CN111320172B - Directional synthesis method and application of biomass activated carbon-based electrode material containing micropore-mesoporous pore canal - Google Patents

Directional synthesis method and application of biomass activated carbon-based electrode material containing micropore-mesoporous pore canal Download PDF

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CN111320172B
CN111320172B CN202010128215.7A CN202010128215A CN111320172B CN 111320172 B CN111320172 B CN 111320172B CN 202010128215 A CN202010128215 A CN 202010128215A CN 111320172 B CN111320172 B CN 111320172B
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electrode material
activated carbon
biomass
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gulfweed
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CN111320172A (en
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郭飞强
贾小芃
梁爽
占银玻
周惠明
钱琳
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China University of Mining and Technology CUMT
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    • C—CHEMISTRY; METALLURGY
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    • C01B32/00—Carbon; Compounds thereof
    • C01B32/30—Active carbon
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    • C01B32/318—Preparation characterised by the starting materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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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
    • C01B32/342—Preparation characterised by non-gaseous activating agents
    • C01B32/348—Metallic compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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
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    • H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
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    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Abstract

The invention discloses a directional synthesis method and application of a biomass activated carbon-based electrode material containing micropore-mesoporous pore canals. Using gulfweed as raw material, introducing NH3·H2The method has the advantages that the biomass is pretreated, chemical bonds among cellulose/hemicellulose/lignin are broken, the chemical activity of the material is enhanced, part of lignin is removed, the cellulose/hemicellulose proportion is improved, the 'hard carbon' is removed, the activating agent is enabled to permeate into the carbon fiber structure more efficiently, the pore etching is enhanced by means of defects formed after the lignin is removed, the formation of a three-dimensional porous pore channel is promoted, and the response capability of the material to large current is remarkably improved. The method for preparing the electrode material of the supercapacitor by using the marine biomass has the advantages of simple preparation process, low cost, little pollution, higher mass specific capacitance, excellent cycle stability and rate capability, is a process for changing waste into valuable with potential application value, and is beneficial to realizing large-scale industrial synthesis.

Description

Directional synthesis method and application of biomass activated carbon-based electrode material containing micropore-mesoporous pore canal
Technical Field
The invention belongs to the technical field of energy chemical engineering of energy storage materials and biomass solid waste recycling, and particularly relates to a directional synthesis method and application of a biomass activated carbon-based electrode material containing micropore-mesoporous pore canals.
Background
As a green energy storage tool, super capacitors have been increasingly regarded as important because of their high specific capacitance, excellent cycle performance, long cycle life and charge/discharge rate. Nowadays, supercapacitors are widely used in the fields of hybrid vehicles, portable electronic devices, electrical devices, medical devices, and the like. Supercapacitors are generally classified into electric double layer capacitors and pseudocapacitors based on their charge storage mechanism. Electric double layer capacitors store electrical energy by electrostatic adsorption of highly reversible charges at the electrode-electrolyte interface, while pseudocapacitors store energy by redox reactions occurring at the electrode surface. In general, electrode materials are one of the important factors affecting the performance of supercapacitors, and therefore, the importance of the research is also focused on, and the research is motivated to continuously try to synthesize novel electrode materials.
The porosity and the conductivity of the electrode material are key factors influencing the electrochemical performance of the super capacitor, and respectively have important influence on the charge storage capacity and the electrochemical impedance of the material. Carbon materials are considered to be the most promising supercapacitor electrode materials because they are lower in cost, and have good electrical conductivity, environmental friendliness, and chemical stability, compared to metal oxides and conductive polymers. The graphene mainly comprises activated carbon, graphene and carbon nanotubes. Among these carbon electrode materials, graphene and carbon nanotubes require relatively complicated and costly preparation processes, and are not suitable for mass production. Biomass-based activated carbon has become the most potential electrode material due to its advantages of low cost, high reproducibility and good economy. Activated carbon prepared based on biomass generally has a high specific surface area and a three-dimensional pore structure, which makes it potential as an electrode material for supercapacitors.
The preparation method of the electrode material of the super capacitor generally comprises a physical activation method and a chemical activation method. In the physical activation method, a carbide is usually activated by contacting with a gas such as steam or carbon dioxide at a high temperature, and these oxidizing gases react with carbon atoms in the carbide to open pores in addition to the initial pores, thereby forming a developed pore structure. The chemical activation method is to mix a chemical activator with raw materials and heat the mixture under an inert atmosphere. Commonly used activators are inorganic salts, hydroxides of alkali metals, alkaline earth metals and certain acids. Common chemical activation methods include KOH activation and ZnCl2Activation method and H3PO4The activated carbon prepared by the KOH activation method has excellent performance, and the pore structure and the specific surface area of the activated carbon are easy to adjust and control. Therefore, a method for preparing activated carbon using KOH as an activating agent is favored by many researchers at home and abroad.
