CN103882559B - High-ratio surface porous carbon fiber and preparation method thereof and application - Google Patents

Abstract

The invention discloses a kind of high-ratio surface carbon fiber and preparation method thereof.The method, comprises the steps: the spinning solution be made up of pore creating material, macromolecule and organic solvent to carry out carbonization pickling after spinning, obtains described high-ratio surface carbon fiber.The method tool has the following advantages: a) preparation is simple, and output is high, and cost is low; B) porous carbon fiber with high-ratio surface can be prepared by the method; C) this carbon fiber has micropore and meso-hole structure simultaneously.

Description

High specific surface porous carbon fiber and its preparation method and application

technical field

The invention relates to a carbon fiber and its preparation method and application, in particular to a high specific surface porous carbon fiber and its preparation method and application.

Background technique

Due to its unique structure and characteristics, carbon fibers are widely used as macromolecular absorption materials, supercapacitors, batteries, catalyst carriers, gas or liquid filtration, and field emission display materials. Electrospinning is a very simple and efficient method for preparing carbon fibers, and has attracted widespread attention due to its low cost. However, carbon fibers prepared by ordinary electrospinning are non-porous carbon fibers with low specific surface area, which greatly limits the application of carbon fibers. In response to this shortcoming, in recent years, high specific surface porous carbon fibers and their preparation have aroused widespread research interest and become a research and development hotspot.

The following problems still exist in the high specific surface porous carbon fibers and their preparation methods reported in the literature at present: the pore-forming process in the method is cumbersome and complicated, the cost is high, and it is difficult to realize industrial production; the above problems greatly limit the prepared porous carbon fibers. It is used as catalyst carrier, supercapacitor and lithium ion battery. Therefore, it is of great significance to develop a porous carbon fiber with superior performance and a simple and low-cost preparation method suitable for catalyst supports, supercapacitors, and lithium-ion batteries.

Contents of the invention

The object of the present invention is to overcome the defects of the above-mentioned prior art, and provide a kind of high specific surface porous carbon fiber suitable for use as catalyst carrier, supercapacitor, lithium ion battery and filter membrane with superior performance.

Another object of the present invention is to provide a simple, efficient and low-cost preparation method for the above-mentioned porous carbon fiber with high specific surface area.

Another object of the present invention is to provide the application of the above-mentioned porous carbon fiber with high specific surface area as catalyst carrier, supercapacitor, lithium ion battery and filter membrane.

The present invention adopts following technical scheme:

A kind of porous carbon fiber with high specific surface, its specific surface area is greater than 100m ² /g, and has micropore and mesopore structure at the same time, and the diameter of the carbon fiber is between 100nm-10μm.

According to the present invention, preferably, its specific surface area is greater than 300 m ² /g; more preferably, its specific surface area is greater than 600 m ² /g, still more preferably, its specific surface area is greater than 800 m ² /g.

According to the present invention, the diameter of the carbon fiber is preferably between 100 nm-1 μm.

According to the present invention, the porous carbon fiber with high specific surface area is prepared by a method comprising the steps of: carbonizing a spinning solution including a pore-forming agent, a macromolecule and an organic solvent after spinning, and obtaining the high-density porous carbon fiber after pickling and drying. Specific surface porous carbon fiber; wherein, the pore forming agent is selected from potassium sulfide.

According to the present invention, the polymer is selected from at least one of polyacrylonitrile, polyimide, pitch, polyvinyl alcohol, polyvinylpyrrolidone and phenolic resin.

According to the present invention, the number average molecular weight of the polyacrylonitrile is 50w-300w, preferably 150w.

According to the present invention, the number average molecular weight of the polyimide is 50w-300w, preferably 150w.

According to the present invention, the number average molecular weights of the asphalt and polyvinyl alcohol are both 50w-300w, preferably 150w.

According to the present invention, the number average molecular weight of the polyvinylpyrrolidone is 50w-300w, preferably 150w.

According to the present invention, the number average molecular weight of the phenolic resin is 50w-300w, preferably 150w.

