CN113511654B - Capacitance carbon and preparation method thereof - Google Patents
Capacitance carbon and preparation method thereof Download PDFInfo
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- CN113511654B CN113511654B CN202110411481.5A CN202110411481A CN113511654B CN 113511654 B CN113511654 B CN 113511654B CN 202110411481 A CN202110411481 A CN 202110411481A CN 113511654 B CN113511654 B CN 113511654B
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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
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- 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
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Abstract
The invention relates to capacitance carbon and a preparation method thereof, and relates to the technical field of capacitance carbon. The main technical scheme adopted is as follows: a preparation method of capacitance carbon comprises the following steps: a pretreatment source tempering step, namely performing pretreatment tempering on the biomass raw material to obtain a tempered biomass raw material; wherein the pretreatment quenching and tempering treatment comprises the steps of crushing, screening, acid washing, water washing and drying the biomass raw material; a low-temperature carbon fixation step, namely performing preoxidation treatment on the biomass raw material after the quenching and tempering treatment to obtain a preoxidation product; a carbonization step, in which the preoxidation product is carbonized to obtain a carbonized product; and an activation step, namely performing activation treatment on the carbonized product to obtain the capacitance carbon. According to the invention, after the pretreatment source quenching and tempering process and the low-temperature carbon fixing process are added, the purity of the capacitance carbon is improved, the performance of the capacitance carbon is optimized, and meanwhile, the yield of the capacitance carbon is also greatly improved.
Description
Technical Field
The invention relates to the technical field of capacitance carbon, in particular to capacitance carbon and a preparation method thereof.
Background
The super capacitor has the characteristics of high power, long service life, wide use temperature and the like, and has wide application prospect in the fields of electric vehicles, smart grids, portable electronic equipment and the like.
The porous carbon material has the characteristics of good conductivity, large specific surface area, stable physicochemical property, rich pore structure and the like, and becomes the electrode material of the super capacitor which is widely researched at present. The commercial super capacitor has very strict requirements on various indexes of the carbon-based electrode material, including ultrahigh purity, large specific surface area, porous structure, high conductivity, high compaction density, low cost and the like, and more than 90% of the carbon material depends on import at present. How to prepare the low-cost and high-performance capacitance carbon material becomes the difficult problem of 'neck' puzzling the development of the super capacitor industry in China.
At present, the method for preparing capacitance carbon by biomass is to directly carry out carbonization and activation treatment on biomass raw materials to prepare the capacitance carbon. However, the inventor of the invention finds that the existing method has the technical problems of more investment, less output, low yield and poor performance, and cannot meet the requirement of commercialized capacitance carbon.
Disclosure of Invention
In view of this, the present invention provides a capacitance carbon and a preparation method thereof, and mainly aims to improve the performance, purity and yield of a capacitance carbon material.
In order to achieve the purpose, the invention mainly provides the following technical scheme:
in one aspect, an embodiment of the present invention provides a method for preparing capacitance carbon, including the following steps:
pretreating a source to temper: carrying out pretreatment and thermal refining on the biomass raw material to obtain a thermal-refined biomass raw material; wherein the pretreatment quenching and tempering treatment comprises the steps of crushing, screening, acid washing, water washing and drying the biomass raw material;
and (3) low-temperature carbon fixation: carrying out pre-oxidation treatment on the biomass raw material after the quenching and tempering treatment to obtain a pre-oxidation product;
a carbonization step: carbonizing the pre-oxidized product to obtain a carbonized product;
an activation step: and carrying out activation treatment on the carbonized product to obtain the capacitance carbon.
Preferably, in the step of the acid washing treatment: the adopted acid solution comprises one or more of hydrochloric acid, nitric acid and sulfuric acid; preferably, the concentration of the acid solution is 0.1-5mol/L; preferably, the step of acid washing treatment specifically comprises: soaking a biomass raw material in the acid solution; preferably, the soaking time is 0.1-24h.
Preferably, before the step of conditioning the pretreatment source, the method further comprises: and cleaning and drying the biomass raw material.
Preferably, in the step of conditioning the pretreatment source: the biomass raw material after being crushed is sieved by a sieve with 40 to 200 meshes.
Preferably, in the step of conditioning the pretreatment source: and washing the biomass raw material subjected to acid washing with deionized water until the biomass raw material is neutral.
Preferably, in the step of conditioning the pretreatment source: and drying the washed biomass raw material at the temperature of 60-90 ℃ for 2-15h.
