Porous carbon material and preparation method thereof

Abstract

The invention discloses a porous carbon material and a preparation method thereof. The nano porous carbon material has the tap density of 0.1-0.5 g / cm < 3 >, the pore diameter of 1-50 nm, the average particle diameter of 1-20 microns and the specific surface area of 500-1000 m < 2 > / g. The porous carbon material provided by the invention is uniform in internal pore distribution and small in pore channel resistance, is suitable for preparing a silicon-carbon composite material by a vapor deposition method, and can improve the silicon loading ratio and the capacity of the composite material. Meanwhile, the porous carbon is high in strength, and expansion of the composite particles can be effectively inhibited.

Description

Technical Field

[0001] The invention relates to a porous carbon material and a preparation method thereof, belonging to the technical field of carbon materials. Background Art

[0002] Porous carbon materials have been widely studied and applied due to their high specific surface area, adjustable pore structure and excellent chemical stability. According to the pore size, porous carbon materials are divided into microporous carbon (pore size <2 nm), mesoporous carbon (2–50 nm) and macroporous carbon (>50 nm); according to the morphology, they can be divided into powder, block, fiber and film-like materials. In addition, according to the different carbon sources, they can be divided into biomass-based and synthetic-based porous carbon. At present, the methods for preparing porous carbon materials mainly include template method, activation method, self-assembly method and direct carbonization method. The template method precisely controls the pore structure through hard templates (such as silica) or soft templates (such as surfactants), which is suitable for the preparation of highly regular mesoporous and macroporous carbon; the activation method uses chemical or physical activators to treat the carbon source to form a multi-level pore structure, which is a common preparation technology for biomass-based porous carbon; the self-assembly method constructs a pore structure through the self-assembly of molecules or nanoparticles, which is used for the development of high-performance materials; the direct carbonization method carbonizes and activates natural biomass, which is an effective way to prepare at low cost.

[0003] Porous carbon materials have a wide range of applications in energy storage, adsorption and separation, catalysis, and biomedicine. In the field of energy storage, as an electrode material for supercapacitors, lithium-ion batteries, and sodium-ion batteries, it significantly improves energy density and cycle life due to its high specific surface area and electrical conductivity; in the field of adsorption and separation, porous carbon can efficiently adsorb water pollutants, purify air, and capture carbon dioxide with its high porosity and surface chemical properties; in the field of catalysis, it can be used directly as a catalyst or as a catalyst carrier, and is widely used in fuel cells and electrocatalytic reactions; in biomedicine, porous carbon has good biocompatibility and functionalization potential as a drug carrier and biosensor. In the future, with the development of green preparation technology and precise control of pore structure, porous carbon materials will play a more important role in the fields of new energy, environmental protection, and high-end manufacturing. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a porous carbon material. The nano porous carbon material has a uniform pore structure, a small pore size and a large specific surface area.

[0005] A porous carbon material comprises a carbon skeleton and pores, wherein the pores have a nanometer diameter of 1-100 nm and a tap density of 0.1-0.5 g / cm 3 .

[0006] The porous carbon material may be made of any of soft carbon, hard carbon, and graphite.

[0007] Tap density is 0.1-0.3 g / cm 3 ; Pore diameter 1-100nm.

[0008] The particle size of a single porous carbon material is 1-20 μm, preferably 3-7 μm.

[0009] The specific surface area of ​​porous carbon materials is 500-1000 m 2 / g.

[0010] The method for preparing the porous carbon material comprises the following steps: Carbon is used as the workpiece electrode and tool electrode respectively, connected to the positive and negative electrodes of the pulse power supply respectively, inert liquid or gas is used as the working medium, and a proper gap is maintained between the two electrodes; Pulse discharge causes the carbon material on the surface of the tool electrode and the workpiece electrode to melt or gasify; Under the cooling effect of the medium, the melted or gasified carbon material quickly condenses and agglomerates to obtain a porous carbon material.

[0011] The workpiece electrode uses block carbon material with a thickness of 0.1-50 mm, preferably 5-20 mm; the tool electrode uses columnar carbon material with a diameter of 0.1-10 mm, preferably 0.5-3 mm.

[0012] The pulse width of the electric pulse of the pulse power supply is 50 ns-500 μs, preferably 500-1000 ns.

[0013] The inert liquid or gas is the working medium. The inert liquid is one or a combination of at least two of deionized water, kerosene, and ethylene glycol; the inert gas is one or a combination of at least two of high-purity argon, helium, neon, krypton, and xenon.

[0014] The beneficial effects of the present invention are: the porous carbon material obtained by the method has a large specific surface area and a uniform pore size distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : SEM photograph of the porous carbon prepared in Example 1. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is described in detail as follows: A porous carbon material having a tap density of 0.1-0.5 g / cm 3 , preferably 0.1-0.3 g / cm 3 ; The pore size is 1-100 nm, preferably 1-50 nm.

[0017] Preferably, the porous carbon material has an average particle size of 1-20 μm, preferably 3-7 μm.

[0018] Preferably, the porous carbon material has a specific surface area of ​​500-1000 m 2 / g, preferably 800-1000 m 2 / g.

[0019] The method for preparing any of the above-mentioned porous carbon materials is to use a bulk carbon material and a tubular carbon material as electrodes, and respectively connect them to the positive and negative electrodes of a pulse power supply, use an inert non-conductive liquid or gas as a working medium, apply electricity and collect the generated particles, and the obtained particles are nanoporous carbon materials; specifically, the following steps are included: Step 1: Select block carbon material as workpiece electrode and columnar carbon material as tool electrode, and connect them to the positive and negative poles of pulse power supply respectively. Use inert liquid or gas as working medium to ensure that there is a proper gap between the two electrodes.