The present invention also discloses the following technical solutions:

A method for preparing porous carbon fibers with a high specific surface, comprising the steps of: carbonizing a spinning solution including a pore-forming agent, a polymer and an organic solvent after spinning, and obtaining the porous carbon fibers with a high specific surface after pickling and drying; Wherein, the pore-forming agent is selected from potassium sulfide.

Different from the existing methods for preparing porous carbon fibers, the present invention uses potassium sulfide as a pore-forming agent in the method, instead of the existing alkali activation method, steam activation method and thermal decomposable copolymer pore-forming method, etc., and the preparation process is simple High-efficiency and low-cost, the prepared porous carbon fibers have high specific surface area and abundant micropore and mesopore structure.

According to the present invention, the specific surface area of the high specific surface porous carbon fiber is greater than 100m ² /g, and has both micropore and mesopore structure, and the diameter of the carbon fiber is between 100nm-10μm.

According to the present invention, preferably, its specific surface area is greater than 300 m ² /g; more preferably, its specific surface area is greater than 600 m ² /g, still more preferably, its specific surface area is greater than 800 m ² /g.

According to the present invention, the diameter of the carbon fiber is preferably between 100 nm-1 μm.

According to the present invention, the polymer in the above method is at least one selected from polyacrylonitrile, polyimide, asphalt, polyvinyl alcohol, polyvinylpyrrolidone and phenolic resin.

According to the present invention, the number average molecular weight of the polyacrylonitrile is 50w-300w, preferably 150w.

According to the present invention, the number average molecular weight of the polyimide is 50w-300w, preferably 150w.

According to the present invention, the number average molecular weights of the asphalt and polyvinyl alcohol are both 50w-300w, preferably 150w.

According to the present invention, the number average molecular weight of the polyvinylpyrrolidone is 50w-300w, preferably 150w.

According to the present invention, the number average molecular weight of the phenolic resin is 50w-300w, preferably 150w.

According to the present invention, the organic solvent in the above method is at least one selected from N,N-dimethylformamide, N-methylpyrrolidone and dimethylsulfoxide.

According to the present invention, the mass percentage of the pore-forming agent in the spinning solution is 1-10%, specifically 1% or 3% or 5% or 8%; the mass of the polymer in the spinning solution The percentage is 5-20%, specifically 8% or 10% or 15%.

According to the present invention, in the spinning step, the spinning method is electrospinning. The spinning process stretches, solidifies and fibrillates the polymer solution.

According to the present invention, in the electrospinning, the voltage is 10-35kV, specifically 25kV; the flow rate of the spinning solution is 0.5-5.0mL/h, specifically 1.5mL/h or 1mL/h; the temperature is 15-40 °C, specifically 15 °C or 30 °C or 15-30 °C; the collecting plate is aluminum foil; the distance between the needle tip and the aluminum foil is 5-50 cm, specifically 15 cm.

According to the invention, said carbonization step comprises successively preoxidation in air and high temperature carbonization in an inert atmosphere.

According to the present invention, in the pre-oxidation step, the temperature is 180-280°C, specifically 230°C or 260°C or 230-280°C or 180-230°C or 180-260°C; the time is 1-4 hours, specifically 2 hours; the atmosphere is an air atmosphere.

According to the present invention, in the high temperature carbonization step, the inert atmosphere is _N2 or Ar atmosphere.

According to the present invention, in the high-temperature carbonization step, the carbonization temperature is 600-1000°C, specifically 600°C or 900°C or 1000°C or 600-900°C or 600-1000°C or 900-1000°C; the heating rate is 1-10°C/min, specifically 4°C/min; carbonization time is 1-4 hours, specifically 2 hours.

In this process, when the carbonization temperature is higher than 600 °C, potassium sulfide activates the carbon fibers to form a microporous structure, and the formed high specific surface carbon fibers have both microporous and mesoporous structures.

According to the present invention, in the pickling step, the acid is selected from at least one of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid and nitric acid; the concentration of the acid is 0.1-12M, specifically 2M; the time is 0.5-4 hours, Specifically 2 hours. The purpose of pickling is to remove potassium sulfide inside the fiber.

