Surface coating method of carbon material with high specific surface area

Abstract

The invention discloses a surface coating method of a high-specific-surface carbon material, and belongs to the technical field of material engineering.According to the method, the characteristic that the high-specific-surface carbon material reaches adsorption equilibrium in a vapor pressure environment formed by a specific coating material is utilized, the coating material is effectively introduced into the surface of the high-specific-surface carbon material and an internal pore structure of the high-specific-surface carbon material, and then the high-specific-surface carbon material is prepared. And the adsorbed coating material is cured by a rapid cooling method, so that a uniform and stable coating layer is formed on the surface of the high-specific-surface carbon material and in an internal pore structure.

Description

Technical Field

[0001] The invention belongs to the technical field of material engineering, and in particular relates to a surface coating method for a high specific surface carbon material. Background Art

[0002] High specific surface carbon materials, such as activated carbon, template carbon, carbon aerogel, carbon nanotubes and graphene, have shown great application potential in many high-tech fields such as adsorption separation, catalytic reaction, energy storage and conversion due to their unique porous structure and excellent specific surface area. Specifically, in the field of adsorption separation, these materials effectively improve the efficiency of gas purification and wastewater treatment; in catalytic reactions, their multi-active site characteristics significantly enhance the reaction rate and selectivity. In addition, in the field of energy storage, the application of high specific surface carbon materials has significantly improved the energy density and charge and discharge performance of lithium-ion batteries and supercapacitors, and has also played an important role in key areas such as hydrogen storage and carbon dioxide capture and conversion.

[0003] However, in actual application scenarios, high specific surface carbon materials still generally have significant problems such as insufficient surface active sites, poor stability and short life, which seriously restrict the full performance of their performance. In view of these key constraints, it is particularly urgent and important to implement surface coating modification of high specific surface carbon materials. For example: with the help of advanced surface modification technology, it is possible to effectively repair defects on the surface of the material, remove harmful functional groups, and build a protective layer, thereby significantly enhancing the stability of the material under harsh environmental conditions such as high temperature, strong acid and alkali, and high voltage, and effectively extending the service life of the material; at the same time, by increasing the active sites of the material and introducing specific groups or structures, the conductivity, wettability, adsorption and catalytic properties of the material are significantly improved, thereby significantly improving the reaction efficiency and selectivity of the material. In summary, surface coating modification is a key technical means to meet the application challenges of high specific surface carbon materials and improve their performance.

[0004] At present, the surface coating modification of high specific surface carbon materials mainly relies on a variety of technical means such as liquid phase method, solid phase method, sol-gel method, chemical vapor deposition, laser pulse deposition and atomic layer deposition. These methods effectively increase the active sites of the material, improve stability, and optimize other related properties to a certain extent. However, these traditional methods also have significant limitations. Specifically, the liquid phase method and the solid phase method are prone to introduce impurities during the operation process, which significantly affects the purity and of the coating layer. It is difficult to form a uniform coating layer when the coating content is low, which in turn affects the application effect of the material; although the sol-gel method has good controllability, its preparation process is complicated, and the gel is prone to cracks when drying, resulting in a decrease in the coating quality; although chemical vapor deposition, laser pulse deposition and atomic layer deposition can achieve high-quality coating layers, the equipment cost is high and the deposition rate is relatively slow, which restricts its application in large-scale production. Therefore, the development of simple, efficient, high-purity and environmentally friendly new surface coating methods is crucial to further improve the performance of high specific surface carbon materials. Summary of the invention

[0005] In view of the shortcomings of the existing high specific surface carbon material surface coating technology, the present invention proposes a surface coating method based on the adsorption equilibrium principle. The method utilizes the characteristic that the high specific surface carbon material reaches adsorption equilibrium under the vapor pressure environment formed by a specific coating material, effectively introduces the coating material into the surface of the high specific surface carbon material and its internal pore structure, and then solidifies the adsorbed coating material through a rapid cooling method, thereby forming a uniform and stable coating layer on the surface of the high specific surface carbon material and its internal pore structure.

