CN113880085B - Preparation method of biomass activated carbon for supercapacitor and supercapacitor - Google Patents
Preparation method of biomass activated carbon for supercapacitor and supercapacitor Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 169
- 239000002028 Biomass Substances 0.000 title claims abstract description 77
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 36
- 230000004913 activation Effects 0.000 claims abstract description 24
- 239000000463 material Substances 0.000 claims abstract description 23
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 21
- 238000002156 mixing Methods 0.000 claims abstract description 15
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000005469 granulation Methods 0.000 claims abstract description 13
- 230000003179 granulation Effects 0.000 claims abstract description 13
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims abstract description 13
- 239000005539 carbonized material Substances 0.000 claims abstract description 12
- 230000003213 activating effect Effects 0.000 claims abstract description 10
- 238000003763 carbonization Methods 0.000 claims abstract description 9
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 9
- 239000011230 binding agent Substances 0.000 claims abstract description 8
- 238000010438 heat treatment Methods 0.000 claims description 37
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical group [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 33
- 238000001994 activation Methods 0.000 claims description 25
- 239000002245 particle Substances 0.000 claims description 15
- 239000003990 capacitor Substances 0.000 claims description 13
- 239000011347 resin Substances 0.000 claims description 12
- 229920005989 resin Polymers 0.000 claims description 12
- 238000005406 washing Methods 0.000 claims description 9
- 244000060011 Cocos nucifera Species 0.000 claims description 8
- 235000013162 Cocos nucifera Nutrition 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- 238000002791 soaking Methods 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000001291 vacuum drying Methods 0.000 claims description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 235000009496 Juglans regia Nutrition 0.000 claims description 4
- 238000004939 coking Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 235000020234 walnut Nutrition 0.000 claims description 4
- 239000012298 atmosphere Substances 0.000 claims description 2
- 239000002131 composite material Substances 0.000 claims description 2
- 238000005470 impregnation Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000010907 mechanical stirring Methods 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims description 2
- 239000010902 straw Substances 0.000 claims description 2
- 239000002023 wood Substances 0.000 claims description 2
- 240000007049 Juglans regia Species 0.000 claims 1
- 239000011148 porous material Substances 0.000 abstract description 33
- 230000001105 regulatory effect Effects 0.000 abstract description 4
- 230000001276 controlling effect Effects 0.000 abstract description 3
- 238000011031 large-scale manufacturing process Methods 0.000 abstract description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 8
- 238000001179 sorption measurement Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 238000010277 constant-current charging Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000003795 desorption Methods 0.000 description 4
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
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- 239000001307 helium Substances 0.000 description 4
- 229910052734 helium Inorganic materials 0.000 description 4
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 4
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- 239000003575 carbonaceous material Substances 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical group O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/312—Preparation
- C01B32/318—Preparation characterised by the starting materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/44—Raw materials therefor, e.g. resins or coal
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
- H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a preparation method of biomass activated carbon for a supercapacitor, which comprises the steps of pretreating a biomass carbonized material with a sodium persulfate solution, adding a binder for room-temperature granulation, mixing a granulated product with an activating agent for carbonization and activation treatment, and carrying out aftertreatment to obtain spherical activated carbon. The biomass activated carbon prepared by the method has high tap density, good pore diameter structure and good electrochemical performance, the method for regulating and controlling the pore diameter structure of the super-capacity carbon is simple, the large-scale production of the high-quality super-capacity carbon is easy to realize, and the high-added-value application of biomass materials is realized.
Description
Technical Field
The invention belongs to the technical field of supercapacitor preparation, and particularly relates to a preparation method of biomass activated carbon for a supercapacitor and the biomass activated carbon.
Background
As a novel energy storage device between a battery and a conventional capacitor, a super capacitor has been widely used due to its characteristics of high power density, long service life, strong adaptability, and the like. The super capacitor mainly depends on the adsorption of ions on the surface of an electrode to store energy, so that the electrode material has important influence on the performance of the super capacitor.