The high specific surface porous carbon fiber prepared according to the above method also belongs to the protection scope of the present invention.

The present invention also discloses the following technical solutions:

A catalyst carrier, supercapacitor, lithium ion battery or filter membrane, which includes the above-mentioned high specific surface porous carbon fiber.

The application of the above-mentioned high specific surface porous carbon fiber is used as a catalyst carrier, a supercapacitor, a lithium ion battery or a filter membrane, etc.

Since the high specific surface porous carbon fiber provided by the present invention has a high specific surface and has both micropore and mesoporous structures, the high specific surface porous carbon fiber has a good advantage in mass transfer of ions. Therefore, the porous carbon fiber of the present invention is suitable for application in the preparation of supercapacitors, lithium ion batteries, catalyst supports or filter membranes.

The beneficial effects of the present invention are:

The carbon fiber of the present invention has a very high specific surface area and has both micropore and mesoporous structure, and is especially suitable for the application in the preparation of supercapacitors, lithium ion batteries, catalyst supports or filter membranes.

Compared with the existing high specific surface carbon fiber preparation method, the method provided by the invention has the following advantages:

a) The carbon fiber prepared by this method has a very high specific surface area, which is a porous carbon fiber with both micropore and mesoporous structure, which cannot be realized by the method of the prior art.

b) Different from the existing methods for preparing porous carbon fibers, the present invention introduces potassium sulfide as a pore-forming agent in the method, instead of the existing alkali activation method, steam activation method, and pyrolytic copolymer pore-forming method, etc., The preparation process is simple, efficient and low in cost, and the prepared porous carbon fiber has a high specific surface area and abundant micropore and mesopore structure.

Description of drawings

Fig. 1 is the nitrogen adsorption and desorption curve of the high specific surface porous carbon fiber prepared in Example 1.

FIG. 2 is a TEM electron microscope examination image of the high specific surface porous carbon fiber prepared in Example 1.

Fig. 3 is the nitrogen adsorption and desorption curve of the high specific surface porous carbon fiber prepared in Example 2.

FIG. 4 is a TEM electron microscope examination image of the high specific surface porous carbon fiber prepared in Example 2.

Fig. 5 is the nitrogen adsorption and desorption curve of the high specific surface porous carbon fiber prepared in Example 3.

FIG. 6 is a TEM electron microscope examination image of the high specific surface porous carbon fiber prepared in Example 3.

detailed description

The present invention is further described in detail below through the examples, but those skilled in the art understand that the examples of the present invention are not limitations to the scope of protection of the present invention, and any improvements and changes made on the basis of the present invention are all within the scope of protection of the present invention within.

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.

In the following examples, JEOL JEM-1011 transmission electron microscope (TEM) was used to characterize the structure of porous carbon fibers. Quantachrome Autosorb-1 specific surface area and pore distribution analyzer was used to characterize the pore structure in porous carbon fibers, the adsorption gas was N ₂ , and the degassing temperature was 200°C. Electrospinning uses DC high-voltage power supply SPL50P60Spellman, micro-injection pump KDS-200, StoeltingCo, medical syringes, and medical flat-head stainless steel needles.

Example 1

1) Add 0.5g of pore-forming agent potassium sulfide to 10g of organic solvent N,N-dimethylformamide to dissolve, add 1.0g of polymer polyacrylonitrile with a number average molecular weight of 150w, stir at 80°C for 1h to form a dark purple color The viscous solution is the spinning solution.

2) The electrospinning process was carried out on a single-nozzle electrospinning device, which consisted of a DC high-voltage power supply, a single capillary spinneret, a collecting plate and a ground wire. The collecting plate was made of aluminum foil, and the electrospinning temperature was 15°C.

The specific preparation process is as follows: transfer the dark purple precursor solution prepared above into a 10mL medical syringe, inject it into the spinneret at a flow rate of 1.5mL/h, and apply a high-voltage electric field between the spinneret and the collecting plate to make the spinning solution After being stretched, thinned and solidified, the fibers are formed and fall on the aluminum foil collecting plate. The working voltage is 25kV, and the distance between the needle tip and the aluminum foil is 15cm.

