CN113060729A - Method for preparing super-capacitor electrode material active carbon by adopting carbon ring layer-to-layer spacing expansion treatment - Google Patents
Method for preparing super-capacitor electrode material active carbon by adopting carbon ring layer-to-layer spacing expansion treatment Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 240
- 239000003990 capacitor Substances 0.000 title claims abstract description 55
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000007772 electrode material Substances 0.000 title claims abstract description 29
- 239000010410 layer Substances 0.000 claims abstract description 71
- 238000006243 chemical reaction Methods 0.000 claims abstract description 67
- 239000011229 interlayer Substances 0.000 claims abstract description 34
- 238000002360 preparation method Methods 0.000 claims abstract description 22
- 238000001994 activation Methods 0.000 claims abstract description 15
- 230000007547 defect Effects 0.000 claims abstract description 9
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 6
- 230000003647 oxidation Effects 0.000 claims abstract description 4
- 238000011049 filling Methods 0.000 claims description 34
- 239000007789 gas Substances 0.000 claims description 32
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 28
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 22
- 230000001681 protective effect Effects 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 15
- 229910052786 argon Inorganic materials 0.000 claims description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 13
- 239000000843 powder Substances 0.000 claims description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000012495 reaction gas Substances 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 5
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
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- 238000000227 grinding Methods 0.000 claims description 2
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- 238000005406 washing Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 abstract description 20
- 229910002804 graphite Inorganic materials 0.000 abstract description 16
- 239000010439 graphite Substances 0.000 abstract description 16
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- 238000003780 insertion Methods 0.000 abstract description 7
- 230000037431 insertion Effects 0.000 abstract description 7
- 230000009471 action Effects 0.000 abstract description 2
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract 4
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract 3
- 239000001569 carbon dioxide Substances 0.000 abstract 2
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- 238000002441 X-ray diffraction Methods 0.000 description 5
- 125000004432 carbon atom Chemical group C* 0.000 description 5
- 238000004146 energy storage Methods 0.000 description 5
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- 244000060011 Cocos nucifera Species 0.000 description 4
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/354—After-treatment
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/24—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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a preparation method for carbon ring layer-to-layer spacing expansion treatment of super-capacitor electrode material active carbon. The method comprises treating the active carbon product prepared by three-step physical activation process with CO2The characteristic that the carbon dioxide and the C are not easy to generate violent oxidation action at a certain high temperature is that a weaker reaction is generated by introducing a carbon dioxide atmosphere and controlling the reaction temperature and prolonging the calcination time so as to form vacancies (defects) in the carbon ring layer and reduce the van der Waals bond interlayer force between the carbon layers so as to regulate and control the interlayer spacing of the graphite carbon ring layer. The prepared activated carbon has the carbon ring interlayer spacing of 0.384-0.405 nm, which is far larger than the carbon ring interlayer spacing of 0.335nm of normal graphite, and when the activated carbon is used as an electrode material of a super capacitor, the activated carbon is used as electrolyte ions of the super capacitorThe insertion between the ring layers provides an opportunity, the effective specific surface area is increased, and the specific capacity is improved, so that the super capacitor with high energy density can be prepared.
Description
Technical Field
The invention belongs to the field of preparation and processing of activated carbon materials, particularly relates to activated carbon for processing and processing electrode materials of a supercapacitor, and more particularly relates to a preparation and processing method for expanding the layer-to-layer spacing of carbon rings by offline processing of an activated carbon electrode material of a coconut shell activated carbon supercapacitor, which is prepared continuously and industrially.
