CN114380289A - Preparation method and application of carbonized particle material and activated carbon electrode material - Google Patents

Preparation method and application of carbonized particle material and activated carbon electrode material Download PDF

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CN114380289A
CN114380289A CN202111518488.3A CN202111518488A CN114380289A CN 114380289 A CN114380289 A CN 114380289A CN 202111518488 A CN202111518488 A CN 202111518488A CN 114380289 A CN114380289 A CN 114380289A
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temperature
sintering
activated carbon
nitrogen
electrode material
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李欣
雷磊
赵晓磊
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Northern Altair Nanotechnologies Co Ltd
Gree Altairnano New Energy Inc
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Gree Altairnano New Energy Inc
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    • C01B32/342—Preparation characterised by non-gaseous activating agents
    • C01B32/348—Metallic compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
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    • C01B32/312—Preparation
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    • H—ELECTRICITY
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    • 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
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • 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
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    • 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
    • H01G11/32—Carbon-based
    • H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
    • 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
    • H01G11/84—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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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The invention provides a preparation method and application of a carbonized particle material and an activated carbon electrode material. The preparation method comprises the following steps: carbonizing and sintering the precursor of the carbon source in nitrogen or inert gas to obtain carbonized particles; the carbon source precursor comprises starch; the carbonization sintering is heated to the heat preservation temperature by adopting n sections of temperature programming means, the temperature raising speed of the temperature programming is 0.1-10 ℃/min, and the temperature raising speed of the temperature programming between 100 ℃ and 250 ℃ is 0.1-3 ℃, wherein n is an integer and is more than 1. The carbonization sintering process is optimized, and the temperature rise speed of the temperature programming between 100 ℃ and 250 ℃ is strictly controlled to be 0.1 ℃ to 3 ℃ so as to obtain the carbonization particles with high structural stability.

Description

Preparation method and application of carbonized particle material and activated carbon electrode material
Technical Field
The invention relates to the field of supercapacitor electrode technology, in particular to a preparation method and application of a carbonized particle material and an activated carbon electrode material.
Background
With the continuous development and progress of the human industrial technology, the demand for energy is also expanding day by day. Therefore, the sustainable development of socio-economic can be realized only by developing and using new renewable clean energy. At present, China has made great progress on the development of natural energy sources, such as wind energy, water energy, solar energy, geothermal energy and the like. However, these new energy sources cannot be directly utilized for industrial development, and must be converted and stored to be used. Electric energy is used as secondary energy, and has the remarkable advantages of high energy conversion efficiency, no pollution, convenience in storage and transmission and the like, so that the electric energy occupies the main position of energy utilization. Among numerous electric energy storage devices, the super capacitor has the advantages of high energy density and high power density as a novel energy storage device, and fills the energy storage gap between the traditional capacitor and the secondary battery. The super capacitor has good chemical stability, so that the super capacitor has long cycle life and safety. At present, super capacitors are widely applied to various electronic digital products and energy storage devices of new energy automobiles.
Carbon materials have been commercially used for decades as a conventional supercapacitor electrode material. However, since the energy storage mechanism of the electric double layer capacitor is energy storage through physical adsorption on the surface of the bulk phase, the carbon-based electrode material has a low energy density, which limits its further application as an energy storage material. Therefore, in order to further increase the energy density of the carbon material, the following two aspects are mainly performed:
the selection of the carbon precursor improves the particle microscopic morphology and the uniformity of the particle size of the carbon material, and increases the adsorption capacity of the bulk phase surface;
by means of heteroatom doping, heteroatoms enter a carbon skeleton of the activated carbon material, functional groups on the surface of the carbon material are changed, pseudo capacitance is increased, and specific capacitance of the material is improved.
Among the abundant carbon sources, starch has the advantages of low price, reproducibility, no toxicity and no pollution. Compared with other biomass carbon materials, the starch-based carbon material inherits the morphological characteristics of natural starch, has the advantages of uniform particle dispersion, proper size, smooth surface, unique morphological structure and the like, and becomes an ideal carbon-based material precursor of a supercapacitor.
However, in the process of preparing the carbon material by using starch, the phenomena of crushing, fusion, agglomeration and the like of carbon particles can be caused in the carbonization stage, the damage to the material structure is large, and the problems of the structural stability and the electrical property reduction of the material are caused.
Disclosure of Invention
The invention mainly aims to provide a preparation method and application of a carbonized particle material and an activated carbon electrode material, so as to solve the problem of poor structural stability of the activated carbon electrode material in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method of preparing a carbonized particulate material, the method comprising: carbonizing and sintering the precursor of the carbon source in nitrogen or inert gas to obtain carbonized particles; the carbon source precursor comprises starch; the carbonization sintering is heated to the heat preservation temperature by adopting n sections of temperature programming means, the temperature raising speed of the temperature programming is 0.1-10 ℃/min, and the temperature raising speed of the temperature programming between 100 ℃ and 250 ℃ is 0.1-3 ℃, wherein n is an integer and is more than 1.
Further, the heat preservation temperature of the carbonization sintering is 400-500 ℃, and the heat preservation time of the carbonization sintering is 2-6 h.
Further, n is 3, the end point temperature of the first stage temperature programming is 80 to 120 ℃, the end point temperature of the second stage temperature programming is 200 to 300 ℃, the end point temperature of the third stage temperature programming is 400 to 500 ℃, preferably the end point temperature of the first stage temperature programming is 100 ℃, the end point temperature of the second stage temperature programming is 250 ℃, the speed of the first stage temperature programming is 3 to 5 ℃/min, preferably the speed of the second stage temperature programming is 0.1 to 1 ℃/min, and preferably the speed of the third stage temperature programming is 3 to 5 ℃/min.
Further, the carbon source precursor also comprises a flame retardant, and the preparation method also comprises a preparation process of the carbon source precursor, wherein the preparation process comprises the following steps: carrying out first mixing on starch and a flame retardant solution to obtain mixed slurry; filtering and drying the mixed slurry to obtain a carbon source precursor; the flame retardant solution is preferably selected from phosphate solutions, the phosphate is preferably selected from one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate and disodium hydrogen phosphate, the mass ratio of starch to phosphate is preferably 1: 0.2-2, and the particle size of starch is preferably 5-50 μm.
According to another aspect of the present invention, there is provided a method of preparing an activated carbon electrode material, the method comprising: step A, preparing carbonized particles by any one of the preparation methods; and B, in a nitrogen atmosphere or an inert gas atmosphere, carrying out second sintering on the raw material system containing the activating agent and the carbonized particles to obtain the activated carbon electrode material.
