Compact porous carbon material as well as preparation method and application thereof

Abstract

The invention relates to a compact porous carbon material as well as a preparation method and application thereof. The preparation method comprises the following steps: adding a surfactant, a carbon source material and a template raw material into a solvent, uniformly mixing, and carrying out spray drying treatment to obtain a mixed precursor; carrying out low-temperature pre-carbonization treatment on the mixed precursor in an inert atmosphere at 300-600 DEG C to obtain a pre-carbonized material; carrying out crushing and grading treatment on the pre-carbonized material; carrying out etching treatment on the crushed and graded material by using an etching agent, cleaning and drying to obtain a porous carbon precursor; and carrying out secondary carbonization treatment on the porous carbon precursor at 700-1100 DEG C, cooling and discharging to obtain the compact porous carbon material. According to the preparation method, a surfactant is introduced into a precursor, so that the distribution of a carbon source in a template material is optimized; through three steps of processes of low-temperature pre-carbonization, etching and high-temperature carbonization and process parameter control, densification of a carbon layer and regulation and control of a pore structure are realized step by step, cracks are prevented from being generated in particles, and the mechanical strength and the structural stability of the material are improved.

Description

Technical Field

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

[0002] In modern materials science, porous carbon materials are widely used in catalysis, adsorption, energy storage, and sensors due to their excellent electrochemical properties, good electrical conductivity, high specific surface area, and porous structure, especially in lithium-ion battery electrode materials, supercapacitors, and electrocatalyst support materials. Traditional methods for preparing porous carbon materials typically involve high-temperature pyrolysis, a process that easily leads to internal cracking, affecting their mechanical strength and structural stability. Therefore, effectively preventing crack formation has become a significant challenge in the current field of porous carbon material preparation.

[0003] Several methods have been proposed in the prior art to address this problem. For example, Chinese patent document CN114933294A discloses a "high volumetric density multilayer dense porous carbon nanosheet and its preparation method." This method prepares dense porous carbon nanosheets with high specific surface area and excellent electrochemical performance by dispersing two-dimensional layered bimetallic hydroxide (LDH), mixing it with a carbon precursor and activator, calcining, and post-treatment. However, this method is still prone to cracking during high-temperature processing, and the preparation process is relatively complex and costly.

[0004] Among methods for preparing porous carbon materials, the hard template method is one of the effective methods for preparing dense porous carbon materials due to its ability to precisely control pore size and pore structure. The hard template method typically uses inorganic materials (such as silica, alumina, etc.) as templates to form carbon materials on their surface or within their pores. However, traditional hard template methods have some drawbacks in practical applications, such as the difficulty in removing the template material, and the carbon material's pore structure being neither uniform nor dense enough, leading to poor stability and repeatability of material properties. Furthermore, the problem of internal cracks caused by the pyrolysis process has not been substantially resolved. Summary of the Invention

[0005] The purpose of this invention is to address the deficiencies of existing technologies by providing a dense porous carbon material, its preparation method, and its application. By adding surfactants, carbon sources, and hard templates, combined with optimized low-temperature pre-carbonization, etching processes, and secondary carbonization treatment, the generation of internal cracks in the material during pyrolysis can be significantly reduced, thereby improving the material's mesoporosity and pressure resistance.

[0006] To achieve the above objectives, the present invention provides a method for preparing a dense porous carbon material, comprising:

[0007] Surfactants, carbon source materials and template raw materials are added to a solvent, mixed evenly and then spray-dried to obtain a mixed precursor.

[0008] The mixed precursor is subjected to low-temperature pre-carbonization treatment at 300-600℃ in an inert atmosphere to obtain a pre-carbonized material.

[0009] The pre-carbonized material is then pulverized and graded.

[0010] The pulverized and classified material is etched with an etchant, and after cleaning and drying, a porous carbon precursor is obtained.

[0011] In an inert atmosphere, the porous carbon precursor is subjected to a secondary carbonization treatment at 700-1100℃, and after cooling and discharge, the dense porous carbon material is obtained.