Background
Super capacitors have attracted much attention as a new type of energy storage element, and have been studied extensively. Although the energy storage capacity of the capacitor is lower than that of a secondary battery, the capacitor is higher than that of a traditional capacitor by several orders of magnitude, and the capacitor has the characteristics of high power density, high safety, long cycle life, capability of realizing rapid charge and discharge and the like. The principle is to store electric energy by utilizing an electric double layer formed on the surface of an electrode or a generated two-dimensional or quasi two-dimensional Faraday reaction. The double electric layer type of the electrode material of the electrochemical capacitor is generally composed of a carbon material with high specific surface area, and the carbon electrode does not cause harm to producers or users in the production and use processes and is also beneficial to environmental protection. For carbon having a high specific surface area, it is practically realized by preparing a very fine pore structure, whereas voids (pore diameters) containing a liquid electrolyte are very short and small, and the electrolyte stays near the surface of these pores, constituting a large specific surface area and forming a large number of electric double layers. The use of large specific area materials has significant advantages such as low effective operating current density and high specific electric double layer capacitance. The activated carbon is an important electrode material of the super capacitor, and the performance, particularly the electricity storage performance of the activated carbon is directly influenced by the pore distribution and the internal resistance of a system when the super capacitor works. Actually, the graphite type supercapacitor active carbon electrode material prepared by using coconut shell raw materials and a water vapor physical activation method has excellent performance, and DuBrassica juncea has been subjected to a series of researches (such as an industrial preparation step-by-step purification method CN109592681B, a twice-activation industrial preparation method CN109850892B and a three-step physical activation preparation method CN109592680A), so that a high-density specific pore volume is formed, and the capacitance performance of the commercial supercapacitor active carbon electrode material can be comparable to the current commercial performance.
Although the conductivity of the graphite is better than that of the common carbon, the carbon electrode prepared by the graphite type activated carbon electrode is expected to improve the conductivity of the activated carbon, so that the internal resistance is reduced, and the energy storage and other application characteristics of the activated carbon when the activated carbon is used as a super capacitor electrode material are improved. However, the internal resistance of the electrode is related to the ability of the electrolyte ions to adsorb and desorb when forming an electric double layer, in addition to the conductivity of the material itself. When the electrolyte ions are difficult to flow into the inside of the micropores to cover the surface of the inner pores or difficult to leave, the internal resistance is increased, and the electricity storage performance is lowered. The conductivity of the carbon is related to the contact resistance introduced by the contact between the activated carbon material and particles forming the porous matrix, namely the conductivity of the activated carbon which is affected by the contact between the activated carbon material and the particles during the electrode preparation by tabletting; the capacity of the electrolyte ions of the super capacitor for adsorbing and separating from the effective micropore surface of the active carbon electrode is actually related to the transmission resistance of the ions, and the larger the capacity of the electrolyte ions for adsorbing and separating from the effective surface is, the easier the transmission is shown, the internal resistance of the super capacitor system is small, the smaller the energy consumed by the capacitor in the self system during the work is, and the better the performance of the capacitor is. In addition, based on the concept of forming a large number of micropores by activated carbon and considering the use of an electrolyte, it is obviously necessary to develop a supercapacitor with high capacitance density and high energy density if the effective micropore surface area of the electrode material of the activated carbon of the supercapacitor can be further increased while reducing internal resistance on the basis of forming micropores.
In fact, the performance of the supercapacitor is mainly determined by the transmission channel of electrolyte ions in the pore structure of the supercapacitor system, the effective pore surface and the electronic conductivity. The carbon ring layer-to-layer spacing of common graphite is 0.335nm, while the common supercapacitor organic electrolyte salt currently in question is TEABF4The relative sizes of the anions and cations are different: at TEABF4in/PC, cation (TEA)+) Radius greater than anion (BF)4-): charged ionic groupsHas a particle size of about 0.54nm (TEA)+)、0.48nm(BF4 -) Besides generating high specific surface area by forming micropores (the pore diameter is usually about 1nm when the pores are generated), if the interlayer spacing of graphite can be increased, the available effective pore surface area can be increased by utilizing the gaps among carbon ring layers of the graphite, and the electricity storage capacity of the supercapacitor can be improved; meanwhile, the expansion of the layer spacing can also improve the insertion capacity of electrolyte ions of a super capacitor system between carbon ring layers, provide a better transmission channel for the electrolyte ions, improve the transmission performance of the ions in a pore structure, and reduce the transport resistance of the ions in the system while the electrolyte ions enter to form a double electric layer, thereby increasing the specific capacitance of the super capacitor, reducing the internal resistance and improving the energy density. Therefore, if the problem of improving the graphite interlayer spacing can be directly solved, the preparation of the coconut shell activated carbon with higher energy density is facilitated, and the method has important significance for promoting the large-scale application of the high-performance activated carbon supercapacitor.
