Sulfur-doped porous spherical carbon and preparation method and application thereof
By using a sulfur-doped porous spherical carbon preparation method with lignin as the carbon source, the problems of high cost and unsustainable resources in the preparation of spherical carbon materials in the prior art have been solved. The method produces porous spherical carbon with high conductivity and catalytic activity, which is suitable for energy storage devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN YUSHILING NEW MATERIAL CO LTD
- Filing Date
- 2024-07-02
- Publication Date
- 2026-06-16
AI Technical Summary
Existing chemical vapor deposition methods for preparing spherical carbon materials suffer from high economic costs and unsustainable resource consumption.
A method for preparing sulfur-doped porous spherical carbon was adopted, using lignin as the carbon source. Sulfur-doped porous spherical carbon was prepared in a hydrogen atmosphere through pre-oxidation and carbonization processes. The porous structure was formed by using sulfur atom dopants and activators to improve the conductivity and catalytic activity of the material.
A low-cost, sustainable preparation of porous spherical carbon materials has been achieved, which have high conductivity and excellent redox catalytic activity, making them suitable for energy storage devices and providing better potassium storage performance and lithium diffusion rate.
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Figure CN118619271B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of carbon materials technology, specifically relating to a sulfur-doped porous spherical carbon, its preparation method, and its application. Background Technology
[0002] Currently, the carbon materials used are generally petrochemical-based, which suffer from problems such as non-renewability, poor environmental performance, and high cost. Spherical carbon, on the other hand, possesses superior properties such as self-sintering ability, chemical inertness, high bulk density, and excellent electrical and thermal conductivity. It is widely used as a high-density, high-strength carbon material, high-performance liquid chromatography column packing material, catalyst support, ultra-high specific surface area activated carbon, and lithium-ion secondary battery anode material, and is receiving increasing attention.
[0003] Currently, chemical vapor deposition (CVD) is a widely used method for preparing spherical carbon. Similar to the preparation of carbon nanotubes, CVD involves catalytically decomposing a carbon-source-containing gas (or vapor) as it flows across the surface of a catalyst, thereby generating carbon spheres. Ethylene, acetylene, styrene, benzene, toluene, and methane are commonly used as carbon sources; these are generally chemically reactive compounds containing unsaturated bonds. Transition metals, rare metals, or metal oxides are often used as catalysts. Argon, nitrogen, or hydrogen are commonly used as carrier gases.
[0004] The above methods are clearly insufficient in terms of both economic cost (high production cost of vapor deposition) and resource sustainability (they cannot achieve resource sustainability). Summary of the Invention
[0005] In view of this, the purpose of this invention is to provide sulfur-doped porous spherical carbon, its preparation method, and its applications. The preparation method provided by this invention is low-cost and resource-sustainable.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] This invention provides a method for preparing sulfur-doped porous spherical carbon, comprising the following steps:
[0008] A sulfur atom dopant, lignin, solvent, activator, and formaldehyde aqueous solution are mixed to obtain a lignin aqueous solution;
[0009] The lignin aqueous solution was pre-oxidized under a weak oxidizing atmosphere to obtain a sulfur-doped porous spherical carbon precursor.
[0010] The sulfur-doped porous spherical carbon precursor was carbonized in a hydrogen atmosphere to obtain sulfur-doped porous spherical carbon.
[0011] The carbonization temperature is 600–1100°C.
[0012] Preferably, the pre-oxidation temperature is 200–300°C and the time is 2–3 hours.
[0013] Preferably, during the pre-oxidation process, the hydrogen flow rate is 320–380 L / h.
[0014] Preferably, during the carbonization process, the hydrogen flow rate is 1 to 1.5 L / min.
[0015] Preferably, the carbonization time is 2.5 to 6.5 hours.
[0016] Preferably, the mixing of the sulfur atom dopant, lignin, solvent, activator, and formaldehyde aqueous solution includes the following steps:
[0017] A sulfur atom dopant, lignin, and solvent are mixed to obtain a lignin solution containing sulfur atom dopant;
[0018] The lignin solution containing sulfur atom dopant is mixed sequentially with an activator and a formaldehyde aqueous solution to obtain the lignin aqueous solution.
[0019] Preferably, the mass ratio of the lignin to the volume ratio of the solvent is (2-5) g: (100-300) mL.
[0020] Preferably, the mass ratio of the sulfur atom dopant to lignin is (1-3):(2-5); the mass ratio of the activator to lignin is (3-15):(2-5); and the mass ratio of lignin to the volume ratio of formaldehyde aqueous solution is (2-5) g:(35-60) mL.
