Porous carbon material as well as preparation method and application thereof

Abstract

The embodiment of the invention relates to a porous carbon material as well as a preparation method and application thereof, and the preparation method comprises the following steps: dissolving a phenol source in an anhydrous polar solution, adding cyclic organosiloxane with a preset size, and stirring, so that the phenol source and the cyclic organosiloxane are uniformly mixed to obtain a first mixed solution; adding organic alkali into the first mixed solution to enable the first mixed solution to be alkalescent, then adding an aldehyde source, and stirring to enable hydroxyl of the phenol source and carbonyl carbon of the aldehyde source to be subjected to an addition reaction to generate hemiacetal; carrying out heat treatment on the hemiacetal to enable the hemiacetal to be subjected to condensation reaction, and then washing and drying to obtain an organic silicon / phenolic resin compound; carrying out carbonization treatment on the organic silicon / phenolic resin compound in an inert atmosphere to generate a carbonized product; washing the carbonized product to remove silicon oxide in the carbonized product to form a pore structure, and then passivating to obtain the porous carbon material.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a porous carbon material, its preparation method, and its application. Background Technology

[0002] Nanoporous carbon materials possess high specific surface area, porous structure, and excellent chemical, mechanical, and thermal stability, making them widely applicable in energy storage and conversion, catalysis, and sensing. According to the International Union of Pure and Applied Chemistry (IUPAC), porous carbon materials can be classified into three categories based on pore size: macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). Correspondingly, porous carbon materials can be classified into microporous materials, mesoporous materials, and macroporous materials. The pore structure and size of porous carbon materials are closely related to their application performance.

[0003] Micropores can significantly increase the specific surface area of ​​materials, enabling them to possess highly efficient adsorption and separation properties. In silicon-carbon anodes, micropores can tightly encapsulate silicon nanoparticles, limiting their volume expansion and thus improving the electrode's cycle stability. The high specific surface area of ​​the microporous structure ensures more uniform contact between the electrolyte and the active material, facilitating the formation of a stable solid electrolyte interphase (SEI) film. This uniform SEI film is less prone to rupture during charge and discharge, thereby reducing irreversible capacity loss and improving coulombic efficiency.

[0004] Mesoporous materials have the advantages of large pore capacity and flexible, tunable pore structure. In silicon-carbon anodes, mesopores excel in buffering the expansion of silicon nanoparticles, enhancing ion transport rates, improving electrochemical reaction kinetics, and increasing structural stability.

[0005] In summary, micropores and mesopores each exhibit unique advantages in silicon-carbon anode materials. Micropores have significant advantages in limiting silicon volume expansion, forming a stable SE I film, and improving electrode energy density, while mesopores perform well in buffering silicon expansion, increasing ion transport rate, enhancing electrochemical reaction kinetics, and improving structural stability.

[0006] Therefore, how to precisely control the pore size of porous carbon materials and maximize the combination of the advantages of micropores and mesopores to provide strong support for optimizing the electrochemical performance of silicon-carbon anode materials is an urgent problem to be solved in the current research field.

[0007] Current technologies primarily use silica as a template to control the pore size of porous carbon. However, the uneven distribution of silica within the carbon source leads to inconsistent pore sizes. Dense regions of silica result in larger pores, while sparse regions form smaller pores. Since silica dimensions range from approximately 2nm to 100nm, forming micropores is difficult. Furthermore, this unevenness leads to instability in the specific surface area and pore structure of porous carbon materials, thus affecting the overall performance of the material. Summary of the Invention

[0008] The purpose of this invention is to address the deficiencies of existing technologies by providing a porous carbon material, its preparation method, and its application. This preparation method uses cyclic organosiloxanes of a predetermined size to prepare porous carbon materials, achieving the effect of controllable adjustment of the pore size of the porous carbon material.

[0009] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing porous carbon materials, the method comprising:

[0010] The phenol source is dissolved in an anhydrous polar solution, and a cyclic organosiloxane of a predetermined size is added and stirred to make the phenol source and the cyclic organosiloxane mix evenly, thus obtaining the first mixture.

