Preparation method and application of highly wrinkled nitrogen-doped porous carbon nanosheets
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU ZIJIN PLASTIC
- Filing Date
- 2026-04-10
- Publication Date
- 2026-07-21
Smart Images
Figure CN122436375A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon materials technology, specifically to a method for preparing and applying highly wrinkled nitrogen-doped porous carbon nanosheets. Background Technology
[0002] Porous carbon nanosheets are porous carbon nanomaterials with a sheet-like structure at the nanometer scale. They possess numerous excellent properties, including stable physicochemical properties, high specific surface area, tunable pore structure, controllable microstructure, and good electrical conductivity. Furthermore, they provide more electrolyte ion adsorption sites and redox reaction active sites for charge storage, making them widely used as electrode materials in various advanced energy storage and conversion devices, including lithium-ion batteries, sodium-ion batteries, and supercapacitors. However, the tendency of porous carbon nanosheets to aggregate and stack directly results in a relatively low effective specific surface area and a significantly fewer active sites exposed to the electrolyte, greatly limiting further improvements in their electrochemical performance.
[0003] By fabricating two-dimensional flat porous carbon nanosheets into two-dimensional pleated porous carbon nanosheets, the unique and highly pleated structure within the pleated carbon nanosheets can effectively solve the problems of aggregation and stacking between carbon nanosheets, greatly improving the specific surface area and surface active site utilization of porous carbon nanosheets. This has significant implications and value for applications such as lithium-ion batteries, sodium-ion batteries, supercapacitors, lithium-sulfur batteries, nanocatalysis, and seawater desalination.
[0004] Although there are reports of preparing highly wrinkled porous carbon nanosheets via potassium hydroxide activation, these methods are not only complex and cumbersome, causing severe equipment corrosion, but also produce nanosheets with low nitrogen doping levels (≤3.0 at%). Currently, there is a lack of methods for preparing highly wrinkled porous carbon nanosheets with large specific surface area and high nitrogen doping content. Summary of the Invention
[0005] This invention provides a method for preparing and applying highly wrinkled nitrogen-doped porous carbon nanosheets, which solves the problems mentioned in the background art, such as the complex preparation method, cumbersome steps, severe equipment corrosion, and low nitrogen doping content (≤3.0 at%) of the prepared highly wrinkled porous carbon nanosheets when using the potassium hydroxide activation method.
[0006] The present invention provides the following technical solution: a method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets, using polyethylene as the raw material and melamine as the nitrogen source and expanding agent. During the heating process, polyethylene melts first, and then melamine is thermally decomposed to release a large amount of chemical gas. These chemical gases inflate the molten polyethylene to form a polymer with a honeycomb structure. Finally, the polymer is pyrolyzed in the range of 600-900℃ to obtain highly wrinkled porous carbon nanosheets.
[0007] A highly pleated nitrogen-doped porous carbon nanosheet, wherein the raw materials used in the preparation of the highly pleated porous carbon nanosheet include raw materials, a nitrogen source, an expanding agent, and a protective atmosphere. Wherein: the raw material for preparation is polyethylene; the nitrogen source and the expanding agent are both melamine; and the protective atmosphere is an inert gas.
[0008] Preferably, the polyethylene is particulate matter, and the diameter of the polyethylene particles is 0.5-5 mm.
[0009] Preferably, the mass ratio of polyethylene to melamine is 1:0.5-1:5 by weight.
[0010] Preferably, the inert gas is nitrogen or argon.
[0011] The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to any one of the above-mentioned methods is characterized in that the preparation method includes the following steps: Step 1: Mix polyethylene and melamine in a mass ratio of 1:0.5-1:5 until homogeneous to obtain a mixture precursor; Step 2: The mixture precursor prepared in Step 1 is pyrolyzed in an inert gas to obtain highly wrinkled porous carbon nanosheets. During this process, the mixture precursor is carbonized in a carbonization furnace, and the temperature in the carbonization furnace is first raised to 120-190℃ at a constant heating rate. The polyethylene raw material in the mixture precursor melts at this temperature and is kept at this temperature for 0.2h-1h. After the polyethylene raw material is completely melted, the temperature in the carbonization furnace continues to rise at a constant heating rate to 270-350℃. Melamine decomposes at this temperature and releases a large amount of chemical gases. These chemical gases inflate the molten polyethylene to form a polymer with a honeycomb structure. After being kept at this temperature for 0.3-1h, the melamine is completely decomposed. The temperature in the carbonization furnace continues to rise at a constant heating rate to the final temperature, which is 600-900℃. That is, the polymer finally formed in this step is pyrolyzed in the temperature range of 600-900℃. Step 3: Take out the highly wrinkled porous carbon nanosheets prepared in Step 2.