Further, the step B includes: step B1, carrying out second mixing on the solvent, the activating agent and the carbonized particles to obtain a first dispersion liquid; step B2, drying the first dispersion liquid to obtain a raw material system; step B3, carrying out second sintering on the raw material system to obtain an activated carbon electrode material; preferably, the activator is selected from any one or more of hydroxides and salts of alkali metals, and more preferably, the activator is selected from KOH, NaOH, ZnCl2Preferably, the mass ratio of the carbonized particles to the activating agent is 1: 1-10.
Further, the raw material system also comprises a nitrogen source, and the step B comprises the following steps: step B1, mixing a nitrogen source, a solvent, an activating agent and carbonized particles for the second time to obtain a first dispersion liquid; step B2, drying the first dispersion liquid to obtain a raw material system; step B3, carrying out second sintering on the raw material system to obtain an activated carbon electrode material; the nitrogen source is preferably selected from one or more of urea, dicyandiamide and melamine, and the mass ratio of the carbonized particles, the activating agent and the nitrogen source is preferably 1: 1-10: 1-5.
Further, performing second mixing by adopting ultrasonic dispersion, preferably, the power of the ultrasonic dispersion is 10-40 Kw, and the time is 10-50 min; preferably, the temperature of the drying treatment is 60-120 ℃.
Further, the second sintering is buried sintering, preferably, petroleum coke is used as a cover for the buried sintering, the temperature of the second sintering is 700-1000 ℃, the time is 1-2 h, and the temperature rise speed before the second sintering is preferably 5-15 ℃/min.
According to another aspect of the present invention, a supercapacitor is provided, the supercapacitor includes an electrode and an electrolyte, the electrode includes an activated carbon electrode material, the activated carbon electrode material is the activated carbon electrode material prepared by any one of the above preparation methods, preferably, the activated carbon electrode material has a porosity of 30-40% and a specific surface area of 1000m2/g～2000m2The grain diameter of the activated carbon electrode material is preferably 5-50 mu m, the activated carbon electrode material is preferably doped with nitrogen, and the surface nitrogen content of the activated carbon electrode material is preferably 1-5 wt%.
By applying the technical scheme of the invention, water adsorbed in starch is mainly removed in the sintering process below 100 ℃, and the temperature rise speed can be selected in a larger range because the process has less influence on the molecular structure of the starch. In the sintering process between 100 ℃ and 250 ℃, bound water and starch intramolecular water are mainly removed, and the molecular structure of the starch is greatly changed by removing the bound water and the starch intramolecular water, so that the temperature rise speed needs to be controlled at a lower level, most of the bound water and the starch intramolecular water are sequentially and slowly removed, and the phenomena that the structure of the starch is seriously damaged due to the overhigh dehydration speed, and further the finally obtained carbonized particles are crushed, melted and agglomerated are avoided. In the oxidation sintering process at the temperature of more than 250 ℃, residual water in the precursor of the carbon source is further removed, and carbonized particles with complete and uniform structures are obtained. In summary, the carbonization sintering process is optimized, and the temperature rise speed of the temperature programming between 100 ℃ and 250 ℃ is strictly controlled to be 0.1 ℃ to 3 ℃ so as to obtain the carbonization particles with high structural stability.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 shows SEM images of activated carbon electrode materials prepared according to example 1 and comparative example 3 of the present invention;
FIG. 2 shows XPS spectra of activated carbon electrode materials prepared in examples 2 and 27 of the present invention, wherein a is the XPS survey spectra of examples 2 and 27, and b is the spectrum of N1s of example 1
Fig. 3 shows charge and discharge curves of supercapacitors composed of the activated carbon electrode materials prepared in example 1 and example 31 of the present invention at different magnifications, wherein a is the charge and discharge curve of example 1, and b is the charge and discharge curve of example 31;
fig. 4 shows cyclic voltammetry curves of supercapacitors composed of the activated carbon electrode materials prepared in example 1 and example 31 of the invention at different sweep rates, wherein a is the charge-discharge curve of example 1, and b is the charge-discharge curve of example 31;
FIG. 5 shows the AC impedance diagram of the supercapacitor made of the activated carbon electrode materials prepared in example 1 and example 31 of the present invention;
FIG. 6 shows N of the electrode material of activated carbon prepared in example 1 of the present invention2Adsorption and desorption isotherms;
fig. 7 shows a pore size distribution diagram of the activated carbon electrode material prepared in example 1 of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
As described in the background of the present application, in the prior art, during the preparation of activated carbon material from starch, the phenomena of breaking, fusion and agglomeration of carbon particles are easily generated in the carbonization stage, which leads to the problem of reduced structural stability of the material. In order to solve the problems, the application provides a preparation method and application of a carbonized particle material and an activated carbon electrode material.
In an exemplary embodiment of the present application, there is provided a method of preparing a carbonized particulate material, the method comprising: carbonizing and sintering the precursor of the carbon source in nitrogen or inert gas to obtain carbonized particles; the carbon source precursor comprises starch; the carbonization sintering is heated to the heat preservation temperature by adopting n sections of temperature programming means, the temperature raising speed of the temperature programming is 0.1-10 ℃/min, and the temperature raising speed of the temperature programming between 100 ℃ and 250 ℃ is 0.1-3 ℃, wherein n is an integer and is more than 1.
The carbonization and sintering aims to remove free water, combined water and intramolecular water from a carbon source precursor in a high-temperature environment to obtain carbonized particles. Among them, water adsorbed in starch is mainly removed in the sintering process at 100 ℃ or lower, and since the influence of this process on the molecular structure of starch is small, the temperature rise rate can be selected in a wide range. In the sintering process between 100 ℃ and 250 ℃, bound water and starch intramolecular water are mainly removed, and the molecular structure of the starch is greatly changed by removing the bound water and the starch intramolecular water, so that the temperature rise speed needs to be controlled at a lower level, most of the bound water and the starch intramolecular water are sequentially and slowly removed, and the phenomena that the structure of the starch is seriously damaged due to the overhigh dehydration speed, and further the finally obtained carbonized particles are crushed, melted and agglomerated are avoided. In the oxidation sintering process at the temperature of more than 250 ℃, residual water in the precursor of the carbon source is further removed, and carbonized particles with complete and uniform structures are obtained. In summary, the carbonization sintering process is optimized, and the temperature rise speed of the temperature programming between 100 ℃ and 250 ℃ is strictly controlled to be 0.1 ℃ to 3 ℃ so as to obtain the carbonization particles with high structural stability.
