Bamboo fiber-assisted coal pitch-based capacitor carbon material and preparation method thereof
By using bamboo fiber and coal asphalt to prepare capacitive carbon materials with high specific surface area and porous structures, the problem of double layer electrode materials relying on imported materials in the prior art is solved, and high-performance and low-cost supercapacitor electrode materials are achieved, with broad market application potential.
Patent Information
- Application Number
- CN202510248873.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-05-30
AI Technical Summary
In existing supercapacitors, the double-layer electrode materials mainly rely on imported activated carbon and carbon black, which leads to difficult domestic and large-scale production, high material cost, and insufficient specific surface area and pore structure of biomass-derived carbon materials, resulting in low capacitance performance.
Using low-priced bamboo fiber and coal asphalt as carbon sources, soft and hard carbon composite capacitive carbon material with high specific surface area and porous structure is prepared for electrode materials for electric double layer supercapacitors through pre-carbonization and activation treatment.
It has achieved high specific capacity and good cycle stability of capacitive carbon materials, overcomes the problem of fast attenuation of domestic activated carbon materials, has the advantages of high added value and large-scale production, and can replace imported activated carbon materials and reduce the production cost of supercapacitors.
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Figure CN120072533A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of new energy material preparation, and relates to the preparation of electrodes for electric double layer supercapacitors. Background Art
[0002] The depletion of fossil fuels and the corresponding environmental problems have stimulated the vigorous development of sustainable and high-performance energy storage technologies to meet global energy demands. In the field of energy storage, supercapacitors have great application prospects in portable devices, stationary energy storage systems, and electric vehicles due to their advantages such as high specific power, long cycle life, and ultra-fast charge and discharge (within seconds).
[0003] The supercapacitor has a relatively strong dependence on imported materials. For example, the main materials for electric double layer electrodes are activated carbon and carbon black. Activated carbon provides the energy storage capacity for the capacitor, and carbon black is the conductive network of the capacitor. 80% of the activated carbon electrode materials for supercapacitors in China come from Kuraray Company in Japan, 50% of the carbon black materials are imported from Japan, and 50% rely on domestic production. The localization and large-scale production of raw materials will provide at least a 20% cost reduction space for supercapacitors.
[0004] The electrode accounts for a relatively high proportion in the material cost of supercapacitors, exceeding 30%, and is the core for preparing high-performance supercapacitors. Among all electrode materials, carbon materials have attracted much attention due to their unique properties such as functional surfaces, high cost performance, excellent electronic conductivity, and excellent cycle stability. Nevertheless, the extensive development of functional carbonaceous materials is limited by the corresponding fossil fuel-based precursors (such as coal, coal cinder, and pitch), poor rate capabilities, and complex and energy-intensive synthesis processes. At the same time, biomass and its waste are relatively abundant, and the methods for preparing carbon materials from them have also received increasing attention and can be used for large-scale production. However, the main disadvantage of biomass-derived carbon materials is the structure and size of the biomass species themselves, with a relatively small specific surface area and less abundant pores, resulting in low bulk density and specific capacitance. Therefore, it is necessary to further design and adjust the pore structure of its specific surface area.
[0005] The present invention uses inexpensive bamboo fiber and coal tar pitch as carbon sources to obtain capacitive carbon materials composed of hard and soft carbon composites with a high surface area and porous structure, which have characteristics such as high added value and high charge storage capacity. When applied as electrode materials for electric double layer supercapacitors, they can achieve rapid mass and charge transfer, exhibit high specific capacitance and good cycle stability, and overcome the problem of rapid performance decay of domestic activated carbon materials. At the same time, the material preparation process is simple, can be produced on a large scale, has great potential to become an alternative product to imported activated carbon materials, effectively reduce the cost of the supercapacitor industry, and open up huge market opportunities for supercapacitors. Summary of the Invention
[0006] An object of an embodiment of the present invention is to provide a bamboo fiber-assisted coal tar pitch-based capacitive carbon material and a preparation method thereof. The obtained capacitive carbon material can achieve a high specific capacitance and good cycle stability when applied to an aqueous 6 M KOH electrolyte and an ionic liquid EMIMBF 4 electrolyte.