[0011] An organic base is added to the first mixture to make it weakly alkaline. Then, an aldehyde source is added and stirred to allow the hydroxyl group of the phenol source to undergo an addition reaction with the carbonyl carbon of the aldehyde source to generate a hemiacetal. The hemiacetal is then heat-treated to cause a condensation reaction. After washing and drying, an organosilicon / phenolic resin composite is obtained.

[0012] The organosilicon / phenolic resin composite was carbonized under an inert atmosphere to generate carbonized products.

[0013] The carbonized product is washed to remove the silicon oxide that forms a porous structure, and then passivated to obtain a porous carbon material.

[0014] Preferably, the phenol source includes one or more of resorcinol, catechol, m-cresol, and p-cresol; the anhydrous polar solvent includes one or more of anhydrous ethanol, anhydrous acetone, anhydrous dimethylformamide, and anhydrous N-methylpyrrolidone; and the cyclic organosiloxane includes one or more of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane.

[0015] Preferably, the organic base includes one or more of triethylamine, dimethylamine, pyridine, and methylethylamine; the aldehyde source includes one or more of formaldehyde, acetaldehyde, and furfural.

[0016] Preferably, the heat treatment conditions are: temperature 40℃-80℃, time 5 hours-16 hours.

[0017] Preferably, the carbonization treatment conditions are: temperature of 700℃-900℃ and time of 1 hour-3 hours.

[0018] Preferably, the washing solution includes either hydrofluoric acid or sodium hydroxide.

[0019] Preferably, the passivation treatment conditions are: temperature 800℃-1000℃, time 1 hour-3 hours.

[0020] In a second aspect, the present invention provides a porous carbon material, which is prepared by any of the preparation methods described in the first aspect above.

[0021] Thirdly, the present invention provides a negative electrode sheet, the negative electrode sheet comprising the porous carbon material described in the second aspect.

[0022] Fourthly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising the negative electrode sheet described in the third aspect.

[0023] The present invention provides a method for preparing porous carbon materials. This method utilizes the property that cyclic organosiloxanes do not undergo hydrolytic polymerization in anhydrous systems and under weakly alkaline conditions. By selecting cyclic organosiloxanes of different molecular sizes, these cyclic organosiloxanes are encapsulated during the formation of phenolic resin. After carbonization and template removal, porous carbon materials are obtained. The pore size of the porous carbon material is related to the molecular size of the added cyclic organosiloxanes, making the pore size controllable and the pore structure uniformly distributed. This preparation method is simple, easy to operate, and highly practical. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for preparing porous carbon materials according to an embodiment of the present invention;

[0025] Figure 2 This is a SEM image of the porous carbon material provided in Embodiment 4 of the present invention;

[0026] Figure 3 This is a pore size distribution diagram of the porous carbon material provided in Embodiment 2 of the present invention;

[0027] Figure 4 This is a pore size distribution diagram of the porous carbon material provided in Comparative Example 2 of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] This invention provides a method for preparing porous carbon materials, the process of which is as follows: Figure 1 As shown, it includes the following steps:

[0031] Step 110: Dissolve the phenol source in an anhydrous polar solution, add a cyclic organosiloxane of a preset size and stir to make the phenol source and cyclic organosiloxane mix evenly to obtain the first mixture.

[0032] Specifically, the phenol source may include one or more of resorcinol, catechol, m-cresol, and p-cresol. The anhydrous polar solvent may include one or more of anhydrous ethanol, anhydrous acetone, anhydrous dimethylformamide, and anhydrous N-methylpyrrolidone. The concentration of the phenol source in the anhydrous polar solution may be 0.1 g / mL to 0.3 g / mL.

[0033] Cyclic organosiloxanes may include one or more of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane. The concentration of cyclic organosiloxanes may be 0.9 mol / L to 1.1 mol / L.

[0034] The molecular structures of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane are shown below:

[0035]

[0036] This shows that the size of the siloxane (Si-O-Si) skeleton varies significantly in different cyclic organosiloxanes.