[0006] The present invention is achieved through the following technical solutions:

[0007] A surface coating method for a high specific surface carbon material comprises the following steps:

[0008] Step 1, placing a high specific surface carbon material and a surface coating material in a vacuum chamber that is interconnected;

[0009] Step 2, treating the high specific surface carbon material by vacuuming at high temperature, so that the substances adsorbed inside the high specific surface carbon material are discharged in the form of gas;

[0010] Step 3, heating the surface coating material so that the surface coating material forms an atmosphere environment with a specific vapor pressure at a high temperature, diffuses around the high specific surface carbon material, and enters the surface and pore structure of the high specific surface carbon material under the driving condition of spontaneous adsorption;

[0011] Step 4, maintaining the treatment temperature of step 3, so that the high specific surface carbon material reaches adsorption equilibrium under the condition of a specific vapor pressure, and the coating material is evenly distributed on the surface and pore structure of the high specific surface carbon material;

[0012] Step 5: Rapidly lower the temperature to room temperature, so that the gaseous coating product is quickly and evenly fixed on the surface and pore structure of the high specific surface carbon material, forming a good surface and internal coating state, and obtaining the coated high specific surface carbon material.

[0013] In the above technical solution, in step 1, the surface coating material can form a certain vapor pressure at high temperature and does not react with carbon at this temperature.

[0014] In the above technical solution, in step 1, the surface coating material is preferably LiF, Li2O, Li3PO4, Al2O3, B2O3, SiO2 or TiO2.

[0015] In the above technical solution, in step 2, the high temperature is 100°C-2500°C, and the processing time is 0-120h.

[0016] In the above technical solution, in step 3, the high temperature is 100°C-2500°C.

[0017] In the above technical solution, in step 4, the holding time is 2-120 hours.

[0018] In the above technical solution, the method further comprises subjecting the coated high specific surface carbon material to multiple coating treatments to form a high specific surface carbon material coated with multiple materials.

[0019] Beneficial effects:

[0020] 1. Directly using coating materials to treat high specific surface carbon materials avoids the problem of various impurities introduced by conventional coating methods, and no additional washing and purification steps are required, so a high-purity coating layer can be obtained;

[0021] 2. By controlling the heat treatment temperature in steps 3-4, the vapor pressure formed by the coating material around the high specific surface carbon material can be accurately controlled. Since there is a specific relationship between the adsorption process and the vapor pressure, the coating ratio and coating position of the coating material on the high specific surface carbon material can be accurately controlled by controlling the temperature, thereby greatly improving the controllability of the adsorption process;

[0022] 3. Due to the steam treatment method, on the one hand, it can improve the utilization efficiency of the coating material and form a uniform coating layer. On the other hand, it is very suitable for trace coating and achieves a good coating effect without affecting the original specific surface area and pore structure of the material;

[0023] 4. This method has good versatility and is suitable for a variety of coating materials that can form vapor pressure at high temperatures, as well as some coating materials that can be generated by gas phase reactions;

[0024] 5. The preparation process only includes two steps: vacuum and heat treatment, which is simple to operate and has low equipment requirements. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0026] Embodiment 1:

[0027] Take 1g of graphene, put it into a quartz tube crucible, and put it into a quartz tube containing 0.5g of LiF powder with a purity of 99.9%. Connect the quartz tube to a molecular pump, heat it to 200℃ under vacuum conditions, keep the vacuum state for 24 hours, and then weld and seal the quartz tube. Transfer the sealed quartz tube to a muffle furnace, control the heating temperature to 1047℃, at which time the vapor pressure of LiF is about 0.133Kpa, and keep it at this temperature for 12 hours to allow the activated carbon to reach adsorption equilibrium. After the time is up, quickly reduce the temperature of the quartz tube to below 1000℃, so that LiF is evenly attached to the surface of the activated carbon and the pore structure to form a uniform coating.

[0028] Embodiment 2:

[0029] Take 1g of CMK-3 template carbon, put it into a quartz tube crucible, and put it into a quartz tube containing 0.5g of Li3PO4 powder with a purity of 99.9%. Connect the quartz tube to a molecular pump, heat it to 827℃ under vacuum conditions, keep the vacuum state for 24 hours, and then weld and seal the quartz tube. Transfer the sealed quartz tube to a muffle furnace, control the heating temperature to 827℃, at which time the vapor pressure of Li3PO4 is about 0.74pa, and keep it at this temperature for 12 hours to allow the activated carbon to reach adsorption equilibrium. After the time is up, quickly reduce the temperature of the quartz tube to below 1000℃, so that Li3PO4 is evenly attached to the surface of the activated carbon and the pore structure to form a uniform coating.