[0012] Preferably, the pyrolysis temperature is 600-900℃.
[0013] Preferably, the heating rate to the pyrolysis temperature is 3-5 °C / min.
[0014] Preferably, the pyrolysis time is 1-4 hours.
[0015] Preferably, after pyrolysis, the product is further cooled; the target temperature for cooling is 0-36°C, and the prepared nitrogen-doped porous carbon nanosheets are cooled in a carbonization furnace before being taken out.
[0016] The highly wrinkled nitrogen-doped porous carbon nanosheets prepared by any of the above preparation methods are honeycomb-like particles composed of interconnected highly wrinkled nanosheets, with a large number of mesopores and macropores, and the highly wrinkled carbon nanosheets are dispersed from each other and do not stack.
[0017] This invention also provides the application of highly wrinkled nitrogen-doped porous carbon nanosheets, comprising any one of the above-described preparation methods, in supercapacitors. Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method and application of the highly wrinkled nitrogen-doped porous carbon nanosheets: using inexpensive polyethylene and melamine as raw materials, highly wrinkled porous carbon nanosheets can be obtained through a simple one-step high-temperature pyrolysis method. The preparation method is simple, highly operable, and can directly obtain highly wrinkled porous carbon nanosheets without post-processing.
[0018] 2. The preparation method and application of the highly wrinkled nitrogen-doped porous carbon nanosheets, which use a mixture of polyethylene and melamine as precursors for carbonization in a protective atmosphere, can make the prepared samples free of other impurities and have the characteristics of amorphous shape and low degree of graphitization.
[0019] 3. Preparation method and application of the highly wrinkled nitrogen-doped porous carbon nanosheets: The prepared highly wrinkled porous carbon nanosheets are honeycomb-like particles composed of interconnected highly wrinkled nanosheets, with a large number of mesopores and macropores, and the highly wrinkled carbon nanosheets are dispersed from each other without stacking. Attached Figure Description
[0020] Figure 1 X-ray diffraction pattern of the highly wrinkled porous carbon nanosheets prepared in Example 1; Figure 2 This is a scanning electron microscope image of the highly wrinkled porous carbon nanosheets obtained in Example 1; Figure 3 Transmission electron microscope image of the highly wrinkled porous carbon nanosheets obtained in Example 1; Figure 4 This is a high-resolution transmission electron microscope image of the highly wrinkled porous carbon nanosheets obtained in Example 1; Figure 5 The X-ray photoelectron spectrum of the highly wrinkled porous carbon nanosheets obtained in Example 1 is shown below. Figure 6 This is a scanning electron microscope image of the highly wrinkled porous carbon nanosheets obtained in Example 2; Figure 7 This is a scanning electron microscope image of the highly wrinkled porous carbon nanosheets obtained in Example 4; Figure 8 This is a scanning electron microscope image of the highly wrinkled porous carbon nanosheets obtained in Example 5; Figure 9 The image shows a scanning electron microscope (SEM) image of the porous carbon nanosheets obtained in Comparative Example 1. Figure 10 Cyclic voltammetry curves of the working electrode prepared in Application Example 1 at different scan rates; Figure 11 The constant current charge-discharge curves of the working electrode prepared in Application Example 1 at different current densities are shown. Figure 12 The graph shows the specific capacitance curves of the working electrode prepared in Application Example 1 under different current densities. Detailed Implementation
[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] This invention provides an embodiment: This invention provides a highly wrinkled nitrogen-doped porous carbon nanosheet, the raw materials used in the preparation of the highly wrinkled porous carbon nanosheet include a preparation raw material, a nitrogen source, an expanding agent, and a protective atmosphere; wherein: the preparation raw material is polyethylene; the nitrogen source and the expanding agent are both melamine; and the protective atmosphere is an inert gas.
[0023] The polyethylene mentioned above is in granular form, with a diameter of 0.5-5 mm; the mass ratio of the polyethylene to melamine is 1:0.5-1:5 by mass; and the inert gas mentioned above is nitrogen or argon.