In some embodiments, the temperature of the carbonization sintering is 400-500 ℃, and the time of the carbonization sintering is 2-6 h. In the heat preservation time and the heat preservation period, the water in the precursor of the carbon source can be removed, and the structure of the carbonized particles can be prevented from being damaged due to overhigh sintering temperature.
The number of stages of the carbonization and sintering can be determined by those skilled in the art according to actual needs, and according to repeated experiments by the inventor, n is preferably 3, the end point temperature of the first stage temperature programming is 80 to 120 ℃, the end point temperature of the second stage temperature programming is 200 to 300 ℃, and the end point temperature of the third stage temperature programming is 400 to 500 ℃ (namely, the heat preservation temperature). By adopting the three-stage temperature programming, the temperature rising speed in the temperature rising process can be flexibly adjusted, the carbonization sintering stage is not damaged due to the overhigh dehydration speed, and the temperature rising speed can be properly increased in the stage with less influence on the carbonization particle structure, so that the sintering efficiency is effectively improved.
In one embodiment, the terminal temperature of the first stage temperature programming is preferably 100 ℃, the terminal temperature of the second stage temperature programming is 250 ℃, the speed of the first stage temperature programming is 3-5 ℃/min, the speed of the second stage temperature programming is preferably 0.1-1 ℃/min, and the speed of the third stage temperature programming is preferably 3-5 ℃/min. In the first section of temperature programming process, water adsorbed in the starch can be discharged more efficiently. And then controlling the temperature rise speed of the second section of temperature programming to ensure that water in starch molecules is removed at a slower speed, thereby further ensuring the structural stability of the carbonized particles. Finally, the temperature is increased to 450 ℃ at a higher temperature increase speed so as to realize the purpose of removing the residual water more efficiently.
The carbon source precursor can be prepared by a method commonly used in the prior art, and in order to better ensure the spontaneous combustion of the starch at high temperature, the carbon source precursor further comprises a flame retardant, so that the preparation method preferably further comprises a preparation process of the carbon source precursor, and the preparation process comprises the following steps: carrying out first mixing on starch and a flame retardant solution to obtain mixed slurry; and filtering and drying the mixed slurry to obtain a carbon source precursor. By mixing the starch and the flame retardant, the flame retardant is absorbed into the starch. In the carbonization and sintering process, the flame retardant avoids starch combustion, and the structural integrity of the material is further improved. The flame retardant can be selected by a person skilled in the art in the prior art, in order to avoid the residue of the flame retardant component, the flame retardant is preferably selected from a phosphate solution, preferably, the phosphate is selected from one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate and disodium hydrogen phosphate, preferably, the mass ratio of starch to phosphate is 1: 0.2-2, because the flame retardant is mixed with starch in the form of the flame retardant solution, after subsequent filtration and drying, part of the flame retardant is wrapped on the starch, and the rest of the flame retardant flows out along with the filtrate, when the amount of the phosphate is less than the numerical range, the amount of the phosphate is insufficient, and the starch structure cannot be fully prevented from being damaged; the excessive use amount of the flame retardant can cause the residue of the flame retardant and cause negative effects on the subsequently formed activated carbon.
Starches of the present application may include, but are not limited to: one or more of sweet potato starch, tapioca starch, mung bean starch, potato starch and corn starch. The starch with the grain size of 5-50 microns is preferably selected, so that the grain size of the finally obtained active carbon electrode material can be well controlled without a crushing step in the preparation process, the possible damage to the material structure in the crushing step process is avoided, the preparation process is simplified, and the efficiency is improved.
In another exemplary embodiment of the present application, there is provided a method of preparing an activated carbon electrode material, the method comprising: step A, preparing carbonized particles by any one of the preparation methods; and B, in a nitrogen atmosphere or an inert gas atmosphere, carrying out second sintering on the raw material system containing the activating agent and the carbonized particles to obtain the activated carbon electrode material.
This application is through controlling carbonization sintering stage programming rate, makes the water of adsorbing in the starch and the water in the starch molecule slowly, in proper order be taken off in proper order, avoids because the dehydration rate is too fast, leads to the structure of starch to be seriously destroyed, and then causes the carbonization granule that finally obtains to appear breakage, melt and with the phenomenon of caking. The carbonized particles have uniform and complete structure, and are sintered together with an activating agent for activation treatment to obtain the activated carbon electrode material with large specific surface area and high porosity. The preparation method effectively avoids the crushing, melting and caking of the carbon source precursor in the carbonization and sintering process, effectively improves the structural stability of the material, and further improves the capacitance of the material.
In order to enhance the effect of the activation treatment, it is preferable that step B includes: step B1, carrying out second mixing on the solvent, the activating agent and the carbonized particles to obtain a first dispersion liquid; step B2, drying the first dispersion liquid to obtain a raw material system; and step B3, carrying out second sintering on the raw material system to obtain the activated carbon electrode material. The activating agent and the carbonized particles are fully mixed and dried, and then secondary sintering is carried out, so that the activating agent can be uniformly adsorbed on the inner surface and the outer surface of the carbonized particles, a better pore-forming effect can be obtained after sintering, and the porosity and the specific surface area of the activated carbon electrode material are effectively improved.
The activator used in the present application may be selected from the activators commonly used in the art, and in order to reduce the cost and improve the universality of the preparation method of the present application, the activator is preferably selected from any one or more of hydroxides and salts of alkali metals, and the activator is further preferably selected from KOH and ZnCl2And NaOH. The mass ratio of the carbonized particles to the activating agent is preferably 1: 1-10, and within the numerical range, the specific surface area of the material can be increased as much as possible, and the mechanical property is not reduced due to excessive material gaps.
In some embodiments, the activating and the nitrogen doping are performed simultaneously, the raw material system further comprises a nitrogen source, and the step B comprises: step B1, mixing a nitrogen source, a solvent, an activating agent and carbonized particles for the second time to obtain a first dispersion liquid; step B2, drying the first dispersion liquid to obtain a raw material system; and step B3, carrying out second sintering on the raw material system to obtain the activated carbon electrode material. By mixing the nitrogen source and the activating agent with the carbonized particles, the nitrogen source and the activating agent are adsorbed on the surfaces of the carbonized particles at the same time, and when the carbonized particles are sintered, on one hand, the carbonized particles are activated to generate more pores, and on the other hand, nitrogen doping is realized, so that the nitrogen-doped activated carbon electrode material is obtained. On one hand, nitrogen has a similar electron arrangement mode with carbon elements (the two have two electron layers, and simultaneously, nitrogen atoms have one more lone electron than carbon atoms), so that carbon atoms in an activated carbon skeleton can be replaced more easily to realize doping, and on the other hand, nitrogen-containing functional groups can enable activated carbon to improve the pseudo-capacitance of materials and effectively promote electron transfer, thereby improving the energy density of the materials.
