A kind of nitrogen-sulfur co-doped carbon microsphere and its preparation method and application
By using monomeric materials such as resorcinol, formaldehyde, thiourea, etc. to prepare nitrogen and sulfur co-doped carbon microspheres, the complex preparation conditions and high cost problems in the prior art are solved, and efficient electrochemical energy storage performance is achieved. Especially in applications in supercapacitors, excellent capacitance performance is shown.
Patent Information
- Application Number
- CN202310615852.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-29
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2043-05-29
AI Technical Summary
The existing nitrogen-doped carbon microspheres and nitrogen-sulfur co-doped porous carbon microspheres show good electrochemical energy storage performance in supercapacitors, but the chemical reagents used are complex, expensive, the preparation conditions are complex and the operation is cumbersome.
Resorcinol, formaldehyde and thiourea are used as monomer materials, and polymerization reaction is carried out through catalyst action to obtain carbon microsphere precursors rich in nitrogen and sulfur, and nitrogen and sulfur co-doped carbon microspheres are prepared under high-temperature activation conditions. , used for supercapacitor electrode material.
A simplified preparation process is realized, and the obtained nitrogen-sulphur-doped carbon microspheres show good microscopic dimensional uniformity and high specific surface area. As an electrode material, it shows excellent electrochemical energy storage performance in 6MKOH solution, and capacitors. Up to 257F/g.
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Figure CN117776175B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of carbon materials, and specifically relates to nitrogen-sulfur co-doped carbon microspheres and a preparation method and application thereof. Background Art
[0002] Carbon materials are widely used in the field of electrochemical energy storage due to their good conductivity, excellent chemical stability, high specific surface area and good porosity. At present, biomass activated carbon is widely used as commercial supercapacitor electrodes due to its advantages such as low cost and easy preparation, but biomass activated carbon also has the disadvantage of low capacitance, which hinders the further development of energy storage devices. In order to achieve efficient energy storage of carbon materials, a variety of precursors have been used in the preparation of carbon materials, from common biomass, small molecule organic matter to phenolic resin, and then to various new organic polymers. In addition, new carbon materials with different dimensions, excellent pore structure and surface modification are also used in high-performance supercapacitors.
[0003] The Chinese patent with publication number CN105152160A discloses a method for preparing nitrogen-doped carbon microspheres, which uses o-toluidine as the main raw material to prepare poly-o-toluidine microspheres by oxidative polymerization, and then places them in a tube furnace for high-temperature carbonization to obtain nitrogen-doped carbon microspheres. The prepared nitrogen-doped carbon microspheres have a particle size of about 1 μm, are evenly dispersed, and have a specific surface area of 727 m 2 / g.
[0004] The Chinese patent with publication number CN107689303A discloses a method for preparing nitrogen-sulfur co-doped porous carbon microspheres, which uses hexachlorobutadiene and tellurium diethyldithiocarbamate as raw materials, obtains a precursor through high temperature and high pressure solvent thermal reaction, and carbonizes under inert gas to obtain nitrogen-sulfur co-doped porous carbon microspheres. The prepared nitrogen-sulfur co-doped porous carbon microspheres have a particle size between 150 and 400 nm, are evenly dispersed, and have a specific surface area of 947 m 2 / g.
[0005] By comparison, it was found that the heteroelement-doped carbon microspheres introduced in the above patents exhibited good electrochemical energy storage performance in supercapacitors: large electrochemical capacity and long cycle life. However, the chemical reagents used in the above patents are complex and expensive, and the preparation conditions are complex and the operation is cumbersome. Summary of the invention
[0006] The purpose of the present invention is to provide a nitrogen-sulfur co-doped carbon microsphere and a preparation method and application thereof in view of the above-mentioned existing problems. The present invention adopts relatively cheap resorcinol, formaldehyde and thiourea as monomer materials, wherein thiourea is a nitrogen source and a sulfur source. The three monomers are polymerized under the action of a catalyst to obtain a carbon microsphere precursor rich in nitrogen and sulfur elements. After high-temperature activation, nitrogen-sulfur doped carbon microspheres are prepared and used as supercapacitor electrode materials.
[0007] In order to achieve the above purpose, the technical solution adopted in this application is:
[0008] The first object of the present invention is to provide a method for preparing nitrogen-sulfur co-doped carbon microspheres, comprising the following steps:
[0009] S1, adding resorcinol, formaldehyde and thiourea into a solvent, then adding a catalyst and stirring evenly to carry out a prepolymerization reaction, and after the reaction is completed, a hydrothermal reaction is carried out, and after the hydrothermal reaction is completed, washing and drying are carried out to obtain a carbon microsphere precursor;
[0010] S2. Grind and mix the carbon microsphere precursor obtained in S1 and the activator, and activate them under a protective gas atmosphere to obtain nitrogen-sulfur co-doped carbon microspheres.