[0012] Preferably, the surfactant comprises one or more of the following: polyoxyethylene polyoxypropylene ether (Pluronic F127), hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and polyethylene glycol (PEG);

[0013] The carbon source materials include one or more of the following: glucose, corn starch, glycerol, fructose, maltose, sucrose, phenolic resin, polyvinyl alcohol (PVA), polyethylene terephthalate (PET), and asphalt;

[0014] The template material includes one or more of the following: magnesium citrate, magnesium gluconate, magnesium acetate, magnesium glycine, polymethylphenylsiloxane (PMPS), and polyphenylsilsesquioxane (PPSSO).

[0015] The solvent includes water or ethanol.

[0016] Preferably, the mass ratio of the surfactant, carbon source material, and template raw material is 1:2-5:1-10;

[0017] The mixing specifically includes stirring; the stirring speed is 400-1000 rpm, the stirring temperature is 25-80℃, and the stirring time is 12-24h;

[0018] In the spray drying process, the inlet temperature is 150-180℃, the outlet temperature is 70-90℃, and the atomizer frequency is 220Hz.

[0019] Preferably, the equipment for the low-temperature pre-carbonization treatment includes one or more of the following: tube furnace, atmosphere furnace, rotary furnace, and box furnace;

[0020] The low-temperature pre-carbonization treatment takes 1-4 hours and the heating rate is 1-5℃ / min.

[0021] The inert atmosphere is an argon atmosphere or a nitrogen atmosphere.

[0022] Preferably, the particle size parameters of the material obtained after the crushing and grading process are: D00≥1μm, D10≥3μm, D50≥7μm-15μm, D90≤50μm, and D99≤90μm.

[0023] Preferably, the etching agent comprises one or more of HCl, H2SO4, HNO3, HF, KOH and NaOH with a solution concentration of 0.1-5 mol / L;

[0024] The etching process takes 2-8 hours and is carried out at a temperature of 25-80°C.

[0025] The cleaning is a water wash;

[0026] The drying equipment includes one or more of the following: a forced-air drying oven, a vacuum drying oven, a tunnel drying oven, and a rotary dryer;

[0027] The drying temperature is 70-110℃, and the time is 8-20h.

[0028] Preferably, the secondary carbonization process takes 1-3 hours and the heating rate is 1-5℃ / min.

[0029] Secondly, embodiments of the present invention provide a dense porous carbon material prepared by the preparation method described in the first aspect above.

[0030] Preferably, the dense porous carbon material has a mesoporous ratio of ≥40% and a compressive strength of ≥5MPa.

[0031] Thirdly, embodiments of the present invention provide an application of the dense porous carbon material described in the second aspect above, wherein the dense porous carbon material is used as an electrode material for lithium-ion batteries, an electrode material for supercapacitors, or a catalyst support for fuel cells.

[0032] The method for preparing dense porous carbon materials provided in this invention optimizes the distribution of carbon source in the template material by introducing a surfactant into the precursor, thus protecting the integrity of the carbon particle surface. Through a three-step process of low-temperature pre-carbonization, etching, and high-temperature carbonization, and by controlling the process parameters, the densification of the carbon layer and the regulation of the pore structure are gradually achieved, preventing internal cracking of the particles and improving the mechanical strength and structural stability of the material. The preparation method proposed in this invention is simple, environmentally friendly, and widely applicable. The dense porous carbon material prepared using this method exhibits smooth and dense characteristics on both the particle surface and interior, with a mesoporosity greater than or equal to 40% and a pressure resistance greater than or equal to 5 MPa. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation method of dense porous carbon materials provided in this embodiment of the invention.

[0034] Figure 2 This is a scanning electron microscope (SEM) image of the carbon profile (CP) of the electrode after secondary carbonization treatment of the dense porous carbon material prepared in Example 1 of the present invention.

[0035] Figure 3 This is a SEM image of the dense porous carbon material prepared in Example 1 of the present invention;

[0036] Figure 4 This is a pore size distribution diagram of the dense porous carbon material prepared in Example 1 of the present invention;

[0037] Figure 5 This is a SEM image of the porous carbon material electrode CP prepared in Comparative Example 1 of this invention;

[0038] Figure 6 This is a SEM image of the porous carbon material prepared in Comparative Example 2 of this invention. Detailed Implementation

[0039] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0040] This invention provides a dense porous carbon material, its preparation method, and its application.