The nitrogen source used in the present application may be selected from nitrogen sources commonly used in the prior art by those skilled in the art, and preferably, the nitrogen source is selected from one or more of urea, dicyandiamide and melamine, and the nitrogen source may better react with the carbonized particles of the present application, thereby improving the nitrogen doping efficiency. The mass ratio of the carbonization particles to the activating agent to the nitrogen source is preferably 1: 1-10: 1-5, and more appropriate porosity and nitrogen doping amount can be obtained within the numerical range, so that the stability and the electrical property of the material are further improved.
In order to make the mixing effect of the carbonized particles, the activator and the optional nitrogen source better, it is preferable to perform the second mixing by ultrasonic dispersion. The power of ultrasonic dispersion is preferably 10-40 Kw, the time is 10-50 min, and within the numerical range, the activating agent and the optional nitrogen source can be uniformly dispersed on the surface of the carbonized particles, and the mechanical damage to the carbonized particles is avoided by adopting an ultrasonic dispersion mode. Preferably, the drying temperature is 60-110 ℃, so that water adsorbed by the carbonized particles is completely removed, and the carbon particles are prevented from being crushed in the calcining process due to residual adsorbed water; the drying process does not completely remove the water, and some intramolecular water remains.
The second sintering of this application can be carried out to the method commonly used in this field, and preferred second sintering is buried sintering, buries raw materials system completely with the cover earlier, and then sinters to reach abundant nitrogen doping's effect and save nitrogen gas consumption, buries the sintering preferentially and adopts petroleum coke as the cover, and the cover can insulate air on the one hand, utilizes the good heat conduction of petroleum coke and heat preservation effect, can make the even being heated of raw materials, and on the other hand because there is the gap between the petroleum coke granule, can be with the gas discharge that produces in the calcination process, avoid producing the explosion. The temperature of the second sintering is preferably 700-1000 ℃, the time is 1-2 h, the heating rate before the second sintering is preferably 5-15 ℃/min, the activation can be more fully performed within the numerical range, and when the raw material system contains a nitrogen source, the nitrogen doping effect can be further improved
In another exemplary embodiment of the present application, there is provided a supercapacitor, the supercapacitor including an electrode and an electrolyte, the electrode including an activated carbon electrode material, the activated carbon electrode material being prepared by any one of the above-mentioned preparation methods.
The preparation method successfully avoids the crushing, melting and caking of starch particles in the carbonization process, thereby effectively improving the structural stability and energy density of the material and obviously improving the service performance of the supercapacitor. Preferably, the active carbon electrode material prepared by the preparation method has the porosity of 30-40%, the porosity of 2-10 nm and the specific surface area of 1000m2/g～2000m2The particle size of the activated carbon electrode material is preferably 5 μm to 50 μm, and within the above numerical range, the material can have better electrical properties. Preferably, the activated carbon electrode material is doped with nitrogen, the pseudocapacitance and the conductivity of the activated carbon electrode material doped with nitrogen are higher, and further the energy density of the material is improved, and preferably, the surface nitrogen content of the activated carbon electrode material is 1-5 wt%, preferably 1.5-4.8%, so that the electrical performance of the material is better improved.
The advantageous effects of the present application will be further described below with reference to examples and comparative examples.
Example 1
(1) Pretreatment of starch: potato starch is selected as a carbon source, and the potato starch (with the grain diameter of 20-50 mu m) is soaked in (NH)4)2HPO4In solution (starch and (NH)4)2HPO4The mass ratio of (1): 2) the mixture was immersed for 1 hour, and then the mixture was filtered. Then, collecting a starch sample, and removing residual moisture by using a freeze drying method to obtain a carbon source precursor;
(2) carbonizing: putting a carbon source precursor into a nitrogen atmosphere furnace, heating to 250 ℃ (the first stage of programmed heating) at 0.2 ℃/min, then heating to 450 ℃ (the heat preservation temperature) at 5 ℃/min, preserving heat for 4h (the second stage of programmed heating), and finally lightly pressing and sieving a black solid product (150 meshes) to obtain carbonized particles;
(3) pore-forming and nitrogen doping of the carbonized particles: mixing carbonized particles, KOH and urea according to the proportion of 1: 2: 3, adding a proper amount of deionized water, ultrasonically stirring for 30min (the power is 10Kw), and drying at 80 ℃ for 6h to obtain a raw material system;
(4) and (3) second sintering: putting the raw material system into a sealed graphite crucible, burying the graphite crucible with petroleum coke to isolate air, heating to 850 ℃ in a muffle furnace at a heating rate of 5 ℃/min, and keeping for 1 hour to obtain a nitrogen-doped activated carbon electrode material;
(5) cleaning and drying: and repeatedly washing the nitrogen-doped activated carbon electrode material by using diluted HCl or clear water to remove residual inorganic impurities, and then putting the electrode material into a spiral strip drier for drying treatment at 250 ℃ to obtain the nitrogen-doped activated carbon electrode material with the specified moisture content.
Example 2
(1) Pretreatment of starch: selecting potato starch as a carbon source, and soaking the potato starch (with the grain diameter of 20-50 mu m) in (NH)4)2HPO4In solution (starch and (NH)4)2HPO4The mass ratio of (1): 1) the mixture was immersed for 1 hour, and then the mixture was filtered. Then, collecting a starch sample and drying in a blast drying oven at 40 ℃ to obtain a carbon source precursor;
(2) carbonizing: putting a carbon source precursor into an argon atmosphere furnace, heating to 100 ℃ at a speed of 5 ℃/min (first-stage programmed heating), heating to 250 ℃ at a speed of 0.2 ℃/min (second-stage programmed heating), heating to 450 ℃ at a speed of 5 ℃/min (heat preservation temperature), preserving heat for 4h (third-stage programmed heating), and lightly pressing and screening a black solid product to obtain carbonized particles (150 meshes);
(3) pore-forming and nitrogen doping of the carbonized particles: mixing carbonized particles, KOH and dicyandiamide according to the weight ratio of 1: 2: 2, adding a proper amount of deionized water, ultrasonically stirring for 30min (the power is 10Kw), and drying at 80 ℃ for 6h to obtain a raw material system;
(4) and (3) second sintering: putting the raw material system into a sealed graphite crucible, burying the graphite crucible petroleum coke to isolate air, heating to 850 ℃ in a muffle furnace at a heating rate of 5 ℃/min, and keeping for 1 hour to obtain a nitrogen-doped activated carbon electrode material;
(5) cleaning and drying: and repeatedly washing the nitrogen-doped activated carbon electrode material by using diluted HCl or clear water to remove residual inorganic impurities, and then putting the electrode material into a spiral strip drier for drying treatment at 250 ℃ to obtain the nitrogen-doped activated carbon electrode material with the specified moisture content.
