A method for preparing silicon-oxygen-carbon electrode material

Abstract

The present invention provides a method for preparing a silicon-oxygen-carbon electrode material. The method comprises impregnating a silicon source in a template solution, then adding carbon nanotubes or fiber materials, filtering, drying, and calcining to obtain a composite material composed of a carbon material and all-silicon nanosheets. The composite material is then added to an alkaline solution of phenolic resin for carbonization and pulverization to obtain silicon-oxygen-carbon particles. The silicon-oxygen-carbon particles are then etched and heat-treated to obtain a silicon-oxygen-carbon electrode material rich in pores with diameters of 0.5 to 2 nm. Because all-silicon nanosheets have a relatively uniform pore structure and are nanometer-sized, they are easily reactive. The resulting silicon-oxygen-carbon electrode material exhibits excellent product consistency and spatial uniformity, with a service life increased by 2-3 times. Furthermore, due to the high mechanical strength of the reaction precursor, the silicon-oxygen-carbon electrode material can be produced in large quantities using a fluidized bed, reducing costs by 30-50%. Furthermore, the silicon-oxygen-carbon electrode material can be present in very large particles, making it easier to slurry, resulting in a 20-30% higher compaction density for the resulting electrode.

Description

Technical Field

[0001] The present invention relates to the field of clean electrochemical storage materials, and in particular to a method for preparing a silicon-oxygen-carbon electrode material. Background Art

[0002] Lithium-ion batteries are the most representative secondary batteries, with the advantages of high energy density, wide application fields, and huge market. The commercial negative electrode material for lithium-ion batteries is currently mainly graphite negative electrode, but its energy density is limited and gradually cannot meet the performance requirements of the next generation of high-energy-density lithium-ion batteries. Silicon-oxygen-carbon negative electrode material is one of the most promising negative electrode materials of the new generation, with the combined advantages of higher energy density than graphite material and lower volume expansion rate than silicon-carbon negative electrode material. At present, overall coating on the surface of silicon oxide is the most common technical means. First of all, there are great technical challenges and product consistency issues in the overall uniform coating. Secondly, during the long-term lithium intercalation and lithium deintercalation process, the expansion and contraction of the silicon-oxygen-carbon material lattice will still cause the carbon layer to peel off and the performance to deteriorate significantly. This problem has not been effectively solved so far. Summary of the Invention

[0003] In response to the above-mentioned problems existing in the prior art, the present invention provides a method for preparing a silicon-oxygen-carbon electrode material. The method comprises impregnating a template agent into a silicon source solution, then adding carbon nanotubes or fiber materials, filtering, drying, and calcining to obtain a composite material of carbon material and all-silicon nanosheets. The composite material is then added to an alkaline solution of phenolic resin for carbonization and pulverization to obtain silicon-oxygen-carbon particles. The silicon-oxygen-carbon particles are then etched and heat-treated to obtain the silicon-oxygen-carbon electrode material. The specific invention content is as follows:

[0004] In a first aspect, the present invention provides a method for preparing a silicon-oxygen-carbon electrode material, comprising:

[0005] Under stirring conditions, the template is immersed in a silicon source solution at a temperature of 160 to 250° C. and reacted for 0.2 to 1 hour. Carbon nanotubes or fiber materials are further added and the reaction is continued for 2.8 to 24 hours. The resultant material is filtered, dried, and calcined to obtain a composite material of all-silicon nanosheets and carbon materials. The mass of the carbon nanotubes or fiber materials accounts for 0.5 to 1% of the mass of the all-silicon nanosheets. The pore diameter of the all-silicon nanosheets is 0.5 to 2 nm.

[0006] The composite material is placed in an alkaline solution of phenolic resin, stirred and solidified, and then crushed to obtain silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm;

[0007] The silicon-oxygen-carbon particles are etched with water vapor or CO2 at 800-1000°C for 3-24 hours, and then heat-treated in an inert gas atmosphere at 1500-2500°C for 3-24 hours to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5-2 nm.