[0007] To achieve the above object, the present invention provides the following technical solutions:
[0008] A bamboo fiber-assisted coal tar pitch-based capacitive carbon material and a preparation method thereof, comprising the following steps:
[0009] (1) Dispersing bamboo fibers and coal tar pitch powder into an organic solvent, drying after mixing evenly, and transferring to a porcelain boat.
[0010] (2) Under the protection of an inert atmosphere, heating the mixture at a heating rate of 5 °C / min and keeping it at 200-400 °C for 2 h for pre-carbonization.
[0011] (3) After thoroughly grinding and mixing the obtained pre-carbonized solid with an activator, transferring to a porcelain boat. Under the protection of an inert atmosphere, heating at a heating rate of 5 °C / min and keeping it at 650-950 °C for 2 h for carbonization and activation.
[0012] The mass ratio of the pre-carbonized material to the activator is 1:3.
[0013] (4) Soaking the obtained carbonized solid in a 2 M dilute hydrochloric acid solution, stirring for 6 h for sufficient pickling, and then repeatedly rinsing with deionized water and drying to obtain the capacitive carbon material.
[0014] Specifically, in step (1), the mass ratio of the bamboo fibers to the coal tar pitch is 1:(0.3-3), preferably 1:1; the organic solvent is one of toluene, xylene, and acetone, preferably toluene.
[0015] Specifically, in step (2), the pre-carbonization temperature is 200-400 °C, and the inert gas is at least one of nitrogen and argon.
[0016] Specifically, in step (3), the activator is one of KOH, NaOH, ZnCI 2 , NaCl, preferably KOH; the carbonization temperature is 650-950 °C, preferably 750 °C.
[0017] The present invention has the following excellent effects:
[0018] The capacitive carbon material prepared by the present invention through bamboo fiber-assisted coal tar pitch has 2270.87 m 2The large specific surface area and abundant pore structure of / g, while the specific surface area of the capacitive carbon material derived from coal tar pitch is 1682.20 m 2 / g, and the specific surface area of the capacitive carbon material derived from bamboo fiber is 1348.60 m 2 / g. The significantly increased specific surface area provides more active adsorption sites, greatly improving its capacitive performance. When the capacitive carbon material prepared in this invention is used as the electrode of a symmetric supercapacitor, it has a high specific capacitance and good cycle stability. In 6 M KOH electrolyte, it shows a capacitance of 344 F@1 A g -1 ; in the ionic liquid EMIMBF 4 electrolyte, it shows a capacitance of 214 F@1 A g -1 ; when the power density is 2000 Wkg -1 , the energy density reaches 118.89 Wh kg -1 ; when the power density is 20000 Wkg -1 , the energy density reaches 77.78 Wh kg -1 . BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 are the X-ray diffraction (XRD) patterns and Raman patterns of the capacitive carbon materials obtained in Examples 1, 2, 3, 4, and 5.
[0020] Figure 2 are the scanning electron microscopy (SEM) images of the capacitive carbon materials obtained in Examples 1, 2, 3, 4, and 5.
[0021] Figure 3 are the N 2 adsorption / desorption isotherms and pore size distribution plots of the capacitive carbon materials obtained in Examples 1, 2, 3, 4, and 5.
[0022] Figure 4 are the cyclic voltammograms and galvanostatic charge / discharge curves of the electrodes of the capacitive carbon materials obtained in Application Examples 1, 2, 3, 4, and 5 in 6 M KOH electrolyte.
[0023] Figure 5 are the cyclic voltammograms and galvanostatic charge / discharge curves of the button cells assembled with the capacitive carbon materials obtained in Application Examples 6, 7, 8, 9, and 10. DETAILED DESCRIPTION OF THE INVENTION
[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0025] An embodiment of the present invention discloses a bamboo fiber-assisted coal tar pitch-based capacitive carbon material and a preparation method thereof.