As a typical planar lamellar crystal, the layer-to-layer spacing of the carbon rings of the graphite structure is 0.335 nm. All carbon atoms in the carbon ring layer of the graphite layer are sp2Hybridization, covalently bonding adjacent carbon atoms to each other, and in-plane atoms each provide a P orbital electron perpendicular to the plane, forming a large delocalized pi bond. The graphite carbon ring layer has strong bonding force (345kJ/mol) in the layer, and the carbon atoms between the layers are only connected through intermolecular bonding force (Van der Waals bond), so the bonding force is much smaller and is only 16.7 kJ/mol.
As a result of careful analysis, CO is found2The reaction with carbon itself can occur as follows:
C+CO2→2CO (1)
ΔH＝172.459KJ·mol-1
ΔS＝175.868J·mol-1·K-1
ΔG＝ΔH-TΔS
from CO2The reaction equation for the reaction with C is calculated to give a reaction forward progress temperature of at least 708 ℃. In practice, when the temperature is controlled at 700 ℃ and above, the reaction is carried outIt should still be possible, albeit weakly, to proceed in the forward direction. Because the reaction is very weak, the system can be controlled by using the principle without generating violent oxidation action, and only as shown in the above equation, the reaction generates CO or the reaction speed can be adjusted by introducing a trace amount of oxygen according to the requirement so as to control the completion of the reaction; in fact, in the above reaction, a certain amount of carbon vacancies (defects) are formed in the carbon ring layer due to the consumption of carbon atoms during the reaction, and the more consumed carbon atoms and thus the more vacancies are formed in the carbon ring layer as the calcination time is longer. Due to the delocalized, large pi bonds on the graphitic carbon ring layers, the creation of defects may alter the electron cloud density of the delocalized, large pi bonds of the carbon ring layers, thereby altering the van der waals bonds between the carbon ring layers. As the carbon vacancies increase, the van der waals bond ply forces between the carbon layers decrease. That is, van der waals bonding forces between carbon ring layers and layer spacing can be controlled by controlled formation of carbon vacancies in the carbon ring layers. It is therefore possible to further extend the interlayer spacing of graphitic carbon from theoretically 0.335nm for use in supercapacitors with high energy storage performance.
According to the above thought, the present disclosure provides a preparation method for regulating and controlling the layer-to-layer spacing of the carbon surface ring layer by means of off-line treatment of a super-capacitor activated carbon product, that is, a method for directly performing preparation treatment on the prepared activated carbon product. Particularly, the preparation treatment is carried out on the coconut shell raw material active carbon electrode material product, the gas reaction atmosphere, the gas pressure, the reaction time and the temperature are controlled to control the defects generated in the carbon ring layer and the defect quantity, and further the carbon layer delocalized large pi-bond electron cloud density is changed to control the bond strength of van der waals bonds between the carbon ring layers, so that the aim of effectively regulating and controlling the layer-to-layer spacing of the carbon rings is fulfilled. The essence of the control and adjustment of the carbon ring interlayer distance is that the atmosphere composition and the reaction capability of the atmosphere and carbon are comprehensively controlled so as to control the carbon ring layer to only generate vacancy defects without strong integral oxidation reaction; not only ensures that carbon participates in the reaction with the atmosphere, but also does not damage the overall structure of the formed graphite crystal, and achieves the purpose of regulating and controlling the layer-to-layer spacing of the carbon rings. By utilizing the subsequent continuous industrial process preparation method of the electrode material active carbon of the super capacitor, the prepared active carbon with the adjustable carbon layer spacing within the range of 0.384-0.405 nm can be successfully controlled. The maximum increase of the carbon layer spacing is more than 20 percent compared with the graphite theoretical carbon layer spacing of 0.335nm, a channel and an effective specific surface area are provided for the insertion of electrolyte ions between carbon ring layers, and the pores of about 0.5nm and the insertion amount of corresponding ions are greatly increased; meanwhile, the transmission capability of ions in the layer structure is promoted due to the expansion of the interlayer spacing, and the internal resistance is further reduced. The technology successfully solves the problems of low specific capacitance and large internal resistance of the traditional activated carbon super capacitor, and improves the specific capacitance and energy density of the super capacitor. Compared with the prior similar materials which are not subjected to layer expanding treatment, the single electrode specific capacitance of the prepared super capacitor is improved by more than 30 percent at most, and the energy density of the super capacitor can be improved by more than 30 percent at most.
