Porous carbon carrier for silicon-oxygen negative electrode of lithium battery and preparation method of porous carbon carrier

Abstract

The invention belongs to the technical field of lithium battery silicon-oxygen negative electrode materials, and particularly relates to a porous carbon carrier for a lithium battery silicon-oxygen negative electrode and a preparation method, the preparation method comprises the following steps: 1) pretreating raw oil to obtain a low-condensation-degree carbon-rich precursor; 2) performing oxidation crosslinking treatment on the low-condensation-degree carbon-rich precursor to obtain a heavy condensation polymer; 3) carrying out multistage supercritical extraction separation on the heavy condensation polymer to respectively obtain a component A, a component B and a component C, and drying and mixing the component A, the component B and the component C to obtain a carbon carrier precursor; 4, the carbon carrier precursor is subjected to pre-oxidation, etching and carbonization, and the porous carbon carrier for the silicon-oxygen negative electrode is obtained.The prepared porous carbon carrier for the silicon-oxygen negative electrode of the lithium battery has the advantages of being small in density, light in mass, reasonable in pore size distribution, high in specific surface area and excellent in conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon-oxygen negative electrode materials for lithium batteries, and in particular relates to a porous carbon carrier for silicon-oxygen negative electrodes of lithium batteries and a preparation method thereof. Background Art

[0002] In recent years, with the rapid rise of emerging fields such as grid energy storage, new energy vehicles and consumer electronic devices, higher requirements have been placed on the cycle performance, energy density and safety of lithium-ion batteries. Therefore, the development of lithium-ion batteries with long cycle stability and high energy density is of great significance to meet the growing energy storage needs of various technical applications in portable electronic devices, electric vehicles and large-scale energy storage systems. However, the full battery energy density of the most widely commercialized graphite anode material matched with high-energy nickel-cobalt-manganese oxide is less than 250Wh / kg, which is difficult to meet the high energy density needs of many end users. Therefore, in order to achieve the goal of lithium-ion battery energy density of 400-500Wh / kg, the core of developing the next generation of lithium-ion batteries is to develop cheap and abundant high-energy electrode materials.

[0003] Among the many known negative electrode materials, silicon-based materials have extremely high mass specific capacity (4200mAh / g, 10 times higher than the specific capacity of graphite negative electrode), which is crucial for improving the energy density of lithium-ion batteries. By adding 5-10wt% Si negative electrode material to graphite, the goal of achieving a power battery energy density of 300Wh / kg is achieved. In addition, the lithium insertion potential of Si material is slightly higher than that of graphite (~0.4VvLi / Li + ), which can effectively avoid the growth of lithium dendrites and reduce the risk of battery safety accidents. It also has abundant natural resources and good environmental affinity. Unfortunately, the Si material is accompanied by severe volume changes (300%~400%), continuous growth of SEI film, low intrinsic conductivity (10 -5 to 10 -3 S / cm) and Li + Diffusion rate (10 -14 to 10 -13 cm 2 / s), which seriously hinders the large-scale commercial application of Si materials.

[0004] In contrast, non-stoichiometric silicon dioxide (SiO x , 0≤x≤2) materials also have a higher mass specific capacity (2200~2500mAh / g) and better cycle stability than Si materials, which has attracted widespread attention. Therefore, in-depth research on SiO x , develop carbon carriers for silicon-oxygen negative electrodes, and use them as negative electrode materials in lithium-ion batteries to improve SiOx The lithium storage performance of the material is of great significance to the realization of high energy density lithium-ion batteries. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a porous carbon support for lithium battery silicon oxygen negative electrode and a preparation method. The raw materials are widely available, and the prepared porous carbon support is rich in heteroatoms and has a hierarchical porous structure. It has the characteristics of low density and light weight, reasonable pore size distribution, high specific surface area and excellent conductivity.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery comprises the following steps:

[0008] 1) Pre-treating the crude oil to obtain a type of low-condensation carbon-rich precursor;

[0009] 2) The low-condensation carbon-rich precursor is subjected to oxidative cross-linking treatment to obtain a heavy polycondensate;

[0010] 3) The heavy polycondensate is separated by multi-stage supercritical extraction to obtain component A, component B, and component C, which are then dried and 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 the silicon-oxygen negative electrode.