[0041] Figure 1 This is a flowchart of the preparation method of dense porous carbon material provided in the embodiments of the present invention. The following is in conjunction with... Figure 1 First, the preparation method provided by the present invention will be described.

[0042] The preparation method of the present invention includes:

[0043] Step 110: Add surfactant, carbon source material and template raw material to solvent, mix evenly and then spray dry to obtain mixed precursor;

[0044] Surfactants include one or more of the following: polyoxyethylene polyoxypropylene ether (Pluronic F127), hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and polyethylene glycol (PEG);

[0045] Carbon source materials include one or more of the following: glucose, corn starch, glycerol, fructose, maltose, sucrose, phenolic resin, polyvinyl alcohol (PVA), polyethylene terephthalate (PET), and asphalt;

[0046] Template materials include one or more of the following: magnesium citrate, magnesium gluconate, magnesium acetate, magnesium glycine, polymethylphenylsiloxane (PMPS), and polyphenylsilsesquioxane (PPSSO);

[0047] Solvents include water or ethanol.

[0048] The mass ratio of surfactant, carbon source material, and template raw material is 1:2-5:1-10; the solid-liquid mass ratio in the mixed solution is 10%-50%.

[0049] In this step, mixing specifically includes stirring; the stirring speed is 400-1000 rpm, the stirring temperature is 25-80℃, and the stirring time is 12-24h.

[0050] During spray drying, the inlet temperature is 150-180℃, the outlet temperature is 70-90℃, and the atomizer frequency is 220Hz.

[0051] By introducing surfactants during the mixing and spray drying process, the distribution of carbon source in the template material can be optimized, making the carbon material more uniform and dense during formation, while protecting the integrity of the carbon particle surface.

[0052] Step 120: In an inert atmosphere, the mixed precursor is subjected to low-temperature pre-carbonization treatment at 300-600℃ to obtain pre-carbonized material.

[0053] The equipment for low-temperature pre-carbonization treatment includes one or more of the following: tubular furnace, atmosphere furnace, rotary furnace, and box furnace.

[0054] The inert atmosphere is either argon or nitrogen.

[0055] The low-temperature pre-carbonization treatment takes 1-4 hours and the heating rate is 1-5℃ / min.

[0056] By treating the carbon precursor at low temperatures, some carbides are fixed within the pores of the template, forming a preliminary carbon skeleton. The low temperature (300-600℃) during the pre-carbonization process allows the pore structure of the carbon material to take initial shape, while controlling the heating rate avoids cracking caused by drastic volume changes.

[0057] Step 130: The pre-carbonized material is crushed and graded.

[0058] The crushing and grading processes can be performed using commonly used equipment in the industry. For example, ball mills and air classifiers can be used to crush and grade the pre-carbonized materials. After crushing and grading, the particle size parameters of the resulting materials are: D00≥1μm, D10≥3μm, D50≥7μm-15μm, D90≤50μm, and D99≤90μm.

[0059] Step 140: The pulverized and classified material is etched with an etchant, and after cleaning and drying, a porous carbon precursor is obtained.

[0060] Specifically, the etching agent includes one or more of HCl, H2SO4, HNO3, HF, KOH and NaOH with a solution concentration of 0.1-5 mol / L; the etching time is 2-8 h, and the etching temperature is 25-80 °C; the mass ratio of the etching solution to the pulverized and graded material is 2:1-10:1, more preferably 3:1-5:1.

[0061] After etching, the sample is washed with water to remove any residual acid or alkali, and then dried.

[0062] The drying equipment includes one or more of the following: a blower oven, a vacuum oven, a tunnel oven, and a rotary dryer; preferably, the drying temperature is 70-110℃ and the time is 8-20h.

[0063] Etching with an etchant removes template material and further enlarges and homogenizes the pore structure. Furthermore, etching can remove inorganic impurities that may remain on the material surface, improving pore size distribution and increasing specific surface area.

[0064] Step 150: In an inert atmosphere, the porous carbon precursor is subjected to a secondary carbonization treatment at 700-1100℃, and after cooling and discharge, a dense porous carbon material is obtained.