[0037] In this step, the anhydrous polar solution can dissolve the phenol source while preventing the hydrolysis of the cyclic organosiloxane, thus preserving the intact Si-O-Si bond framework of the cyclic organosiloxane. Different cyclic organosiloxanes have different molecular sizes and occupy different spaces, resulting in different pore sizes after removal. Therefore, the preset size is determined according to the required pore size.

[0038] Step 120: Add an organic base to the first mixture to make the first mixture weakly alkaline. Then, add an aldehyde source and stir to allow the hydroxyl group of the phenol source and the carbonyl carbon of the aldehyde source to undergo an addition reaction to generate a hemiacetal. Then, heat-treat the hemiacetal to allow it to undergo a condensation reaction. After washing and drying, obtain an organosilicon / phenolic resin composite.

[0039] Specifically, the organic base may include one or more of triethylamine, dimethylamine, pyridine, and methylethylamine. The amount of organic base used is 0.8%-1.2% of the total solution volume. The role of the organic base is to make the first mixture weakly alkaline, which also prevents the hydrolysis of cyclic organosiloxanes. The aldehyde source may include one or more of formaldehyde, acetaldehyde, and furfural.

[0040] The addition reaction is carried out at room temperature. Stirring can be performed during the addition reaction. The addition reaction time is 1 hour to 3 hours, preferably 2 hours.

[0041] The heat treatment conditions can be: temperature 40℃-80℃, preferably 60℃, time 5 hours-16 hours, preferably 10 hours.

[0042] Deionized water can be used for washing, and the number of washing cycles can be 3-5. After each washing, the supernatant should be removed. The centrifugation speed for each cycle can be 8000r / min-10000r / min, preferably 9000r / min, and the time can be 2min-5min, preferably 3min.

[0043] The drying process can be carried out in a vacuum drying oven at a temperature of 50℃-70℃, preferably 60℃, for a time of 10-15 hours, preferably 12 hours.

[0044] In this step, during the hemiacetal condensation, cyclic organosiloxanes are uniformly distributed within the three-dimensional network structure of the phenolic resin. Because the cyclic organosiloxanes have different molecular sizes, they occupy different amounts of space within the three-dimensional network.

[0045] Step 130: Under an inert atmosphere, the organosilicon / phenolic resin composite is carbonized to generate carbonized products.

[0046] Specifically, the inert atmosphere can be nitrogen and / or argon. The carbonization treatment can be carried out in a tube furnace under the following conditions: a heating rate of 2°C / min-8°C / min, preferably 3°C / min; a temperature of 700°C-900°C, preferably 800°C; and a time of 1 hour-3 hours, preferably 2 hours. The purpose of the carbonization treatment is to convert the organic groups in the phenolic resin and cyclic organosiloxanes into amorphous carbon, while the silicon-oxygen bonds (Si-O-Si) framework in the cyclic organosiloxanes break to generate silicon oxides such as silicon dioxide and carbon-silicon oxide complexes.

[0047] Step 140: The carbonized product is washed to remove the silicon oxide that forms a porous structure, and then passivated to obtain a porous carbon material.

[0048] Specifically, the washing solution can include either hydrofluoric acid or sodium hydroxide. The concentration of hydrofluoric acid can be 10 wt%, and the concentration of sodium hydroxide can be 1 mol / L. The purpose of the washing process is to remove silicon oxides such as silica and carbosiloxanes, allowing the silicon oxide sites to form porous structures—essentially a template removal process. If the added cyclic organosiloxanes have different molecular sizes, the different ring sizes of the silicon oxide rings within them will create pore structures of varying sizes, resulting in a diverse and uniformly distributed pore structure within the porous carbon material. In other words, the pore size of the porous carbon material is controlled by the molecular size of the cyclic organosiloxanes.

[0049] Passivation treatment mainly removes unnecessary oxygen-containing functional groups and other organic substances, ensuring the purity, oxidation resistance, and surface stability of porous carbon materials. It can be carried out in a tube furnace. The specific conditions for passivation treatment are: an atmosphere of nitrogen and / or argon, a temperature of 800℃-1000℃, preferably 900℃, and a time of 1 hour-3 hours, preferably 2 hours.