[0024] This invention uses inexpensive polyethylene and melamine as raw materials to obtain highly wrinkled nitrogen-doped porous carbon nanosheets through a simple one-step high-temperature pyrolysis method. The preparation method of porous carbon nanosheets provided by this invention specifically includes the following steps: Step 1: Mix the weighed polyethylene and the weighed melamine evenly to obtain the mixture precursor; Step 2: Place the mixture precursor obtained in Step 1 into a carbonization furnace. In an inert gas atmosphere, the temperature inside the carbonization furnace is first increased to 120-190℃ at a constant heating rate of 3-5℃ / min. The polyethylene raw material in the mixture precursor melts at this temperature, and the temperature is maintained for 0.2-1 hours. After the polyethylene raw material is completely melted, the temperature inside the carbonization furnace continues to increase to 270-350℃ at a constant heating rate of 3-5℃ / min. At this temperature, melamine decomposes and releases a large amount of chemical gases. These chemical gases inflate the molten polyethylene, forming a polymer with a honeycomb structure. The temperature is then maintained at a constant level. After 0.3-1 hours, once the melamine has completely decomposed, the temperature in the carbonization furnace continues to rise at a constant rate of 3-5℃ / min until the final temperature is reached. The final temperature in the carbonization furnace is 600-900℃, meaning that the polymer formed in this step undergoes pyrolysis and carbonization within the temperature range of 600-900℃. After carbonization for 1-4 hours, highly wrinkled porous carbon nanosheets are obtained. The prepared highly wrinkled porous carbon nanosheets are honeycomb-like particles composed of interconnected highly wrinkled nanosheets, possessing a large number of mesopores and macropores. Furthermore, the highly wrinkled carbon nanosheets are dispersed among themselves and do not stack.
[0025] Step 3: The highly wrinkled porous carbon nanosheets prepared in Step 2 are removed after cooling in the carbonization furnace.
[0026] Unless otherwise specified, all raw materials used in this invention are preferably commercially available products.
[0027] In this invention, the polyethylene is in the form of particles with a diameter of 0.5-5 mm, more preferably spherical particles with a diameter of 2 mm. The mass ratio of polyethylene to melamine is 1:0.5-1:5, more preferably 1:1. The pyrolysis temperature is 600-900℃, more preferably 700-800℃. In this invention, the carbonization time is preferably 1-4 h, more preferably 2-3 h. In this invention, the heating rate to the carbonization temperature is preferably 3-5℃ / min, more preferably 5℃ / min.
[0028] In this invention, the carbonization is preferably carried out in a protective atmosphere. After carbonization, the target cooling temperature for the resulting material is preferably 0-36°C, more preferably 20-30°C.
[0029] The present invention also provides the application of the highly wrinkled porous carbon nanosheets described above in supercapacitors.
[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention. Example 1
[0031] 10g of polyethylene and 10g of melamine were mixed evenly to obtain a mixture precursor. The obtained mixed precursor was heated to 130℃ in an argon atmosphere at a heating rate of 5℃ / min, held at that temperature for 0.3h, then heated to 300℃, held at that temperature for 0.4h, and finally heated to 800℃. After carbonization for 2h, it was cooled to 25℃ to obtain highly wrinkled porous carbon nanosheets.
[0032] Figure 1 X-ray diffraction pattern of the highly wrinkled porous carbon nanosheets prepared in Example 1. Figure 1 As can be seen from the spectrum, there is a broad diffraction peak at 26º, which corresponds to the diffraction peak position of the graphite (002) crystal plane. This indicates that the sample is an amorphous carbon material, free of other impurities, and has the characteristics of amorphous shape and low degree of graphitization.
[0033] Figure 2 This is a scanning electron microscope (SEM) image of the highly wrinkled porous carbon nanosheets obtained in Example 1. From... Figure 2 It can be seen that highly wrinkled porous carbon nanosheets are honeycomb-like particles composed of interconnected highly wrinkled nanosheets, and the highly wrinkled carbon nanosheets are dispersed from each other and do not stack up.
[0034] Figure 3 This is a transmission electron microscope (TEM) image of the highly wrinkled porous carbon nanosheets obtained in Example 1. From... Figure 3 It can be seen that highly wrinkled porous carbon nanosheets are honeycomb-like particles composed of interconnected highly wrinkled nanosheets, and the highly wrinkled carbon nanosheets are dispersed from each other and do not stack up.
[0035] Figure 4 This is a high-resolution transmission electron microscope (TEM) image of the highly wrinkled porous carbon nanosheets obtained in Example 1. From... Figure 4 As can be seen from the above, the highly wrinkled porous carbon nanosheets prepared in Example 1 of the present invention have a large number of mesopores and macropores.