In the low-temperature carbon fixation step: heating the biomass raw material subjected to thermal refining treatment to a pre-oxidation treatment temperature in an air or oxygen atmosphere, and performing pre-oxidation treatment; preferably, the pre-oxidation treatment temperature is 100-350 ℃, and the pre-oxidation treatment time is 0.5-10h; preferably, in the process of heating the biomass raw material after the thermal refining to the pre-oxidation treatment temperature: the heating rate is 0.1-20 deg.C/min.
In the carbonization step: under the protective atmosphere (nitrogen or argon), heating the pre-oxidized product to a carbonization temperature, carrying out carbonization treatment, and cooling to room temperature to obtain a carbonized product; preferably, the carbonization temperature is 400-1000 ℃, and the carbonization treatment time is 0.5-10h; preferably, during the heating of the pre-oxidation product to the charring temperature: the heating rate is 0.1-20 ℃/min; preferably, after the pre-oxidation treatment in the low-temperature carbon fixation step is finished, the atmosphere is switched to a protective atmosphere, and the pre-oxidation product is heated from the pre-oxidation treatment temperature to the carbonization temperature.
Preferably, in the activation step: soaking the carbonized product and an activating agent in deionized water according to a set mass ratio for soaking treatment; drying the product after the dipping treatment; and then, heating the product of the dipping treatment to an activation temperature for activation treatment under a protective atmosphere, cooling to room temperature, and washing with water to be neutral to obtain the capacitance carbon. Preferably, the activation temperature is 300-1000 ℃, and the activation treatment time is 0.5-10h; preferably, during heating of the product of the impregnation treatment to the activation temperature: the heating rate is 0.1-20 ℃/min; preferably, the activating agent is KOH, naOH or K 2 CO 3 、Na 2 CO 3 、ZnCl 2 、AlCl 3 And H 3 PO 4 One or more of the above; preferably, in the step of the impregnation treatment: the set mass ratio is 1: (0.1-100). Preferably, the time of the dipping treatment is 0.5 to 24 hours.
Preferably, the biomass raw material is any one of corn leaves, straws, rice hulls and fruit shells.
Preferably, the yield of the capacitance carbon prepared by the preparation method of the capacitance carbon is 25-40%.
In another aspect, an embodiment of the present invention provides a capacitor carbon; wherein the first discharge specific capacitance of the organic system of the capacitance carbon is more than or equal to 35.0F/g; the first discharge specific capacitance of the inorganic system of the capacitance carbon is more than or equal to 65.0F/g; preferably, the cycling stability (the specific capacity retention rate of the capacitance carbon) of the capacitance carbon is more than or equal to 98 percent;
preferably, the content of metallic elements, namely iron element, in the capacitance carbon is not more than 50mg/kg, the content of nickel element is not more than 50mg/kg, the content of cobalt element is not more than 20mg/kg, the content of copper element is not more than 20mg/kg, the content of sodium element is not more than 100mg/kg, the content of potassium element is not more than 200mg/kg, and the content of aluminum element is not more than 200mg/kg;
preferably, the capacitance carbon is prepared by the preparation method of any one of the above methods.
Compared with the prior art, the capacitance carbon and the preparation method thereof have the following beneficial effects:
the preparation method of the capacitance carbon provided by the embodiment of the invention adopts the treatment technologies of crushing, sieving, acid washing, water washing to neutrality and drying to carry out pretreatment source conditioning on the biomass raw material, solves the problems of high water content, more impurities, irregular particle size and shape distribution, low stacking density, low equipment utilization rate, poor product stability and the like of the biomass raw material, improves the process consistency of the raw material, and is coupled with the subsequent low-temperature carbon fixation-carbonization-activation process technology to prepare the capacitance carbon material with high yield, reasonable particle size distribution, high purity and high specific capacitance. The invention adds a preoxidation process to stabilize the carbon skeleton to prevent carbon elements from being CO and CO 2 The escape of carbon-containing gas micromolecules and the reduction of the generation of liquid products reduce the loss of carbon elements, the yield of solid carbon is improved by 5-20 percent compared with the traditional process, the production cost is reduced, and meanwhile, the addition of the pre-oxidation process does not cause the result of overhigh oxygen content of the product; therefore, thisThe low-temperature carbon fixation technology has important significance for the large-scale production of the biomass-based capacitance carbon material.
In conclusion, the preparation method of the capacitance carbon provided by the invention adds a pretreatment source quenching and tempering technology and a low-temperature carbon fixing technology before carbonization, so that the purity of the capacitance carbon material is improved, the performance of the capacitance carbon material is optimized, and meanwhile, the yield of the capacitance carbon is greatly improved.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to make the technical solutions of the present invention practical in accordance with the contents of the specification, the following detailed description is given of preferred embodiments of the present invention with reference to the accompanying drawings.