[0020] Step 2: During the pulse discharge process, positive and negative charges gradually accumulate between the two electrodes to form a high-intensity electric field. When the electric field strength exceeds the insulation breakdown limit of the working medium, the medium undergoes impact ionization to form a stable ion channel, i.e., the discharge channel. The high-intensity current passing through the channel triggers the ionization of the medium and generates high-temperature plasma. In the discharge area, the temperature can reach thousands of degrees Celsius, causing the carbon materials on the surfaces of the tool electrode and the workpiece electrode to melt and gasify.

[0021] Step 3: After the discharge is completed, the vaporized carbon atoms and their clusters are taken away from the discharge area by the working medium. Under the cooling effect of the medium, these carbon clusters quickly condense and agglomerate, and gradually self-assemble to form a nanoporous carbon material with a porous structure.

[0022] This process achieves the preparation of nanoporous carbon materials through the thermal effect induced by the electric field and the condensation of the working medium, combined with the material migration and self-assembly mechanism between electrodes, showing high precision and efficiency.

[0023] Preferably, the block carbon material is any one of soft carbon, hard carbon and graphite; the carbon material is made into a block-shaped electrode with a thickness of 0.1-50 mm, preferably 5-20 mm; Preferably, the columnar carbon material is any one of soft carbon, hard carbon and graphite; preferably graphite material; the carbon material is made into a columnar shape with a diameter of 0.1-10 mm, preferably 0.5-3 mm; The pulse width of the electric pulse of the pulse power supply is 50ns-500 μs, preferably 500-1000 ns; The inert liquid or gas is the working medium. The inert liquid is one or a combination of at least two of deionized water, kerosene, and ethylene glycol; the inert gas is one or a combination of at least two of high-purity argon, helium, neon, krypton, and xenon.

[0024] The collected material is a porous carbon material, and the particle size needs to be screened, with an average particle size of 1-20 μm, preferably 3-7 μm.

[0025] Example 1 In the first step, a 10 mm thick bulk carbon material is selected as the workpiece electrode, a 1 mm diameter graphite is selected as the tool electrode, and high-purity argon is selected as the working medium.

[0026] In the second step, a pulse power supply is selected to generate a discharge pulse with a pulse width of 50 ns, a duty cycle of 1:4, and an open circuit voltage of 160 V. A rectangular pulse voltage is applied between the workpiece electrode and the tool electrode to ionize and break down the insulating working medium to form a plasma discharge channel. The high-temperature etched material is obtained, and the agglomerated particles are recorded as C-1 (such as Figure 1 as shown).

[0027] Comparative Example 1 The difference from Example 1 is that in step 2, the discharge pulse width generated by the pulse power supply is selected to be 5 μs, and the obtained agglomerated particles are recorded as C-2.

[0028] Comparative Example 2 The difference from Example 1 is that in step 2, the discharge pulse width generated by the pulse power supply is selected to be 500 μs, and the obtained agglomerated particles are recorded as C-3. Example

[0029] The difference from Example 1 is that in step 1, dekerosene is selected as the working medium; in step 2, the agglomerated particles obtained are recorded as C-4.

[0030] Comparative Example 3 The difference from Example 2 is that in step 2, the discharge pulse width generated by the pulse power supply is selected to be 5 μs, and the obtained agglomerated particles are recorded as C-5.

[0031] Table 1 Main physical characterization results of porous carbon materials prepared in Examples 1-2 and Comparative Examples 1-3

[0032] It can be seen from Example 1 and Comparative Examples 1 and 2 that when a larger pulse width is used, the duration of a single pulse discharge increases, resulting in a significant increase in the energy input of a single discharge. This high energy input will increase the diameter of the discharge channel, and the accumulation of energy will cause more material to be melted or vaporized, resulting in a larger pore size.

Claims

1. A porous carbon material, characterized in that: It includes a carbon skeleton and pores, wherein the pore size is nanoscale, ranging from 1 to 100 nm, and its tap density is 0.1 to 0.5 g / cm 3 .

2. The porous carbon material according to claim 1, characterized in that The porous carbon material may be made of any of soft carbon, hard carbon, and graphite.

3. The porous carbon material according to claim 1, characterized in that Tap density is 0.1-0.3 g / cm 3 ; Pore diameter 1-100nm.

4. The porous carbon material according to claim 1, characterized in that The particle size of a single porous carbon material is 1-20 μm, preferably 3-7 μm.

5. The porous carbon material according to claim 1, characterized in that: The specific surface area of ​​porous carbon materials is 500-1000m 2 / g.

6. The method for preparing the porous carbon material according to claim 1, characterized in that: The steps include: Carbon is used as the workpiece electrode and tool electrode respectively, connected to the positive and negative electrodes of the pulse power supply respectively, inert liquid or gas is used as the working medium, and a proper gap is maintained between the two electrodes; Pulse discharge causes the carbon material on the surface of the tool electrode and the workpiece electrode to melt or gasify; Under the cooling effect of the medium, the melted or gasified carbon material quickly condenses and agglomerates to obtain a porous carbon material.

7. The method for preparing a porous carbon material according to claim 6, characterized in that: The workpiece electrode uses block carbon material with a thickness of 0.1-50 mm, preferably 5-20 mm; the tool electrode uses columnar carbon material with a diameter of 0.1-10 mm, preferably 0.5-3 mm.

8. The method for preparing a porous carbon material according to claim 6, characterized in that: The pulse width of the electric pulse of the pulse power supply is 50 ns-500 μs, preferably 500-1000 ns.

9. The method for preparing a porous carbon material according to claim 6, characterized in that: The inert liquid or gas is the working medium. The inert liquid is one or a combination of at least two of deionized water, kerosene, and ethylene glycol; the inert gas is one or a combination of at least two of high-purity argon, helium, neon, krypton, and xenon.

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