[0050] The present invention provides a method for preparing porous carbon materials. This method utilizes the property that cyclic organosiloxanes do not undergo hydrolytic polymerization in anhydrous systems and under weakly alkaline conditions. By selecting cyclic organosiloxanes of different molecular sizes, these cyclic organosiloxanes are encapsulated during the formation of phenolic resin. After carbonization and template removal, porous carbon materials are obtained. The pore size of the porous carbon material is related to the molecular size of the added cyclic organosiloxanes, making the pore size controllable and the pore structure uniformly distributed. This preparation method is simple, easy to operate, and highly practical.

[0051] The porous carbon material provided by this invention can be used as an electrode material in energy storage devices such as supercapacitors, lithium-ion batteries, sodium-ion batteries, and dye-sensitized batteries.

[0052] To better understand the technical solution provided by the present invention, the following uses several specific examples to illustrate the specific process of preparing porous carbon materials using the method provided in the above embodiments of the present invention, as well as the characteristics of the prepared porous carbon materials.

[0053] Example 1

[0054] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous ethanol, and then add 111g of hexamethylcyclotrisiloxane dropwise while stirring for 30min to ensure that the hexamethylcyclotrisiloxane and resorcinol are evenly dispersed to obtain a mixture.

[0055] In the second step, 5 mL of triethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating hexamethylcyclotrisiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the organosilicon / phenolic resin composite.

[0056] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and hexamethylcyclotrisiloxane into amorphous carbon, while the silicon-oxygen bond (Si-OSi) skeleton in hexamethylcyclotrisiloxane breaks to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0057] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0058] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0059] The methods used to determine the properties of porous carbon materials are all commonly used techniques in this field, and will be briefly described below:

[0060] 1. Determination of specific surface area, pore size, and pore volume: Static adsorption method was used. The sample was placed in a nitrogen environment and pretreated at 200℃ for 6 hours. Nitrogen was then introduced at -196℃, and its adsorption in the sample and pores was controlled. The specific surface area, pore size, and pore volume were calculated using adsorption isotherms.

[0061] 2. Determination of volatile components: The porous carbon material is heated to 300℃, causing the volatile components in the porous carbon material to escape. The escaped volatile components are introduced into the absorption device through airflow, and the content of volatile components is obtained by weighing the weight gain of the silica gel absorbent.

[0062] 3. Ash content determination: The porous carbon material was digested at 200℃ for 30 min using microwave heating technology. The ash content of the porous carbon material was calculated by measuring the mineral content in the decomposed solution.

[0063] 4. Determination of oxygen content: Fourier transform infrared spectroscopy was used for testing. The sample and KBr powder were mixed at a ratio of 3:100, and then pressed into a transparent sheet under a pressure of 10 MPa. The prepared sample was placed in the instrument to measure and record the infrared spectrum of the sample. The oxygen content was indirectly analyzed by analyzing the infrared spectrum.

[0064] Example 2

[0065] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous ethanol, and then add 148g of octamethylcyclotetrasiloxane dropwise while stirring for 30min to ensure that the octamethylcyclotetrasiloxane and resorcinol are evenly dispersed to obtain a mixture.

[0066] In the second step, 5 mL of triethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating octamethylcyclotetrasiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the organosilicon / phenolic resin composite.

[0067] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and octamethylcyclotetrasiloxane into amorphous carbon, while the silicon-oxygen bond (Si-OSi) skeleton in octamethylcyclotetrasiloxane breaks to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0068] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0069] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0070] The testing process is the same as in Example 1.

[0071] Example 3

[0072] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous acetone, and then add 148g of octamethylcyclotetrasiloxane dropwise while stirring for 30min to ensure that the octamethylcyclotetrasiloxane and resorcinol are evenly dispersed to obtain a mixture.

[0073] In the second step, 5 mL of triethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating octamethylcyclotetrasiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the organosilicon / phenolic resin composite.

