A method for preparing porous carbon-supported nano-silicon material

Abstract

The present invention belongs to the technical field of lithium-ion battery materials, and in particular, is a method for preparing a porous carbon-loaded nano-silicon material, comprising: step one, template selection, selecting nano-silicon dioxide particles as the template material of the present invention; step two, preparation of phenolic resin, mixing phenol and formaldehyde as reactants with the silicon dioxide template, and performing a hydrothermal reaction at a certain temperature and pressure to form a polymer; step three, a carbonization process, carbonizing the polymer obtained by hydrothermal synthesis under the protection of a nitrogen atmosphere to obtain a porous carbon loaded with silicon dioxide. The preparation method of the porous carbon-loaded nano-silicon material is simple, low-cost, and easy to mass-produce; the prepared porous carbon-loaded nano-silicon material has a high specific surface area, which is conducive to improving the electrochemical activity of the material.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery materials, and in particular to a method for preparing a porous carbon-loaded nano-silicon material. Background Art

[0002] With the rapid development of renewable energy, the demand for efficient energy storage and conversion materials is growing; porous carbon has become an ideal carrier material due to its high specific surface area, good conductivity and chemical stability; nanosilicon, as the negative electrode material of lithium-ion batteries, has high theoretical capacity and low potential platform, but its poor cycle stability and volume expansion problems limit its application; loading nanosilicon on porous carbon can effectively improve its structural stability and electrochemical performance.

[0003] The existing method for preparing porous carbon-loaded nanosilicon is to first prepare porous carbon and then use silane to deposit nanosilicon on the porous carbon. This method is cumbersome, costly, and has certain safety risks. Therefore, developing a simple, efficient, and low-cost method for preparing porous carbon-loaded nanosilicon has important practical application value. Summary of the invention

[0004] Based on the existing technical problems, the present invention proposes a method for preparing porous carbon-loaded nano-silicon material.

[0005] The present invention provides a method for preparing a porous carbon-supported nano-silicon material, comprising:

[0006] Step 1: template selection, selecting nano-silicon dioxide particles as the template material of the present invention;

[0007] Step 2, preparation of phenolic resin, phenol and formaldehyde as reactants, mixed with silica template, and hydrothermally reacted at a certain temperature and pressure to form a polymer;

[0008] Step 3, carbonization process, carbonizing the polymer obtained by hydrothermal synthesis under nitrogen atmosphere protection to obtain porous carbon loaded with silica;

[0009] Step 4: magnesium thermal reduction, wherein the molten metal magnesium is fully mixed with the porous carbon, and the silicon dioxide is reduced to nano-silicon by magnesium thermal reduction reaction under nitrogen protection;

[0010] Step five, acid washing and water washing, the material obtained in step four is subjected to multiple acid washing, water washing and drying to obtain the final porous carbon-supported nano-silicon material.

[0011] Preferably, the size of the nano-silicon dioxide particles in step 1 is ≤1000 nm.

[0012] Preferably, in step 2, the phenols in the phenolic resin are one or more of phenol, resorcinol, hydroquinone and phloroglucinol.

[0013] Preferably, in the step 2, the aldehyde in the phenolic resin is one or more of formaldehyde, terephthalaldehyde, isophthalaldehyde, and trimesaldehyde.

[0014] Preferably, in the step 2, the molar ratio of phenol to formaldehyde reactants in the preparation process of the phenolic resin is 0.1:1-5:1.

[0015] Preferably, in the step 2, the mass ratio of nano-silicon dioxide to phenol in the preparation process of the phenolic resin is 0.1:1-3:1.

[0016] Preferably, in the step 2, the hydrothermal temperature range of the phenolic resin preparation process is 50-300° C. and the pressure is 1-3 MPa.

[0017] Preferably, in the step three, the carbonization temperature in the carbonization process is 600-1200° C., and the carbonization time is 2-12 hours.

[0018] Preferably, in step 4, the temperature of the magnesium thermal reduction reaction is 500-700° C., and the reaction time is 1 to 3 hours.

[0019] Preferably, in step five, the acid in the pickling and water washing is one of dilute hydrochloric acid, dilute nitric acid and dilute sulfuric acid, and the pH value of the solution after the final water washing is between 5 and 9.

[0020] The beneficial effects of the present invention are:

[0021] 1. The preparation method of the present invention is simple, low-cost, and easy to mass-produce; the prepared porous carbon-loaded nano-silicon material has a high specific surface area, which is beneficial to improving the electrochemical activity of the material.

