Super-capacitor carbon based on waste traditional Chinese medicine residues and preparation method and application thereof

Abstract

The invention discloses super-capacitor carbon based on waste traditional Chinese medicine residues and a preparation method and application thereof, and the preparation method comprises the following steps: 1, taking traditional Chinese medicine residue powder, and carrying out the hydrothermal carbonization to obtain hydrothermal carbon; 2, mixing the hydrothermal carbon with KOH, and performing high-temperature activation; and step 3, washing the activated sample to be neutral, drying, pickling, and drying again. The specific surface area range of the super capacitor carbon is 510.60-2060.21 m < 2 > / g, and the super capacitor carbon is of a porous structure. According to the prepared high-performance supercapacitor carbon based on thermochemical treatment of the waste traditional Chinese medicine residues, the specific capacitance value of a double-electrode-layer supercapacitor prepared from the high-performance supercapacitor carbon reaches up to 145.5 F / g, and the capacitance retention rate is higher than 90% after 10000 times of circulation; the optimal working condition is screened out by testing the capacitive performance of porous carbon with different hydrothermal reaction conditions, different activation temperatures, different manganese contents and different activated alkali-carbon ratios, and used traditional Chinese medicine residues belong to biomass and are cheap and easy to obtain.

Description

Technical Field

[0001] The invention relates to a biomass material and a preparation method and application thereof, and in particular to a supercapacitor carbon based on discarded traditional Chinese medicine residues and a preparation method and application thereof. Background Art

[0002] Traditional Chinese medicine residue is a kind of wet biomass (water content can reach up to 70% or more), which can cause microbial corruption and rapid degradation. In addition, many mineral traditional Chinese medicine residues contain toxic heavy metals. If not handled properly, they may pose a threat to the local ecological environment and human health. The traditional treatment method of traditional Chinese medicine residue is mainly simple stacking and landfilling, which not only aggravates environmental pollution, but also causes the waste of traditional Chinese medicine residue as a special biomass resource. Therefore, how to harmlessly treat traditional Chinese medicine residue and further utilize it as a resource has gradually become a research hotspot.

[0003] At present, the main methods for resource utilization of Chinese medicine residues include pyrolysis and gasification, soil remediation, and direct combustion. Most of these methods have low utilization rates and are difficult to achieve harmlessness and high value of Chinese medicine residues. Due to the high water content, the pre-drying process of Chinese medicine residues before incineration, pyrolysis and gasification will incur high drying costs, resulting in low energy recovery rate, which limits the application to a certain extent. In addition to pyrolysis and gasification, hydrothermal carbonization, a biomass thermochemical conversion technology currently used, has attracted widespread attention in the field of biomass treatment due to its advantages such as mild conditions and low energy consumption. Chinese medicine residues contain cellulose, hemicellulose and lignin, and have rich primary pore structures. Pyrolysis or hydrothermal carbonization technology can be used to convert Chinese medicine residues into porous carbon precursors, and then porous carbon is prepared for energy storage and adsorption of pollutants, realizing the high value utilization of Chinese medicine residues.

[0004] A supercapacitor is a device that achieves charge storage. Its performance is between that of traditional capacitors and chemical batteries. It has the characteristics of fast charging and discharging and charge storage. According to the electrode materials and charge storage mechanisms, supercapacitors are mainly divided into the following three categories: hybrid supercapacitors, pseudocapacitors and double-layer capacitors. Among them, double-layer capacitors store energy by adsorbing ions at the positive and negative electrodes. Compared with electrochemical energy storage devices such as lithium-ion batteries, they have the advantages of high power density, long cycle life, and good low-temperature performance. They are widely used in new energy vehicles and other fields.

[0005] The existing supercapacitor carbon made from traditional Chinese medicine residues has the disadvantages of not using hydrothermal carbonization technology for pre-carbonization, high energy consumption, lack of manganese functional groups, and no pseudocapacitive effect. Summary of the invention

[0006] Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing supercapacitor carbon based on discarded Chinese medicine residues with cheap and readily available raw materials. Another purpose of the present invention is to provide a supercapacitor carbon with a high specific capacitance value. Another purpose of the present invention is to provide an application of supercapacitor carbon in a double-layer supercapacitor.

[0007] Technical solution: The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues of the present invention comprises the following steps:

[0008] Step 1, taking the Chinese medicine residue powder and performing hydrothermal carbonization to obtain hydrothermal charcoal;

[0009] Step 2, mixing the hydrothermal carbon with KOH and performing high temperature activation;

[0010] Step three, washing the activated sample to neutrality, drying it, acid washing it, and drying it again to obtain supercapacitor carbon.

