the prior art, the present invention proposes a preparation method of recycled acetate fiber modified asphalt-based electrode materials, which utilizes recycled acetate fiber to strengthen pore formation and combines it with an activated carbonization process to prepare high-performance electrode materials, thereby achieving high-value recycling of waste acetate fiber and taking into account both environmental governance and the dual improvement of supercapacitor energy storage material performance.

[0008] The technical solution of the present invention is a method for recycling acetate fiber modified asphalt-based supercapacitor electrode material and preparing the same, comprising the following steps: (1) Recovery and pretreatment of acetate fiber: The acetate fiber filter element collected from discarded cigarette butts is separated from the cigarette paper and residual tobacco, the filter element is crushed into uniform particles, and dried at 50-60°C to obtain recycled acetate fiber; (2) Preparation of carbonized matrix: Recycled cellulose acetate and asphalt are mixed in proportion, with the mass fraction of cellulose acetate being 10-60 wt%. An activator is added to the above mixture, and the mixture is ground evenly using an agate mortar and then transferred to a nickel square crucible and covered; (3) High temperature carbonization: Place the crucible in a tube furnace under an inert atmosphere, heat from room temperature to 180-210°C and maintain for 20-40 minutes, then increase the temperature to 750-820°C at a rate of 4-7°C / min and keep warm for 1-2 hours. After carbonization, the product is washed with deionized water and 1 mol / L hydrochloric acid in sequence until neutral, and finally dried in a forced air oven at 80-100°C for 10-24 hours; (4) Electrode preparation and testing: The prepared porous carbon, acetylene black and polytetrafluoroethylene emulsion were mixed in a mass ratio of 85:10:5, 8-15 mL of anhydrous ethanol was added and ultrasonically dispersed for 30-60 min. After drying to constant weight, the carbon sheet with a diameter of 8 mm and a weight of 2 mg was pressed at 3-6 MPa. The carbon sheet was combined with a nickel foam current collector with a diameter of 15 mm to form a working electrode.

[0009] The aforementioned recycled cellulose acetate modified asphalt-based supercapacitor electrode material and preparation method thereof are characterized in that: in the step (2), the activator is potassium hydroxide, zinc chloride or potassium carbonate.

[0010] The aforementioned recycled cellulose acetate modified asphalt-based supercapacitor electrode material and preparation method thereof are characterized in that: in the step (3), the inert atmosphere is nitrogen or argon.

[0011] The aforementioned recycled cellulose acetate modified asphalt-based supercapacitor electrode material and preparation method thereof are characterized in that: in the step (4), the prepared working electrode can be used to assemble a supercapacitor.

[0012] The beneficial effects of the present invention are as follows: (1) a recycled acetate fiber modified asphalt-based supercapacitor electrode material with excellent electrochemical properties and stable structure and a preparation method thereof are provided; (2) the acetate fiber in discarded cigarette butts is innovatively used as a modifier and pore-forming template, which not only significantly optimizes the multi-level pore structure of the asphalt-based material and improves the specific surface area and conductivity of the material, but also effectively solves the environmental pollution problem of discarded cigarette butts and realizes the high-value recycling of discarded acetate fiber; (3) by combining activated carbonization technology with acetate fiber template pore-forming, a multi-level through-hole structure is constructed, which effectively improves the ion transmission efficiency and charge storage capacity, and significantly improves the specific capacitance, cycle life and rate performance of the supercapacitor; (4) the process is simple and green and environmentally friendly, the raw materials used are cheap and easily available, the production process is easy to scale up, and it has high potential for industrial application; (5) the prepared electrode material is not only suitable for high-performance supercapacitors, but can also be widely used in energy storage, gas adsorption and environmental governance and other fields, with good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The synthetic route of the asphalt-based supercapacitor electrode material of the present invention is shown in FIG.

[0014] Figure 2 TG and DTG curves of the asphalt and recycled acetate fiber used in Examples 1-5.

[0015] Figure 3 SEM (af) and TEM (g, h) images of carbonized materials: (a) SEM image of recycled acetate fiber, showing a fibrous morphology; (b) SEM image of recycled acetate fiber after pyrolysis and carbonization; (cf) SEM images of the co-carbonization products of asphalt-recycled acetate fiber of Examples 1-4, corresponding to 0 wt% (c), 17 wt% (d), 33 wt% (e) and 50 wt% (f) of recycled acetate fiber added, respectively; TEM images of carbonized asphalt of Example 1 (g) and asphalt with 33 wt% acetate fiber added of Example 3 (h).

[0016] Figure 4 Nitrogen adsorption-desorption isotherms (a) and pore size distribution curves (b) of the co-carbonized samples of asphalt and recycled acetate fiber of Examples 1-5.

[0017] Figure 5The electrochemical properties of the asphalt and recycled acetate fiber co-carbonized materials of Examples 1-5: (a) cyclic voltammetry (CV) curves at a scan rate of 20 mV / s, (b) constant current charge and discharge (GCD) curves at a current density of 0.5 A / g, (c) the relationship between specific capacitance and current density, and (d) Nyquist plot. DETAILED DESCRIPTION

[0018] The effects and results of the method of the present invention are further described below with reference to the embodiments, but are not limited to the following embodiments.

