CN116443875A - Preparation method and application of a nitrogen-doped porous carbon material - Google Patents

Abstract

The invention discloses a preparation method and application of a nitrogen-doped porous carbon material, which specifically comprises the following steps: crushing waste corn stalks, washing the crushed waste corn stalks with deionized water, and drying the washed waste corn stalks; sterilizing the dried corn stalk powder; uniformly mixing sterilized corn stalk powder and fungus spore liquid, performing constant temperature treatment, filtering, washing and drying to obtain a carbonized precursor; carbonizing the carbonized precursor; dissolving corn stalk carbide, urea and KOH in deionized water, magnetically stirring, drying and sieving to obtain an activated precursor; the activation precursor is added in N ₂ Performing activation treatment in atmosphere, washing the activated product with hydrochloric acid, washing with deionized water to neutrality, washing with absolute ethanol, drying, grinding, and sieving to obtain nitrogen-doped porous carbon material. The preparation method has the advantages of low cost, simple steps, high nitrogen doping efficiency, high specific capacity of the electrode material and good cycle stability when being applied to the preparation of the electrode material.

Description

Preparation method and application of a nitrogen-doped porous carbon material

technical field

The invention belongs to the technical field of preparation of biomass carbon materials, and relates to the preparation of a nitrogen-doped porous carbon material, in particular to a preparation method of a nitrogen-doped porous carbon material and its application in the preparation of high-performance electrode materials.

Background technique

With the continuous growth of energy demand and the increasingly prominent environmental problems, the development of advanced energy storage equipment and management systems has become a trend in the energy industry. Supercapacitors are also called supercapacitors or electrochemical double layer capacitors. Due to the advantages of high power density, fast charging and discharging speed, long service life and wide operating temperature, it has become one of the most concerned and promising energy storage devices.

At present, the key problem limiting the large-scale application of supercapacitors is the low energy density of supercapacitors. The energy density of supercapacitors can be improved by increasing the specific capacitance, which mainly depends on the performance of the electrode materials.

Biomass carbon materials have the characteristics of wide sources, rich heteroatoms and natural pores, and have become one of the research hotspots of supercapacitor electrode materials. The structural characteristics of biochar materials are closely related to the electrochemical performance of supercapacitors, such as specific surface area, surface properties, electrical conductivity, and pore size. The biochar material prepared by the traditional process has a small number of macroporous structures and a low nitrogen doping rate, which leads to difficulty in ion transport in the electrolyte and low electrochemical performance of the prepared supercapacitor. Although traditional physical and chemical pretreatment methods can regulate the biochar material by changing the composition and structure of biomass, part of the primary skeleton of the pretreated biomass will collapse, which will lead to the blockage of the internal pores of the biomass, making It is difficult for the nitrogen source to be fully doped with the biomass substrate, and the nitrogen source is easily lost in the subsequent treatment process, which will eventually have an adverse effect on the electrochemical performance of the carbon material.

Therefore, it is urgent to develop a new preparation method of nitrogen-doped porous carbon materials to achieve sufficient doping of nitrogen sources and biomass substrates, so as to obtain high-performance electrode materials with high specific capacity and good cycle stability.

Contents of the invention

Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of nitrogen-doped porous carbon material. The preparation method of the present invention has low cost, simple steps and high nitrogen doping efficiency. When applied to the preparation of electrode materials, electrode materials High specific capacity and good cycle stability.

The present invention is achieved through the following technical solutions:

A preparation method of a high-performance supercapacitor electrode material, comprising the following steps:

1) Grinding the waste corn stalks, washing with deionized water after crushing, removing impurities on the surface of the corn stalk powder, washing and drying;

2) Mix the dried corn stalk powder with deionized water evenly, and perform sterilization treatment to obtain sterilized corn stalk powder;

3) Mix the sterilized corn stalk powder and the fungal spore liquid evenly, treat at a constant temperature, filter, wash, and dry to obtain a carbonized precursor;

4) Carbonize the carbonization precursor to obtain carbonized corn stalks;

5) Dissolve corn stalk charcoal, urea and KOH in deionized water, stir magnetically, dry, and sieve to obtain activated precursors;

6) The activated precursor is activated under N2 atmosphere, the activated product is first washed with hydrochloric acid, then washed with deionized water until neutral, then washed with absolute ethanol, dried, ground, and sieved to obtain Nitrogen-doped porous carbon materials.