[0065] Specifically, the secondary carbonization process takes 1-3 hours, with a heating rate of 1-5℃ / min.

[0066] Further carbonization at high temperatures (700-1100℃) completely converts residual organic components into carbon materials, while simultaneously increasing the material's density. During this process, controlling the temperature and heating rate increases the crystallinity of the carbon materials, thereby improving their strength and compressive strength, and also stabilizing the pore structure, ensuring a high mesoporosity in the final material.

[0067] The dense porous carbon material prepared by the above method has a mesoporosity of ≥40% and a compressive strength of ≥5MPa. It can be used as an electrode material for lithium-ion batteries, an electrode material for supercapacitors, or a catalyst support for fuel cells.

[0068] The method for preparing dense porous carbon materials provided in this invention optimizes the distribution of carbon source in template material by introducing surfactants into the precursor, thus protecting the integrity of the carbon particle surface. Through three-step processes of low-temperature pre-carbonization, etching, and high-temperature carbonization, and by controlling process parameters, the densification of the carbon layer and the regulation of the pore structure are gradually achieved, avoiding cracks inside the particles and improving the mechanical strength and structural stability of the material.

[0069] The preparation method proposed in this invention is simple, environmentally friendly, and widely applicable.

[0070] 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 merely some embodiments of this invention, and not all embodiments. 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.

[0071] Example 1

[0072] This embodiment provides a method for preparing dense porous carbon materials, the specific process of which is as follows.

[0073] Step 1: Add 0.5kg F127, 1kg corn starch and 1kg magnesium citrate to 10kg water, and stir rapidly at 400rpm in a 60℃ heating environment for 12 hours; then pass the well-stirred solution into an open spray tower for spray drying. The spray drying program is set as follows: air inlet 180℃, air outlet 70℃, atomizer frequency 220Hz.

[0074] Step 2: Pre-carbonize the sprayed powder using a rotary kiln: Under a nitrogen atmosphere, slowly raise the equipment temperature to 500°C at a heating rate of 1°C / min, hold at this temperature for 4 hours, and then cool and discharge the material.

[0075] Step 3: Crush and classify the pre-carbonized semi-finished material to obtain particle sizes of: D00 = 1.2 μm, D10 = 5.7 μm, D50 = 9.1 μm, D90 = 47 μm, D99 = 70 μm.

[0076] Step 4: Use a 1 mol / L HCl solution to etch the pulverized and graded material. The mass ratio of etching solution to material is 3:1. After soaking the material at room temperature for 6 hours, wash and discharge it, then place it in a 95℃ oven to dry for 10 hours.

[0077] Step 5: Perform a secondary carbonization treatment on the etched material: Under a nitrogen atmosphere, gradually increase the equipment temperature to 700℃ at a rate of 5℃ / min, and hold at this temperature for 2 hours. After cooling, a dense porous carbon material is finally obtained.

[0078] The scanning electron microscope (SEM) images of the carbon profile (CP) of the dense porous carbon material provided in this embodiment, the electrode SEM images, and the pore size distribution diagrams are shown below. Figure 2 , 3 As shown in Figure 4.

[0079] The prepared materials were subjected to physicochemical property tests.

[0080] Specific surface area and pore size were tested according to the national standard GB / T19587-2017. Specifically, nitrogen adsorption-desorption tests were conducted using an ASAP 2460 instrument from Micron Instruments at liquid nitrogen temperature (77.3 K) to measure the specific surface area and pore structure of the material, including parameters such as pore volume and pore size distribution. The obtained specific surface area of ​​the material was 1345 m². 2 / g, with a mesoporous rate of 82%. More specific test results are recorded in Table 1.

[0081] The compressive strength test method is as follows: First, the particle sample to be tested is placed in the fixture of a micro compression testing machine and fixed; the appropriate compressive strength test mode is selected, and appropriate test parameters are set; by recording the strength data when the particles break, the compressive strength of the material can be evaluated. The test results show that the compressive strength of the dense porous carbon material prepared in this embodiment reaches 17 MPa.

[0082] Example 2

[0083] This embodiment provides a method for preparing dense porous carbon materials, the specific process of which is as follows.