[0021] The present invention provides sulfur-doped porous spherical carbon prepared by the preparation method described above.
[0022] This invention provides the application of the sulfur-doped porous spherical carbon energy storage device described above.
[0023] This invention provides a method for preparing sulfur-doped porous spherical carbon, comprising the following steps: mixing a sulfur atom dopant, lignin, a solvent, an activator, and a formaldehyde aqueous solution to obtain a lignin aqueous solution; pre-oxidizing the lignin aqueous solution under a weak oxidizing atmosphere to obtain a sulfur-doped porous spherical carbon precursor; and carbonizing the sulfur-doped porous spherical carbon precursor under a hydrogen atmosphere to obtain sulfur-doped porous spherical carbon; wherein the carbonization temperature is 600–1100 °C.
[0024] In this invention, heteroatom-doped porous carbon materials can provide better potassium storage performance and lithium diffusivity. Heteroatom dopants (sulfur dopants such as thiosulfates, mercapto compounds, and elemental sulfur can introduce sulfur atoms) provide high conductivity, promote Faraday reactions, and stabilize the crystal structure of primary particles (primary particles refer to nanoscale carbon particles that exist as basic units throughout the formation of porous carbon spheres). By increasing the Faraday pseudocapacitance of the porous carbon spheres, the conductivity is significantly improved, or the electronic properties of the porous carbon material can be improved through rapid charge transfer during charging and discharging. Heteroatom-doped porous carbon materials can further be used as substrates for loading other active components. Therefore, the porous carbon materials provided by this invention have broad application potential and can provide excellent performance in a variety of energy storage devices.
[0025] This method uses biomass lignin as raw material, which is resource-sustainable, has low energy consumption, and is easy to mass-produce. The preparation method provided by this invention is simple to operate, consumes little energy, has low cost, and produces sulfur-doped porous spherical carbon with high purity. The preparation method provided by this invention can be used for continuous production, uses inexpensive raw materials, is safe and non-toxic, and produces sulfur-doped porous spherical carbon with small particle size, uniform distribution, light particle agglomeration, good crystal morphology, and controllable particle size. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a flowchart illustrating the preparation of sulfur-doped porous spherical carbon according to the present invention;
[0028] Figure 2 The X-ray photoelectron spectroscopy (XPS) spectrum (a) and Raman spectrum (b) of the sulfur-doped porous spherical carbon obtained in Example 1 are shown.
[0029] Figure 3 The images shown are transmission electron microscope (TEM) images (a) and scanning electron microscope (SEM) images (b) and (c) of the sulfur-doped porous spherical carbon obtained in Example 1.
[0030] Figure 4 The images show the adsorption-desorption isotherms (a) and pore size distribution (b) of the sulfur-doped porous spherical carbon and nitrogen gas obtained in Example 1. Detailed Implementation
[0031] This invention provides a method for preparing sulfur-doped porous spherical carbon, comprising the following steps:
[0032] A sulfur atom dopant, lignin, solvent, activator, and formaldehyde aqueous solution are mixed to obtain a lignin aqueous solution;
[0033] The lignin aqueous solution was pre-oxidized under a weak oxidizing atmosphere to obtain a sulfur-doped porous spherical carbon precursor.
[0034] The sulfur-doped porous spherical carbon precursor was carbonized in a hydrogen atmosphere to obtain sulfur-doped porous spherical carbon.
[0035] In this invention, unless otherwise specified, all raw materials and equipment used are commercially available products well known in the art.
[0036] This invention involves mixing a sulfur atom dopant, lignin, a solvent, an activator, and a formaldehyde aqueous solution to obtain a lignin aqueous solution.
[0037] In this invention, the mixing of sulfur atom dopant, lignin, solvent, activator, and formaldehyde-water solution preferably includes the following steps:
[0038] A sulfur atom dopant, lignin, and solvent are mixed to obtain a lignin solution containing sulfur atom dopant;
[0039] The lignin solution containing sulfur atom dopant is mixed sequentially with an activator and a formaldehyde aqueous solution to obtain the lignin aqueous solution.
[0040] In this invention, the sulfur atom dopant preferably includes one or more of thiosulfate, mercapto compound and elemental sulfur.
[0041] In this invention, the solvent preferably includes one or more of water, methanol, ethanol and isopropanol.