Drawings
Fig. 1 is a process flow chart of a method for preparing capacitance carbon provided in example 1 of the present invention.
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the predetermined object, the following detailed description of the embodiments, structures, features and effects according to the present invention will be made with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
On one hand, the embodiment of the invention provides a preparation method of capacitance carbon, which mainly comprises the following process flows: and (3) carrying out pretreatment source conditioning, low-temperature carbon fixation, carbonization and activation processes on the biomass raw material in sequence to obtain the biomass-based capacitance carbon. The method comprises the following specific steps:
1) A cleaning step: and cleaning and drying the biomass raw material.
2) Pretreating a source to temper: the biomass raw material is subjected to pretreatment and thermal refining, and the pretreatment and thermal refining specifically comprises crushing, sieving, acid washing, deionized water washing to neutrality and drying treatment.
The acid solution used in the acid washing treatment is one of hydrochloric acid, nitric acid and sulfuric acid, or the acid solution is a mixed solution of a plurality of acids of hydrochloric acid, nitric acid and sulfuric acid. Preferably, the concentration of the acid solution is 0.1-5mol/L; wherein, the time length of soaking the screened biomass raw material in the acid solution is 0.1-24h.
Wherein the biomass raw material after being crushed is sieved by a sieve of 40-200 meshes. Here, it is required to pass a 40-200 mesh sieve. The selection of the particle size of the raw material is directly related to the subsequent acid washing, pre-oxidation, carbonization and activation processes, and comprises the determination of the conditions of acid concentration, heating temperature, heat preservation time, heating rate, dipping time and the like. Too small a particle size may result in a reduced char yield. Too large a particle size can result in too large a particle size of the final capacitive carbon product, resulting in a decrease in electrochemical performance.
And drying the washed biomass raw material at the temperature of 60-90 ℃ for 2-15h.
3) And (3) low-temperature carbon fixation: performing low-temperature pre-oxidation treatment on the biomass raw material subjected to the quality treatment in a tubular furnace in the air or oxygen atmosphere; wherein the pre-oxidation treatment temperature is 100-350 ℃, the heating rate is 0.1-20 ℃/min, and the pre-oxidation treatment time is 0.5-10h.
4) A carbonization step: and (3) switching the reaction atmosphere to nitrogen or argon, continuously heating to 400-1000 ℃ for carbonization treatment at the heating rate of 0.1-20 ℃/min for 0.5-10h, and then cooling to room temperature to obtain a carbonized product.
5) An activation step: and (2) soaking the carbonized product and an activating agent in deionized water according to a preset mass ratio, drying after soaking treatment (preferably, the soaking treatment time is 0.5-24h; the use amount of the deionized water does not exceed the use amount of the carbonized product, so that the carbonized product is uniformly soaked in an activating agent aqueous solution), and then performing activating treatment under a protective atmosphere. The protective atmosphere is nitrogen or argon, the activation temperature is 300-1000 ℃, the heating rate is 0.1-20 ℃/min, and the activation treatment time is 0.5-10h. And then cooling to room temperature, and washing with deionized water to be neutral to obtain the capacitance carbon.
Wherein the activating agent is KOH, naOH or K 2 CO 3 、Na 2 CO 3 、ZnCl 2 、AlCl 3 And H 3 PO 4 Or the activating agent is KOH, naOH or K 2 CO 3 、Na 2 CO 3 、ZnCl 2 、AlCl 3 And H 3 PO 4 A mixture of a plurality of (a). The preset mass ratio of the carbonized product to the activating agent is 1:0.1-100.