[0008] Optionally, the silicon source is one or more of sodium silicate, ethyl orthosilicate, silicic acid and silicon oxide.

[0009] Optionally, the template is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, triethylamine and alkyldiamine.

[0010] Optionally, the alkaline agent is one or both of urea and sodium hydroxide; the amount of the alkaline agent is 110-130% of the silicon source.

[0011] Optionally, when carbon nanotubes are added, the calcination temperature is 400-800°C.

[0012] Optionally, the alkaline solution of the phenolic resin is a sodium solution or an ammonia solution.

[0013] Optionally, the etching is performed in a rotating bed or a fluidized bed.

[0014] Optionally, the pressure in the rotating bed or fluidized bed is 0.1-1 MPa.

[0015] Optionally, the gas in the inert gas atmosphere is Ar and / or He.

[0016] In a second aspect, the present invention provides a silicon-oxygen-carbon electrode material obtained by the preparation method described in the first aspect, wherein the silicon-oxygen-carbon electrode material is a three-dimensional silicon-oxygen-carbon nanosheet with a pore diameter of 0.5 to 2 nm.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention provides a method for preparing a silicon-oxygen-carbon electrode material, which comprises the following steps: impregnating a template agent into a silicon source solution, then adding carbon nanotubes or fiber materials, filtering, drying, and calcining to obtain a composite material of carbon material and all-silicon nanosheets; then adding the composite material into an alkaline solution of phenolic resin for carbonization and pulverization to obtain silicon-oxygen-carbon particles; and etching and heat-treating the silicon-oxygen-carbon particles to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5 to 2 nm. Conventional micron-sized spherical reaction precursors (such as SiO xDue to the particle size distribution, the reaction occurs at varying depths, resulting in poor product consistency. In contrast, all-silicon nanosheets, with their relatively uniform pore structure and nanometer-scale dimensions, react more readily as precursors to produce silicon-oxygen-carbon electrode materials. The resulting silicon-oxygen-carbon electrode material exhibits excellent product consistency and spatial uniformity, resisting damage due to volume expansion, and extending its service life by 2-3 times. Furthermore, the high mechanical strength of the silicon-oxygen-carbon particles obtained by carbonizing a composite material composed of nanoscale all-silicon nanosheets and carbon material in a phenolic resin allows for large-scale production of silicon-oxygen-carbon electrode materials using a fluidized bed, reducing costs by 30-50%. Furthermore, the presence of uniform pores allows for microscopically uniform release of the volume expansion caused by lithium intercalation into the silicon-oxygen-carbon electrode material, allowing the silicon-oxygen-carbon electrode material to be present in very large particles. Compared to nanoscale electrode materials, large particles of silicon-oxygen-carbon electrode material are easier to slurry, resulting in a 20-30% higher electrode sheet density, which is beneficial for the production of high-quality, high-energy-density devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A flow chart of a method for preparing a silicon-oxygen-carbon electrode material provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product that is identical or similar to the present invention and is obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work fall within the scope of protection of the present invention.

[0022] Where specific experimental steps or conditions are not specified in the examples, the conventional experimental steps or conditions described in the prior art in the art may be used. Reagents and other instruments used, for which the manufacturer is not specified, are commercially available conventional reagent products. Furthermore, the accompanying drawings are merely schematic illustrations of embodiments of the present invention and are not necessarily drawn to scale. Identical reference numerals in the figures denote identical or similar parts, and their repeated descriptions will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0023] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0024] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Based on the existing technology, spherical reaction precursors are generally used in the preparation of silicon-oxygen-carbon electrode materials, which leads to uneven reaction depth and poor product consistency. In addition, the size of the reaction precursors is mostly micron-sized and the reaction activity is weak. During the long-term lithium intercalation and lithium deintercalation process, the silicon-oxygen-carbon electrode materials obtained by conventional preparation methods have lattice expansion and contraction, which will lead to problems such as carbon layer peeling. The present invention proposes a method for preparing silicon-oxygen-carbon electrode materials using all-silicon nanosheets as reaction precursors, wherein a silicon source is immersed in a template solution to obtain all-silicon nanosheets; then carbon nanotubes or fiber materials are added, and after filtering, drying and calcining, a composite material of carbon material and all-silicon nanosheets is obtained; the composite material is then added to an alkaline solution of phenolic resin for carbonization and crushing to obtain silicon-oxygen-carbon particles; the silicon-oxygen-carbon particles are then etched and heat-treated to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5 to 2 nm. This silicon-oxygen-carbon electrode material has excellent product consistency and spatial uniformity, greatly improved service life, and can be prepared in large quantities through a fluidized bed, significantly reducing costs. In addition, this silicon-oxygen-carbon electrode material can exist in very large particles, making it easier to slurry. The compaction density of the prepared electrode is 20-30% higher, and it has extremely high application prospects in the field of preparing silicon-oxygen-carbon electrode materials.