[0042] In this invention, the preferred mass ratio of lignin to solvent volume is (2-5) g:(100-300) mL, and more preferably (2.5-4.5) g:(150-250) mL.
[0043] In this invention, the preferred mass ratio of the sulfur atom dopant to lignin is (1-3):(2-5), more preferably (1.5-2.5):(3-4.5); the preferred mass ratio of the activator to lignin is (3-15):(2-5), more preferably (5-12):(3-4.5); the preferred mass ratio of lignin to the volume ratio of the formaldehyde aqueous solution is (2-5) g:(35-60) mL, more preferably (2.5-4.5) g:(40-55) mL.
[0044] In this invention, by doping with sulfur (S) atoms, the doped carbon microspheres can overcome the disadvantages of poor surface wettability, insufficient chemical reactivity and few surface active sites caused by being composed of a single carbon atom, thereby possessing better redox catalytic activity and higher specific capacitance.
[0045] In this invention, sulfur acts as a pore-forming agent, migrating and volatilizing during carbonization and activation to form a porous structure in the carbon material. Different sulfur contents affect the pore characteristics; sulfur pyrolysis can generate small molecules such as H2S, which plays a role in the carbonization of sulfur-doped porous spherical carbon precursors to form graphite nuclei under a reducing atmosphere; some sulfides participate in subsequent activation reactions, such as potassium sulfides, affecting the structure and properties of the carbon material; sulfur may introduce a small amount of sulfur doping during the carbonization process, altering the electronic structure and chemical properties of the carbon material.
[0046] In this invention, the activator preferably comprises a hydroxide, and the hydroxide preferably comprises potassium hydroxide. In this invention, the activator can provide hydroxide ions and activate the surface of carbon materials, increasing the number and activity of their active sites.
[0047] In this invention, the mass concentration of the formaldehyde aqueous solution is preferably 36%. In this invention, the formaldehyde aqueous solution has the function of catalytic oxidation and increasing the active sites of lignin, laying the foundation for finally obtaining high-performance spherical carbon.
[0048] After obtaining the lignin aqueous solution, the present invention pre-oxidizes the lignin aqueous solution under a weak oxidizing atmosphere to obtain a sulfur-doped porous spherical carbon precursor.
[0049] In this invention, the weak oxidizing atmosphere preferably includes hydrogen and oxygen; wherein the volume fraction of hydrogen is preferably ≥85% and the volume fraction of oxygen is preferably ≤15%, and the specific ratio can be adjusted according to experimental requirements to achieve the best pre-oxidation effect.
[0050] In this invention, the pre-oxidation temperature is preferably 200-300°C, more preferably 220-280°C; the time is preferably 2-3 hours, more preferably 2.2-2.5 hours.
[0051] During the pre-oxidation process, the hydrogen flow rate is preferably 320-380 L / h, and more preferably 357 L / h.
[0052] In this invention, the pre-oxidation is preferably carried out in a cyclone separator or a spray dryer.
[0053] This invention enables the formation of an oxide layer on the surface of carbon materials through pre-oxidation, thereby enhancing their chemical reactivity and catalytic activity. In a high-temperature hydrogen environment, lignin molecules undergo a series of pyrolysis, dehydration, and condensation reactions, generating intermediates containing numerous active functional groups (such as hydroxyl and carbonyl groups). These active functional groups react with trace amounts of oxygen or water vapor in the gas phase to form various oxides on the surface of the carbon material, such as hydroxyl, carbonyl, and carboxyl groups. (Pre-oxidation occurs under a hydrogen-protected atmosphere; during activation, residual oxygen in the equipment and moisture released from the pyrolysis of lignin may provide trace amounts of oxygen and water vapor, leading to the formation of surface oxides.)
[0054] The main purpose of pre-oxidation under a weak oxidizing atmosphere is to control the degree of lignin oxidation, avoid over-oxidation and side reactions, and promote the formation of a uniform, pure, and stable sulfur-doped porous spherical carbon precursor. This process helps improve the quality of the precursor, provides a good foundation for subsequent carbonization treatment, and ultimately optimizes the performance of the carbon material.
[0055] After obtaining the sulfur-doped porous spherical carbon precursor, the present invention carbonizes the sulfur-doped porous spherical carbon precursor in a hydrogen atmosphere to obtain sulfur-doped porous spherical carbon.
[0056] In this invention, the carbonization temperature is 600-1100℃, more preferably 700-1000℃, and even more preferably 800-950℃; the carbonization time is preferably 2.5-6.5h, more preferably 2-3h, and even more preferably 2.2-2.5h.