In the prior art, the method for preparing the capacitance carbon by using the biomass raw material is to directly carbonize and activate the biomass raw material to prepare the capacitance carbon. Compared with the prior art, the preparation process of the capacitive carbon provided by the invention adds two technologies of pretreatment source tempering and low-temperature carbon fixation before the carbonization step, namely the biomass-based capacitive carbon is prepared by adopting a pretreatment source tempering-low Wen Gutan-carbonization-activation process. Compared with the prior art, the process provided by the invention has the advantages that the performance of the capacitance carbon material is optimized, the purity is improved and the yield of the capacitance carbon is greatly improved after the pretreatment source quenching and tempering process and the low-temperature carbon fixation process are additionally arranged. The specific analysis is as follows:
first, a pretreatment source conditioning technology
Compared with the traditional fossil fuel, the biomass raw material has the disadvantages of low bulk density and energy density, high water content, strong hygroscopicity (hydrophilicity), difficult grinding, poor liquidity and the like; these disadvantages pose challenges and problems to the biomass thermochemical conversion and treatment process:
(1) The low bulk density is detrimental to the storage and transportation of the biomass feedstock, resulting in increased costs for storage and transportation of the biomass feedstock. The low energy density limits the overall capacity scale of the biomass thermodynamic system, reducing the economics of the biomass energy source. High water content in the biomass raw material can delay pyrolysis reaction, influence the yield of pyrolysis products and the stability of the products, and increase the heat supply cost. In addition, the defects of high water content, irregular particle size and shape distribution, low bulk density and the like of the biomass raw material cause poor fluidity of the biomass raw material, and further cause the failure of a biomass raw material feeding system, which is a main factor for limiting the further amplification of the industrial utilization scale of the biomass. On the other hand, due to the difference of biomass raw material types and production places, wherein the relative components of hemicellulose, cellulose, lignin and ash are greatly changed, the biomass pyrolysis characteristics and the product distribution are greatly influenced.
Therefore, the pretreatment source conditioning technology can be used for improving certain physical and chemical properties of the biomass raw materials and is coupled with the subsequent pyrolysis technology, the purpose of maximizing the utilization value of pyrolysis products is achieved, and meanwhile, the difference among different biomass raw materials is reduced due to the use of the technology, so that the technology disclosed by the invention has universal applicability.
(2) The particle size and the morphology of the raw materials influence the dynamic parameter change (drying, heating rate and reaction rate) of biomass particles and the particle size and the morphology of the final product capacitance carbon material; the particle size distribution and the particle size of the capacitance carbon material influence the specific surface area and the tap density, so that the processing technology and the rate capability of the electrode material are influenced.
(3) The activated carbon is used as a key electrode material, and the purity of the activated carbon directly determines the performance of the supercapacitor. The metal ions (iron, nickel, cobalt, copper, sodium, potassium, aluminum, etc.) in the activated carbon undergo redox reactions during charging to generate leakage current, thereby causing the voltage of the capacitor to drop. At the same time, the ions also affect the cycling stability of the capacitor, resulting in a reduced lifetime. Therefore, the removal of impurity metal ions and the improvement of the purity of the activated carbon have important significance for improving the performance of the capacitor.
Aiming at the problems of the biomass raw material, the invention adopts the treatment technologies of crushing, sieving, acid washing, water washing to neutrality and drying to carry out pretreatment source conditioning on the biomass raw material, solves the problems of high water content, more impurities, irregular particle size and shape distribution, low stacking density, low equipment utilization rate, poor product stability and the like of the raw material, improves the process consistency of the raw material, and is coupled with the subsequent low-temperature carbon fixation-carbonization-activation process technology to prepare the capacitance carbon material with high yield, reasonable particle size distribution, high purity and high specific capacitance.
Here, repeated emphasis is given to: the biomass raw material has the following problems: (1) High water content in the biomass raw material can delay pyrolysis reaction, influence the yield and product stability of pyrolysis products, and increase heat supply cost, so that the raw material is dried; (2) The size and shape distribution of the raw material particles can influence mass transfer and heat transfer of the subsequent process, so that the raw material is crushed and sieved; (3) The relative composition of hemicellulose, cellulose, lignin and ash in the raw material is greatly changed due to the difference of biomass types and production places, the biomass pyrolysis characteristics and the product distribution are greatly influenced, the raw material is purified through acid treatment, the difference among different biomass raw materials is reduced, and the subsequent process has universal applicability. Based on this, through long-term and large-scale experimental research, the particle sizes with different meshes are matched with corresponding processes of low-temperature carbon fixation, carbonization, activation and the like, and the final physical and chemical properties of the target product of the invention can be obtained. "move the whole body by pulling one movement", there is a relationship of correlation and coupling between each process parameter.
Second, low temperature carbon sequestration
In the prior art, the problems of more investment, less output and low yield exist in the process of preparing the carbon material by using the biomass. The advantages of low equipment productivity and low raw material cost can be reduced, and the commercialization requirement of the capacitance carbon can not be met. Therefore, the improvement of the carbon yield becomes a core problem of the industrial production of the biomass carbon material.