Due to the relatively low degree of graphitization and the relatively poor ability of biomass carbon-based materials to respond to charge and discharge currents relative to other materials, as influenced by specific surface area and activation processes, researchers have focused more on the directed synthesis of pore structures in recent years to achieve enhanced and improved performance with these structures.
CN108335917A discloses a preparation method of orderly arranged reduced graphene oxide. Carrying out surface modification on graphene oxide by using ionic liquid, carrying out ultrasonic stirring on the modified graphene oxide and a polymer to form an electrostatic spinning solution, then carrying out electrostatic spinning on the solution, and carrying out heat treatment to obtain an RGO embedded composite material vertically and orderly arranged on the surface of carbon nanofiber, wherein the RGO embedded composite material is prepared at 1A g-1Has a current density of 232F g-1Mass to capacitance.
CN106554011A discloses a preparation method of three-dimensional ordered macroporous-mesoporous graphene, which comprises the steps of immersing orderly-stacked organic polymer template spheres into a ceramic precursor solution, obtaining three-dimensional porous ceramic through a series of treatments, growing graphene on a ceramic substrate by using a chemical vapor deposition method, and finally removing the ceramic template to obtain the three-dimensional ordered macroporous-mesoporous graphene which is 1A g times that of the three-dimensional ordered macroporous-mesoporous graphene-1Has a current density of 325F g-1Mass to capacitance.
Although the above-mentioned conventional methods for directional synthesis have their advantages, they have the disadvantage that expensive precursors such as graphene and carbon nanotubes are used, and the process is not economical and simplified, which results in complicated process and high preparation cost. In addition, the prepared electrode material has poor response capability to charge and discharge current under high current density, and needs to be further improved.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a directional synthesis method and application of a biomass activated carbon-based electrode material containing micropore-mesoporous pore canals, wherein a gulfweed raw material is soaked in NH3·H2And (3) heating in water bath in the O solution, then carrying out carbonization-activation treatment on the product to obtain the biomass carbon-based electrode material, and generating a large number of mesoporous channels on the basis of the originally developed pore structure. The method has the advantages of simple preparation steps, low cost of raw materials and process, and high specific capacitance and strong response capability to high current density of the prepared electrode material.
A directional synthesis method of biomass active carbon-based electrode material containing micropore-mesoporous pore canal takes gulfweed which grows rapidly and is rich in multiple elements as a precursor, and NH is introduced3·H2O directionally dissolves and removes partial lignin components, relaxes the chemical structure of gulfweed and selectively constructs incomplete pores of a gulfweed matrix, so that a KOH activator is directionally impregnated in the treated gulfweed matrix along the incomplete pores, carbon-based mesoporous channels uniformly distributed are constructed through an activation reaction, and a large number of micropores are formed on the surfaces of the mesoporous channels, so that an active carbon electrode material with a high specific surface area and communicated with the micropores is prepared, the active carbon electrode material realizes efficient adsorption of ions by the micropores, and the mesoporous channels strengthen rapid transmission of the ions, so that high specific capacitance is obtained.
The directional synthesis method of the biomass activated carbon-based electrode material containing the micropore-mesopore pore canal comprises the following steps:
step 1, washing a gulfweed raw material with deionized water, drying at 105 ℃ for 72 hours, crushing with a crusher, and sieving with a 80-mesh sieve to obtain gulfweed powder;
step 2, respectively weighing 10 wt.% of NH3·H2Mixing O and Sargassum powder, sealing, heating in water bath at 80 deg.C for 12 hr, drying, and pulverizing to 80 mesh to obtain Sargassum powder pretreated with ammonia water;
step 3, putting the gulfweed powder pretreated by the ammonia water into an atmosphere tube furnace, and performing reaction in N2Under atmosphereCarbonizing, crushing and sieving by a 80-mesh sieve to obtain sargassum semi-coke;
step 4, mixing the gulfweed semicoke and KOH, putting the mixture into an atmosphere tube furnace, and adding N2Activating in an atmosphere;
step 5, using 1mol L of the activated mixture-1Washing with hydrochloric acid, washing with a large amount of deionized water to make the pH value neutral, and drying to obtain the biomass activated carbon-based electrode material.