At present, the electrode material commercialized by the super capacitor is mainly active carbon, the active carbon contains a large number of micropores, and the specific surface area is 1500-2400 m 2 Between/g. The pore diameter characteristic is very important for obtaining the electrochemical performance of the ultra-volume carbon with good stability. And such characteristics are closely related to their precursor materials. Precursor materials that are commonly used to prepare ultra-tolerant carbons include mineral feedstocks and biomass feedstocks. Compared with mineral raw materials, the biomass raw materials have the characteristics of wide sources, low price, reproducibility and the like, but have the characteristic of low volume density, so the volume specific capacity is lower than that of the mineral substances. The research aiming at the biomass is mainly focused at presentThe electrochemical performance of the activated carbon is improved by adjusting the process.
The patent CN111874902A relates to a preparation method of biomass super capacitor activated carbon, which limits ash content of a biomass material, obtains super-capacity activated carbon through crushing, heating treatment, activation treatment and washing to neutrality, and solves the problem of pollution caused by an acid deliming process in the existing preparation method of the biomass super capacitor activated carbon; the patent CN112194130A provides biomass activated carbon, an electrode and a preparation method and application thereof, and the activated carbon with high specific surface area and high super capacity is obtained through the steps of KOH primary activation, oxidizing gas secondary activation, washing drying, carbonization and the like, so that the problems of high specific surface area and high mesoporous rate of the super capacity carbon are solved, and the multiplying power performance of the super capacity carbon is improved; CN112265990A provides a preparation method of a furfural residue porous activated carbon material and application of the furfural residue porous activated carbon material in the field of supercapacity, and the activated carbon for the supercapacitor is obtained through steps of pretreatment, pre-carbonization, activation, washing and the like, and the specific surface area of the activated carbon is 1583-2600 m 2 The specific capacity is up to over 300F/g, and provides a method for preparing activated carbon by utilizing a natural substance structure.
Although the patent achieves better effect in the aspect of ultra-volume application, the method for preparing the ultra-volume carbon cannot effectively solve the problem that the volume density and the pore size distribution of the biomass carbon are unreasonable.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
In view of the above and/or other problems in the prior art, the present invention provides a method for preparing biomass activated carbon for a supercapacitor, wherein the biomass activated carbon obtained by the method has a high bulk density, a good pore size distribution and excellent electrochemical properties.
In order to solve the technical problems, the invention provides the following technical scheme: a process for preparing the activated biomass carbon used for super capacitor includes pretreating the carbonized biomass material with sodium persulfate solution, adding adhesive, granulating at ordinary temp, mixing it with activating agent, carbonizing, activating and post-treating.
As a preferred scheme of the preparation method of the biomass activated carbon for the supercapacitor, the method comprises the following steps: the biomass carbonized material comprises one or more of corncobs, walnut shells, straws, coconut shells and wood.
As a preferred scheme of the preparation method of the biomass activated carbon for the supercapacitor, the method comprises the following steps: pretreating with a sodium persulfate solution, crushing the biomass carbonized material, adding the crushed biomass carbonized material into the sodium persulfate solution for soaking, and performing vacuum drying treatment on the composite material obtained after soaking;
wherein the biomass carbonized material is crushed and ground to have a particle size of less than 50 meshes; the concentration of the sodium persulfate is 0.5-8%.
As a preferred scheme of the preparation method of the biomass activated carbon for the super capacitor, the method comprises the following steps: the impregnation adopts mechanical stirring, and the treatment time is 0.5-3 h.
As a preferred scheme of the preparation method of the biomass activated carbon for the super capacitor, the method comprises the following steps: the vacuum drying treatment is carried out at the temperature of 76-85 ℃ for 2-10 h.
As a preferred scheme of the preparation method of the biomass activated carbon for the supercapacitor, the method comprises the following steps: adding a binder to granulate at room temperature, wherein the added binder accounts for 2-13% of the total amount, and the granulated particle size is 0.5-20 mm;
the binder is resin, tar or a mixture of the resin and the tar; wherein the coking value of the resin is not less than 40%, and the coking value of the tar is not less than 20%.