[0036] Figure 5 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the highly wrinkled porous carbon nanosheets obtained in Example 1. Figure 5 As can be seen from the above, the highly wrinkled porous carbon nanosheets prepared in Example 1 of the present invention are composed of carbon, nitrogen and oxygen elements, wherein the atomic percentage of nitrogen element is 10.3%. Example 2
[0037] 10g of polyethylene and 10g of melamine were mixed evenly to obtain a mixture precursor. The obtained mixed precursor was heated to 130℃ in an argon atmosphere at a heating rate of 5℃ / min, held at that temperature for 0.3h, then heated to 300℃, held at that temperature for 0.4h, and finally heated to 850℃. After carbonization for 2h, it was cooled to 25℃ to obtain highly wrinkled porous carbon nanosheets.
[0038] Figure 6 This is a scanning electron microscope (SEM) image of the highly wrinkled porous carbon nanosheets obtained in Example 2. From... Figure 6 It can be seen that the morphology and structure of the highly wrinkled porous carbon nanosheets are consistent with those in Example 1. Example 3
[0039] 10g of polyethylene and 10g of melamine were mixed evenly to obtain a mixture precursor. The obtained mixed precursor was heated to 130℃ in an argon atmosphere at a heating rate of 5℃ / min, held at that temperature for 0.3h, then heated to 300℃, held at that temperature for 0.4h, and finally heated to 900℃. After carbonization for 2h, it was cooled to 25℃ to obtain highly wrinkled porous carbon nanosheets. Example 4
[0040] 10g of polyethylene and 30g of melamine were mixed evenly to obtain a mixture precursor. The obtained mixed precursor was heated to 130℃ in an argon atmosphere at a heating rate of 5℃ / min, held at that temperature for 0.3h, then heated to 300℃, held at that temperature for 0.8h, and finally heated to 800℃. After carbonization for 2h, it was cooled to 25℃ to obtain highly wrinkled porous carbon nanosheets.
[0041] Figure 7 This is a scanning electron microscope (SEM) image of the highly wrinkled porous carbon nanosheets obtained in Example 4. From... Figure 7 It can be seen that the morphology and structure of the highly wrinkled porous carbon nanosheets are consistent with those in Example 1. Example 5
[0042] 10g of polyethylene and 20g of melamine were mixed evenly to obtain a mixture precursor. The obtained mixed precursor was heated to 130℃ in an argon atmosphere at a heating rate of 5℃ / min, held at that temperature for 0.3h, then heated to 300℃, held at that temperature for 0.6h, and finally heated to 700℃. After carbonization for 2h, it was cooled to 25℃ to obtain highly wrinkled porous carbon nanosheets.
[0043] Figure 8This is a scanning electron microscope (SEM) image of the highly wrinkled porous carbon nanosheets obtained in Example 5. From... Figure 8 It can be seen that the morphology and structure of the highly wrinkled porous carbon nanosheets are consistent with those in Example 1.
[0044] Comparative Example 1 10g of polyethylene precursor was heated to 130℃ in an argon atmosphere at a heating rate of 5℃ / min, held at that temperature for 0.3h, then heated to 300℃, held at that temperature for 0.4h, and finally heated to 800℃. After carbonization for 2h, it was cooled to 25℃ to obtain porous carbon nanosheets.
[0045] Figure 9 This is a scanning electron microscope (SEM) image of the porous carbon nanosheets obtained in Comparative Example 1. From... Figure 9 It can be seen that the porous carbon nanosheets prepared in Comparative Example 1 have a sheet-like structure and a relatively smooth surface. The porous carbon nanosheets without wrinkles have a completely different morphology and structure from those in Example 1.
[0046] Application Example 1 The highly wrinkled porous carbon nanosheets prepared in Example 1 were mixed with acetylene black and polytetrafluoroethylene in a mass ratio of 80:15:5, ground and dispersed, and a certain amount of ethanol was added to grind into a viscous slurry. The slurry was uniformly coated on the nickel foam current collector and dried in an oven at 100°C for 12 hours to obtain the working electrode.
[0047] Then, the electrochemical performance of the highly wrinkled porous carbon nanosheets was tested using a CHI760D electrochemical workstation from Shanghai Chenhua Co., Ltd. in a three-electrode system, employing cyclic voltammetry and constant current charge-discharge technology. The 6 mol•L... −1 A KOH aqueous solution was used as the electrolyte, a 2cm × 2cm platinum sheet as the counter electrode, an Hg / HgO electrode as the reference electrode, and a nickel foam sheet coated with highly wrinkled porous carbon nanosheets as the working electrode. The test results are as follows: Figure 10-12 As shown.
[0048] Figure 10 The figures show the cyclic voltammetry curves of the working electrode prepared in Example 1 at different scan rates of 5, 10, 20, 50, and 200 mV•s. −1 The CV curves are nearly rectangular in shape and lack redox peaks, indicating that the electrode capacity is primarily contributed by the double-layer capacitance. Furthermore, the capacity increases with the scan rate up to 200 mV•s. −1 The CV curve shape still maintains a very good rectangular shape, indicating that the highly wrinkled porous carbon nanosheets have good rate performance.
