A porous carbon support for silicon-oxygen anodes in lithium batteries and its preparation method

Abstract

This invention belongs to the technical field of lithium-ion battery silicon-oxygen anode materials, and particularly relates to a porous carbon support for lithium-ion battery silicon-oxygen anodes and its preparation method, comprising the following steps: 1) pretreating the raw material oil to obtain a low-condensation-degree carbon-rich precursor; 2) subjecting the low-condensation-degree carbon-rich precursor to oxidative crosslinking treatment to obtain a heavy condensate polymer; 3) separating the heavy condensate polymer by multi-stage supercritical extraction to obtain components A, B, and C, respectively, and then mixing components A, B, and C after drying to obtain a carbon support precursor; 4) subjecting the carbon support precursor to pre-oxidation, etching, and carbonization to obtain a porous carbon support for silicon-oxygen anodes. The advantages are: the porous carbon support for lithium-ion battery silicon-oxygen anodes prepared by this invention has the advantages of low density and light weight, reasonable pore size distribution, high specific surface area, and excellent conductivity.

Description

Technical Field

[0001] This invention belongs to the technical field of silicon-oxygen anode materials for lithium batteries, and particularly relates to a porous carbon support for silicon-oxygen anodes in lithium batteries and its preparation method. Background Technology

[0002] In recent years, with the rapid rise of emerging fields such as grid energy storage, new energy vehicles, and consumer electronics, higher requirements have been placed on the cycle performance, energy density, and safety of lithium-ion batteries. Therefore, developing lithium-ion batteries with long cycle stability and high energy density is of great significance for meeting the ever-increasing energy storage demands of various technologies in portable electronic devices, electric vehicles, and large-scale energy storage systems. However, the energy density of full cells using graphite anode materials matched with high-energy-density nickel-cobalt-manganese oxides, which are currently the most widely used commercially available, is less than 250 Wh / kg, which is insufficient to meet the high energy density demands of many end users. Therefore, to achieve the goal of lithium-ion battery energy density reaching 400-500 Wh / kg, the core of developing next-generation lithium-ion batteries is to develop inexpensive and abundant high-energy-density electrode materials.

[0003] Among the many known anode materials, silicon-based materials possess extremely high specific capacity (4200 mAh / g, more than 10 times that of graphite anodes), which is crucial for improving the energy density of lithium-ion batteries. By adding 5-10 wt% Si anode material to graphite, the target energy density of power batteries can be achieved at 300 Wh / kg. Furthermore, the lithium intercalation potential of Si materials is slightly higher than that of graphite (~0.4 V vs Li / Li). + This effectively avoids the growth of lithium dendrites, reducing the risk of battery safety accidents, and also possesses abundant natural resources and good environmental compatibility. Unfortunately, Si materials are accompanied by severe volume changes (300%~400%), continuous growth of the SEI film, and low intrinsic conductivity (10⁻⁶) during lithium insertion / extraction. -5 Up to 10 -3 S / cm) and Li + Diffusion rate (10) -14 Up to 10 -13 cm 2 The large-scale commercial application of Si materials is severely hampered by the fact that the Si material is not readily available.

[0004] In comparison, non-stoichiometric silicon suboxide (SiO2) x Materials with the properties of 0≤x≤2 (0≤x≤2) also exhibit high specific capacity (2200~2500mAh / g) and superior cycling stability compared to Si materials, attracting widespread attention. Therefore, in-depth research on SiO2 is necessary. x Develop carbon support for silicon-oxygen anodes, and apply it as an anode material in lithium-ion batteries to improve the performance of SiO2.x The lithium storage performance of materials is of great significance for realizing high-energy-density lithium-ion batteries. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a porous carbon support for silicon-oxygen anodes in lithium batteries and a preparation method thereof. The raw materials are widely available, and the prepared porous carbon support is rich in heteroatoms, has a hierarchical porous structure, and features low density, light weight, reasonable pore size distribution, high specific surface area, and excellent conductivity.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode includes the following steps:

[0008] 1) Pre-treating the feedstock oil yields a type of low-condensation-degree carbon-rich precursor;

[0009] 2) Low-condensation-degree carbon-rich precursors are subjected to oxidative crosslinking treatment to obtain heavy condensate polymers;

[0010] 3) The heavy condensate was separated by multi-stage supercritical extraction to obtain components A, B and C respectively. After drying, components A, B and C were blended to obtain a carbon support precursor.