The pyrolysis of the biomass raw material can generate gas, liquid and solid three-state products, and carbon elements can be CO and CO 2 And the carbon-containing gas micromolecules, liquid products such as acids, phenols, ketones, alcohols, esters and the like and solid carbon are distributed, and the yield of the three products has a competitive relationship. Based on the method, the low-temperature carbon fixation technology is added to the existing manufacturing process, and the carbon skeleton is stabilized through pre-oxidation to prevent carbon elements from being CO and CO 2 And the escape of carbon-containing gas micromolecules and the reduction of the generation of liquid products reduce the loss of carbon elements, improve the yield of solid carbon by 5-20 percent compared with the traditional process and reduce the production cost. In addition, oxygen-containing functional groups on the surface of the capacitance carbon have strong electrochemical activity and are easy to generate decomposition reaction during charging and discharging, so that the cycle stability of the super capacitor is reduced. At the same time, the oxygen-containing functional groups reduce the materialThe equivalent series internal resistance is increased, and the power density and the cycle life of the capacitor are reduced. Therefore, the method has great scientific significance and application value in controlling the oxygen content of the capacitance carbon material. In the invention, the addition of the low-temperature carbon fixation technology has no consequence of over-high oxygen content of the product. Therefore, the low-temperature carbon fixation technology has important significance for the large-scale production of the biomass-based capacitance carbon material.
The invention is further illustrated by the following specific experimental examples:
example 1
In this example, a capacitance carbon is prepared, as shown in fig. 1, by the following main preparation steps:
1) Cleaning and drying the biomass raw material corn leaves.
2) Pretreating a source to temper:
crushing the corn leaves treated in the step 1), sieving the crushed corn leaves with a 60-mesh sieve, then soaking the crushed corn leaves in a proper amount of 1mol/L hydrochloric acid solution, washing the crushed corn leaves with deionized water to be neutral after 12 hours, and drying the washed corn leaves (the drying temperature is 60 ℃ and the drying time is 15 hours) to obtain the corn leaves (namely, the modified corn leaves are powdery) after the modification treatment.
3) Low temperature carbon fixation step
Putting 10g of the tempered corn leaves into a tube furnace for pre-oxidation treatment to obtain pre-oxidized corn leaves; wherein the pre-oxidation treatment temperature is 200 ℃, the pre-oxidation treatment time (namely, the heat preservation time at the pre-oxidation treatment temperature) is 2h, and the heating rate in the process of heating the modified corn leaves to the pre-oxidation treatment temperature is 2 ℃/min.
4) Carbonization step
Carbonizing the pre-oxidized corn leaves in a tubular furnace in nitrogen atmosphere to obtain carbonized corn leaves; wherein the carbonization temperature is 600 ℃, and the carbonization treatment time (the heat preservation time at the carbonization temperature) is 4h; the heating rate in the process of heating the modified corn leaves to the carbonization temperature is 2 ℃/min.
5) Step of activation
Soaking the carbonized corn leaves and KOH in deionized water according to the mass ratio of 1:4 for 12 hours; drying the corn leaves after the dipping treatment, then putting the corn leaves into a tube furnace, and carrying out activation treatment in a nitrogen atmosphere; wherein the activation temperature is 800 ℃, the activation treatment time is 1h, and the temperature rise rate in the process of heating the corn leaves after the dipping treatment to the activation temperature is 2 ℃/min. And after the activation is finished, cooling, taking out, washing with acid and water to be neutral, and drying to obtain the capacitance carbon.
Example 2
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
in the activation step of this embodiment, the selected activating agent is sodium carbonate, and the carbonized corn leaves and the sodium carbonate are mixed according to a mass ratio of 1:10, and immersing in deionized water for 20 hours.
The rest steps are completely consistent.
Example 3
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
pretreating a source to temper: crushing the corn leaves treated in the step 1), sieving the crushed corn leaves with a 60-mesh sieve, then soaking the crushed corn leaves in a proper amount of 0.1mol/L sulfuric acid solution, washing the crushed corn leaves with deionized water to be neutral after 24 hours, and drying the washed corn leaves to obtain the corn leaves subjected to thermal refining (namely, the thermal refining corn leaves are powdery).
The rest steps are completely consistent.
Example 4
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
pretreating a source to temper: crushing the corn leaves treated in the step 1), sieving the crushed corn leaves with a 60-mesh sieve, then soaking the crushed corn leaves in a proper amount of 5mol/L hydrochloric acid solution, washing the crushed corn leaves with deionized water to be neutral after 0.1 hour, and drying the washed corn leaves to obtain the corn leaves subjected to thermal refining treatment (namely, the thermal refining corn leaves are powdery).
The rest steps are completely consistent.