[0074] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and octamethylcyclotetrasiloxane into amorphous carbon, while the silicon-oxygen bond (Si-O-Si) framework in octamethylcyclotetrasiloxane breaks to generate carbonization products of silicon oxides such as silicon dioxide and carbon-silicon oxide composites.

[0075] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0076] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0077] The testing process is the same as in Example 1.

[0078] Example 4

[0079] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous ethanol, and then add 185g of decamethylcyclopentasiloxane dropwise while stirring for 30min to ensure that the decamethylcyclopentasiloxane and resorcinol are evenly dispersed to obtain a mixture.

[0080] In the second step, 5 mL of triethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating decamethylcyclopentasiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the organosilicon / phenolic resin composite.

[0081] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and decamethylcyclopentasiloxane into amorphous carbon, while the silicon-oxygen bond (Si-O-Si) framework in decamethylcyclopentasiloxane breaks to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0082] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0083] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0084] The testing process is the same as in Example 1.

[0085] Example 5

[0086] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous ethanol, and then add 222g of dodecylcyclohexasiloxane dropwise while stirring for 30min to ensure that dodecylcyclohexasiloxane and resorcinol are evenly dispersed to obtain a mixture.

[0087] In the second step, 5 mL of triethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating dodecylcyclohexasiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the organosilicon / phenolic resin composite.

[0088] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and dodecylcyclohexasiloxane into amorphous carbon, while the silicon-oxygen bond (Si-O-Si) framework in dodecylcyclohexasiloxane breaks to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0089] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0090] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0091] The testing process is the same as in Example 1.

[0092] Example 6

[0093] The first step is to dissolve 150g of catechol in 500mL of anhydrous dimethylformamide, and then add 100g of hexamethylcyclotrisiloxane dropwise while stirring for 30min to ensure that the hexamethylcyclotrisiloxane and catechol are evenly dispersed to obtain a mixture.

[0094] In the second step, 4 mL of dimethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 122 g of acetaldehyde was added, and stirring continued at room temperature for 1 hour, allowing acetaldehyde and catechol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 40°C, and stirring continued for 16 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating hexamethylcyclotrisiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 8000 rpm for 5 minutes. This process was repeated four times. Finally, the mixture was dried in a vacuum drying oven at 50°C for 15 hours to obtain the organosilicon / phenolic resin composite.

[0095] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under an argon atmosphere and heating it to 700°C at a heating rate of 2°C / min for 3 hours to carbonize it. This process converts the organic groups in the phenolic resin and hexamethylcyclotrisiloxane into amorphous carbon, while the silicon-oxygen bond (Si-O-Si) framework in hexamethylcyclotrisiloxane breaks to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0096] The fourth step is to wash the carbonized product with 1 mol / L sodium hydroxide, centrifuge it at 8000 r / min for 3 min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 50°C for 3 hours.

[0097] The fifth step involves placing the dried carbonized product in a tube furnace under an argon atmosphere and passivating it at 800°C for 3 hours to further remove residual organic matter and obtain porous carbon material.

[0098] Example 7

[0099] The first step is to dissolve 50g of m-cresol in 500mL of anhydrous N-methylpyrrolidone, and then add 204g of decamethylcyclopentasiloxane dropwise while stirring for 30min to ensure that the decamethylcyclopentasiloxane and catechol are evenly dispersed to obtain a mixture.

[0100] In the second step, 6 mL of pyridine was added to the mixture to create a weakly alkaline environment. While stirring, 88 g of furfural was added, and stirring continued at room temperature for 3 hours, allowing furfural and m-cresol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 80°C, and stirring continued for 5 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating decamethylcyclopentasiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 10000 rpm for 2 minutes. This process was repeated 5 times. Finally, the mixture was dried in a vacuum drying oven at 70°C for 10 hours to obtain the organosilicon / phenolic resin composite.