[0026] The specific implementation methods are as follows:

[0027] In a first aspect, the present invention provides a method for preparing a silicon oxygen carbon electrode material. Figure 1 The flow chart of the preparation method of the silicon oxygen carbon electrode material provided by the embodiment of the present invention is shown as follows: Figure 1 As shown, the preparation method comprises:

[0028] Under stirring conditions, the template agent is immersed in a silicon source solution at a temperature of 160-250°C, an alkaline agent is added, and the reaction is carried out for 0.2-1 hour. Then, carbon nanotubes or fiber materials are further added, and the reaction is continued for 2.8-24 hours. The resultant material is filtered, dried, and calcined to obtain a composite material of all-silicon nanosheets and carbon materials. The mass of the carbon nanotubes or fiber materials accounts for 0.5-1% of the all-silicon nanosheets. The pore diameter of the all-silicon nanosheets is 0.5-2 nm.

[0029] In a specific implementation, the template is immersed in a silicon source solution at a temperature of 160-250°C under stirring conditions, an alkaline agent is added, and the reaction is carried out for 0.2-1h. The carbon nanotubes or fiber material is added to the solution in a monodispersed form under stirring. The reaction is continued for 2.8-24h under the condition of self-balanced pressure. After filtering, drying and calcining, a composite material of all-silicon nanosheets and carbon material is obtained; the mass of the carbon nanotubes or fiber material accounts for 0.5-1% of the all-silicon nanosheets; the pore diameter of the all-silicon nanosheets is 0.5-1%. The particle size is 0.5 to 2 nm; the silicon source is one or more of sodium silicate, tetraethyl orthosilicate, silicic acid, and silicon oxide; the template is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, triethylamine, and alkyldiamine; the alkaline agent is one or both of urea and sodium hydroxide; the amount of the alkaline agent is 110 to 130% of the silicon source; when carbon nanotubes are added, the calcination temperature is 400 to 700°C; when fiber materials are added, the calcination temperature is 400 to 800°C. Self-balancing pressure, i.e., in a sealed environment, the sealing pressure corresponding to the temperature, material properties, and reactant loading of the reaction system is maintained, without the application of additional pressure. The advantage of maintaining self-balancing pressure in the reaction system is that there is no need for deliberate pressure control to maintain the smooth progress of the reaction, resulting in simple equipment and low energy consumption and investment costs.

[0030] The composite material is placed in an alkaline solution of phenolic resin, stirred and solidified, and then crushed to obtain silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm;

[0031] In a specific implementation, the composite material is placed in an alkaline solution of phenolic resin, stirred until solidified, and crushed to obtain carbonized silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm; the alkaline solution of phenolic resin is a sodium solution or an ammonia solution;

[0032] The silicon-oxygen-carbon particles are etched with water vapor or CO2 at 800-1000°C for 3-24 hours, and then heat-treated in an inert gas atmosphere at 1500-2500°C for 3-24 hours to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5-2 nm.