[0026] To better understand the present invention, the following embodiments are used to further specifically illustrate the present invention, but it should not be construed as a limitation of the present invention. For those skilled in the art, some non-essential improvements and adjustments made based on the above-mentioned invention content are also considered to fall within the protection scope of the present invention.
[0027] Next, the technical solutions of the present invention will be further described in conjunction with specific embodiments.
[0028] Example 1
[0029] (1) Take 2 g of bamboo fiber and 6 g of coal tar pitch powder, disperse them in toluene solution, stir well and then dry, and transfer to a porcelain boat.
[0030] (2) Place the above materials in a muffle furnace, heat them to 350 °C at a heating rate of 5 °C / min under an argon atmosphere, and keep for 2 h for pre-carbonization.
[0031] (3) Take 1 g of the pre-carbonized material and 3 g of KOH powder, grind them repeatedly in a mortar until evenly mixed, and transfer to a porcelain boat; heat to 750 °C at a heating rate of 5 °C / min under an argon atmosphere, and keep for 2 h for carbonization.
[0032] (4) Immerse the obtained carbonized solid in a 2 M dilute hydrochloric acid solution, stir for 6 h for sufficient pickling, then rinse repeatedly with deionized water and dry to obtain the capacitive carbon material.
[0033] Example 2
[0034] The rest is the same as in Example 1, except that in step (1), the masses of both the bamboo fiber and the coal tar pitch are 4 g.
[0035] Example 3
[0036] The rest is the same as in Example 1, except that in step (1), the masses of the bamboo fiber and the coal tar pitch are 6 g and 2 g respectively.
[0037] Example 4
[0038] The rest is the same as in Example 1, except that in step (1), the precursor only contains bamboo fibers with a mass of 8 g.
[0039] Example 5
[0040] The rest is the same as in Example 1, except that in step (1), the precursor only contains coal tar pitch with a mass of 8 g.
[0041] Application Example 1
[0042] The capacitive carbon material prepared in Example 1 was used to prepare a supercapacitor electrode. The specific method was as follows: carbon black, binder PTFE, and capacitive carbon material were dispersed in absolute ethanol to form a slurry (mass ratio 1:1:8), and ultrasonicated for 3 min to completely disperse them, and then placed in an oven at 60 °C to dry. The dried solid was pressed into tablets and cut into circular electrodes with a diameter of 10 mm, and the loading amount of a single electrode was 1 - 4 mg / cm 2 , and it was sandwiched between two pieces of nickel foam in a sandwich style and pressed for 10 s under a pressure of 12 MPa. In a three - electrode system, the electrolyte solution was 6 M KOH solution, the reference electrode was a mercury / mercuric oxide electrode, the counter electrode was a platinum sheet electrode, the voltage window was -1 to 0 V, and the current density was 1 A g -1 , and the electrochemical performance of the above single electrode was tested.
[0043] Application Example 2
[0044] The rest is the same as in Application Example 1, except that the capacitive carbon material prepared in Example 2 was used to prepare the supercapacitor electrode.
[0045] Application Example 3
[0046] The rest is the same as in Application Example 1, except that the capacitive carbon material prepared in Example 3 was used to prepare the supercapacitor electrode.
[0047] Application Example 4
[0048] The rest is the same as in Application Example 1, except that the capacitive carbon material prepared in Example 4 was used to prepare the supercapacitor electrode.
[0049] Application Example 5
[0050] The rest is the same as in Application Example 1, except that the capacitive carbon material prepared in Example 5 was used to prepare the supercapacitor electrode.
[0051] Application Example 6
[0052] The rest is the same as in Application Example 1, except that the prepared electrode material is assembled into a button-type supercapacitor. The specific method is as follows: In a Braun inert gas glove box under an argon atmosphere, assemble in the order of the positive electrode case, current collector, electrode sheet, glass fiber separator, electrolyte, negative electrode sheet, current collector, gasket, spring piece, and negative electrode case in sequence and seal with a sealer. The electrolyte uses EMIMBF 4 , and the current collector is nickel foam, and the assembly is completed.