[0101] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under an argon atmosphere and heating it to 900°C at a heating rate of 8°C / min for 1 hour to carbonize it. This process converts the organic groups in the phenolic resin and decamethylcyclopentasiloxane into amorphous carbon, while the silicon-oxygen bond (Si-OSi) skeleton in decamethylcyclopentasiloxane breaks to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0102] The fourth step is to wash the carbonized product with 1 mol / L sodium hydroxide, centrifuge it at 8000 r / min for 3 min, repeat this process 5 times, and then transfer it to a vacuum drying oven at 70℃ for 2 hours.

[0103] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 1000°C for 1 hour to further remove residual organic matter and obtain porous carbon material.

[0104] Example 8

[0105] The first step is to dissolve 100g of p-cresol in 500mL of anhydrous ethanol, and then add 163g of octamethylcyclotetrasiloxane dropwise while stirring for 30min to ensure that the octamethylcyclotetrasiloxane and p-cresol are evenly dispersed to obtain a mixture.

[0106] In the second step, 5.5 mL of methylethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 81 g of acetaldehyde was added, and stirring continued at room temperature for 2.5 hours, allowing acetaldehyde and p-cresol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 65°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating octamethylcyclotetrasiloxane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 8500 rpm for 3 minutes. This process was repeated four times. Finally, the mixture was dried in a vacuum drying oven at 65°C for 13 hours to obtain the organosilicon / phenolic resin composite.

[0107] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under an argon atmosphere and heating it to 750°C at a heating rate of 6°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and octamethylcyclotetrasiloxane into amorphous carbon, while the silicon-oxygen bond (Si-O-Si) framework in octamethylcyclotetrasiloxane breaks to generate carbonization products of silicon oxides such as silicon dioxide and carbon-silicon oxide composites.

[0108] The fourth step is to wash the carbonized product with 1 mol / L sodium hydroxide, centrifuge it at 9000 r / min for 2 min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 65℃ for 3 hours.

[0109] The fifth step involves placing the dried carbonized product in a tube furnace under an argon atmosphere and passivating it at 950°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0110] Comparative Example 1

[0111] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous ethanol.

[0112] In the second step, 5 mL of triethylamine was added to the above solution to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the phenolic resin composite.

[0113] The third step involves placing the phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it, thereby converting the phenolic resin into amorphous carbon.

[0114] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0115] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0116] Comparative Example 2

[0117] The first step is to dissolve 110g of resorcinol in 500mL of anhydrous ethanol, and then add 111g of dimethyldimethoxysilane dropwise while stirring for 30min to ensure that the dimethyldimethoxysilane and resorcinol are evenly dispersed to obtain a mixture.

[0118] In the second step, 5 mL of triethylamine was added to the mixture to create a weakly alkaline environment. While stirring, 90 g of formaldehyde was added, and stirring continued at room temperature for 2 hours, allowing formaldehyde and resorcinol to undergo an addition reaction to form a hemiacetal. Then, the solution temperature was raised to 60°C, and stirring continued for 10 hours, allowing the hemiacetal to undergo a condensation reaction while simultaneously encapsulating dimethyldimethoxysilane. After cooling to room temperature, deionized water was added, and the mixture was centrifuged at 9000 rpm for 3 minutes. This process was repeated three times. Finally, the mixture was dried in a vacuum drying oven at 60°C for 12 hours to obtain the organosilicon / phenolic resin composite.

[0119] The third step involves placing the organosilicon / phenolic resin composite in a tube furnace under a nitrogen atmosphere and heating it to 800°C at a heating rate of 3°C / min for 2 hours to carbonize it. This process converts the organic groups in the phenolic resin and dimethyldimethoxysilane into amorphous carbon, while the silicon-oxygen bond (Si-OSi) framework in dimethyldimethoxysilane breaks down to generate carbonization products such as silicon dioxide and carbon-silicon oxide composites.

[0120] The fourth step is to wash the carbonized product with 10wt% hydrofluoric acid, centrifuge it at 9000r / min for 3min, repeat this process 3 times, and then transfer it to a vacuum drying oven at 60℃ for 2 hours.

[0121] The fifth step involves placing the dried carbonized product in a tube furnace under a nitrogen atmosphere and passivating it at 900°C for 2 hours to further remove residual organic matter and obtain porous carbon material.