3) The potassium sulfide-polyacrylonitrile fiber membrane collected in step 2) was pre-oxidized in an air atmosphere at 280°C for 2 hours in a tube furnace, and then the air atmosphere was changed to an argon atmosphere at a rate of 4°C/min. The heating rate was raised to 900°C for 2 hours of carbonization. After cooling down to room temperature, the black carbon fibers were washed in 2M hydrochloric acid solution for 0.5 hours to remove potassium sulfide, and finally washed and dried to obtain porous carbon fibers.

Figure 1 shows the nitrogen adsorption and desorption curves of carbon fibers with high specific surface area. There is a relatively high adsorption capacity in the micropore absorption range where the relative pressure is below 0.05, indicating that the carbon fibers have a large number of microporous structures. At the same time, there is a hysteresis loop in the relative pressure range of 0.42-0.9, which indicates that the high specific surface carbon fiber has both microporous and mesoporous structures. Nitrogen adsorption and desorption showed that its specific surface area was 835.0m ² /g.

Figure 2 is a transmission electron micrograph of the carbon fiber with a high specific surface area, and the carbon fiber is in the shape of a fiber with a diameter between 100-130nm.

Example 2

1) Add 0.5g of pore-forming agent potassium sulfide to 10g of organic solvent N,N-dimethylformamide to dissolve, add 1.0g of polymer polyacrylonitrile with a number average molecular weight of 150w, stir at 80°C for 1h to form a dark purple color The viscous solution is the spinning solution.

2) Perform electrospinning according to step 2) of Example 1;

3) Carry out pre-oxidation and carbonization according to step 3) of Example 1, and only replace the temperature of the carbonization step with 1000°C. After cooling down to room temperature, put the black carbon fiber membrane into 2M sulfuric acid solution and wash it for 1 hour to remove sulfuration Potassium, finally washed and dried to obtain high specific surface carbon fiber.

Figure 3 is the nitrogen adsorption and desorption curve of the carbon fiber, and there is a relatively high adsorption amount in the micropore absorption range where the relative pressure is below 0.05, indicating that the carbon fiber has a large number of microporous structures. At the same time, there is a hysteresis loop in the relative pressure range of 0.42-0.9, which indicates that the high specific surface carbon fiber has both microporous and mesoporous structures. Nitrogen adsorption and desorption showed that its specific surface area was 614.8m ² / _g .

Fig. 4 is a transmission electron micrograph of the carbon fiber, and the diameter of the carbon fiber is between 100-130nm in a fibrous shape.

Example 3

1) Add 0.3g of pore-forming agent potassium sulfide to 10g of organic solvent N,N-dimethylformamide to dissolve, add 1.0g of polymer polyacrylonitrile with a number average molecular weight of 150w, stir at 80°C for 1h to form a dark purple color The viscous solution is the spinning solution.

2) Perform electrospinning according to step 2) of Example 1, only the electrospinning temperature is replaced by 30°C, the flow rate is replaced by 1.0mL/h, and the working voltage is replaced by 30kV;

3) Perform pre-oxidation, carbonization and pickling according to step 3) of Example 1, only the pre-oxidation temperature is replaced with 230°C, and the carbonization temperature is replaced with 1000°C.

Figure 5 is the nitrogen adsorption and desorption curve of the carbon fiber. There is a relatively high adsorption amount in the micropore absorption range where the relative pressure is below 0.05, indicating that the carbon fiber has a large number of microporous structures. At the same time, there is a hysteresis loop in the relative pressure range of 0.42-0.9, which indicates that the high specific surface carbon fiber has both microporous and mesoporous structures. Nitrogen adsorption and desorption showed that its specific surface area was 325.6m ² /g.

Fig. 6 is a transmission electron micrograph of the carbon fiber, and the carbon fiber is in the shape of a fiber with a diameter between 100-130nm.