[0084] Step 1: Add 0.5 kg F127, 1 kg corn starch, and 1 kg magnesium gluconate to 10 kg of water. Stir rapidly at 400 rpm in a 60°C heating environment for 12 hours. Then, pass the well-stirred solution into an open spray tower for spray drying. The spray drying program is set as follows: inlet temperature 180°C, outlet temperature 70°C, and atomizer frequency 220 Hz.

[0085] Step 2: Pre-carbonize the sprayed powder using a rotary kiln: Under a nitrogen atmosphere, slowly raise the equipment temperature to 450°C at a heating rate of 1°C / min, hold at this temperature for 4 hours, and then cool and discharge the material.

[0086] Step 3: Crush and classify the pre-carbonized semi-finished material to obtain particle sizes of: D00 = 1.1 μm, D10 = 5.3 μm, D50 = 8.7 μm, D90 = 44 μm, D99 = 87 μm.

[0087] Step 4: Use a 1 mol / L HCl solution to etch the pulverized and graded material. The mass ratio of etching solution to material is 3:1. After soaking the material at room temperature for 6 hours, wash and discharge it, then place it in a 95℃ oven to dry for 10 hours.

[0088] Step 5: Perform a secondary carbonization treatment on the etched material: Under a nitrogen atmosphere, gradually increase the equipment temperature to 700℃ at a rate of 3℃ / min, and hold at this temperature for 2 hours. After cooling, a dense porous carbon material is finally obtained.

[0089] Using the same testing method as in Example 1, the specific surface area of ​​the dense porous carbon material provided in this example is 1578 m². 2 / g, with a mesoporous content of 76%, and a pressure resistance of 23MPa.

[0090] Example 3

[0091] This embodiment provides a method for preparing dense porous carbon materials, the specific process of which is as follows.

[0092] Step 1: Add 0.4 kg SDS, 1 kg phenolic resin, and 1 kg PMPS to 10 kg ethanol. Stir rapidly at 400 rpm in an 80°C heating environment for 12 hours. Then, pass the well-stirred solution into a closed spray tower for spray drying. The spray drying program is set as follows: inlet temperature 180°C, outlet temperature 90°C, and atomizer frequency 220 Hz.

[0093] Step 2: Pre-carbonize the sprayed powder using a rotary kiln: Under a nitrogen atmosphere, slowly raise the equipment temperature to 600°C at a heating rate of 1°C / min, hold at this temperature for 4 hours, and then cool and discharge the material.

[0094] Step 3: Crush and classify the pre-carbonized semi-finished material to obtain particle sizes of: D00 = 1.5 μm, D10 = 4.7 μm, D50 = 9.7 μm, D90 = 44 μm, D99 = 88 μm.

[0095] Step 4: Use a 1 mol / L KOH solution to etch the pulverized and graded material. The mass ratio of KOH etching solution to material is 4:1. After soaking the material at 80℃ for 8 hours, wash and drain it, then place it in a 95℃ oven to dry for 10 hours.

[0096] Step 5: Perform a secondary carbonization treatment on the etched material: Under a nitrogen atmosphere, gradually raise the equipment temperature to 1100℃ at a rate of 5℃ / min, and hold at this temperature for 2 hours. After cooling, a dense porous carbon material is finally obtained.

[0097] Using the same testing method as in Example 1, the specific surface area of ​​the dense porous carbon material provided in this example is 756 m². 2 / g, with a mesoporous content of 44%, and a pressure resistance of 21MPa.

[0098] Example 4

[0099] This embodiment provides a method for preparing dense porous carbon materials, the specific process of which is as follows.

[0100] Step 1: Add 0.4 kg SDS, 1 kg phenolic resin, and 1 kg PPSSO to 10 kg ethanol. Stir rapidly at 400 rpm in an 80°C heating environment for 12 hours. Then, pass the well-stirred solution into a closed spray tower for spray drying. The spray drying program is set as follows: inlet temperature 180°C, outlet temperature 90°C, and atomizer frequency 220 Hz.

[0101] Step 2: Pre-carbonize the sprayed powder using a rotary kiln: Under a nitrogen atmosphere, slowly raise the equipment temperature to 600°C at a heating rate of 1°C / min, hold at this temperature for 4 hours, and then cool and discharge the material.