[0011] Preferably, in S1, the molar concentrations of resorcinol, formaldehyde and thiourea are all 0.01-0.2 mol / L, and the solvent is prepared by mixing anhydrous ethanol and water in a volume ratio of 2:5.
[0012] Preferably, in S1, the concentration of the catalyst is 0.01-0.2 mol / L, and the catalyst is one of sodium carbonate, sodium bicarbonate, and ammonia water.
[0013] Preferably, in S1, the prepolymerization reaction temperature is 20-50° C., and the reaction time is 24-36 hours.
[0014] Preferably, in S1, the temperature of the hydrothermal reaction is 80-160° C., and the time is 12-72 hours.
[0015] Preferably, in S2, the activator is one of potassium hydroxide, sodium hydroxide, carbon dioxide, and water vapor, and the protective gas is nitrogen or argon.
[0016] Preferably, in S2, when the activator is potassium hydroxide or sodium hydroxide, the mass ratio of the carbon microsphere precursor to the activator is 1:0.1-2; when the activator is carbon dioxide or water vapor, the flow rate of the activator is 10-100 mL / min.
[0017] Preferably, in S2, the high temperature activation condition is to increase the temperature to 650-900°C at a heating rate of 2-5°C / min and keep the temperature for 1-4h.
[0018] The second object of the present invention is to provide nitrogen-sulfur co-doped carbon microspheres prepared by the above method.
[0019] The third object of the present invention is to provide the use of the nitrogen-sulfur co-doped carbon microspheres in supercapacitors.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] (1) The present invention uses resorcinol, formaldehyde and thiourea as raw materials, and obtains a carbon microsphere precursor through a two-step polymerization method. The synthesis process is simple and easy to operate. After high-temperature activation, nitrogen-sulfur-doped carbon microspheres are obtained, which can be used as supercapacitor electrode materials to obtain excellent electrochemical energy storage performance. This method does not require the use of a template method, thus avoiding cumbersome operating procedures.
[0022] (2) The nitrogen-sulfur doped carbon microspheres prepared by the present invention exhibit good microscopic size uniformity after high-temperature activation, a diameter of about 200 nm, a large specific surface area, and a high nitrogen-sulfur doping content.
[0023] (3) The specific surface area of the nitrogen-sulfur doped carbon microspheres prepared by the present invention is 400 m 2 / g or more, it can be used as an electrode material in a symmetrical supercapacitor with 6MKOH solution as the electrolyte, with a specific capacitance of up to 257F / g, which has good application prospects in electrochemical energy storage. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a scanning electron microscope image of nitrogen-sulfur doped carbon microspheres prepared in Example 1 of the present invention;
[0025] Figure 2 CV curves of nitrogen-sulfur-doped carbon microspheres prepared in Example 1 at different scan rates;
[0026] Figure 3 The constant current charge and discharge curves of the nitrogen-sulfur doped carbon microspheres prepared in Example 1 at different current densities. DETAILED DESCRIPTION
[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0028] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods. It should also be noted that the formaldehyde solution used in the present invention is 38wt.%, and the ammonia content of the ammonia water used is 25%.
[0029] Example 1
[0030] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0031] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0032] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0033] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 1 is 1638 m 2 / g, and the specific capacitance is 257F / g when the current density is 0.2A / g.
[0034] Example 2
[0035] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0036] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.75:0.25 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0037] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 850°C at a heating rate of 5°C / min under nitrogen conditions for high-temperature activation for 7 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0038] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 2 is 1358 m 2 / g, and the specific capacitance is 212F / g at a current density of 0.2A / g.
[0039] Example 3
[0040] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0041] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.25:0.75 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.1 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 20°C for 48 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 12 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0042] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 650°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0043] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 3 is 906 m 2 / g, and the specific capacitance is 182F / g at a current density of 0.2A / g.
[0044] Example 4
[0045] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0046] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.2 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 36 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 48 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0047] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:0.5, and placed in a tube furnace. The temperature was raised to 850°C at a heating rate of 3°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0048] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 4 is 1168 m 2 / g, and the specific capacitance is 234F / g at a current density of 0.2A / g.