Example 4

1) Add 0.1g of pore-forming agent potassium sulfide to 10g of organic solvent N,N-dimethylformamide to dissolve, add 1.0g of polymer polyacrylonitrile with a number average molecular weight of 150w, stir at 80°C for 1h to form a dark purple color The viscous solution is the spinning solution.

2) Perform electrospinning according to step 2) of Example 1, only replace the electrospinning temperature with 30°C, and replace the working voltage with 30kV;

3) Perform pre-oxidation, carbonization and pickling according to step 3) of Example 1, only the pre-oxidation temperature is replaced with 260°C, and the carbonization temperature is replaced with 800°C.

There is no substantial difference with the result obtained in Example 1.

Example 5

1) Add 0.8g of pore-forming agent potassium sulfide to 10g of organic solvent N,N-dimethylformamide to dissolve, add 1.0g of polymer polyacrylonitrile with a number average molecular weight of 150w, stir at 80°C for 1h to form a dark purple color The viscous solution is the spinning solution.

2) Perform electrospinning according to step 2) of Example 1, only replace the electrospinning temperature with 30°C, and replace the working voltage with 30kV;

3) Perform pre-oxidation, carbonization and pickling according to step 3) of Example 1, only the pre-oxidation temperature is replaced by 260°C.

There is no substantial difference with the result obtained in Example 1.

Claims (31)