As a preferred scheme of the preparation method of the biomass activated carbon for the super capacitor, the method comprises the following steps: mixing the granulated product with an activating agent, wherein the mass ratio of the granulated product to the activating agent is 1;
wherein the activating agent is potassium hydroxide.
As a preferred scheme of the preparation method of the biomass activated carbon for the supercapacitor, the method comprises the following steps: carrying out carbonization activation treatment under the protective atmosphere of nitrogen; three-stage heating is adopted, the room temperature is raised to 200 ℃, the heating rate is 5-10 ℃/min, and the temperature is kept for 1-2 h; continuously heating to the preactivation temperature of 450-600 ℃, heating at the rate of 3-6 ℃/min, and keeping the temperature for 1-4 h; continuously heating to the activation temperature of 750-850 ℃, heating rate of 3-6 ℃/min, and keeping the temperature for 1-5 h.
As a preferred scheme of the preparation method of the biomass activated carbon for the supercapacitor, the method comprises the following steps: and (3) carrying out post-treatment, namely washing the activated material for multiple times by using dilute hydrochloric acid and deionized water, and drying in vacuum at 110 ℃.
Wherein the concentration of the dilute hydrochloric acid is 1mol/L.
The invention also aims to provide the super-capacity carbon obtained by the preparation method of the biomass activated carbon for the super capacitor, wherein the mesoporous rate of the super-capacity carbon is 23-45%, the average pore size is 2.11-2.34 nm, and the volume density is 0.45-0.51 g/cm 3 ；
When the current density is 1A/g, the specific capacity is 260-320F/g.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, a biomass carbonized material is used as a raw material, two-time recombination of a pore structure of the super-capacity activated carbon is realized through the processes of granulation, activation and the like, the functional groups on the surface of the carbon material are increased in the pretreatment process, and the pore structure is regulated and controlled in the activation process, so that a good pore structure is obtained.
The activated carbon prepared by the invention has very high volume density, solves the problem of low volume density of the traditional commercial super-capacity carbon, and has good electrochemical performance, particularly when the current density is 1A/g, the specific capacity is 260-320F/g.
The method for regulating and controlling the pore size structure of the super-capacity carbon is simple, the large-scale production of the high-quality super-capacity carbon is easy to realize, and the high-added-value application of the biomass material is realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
FIG. 1 is an adsorption isotherm of activated carbon prepared in example 2 of the present invention;
FIG. 2 is a graph showing the distribution of pore diameters of activated carbon obtained in example 2 of the present invention;
FIG. 3 is a charge/discharge curve showing that the current density of the activated carbon obtained in example 3 of the present invention is 1A/g.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below with reference to examples of the specification.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as specifically described herein, and it will be appreciated by those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the present invention and that the present invention is not limited by the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Example 1
(1) Pretreatment: crushing and grinding corncobs until the particle size is below 50 meshes, soaking the corncobs in 0.5% sodium persulfate solution, and mechanically stirring for 0.5h; then dried under vacuum at 76 ℃ for 2h.
(2) And (3) granulation: mixing the corncobs treated in the step (1) with resin, wherein the adding proportion of the resin is 2 percent of the total amount, and granulating by a particle granulator to obtain particles with the particle size of 3mm;
(3) Activation treatment: mixing the product after granulation in the step (2) with potassium hydroxide according to the mass ratio of 1:5, mixing, and carrying out carbonization and activation treatment by three-stage temperature rise under the nitrogen atmosphere. The first stage is as follows: heating the room temperature to 200 ℃, keeping the temperature for 1h, wherein the heating rate is 10 ℃/min; and a second stage: continuously heating to the preactivation temperature of 450 ℃, heating at the speed of 6 ℃/min, and keeping the temperature for 1h; and a third stage: and continuously heating to the activation temperature of 750 ℃, the heating rate of 6 ℃/min and keeping the temperature for 2h.
(4) And (3) post-treatment: and (4) cooling the activated material obtained in the step (3) to room temperature, washing the activated material for multiple times by using dilute hydrochloric acid and deionized water, and drying the washed activated material at the temperature of 110 ℃ to obtain the biomass activated carbon.
