A wool fiber-based capacitor carbon and its preparation method and application

Abstract

The present invention discloses a wool fiber-based capacitor carbon and its preparation method and application, the method comprising the following steps: washing the wool fiber and freeze-drying it; placing the freeze-dried wool fiber and ultrapure water in a hydrothermal reactor, stirring and heating to obtain carbonized wool fiber; adding the carbonized wool fiber to a mixed solution of an activator and an auxiliary agent for impregnation, stirring, and drying to obtain wool fiber activated carbon; dissolving lead nitrate and manganese sulfate in deionized water, subsequently adding guar gum and wool fiber activated carbon, stirring and heating, standing, drying, and baking the obtained wool fiber activated carbon hydrogel in an inert gas atmosphere to obtain a porous carbon material; washing the porous carbon material with a hydrochloric acid solution, and then using it as an electrode material for a supercapacitor. The capacitor carbon obtained by the present invention not only has an ultra-high specific surface area, but also utilizes the heteroatoms of the biomass itself to synthesize a high specific capacitance electrode material suitable for supercapacitors.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced functional materials, and in particular to a wool fiber-based capacitor carbon and a preparation method and application thereof. Background Art

[0002] As global dependence on fossil fuels increases, resulting in increasingly severe environmental problems and resource shortages, energy sustainability is gaining increasing attention. While countries strive to reduce their reliance on traditional fossil fuels, they are also actively exploring and developing environmentally friendly and cost-effective renewable energy systems. These systems, including wind, solar, fuel cells, and tidal power, not only reduce greenhouse gas emissions but also play a vital role in achieving energy independence and security. However, the intermittent nature of these renewable energy sources makes continuous and stable power supply a challenge. This necessitates an efficient and reliable energy storage system to ensure that social and industrial electricity needs can be met even when energy levels fluctuate.

[0003] Among numerous energy storage technologies, supercapacitors have garnered widespread attention due to their unique properties. Their key advantages include long cycle life, rapid charge and discharge rates, and high power density, making them highly useful in applications requiring rapid response times. Furthermore, their stability in harsh environmental conditions broadens their potential applications. These advantages hold significant promise for supercapacitors in electric vehicles, energy storage in renewable energy systems, and certain high-power applications.

[0004] However, a significant drawback of supercapacitors is their low energy density, meaning they can store relatively little energy relative to their volume or weight. This limitation makes them difficult to use independently in applications requiring a stable, long-term power supply. Therefore, developing advanced porous carbon electrode materials has become a key priority in supercapacitor research. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a wool fiber-based capacitor carbon and its preparation method and application. The wool fiber-based capacitor carbon obtained by the preparation method provided by the present invention has a large specific surface area, high nitrogen and sulfur content, high specific capacity, and the preparation process is environmentally friendly and simple.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing wool fiber-based capacitor carbon, comprising the following steps:

[0008] S1. Wool fiber pretreatment: washing the wool fiber and then freeze-drying it;

[0009] S2. Hydrothermal carbonization: placing the freeze-dried wool fibers and ultrapure water in a hydrothermal reactor, stirring and heating to obtain carbonized wool fibers;

[0010] S3, chemical activation: adding the carbonized wool fiber to a mixture of an activator and an auxiliary agent, immersing, stirring, and drying to obtain wool fiber activated carbon;

[0011] S4. Preparation of porous carbon material: dissolving lead nitrate and manganese sulfate in deionized water, then adding guar gum and the wool fiber activated carbon, stirring and heating, standing, and drying to obtain a wool fiber activated carbon-hydrogel, and calcining the wool fiber activated carbon-hydrogel in an inert gas atmosphere to obtain a porous carbon material;

[0012] S5. Purification: The porous carbon material is washed with a hydrochloric acid solution and can be used as an electrode material for a supercapacitor.

