Wool fiber-based capacitance carbon and preparation method and application thereof

Abstract

The invention discloses wool fiber-based capacitance carbon as well as a preparation method and application thereof. The method comprises the following steps: cleaning wool fibers, and then freeze-drying; putting the freeze-dried wool fibers and ultrapure water into a hydrothermal reaction kettle, stirring and heating to obtain carbonized wool fibers; adding the carbonized wool fibers into a mixed solution of an activating agent and an auxiliary agent for dipping, stirring and drying to obtain wool fiber activated carbon; dissolving lead nitrate and manganese sulfate in deionized water, then adding guar gum and wool fiber activated carbon, stirring, heating, standing and drying, and baking the obtained wool fiber activated carbon-hydrogel in an inert gas atmosphere to obtain a porous carbon material; the porous carbon material can be used as an electrode material of a supercapacitor after being washed by a hydrochloric acid solution. The capacitor carbon obtained by the invention not only has an ultrahigh specific surface area, but also synthesizes a high-specific-capacitance electrode material suitable for a supercapacitor by using heteroatoms of biomass.

Description

Technical Field

[0001] The 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 the world's dependence on fossil fuels gradually increases, the environmental problems and resource shortages caused by them are becoming increasingly serious, and energy sustainability has received more and more attention. While countries are working to reduce their dependence on traditional fossil fuels, they are also actively exploring and developing environmentally friendly and economical renewable energy systems. These systems include wind power, solar energy, fuel cells, and tidal energy, which can not only reduce greenhouse gas emissions, but also play an important 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 requires an efficient and reliable energy storage system to ensure that the needs of society and industry can still be met when energy is unstable.

[0003] Among the many energy storage technologies, supercapacitors have attracted widespread attention due to their unique properties. The main advantages of supercapacitors include long cycle life, fast charge and discharge rates, and high power density, making them very useful in application scenarios that require fast response. In addition, the stability of supercapacitors under harsh environmental conditions also provides a wider range of possibilities for their application. These advantages make supercapacitors have important application prospects in electric vehicles, energy storage in renewable energy systems, and some high-power applications.

[0004] However, a significant drawback of supercapacitors is their low energy density, meaning that they store less energy relative to their volume or weight. This limitation makes it difficult for supercapacitors to be used independently in situations where a stable power supply is required for a long time. Therefore, the development of advanced porous carbon electrode materials has become a top priority in supercapacitor research. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a wool fiber-based capacitor carbon and a preparation method and application thereof. 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 an environmentally friendly and simple preparation process.

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

[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 fiber and ultrapure water in a hydrothermal reactor, stirring and heating to obtain carbonized wool fiber;

[0010] S3, chemical activation: adding the carbonized wool fiber to a mixed solution of an activator and an auxiliary agent for immersion, 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 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 the 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 temperature of the hydrothermal carbonization treatment is 160 to 200° C., and the time of the hydrothermal carbonization treatment is 8 to 24 hours. The present invention achieves highly uniform distribution of doping elements in the carbon material through hydrothermal carbonization. After the hydrothermal carbonization treatment is completed, the present invention preferably cools the product of the hydrothermal carbonization treatment to obtain carbonized wool fibers. In the present invention, the cooling is natural cooling of the stainless steel reactor.

[0017] Hydrothermal carbonization can improve 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 3wt% to 10wt%.

[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 8wt% to 12wt%.

[0020] In the present invention, different activators have different pore-forming effects on carbonized wool fibers. Potassium hydroxide has strong alkalinity and can etch carbon materials, breaking chemical bonds in the materials to form pores; and the redox reaction between potassium hydroxide and carbon materials converts part of the carbon into gas to escape, thereby forming pores; potassium hydroxide can dehydrate carbon materials, causing molecular structure rearrangement to generate pores. Potassium citrate produces gases such as carbon dioxide through complexation, thermal decomposition of itself, and reaction with carbon materials. These gases form bubbles inside the carbon materials, leaving pores after escaping, thereby achieving the purpose of pore formation. Potassium ferrate reacts with carbon materials to produce potassium hydroxide and ferric hydroxide, which produce pores on carbon materials. For ferric hydroxide, the graphitization degree of carbon materials can be improved, thereby improving electrochemical performance. And by controlling the temperature of the high-temperature activation reaction in the box-type atmosphere furnace, the specific surface area and pore size of the carbon material can be controlled, thereby obtaining the highest performance capacitor carbon. The wool fiber can be treated by the synergistic effect of hydrothermal carbonization and chemical activation to transform it from waste into an electrode material that is beneficial to double-layer capacitors.

[0021] Preferably, in step S4, the calcination 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, and other unlisted values ​​within the 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 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 high specific surface area and matching the size of 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 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, and the degree of washing is preferably to neutralize the washing liquid.

[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 as described above in a supercapacitor.