[0057] During the carbonization process, the flow rate of hydrogen is preferably 1 to 1.5 L / min, and more preferably 1.1 to 1.4 L / min.
[0058] In the carbonization process described in this invention, the organic matter in the sulfur-doped porous spherical carbon precursor is converted into carbon material. The carbonized product is usually amorphous carbon or low-degree graphitized carbon, and its structure contains a large number of defects and amorphous carbon components.
[0059] During the carbonization process, hydrogen can act as a reducing agent, causing oxides and other impurities in the carbon material to be reduced into gaseous volatilization, thereby increasing the purity of the carbon material.
[0060] After carbonization is completed, the present invention preferably washes and dries the resulting carbonized material in sequence.
[0061] In this invention, the washing is preferably performed using a hydrochloric acid solution; the washing is preferably performed until the pH value of the washing solution is 7. In this invention, the mass fraction of the hydrochloric acid solution is preferably 37%.
[0062] This invention removes various impurities from sulfur-doped porous spherical carbon through washing and adjusts the pH value, thereby enhancing its chemical activity and purity and providing better performance assurance for subsequent applications. The washing process is a key step in the preparation of high-performance sulfur-doped porous spherical carbon.
[0063] Figure 1 This is a flowchart illustrating the preparation of sulfur-doped porous spherical carbon according to the present invention. As shown in the figure, elemental sulfur (sulfur atom dopant), lignin, and solvent (i.e.,...) are added... Figure 1 Mix the deionized water in the solution with water and stir, then add the activator (i.e., deionized water) in sequence. Figure 1 The lignin aqueous solution is prepared by reacting potassium hydroxide (in a solution of formaldehyde) with an aqueous formaldehyde solution; then, the lignin aqueous solution is pre-oxidized in a cyclone separator or spray dryer under a hydrogen atmosphere (weak oxidizing atmosphere) to obtain a sulfur-doped porous spherical carbon precursor (i.e., Figure 1 (Medium lignin); then the sulfur-doped porous spherical carbon precursor is carbonized in a hydrogen atmosphere (i.e., Figure 1 (Dried at 700℃), and washed with hydrochloric acid to obtain sulfur-doped porous spherical carbon.
[0064] This invention uses low-cost, renewable, and biodegradable commercial lignin as a carbon source to prepare sulfur-doped porous spherical carbon. Compared with existing technologies that use carbon nanomaterials as raw materials, this invention has the advantages of readily available raw materials, full consideration of energy conservation and environmental protection principles, and is of great significance for the sustainable development of resources and the environment. It is also one of the effective ways to achieve high-value utilization of lignin.
[0065] The preparation method provided by this invention is simple, has low preparation cost, and has good practical application value.
[0066] The present invention provides sulfur-doped porous spherical carbon prepared by the preparation method described above.
[0067] The sulfur-doped porous spherical carbon provided by this invention has a good microstructure and excellent dispersion properties, which can improve the performance of lignin carbon materials.
[0068] The sulfur-doped porous spherical carbon provided by this invention has good magnetic properties and has promising application prospects in fields such as information, energy, detection and biology.
[0069] This invention provides the application of the sulfur-doped porous spherical carbon described above in energy storage devices.
[0070] In this invention, heteroatom-doped porous carbon materials can provide better potassium storage performance and lithium diffusivity. Heteroatom dopants (sulfur dopants such as thiosulfates, mercapto compounds, and elemental sulfur can introduce sulfur atoms) provide high conductivity, promote Faraday reactions, and stabilize the crystal structure of primary particles (primary particles refer to nanoscale carbon particles that exist as basic units throughout the formation of porous carbon spheres). By increasing the Faraday pseudocapacitance of the porous carbon spheres, the conductivity is significantly improved, or the electronic properties of the porous carbon material can be improved through rapid charge transfer during charging and discharging. Heteroatom-doped porous carbon materials can further be used as substrates for loading other active components. Therefore, the porous carbon materials provided by this invention have broad application potential and can provide excellent performance in a variety of energy storage devices.
[0071] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a sulfur-doped porous spherical carbon, its preparation method, and its applications, but these descriptions should not be construed as limiting the scope of protection of the present invention.
[0072] Example 1
[0073] Weigh 1.2g of elemental sulfur and 2.4g of lignin, use 120mL of deionized water as solvent, stir and dissolve to obtain a lignin solution containing elemental sulfur;
[0074] Add 4g of potassium hydroxide to the lignin solution containing elemental sulfur and stir to dissolve. Then add 42mL of 36% formaldehyde aqueous solution to obtain lignin aqueous solution.