[0011] Furthermore, in step 1, the temperature of hydrothermal carbonization is 200-300°C, the time is 120-240min, and the solid-liquid ratio is 1:4-1:5. The Chinese medicine residue is one or more of patchouli, clove, and Morinda officinalis. The Chinese medicine residue is patchouli, clove, and Morinda officinalis of equal mass. The particle size of the Chinese medicine residue powder is ≤60 mesh, and the Mn element content is 10.27-8840.91 mg / kg.

[0012] Furthermore, in step 2, the mass ratio of hydrothermal carbon to KOH is 1:2 to 3. The heating rate of high temperature activation is 5 to 15°C / min, the activation temperature is 700 to 900°C, and the holding time is 40 to 70 min.

[0013] The supercapacitor carbon of the present invention has a specific surface area of ​​510.60 to 2060.21 m 2 / g, which is a porous structure.

[0014] Application of the supercapacitor carbon of the present invention in double-layer supercapacitors.

[0015] Furthermore, supercapacitor carbon, carbon black and PVDF are mixed in a mass ratio of 8:1:1, and a KOH aqueous solution is used as the electrolyte. After the negative electrode shell, spring, gasket, negative electrode sheet, diaphragm, positive electrode sheet and positive electrode shell are assembled in sequence, they are stamped into shape; the specific capacitance value of the obtained double-layer supercapacitor reaches 145.5F / g, and the capacitance retention rate is higher than 90% after 10,000 cycles.

[0016] Preparation principle: Traditional Chinese medicine residues are hydrolyzed, dehydrated, decarboxylated, condensed, polymerized and aromatized under hydrothermal carbonization to form hydrothermal carbon. During KOH high-temperature activation, hydrothermal carbon forms a porous structure, which increases the specific surface area. Traditional Chinese medicine residues with high manganese content form a large number of manganese-containing functional groups on the surface, which have a pseudocapacitive effect and increase the specific capacitance.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0018] 1. The high-performance supercapacitor carbon prepared by the present invention is based on the thermochemical treatment of waste Chinese medicine residues. The double-layer supercapacitor prepared by the carbon has a specific capacitance value of up to 145.5F / g, and the capacitance retention rate after 10,000 cycles is higher than 90%;

[0019] 2. The optimal working condition was screened out by testing the capacitive performance of porous carbon based on traditional Chinese medicine residue under different hydrothermal reaction conditions, different activation temperatures, different manganese contents, and different activation alkali-carbon ratios. The traditional Chinese medicine residue used is biomass, which is cheap and easily available. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a scanning electron microscope morphology image of the capacitor carbon of the present invention;

[0021] Figure 2 It is a schematic diagram of the structure of the double electric layer capacitor of the present invention;

[0022] Figure 3 This is a graph showing the variation of specific capacitance of porous carbon materials of traditional Chinese medicine slag with current density at different manganese contents;

[0023] Figure 4 This is a graph showing the variation of specific capacitance of the double-layer supercapacitor obtained with different alkali-carbon ratios according to the present invention with respect to current density. DETAILED DESCRIPTION

[0024] Unless otherwise specified, the materials, reagents, instruments, etc. used in the following examples can be obtained from commercial sources. Experimental methods without specific conditions in the examples are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0025] Example 1

[0026] A method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues comprises the following steps:

[0027] (1) Patchouli, cloves, and Morinda officinalis powders with a mass ratio of 1:1:1 and a mesh size of 60 were hydrothermally carbonized in a hydrothermal reactor at 260°C and a solid-liquid ratio of 1:5 for 180 min to obtain hydrothermal charcoal.

[0028] (2) The hydrothermal charcoal and KOH were mixed in a mass ratio of 1:2 and then activated at high temperature in a tube furnace at a heating rate of 10 °C / min, an activation temperature of 800 °C, and a holding time of 60 min.

[0029] (3) The activated sample is washed with hydrochloric acid and deionized water until it is neutral, then dried and pickled with hydrochloric acid, and dried again to obtain supercapacitor carbon.

[0030] like Figure 1 The supercapacitor carbon obtained in this embodiment was subjected to scanning electron microscopy (SEM), as shown in FIG. Figure 1 As shown, the capacitor carbon structure is porous and has a large specific surface area of ​​2060.21m 2 / g, pore size is 0.52μm.

[0031] The ICP test of the Chinese medicine residue powder in this example showed that the Mn content was 3317.19 mg / kg.

[0032] Application Example 1

[0033] The supercapacitor carbon obtained in Example 1 was mixed with capacitor carbon, carbon black and PVDF in a mass ratio of 8:1:1, and a 6 mol / L KOH aqueous solution was used as the electrolyte. After the negative zinc sheet 1, the negative porous carbon 2, the diaphragm 3 (KOH wetted), the positive porous carbon 4 and the positive zinc sheet 5 were assembled in order, they were placed on a tablet press and stamped to make a double-layer supercapacitor, such as Figure 2 shown.