[0102] Step 3: Crush and classify the pre-carbonized semi-finished material to obtain particle sizes of: D00 = 1.1 μm, D10 = 3.5 μm, D50 = 7.7 μm, D90 = 41 μm, D99 = 81 μm.

[0103] Step 4: Use a 1 mol / L KOH solution to etch the pulverized and graded material. The mass ratio of etching solution to material is 4:1. After soaking the material at 80℃ for 8 hours, wash and drain it, then place it in a 95℃ oven to dry for 10 hours.

[0104] Step 5: Perform a secondary carbonization treatment on the etched material: Under a nitrogen atmosphere, gradually raise the equipment temperature to 1100℃ at a rate of 5℃ / min, and hold at this temperature for 2 hours. After cooling, a dense porous carbon material is finally obtained.

[0105] Using the same testing method as in Example 1, the specific surface area of ​​the dense porous carbon material provided in this example is 821 m². 2 / g, with a mesoporous rate of 51% and a pressure resistance of 32MPa.

[0106] Comparative Example 1

[0107] Step 1: Add 0.5 kg F127, 1 kg corn starch, and 1 kg magnesium citrate to 10 kg of water. Stir rapidly at 400 rpm in a 60°C heating environment for 12 hours. Then, pass the well-stirred solution into an open spray tower for spray drying. The spray drying program is set as follows: inlet temperature 180°C, outlet temperature 70°C, and atomizer frequency 220 Hz.

[0108] Step 2: Pre-carbonize the sprayed powder using a rotary kiln: Under a nitrogen atmosphere, raise the equipment temperature to 700°C at a heating rate of 5°C / min, hold at this temperature for 4 hours, and then cool and discharge the material.

[0109] Step 3: Crush and classify the pre-carbonized semi-finished material to obtain particle sizes of: D00 = 1.2 μm, D10 = 5.7 μm, D50 = 9.2 μm, D90 = 47 μm, and D99 = 70 μm.

[0110] Step 4: Etch the pulverized and graded material using a 1 mol / L HCl solution, with a mass ratio of etching solution to material of 3:1. After soaking the material at room temperature for 6 hours, wash and discharge it, then place it in a 95℃ oven to dry for 10 hours, finally obtaining the material of Comparative Example 1.

[0111] The electrode CP diagram of the carbon material provided in this comparative example is as follows: Figure 5 As shown, cracks and large pores can be seen inside the material.

[0112] Using the same testing method as in Example 1, the specific surface area of ​​the material prepared in this comparative example was measured to be 744 m². 2 / g, with a mesoporous content of 34% and a pressure resistance of 1.7MPa.

[0113] Comparative Example 2

[0114] Step 1: Add 1 kg of corn starch and 1 kg of magnesium citrate to 10 kg of water. Stir rapidly at 400 rpm in a 60°C heating environment for 12 hours. Then, pass the well-stirred solution into an open spray tower for spray drying. The spray drying program is set as follows: inlet temperature 180°C, outlet temperature 70°C, and atomizer frequency 220 Hz.

[0115] Step 2: Pre-carbonize the sprayed powder using a rotary kiln: Under a nitrogen atmosphere, slowly raise the equipment temperature to 500°C at a heating rate of 1°C / min, hold at this temperature for 4 hours, and then cool and discharge the material.

[0116] Step 3: Crush and classify the pre-carbonized semi-finished material to obtain particle sizes of: D00 = 1.3 μm, D10 = 5.8 μm, D50 = 9.3 μm, D90 = 48 μm, D99 = 72 μm.

[0117] Step 4: Use a 1 mol / L HCl solution to etch the pulverized and graded material. The mass ratio of etching solution to material is 3:1. After soaking the material at room temperature for 6 hours, wash and discharge it, then place it in a 95℃ oven to dry for 10 hours.

[0118] Step 5: Perform a secondary carbonization treatment on the etched material: Under a nitrogen atmosphere, gradually raise the equipment temperature to 700℃ at a rate of 5℃ / min, and hold at this temperature for 2 hours. After cooling, the material of Comparative Example 2 is finally obtained.

[0119] The SEM image of the carbon material provided in this comparative example is as follows: Figure 6 As shown, large cracks appear on the exterior of the material.