[0022] 2. The nano-silicon load prepared by the present invention can effectively alleviate its volume expansion during the charge and discharge process and improve the cycle stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a method for preparing porous carbon-loaded nano-silicon material proposed in the present invention. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] Reference Figure 1 , a method for preparing a porous carbon-supported nano-silicon material, comprising:

[0026] Step 1: template selection, selecting nano-silicon dioxide particles as the template material of the present invention, wherein the size of the nano-silicon dioxide particles is ≤1000 nm;

[0027] Step 2, preparation of phenolic resin, phenols and formaldehydes as reactants, mixed with silica template, and hydrothermally reacted at a certain temperature and pressure to form a polymer; the phenols are one or more of phenol, resorcinol, hydroquinone, and phloroglucinol, the aldehydes are one or more of formaldehyde, terephthalaldehyde, isophthalaldehyde, and trimesic acid, the molar ratio of phenols to formaldehyde reactants is 0.1:1-5:1, the mass ratio of nano-silica to phenols is 0.1:1-3:1, the hydrothermal temperature range is 50-300°C, and the pressure is 1-3MPa;

[0028] Step 3, carbonization process, carbonizing the polymer obtained by hydrothermal synthesis under nitrogen atmosphere protection to obtain porous carbon loaded with silica, the carbonization temperature is 600-1200° C., and the carbonization time is 2-12 hours;

[0029] Step 4: magnesium thermal reduction, fully mixing the molten metal magnesium and the porous carbon, and reducing the silicon dioxide to nano-silicon by magnesium thermal reduction reaction under nitrogen protection, the magnesium thermal reduction reaction temperature is 500-700°C, and the reaction time is 1-3h;

[0030] Step 5, acid washing and water washing, the material obtained in step 4 is subjected to multiple acid washing, water washing and drying to obtain the final porous carbon-supported nano-silicon material, the acid washing is one of dilute hydrochloric acid, dilute nitric acid and dilute sulfuric acid, and the pH value of the solution after the final water washing is between 5-9.

[0031] The preparation method of the invention is simple, low-cost and easy to mass-produce; the prepared porous carbon-loaded nano-silicon material has a high specific surface area, which is beneficial to improving the electrochemical activity of the material.

[0032] The nano-silicon load prepared by the present invention can effectively alleviate its volume expansion during the charging and discharging process and improve the cycle stability of the material.

[0033] Embodiment 1

[0034] Prepare silica templates with a size of 100-200 nm.

[0035] Resorcinol and terephthalaldehyde were mixed in a molar ratio of 1:1 and added into a solution containing a silica template.

[0036] The hydrothermal reaction was carried out at 180°C for 24 hours to obtain a polymer.

[0037] The polymer was carbonized at 900 °C for 2 h to obtain silica-loaded porous carbon.

[0038] Metallic magnesium and porous carbon were mixed in a mass ratio of 3:1, heated to 650°C under argon protection, and maintained for 1 hour to complete the magnesium thermal reduction reaction.

[0039] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing porous carbon-supported nano-silicon material, characterized in that: include: Step 1: template selection, selecting nano-silica particles as template material; Step 2, preparation of phenolic resin, phenol and formaldehyde as reactants, mixed with silica template, and hydrothermally reacted at a certain temperature and pressure to form a polymer; Step 3, carbonization process, carbonizing the polymer obtained by hydrothermal synthesis under nitrogen atmosphere protection to obtain porous carbon loaded with silica; Step 4: magnesium thermal reduction, wherein the molten metal magnesium is fully mixed with the porous carbon, and the silicon dioxide is reduced to nano-silicon by magnesium thermal reduction reaction under nitrogen protection; Step 5, acid washing and water washing, the material obtained in step 4 is subjected to multiple acid washing, water washing and drying to obtain the final porous carbon-supported nano-silicon material; In the step 2, the phenol in the phenolic resin is one or more of phenol, resorcinol, hydroquinone, and phloroglucinol; In the step 2, the aldehyde in the phenolic resin is one or more of formaldehyde, terephthalaldehyde, isophthalaldehyde, and trimesaldehyde; In the step 2, the molar ratio of phenol and formaldehyde reactants in the preparation process of the phenolic resin is 0.1:1-5:1; In the step 2, the mass ratio of nano-silicon dioxide to phenol in the preparation process of the phenolic resin is 0.1:1-3:

1.

2. The method for preparing a porous carbon-supported nano-silicon material according to claim 1, characterized in that: The size of the nano silicon dioxide particles in step 1 is ≤1000nm.

3. The method for preparing a porous carbon-supported nano-silicon material according to claim 1, characterized in that: In the step 2, the hydrothermal temperature range of the phenolic resin preparation process is 50-300° C. and the pressure is 1-3 MPa.

4. The method for preparing a porous carbon-supported nano-silicon material according to claim 1, characterized in that: In the step three, the carbonization temperature during the carbonization process is 600-1200° C., and the carbonization time is 2-12 hours.

5. The method for preparing a porous carbon-supported nano-silicon material according to claim 1, characterized in that: In the step 4, the temperature of the magnesium thermal reduction reaction is 500-700° C., and the reaction time is 1 to 3 hours.

6. The method for preparing a porous carbon-supported nano-silicon material according to claim 1, characterized in that: In the step 5, the acid in the pickling and water washing is one of dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid, and the pH value of the solution after the final water washing is between 5 and 9.

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