[0075] The lignin aqueous solution was dried in a cyclone separator using hydrogen as the carrier gas, with a flow rate of 357 L / h and a temperature of 200 °C for 2.5 h, to obtain a sulfur-doped porous spherical carbon precursor (lignin powder with a content of 90-95% or more).
[0076] 200g of the sulfur-doped porous spherical carbon precursor was placed in a tube furnace and carbonized at 850℃. The carbonization process was carried out in hydrogen gas at a flow rate of 1L / min for 4h. The resulting carbon spheres were then rinsed in 3000mL of hydrochloric acid (37% by mass) until the pH value reached 7. After drying, the sulfur-doped porous spherical carbon was obtained.
[0077] The sulfur-doped porous spherical carbon obtained in this embodiment exhibits a good spherical morphology, and at the same time, the sulfur-doped porous spherical carbon has good dispersion performance.
[0078] Figure 2The images show the X-ray photoelectron spectroscopy (XPS) spectrum (a) and Raman spectrum (b) of the sulfur-doped porous spherical carbon obtained in Example 1. The peaks in (a) correspond to the chemical states of sulfur in the sample, particularly the chemical bonds formed between sulfur and carbon, which can be used to analyze the form and relative content of sulfur in the sample. The XPS spectrum shows different chemical states of sulfur: 1. CSC: approximately 164 eV, representing the chemical state where sulfur atoms are bonded to two carbon atoms, forming a thiophene-like state. 2. The second is the S2p state.
[0079] The relative sulfur content is given by the peak area in the figure. Based on the relative height and width of each peak, the relative sulfur content is 10-15%.
[0080] (b) shows the results at different Raman displacements (cm). -1 The spectral intensity distribution under ( ) is shown. It can be seen that the Raman spectrum of the carbon material has two significant peaks: the D peak (approximately 1350 cm⁻¹). -1 ) and G peak (approximately 1580cm) -1 The D peak corresponds to defective or disordered carbon atoms in carbon materials, while the G peak corresponds to carbon atoms in an ordered graphite structure. The relative intensity and position of these two peaks can be used to determine the crystallinity and graphitization degree of carbon materials: from the Raman spectrum, if the ID / IG ratio is between 1.0 and 2.0, it indicates that the sample has a moderate to low degree of crystallinity and graphitization.
[0081] Figure 3 Images of the sulfur-doped porous spherical carbon obtained in Example 1 are shown in transmission electron microscopy (TEM) image (a) and scanning electron microscopy (SEM) images (b) and (c). (a) Transmission electron microscopy (TEM) image: shows the nanoscale microstructure of the material. Analysis: The image shows many interconnected nanoscale pores, with black areas representing pores. The size and distribution of these pores indicate that the material has a nanoscale porous structure: from Figure 3 The scanning electron microscope (SEM) image in (a) shows that the diameter of the particles is approximately less than 1 μm. This means that the particle size is between 100 nm and 1 μm.
[0082] Figure 3Images (b) and (c) in Figure 1 are scanning electron microscope (SEM) images at different magnifications (scale bars of 1 μm and 200 nm, respectively): showing the surface morphology of the material. Analysis: The images show a large number of spherical particles, whose surfaces may have a porous structure. The SEM images provide a wider range of structural information, revealing the overall porous nature of the material: the particle size is more clearly visible in the transmission electron microscope (TEM) images (b) and (c). The particles shown in (c) are significantly smaller than 200 nm. Therefore, the size of these nanoparticles is approximately between tens of nanometers and 200 nanometers.
[0083] Figure 4 The images show the adsorption-desorption isotherms (a) and pore size distribution (b) of the sulfur-doped porous spherical carbon and nitrogen gas obtained in Example 1. Figure 4 In diagram (a), the nitrogen adsorption-desorption isotherm shows a rapid increase in adsorption at low relative pressure, indicating the presence of numerous micropores in the sample. The adsorption at high relative pressure increases dramatically, indicating the presence of mesopores or macropores in the sample. Figure 4 The pore size distribution in (b) shows a significant peak in the range of 5–10 nm, indicating that the sample contains abundant mesoporous structures.