[0120] Using the same testing method as in Example 1, the specific surface area of ​​the material prepared in this comparative example was measured to be 841 m². 2 / g, with a mesoporous content of 30% and a pressure resistance of 1.3MPa.

[0121] The specific test results of the physicochemical properties (including specific surface area, pore structure and pressure resistance tests) of the materials prepared in Examples 1-4 and Comparative Examples 1-2 are summarized in Table 1.

[0122] Table 1 summarizes the physicochemical parameters of the materials prepared in Examples 1-4 and Comparative Examples 1-2:

[0123]

[0124] Table 1

[0125] As shown in Table 1, the dense porous carbon materials prepared in Examples 1-4 exhibit higher compaction density and compressive strength, as well as lower ash content, compared to the carbon materials in Comparative Examples 1-2. This indicates that the porous carbon materials prepared in Examples 1-4 possess high battery capacity, high compressive strength, and high purity. This is because during the slow pyrolysis of the raw materials at high temperatures, the gasification rate of internal volatile substances is slow and stable, resulting in more uniform internal pores and ultimately yielding a dense porous carbon material. By adding a surfactant, the surface of the raw materials is coated after mixing, ensuring the stability of the material surface and preventing cracking during pyrolysis. Furthermore, through the three-step process of low-temperature pre-carbonization, etching, and high-temperature carbonization, and the control of process parameters, the densification of the carbon layer and the regulation of the pore structure are gradually achieved, avoiding internal cracks in the particles and improving the mechanical strength and structural stability of the material.

[0126] Using the dense porous carbon materials prepared in Examples 1-4 and the carbon materials in Comparative Examples 1-2, nano-silicon particles were deposited in the pores of the porous carbon materials using the same silicon deposition method to prepare six groups of silicon-carbon composite materials. Each group of silicon-carbon composite materials was then used to prepare negative electrode sheets. The specific process is as follows:

[0127] Negative electrode preparation: Silicon-carbon composite material, Super P conductive agent, sodium carboxymethyl cellulose, and styrene-butadiene rubber were mixed in a mass ratio of 16:2:1:1 to prepare an aqueous negative electrode slurry, with the solid content of the slurry controlled at approximately 45 wt%. After ensuring uniform mixing using a homogenizer, the slurry was coated onto copper foil with a coating thickness of 70 μm. Subsequently, it was dried at 80℃, rolled, cut, and vacuum dried at 110℃ for 12 hours to obtain the final negative electrode.

[0128] Assemble the half-cell: Using the negative electrode sheet prepared above as the working electrode, the lithium metal sheet as the counter electrode and reference electrode, and with the CR2025 matching battery case, Celgard2500 separator and 1 mol / L LiPF6 / ethylene carbonate + dimethyl carbonate (volume ratio 1:1) electrolyte (with 5.0 vol% fluorocarbonate and 1.0 vol% ethylene carbonate added), the half-cell was assembled in a glove box.

[0129] The assembled half-cells were tested: The half-cells assembled in each embodiment and comparative example were simultaneously subjected to constant current cyclic charge-discharge tests on the Newway testing system. The test voltage range was 0.01–2V, and the tests were conducted at room temperature. The first cycle consisted of discharging to 0.5V at 0.1C (1C = 2000mAh / g), then discharging to 0.1V at 0.05C, then discharging to 0.01V at 0.02C, followed by a 10-minute rest period; then charging to 1.5V at 0.1C, followed by a 10-minute rest period. The charge and discharge capacities after the first cycle were recorded, and the coulombic efficiency of the first cycle was calculated. The cells were cycled 300 times according to the above test method, and the capacity retention rate after 300 cycles was calculated. The test results are shown in Table 2 below.

[0130]

[0131]

[0132] Table 2

[0133] As shown in Table 2, the silicon-carbon composite batteries assembled using the dense porous carbon materials of Examples 1-4 exhibit better first-cycle coulombic efficiency and capacity retention after 300 cycles compared to the silicon-carbon composite batteries assembled in Comparative Examples 1-2. This is because the porous carbon materials of Examples 1-4 possess high density, high voltage resistance, and high mesoporosity. This high density allows the material to better maintain structural integrity during charge and discharge, reducing capacity loss due to structural collapse. The high voltage resistance ensures stable performance under high-pressure environments, which is crucial for improving the long-term cycle stability of the battery. Furthermore, the high mesoporosity facilitates electrolyte permeation and rapid ion transport, thereby improving the battery's conductivity and rate performance.