[0030] Embodiment 3:

[0031] Take 5g of activated carbon, put it into a quartz tube crucible, and put it into a quartz tube containing 0.5g of 99.9% pure Li3PO4 powder. Connect the quartz tube to a molecular pump, heat it to 827℃ under vacuum conditions, keep the vacuum state for 24 hours, and then weld and seal the quartz tube. Transfer the sealed quartz tube to a muffle furnace, control the heating temperature to 827℃, at which time the vapor pressure of Li3PO4 is about 0.74pa, and keep it at this temperature for 12 hours to allow the activated carbon to reach adsorption equilibrium. After the time is up, quickly reduce the temperature of the quartz tube to below 1000℃, so that Li3PO4 is evenly attached to the surface of the activated carbon and the pore structure to form a uniform coating.

[0032] Then, the activated carbon material coated with Li3PO4 was taken out and transferred into a quartz tube containing 0.5g of LiF powder with a purity of 99.9%. The quartz tube was connected to a molecular pump and heated to 200°C under vacuum conditions. After maintaining the vacuum state for 24 hours, the quartz tube was welded and sealed. The sealed quartz tube was transferred to a muffle furnace and the heating temperature was controlled to 1047°C. At this time, the vapor pressure of LiF was about 0.133Kpa. It was kept at this temperature for 12 hours to allow the activated carbon to reach adsorption equilibrium. After the time is up, the temperature of the quartz tube was quickly reduced to below 1000°C, so that LiF was evenly attached to the surface of the activated carbon and the pore structure to form a uniform coating layer, and a high specific surface carbon material coated with LiF and Li3PO4 was obtained.

[0033] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for coating a surface of a high specific surface carbon material, characterized in that: The steps include: Step 1, placing a high specific surface carbon material and a surface coating material in a vacuum chamber that is interconnected; Step 2, treating the high specific surface carbon material by vacuuming at high temperature, so that the substances adsorbed inside the high specific surface carbon material are discharged in the form of gas; Step 3, heating the surface coating material so that the surface coating material forms an atmosphere environment with a specific vapor pressure at a high temperature, diffuses around the high specific surface carbon material, and enters the surface and pore structure of the high specific surface carbon material under the driving condition of spontaneous adsorption; Step 4, maintaining the treatment temperature of step 3, so that the high specific surface carbon material reaches adsorption equilibrium under the condition of a specific vapor pressure, and the coating material is evenly distributed on the surface and pore structure of the high specific surface carbon material; Step 5: Rapidly lower the temperature to room temperature, so that the gaseous coating product is quickly and evenly fixed on the surface and pore structure of the high specific surface carbon material, forming a good surface and internal coating state, and obtaining the coated high specific surface carbon material.

2. The surface coating method of a high specific surface carbon material according to claim 1, characterized in that: In step 1, the surface coating material can form a certain vapor pressure at a high temperature and does not react with carbon at the temperature.

3. The surface coating method of a high specific surface carbon material according to claim 2, characterized in that: In step 1, the surface coating material is LiF, Li2O, Li3PO4, Al2O3, B2O3, SiO2 or TiO2.

4. The surface coating method of a high specific surface carbon material according to claim 1, characterized in that: In step 2, the high temperature is 100° C.-2500° C., and the treatment time is 0-120 hours.

5. The surface coating method of a high specific surface carbon material according to claim 1, characterized in that: In step 3, the high temperature is 100°C-2500°C.

6. The surface coating method of a high specific surface carbon material according to claim 1, characterized in that: In step 4, the holding time is 2-120 hours.

7. The method for coating a surface of a high specific surface carbon material according to claim 1, characterized in that: The method further comprises subjecting the coated high specific surface carbon material to multiple coating treatments to form a high specific surface carbon material coated with multiple materials.