As an improvement, the specific surface area of the activated carbon obtained in the step 5 can reach 3000m2 g-1。
As a modification, the NH in step 23·H2The ratio of O to sargassum powder was 100mL:10 g.
As a modification, the temperature increase rate in the step 3 is 5 ℃ min-1The carbonization temperature is 600 ℃, and the carbonization time is 3 h.
The improvement is that in the step 4, the mass ratio of the gulfweed semicoke to the KOH is 1:4, and the heating rate is 10 ℃ min-1The activation temperature is 800 ℃, and the activation time is 2 h.
The improvement is that the molar ratio of hydrochloric acid in step 5 to KOH in step 4 is 1.5: 1.
The biomass activated carbon-based electrode material is applied to preparing an electrode of a supercapacitor.
According to the application, the biomass activated carbon-based electrode material, acetylene black and PTFE are mixed in a mortar according to the mass ratio of 8:1:1, ethanol is added to mix the materials uniformly, about 10mg of the mixture is smeared on foamed nickel, tabletting is carried out for 30s under the pressure of 10MPa, and drying is carried out to ensure that the ethanol is completely removed, so that the biomass carbon-based electrode containing mesoporous pore canals is obtained.
Has the advantages that:
the invention takes sargassum as raw material and introduces NH3·H2O is used as a pretreatment agent to remove part of lignin and strengthen the activation effect, KOH is used as an activating agent to realize the preparation of the activated carbon by a carbonization-activation two-step method, and the activated carbon is applied to the electrode material of the super capacitor.
Compared with the prior art, the invention has the advantages that:
1. the raw materials have wide sources and low cost. In the aspect of selecting raw materials of electrode materials, the materials such as graphene and carbon nano tubes cannot realize large-scale production due to high price, and gulfweed is used as a marine waste, so that the growth period is short, the collection cost is low, the source is wide and stable, and the gulfweed is an excellent biomass raw material;
2. NH is introduced in the preparation process3·H2And O, pretreating the biomass raw material to generate a compact fiber structure of a swelling relaxation precursor, breaking chemical bonds among cellulose/hemicellulose/lignin, and strengthening the generation of a three-dimensional porous carbon structure while directionally removing hard carbon. Meanwhile, the activator takes the defect after removing the lignin as a substrate to further etch micropores, the contact between the activator and the amorphous carbon is enhanced, mesoporous channels are further grown on the material on the basis of reserving a large number of micropores, and the response capability of the material to large current is effectively improved;
3. as a marine biomass, gulfweed contains a large amount of nitrogen (4.13%) and sulfur (1.28%), is easy to self-assemble in the activation process to realize nitrogen/sulfur autodoping, can reduce the introduction of additional chemical reagents, reduces the preparation cost and reduces the environmental pollution.
Drawings
FIG. 1 is a flow chart of the preparation of a bioactive carbon-based electrode material;
FIG. 2 is a HRTEM image of a biomass-activated carbon-based electrode material, (a) at scale 100 nm; (b) 20nm for scale; (c) scale 5 nm;
FIG. 3 is an XRD spectrum of a material of a bioactive carbon-based electrode;
FIG. 4 is a Raman spectrum of a bioactive carbon-based electrode material;
FIG. 5 is an XPS spectrum of a biomass activated carbon-based electrode material, (a) is C1 s; (b) is O1 s;
FIG. 6 shows the pore structure of the electrode material, wherein (a) is a nitrogen adsorption/desorption curve, and (b) is a pore size distribution diagram;
FIG. 7 is a cyclic voltammogram of a biomass activated carbon electrode;
FIG. 8 is a constant current charge-discharge diagram of a biomass activated carbon electrode;
FIG. 9 is an electrochemical impedance spectrum of a biomass activated carbon electrode;
FIG. 10 is a graph of the cycling stability of a bioactivated carbon electrode;
fig. 11 is a schematic drawing of a biomass activated carbon electrode.
Detailed Description
The present invention will now be described in detail with reference to fig. 1-11 and specific examples, which are not intended to limit the scope of the invention, but technical means used in the examples, unless otherwise specified, are conventional in the art.
Example 1
The flow chart of the biomass activated carbon-based electrode material is shown in figure 1.
Taking a proper amount of dried sargassum, fully washing and drying at 105 ℃ for 72h, crushing the sargassum into powder by using a crusher, and sieving the sargassum powder by using a 80-mesh sieve.