Example 3
(1) Pretreatment of starch: selecting potato starch as a carbon source, and soaking the potato starch (with the grain diameter of 20-50 mu m) in (NH)4)2HPO4In solution (starch and (NH)4)2HPO4The mass ratio of (1): 2) the mixture was immersed for 1 hour, and then the mixture was filtered. Then, collecting a starch sample and drying in a blast drying oven at 40 ℃ to obtain a carbon source precursor;
(2) carbonizing: putting a carbon source precursor into an argon atmosphere furnace, heating to 100 ℃ at a speed of 5 ℃/min (first-stage programmed heating), heating to 250 ℃ at a speed of 0.2 ℃/min (second-stage programmed heating), heating to 450 ℃ at a speed of 5 ℃/min (heat preservation temperature), preserving heat for 4h (third-stage programmed heating), and finally lightly pressing and screening a black solid product to obtain carbonized particles (150 meshes);
(3) pore-forming and nitrogen doping of the carbon microspheres: mixing (2) carbon powder, KOH and melamine according to the proportion of 1: 2: 3, adding a proper amount of deionized water, ultrasonically stirring for 30min (the power is 20Kw), and drying at 80 ℃ for 6h to obtain a raw material system;
(4) and (3) second sintering: putting the raw material system into a sealed graphite crucible, burying the graphite crucible petroleum coke to isolate air, heating to 800 ℃ in a muffle furnace at a heating rate of 5 ℃/min, and keeping for 1 hour to obtain a nitrogen-doped activated carbon electrode material;
(5) cleaning and drying: and repeatedly washing the nitrogen-doped activated carbon electrode material by using diluted HCl or clear water to remove residual inorganic impurities, and then putting the electrode material into a spiral strip drier for drying treatment at 250 ℃ to obtain the nitrogen-doped activated carbon electrode material with the specified moisture content.
Example 4
The difference from example 2 is that in step (2) the temperature is increased from 3 ℃/min to 100 ℃.
Example 5
The difference from example 2 is that in step (2) the temperature is increased from 1 ℃/min to 100 ℃.
Example 6
The difference from example 2 is that in step (2) the temperature is between 7 ℃/min and 100 ℃.
Example 7
The difference from example 2 is that in step (2) the temperature is increased from 1 ℃/min to 250 ℃.
Example 8
The difference from example 2 is that in step (2) the temperature is increased to 250 ℃ at 3 ℃/min.
Example 9
The difference from example 2 is that in step (2) the temperature is between 0.1 ℃/min and 250 ℃.
Example 10
The difference from example 2 is that in step (2) the temperature is increased to 450 ℃ at 3 ℃/min.
Example 11
The difference from example 2 is that in step (2) the temperature is between 1 ℃/min and 450 ℃.
Example 12
The difference from example 2 is that in step (2) the temperature is between 7 ℃ and 450 ℃.
Example 13
The difference from the example 2 is that in the step (2), the carbon source precursor is put into an argon atmosphere furnace, and is heated to 80 ℃ at a speed of 5 ℃/min (first stage temperature programming), then heated to 200 ℃ at a speed of 0.2 ℃/min (second stage temperature programming), finally heated to 450 ℃ at a speed of 0.2 ℃/min and kept for 4h (third stage temperature programming), and finally the black solid product is lightly pressed and sieved (150 meshes) to obtain carbonized particles.
Example 14
The difference from the example 2 is that in the step (2), the carbon source precursor is put into an argon atmosphere furnace, and is heated to 120 ℃ at a speed of 0.2 ℃/min (first stage programmed temperature), then heated to 300 ℃ at a speed of 0.2 ℃/min (second stage programmed temperature), finally heated to 400 ℃ at a speed of 5 ℃/min and kept for 4 hours (third stage programmed temperature), and finally the black solid product is lightly pressed and sieved (150 meshes) to obtain carbonized particles.
Example 15
The difference from example 2 is that the temperature for heat preservation in step (2) was 400 ℃.
Example 16
The difference from example 2 is that the temperature for heat preservation in step (2) was 500 ℃.
Example 17
The difference from example 2 is that the temperature for the heat-preservation in step (2) was 350 ℃.
Example 18
The difference from example 2 is that the temperature for heat preservation in step (2) was 550 ℃.
Example 19
The difference from example 2 is that the incubation time in step (2) was 2 h.
Example 20
The difference from example 2 is that the incubation time in step (2) was 6 h.
Example 21
The difference from example 2 is that the holding time in step (2) was 1 hour.
Example 22
The difference from example 2 is that the incubation time in step (2) was 8 h.
Example 23
The difference from example 2 is that in step (1) starch and (NH)4)2HPO4The mass ratio of (1): 0.2.
example 24
The difference from example 2 is that in step (1) starch and (NH)4)2HPO4The mass ratio of (1): 2.
example 25
The difference from example 2 is that in step (1) starch and (NH)4)2HPO4The mass ratio of (1): 0.1.
example 26
The difference from example 2 is that in step (1) starch and (NH)4)2HPO4The mass ratio of (1): 3.
example 27
The difference from example 2 is that, in step (3), no nitrogen doping is performed:
mixing (2) carbon powder with KOH according to the weight ratio of 1: 2, adding a proper amount of deionized water, ultrasonically stirring for 30min (the power is 10Kw), and drying at 80 ℃ for 6h to obtain a raw material system;
example 28
The difference from example 1 is that, in the absence of a starch pretreatment step, the potato starch was directly put into a nitrogen atmosphere furnace for carbonization.