[0012] The raw oil is one or more of medium and low temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue oil, and visbreaking residue oil.

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

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

[0015] The reaction reagent used in the oxidative crosslinking treatment in step 2) is a solvent selected from paraformaldehyde, benzaldehyde, glyoxal, glutaraldehyde, and an alkylphenol-formaldehyde resin, or a combination 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 0.01-0.09 MPa, the heating rate is 5-15°C / min, the reaction temperature is 280-420°C, and the treatment time is 0.5-4h;

[0016] The indicators of the obtained heavy polycondensate are: the size of the microcrystalline unit is controlled within 2-15 μm, the content of secondary quinoline insoluble matter is 1%-30%, and the ash content is ≤0.05%.

[0017] The multi-stage supercritical extraction in step 3) is a supercritical extraction treatment performed step by step in the form of a first stage, a second stage, and three or more stages; according to the molecular weight requirement, if the molecular weight of the extracted product is 5000-50000, a first stage supercritical extraction is used; if the molecular weight of the extracted product is 2600-5000 (excluding 5000), a second stage supercritical extraction is used; if the molecular weight of the extracted product is 200-2600 (excluding 2600), a third stage or more 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 as follows: the separation temperature is 30-85°C, the separation time is 0.5-4h, and the separation pressure is 1-10MPa.

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

[0020] The molecular weight of component B is 1000~2600, the volatile matter is ≤10%, the ash content is ≤0.05%, the C / H atomic ratio is (1.25~2.0):1, D 50 The particle size is 3~15μm, and the specific surface area is 800~1500m 2 / g;

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

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

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

[0024] The etching is divided into one-stage etching reaction treatment, two-stage etching reaction treatment, and three-stage or more etching reaction treatment according to the structure of the etching product;

[0025] The specific surface area of ​​the etched product structure is 600~1000m 2 / g, excluding 1000m 2 / g, when the proportion of micropores is ≥10% and the proportion of mesopores is ≥30%, a one-stage etching reaction treatment is adopted;

[0026] The specific surface area of ​​the etched product structure is 1000~1800m 2 / g, excluding 1800m 2 / g, when the proportion of micropores is ≥20% and the proportion of mesopores is ≥40%, a two-stage etching reaction treatment is used;

[0027] The specific surface area of ​​the etched product structure is 1800~2800m 2 / g, when the proportion of micropores is ≥30% and the proportion of mesopores is ≥50%, more than three stages of etching reaction treatment are used;

[0028] The etching reaction conditions are as follows: reaction temperature is 600-1200°C, reaction time is 2-10 hours, and 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, a nitrogen flow rate of 300-1200 ml / min, a heating rate of 5-15°C / min, a carbonization temperature of 800-1500°C, and a final temperature constant temperature time of 2-8 hours.

[0030] A porous carbon carrier for a lithium battery silicon-oxygen negative electrode, wherein the specific surface area of ​​the porous carbon carrier for a lithium battery silicon-oxygen negative electrode is 1000-3000m 2 / g, pore volume is 0.4~1.4cm 3 / g, average pore size is 20~100nm, micropores account for ≥20%, mesopores account for ≥50%, and true density is 1.50~2.0g / cm 3 , tap density ≥0.6g / cm 3 , ash content <0.05%, particle size distribution, D 50 :15~45μm、D max≤80μm, interlayer spacing is 0.34nm~0.375nm; OI value is <50, carbon crystallinity: ID / IG <1.0.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) The porous carbon carrier for lithium battery silicon-oxygen negative electrode prepared by the present invention has the advantages of low density, light weight, reasonable pore size distribution, high specific surface area and excellent conductivity. Its index is the specific surface area of ​​1000~3000m 2 / g, pore volume is 0.4~1.4cm 3 / g, average pore size is 20~100nm, micropores account for ≥20%, mesopores account for ≥50%, and true density is 1.50~2.0g / cm 3 , tap density ≥0.6g / cm 3 , ash content <0.05%, particle size distribution, D 50 :15~45μm、D max ≤80μm, interlayer spacing (d 002 ) is 0.34nm~0.375nm. OI value is less than 50, and carbon crystallinity: ID / IG <1.0.