Taking 10g sargassum powder in a beaker, adding NH3·H2And (3) sealing the O (5 wt.%) solution by using a preservative film, placing the O (5 wt.%) solution in a water bath kettle, heating the O (5 wt.%) solution in a water bath kettle for 80 ℃, heating the O (5 wt.%) solution in a water bath for 12 hours, then placing the mixture in a drying box for drying, crushing the obtained solid again, and sieving the solid by using a sieve with 80 meshes to obtain the gulfweed powder pretreated by using ammonia water.
Putting sargassum powder pretreated by ammonia water into a boat, putting into an atmosphere tube furnace, carbonizing at 600 deg.C for 3 hr at a temperature rise rate of 5 deg.C/min under nitrogen atmosphere-1And crushing the obtained biomass semi-coke again and sieving the crushed biomass semi-coke through a 80-mesh sieve.
Putting 2g of gulfweed semicoke and 8g of KOH in a boat, adding 5mL of deionized water to uniformly mix, and heating at 80 ℃ for 30min to obtain a slurry-like mixture. Placing the slurry mixture into an atmosphere tube furnace, activating at 800 deg.C for 2h in nitrogen atmosphere, and heating at 10 deg.C/min-1。
The activated mixture was ground and crushed, and 200mL of hydrochloric acid (1 mol. L) was poured-1) Sealed by preservative filmThen heating the solution in water bath at 60 ℃ for 2h, and then carrying out suction filtration and drying on the solution to obtain the biomass activated carbon-based electrode material.
Grinding the obtained biomass activated carbon-based electrode material until the particle size of the biomass activated carbon-based electrode material is 200 meshes, mixing the biomass activated carbon-based electrode material and acetylene black in a mortar according to the mass ratio of 8:1:1, and adding ethanol to uniformly mix the biomass activated carbon-based electrode material and the PTFE. Applying about 10mg of the mixture to 1cm2And (3) tabletting for 30s under the pressure of 10MPa on the foamed nickel, and drying to obtain the biomass carbon-based electrode material.
Example 2
Taking a proper amount of dried gulfweed, fully washing and drying at 105 ℃ for 72h, crushing the gulfweed into powder by a crusher, and sieving the powder by a 80-mesh sieve.
10g of the powder was placed in a beaker, NH was added3·H2And (3) sealing the solution with a preservative film, placing the sealed solution in a water bath kettle, heating the sealed solution for 12 hours in a water bath at 80 ℃, then placing the mixture in a drying box, evaporating the mixture to dryness, crushing the obtained solid again, and sieving the crushed solid with a 80-mesh sieve to obtain the gulfweed powder pretreated by ammonia water.
Putting sargassum powder pretreated by ammonia water into a boat, putting into an atmosphere tube furnace, carbonizing at 600 deg.C for 3 hr at a temperature rise rate of 5 deg.C/min under nitrogen atmosphere-1. The obtained biomass semi-coke is crushed again and passes through a 80-mesh screen.
2g of semicoke and 8g of KOH are put in a boat, 5mL of deionized water is added to be uniformly mixed, and the mixture is heated at the temperature of 80 ℃ for 30min to obtain a slurry-like mixture. Placing the slurry mixture into an atmosphere tube furnace, activating at 800 deg.C for 2h in nitrogen atmosphere, and heating at 10 deg.C/min-1。
The activated mixture was ground and crushed, and 200mL of hydrochloric acid (1mol L) was poured-1) And sealing the electrode material by using a preservative film, heating the electrode material in water bath at 60 ℃ for 2 hours, then carrying out suction filtration on the solution, and drying the solution to obtain the biomass activated carbon-based electrode material.
Grinding the biomass activated carbon-based electrode material to 200 meshes, and mixing the biomass activated carbon-based electrode material, acetylene black and PTFE (polytetrafluoroethylene) in a mortar according to the mass ratio of 8:1:1Several drops of ethanol were added to mix well. Applying about 10mg of the mixture to 1cm2And (3) tabletting for 30s under the pressure of 10MPa on the foamed nickel, and drying to obtain the biomass carbon-based electrode material.
Example 3
Taking a proper amount of dried gulfweed, fully washing and drying at 105 ℃ for 72h, crushing the gulfweed into powder by a crusher, and sieving the powder by a 80-mesh sieve.
10g of the powder was placed in a beaker, NH was added3·H2And (3) sealing the solution with a preservative film, placing the sealed solution in a water bath kettle, heating the sealed solution for 12 hours in a water bath at 80 ℃, then placing the mixture in a drying box, evaporating the mixture to dryness, crushing the obtained solid again, and sieving the crushed solid with a 80-mesh sieve to obtain the gulfweed powder pretreated by ammonia water.