1. A high specific surface porous carbon fiber, characterized in that the specific surface area of the fiber is greater than 300m ² /g, and has a micropore and mesoporous structure, and the diameter of the carbon fiber is between 100nm-10μm; The high specific surface porous carbon fiber is prepared by a method comprising the steps of: carbonizing a spinning solution including a pore forming agent, a polymer and an organic solvent after spinning, and then pickling and drying to obtain the high specific surface porous carbon fiber ; Wherein, the pore-forming agent is selected from potassium sulfide. 2. The high specific surface porous carbon fiber according to claim 1, characterized in that the specific surface area of the high specific surface porous carbon fiber is greater than 600 m ² /g. 3. The high specific surface porous carbon fiber according to claim 1, characterized in that the specific surface area of the high specific surface porous carbon fiber is greater than 800 m ² /g. 4. The high specific surface porous carbon fiber according to any one of claims 1-3, characterized in that the diameter of the carbon fiber is between 100 nm-1 μm. 5. The high specific surface porous carbon fiber according to claim 1, characterized in that, the polymer is selected from at least one of polyacrylonitrile, polyimide, pitch, polyvinyl alcohol, polyvinylpyrrolidone and phenolic resin kind. 6. The high specific surface porous carbon fiber according to claim 5, characterized in that, the number average molecular weight of the polyacrylonitrile is 50w-300w; The number average molecular weight of the polyimide is 50w-300w; The number average molecular weights of the asphalt and polyvinyl alcohol are both 50w-300w. 7. The high specific surface porous carbon fiber according to claim 6, characterized in that the number average molecular weight of the polyacrylonitrile is 150w; The number average molecular weight of the polyimide is 150w; The number average molecular weight of described asphalt and polyvinyl alcohol is 150w; The number average molecular weight of the polyvinylpyrrolidone is 150w. 8. A method for preparing the high specific surface porous carbon fiber of claim 1, characterized in that it comprises the steps of: carbonizing the spinning solution comprising a pore-forming agent, a polymer and an organic solvent after spinning, and acid washing The high specific surface porous carbon fiber is obtained after drying; wherein, the pore-forming agent is selected from potassium sulfide; The specific surface area of the high specific surface porous carbon fiber is larger than 300m ² /g, and has micropore and mesopore structure at the same time, and the diameter of the carbon fiber is between 100nm-10μm. 9 . The method according to claim 8 , wherein the specific surface area of the high specific surface porous carbon fiber is greater than 600 m ² /g. 10. The method according to claim 9, characterized in that the specific surface area of the high specific surface porous carbon fiber is greater than 800 m ² /g. 11. The method according to any one of claims 8-10, characterized in that the diameter of the carbon fiber is preferably between 100 nm-1 μm. 12 . The method according to claim 8 , wherein the polymer is selected from at least one of polyacrylonitrile, polyimide, asphalt, polyvinyl alcohol, polyvinylpyrrolidone and phenolic resin. 13. The method according to claim 8, characterized in that, the mass percentage of the pore-forming agent in the spinning solution is 1-10%; The mass percent content of the polymer in the spinning solution is 5-20%. 14. The method according to claim 13, characterized in that the mass percentage of the pore forming agent in the spinning solution is 1% or 3% or 5% or 8%; The mass percentage of the polymer in the spinning solution is 8%, or 10%, or 15%. 15. The method according to claim 12, characterized in that, the number average molecular weight of the polyacrylonitrile is 50w-300w; The number average molecular weight of the polyimide is 50w-300w; The number average molecular weight of described asphalt and polyvinyl alcohol is 50w-300w; The number average molecular weight of the polyvinylpyrrolidone is 50w-300w. 16. The method according to claim 15, characterized in that, the number average molecular weight of the polyacrylonitrile is 150w; The number average molecular weight of the polyimide is 150w; The number average molecular weight of described asphalt and polyvinyl alcohol is 150w; The number average molecular weight of the polyvinylpyrrolidone is 150w. 17. The method according to claim 8, in the spinning step, the spinning method is electrospinning. 18. The method according to claim 17, characterized in that, in the electrospinning, the voltage is 10-35kV; the flow rate of the spinning solution is 0.5-5.0mL/h; the temperature is 15-40°C; the collecting plate Aluminum foil; the distance between the needle tip and the aluminum foil is 5-50cm. 19. The method according to claim 18, characterized in that, in the electrospinning, the voltage is 25kV; the flow rate of the spinning liquid is 1.5mL/h or 1mL/h; the temperature is 15-30°C; The distance of aluminum foil is 15cm. 20. The method of claim 8, the carbonizing step comprising sequentially preoxidation in air and high temperature carbonization in an inert atmosphere. 21. The method according to claim 20, characterized in that, in the pre-oxidation step, the temperature is 180-280° C.; the time is 1-4 hours; the atmosphere is air atmosphere. 22. The method according to claim 21, characterized in that, in the pre-oxidation step, the temperature is 230-280° C. and the time is 2 hours. 23. The method according to claim 21, characterized in that, in the pre-oxidation step, the temperature is 180-230° C. and the time is 2 hours. 24. The method according to claim 21, characterized in that, in the pre-oxidation step, the temperature is 180-260° C. and the time is 2 hours. 25. The method according to claim 20, characterized in that, in the high-temperature carbonization step, the inert atmosphere is _N2 or Ar atmosphere; the carbonization temperature is 600-1000°C; the heating rate is 1-10°C /min; carbonization time is 1-4 hours. 26. The method according to claim 25, characterized in that, in the high-temperature carbonization step, the carbonization temperature is 600-900°C; the heating rate is 4°C/min; and the carbonization time is 2 hours. 27. The method according to claim 25, characterized in that, in the high-temperature carbonization step, the carbonization temperature is 900-1000°C; the heating rate is 4°C/min; and the carbonization time is 2 hours. 28. The method according to claim 8, characterized in that, in the pickling step, the acid is selected from at least one of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid and nitric acid; the concentration of the acid is 0.1-12M; The time is 0.5-4 hours. 29. The method according to claim 28, characterized in that, in the pickling step, the concentration of the acid is 2M; the time is 2 hours. 30. A catalyst carrier, supercapacitor, lithium ion battery or filter membrane, which comprises the high specific surface porous carbon fiber described in any one of claims 1 to 7 or prepared by any one of the methods described in claims 8 to 29 The obtained high specific surface porous carbon fibers. 31. The application of the high specific surface porous carbon fiber described in any one of claims 1 to 7 or the high specific surface porous carbon fiber prepared by the method described in any one of claims 8 to 29, which is used as a catalyst carrier, Supercapacitors, lithium-ion batteries or filter membranes.