[0122] Table 1 summarizes the performance test data of the porous carbon materials in Examples 1-5 and Comparative Examples 1-2 of the present invention.

[0123]

[0124] As shown in Table 1, compared to Comparative Examples 1-2, the porous carbon materials prepared by adding cyclic organosiloxanes of different molecular sizes as templates in Examples 1-5 of this invention have larger specific surface areas and pore volumes, and the pore size is adjustable, realizing the controllable preparation of micropores and mesopores in porous carbon materials. In contrast, Comparative Example 1, without using a silicon source, only achieved pore structure formation through the evaporation of water vapor or gas escape from oxygen-containing functional groups during the carbonization process of phenolic resin. Comparative Example 2 used an easily hydrolyzed silicon source, which tends to aggregate during hydrolysis, resulting in an uneven pore structure. Therefore, the porous carbon materials prepared by both examples have very small specific surface areas, pore volumes, and pore sizes.

[0125] As shown in Figure 2, this is a SEM image of the porous carbon material provided in Embodiment 4 of the present invention. Figure 2 It can be seen that the porous carbon material has a spherical structure of about 10 μm and the particle size is relatively uniform. The SEM image does not show large pores on the carbon surface, indicating that the porous carbon material has good compactness.

[0126] contrast Figure 3 and 4 It can be seen that the porous carbon material provided in Example 2 of the present invention has a more uniform pore size distribution because the present invention uses octamethylcyclotetrasiloxane, which is not easily hydrolyzed. In contrast, Comparative Example 2 uses dimethyldimethoxysilane, which is easily hydrolyzed. Even in an anhydrous environment, trace amounts of moisture in the air can cause it to hydrolyze, resulting in a non-uniform pore size distribution in the porous carbon material prepared therefrom.

[0127] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing porous carbon materials, characterized in that, The preparation method includes: The phenol source is dissolved in an anhydrous polar solution, and a cyclic organosiloxane of a predetermined size is added and stirred to make the phenol source and the cyclic organosiloxane mix evenly, thus obtaining the first mixture. An organic base is added to the first mixture to make it weakly alkaline. Then, an aldehyde source is added and stirred to allow the hydroxyl group of the phenol source to undergo an addition reaction with the carbonyl carbon of the aldehyde source to generate a hemiacetal. The hemiacetal is then heat-treated to cause a condensation reaction. After washing and drying, an organosilicon / phenolic resin composite is obtained. The organosilicon / phenolic resin composite was carbonized under an inert atmosphere to generate carbonized products. The carbonized product is washed to remove the silicon oxide that forms a porous structure, and then passivated to obtain a porous carbon material.

2. The preparation method according to claim 1, characterized in that, The phenol source includes one or more of resorcinol, catechol, m-cresol, and p-cresol; the anhydrous polar solvent includes one or more of anhydrous ethanol, anhydrous acetone, anhydrous dimethylformamide, and anhydrous N-methylpyrrolidone; the cyclic organosiloxane includes one or more of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane.

3. The preparation method according to claim 1, characterized in that, The organic base includes one or more of triethylamine, dimethylamine, pyridine, and methylethylamine; the aldehyde source includes one or more of formaldehyde, acetaldehyde, and furfural.

4. The preparation method according to claim 1, characterized in that, The heat treatment conditions are: temperature 40℃-80℃, time 5 hours-16 hours.

5. The preparation method according to claim 1, characterized in that, The carbonization conditions are: temperature 700℃-900℃, time 1 hour-3 hours.

6. The preparation method according to claim 1, characterized in that, The washing solution includes either hydrofluoric acid or sodium hydroxide.

7. The preparation method according to claim 1, characterized in that, The passivation treatment conditions are: temperature 800℃-1000℃, time 1 hour-3 hours.

8. A porous carbon material, characterized in that, The porous carbon material is prepared by any one of the preparation methods described in claims 1-7.

9. A negative electrode sheet, characterized in that, The negative electrode sheet comprises the porous carbon material as described in claim 8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the negative electrode sheet as described in claim 9.

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