Putting sargassum powder pretreated by ammonia water into a boat, putting into an atmosphere tube furnace, carbonizing at 600 deg.C for 3 hr at a temperature rise rate of 5 deg.C/min under nitrogen atmosphere-1. The obtained biomass semi-coke is crushed again and passes through a 80-mesh screen.
Putting 2g of gulfweed semicoke and 8g of KOH in a boat, adding 5mL of deionized water to uniformly mix, and heating at 80 ℃ for 30min to obtain a slurry-like mixture. Placing the slurry mixture into an atmosphere tube furnace, activating at 800 deg.C for 2h in nitrogen atmosphere, and heating at 10 deg.C/min-1。
The activated mixture was ground and crushed, and 200mL of hydrochloric acid (1mol L) was poured-1) And sealing the electrode material by using a preservative film, heating the electrode material in water bath at 60 ℃ for 2 hours, then carrying out suction filtration on the solution, and drying the solution to obtain the biomass activated carbon-based electrode material.
Grinding the biomass activated carbon-based electrode material to 200 meshes, mixing the biomass activated carbon-based electrode material with acetylene black and PTFE (polytetrafluoroethylene) in a mortar according to the mass ratio of 8:1:1, and adding a few drops of ethanol to uniformly mix the materials. Applying about 10mg of the mixture to 1cm2And (3) tabletting for 30s under the pressure of 10MPa on the foamed nickel, and drying to obtain the biomass carbon-based electrode material.
The biomass carbon-based electrode materials prepared in examples 1-3 are characterized and electrochemicallyPerforming performance test, namely performing CV, GCD and EIS electrochemical test on the electrode plate under a two-electrode system, wherein the used electrolyte is 6mol L-1The KOH solution is used for adjusting parameters such as scanning speed, current density and the like to obtain electrochemical performance parameters of the electrode material under different working conditions, and further calculating and solving the parameters of mass specific capacitance, circulation stability, multiplying power performance and alternating current impedance of the electrode, wherein the calculation formula of each parameter is as follows:
Figure BDA0002395056990000071
wherein C ismIs the mass specific capacitance of the sample, in F g-1(ii) a I is current in mA; Δ t is the discharge time in units of s; m is the loading of active substances on the electrode sheet, and the unit is mg; Δ V is the discharge drop in V.
Figure BDA0002395056990000072
Figure BDA0002395056990000073
Wherein E is the energy density in W h kg-1；CmIs the mass specific capacitance of the sample, in F g-1(ii) a Δ V is the discharge voltage drop in units of V; p is the energy density in W kg-1(ii) a Δ t is the discharge time in units of s.
Figure BDA0002395056990000074
Wherein ScIs a cycle stability parameter; c5,1Is at 5A g-1Current density of (1) measured specific capacitance by mass F g-1；C5,5000Is at 5A g-1Current density of (2) mass specific capacitance measured at 5000 th time in F g-1。
Figure BDA0002395056990000075
Wherein SRIs a rate performance parameter; c1Is at 1A g-1Current density of F g-1；C10Is at 10A g-1Current density of (2) mass specific capacitance measured at 5000 th time in F g-1。
The results obtained were as follows:
as shown in fig. 2(a), 2(b) and 2(c), the biomass activated carbon-based electrode material HRTEM shows that a sample treated by ammonia water generates an obvious mesoporous channel structure, so that the specific capacitance of the material can be effectively improved, and the ion transmission capability can be enhanced;
FIGS. 3 and 4 are XRD and Raman spectra of the sample, respectively, from which two typical carbon diffraction peaks at 26 and 44 are observed, and I in the Raman spectrumDAnd IGThe ratio of (A) to (B) is 0.94, which indicates that the sample is a carbon material mainly containing amorphous carbon and having a certain graphite microcrystal structure;
fig. 5(a) and 5(b) are XPS spectra of a sample, from which it can be observed that the presence of oxygen-containing functional groups can effectively improve the hydrophilicity of the material, thereby improving the utilization rate of the specific surface area of the material and providing more active sites for charge storage;
fig. 6(a) and fig. 6(b) are a nitrogen adsorption analysis curve and a pore size distribution of a sample, respectively, the nitrogen adsorption desorption curve of the sample is an IV isotherm, which indicates that the material contains not only a large number of micropores but also mesopores, and the same conclusion can be obtained from the pore size distribution, the carbon material contains a large number of micropores below 2nm, which can provide a large amount of specific surface area and charge storage sites, and a large number of mesopores between 2nm and 4nm, which have small pore sizes, so that the material can provide the specific surface area, and at the same time, can effectively enhance the ion transport capacity, improve the response capability of the capacitor to large current, and reduce the influence of polarization;