[0011] 4) The carbon support precursor is pre-oxidized, etched, and carbonized to obtain a porous carbon support for silicon-oxygen anodes.

[0012] The feedstock oil is one or more of the following: medium-low temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue, and viscosity-reducing cracking residue.

[0013] The pretreatment in step 1) is one or more of the following: solid-liquid separation, solvent sedimentation, solvent extraction purification, solvent deasphalting, furfural solvent purification, supercritical fluid extraction, catalytic hydrogenation, and short-process molecular cutting.

[0014] The low-condensation-degree carbon-rich precursor has a saturated content ≤10wt%, an aromatic content ≥60wt%, a resin content ≥18wt%, an asphaltene content ≤1wt%, an ash content ≤0.05wt%, and an H / C atomic ratio of (0.1~0.15):1.

[0015] In step 2), the reaction reagent used in the oxidative crosslinking process is one of the following solvents: paraformaldehyde, benzaldehyde, glyoxal, glutaraldehyde, and alkylphenol resin, or a compound solvent of the aforementioned solvents; the mass ratio of the reaction reagent to the low condensation degree carbon-rich precursor is (1~10):100, the vacuum degree is 0.01~0.09MPa, the heating rate is 5~15℃ / min, the reaction temperature is 280~420℃, and the treatment time is 0.5~4h.

[0016] The obtained heavy condensate has the following properties: the size of the microcrystalline unit is controlled at 2~15μm, the content of secondary quinoline insolubles is 1%~30%, and the ash content is ≤0.05%.

[0017] In step 3), the multi-stage supercritical extraction is performed in stages: first-stage, second-stage, third-stage, and above. Based on the molecular weight requirements, if the molecular weight of the extracted product is 5000-50000, first-stage supercritical extraction is used; if the molecular weight is 2600-5000 (excluding 5000), second-stage supercritical extraction is used; and if the molecular weight is 200-2600 (excluding 2600), third-stage or higher supercritical extraction is used.

[0018] The extractant used in the separation is one or more of H2O, acetone, benzene, toluene, xylene, pyridine, quinoline, furfural, and N-methylpyrrolidone; the reaction conditions are: separation temperature of 30~85℃, separation time of 0.5~4h, and separation pressure of 1~10MPa.

[0019] In step 3), component A has a molecular weight of 200-1800, volatile matter ≤15%, ash content ≤0.05%, and a C / H atomic ratio of (0.56-1.25):1. 50 The micrometer diameter is 1~5μm, and the specific surface area is 1200~2000m². 2 / g;

[0020] Component B has a molecular weight of 1000~2600, volatile matter ≤10%, ash content ≤0.05%, and a C / H atomic ratio of (1.25~2.0):1. 50 Its thickness is 3~15μm, and its specific surface area is 800~1500m². 2 / g;

[0021] Component C has a molecular weight of 1800~50000, volatile matter ≤5%, ash content ≤0.05%, and a C / H atomic ratio of (1.67~2.25):1. 50 The micrometer diameter is 10~30 μm, and the specific surface area is 600~1000 m². 2 / g.

[0022] The carbon support precursor obtained in step 3) has a fixed carbon content ≥95%, volatile matter ≤10%, ash content ≤0.05%, and bulk density ≤0.6 g / cm³. 3 .

[0023] In step 4), the oxidant used for pre-oxidation is one of HNO3, H2SO4, KMnO4, and H2O2. The reaction conditions for pre-oxidation are: oxidation reaction temperature of 150~350℃, oxidation residence time of 1~6h, and the mixing ratio of oxidant to carbon support precursor of (0.5~2):1.

[0024] The etching process is classified into three stages based on the structure of the etching product: single-stage etching reaction processing, two-stage etching reaction processing, and three or more-stage etching reaction processing.