[0019] Embodiment 1: The acetate filter element collected from discarded cigarette butts is separated from cigarette paper and residual tobacco, the filter element is crushed into uniform particles, and dried at 50°C to obtain recycled acetate fiber; the recycled acetate fiber is mixed with asphalt in proportion, the mass fraction of acetate fiber is 0 wt%, potassium hydroxide is added to the above mixture, and after grinding evenly with an agate mortar, it is transferred to a nickel square crucible and covered; the crucible is placed in a tubular furnace under a nitrogen atmosphere, heated from room temperature to 200°C and maintained for 30 minutes, then raised to 800°C at a rate of 5°C / min, and kept warm for 1 hour. After carbonization, the product is washed with deionized water and 1 mol / L hydrochloric acid in sequence until neutral, and finally dried in a 90°C forced air oven for 24 hours; the prepared porous carbon, acetylene black and polytetrafluoroethylene emulsion are mixed in a mass ratio of 85:10:5, 10 mL of anhydrous ethanol is added and ultrasonically dispersed for 40 minutes, and after drying to constant weight, it is pressed into a granular product with a diameter of 8 mm and a weight of 2 mg of carbon sheet, the carbon sheet and the nickel foam current collector with a diameter of 15 mm were pressed and combined into a working electrode, and its electrochemical performance was tested. Using 6 M KOH electrolyte, the working electrode, PTFE diaphragm and counter electrode were completely immersed in the electrolyte to complete the assembly. The electrochemical performance was tested at 25°C using a three-electrode system, with a saturated calomel electrode (SCE) as the reference electrode and 6 M KOH as the electrolyte. Cyclic voltammetry (CV), constant current charge and discharge (GCD) and electrochemical impedance spectroscopy (EIS) tests were performed using an Ivium Vertex workstation, and the cycle stability after 10,000 charge and discharge cycles was tested at a current density of 5 A g⁻¹ using a LAND CT2001A tester.

[0020] Example 2: The steps are the same as those described in Example 1, except that the amount of recycled acetate fiber added is changed from 0 wt % to 17 wt %.

[0021] Example 3: The steps are the same as those described in Example 1, except that the amount of recycled acetate fiber added is changed from 0 wt% to 33 wt%.

[0022] Example 4: The steps are the same as those described in Example 1, except that the amount of recycled acetate fiber added is changed from 0 wt % to 50 wt %.

[0023] Example 5: The steps are the same as those described in Example 1, except that the amount of recycled acetate fiber added is changed from 0 wt % to 100 wt %.

[0024] The TG and DTG curves of the asphalt and recycled acetate fiber used are as follows: Figure 2 As shown, representative SEM and TEM images of Examples 1-5 are shown in Figure 3 As shown, the nitrogen adsorption-desorption isotherms and pore size distribution curves of the co-carbonized samples of asphalt and recycled acetate fiber of Examples 1-5 are as follows Figure 4 As shown, the electrochemical performance of the asphalt and recycled acetate fiber co-carbonized materials of Examples 1-5 is as follows Figure 5 As shown. From the above examples, it can be seen that the recycled acetate fiber modified asphalt-based supercapacitor electrode material prepared by the present invention has stable thermal performance, rich through-hole structure, large specific surface area, and excellent electrochemical energy storage properties, and is an ideal supercapacitor electrode material. Compared with conventional technology, the content of the present invention has significant technical progress.

Claims

1. A method for recycling acetate fiber modified asphalt-based supercapacitor electrode material and preparing the same, comprising the following steps: (1) Recovery and pretreatment of acetate fiber: The acetate fiber filter element collected from discarded cigarette butts is separated from the cigarette paper and residual tobacco, the filter element is crushed into uniform particles, and dried at 50-60°C to obtain recycled acetate fiber; (2) Preparation of carbonized matrix: Recycled cellulose acetate and asphalt are mixed in proportion, with the mass fraction of cellulose acetate being 10-60 wt%. An activator is added to the above mixture, and the mixture is ground evenly using an agate mortar and then transferred to a nickel square crucible and covered; (3) High temperature carbonization: Place the crucible in a tube furnace under an inert atmosphere, heat from room temperature to 180-210°C and maintain for 20-40 minutes, then increase the temperature to 750-820°C at a rate of 4-7°C / min and keep warm for 1-2 hours. After carbonization, the product is washed with deionized water and 1 mol / L hydrochloric acid in sequence until neutral, and finally dried in a forced air oven at 80-100°C for 10-24 hours; (4) Electrode preparation and testing: The prepared porous carbon, acetylene black and polytetrafluoroethylene emulsion were mixed in a mass ratio of 85:10:5, 8-15 mL of anhydrous ethanol was added and ultrasonically dispersed for 30-60 min. After drying to constant weight, the carbon sheet with a diameter of 8 mm and a weight of 2 mg was pressed at 3-6 MPa. The carbon sheet was combined with a nickel foam current collector with a diameter of 15 mm to form a working electrode.

2. The recycled cellulose acetate modified asphalt-based supercapacitor electrode material and preparation method thereof according to claim 1, characterized in that: In the step (2), the activator is potassium hydroxide, zinc chloride or potassium carbonate.

3. The recycled cellulose acetate modified asphalt-based supercapacitor electrode material and preparation method thereof according to claim 1, characterized in that: In the step (3), the inert atmosphere is nitrogen or argon.

4. The recycled cellulose acetate modified asphalt-based supercapacitor electrode material and preparation method thereof according to claim 1, characterized in that: In the step (4), the prepared working electrode can be used to assemble a supercapacitor.

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