A further improvement of the present invention is:

The drying temperature in step 1) is 100-110° C., and the drying time is 10-14 hours; the particle size of the crushed corn stalk powder is 40-60 mesh; the mass ratio of corn stalk powder to deionized water is 1:2-5.

Further, the fungal spore liquid in step 3) is obtained by inoculating Phanerochaetechrysosporium SHBCC D22643 on the medium, culturing, washing with water, and filtering; the temperature of the constant temperature treatment is 25-32°C, and the time is 1- 3 weeks.

Further, the temperature of the carbonization treatment in step 4) is 480-520° C., and the carbonization time is 8-15 minutes.

Further, in step 5), the mass ratio of corn stalk charcoal, urea and KOH is 1:0.8~1.2:0.8~1.2.

Further, the temperature of the activation treatment in step 6) is 750°C~850°C, and the time is 80~100 min.

Further, the molar concentration of the hydrochloric acid described in step 6) is 0.8-1.2 mol/L, passing through a 200-mesh sieve.

A further improvement of the present invention is:

Application of the nitrogen-doped porous carbon material prepared by the above method in the preparation of high-performance electrode materials.

Further, the specific process of application is: nitrogen-doped porous carbon is used as the active material, acetylene black is used as the conductive agent, and polytetrafluoroethylene emulsion is used as the binder, and they are mixed according to the mass ratio of 8:0.8~1.2:0.8~1.2 In a mortar, add ethanol, fully grind to mix evenly to obtain a slurry, smear the slurry on a 1 cm×1 cm foamed nickel, dry it and press it into a tablet to obtain a biochar electrode.

Compared with prior art, the beneficial effect of the present invention is:

First, the present invention uses fungi to pretreat corn stalks to prepare high-performance supercapacitor electrode materials and its preparation method, and obtains high-performance electrode materials with high nitrogen doping rate, high specific energy storage capacity, and good cycle stability. It provides a new way for the comprehensive utilization of biomass resources.

Second, the present invention uses fungi to pretreat corn stalks to prepare high-performance supercapacitor electrode materials and its preparation method. The present invention uses corn stalks as raw materials, which are waste biomass with abundant sources, and realize resource regeneration and utilization.

Third, the present invention uses fungi to pretreat corn stalks to prepare high-performance supercapacitor electrode materials and its preparation method. The present invention uses lignocellulose-degrading enzymes produced by fungi to destroy the waxy layer on the surface of biomass and widen the pores on the surface of biomass The structure allows urea molecules to penetrate into the interior of the material, further increasing the nitrogen doping amount of the carbon material.

Fourth, the present invention uses fungi to pretreat corn stalks to prepare high-performance supercapacitor electrode materials and its preparation method. The present invention uses lignocellulose-degrading enzymes produced by fungi to destroy biomass so that fungal hyphae directly enter the interior of the biomass, broadening the The pores allow the electrolyte to enter the interior of the material and improve the electrochemical performance.

Fifth, the present invention uses fungi to pretreat corn stalks to prepare high-performance supercapacitor electrode materials and its preparation method. The prepared electrode materials exhibit high specific capacitance, high rate performance and good cycle stability.

Description of drawings

Fig. 1 is the SEM figure of the corn stalk carbonized product obtained in embodiment 1;

Fig. 2 is the SEM figure of the obtained corn stalk charcoal of embodiment 3;

Fig. 3 is the CV graph under the different scanning speeds of the biochar electrode sheet gained in embodiment 4;

Fig. 4 is the GCD graph of the biochar electrode sheet obtained in Example 4 under different current densities;

Fig. 5 is the CV graph under the different scanning speeds of the biochar electrode sheet gained in embodiment 5;

Fig. 6 is the GCD graph of the biochar electrode sheet obtained in Example 5 under different current densities;

Fig. 7 is the cycle stability diagram of the biomass electrode sheet obtained in Example 4 at a current density of 10 A/g.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

Embodiment 1: prepare fungal spore liquid

After the freeze-dried powder of Phanerochaete chrysosporium is activated, it is transferred to a comprehensive PDA plate and cultured in an incubator at 27°C for 7-9 days. After the plate is covered with hyphae, drop sterilized water into the plate, gently scrape off the fungal mycelium with a sterilized inoculation loop, filter it with gauze, pour it into a 250 mL Erlenmeyer flask, and rinse with sterilized deionized water Constant volume, obtain Phanerochaete chrysosporium fungal spore liquid.