[0025] The specific surface area of ​​the etched product structure is 600~1000m². 2 / g, excluding 1000m 2 / g, when the micropore ratio is ≥10% and the mesopore ratio is ≥30%, a single-stage etching reaction treatment is adopted;

[0026] The specific surface area of ​​the etched product structure is 1000~1800m². 2 / g, excluding 1800m 2 / g, when the micropore ratio is ≥20% and the mesopore ratio is ≥40%, a two-stage etching reaction treatment is adopted;

[0027] The specific surface area of ​​the etched product structure is 1800~2800m². 2 / g, when the micropore ratio is ≥30% and the mesopore ratio is ≥50%, three or more etching reaction processes are adopted;

[0028] The etching reaction conditions are as follows: reaction temperature is 600~1200℃, reaction time is 2~10h, and the reaction medium is one of KOH, NaOH, CO2, water vapor, NaHCO3, KHCO3, and H3PO4.

[0029] The carbonization reaction conditions are as follows: heating under nitrogen protection, nitrogen flow rate of 300~1200 ml / min, heating rate of 5~15℃ / min, carbonization temperature of 800~1500℃, and final temperature holding time of 2~8 h.

[0030] A porous carbon support for silicon-oxygen anodes in lithium-ion batteries, wherein the specific surface area of ​​the porous carbon support for silicon-oxygen anodes in lithium-ion batteries is 1000~3000 m². 2 / g, pore volume 0.4~1.4cm 3 / g, average pore size 20~100nm, micropores ≥20%, mesopores ≥50%, true density 1.50~2.0g / cm³ 3 Tap density ≥ 0.6 g / cm³ 3 Ash content < 0.05%, particle size distribution, D 50 15~45μm, D max≤80μm, interlayer spacing is 0.34nm~0.375nm; OI value <50, carbon crystallinity: ID / IG <1.0.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1) The porous carbon support for lithium-ion battery silicon-oxygen anodes prepared by this invention has the advantages of low density and light weight, reasonable pore size distribution, high specific surface area, and excellent conductivity. Its specifications include a specific surface area of ​​1000~3000 m². 2 / g, pore volume 0.4~1.4cm 3 / g, average pore size 20~100nm, micropores ≥20%, mesopores ≥50%, true density 1.50~2.0g / cm³ 3 Tap density ≥ 0.6 g / cm³ 3 Ash content < 0.05%, particle size distribution, D 50 15~45μm, D max ≤80μm, interlayer spacing (d 002 The wavelength range is 0.34 nm to 0.375 nm. The OI value is <50, and the carbon crystallinity is ID / IG <1.0.

[0033] 2) This invention has the following advantages:

[0034] ① Low cost and wide availability; ② Porous carbon support for silicon-carbon anodes has a hierarchical porous structure, and the structure obtained varies greatly depending on the properties of the raw oil and the pretreatment method; ③ Rich in heteroatoms, which can increase the wettability of the electrode material surface and reduce the interfacial resistance.

[0035] 3) Using porous carbon supports to prepare silicon-oxygen anode materials for lithium-ion batteries allows for micron-scale control, resulting in products with complete structures and good morphology. Furthermore, the deposited silicon-oxygen materials exhibit uniform composition, dense structure, low expansion rate, and excellent cycle life. Bulk expansion rate ≤120%, cycle life ≥800 cycles.

[0036] 4) According to the process requirements of silicon-oxygen anode, the performance of carbon support precursor and the structure of porous carbon support can be controlled by mixing components A, B and C in different proportions. Attached Figure Description

[0037] Figure 1 This is a 5000x scanning electron microscope (SEM) image of a porous carbon support used in silicon-oxygen anodes for lithium-ion batteries.

[0038] Figure 2 This is a 20,000x scanning electron microscope (SEM) image of a porous carbon support used in silicon-oxygen anodes for lithium-ion batteries. Detailed Implementation

[0039] The present invention will now be described in detail, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0040] A method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode includes the following steps:

[0041] 1) Pre-treating the feedstock oil yields a type of low-condensation-degree carbon-rich precursor;

[0042] The feedstock is one or more of the following: medium-low temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue, and viscosity-reducing cracking residue.

[0043] Pretreatment includes one or more of the following: solid-liquid separation, solvent sedimentation, solvent extraction purification, solvent deasphalting, furfural solvent purification, supercritical fluid extraction, catalytic hydrogenation, and short-process molecular cutting.

[0044] The specifications for low-condensation-degree carbon-rich precursors are: saturated content ≤10wt%, aromatic content ≥60wt%, resin ≥18wt%, asphaltenes ≤1wt%, ash content ≤0.05wt%, and H / C atomic ratio of (0.1~0.15):1.