Disclosure of Invention
The invention aims to solve the problem of further improving the performance of an activated carbon supercapacitor electrode material, and provides a method for expanding and preparing the carbon ring layer-to-layer spacing of activated carbon of a supercapacitor electrode material.
The technical scheme adopted by the invention is as follows:
a method for preparing activated carbon of super capacitor electrode material by carbon ring layer-to-layer spacing expansion treatment is characterized in that high-temperature reaction regulation and control treatment is carried out on activated carbon finished product powder prepared by a three-step physical activation process (particularly, CN109592680A), the spacing between activated carbon layers is regulated and controlled by using extremely weak oxidation reaction atmosphere and reaction conditions in a high-temperature atmosphere protective furnace, the spacing between the prepared super capacitor activated carbon layers can be increased from 0.335nm of normal graphite to 0.384-0.405 nm, the super capacitor electrode material is suitable for being used as activated carbon of a super capacitor electrode material, and the prepared super capacitor has high energy density.
The preparation method comprises the following preparation steps:
the method comprises the following steps: will be provided withThe active carbon product powder prepared by adopting the three-step physical activation process is placed in an alumina pot body and is placed in an atmosphere protection high-temperature furnace or a tubular furnace. Then, the filling of nitrogen gas or argon gas is started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the filling gas is kept controlled to be per unit volume (m) of the reaction chamber in the high-temperature furnace3)0.005～0.008m3And/min, and simultaneously heating the mixture from room temperature to 650-850 ℃ at the speed of 9-12 ℃/min. The active carbon finished powder is the finished active carbon powder prepared by the post-treatment processes of acid washing, impurity removal, grinding and the like of the active carbon prepared by the three-step physical activation process.
Step two: when the set reaction temperature is 650-850 ℃, stopping filling the protective atmosphere of nitrogen or argon, and changing to filling pure CO2Taking the gas as a reaction atmosphere, and keeping the temperature at 650-850 ℃ for 2-7 h. Wherein the flow rate of the reaction gas is controlled to be 0.01-0.025 m3/min (per kilogram of material).
Step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into nitrogen or argon protective atmosphere, and controlling the flow rate of the filling gas in the high-temperature furnace per unit volume (m) of the reaction chamber3)0.002～0.004m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
The interlayer spacing of the wide interlayer spacing activated carbon carbocycle prepared by the method can be regulated and controlled between 0.384-0.405 nm, the specific capacitance of a single electrode of the super capacitor prepared by using the wide interlayer spacing activated carbon carbocycle as an electrode material can reach 106.4-146.7F/g, and the energy density of the super capacitor is 26.85-37.13 Wh/kg.
Compared with the background art, the invention has the beneficial effects that:
the method is simple and novel, and can be used for widening the preparation of the supercapacitor electrode material active carbon with wider carbon ring layer-to-layer spacing than graphite. The method can directly carry out off-line post-treatment on the finished powder of the activated carbon produced industrially, and effectively regulate and control the layer-to-layer spacing of the carbon rings. The method provides the opportunity of preparing the high-performance supercapacitor activated carbon material by later-stage modification for the reason that the high-performance activated carbon cannot be directly prepared on line, the layer-to-layer spacing range of the carbon rings can be effectively regulated and controlled to be 0.384-0.405 nm, and the carbon layer spacing is maximally increased by more than 20% compared with the graphite theoretical carbon layer spacing of 0.335 nm. The technology provides an opportunity for improving the energy storage density of the super capacitor, provides a channel for the insertion of electrolyte ions of the super capacitor between carbon ring layers, promotes the rapid transmission of the ions in a pore structure, increases the effective specific surface area, reduces the internal resistance, and greatly improves the specific capacitance and the energy density of the super capacitor. The specific capacitance of the single electrode of the super capacitor prepared by the method reaches 106.4-146.7F/g, and the energy density of the super capacitor is 26.75-37.04 Wh/kg. Compared with the best similar material without layer expanding treatment, the single electrode specific capacitance of the prepared super capacitor is improved by more than 30 percent at most, and the energy density of the super capacitor can be improved by more than 30 percent at most.
The method has the advantages of simple process, short experimental period, strong operability and low cost, and can effectively regulate and control the layer-to-layer spacing of the carbon rings of the activated carbon.