[0013] Preferably, in step S1, the freeze-drying temperature is -50 to -10°C, for example, -50°C, -40°C, -30°C, -20°C or -10°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0014] Preferably, in step S2, the mass ratio of the wool fiber to ultrapure water is (1-2):(4-8).

[0015] The hydrothermal carbonization reaction of the present invention adopts a stainless steel hydrothermal reactor, and the total volume of the wool fiber and ultrapure water accounts for 2 / 3 of the reactor.

[0016] The hydrothermal carbonization treatment is performed at a temperature of 160-200°C for a duration of 8-24 hours. The present invention achieves a highly uniform distribution of doping elements within the carbon material through hydrothermal carbonization. After the hydrothermal carbonization treatment is completed, the present invention preferably cools the hydrothermal carbonization product to obtain carbonized wool fibers. In the present invention, the cooling step involves natural cooling of the stainless steel reactor.

[0017] Hydrothermal carbonization can increase the carbon yield and retain the heteroatoms of the biomass to a greater extent.

[0018] Preferably, in step S3, the auxiliary agent is sodium hydrogen phosphate, and the concentration of the auxiliary agent is 3 wt% to 10 wt%.

[0019] Preferably, in step S3, the activator is any one of potassium hydroxide, potassium citrate, and potassium ferrate; and the concentration of the activator is 8 wt% to 12 wt%.

[0020] In the present invention, different activators have different pore-forming effects on carbonized wool fibers. Potassium hydroxide, a strong alkaline agent, etches the carbon material, breaking chemical bonds within the material and forming pores. The redox reaction between potassium hydroxide and the carbon material converts some of the carbon into gas, which escapes, forming pores. Potassium hydroxide also dehydrates the carbon material, causing a rearrangement of its molecular structure, creating pores. Potassium citrate, through complexation, thermal decomposition, and reaction with the carbon material, produces gases such as carbon dioxide. These gases form bubbles within the carbon material, escaping and leaving pores behind, achieving the pore-forming effect. Potassium ferrate, on the other hand, reacts with the carbon material to produce potassium hydroxide and ferric hydroxide, which form pores in the carbon material. The ferric hydroxide improves the carbon material's graphitization, thereby enhancing electrochemical performance. Controlling the temperature of the high-temperature activation reaction in a box-type atmosphere furnace allows the specific surface area and pore size of the carbon material to be controlled, resulting in the highest-performance capacitor carbon. The synergistic effect of hydrothermal carbonization and chemical activation on wool fibers transforms them from waste into an electrode material suitable for electric double-layer capacitors.

[0021] Preferably, in step S4, the baking temperature is 800-900°C, the heating rate is 3-5°C / min, for example, 3°C / min, 4°C / min or 5°C / min, but is not limited to the listed values. Other unlisted values within this numerical range are also applicable. The activation time is 1-2h, for example, 1, 1.5h or 2h; the inert gas is nitrogen or argon.

[0022] The present invention controls the specific surface area and pore size of wool fiber-based capacitor carbon by controlling the types or temperatures of carbonized wool fibers and activators, thereby obtaining wool fiber-based capacitor carbon with a high specific surface area and matching the size of the electrolyte.

[0023] The baking process of the present invention is carried out in a box-type atmosphere furnace.

[0024] Preferably, in step S4, the mass ratio of the lead nitrate, manganese sulfate, guar gum and wool fiber activated carbon is (2-3): (1-2): (12-20): (2-5).

[0025] Preferably, in step S5, the concentration of the hydrochloric acid solution is 0.4-0.5 mol / L. In this step, the washing is preferably performed by suction filtration, and the porous carbon material is washed by suction filtration. The degree of washing is preferably such that the washing solution becomes neutral.

[0026] The present invention also provides a wool fiber-based capacitor carbon prepared by the above preparation method.