Example 5
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
and (3) low-temperature carbon fixation: putting 10g of the tempered corn leaves into a tube furnace for pre-oxidation treatment to obtain pre-oxidized corn leaves; wherein the pre-oxidation treatment temperature is 100 ℃, the pre-oxidation treatment time (namely, the heat preservation time at the pre-oxidation temperature) is 10h, and the heating rate in the process of heating the modified corn leaves to the pre-oxidation temperature is 0.1 ℃/min.
The rest steps are completely consistent.
Example 6
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
and (3) low-temperature carbon fixation: putting 10g of the tempered corn leaves into a tube furnace for pre-oxidation treatment to obtain pre-oxidized corn leaves; wherein the pre-oxidation treatment temperature is 350 ℃, the pre-oxidation treatment time (namely, the heat preservation time at the pre-oxidation temperature) is 0.5h, and the heating rate in the process of heating the modified corn leaves to the pre-oxidation temperature is 15 ℃/min.
The rest steps are completely consistent.
Example 7
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
a carbonization step: carrying out high-temperature carbonization on the preoxidized corn leaves in a tubular furnace under the nitrogen atmosphere to obtain carbonized corn leaves; wherein the carbonization temperature is 400 ℃, and the carbonization treatment time (the heat preservation time at the carbonization temperature) is 10h; the heating rate in the process of heating the modified corn leaves to the carbonization temperature is 1 ℃/min.
The rest steps are completely consistent.
Example 8
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
a carbonization step: carrying out high-temperature carbonization on the preoxidized corn leaves in a tubular furnace under the nitrogen atmosphere to obtain carbonized corn leaves; wherein the carbonization temperature is 1000 ℃, and the carbonization treatment time (the heat preservation time at the carbonization temperature) is 1h; the heating rate of the modified corn leaves in the process of heating to the carbonization temperature is 18 ℃/min.
The rest steps are completely consistent.
Example 9
In the embodiment, the biomass raw material corn leaves are adopted to prepare the capacitance carbon; this example differs from the preparation procedure of example 1 in that:
the activation temperature in the activation step is 600 ℃, and the time of the activation treatment is 3h.
The rest steps are completely consistent.
Example 10
In the embodiment, the capacitance carbon is prepared by using straw as a biomass raw material, and the specific preparation steps are completely the same as those in the embodiment 1 except that the raw materials are different.
Example 11
In the embodiment, the capacitance carbon is prepared by using rice hulls as the biomass raw materials, and the specific preparation steps are completely the same as those in the embodiment 1 except that the raw materials are different.
Comparative example 1
Comparative example 1 a capacitance carbon was prepared by the following specific steps:
carbonizing: cleaning and drying the biomass raw material corn leaves; and then, putting the corn leaves into a tube furnace, and carrying out high-temperature carbonization in a nitrogen atmosphere, wherein the carbonization temperature is 600 ℃, the carbonization time (namely, the heat preservation time at the carbonization temperature) is 4h, and the temperature rise rate is 2 ℃/min, so as to obtain the carbonized corn leaves.
An activation step: soaking the carbonized corn leaves and KOH in deionized water for 12 hours according to the mass ratio of 1:4; drying the soaked corn leaves, then putting the corn leaves into a tube furnace, and activating the corn leaves in a nitrogen atmosphere; wherein the activation temperature is 800 ℃, and the activation time (namely, the heat preservation time at the activation temperature) is 1h; the heating rate of the soaked corn leaves in the process of heating to the activation temperature is 2 ℃/min. And after the activation is finished, cooling, taking out, washing with acid and water to be neutral, and drying to obtain the capacitance carbon.
Table 1 is a summary of the properties of the capacitive carbons prepared in examples 1-11 of the present invention.
TABLE 1
Wherein, table 2 shows the yield data of the capacitance carbon prepared in the inventive example and the comparative example 1.
TABLE 2
| Capacity charcoal yield (%) | |
| Comparative example 1 | 17.2 |
| Example 1 | 25.6 |
| Example 2 | 29.1 |
| Example 3 | 28.2 |
| Example 4 | 27.9 |
| Example 5 | 35.5 |
| Example 6 | 37.4 |
| Example 7 | 40 |
| Example 8 | 36.3 |
| Example 9 | 31.7 |
| Example 10 | 28.2 |
| Example 11 | 30.6 |
Wherein, table 3 shows the particle size comparison of the capacitance carbon prepared in the inventive example and comparative example 1.