[0034] Example 2

[0035] A method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues comprises the following steps:

[0036] (1) A Chinese medicinal residue powder of patchouli with a mass ratio of 1:1:1 and a mesh size of 60 was hydrothermally carbonized in a hydrothermal reactor at 260°C and a solid-liquid ratio of 1:5 for 180 min to obtain hydrothermal charcoal.

[0037] (2) The hydrothermal charcoal and KOH were mixed in a mass ratio of 1:2 and then activated at high temperature in a tube furnace at a heating rate of 10 °C / min, an activation temperature of 800 °C, and a holding time of 60 min.

[0038] (3) The activated sample was washed with hydrochloric acid and deionized water until neutral, dried, pickled with hydrochloric acid, and dried again to obtain supercapacitor carbon with a specific surface area of ​​1947.04 m 2 / g, pore size is 0.72μm.

[0039] ICP test was performed on the Chinese medicine residue powder, and the Mn content was found to be 8840.91 mg / kg.

[0040] Application Example 2

[0041] The supercapacitor carbon obtained in Example 2 was mixed with capacitor carbon, carbon black and PVDF in a mass ratio of 8:1:1, and a 6 mol / L KOH aqueous solution was used as the electrolyte. After the negative electrode shell, spring, gasket, negative electrode sheet, diaphragm (KOH wetted), positive electrode sheet and positive electrode shell were assembled in order, they were placed on a tablet press for stamping to produce a double-layer supercapacitor.

[0042] Comparative Example 1

[0043] The remaining steps of this comparative example are the same as those of Example 1, except that the Chinese medicine residue powder is replaced with 60-mesh Astragalus Chinese medicine residue powder. A double-layer supercapacitor is prepared according to the method of Application Example 1.

[0044] The ICP test of the Chinese medicine residue in this example showed that the Mn content was 10.27 mg / kg.

[0045] The specific capacitance of the double-layer supercapacitors obtained in Application Example 1, Application Example 2, and Comparative Example 1 was measured by cyclic voltammetry. The results are as follows: Figure 3 As shown, the double-layer supercapacitor obtained in Application Example 1 has the highest specific capacitance, followed by the double-layer supercapacitor obtained in Application Example 2, and the double-layer supercapacitor obtained in Comparative Example 1 has the smallest specific capacitance.

[0046] Example 3

[0047] A method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues comprises the following steps:

[0048] (1) A Chinese medicinal residue powder of patchouli with a mass ratio of 1:1:1 and a mesh size of 60 was hydrothermally carbonized in a hydrothermal reactor at 260°C and a solid-liquid ratio of 1:5 for 180 min to obtain hydrothermal charcoal.

[0049] (2) The hydrothermal charcoal and KOH were mixed in a mass ratio of 1:3 and then activated at high temperature in a tube furnace at a heating rate of 10 °C / min, an activation temperature of 800 °C, and a holding time of 60 min.

[0050] (3) The activated sample was washed with hydrochloric acid and deionized water until neutral, dried, pickled with hydrochloric acid, and dried again to obtain supercapacitor carbon with a specific surface area of ​​510.60 m 2 / g, pore size is 1.20μm.

[0051] Application Example 3

[0052] The supercapacitor carbon obtained in Example 3 was mixed with capacitor carbon, carbon black and PVDF in a mass ratio of 8:1:1, and a 6 mol / L KOH aqueous solution was used as the electrolyte. After the negative electrode shell, spring, gasket, negative electrode sheet, diaphragm (KOH wetted), positive electrode sheet and positive electrode shell were assembled in order, they were placed on a tablet press for stamping to make a double-layer supercapacitor.

[0053] The specific capacitance of the double-layer supercapacitor obtained in Application Example 1 and Application Example 3 was determined by cyclic voltammetry. The results are as follows: Figure 4 As shown, the specific capacitance of the double-layer supercapacitor obtained in Application Example 1 is higher than that of the double-layer supercapacitor obtained in Application Example 3. The capacitance retention rate of the double-layer supercapacitor obtained in Application Example 1 after 10,000 cycles is 90.5%, and the capacitance retention rate of the double-layer supercapacitor obtained in Application Example 3 after 10,000 cycles is 91.2%.

[0054] Example 4

[0055] A method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues comprises the following steps:

[0056] (1) Patchouli, cloves, and Morinda officinalis powders with a mass ratio of 1:1:1 and 80 mesh were hydrothermally carbonized in a hydrothermal reactor at 200°C and a solid-liquid ratio of 1:1 for 120 min to obtain hydrothermal charcoal.