FIG. 7 andFIG. 8 shows the cyclic voltammetry curve and the constant current charging and discharging curve of the electrode, the cyclic voltammetry curve of the sample has a good rectangular shape, the constant current charging and discharging curve is a good isosceles triangle shape, which shows that the internal resistance of the material is small, and the mass specific capacitance of the electrode is 1A g according to the calculation formula of the two-electrode capacitor-1At time 336F g-1At 10A g-1When it is 277F g-1The capacity retention rate is 82%, and the electrode has excellent rate performance;
FIG. 9 is an electrochemical impedance spectrum of an electrode whose intrinsic resistance (R) ise) 1.51 omega, charge transfer resistance (R)ct) Is 0.43 omega;
FIGS. 10 and 11 are graphs of the cycling stability test and Ragong of the electrode at 5A g -15000 cycles of charge and discharge tests were carried out on the electrode at a current density of (1), and it finally had a capacity retention ratio of 87% (before charging: 286F g)-1And after charging: 248F g-1) It is shown that the electrochemical stability is strong, and is 1A g in the Ragong diagram-1Has a current density of 44W h kg and a potential window of 0-1V-1Energy density of 2441W kg-1When the current density is increased to 5A g-1When the power density of the material is increased to 11134W kg-1The corresponding energy density is only reduced to 32 Wkg-1。
Comparative example 1
Taking a proper amount of dried gulfweed, fully washing and drying at 105 ℃ for 72h, crushing the gulfweed into powder by a crusher, and sieving the powder by a 80-mesh sieve.
Putting Sargassum powder into boat, putting into atmosphere tube furnace, carbonizing at 600 deg.C for 3 hr at heating rate of 5 deg.C/min under nitrogen atmosphere-1And crushing the obtained biomass semi-coke again and sieving the crushed biomass semi-coke through a 80-mesh sieve.
Putting 2g of gulfweed semicoke and 8g of KOH in a boat, adding 5mL of deionized water to uniformly mix, and heating at 80 ℃ for 30min to obtain a slurry-like mixture. Placing the slurry mixture into an atmosphere tube furnace, activating at 800 deg.C for 2h in nitrogen atmosphere, and heating at 10 deg.C/min-1。
The activated mixture was ground and crushed, and 200mL of hydrochloric acid (1 mol. L) was poured-1) And sealing the electrode material by using a preservative film, heating the electrode material in water bath at 60 ℃ for 2 hours, and then carrying out suction filtration and drying on the solution to obtain the biomass activated carbon-based electrode material containing the mesoporous channel.
Grinding the biomass activated carbon-based electrode material to 200 meshes, mixing the biomass activated carbon-based electrode material with acetylene black and PTFE (polytetrafluoroethylene) in a mortar according to the mass ratio of 8:1:1, and adding a few drops of ethanol to uniformly mix the materials. Applying about 10mg of the mixture to 1cm2And (3) tabletting for 30s under the pressure of 10MPa on the foamed nickel, and drying to obtain the biomass carbon-based electrode material. The specific surface area is 2465m2 g-1At 1A g-1Current density of 290F g-1。
Comparative example 2
Immersing the orderly stacked organic polymer template ball to the concentration of 0.5-2.0mol L-1After separation and drying, the ceramic precursor solution is subjected to heat treatment at 800 ℃ for 4-24h at 300-. Growing graphene by using a chemical vapor deposition method and taking three-dimensional porous ceramic as a substrate, and introducing 5-50mL L of carbon source-1Hydrogen 5-50mL L-15-500mL of argon-1The growth temperature is 600-1200 ℃, and the growth time is 30-180 min. And (3) putting the obtained graphene three-dimensional composite material into etching liquid, wherein the etching liquid is at least one of hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid, hydrofluoric acid, hydrogen peroxide, and a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, and directly performing vacuum drying, freeze drying or supercritical drying after removing the template to obtain the three-dimensional ordered macroporous-mesoporous graphene. The electrode material produced is 1A g-1Has a current density of 325F g-1The mass specific capacitance and the energy density of the capacitor reach 12.0W h kg-1At 6.0kW kg-1At a power density of 7.17 Whhkg-1The energy density of (1).