TABLE 3
| D10/μm | D50/μm | D90/μm | |
| Comparative example 1 | 5.694 | 15.286 | 43.850 |
| Example 1 | 2.145 | 6.417 | 15.366 |
| Example 2 | 2.335 | 5.823 | 17.651 |
| Example 3 | 2.653 | 7.846 | 15.237 |
| Example 4 | 2.059 | 6.855 | 18.112 |
| Example 5 | 2.505 | 6.364 | 16.830 |
| Example 6 | 2.267 | 7.142 | 17.287 |
| Example 7 | 2.482 | 6.818 | 18.059 |
| Example 8 | 2.227 | 6.952 | 17.854 |
| Example 9 | 2.586 | 7.583 | 18.302 |
| Example 10 | 3.004 | 5.997 | 15.339 |
| Example 11 | 2.741 | 6.028 | 17.295 |
Wherein, table 4 shows the comparison of the contents of metal elements in the capacitor carbons prepared in the examples of the present invention and comparative example 1.
TABLE 4
Wherein, table 5 shows the comparison of CHONS element content in the capacitance carbon prepared by the embodiment of the invention and the comparative example 1.
TABLE 5
| C | H | N | S | O | |
| Comparative example 1 | 89.27 | 1.07 | 0.26 | 0.10 | 1.796 |
| Example 1 | 95..37 | 0.96 | 0.20 | 0.00 | 1.814 |
| Example 2 | 96.02 | 0.82 | 0.21 | 0.00 | 1.020 |
| Example 3 | 95.89 | 1.58 | 0.19 | 0.00 | 1.332 |
| Example 4 | 95.91 | 1.32 | 0.20 | 0.00 | 1.565 |
| Example 5 | 94.67 | 1.19 | 0.18 | 0.00 | 1.245 |
| Example 6 | 95.32 | 1.03 | 0.20 | 0.00 | 1.801 |
| Example 7 | 94.88 | 0.85 | 0.19 | 0.00 | 1.367 |
| Example 8 | 95.33 | 1.62 | 0.25 | 0.00 | 1.462 |
| Example 9 | 96.27 | 0.98 | 0.32 | 0.00 | 1.774 |
| Example 10 | 94.26 | 1.14 | 0.11 | 0.00 | 1.558 |
| Example 11 | 95.15 | 1.27 | 0.26 | 0.00 | 1.349 |
Wherein, table 6 shows the specific capacitance ratios (inorganic system) in the preparation of the capacitance carbon of the examples of the present invention and comparative example 1.
TABLE 6
| Inorganic system specific capacitance/(F/g) | |
| Comparative example 1 | 54.9 |
| Example 1 | 66.3 |
| Example 2 | 68.1 |
| Example 3 | 67.3 |
| Example 4 | 66.2 |
| Example 5 | 67.5 |
| Example 6 | 65.2 |
| Example 7 | 69.3 |
| Example 8 | 67.7 |
| Example 9 | 68.6 |
| Example 10 | 67.9 |
| Example 11 | 67.0 |
Wherein, table 7 shows comparison of cycle stability (10000 cycles) in the preparation of the capacitor carbon according to the example of the present invention and the comparative example 1.
TABLE 7
| Specific capacity retention (%) | |
| Comparative example 1 | 94.7 |
| Example 1 | 98.6 |
| Example 2 | 98.9 |
| Example 3 | 98.5 |
| Example 4 | 99.3 |
| Example 5 | 98.7 |
| Example 6 | 99.0 |
| Example 7 | 98.9 |
| Example 8 | 99.2 |
| Example 9 | 99.1 |
| Example 10 | 99.4 |
| Example 11 | 98.8 |
As is evident from the data of the above examples, comparative example 1 and tables 1-7: the preparation method of the capacitance carbon provided by the embodiment of the invention can improve the yield, purity and performance of the capacitance carbon.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are still within the scope of the technical solution of the present invention.