[0053] Using a Chenhua electrochemical workstation, with a working voltage window of 0 - 4 V and a current density of 1 A g -1 , perform electrochemical performance testing on the above battery
[0054] Application Example 7
[0055] The rest is the same as in Application Example 4, except that the supercapacitor electrode is prepared using the capacitive carbon material obtained in Example 2.
[0056] Application Example 8
[0057] The rest is the same as in Application Example 4, except that the supercapacitor electrode is prepared using the capacitive carbon material obtained in Example 3.
[0058] Application Example 9
[0059] The rest is the same as in Application Example 4, except that the supercapacitor electrode is prepared using the capacitive carbon material obtained in Example 4.
[0060] Application Example 10
[0061] The rest is the same as in Application Example 4, except that the supercapacitor electrode is prepared using the capacitive carbon material obtained in Example 5.
[0062] Figure 1 are the X-ray diffraction patterns of the capacitive carbon materials obtained in Examples 1, 2, 3, 4, and 5. The XRD patterns all show peaks near 23° and 43°, representing the (002) and (100) diffraction peaks of carbon. The relatively broad peaks indicate the amorphous structure of the material, and the high intensity of the low-angle scattering indicates that the prepared capacitive carbon material has a highly developed nanoporous structure. The Raman spectrum shows two broad and overlapping peaks at 1341 cm −1 and 1580 cm −1 , corresponding to the D band (disordered and defective structure) and G band (graphite structure) of the carbon material respectively. The higher I D / I G value indicates the disordered graphite structure of the formed carbon material. After adding pitch, the graphitization degree of the obtained carbon material is improved compared to the biomass carbon, (I D / I GThe value decreases), indicating that a long-range ordered structure is introduced into the biomass-based framework, thereby increasing the graphitization degree of the co-converted carbon.
[0063] Figure 2 Scanning electron microscope (SEM) images of the capacitive carbon materials obtained in Examples 1, 2, 3, 4, and 5. (a) For Example 1, the surface of the carbon material derived from the precursor with a mass ratio of coal tar pitch to bamboo fiber of 1:1 is rough, with a large number of wrinkles, which can provide a large number of active sites. (b) For Example 2, the surface of the co-converted carbon material with a mass ratio of bamboo fiber to coal tar pitch of 1:3 is smooth, showing the characteristics of biomass-based carbon materials. (c) For Example 3, the surface of the carbon material derived from the precursor with a mass ratio of coal tar pitch to bamboo fiber of 3:1 is relatively smooth, with pores etched by the activator. (d) For Example 4, the surface of the carbon material derived from bamboo fiber is smooth. (e) For Example 5, the surface of the carbon material derived from coal tar pitch is rough, with fewer pore structures.
[0064] Figure 3 N 2 adsorption / desorption curves and pore size distribution diagrams of the capacitive carbon materials obtained in Examples 1, 2, 3, 4, and 5. The capacitive carbon materials prepared by the present invention through the assistance of bamboo fiber and coal tar pitch have a large specific surface area of 2270.87 m 2 / g and a rich pore structure. The specific surface area of the capacitive carbon material in Example 2 is 1682.20 m 2 / g, the specific surface area of the capacitive carbon material in Example 3 is 1348.60 m 2 / g, the specific surface area of the capacitive carbon material in Example 4 is 1735.38 m 2 / g, and the specific surface area of the capacitive carbon material in Example 5 is 1538.94 m 2 / g. The significantly increased specific surface area provides more active adsorption sites, greatly improving its capacitive performance.
[0065] Figure 4 Cyclic voltammetry curves and galvanostatic charge-discharge curves of the electrodes of the capacitive carbon materials obtained in Application Examples 1, 2, 3, 4, and 5 in 6 M KOH electrolyte. It can be seen that at a scanning rate of 50 mV / s, the cyclic voltammetry curves are all rectangular in shape. The rectangular area of the cyclic voltammetry curve of the electrode material in Application Example 1 is the largest, and the galvanostatic charge-discharge curve shows a symmetric triangle, indicating that the electrode material in Application Example 1 has the highest specific capacitance and good reversibility. When the capacitive carbon material prepared by the present invention is used as the electrode of a symmetric supercapacitor, it has a high specific capacitance and good cyclic stability. In 6 M KOH electrolyte, Application Example 1 shows a specific capacitance of 344 F@1 A g -1 .