And (3) characterizing the obtained biomass activated carbon according to GB/T243339-2019 standard and a helium adsorption and desorption method. The tap density of the biomass activated carbon is 0.45g/cm 3 (ii) a The specific surface area of the biomass activated carbon is 2034m 2 (g) total pore volume of 1.27m 3 G, pore volume of micropores 0.98m 3 The ratio of mesopores to the total pore volume is 23.00%, and the average pore diameter is 2.1nm.
And (3) carrying out electrochemical performance test on the obtained biomass activated carbon, wherein the test is carried out on an electrochemical workstation, a constant-current charging and discharging method is adopted, 6M KOH solution is used as electrolyte, the foamed nickel coated with the biomass activated carbon is used as a working electrode, a platinum sheet electrode is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode.
The test result shows that the specific capacity of the prepared biomass activated carbon is 267F/g under the current density of 1A/g.
Example 2
(1) Pretreatment: crushing and grinding walnut shells to a particle size of below 50 meshes, soaking the walnut shells in a 2% sodium persulfate solution, and mechanically stirring for 2 hours; then dried under vacuum at 80 ℃ for 5h.
(2) And (3) granulation: mixing the corn cobs treated in the step (1) with tar, wherein the addition proportion of the tar is 8% of the total amount, and granulating by using a granule granulator to obtain granules with the particle size of 10mm;
(3) Activation treatment: mixing the product after granulation in the step (2) with potassium hydroxide according to the mass ratio of 1:3, mixing, and carrying out carbonization and activation treatment by three-stage temperature rise under the nitrogen atmosphere. The first stage is as follows: heating the room temperature to 200 ℃, keeping the temperature for 2h at the heating rate of 10 ℃/min; and a second stage: continuously heating to the preactivation temperature of 500 ℃, keeping the temperature rising rate at 5 ℃/min, and keeping the temperature for 3h; and a third stage: and continuously heating to the activation temperature of 800 ℃, keeping the temperature at the heating rate of 5 ℃/min and keeping the temperature for 2 hours.
(4) And (3) post-treatment: and (4) cooling the activated material obtained in the step (3) to room temperature, washing the activated material for multiple times by using dilute hydrochloric acid and deionized water, and drying the washed activated material at the temperature of 110 ℃ to obtain the biomass activated carbon.
And (3) characterizing the obtained biomass activated carbon according to GB/T243339-2019 standard and a helium adsorption and desorption method. The tap density of the biomass activated carbon is 0.45g/cm 3 。
The adsorption isotherm of the prepared biomass activated carbon is shown in FIG. 1, and it can be seen from FIG. 1 that the activated carbon is mainly composed of micropores and has a small amount of mesopores, and the specific surface area of the biomass activated carbon is 2239m 2 (g) total pore volume of 1.20m 3 G, pore volume of micropores 0.86m 3 The ratio of mesopores to the total pore volume is 38.59%.
The pore size distribution diagram of the prepared biomass activated carbon is shown in figure 2, and as can be seen from figure 2, the super-capacity carbon has micropores, ultramicropores and mesopores, and the average pore size is 2.1nm.
And (3) carrying out electrochemical performance test on the obtained biomass activated carbon on an electrochemical workstation, wherein a constant-current charging and discharging method is adopted, 6M KOH solution is used as electrolyte, the foamed nickel coated with the biomass activated carbon is used as a working electrode, a platinum sheet electrode is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode.
The test result shows that the specific capacity of the prepared biomass activated carbon is 280F/g under the current density of 1A/g.
Example 3
(1) Crushing and grinding coconut shells to below 50 meshes, soaking the coconut shells in 6% sodium persulfate solution, and mechanically stirring for 3 hours; then dried under vacuum at 80 ℃ for 6h.