Total gas amount unit m in the present invention3The/min kg means the corresponding gas volume introduced per minute per kg of carbonized material.
Drawings
FIG. 1 XRD pattern of large interlayer spacing activated carbon prepared according to example 1
FIG. 2 XRD pattern of large interlayer spacing activated carbon prepared according to example 2
FIG. 3 XRD patterns of large interlayer spacing activated carbon prepared according to example 3
FIG. 4 XRD patterns of large interlayer spacing activated carbon prepared according to example 4
FIG. 5 XRD pattern of large interlayer spacing activated carbon prepared according to example 5
FIG. 6 Ragon graph of large interlayer spacing activated carbon prepared according to example 1
FIG. 7 Ragon graph of large interlayer spacing activated carbon prepared according to example 2
FIG. 8 Ragon plot of large interlayer spacing activated carbon prepared as in example 3
FIG. 9 Ragon plot of large interlayer spacing activated carbon prepared as in example 4
FIG. 10 Ragon plot of large interlayer spacing activated carbon prepared as in example 5
Detailed Description
The technical solution of the present invention is clearly and completely described below. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of protection of the present invention.
Example 1:
the preparation method comprises the following steps:
the method comprises the following steps: putting the activated carbon finished product powder prepared by adopting the three-step physical activation process into an alumina pot body and putting the alumina pot body into an atmosphere protection high-temperature furnace. Then, the argon gas filling was started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the filling gas was kept controlled to a volume (m) per unit reaction chamber in the high-temperature furnace3)0.005m3At the same time, the temperature is increased from room temperature to 650 ℃ at a rate of 9 ℃/min.
Step two: when the set reaction temperature is 650 ℃, the filling of the protective atmosphere argon is stopped, and pure CO is filled instead2The gas is used as reaction atmosphere, and the temperature is kept for 4h at 650 ℃. Wherein the flow rate of the reaction gas was controlled to 0.01m3/min (per kg material).
Step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into argon protective atmosphere, and keeping the flow rate of the filling gas to be controlled in the high-temperature furnace per unit volume (m) of the reaction chamber3)0.002m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
As shown in fig. 1, the finally obtained activated carbon had a diffraction angle of 23.143 ° at the (002) peak position and an interlayer spacing of 0.384nm according to the bragg formula. The specific capacitance of the single electrode of the super capacitor prepared by the method is 106.4F/g; as shown in FIG. 6, the maximum energy density and power density of the prepared super capacitor were 26.75Wh/kg and 8.97kW/kg, respectively.
Example 2:
the preparation method comprises the following steps:
the method comprises the following steps: putting the activated carbon finished product powder prepared by adopting the three-step physical activation process into an alumina pot body and putting the alumina pot body into an atmosphere protection high-temperature furnace. Then, the nitrogen gas charging was started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the charged gas was kept controlled to a volume (m) per unit reaction chamber in the high-temperature furnace3)0.006m3At the same time, the temperature was increased from room temperature to 700 ℃ at a rate of 9.5 ℃/min.
Step two: when the set reaction temperature is 700 ℃, the filling of the protective atmosphere nitrogen is stopped, and pure CO is filled instead2The gas is used as reaction atmosphere, and the temperature is kept for 5h at 700 ℃. Wherein the flow rate of the reaction gas was controlled to 0.014m3Min. (per kg of material).
Step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into nitrogen protective atmosphere, and keeping the flow rate of the filling gas to be controlled in the high-temperature furnace per unit volume (m) of the reaction chamber3)0.002m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
As shown in FIG. 2, the finally obtained activated carbon had a diffraction angle of 22.938 ℃ at the (002) peak position and a layer spacing of 0.387nm according to the Bragg formula. The specific capacitance of the single electrode of the super capacitor prepared by the method is 116.2F/g; as shown in FIG. 7, the maximum energy density and power density of the prepared super capacitor were 29.28Wh/kg and 9.45kW/kg, respectively.
Example 3:
the preparation method comprises the following steps:
the method comprises the following steps: putting the activated carbon finished product powder prepared by adopting the three-step physical activation process into an alumina pot body and putting the alumina pot body into an atmosphere protection high-temperature furnace. Then, the argon gas filling was started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the filling gas was kept controlled to a volume (m) per unit reaction chamber in the high-temperature furnace3)0.006m3A/min, and at the same time 10The temperature is raised from room temperature to 750 ℃ at a speed of 750 ℃ per min.