Example 29
(1) Pretreatment of starch: selecting potato starch as a carbon source, soaking the potato starch (with the grain diameter of 20-50 microns) in 20 wt% of (NH4)2HPO4 solution for 1h, and filtering the mixed solution. Then, collecting a starch sample and drying in a blast drying oven at 40 ℃ to obtain a carbon source precursor;
(2) carbonizing: putting a carbon source precursor into an argon atmosphere furnace, heating to 100 ℃ at a speed of 5 ℃/min (first-stage programmed heating), heating to 250 ℃ at a speed of 0.2 ℃/min (second-stage programmed heating), heating to 450 ℃ at a speed of 5 ℃/min (heat preservation temperature), preserving heat for 4h (third-stage programmed heating), and lightly pressing and screening a black solid product to obtain carbonized particles (150 meshes);
(3) pore-forming and nitrogen doping of the carbonized particles: mixing carbonized particles, KOH and dicyandiamide according to the weight ratio of 1: 10: 5, adding a proper amount of deionized water, ultrasonically stirring for 50min (the power is 10Kw), and drying for 4h at 100 ℃ to obtain a raw material system;
(4) and (3) second sintering: putting the raw material system into a sealed graphite crucible, burying the graphite crucible petroleum coke to isolate air, heating to 1000 ℃ in a muffle furnace at a heating rate of 15 ℃/min, and keeping for 1h to obtain a nitrogen-doped activated carbon electrode material;
(5) cleaning and drying: and repeatedly washing the nitrogen-doped activated carbon electrode material by using diluted HCl or clear water to remove residual inorganic impurities, and then putting the electrode material into a spiral strip drier for drying treatment at 250 ℃ to obtain the nitrogen-doped activated carbon electrode material with the specified moisture content.
Example 30
(1) Pretreatment of starch: selecting potato starch as a carbon source, soaking the potato starch (with the grain diameter of 20-50 microns) in 20 wt% of (NH4)2HPO4 solution for 1h, and filtering the mixed solution. Then, collecting a starch sample and drying in a blast drying oven at 40 ℃ to obtain a carbon source precursor;
(2) carbonizing: putting a carbon source precursor into an argon atmosphere furnace, heating to 100 ℃ at a speed of 5 ℃/min (first-stage programmed heating), heating to 250 ℃ at a speed of 0.2 ℃/min (second-stage programmed heating), heating to 450 ℃ at a speed of 5 ℃/min (heat preservation temperature), preserving heat for 4h (third-stage programmed heating), and lightly pressing and screening a black solid product to obtain carbonized particles (150 meshes);
(3) pore-forming and nitrogen doping of the carbonized particles: mixing carbonized particles, KOH and dicyandiamide according to the weight ratio of 1: 1:1, adding a proper amount of deionized water, ultrasonically stirring for 10min (the power is 40Kw), and drying at 60 ℃ for 6h to obtain a raw material system;
(4) and (3) second sintering: putting the raw material system into a sealed graphite crucible, burying the graphite crucible petroleum coke in the graphite crucible to isolate air, heating the graphite crucible petroleum coke in a muffle furnace to 700 ℃ at a heating rate of 15 ℃/min, and keeping the temperature for 2 hours to obtain a nitrogen-doped activated carbon electrode material;
(5) cleaning and drying: and repeatedly washing the nitrogen-doped activated carbon electrode material by using diluted HCl or clear water to remove residual inorganic impurities, and then putting the electrode material into a spiral strip drier for drying treatment at 250 ℃ to obtain the nitrogen-doped activated carbon electrode material with the specified moisture content.
Example 31
The difference from example 1 is that, in step (3), nitrogen doping is not performed.
Comparative example 1
The difference from the example 1 is that in the step (2), the carbon source precursor is put into a nitrogen atmosphere furnace, heated to 450 ℃ at a speed of 5 ℃/min and kept for 4h to obtain carbonized particles.
Comparative example 2
The difference from the example 1 is that in the step (2), the carbon source precursor is put into a nitrogen atmosphere furnace, heated to 450 ℃ at the speed of 7 ℃/min and kept for 4h to obtain carbonized particles.
Comparative example 3
The difference from example 2 is that in step (2) the temperature is between 7 ℃ and 250 ℃.
Product characterization
The types and the contents of the elements on the surface of the sample are analyzed by adopting photon energy spectrum analysis (X-ray photon spectroscopy), and the energy spectrum data of the sample is characterized by adopting an NORAN 7 type X-ray photon energy spectrometer in the experiment. The XPS survey spectra of example 1 and example 29 are shown in fig. 2, and the N content of each of the examples and comparative examples is shown in table 1.
A scanning electron microscope is used for observing the micro morphology of the powder and testing the particle size, the electron microscopes of the example 2 and the comparative example 3 are shown in figure 1, the left image is the electron microscope image of the example 2, and the right image is the electron microscope image of the comparative example 3. The particle diameters of the activated carbon electrode materials obtained in the respective examples and comparative examples are shown in table 1.
Before testing, the samples were degassed at 300 ℃ for 3h to remove moisture and impurities from the samples. The absorption and desorption isotherm is drawn by measuring the absorption and desorption amount of the sample to nitrogen under different pressure conditions, and the parameters of the specific surface area, the pore diameter structure and the like of the sample are further analyzed and calculated. The specific surface area tester of Congta NOVA1200e is used to measure parameters such as specific surface area and pore size structure of the sample.
As seen in FIG. 1, the sample retained the native microscopic morphology of the starch granules by the low temperature carbonization treatment with diammonium phosphate soaking at 0.2 ℃/Min heating to 450 ℃. The activated carbon has smooth surface, uniform particles, complete appearance and good dispersibility, is spherical and elliptical, has the particle size of between 20 and 50 mu m, and does not have the phenomenon of fusion and combination of the activated carbon particles. And the sample is heated to 450 ℃ at the temperature of 7 ℃/Min for carbonization treatment at a low temperature, a large amount of water vapor is rapidly generated in the intrinsic carbonization process of the starch due to an excessively high temperature rise rate, the water vapor is broken from the starch granules, carbon spheres are broken, and a large amount of fragments are formed by stacking the spherical shells, so that the adsorption capacity of the material is seriously influenced, and the electrochemical performance of the material is reduced.