[0045] 2) Low-condensation-degree carbon-rich precursors are subjected to oxidative crosslinking treatment to obtain heavy condensate polymers;

[0046] The reaction reagent used in the oxidative crosslinking process is one of the following solvents: paraformaldehyde, benzaldehyde, glyoxal, glutaraldehyde, alkylphenol resin, or a compound solvent of the aforementioned solvents; the mass ratio of the reaction reagent to the low condensation degree carbon-rich precursor is (1~10):100, the vacuum degree is 0.01~0.09MPa, the heating rate is 5~15℃ / min, the reaction temperature is 280~420℃, and the treatment time is 0.5~4h.

[0047] The obtained heavy condensate has the following properties: the size of the microcrystalline unit is controlled at 2~15μm, the content of secondary quinoline insolubles is 1%~30%, and the ash content is ≤0.05%.

[0048] 3) The heavy condensate was separated by multi-stage supercritical extraction to obtain components A, B and C respectively. After drying, components A, B and C were mixed to obtain a carbon support precursor. Components A, B and C are all mixtures of liquid and semi-solid phases and are different mixtures distinguished by molecular weight.

[0049] Multi-stage supercritical extraction separation is based on molecular weight requirements, and is carried out in stages: single-stage supercritical extraction is used for products with molecular weight of 5000~50000; single-stage supercritical extraction is used for products with molecular weight of 2600~5000 (excluding 5000); and triple-stage or higher supercritical extraction is used for products with molecular weight of 200~2600.

[0050] The extractant used is one or more of H2O, acetone, benzene, toluene, xylene, pyridine, quinoline, furfural, and N-methylpyrrolidone; the reaction conditions are: separation temperature of 30~85℃, separation time of 0.5~4h, and separation pressure of 1~10MPa.

[0051] Component A has a molecular weight of 200~1800, volatile matter ≤15%, ash content ≤0.05%, and a C / H atomic ratio of (0.56~1.25):1. 50 The micrometer diameter is 1~5μm, and the specific surface area is 1200~2000m². 2 / g;

[0052] Component B has a molecular weight of 1000~2600, volatile matter ≤10%, ash content ≤0.05%, and a C / H atomic ratio of (1.25~2.0):1. 50 Its thickness is 3~15μm, and its specific surface area is 800~1500m². 2 / g;

[0053] Component C has a molecular weight of 1800~50000, volatile matter ≤5%, ash content ≤0.05%, and a C / H atomic ratio of (1.67~2.25):1. 50 The micrometer diameter is 10~30 μm, and the specific surface area is 600~1000 m². 2 / g.

[0054] The obtained carbon support precursor has a fixed carbon content ≥95%, volatile matter ≤10%, ash content ≤0.05%, and bulk density ≤0.6 g / cm³. 3 .

[0055] 4) The carbon support precursor is pre-oxidized, etched, and carbonized to obtain a porous carbon support for silicon-oxygen anodes.

[0056] The oxidant used in the pre-oxidation is one of HNO3, H2SO4, KMnO4, and H2O2. The reaction conditions for pre-oxidation are: oxidation reaction temperature of 150~350℃, oxidation residence time of 1~6h, and the mixing ratio of oxidant to carbon support precursor of (0.5~2):1.

[0057] Etching is classified into single-stage etching reaction processing, two-stage etching reaction processing, and three-stage or more etching reaction processing according to the structure of the final etching product. When using two-stage or more etching reaction processing, a single-stage etching reaction processing is performed first, followed by a two-stage etching reaction processing, and finally a three-stage or more processing.

[0058] The specific surface area of ​​the etched product structure is 600~1000m². 2 / g, excluding 1000m 2 / g, when the micropore ratio is ≥10% and the mesopore ratio is ≥30%, a single-stage etching reaction treatment is adopted;

[0059] The specific surface area of ​​the etched product structure is 1000~1800m². 2 / g, excluding 1800m 2 / g, when the micropore ratio is ≥20% and the mesopore ratio is ≥40%, a two-stage etching reaction treatment is adopted;

[0060] The specific surface area of ​​the etched product structure is 1800~2800m². 2 When the micropore ratio is ≥30% and the mesopore ratio is ≥50%, a three-stage or higher etching reaction process is adopted.