[0033] In a specific implementation, the silicon-oxygen-carbon particles are etched with water vapor or CO2 in a rotating bed or fluidized bed for 3 to 24 hours at a temperature of 800 to 1000°C and a pressure of 0.1 to 1 MPa to activate them. The particles are then heat treated in an atmosphere of inert gas, Ar and / or He, at a temperature of 1500 to 2500°C for 3 to 24 hours to obtain a silicon-oxygen-carbon electrode material with pore diameters of 0.5 to 2 nm. The microstructure of this silicon-oxygen-carbon electrode material consists of three-dimensional silicon-oxygen-carbon nanosheets rich in pores with diameters of 0.5 to 2 nm. The carbon and silicon-oxygen elements are uniformly distributed in space, and the macroscopic particle size can be adjusted as needed.

[0034] The present invention provides a method for preparing a silicon-oxygen-carbon electrode material. The method involves impregnating a silicon source in a template solution, then adding carbon nanotubes or fiber materials. The mixture is filtered, dried, and calcined to obtain a composite material composed of carbon material and all-silicon nanosheets. The composite material is then carbonized and pulverized in an alkaline solution of phenolic resin to obtain silicon-oxygen-carbon particles. The particles are then etched and heat-treated to produce a silicon-oxygen-carbon electrode material with pore diameters of 0.5 to 2 nm. Because all-silicon nanosheets have a relatively uniform pore structure and are nanometer-sized, they react more readily as precursors to produce the silicon-oxygen-carbon electrode material. The resulting silicon-oxygen-carbon electrode material exhibits excellent product consistency and spatial uniformity, extending its service life by 2-3 times. Furthermore, due to the high mechanical strength of the silicon-oxygen-carbon particles formed by the reaction of the precursors, the silicon-oxygen-carbon electrode material can be mass-produced using a fluidized bed, reducing costs by 30-50%. Furthermore, the silicon-oxygen-carbon electrode material can be produced in very large particles, making slurrying easier, resulting in a 20-30% higher compaction density for the resulting electrode.

[0035] In a second aspect, the present invention provides a silicon-oxygen-carbon electrode material obtained by the preparation method described in the first aspect, wherein the silicon-oxygen-carbon electrode material is a three-dimensional silicon-oxygen-carbon nanosheet with a pore diameter of 0.5 to 2 nm.

[0036] In order to enable those skilled in the art to more clearly understand the present invention, the preparation method and application of the silicon oxygen carbon electrode material of the present invention are described in detail through the following examples.

[0037] Example 1

[0038] (1) Under stirring conditions, tetraethylammonium hydroxide is immersed in a sodium silicate solution at a temperature of 180°C, urea and sodium hydroxide are added (the molar fraction of urea is 70% and the molar fraction of sodium hydroxide is 30%), and after reacting for 0.5h, fiber material (plant fiber) is added to the solution in a monodispersed form under stirring, and the reaction is continued for 11.5h under the condition of self-balanced pressure. After filtering, drying, and calcining at 600°C, a composite material of all-silicon nanosheets and carbon material is obtained; the molar fraction of the alkaline agent is 110% of the sodium silicate; the mass of the added fiber material accounts for 1% of the all-silicon nanosheets; the pore diameter of the all-silicon nanosheets is 0.5-2nm;

[0039] (2) placing the composite material into an alkaline solution (ammonia solution) of phenolic resin, stirring until solidified, and crushing to obtain carbonized silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm;

[0040] (3) The silicon-oxygen-carbon particles are etched in a fluidized bed at a temperature of 800°C and a pressure of 1 MPa for 4 hours using water vapor to activate and etch pores. The particles are then heat treated at 1500°C in an atmosphere of inert gas He for 24 hours to obtain a silicon-oxygen-carbon electrode material having a pore diameter of 0.5 to 2 nm. The microstructure of the silicon-oxygen-carbon electrode material is rich in three-dimensional silicon-oxygen-carbon nanosheets with pore diameters of 0.5 to 2 nm. The carbon and silicon-oxygen elements are uniformly distributed in space, and the macroscopic particle size can be adjusted as required.