[0134] Therefore, when the dense porous carbon material of this invention is applied to energy storage devices, its high density and high mesoporosity can effectively promote the deposition and dispersion of silicon in the mesopores of the porous carbon material during the preparation of silicon-carbon anode materials for lithium batteries, significantly improving the effective utilization rate of Si. This characteristic not only enhances the specific capacity of lithium batteries but also improves their cycle performance.

[0135] 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 a dense porous carbon material, characterized in that, The preparation method includes: Surfactants, carbon source materials and template raw materials are added to a solvent, mixed evenly and then spray-dried to obtain a mixed precursor. The mixed precursor is subjected to low-temperature pre-carbonization treatment at 300-600℃ in an inert atmosphere to obtain a pre-carbonized material. The pre-carbonized material is then pulverized and graded. The pulverized and classified material is etched with an etchant, and after cleaning and drying, a porous carbon precursor is obtained. In an inert atmosphere, the porous carbon precursor is subjected to a secondary carbonization treatment at 700-1100℃, and after cooling and discharge, the dense porous carbon material is obtained.

2. The preparation method according to claim 1, characterized in that, The surfactant includes one or more of the following: polyoxyethylene polyoxypropylene ether Pluronic F127, hexadecyltrimethylammonium bromide CTAB, sodium dodecyl sulfate SDS, and polyethylene glycol PEG. The carbon source material includes one or more of the following: glucose, corn starch, glycerol, fructose, maltose, sucrose, phenolic resin, polyvinyl alcohol (PVA), polyethylene terephthalate (PET), and asphalt. The template material includes one or more of the following: magnesium citrate, magnesium gluconate, magnesium acetate, magnesium glycine, polymethylphenylsiloxane PMPS, and polyphenylsilsesquioxane PPSSO. The solvent includes water or ethanol.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the surfactant, carbon source material, and template raw material is 1:2-5:1-10; The mixing specifically includes stirring; the stirring speed is 400-1000 rpm, the stirring temperature is 25-80℃, and the stirring time is 12-24h; In the spray drying process, the inlet temperature is 150-180℃, the outlet temperature is 70-90℃, and the atomizer frequency is 220Hz.

4. The preparation method according to claim 1, characterized in that, The equipment for the low-temperature pre-carbonization treatment includes one or more of the following: tube furnace, atmosphere furnace, rotary furnace, and box furnace; The low-temperature pre-carbonization treatment takes 1-4 hours and the heating rate is 1-5℃ / min. The inert atmosphere is an argon atmosphere or a nitrogen atmosphere.

5. The preparation method according to claim 1, characterized in that, After the crushing and grading process, the particle size parameters of the resulting material are: D00≥1μm, D10≥3μm, D50≥7μm-15μm, D90≤50μm, D99≤90μm.

6. The preparation method according to claim 1, characterized in that, The etching agent includes one or more of HCl, H2SO4, HNO3, HF, KOH and NaOH with a solution concentration of 0.1-5 mol / L; The etching process takes 2-8 hours and is carried out at a temperature of 25-80°C. The cleaning is a water wash; The drying equipment includes one or more of the following: a forced-air drying oven, a vacuum drying oven, a tunnel drying oven, and a rotary dryer; The drying temperature is 70-110℃, and the time is 8-20h.

7. The preparation method according to claim 1, characterized in that, The secondary carbonization process takes 1-3 hours and the heating rate is 1-5℃ / min.

8. A dense porous carbon material prepared by any one of the preparation methods described in claims 1-7.

9. The dense porous carbon material according to claim 8, characterized in that, The dense porous carbon material has a mesoporous rate of ≥40% and a compressive strength of ≥5MPa.

10. An application of the dense porous carbon material according to claim 8, characterized in that, The dense porous carbon material is used as an electrode material for lithium-ion batteries, an electrode material for supercapacitors, or a catalyst support for fuel cells.

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