[0061] The etching reaction conditions are as follows: reaction temperature is 600~1200℃, reaction time is 2~10h, and the reaction medium is one of KOH, NaOH, CO2, water vapor, NaHCO3, KHCO3, and H3PO4.

[0062] The carbonization reaction conditions are as follows: heating under nitrogen protection, nitrogen flow rate of 300~1200 ml / min, heating rate of 5~15℃ / min, carbonization temperature of 800~1500℃, and final temperature holding time of 2~8 h.

[0063] See Figure 1 , Figure 2 The specific surface area of ​​porous carbon support used in lithium-ion battery silicon-oxygen anodes is 1000~3000 m². 2 / g, pore volume 0.4~1.4cm 3 / g, average pore size 20~100nm, micropores ≥20%, mesopores ≥50%, true density 1.50~2.0g / cm³ 3 Tap density ≥ 0.6 g / cm³ 3 Ash content < 0.05%, particle size distribution, D 50 15~45μm, D max ≤80μm, interlayer spacing (d 002 The wavelength range is 0.34nm to 0.375nm; OI value < 50; carbon crystallinity: ID / IG < 1.0.

[0064] Example:

[0065] The preparation process parameters and test results of the porous carbon support for the silicon-oxygen anode of lithium batteries in Examples 1-5 are shown in Tables 1-3.

[0066] Table 1. Preparation process and indicators of heavy condensate polymers

[0067]

[0068] Table 2. Preparation process and indicators of carbon support precursors

[0069]

[0070] Table 3. Preparation process and indicators of porous carbon support for silicon-oxygen anodes

[0071]

[0072] This invention discloses a porous carbon support for lithium-ion battery silicon-oxygen anodes, characterized by low density, light weight, reasonable pore size distribution, high specific surface area, and excellent conductivity, as well as its preparation method. The preparation method of this invention has the following advantages: ① low cost and wide availability; ② the porous carbon support for silicon-oxygen anodes has a hierarchical porous structure, and the structures obtained vary greatly depending on the properties of the raw oil and the pretreatment methods; ③ it is rich in heteroatoms, which can increase the wettability of the electrode material surface and reduce the interfacial resistance. The silicon-oxygen anode material prepared using the porous carbon support for lithium-ion battery silicon-oxygen anodes achieves micron-scale control, with a complete product structure and good morphology. Simultaneously, the deposited silicon-oxygen material has uniform composition, dense structure, low expansion rate, and excellent cycle performance.

Claims

1. A method for preparing a porous carbon support for a silicon-oxygen anode in a lithium battery, characterized in that, Includes the following steps: 1) Pre-treating the feedstock oil yields a type of low-condensation-degree carbon-rich precursor; 2) Low-condensation-degree carbon-rich precursors are subjected to oxidative crosslinking treatment to obtain heavy condensate polymers; 3) The heavy condensate was separated by multi-stage supercritical extraction to obtain components A, B and C respectively. After drying, components A, B and C were blended to obtain a carbon support precursor. 4) The carbon support precursor is pre-oxidized, etched, and carbonized to obtain a porous carbon support for silicon-oxygen anodes. The low-condensation-degree carbon-rich precursor has a saturated content ≤10wt%, an aromatic content ≥60wt%, a resin content ≥18wt%, an asphaltenes content ≤1wt%, an ash content ≤0.05wt%, and an H / C atomic ratio of (0.1~0.15):1; The obtained heavy condensate has the following properties: the size of the microcrystalline unit is controlled at 2~15μm, the content of secondary quinoline insolubles is 1%~30%, and the ash content is ≤0.05%; In step 3), component A has a molecular weight of 200-1800, volatile matter ≤15%, ash content ≤0.05%, and a C / H atomic ratio of (0.56-1.25):

1. 50 The micrometer diameter is 1~5μm, and the specific surface area is 1200~2000m². 2 / g; Component B has a molecular weight of 1000~2600, volatile matter ≤10%, ash content ≤0.05%, and a C / H atomic ratio of (1.25~2.0):

1. 50 Its thickness is 3~15μm, and its specific surface area is 800~1500m². 2 / g; Component C has a molecular weight of 1800~50000, volatile matter ≤5%, ash content ≤0.05%, and a C / H atomic ratio of (1.67~2.25):

1. 50 The micrometer diameter is 10~30 μm, and the specific surface area is 600~1000 m². 2 / g; The porous carbon support used for the silicon-oxygen anode in the lithium battery has a specific surface area of ​​1000~3000 m². 2 / g, pore volume 0.4~1.4cm 3 / g, average pore size 20~100nm, micropores ≥20%, mesopores ≥50%, true density 1.50~2.0g / cm³ 3 Tap density ≥ 0.6 g / cm³ 3 Ash content < 0.05%, particle size distribution, D 50 15~45μm, D max ≤80μm, interlayer spacing is 0.34nm~0.375nm; OI value < 50, carbon crystallinity: ID / IG < 1.