[0049] Example 5
[0050] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0051] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.1:0.9 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 50°C for 48 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 72 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0052] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:2, and then placed in a tube furnace. The temperature was raised to 650°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0053] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 5 is 1056 m 2 / g, and the specific capacitance is 178F / g at a current density of 0.2A / g.
[0054] Example 6
[0055] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0056] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.9:0.1 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.2 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 50°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0057] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 5°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0058] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 6 is 1336 m 2 / g, and the specific capacitance is 227F / g at a current density of 0.2A / g.
[0059] Example 7
[0060] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0061] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.01 mol / L, add 0.01 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0062] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 700°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 1 hour to obtain nitrogen-sulfur co-doped carbon microspheres.
[0063] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 7 is 1268 m 2 / g, and the specific capacitance is 216F / g when the current density is 0.2A / g.
[0064] Example 8
[0065] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0066] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of sodium carbonate, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0067] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0068] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 8 is 1329 m 2 / g, and the specific capacitance is 229F / g when the current density is 0.2A / g.
[0069] Example 9
[0070] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0071] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of sodium bicarbonate, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0072] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0073] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 9 is 1138 m 2 / g, and the specific capacitance is 195F / g at a current density of 0.2A / g.
[0074] Example 10
[0075] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0076] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.1 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0077] S2. The carbon microsphere precursor obtained in S1 was heated to 750° C. at a heating rate of 2° C. / min under carbon dioxide (100 mL / min) conditions for high-temperature activation for 1 h to obtain nitrogen-sulfur co-doped carbon microspheres.
[0078] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 10 is 821 m 2 / g, and the specific capacitance is 179F / g when the current density is 0.2A / g.
[0079] Embodiment 11
[0080] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0081] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0082] S2. The carbon microsphere precursor obtained in S1 was heated to 750°C at a heating rate of 2°C / min under water vapor (10 mL / min) for 4 h to obtain nitrogen-sulfur co-doped carbon microspheres.
[0083] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 11 is 766 m 2 / g, and the specific capacitance is 168F / g when the current density is 0.2A / g.
[0084] Example 12
[0085] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0086] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 40°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 48 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0087] S2. The carbon microsphere precursor obtained in S1 was heated to 900°C at a heating rate of 5°C / min under carbon dioxide (50 mL / min) conditions for high-temperature activation for 4 h to obtain nitrogen-sulfur co-doped carbon microspheres.
[0088] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 12 is 981 m 2 / g, and the specific capacitance is 209F / g when the current density is 0.2A / g.
[0089] Embodiment 13
[0090] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0091] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:1:1 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0092] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:0.1, and placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0093] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 13 is 768 m 2 / g, and the specific capacitance is 159F / g at a current density of 0.2A / g.
[0094] Embodiment 14
[0095] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0096] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:1:0.01 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0097] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0098] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 14 is 1169 m 2 / g, and the specific capacitance is 208F / g when the current density is 0.2A / g.
[0099] Embodiment 15
[0100] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0101] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.01:1 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.05 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0102] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 750°C at a heating rate of 2°C / min under nitrogen conditions for high-temperature activation for 2 hours to obtain nitrogen-sulfur co-doped carbon microspheres.
[0103] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 15 is 943 m 2 / g, and the specific capacitance is 186F / g when the current density is 0.2A / g.
[0104] Example 16
[0105] A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that it comprises the following steps:
[0106] S1. Add resorcinol, formaldehyde and thiourea in a molar concentration ratio of 1:0.5:0.5 to a mixed solution of 16 mL of anhydrous ethanol and 40 mL of distilled water, wherein the molar concentration of resorcinol is 0.1 mol / L, add 0.1 mol / L of ammonia water, continue stirring for 10 min to mix evenly, seal the mixed solution and place it in an oven, perform a prepolymerization reaction at 30°C for 24 hours, transfer it to a polytetrafluoroethylene reactor after the reaction is completed, place it at 100°C for a hydrothermal reaction for 24 hours, and after the hydrothermal reaction is completed, wash the product with anhydrous ethanol and distilled water, and dry it to obtain a carbon microsphere precursor;
[0107] S2. The carbon microsphere precursor obtained in S1 and potassium hydroxide were ground and mixed in a mass ratio of 1:1, and then placed in a tube furnace. The temperature was raised to 850°C at a heating rate of 2°C / min under argon conditions for high-temperature activation for 1 hour to obtain nitrogen-sulfur co-doped carbon microspheres.