[0066] Figure 5Cyclic voltammetry curves and galvanostatic charge-discharge curves of button batteries assembled with the capacitive carbon materials obtained in Application Examples 6, 7, 8, 9, and 10. It can be seen that at a scanning rate of 50 mV / s, the area of the cyclic voltammetry curve of the supercapacitor in Application Example 6 is the largest, and the galvanostatic charge-discharge curve has a longer discharge time, indicating that it has a higher specific capacitance. In the ionic liquid EMIMBF 4 electrolyte, Application Example 6 shows a capacity of 214 F@1 A g -1 . When the power density is 2000 Wkg -1 , the energy density reaches 118.89 Wh kg -1 . When the power density is 20000 Wkg -1 , the energy density reaches 77.78 Wh kg -1 .
[0067] In summary, the present invention uses inexpensive bamboo fiber and coal tar pitch as carbon sources to obtain a capacitive carbon material composed of hard and soft carbon with a high surface area and porous structure, which has the characteristics of high added value and high charge storage capacity. When applied as the electrode material of an electric double-layer supercapacitor, it exhibits a high specific capacitance and good cyclic stability, and can overcome the problem of rapid performance decay of domestic activated carbon. The raw materials involved are rich in source, low in price, and strong in operability, can be prepared on a large scale, and have great potential to become an alternative product to imported activated carbon materials, effectively reducing the cost of the supercapacitor industry, having good market application potential and economic benefits, and opening up huge market opportunities for supercapacitors.
[0068] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered by the protection scope of the present invention. Those skilled in the art should understand that any improvement to the present invention, equivalent substitution of the raw materials selected by the present invention, and substitution and selection of auxiliary components, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A bamboo fiber-assisted coal tar pitch-based capacitor carbon material and a preparation method, characterized in that: The steps include: (1) Dispersing bamboo fiber and coal tar powder in an organic solvent, mixing them evenly and then drying them; The mass ratio of the bamboo fiber to the coal tar is 1:(0.3-3); (2) Pre-carbonizing the mixture at 200-400 °C for 1-3 h at a heating rate of 5 °C / min under an inert atmosphere; (3) After the obtained pre-carbonized solid and the activator are fully ground and mixed evenly, they are heated at 650-950°C for 1-3 h at a heating rate of 5°C / min under inert atmosphere for carbonization and activation; The mass ratio of the pre-carbonized material to the activator is 1:3; (4) The obtained carbonized solid is immersed in a 2 M dilute hydrochloric acid solution and stirred for 6 h for thorough acid washing, and then repeatedly rinsed with deionized water and dried to obtain a capacitive carbon material.
2. The bamboo fiber-assisted coal tar pitch-based capacitor carbon material and preparation method according to claim 1, characterized in that: The organic solvent is one of toluene, xylene and acetone.
3. The bamboo fiber-assisted coal tar pitch-based capacitor carbon material and preparation method according to claim 1, characterized in that: The gas used in the inert atmosphere is one of nitrogen and argon.
4. The bamboo fiber-assisted coal tar pitch-based capacitor carbon material and preparation method according to claim 1, characterized in that: The activator is one of KOH, NaOH, ZnCl2 and NaCl.
5. A bamboo fiber-assisted coal tar pitch-based capacitor carbon material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.
6. The use of a bamboo fiber-assisted coal tar pitch-based capacitor carbon material according to claim 5, characterized in that: The capacitive carbon material is applied to supercapacitor electrodes.
7. The use of a bamboo fiber-assisted coal tar pitch-based capacitor carbon material according to claim 6, characterized in that: The specific electrode preparation process is as follows: (1) Disperse carbon black, binder PDEF, and capacitor carbon material in anhydrous ethanol at a mass ratio of 1:1:8, perform ultrasonication to completely disperse them, and dry them; (2) Cut the dried solid tablets into discs to serve as supercapacitor electrodes; the average mass of the electrodes is 2-3 mg / cm 2 .