[0049] Figure 11The graphs show the constant current charge-discharge curves of the working electrode prepared in Example 1 at different current densities of 0.5, 1, 2, 5, and 10 A•g. −1 All charge-discharge curves exhibit a typical triangular symmetric distribution and change linearly with time, indicating that the highly wrinkled porous carbon nanosheets possess excellent double-layer capacitance characteristics, while also demonstrating good reversibility and high coulombic efficiency.
[0050] Figure 12 This is a schematic diagram of the specific capacitance curves of the working electrode prepared in Application Example 1 at different current densities. At 0.5 A•g −1 The specific capacitance at current density reaches 257 F•g −1 When the current density is 10 A•g −1 At that time, its specific capacitance can still be maintained at 192 F•g −1 This indicates that highly pleated porous carbon nanosheets have high specific capacitance and specific capacitance retention.
[0051] It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.
Claims
1. A method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets, characterized in that: The raw materials used in the preparation of the highly pleated porous carbon nanosheets include raw materials, nitrogen source, expanding agent and protective atmosphere; Wherein: the raw material for preparation is polyethylene; the nitrogen source and the expanding agent are both melamine; the protective atmosphere is an inert gas; The preparation method specifically includes the following steps: Step 1: Mix the weighed raw materials polyethylene and melamine evenly to obtain a mixture precursor; Step 2: Place the mixture precursor prepared in Step 1 into a carbonization furnace. In an inert gas atmosphere, the temperature inside the carbonization furnace is gradually increased to the pyrolysis temperature. During the heating process, polyethylene melts first, and the temperature inside the carbonization furnace remains constant during the melting of polyethylene. After the polyethylene is completely melted, the temperature inside the carbonization furnace continues to rise at the same heating rate to the decomposition temperature of melamine. At this temperature, melamine decomposes and releases a large amount of chemical gases. These chemical gases inflate the molten polyethylene to form a polymer with a honeycomb structure. After the melamine is completely decomposed, the temperature inside the carbonization furnace continues to rise to the pyrolysis temperature. Finally, the polymer formed undergoes pyrolysis and carbonization within the pyrolysis temperature range. After the reaction is completed, nitrogen-doped porous carbon nanosheets with high wrinkles are obtained. Step 3: Take out the highly wrinkled nitrogen-doped porous carbon nanosheets prepared in Step 2.
2. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that: The polyethylene is in the form of particulate matter, and the diameter of the polyethylene particles is 0.5-5 mm.
3. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that: The mass ratio of the polyethylene to melamine is 1:0.5-1:5 by weight.
4. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that: The inert gas is nitrogen or argon.
5. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that, In step two, the temperature inside the carbonization furnace is first raised to 120-190℃ at a constant heating rate. The polyethylene raw material in the precursor of the mixture melts at this temperature and is held at this temperature for 0.2h-1h. After the polyethylene raw material has completely melted, the temperature inside the carbonization furnace continues to rise at a constant heating rate to 270-350℃ and is held at this temperature for 0.3-1h. Then, the temperature inside the carbonization furnace continues to rise at a constant heating rate to the final temperature, which is 600-900℃. That is, the polymer finally formed in step two undergoes pyrolysis in the temperature range of 600-900℃.
6. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that, The heating rate in the carbonization furnace is constant, at 3-5℃ / min, and the pyrolysis carbonization time of the polymer finally formed in step two is 1-4h.
7. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that, After pyrolysis, the process further includes cooling the highly wrinkled nitrogen-doped porous carbon nanosheets obtained from the pyrolysis; the target cooling temperature is 0-36℃, and the prepared nitrogen-doped porous carbon nanosheets are taken out after cooling in a carbonization furnace.
8. The method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to claim 1, characterized in that, The highly wrinkled porous carbon nanosheets prepared in step two are honeycomb-like particles composed of interconnected highly wrinkled nanosheets, with a large number of mesopores and macropores, and the highly wrinkled carbon nanosheets are dispersed from each other and do not stack.
9. The highly wrinkled nitrogen-doped porous carbon nanosheets prepared by the method for preparing highly wrinkled nitrogen-doped porous carbon nanosheets according to any one of claims 1-8.
10. The application of a highly pleated porous carbon nanosheet obtained by the preparation method according to any one of claims 1-8 or the highly pleated porous carbon nanosheet according to claim 9 in a supercapacitor.