Example 2: Preparation of nitrogen-doped porous carbon material

1) The waste corn stalks are crushed, and the particle size after crushing is 40-60 mesh. After crushing, it is continuously washed with 2-5 times the weight of deionized water until the washing liquid is not turbid, it is considered that the impurities on the surface of the raw material have been removed. After washing, dry at 100~110℃ for 10~14h;

2) Mix the dried corn stalk powder with deionized water evenly, and perform sterilization treatment to obtain sterilized corn stalk powder;

3) The sterilized corn stalk powder and the fungal spore liquid were mixed evenly according to the mass volume ratio of 30 g: 10 mL, treated at a constant temperature of 25-32 °C for 1 week, filtered, washed, and dried to obtain a carbonized precursor;

4) The carbonization precursor was carbonized at 480-520°C for 8-15 minutes to obtain carbonized corn stalks; the carbonized corn stalks were observed with a scanning electron microscope (SEM). More developed pore structure is conducive to the infiltration of nitrogen source and activator;

5) Dissolve corn stalk charcoal, urea and KOH in deionized water at a mass ratio of 1:0.8~1.2:0.8~1.2, magnetically stir, dry, and pass through a 60-mesh sieve to obtain an activated precursor;

6) The activated precursor is activated under N2 atmosphere at 750°C~850°C for 80~100 min, and the activated product is first washed with 0.8~1.2 mol/L hydrochloric acid, and then washed with deionized water until neutral , and then washed with absolute ethanol, dried, ground, and sieved to obtain a nitrogen-doped porous carbon material.

Example 3: Preparation of nitrogen-doped porous carbon material

Step 3) The constant temperature treatment time was 3 weeks, and other operations were the same as in Example 2. The carbonized corn stalks obtained from fungal treatment for 3 weeks and carbonization were observed with a scanning electron microscope (SEM), and the results are shown in Figure 2.

Example 4: Preparation of Biomass Charcoal Electrode

The nitrogen-doped porous carbon material obtained in Example 2 is used as an active material, acetylene black is used as a conductive agent, and polytetrafluoroethylene emulsion is used as a binder, mixed in a mortar according to a mass ratio of 8:1:1, and added Ethanol, fully ground to make it evenly mixed to obtain a slurry, smear about 5 mg of the slurry on a nickel foam of 1 cm×1 cm, dry it and press it under a pressure of 10 MPa for 2 minutes to obtain a biochar electrode .

Embodiment 5: preparation biochar electrode

The nitrogen-doped porous carbon material prepared in Example 3 was used as the active material, and the other operations were the same as in Example 4.

Embodiment 6: performance test

The biomass charcoal electrode prepared in Examples 4 and 5 was used in a CS310M electrochemical workstation to carry out electrochemical tests in a three-electrode system. The prepared biomass charcoal electrode was used as the working electrode, and the platinum sheet electrode (2 cm × 2 cm) was The counter electrode, the Hg/HgO electrode is the reference electrode, and the electrochemical test is carried out in 6M KOH solution. The potential window range is -0.8-0.2 V, constant current discharge at different current densities, according to the specific capacitance calculation formula Cs=IΔt/(m*ΔV). Among them, Cs is the mass specific capacitance of the sample, the unit is F/g; I is the discharge current, the unit is A; Δt is the discharge time, the unit is s; m is the mass of the active material on the electrode sheet, the unit is g; ΔV is the potential difference, the unit is for V.

The results obtained are as follows:

Fig. 3 is the CV curve diagram of the biochar electrode sheet obtained in Example 4 at different scan rates, the CV curve shows a good rectangle, and there is no obvious deformation at the scan rate of 2-100 mV s-1, the prepared The specific capacitance of the electrode material is mainly derived from the electric double layer capacitance;

Fig. 4 is the GCD graph of the biochar electrode sheet obtained in Example 4 at different current densities, by calculation at 0.5A/g, 1A/g, 2A/g, 5A/g, 10A/g current density ratio The capacitance is 303.9 F/g, 286.1 F/g, 273.8 F/g, 260.0 F/g, 252.4 F/g;