Comparative example 3
By the Hummer methodPreparing graphene oxide, slowly adding 10.0g of 1000-5000 meshes natural crystalline flake graphite into a 2000mL beaker filled with 200mL-400mL of concentrated sulfuric acid under the stirring condition, keeping the temperature at 0 +/-1 ℃, then slowly adding a mixture of 4.0g-6.0g of sodium nitrate and 20.0g-40.0g of potassium permanganate, stirring for 2 hours at the temperature of 0 +/-1 ℃ to ensure that the reaction is complete, stirring for 30 minutes under the water bath condition of 35 +/-3 ℃, then slowly adding 460mL of water, heating to 98 ℃ and maintaining for 15 minutes, diluting to 1400mL with warm water, adding 0.5g of hydrogen peroxide, filtering, fully washing with 5% hydrochloric acid to ensure that the sulfate radical is completely removed, and fully washing at 50 ℃ to remove the sulfate radical P at 50 DEG C2O5Drying in vacuum for 24h in the presence of oxygen, sealing and storing to prepare the graphene oxide aqueous solution with the O/C ratio of 0.3-0.5. And (3) treating the aqueous solution by using an ultrasonic crusher, wherein the ultrasonic frequency is 60.0KHz-100.0KHz, the power is 1.0KW-3.0KW, and the treatment time is 10min-30min, so as to obtain the graphene oxide dispersion solution with the thickness of a graphene oxide sheet layer of 10.0nm-30.0nm and the size of the graphene oxide sheet layer of 0.1 mu m-2 mu m. And (3) carrying out deacidification and deionization purification on the graphene oxide dispersion solution in deionized water by adopting a semipermeable membrane, replacing the deionized water outside the semipermeable membrane every 6h until the pH value of the solution outside the semipermeable membrane is 7, and carrying out vacuum drying on the obtained graphene oxide at 40 ℃ for 12h for later use. Dissolving 10.0g of graphene oxide in deionized water, adding 0.1g to 0.5g of ionic liquid (the ionic liquid is ionic liquid containing carboxyl, sulfonic group, amino or hydroxyl, such as 1, 2-dimethyl-3-hydroxyethyl imidazole p-methyl benzene sulfonate, 1, 2-dimethyl-3-hydroxyethyl imidazole bis (trifluoromethanesulfonyl) imide salt, 1, 2-dimethyl-3-hydroxyethyl imidazole hexafluorophosphate and the like), carrying out surface modification on the graphene oxide at 60 ℃ for 6 hours, then carrying out centrifugal separation for 10min to 30min under the condition of 10000 r/min to 12000 r/min, removing supernatant, taking out the ionic liquid modified graphene oxide at the bottom, and drying for 12 hours at 40 ℃. Adding 1.0g of ionic liquid modified graphene oxide and a polymer into a solvent (the polymer is one of polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polybenzimidazole and polyimide) according to the mass ratio of 1:100-10:100, wherein the solvent is one of N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydroxypyran, concentrated sulfuric acid, acetic acid, dichloromethane and tetrachloromethaneSeed) is stirred for 4.0h to 8.0h under the action of 300W ultrasonic waves to form an electrostatic spinning solution with the ionic liquid surface modified graphene oxide and the polymer content of 20.0 wt.% to 30.0 wt.%. Performing electrostatic spinning on the solution, wherein the electrostatic spinning distance is 8.0cm-12.0cm, the voltage is 5.0kV-10.0kV, and the flow rate is 3.0mL h-1-5.0mL h-1. Followed by heat treatment at 0.3 deg.C for min in air-1-0.5℃min-1At a rate of from room temperature to 120 ℃ and held at a constant temperature for 2h at 0.5 ℃ for min-1-1.5℃min-1Then the temperature is raised to 280 ℃ and kept constant for 2 hours, and the temperature is raised to 3.0 ℃ for min in the argon atmosphere-1-5.0℃min-1Then the temperature is raised to 1000 ℃ and the temperature is kept for 2h, thus obtaining the RGO embedded composite material which is vertically and orderly arranged on the surface of the carbon nanofiber. Its specific capacitance is 223.1F g-1-231.6F g-1。
It is clearly seen that the reaction is not accompanied by NH3·H2Sample comparison of O, NH3·H2The introduction of O obviously improves the specific surface area and the specific capacitance of the material, wherein the specific capacitance is 336F g respectively-1And 290F g-1. Compared with the prior art, the prior art mostly prepares the electrode material by using a template method or directional synthesis of the material as a background, the process is complicated, the preparation cost is also increased, and a large amount of chemical reagents introduced in the process also cause burden to the environment. The invention takes biomass as a precursor, adopts a physical-chemical activation method to prepare the electrode material of the super capacitor, has short process flow, and the prepared electrode material has excellent performance, compared with the comparative example 2, the material of the invention is 1A g-1Respectively has an energy density of 44 Wh kg-1And 12.0 Wkg-1The mass-to-capacitance ratios were 336F g, respectively, as compared with comparative example 3-1And 223.1F g-1All have obvious promotion.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and any simple modifications or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope of the present invention are within the scope of the present invention.