[0027] The present invention further proposes the use of the wool fiber-based capacitor carbon described above in supercapacitors.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention provides a method for preparing wool fiber-based capacitor carbon. First, the wool fiber is freeze-dried and then hydrothermally carbonized and chemically activated. Subsequently, the wool fiber activated carbon is coated with a hydrogel as a bonding coating. The coated material is then calcined and the pore structure is controlled to obtain a porous carbon material. Finally, the obtained porous carbon material is purified to obtain a porous carbon electrode material. The capacitor carbon obtained by the present invention not only has an ultra-high specific surface area, but also utilizes heteroatoms in the biomass itself to synthesize a high specific capacitance electrode material suitable for supercapacitors.

[0030] (2) The present invention first freeze-dries the wool fiber to maintain the fiber structure of the wool fiber itself, providing a relatively complete raw material basis for the subsequent preparation of porous carbon; then the raw material is initially carbonized to form a carbonaceous structure through hydrothermal carbonization, thereby improving the carbon yield and retaining the nitrogen and sulfur heteroatoms of the biomass itself; then chemical activation with an activator and an auxiliary agent further creates pores in the carbon material, increases the specific surface area and porosity, and forms a developed microporous-mesoporous structure, and chemical activation can adjust and increase the types and number of functional groups and increase the number of active sites; through the synergistic effect of hydrothermal carbonization and activation with potassium hydroxide, potassium citrate, potassium ferrate, and sodium hydrogen phosphate, as well as Controlling the activation temperature of potassium hydroxide, potassium citrate, and potassium ferrate can control the specific surface area and pore size of the carbon material, thereby obtaining a capacitor carbon with an ultra-high specific surface area that matches the electrolyte. Finally, guar gum, wool fiber activated carbon, and a metal salt solution are mixed to prepare a wool fiber activated carbon-hydrogel, which is then calcined to obtain a porous carbon material. In this step, the hydrogel bonds and encapsulates the metal salt and wool fiber activated carbon. Under high temperature, the hydrogel pyrolyzes to form an amorphous carbon coating, which then encapsulates the metal oxide and wool fiber activated carbon. After purification, an amorphous carbon-coated, metal oxide-doped wool fiber-based capacitor carbon is obtained. This wool fiber-based capacitor carbon has excellent electrochemical properties and cycle stability.

[0031] (3) The present invention uses wool fiber as raw material. As a rich renewable biomass, it contains abundant nitrogen and sulfur elements. During the hydrothermal carbonization process, the reactants are in a uniform mixed state at the molecular or ionic level. The heteroatoms can be evenly dispersed in the reaction system, fully contacting and interacting with the carbon source, thereby achieving a highly uniform distribution of doping elements in the carbon material. During the activation process, the functional groups on the surface of the carbon material will change and reorganize. In order to fully retain the heteroatoms, the material is calcined under an inert gas atmosphere, and hydrogel coating and sodium hydrogen phosphate additives are used to synergistically assist in retaining the nitrogen-containing, sulfur-containing and other functional groups in the wool fiber. These heteroatoms can effectively adjust its electronic and chemical structure, providing high power density and long-cycle electrochemical performance for energy storage devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic flow chart of the preparation method of the wool fiber-based capacitor carbon provided by the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0034] It should be noted that, unless otherwise specified, all chemical reagents involved in the present invention were purchased through commercial channels.

[0035] Wool fiber: purchased from high-quality sheep wool in the northwest region;

[0036] Guar gum: purchased from Anhui Zhonghong Bioengineering Co., Ltd., with a mesh size of 80-100 mesh.