Fig. 5 is the CV curve diagram of the biochar electrode sheet obtained in Example 5 at different scan rates, the CV curve shows a good rectangle, and there is no obvious deformation at the scan rate of 2-100 mV s-1, the prepared The specific capacitance of the electrode material is mainly derived from the electric double layer capacitance;

Fig. 6 is the GCD graph of the biochar electrode sheet obtained in Example 5 at different current densities, by calculation at 0.5A/g, 1A/g, 2A/g, 5A/g, 10A/g current density ratio The capacitances are 408.7 F/g, 377.2 F/g, 356.8 F/g, 335.8 F/g, 320.4 F/g;

Figure 7 is the cycle stability diagram of the biomass electrode sheet obtained in Example 4 at a current density of 10 A/g. The electrode material is tested and evaluated for its cycle life through a constant current charge and discharge cycle. Under 10 A/g After 10,000 cycles, the capacitance retention rate is 89.5%, showing good cycle stability.

The above-mentioned embodiments are only for illustrating the technical concept and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (9)

1. The preparation method of the nitrogen-doped porous carbon material is characterized by comprising the following steps of:

1) Crushing waste corn stalks, washing the crushed waste corn stalks with deionized water to remove impurities on the surfaces of corn stalk powder, and drying the washed waste corn stalk powder;

2) Uniformly mixing the dried corn stalk powder with deionized water, and performing sterilization treatment to obtain sterilized corn stalk powder;

3) Uniformly mixing sterilized corn stalk powder and fungus spore liquid, performing constant temperature treatment, filtering, washing and drying to obtain a carbonized precursor;

4) Carbonizing the carbonized precursor to obtain corn stalk carbonized matter;

5) Dissolving corn stalk carbide, urea and KOH in deionized water, magnetically stirring, drying and sieving to obtain an activated precursor;

6) The activation precursor is added in N ₂ And (3) performing activation treatment in an atmosphere, washing the activated product with hydrochloric acid, washing with deionized water to be neutral, washing with absolute ethyl alcohol, drying, grinding and sieving to obtain the nitrogen-doped porous carbon material.

2. The method for preparing the nitrogen-doped porous carbon material according to claim 1, wherein the method comprises the following steps: the drying temperature in the step 1) is 100-110 ℃ and the drying time is 10-14 h; the grain diameter of the crushed corn stalk powder is 40-60 meshes; the mass ratio of the corn stalk powder to the deionized water is 1:2-5.

3. The method for preparing the nitrogen-doped porous carbon material according to claim 1, wherein the method comprises the following steps: the fungus spore liquid in the step 3) is obtained by inoculating Phanerochaete chrysosporium to a culture medium for culturing, washing and filtering; the constant temperature treatment is carried out at 25-32 ℃ for 1-3 weeks.

4. The method for preparing the nitrogen-doped porous carbon material according to claim 1, wherein the method comprises the following steps: the carbonization treatment temperature in the step 4) is 480-520 ℃, and the carbonization time is 8-15 min.

5. The method for preparing the nitrogen-doped porous carbon material according to claim 1, wherein the method comprises the following steps: in the step 5), the mass ratio of the corn stalk carbide to the urea to the KOH is 1:0.8-1.2:0.8-1.2.

6. The method for preparing the nitrogen-doped porous carbon material according to claim 1, wherein the method comprises the following steps: the temperature of the activation treatment in the step 6) is 750-850 ℃ and the time is 80-100 min.

7. The method for preparing the nitrogen-doped porous carbon material according to claim 1, wherein the method comprises the following steps: and 6) the molar concentration of the hydrochloric acid in the step 6) is 0.8-1.2 mol/L, and the hydrochloric acid is sieved by a 200-mesh sieve.

8. Use of a nitrogen-doped porous carbon material prepared by the method of any one of claims 1-7 in the preparation of a high performance electrode material.

9. The use of the nitrogen-doped porous carbon material according to claim 8 for preparing high-performance electrode materials, wherein the specific process is: mixing nitrogen-doped porous carbon serving as an active material, acetylene black serving as a conductive agent and polytetrafluoroethylene emulsion serving as a binder in a mass ratio of 8:0.8-1.2:0.8-1.2 in a mortar, adding ethanol, fully grinding and uniformly mixing to obtain slurry, smearing the slurry on foamed nickel of 1 cm multiplied by 1 cm, drying and tabletting to obtain the biomass carbon electrode.