Claims (17)
1. The preparation method of the capacitance carbon is characterized by comprising the following steps:
pretreating a source to temper: carrying out pretreatment and tempering on the biomass raw material to obtain a tempered biomass raw material; wherein the pretreatment quenching and tempering treatment comprises the steps of crushing, screening, acid washing, water washing and drying the biomass raw material; wherein the biomass material is corn leaves; sieving the crushed biomass raw material through a 40-200 mesh sieve; in the step of the acid washing treatment: the adopted acid solution comprises one or more of hydrochloric acid, nitric acid and sulfuric acid; washing the biomass raw material subjected to acid washing with deionized water until the biomass raw material is neutral;
and (3) low-temperature carbon fixation: carrying out pre-oxidation treatment on the biomass raw material after the quenching and tempering treatment to obtain a pre-oxidation product; heating the biomass raw material subjected to thermal refining treatment to a pre-oxidation treatment temperature in an air or oxygen atmosphere, and performing pre-oxidation treatment; wherein the pre-oxidation treatment temperature is 100-350 ℃, and the pre-oxidation treatment time is 0.5-10h; the low-temperature carbon fixation step stabilizes a carbon skeleton through pre-oxidation, prevents carbon elements from escaping as carbon-containing gas micromolecules, and reduces the generation of liquid products, thereby reducing the loss of the carbon elements;
a carbonization step: carbonizing the pre-oxidized product to obtain a carbonized product;
an activation step: activating the carbonized product to obtain capacitance carbon; soaking the carbonized product and an activating agent in deionized water according to a set mass ratio for soaking treatment; drying the product after the dipping treatment; then, under the protective atmosphere, heating the product of the dipping treatment to an activation temperature for activation treatment, cooling to room temperature, and washing with water to be neutral to obtain capacitance carbon; the activation temperature is 300-1000 ℃, and the activation treatment time is 0.5-10h;
wherein the yield of the capacitance carbon prepared by the preparation method of the capacitance carbon is 25-40%.
2. The process for producing capacitive carbon according to claim 1,
the concentration of the acid solution is 0.1-5mol/L.
3. The process for producing capacitive carbon according to claim 1,
the pickling treatment comprises the following specific steps: the biomass feedstock is soaked in the acid solution.
4. The method of producing capacitive carbon according to claim 3,
the soaking time is 0.1-24h.
5. The process for producing capacitive carbon according to claim 1,
before the step of conditioning the pretreatment source, the method further comprises the following steps: and cleaning and drying the biomass raw material.
6. The method of making capacitive carbon of claim 1, wherein in the preconditioning source conditioning step:
and drying the washed biomass raw material at the temperature of 60-90 ℃ for 2-15h.
7. The method for preparing capacitive carbon according to claim 1, wherein in the low-temperature carbon fixation step:
in the process of heating the biomass raw material after the thermal refining treatment to the pre-oxidation treatment temperature: the heating rate is 0.1-20 ℃/min.
8. The method for producing capacitive carbon according to claim 1, wherein in the carbonizing step:
and heating the pre-oxidized product to a carbonization temperature under a protective atmosphere, carrying out carbonization treatment, and cooling to room temperature to obtain a carbonized product.
9. The method of producing capacitive carbon according to claim 8,
the carbonization temperature is 400-1000 ℃, and the carbonization treatment time is 0.5-10h.
10. The method of producing capacitive carbon according to claim 8,
during the heating of the pre-oxidation product to the charring temperature: the heating rate is 0.1-20 deg.C/min.
11. The method of producing capacitive carbon according to claim 8,
after the pre-oxidation treatment in the low-temperature carbon fixation step is finished, the atmosphere is switched to a protective atmosphere, and the pre-oxidation product is heated to the carbonization temperature from the pre-oxidation treatment temperature.
12. The process for producing capacitive carbon according to claim 1,
during the heating of the impregnated product to the activation temperature: the heating rate is 0.1-20 deg.C/min.
13. The method of producing capacitive carbon according to claim 1,
the activating agent is KOH, naOH or K 2 CO 3 、Na 2 CO 3 、ZnCl 2 、AlCl 3 And H 3 PO 4 One or more of them.
14. The process for producing capacitive carbon according to claim 1,
in the step of the impregnation treatment: the set mass ratio is 1: (0.1-100).
15. The method of producing capacitive carbon according to claim 1,
the time of the dipping treatment is 0.5-24h.
16. The capacitance carbon is characterized in that the first discharge specific capacitance of an organic system of the capacitance carbon is more than or equal to 35.0F/g; the first discharge specific capacitance of the inorganic system of the capacitance carbon is more than or equal to 65.0F/g; the cycling stability of the capacitance carbon is more than or equal to 98 percent;
wherein the capacitance carbon is prepared by the preparation method of the capacitance carbon as claimed in any one of claims 1 to 15.
17. The capacitive carbon of claim 16,
the content of metallic elements, namely iron element, is not more than 50mg/kg, the content of nickel element is not more than 50mg/kg, the content of cobalt element is not more than 20mg/kg, the content of copper element is not more than 20mg/kg, the content of sodium element is not more than 100mg/kg, the content of potassium element is not more than 200mg/kg, and the content of aluminum element is not more than 200mg/kg.
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