[0033] 2) The present invention has the following advantages:

[0034] ① Low cost and wide source; ② The porous carbon carrier used for silicon-carbon negative electrode has a hierarchical porous structure, and the structure obtained is rich and diverse according to the different properties of the raw oil and different pretreatment methods; ③ It is rich in heteroatoms, which can increase the wettability of the electrode material surface and reduce the interface resistance.

[0035] 3) Using porous carbon supports for lithium battery silicon-oxygen anodes to prepare silicon-oxygen anode materials enables micron-scale control, resulting in a complete product structure and excellent morphology. The deposited silicon-oxygen material also exhibits uniform composition, a dense structure, low expansion, and excellent cycling performance. The volume expansion is ≤120%, and the cycle life is ≥800 cycles.

[0036] 4) According to the process requirements of the silicon-oxygen negative electrode, the performance of the carbon support precursor and the structure of the porous carbon support can be adjusted by mixing components A, B, and C in different proportions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a 5000x scanning electron microscope structure diagram of the porous carbon support used in the silicon-oxygen negative electrode of lithium batteries.

[0038] Figure 2 This is a 20,000x scanning electron microscope structure diagram of the porous carbon support used in the silicon-oxygen negative electrode of lithium batteries. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below, 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 silicon-oxygen negative electrode of a lithium battery comprises the following steps:

[0041] 1) Pre-treating the crude oil to obtain a type of low-condensation carbon-rich precursor;

[0042] The raw oil is one or more of medium and low temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue oil, and visbreaking residue oil.

[0043] The pretreatment is one or more of solid-liquid separation, "solvent method" sedimentation, solvent extraction and refining, solvent deasphalting, furfural solvent refining, supercritical fluid extraction, catalytic hydrogenation, and short-process molecular cutting.

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

[0045] 2) The low-condensation carbon-rich precursor is subjected to oxidative cross-linking treatment to obtain a heavy polycondensate;

[0046] The reaction reagent used in the oxidative crosslinking treatment process is a solvent selected from the group consisting of paraformaldehyde, benzaldehyde, glyoxal, glutaraldehyde, and alkylphenol-formaldehyde resin, or a composite 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 0.01-0.09 MPa, the heating rate is 5-15°C / min, the reaction temperature is 280-420°C, and the treatment time is 0.5-4h.

[0047] The indicators of the obtained heavy polycondensate are: the size of the microcrystalline unit is controlled within 2-15 μm, the content of secondary quinoline insoluble matter is 1%-30%, and the ash content is ≤0.05%.

[0048] 3) The heavy polycondensate is separated by multi-stage supercritical extraction to obtain component A, component B and component C, which are dried and blended to obtain a carbon support precursor; component A, component B and component 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 divided into one-stage, two-stage, and three-stage or above supercritical extraction treatment according to molecular weight requirements: if the molecular weight of the extraction product is 5000~50000, one-stage supercritical extraction is adopted; if the molecular weight of the extraction product is 2600~5000 (excluding 5000), two-stage supercritical extraction is adopted; if the molecular weight of the extraction product is 200~2600, three-stage or above supercritical extraction is adopted.

[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°C, separation time of 0.5-4h, and separation pressure of 1-10MPa.

[0051] The molecular weight of component A is 200~1800, the volatile matter is ≤15%, the ash content is ≤0.05%, the C / H atomic ratio is (0.56~1.25):1, D 50 The particle size is 1~5μm, and the specific surface area is 1200~2000m 2 / g;

[0052] The molecular weight of component B is 1000~2600, the volatile matter is ≤10%, the ash content is ≤0.05%, the C / H atomic ratio is (1.25~2.0):1, D 50 The particle size is 3~15μm, and the specific surface area is 800~1500m 2 / g;

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

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

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

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

[0057] Etching is divided into one-stage etching reaction treatment, two-stage etching reaction treatment, and three-stage or more etching reaction treatment according to the structure of the final etching product; when two-stage or more etching reaction treatment is adopted, one-stage etching reaction treatment is performed first, then two-stage etching reaction treatment is performed, and finally three-stage or more treatment is performed.