[0041] Example 2

[0042] (1) Under stirring conditions, tetrapropylammonium hydroxide is immersed in a mixed solution of silicon oxide and tetraethyl orthosilicate (the mass fraction of silicon oxide is 95% and the mass fraction of tetraethyl orthosilicate is 5%) at a temperature of 250°C, sodium hydroxide is added, and after reacting for 1 hour, carbon nanotubes are added to the solution in a monodispersed form under stirring. Under the condition of self-balanced pressure, the reaction is continued for 23 hours, and then filtered, dried, and calcined at 650°C to obtain a composite material of all-silicon nanosheets and carbon material; the amount of the alkaline agent is 115% of the total amount of silicon oxide and tetraethyl orthosilicate; the mass of the added carbon nanotubes accounts for 0.5% of the all-silicon nanosheets; the pore diameter of the all-silicon nanosheets is 0.5-2 nm;

[0043] (2) placing the composite material into an alkaline solution (sodium type solution) of phenolic resin, stirring until solidified, and crushing to obtain carbonized silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm;

[0044] (3) The silicon-oxygen-carbon particles were etched in a fluidized bed at a temperature of 1000°C and a pressure of 0.1 MPa for 6 hours using CO2 to activate and etch out pores. The particles were then heat treated at 2500°C in an atmosphere of inert Ar for 3 hours to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5 to 2 nm. The microstructure of the silicon-oxygen-carbon electrode material is rich in three-dimensional silicon-oxygen-carbon nanosheets with pore diameters of 0.5 to 2 nm. The carbon and silicon-oxygen elements are uniformly distributed in space, and the macroscopic particle size can be adjusted as required.

[0045] Example 3

[0046] (1) Under stirring conditions, tetraethylammonium hydroxide and triethylamine (the mass fraction of tetraethylammonium hydroxide is 50%, and the mass fraction of triethylamine is 50%) are immersed in a silicic acid solution at a temperature of 160°C, and urea and sodium hydroxide (the mass fraction of urea is 10%, and the mass fraction of sodium hydroxide is 90%) are added. After reacting for 0.6 hours, carbon nanotubes are added to the solution in a monodispersed form under stirring. Under the condition of self-balanced pressure, the reaction is continued for 23.4 hours, and then filtered, dried, and calcined at 550°C to obtain a composite material of all-silicon nanosheets and carbon material; the mass fraction of the alkaline agent is 125% of the silicic acid; the mass of the added carbon nanotubes accounts for 0.8% of the all-silicon nanosheets; the pore diameter of the all-silicon nanosheets is 0.5-2 nm;

[0047] (2) placing the composite material into an alkaline solution (sodium type solution) of phenolic resin, stirring until solidified, and crushing to obtain carbonized silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm;

[0048] (3) At a temperature of 900°C and a pressure of 0.5 MPa, the silicon-oxygen-carbon particles were etched in a rotating bed for 6 hours using water vapor and CO2 (the molar fraction of water vapor was 40% and the molar fraction of sodium hydroxide was 60%) to activate and etch out pores; then, the particles were heat treated in an atmosphere of inert gases Ar and He (the molar fraction of Ar was 40% and the molar fraction of He was 60%) at 1800°C for 10 hours to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5 to 2 nm. The microscopic unit structure of the silicon-oxygen-carbon electrode material is rich in three-dimensional silicon-oxygen-carbon nanosheets with a pore diameter of 0.5 to 2 nm. The carbon and silicon-oxygen elements are uniformly distributed in space, and the macroscopic particle size can be adjusted as required.