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

[0029] (1) The preparation method of wool fiber-based capacitor carbon provided by the present invention comprises the following steps: firstly, freeze-drying the wool fiber and then subjecting it to hydrothermal carbonization and chemical activation treatment, then coating the wool fiber activated carbon with hydrogel as a bonding coating, and then baking and regulating the pore structure to obtain a porous carbon material; finally, purifying the obtained porous carbon material 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 the heteroatoms of 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, thereby providing a relatively complete raw material basis for the subsequent preparation of porous carbon; then, the raw material is initially carbonized by hydrothermal carbonization to form a carbonaceous structure, thereby increasing the carbon yield and retaining the nitrogen and sulfur atoms of the biomass itself; then, chemical activation with an activator and an auxiliary agent is performed to further form pores in the carbon material, increase the specific surface area and porosity, and form a developed microporous-mesoporous structure, and chemical activation can adjust and increase the types and quantities 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, and 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 wool fiber activated carbon-hydrogel, and a porous carbon material is obtained after baking. In this step, the hydrogel bonds and wraps the metal salt and the wool fiber activated carbon. Under high temperature, the amorphous carbon wrapping layer formed by the pyrolysis of the hydrogel wraps the metal oxide and the wool fiber activated carbon. After purification, amorphous carbon-wrapped, metal oxide-doped wool fiber-based capacitor carbon is obtained. The 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 rich nitrogen and sulfur elements. During the hydrothermal carbonization process, the reactants are in a uniformly mixed state at the molecular or ionic level. The heteroatoms can be evenly dispersed in the reaction system, fully contact and interact 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 in 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 their electronic and chemical structures, providing high power density and long cycle electrochemical performance for energy storage devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic flow chart of the method for preparing 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, the chemical reagents involved in the present invention were purchased through commercial channels.

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

[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 placed in a -40°C freeze drying oven for freeze drying;

[0040] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 12 h. The carbonized wool fiber 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, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked 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 the 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 placed in a -50°C freeze drying oven for freeze drying;

[0047] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 8 h. The carbonized wool fiber 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 hours, and then dried in a forced air drying oven at 80° C. until the moisture disappeared, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked 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 the 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 placed in a -40°C freeze drying oven for freeze drying;

[0054] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and 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, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked 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 the 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 placed in a -30°C freeze drying oven for freeze drying;

[0061] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 14 h. The carbonized wool fiber 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, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked at 900° C. for 2 hours in a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0064] (5) 8 g of the 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 placed in a -20°C freeze drying oven for freeze drying;

[0068] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 16 h. The carbonized wool fiber 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 hours, and then dried in a forced air drying oven at 80° C. until the moisture disappeared, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked at 900° C. for 2 hours in a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0071] (5) 8 g of the 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 placed in a -10°C freeze drying oven for freeze drying;

[0075] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 24 h. The carbonized wool fiber 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, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked at 900° C. for 2 hours in a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0078] (5) 8 g of the 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 placed in a -40°C freeze drying oven for freeze drying;

[0082] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 12 h. The carbonized wool fiber 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, and then stirred at 120 r / min for 12 hours, and then dried in a forced air drying oven at 80° C. until the moisture disappeared, thereby obtaining 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, and then 25 g of guar gum and 8 g of wool fiber activated carbon were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked 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 the 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 an activating 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 placed in a -40°C freeze drying oven for freeze drying;

[0090] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 12 h. The carbonized wool fiber 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, and then 25 g of guar gum and 8 g of carbonized wool fiber were added, stirred and heated to 40° C., and allowed to stand to obtain wool fiber activated carbon-hydrogel, and the wool fiber activated carbon-hydrogel was moved to a box-type atmosphere furnace for activation, and baked at 850° C. for 2 hours in a nitrogen atmosphere at a heating rate of 5° C. / min to obtain a porous carbon material;

[0092] (4) 8 g of the 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 an activating agent, potassium hydroxide solution, and an 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 placed in a -40°C freeze drying oven for freeze drying;

[0097] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 12 h. The carbonized wool fiber 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, thereby obtaining 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, stirred and heated to 40 ° C, and allowed to stand to obtain a composite. The composite was moved to a box-type atmosphere furnace for activation, and baked at 850 ° C for 2 hours in a nitrogen atmosphere at a heating rate of 5 ° C / min to obtain a porous carbon material;

[0100] (5) 8 g of the 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 placed in a -40°C freeze drying oven for freeze drying;

[0105] (2) 10 g of freeze-dried wool fiber was mixed with 40 mL of ultrapure water, which accounted for 2 / 3 of a stainless steel hydrothermal reactor, and stirred, heated, and hydrothermally carbonized at a temperature of 180° C. for 12 h. The carbonized wool fiber 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, thereby obtaining 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., standing to obtain wool fiber activated carbon-hydrogel, 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 the 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 conductive agent acetylene black and binder PTFE 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 by a screen printing plate. 2 The current collector was placed on nickel foam and vacuum dried at 100 °C for 12 h. Finally, the supercapacitor electrode was obtained by a tablet press at 12 MPa for 30 s. The prepared supercapacitor electrode was used as the working electrode, mercury / mercuric oxide was used as the reference electrode, Pt sheet was used as the auxiliary electrode, and 6 mol / L KOH aqueous solution was used 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, a high nitrogen and sulfur content, a high specific capacity, and has excellent electrochemical properties.

[0115] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to 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 fiber and ultrapure water in a hydrothermal reactor, stirring and heating to obtain carbonized wool fiber; S3, chemical activation: adding the carbonized wool fiber to a mixed solution of an activator and an auxiliary agent for immersion, 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 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: The porous carbon material is washed with a hydrochloric acid solution and can be used as an electrode material for a supercapacitor.

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 the 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 3wt% to 10wt%.

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; the concentration of the activator is 8wt% to 12wt%.

6. The method for preparing wool fiber-based capacitor carbon according to claim 1, characterized in that: In step S4, the calcination temperature is 800-900°C, the heating rate is 3-5°C / min, and the calcination time is 1-2h; 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 S4, the mass ratio of lead nitrate, manganese sulfate, guar gum and wool fiber activated carbon is (2-3): (1-2): (12-20): (2-5).

8. 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.

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

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

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