[0058] The specific surface area of ​​the etched product structure is 600~1000m 2 / g, excluding 1000m 2 / g, when the proportion of micropores is ≥10% and the proportion of mesopores is ≥30%, a one-stage etching reaction treatment is adopted;

[0059] The specific surface area of ​​the etched product structure is 1000~1800m 2 / g, excluding 1800m 2 / g, when the proportion of micropores is ≥20% and the proportion of mesopores is ≥40%, a two-stage etching reaction treatment is used;

[0060] The specific surface area of ​​the etched product structure is 1800~2800m 2 / g, when the proportion of micropores is ≥30% and the proportion of mesopores is ≥50%, more than three stages of etching reaction treatment are used.

[0061] The etching reaction conditions are as follows: reaction temperature is 600-1200° C., reaction time is 2-10 hours, and reaction medium is one of KOH, NaOH, CO 2 , water vapor, NaHCO 3 , KHCO 3 , and H 3 PO 4 .

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

[0063] See Figure 1 、 Figure 2 The specific surface area of ​​porous carbon carriers for silicon-oxygen negative electrodes of lithium batteries is 1000~3000m 2 / g, pore volume is 0.4~1.4cm 3 / g, average pore size is 20~100nm, micropores account for ≥20%, mesopores account for ≥50%, and true density is 1.50~2.0g / cm 3 , tap density ≥0.6g / cm 3 , ash content <0.05%, particle size distribution, D 50 :15~45μm、D max ≤80μm, interlayer spacing (d 002 ) is 0.34nm~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 negative electrode of the lithium battery in Examples 1 to 5 are shown in Tables 1 to 3.

[0066] Table 1 Preparation process and indicators of heavy polycondensate

[0067]

[0068] Table 2 Carbon support precursor preparation process and indicators

[0069]

[0070] Table 3 Preparation process and indicators of porous carbon carrier for silicon-oxygen negative electrode

[0071]

[0072] The porous carbon carrier for silicon-oxygen negative electrode of lithium battery prepared by the present invention has low density, light weight, reasonable pore size distribution, high specific surface area and excellent conductivity. A porous carbon carrier for silicon-carbon negative electrode of lithium battery and a preparation method thereof. The preparation method of the present invention has the following advantages: ① low cost and wide source; ② the porous carbon carrier for silicon-carbon negative electrode has a graded porous structure, and the structure obtained is rich and diverse according to the different properties of the raw oil and different pretreatment methods; ③ rich in heteroatoms, which can increase the wettability of the surface of the electrode material and reduce the interface resistance. The silicon-oxygen negative electrode material prepared by the porous carbon carrier for silicon-oxygen negative electrode of lithium battery realizes micron-scale control, the product structure is complete, the morphology is good, and the silicon-oxygen material produced by deposition has uniform components, dense structure, low expansion rate and excellent cycle performance.

Claims

1. A method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery, characterized in that: The following steps are involved: 1) Pre-treating the crude oil to obtain a type of low-condensation carbon-rich precursor; 2) The low-condensation carbon-rich precursor is subjected to oxidative cross-linking treatment to obtain a heavy polycondensate; 3) The heavy polycondensate is separated by multi-stage supercritical extraction to obtain component A, component B, and component C, which are dried and 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 the silicon-oxygen negative electrode.

2. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: The raw oil is one or more of medium and low temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue oil, and visbreaking residue oil.

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

4. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: The low-condensation carbon-rich precursor has a saturated content of ≤10wt%, an aromatic content of ≥60wt%, a colloid content of ≥18wt%, an asphaltenes content of ≤1wt%, an ash content of ≤0.05wt%, and an H / C atomic ratio of (0.1-0.15):

1.

5. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: The reaction reagent used in the oxidative crosslinking treatment in step 2) is a solvent selected from paraformaldehyde, benzaldehyde, glyoxal, glutaraldehyde, and an alkylphenol-formaldehyde resin, or a combination 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 0.01-0.09 MPa, the heating rate is 5-15°C / min, the reaction temperature is 280-420°C, and the treatment time is 0.5-4h; The indicators of the obtained heavy polycondensate are: the size of the microcrystalline unit is controlled within 2-15 μm, the content of secondary quinoline insoluble matter is 1%-30%, and the ash content is ≤0.05%.

6. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: The multi-stage supercritical extraction in step 3) is a supercritical extraction treatment performed step by step in the form of a first stage, a second stage, and three or more stages; according to the molecular weight requirement, if the molecular weight of the extracted product is 5000-50000, a first stage supercritical extraction is used; if the molecular weight of the extracted product is 2600-5000 (excluding 5000), a second stage supercritical extraction is used; if the molecular weight of the extracted product is 200-2600 (excluding 2600), a third stage or more 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 as follows: the separation temperature is 30-85°C, the separation time is 0.5-4h, and the separation pressure is 1-10MPa.

7. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: In the step 3), the molecular weight of component A is 200-1800, the volatile matter is ≤15%, the ash content is ≤0.05%, the C / H atomic ratio is (0.56-1.25):1, and D 50 The particle size is 1~5μm, and the specific surface area is 1200~2000m 2 / g; The molecular weight of component B is 1000~2600, the volatile matter is ≤10%, the ash content is ≤0.05%, the C / H atomic ratio is (1.25~2.0):1, D 50 The particle size is 3~15μm, and the specific surface area is 800~1500m 2 / g; The molecular weight of component C is 1800~50000, the volatile matter is ≤5%, the ash content is ≤0.05%, the C / H atomic ratio is (1.67~2.25):1, D 50 The particle size is 10~30μm, and the specific surface area is 600~1000m 2 / g.

8. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: The carbon carrier precursor obtained in step 3) has a fixed carbon content of ≥95%, a volatile matter of ≤10%, an ash content of ≤0.05%, and a bulk density of ≤0.6 g / cm 3 .

9. The method for preparing a porous carbon support for a silicon-oxygen negative electrode of a lithium battery according to claim 1, characterized in that: The oxidant used in the pre-oxidation in step 4) is one of HNO3, H2SO4, KMnO4, and H2O2; the reaction conditions for the pre-oxidation are: an oxidation reaction temperature of 150-350°C, an oxidation residence time of 1-6 hours, and a mixing ratio of the oxidant to the carbon support precursor of (0.5-2):1; The etching is divided into one-stage etching reaction treatment, two-stage etching reaction treatment, and three-stage or more etching reaction treatment according to the structure of the etching product; The specific surface area of ​​the etched product structure is 600~1000m 2 / g, excluding 1000m 2 / g, when the proportion of micropores is ≥10% and the proportion of mesopores is ≥30%, a one-stage etching reaction treatment is adopted; The specific surface area of ​​the etched product structure is 1000~1800m 2 / g, excluding 1800m 2 / g, when the proportion of micropores is ≥20% and the proportion of mesopores is ≥40%, a two-stage etching reaction treatment is used; The specific surface area of ​​the etched product structure is 1800~2800m 2 / g, when the proportion of micropores is ≥30% and the proportion of mesopores is ≥50%, more than three stages of etching reaction treatment are used; The etching reaction conditions are as follows: reaction temperature is 600-1200°C, reaction time is 2-10 hours, and 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, a nitrogen flow rate of 300-1200 ml / min, a heating rate of 5-15°C / min, a carbonization temperature of 800-1500°C, and a final temperature constant temperature time of 2-8 hours.

10. A porous carbon support for a silicon-oxygen negative electrode of a lithium battery prepared by the method according to any one of claims 1 to 9, characterized in that: The specific surface area of ​​the porous carbon carrier for the silicon-oxygen negative electrode of the lithium battery is 1000~3000m 2 / g, pore volume is 0.4~1.4cm 3 / g, average pore size is 20~100nm, micropores account for ≥20%, mesopores account for ≥50%, and true density is 1.50~2.0g / cm 3 , tap density ≥0.6g / cm 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.

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