[0049] Example 4

[0050] (1) Under stirring conditions, hexamethylenediamine and isopropylamine (the mass fraction of hexamethylenediamine is 80% and the mass fraction of isopropylamine is 20%) are immersed in a sodium silicate solution at a temperature of 180°C, sodium hydroxide is added, and the reaction is carried out for 0.2 hours. Then, the fiber material is added to the solution in a monodispersed form under stirring, and the reaction is continued for 2.8 hours under the condition of self-balanced pressure. After filtering, drying, and calcining at 700°C, a composite material of all-silicon nanosheets and carbon material is obtained; the amount of the alkaline agent is 130% of the sodium silicate; the mass of the fiber material added accounts for 0.75% of the all-silicon nanosheets; the pore diameter of the all-silicon nanosheets is 0.5-2 nm;

[0051] (2) placing the composite material into an alkaline solution (ammonia solution) of phenolic resin, stirring until solidified, and crushing to obtain carbonized silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm;

[0052] (3) At a temperature of 950°C and a pressure of 0.6 MPa, the silicon-oxygen-carbon particles were etched in a fluidized bed for 4 hours using water vapor and CO2 (the molar fraction of water vapor was 60% and the molar fraction of sodium hydroxide was 40%) to activate and etch out pores; then, a heat treatment was performed for 12 hours in an atmosphere of inert gases Ar and He (the molar fraction of Ar was 80% and the molar fraction of He was 20%) at 2200°C to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5 to 2 nm. The microscopic unit structure of the silicon-oxygen-carbon electrode material is rich in three-dimensional silicon-oxygen-carbon nanosheets with a pore diameter of 0.5 to 2 nm. The carbon and silicon-oxygen elements are uniformly distributed in space, and the macroscopic particle size can be adjusted as required.

[0053] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0054] For simplicity of description, the method embodiments are described as a series of actions. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, as certain steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also be aware that the embodiments described in this specification are preferred embodiments, and the actions and components involved are not necessarily required for the present invention.

[0055] The above is a detailed introduction to the preparation method and application of a silicon oxygen carbon electrode material provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for preparing a silicon-oxygen-carbon electrode material, characterized in that: include: Under stirring conditions, the template is immersed in a silicon source solution at a temperature of 160-250°C, an alkaline agent is added, and the reaction is carried out for 0.2-1 hour. Then, carbon nanotubes or fiber materials are further added, and the reaction is continued for 2.8-24 hours. The resultant material is filtered, dried, and calcined to obtain a composite material of all-silicon nanosheets and carbon materials. The mass of the carbon nanotubes or fiber materials accounts for 0.5-1% of the composite material. The pore diameter of the all-silicon nanosheets is 0.5-2 nm. The composite material is placed in an alkaline solution of phenolic resin, stirred and solidified, and then crushed to obtain silicon-oxygen-carbon particles with a diameter of 0.01 to 0.1 mm; The silicon-oxygen-carbon particles are etched with water vapor or CO2 at 800-1000°C for 3-24 hours, and then heat-treated in an inert gas atmosphere at 1500-2500°C for 3-24 hours to obtain a silicon-oxygen-carbon electrode material with a pore diameter of 0.5-2 nm; The template agent is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, triethylamine and alkyldiamine.

2. The preparation method according to claim 1, characterized in that The silicon source is one or more of sodium silicate, ethyl orthosilicate, silicic acid and silicon oxide.

3. The preparation method according to claim 1, characterized in that The alkaline agent is one or both of urea and sodium hydroxide; the amount of the alkaline agent is 110-130% of the silicon source.

4. The preparation method according to claim 1, characterized in that The calcination temperature is 400-800°C.

5. The preparation method according to claim 1, characterized in that The alkaline solution of the phenolic resin is a sodium type solution or an ammonia type solution.

6. The preparation method according to claim 1, characterized in that The etching is performed in a rotating bed or a fluidized bed.

7. The preparation method according to claim 6, characterized in that The pressure in the rotating bed or fluidized bed is 0.1-1 MPa.

8. The preparation method according to claim 1, characterized in that The gas in the inert gas atmosphere is Ar and / or He.

9. A silicon-oxygen-carbon electrode material obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The silicon-oxygen-carbon electrode material is a three-dimensional silicon-oxygen-carbon nanosheet with a pore diameter of 0.5 to 2 nm.

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