Step two: when the reaction temperature reaches 750 ℃, the filling of the protective atmosphere argon is stopped, and pure CO is filled instead2The gas is used as reaction atmosphere, and the temperature is kept at 750 ℃ for 7 h. Wherein the flow rate of the reaction gas was controlled to 0.018m3Min. (per kg of material).
Step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into argon protective atmosphere, and keeping the flow rate of the filling gas to be controlled in the high-temperature furnace per unit volume (m) of the reaction chamber3)0.004m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
As shown in FIG. 3, the finally obtained activated carbon had a diffraction angle of 21.934 ℃ at the (002) peak position and an interlayer spacing of 0.405nm according to the Bragg formula. The specific capacitance of the single electrode of the super capacitor prepared by the method is 118.8F/g; as shown in FIG. 8, the maximum energy density and power density of the prepared two-electrode supercapacitor were 29.9Wh/kg and 11.08kW/kg, respectively.
Example 4:
the preparation method comprises the following steps:
the method comprises the following steps: putting the activated carbon finished product powder prepared by adopting the three-step physical activation process into an alumina pot body and putting the alumina pot body into an atmosphere protection high-temperature furnace. Then, the nitrogen gas charging was started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the charged gas was kept controlled to a volume (m) per unit reaction chamber in the high-temperature furnace3)0.008m3At the same time, the temperature is increased from room temperature to 800 ℃ at a speed of 10.5 ℃/min.
Step two: when the reaction temperature reaches 800 ℃, the filling of the protective atmosphere nitrogen is stopped, and pure CO is filled instead2The gas is used as reaction atmosphere, and the temperature is kept at 800 ℃ for 6 h. Wherein the flow rate of the reaction gas was controlled to 0.022m3Min. (per kg of material).
Step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into nitrogen protective atmosphere, and controlling the flow rate of the filling gas in the high-temperature furnace per unit volume of the reaction chamber(m3)0.004m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
As shown in fig. 4, the finally obtained activated carbon had a diffraction angle of 22.035 ° at the (002) peak position and a layer spacing of 0.403nm according to the bragg formula. The specific capacitance of the single electrode of the super capacitor prepared by the method is 147.1F/g; as shown in FIG. 9, the maximum energy density and power density of the prepared two-electrode supercapacitor were 37.04Wh/kg and 10.34kW/kg, respectively.
Example 5:
the preparation method comprises the following steps:
the method comprises the following steps: putting the activated carbon finished product powder prepared by adopting the three-step physical activation process into an alumina pot body and putting the alumina pot body into an atmosphere protection high-temperature furnace. Then, the argon gas filling was started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the filling gas was kept controlled to a volume (m) per unit reaction chamber in the high-temperature furnace3)0.007m3At the same time, the temperature is increased from room temperature to 850 ℃ at a speed of 11 ℃/min.
Step two: when the set reaction temperature is 850 ℃, stopping filling the protective atmosphere argon, and changing to filling pure CO2The gas is used as reaction atmosphere, and the temperature is kept for 5h at 850 ℃. Wherein the flow rate of the reaction gas is controlled to 0.025m3Min. (per kg of material).
Step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into nitrogen protective atmosphere, and keeping the flow rate of the filling gas to be controlled in the high-temperature furnace per unit volume (m) of the reaction chamber3)0.002m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
As shown in FIG. 5, the finally obtained activated carbon had a diffraction angle of 22.322 ℃ at the (002) peak position and an interlayer spacing of 0.398nm according to the Bragg formula. The specific capacitance of the single electrode of the super capacitor prepared by the method is 134.3F/g; as shown in FIG. 10, the maximum energy density and power density of the prepared super capacitor are 33.87Wh/kg and 10.95kW/kg respectively.