[0037] Example 1

[0038] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0039] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -40°C freeze drying oven;

[0040] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 12 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0041] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium hydroxide solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0042] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 850° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0043] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0044] Example 2

[0045] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0046] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -50°C freeze drying oven;

[0047] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 8 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0048] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium citrate solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 h, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0049] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 850° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0050] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0051] Example 3

[0052] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0053] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -40°C freeze drying oven;

[0054] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor, stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 10 h. The carbonized wool fiber was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0055] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium ferrate solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80°C until the moisture disappeared to obtain wool fiber activated carbon;

[0056] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 850° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0057] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0058] Example 4

[0059] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0060] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -30°C freeze drying oven;

[0061] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 14 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0062] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium hydroxide solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0063] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 900° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0064] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0065] Example 5

[0066] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0067] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -20°C freeze drying oven;

[0068] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 16 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0069] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium citrate solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 h, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0070] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 900° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0071] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0072] Example 6

[0073] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0074] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -10°C freeze drying oven;

[0075] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 24 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0076] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium ferrate solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80°C until the moisture disappeared to obtain wool fiber activated carbon;

[0077] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 900° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0078] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0079] Comparative Example 1

[0080] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0081] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -40°C freeze drying oven;

[0082] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 12 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0083] (3) 9 g of carbonized wool fiber was added to 1.5 mL of sodium hydrogen phosphate solution and mixed, then stirred at 120 r / min for 12 h, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0084] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of wool fiber activated carbon, and the mixture was stirred and heated to 40° C., and allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 850° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0085] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0086] Compared with Example 1, Comparative Example 1 was not treated with the active agent potassium hydroxide solution.

[0087] Comparative Example 2

[0088] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0089] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -40°C freeze drying oven;

[0090] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 12 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0091] (3) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, followed by the addition of 25 g of guar gum and 8 g of carbonized wool fiber, and the mixture was stirred and heated to 40°C. The mixture was allowed to stand to obtain a wool fiber activated carbon-hydrogel. The wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation and calcined at 850°C for 2 hours under a nitrogen atmosphere at a heating rate of 5°C / min to obtain a porous carbon material.

[0092] (4) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0093] Compared with Example 1, Comparative Example 2 was not treated with the active agent potassium hydroxide solution and the auxiliary agent sodium hydrogen phosphate.

[0094] Comparative Example 3

[0095] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0096] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -40°C freeze drying oven;

[0097] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 12 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0098] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium hydroxide solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0099] (4) 6 g of lead nitrate and 3 g of manganese sulfate were dissolved in 30 mL of deionized water, and then 8 g of wool fiber activated carbon was added. The mixture was stirred and heated to 40 °C. The mixture was allowed to stand to obtain a composite. The composite was moved to a box-type atmosphere furnace for activation and calcined at 850 °C for 2 h under a nitrogen atmosphere at a heating rate of 5 °C / min to obtain a porous carbon material.

[0100] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0101] Comparative Example 3 Compared with Example 1, the hydrogel was prepared without guar gum.

[0102] Comparative Example 4

[0103] A method for preparing wool fiber-based capacitor carbon comprises the following steps:

[0104] (1) 10 g of wool fiber was washed with ultrapure water and then freeze-dried in a -40°C freeze drying oven;

[0105] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which occupied 2 / 3 of a stainless steel hydrothermal reactor. The mixture was stirred, heated, and hydrothermally carbonized at a temperature of 180°C for 12 h. The mixture was then cooled to room temperature in an oven to obtain carbonized wool fiber.

[0106] (3) 9 g of carbonized wool fiber was added to 24 mL of potassium hydroxide solution and 1.5 mL of sodium hydrogen phosphate solution, and the mixture was stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80 °C until the moisture disappeared to obtain wool fiber activated carbon;

[0107] (4) adding 25 g of guar gum and 8 g of wool fiber activated carbon to 30 mL of deionized water, stirring and heating to 40° C., and standing to obtain wool fiber activated carbon-hydrogel, and moving the wool fiber activated carbon-hydrogel to a box-type atmosphere furnace for activation, and baking at 850° C. for 2 hours under a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0108] (5) 8 g of porous carbon material was placed in a 0.5 mol / L hydrochloric acid solution for purification, and then washed with ultrapure water until neutral to obtain wool fiber-based capacitor carbon.