Claims (7)

1. A directional synthesis method of a biomass activated carbon-based electrode material containing micropore-mesoporous pore canals is characterized in that gulfweed which grows rapidly and is rich in various elements is used as a precursor, and NH is introduced3·H2The method comprises the following steps of removing part of lignin components through oriented dissolution of O, relaxing a sargassum chemical structure, selectively constructing incomplete pores of a sargassum matrix, realizing oriented impregnation of a KOH activator along the incomplete pores in the treated sargassum matrix, constructing uniformly distributed carbon-based mesoporous channels through an activation reaction, and forming a large number of micropores on the surfaces of the mesoporous channels, so that an activated carbon electrode material with a high specific surface area and communicated micropores with the mesoporous channels is prepared, wherein the activated carbon electrode material realizes efficient adsorption of ions by the large number of micropores, and the mesoporous channels strengthen rapid transmission of the ions, so that high specific capacitance is obtained, and the method comprises the following steps:
step 1, washing a gulfweed raw material with deionized water, drying at 105 ℃ for 72 hours, crushing with a crusher, and sieving with a 80-mesh sieve to obtain gulfweed powder;
step 2, respectively weighing 10 wt.% of NH3·H2Mixing O and Sargassum powder, sealing, heating in water bath at 80 deg.C for 12 hr, drying, and pulverizing to 80 mesh to obtain Sargassum powder pretreated with ammonia water;
step 3, putting the gulfweed powder pretreated by the ammonia water into an atmosphere tube furnace, and performing reaction in N2Carbonizing in the atmosphere, crushing and sieving with a 80-mesh sieve to obtain sargassum semi-coke;
step 4, mixing the gulfweed semicoke and KOH, putting the mixture into an atmosphere tube furnace, and adding N2Activating in an atmosphere;
step 5, using 1mol L of the activated mixture-1Washing with hydrochloric acid, washing with deionized water to neutral pH, and drying to obtain a product with specific surface area of 3000m2 g-1The biomass activated carbon-based electrode material.
2. The biomass activated carbon containing micropore-mesopore channels as claimed in claim 1The directional synthesis method of the base electrode material is characterized in that the NH in the step 23·H2The ratio of O to sargassum powder was 100mL:10 g.
3. The directional synthesis method of the biomass activated carbon-based electrode material with the micropore-mesopore pore canal as claimed in claim 1, wherein the temperature rise rate in step 3 is 5 ℃ min-1The carbonization temperature is 600 ℃, and the carbonization time is 3 h.
4. The oriented synthesis method of the biomass activated carbon-based electrode material with the microporous-mesoporous channels as claimed in claim 1, wherein the mass ratio of the gulfweed semicoke to the KOH in the step 4 is 1:4, and the heating rate is 10 ℃ min-1The activation temperature is 800 ℃, and the activation time is 2 h.
5. The oriented synthesis method of the biomass activated carbon-based electrode material with the microporous-mesoporous channels as claimed in claim 1, wherein the molar ratio of the hydrochloric acid in the step 5 to the KOH in the step 4 is 1.5: 1.
6. Use of the biomass activated carbon-based electrode material obtained according to claim 1 for the preparation of electrodes for supercapacitors.
7. The application of the biomass activated carbon-based electrode material as claimed in claim 6, wherein the biomass activated carbon-based electrode material is ground to 200 meshes, then mixed with acetylene black and PTFE in a mortar according to the mass ratio of 8:1:1, ethanol is added to uniformly mix the materials, then 10mg of the mixture is coated on foamed nickel, and the foamed nickel is pressed into a sheet for 30s under the pressure of 10MPa, and the sheet is dried to ensure that the ethanol is completely removed, so that the biomass activated carbon-based electrode containing micropore-mesopore channels is obtained.
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