To examine the composition of the elements on the surface of the sample, XPS test was performed. The full spectrum of the samples of example 2 and example 27 in FIG. 2 shows that in example 27, only the peaks of C and O are detected and the peaks of N are not detected, and the C and O contents are 77.57% and 22.43%, respectively, which are consistent with the constituent elements of starch. In contrast, in the full spectrum of example 2, a peak of N1s was detected at 400eV, which indicates that the incorporation of nitrogen element was achieved in the sample, and the nitrogen content was divided into 3.25%, and from the deconvolution result of the N1s spectrum, it can be seen that there are four ways for the N element in the sample: pyridine nitrogen N6 at around 398.8eV, pyrrole nitrogen N5 at around 400.4eV, graphite nitrogen N-Q at around 401.4eV, and nitrogen oxide N-X at around 402.4 eV. According to the literature, pyrrole nitrogen N5 and pyridine nitrogen N6 in the carbon skeleton can directly participate in Faraday reaction to generate pseudo capacitance; the graphite type nitrogen N-Q can effectively promote electron transfer and increase the conductivity of the material; the functional group N-X containing oxygen and nitrogen can improve the wettability of the material in an alkaline aqueous solution, so that the electrolyte can be more effectively contacted with the material, the effective specific surface area of the material is increased, and the storage of charges is improved. Several different nitrogen configurations are cooperated with each other, so that the electrochemical performance of the material can be effectively improved.
Fig. 3 is a graph showing the charging and discharging curves of example 1 and example 31 at different current densities, the left graph is a graph showing the charging and discharging curves of example 1 at different current densities, and the right graph is a graph showing the charging and discharging curves of example 31 at different current densities, and it can be seen from the graphs that the charging and discharging curves are triangular structures, and the graphs show that the material has good electric double layer capacitance behavior. As can be seen from the graph, example 1 has the longest discharge time at a current density of 1A/g, indicating a higher specific capacity. Through the calculation of the formula, the specific capacity of the nitrogen-doped activated carbon in the embodiment 1 under the A/g current density is 207F/g, and the specific capacity of the nitrogen-doped activated carbon in the embodiment 31 under the A/g current density is 184F/g. The abundant nitrogen elements can improve the wettability of the surface of the carbon material, and are beneficial to further diffusing electrolyte ions to micropores, so that the effective specific surface area is increased. Meanwhile, the graphitized nitrogen N-Q improves the conductive capacity of the electrode material, and the redox reaction on the nitrogen-containing functional group introduces part of pseudo capacitance, thereby further increasing the total capacitance.
Fig. 4 shows the current density plots for example and example 31 at different voltages. As can be seen from fig. 4, after the N element is doped into the framework of the activated carbon, the CV curve of the activated carbon is greatly improved after the nitrogen doping treatment at the same scanning rate, and the severe warping phenomenon similar to that of example 31 does not occur. This process is because the N element doped in the carbon skeleton improves the charge transport property in the sample, and increases the wettability of the electrode and the electrolyte, reducing the polarization effect of the charge.
Fig. 5 shows ac impedance diagrams of supercapacitors composed of the activated carbon electrode materials prepared in example 1 and example 31 of the present invention. As can be seen from fig. 5, example 31 has a larger diameter in the high frequency region semicircle, indicating that the sample charge transfer resistance is higher, whereas the high frequency curve semicircles of example 1 are all smaller in diameter by C, indicating that the electrode charge transfer resistance of the nitrogen-doped activated carbon is lower. The extra lone pair electrons of the nitrogen atoms in the carbon skeleton can promote the transmission of electrons in the carbon matrix, change the electron acceptor/donor property on the surface of the sample and enhance the charge transfer capacity. The straight line in the middle and low frequency region is the Warburg impedance, which is the diffusion resistance Rw of the electrolyte ions in the pore structure of the sample, and the more perpendicular the straight line is to the real axis, which indicates that the diffusion resistance Rw of the ions in the sample is smaller. As can be seen from the graph, the straight-line Warburg impedance in example 1 is more perpendicular to the real axis, and the surface nitrogen-doped activated carbon has a lower ion diffusion resistance Rw. The reason is that the doping of nitrogen element improves the wettability of the surface of the carbon material, so that the electrolyte fully infiltrates the electrode material, the contact area is increased, the diffusion resistance of electrolyte ions in the pore diameter is reduced, the electrolyte ions can be further diffused to micropores, and the electric double layer capacitance behavior of the sample is enhanced. This result is consistent with the fig. 3 and 4 tests.
The specific surface area and pore size distribution of example 1 were tested by N2 desorption method. Fig. 6 is a graph showing the adsorption and desorption curves of the sample of example 1, and fig. 7 is a graph showing the pore size distribution of the sample of example 1. It can be seen from the N2 adsorption-desorption isotherm curve in the figure that the adsorption of the sample to N2 reaches a saturation state at a lower relative pressure, and no adsorption-desorption hysteresis loop with obvious adsorption is generated in the medium-pressure and high-pressure zones, and according to the classification of IUPAC, the sample is type I isotherm adsorption, which indicates that the pore size structure in the sample is mainly microporous. As can be seen from the pore size distribution diagram, the sample pore size structure is mainly microporous and contains a small amount of mesoporous structure, wherein the mesoporous distribution range reaches the maximum around 2nm-3nm, and the result is the optimal pore size range for ion adsorption and storage.
Buckle electricity assembly
The samples prepared in the above examples and comparative examples were mixed with a conductive agent (acetylene black) and a binder, polytetrafluoroethylene ethanol solution (60%, PTFE), respectively, at a ratio of 80: 10: 10, dispersing the mixture in absolute ethyl alcohol, uniformly stirring to prepare electrode slurry, heating to 65 ℃ to remove redundant ethyl alcohol, pressing the mixture into 150 mu m slices after the corrected ethyl alcohol is volatilized, and finally punching the slices into circular pole pieces with the diameter of 12 mm; then, the two electrode plates are put into an R2025 cover, the two electrode plates are separated by using a cellulose diaphragm (cellulose TF of NKK Co., Ltd., Japan), a sufficient amount of 6mol/LKOH electrolyte is dripped, the two electrode plates are assembled according to the sequence of negative electrode shell-pole piece-diaphragm-pole piece-gasket-shrapnel-positive electrode shell, and finally, the two electrode plates are sealed on a battery packaging machine to form the 2025 button type symmetrical supercapacitor.