[0109] Comparative Example 4 Compared with Example 1, lead nitrate and manganese sulfate were not added in step (4).

[0110] The specific surface area, nitrogen content, and sulfur content of the capacitor carbons prepared in Examples 1-6 and Comparative Examples 1-4 of the present invention were tested; the capacitor carbons prepared in Examples 1-6 and Comparative Examples 1-4 were mixed with acetylene black as a conductive agent and PTFE as a binder in a mass ratio of 8:1:1 and stirred to obtain a coating liquid; the obtained coating liquid was evenly applied to an area of 1 cm using a screen printing plate. 2 The supercapacitor electrode was prepared by vacuum drying at 100 ° C for 12 h on the current collector nickel foam, and finally pressed at 12 MPa for 30 s by a tablet press. The prepared supercapacitor electrode was used as the working electrode, mercury / mercuric oxide as the reference electrode, Pt sheet as the auxiliary electrode, and 6 mol / L KOH aqueous solution as the electrolyte. Cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge and discharge tests were carried out on a Shanghai Chenhua CHI660E electrochemical workstation. The test voltage was -1 to 0 V, the test current density was 1 A / g, and the number of long cycle charge and discharge was 20,000 times. The test results are shown in Table 1.

[0111] Table 1 Product performance test results

[0112]

[0113]

[0114] It can be seen from the above table that compared with the products prepared in Comparative Examples 1 to 4, the wool fiber-based capacitor carbon prepared by the present invention has a large specific surface area, high nitrogen and sulfur content, high specific capacity, and excellent electrochemical properties.

[0115] Finally, it should be noted that the above embodiments do not limit the present invention in any form. Those skilled in the art will appreciate that modifications and improvements can be made based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are intended to fall within the scope of protection claimed in the present invention.

Claims

1. A method for preparing wool fiber-based capacitor carbon, characterized in that: The following steps are involved: S1. Wool fiber pretreatment: washing the wool fiber and then freeze-drying it; S2. Hydrothermal carbonization: placing the freeze-dried wool fibers and ultrapure water in a hydrothermal reactor, stirring and heating to obtain carbonized wool fibers; S3, chemical activation: adding the carbonized wool fiber to a mixture of an activator and an auxiliary agent, immersing, stirring, and drying to obtain wool fiber activated carbon; S4. Preparation of porous carbon material: dissolving lead nitrate and manganese sulfate in deionized water, then adding guar gum and the wool fiber activated carbon, stirring and heating, standing, and drying to obtain a wool fiber activated carbon-hydrogel, and calcining the wool fiber activated carbon-hydrogel in an inert gas atmosphere to obtain a porous carbon material; S5, purification: washing the porous carbon material with a hydrochloric acid solution, and then using it as an electrode material for a supercapacitor; In step S4, the mass ratio of the lead nitrate, manganese sulfate, guar gum and wool fiber activated carbon is (2-3): (1-2): (12-20): (2-5).

2. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S1, the freeze-drying temperature is -50 to -10°C.

3. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S2, the mass ratio of the wool fiber to ultrapure water is (1-2):(4-8); The temperature of the hydrothermal carbonization treatment is 160-200° C., and the time of the hydrothermal carbonization treatment is 8-24 hours.

4. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S3, the auxiliary agent is sodium hydrogen phosphate, and the concentration of the auxiliary agent is 3 wt% to 10 wt%.

5. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S3, the activator is any one of potassium hydroxide, potassium citrate, and potassium ferrate; and the concentration of the activator is 8 wt% to 12 wt%.

6. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S4, the baking temperature is 800-900° C., the heating rate is 3-5° C. / min, and the baking time is 1-2 hours; the inert gas is nitrogen or argon.

7. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S5, the concentration of the hydrochloric acid solution is 0.4-0.5 mol / L.

8. A wool fiber-based capacitor carbon prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the wool fiber-based capacitor carbon as claimed in claim 8 in supercapacitors.

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