[0057] (2) The hydrothermal charcoal and KOH were mixed in a mass ratio of 1:3 and then activated at high temperature in a tube furnace at a heating rate of 5 °C / min, an activation temperature of 700 °C, and a holding time of 70 min.

[0058] (3) The activated sample was washed with hydrochloric acid and deionized water until neutral, dried, pickled with hydrochloric acid, and dried again to obtain supercapacitor carbon with a specific surface area of ​​2001.04 m 2 / g, pore size is 0.49μm.

[0059] Example 5

[0060] A method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues comprises the following steps:

[0061] (1) Patchouli, cloves, and Morinda officinalis powders with a mass ratio of 1:1:1 and 80 mesh were hydrothermally carbonized in a hydrothermal reactor at 300°C and a solid-liquid ratio of 1:6 for 240 min to obtain hydrothermal charcoal.

[0062] (2) The hydrothermal charcoal was mixed with KOH in a mass ratio of 1:2 and then activated at a high temperature in a tube furnace at a heating rate of 15 °C / min, an activation temperature of 900 °C, and a holding time of 40 min.

[0063] (3) The activated sample was washed with hydrochloric acid and deionized water until neutral, dried, pickled with hydrochloric acid, and dried again to obtain supercapacitor carbon with a specific surface area of ​​2010.56 m 2 / g, pore size is 0.45μm.

[0064] Example 6

[0065] This example aims to explore the effects of different hydrothermal reaction conditions on the capacitive properties of traditional Chinese medicine residue-based porous carbon.

[0066] The remaining steps of this embodiment are the same as those of embodiment 1 and application example 1, except that five parallel tests are set, and the temperature of the hydrothermal carbonization in step 1 is set to 250° C., 255° C., 260° C., 265° C., and 270° C. The specific capacitance of the obtained double-layer supercapacitor is measured by cyclic voltammetry, and it is found that the specific capacitance does not substantially change with the hydrothermal carbonization temperature.

[0067] Example 7

[0068] This example aims to explore the effect of different activation temperatures on the capacitive properties of traditional Chinese medicine residue-based porous carbon.

[0069] The remaining steps of this embodiment are the same as those of embodiment 1 and application example 1, except that six parallel tests are set, and the activation temperature of step 2 is set to 800° C., 810° C., 820° C., 830° C., 840° C., and 850° C. The specific capacitance of the obtained double-layer supercapacitor is measured by cyclic voltammetry, and it is found that the specific capacitance increases with the increase of activation temperature, but the increase is small.

Claims

1. A method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residues, characterized in that: The following steps are involved: Step 1, taking the Chinese medicine residue powder and performing hydrothermal carbonization to obtain hydrothermal charcoal; Step 2, mixing the hydrothermal carbon with KOH and performing high temperature activation; Step three, washing the activated sample to neutrality, drying it, acid washing it, and drying it again to obtain supercapacitor carbon.

2. The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to claim 1, characterized in that: In the step 1, the temperature of the hydrothermal carbonization is 200-300° C., the time is 120-240 min, and the solid-liquid ratio is 1:1-1:

6.

3. The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to claim 1, characterized in that: In the step 1, the Chinese medicinal residue is one or more of patchouli, clove, and Morinda officinalis.

4. The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to claim 3, characterized in that: The Chinese medicinal residues are patchouli, cloves and Morinda officinalis of equal mass.

5. The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to claim 1, characterized in that: In the step 1, the particle size of the Chinese medicine residue powder is ≤60 mesh, and the Mn element content is 3317.19-8840.91 mg / kg.

6. The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to claim 1, characterized in that: In the step 2, the mass ratio of the hydrothermal charcoal to KOH is 1:2-3.

7. The method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to claim 1, characterized in that: In the step 2, the heating rate of high temperature activation is 5-15°C / min, the activation temperature is 700-900°C, and the holding time is 40-70min.

8. The supercapacitor carbon obtained by the method for preparing supercapacitor carbon based on discarded traditional Chinese medicine residue according to any one of claims 1 to 7, characterized in that: The specific surface area of ​​the supercapacitor carbon is 510.60-2060.21 m 2 / g, which is a porous structure.

9. Use of the supercapacitor carbon according to claim 8 in a double-layer supercapacitor.

10. The use of the supercapacitor carbon according to claim 9 in a double-layer supercapacitor, characterized in that: The supercapacitor carbon, carbon black and PVDF are mixed in a mass ratio of 8:1:1, a KOH aqueous solution is used as the electrolyte, and after the negative electrode shell, spring sheet, gasket, negative electrode sheet, diaphragm, positive electrode sheet and positive electrode shell are assembled in sequence, they are stamped into shape; the obtained double-layer supercapacitor has a specific capacitance value of 145.5F / g, and a capacitance retention rate of more than 90% after 10,000 cycles.

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