Capacitance measurement
A constant current charge and discharge test (GCD) is an important characterization means of electrochemical performance of a supercapacitor and is used for researching specific capacitance and rate performance of an electrode material. The capacitor is subjected to a charge-discharge test under a constant current, constant-current charge is started from a starting voltage, constant-current discharge is performed at a stopping voltage, and a current constant-current charge-discharge curve is drawn by recording the relation between the voltage and the time. The specific capacitance of the electrode material can be obtained by calculation of the charge-discharge curve. The GCD test is carried out by adopting CHI660e type electrochemical workstation of Shanghai Chenghua apparatus Co., Ltd, the current density is 1A/g-10A/g, the working voltage is 0-1V, and the calculation formula of the mass specific capacity of the active substance of the super capacitor is as follows:C＝2(I×△t)/△V×m
wherein, I (A) is constant current charging and discharging current, m (g) is the mass of the active material of a single pole piece, Δ t(s) is constant current discharging time, and Δ V (V) is a charging and discharging voltage window.
The measured capacitances are recorded in table 1.
TABLE 1
Figure BDA0003407790640000131
Figure BDA0003407790640000141
Figure BDA0003407790640000151
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
the carbonization and sintering aims to remove free water, combined water and intramolecular water from a carbon source precursor in a high-temperature environment to obtain carbonized particles. Among them, water adsorbed in starch is mainly removed in the sintering process at 100 ℃ or lower, and since the influence of this process on the molecular structure of starch is small, the temperature rise rate can be selected in a wide range. In the sintering process between 100 ℃ and 250 ℃, bound water and starch intramolecular water are mainly removed, and the molecular structure of the starch is greatly changed by removing the bound water and the starch intramolecular water, so that the temperature rise speed needs to be controlled at a lower level, most of the bound water and the starch intramolecular water are sequentially and slowly removed, and the phenomena that the structure of the starch is seriously damaged due to the overhigh dehydration speed, and further the finally obtained carbonized particles are crushed, melted and agglomerated are avoided. In the oxidation sintering process at the temperature of more than 250 ℃, residual water in the precursor of the carbon source is further removed, and carbonized particles with complete and uniform structures are obtained. In summary, the carbonization sintering process is optimized, and the temperature rise speed of the temperature programming between 100 ℃ and 250 ℃ is strictly controlled to be 0.1 ℃ to 3 ℃ so as to obtain the carbonization particles with high structural stability.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method of preparing a carbonized particulate material, the method comprising:
carbonizing and sintering the precursor of the carbon source in nitrogen or inert gas to obtain carbonized particles;
the carbon source precursor comprises starch;
the carbonization sintering is heated to the heat preservation temperature by adopting n sections of temperature programming means, the temperature raising speed of the temperature programming is 0.1-10 ℃/min, the temperature raising speed of the temperature programming between 100 ℃ and 250 ℃ is 0.1-3 ℃, wherein n is an integer and is more than 1.
2. The preparation method according to claim 1, wherein the temperature for the carbonization sintering is 400 to 500 ℃, and the time for the carbonization sintering is 2 to 6 hours.
3. The preparation method according to claim 1 or 2, wherein n is 3, the end point temperature of the first stage temperature programming is 80-120 ℃, the end point temperature of the second stage temperature programming is 200-300 ℃, the end point temperature of the third stage temperature programming is 400-500 ℃, preferably the end point temperature of the first stage temperature programming is 100 ℃, the end point temperature of the second stage temperature programming is 250 ℃, the speed of the first stage temperature programming is 3-5 ℃/min, preferably the speed of the second stage temperature programming is 0.1-1 ℃/min, and preferably the speed of the third stage temperature programming is 3-5 ℃/min.
4. The method of claim 1, wherein the carbon source precursor further comprises a flame retardant, the method further comprising a process of preparing the carbon source precursor, the process comprising:
carrying out first mixing on the starch and the flame retardant solution to obtain mixed slurry;
filtering and drying the mixed slurry to obtain the carbon source precursor;
the flame retardant solution is preferably selected from phosphate solutions, the phosphate is preferably selected from one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate and disodium hydrogen phosphate, the mass ratio of the starch to the phosphate is preferably 1: 0.2-2, and the particle size of the starch is preferably 5-50 μm.
5. A method for preparing an activated carbon electrode material, comprising:
step A, preparing carbonized particles by the preparation method of any one of claims 1 to 4;
and B, in a nitrogen atmosphere or an inert gas atmosphere, carrying out second sintering on a raw material system containing an activating agent and the carbonized particles to obtain the activated carbon electrode material.
6. The method according to claim 5, wherein the step B comprises:
step B1, carrying out second mixing on a solvent, the activating agent and the carbonized particles to obtain a first dispersion liquid;
step B2, drying the first dispersion liquid to obtain the raw material system;
step B3, performing the second sintering on the raw material system to obtain the activated carbon electrode material;
preferably, the activator is selected from any one or more of hydroxides and salts of alkali metals, and more preferably, the activator is selected from KOH, NaOH, ZnCl2Preferably the mass ratio of the carbonized particles to the activator is 1:1～10。
7. the method according to claim 6, wherein the raw material system further comprises a nitrogen source, and the step B comprises:
step B1, performing a second mixing of a nitrogen source, the solvent, the activator, and the carbonized particles to obtain the first dispersion;
step B2, drying the first dispersion liquid to obtain the raw material system;
step B3, performing the second sintering on the raw material system to obtain the activated carbon electrode material;
preferably, the nitrogen source is selected from one or more of urea, dicyandiamide and melamine, and the mass ratio of the carbonized particles, the activating agent and the nitrogen source is preferably 1: 1-10: 1-5.
8. The preparation method according to claim 6 or 7, wherein the second mixing is performed by ultrasonic dispersion, preferably the power of the ultrasonic dispersion is 10 to 40Kw and the time is 10 to 50 min; preferably, the temperature of the drying treatment is 60-120 ℃.
9. The preparation method according to any one of claims 5 to 8, wherein the second sintering is buried sintering, preferably the buried sintering uses petroleum coke as a cover, the temperature of the second sintering is 700-1000 ℃ and the time is 1-2 h, and preferably the temperature rise rate before the second sintering is 5-15 ℃/min.
10. A super capacitor, which comprises an electrode and an electrolyte, wherein the electrode comprises an activated carbon electrode material, and the activated carbon electrode material is prepared by the preparation method of any one of claims 5 to 9, and preferably has a porosity of 30-40% and a specific surface area of 1000m2/g～2000m2The particle diameter of the activated carbon electrode material is preferably 5 to 50 μm,preferably, the activated carbon electrode material is doped with nitrogen, and preferably, the content of nitrogen on the surface of the activated carbon electrode material is 1-5 wt%.
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