The invention can prepare wide interlayer spacing active carbon for a super capacitor electrode material with higher energy density, has low cost and convenient treatment, effectively regulates and controls the interlayer spacing of carbon rings of the active carbon to be between 0.384 and 0.405nm by comprehensively controlling the atmosphere composition and the reaction capability of the atmosphere and carbon in an atmosphere protection high-temperature furnace, particularly controlling the gas reaction atmosphere, the gas pressure, the reaction time and the temperature, provides a channel for the insertion of electrolyte ions between the carbon ring layers, greatly increases the insertion amount of ions about 0.5nm, promotes the transmission of the ions in a pore structure, reduces the internal resistance and improves the specific capacitance and the energy density of the super capacitor. The problems of low specific capacitance and high internal resistance of the traditional super capacitor are successfully solved. The specific capacitance of the single electrode of the super capacitor prepared by the electrode reaches 106.4-146.7F/g, and the energy density of the double-electrode capacitor is 26.75-37.04 Wh/kg. Compared with the best activated carbon product for the electrode material of the same type of supercapacitor sold in the market at present, the specific capacitance and the energy density of the supercapacitor prepared by the product after the technology is subjected to layer expansion are both higher than those of the supercapacitor prepared by the existing activated carbon which is not subjected to layer expansion in the market, and obviously, the technology is expected to be widely applied to the preparation of the electrode material of the supercapacitor with higher performance.
Claims (5)
1. A method for preparing super-capacitor electrode material active carbon by carbon ring layer-to-layer spacing expansion treatment is characterized in that finished product powder of the active carbon prepared by a three-step physical activation process is subjected to high-temperature reaction regulation and control treatment, and vacancy defects are formed in a carbon ring layer and the number of the defects is controlled by controlling reaction atmosphere, air pressure, reaction time and reaction temperature, so that van der Waals bonds between carbon layers are controlled to regulate and control the spacing of the expanded carbon layers, and the layer-to-layer spacing of the prepared active carbon rings is 0.384-0.405 nm.
2. The method for preparing activated carbon ring of supercapacitor electrode material according to claim 1, wherein the reaction gas and carbon are controlled not to undergo severe oxidation during the process, but carbon vacancy defects are formed in the carbon ring layer, and the severe oxidation is stronger than the reaction of water vapor and carbon.
3. The preparation method of the super-capacitor electrode material activated carbon by adopting the carbon ring layer-to-layer spacing expansion treatment as claimed in claim 1, wherein the high-temperature reaction regulation and control treatment comprises the following steps:
the method comprises the following steps: putting the finished powder of the activated carbon prepared by the three-step physical activation process into an alumina pot body, and putting the alumina pot body into an atmosphere protection high-temperature furnace or a tubular furnace. Then, the filling of nitrogen gas or argon gas is started to exhaust the oxygen atmosphere in the furnace, wherein the flow rate of the filling gas is kept controlled to be per unit volume (m) of the reaction chamber in the high-temperature furnace3)0.005～0.008m3Heating the mixture to 650-850 ℃ from room temperature at a speed of 9-12 ℃/min;
step two: when the set reaction temperature is 650-850 ℃, stopping filling the protective atmosphere of nitrogen or argon, and changing to filling pure CO2Taking the gas as a reaction atmosphere, and preserving the heat for 2-7 h at the temperature of 650-850 ℃; wherein the flow rate of the reaction gas is controlled to 0.01 to 0.025m3Min. (per kg material);
step three: after the reaction is finished, pure CO is added2Changing the reaction atmosphere into nitrogen or argon protective atmosphere, and controlling the flow rate of the filling gas in the high-temperature furnace per unit volume (m) of the reaction chamber3)0.002～0.004m3And/min, cooling to room temperature along with the furnace, and then stopping filling the protective atmosphere to obtain the high-performance activated carbon powder with the wide interlayer spacing.
4. The method for preparing activated carbon ring-layer spacing expansion of supercapacitor electrode material according to claim 3, wherein the finished powder of activated carbon is prepared by performing a three-step physical activation process on activated carbon, and performing acid washing, impurity removal, grinding and other treatment processes on the activated carbon.
5. The method for preparing the activated carbon ring of the supercapacitor electrode material according to claim 3, wherein the supercapacitor prepared from the activated carbon prepared by the method has a single-electrode specific capacitance of 106.4-146.7F/g and an energy density of 26.75-37.04 Wh/kg.
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| CN109592681A (en) * | 2019-01-25 | 2019-04-09 | 浙江大学 | A kind of preparation of industrialization of coconut husk super capacitor highly pure active charcoal purification process step by step |
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