(2) And (3) granulation: mixing the coconut shells treated in the step (1) with resin and tar, wherein the addition proportion of the resin is 6% of the total amount, the addition proportion of the tar is 5% of the total amount, and granulating by a particle granulator to obtain particles with the particle size of 20mm;
(3) Activation treatment: mixing the product after granulation in the step (2) with potassium hydroxide according to the mass ratio of 1:1, and carrying out carbonization and activation treatment by three-stage temperature rise under the nitrogen atmosphere. The first stage is as follows: heating the mixture to 200 ℃ at the room temperature, keeping the temperature for 2h at the heating rate of 5 ℃/min; and a second stage: continuously heating to the preactivation temperature of 600 ℃, heating at the rate of 3 ℃/min, and keeping the temperature for 4h; and a third stage: continuously heating to the activation temperature of 850 ℃, heating at the speed of 3 ℃/min, and keeping the temperature for 5 hours.
(4) And (3) post-treatment: and (4) cooling the activated material obtained in the step (3) to room temperature, washing the activated material for multiple times by using dilute hydrochloric acid and deionized water, and drying the washed activated material at 110 ℃ to obtain the biomass activated carbon.
The obtained biomass activated carbon is characterized according to the GB/T243358-2019 standard and a helium adsorption and desorption method, and the tap density of the obtained biomass activated carbon is 0.50g/cm 3 Specific surface area of 2018m 2 (g) total pore volume of 1.30m 3 A pore volume of the micropores of 0.94m 3 The ratio of mesopores to the total pore volume was 27.65%, and the average pore diameter was 2.30nm.
And (3) carrying out electrochemical performance test on the obtained biomass activated carbon, wherein the test is carried out on an electrochemical workstation, a constant-current charging and discharging method is adopted, 6M KOH solution is used as electrolyte, the foamed nickel coated with the biomass activated carbon is used as a working electrode, a platinum sheet electrode is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode.
The test result is shown in figure 3, and the specific capacity of the biomass activated carbon reaches 320F/g under the current density of 1A/g.
Example 4
(1) Crushing and grinding coconut shells to below 50 meshes, soaking the coconut shells in 0.2% sodium persulfate solution, and mechanically stirring for 3 hours; then vacuum drying for 6h at the temperature of 80 ℃;
(2) And (3) granulation: mixing the coconut shells treated in the step (1) with resin and tar, wherein the addition proportion of the resin is 6% of the total amount, the addition proportion of the tar is 5% of the total amount, and granulating by a particle granulator to obtain particles with the particle size of 20mm;
(3) Activation treatment: and (3) mixing the product after granulation in the step (2) with potassium hydroxide according to the mass ratio of 1:1, and carrying out carbonization and activation treatment by three-stage heating under the nitrogen atmosphere. The first stage is as follows: heating the mixture to 200 ℃ at the room temperature, keeping the temperature for 2h at the heating rate of 5 ℃/min; and a second stage: continuously heating to the preactivation temperature of 600 ℃, heating at the rate of 3 ℃/min, and keeping the temperature for 4h; and a third stage: continuously heating to the activation temperature of 850 ℃, heating at the speed of 3 ℃/min, and keeping the temperature for 5 hours.
(4) And (3) post-treatment: and (4) cooling the activated material obtained in the step (3) to room temperature, washing the activated material for multiple times by using dilute hydrochloric acid and deionized water, and drying the washed activated material at 110 ℃ to obtain the biomass activated carbon.
The obtained biomass activated carbon is characterized according to the GB/T243358-2019 standard and a helium adsorption and desorption method, and the tap density of the obtained biomass activated carbon is 0.30g/cm 3 The specific surface area is 1580m 2 (g) total pore volume of 1.08m 3 G, pore volume of micropores 0.74m 3 The ratio of mesopores to the total pore volume was 39.74%, and the average pore diameter was 3.30nm.
And (3) carrying out electrochemical performance test on the obtained biomass activated carbon, wherein the test is carried out on an electrochemical workstation, a constant-current charging and discharging method is adopted, 6M KOH solution is used as electrolyte, the foamed nickel coated with the biomass activated carbon is used as a working electrode, a platinum sheet electrode is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode.
The specific capacity of the biomass activated carbon reaches 123F/g under the electrochemical test result of 1A/g current density.