0.

2. The method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode according to claim 1, characterized in that, The feedstock oil is one or more of the following: medium-low temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue, and viscosity-reducing cracking residue.

3. The method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode according to claim 1, characterized in that, The pretreatment in step 1) is one or more of the following: solid-liquid separation, solvent sedimentation, solvent extraction purification, solvent deasphalting, furfural solvent purification, supercritical fluid extraction, catalytic hydrogenation, and short-process molecular cutting.

4. The method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode according to claim 1, characterized in that, In step 2), the reaction reagent used in the oxidative crosslinking process is one of the following solvents: paraformaldehyde, benzaldehyde, glyoxal, glutaraldehyde, alkylphenol resin, or a compound solvent of the above solvents; the mass ratio of the reaction reagent to the low condensation degree carbon-rich precursor is (1~10):100, the vacuum degree is 0.01~0.09MPa, the heating rate is 5~15℃ / min, the reaction temperature is 280~420℃, and the treatment time is 0.5~4h.

5. The method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode according to claim 1, characterized in that, In step 3), the multi-stage supercritical extraction is performed in stages: first-stage, second-stage, third-stage, and above. Based on the molecular weight requirements, if the molecular weight of the extracted product is 5000-50000, first-stage supercritical extraction is used; if the molecular weight is 2600-5000 (excluding 5000), second-stage supercritical extraction is used; and if the molecular weight is 200-2600 (excluding 2600), third-stage or higher supercritical extraction is used. The extractant used in the separation is one or more of H2O, acetone, benzene, toluene, xylene, pyridine, quinoline, furfural, and N-methylpyrrolidone; the reaction conditions are: separation temperature of 30~85℃, separation time of 0.5~4h, and separation pressure of 1~10MPa.

6. The method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode according to claim 1, characterized in that, The carbon support precursor obtained in step 3) has a fixed carbon content ≥95%, volatile matter ≤10%, ash content ≤0.05%, and bulk density ≤0.6 g / cm³. 3 .

7. The method for preparing a porous carbon support for a lithium-ion battery silicon-oxygen anode according to claim 1, characterized in that, In step 4), the oxidant used for pre-oxidation is one of HNO3, H2SO4, KMnO4, and H2O2; the reaction conditions for pre-oxidation are: oxidation reaction temperature of 150~350℃, oxidation residence time of 1~6h, and the mixing ratio of oxidant to carbon support precursor of (0.5~2):

1. The etching process is classified into three stages based on the structure of the etching product: single-stage etching reaction processing, two-stage etching reaction processing, and three or more-stage etching reaction processing. The specific surface area of ​​the etched product structure is 600~1000m². 2 / g, excluding 1000m 2 / g, when the micropore ratio is ≥10% and the mesopore ratio is ≥30%, a single-stage etching reaction treatment is adopted; The specific surface area of ​​the etched product structure is 1000~1800m². 2 / g, excluding 1800m 2 / g, when the micropore ratio is ≥20% and the mesopore ratio is ≥40%, a two-stage etching reaction treatment is adopted; The specific surface area of ​​the etched product structure is 1800~2800m². 2 / g, when the micropore ratio is ≥30% and the mesopore ratio is ≥50%, three or more etching reaction processes are adopted; The etching reaction conditions are as follows: reaction temperature is 600~1200℃, reaction time is 2~10h, and the reaction medium is one of KOH, NaOH, CO2, water vapor, NaHCO3, KHCO3, and H3PO4. The carbonization reaction conditions are as follows: heating under nitrogen protection, nitrogen flow rate of 300~1200 ml / min, heating rate of 5~15℃ / min, carbonization temperature of 800~1500℃, and final temperature holding time of 2~8 h.

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