[0108] After testing, the specific surface area of the nitrogen-sulfur co-doped carbon microspheres in Example 16 is 1298 m 2 / g, and the specific capacitance is 212F / g at a current density of 0.2A / g.
[0109] The microscopic size of the nitrogen-sulfur co-doped carbon microspheres prepared in Example 1 was tested. Figure 1This is a scanning electron microscope (SEM) image of nitrogen-sulfur-doped carbon microspheres prepared in Example 1 of the present invention. Figure 1 It can be seen that the nitrogen-sulfur co-doped carbon microspheres prepared in Example 1 have good microscopic size uniformity, and the diameter of the nitrogen-sulfur co-doped carbon microspheres is about 200 nm.
[0110] Electrochemical test method: The nitrogen-sulfur co-doped carbon microspheres prepared in Example 1 were mixed with conductive graphite and a binder (polytetrafluoroethylene solution) at a mass ratio of 8:1:1, dried and pressed into discs, which were pressed onto nickel foam at a pressure of 10 MPa, and the pressed electrode sheets were immersed in a 6 mol / L KOH solution for 24 h. Two electrode sheets with similar mass were assembled in a button cell to test their electrochemical properties. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation, and the test methods were cyclic voltammetry and constant current charge-discharge method.
[0111] Figure 2-3 This is the electrochemical test diagram of the nitrogen-sulfur doped carbon microspheres prepared in Example 1. Figure 2 is a cyclic voltammetry (CV) curve of nitrogen-sulfur doped carbon microspheres in Example 1, Figure 3 The constant current charge and discharge curve of nitrogen and sulfur doped carbon microspheres in Example 1. Figure 2 It can be seen from the figure that the curves from 5 to 100 mV / s have good rectangular properties, which is consistent with Figure 3 The constant current charge-discharge curves show good triangular consistency from 0.2-10A / g, indicating that the sample has good rate capability in electrochemical tests. The specific capacitance is 257F / g at a current density of 0.2A / g.
[0112] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0113] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A method for preparing nitrogen-sulfur co-doped carbon microspheres, characterized in that: The following steps are involved: S1, adding resorcinol, formaldehyde and thiourea into a solvent, then adding a catalyst and stirring evenly to carry out a prepolymerization reaction, and after the reaction is completed, a hydrothermal reaction is carried out, and after the hydrothermal reaction is completed, washing and drying are carried out to obtain a carbon microsphere precursor; S2, grinding and mixing the carbon microsphere precursor obtained in S1 and the activator, and activating them under a protective gas atmosphere to obtain nitrogen-sulfur co-doped carbon microspheres; The molar concentrations of resorcinol, formaldehyde and thiourea are all 0.01-0.2 mol / L; The activator is one of potassium hydroxide, sodium hydroxide, carbon dioxide and water vapor; When the activator is potassium hydroxide or sodium hydroxide, the mass ratio of the carbon microsphere precursor to the activator is 1:0.1~2; When the activating agent is carbon dioxide or water vapor, the flow rate of the activating agent is 10~100 mL / min.
2. The method for preparing nitrogen-sulfur co-doped carbon microspheres according to claim 1, characterized in that: In S1, the solvent is prepared by mixing anhydrous ethanol and water in a volume ratio of 2:
5.
3. The method for preparing nitrogen-sulfur co-doped carbon microspheres according to claim 1, characterized in that: In S1, the concentration of the catalyst is 0.01-0.2 mol / L, and the catalyst is one of sodium carbonate, sodium bicarbonate, and ammonia water.
4. The method for preparing nitrogen-sulfur co-doped carbon microspheres according to claim 1, characterized in that: In S1, the prepolymerization reaction temperature is 20-50°C, and the reaction time is 24-36 h.
5. The method for preparing nitrogen-sulfur co-doped carbon microspheres according to claim 1, characterized in that: In S1, the temperature of the hydrothermal reaction is 80-160° C., and the time is 12-72 h.
6. The method for preparing nitrogen-sulfur co-doped carbon microspheres according to claim 1, characterized in that: The protective gas in S2 is nitrogen or argon.
7. The method for preparing nitrogen-sulfur co-doped carbon microspheres according to claim 1, characterized in that: In S2, the activation condition is to increase the temperature to 650-900°C at a heating rate of 2-5°C / min and keep the temperature for 1-4 h.
8. Nitrogen-sulfur co-doped carbon microspheres prepared by the preparation method according to any one of claims 1 to 7.
9. Use of the nitrogen-sulfur co-doped carbon microspheres according to claim 8 in supercapacitors.