[0084] Example 2
[0085] Weigh 1.5g of elemental sulfur and 3g of lignin, use 150mL of deionized water as solvent, stir and dissolve to obtain a lignin solution containing elemental sulfur;
[0086] Add 6g of potassium hydroxide to the lignin solution containing elemental sulfur and stir to dissolve. Then add 50mL of 36% formaldehyde aqueous solution to obtain lignin aqueous solution.
[0087] The lignin aqueous solution was dried in a cyclone separator using hydrogen as the carrier gas, with a flow rate of 357 L / h and a temperature of 250 °C for 2.5 h, to obtain a sulfur-doped porous spherical carbon precursor (lignin powder with a content of 90-95% or more).
[0088] 200g of the sulfur-doped porous spherical carbon precursor was placed in a tube furnace and carbonized at 850℃. The carbonization process was carried out in hydrogen gas at a flow rate of 1L / min for 5h. The resulting carbon spheres were then rinsed in 3200mL of hydrochloric acid (37% by mass) until the pH value reached 7. After drying, sulfur-doped porous spherical carbon was obtained.
[0089] The sulfur-doped porous spherical carbon obtained in this embodiment exhibits a good spherical morphology and good dispersion performance.
[0090] Example 3
[0091] Weigh 2g of elemental sulfur and 4g of lignin, use 240mL of deionized water as solvent, stir to dissolve, and obtain a lignin solution containing elemental sulfur.
[0092] Add 10g of potassium hydroxide to the lignin solution containing elemental sulfur and stir to dissolve. Then add 55mL of 36% formaldehyde aqueous solution to obtain lignin aqueous solution.
[0093] The lignin aqueous solution was dried in a cyclone separator using hydrogen as the carrier gas, with a flow rate of 357 L / h and a temperature of 275 °C for 2.5 h, to obtain a sulfur-doped porous spherical carbon precursor (lignin powder with a content of 90-95% or more).
[0094] 200g of the sulfur-doped porous spherical carbon precursor was placed in a tube furnace and carbonized at 850℃. The carbonization process was carried out in hydrogen gas at a flow rate of 1L / min for 6h. The resulting carbon spheres were then rinsed in 3500mL of hydrochloric acid (37% by mass) until the pH value reached 7. After drying, sulfur-doped porous spherical carbon was obtained.
[0095] The sulfur-doped porous spherical carbon obtained in this embodiment exhibits a good spherical morphology and good dispersion performance.
[0096] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for preparing sulfur-doped porous spherical carbon, characterized in that, Includes the following steps: A sulfur atom dopant, lignin, solvent, activator, and formaldehyde aqueous solution are mixed to obtain a lignin aqueous solution; The lignin aqueous solution was pre-oxidized under a weak oxidizing atmosphere to obtain a sulfur-doped porous spherical carbon precursor. The sulfur-doped porous spherical carbon precursor was carbonized in a hydrogen atmosphere to obtain sulfur-doped porous spherical carbon. The carbonization temperature is 600–1100°C.
2. The preparation method according to claim 1, characterized in that, The pre-oxidation temperature is 200–300°C, and the time is 2–3 hours.
3. The preparation method according to claim 1 or 2, characterized in that, During the pre-oxidation process, the hydrogen flow rate is 320–380 L / h.
4. The preparation method according to claim 1, characterized in that, During the carbonization process, the hydrogen flow rate is 1 to 1.5 L / min.
5. The preparation method according to claim 1 or 4, characterized in that, The carbonization time is 2.5 to 6.5 hours.
6. The preparation method according to claim 1, characterized in that, The process of mixing the sulfur atom dopant, lignin, solvent, activator, and formaldehyde aqueous solution includes the following steps: A sulfur atom dopant, lignin, and solvent are mixed to obtain a lignin solution containing sulfur atom dopant; The lignin solution containing sulfur atom dopant is mixed sequentially with an activator and a formaldehyde aqueous solution to obtain the lignin aqueous solution.
7. The preparation method according to claim 1 or 6, characterized in that, The mass ratio of the lignin to the volume ratio of the solvent is (2-5) g: (100-300) mL.
8. The preparation method according to claim 1 or 6, characterized in that, The mass ratio of the sulfur atom dopant to lignin is (1-3):(2-5); the mass ratio of the activator to lignin is (3-15):(2-5); and the mass ratio of lignin to the volume ratio of formaldehyde aqueous solution is (2-5) g:(35-60) mL.
9. Sulfur-doped porous spherical carbon prepared by the preparation method according to any one of claims 1 to 8.
10. The application of the sulfur-doped porous spherical carbon according to claim 9 in energy storage devices.