The invention takes biomass carbonized material as raw material, realizes twice recombination of the pore structure of the super-capacity activated carbon by the working procedures of granulation, activation and the like, increases the functional groups on the surface of the carbon material by utilizing the pretreatment process and regulates the pore structure by utilizing the activation process, and obtains good pore diameter structure (the mesoporous rate is 23-45 percent, and the average pore diameter is 2.1-2.3 nm).
The active carbon prepared by the invention has very high tap density (the volume density is 0.45-0.51 g/cm) 3 ) Solves the problem of low volume density of the traditional commercial super-capacity carbon, and has good electrochemical performance, especially when the current density is 1A/g, the specific volumeThe amount is 260 to 320F/g.
The method for regulating and controlling the pore diameter structure of the super-capacity carbon is simple, the large-scale production of the high-quality super-capacity carbon is easy to realize, and the high value-added application of biomass materials is realized.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (8)
1. A preparation method of biomass activated carbon for a supercapacitor is characterized by comprising the following steps: pretreating a biomass carbonized material by using a sodium persulfate solution, adding a binder for granulating at room temperature, mixing a granulated product with an activating agent for carbonization and activation, and performing post-treatment to obtain spherical activated carbon;
the binder is resin, tar or a mixture of the resin and the tar; the activating agent is potassium hydroxide;
the biomass carbonized material comprises one or more of corncobs, walnut shells, straws, coconut shells and wood;
carrying out carbonization activation treatment under the protective atmosphere of nitrogen; heating in three stages to 200 ℃ at room temperature, wherein the heating rate is 5 to 10 ℃/min, and keeping the temperature for 1 to 2 hours; continuously heating to the preactivation temperature of 450-600 ℃, the heating rate of 3~6 ℃/min, and keeping the temperature for 1-4 h; and continuously heating to the activation temperature of 750-850 ℃, the heating rate of 3~6 ℃/min, and keeping the temperature for 1-5 h.
2. The process for the preparation of biomass activated carbon for supercapacitors as claimed in claim 1, wherein: pretreating with a sodium persulfate solution, crushing the biomass carbonized material, adding the crushed biomass carbonized material into the sodium persulfate solution for soaking, and performing vacuum drying treatment on the composite material obtained after soaking;
wherein the biomass carbonized material is crushed and ground to have a particle size of less than 50 meshes; the concentration of the sodium persulfate is 0.5 to 8 percent.
3. The process for the preparation of biomass activated carbon for supercapacitors as claimed in claim 2, wherein: the impregnation is carried out by adopting mechanical stirring, and the treatment time is 0.5 to 3 hours.
4. The process for the preparation of biomass activated carbon for supercapacitors as claimed in claim 2, wherein: and (3) carrying out vacuum drying treatment at the temperature of 76-85 ℃ for 2-10 h.
5. The method of making biomass activated carbon for a supercapacitor of any one of claims 1~4, wherein: adding a binder to carry out granulation at room temperature, wherein the added binder accounts for 2-13% of the total amount, and the particle size after granulation is 0.5-20 mm;
wherein the coking value of the resin is not less than 40%, and the coking value of the tar is not less than 20%.
6. The process for the preparation of biomass activated carbon for supercapacitors as claimed in claim 5, wherein: and mixing the granulated product with an activating agent, wherein the mass ratio of the granulated product to the activating agent is 1.
7. The process for making biomass activated carbon for supercapacitors as claimed in any of claims 1~4, 6 wherein: the post-treatment comprises the steps of washing the activated material for multiple times by using dilute hydrochloric acid and deionized water, and drying in vacuum at 110 ℃;
wherein the concentration of the dilute hydrochloric acid is 1mol/L.
8. The super capacitor activated carbon prepared by the method for preparing the bio-activated carbon according to any one of claims 1~7, wherein: the mesoporous rate of the super-capacity carbon is 23 to 45 percent, the average aperture size is 2.1 to 2.3nm, and the volume density is 0.45 to 0.51g/cm 3 ；
When the current density is 1A/g, the specific capacity is 260 to 320F/g.
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